DIFFERENTIATION OF DROSOPHILA-SERIDO (ISOFEMALE LINE A95F3) AND D-KOEPFERAE (ISOFEMALE LINE B20D2) - REPRODUCTIVE ISOLATION, DEVELOPMENT TIME AND POLYTENE CHROMOSOME-BANDING PATTERNS

Drosophila serido is considered to be a superspecies consisting of two species: D. serido, from Brazil and D. koepferae from Argentina and Bolivia. However this probably does not express the entire evolutionary complexity of its populations. Isofemale lines A95F3 (from Brazil) and B20D2 (from Argentina), at present representing, respectively, the first and second species, were analyzed for fertility and fecundity in pair-mating intracrosses and intercrosses, as well as for development time, banding patterns and asynapsis of polytene chromosomes in the isofemale lines and their hybrids.Although variations in experimental conditions resulted in some variability in the results, in general A95F3 fertility and fecundity were lower than in B20D2. Intercrosses of A95F3 females and B20D2 males showed lower fertility and fecundity than the reciprocal crosses, following more closely characteristics of the mother strains. This is in contrast to the results obtained by Fontdevilla et al. (An. Entomol. Soc. Amer. 81: 380-385, 1988) and may be due to the different geographic origin of D. serido strains they used in crosses to B20D2. This difference and others cited in the literature relative to aedeagus morphology, karyotype characteristics, inversion polymorphisms and reproductive isolation strongly indicate that A95F3 and D. serido from the State of Bahia, Brazil are not a single evolutionary entity, reinforcing the idea of greater complexity of the superspecies D. serido than is known today.The reproductive isolation mechanisms found operating between A95F3 and B20D2 were prezygotic and postzygotic, the latter included mortality at the larvae stage in both directions of crosses and sterility of male hybrids in intercrosses involving B20D2 females and A95F3 males. The two isofemale lines differed in egg-adult development time, which was also differently affected by culture medium composition.A95F3 and B20D2 also showed differences in the banding patterns of proximal regions of polytene chromosomes 2, 3 and X, a fixed inversion in chromosome 3 (here named 3t), apparently not described previously, and a high degree of asynapsis in hybrids.These observations, especially those related to reproductive isolation and chromosomal differentiation (including the karyotype, previously described, and the differentiation of banding patterns, described in this paper), as well as the extensive asynapsis observed in hybrids reinforces the distinct species status of A95F3 and B20D2 isofemale lines.

CYTOGENETICS OF 4 BRAZILIAN HYLA SPECIES (AMPHIBIA-ANURA) AND DESCRIPTION OF A CASE WITH A SUPERNUMERARY CHROMOSOME

The chromosomes of Hyla fuscovaria, H. hayii and II. prasina, with 2n=24, and of Hyla sp. (aff. circumdata), a new species, with 2n=24 and 2n=25, were studied.The karyotypes with 2n=24 in the four species were very similar, with almost no differences in the size and morphology of the chromosomes. The numerical variability found in Hyla sp. (aff. circumdata) is due to the occurrence of a supernumerary chromosome in some specimens. NOR data obtained for the first time in the four species and C banding analysis of H. prasina indicate that such types of banding may be useful to differentiate species with very similar karyotypes, contributing to the understanding of chromosome evolution and the establishment of phylogenetic relationships among Brazilian Hyla species.

AN INEXPENSIVE METHOD FOR CHROMOSOME PREPARATIONS FROM FEATHER PULP IN BIRDS, USING SHORT-TERM TREATMENT WITH COLCHICINE IN-VITRO, DEMONSTRATED ON AMAZONA-AMAZONICA (PSITTACIDAE)

In order to develop an efficient and low-cost technique for obtaining bird chromosome preparations, and to adapt the cytogenetic process of bird sexing for general use at zoos and breeding farms with the technical support of cytogenetics laboratories, we tested variants of the technique described by Giannoni et al. (Genet. Sel. Evol. 23: 123-125, 1991), based on the utilization of cellular material from growing feather pulp cultured in complete medium for six hours. Hanks' saline solution gave satisfactory performance as a substitute for complete medium, with no need to use PHA, serum of collagenase, when utilized in material obtained from feather pulp of Amazona amazonica (Psittacidae).

Mapping QTLs on chicken chromosome 1 for performance and carcass traits in a broiler x layer cross

With the objective of mapping quantitative trait loci (QTLs) for performance and carcass traits, an F-2 chicken population was developed by crossing broiler and layer lines. A total of 2063 F-2 chicks in 21 full-sib families were reared as broilers and slaughtered at 42 days of age. Seventeen performance and carcass traits were measured. Parental (F-0) and F-1 individuals were genotyped with 80 microsatellites from chicken chromosome 1 to select informative markers. Thirty-three informative markers were used for selective genotyping of F-2 individuals with extreme phenotypes for body weight at 42 days of age (BW42). Based on the regions identified by selective genotyping, seven full-sib families (649 F-2 chicks) were genotyped with 26 markers. Quantitative trait loci affecting body weight, feed intake, carcass weight, drums and thighs weight and abdominal fat weight were mapped to regions already identified in other populations. Quantitative trait loci for weights of gizzard, liver, lungs, heart and feet, as well as length of intestine, not previously described in the literature were mapped on chromosome 1. This F-2 population can be used to identify novel QTLs and constitutes a new resource for studies of genes related to growth and carcass traits in poultry.

POPULATIONAL STUDY OF CHROMOSOME POLYMORPHISM IN ZONOTRICHIA-CAPENSIS (EMBERIZIDAE, PASSERIFORMES, AVES)

The karyotypes of 328 specimens of Zonotrichia capensis from four regions, three in the state of Parana and one in the state of São Paulo (Brazil), were studied. This species presents a chromosomal polymorphism due to pericentric inversion, involving the 3rd and 5th chromosome pairs. Chromosome 3 exists in the 3st and 3sm conditions and chromosome 5, in 5st and 5m conditions. Mitotic metaphase spreads were obtained from bone-marrow material of colchicine-treated animals.At all collection sites the frequency of chromosome 5m was considerably lower than that of the inverted chromosome 3sm.The present work tried to establish a correlation between the frequencies of the 3rd and 5th chromosome pairs with the climatical and geographical parameters at the collecting regions.Data show that the frequency of chromosome 5m is higher in regions with low temperature and high altitude.

DUPLICATION OF THE SHORT ARM OF THE X-CHROMOSOME IN MOTHER AND DAUGHTER

An 11-year-old girl with short stature, mental retardation, and mild dysmorphic features was found to have an inverted duplication of most of the short arm of the X chromosome [dic inv dup(X)(qter --> p22.3 = p22.3 --> cen:)]. Her mother, who is also short and retarded, carries the same duplication. Fluorescence in situ hybridization with an X chromosome library, and with X centromere-specific alpha satellite and telomere probes, was useful in characterizing the duplication. In most females with structurally abnormal X chromosomes, the abnormal chromosome is inactivated. Although the duplicated X was consistently late replicating in the mother, X chromosome inactivation studies in the proband indicated that in 11 % of her lymphocytes the duplicated X was active.

Reproductive compatibility and chromosome pairing in the Drosophila buzzatii complex

Fertility (percentage of fertile crosses) and the degree of synapsis in salivary gland chromosomes in isofemale lines of Drosophila buzzatii, D. serido, D. koepferae and D. seriema were analysed. D. buzzatii was completely sterile in intercrosses with strains from the other species except for D. koepferae. The other species intercrossed to a greater or lesser degree, but also differed between crossing directions. Homologous pairing in salivary gland preparations of strains and hybrids conformed with the data on fertility. The lowest degree of synapsis was present in hybrids between D. koepferae and D. buzzatii, D. seriema and D. koepferae and D. koepferae and D. serido. These species also exhibited the lowest degree of reproductive compatibility. Hybrids between D. seriema and D. serido showed an intermediate degree of synapsis (pairing absent in the proximal and distal chromosome ends), as well as fertility greater than that found in the other interspecific crosses. Results of the fertility of crosses involving strains of a single species, compared with data in the literature, indicated that intraspecific divergence occurred in D. serido and D. koepferae.

Chromosome breakpoint distribution in nonmelanoma skin cancers

We have identified chromosome regions that may be sites of genes activated as a result of chromosomal rearrangements observed in 61 of the 86 skin tumors referenced in the literature. The data showed that most of the breakpoints were distributed throughout the genome and some tended to cluster. Highest frequencies of breakpoints were observed in chromosomes with high relative length, except chromosomes 14 and 15 that were more often affected in malignant tumors, despite their size. Our work provides a starting point for more detailed studies that may allow identification of these genes as important keys in the development and progression of skin cancers. (C) Elsevier B.V., 1997.

Cytogenetic study of neoplastic and nonneoplastic cells of the skin

We describe the cytogenetic study of six neoplastic and eight nonneoplastic skin samples from sun-exposed body sites or sites close to tumors. The cytogenetic findings revealed that chromosome rearrangements are common in sun-exposed normal skin, similar to the situation in cutaneous tumors, and suggest that such karyotypic abnormalities might be indicative of the genetic instability caused by specific mutations and resulting from carcinogenic exposure of the tissue.

Cytogenetics of three breeds of river buffalo (Bubalus bubalis L.), with evidence of a fragile site on the X chromosome

The cytogenetic study of 182 river buffalo (Bubalus bubalis L., 2n=50) of Murrah, Mediterranean and Jaffarabadi breeds, from the State of São Paulo, was carried out to characterize their chromosomes and to detect possible chromosomal abnormalities. The karyotypes were indistinguishable with conventional staining as well as with C and replication R banding techniques. In about 44% of the sample (8 males and 72 females), an X marker chromosome due to a fragile site was shown. The frequency of metaphases expressing the fragility site on the X was highly variable, from 2.86 to 41.03%. In females, the fragile site, rarely appeared on both X chromosomes. Most of the metaphases showed only 1 marker chromosome. In R-banded metaphases using 5-bromodeoxyuridine (BrdU) treatment, it corresponded in general to the late replicating X chromosome. No correlation between the X fragile site and altered phenotype was found. Structural and numerical chromosome rearrangements were ruled out in the present sample of buffalo. (C) 1998 by Elsevier B.V.