Search results for "Polytene chromosome"

Chironomus riparius(Diptera) genome sequencing reveals the impact of minisatellite transposable elements on population divergence

2016

AbstractActive transposable elements (TEs) may result in divergent genomic insertion and abundance patterns among conspecific populations. Upon secondary contact, such divergent genetic backgrounds can theoretically give rise to classical Dobzhansky-Muller incompatibilities (DMI), a way how TEs can contribute to the evolution of endogenous genetic barriers and eventually population divergence. We investigated whether differential TE activity created endogenous selection pressures among conspecific populations of the non-biting midgeChironomus riparius,focussing on aChironomus-specific TE, the minisatellite-likeCla-element, whose activity is associated with speciation in the genus. Using an …

Ultrastructure of regions containing homologous loci in polytene chromosomes of Drosophila melanogaster and Drosophila subobscura.

1998

We have used a new approach involving in situ hybridisation and electron microscopy to establish ultrastructural homologies between polytene chromosome regions of Drosophila melanogaster and Drosophila subobscura. Twelve probes were chosen to cover all the chromosomal elements: the myospheroid gene, the collagen type IV gene, the collagen-like gene, the w26 homeobox gene, the beta3 tubulin gene, the kinesin heavy chain gene, the tryptophan hydrolase gene, the Hsp82, Hsp22-26 and Hsp23-28, Hsp68, Hsp70 genes and the beta unit of the F0-F1 ATPase gene. Most of these loci were previously undescribed in D. subobscura and imprecisely located in D. melanogaster. We have demonstrated here, by an u…

P/CAF-mediated spermidine acetylation regulates histone acetyltransferase activity

2016

Histones and polyamines are important determinants of the chromatin structure. Histones form the core of nucleosome particles and their modification by acetylation of N-terminal tails is involved in chromatin structural changes and transcriptional regulation. Polyamines, including spermidine, are also targets of both cytoplasmic and nuclear acetylation, which in turn alters their affinity for DNA and nucleosomes. Previous studies report the interplay between polyamines metabolism and levels of histone acetylation, but the molecular basis of this effect is still unclear. In this work, we have analyzed the in vitro effect of spermidine on histone H3 acetylation catalyzed by P/CAF, a highly co…

Development and localization of microsatellite markers for the sibling species Chironomus riparius and Chironomus piger (Diptera: Chironomidae)

2006

Five variable microsatellite loci are reported for the nonbiting midge species Chironomus riparius and Chironomus piger. All loci show considerable intraspecific variation and species-specific alleles, which allow to discriminate among the two closely related species and their interspecific hybrids, and to estimate genetic diversity within and between populations. Additionally, the loci were localized on C. riparius polytene chromosomes to verify their single copy status and investigate possible chromosomal linkage. The described markers are used in different studies with regard to population and ecological genetics and evolutionary ecotoxicology of Chironomus.

Tumor suppression inDrosophila is causally related to the function of thelethal(2)tumorous imaginal discs gene, adnaJ homolog

1995

The Drosophila melanogaster tumor suppressor gene lethal(2)tumorous imaginal discs (l(2)tid) causes in homozygotes malignant growth of cells of the imaginal discs and the death of the mutant larvae at the time of puparium formation. We describe the molecular cloning of the l(2)tid+ gene and its temporal expression pattern in the wild-type and mutant alleles. Germ line rescue of the tumor phenotype was achieved with a 7.0 kb Hindlll-fragment derived from the polytene chromosome band 59F5. The l(2)tid+ gene spans approximately 2.5 kb of genomic DNA. The protein coding region, 1,696 bps long, is divided by an intron into two exons. The predicted Tid56 protein contains 518 amino acids and posse…

The Mutation without childrenrgl Causes Ecdysteroid Deficiency in Third-Instar Larvae of Drosophila melanogaster

2000

Larvae homozygous for the recessive lethal allele without children(rgl) (woc(rgl)) fail to pupariate. Application of exogenous 20-hydroxyecdysone elicits puparium formation and pupation. Ecdysteroid titer measurements on mutant larvae show an endocrine deficiency in the brain-ring gland complex, which normally synthesizes ecdysone, resulting in a failure of the larvae to achieve a threshold whole body hormone titer necessary for molting. Ultrastructural investigation revealed extensive degeneration of the prothoracic cells of the ring gland in older larvae. The woc gene, located in polytene chromosomal region 97F, consists of 11 exons. A 6.8-kb transcript is expressed throughout development…

Immuno-Fluorescence (IF) on interphase polytene chromosomes of Drosophila melanogaster

2008

Interspecific transgenic analysis of basal versus heat-shock-induced expression of a Drosophila pseudoobscura hsp82-neo fusion gene in D. melanogaster

1994

Drosophila melanogaster transformants containing a D. pseudoobscura hsp82-neo fusion gene were used to examine the relationship between chromosome structure and its variation to transcriptional activation and gene expression. At normal temperatures (25° C) transgenic hsp82-neo was transcribed in diffuse polytene chromosomal bands encoding antibiotic G418-resistance without intensive puff formation. Substantial basal expression of the transgene was observed in all tissues examined: salivary glands, brain, ventral ganglion, foregut, gastric caeca, midgut, imaginal discs, nurse cells and oocytes. In addition, basal hsp82-neo expression occurred throughout embryogenesis. In third-instar larvae …

Sequence and evolution of the gene for the monomeric globin I and its linkage to genes coding for dimeric globins in the insect Chironomus thummi.

1995

We isolated genomic clones containing sequences encoding globins I and IA from a Chironomus thummi thummi genomic library. Three clones contain globin IA (ctt-1A) genes, while one contains a globin I (ctt-1) gene. The coding regions of the four genes are identical except for the single base substitution accounting for the globin I/IA polymorphism. The noncoding DNA flanking the coding region is more than 98% similar, confirming a previous hypothesis that the globin ctt-1 and ctt-1A genes are alleles. Hemoglobins I and IA are monomeric in the insect hemolymph. Earlier in situ hybridization studies suggested that monomeric and dimeric globin genes are clustered at different chromosomal loci. …

Genome instability ofChironomus ripariusMg. andChironomus pigerStrenzke (Diptera, Chironomidae)

2007

Intra and interspecific variation was evaluated in two Bulgarian populations (Pancharevo and Koka- lijane) of the two sibling and homosequential species Chironomus riparius Mg. and Chironomus piger Strenzke, by analyzing structural and functional alterations in salivary gland polytene chromosomes. In both species genome in- stability was demonstrated, which was expressed by structural and functional somatic chromosomal alterations. In the C. riparius population from Pancharevo, living in sediments containing high concentrations of Cu, Pb and Zn, salivary gland cells containing somatic rearrangements appeared at a significantly higher frequency (51.92%) than in the Kokalijane C. piger popula…