Chromosomal characterization of two species of genus <Emphasis Type="Italic">Steatogenys</Emphasis> (Gymnotiformes: Rhamphichthyoidea: Steatogenini) from the Amazon basin: sex chromosomes and correlations with Gymnotiformes phylogeny

Gymnotiformes are an important component of the Neotropical ichthyofauna and they are known for their ability to generate and detect electrical discharges. Phylogenetic relationships of Gymnotiformes are still not well understood. However, the monophyly of the superfamily Rhamphichthyoidea is well accepted, despite the position of tribe Steatogenini (Steatogenys, Hypopygus and Stegostenopos) within this superfamily is unclear. The genus Steatogenys includes three species that, together with Hypopygus and Stegostenopos, form tribe Steatogenini. Cytogenetic information is currently only available for Hypopygus lepturus. Here, we describe the karyotypes of Steatogenys elegans from four localities and S. duidae from two localities. S. elegans was found to have 2n = 50, ZZ/ZW (12m-sm/38st-a), while S. duidae had 2n = 50 (50m-sm). In S. elegans, constitutive heterochromatin (CH) was observed in the centromeric regions of all chromosomes, in the interstitial region of 1q, and in two blocks of Wq. In S. duidae, CH was observed in the centromeric and pericentromeric regions of all chromosomes, and in the interstitial regions of 2q, 3q, 5q, and 7q. Nucleolar organizer regions (NORs) were identified in the distal regions of one chromosome pair in each species. The CMA₃ fluorochrome (specific to G-C rich regions) coincided with the NORs in both species, and with the HC of S. elegans except on chromosome pair 5 and the W. The DAPI fluorochrome (specific to A-T rich regions) coincided with the CH of both species, and was very intense for chromosome pair 5 and the W of S. elegans. Our observations suggest that the ZZ/ZW system observed in S. elegans likely evolved through CH addition followed by a paracentric inversion. The chromosomal data described herein are consistent with the phylogenetic hypothesis that tribe Steatogenini should be positioned within family Ramphychthyidae.     

CXCL12 rs1801157 polymorphism and expression in peripheral blood from breast cancer patients

The role of chemokines has been extensively analyzed both in cancer risk and tumor progression. Among different cytokines, CXCR4 and its ligand CXCL12 have been recently subjected to a closer examination. The single-nucleotide polymorphism (SNP) rs1801157 (previously known as CXCL12-A/SDF1-3'A) in the CXCL12 gene and the relative expression of mRNA CXCL12 in peripheral blood were assessed in breast cancer patients, since the chemokine CXCL12 and its receptor CXCR4 regulate leukocyte trafficking and many essential biological processes, including tumor growth, angiogenesis and metastasis of different types of tumors. Genotyping was performed by PCR-RFLP (polymerase chain reaction followed by restriction fragment length polymorphism) using MspI restriction enzyme and the expression analyses by quantitative RT-PCR. No difference in GG genotype and allele A carrier frequencies were observed between breast cancer patients and healthy blood donors and nor when CXCL12 mRNA expression was assessed among patients with different tumor stages. However a significant difference was observed when CXCL12 mRNA relative expression was analyzed in breast cancer patients in accordance to the presence or absence of the CXCL12 rs1801157 allele A. Allele A breast cancer patients presented a mRNA CXCL12 expression about 2.1-fold smaller than GG breast cancer patients. Estrogen positive patients presenting CXCL12 allele A presented a significantly lower expression of CXCL12 in peripheral blood (p=0.039) than GG hormone positive patients. Our findings demonstrated that allele A is associated with low expression of CXCL12 in the peripheral blood from ER-positive breast cancer patients, which suggests implications on breast cancer clinical outcome.     

Synthetic arylquinuclidine derivatives exhibit antifungal activity against Candida albicans, Candida tropicalis and Candida parapsilopsis

Background

Severely burned patients may develop life-threatening nosocomial infections due to Pseudomonas aeruginosa, which can exhibit a high-level of resistance to antimicrobial drugs and has a propensity to cause nosocomial outbreaks. Antiseptic and topical antimicrobial compounds constitute major resources for burns care but in vitro testing of their activity is not performed in practice.

Results

In our burn unit, a P. aeruginosa clone multiresistant to antibiotics colonized or infected 26 patients over a 2-year period. This resident clone was characterized by PCR based on ERIC sequences. We investigated the susceptibility of the resident clone to silver sulphadiazine and to the main topical antimicrobial agents currently used in the burn unit. We proposed an optimized diffusion assay used for comparative analysis of P. aeruginosa strains. The resident clone displayed lower susceptibility to silver sulphadiazine and cerium silver sulphadiazine than strains unrelated to the resident clone in the unit or unrelated to the burn unit.

Conclusions

The diffusion assay developed herein detects differences in behaviour against antimicrobials between tested strains and a reference population. The method could be proposed for use in semi-routine practice of medical microbiology.     

Utility of characteristic QTOF MS/MS fragmentation for MHC class I peptides

Systematic investigation of cellular process by mass spectrometric detection of peptides obtained from proteins digestion or directly from immuno-purification can be a powerful tool when used appropriately. The true sequence of these peptides is defined by the interpretation of spectral data using a variety of available algorithms. However peptide match algorithm scoring is typically based on some, but not all, of the mechanisms of peptide fragmentation. Although algorithm rules for soft ionization techniques generally fit very well to tryptic peptides, manual validation of spectra is often required for endogenous peptides such as MHC class I molecules where traditional trypsin digest techniques are not used. This study summarizes data mining and manual validation of hundreds of peptide sequences from MHC class I molecules in publically available data files. We herein describe several important features to improve and quantify manual validation for these endogenous peptides--post automated algorithm searching. Important fragmentation patterns are discussed for the studied MHC Class I peptides. These findings lead to practical rules that are helpful when performing manual validation. Furthermore, these observations may be useful to improve current peptide search algorithms or development of novel software tools.     

Phylogeny of Celastraceae subfamily Hippocrateoideae inferred from morphological characters and nuclear and plastid loci

The phylogeny of Celastraceae subfamily Hippocrateoideae (～ 100 species and 19 genera in the Old and New World tropics) was inferred using morphological characters together with plastid (matK, trnL-F) and nuclear (ITS and 26S rDNA) genes. The subfamily is easily recognized by the synapomorphies of transversely flattened, deeply lobed capsules and seeds with membranous basal wings or narrow stipes together with bisexual, 5-merous flowers that generally have an extrastaminal disk and three stamens. Hippocrateoideae, like Salacioideae, are inferred to have an Old World origin. The narrow stipes of Neotropical species that are water-dispersed are inferred to be derived within the subfamily from ancestral species with wind-dispersed winged seeds. Helictonema, a monotypic genus endemic to tropical Africa, has a small, white, spongy aril that is located at the base of the seed wing and appears to be unique within Hippocrateoideae. Our inference that Helictonema is sister to the remaining members of the subfamily, considered in the context of Sarawakodendron being sister to Salacioideae, suggests that small arils and capsular fruit were primitive within both subfamilies. The aril became dramatically enlarged within Salacioideae, in which the fruits are berries, and lost entirely within Hippocrateoideae, in which the fruits are transversely flattened capsules. All five Old World taxa of Prionostemma and all eight currently recognized species within Simirestis are transferred to Pristimera, one South African variety of Pristimera is raised to species level, and all three taxa in Pristimera subgenus Trochantha are transferred to the new genus Trochantha.     

Reactive oxygen species participate in the p38-mediated apoptosis induced by potassium deprivation and staurosporine in cerebellar granule neurons

Apoptosis induced by low potassium (K5) or staurosporine in cerebellar granule neurons triggers an increase in reactive oxygen species (ROS) levels. ROS inhibition by antioxidants or inhibitors of the NADPH oxidase (NOX) activity reduces the apoptosis induced by both stimuli. It has been reported that JNK mediates the apoptosis induced by K5 but not by staurosporine. No information is available about the role of other signaling pathways such as p38 in staurosporine-induced apoptosis, and whether p38 activation could be related to ROS levels induced by both K5 and staurosporine. Here, we explored this possibility and found that K5 activates p38 and ATF2 and that the inhibition of p38 activity prevents the apoptosis induced by this treatment. We also found that p38 is downstream of ROS generation induced by K5. On the other hand, staurosporine promotes a sustained activation of p38. We found that p38 inhibition markedly decreases ROS generation, NOX activity and apoptosis induced by staurosporine. Furthermore, antioxidants inhibit p38 activation induced by staurosporine. These data indicate that apoptosis induced by both K5 and staurosporine is dependent on p38 activation, which is mediated by ROS. In addition, p38 activation by staurosporine induces a further production of ROS through NOX activation.