Two new cytotypes reinforce that <Emphasis Type="Italic">Micronycteris hirsuta</Emphasis> Peters, 1869 does not represent a monotypic taxon

Background

The genus Micronycteris is a diverse group of phyllostomid bats currently comprising 11 species, with diploid number (2n) ranging from 26 to 40 chromosomes. The karyotypic relationships within Micronycteris and between Micronycteris and other phyllostomids remain poorly understood. The karyotype of Micronycteris hirsuta is of particular interest: three different diploid numbers were reported for this species in South and Central Americas with 2n?=?26, 28 and 30 chromosomes. Although current evidence suggests some geographic differentiation among populations of M. hirsuta based on chromosomal, morphological, and nuclear and mitochondrial DNA markers, the recognition of new species or subspecies has been avoided due to the need for additional data, mainly chromosomal data.

Results

We describe two new cytotypes for Micronycteris hirsuta (MHI) (2n?=?26 and 25, NF?=?32), whose differences in diploid number are interpreted as the products of Robertsonian rearrangements. C-banding revealed a small amount of constitutive heterochromatin at the centromere and the NOR was located in the interstitial portion of the short arm of a second pair, confirmed by FISH. Telomeric probes hybridized to the centromeric regions and weakly to telomeric regions of most chromosomes. The G-banding analysis and chromosome painting with whole chromosome probes from Carollia brevicauda (CBR) and Phyllostomus hastatus (PHA) enabled the establishment of genome-wide homologies between MHI, CBR and PHA.

Conclusions

The karyotypes of Brazilian specimens of Micronycteris hirsuta described here are new to Micronycteris and reinforce that M. hirsuta does not represent a monotypic taxon. Our results corroborate the hypothesis of karyotypic megaevolution within Micronycteris, and strong evidence for this is that the entire chromosome complement of M. hirsuta was shown to be derivative with respect to species compared in this study.

     

Glycogen synthase kinase 3: a drug target for CNS therapies

Abstract Glycogen synthase kinase3 (GSK3) is emerging as a prominent drug target in the CNS. The most exciting of the possibilities of GSK3 lies within the treatment of Alzheimer's disease (AD) where abnormal increases in GSK3 levels and activity have been associated with neuronal death, paired helical filament tau formation and neurite retraction as well as a decline in cognitive performance. Abnormal activity of GSK3 is also implicated in stroke. Lithium, a widely used drug for affective disorders, inhibits GSK3 at therapeutically relevant concentrations. Thus while the rationale remains testable, pharmaceutical companies are investing in finding a selective inhibitor of GSK3. In the present review, we summarize the properties of GSK3, and discuss the potential for such a therapy in AD, and other CNS disorders.     

Association of high-altitude systemic hypertension with the deletion allele-of the angiotensin-converting enzyme (ACE) gene

People who visit high-altitude areas are exposed to a stressful environment and a good percentage of them suffer from high-altitude-induced diseases, including systemic hypertension. Identification of genetic markers for high-altitude-induced diseases would help to reduce the rate of morbidity/mortality from such diseases. The development of systemic hypertension on exposure to high altitude (3,500 m) for 30 days in otherwise normotensive natives of low-altitudes was investigated. The angiotensin-converting enzyme (ACE) insertion/deletion (I/D) genotypes and renin-angiotensin-aldosterone system were simultaneously studied. In the hypertensives during their stay at high altitude, the ACE D allele frequency was significantly higher than in the normotensives (0.67 versus 0.32 chi(2)(1) = 10.6, P < 0.05). In the normotensives during their stay at high altitude, there was no significant increase in plasma aldosterone levels despite increased plasma renin activity. Results of the present study suggest that environmental changes and pre-existing genetic factors, namely the ACE D allele, might be two of the factors predisposing natives of low altitudes to systemic hypertension, a polygenic disease, at high altitude.     

Variations of scalp, pubic and axillary hair

Hair examinations and comparisons conducted by forensic scientists often provide investigative and associative information. Apart from its length and its natural color, hair displays a morphologic diversity both macroscopically and microscopically. Pseudogenization of 相似文献   

Inhibition versus induction of apoptosis by proteasome inhibitors depends on concentration

We previously established that NF-kappaB DNA binding activity is required for Sindbis Virus (SV)-induced apoptosis. To investigate whether SV induces nuclear translocation of NF-kappaB via the proteasomal degradation pathway, we utilized MG132, a peptide aldehyde inhibitor of the catalytic subunit of the proteasome. 20 microM MG132 completely abrogated SV-induced NF-kappaB nuclear activity at early time points after infection. Parallel measures of cell viability 48 h after SV infection revealed that 20 microM MG132 induced apoptosis in uninfected cells. In contrast, a lower concentration of MG132 (200 nM) resulted in partial inhibition of SV-induced nuclear NF-kappaB activity and inhibition of SV-induced apoptosis without inducing toxicity in uninfected cells. The specific proteasomal inhibitor, lactacystin, also inhibited SV-induced death. Taken together, these results suggest that the pro-apoptotic and anti-apoptotic functions of peptide aldehyde proteasome inhibitors such as MG-132 depend on the concentration of inhibitor utilized and expand the list of stimuli requiring proteasomal activation to induce apoptosis to include viruses.     

In vitro effects of steroid hormones on IgM-secreting cells and IgM secretion in common carp (Cyprinus carpio)

The effects of steroid hormones on in vitro IgM-secreting cells (IgMSC) and IgM secretion by lymphocytes of the lymphoid organs in common carp, Cyprinus carpio were examined by ELISPOT and ELISA assay, respectively. Cells isolated from peripheral blood (PB), spleen and head kidney were cultured for 12, 24 and 48 h either in the absence or in the presence of steroid hormones, i.e. cortisol, testosterone, 11-ketotestosterone (11-KT), and estradiol-17beta (E(2)) at doses of 1, 10 and 100 ng/ml. Cortisol reduced the IgMSC numbers and IgM secretion by cells from all organs. In addition, cortisol induced apoptosis in lymphocytes from all organs. High dose of testosterone showed tissue-specific functions; it reduced the number of IgMSC and amount of IgM secretion by cells from spleen and head kidney, but not in PB, though IgM secretion was suppressed. However, no effects of sex steroids were observed in this study. The results show that sex-specific steroid hormones may have no immunosuppressive effects in common carp.