scholarly journals Experimental modification of the dominance relations of a melanotic tumour gene in Drosophila melanogaster

1972 ◽  
Vol 20 (1) ◽  
pp. 115-135 ◽  
Author(s):  
Ann Louise Belt ◽  
Barrie Burnet
Keyword(s):  
Drosophila Melanogaster ◽  
Larval Instar ◽  
Environment Interaction ◽  
Larval Food ◽  
Dominance Relations ◽  
The Third ◽  
Genotype Environment Interaction ◽  
Tumour Formation ◽  
Food Medium ◽  
Melanotic Tumour

SUMMARYThe melanotic tumour gene tu-C4 in Drosophila melanogaster shows incomplete dominance, together with variable penetrance and expressivity. It is tentatively located in the region of locus 52–53 on the third chromosome. Tumour formation in mutant homozygotes involves a precocious haemocyte transformation leading to the appearance of lamellocytes at the beginning of the third larval instar. These aggregate to form tumour-like masses which subsequently melanize. The process of tumour formation is in broad outline similar to that found in other tumour strains. Melanotic tumour formation is treated as a dichotomous threshold character, assuming an underlying normal distribution of liability relative to a fixed threshold. The expression of the tumour gene can be influenced by the levels of protein, phospholipid, nucleic acid and carbohydrate in the larval food medium, and changes in dominance and penetrance induced by sub-optimal environments deficient in these nutrients are positively correlated. Reinforcement by selection of the dominance relations of tu-C4 was accompanied by correlated changes in penetrance. Conversely, selection for increased penetrance was accompanied by correlated changes in dominance. Dominance and penetrance, it is concluded, are fundamentally related aspects of tumour gene expression. Recruitment of dominance modifiers linked to the tumour gene was excluded by the mating scheme employed, and the observed changes in dominance relations in response to selection were due largely to modifiers located on the second chromosome. Changes in dominance relations produced by selection could be significantly reinforced, or reversed, by environmental factors and consequently show a substantial genotype – environment interaction effect. These facts are relevant to current theories of dominance evolution.

The Post-embryonic Development of the Tracheal System in Drosophila melanogaster

1957 ◽  
Vol s3-98 (41) ◽  
pp. 123-150
Author(s):  
JOAN M. WHITTEN
Keyword(s):  
Drosophila Melanogaster ◽  
Adult Stage ◽  
Larval Instar ◽  
Pupal Stage ◽  
Tracheal System ◽  
True Nature ◽  
The Third ◽  
Air Sacs ◽  
Abdominal Region ◽  
Pupal Cuticle

The fate of the tracheal system is traced from the first larval instar to the adult stage. The basic larval pattern conforms to that shown for other Diptera Cyclorrhapha (Whitten, 1955), and is identical in all three instars. According to previous accounts the adult system directly replaces the larval: the larval system is partly shed, partly histolysed, and the adult system arises from imaginal cell clusters independently of the preceding larval system. In contrast, it is shown here that in the cephalic, thoracic, and anterior abdominal region there is a definite continuity in the tracheal system, from larval, through pupal to the adult stage, whereas in the posterior abdominal region the larval system is histolysed, and the adult system is independent of it in origin. Moreover, in the pupal stage this region is tracheated by tracheae arising from the anterior abdominal region and belonging to a distinct pupal system. Moulting of the tracheal linings is complete at the first and second larval ecdyses, but incomplete at the third larval-pupal and pupal-adult ecdyses. In consequence, in both pupal and adult systems there are tracheae which are secreted around preexisting tracheae, others formed as new ‘branch’ tracheae, and those which have been carried over from the previous instar. In the adult the newly formed tracheae of the posterior abdominal region fall into a fourth category. Most of the adult thoracic air sacs correspond to new ‘branch’ tracheae of other instars. The pre-pupal moult and instar are discussed with reference to the tracheal system and tentative suggestions are made concerning the true nature of the pre-pupal cuticle. There is no pre-pupal tracheal system. Events traced for Drosophila would seem to be general for Cyclorrhapha, both Acalypterae and Calypterae. The separate fates of the anterior and posterior abdom inal systems, in contrast with the straightforward development in Dipterc Nematocera, would appear to mark a distinct step in the evolution of the system in Diptera.

Genetic parameters and genotype–environment interactions of Chinese fir (Cunninghamia lanceolata) in Fujian Province

2014 ◽  
Vol 44 (6) ◽  
pp. 582-592 ◽  
Author(s):  
Liming Bian ◽  
Jisen Shi ◽  
Renhua Zheng ◽  
Jinhui Chen ◽  
Harry X. Wu
Keyword(s):  
Genetic Parameters ◽  
Breeding Strategy ◽  
Chinese Fir ◽  
Breeding Program ◽  
Cunninghamia Lanceolata ◽  
Environment Interaction ◽  
Fujian Province ◽  
The Third ◽  
Genotype Environment Interaction ◽  
Sib Families

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) is the most commercially important conifer in China, and the Nanjing Forestry University – Fujian Province Chinese fir Cooperation (NJFU – Fujian Cooperation) breeding program has advanced it into the third cycle of selection and breeding. In this paper, we estimated genetic parameters from four sites for 80 half-sib families and summarized previous estimates of genetic parameters in Chinese fir with an objective to propose optimal breeding strategy. Heritability averaged 0.20 and 0.14 for height and diameter at breast height (DBH), respectively, for the four sites. A significant genotype–environment interaction (G × E) for growth was also observed among the four sites, with the greatest interactions between a marginal site and the three central sites in the Fujian Province Chinese fir plantation region. The average estimated type-B genetic correlation between the marginal site and the three central sites was 0.08 for height and –0.09 for DBH. However, the highly productive families were among the most stable across the four sites. The results from this study in combination with summarized genetic parameters from literature were used to discuss and propose an optimal breeding strategy for the third generation of the breeding program for Chinese firs in Fujian Province.

scholarly journals Temporal uniformity of the spontaneous mutational variance of quantitative traits in Drosophila melanogaster

2000 ◽  
Vol 75 (1) ◽  
pp. 47-51 ◽  
Author(s):  
AURORA GARCÍA-DORADO ◽  
JESUS FERNÁNDEZ ◽  
CARLOS LÓPEZ-FANJUL
Keyword(s):  
Drosophila Melanogaster ◽  
Morphological Traits ◽  
Quantitative Traits ◽  
Wing Length ◽  
Environment Interaction ◽  
Genotype Environment Interaction ◽  
Bristle Number ◽  
Sib Mating ◽  
Mutational Variance ◽  
Interaction Variance

Spontaneous mutations were allowed to accumulate over 209 generations in more than 100 lines, all of them independently derived from a completely homozygous population of Drosophila melanogaster and subsequently maintained under strong inbreeding (equivalent to full-sib mating). Traits scored were: abdominal (AB) and sternopleural (ST) bristle number, wing length (WL) and egg-to-adult viability (V). On two occasions – early (generations 93–122) and late (generations 169–209) – ANOVA estimates of the mutational variance and the mutational line × generation interaction variance were obtained. Mutational heritabilities of morphological traits ranged from 2 × 10−4 to 2 × 10−3 and the mutational coefficient of variation of viability was 0·01. For AB, WL and V, temporal uniformity of the mutational variance was observed. However, a fluctuation of the mutational heritability of ST was detected and could be ascribed to random genotype × environment interaction.

scholarly journals Interactions and developmental effects of mutations in the Broad-Complex of Drosophila melanogaster.

Genetics ◽  
1988 ◽  
Vol 118 (2) ◽  
pp. 247-259
Author(s):  
I Kiss ◽  
A H Beaton ◽  
J Tardiff ◽  
D Fristrom ◽  
J W Fristrom
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Genetic Locus ◽  
Larval Instar ◽  
Imaginal Discs ◽  
Functional Domains ◽  
Developmental Processes ◽  
The Third ◽  
Developmental Effects ◽  
Broad Complex

Abstract The 2B5 region on the X chromosome of Drosophila melanogaster forms an early ecdysone puff at the end of the third larval instar. The region contains a complex genetic locus, the Broad-Complex (BR-C) composed of four groups of fully complementing (br, rbp, l(1)2Bc, and l(1)2Bd) alleles, and classes of noncomplementing (npr 1) and partially noncomplementing l(1)2Bab alleles. BR-C mutants prevent metamorphosis, including the morphogenesis of imaginal discs. Results are presented that indicate that the BR-C contains two major functional domains. One, the br domain is primarily, if not exclusively, involved in the elongation and eversion of appendages by imaginal discs. The second, the l(1)2Bc domain, is primarily involved in the fusion of discs to form a continuous adult epidermis. Nonetheless, the two domains may encode products with related functions because in some situations mutants in both domains appear to affect similar developmental processes.

scholarly journals Drosophila Med6 Is Required for Elevated Expression of a Large but Distinct Set of Developmentally Regulated Genes

2001 ◽  
Vol 21 (15) ◽  
pp. 5242-5255 ◽  
Author(s):  
Byung Soo Gim ◽  
Jin Mo Park ◽  
Jeong Ho Yoon ◽  
Changwon Kang ◽  
Young-Joon Kim
Keyword(s):  
Cell Proliferation ◽  
Drosophila Melanogaster ◽  
Transcriptional Activation ◽  
Larval Instar ◽  
Developmentally Regulated ◽  
The Third ◽  
Reverse Transcription Pcr ◽  
Evolutionarily Conserved ◽  
Elevated Expression

ABSTRACT Mediator is the evolutionarily conserved coactivator required for the integration and recruitment of diverse regulatory signals to basal transcription machinery. To elucidate the functions of metazoan Mediator, we isolated Drosophila melanogaster Med6mutants. dMed6 is essential for viability and/or proliferation of most cells. dMed6 mutants failed to pupate and died in the third larval instar with severe proliferation defects in imaginal discs and other larval mitotic cells. cDNA microarray, quantitative reverse transcription-PCR, and in situ expression analyses of developmentally regulated genes indMed6 mutants showed that transcriptional activation of many, but not all, genes was affected. Among the genes found to be affected were some that play a role in cell proliferation and metabolism. Therefore, dMed6 is required in most cells for transcriptional regulation of many genes important for diverse aspects of Drosophila development.

scholarly journals Genotype-Environment Interaction at Quantitative Trait Loci Affecting Sensory Bristle Number in Drosophila melanogaster

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 1883-1898 ◽  
Author(s):  
Marjorie C Gurganus ◽  
James D Fry ◽  
Sergey V Nuzhdin ◽  
Elena G Pasyukova ◽  
Richard F Lyman ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Quantitative Trait Loci ◽  
Quantitative Trait ◽  
Rank Order ◽  
Recombinant Inbred Lines ◽  
Environment Interaction ◽  
Genotype Environment Interaction ◽  
Bristle Number ◽  
A Genome ◽  
Trait Loci

AbstractThe magnitude of segregating variation for bristle number in Drosophila melanogaster exceeds that predicted from models of mutation-selection balance. To evaluate the hypothesis that genotype-environment interaction (GEI) maintains variation for bristle number in nature, we quantified the extent of GEI for abdominal and sternopleural bristles among 98 recombinant inbred lines, derived from two homozygous laboratory strains, in three temperature environments. There was considerable GEI for both bristle traits, which was mainly attributable to changes in rank order of line means. We conducted a genome-wide screen for quantitative trait loci (QTLs) affecting bristle number in each sex and temperature environment, using a dense (3.2-cM) marker map of polymorphic insertion sites of roo transposable elements. Nine sternopleural and 11 abdominal bristle number QTLs were detected. Significant GEI was exhibited by 14 QTLs, but there was heterogeneity among QTLs in their sensitivity to thermal and sexual environments. To further evaluate the hypothesis that GEI maintains variation for bristle number, we require estimates of allelic effects across environments at genetic loci affecting the traits. This level of resolution may be achievable for Drosophila bristle number because candidate loci affecting bristle development often map to the same location as bristle number QTLs.

scholarly journals CONDITIONAL POLYGENIC EFFECTS IN THE STERNOPLEURAL BRISTLE SYSTEM OF DROSOPHILA MELANOGASTER

Genetics ◽  
1984 ◽  
Vol 108 (2) ◽  
pp. 409-424
Author(s):  
Fred B Schnee ◽  
James N Thompson
Keyword(s):  
Drosophila Melanogaster ◽  
Environment Interaction ◽  
Temperature Dependent ◽  
Genotype Environment Interaction ◽  
Bristle Number ◽  
The Face ◽  
Chromosomal Architecture ◽  
Selection For ◽  
Response To Temperature ◽  
Polygenic Variation

ABSTRACT The chromosomal architecture of genotype × environment interactions was investigated in lines of Drosophila melanogaster selected for increased or decreased sternopleural bristle number at 18°, 25° and 29°. In general, interactions were found to have a stabilizing effect upon the bristle phenotype, in the sense that the genotype × environment interaction tended to increase bristle number under conditions in which temperature alone reduced bristle number and vice versa. The polygenic modifiers of mean bristle number were often separable from modifiers of the response to temperature both at the chromosomal level and intrachromosomally. In one of the low selection lines, a temperature-dependent polygenic locus was mapped on chromosome 3. It is suggested that genotype × environment interactions be thought of in terms of conditional polygenic expression. Such conditionality may be one of the ways in which polygenic variation is maintained in a population in the face of selection for an optimum phenotype.

STUDIES ON NATURAL POPULATIONS OF DROSOPHILA. XII. HETEROSIS AND FITNESS CHARACTERS IN HYBRIDS BETWEEN DIFFERENT POPULATIONS OF DROSOPHILA MELANOGASTER

1970 ◽  
Vol 12 (4) ◽  
pp. 695-710 ◽  
Author(s):  
A. O. Tantawy ◽  
M. R. El-Helw
Keyword(s):  
Drosophila Melanogaster ◽  
Inbred Line ◽  
Egg Production ◽  
Natural Populations ◽  
Relative Fitness ◽  
Environment Interaction ◽  
Population Variance ◽  
Genotype Environment Interaction ◽  
The Poor ◽  
Different Populations

Three different unrelated natural populations of Drosophila melanogaster from Scotland, Japan and Egypt, as well a highly inbred line, were the basis of the present study. Crosses were made within and between natural populations and between each of the natural populations and the highly inbred line to obtain the parental, F1 and F2 generations and their relative fitness studied at 15°, 25° and 28 °C.The F1 interpopulation hybrids were superior to both parents in egg production, percentage emergence and longevity of adults in most of the crosses. Heterosis tended to be higher at 15° and 28° than at 25 °C. The F2 in all crosses was inferior to the F1 and also inferior to one or both parents. In crossing the inbred line with any of the natural populations, the F1 generally showed higher heterosis than that of the interpopulation hybrids; the F2 was also inferior to the F1 but superior to the inbred parent.Significant genotype-environment interaction was detected, indicating the differences in sensitivity to temperature in each population. Variance of any-given fitness character of a superior population at a given temperature was often smaller than the poor genotype. There was a decline in the coefficient of variation in the F1 generation and an increase in the F2's.

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