scholarly journals THE GENETIC FACTORS ALTERED IN HOMOZYGOUS abo STOCKS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1986 ◽  
Vol 114 (3) ◽  
pp. 885-895
Author(s):  
William Sullivan ◽  
Sergio Pimpinelli
Keyword(s):  
Drosophila Melanogaster ◽  
Maternal Effect ◽  
Genetic Factors ◽  
Large Fraction ◽  
Embryonic Lethality ◽  
Heterozygous Condition ◽  
Homozygous Condition

ABSTRACT Females homozygous for the maternal-effect mutation abo (2-44.0) produce a large fraction of eggs which arrest during embryogenesis. Increasing doses of defined heterochromatic regions inherited by offspring of abo mothers from their fathers function zygotically to bring about a partial rescue of the abo-induced embryonic lethality. Another property of the abo mutation is that the severity of the maternal effect decreases when an abo stock is maintained in homozygous condition for a number of generations. Here, we show that the factors which change in homozygous abo stocks to result in the decrease in maternally induced embryonic lethality, act zygotically, dominantly and additively. More importantly, we show that the X and second chromosomes, but not the Y and third chromosomes, derived from homozygous abo stocks are, when inherited from males, more effective in promoting zygotic rescue of the abo-induced lethality than are the equivalent chromosomes derived from an abo stock maintained in heterozygous condition. The chromosomal locations of the factors altered in the homozygous stock, as well as their behavior, strongly suggest that the same heterochromatic elements that are responsible for rescuing embryos from the abo-induced maternal effect are altered in homozygous abo flies in such a way that the maternal effect itself is less severe.

scholarly journals HETEROZYGOUS EFFECTS ON FITNESS OF EMS-TREATED CHROMOSOMES IN DROSOPHILA MELANOGASTER

Genetics ◽  
1978 ◽  
Vol 88 (3) ◽  
pp. 575-590
Author(s):  
Michael J Simmons ◽  
Emily W Sheldon ◽  
James F Crow
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Heterozygous Condition ◽  
Homozygous Condition ◽  
Fitness Effects ◽  
Lethal Mutations ◽  
Induced Mutants ◽  
Heterozygous Carriers ◽  
Different Doses ◽  
Over Time

ABSTRACT The heterozygous effects on fitness of second chromosomes carrying mutants induced with different doses of EMS were ascertained by monitoring changes in chromosome frequencies over time. These changes were observed in populations in which the treated chromosomes, as well as untreated competitors, remained heterozygous in males generation after generation. This situation was achieved by using a translocation which links the second chromosome to the X chromosome; however, only untranslocated second chromosomes were mutagenized. Chromosomes were classified according to their effects on viability in homozygous condition. A preliminary homozygosis identified completely lethal chromosomes; secondary tests distinguished between drastic (viability index < 0.1) and nondrastic chromosomes. Chromosomes that were nondrastic after treatment were found to reduce the fitness of their heterozygous carriers by 3-5%. The data show that flies homozygous for these chromosomes were about 2.7% less viable per treatment with 1 mm EMS than flies homozygous for untreated chromosomes. By comparing the fitness-depressing effects of nondrastic EMS-induced mutants in heterozygous condition with the corresponding viability-depressing effects measured by Temin, it is apparent that the total fitness effects are several times larger than the viability effects alone. Completely lethal chromosomes derived from the most heavily treated material reduced fitness by 11% in heterozygous condition; approximately half of this reduction was due to the lethal mutations themselves.

scholarly journals A NOTE ON THE MATERNAL EFFECT MUTANTS DAUGHTERLESS AND ABNORMAL OOCYTE IN DROSOPHILA MELANOGASTER

Genetics ◽  
1973 ◽  
Vol 73 (1) ◽  
pp. 73-86
Author(s):  
Arthur P Mange ◽  
L Sandler
Keyword(s):  
Drosophila Melanogaster ◽  
Maternal Effect ◽  
Sex Chromosome ◽  
Chromosome 2 ◽  
Dominant Marker ◽  
Enhancing Effect ◽  
X Irradiation ◽  
The Right ◽  
Chromosome Breakpoint ◽  
Special Region

ABSTRACT Two deficiencies for, and a dominant enhancer of, the second chromosome maternal effect mutant, "daughterless" (da), were induced with X-irradiation. Their properties were studied with respect to both da and the linked maternal effect mutant, "abnormal oocyte" (abo), with the following conclusions. (1) The most probable map positions of da and abo are: J–½–da–2½–abo, where J is a dominant marker located at 41 on the standard map. (2) The da locus is in bands 31CD-F on the polytene chromosome map; abo is to the right of 32A. (3) Because homozygous da individuals survive while individuals carrying da and a deficiency for da are lethal, it is concluded that da is hypomorphic. (4) From a weak da-like maternal effect in heterozygous da females induced by an "Enhancer of da," we have confirmed a previous report that (a) the amount of sex chromosome heterochromatin contributed by the father can influence the severity of the da maternal effect, and (b) the sex chromosome heterochromatin which influences the da effect is different from that which influences the abo effect. (5) The possibility that da and abo are in a special region of chromosome 2 concerned with the regulation of sex chromosome heterochromatin is strengthened by the observation that the Enhancer of da appears to rescue abnormal eggs produced by homozygous abo mothers. (6) The Enhancer of da is a translocation between chromosomes 2 and 3 with the second chromosome breakpoint in the basal heterochromatin; because the enhancing effect maps in this region of chromosome 2, it is possible that autosomal, as well as sex chromosomal, heterochromatin interacts with da and abo.

scholarly journals The Maternal Effect Mutation sésame Affects the Formation of the Male Pronucleus in Drosophila melanogaster

2000 ◽  
Vol 222 (2) ◽  
pp. 392-404 ◽  
Author(s):  
Benjamin Loppin ◽  
Mylène Docquier ◽  
François Bonneton ◽  
Pierre Couble
Keyword(s):  
Drosophila Melanogaster ◽  
Maternal Effect ◽  
Male Pronucleus

scholarly journals Does RNA interference influence meiotic crossing over in Drosophila melanogaster?

2008 ◽  
Vol 90 (3) ◽  
pp. 253-258 ◽  
Author(s):  
ERIC W. CROSS ◽  
MICHAEL J. SIMMONS
Keyword(s):  
Drosophila Melanogaster ◽  
Rna Interference ◽  
X Chromosome ◽  
Maternal Effect ◽  
Crossing Over ◽  
Crossover Frequency ◽  
Chromosome Iii ◽  
Chromosome Ii ◽  
Balancer Chromosomes ◽  
Balancer Chromosome

SummaryMutations in the RNA interference (RNAi) genes aubergine (aub), homeless and piwi were tested for effects on the frequency, distribution and coincidence of meiotic crossovers in the long arm of the X chromosome. Some increases in crossover frequency were seen in these tests, but they may have been due to a maternal effect of the balancer chromosomes that were used to maintain the RNAi mutations in stocks rather than to the RNAi mutations themselves. These same balancers produced strong zygotic interchromosomal effects when tested separately. Mutations in aub and piwi did not affect the frequency of crossing over in the centric heterochromatin of chromosome II; nor did a balancer chromosome III.

scholarly journals Repression of P element-mediated hybrid dysgenesis in Drosophila melanogaster.

Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 663-676 ◽  
Author(s):  
M J Simmons ◽  
J D Raymond ◽  
K E Rasmusson ◽  
L M Miller ◽  
C F McLarnon ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Maternal Effect ◽  
Gonadal Dysgenesis ◽  
De Novo ◽  
Inbred Lines ◽  
Hybrid Dysgenesis ◽  
P Element ◽  
P Elements ◽  
Hybrid Offspring ◽  
Element Movement

Abstract Inbred lines derived from a strain called Sexi were analyzed for their abilities to repress P element-mediated gonadal dysgenesis. One line had high repression ability, four had intermediate ability and two had very low ability. The four intermediate lines also exhibited considerable within-line variation for this trait; furthermore, in at least two cases, this variation could not be attributed to recurring P element movement. Repression of gonadal dysgenesis in the hybrid offspring of all seven lines was due primarily to a maternal effect; there was no evidence for repression arising de novo in the hybrids themselves. In one of the lines, repression ability was inherited maternally, indicating the involvement of cytoplasmic factors. In three other lines, repression ability appeared to be determined by partially dominant or additive chromosomal factors; however, there was also evidence for a maternal effect that reduced the expression of these factors in at least two of the lines. In another line, repression ability seemed to be due to recessive chromosomal factors. All seven lines possessed numerous copies of a particular P element, called KP, which has been hypothesized to produce a polypeptide repressor of gonadal dysgenesis. This hypothesis, however, does not explain why the inbred Sexi lines varied so much in their repression abilities. It is suggested that some of this variation may be due to differences in the chromosomal position of the KP elements, or that other nonautonomous P elements are involved in the repression of hybrid dysgenesis in these lines.

scholarly journals ACCUMULATION OF DELETERIOUS GENES IN A CAGE POPULATION OF DROSOPHILA MELANOGASTER

Genetics ◽  
1977 ◽  
Vol 86 (3) ◽  
pp. 657-664
Author(s):  
Won Ho Lee ◽  
Takao K Watanabe
Keyword(s):  
Drosophila Melanogaster ◽  
Deleterious Effect ◽  
Natural Populations ◽  
Lethal Gene ◽  
Male Sterile ◽  
Effective Population ◽  
Population Number ◽  
Heterozygous Condition ◽  
Cage Population ◽  
Deleterious Genes

ABSTRACT Lethal and sterility mutations were accumulated in a cage population which was initiated with lethal- and sterility-free second chromosomes of D. melanogaster. It took about 2,000 days for the frequencies of these genes to reach equilibrium levels, i.e., 18% lethal and 9% male-sterile chromosomes. Two other cage populations which were initiated with random chromosomes sampled from natural populations and kept for more than eleven years in the laboratory showed 19-20% lethal content. The elimination rates of lethals by homozygosis in these populations were smaller than the mutation rate. By using Nei's formulae, the deleterious effect of a lethal gene in heterozygous condition (h) was estimated to be 0.035. The effective population number in the cage populations was estimated to be 1,000-2,900, while the actual population number was 3,500-7,800.

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