Chromosome polymorphism and cytotype establishment in Bidens pilosa (Asteraceae)

Chromosome evolution, in the Bidens genus, was by polyploidy mechanisms. The basic number to the genus is X = 12 chromosomes, as all the Fitchinae subtribe. The association of chromosome number and environment in these plants was made some time ago, concerning the cytotypes of the species. In this paper, the chromosome number of nine Bidens pilosa populations was studied. The chromosome numbers found were 2n = 48, 70 and 72. In six of the nine populations analysed the most frequent number was 2n = 72. The Ibiuna population had 2n = 70 chromosomes and two had the lowest chromosome number (2n = 48). Observations of the B. pilosa population suggests that ploidy levels were related to a geographical gradient establishing the environmental altitudes. The data showed that lower ploidy levels, that is 2n = 48, were found at lower altitudes, while the populations higher ploidy levels were found in several environments, over a wide distribution.

Chromosome evolution in the erythrinid fish, Erythrinus erythrinus (Teleostei : Characiformes)

The genus Erythrinus belongs to the family Erythrinidae, a neotropical fish group. This genus contains only two described species, Erythrinus erythrinus being the most widely distributed in South America. Six samples of this species from five distinct Brazilian localities and one from Argentina were studied cytogenetically. Four groups were identified on the basis of their chromosomal features. Group A comprises three samples, all with 2n = 54 chromosomes, a very similar karyotypic structure, and the absence of chromosome differentiation between males and females. One sample bears up to four supernumerary microchromosomes, which look like 'double minute chromosomes' in appearance. Groups B - D comprise the three remaining samples, all sharing an X1X1X2X2/X1X2Y sex chromosome system. Group B shows 2n = 54/53 chromosomes in females and males, respectively, and also shows up to three supernumerary microchromosomes. Groups C and D show 2n = 52/51 chromosomes in females and males, respectively, but differ in the number of metacentric, subtelocentric, and acrocentric chromosomes. In these three groups ( B - D), the Y is a metacentric chromosome clearly identified as the largest in the complement. The present results offer clear evidence that local samples of E. erythrinus retain exclusive and fixed chromosomal features, indicating that this species may represent a species complex.

KARYOTYPIC ANALYSIS AND CHROMOSOME BIOMETRY OF CELL-CULTURES OF THE YELLOW-THROATED ALLIGATOR (CAIMAN-LATIROSTRIS DAUDIN)

Blood from eight specimens of both sexes of the alligator Caiman latirostris was collected and incubated in culture medium. Conventional as well as chromosomal banding (C and NOR) techniques were used.The diploid number was determined as 42, being 24 telocentric, 12 metacentric and six submetacentric, with real lengths varying from 1.49 to 6.08, 1.63 to 3.71, and 2.41 to 3.19 mum, respectively. The fundamental number was 60. About 81% of the chromosomes were small and 19% medium in size. NOR-banding was presented for the first time for this species and it was verified that only one submetacentric pair (no. 20) was marked on arm q, and under conventional staining it presented a secondary constriction. There was no association between NOR marked chromosomes.

Chromosome aberrations as a predictor of clinical outcome for smoking associated lung cancer

The ability to identify individuals at greatest risk of developing lung cancer can significantly enhance the efficacy of intervention modalities. One strategy for identifying these individuals is through biomarkers that reflect the severity of their cancer. In the present study, we evaluated 22 lung cancer patients and 35 controls to determine whether the frequency of chromosome aberrations was significantly associated with specific clinical variables such as the histological type, grade and stage of the turners. Chromosome aberrations (expressed as total breaks) were investigated on chromosome 1 in interphase nuclei obtained from blood Lymphocytes of the study participants using the fluorescence in situ hybridization (FISH) chromosome aberration assay. Our results indicate a significant linear increase (P = 0.01) in the level of breaks with respect to the grade of the carcinoma. The poorly differentiated tumors had a significantly higher level of chromosome breaks mean +/- SD (1.7 +/- 0.46) as compared to the well differentiated tumors (0.98 +/- 0,23, P < 0,05). These results indicate that chromosome aberrations, as determined by the FISH assay, can be used as a biomarker for identifying individuals with aggressive types of lung cancer and potentially, as a predictor for prognostic outcome of the disease. (C) 2000 Elsevier B.V. Ireland Ltd. All rights reserved.

Karyotype Conservation in 2 Populations of the Parthenogenetic Scorpion Tityus serrulatus (Buthidae): rDNA and Its Associated Heterochromatin Are Concentrated on Only One Chromosome

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

Chromosome reduction in Eleocharis maculosa (Cyperaceae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of ankle functional instability on the ankle electromyography during landing after volleyball blocking

The purpose of this study was to describe, interpret and compare the EMG activation patterns of ankle muscles - tibialis anterior (TA), peroneus longus (PL) and gastrocnemius lateralis (GL) - in volleyball players with and without ankle functional instability (FI) during landing after the blocking movement. Twenty-one players with FI (IG) and 19 controls (CG) were studied. The cycle of movement analyzed was the time period between 200 ms before and 200 ms after the time of impact determined by ground reaction forces. The variables were analyzed for two different phases: pre-landing (200 ms before impact) and post-landing (200 ms after impact). The RMS values and the timing of onset activity were calculated for the three studied muscles, in both periods and for both groups. The co-activation index for TA and PL, TA and GL were also calculated. Individuals with FI presented a lower RMS value pre-landing for PL (CG = 43.0 perpendicular to 22.0; IG = 26.2 perpendicular to 8.4, p < 0.05) and higher RMS value post-landing (CG = 47.5 perpendicular to 13.3; IG = 55.8 perpendicular to 21.6, p < 0.10). Besides that, in control group PL and GL activated first and simultaneously, and TA presented a later activation, while in subjects with FI all the three muscles activated simultaneously. There were no significant differences between groups for co-activation index. Thus, the rate of contraction between agonist and antagonist muscles is similar for subjects with and without FI but the activation individually was different. Volleyball players with functional instability of the ankle showed altered patterns of the muscles that play an important role in the stabilization of the foot-ankle complex during the performance of the blocking movement, to the detriment of the ligament complex, and this fact could explain the usual complaints in these subjects. (C) 2007 Elsevier Ltd. All rights reserved.

Chromosomal evolution in Gekkonidae. I. Chromosome painting between Gekko and Hemidactylus species reveals phylogenetic relationships within the group

Geckos are a large group of lizards characterized by a rich variety of species, different modes of sex determination and diverse karyotypes. In spite of many unresolved questions on lizards' phylogeny and taxonomy, the karyotypes of most geckos have been studied by conventional cytogenetic methods only. We used flow-sorted chromosome-specific painting probes of Japanese gecko (Gekko japonicus), Mediterranean house gecko (Hemidactylus turcicus) and flat-tailed house gecko (Hemidactylus platyurus) to reveal homologous regions and to study karyotype evolution in seven gecko species (Gekko gecko, G. japonicus, G. ulikovskii, G. vittatus, Hemidactylus frenatus, H. platyurus and H. turcicus). Generally, the karyotypes of geckos were found to be conserved, but we revealed some characteristic rearrangements including both fissions and fusions in Hemidactylus. The karyotype of H. platyurus contained a heteromorphic pair in all female individuals, where one of the homologues had a terminal DAPI-negative and C-positive heterochromatic block that might indicate a putative sex chromosome. Among two male individuals studied, only one carried such a polymorphism, and the second one had none, suggesting a possible ZZ/ZW sex determination in some populations of this species. We found that all Gekko species have retained the putative ancestral karyotype, whilst the fission of the largest ancestral chromosome occurred in the ancestor of modern Hemidactylus species. Three common fissions occurred in the ancestor of Mediterranean house and flat-tailed house geckos, suggesting their sister group relationships. PCR-assisted mapping on flow-sorted chromosome libraries with conserved DMRT1 gene primers in G. japonicus indicates the localization of DMRT1 gene on chromosome 6.

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)