Keywords: History
Probing “Selfish” Centromeres Unveils an Evolutionary Arms Race
24935M. Lampson, The Scientist, 2023-04-03 10:08:47.
The so-called Robertsonian (Rb) fusions that led to these rapid karyotype changes are relatively common chromosomal rearrangements. But their accumulation in the populations of Madeira Island and in multiple other isolated mouse populations elsewhere is likely due to another influencing factor: the preferential segregation of the Rb fusion into the egg rather than into the discarded polar bodies that form during female meiosis. We usually think of the chromosome segregation machinery as ensuring unbiased, random segregation. As we learn in high school biology, if a diploid individual carries two different alleles of a gene (i.e., is heterozygous), then either allele is equally likely to end up in a haploid gamete. This law explains the 3:1 ratio of phenotypes that Mendel observed in his classic studies of heredity. Scientists have known for decades, however, that selfish genes can subvert Mendelian segregation to increase their frequency in the next generation, a phenomenon known as meiotic drive. The Madeira mice suggest that fusion chromosomes can also drive unequal inheritance.
Driving lessons: a brief (personal) history of centromere drive
24030H. S. Malik, Genetics, 2022-11-15 09:41:41.
Meiosis is an important specialized cell division in many eukaryotic species, including fungi, plants, and animals. Meiosis results in the production of haploid gametes starting from a diploid cell via 1 round of replication and 2 rounds of cell division. In an influential article published in 1957, Sandler and Novitski first pointed out that meiosis is also an intense battleground, in which gametes vie for evolutionary supremacy with each other, often poisoning their competition to gain a fratricidal advantage (Sandler and Novitski 1957). This competition, which they termed “meiotic drive,” operates as an evolutionary force that can cause an increase in frequency of the allele that is favored during meiotic transmission. Unlike alleles that rise in frequency because they confer a fitness advantage to their carriers, meiotic drivers can rise in frequency even while conferring significant fitness disadvantages on their carriers. Thus, meiotic drivers can be viewed as the quintessential selfish genes; it is the best interest of the rest of the genome to counteract their action to restore organismal fitness.
Mendel’s laws of heredity on his 200th birthday: What have we learned by considering exceptions?
23269J. B. Wolf, A. C. Ferguson-Smith and A. Lorenz, Heredity, 129:1-3. 2022-07-01 07:36:08.
Violations of Mendel’s laws can generically be referred to as ‘non-Mendelian inheritance’. However, from that broad perspective, nearly all inheritance systems would show non-Mendelian inheritance (at least to some degree). To hold exactly, Mendel’s laws impose strict requirements: a locus has to contain two allelic variants that have discrete effects on categorical (or at least discrete and countable) traits, and they must show complete dominance. These strict conditions are rarely met in real systems (Hou et al. 2016), both because allelic effects do not adhere to the strict law of dominance and because many traits of interest show continuous variation. Mendel recognised many of the exceptions related to effects of alleles, such as the presence of incomplete dominance, pleiotropy, and epistasis (see Fairbanks 2022, this volume), and Fisher (1918) reconciled the assumption of Mendelian inheritance with continuous variation. Hence, from this perspective, a large array of scenarios that show nonMendelian inheritance are actually consistent with the conceptual foundation of Mendel’s perspective based on elemental inheritance
The fight against malaria
22445F. Ammache, Year 2049, 2022-05-06 08:51:20.
Malaria is a disease we’ve been dealing with for thousands of years. Traces of the malaria parasite have been found in the remains of Egyptian mummies. Hippocrates described the fevers caused by malaria in Ancient Greece. The mosquito-filled Pontine Marshes protected Ancient Rome from invaders. Back then, we thought the disease was caused by people breathing “bad air”, or “mal aria”. The relationship between mosquitoes and malaria was unknown. Plasmodium falciparum, the deadliest form of malaria, was introduced by a new breed of mosquitoes around the 5th century. Some historians speculate that P. falciparum played a key role in the fall of the Roman Empire. It wasn’t until 1897 that we understood that mosquitoes transmitted malaria. Sir Ronald Ross, a British doctor based in India, found the malaria parasite in the blood of Anopheles mosquitoes which proved a hypothesis that was first put forward by his predecessor Alphonse Laveran.
New weapons to fight malaria transmission: A historical view
22487W. Huang, S.-J. Cha and M. Jacobs-Lorena, Entomological Research, 2022-05-02 07:19:32.
The stagnation of our fight against malaria in recent years, mainly due to the development of mosquito insecticide resistance, argues for the urgent development of new weapons. The dramatic evolution of molecular tools in the last few decades led to a better understanding of parasite?mosquito interactions and coalesced in the development of novel tools namely, mosquito transgenesis and paratransgenesis. Here we provide a historical view of the development of these new tools and point to some remaining challenges for their implementation in the field.
Genetic Control in Historical Perspective: The Legacy of India’s Genetic Control of Mosquitoes Unit
19652R. Wilbanks, Hastings Center Report, 51:S11-S18. 2021-12-14 18:54:15.
Abstract In the early 1970s, a World Health Organization-initiated and United States-funded project released lab-reared mosquitoes outside New Delhi in the first large-scale field trials of the genetic control of mosquitoes. Despite partnering with the Indian Council of Medical Research and investing significantly in outreach to local communities at the release sites, the project was embroiled in controversy and became an object of vehement debate within the Indian parliament and diplomatic contretemps between the United States and India. This early episode of genetic control research demonstrates how a scientific collaboration was entangled in geopolitics and shaped by the legacy of colonialism. This historical case study has implications for public deliberation in the present, pointing to the challenges of shared decision-making in the context of structural inequality, the way that a backdrop of military interest in a technology can impede trust, and the long-term consequences of projects that foster mistrust.
New mosquito control tools are critical
18148L. Braack, Open Access Government, 2021-08-17 17:38:18.
Globally, we are making slow headway in the fight against malaria, but there has been progress, nonetheless. Since 2000, 39 countries and territories have managed to rid themselves of malaria; the most recent is China. Existing tools can achieve local elimination, but the battle is becoming harder and mosquitoes and parasites are able to change their defences, which is why we too have to constantly adapt and respond with better tools and strategies. We should also be on high alert; malaria has been distracting our attention from what will be our next global public health threat: mosquito-borne arboviruses such as Dengue, Chikungunya, Zika, Yellow Fever, West Nile Virus, Usutu, and a host of others few people have heard of. These arboviruses are spreading across the globe, each year more abundant. The mosquitoes that transmit them pose a different set of challenges, as most of them bite by day, with very different breeding habits. We must increase public awareness of the rising threat and invest much greater research effort to find ways to combat these viruses and mosquitoes.
Oxitec and MosquitoMate in the United States: lessons for the future of gene drive mosquito control
17890C. E. Schairer, J. Najera, A. A. James, O. S. Akbari and C. S. Bloss, Pathogens and Global Health, 2021-07-27 12:51:01.
ABSTRACTIn response to growing concerns regarding mosquito-borne diseases, scientists are developing novel systems of vector control. Early examples include Oxitec?s OX513A genetically-engineered mosquito and MosquitoMate?s Wolbachia-infected mosquito, and systems using ?gene-drive? are in development. Systems based on genetic engineering are controversial and institutions around the world are grappling with the question of who should have a say in how such technologies are field-tested and used. Based on media coverage and public records, we created comparative timelines of the efforts of Oxitec and MosquitoMate to navigate federal and local governance and bring their products to market in the United States. We analyze these timelines with particular attention to the role of public input in technology governance. These cases illustrate how governance of technology in the US is diverse, complex, and opaque. Further, the public response to proposed field trials of the Oxitec product highlights inconsistencies between public expectations for governance and actual practice. As gene-drive mosquito control products develop, both federal and local agencies will find their legitimacy tested without a better procedure for transparently integrating public input.
His Passion Was Contagious
15928D. C. McCool, Notre Dame Magazine, 2021-01-01 19:03:35.
Craig was an entomologist and vector biologist whose interest in mosquitoes and the diseases they transmit to people was as contagious as the pathogens themselves. Hesburgh could not have chosen a more driven faculty member. In his 38 years at Notre Dame, before he died in 1995 at an Entomology Society of America conference in Las Vegas, Craig cultivated a legacy in a field that was in its infancy. His personality attracted even more people dedicated to eliminating mosquito-borne diseases, and the circle widened in unexpected ways. The Chicago native directed more than 40 doctoral students and mentored 38 postdoctoral researchers. He created Notre Dame’s Vector Biology Laboratory — vectors pass diseases from one organism to another — with a focus on the Aedes genus of mosquitoes. He became Notre Dame’s first member of the prestigious National Academy of Sciences (NAS). And he developed a program that has turned out hundreds of new field biologists who have gone onto careers in academia and public health.
Teach Me in 10 – Gene Drive Research with Dr. Jennifer Baltzegar
14362J. Baltzegar, Technology Networks, 2020-09-10 15:44:16.
Dr Baltzegar teaches us about how the maturation of genetic engineering approaches has advanced gene drives, the two different strategies for gene drives and some of the key questions surrounding the application of gene drives in society.
America’s Never-Ending Battle Against Flesh-Eating Worms
16665S. Zhang, The Atlantic, 2020-05-26 14:33:06.
The United States Department of Agriculture undertook what would ultimately become an immense, multidecade effort to wipe out the screwworms, first in the U.S. and then in Mexico and Central America—all the way down to the narrow strip of land that is the Isthmus of Panama. The eradication was a resounding success. But the story does not end there. Containing a disease is one thing. Keeping it contained is another thing entirely, as the coronavirus pandemic is now so dramatically demonstrating. To get the screwworms out, the USDA to this day maintains an international screwworm barrier along the Panama-Colombia border. The barrier is an invisible one, and it is kept in place by constant human effort. Every week, planes drop 14.7 million sterilized screwworms over the rainforest that divides the two countries. A screwworm-rearing plant operates 24/7 in Panama. Inspectors cover thousands of square miles by motorcycle, boat, and horseback, searching for stray screwworm infections north of the border. The slightest oversight could undo all the work that came before.
Gene Drives: A scientific case for a complete and perpetual ban
4597Latham, J, GeneWatch, 2017-02-06 00:00:00.
One of the central issues of our day is how to safely manage the outputs of industrial innovation. Novel products incorporating nanotechnology, biotechnology, rare metals, microwaves, novel chemicals, and more, enter the market on a daily basis. Yet none of these products come with an adequate data set of scientific information. Nor do they come with a clear intellectual framework within which their risks can be placed, as disputes over the precautionary principle show. The majority of products receive no regulatory supervision at all. How will the product be disposed of? What populations and which ecosystems will be exposed in the course of its advertised uses? What will be the consequences of accidental, off-label or illegal uses? Typically, none of these kinds of questions are adequately asked by government regulatory agencies unless citizens actively prod them to do so.; ; In consequence of these defects, we expose our world to unique hazards with every product launch. In comparison with its tremendous importance, this is surely one of the least discussed issues of our day.
Sterile Insect Techniques, GE mosquitoes and gene drives
4595Hanson, J, GeneWatch, 2017-02-06 00:00:00.
One of the great temptations in any field is to promote your solution to a problem as the only solution. The recent application of gene drives to sterilize mosquitoes that transmit malaria or viruses like dengue and zika is an example of this tendency to first develop a technology and then look for applications that might justify its use.; ; For at least 70 years, scientists have been trying to sterilize insects to prevent them from spreading disease, especially mosquito-borne diseases like malaria, dengue and zika, an approach known as "sterile insect technique." Sterilizing some insects with irradiation has been successful in preventing their reproduction.[1] In the 1950s, it was used to rid the southeastern U.S. of the New World screwworm Cochliomyia hominivorax (Coquerel), a deadly parasite of livestock. During the next 43 years the technique was used to eradicate this screwworm from the U.S., Mexico, and Central America. Currently, the largest use of Sterile Insect Technique in the U.S. is for the control of Mediterranean fruit fly. Irradiated bollworms are also being released to control cotton boll weevils, and irradiated coddling moths are being released to help protect apples and pears.[2] Interestingly, Rachel Carson, in Silent Spring, warned that using the Sterile Insect Technique to control a population of insects that could rebuild from neighboring islands or other populations was especially challenging. Talking about a SIT effort to control houseflies in the Florida Keys, she wrote:; ; "In a test on an island in the Florida Keys in 1961, a population of flies was nearly wiped out within a period of only five weeks. Repopulation of course followed from nearby islands, but as a pilot project the test was successful....; ; One of the problems of sterilization by radiation is that this requires not only artificial rearing but the release of sterile males in larger number than are present in the wild population. This could be done with the screw-worm, which is actually not an abundant insect. With the housefly, however, more than doubling the population through releases could be highly objectionable [to the local people]."[3]
Gene drive and collective oversight
4594Esvelt, K, GeneWatch, 2017-01-01 00:00:00.
As one of the scientists who first described how CRISPR could create gene drive systems capable of altering wild; populations, I am morally responsible for the consequences. I'm writing to you in the hope that the people most; critical of the very idea can help. Bluntly, gene drive is an example of how the current scientific enterprise causes; our technological power to grow faster than our ability to ensure it is developed wisely. But because it affects the; shared environment, gene drive may also be the key to improving the system - namely, by causing it to favor; collective oversight. And to do that, we need your help.
Concept and history of genetic control
6014Scott, M. J. and Benedict, M. Q., Genetic Control of Malaria and Dengue, 2:31-54. 2016-12-30 20:16:45.
Genetic control of insects is an established method, mainly for insects that are important crop and veterinary pests such as medflies and screwworm. Efforts to use the same technologies against insects of medical importance, especially mosquitoes, have had limited success. The successes against mosquitoes have been accomplished using forms of both conventional and modern methods, both of which are promising. In this chapter, we provide highlights of the development of genetic control of agricultural pests and describe how the development of methods against mosquitoes reflects those advances. While admiring successful genetic control programs is motivating, we suggest that much can also be learned from both past successful and failed efforts, as doing so will increase our ability to improve future activities.
Marcus Rhoades on preferential segregation in maize
4082Birchler, JA, Genetics, 203:1489-1490. 2016-01-20 00:00:00.
Rhoades was studying a variant form of chromosome 10 with a conspicuous abnormality; it carried extensive heterochromatin at the tip of the long arm. This variant had been found by Albert Longley in indigenous maize varieties from the southwestern United States and provided to Rhoades for the pedestrian task of determining the recombination frequency between the anthocyanin pigment gene, R, and the end of the chromosome. The abnormal chromosome 10 originally carried the recessive, r, allele (colorless kernels) and was crossed to other lines carrying the dominant R (red kernels). Much to the surprise of Rhoades, when these heterozygotes were testcrossed with the recessive, there was a strong skew from a 1:1 ratio. Rather than the roughly even mix of colorless and red kernels that he expected, around two-thirds were colorless. This excess of r alleles was caused by linkage to the variant chromosome; in the few progeny that transferred the dominant R allele to the abnormal chromosome 10, subsequent testcrosses demonstrated that it was now the dominant allele that was preferentially inherited.
Selfish genetic elements and the gene’s-eye view of evolution
4078Ågren, JA, Current Zoology, 62:659-665. 2016-01-16 00:00:00.
During the last few decades, we have seen an explosion in the influx of details about the biology of selfish genetic elements. Ever since the early days of the field, the gene’s-eye view of Richard Dawkins, George Williams, and others, has been instrumental to make sense of new empirical observations and to the generation of new hypotheses. However, the close association between selfish genetic elements and the gene’s-eye view has not been without critics and several other conceptual frameworks have been suggested. In particular, proponents of multilevel selection models have used selfish genetic elements to criticize the gene’s-eye view. In this paper, I first trace the intertwined histories of the study of selfish genetic elements and the gene’s-eye view and then discuss how their association holds up when compared with other proposed frameworks. Next, using examples from transposable elements and the major transitions, I argue that different models highlight separate aspects of the evolution of selfish genetic elements and that the productive way forward is to maintain a plurality of perspectives. Finally, I discuss how the empirical study of selfish genetic elements has implications for other conceptual issues associated with the gene’s-eye view, such as agential thinking, adaptationism, and the role of fitness maximizing models in evolution.
History of the Sterile Insect Technique
6360Klassen, W. and C. F. Curtis, Sterile Insect Technique: Principles and Practice in Area-Wide Integrated Pest Managemen, 2005:3-36.. 2005-03-09 20:56:59.
During the 1930s and 1940s the idea of releasing insects of pest species to introduce sterility (sterile insect technique or SIT) into wild populations, and thus control them, was independently conceived in three extremely diverse intellectual environments. The key researchers were A. S. Serebrovskii at Moscow State University, F. L. Vanderplank at a tsetse field research station in rural Tanganyika (now Tanzania), and E. F. Knipling of the United States Department of Agriculture. Serebrovskii’s work on chromosomal translocations for pest population suppression could not succeed in the catastrophic conditions in the USSR during World War II, after which he died. Vanderplank used hybrid sterility to suppress a tsetse population in a large field experiment, but lacked the resources to develop this method further. Knipling and his team exploited H. J. Muller’s discovery that ionizing radiation can induce dominant lethal mutations, and after World War II this approach was applied on an area-wide basis to eradicate the New World screwworm Cochliomyia hominivorax (Coquerel) in the USA, Mexico, and Central America. Since then very effective programmes integrating the SIT have been mounted against tropical fruit flies, some species of tsetse flies Glossina spp., the pink bollworm Pectinophora gossypiella (Saunders), and the codling moth Cydia pomonella (L.). In non-isolated onion fields in the Netherlands, the onion maggot Delia antiqua (Meigen) has since 1981 been suppressed by the SIT. In the 1970s there was much research conducted on mosquito SIT, which then went into “eclipse”, but now appears to be reviving. Development of the SIT for use against the boll weevil Anthonomus grandis grandis Boheman and the gypsy moth Lymantria dispar (L.) has ended, but it is in progress for two sweetpotato weevil species, Cylas formicarius (F.) and Euscepes postfasciatus (Fairmaire), the false codling moth Cryptophlebia leucotreta (Meyrick), the carob moth Ectomyelois ceratoniae (Zeller), the cactus moth Cactoblastis cactorum (Berg), the Old World screwworm Chrysomya bezziana (Villeneuve), additional Glossina spp., other Anastrepha spp. and Bactrocera spp. fruit flies, and other pest insects.
Marcus Rhoades, preferential segregation and meiotic drive
4305Birchler, JAD, R. K.; Doebley, J. F., Genetics, 164:835-841. 2003-01-03 00:00:00.
LONG before microarray biologists coined and promoted the term “discovery science,” maize geneticists were avid practitioners of this mode of investigation. In fact, one might say that for a number of years, the field of maize genetics basically operated as discovery science. Many have speculated about why maize remains a model organism for genetic analysis, given its long life cycle relative to other species. It has many virtues, sometimes little understood or appreciated by outsiders, but the maize geneticist’s style of science devoted to discovery and an unusually strong commitment to cooperation probably contributes to this trend. One of the great practitioners of this style of science was Marcus Rhoades (Figure 1), who often advised beginning graduate students: “Just get in the lab and start to work; you can’t help but find something.” “What are the facts?” was his common refrain to model building and theorizing. Along with his penchant for discovery was a dogged experimentalist attack to explore the parameters and dimensions of a new finding.
Recurrent invasion and extinction of a selfish gene
4353Goddard, MRB, A., Proceedings of the National Academy of Sciences of the United States of America, 96:13880-13885. 1999-01-11 00:00:00.
Homing endonuclease genes show super-Mendelian inheritance, which allows them to spread in populations even when they are of no benefit to the host organism. To test the idea that regular horizontal transmission is necessary for the long-term persistence of these genes, we surveyed 20 species of yeasts for the omega-homing endonuclease gene and associated group I intron. The status of omega could be categorized into three states (functional, nonfunctional, or absent), and status was not clustered on the host phylogeny. Moreover, the phylogeny of w differed significantly from that of the host, strong evidence of horizontal transmission. Further analyses indicate that horizontal transmission is more common than transposition, and that it occurs preferentially between closely related species. Parsimony analysis and coalescent theory suggest that there have been 15 horizontal transmission events in the ancestry of our yeast species, through simulations indicate that this value is probably an underestimate. Overall, the data support a cyclical model of invasion, degeneration, and loss, followed by reinvasion, and each of these transitions is estimated to occur about once every 2 million years. The data are thus consistent with the idea that frequent horizontal transmission is necessary for the long-term persistence of homing endonuclease genes, and further, that this requirement limits these genes to organisms with easily accessible germ lines. The data also show that mitochondrial DNA sequences are transferred intact between yeast species; if other genes do not show such high levels of horizontal transmission, it would be due to lack of selection, rather than lack of opportunity.
Sander,Larry – The father of meiotic drive
4447Lindsley, DL, American Naturalist, 137:283-286. 1991-01-05 00:00:00.
The symposium at which the following papers were presented was deprived of what surely would have been a major intellectual contribution by the sudden death of its co-organizer, Larry Sandler, in February 1987. Larry was a leading contributor to the study of segregation distortion and meiotic drive, beginning with his seminal research as a graduate student with Ed Novitski at the University of Missouri and continuing, in collaboration with Yuichiro Hiraizumi, as a post- doctoral fellow with Jim Crow and as a fledgling faculty member at the University of Wisconsin. Many of us at the conference worked with him personally and benefited from his insights and his enthusiasm for genetic analysis of meiotic problems. We all felt a great sense of loss and missed his lively contributions at the symposium.
Genetics-driving genes and chromosomes
4463Charlesworth, B, Nature, 332:394-395. 1988-01-21 00:00:00.
Thereare several genetic and chromosomal systems in which Mendel's first law - the equal probability of transmission of maternal and paternal alternative alleles or homologues - is violated. This phenomenon was named 'meiotic drive' in 1957 by Sandler and Novitski, who drew attention to the fact that it operates as an evolutionary force which can cause an increase in the population frequency of the allele or chromosome which is favoured in transmission, even if it confers a disadvantage on its carriers in terms of fitness at the level of the individual
Population replacement in Culex fatigens by means of cytoplasmic incompatibility. Laboratory experiments with non-overlapping generations
6291C. F. Curtis and T. Adak, Bulletin of the World Health Organization, 51:249-255. 1974-01-08 19:45:42.
Bidirectional cytoplasmic incompatibility in the Culex pipiens complex appears to provide a mechanism for the replacement of a wild population by a strain refractory to filaria or a strain made partly sterile by a translocation. As a preliminary test of the feasibility of the replacement process, various ratios of strains with the cytoplasm of either Delhi or Paris, which are bidirectionally incompatible, were tested in laboratory cages. Where one strain was marked with the ruby-eye gene, this strain always declined in frequency in the next generation. In experiments in which the Paris strain was marked with a male-linked translocation complex, after 2-4 generations of breeding there was complete elimination of either the Paris or the Delhi type depending, as expected, on the relative frequencies of the two types with which the population began. In one experiment a type with Paris cytoplasm devoid of the translocation was found. This type increased in frequency in succeeding generations. The possible causes of origin of this type and its relevance to the practical use of the replacement principle are discussed.
Genetic control of insect populations: I. Cage studies of chromosome replacement by compound autosomes in Drosophila melanogaste
6297M. Fitz-Earle, D. G. Holm and D. T. Suzuki, Genetics, 74:461-475. 1973-07-08 19:53:27.
A genetic method for insect control was evaluated using the test organism, Drosophila melanogaster. The technique involved the displacement under a system of continuous reproduction, of standard strains by those carrying compound autosomes. The eradication of the replacements could subsequently be achieved through the use of temperature-sensitive lethal mutations.—While certain compound autosome strains failed to displace standards in population cages, even at the initial release ratio of 25:1, others were highly successful. Indeed, for some strains when the ratio of compounds to standards was as low as 9:1, the population rapidly went to fixation in favor of the compound line.—Hatchability was found to be an insufficient index of fitness to estimate the initial ratios of compounds to standards that would guarantee fixation of the former. Differences in other fitness components, such as development time, were detected that could seriously modify displacement, especially with continuous overlapping generations. The importance of examining the fitness of various compound lines and selecting the most competitive in cages, prior to field tests, cannot be overemphasized.
Changing population structure through the use of compound chromosomes
6295D. Childress, Genetics, 72:183-186. 1972-09-08 19:50:49.
Theoretical calculations and population cage data are presented to illustrate the use of compound chromosomes to change the genetic structure of insect populations.
Chromosome rearrangements for the control of insect pests
6293G. G. Foster, M. J. Whitten, T. Prout and R. Gill, Science, 176:875-880. 1972-05-26 19:48:27.
Over several years some biologists have been interested in the possibilities of employing genetic techniques in the control of insect pests. One idea has been to introduce in the natural population genotypes which could subsequently facilitate control, or which might render the pest innocuous. An- other idea that followed from the success of the .'sterile male" technique was to release genotypes with chromosomal aberrations whose subsequent segregation would result in sterility effects damaging to the population. Whitten (I) suggested combining these two ideas in one operation: in its simplest form the desired genotype would be obtained by incorporating the required genes in a chromosomal translocation. This would then be released as a homozygote in excess of the intrinsic unstable equilibrium which would result from the semisterility of the translocation heterozygote. The translocation producing the desired genotype would then autonomously become fixed while the genotype at the same time would produce sterile progeny in the early stages of the process. Thus we have the concept of a genetic transporting mechanism and a desired genotype to be transported, with the additional benefit of a transport device that might itself have transient damaging effects.
Possible use of translocations to fix desirable genes in insect populations.
4503Curtis, CF, Nature, 218:368-369. 1968-01-21 00:00:00.
Chromosome translocation heterozygotes (T/+) are usually semisterile, but translocation homozygotes (T/T) if viable are usually fully fertile. If such a viable translocation were produced in an insect pest, T/T insects could be reared in captivity and released into the wild, where matings with wild types (+/+) would produce T/+ progeny.
Eradication of Culex pipiens fatigans through cytoplasmic incompatibility.
6278H. Laven, Nature, 216:383. 1967-10-28 16:57:49.
Culex pipiens fatigans is the chief vector of filariasis in south-east Asia. Urbanization has often caused the numbers of this mosquito-and with it the danger of filariasis infection-to increase alarmingly. The natural vigour, tolerance and fast development of resistance to insecticides of this mosquito necessitate the development of other control methods, and cytoplasmic incompatibility2 seems to be an ideal means.
Applications of genetic technology to mosquito rearing
6098G. B. Craig, Bulletin of the World Health Organization, 29:89-97. 1963-01-02 16:40:36.
Since the development of insecticide-resistance and the consequent partial failure of the chemical approach to the control of disease vectors, interest in the biological approach has re-awakened. An aspect of the latter approach that is of great current interest is " autocidal control "-that is, the use of insects for their own destruction. This paper discusses the various ways in which genetic mechanisms can be used to bring about the destruction of harmful insects, with special reference to those of medical importance. The author considers that the prospects for the genetic control of vector species are good, but stresses that before genetic methods can be applied on a field scale certain requirements must be met. For example, genetic technology must be expanded, a firm background of genetic knowledge of vector species must be built up, a great deal more information about vector ecology, particularly population dynamics, must be acquired, and techniques for the mass production of vector insects under controlled conditions must be developed.
On the role of lethal mutants in the control of populations
6101R. C. Von Borstel and A. A. Buzzati-Traverso, Radioisotopes and Radiation in Entomology: Proceedings of a Symposium, Bombay, 5-9 December, 1960, 1962:273-278. 1962-01-02 16:52:59.
On the role of lethal. mutants in the control of populations. Population control by release of irradiated males requires that the sperm must be damaged by radiation. The type of damage induced by radiation imposes a restriction on which species may be controlled because if the sperm are functionally damaged by radiation, then for effective control, the females must be monogamous. If dominant lethality is induced in sperm then either polygamy or monogamy may prevail. It is generally accepted that dominant lethal events are induced in sperm at doses much lower than those required to hamper sperm function or cause sperm inactivation. With Drosophila it is possible to test directly the effect of releasing irradiated males into an artificial population where polygamy is the rule. Preliminary experiments have been performed under conditions of unlimited production of offspring. It appears that radiation induces dominant lethality in sperm, and the sperm that bear dominant lethals are able to compete successfully with normal sperm. A series of tests are currently under way to ascertain the degree of induced dominant lethality and sperm inactivation at different X-ray dosages. A series of experiments are outlined in a general discussion of the possible use of dominant and recessive lethals for bringing about collapse of artificial and natural populations.
Inherited male-producing factor in Aedes aegypti
6096G. B. Craig, W. A. Hickey and R. C. Vandehey, Science, 132:1887-1889. 1960-12-23 14:59:02.
An inherited factor causes a predominance of males in certain strains and in progeny of single pairs of Aedes aegypti L. This factor appears to be transmitted only by males and is not due to differential mortality, at least in postgametic stages. Mass release of male-producing males might be used in control operations.
Meiotic drive in natural-populations of Drosophila melanogaster 3: Populational implications of the Segregation-Distorter locus
4513Hiraizumi, YS, L.; Crow, J. E., Evolution, 14:433-444. 1960-01-11 00:00:00.
If, among the successful gametes frm heterozygotes, one allele is regularly included in more than half, it may increase in frequency even if it has a harmful effect. Unequal gamete production, when attributable to the mechanics of meiosis, has been called meiotic drive (Sandler and Novitski, 1957). An example is segregation-distortion in Drosophila melanogaster, the cytogenetic behavior of which has been reported by Sander, Hiraizumi and Sandler (1959) and Sandler and Hiraizumi (1959)
Meiotic drive in natural populations of Drosophila melanogaster .1. The cytogenetic basis of segregation distortion
4517Sandler, LH, Y.; Sandler, I., Genetics, 44:233-250. 1959-01-15 00:00:00.
Meiotic drive has been defined as a force, potentially capable of altering gene frequencies in natural populations, which somehow depends upon the nature of the meiotic divisions; specifically, when the meiotic divisions are such that the two kinds of gametes from a heterozygote are produced in a ratio different from 1 : 1 ( SANDLER and NOVITSKI 195 7). There have been reported numerous cases which either are, or may be, examples of meiotic drive. These include cases in Drosophila ( GERSHENSON 1928; STURTEVANT and DOBZHANSKY 1936; NOVITSKI 1951 ; NOVITSKI and IRIS SANDLER 1957; LINDSLEY and SANDLER 1958), in maize (RHOADES 1942; LONGLEY 1945), in tobacco (CAMERON and MOAV 1957), and possibly in mice (DUNN 1953) and in man (DUNN 1953; SANDLER and NOVITSKI 1957). The purpose of this paper is to present a first account of the results of a series of studies designed to elucidate the cytogenetic basis of a case of meiotic drive which was discovered in a natural population of D. melanogaster. In this population there has been found a second chromosome locus, located in or near the proximal heterochromatin and called segregation-distorter (symbol, SO), which is recovered much more frequently than its normal allele among the progeny of heterozygous male parents. This phenomenon, to which the name segregation distortion has been applied, (1) has never been found to occur in females, (2) apparently requires synapsis (particularly in the region of the locus in question) in order to operate, and (3) comes about as a result of the failure of sperm carrying the normal allele to be formed or to function normally. The evidence bearing on these, and certain other points, and a cytogenetic model to account for the results are presented below.
Possible replacement of malaria mosquitoes
6118S. Avery Jones, Transactions of The Royal Society of Tropical Medicine and Hygiene, 51:469-470. 1957-08-10 19:43:41.
Sir,--The purpose of this letter is to draw the attention of research workers in control of mosquito colonies to the possible value of investigating the factors governing the infection of mosquitoes with parasites of human malaria. If a strain of a vector species could be isolated that has inability to become infective as a dominant characteristic, the way would be opened up to implant such mosquitoes in areas where the normal vectors of the same species have been reduced in numbers. There is the hope that they would breed and become locally predominant.
Meiotic drive as an evolutionary force
4518Sandler, L. and Novitski, E., American Naturalist, 91:105-110. 1957-01-16 00:00:00.
A heterozygote for alleles A and A' ordinarilly produces gametes carrying each of the alleles with a frequency of 50 per cent. The constancy of allele frequencies from one generation to the nest in natural populations of diploid species depends on this equality, which itself depends on the nature of the meiotic divisions. As the study of the genetics of higher organisms becomes more precise and extensive, an increasing number of cases is found in which heterozygotes of certain constitutions fail to produce the two kinds of gametes with equal frequency. Such a pattern of behavior will drastically alter frequencies of alleles in a population; where such a fouce, potentially capable of altering gene frequencies, is a consequence of the mechanics of the meiotic divisions, we suggest that the name meiotic drive be applied. The distinction between meiotic drive and the superficially similar phenomenon of gametic selection and gametic competition may be operationally difficult in those instances in which a detailed cytogenetic study cannot be made. The later, however, represent selecdtion in the ordinary sense, operating in the haploid phase, and as such their effectiveness is directly dependent on the gene content (fitness) of the gametes, whereas the effectiveness of the former is independent of the gene content in the ordinary sense.
Inheritance in Nicotiana tabacum XXVII. Pollen Killer, An alien genetic locus inducing abortion of microspores not carrying it
6116D. R. Cameron and R. M. Moav, Genetics, 42:326. 1957-01-02 19:37:02.
A cytogenetic study of experimental introgression from N. plumbaginifolia (pbg) into N. tabacum (tbc) has been pursued in this laboratory for several years (CLAUSEN 1952). In the hybrid derivatives it was observed that genically controlled pollen abortion was associated with the addition of a pbg chromosome to the tbc complement. This chromosome also carried the locus (Bs) determining resistance or probably immunity to black shank, a serious disease of commercial tobacco caused by Phytophthora parasitica var. nicotianae. (For description see CLAYTON and AICAIVRTRY 1950). Paradoxically, it developed that the pbg chromosome under study produced its effect on gametophytes in which it was not present. Thus, the male gametophytes containing a complete set of 24 tbc chromosomes degenerate while most of the functional pollen had the constitution 24 tbc + 1 pbg. This paper presents a description of the genetic aspects of the problem with some suggestions as to the possible method of action of the locus involved. Certain other phases of the larger investigation will be mentioned but only as they apply to the pollen lethal condition. The investigation was initiated by the late PROF. R. E. CLAUSEN who participated actively in the work presented here.
Studies of the genetic variability in populations of wild house mice .2. Analysis of eight additional alleles at locus – T
6113L. C. Dunn, Genetics, 42:299-311. 1957-01-02 19:27:44.
1 Eight additional lethal alleles at locus T are described, each derived from a wild heterozygote in one of six different wild populations. 2. The frequency of heterozygotes appears to be high in most wild populations, possibly as high as 50 percent. 3. In two of the populations in which several heterozygotes were found, the same allele was isolated from each heterozygote of the same population. One heterozygote was found in each of two subpopulations on the same farm. These two alleles have not been shown to be different. One wild heterozygote from another population transmitted two different alleles; probably one was a new mutant, giving rise to the possibility that more than one allele may occur in the same population, although the rule at present is to find but one type of variant allele per population. 4. All wild t alleles show the “male segregation ratio peculiarity” by which male heterozygotes transmit the t allele to a great majority (about 96 percent) of the offspring. This may be due to the effects of natural selection on factors favoring high transmission ratios. 5. t alleles from the wild fall into at least three groups, one with three viable alleles, and two groups of lethals. Lethals within the same group have not formed viable compounds when combined; lethals belonging to different groups do form viable compounds by complementary interaction and are thus shown to be nonidentical. 6. Since 29 alleles have now been detected at this locus, many of which are nonidentical, the locus is assumed to contain many sites of mutation and to have great potential complexity.
Screw-worm control through release of sterilized flies
6107A. H. Baumhover, A. J. Graham, B. A. Bitter, D. E. Hopkins, W. D. New, F. H. Dudley and R. C. Bushland, Journal of Economic Entomology, 48:462-466. 1955-08-03 17:00:44.
Screw-worms, Callitroga hominivorax (Cqrl.), did not exist in the southeastern United States until about 20 years ago, and it is probable that, if the present infestation could be eradicated, the area might be kept free of infestation through inspection of livestock shipments originating in infested areas
Possibilities of Insect Control or Eradication Through the Use of Sexually Sterile Males
6006E. F. Knipling, Journal of Economic Entomology, 48:459-462. 1955-08-01 19:58:21.
The purpose of this paper is to consider the possibility of controlling insects by releasing sexually sterile males among the existing natural population. The principles involved will be described and the potentialities as well as the limitations of the method as we know them at present, will be discussed.
Eradication of screw-worms through release of sterilized males
6091R. C. Bushland, A. W. Lindquist and E. F. Knipling, Science, 122:287-288. 1955-01-02 14:50:36.
Although the sterilizing effect of ionizing radiations has been known for years, it is only recently that entomologists have attempted to take advantage of the phenomenon for insect control. Knipling (1) has theorized on the effects of releasing sterilized males among a normal insect population. In 1947, on a visit to the Kerrville, Tex., laboratory, he proposed investigations on the mating habits of the screw-worm, Callitroga hominivorax (Cqrl.), and experiments with sterilized males. In such experiments Bushland and Hopkins (2) found that screw-worms were easily sterilized by exposing pupae to x-rays or gamma rays. They showed that under laboratory conditions male screw-worms mated repeatedly but fe males only once. If a female mated with a sterilized male it did not mate again and laid eggs that did not hatch. When mixed populations of normal and sterilized insects were observed in cages, the sterilized and normal males competed about equally for mates.
Mutable loci in maize.
6388B. McClintock, Carnegie Inst. Washington Year Book, 47:155-169. 1948-02-10 16:25:33.
Previous reports have state that the number of unstable loci have recently arisen in maize culture. In a particular cell of a plant, a normal "wild-type" locus becomes altered; the normal, dominant expression of this locus changes and gives rise to a recessive expression (or, in several cases, a recessive locus become unstable and mutates toward a dominant expression). This expression of the locus need not be permanent. In some decendent cells, a second change may occur within the locus that results in the restoring of the capacity of thelocus to express the dominant phenotype or brings about an intermediate expression between full recessive and full dominant. In the latter case, a third alteration may occur in some decendent cells that steps up the phenotype expression toward the full dominant or reduces it toward the full recessive.
Experiments in the hybridisation of tsetse-flies (Glossina, Diptera) and the possibility of a new method of control.
6139F. L. Vanderplank, Transactions of the Royal Entomological Society of London, 98:1-18. 1947-01-02 21:38:18.
Hybridisation of Glossina morsitans Westwood, G. swynnertoni Austen and G. pallidipes Austen was attempted in order to discover(a) Whether the three could be regarded as distinct species or as sub-species of morsitans ; (b) Whether they would mate freely with one another, and if not by what means the three closely allied forms distinguished their own kind ; (c) Whether morsitans and swynnertoni would readily produce hybrid offspring, and if so, what proportion of females would do so, and what proportion of hybrids would be sterile ; (d) Finally, whether interference with one species by another could be used as a measure of control. I also wanted to explore other details including markings, colouration and nature of the genitalia of the hybrids, and whether these characters were constant or variable.
Parasitic nature of extra fragment chromosomes
6003Östergren G., Botaniska Notiser, 2:157-163. 1945-12-30 19:52:12.
This paper is intended as a contribution to the discussion concerning the significance of the extra fragments or »accessory chromosomes» as they are called by Håk ansso n(1945), which are not too rarely found in cross-fertilizing populations. I think reasonable support may he given to the view that in many cases these chromosomes have no useful function at all to the species carrying them, but that they often lead an exclusively parasitic existence.
Tsetse hybrids
6145W. H. Potts, Nature, 154:606-607. 1944-11-11 21:48:03.
IN 1936 I attempted to cross various species of tsetse (Glossina) with the idea that, should they hybridize readily, and should the resultant hybrids prove sterile, this might be tried as a measure of control. Corson had already, in 1932, obtained three offspring from crosses between male G. swynnertoni and female G. morsitans; he suggested, however, that these might not be true hybrids, but the result of parthenogenesis (see further details in the accompanying communication by Mr. F. L. Vanderplank). I obtained a number of offspring from this and other crosses, but as a slight doubt arose as to whether they were authentic hybrids, the results were never published.
Hybridization between Glossina Species and Suggested New Method for Control of Certain Species of Tsetse
6142F. L. Vanderplank, Nature, 154:607-608. 1944-11-11 21:43:25.
Corson and Potts record crossing Glossina swynnertoni Aust. with G. morsitans Westwood. Corson crossed twelve female G. morsitans with male G. swynnertoni, of which only two females produced a total of three pupæ. All his females lived long enough for reproduction to take place. He records the offspring, all females, as being identical with pure-bred G. morsitans, and suggested parthenogenesis. Potts crossed both male G. morsitans with female G. swynnertoni and male G. swynnertoni with female G. morsitans (see accompanying communication by Mr. W. H. Potts).
Preferential segregation in maize
6000M. M. Rhoades, Genetics, 27:395-407. 1942-12-30 19:47:18.
An abnormal type of chromosome 10, found by Longley in maize from the s.-w. part of the U. S., is preferentially segregated during megasporogenesis. More than 70% of the ovules receive the abnormal chromosome instead of the 50% expected with random segregation. At pachytene the length of the extra piece of chromatin in the abnormal chromosome is slightly greater than the short arm of chromosome 10. The proximal and distal portions of the extra piece are euchromatic, but a large and conspicuous knob lies between the 2 euchromatic portions. The origin of this extra piece is unknown. Pollen with the abnormal chromosome 10 is only partially successful in competing with pollen possessing a normal chromosome 10. Extra chromatin present in the abnormal chromosome may impair pollen-tube growth. The excess of ovules with the abnormal type of chromosome is due neither to abortion of ovules with a normal chromosome nor to megaspore competition. The R locus, known to lie in the long arm of chromosome 10, proved to be closely linked to the extra piece of chromatin which is believed to be inserted near the tip of the long arm. The observed % of recombination (1-2%) is probably less than the amt. occurring distal to R in stocks carrying 2 normal chromosomes 10. Crossing-over in the gR region is not affected when the abnormal chromosome is heterozygous, and crossing-over in this interval did not affect preferential segregation. Evidence was obtained indicating the influence of the environment on the degree of preferential segregation.
On the possibility of a new method for the control of insect pests.
6157A. S. Serebrovskii, Zoologicheskiĭ zhurnal, 19:618-630 (in Russian). 1940-01-03 16:43:28.
ON THE POSSIBILITY OF A NEW METHOD FOR THE CONTROL OF INSECT PESTS. The new principle of insect control consists in disturbing the propagation of the pest population by means of translocations. It is well known that individuals heterozygous for some translocations usually form a portion of aneuploid gametes and give a more or less inviable aneuploid progeny. On releasing, therefore, a sufficient number of individuals with a chromosome set altered by. translocations into a wild population (with allogamous propagation), there will arise heterozygotes for translocations yielding a certain percentage of inviable offspring. Crosses inside this population will be similar to those between species with resulting sterility of hybrids. The theoretical analysis reveals that if a wild population is mixed in proportion 1:1 with some race containing only one translocation viable in homozygous condition and giving in heterozygotes 50% of aneuploid gametes, the reproduction of the population will be reduced by 43%. If several races with different allelic translocations are released the reduction of reproduction in the population can reach 75%, and if races with 4-5 independent translocations are used the reduction can attain 95%-99% and even more. A population consisting of races with different translocations cannot remain in balance. Those types of chromosomes which happened to be in minority are subjected to elimination. Yet this process of elimination will go on during many generations and thus the disturbance of reproduction will be protracted. By an additional releasing of eliminating race, this disturbance can be maintained permanently. Diverse variants of this method are possible, depending upon the biology and economic importance of injurious insects, the cost of breeding translocated races in laboratories, the difficulties of obtaining viable translocations, etc. It is possible, for instance, to release only males, a method in which there is evidently no danger at all. The present investigation is a purely theoretical one. For the purpose of verifying experimentally this idea work has been started with Musca domestica and Calandra granaria - two insects widely differing in their cytogenetics, ecology and the kind of damage caused.
A new sex-ratio abnormality in Drosophila obscura
6047S. Gershenson, Genetics, 13:488. 1928-12-30 21:32:10.
1. The sex-ratio in the normal lines of Drosophila obscura is very near to the theoretical 1 : 1. 2. Out of 19 females caught in nature, two were heterozygous for a gene which causes strong deviations in the normal sex distribution. 3. The researches made have shown that this gene is localized in the X-chromosome and is transmitted like an ordinary sex-linked gene. 4. This gene is absolutely sex-limited, as it is not manifested either in heterozygous or homozygous females. 5. The males bearing this gene give in their progeny about 96 percent of females and only about 4 percent of males. 6. This gene has no influence on the development of the zygotes already formed, but acts directly upon the mechanism of sex-distribution. It provokes a sharp preponderance of females by almost totally removing the spermatozoa with the Y-chromosome from the fertilization process, acting thus like a gametic lethal (in the genetic sense of this term).
Sur la reproduction des souris anoures
6057N. Dobrovolskaia-Zavadskaia and N. Kobozieff, Comptes rendus des séances de la Société de biologie et de ses filiales, 97:116-119. 1927-06-15 15:44:03.
Nous ne connaissons que deux lignees de Souris sans queue, celle de Lang (1913), et cell de Duboscq (1922). L’elevange de Lang (lignee des Souris brachyures et anoures du preparateur Alfred Nageli) a donne 199 Souris normales, pour 173 brachyures et 9 anoures. Croisses entre ells et aveec des bachyures, les Souris anoures n’ont donne aucune reproduction. Dans la lignee du P Duboscq, provenant d’une femelle anoure A et de son frere normal, et comportant 25 petis en 8 portees, il y avait 8 anoures, don’t la plupart moururent jeunes.
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