TEMPERATURE-DEPENDENT EXPRESSION OF THE APTEROUS PHENOTYPE IN DROSOPHILA MELANOGASTER

Genetics ◽  
1986 ◽  
Vol 112 (2) ◽  
pp. 217-228
Author(s):  
Mary E Stevens ◽  
Peter J Bryant

ABSTRACT Mutations at the apterous (ap) locus in Drosophila melanogaster produce a variety of developmental defects, including several classes of wing abnormalities. We describe the wing phenotype produced by homozygotes and hemizygotes of three different temperature-sensitive apterous alleles grown at 16, 18, 20, 22, 25, and 29°. We also describe the phenotype produced by each of these three alleles when heteroallelic with the non-temperature-sensitive apc allele. Constant-temperature and temperature-shift experiments show that each of the heteroallelic genotypes can produce several of the previously described apterous phenotypes and that the length of the temperature-sensitive period for a given phenotype depends on the allelic combinations used to measure it. We suggest that the stage-specific requirements of the tissue for gene product, rather than the time of gene expression per se, determine the temperature-sensitive periods for apterous and other loci. The results support the hypothesis that the various wing phenotypes produced by apterous mutations are due to quantitative reductions in the activity of gene product and that failure to meet specific threshold requirements for gene product can lead to qualitatively different phenotypes.

1981 ◽  
Vol 38 (3) ◽  
pp. 297-314 ◽  
Author(s):  
John C. Sparrow

SUMMARYThe recovery of two EMS induced mutations which are dominant suppressors of the lethality of cryptocephal in Drosophila melanogaster are described. One of these mutations Su(crc)1 is described in detail. It maps very close to cryptocephal at 54·7 on the second chromosome and its suppression of cryptocephal is temperature-sensitive. Temperature shift experiments show that the temperature-sensitive period is from before the pupariation until 12 h post pupariation. The temperature-sensitive period of Su(crc)1 is discussed in relation to the expression of l(2)crc, head eversion and the timing of pupal chitin synthesis.


Genetics ◽  
1975 ◽  
Vol 79 (4) ◽  
pp. 613-634
Author(s):  
W J Peacock ◽  
George L Gabor Miklos ◽  
D J Goodchild

ABSTRACT The meiotic drive characteristics of the In(1)sc4Lsc8R/Y system have been examined by genetic analysis and by light and electron microscopy. sc4sc8/Y males show a direct correlation between nondisjunction frequency and meiotic drive. Temperature-shift experiments reveal that the temperature-sensitive period for nondisjunction is at meiosis, whereas that for meiotic drive has both meiotic and post-meiotic components. Cytological analyses in the light and electron microscopes reveal failures in spermiogenesis in the testes of sc  4  sc  8 males. The extent of abnormal spermatid development increases as nondisjunction becomes more extreme.


Development ◽  
1991 ◽  
Vol 113 (1) ◽  
pp. 373-384 ◽  
Author(s):  
R.E. Boswell ◽  
M.E. Prout ◽  
J.C. Steichen

The mago nashi (mago) locus is a newly identified strict maternal effect, grandchildless-like, gene in Drosophila melanogaster. In homozygous mutant mago females reared at 17 degrees C, mago+ function is reduced, the inviable embryos lack abdominal segments and 84–98% of the embryos die. In contrast, at 25 degrees C, some mago alleles produce a novel gene product capable of inducing the formation of symmetrical double abdomen embryos. Reciprocal temperature-shift experiments indicate that the temperature-sensitive period is during oogenetic stages 7–14. Furthermore, embryos collected from mago1 homozygous females contain no apparent functional posterior determinants in the posterior pole. In viable F1 progeny from mago mutant females, regardless of genotype and temperature, polar granules are reduced or absent and germ cells fail to form (the grandchildless-like phenotype). Thus, we propose that the mago+ product is a component of the posterior determinative system, required during oogenesis, both for germ cell determination and delineation of the longitudinal axis of the embryo.


1984 ◽  
Vol 43 (3) ◽  
pp. 257-275 ◽  
Author(s):  
Donald A. R. Sinclair ◽  
Thomas A. Grigliatti ◽  
Thomas C. Kaufman

SUMMARYMinute(M) lesions exhibit a striking propensity for interacting with many different mutations. In the past, few attempts have been made to explain these diverse phenomena. This study describes a variety of temperature-sensitive (ts) interactions exhibited by the ts third chromosomeMinutemutationM(3)LS4Q-III(Q-III). Most of these interactions (i.e. those involvingvg, cp, Dl, DfdorLy) reflectQ-III-induced enhancement of the respective mutant phenotypes at the restrictive temperature. However,Q-IIIalso suppresses the extra-sex-comb phenotypes ofPcandMscat 29 °C and evokes lethal and bristle traits when combined withJ34eat the restrictive temperature. All of these interactions are characteristic of non-tsMinutelesions and thus they appear to be correlated with general physiological perturbations associated with theMsyndrome. In addition, our findings show that mutations that affect ribosome production and/or function, namelysu(f)ts67gandbbts−1, exhibit interactions comparable to those elicited byQ-III. Hence, in accordance with previous findings, we argue that most of theQ-IIIinteractions can be attributed to reduced translational capacity at the restrictive temperature. Finally, reciprocal temperature shift studies were used to delineate TSPs for interactions betweenQ-IIIandvg(mid to late second instar),cp(about mid-third instar),Dfd(early third instar) andDl(late second to mid third instar). We believe that these TSPs represent developmental intervals during which the respective gene products are utilized.


1984 ◽  
Vol 44 (1) ◽  
pp. 11-28 ◽  
Author(s):  
Margaret G. Kidwell

SummaryVariable frequencies of unhatched eggs were observed to be produced by a number of F1 interstrain hybrids. This type of partial sterility resulting from F2 embryo death was found to be associated with the P-M system of hybrid dysgenesis. Dysgenic hybrid progeny of crosses between M strain females and P strain males may therefore have reduced fertility due to the disruption of development at two different stages: early F1 gonadal development and early F2 embryo development. These disruptions result in the previously described F1 gonadal dysgenesis (GD sterility) and F2 embryo lethality (EL sterility) respectively. The two morphologically distinct types of P-M-associated sterility differ in their patterns of response to F1 developmental temperature, and the temperature-sensitive period for EL sterility occurs considerably later in F1 development than for GD sterility. EL sterility is similar to SF sterility, which is associated with the I–R system of hybrid dysgenesis in that both result from death during early F2 embryogenesis. However, EL sterility differs from SF sterility in not being restricted to hybrids of the female sex and in showing different patterns of response to temperature and ageing in the F1 generation. Some implications of the existence of EL sterility for methods of strain classification in the I–R system are explored.


Genetics ◽  
1981 ◽  
Vol 97 (3-4) ◽  
pp. 581-606 ◽  
Author(s):  
Donald A R Sinclair ◽  
David T Suzuki ◽  
Thomas A Grigliatti

ABSTRACT A temperature-sensitive (ts) third chromosome Minute (M) mutation, designated Q-III, has been recovered and characterized. Q-III heterozygotes raised at 29" exhibit all of the dominant traits of M mutants including small bristles, rough eyes, prolonged development, reduced viability 2nd interactions with several unrelated mutations. Q-III homozygotes raised at 29° are lethal; death occurs primarily during the first larval instar. When raised at 22°, Q-Ill heterozygotes are phenotypically normal and Q-III homozygotes display moderate Mtraits. In addition, Q-IIIelicits ts sterility and maternal-effect lethality. As it true of Mlesions, the dominant traits of Q-111 are not expressed in triploid females raised at 29°. Complementation tests suggest that Q-III is a ts allele of M(3)LS4, which is located in 3L near the centromere.——Reciprocal temperature-shift experiments revealed that the temperature-sensitive period (TSP) of Q-111 lethality is polyphasic, extending from the first instar to the latter half of pupation. Heat-pulse experiments further resolved this into two post-embryonic TSPs: one occurring during the latter half of the second larval instar, and the other extending from the larval/pupal boundary to the second half of pupation. In addition, heat pulses elicited a large number of striking adult phenotypes in Q-III individuals. These included pattern alterations such as deficiencies and duplications and cther morphological defects in structures produced by the eye-antennal, leg, wing and genital imaginal discs and the abdominal histoblasts. Each defect or pattern alteration is associated with a specific TSP during development.——We favor the interpretation that most of the major Q-III defects, particularly the structural duplications and deficiencies, result from temperature-induced cell death in mitotically active imaginal anlagen, while the small macrochaete phene probably results from the direct effects of Q-III on bristle synthesis. The hypothesis that the Q-III locus specifices a component required for protein synthesis is discussed, and it is concluded that this hypothesis can account for the pleiotropy of Q-III, and that perhaps it can be extended to M loci in general.


Genetics ◽  
1988 ◽  
Vol 118 (1) ◽  
pp. 61-74
Author(s):  
T M Rogalski ◽  
D L Riddle

Abstract The amanitin-binding subunit of RNA polymerase II in Caenorhabditis elegans is encoded by the ama-1 gene, located approximately 0.05 map unit to the right of dpy-13 IV. Using the amanitin-resistant ama-1(m118) strain as a parent, we have isolated amanitin-sensitive mutants that carry recessive-lethal ama-1 alleles. Of the six ethyl methanesulfonate-induced mutants examined, two are arrested late in embryogenesis. One of these is a large deficiency, mDf9, but the second may be a novel point mutation. The four other mutants are hypomorphs, and presumably produce altered RNA polymerase II enzymes with some residual function. Two of these mutants develop into sterile adults at 20 degrees but are arrested as larvae at 25 degrees, and two others are fertile at 20 degrees and sterile at 25 degrees. Temperature-shift experiments performed with the adult sterile mutant, ama-1(m118m238ts), have revealed a temperature-sensitive period that begins late in gonadogenesis and is centered around the initiation of egg-laying. Postembryonic development at 25 degrees is slowed by 30%. By contrast, the amanitin-resistant allele of ama-1 has very little effect on developmental rate or fertility. We have identified 15 essential genes in an interval of 4.5 map units surrounding ama-1, as well as four gamma-ray-induced deficiencies and two duplications that include the ama-1 gene. The larger duplication, mDp1, may include the entire left arm of chromosome IV, and it recombines with the normal homologue at a low frequency. The smallest deficiency, mDf10, complements all but three identified genes: let-278, dpy-13 and ama-1, which define an interval of only 0.1 map unit. The terminal phenotype of mDf10 homozygotes is developmental arrest during the first larval stage, suggesting that there is sufficient maternal RNA polymerase II to complete embryonic development.


1998 ◽  
Vol 180 (6) ◽  
pp. 1389-1395 ◽  
Author(s):  
Toshiko Aiso ◽  
Reiko Ohki

ABSTRACT A divE mutant, which has a temperature-sensitive mutation in the tRNA1 Ser gene, exhibits differential loss of the synthesis of certain proteins, such as β-galactosidase and succinate dehydrogenase, at nonpermissive temperatures. In Escherichia coli, the UCA codon is recognized only by tRNA1 Ser. Several genes containing UCA codons are normally expressed after a temperature shift to 42°C in the divE mutant. Therefore, it is unlikely that the defect in protein synthesis at 42°C is simply caused by a defect in the decoding function of the mutant tRNA1 Ser. In this study, we sought to determine the cause of the defect in lacZ gene expression in thedivE mutant. It has also been shown that the defect inlacZ gene expression is accompanied by a decrease in the amount of lacZ mRNA. To examine whether inactivation of mRNA degradation pathways restores the defect in lacZ gene expression, we constructed divE mutants containingrne-1, rnb-500, and pnp-7 mutations in various combinations. We found that the defect was almost completely restored by introducing an rne-1 pnp-7 double mutation into the divE mutant. Northern hybridization analysis showed that the rne-1 mutation stabilized lacZ mRNA, whereas the pnp-7 mutation stabilized mutant tRNA1 Ser, at 44°C. We present a mechanism that may explain these results.


Genetics ◽  
1974 ◽  
Vol 76 (3) ◽  
pp. 487-510
Author(s):  
Marianne E Dudick ◽  
Theodore R F Wright ◽  
Lynda Lee Brothers

ABSTRACT A temperature-sensitive lethal allele of suppressor of forked, l(1)su(f)ts67g (ts67), has been discovered and characterized as follows: Flies which are hemizygous for ts67 live at 18° and 25° but die at 30° primarily as larvae. The temperature-sensitive period for ts67 homozygotes or hemizygotes begins in second instar and ends at pupation. ts67 is lethal at 30° when heterozygous with suppressor of forked (su(f)), a deficiency for suppressor of forked (su(f)  -), and a non-conditional lethal allele of suppressor of forked (3DES). It is viable at 30° when heterozygous with the wild-type allele of suppressor of forked. At 25° but not at 18° forked bristles are suppressed in flies of the following genotypes: fsts67/Y, fsts67/fsts67, fsts67/fssu(f), futs67/fs3DES, futs67/fssu(f)  -, futs67/fssu(f). There is some suppression of forked bristles at 25° in the heterozygote, fsts67/fs+su(f). The forked bristle phenotype is not suppressed at either temperature in flies of the genotypes futs67/Y, futs67/futs67/ (fs and fu indicating suppressible and unsuppressible alleles of forked). The temperature-sensitive period for suppression of forked bristles begins at pupation and extends through the period of bristle synthesis. The deficiency phenotype (bristles reduced in size or absent, wing wrinkled or blistered, eyes rough) typical of flies of the genotype fssu(f)/fssu(f)  - at 18° and 25°, is exhibited by flies of the genotypes fsts67/fssu(f)  - at 25° and futs67/fssu(f) at 29°. An allele of lozenge (lz1) which can be suppressed by su(f) is suppressed at 25° but not at 18° in lz1ts67/Y males. ts67 homozygous females are fertile at 25° but sterile at 30°. The hypothesis is discussed that the su(f) locus codes for a ribosomal protein and that suppression and enhancement are affected by mutations at the locus by mutant ribosome-induced misreading. The possibility is presented that ts67 may be used to determine the translation time in development of any gene.


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