scholarly journals Cytogenetic Analysis of the Third Chromosome Heterochromatin of Drosophila melanogaster

Genetics ◽  
2002 ◽  
Vol 160 (2) ◽  
pp. 509-517
Author(s):  
Dmitry E Koryakov ◽  
Igor F Zhimulev ◽  
Patrizio Dimitri

Abstract Previous cytological analysis of heterochromatic rearrangements has yielded significant insight into the location and genetic organization of genes mapping to the heterochromatin of chromosomes X, Y, and 2 of Drosophila melanogaster. These studies have greatly facilitated our understanding of the genetic organization of heterochromatic genes. In contrast, the 12 essential genes known to exist within the mitotic heterochromatin of chromosome 3 have remained only imprecisely mapped. As a further step toward establishing a complete map of the heterochomatic genetic functions in Drosophila, we have characterized several rearrangements of chromosome 3 by using banding techniques at the level of mitotic chromosome. Most of the rearrangement breakpoints were located in the dull fluorescent regions h49, h51, and h58, suggesting that these regions correspond to heterochromatic hotspots for rearrangements. We were able to construct a detailed cytogenetic map of chromosome 3 heterochromatin that includes all of the known vital genes. At least 7 genes of the left arm (from l(3)80Fd to l(3)80Fj) map to segment h49–h51, while the most distal genes (from l(3)80Fa to l(3)80Fc) lie within the h47–h49 portion. The two right arm essential genes, l(3)81Fa and l(3)81Fb, are both located within the distal h58 segment. Intriguingly, a major part of chromosome 3 heterochromatin was found to be “empty,” in that it did not contain either known genes or known satellite DNAs.

Genetics ◽  
1996 ◽  
Vol 143 (1) ◽  
pp. 353-364 ◽  
Author(s):  
Jerry A Coyne

Abstract Females of Drosophila melanogaster and its sibling species D. simulans have very different cuticular hydrocarbons, with the former bearing predominantly 7,11-heptacosadiene and the latter 7-tricosene. This difference contributes to reproductive isolation between the species. Genetic analysis shows that this difference maps to only the third chromosome, with the other three chromosomes having no apparent effect. The D. simulans alleles on the left arm of chromosome 3 are largely recessive, allowing us to search for the relevant regions using D. melanogaster deficiencies. At least four nonoverlapping regions of this arm have large effects on the hydrocarbon profile, implying that several genes on this arm are responsible for the species difference. Because the right arm of chromosome 3 also affects the hydrocarbon profile, a minimum of five genes appear to be involved. The large effect of the third chromosome on hydrocarbons has also been reported in the hybridization between D. simulans and its closer relative D. sechellia, implying either an evolutionaly convergence or the retention in D. sechllia of an ancestral sexual dimorphism.


2019 ◽  
Vol 9 (5) ◽  
pp. 1581-1595 ◽  
Author(s):  
Monika Syrzycka ◽  
Graham Hallson ◽  
Kathleen A. Fitzpatrick ◽  
Inho Kim ◽  
Shawn Cotsworth ◽  
...  

Genetics ◽  
1999 ◽  
Vol 153 (2) ◽  
pp. 773-786 ◽  
Author(s):  
Kenneth Weber ◽  
Robert Eisman ◽  
Lisa Morey ◽  
April Patty ◽  
Joshua Sparks ◽  
...  

AbstractLoci on the third chromosome of Drosophila melanogaster that affect an index of wing shape were mapped, using recombinant isogenic lines, with transposable elements as markers. Many genes with small subequal effects are dispersed along the whole chromosome. Their alleles act nearly additively in heterozygotes. They have small correlated effects on leg shape, but no detectable effects on halteres. Small negative net interactions occur over most of the chromosome. The data set of 519 recombinant isogenic lines can be explained reasonably well by two models. One model posits an indefinitely large number of loci with no interactions. The other model posits 11 loci with additive effects whose sum equals the total phenotypic range and with large positive and negative interactions that nearly cancel each other.


2020 ◽  
Author(s):  
Xiaolu Wei ◽  
Danna G. Eickbush ◽  
Iain Speece ◽  
Amanda M. Larracuente

ABSTRACTLarge blocks of tandemly repeated DNAs—satellite DNAs (satDNAs)—play important roles in heterochromatin formation and chromosome segregation. We know little about how satDNAs are regulated, however their misregulation is associated with genomic instability and human diseases. We use the Drosophila melanogaster germline as a model to study the regulation of satDNA transcription and chromatin. Here we show that complex satDNAs (>100-bp repeat units) are transcribed into long noncoding RNAs and processed into piRNAs (PIWI interacting RNAs). This satDNA piRNA production depends on the Rhino-Deadlock-Cutoff complex and the transcription factor Moonshiner—a previously-described non-canonical pathway that licenses heterochromatin-dependent transcription of dual-strand piRNA clusters. We show that this pathway is important for establishing heterochromatin at satDNAs. Therefore, satDNAs are regulated by piRNAs originating from their own genomic loci. This novel mechanism of satDNA regulation provides insight into the role of piRNA pathways in heterochromatin formation and genome stability.


Genetics ◽  
1995 ◽  
Vol 139 (3) ◽  
pp. 1273-1291 ◽  
Author(s):  
A D Long ◽  
S L Mullaney ◽  
L A Reid ◽  
J D Fry ◽  
C H Langley ◽  
...  

Abstract Factors responsible for selection response for abdominal bristle number and correlated responses in sternopleural bristle number were mapped to the X and third chromosome of Drosophila melanogaster. Lines divergent for high and low abdominal bristle number were created by 25 generations of artificial selection from a large base population, with an intensity of 25 individuals of each sex selected from 100 individuals of each sex scored per generation. Isogenic chromosome substitution lines in which the high (H) X or third chromosome were placed in an isogenic low (L) background were derived from the selection lines and from the 93 recombinant isogenic (RI) HL X and 67 RI chromosome 3 lines constructed from them. Highly polymorphic neutral roo transposable elements were hybridized in situ to the polytene chromosomes of the RI lines to create a set of cytogenetic markers. These techniques yielded a dense map with an average spacing of 4 cM between informative markers. Factors affecting bristle number, and relative viability of the chromosome 3 RI lines, were mapped using a multiple regression interval mapping approach, conditioning on all markers > or = 10 cM from the tested interval. Two factors with large effects on abdominal bristle number were mapped on the X chromosome and five factors on the third chromosome. One factor with a large effect on sternopleural bristle number was mapped to the X and two were mapped to the third chromosome; all factors with sternopleural effects corresponded to those with effects on abdominal bristle number. Two of the chromosome 3 factors with large effects on abdominal bristle number were also associated with reduced viability. Significant sex-specific effects and epistatic interactions between mapped factors of the same order of magnitude as the additive effects were observed. All factors mapped to the approximate positions of likely candidate loci (ASC, bb, emc, h, mab, Dl and E(spl), previously characterized by mutations with large effects on bristle number.


Genetics ◽  
1988 ◽  
Vol 120 (2) ◽  
pp. 503-517
Author(s):  
G E Marchant ◽  
D G Holm

Abstract The heterochromatin of the third chromosome is the largest uncharacterized region of the Drosophila melanogaster genome, and the last major block of D. melanogaster heterochromatin to be thoroughly analyzed. In the present study, this region was genetically dissected by generating and analyzing a series of attached, detached and reattached third chromosomes. Separate detachment experiments were conducted for all 12 possible combinations of four newly synthesized sister-strand compound-3L and three newly synthesized sister-strand compound-3R chromosomes. A total of 443 recessive lethal detachment products carrying putative heterochromatic deficiencies were tested for complementation in a several-stage complementation analysis. The results revealed the presence of seven separable vital regions in the heterochromatin of chromosome 3. Attempts to reattach deficiency-carrying detachment products established that six of these vital regions are on the left arm, but only one is on the right arm. An analysis of the types and frequencies of detachment-product deficiencies generated in each detachment experiment permitted the genetic characterization of the progenitor compounds. It was also possible to determine the proximal-distal orientation of the genes on each arm, and to identify possible breakpoints for each lethal detachment product produced. The results of this study suggest that vital genes in the heterochromatin of the third chromosome are not randomly distributed between, nor within, the heterochromatic blocks of the left and right arms.


eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Xiaolu Wei ◽  
Danna G Eickbush ◽  
Iain Speece ◽  
Amanda M Larracuente

Large blocks of tandemly repeated DNAs-satellite DNAs (satDNAs)-play important roles in heterochromatin formation and chromosome segregation. We know little about how satDNAs are regulated, however their misregulation is associated with genomic instability and human diseases. We use the Drosophila melanogaster germline as a model to study the regulation of satDNA transcription and chromatin. Here we show that complex satDNAs (>100-bp repeat units) are transcribed into long noncoding RNAs and processed into piRNAs (PIWI interacting RNAs). This satDNA piRNA production depends on the Rhino-Deadlock-Cutoff complex and the transcription factor Moonshiner—a previously-described non-canonical pathway that licenses heterochromatin-dependent transcription of dual-strand piRNA clusters. We show that this pathway is important for establishing heterochromatin at satDNAs. Therefore, satDNAs are regulated by piRNAs originating from their own genomic loci. This novel mechanism of satDNA regulation provides insight into the role of piRNA pathways in heterochromatin formation and genome stability.


10.1558/37291 ◽  
2018 ◽  
Vol 2 (2) ◽  
pp. 242-263
Author(s):  
Stefano Rastelli ◽  
Kook-Hee Gil

This paper offers a new insight into GenSLA classroom research in light of recent developments in the Minimalist Program (MP). Recent research in GenSLA has shown how generative linguistics and acquisition studies can inform the language classroom, mostly focusing on what linguistic aspects of target properties should be integrated as a part of the classroom input. Based on insights from Chomsky’s ‘three factors for language design’ – which bring together the Faculty of Language, input and general principles of economy and efficient computation (the third factor effect) for language development – we put forward a theoretical rationale for how classroom research can offer a unique environment to test the learnability in L2 through the statistical enhancement of the input to which learners are exposed.


2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Colby Doyle ◽  
Matthew Gaudet ◽  
Dominic Lay ◽  
Amber McLeod ◽  
Robert Schaeffer

The primary goal of this research is to identify and examine the components of responsible drinking advertisements. We will examine industry and government related advertisements as we try to understand one of our major questions: does the source influence the validity of the message? The next group of major questions that we will be looking to answer is how are the vague quantifiers used in responsible drinking campaigns interpreted by the public?  How many drinks do people consider “too much?” What does “drink responsibly” really mean? The third major question is whether or not an individual’s current consumption patterns of alcohol have any effect on how individuals assess responsible drinking campaigns. Our qualitative research has indicated that social influences can be strongly related with drinking patterns; this will be further examined in our quantitative research. Also, we will be looking into some of the psychology behind industry and government sponsored advertisements as well as gathering and interpreting information from a sample of our target demographic. Our target demographic consists of both male and females between the ages 18-24. Our literature review and qualitative analysis gave us good insight into some of the potential answers to our questions. We will use these potential answers from our previous research to guide us as we attempt to conduct conclusive research based on a sample data of 169 individuals. Our findings will aid us in developing conclusions and recommendations for Alberta Health Services.


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