Scholarly Literature

This is a database of scholarly literature that concentrates currently on natural and engineered selfish genetic elements (gene drives).  The latest are shown here.
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Genotypes suppressing meiotic drive of a B-chromosome in the mealybug, Pseudococcus obscurus

4471
Nur, UB, B. L. H.,  Genetics,  110:73-92. 1985-01-09 00:00:00.
The rate of transmission (k) of a supernumerary B chromosome in male mealybugs is shown tq depend strongly on the chromosome set of materpal origin. When both parents came from an isofemale line in which the frequency of the B chromosome increased rapidly and stabilized at a mean of more than 4.0 B chromosomes per individual, was 0,92 and 0.95 in two series of crosses. However, when the female parent came from one of two isofemale lines in which the frequency of the B chromosome decreased from 2.0 to 0 in a few generations, R ranged from 0.53 to 0.78. The high ks, which represent a strong meiotic drive, are apparently responsible for the observed increase in the frequency of the B chromosome in several lines from a mean of about 0.5 to more than 4.0 in about 20 generations. The rapid loss of the B chromosome in other lines is attributed to genetic factors which caused the reduction in the rate of transmission qf the B chromosome.

Sex-chromosome meiotic drive in Drosophila melanogaster males

4474
McKee, B,  Genetics,  106:403-422. 1984-01-12 00:00:00.
In Drosophila melanogaster males, deficiency for X heterochromatin causes high X-Y nondisjunction and skewed sex chromosome segregation ratios (meiotic drive). Y and XY classes are recovered poorly because of sperm dysfunction. In this study it was found that X heterochromatic deficiencies disrupt recovery not only of the Y chromosome but also of the X and autosomes, that; both heterochromatic and euchromatic regions of chromosomes are affected and that the "sensitivity" of a chromosome to meiotic drive is a function of its length. Two models to explain these results are considered. One is a competitive model that proposes that all chromosomes must compete for a scarce chromosome-binding material in Xh- males. The failure to observe competitive interactions among chromosome recovery probabilities rules out this model. The second is a pairing model which holds that normal spermiogenesis requires X-Y pairing at special heterochromatic pairing sites. Unsaturated pairing sites become gametic lethals. This model fails to account for autosomal sensitivity to meiotic drive. It is also contradicted by evidence that saturation of Y-pairing sites fails to suppress meiotic drive in Xh- males and that extra X-pairing sites in an otherwise normal male do not induce drive. It is argued that meiotic drive results from separation of X euchromatin from X heterochromatin.

Integration of insect sterility and insecticides for control of Glossina morsitans morsitans Westwood (Diptera: Glossinidae) in Tanzania. IV. Application of endosulfan as an aerosol prior to release of sterile males

26520
D. L. Williamson, D. A. Dame, C. W. Lee, D. B. Gates and P. E. Cobb,  Bulletin of Entomological Research,  73:383-389. 1983-07-07 13:20:11.
As part of a programme to test the sterile insect technique against Glossina morsitans morsitans Westw. in Tanzania, two aerial applications of endosulfan were applied to a 195-km2 test area. The applications were made with a 28-day interval to provide an initial reduction in the target species prior to the release of sterile males. A Cessna 310 aircraft equipped with a rotary atomiser and operating at night was used to apply the insecticide at a dosage of about 20 g/ha. Flyround surveys within 48 h following the spraying operations indicated that a 100% reduction of G. m. morsitans adults was achieved in both applications, while G. pallidipes Aust. was reduced by 91 5% in the first and 100% in the second.

The fate of autosomeal modifiers of the sex-ratio trait in Drosophila and other sex-linked meiotic drive systems.

4475
Wu, CI,  Theoretical Population Biology,  24:107-120. 1983-01-13 00:00:00.
A model is proposed to analyze the behavior of autosomal suppressor modifiers of "Sex-Ratio" meiotic drive in drosophila. These modifiers, if neutral in fitness, are expected to increase because they tend to be associated with the rare sex (males). However, selection operating on the sex-linked drive locus will sometimes act against autosomal modifiers as well because the two loci are always in gametic phase disequilibrium. Conditions under which modifiers will not increase are presented in terms of the relative fitness of the sex-linked drive locus. To prevent the increase of modifiers, the fitness of Sex-Ratio males relative to Standard males has to be no greater than 0.3 and there has to be overdominance in females. This model integrates findings from the search for modifiers and results from the measurement of fitness.

Genetic-transformation of Drosophila with transposable element vectors

6252
G. M. Rubin and A. C. Spradling,  Science,  218:348-353. 1982-10-22 19:25:36.
Exogenous DNA sequences were introduced into the Drosophila germ line. A rosy transposon (ry1), constructed by inserting a chromosomal DNA fragment containing the wild-type rosy gene into a P transposable element, transformed germ line cells in 20 to 50 percent of the injected rosy mutant embryos. Transformants contained one or two copies of chromosomally integrated, intact ry1 that were stably inherited in subsequent generations. These transformed flies had wild-type eye color indicating that the visible genetic defect in the host strain could be fully and permanently corrected by the transferred gene. To demonstrate the generality of this approach, a DNA segment that does not confer a recognizable phenotype on recipients was also transferred into germ line chromosomes.

A cage replacement experiment involving introduction of genes for refractoriness to Plasmodium-yoelii-nigeriensis into a population of Anopheles gambiae (Diptera, Culicidae)

6230
P. M. Graves and C. F. Curtis,  Journal of Medical Entomology,  19:127-133. 1982-03-24 21:46:47.
A caged population of Anopheles gambiae was allowed to breed continuously and samples of the progeny were tested for susceptibility to Plasmodium yoelii nigeriensis. Males of a strain partially refractory to this parasite were released into the population for an 18-wk period. The susceptibility of the population declined from 100% to about 50% and remained at that level for several months after releases were terminated. Separate experiments showed that the fitness of the adult males and larvae of the refractory strain was much less than that of the susceptible caged strain. The observed change in the susceptibility of the caged population was compared with the expectations on various assumptions about the relative fitness of the refractory and susceptible strains. It appears that initially the efficiency of the replacement process was considerably reduced because of poor fitness of the refractory strain. Once the refractoriness genes were in the caged population, however, they were able to recombine with the genes causing poor fitness and the latter could be eliminated by natural selection, leaving a considerable degree of refractoriness in the population. The results are discussed in relation to the possibility of vector control by the release of males from a refractory strain and with particular reference to the advantages and disadvantages of the use of a negatively heterotic system to assist the replacement process and the release of both sexes.

A theoretical-analysis of the effects of sex-chromosome aneuploidy on X-chromosome and Y-chromosome meiotic drive

4476
Lyttle, TW,  Evolution,  36:822-831. 1982-01-14 00:00:00.
Extra sex chromosomes are normally detrimental to the individual carrying them. In XY (or WZ) sex determining systems, an extra X chromosome in the homogametic sex generates enough X-autosome imbalance to usually cause inviability, or at least sterility. On the oth- er hand, extra Y chromosomes are some- times tolerated, although in mammals and other higher organisms where the Y is ac- tively involved in sexual development, XXY individuals are generally sterile. In Drosophila and perhaps other inverte- brates where the Y is largely genetically inert, a single extra Y may be permitted in both sexes, while two extra copies is only fertile in XXYY females (Cooper, 1956), if at all.

Control of tsetse flies, Glossina spp.

26683
D. A. Dame and A. M. Jordan,  Advances in Veterinary Science and Comparative Medicine,  25:101-119. 1981-07-18 13:09:37.
Studies of SIT in Zimbabwe with releases of chemosterilized G. m. morsitans (Dame and Schmidt, 1970) demonstrated the feasibility of the methodology used both in the laboratory and in the field. Subsequent trials were recently completed in Tanzania, where laboratory bred sterile males were released into the natural breeding areas of a population of flies that had been partially suppressed by two aerial applications of endosulfan. Over a quarter of a million irradiated insects were released to control the G. m. morsitans population on a 195-km2 cattle ranch. The flies proved to be fully competitive andeffective. If it had been possible to isolate the plot from immigrating tsetse, the natural population on the ranch would probably have beep eliminated with a substantially lower number of flies than was necV essary to maintain the prolonged 90% level of control that was achieved (Dame et al., 1980). In Upper Volta, similar advances werd made with sterile G. p. gambiensis, bred in the laboratory and released in linear riverine habitats. Glossina p. gambiensis was eradicated from an 11-km section of the experimental plot (Cuisance et al., 1980)/ These accomplishments were completed after extensive study in Chad/ the Central African Republic, and Upper Volta.

Meiotic drive at the D(MD) locus and fertility in the mosquito, Aedes aegypti (L)

4479
Youngson, JW, H. M.; Wood, R. J.,  Genetica,  54:335-340. 1981-01-17 00:00:00.
The Distorter gene D in Aedes aegypti shows meiotic drive when associated with the male determining M gene, causing sex ratio distortion in favour of males. The fertility of Distorter (MD /ms) and normal (M/m-) males has been compared after mating them to a series of 20 females at daily intervals. ; Males of each genotype inseminated up to 13 fe. males (mean 8.0 - 9.0). The major difference was in the significantly greater number of inviable eggs produced by females mated to Distorter males. It is postulated that these eggs were fertilised by abnormal spermatozoa. Females mated to Distorter males also produced significantly greater numbers of shrivelled i.e. unfertilised eggs, indicating a lower density of effective spermatozoa.; The difference in percentage hatch from the two matings was small, indicating that spermatozoa were produced in superabundance so that the overall fertility of Distorter males was not greatly reduced.

A 2-locus model for polymorphism for sex-linked meiotic drive modifiers with possible applications to Aedes aegypti

4478
Maffi, GJ, S. D.,  Theoretical Population Biology,  19:19-36. 1981-01-16 00:00:00.
A two-locus model is presented which shows the possibility of maintaining a polymorphism for modifiers of sex-linked meiotic drive in the absence of fitness differences. The model is very similar to the situation actually found in some laboratory strains of the mosquito Aedes aegypti. The existence of a stable polymorphism usually requires sufficiently loose linkage between the two loci.

Experimental population-genetics of meiotic drive systems .3: Neutralization of sex-ratio distortion in Drosophila through sex-chromosome aneuploidy

4477
Lyttle, TW,  Genetics,  98:317-334. 1981-01-15 00:00:00.
Laboratory populations of Drosophila melanogaster were challenged by; pseudo-Y drive, which mimics true Y-chromosome meiotic drive through the; incorporation of Segregation Distorter (SD) in a T(Y;2) complex. This causes; extreme sex-ratio distrotion and can ultimately lead to population extinction.; Populations normally respond by the gradual accumulation of drive suppressors,; and this reduction in strength of distortion allows the sex ratio to move; closer to the optimal value of 1:l. One population monitored, however, was; rapidly able to neutralize the effects of sex-ratio distortion by the accumulation; of sex-chromosome aneuploids (XXY, XYY) . This apparently occurs because; XX-bearing eggs, produced in relatively high numbers (-4%) by XXY; genotypes, become the main population source of females under strong Ychromosome; drive. Computer simulation for a discrete generation model incorporating; random mating with differences in fitness and segregation permits; several predictions that can be compared to the data. First, sex-chromosome; aneuploids should rapidly attain equilibrium, while stabilizing the population; at -60% males. This sex ratio should be roughly independent of the strength; of the meiotic drive. Moreover, conditions favoring the accumulation of drive; suppressors (e.g., weak distortion, slow population extinction) are insufficient; for maintaining aneuploidy, while conditions favoring aneuploidy (e.g., strong; distortion, low production of females) lead to population extinction before drive; suppressors can accumulate. Thus, the different mechanisms for neutralizing; sex-ratio distortion are complementary. In addition, Y drive and sex-chromosome; aneuploidy are potentially co-adaptive, since under some conditions; neither will survive alone. Finally, these results suggest the possibility that; genetic variants promoting sex-chromosome nondisjunction may have a selective; advantage in natural populations faced with sex-ratio distortion.

Combining the meiotic drive gene-D and the translocation T-1 in the mosquito, Aedes aegypti(L) .2: Recombination

4481
Pearson, AMW, R. J.,  Genetica,  54:79-85. 1980-01-19 00:00:00.
Recombination on the sex-chromosome of Aedes aegypti has been studied in male genotypes incorporating the sex-linked translocation T1 and the meiotic drive gene D from three different strains (Trinidad, Bozo and Caracas).

Combining the meiotic drive gene-D and the translocation-T1 in the mosquito, Aedes aegypti (L) .1: Sex-ratio distortion and fertility

4480
Pearson, AMW, R. J.,  Genetica,  51:203-210. 1980-01-18 00:00:00.
Sex-ratio distortion has been investigated in males carrying the Y(M)-linked meiotic-drive gene D, from three different strains (Bozo, Caracas and Trinidad), paired with Chipei X-chromosomes highly sensitive to D. The effect of D was tested on its own and also associated with a 1-3 translocation (designated TI). The fertility of males homozygous and heterozygous for the translocation, with and without D, was also investigated

Experimental population-genetics of meiotic drive systems .2: Accumulation of genetic modifiers of Segregation Distorter (SD) in laboratory populations

4482
Lyttle, TW,  Genetics,  91:339-357. 1979-01-20 00:00:00.
The accumulation of modifiers of the meiotic-drive locus Segregation; Distorter (SD) in Drosophila melanogaster was monitored by measuring the; changes in the mean and variance of drive strength (in terms of “make” value); that occur in laboratory populations when SD and SD+ chromosomes are in; direct competition. The particular SD lines used are T(Y;Z),SD translocations; showing pseudo-Y drive. Four sets of population cages were analyzed. Two sets; were monitored for changes in SD fitness and drive strength (presumed to be; positively correlated) and analyzed for the presence of autosomal dominant; or X-linked modifiers after long periods of time. The remaining two sets were; made up of cages either made isogenic or variable for background genetic; material, and these were used to test whether the rate of accumulation of; modifiers was dependent on initial genetic variability.-Contrary to previous; studies in which most suppression of SD action could apparently be attributed; to a few dominantly acting modifiers of large effect, the conclusion here is; that laboratory populations that are initially free of such major dominant loci; evolve to suppress SD action by accumulating polygenic, recessive modifiers,; each of small effect, and that much of the required genetic variability can be; generated a!e novo by mutation. Possible explanations for these seemingly incompatible results and the evolutionary implications for SD are considered.

Sex-ratio trait in Drosophila pseudoobscura – Fertility relations of males and meiotic drive.

4483
Beckenbach, AT,  American Naturalist,  112:97-117. 1978-01-21 00:00:00.
In the early analysis of the "sex-ratio" polymorphism (SR) of Drosophila pseudoobscura, complete meiotic drive was assumed, and study centered on the nature of the selective forces opposing its spread. Policansky and Ellison (1970) found that the mechanism of SR involved the degeneration of half the spermatids during spermatogenesis. They suggested that little or no drive may be expressed due to a fertility deficiency of SR males. Thus little or no selection is required to balance the drive. I report studies conducted to determine the conditions under which either of these alternatives might hold. Virgin females were mated once to either SR or ST (standard) males aged as virgins for 3 days, and their fecundities were determined by daily egg counts. No differences were found between the two groups in either daily egg production or egg-to-adult survival of the progenies. Only females maintained with males throughout the experiment were clearly superior in these parameters. No fertility differences between SR and ST males are unconditional. Fertilities of males aged for varying lengths of time as virgins were determined by mating them to as many virgin females as they would inseminate in a brief span of time. Time periods ranged from 3 to 8 h, depending on the ages of the males. Fertility of the SR males was lower than that of ST males of the same age for males aged 20-33 h from eclosion. Differences in 4-day-old males were not so clear. When 4-day-old males which had depleted their stores of sperm by repeated matings were retested after 12 h of rest, SR males again showed lower fertility than ST males. The fertility reduction of SR males occurs only during the first few days as adults or after repeated matings. The effect of different degrees of insemination on the pattern of production of fertile eggs was examined by mating virgin females to males which were either virgin (heavy insemination) or with seminal vesicles partially depleted by three previous matings (light insemination). No differences in either fecundity or hatchability between the groups were observed early in the reproductive period, but the hatchability of the eggs produced by the lightly inseminated females declined sooner than that of the heavily inseminated group. This response would minimize the populational consequences of fertility differences in males unless the females remate. It is suggested that the conditional fertility differences between SR and ST males are of little consequence until the females remate. Depending on the time of remating, there is potentially a wide range in the amount of meiotic drive expressed.

Transporting marker gene re (red eye) into a laboratory cage population of Aedes aegypti (Diptera Culicidae), using meiotic drive at MD locus

4486
Wood, RJC, L. M.; Hamilton, A.; Whitelaw, A.,  Journal of Medical Entomology,  14:461-464. 1978-01-04 00:00:00.
An attempt has.been made to use the meiotic drive gene MD to transport a marker re (red eye) into a laboaratory population of the mosquito Aedes aegypti. The experiment produced an increase in re frequency, but also indicated that this gene has unexpectedly high fitness in the laboratory. The need for field estimates of fitness is indicated.

Sex ratio distortion caused by meiotic drive in a mosquito Culex pipiens

4485
Sweeny, TLB, A. R.,  Genetics,  88:427-446. 1978-01-03 00:00:00.
A genetic factor, distorter (d), has been discovered that upsets the normal sex ratio of 1 : 1 and results in a large excess of males in Culex pipiens. The effect can be explained by a sex-linked, recessive gene. Males homozygous for the gene (Md/md) produce few female offspring; the effect is not due to postzygotic mortality. During the first meiotic division in spermatogenesis, the shortest chromosome pair, which, according to JOST and LAVEN (1971), is associated with sex determination, can be seen to be abnormal. In a high proportion of spermatocysts, one of the dyads of the shortest bivalent fragments, and the pieces are distributed irregularly to the daughter cells. It is believed that the female-determining chromosomes fragment. This would give rise to an excess of male-determining sperm. The possible usefulness of this factor for control or for experimental purposes is discussed.

Transporting marker gene re (red eye) into a laboratory cage population of Aedes-aegypti (Diptera Culicidae), using meiotic drive at MD locus

6233
R. J. Wood, L. M. Cook, A. Hamilton and A. Whitelaw,  Journal of Medical Entomology,  14:461-464. 1977-12-24 21:51:08.
An attempt has been made to use the meiotic drive gene MD to transport a marker re (redeye) into a laboratory population of the mosquito Aedes aegypti. The experiment produced an increase in re frequency, but also indicated that this gene has unexpectedly high fitness in the laboratory. The need for field estimates of fitness is indicated.

Sterility introduced by release of genetically altered males to a domestic population of Aedes aegypti at the Kenya coast

25875
P. T. McDonald, W. Hausermann and N. Lorimer,  Am J Trop Med Hyg,  26:553-61. 1977-05-06 07:09:31.
The release of males heterozygous for one or two sex-linked translocations was effective in introducing a high level of sterility into a domestic population of Aedes aegypti at a Rabai village. The effect of the releases continued for several weeks after the release period. Male mosquitoes, Aedes aegypti, were released at the Kenya coast to test the effectiveness of laboratory engineered mosquitoes in introducing a genetic mechanism and the ability of the mechanism to establish itself under field conditions. A triplicate of Rabai villages was selected for the experiment. In the 1st village nottreatment was made. In the 2nd village the domestic water containers were cleaned twice a week to remove larvae and pupae. Translocation males were released in the 3rd village. A mixture of 2 types of males was introduced: the single heteroxygote male selected from 78 translocations induced by irradiation in the African strains, and the double heterozygote male. Genetic analysis of the content of release samples determined quality control of released males. Fertility was also determined with females of a strain collected at Chibarani before releases began. Hatchability of eggs in all villages was counted to assay sterility in all villages. Before the releases population fluctuations in the 3 villages were monitored for 20 weeks. The release mixture had a fertility of 37% and the single heterozygote of 50%. A daily survival rate of .63 was shown for the dusted release males. There was close agreement between the monitoring for sterility for both the egg collections and the oviposition of the LB catch females. The sterility introduced into the Chibarani population was extensive.

Resistance to meiotic drive at MD locus in an Indian wild population of Aedes aegypti

4488
Suguna, SGW, R. J.; Curtis, C. F.; Whitelaw, A.; Kazmi, S. J.,  Genetical Research,  29:123-132. 1977-01-06 00:00:00.
Females from an Indian wild population of Aedes aegypti were crossed to males carrying the sex ratio distorter factor MB which shows meiotic drive. Progenies from ¥1 males were tested for sex ratio distortion, i.e. the chromosomes from the wild females were screened for their resistance to the action of M°. The distribution of sex ratio in the progenies of different ¥1 males indicated a polymorphism in the wild population for resistant and sensitive variants of the X chromosome. Seven discrete categories of X appear to exist, associated with sex ratios ranging from 50 % $ to less than 1'25 % $. The overall level of resistance varied slightly but significantly in different parts of a town. The results are discussed in relation to the use of sex ratio distortion for genetic control of mosquitoes.

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