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At least 325 records · Page 18Linked to original sources
PubMed1996

The Afrotropical Drosophila montium subgroup: Balbiani ring 1, polytene chromosomes, and heat shock response of Drosophila vulcana.

A detailed photographic map of the salivary gland polytene chromosomes of Drosophila vulcana, an Afrotropical species of the montium subgroup of the melanogaster group, is presented, along with chromosomal rearrangements, such as reverse tandem duplications and inversions, the well-formed Balbiani ring 1, and the most prominent puffs during normal larval and white prepupal development and after ecdysone treatment. In addition, the heat inducible protein and puffing pattern and the loci of the major heat shock genes, namely, hsp70, hsp83, the "small" hsps, and a putative hsp68, of this species were studied. In the light of the data revealed by the above studies, phylogenetic relationship among the montium subgroup species are attempted.

Africa↗
PubMed2001

Autoradiographic study of transcription and dosage compensation in the sex and neo-sex chromosome of Drosophila nasuta nasuta and Drosophila nasuta albomicans.

Cellular autoradiography is used to study the transcription patterns of the polytene X chromosomes in Drosophila nasuta nasuta and D. n. albomicans. D. n. nasuta, with 2n = 8, includes a pair of complete heteromorphic sex chromosomes, whereas D. n. albomicans, with 2n = 6, has a pair of metacentric neo-sex chromosomes representing incomplete heteromorphic sex chromosomes. The neo-X chromosome has two euchromatic arms, one representing the ancestral X while the other represents the ancestral autosome 3 chromosomes. The metacentric neo-Y chromosome has one arm with a complete heterochromatic ancestral Y and the other arm with a euchromatic ancestral autosome 3. The transcription study has revealed that the X chromosome in D. n. nasuta is hyperactive, suggesting complete dosage compensation, while in the neo-X chromosome of D. n. albomicans the ancestral X chromosome is hyperactive and the ancestral autosome 3, which is part of the neo-sex chromosome, is similar to any other autosomes. This finding shows dosage compensation on one arm (XLx/-) of the neo-X chromosome, while the other arm (XR3/YR3) is not dosage compensated and has yet to acquire the dosage compensatory mechanism.

Animals↗
PubMed1995

Adaptive significance of amylase polymorphism in Drosophila. X. Analysis of alpha-amylase activity of two amylase variants in individual Drosophila subobscura flies.

Experiments were designed to estimate the variation of alpha-amylase activity in Drosophila subobscura individuals homozygous for AmyS and AmyF alleles at the Amy locus. The measurements of enzyme activities in six groups of male progenies determined in each individual have shown that degree of variation differs between S and F strains. Variability of amylase activity among male progenies of S strain was substantially greater, which also had significantly higher specific amylase activity than in F strain. The analysis of amylase activity variance showed that this variance among the males is 40 times, and among the females 2.7 times smaller in F than in S strain.

Adaptation, Biological↗
PubMed2002

Phylogenetic position of Chinese endemic Drosophila curviceps species subgroup in the Drosophila immigrans group.

In order to investigate the phylogenetic position of Chinese endemic Drosophila curviceps species subgroup within the D. immigrans group on DNA molecular level, the ITS1 region of ribosomal DNA and part of Adh gene for 12 species represented all the five subgroups in D. immigrans group were sequenced. Molecular phylogenetic trees were constructed by using parsimony and neighbor-joining methods based on ITS1, Adh and combined sequences. In the molecular trees, species of the D. curviceps subgroup cluster together, strongly supporting establishment of a separating subgroup suggested in an initial morphologic study. This subgroup is the sister taxa of the D. quadrilineata subgroup. They are the younger subgroups, splitting about 3.4 Mya. The D. hypocausta subgroup is located at the base of the molecular tree, diverged first in this group about 9.2 Mya. Taking the geographic distribution into account, we can conclude that D. curviceps subgroup originated from tropic zones, agreeing with the previous morphologic and biogeographic suggestions. The position of D. neohypocausta was also discussed in this report and it seems that it is closer to the D. immigrans subgroup than to the D. hypocausta subgroup.

Alcohol Dehydrogenase↗
PubMed1976

[Further experiments on the conditioning and pseudoconditioning of the tarsal reflex in the drosophila (Drosophila melanogaster): effect of low intensity electric shocks].

In a recently described procedure of negative instrumental conditioning, applied to the tarsal reflex of Drosophila (Médioni and Vaysse, 1975), it was attempted to eliminate some "noise" sources superimposed on the associative conditioning effect. 1) By increasing the preliminary reiteration of the sugar stimulus (US for the tarsal reflex), the suppressive influence of "desensitization" (i.e. sensory adaptation and/or central habituation) could be minimized, at least in the first 20 trials of the training phase. 2) By lowering the intensity of the electrical shock used as an aversive reinforcer, the pseudo-conditioning rate could be substantially reduced too. However the relative weight of the pseudoconditioninq effects could not be decreased by these means: for the effectiveness of the mild shock became weaker for the "true" conditioning as well.

Animals↗
PubMed2006

New evidence for nucleolar dominance in hybrids of Drosophila arizonae and Drosophila mulleri.

Drosophila mulleri (MU) and D. arizonae (AR) are cryptic species of the mulleri complex, mulleri subgroup, repleta group. Earlier cytogenetic studies revealed that these species have different regulatory mechanisms of nucleolar organizing activity. In these species, nucleolar organizing regions are found in both the X chromosome and the microchromosome. In the salivary glands of hybrids between MU females and AR males, there is an interspecific dominance of the regulatory system of the D. arizonae nucleolar organizer involving, in males, amplification and activation of the nucleolar organizer from the microchromosome. The authors who reported these findings obtained hybrids only in that cross-direction. More recently, hybrids in the opposite direction, i.e., between MU males and AR females, have been obtained. The purpose of the present study was to evaluate, in these hybrids, the association of the nucleoli with the chromosomes inherited from parental species in order to cytogenetically confirm the dominance patterns previously described. Our results support the proposed dominance of the AR nucleolar organizer activity over that of MU, regardless of cross-direction.

Animals↗
PubMed1991

[Cytogenetic analysis of chromosome segments containing radiosensitivity genes in Drosophila. Radiation mutagenesis in the 44-45 region of chromosome 2 of Drosophila melanogaster].

The first step of cytogenetic analysis of Drosophila melanogaster chromosome 2 44F-45D containing the radiosensitivity gene rad(2)201 is described. Using various mutation selection systems as well as lines of different origin and two kinds of ionizing radiation--gamma-rays and neutrons--the mutagenesis in the region of interest is characterized at the cytogenetic level. 85 gamma-induced mutations affecting viability were isolated in the 44F 2-4; 45C6-7 interval, 27% of mutations being chromosomal aberrations. 15 radiation-induced aberrations were obtained by selecting mutations at the white gene inserted into the 45D region by P-mediated transformation. The 44F-45D region is characterized by relatively low frequency of deficiency formation and by significant predomination of heterochromatic aberrations in the spectrum of rearrangements. In these regions, the existence of hot spots for heterochromatic aberrations was discovered. As low deletion frequency is not connected with the presence of haplolethal and haplosterile loci in the region studied, the unusual character of radiation mutagenesis reflects possibly the peculiarities in sequence organization of the chromosomal region mentioned or the packaging in the sperm nuclei.

Animals↗
PubMed1977

[Analysis of mutations induced by alkylating compounds in Drosophila sperm. I. Character of visible changes induced by N-nitrosoethylurea and ethylmethanesulfonate in a succession of Drosophila generations].

Newly appearing hereditary traits were observed in several generations of Drosophila melanogaster: changes in eye and body colour, wing shape, number and shape of chaetae. The results obtained may be interpreted as the evidence for the realization of potential changes induced by NEU and EMS into visible mutations during 1-4th generations. X-irradiation (at a dose of 1000 r) of males from the first generation did not affect the realization of long-living potential changes induced by NEU.

Animals↗
PubMed1987

[Molecular genetic study of the cut locus of Drosophila melanogaster. V. The suffix sequence found in the locus is involved in the 3'-end maturation of different Drosophila mRNAs].

The nucleotide sequences of 8 genomic and 2 mRNA copies of the suffix were studied. It was found that this short repeat (265 bp) forms the last exon (73 bp) in different developmentally regulated Drosophila genes. The functioning genes contain short insertions carrying polyadenylation signals and polyadenylation sites at the same position of the suffix. It was shown that the suffix sequence is directly involved in the formation of the last splicing site and 3'-end maturation of mRNA.

Animals↗
PubMed1985

[Radiosensitive Drosophila lines. VIII. The effect of the mus (201)Gl gene of Drosophila melanogaster on the sensitivity of the flies to ultraviolet rays in the imago stage].

The effect of UV-light on survival of adult flies of the mutant line mus(2) 201G1 sensitive to methyl methanesulfonate (MMS) was studied. One day old flies were irradiated by UV-light and the survival was determined depending on the UV dose, the genotype and the sex of irradiated flies. High sensitivity of mutant flies was shown in the imaginal stage when division of somatic cells was absent. Moreover, the differences in sensitivity to UV-light were observed depending on the sex of flies. We suggest that the mutation mus(2)201G1 blocking the excision repair affects undivisional cells of the imaginal stage of Drosophila melanogaster.

Animals↗
PubMed1993

[Drosophila beta-heterochromatin: molecular organization and function. Characteristics of the DNA sequences from proximal beta-heterochromatin, associated with the nuclear envelope of Drosophila melanogaster].

To study the nucleotide sequence from the pericentric heterochromatin associated with the nuclear envelope, a residual DNA was extracted from the DNAse-treated nuclear lamins of Drosophila melanogaster tissue culture cell line Kc. The isolated DNA was cloned in lambda vector. The DNA library obtained was screened for the clones homologous to the pericentric heterochromatin. The experiments on in situ hybridization to the polytene chromosome of the nurse cell nuclei of the strain fs(2) B assigned the reiterated sequence, homologous to the lamin DNA clone, to the nuclear envelope associated regions of the proximal beta-heterochromatin which is known to undergo structural reorganization during cell differentiation. The nucleotide analysis of 300 bp from this sequence has established the presence of 21 bp and 300 bp d(GT/CA), 12 bp AT-box, the regions of recognition of the nuclear factor and the inverted repeats.

Animals↗
PubMed1996

[Beta-heterochromatin in Drosophila: molecular organization and function. Molecular biological analysis of a MAR/SAR DNA sequence in centromere heterochromatin of Drosophila melanogaster].

A molecular biological characteristic of a DNA fragment delta 20p1.4, which is a moderately repetitive sequence of the Drosophila melanogaster genome, is presented. The fragment is present in about 120 copies per haploid genome. The main pool of the delta 20p1.4 homologous DNA can be isolated, along with the nuclear matrix DNA, and consists of Hind III-EcoR I monomers 1.4-1.6 kb in length. The monomers may occur in the genome as both single copies and tandem clusters forming chromosomes fragments up to 6-10 kb in length. The region of the delta 20p1.4 fragment between nucleotides 350 and 905 polymerizes with purified lamin from D. melanogaster. The sites of the fragment that had physical contact with lamin in vitro were determined using an Exo III protection. It was demonstrated that ATATTT, A, and T boxes located in four nonperfect tandem repeats were involved in the contact, both DNA strains reacting with lamin.

Animals↗
PubMed1997

[Genomic incompatibility in Drosophila virilis Sturt. X Drosophila lummei Hackman hybrids].

Genetic analysis of male sterility in Drosophila virilis x D. lummei hybrids was performed. It was shown that hybrid male sterility was caused mainly by incompatibility of sex chromosomes X and Y and homozygous chromosome 2 of D. virilis with other autosomes of D. lummei. Genes of chromosomes 3 and 5 enhanced sterility whereas genes of chromosome 4 suppressed its development. Factors controlling hybrid male sterility were demonstrated to have a recessive type of inheritance. At 17 degrees C, chromosome 6 of D. lummei was eliminated in F1 hybrids of the cross female D. virilis x male D. lummei. At 17 degrees C and 25 degrees C, sterility of the F1 hybrid males was 96% and 9%, respectively. Thus, two isolation mechanisms-elimination of chromosome 6 and male sterility-can simultaneously operate in F1. In addition to the region of the species-specific inversion In 1(a+b), factors controlling male sterility were mapped to the vermillion region of the X chromosome.

Animals↗
PubMed1997

The Afrotropical Drosophila montium subgroup: Balbiani ring 1 and polytene chromosomes of Drosophila nikananu.

Drosophila nikananu, an Afrotropical species, belongs to the montium subgroup of the melanogaster species. Photographic maps of the salivary gland chromosomes are presented, as well as data on their most prominent puffs during late larval and white prepupal development and, after in vitro ecdysone treatment, their reverse tandem duplications, and the well-formed Balbiani ring 1. The data are discussed and compared with those of other montium species.

Africa↗