Search results for "Cytogenetic"
showing 10 items of 159 documents
Cytogenetics in the sacoglossan Oxynoe olivacea (Mollusca: Opisthobranchia): karyotype, chromosome banding and fluorescent in situ hybridization
2000
Developing embryos and sexually mature follicles of the male portion of ovotestis proved to be a suitable material as a source of cleaving cells for advanced cytological investigations on the sacoglossan species Oxynoe olivacea Rafinesque, 1819 (Mollusca: Opisthobranchia). O. olivacea has a diploid chromosomal number of 30 made up of 15 pairs of which six are metacentric/submetacentric (M/SM), four subtelocentric (ST) and five on the borderline between SM and ST. Correspondingly, 15 bivalents occur in spermatocytes at Metaphase I. Constitutive heterochromatin is scarce and restricted to small C-bands seen in five pachytene bivalents. The use of combined silver staining and fluorescent in si…
Ag-NOR and C-banding analysis of spermatocyte chromosomes ofClavelina lepadiformis(Ascidiacea, Aplousobranchiata)
1991
SUMMARYChromosome number n = 9 and 2n = 18 for Clavelina lepadiformis (Ascidiacea, Aplousobranchiata) from the Gulf of Palermo have been determined. Silver staining analysis of testicular cells reveals that within-individual variability in NOR banding patterns is present. Using the C-banding procedure, a very impressive heterochromatin amount seems to characterize the chromosome set of this species.
Brief communication. Karyotype analysis, banding, and fluorescent in situ hybridization in the scarab beetle Gymnopleurus sturmi McLeay (Coleoptera S…
2000
Conventional staining, differential banding, and in situ hybridization with both ribosomal and telomeric probes to mitotic chromosomes of Gymnopleurus sturmi (Scarabaeoidea : Scarabaeidae) are described. The karyotype is distinguished by a pericentric inversion polymorphism in chromosome 3, which is either acrocentric or subtelocentric. Silver staining (Ag-NOR) and chromomycin A3 (CMA3), failed to study the detection of nucleolar organizer regions (NORs), due to the extensive silver and CMA3 stainability of all GC-rich heterochromatin. Fluorescent in situ hybridization (FISH) using a Paracentrotus lividus (Echinodermata) rDNA probe mapped the ribosomal RNA genes (rDNA). FISH with the all-hu…
PATTERNS OF PUFFING ACTIVITY AND CHROMOSOMAL POLYMORPHISM IN DROSOPHILA SUBOBSCURA . IV. EFFECT OF INVERSIONS ON GENE EXPRESSION
1988
We have observed that, contrary to a common assumption, the puffing patterns manifest in the salivary chromosomes of Drosophila subobscura are modified by chromosomal inversions as well as by genic content. An inversion effect is apparent in the E and A chromosomes of five strains coming from four different natural populations. An effect due to the geographical location of the populations is also detected in the J and O chromosomes. The chromosomal and geographic effects are distinguishable but not contradictory. Indeed, a statistical test using the DK2 coefficient of distance shows that, for a given chromosomal arrangement, strains of different geographic origin exhibit puffing patterns si…
Gene activity of polytene chromosomes in Drosophila species of the obscura group.
1988
The polytene chromosome puffing patterns of Drosophila guanche were established and compared with those of Drosophila subobscura. A total of 150 loci, active in some of the 17 developmental stages studied, were described and 23 of them were found to form the characteristic puffing pattern of D. guanche. Taking into account the number of puffs as well as the gene activity of each chromosome and the total gene activity, D. guanche seems to be less active than D. subobscura. Although both species show a degree of homology in their puffing patterns lower than that found for sibling species, the degree of homology is stronger than that between species belonging to the same group but to different…
Patterns of puffing activity and chromosomal polymorphism in Drosophila subobscura II. Puffing patterns at the prepupa stage
1985
Puffing activity patterns of the five large polytene chromosomes of Drosophila subobscura were studied during the late third-larval instar and through the prepupal period. A total of 166 loci active in some of the eleven stages studied were described. The distribution of these active loci per chromosome is the following: 25 on chromosome A, 33 on chromosome J, 31 on chromosome U, 34 on chromosome E and 43 on chromosome O. Seven principal patterns of puffing activity were defined taking into account the different curves of the puffing histograms. Gene activities per chromosome as well as total were analysed. Three peaks of gene activity at the beginning, middle and ending of prepupation can …
Differences in gene activity in a Drosophila species cluster belonging to the Obscura group
1993
The polytene chromosome puffing pattern of Drosophila madeirensis was established and compared with those of the related species D. subobscura and D. guanche. A total of 145 loci, active in some of the 12 developmental stages analysed, were described, 38 of which were found to form the puffing pattern characteristic to this species. Taking into account the number of puffs as well as the mean puff expression, D. madeirensis shows a similar activity level to D. guanche, both species being less active than D. subobscura. The low gene activity of D. madeirensis and D. guanche was explained as a consequence of their ecological characteristics.
Karyotype analysis, nucleolar organizer regions(NORs), and C-banding pattern of Dicentrarchus iabrax(L.) and Dicentrarchus punctatus(Block, 1792)(Pis…
1990
Chromosomes of Dicentrarchus labrax and Dicentrarchus punctatus collected from the Gulf of Palermo are examined from kidney cells. The diploid chromosome number in both species is 2n=48. Ag-NOR and C-banding analyses revealed the presence of structural chromosomal polymorphism involving pair 1.A comparative analysis among the Giemsa, NOR- and C-banded karyotypes suggests that a close phylogenetic relationship between D. labrax and D. punctatus occurs. There are evidences for a conservative evolutionary trend in this genus.
Chromosomal polymorphism associated with Robertsonian fusion in Seriola dumerili (Risso, 1810) (Pisces: Carangidae)
1986
The diploid numbers 2n= 48, and 2n= 47 have been determined for the greater amberjack, Seriola dumerili. A chromosome polymorphism due to Robertsonian fusion is present in this species. A simple sex-determining mechanism has not been observed.
Spermatocyte chromosome banding studies inBuccinulum corneum (Prosobranchia: Neogastropoda): Variation in silver-NOR banding pattern
1990
Diploid number (2n=72), and haploid number (n=36) forBuccinulum corneum (L. 1758) collected from the Gulf of Palermo in December 1987 were determined. A simple method to obtain nucleolar organizer regions (NOR), and constitutive heterochromatin regions (C-bands) of chromosomes ofB. corneum is described. Analyses of silver-stained chromosome preparations ofB. corneum suggest that a within-individual variability in NOR-banding pattern is present in each of the five specimens analysed.