Karyotype studies of some species of Dalechampia plum. (Euphorbiaceae)

Karyotype studies in eight species of Dalechampia, including 10 natural populations, revealed chromosome numbers (2n = 36, 46, 138 and 198) differing from two numbers cited in the literature (2n = 44 and 72). The basic number x = 6, as in the genus Acalypha, may be considered ancestral in Dalechampia. Analysis of Chromosome number, haploid chromosome length and karyotype symmetry suggests that the major chromosome mechanism acting in karyotype evolution of Dalechampia is polyploidy, but differences in chromosome morphology may be caused by chromosome rearrangements.

Methodology for kariological study of Brazilian Palms

In the laboratory of cytogenetics of the DBAA-UNESP we are studying the karyotipe of some Brazilian Palms. To determine the best protocol, methods of seed germination, inhibition of mitosis, time to pick up the roots and staining were analyzed. The results shown that the seed germination in sphagnum is effective to achieve good roots. The best time to collect the root tips is between 11 to 12 AM., when there are more cell metaphases. The inhibition of mitosis cycle at metaphases may be effective both with 8-hydroxiquinoleine (0,03% -5 hours) or with cold water (0°C - 18-20 hours). The staining with Giemsa 2% showed the best chromosome figures in the metaphases. Now, to get good metaphases slides the method in use in the lab is: 1) seed germination in sphagnum at room temperature and high humidity; 2) The major roots are cut maintaining at least 5 cm, because this technic allows new emergence of roots, increasing the number of roots collected per germinated seed, that is very important in some species with poor germination rates; 3) To get the mitosis inhibition we are using cold water (0°C) treatment for 18-20 hours, following the standard protocols for conservation and hydrolysis; or enzyme digestion with pectinasecellulase 4) the staining procedures are made using Giemsa 2%. The Brazilian palms species studied and their respective chromosome number were: Aiphanes acanthophylla (2n=30), A. caryotaefolia (2n=30), Syagrus quinquifaria (2n=32), S. coronata (2n=32), S. romanzoffiana (2n=32), Euterpe edulis (2n=36), E. oleracea (2n=36), Copernicia prunifera (2n=36), Scheelea lauromuelleriana (2n=32) and Bactris gasipaes (2n=30).

Cytogenetic analysis of seven species of Eucalyptus L'Hér. (Myrtaceae)

Seven species of the genus Eucalyptus were studied cytogenetically (E. deanei, E. dunni, E. grandis, E. maculata E. propinqua, E. saligna and E. tereticornis). The species showed a symmetrical karyotype with 2n=22 chromosomes, with chromosome length ranging from 0.58 μm to 1.39 μm. Karyotypic analysis indicated homogeneity of morphology and of chromosome number for most of the species of this genus studied here, although casual disploid species with 2n=24 have been found in previous studies. According to these data, a basic number of x=11 was established for this genus. The evolutionary tendency probably occurred by structural alterations (deletions, duplications, additions and translocations) and in some cases by aneuploid chromosome alterations.

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.

Cytogenetics of two species of Paratelmatobius (Anura: Leptodactylidae), with phylogenetic comments

In this paper we provide a cytogenetic analysis of Paratelmatobius cardosoi and Paratelmatobius poecilogaster. The karyotypes of both species showed a diploid number of 24 chromosomes and shared some similarity in the morphology of some pairs. On the other hand, pairs 4 and 6 widely differed between these complements. These karyotypes also differed in their NOR number and location. Size heteromorphism was seen in all NOR-bearing chromosomes of the two karyotypes. In addition, both karyotypes showed small centromeric C-bands and a conspicuous heterochromatic band in the short arm of chromosome 1, although with a different size in each species. The P. cardosoi complement also showed other strongly stained non-centromeric C-bands, with no counterparts in the P. cardosoi karyotype. Chromosome staining with fluorochromes revealed heterogeneity in the base composition of two of the non-centromeric C-bands of P. cardosoi. Comparison of the chromosomal morphology of these Paratelmatobius karyotypes with that of P. lutzii showed that the P. poecilogaster karyotype is more similar to that of P. lutzii than P. cardosoi. These cytogenetic results agree with the proposed species arrangements in the P. cardosoi and P. lutzii groups based on morphological and ecological data.

Intrachromosomal distribution of telomeric repeats in Eumops glaucinus and eumops perotis (Molossidae, Chiroptera)

The location of chromosomal telomeric repeats (TTAGGG)(n) was investigated in two species of the Molossidae family, Eumops glaucinus and Eumops perotis. The diploid chromosome number (2n) is 40 in E. glaucinus and 48 in E. perotis and the fundamental numbers (FN) are 64 and 58, respectively. It has been suggested that the E. glaucinus karyotype has evolved from the E. perotis karyotype through Robertsonian fusion events. In the present study, the telomeric sequences were detected at the termini of chromosomes in both species. In addition, E. glaucinus also displayed telomeric repeats in centromeric and pericentromeric regions in almost all biarmed chromosomes. Conversely, in E. perotis pericentromeric signals were only observed in two biarmed chromosomes. In both E. glaucinus and E. perotis, such telomeric sequences were observed as part of the heterochromatin. The interstitial sites of telomeric sequences suggest that they are remnants of telomeres of ancestral chromosomes that participated in the fusion event.

Systematics and distribution of Thorea (Thoreaceae, Rhodophyta) from central Mexico and south-eastern Brazil

Thirteen populations of Thorea were analyzed from central Mexico and south-eastern Brazil. All populations were considered as belonging to a single species [Thorea hispida (Thore) Desvaux], with wide variation of morphological features. Secondary branches varying in frequency were observed in several populations with an overlapping in the range of branch density for Thorea violacea Bory and T. hispida (0-9 and 11-41 per 30 mm, respectively). As this is the most distinguishing character and on the basis of the overlapping (within a same population or even a single plant), we regarded T. violacea as a synonym of T. hispida. 'Chantransia' stage in culture, as well as gametophyte and carposporophyte were described in detail. We confirmed the coexistence of asexual monosporangia with sexual reproductive structures (carpogonia and spermatangia) and carposporangia. Size, content, arrangement and chromosome number were the most distinctive characteristics among spermatangia, carposporangia and monosporangia. Monosporangia can be promptly differentiated from spermatangia by their granulated content and larger size but they are similar to carposporangia in shape and size; however, monosporangia are not arranged in fascicles. Structures resembling bisporangia were observed in female plants of some populations. Chromosome numbers were n = 4 for spermatangia and fascicle cells, and 2n ca8 for gonimoblast filaments, carpospores and the 'Chantransia' stage cells. The populations of Thorea from central Mexico and south-eastern Brazil corroborated the known world distribution for T. hispida, consisting dominantly of tropical to subtropical rainforests, sometimes extending into warm temperate areas. Thorea hispida occurred in warm (temperature 17.6-28.0°C), neutral to alkaline (pH 7.0-8.0), high ion content (specific conductance 59-2140 μS cm-1), moderate flowing (current velocity 17-43 cm/s) and shallow waters (depth <50 cm); these data are essentially similar to previous reports.

Paternity study of an interspecific natural hybrid of the genus Eucalyptus L'Hér (Myrtaceae) based on cytogenetic data

Three species of the genus Eucalyptus (E. dunni, E. grandis, E. saligna) and interspecific hybrid were studied cytogenetically. The Eucalyptus species and the hybrid showed a symmetrical karyotype with 2n=22 chromosomes, with chromosome length ranging from 0.67 to 1.39 μm. Karyotypic analysis indicated a homogenous morphology and chromosome number for the species and the hybrid studied here. Based on the karyotype asymmetry data, together with the chromosome morphology results, the hybrid presented close similarity to E. saligna, suggesting that the latter is one of the parental species involved in the production of the hybrid.

Cytogenetic studies in Diplopoda

The Diplopoda have received little attention from cytogeneticists owing mostly to technical difficulties in obtaining mitotic chromosomes, restricting the studies to meiosis and eventual spermatogonial metaphases, which limits the use of modern cytogenetical techniques. A literature search shows that only about 0.1% of all known species have been cytogenetically studied. There are 80,000 species estimated for this group, making it the 3rd. larger class in Arthropoda, after Insecta and Arachnida. The diploid chromosomal number in diplopods varies from 2n=8 to 2n=30 and the sex determination mechanism commonly found is XY/XX. In meiotic prophase, the bouquet formation and the diffuse state in pachytene are typical events. The few works performed on Brazilian fauna add up to 16 species, out of an estimated number of 2000 to 3000 species. The present review reports all the species of diplopods that have been cytogenetically studied so far, each with its chromosome number and sex determination system.

Occurence of karyotypical mosaicism in Trichomycterus paolence (Teleostei, Trichomycteridae)

A chromosomal mosaic has at least two cell lineages with different karyotypes derived from a single zygote and the karyotype alteration can be numeric or structural as well. In the present paper were detected a numeric chromosomal alterations in a single specimen of Thichomycterus paolence from the Quinta stream (Itatinga, state of São Paulo, Brazil). In a total of 61 analysed metaphases, besides the normal chromosome number of this species (2n=54), other four chromosomal sets characterized by 2n=55 (54 plus a microchromosome), 2n=55 (54 plus a small subtelocentric chromosome), 2n=56 (54 plus a subtelocentric and a microchromosome) and 2n=57 (54 plus a subtelocentric pair and a microchromosome) have been detected. The mechanisms that have originated those abnormal karyotypical constitutions is discussed.

Cytogenetical aspects of testicular cells in economically important species of coreidae family (Heteroptera)

Some cytogenetical aspects of spermatozoa formation were studied in 9 Coreidae Brazilian species: Anasa bellator, Athaumastus haematicus, Chariesterus armatus, Dallacoris obscura, Dallacoris pictus, Leptoglossus gonagra, Leptoglossus zonatus, Sphictyrtus fasciatus, and Zicca annulata. Similarly to the other species described to date, all the species studied herein showed cystic spermatogenesis, a reddish membrane covering the testes, a X0 sex determining system, a pair of m-chromosomes, intersticial chiasmata in most autosomes, and autosomes dividing reductionally at first meiotic division and equationally in the second 1 while sex chromosomes, divide equationally and reductionally at first and second meiotic division, respectively. In addition, it was observed that the sex chromosome is heteropycnotic at prophase and that heteropycnotic chromosomal material is found in the nuclei at spermiogenesis. In the species studied, the diploid chromosome number ranged from 19 to 25. It was 19 in S. fasciatus (16A+2m+X0); 21 in A. bellator, A. haematicus, D. obscura, D. pictus, L. gonagra, and L. zonatus (18A+2m+X0); 23 in Z. annulata (20A+2m+X0); and 25 in C. armatus (22A+2m+X0). © 2007 The Japan Mendel Society.

Cytogenetic analysis in the spermatogenesis of Triatoma melanosoma (Reduviidae; Heteroptera)

Triatomines are of great concern in public health because they are vectors of Chagas' disease. This study presents an analysis of the species Triatoma melanosoma. The cytogenetic characteristics of triatomines include holocentric chromosomes, post-reductional meiosis in the sex chromosomes and nucleolar fragmentation in the meiotic cycle. The methodology utilized consisted of the techniques of lacto-acetic orcein staining and silver ion impregnation. The organs analyzed were adult testicles. The results enabled to classify the chromosomes by number and size, being three large, eight medium and one small heterochromosome. The three largest chromosomes and the heterochromosomes showed heteropyknotic chromatin in meiosis. The heterochromosomes in 8.05% of the cells in metaphase I behaved as pseudobivalents, contrasting with 91.95% of the cells with individualized sex chromosomes, confirming the achiasmatic nature of these chromosomes. However, the pseudobivalents occurred prominently in metaphase II (78.38%), this fact probably is related to the post-reductional nature of the sex chromosomes. The nucleolus in T. melanosoma persisted until the diplotene phase after which it began to fragment. Nucleolar corpuscles were observed in metaphases I and II and during anaphases I and II, these characteristics being related to the phenomenon of nucleolar persistence. In the initial spermatids, peripheral silver ion impregnation occurred, which could be analogous to the pre-nucleolar corpuscles observed after fragmentation. Thus, this study extends our knowledge of the characteristics of triatomines, in particular, heteropyknotic degree, kinetic activity, formation of sex chromosome achiasmatic pseudobivalency, confirmation of the fragmentation phenomenon, and post-meiotic nucleolar reactivation. ©FUNPEC-RP.

Chromosomal characteristics and karyotype evolution of oxyopidae spiders (araneae, entelegynae)

We made a cytogenetic analysis of four species of Oxyopidae and compared it with the karyotype data of all species of this family. In Hamataliwa sp, the mitotic cells showed 2n♂ = 26+X 1X 2 and telocentric chromosomes. The 2n♂ = 28, which has been described for only one oxyopid spider, is the highest diploid number reported for this family. Peucetia species exhibited distinct karyotype characteristics, i.e., 2n♂ = 20+X 1X 2 in P. flava and 2n♂ = 20+X in P. rubrolineata, revealing interspecific chromosome variability within this genus. However, both Peucetia species exhibited telocentric chromosomes. The most unexpected karyotype was encountered in Oxyopes salticus, which presented 2n♂ = 10+X in most individuals and a predominance of biarmed chromosomes. Additionally, one male of the sample of O. salticus was heterozygous for a centric fusion that originated the first chromosomal pair and exhibited one supernumerary chromosome in some cells. Testicular nuclei of Hamataliwa sp and O. salticus revealed NORs on autosomal pairs, after silver impregnation. The majority of Oxyopidae spiders have their karyotype differentiated by both reduction in diploid number chromosome number and change of the sex chromosome system to X type; however, certain species retain the ancestral chromosome constitution 2n = 26+X1X2. The most remarkable karyotype differentiation occurred in O. salticus studied here, which showed the lowest diploid number ever observed in Oxyopidae and the second lowest registered for Entelegynae spiders. © FUNPEC-RP www.funpecrp.com.br.

Simple method for culture of peripheral blood lymphocytes of Testudinidae.

We developed and optimized a simple, efficient and inexpensive method for in vitro culture of peripheral blood lymphocytes from the Brazilian tortoise Chelonoidis carbonaria (Testudinidae), testing various parameters, including culture medium, mitogen concentration, mitotic index, culture volume, incubation time, and mitotic arrest. Peripheral blood samples were obtained from the costal vein of four couples. The conditions that gave a good mitotic index were lymphocytes cultured at 37°C in minimum essential medium (7.5 mL), with phytohemagglutinin as a mitogen (0.375 mL), plus streptomycin/penicillin (0.1 mL), and an incubation period of 72 h. Mitotic arrest was induced by 2-h exposure to colchicine (0.1 mL), 70 h after establishing the culture. After mitotic arrest, the cells were hypotonized with 0.075 M KCl for 2 h and fixed with methanol/acetic acid (3:1). The non-banded mitotic chromosomes were visualized by Giemsa staining. The diploid chromosome number of C. carbonaria was found to be 52 in females and males, and sex chromosomes were not observed. We were able to culture peripheral blood lymphocytes of a Brazilian tortoise in vitro, for the preparation of mitotic chromosomes.

Descrição cariotípica de possíveis novas espécies do complexo Hypostomus ancistroides e outros Hypostominae

Cytogenetic analyses were performed in four species of the Hypostominae subfamily, three from Hypostomus (Hypostomini) genus and Rhinelepis aspera (Rhinelepini). Three populations of Hypostomus ancistroides were analyzed, which had 2n=68 chromosomes, but presented different karyotype formulas. Hypostomus regani and H. strigaticeps, both from Ivaí river, showed 2n=72 chromosomes with two distinct cytotypes. In turn, R. aspera of the upper Paraná river basin presented 2n=54 chromosome. Multiple Nucleolar Organizer Regions (NORs) have been evidenced by silver nitrate staining in species of Hypostomus and single NOR in R. aspera. The observed variation in the chromosome number and the marked variability in karyotype formulas and NORs reveal a certain amount of karyotype variation in the genus Hypostomus suggesting the probable existence of cryptic species with independent chromosome traits. Therefore, our data can be of great value in discriminating species and understanding their chromosomal evolution.