Dinoponera lucida Emery (Formicidae : Ponerinae): the highest number of chromosomes known in Hymenoptera

We report the remarkable karyotype of Dinoponera lucida, a Brazilian endemic ponerine ant. Its chromosome number is 2n=106, most of the chromosomes are acrocentric and of very small size, and the karyotype formula is 88A+18M. A chromosome pair of the AM(t) type is reported. This is the largest number of chromosomes reported for the Hymenoptera order until now.

Mapping of quantitative trait loci controlling tick [Riphicephalus (Boophilus) microplus] resistance on bovine chromosomes 5, 7 and 14

Differences in domestication and selection processes have contributed to considerable phenotypic and genotypic differences between Bos taurus and Bos indicus cattle breeds. of particular interest in tropical and subtropical production environments are those genetic differences between subspecies that underlie the phenotypic extremes in tolerance and susceptibility to parasite infection. In general, B. taurus cattle are more susceptible to ectoparasites than B. indicus cattle in tropical environments, and much of this difference is under genetic control. To identify genomic regions involved in tick resistance, we developed a B. taurus x B. indicus F-2 experimental population to map quantitative trait loci (QTL) for resistance to the Riphicephalus (Boophilus) microplus tick. About 300 individuals were measured for parasite load in two seasons (rainy and dry) and genotyped for 23 microsatellite markers covering chromosomes 5, 7 and 14. We mapped a suggestive chromosome-wide QTL for tick load in the rainy season (P < 0.05) on chromosome 5. For the dry season, suggestive (P < 0.10) chromosome-wide QTL were mapped on chromosomes 7 and 14. The additive effect of the QTL on chromosome 14 corresponds to 3.18% of the total observed phenotypic variance. Our QTL-mapping study has identified different genomic regions controlling tick resistance; these QTL were dependent upon the season in which the ticks were counted, suggesting that the QTL in question may depend on environmental factors.

Supernumerary chromosomes in the pufferfish Sphoeroides spengleri: first occurrence in marine Teleostean Tetraodontiformes fish

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A lethal effect associated with polymorphism of the NOR-bearing chromosomes in rainbow trout (Oncorhynchus mykiss)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genetic linkage maps of chicken chromosomes 6, 7, 8, 11 and 13 from a Brazilian resource population

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Twelve loci from HSA10, HSA11 and HSA20 were comparatively FISH-mapped on river buffalo and sheep chromosomes

Ten type I loci from HSA 10 (IL2RA and VIM), HSA11 (HBB and FSHB) and HSA20 (THBD, AVP/OXT, GNAS1, HCK and TOP1) and two domestic cattle type II loci (CSSM30 and BL42) were FISH mapped to R-banded river buffalo (BBU) and sheep (OAR) chromosomes. IL2RA (HSA 10) maps on BBU 14q13 and OAR13q13, VIM (HSA 10) maps on BBU14q15 and OAR13q15, HBB (HSA11) maps on BBU16q25 and OAR15q23, FSHB (HSA11) maps on BBU16q28 and OAR15q26. THBD (HSA20) maps on BBU 14q15 and OAR13q15 while AVP/OXT. GNAS1, HCK, and TOP I (HSA20) as well as CSSM30 and BL42 map on the same large band of BBU 14q22 and OAR13q22. All loci were mapped on the same homologous chromosomes and chromosome bands of the two species, and these results agree with those earlier reported in cattle homologous chromosomes 15 and 13. respectively, confirming the high degree of both banding and physical map similarities among the bovid species. Indirect comparisons between physical maps achieved on bovid chromosomes and those reported on HSA10, HSA11 and HSA20 were performed. Copyright (C) 2001 S. Karger AG, Basel.

A standard protocol for obtaining fish chromosomes under post-mortem conditions

In order to improve cytogenetical analyses on fish, especially focusing on delicate and rare species, we have adopted a new in vitro methodology using dead animals. The results obtained from 24 neotropical freshwater and marine fish species demonstrate that chromosomes can be obtained under post-mortem conditions. Significantly, the samples analyzed provided reliable cytogenetical data in nearly all cases. Other advantages of this new methodology are also discussed. (c) 2006 Elsevier Ltd. All rights reserved.

Molecular cytogenetic analysis of heterochromatin in the chromosomes of tilapia, Oreochromis niloticus (Teleostei : Cichlidae)

The structure of the heterochromatic bands in mitotic chromosomes of the important tropical aquaculture species of tilapia, Oreochromis niloticus, was investigated by the combination of the C-banding technique, chromosomal digestion with two restriction endonucleases and fluorescence in situ hybridization (FISH) of two satellite DNAs (SATA and SATB). The tilapia chromosomes presented heterochromatic bands in the centromeres and in the short arms of almost all chromosomes that were differentially digested by the restriction endonucleases HaeIII and EcoRI. FISH of SATA showed that the satellite sequence is distributed in the centromeric region of all chromosomes of tilapia. FISH also revealed an intense hybridization signal for SATB in only one chromosome pair, but less intense signals were also present in several other pairs. The digestion of tilapia chromosomes by HaeIII and EcoRI was positively correlated with the position of SATA and SATB in chromosomes as revealed by FISH. The results obtained may be useful in future molecular and genetic studies of tilapias.

Localization of 5-methylcytosine in metaphase chromosomes of diploid and triploid pacu fish, Piaractus mesopotamicus (Pisces, Characiformes)

The distribution of 5-methylcytosine (5-MeC) was investigated in fish chromosomes by indirect immunofluorescence using a highly specific 5-MeC monoclonal antibody. Diploid and artificially produced triploid specimens of the pacu fish, Piaractus mesopotamicus, were analyzed. The strong immunofluorescent signals were coincident with the heterochromatic regions of both diploids and triploids in a pattern that matched the C-banding pattern. In the euchromatin, heterogeneous labeling was observed along the chromatids. The weakness of this labeling hindered comparison of the fluorescence labeling of homologous chromosomes from diploid and triploid individuals. However, no striking differences were observed. The possibility that the euchromatin labeling by the 5-MeC antibody is related to the occurrence of mildly repetitive sequences in the genome of Piaractus is discussed.

Cytogenetic analysis of A- and B-chromosomes of Prochilodus lineatus (Teleostei, Prochilodontidae) using different restriction enzyme banding and staining methods

Different cytogenetic techniques were used to analyse the chromosomes of Prochilodus lineatus with the main objective of comparing the base composition of A- and B-chromosomes. The results of digestion of chromosomes with 10 different restriction endonucleases (REs), silver staining, CMA(3) staining and C-banding indicated the existence of different classes of highly repetitive DNA in the A-set and also suggested the existence of compositional differences between the chromatin of A- and B-chromosomes. The 5-BrdU incorporation technique showed a late replicating pattern in all B-chromosomes and in some heterochromatic pericentromeric regions of A-chromosomes. The cleavage with RE BamHI produced a band pattern in all chromosomes of P. lineatus which permitted the tentative pairing of homologues in the karyotype of this species. We concluded that the combined use of the above techniques can contribute to the correct identification of chromosomes and the karyotypic analysis in fishes. on the basis of the results, some aspects of chromosome structure and the origin of the B-chromosomes in P. lineatus are discussed.

Cytogenetic characterization of a supernumerary chromosome segment and of B-chromosomes in Astyanax scabripinnis (Teleostei, Characidae)

The chromosome complement of a local population of Astyanax scabripinnis in Brazil was investigated with emphasis on the study of the heterochromatin attached to the A-chromosomes and present in the macro B-chromosome. Analysis after C-banding, silver and CMA(3) staining, incorporation of 5-bromo-2'-deoxyuridine and chromosome digestion with nine restriction endonucleases revealed that the heterochromatin in the B-chromosomes was different from that found in the A-chromosomes. A polymorphism due to the presence of a supernumerary heterochromatic chromosome segment was observed in the population investigated. Some aspects related to the origin of the heterochromatin polymorphism in Astyanax scabripinnis are discussed.