scholarly journals Genetic and Bioinformatic Analysis of 41C and the 2R Heterochromatin of Drosophila melanogaster: A Window on the Heterochromatin-Euchromatin Junction

Genetics ◽  
2004 ◽  
Vol 166 (2) ◽  
pp. 807-822 ◽  
Author(s):  
Steven H Myster ◽  
Fei Wang ◽  
Robert Cavallo ◽  
Whitney Christian ◽  
Seema Bhotika ◽  
...  

Abstract Genomic sequences provide powerful new tools in genetic analysis, making it possible to combine classical genetics with genomics to characterize the genes in a particular chromosome region. These approaches have been applied successfully to the euchromatin, but analysis of the heterochromatin has lagged somewhat behind. We describe a combined genetic and bioinformatics approach to the base of the right arm of the Drosophila melanogaster second chromosome, at the boundary between pericentric heterochromatin and euchromatin. We used resources provided by the genome project to derive a physical map of the region, examine gene density, and estimate the number of potential genes. We also carried out a large-scale genetic screen for lethal mutations in the region. We identified new alleles of the known essential genes and also identified mutations in 21 novel loci. Fourteen complementation groups map proximal to the assembled sequence. We used PCR to map the endpoints of several deficiencies and used the same set of deficiencies to order the essential genes, correlating the genetic and physical map. This allowed us to assign two of the complementation groups to particular “computed/curated genes” (CGs), one of which is Nipped-A, which our evidence suggests encodes Drosophila Tra1/TRRAP.

Genome ◽  
2007 ◽  
Vol 50 (2) ◽  
pp. 137-141 ◽  
Author(s):  
Sylvia Glen Levine ◽  
Suchot Sunday ◽  
Ruth E. Dörig ◽  
Beat Suter ◽  
Paul Lasko

Drosophila mutants have played an important role in elucidating the physiologic function of genes. Large-scale projects have succeeded in producing mutations in a large proportion of Drosophila genes. Many mutant fly lines have also been produced through the efforts of individual laboratories over the past century. In an effort to make some of these mutants more useful to the research community, we systematically mapped a large number of mutations affecting genes in the proximal half of chromosome arm 2L to more precisely defined regions, defined by deficiency intervals, and, when possible, by individual complementation groups. To further analyze regions 36 and 39–40, we produced 11 new deficiencies with gamma irradiation, and we constructed 6 new deficiencies in region 30–33, using the DrosDel system. trans-heterozygous combinations of deficiencies revealed 5 additional functions, essential for viability or fertility.


Genetics ◽  
1999 ◽  
Vol 153 (1) ◽  
pp. 179-219 ◽  
Author(s):  
M Ashburner ◽  
S Misra ◽  
J Roote ◽  
S E Lewis ◽  
R Blazej ◽  
...  

Abstract A contiguous sequence of nearly 3 Mb from the genome of Drosophila melanogaster has been sequenced from a series of overlapping P1 and BAC clones. This region covers 69 chromosome polytene bands on chromosome arm 2L, including the genetically well-characterized “Adh region.” A computational analysis of the sequence predicts 218 protein-coding genes, 11 tRNAs, and 17 transposable element sequences. At least 38 of the protein-coding genes are arranged in clusters of from 2 to 6 closely related genes, suggesting extensive tandem duplication. The gene density is one protein-coding gene every 13 kb; the transposable element density is one element every 171 kb. Of 73 genes in this region identified by genetic analysis, 49 have been located on the sequence; P-element insertions have been mapped to 43 genes. Ninety-five (44%) of the known and predicted genes match a Drosophila EST, and 144 (66%) have clear similarities to proteins in other organisms. Genes known to have mutant phenotypes are more likely to be represented in cDNA libraries, and far more likely to have products similar to proteins of other organisms, than are genes with no known mutant phenotype. Over 650 chromosome aberration breakpoints map to this chromosome region, and their nonrandom distribution on the genetic map reflects variation in gene spacing on the DNA. This is the first large-scale analysis of the genome of D. melanogaster at the sequence level. In addition to the direct results obtained, this analysis has allowed us to develop and test methods that will be needed to interpret the complete sequence of the genome of this species.


1999 ◽  
Vol 9 (5) ◽  
pp. 471-481
Author(s):  
Maria Teresa Hita ◽  
Maryléne Poirié ◽  
Nathalie Leblanc ◽  
Francoise Lemeunier ◽  
Francoise Lutcher ◽  
...  

Drosophila melanogaster larvae usually react against eggs of the parasitoid wasp Leptopilina boulardi by surrounding them with a multicellular melanotic capsule. The genetic determinism of this response has been studied previously using susceptible (non-capsule-forming) and resistant (capsule-forming) strains. The results suggest that differences in their encapsulation response involve a single gene, resistance to Leptopilina boulardi(Rlb), with two alleles, the resistant one being dominant.Rlb confers specific protection against Leptopilina boulardi and is thus probably involved in parasitoid recognition. Recent studies have localized this gene on the right arm of the second chromosome and our aim was to precisely determine its genetic and molecular location. Using strains bearing deletions, we demonstrated that resistance to Leptopilina boulardi is conferred by the55C; 55F3 region and that the 55E2–E6; F3 region is particularly involved. A physical map of the 55C;56A region was then constructed, based on a set of overlapping cosmid and P1 phage clones. Using single and double digests, cross hybridization of restriction fragments, and location of genetically mapped genes and STSs, a complete, five-enzyme restriction map of this 830-kb region was obtained.


Genetics ◽  
1990 ◽  
Vol 124 (4) ◽  
pp. 889-897
Author(s):  
S Y Tiong ◽  
D Nash

Abstract The Gart gene of Drosophila melanogaster is known, from molecular biological evidence, to encode a polypeptide that serves three enzymatic functions in purine biosynthesis. It is located in polytene chromosome region 27D. One mutation in the gene (ade3(1)) has been described previously. We report here forty new ethyl methanesulfonate-induced mutations selected aga!nst a synthetic deficiency of the region from 27C2-9 to ++28B3-4. The mutations were characterized cytogenetically and by complementation analysis. The analysis apparently identifies 12 simple complementation groups. In addition, two segments of the chromosome exhibit complex complementation behavior. The first, the 28A region, gave three recessive lethals and also contains three known visible mutants, spade (spd), Sternopleural (Sp) and wingless (wg); a complex pattern of genetic interaction in the region incorporates both the new and the previously known mutants. The second region is at 27D, where seven extreme semilethal mutations give a complex complementation pattern that also incorporates ade3(1). Since ade3(1) is defective in one of the enzymatic functions encoded in the Gart gene, we assume the other seven also affect the gene. The complexity of the complementation pattern presumably reflects the functional complexity of the gene product. The phenotypic effects of the mutants at 27D are very similar to those described for ade2 mutations, which also interrupt purine biosynthesis.


Genetics ◽  
1988 ◽  
Vol 120 (3) ◽  
pp. 733-742
Author(s):  
W K Jones ◽  
J M Rawls

Abstract Chromosome region 85A contains at least 12 genetic complementation groups, including the genes dhod, pink and hunchback. In order to better understand the organization of this chromosomal segment and to permit molecular studies of these genes, we have carried out a genetic analysis coupled with a chromosome walk to isolate the DNA containing these genes. Complementation tests with chromosomal deficiencies permitted unambiguous ordering of most of the complementation groups identified within the 85A region. Recombinant bacteriophage clones were isolated that collectively span over 120 kb of 85A DNA and these were used to produce a molecular map of the region. The breakpoint sites of a number of 85A chromosome rearrangements were localized on the molecular map, thereby delimiting regions of the DNA that contain the various genetic complementation groups.


Genetics ◽  
1983 ◽  
Vol 105 (4) ◽  
pp. 957-968
Author(s):  
David Nash ◽  
Frank C Janca

ABSTRACT In a small region of the X chromosome of Drosophila melanogaster, we have found that a third of the mutations that appear to act as lethals in segmental haploids are viable in homozygous mutant individuals. These viable mutations fall into four complementation groups. The most reasonable explanation of these mutations is that they are a subset of functionally hypomorphic alleles of essential genes: hypomorphic mutations with activity levels above a threshold required for survival, but below twice that level, should behave in this manner. We refer to these mutations as "haplo-specific lethal mutations." In studies of autosomal lethals, haplo-specific lethal mutations can be included in lethal complementation tests without being identified as such. Accidental inclusion of disguised haplo-specific lethals in autosomal complementation tests will generate spurious examples of interallelic complementation.


Genetics ◽  
1982 ◽  
Vol 102 (3) ◽  
pp. 401-420
Author(s):  
M Ashburner ◽  
S Tsubota ◽  
R C Woodruff

ABSTRACT Exchange mapping locates the dominant mutation Scutoid to the right of Adh on chromosome arm 2L of D. melanogaster. However, deletion mapping indicates that Sco is to the left of Adh. The phenotype of Sco is sensitive to mutation, or deletion, of noc  + and of three genes, el, l(2)br22, and l(2)br29 mapping immediately distal to noc. The four contiguous loci, el, l(2)br22, l(2)br29 and noc, although separable by deletion end points, interact, because certain (or all) alleles of these four loci show partial failure of complementation, or even negative complementation. The simplest hypothesis is that Sco is a small reciprocal transposition, the genes noc, osp, and Adh exchanging places with three genes normally mapping proximal to them: l(2)br34, l(2)br35 and rd. The Sco phenotype is thought to result from a position effect at the newly created noc/l(2)br28 junction.


Genetics ◽  
1990 ◽  
Vol 125 (4) ◽  
pp. 783-793
Author(s):  
J M Belote ◽  
F M Hoffmann ◽  
M McKeown ◽  
R L Chorsky ◽  
B S Baker

Abstract The 73AD salivary chromosome region of Drosophila melanogaster was subjected to mutational analysis in order to (1) generate a collection of chromosome breakpoints that would allow a correlation between the genetic, cytological and molecular maps of the region and (2) define the number and gross organization of complementation groups within this interval. Eighteen complementation groups were defined and mapped to the 73A2-73B7 region, which is comprised of 17 polytene bands. These complementation groups include the previously known scarlet (st), transformer (tra) and Dominant temperature-sensitive lethal-5 (DTS-5) genes, as well as 13 new recessive lethal complementation groups and one male and female sterile locus. One of the newly identified lethal complementation groups corresponds to the molecularly identified abl locus, and another gene is defined by mutant alleles that exhibit an interaction with the abl mutants. We also recovered several mutations in the 73C1-D1.2 interval, representing two lethal complementation groups, one new visible mutant, plucked (plk), and a previously known visible, dark body (db). There is no evidence of a complex of sex determination genes in the region near tra.


Genetics ◽  
1991 ◽  
Vol 128 (4) ◽  
pp. 763-775 ◽  
Author(s):  
A D Wohlwill ◽  
J J Bonner

Abstract The salivary chromosome region including cytological division 63 of Drosophila melanogaster was genetically analyzed in order to (1) characterize this previously unstudied region and (2) attempt to isolate mutations in the hsp82 gene. Seven deletions which span this region were isolated, including four which remove the hsp82 gene. A Minute mutation was mapped to this region and this Minute was used to isolate duplications in the 63 region. These duplications map the Minute to 63B8-C1. F2 screens were initiated using deletions which remove the hsp82 gene. Over 15,000 chromosomes were screened, yielding 40 lethal mutations which comprise 14 complementation groups. Several of these mutations map outside the 63 region and appear to give second site interaction with the Minute locus. Four loci, including the Minute gene, are candidates for hsp82 mutations by cytogenetic mapping. These loci were tested for complementation with a P element carrying the hsp82 gene. However, none of the mutations was rescued.


Genetics ◽  
2002 ◽  
Vol 160 (4) ◽  
pp. 1503-1510
Author(s):  
Stephanie E Mohr ◽  
Robert E Boswell

Abstract A genetic screen to identify mutations in genes in the 45A region on the right arm of chromosome 2 that are involved in oogenesis in Drosophila was undertaken. Several lethal but no female sterile mutations in the region had previously been identified in screens for P-element insertion or utilizing X rays or EMS as a mutagen. Here we report the identification of EMS-induced mutations in 21 essential loci in the 45D–45F region, including 13 previously unidentified loci. In addition, we isolated three mutant alleles of a newly identified locus required for fertility, sine prole. Mutations in sine prole disrupt spermatogenesis at or before individualization of spermatozoa and cause multiple defects in oogenesis, including inappropriate division of the germline cyst and arrest of oogenesis at stage 4.


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