Origin of nuclear and chromosomal alterations derived from the action of an aneugenic agent-Trifluralin herbicide

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Genotoxicity and mutagenicity of water samples from the Monjolinho River (Brazil) after receiving untreated effluents

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

Evaluation of Cyto- and Genotoxicity of Poly(lactide-co-glycolide) Nanoparticles

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

Intriguing evidence of translocations in Discus fish (Symphysodon, Cichlidae) and a report of the largest meiotic chromosomal chain observed in vertebrates

As part of a program to understand the genetics of Amazonian ornamental fish, classical cytogenetics was used to analyze Symphysodon aequifasciatus, S. discus and S. haraldi, popular and expensive aquarium fishes that are endemic to the Amazon basin. Mitotic analyses in Symphysodon have shown some odd patterns compared with other Neotropical cichlids. We have confirmed that Symphysodon species are characterized by chromosomal diversity and meiotic complexity despite the fact that species share the same diploid number 2n = 60. An intriguing meiotic chromosomal chain, with up to 20 elements during diplotene/diakinesis, was observed in S. aequifasciatus and S. haraldi, whereas S. discus only contains typical bivalent chromosomes. Such chromosomal chains with a high number of elements have not been observed in any other vertebrates. We showed that the meiotic chromosomal chain was not sex related. This observation is unusual and we propose that the origin of meiotic multiples in males and females is based on a series of translocations that involved heterochromatic regions after hybridization of ancestor wild Discus species. Heredity (2009) 102, 435-441; doi: 10.1038/hdy.2009.3; published online 25 February 2009

Labeling index in pituitary adenomas evaluated by means of MIB-1: is there a prognostic role? A critical review

Objective: The present article presents an overview of the literature, and analyses the methods and the primary questions related to assessment of proliferation index using the Ki-67/MIB-1 labeling index in pituitary adenomas. Although atypical adenomas are characterized by their atypical morphological features by an elevated mitotic index, a Ki-67 (MIB-1) labeling index greater than 3% and extensive nuclear staining for p53, use of the proliferation index (LI) of pituitary adenomas in assessing the degree of tumor aggressiveness is a controversial topic in the literature, and there are disparate results involving many studies.Methods: A review of literature was carried out to correlate the role of Ki-67 LI and its correlation with clinical findings, tumor size, invasiveness, recurrence, adenoma subtype, adenoma doubling time, and pituitary carcinomas is addressed. Results: The prognosis cannot be predicted on the basis of the Ki-67 LI alone. Although there is no direct relation between Ki-67 LI and some of these variables and controversial data were found regarding some topics, our review justify the use of Ki-67 in the analysis of pituitary adenomas as an additional information for clinical decision.Conclusion: Although assessment of proliferative may be helpful in predicting subsequent tumor recurrence or invasiveness, there are many other important and as yet unidentified factors pituitary tumors. It is clear that further research is needed to clarify these molecular mechanisms to predict those with a potentially poor clinical outcome.

A Comparative Cytogenetic Analysis of 2 Bothriuridae Species and Overview of the Chromosome Data of Scorpiones

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

Sex chromosome differentiation in Belostoma (Insecta: Heteroptera: Belostomatidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cytoplasmic bridges, intercellular junctions, and individualization of germ cells during spermatogenesis in Dermatobia hominis (Diptera: Cuterebridae)

During mitotic and meiotic divisions in Dermatobia hominis spermatogenesis, the germ cells stay interlinked by cytoplasm, bridges as a result of incomplete cytokinesis. By the end of each division, cytoplasmic bridges flow to the center of the cyst, forming a complex, called the fusoma. During meiotic prophase I, spermatocytes I present desmosome-like junctions and meiotic cytoplasmic bridges. At the beginning of spermiogenesis, the fusoma moves to the future caudal end of the cyst, and at this time the early spermatids are linked by desmosome-like junctions. Throughout spermiogensis, new and sometimes broad cytoplasmic bridges are formed among spermatids at times making them share cytoplasm. In this case the individualization of cells is assured by the presence of smooth cisternae that outline then structures The more differentiated spermatids have in addition to narrow cytoplasmic bridges, plasmic membranes junctions. By the end of spermiogenesis the excess cytoplasmic mass is eliminated leading to spermatid individualization. Desmosome-like junctions of spermatocytes I and early spermatids appear during the fusoma readjustment and segregations; on the other hand, plasmic membrane junctions appear in differentiating spermatids and are eliminated along with the cytoplasmic excess. These circumstances suggest that belt desmosome-like and plasmic membrane junctions are involved in the maintenance of the relative positions of male germ cells in D. hominis while they are inside the cysts. © 1996 Wiley-Liss, Inc.

Cycloactive, aneugenic and clastogenic effects of Paracoccidioides brasiliensis exoantigen in human lymphocyte cultures

The in vitro effect of Paracoccidioides brasiliensis exoantigen on the human lymphocytes cell cycle and chromosomes was studied. Human peripheral blood lymphocyte cultures from ten healthy, white, non-smoking, non-related adult males (mean age 31·3 ± 8·2 years) were studied. Blood cultures were treated with three exoantigen concentrations (0·25, 2·50 and 10·00 μg ml -1). At least 1000 metaphases were analysed at each concentration, for evaluation of numerical and structural chromosome aberrations (cA) and 30 000 for mitotic index (MI). Among the treated cultures, statistically significant differences in the frequencies of MI and cA were not observed. Nevertheless, when compared with control cultures, they all showed a significantly lower frequency of MI and higher frequency of cA. It is suggested that the detected alterations were caused by the exoantigen, its fractions or its metabolites. © 1996 Informa UK Ltd All rights reserved.

Human chromosome aberrations induced in vitro by Paracoccidioides brasiliensis glycoproteic component (GP 43)

The in vitro cytogenetic effects of the 43-kDa molecular mass exocellular glycoproteic component (GP 43) from Paracoccidioides brasiliensis were studied in cultures from human lymphocytes. The sample included 10 healthy, white, non-smoking, non-related males (mean age of 31.3 ± 8.2 years). Besides the control, three concentrations of GP 43 (0.125, 1.25 and 5 μg/ml) were used. In each group, around 1000 cells were examined in search of chromosome aberrations, and 30,000 metaphases were analysed for the determination of the Mitotic Index. The authors conclude that GP 43 most probably causes inhibition of the cell cycle and aneugenic and clastogenic effects.

Interaction of Hawking radiation and a static electric charge

We investigate whether the equality found for the response of static scalar sources interacting (i) with Hawking radiation in Schwarzschild spacetime and (ii) with the Fulling-Davies-Unruh thermal bath in the Rindler wedge is maintained in the case of electric charges. We find a finite result in the Schwarzschild case, which is computed exactly, in contrast with the divergent result associated with the infrared catastrophe in the Rindler case, i.e., in the case of uniformly accelerated charges in Minkowski spacetime. Thus the equality found for scalar sources does not hold for electric charges.

Multiplicity of Boardman strata and deformations of map germs

We define algebraically for each map germ f: Kn, 0→ Kp, 0 and for each Boardman symbol i = (il, . . ., ik) a number ci(f) which is script A sign-invariant. If f is finitely determined, this number is the generalization of the Milnor number of f when p = 1, the number of cusps of f when n = p = 2, or the number of cross caps when n = 2, p = 3. We study some properties of this number and prove that, in some particular cases, this number can be interpreted geometrically as the number of Σi points that appear in a generic deformation of f. In the last part, we compute this number in the case that the map germ is a projection and give some applications to catastrophe map germs.

A cytogenetic study of Diplomystes mesembrinus (Teleostei, Siluriformes, Diplomystidae) with a discussion of chromosome evolution in siluriforms

The mitotic chromosomes, nucleolus organizer regions (NORs), C-banding pattern and nuclear DNA content of Diplomystes mesembrinus were studied. The karyotype, with 2n=56 chromosomes (22m+24sm+6st+4a), has a high chromosome arm number (NF = 102), one chromosome pair with NORs, and a very small amount of heterochromatin. The NOR-bearing arm is entirely heterochromatic and exhibits a marked size polymorphism. The diploid DNA content detected in erythrocyte nuclei of D. mesembrinus was 2.57 ± 0.15 pg/nucleus. The chromosome evolution in Siluriformes is discussed on the basis of available cytogenetic data and it is proposed that 2n=56 is synapomorphic for the order.

Cytogenetic analysis of Epicauta atomaria (Meloidae) and Palembus dermestoides (Tenebrionidae) with Xyp sex determination system using standard staining, C-bands, NOR and synaptonemal complex microspreading techniques

The mitotic and meiotic chromosomes of the beetles Epicauta atomaria (Meloidae) and Palembus dermestoides (Tenebrionidae) were analysed using standard staining, C-banding and silver impregnation techniques. We determine the diploid and haploid chromosome numbers, the sex determination system and describe the chromosomal morphology, the C-banding pattern and the chromosome(s) bearing NORs (nucleolar organizer regions). Both species shown 2n = 20 chromosomes, the chromosomal meioformula 9 + Xyp, and regular chromosome segregation during anaphases I and II. The chromosomes of E. atomaria are basically metacentric or submetacentric and P. dermestoides chromosomes are submetacentric or subtelocentric. In both beetles the constitutive heterochromatin is located in the pericentromeric region in all autosomes and in the Xp chromosome; additional C-bands were observed in telomeric region of the short arm in some autosomes in P. dermestoides. The yp chromosome did not show typical C-bands in these species. As for the synaptonemal complex, the nucleolar material is associated to the 7th bivalent in E. atomaria and 3rd and 7th bivalents in P. dermestoides. Strong silver impregnated material was observed in association with Xyp in light and electron microscopy preparations in these species and this material was interpreted to be related to nucleolar material.

The ultrastructure of the pre-meiotic and meiotic stages of spermatogenesis in Plagioscion squamosissimus (Teleostei, Perciformes, Sciaenidae)

Spermatogenesis of 'corvina' P. squamosissimus starts from a stem cell that gives rise to germ cells. These cells are enveloped by Sertoli cells, forming cysts. The germ cells in the cysts are all at the same stage of development and are interconnected by cytoplasmic bridges. Spermatogonia are the largest germ cells. In the cysts, these cells differentiate into primary spermatogonia and secondary spermatogonia. The primary spermatogonia are isolated in the cyst and give rise to the secondary spermatogonia. After several mitotic divisions, they produce spermatocytes I, which can be identified by synaptonemal complexes in the nucleus. The spermatocytes I enter the first phase of meiosis to produce the spermatocytes II. These are not very frequently seen because they rapidly undergo a second phase of meiosis to produce spermatids.