Bassoon and the synaptic ribbon organize Ca²+ channels and vesicles to add release sites and promote refilling

At the presynaptic active zone, Ca2+ influx triggers fusion of synaptic vesicles. It is not well understood how Ca2+ channel clustering and synaptic vesicle docking are organized. Here, we studied structure and function of hair cell ribbon synapses following genetic disruption of the presynaptic scaffold protein Bassoon. Mutant synapses--mostly lacking the ribbon--showed a reduction in membrane-proximal vesicles, with ribbonless synapses affected more than ribbon-occupied synapses. Ca2+ channels were also fewer at mutant synapses and appeared in abnormally shaped clusters. Ribbon absence reduced Ca2+ channel numbers at mutant and wild-type synapses. Fast and sustained exocytosis was reduced, notwithstanding normal coupling of the remaining Ca2+ channels to exocytosis. In vitro recordings revealed a slight impairment of vesicle replenishment. Mechanistic modeling of the in vivo data independently supported morphological and functional in vitro findings. We conclude that Bassoon and the ribbon (1) create a large number of release sites by organizing Ca2+ channels and vesicles, and (2) promote vesicle replenishment.     

The NOD2 single nucleotide polymorphisms rs2066843 and rs2076756 are novel and common Crohn's disease susceptibility gene variants

Background

The aims were to analyze two novel NOD2 variants (rs2066843 and rs2076756) in a large cohort of patients with inflammatory bowel disease and to elucidate phenotypic consequences.

Methodology/Principal Findings

Genomic DNA from 2700 Caucasians including 812 patients with Crohn''s disease (CD), 442 patients with ulcerative colitis (UC), and 1446 healthy controls was analyzed for the NOD2 SNPs rs2066843 and rs2076756 and the three main CD-associated NOD2 variants p.Arg702Trp (rs2066844), p.Gly908Arg (rs2066847), and p.Leu1007fsX1008 (rs2066847). Haplotype and genotype-phenotype analyses were performed. The SNPs rs2066843 (p = 3.01×10⁻⁵, OR 1.48, [95% CI 1.23-1.78]) and rs2076756 (p = 4.01×10⁻⁶; OR 1.54, [95% CI 1.28-1.86]) were significantly associated with CD but not with UC susceptibility. Haplotype analysis revealed a number of significant associations with CD susceptibility with omnibus p values <10⁻¹⁰. The SNPs rs2066843 and rs2076756 were in linkage disequilibrium with each other and with the three main CD-associated NOD2 mutations (D''>0.9). However, in CD, SNPs rs2066843 and rs2076756 were more frequently observed than the other three common NOD2 mutations (minor allele frequencies for rs2066843 and rs2076756: 0.390 and 0.380, respectively). In CD patients homozygous for these novel NOD2 variants, genotype-phenotype analysis revealed higher rates of a penetrating phenotype (rs2076756: p = 0.015) and fistulas (rs2076756: p = 0.015) and significant associations with CD-related surgery (rs2076756: p = 0.003; rs2066843: p = 0.015). However, in multivariate analysis only disease localization (p<2×10⁻¹⁶) and behaviour (p = 0.02) were significantly associated with the need for surgery.

Conclusion/Significance

The NOD2 variants rs2066843 and rs2076756 are novel and common CD susceptibility gene variants.     

DNA lesions and cytogenetic changes induced by N-nitrosomorpholine in HepG2, V79 and VH10 cells: the protective effects of Vitamins A, C and E

INTRODUCTION: N-Nitrosomorpholine (NMOR), present in the workplace of tyre chemical factories, is a known hepatocarcinogen. This compound belongs to the group of N-nitrosamines, which are indirect-acting and require metabolic activation. However, the mechanism of its carcinogenic effect is not completely clear. AIMS: The objective of this study was (i) to compare the DNA-damaging and clastogenic effects of NMOR in three cell lines (HepG2, V79 and VH10) with different levels of metabolizing enzymes and (ii) to determine the protective effects of Vitamins A, C and E against deleterious effects of NMOR. METHODS: The exponentially growing cells were pre-treated with Vitamins A, C and E and treated with NMOR. Genotoxic effects of NMOR were evaluated by single-cell gel electrophoresis (SCGE, comet assay), while the chromosomal aberration assay was used for the study of clastogenic effects. KEY RESULTS: NMOR-induced a significant dose-dependent increase of DNA damage as analyzed by SCGE, but the extent of DNA migration in the electric field was unequal in the different cell lines. Although the results obtained by SCGE confirmed the genotoxicity of NMOR in all cell lines studied, the number of chromosomal aberrations was significantly increased only in HepG2 and V79 cells, while no changes were observed in VH10 cells. In HepG2 cells pre-treated with Vitamins A, C and E we found a significant decrease of the percentage of tail DNA induced by NMOR. The reduction of the clastogenic effects of NMOR was observed only after pretreatment with Vitamins A and E; Vitamin C did not alter the frequency of NMOR-induced chromosomal aberrations under the experimental conditions of this study. CONCLUSIONS: The fat-soluble Vitamins A and E, which are dietary constituents, reduce the harmful effects of N-nitrosomorpholine in human hepatoma cells HepG2, which are endowed with the maximal capacity for metabolic activation of several drugs.     

An evaluation of three pesticides: Piritione,supercypermethrin and metolachlor in transformation bioassays of BHK21 and hamster embryo cells

In a study of potential carcinogenicity of pesticides, Piritione, metolachlor (in the form of Dual and VUCHT 524) and Supercypermethrin (in the form of Supercypermethrin EC and Supercypermethrin TP) were assayed for induction of anchorage independent growth of BHK21 cells and morphological transformation of Syrian hamster embryo cells. The activity of these substances in both transformation assays was compared to the activity of the direct-acting ultimate carcinogen N-methyl-N-nitrosourea. In comparison to the very strong transforming activity of N-methyl-N-nitrosourea all pesticides tested with or without S9 fraction manifested a very weak, weak, medium or strong effect. The ability to induce anchorage independent growth was graded as follows: Dual < Supercypermethrin EC < Supercypermethrin TP Piritione < VUCHT 524. Results of Syrian hamster embryo cell transformation assay were very similar to the BKH21 transformation assay. VUCHT 524 strongly induced transformation whereas Dual was inactive. Piritione and Supercypermethrin EC and Supercypermethrin TP elicited a slight but significant positive response.     

Complete genome sequence of Treponema paraluiscuniculi, strain Cuniculi A: the loss of infectivity to humans is associated with genome decay

Treponema paraluiscuniculi is the causative agent of rabbit venereal spirochetosis. It is not infectious to humans, although its genome structure is very closely related to other pathogenic Treponema species including Treponema pallidum subspecies pallidum, the etiological agent of syphilis. In this study, the genome sequence of Treponema paraluiscuniculi, strain Cuniculi A, was determined by a combination of several high-throughput sequencing strategies. Whereas the overall size (1,133,390 bp), arrangement, and gene content of the Cuniculi A genome closely resembled those of the T. pallidum genome, the T. paraluiscuniculi genome contained a markedly higher number of pseudogenes and gene fragments (51). In addition to pseudogenes, 33 divergent genes were also found in the T. paraluiscuniculi genome. A set of 32 (out of 84) affected genes encoded proteins of known or predicted function in the Nichols genome. These proteins included virulence factors, gene regulators and components of DNA repair and recombination. The majority (52 or 61.9%) of the Cuniculi A pseudogenes and divergent genes were of unknown function. Our results indicate that T. paraluiscuniculi has evolved from a T. pallidum-like ancestor and adapted to a specialized host-associated niche (rabbits) during loss of infectivity to humans. The genes that are inactivated or altered in T. paraluiscuniculi are candidates for virulence factors important in the infectivity and pathogenesis of T. pallidum subspecies.     

Prevalence of avian influenza viruses, <Emphasis Type="Italic">Mycobacterium avium</Emphasis>, and <Emphasis Type="Italic">Mycobacterium avium</Emphasis>, subsp. <Emphasis Type="Italic">paratuberculosis</Emphasis> in marsh-dwelling passerines in Slovakia, 2008

Prevalence of the infectious respiratory agens, avian influenza virus (AIV), Mycobacterium avium (M. avium), and Mycobacterium avium subspecies paratuberculosis (MAP), was studied in migratory marsh-dwelling passerines captured in the Parížske močiare wetlands in Western Slovakia during 2008. Surveillance of 650 birds revealed a lower prevalence of AIV in spring (13.6%) than in summer (17.5%). A total of 14 different subtypes were detected in samples obtained from birds captured during the spring, with the most prevalent subtypes being H8N3, H6N4, H11N6 and H12N6. Subtypes H12N6, H6N6 and H2N5 were predominant in passerines captured during summer months. In eight cases, different AIV infections were detected in the oropharyngeal and cloacal samples originating from a single bird (H1N1 and H8N3; H1N3 and H9N3; H2N3 and H12N6; H2N1 and H8N1; H4N2 and H9N6; H5N5 and H11N6; H6N4 and H11N6; H7N1 and H10N3 in the oropharynx and cloaca, respectively). M. avium was detected in 9.2% and 0.8% of marsh-dwelling passerines captured during spring and summer, respectively. Only two birds were co-infected with AIV and M. avium. All birds were negative for MAP.     

Postnatal development of nitrergic and cholinergic structures in rat spinal cord

Nitric oxide (NO) is known to be a freely diffusible gaseous neurotransmitter that is not requiring synaptic connection to exert its effects. Nitric oxide synthase (NOS), the enzyme responsible for NO synthesis can be visualised by nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry. Other neurotransmitter is a classical neurotransmitter acetylcholine (ACh), regulated by enzyme acetylcholinesterase (AChE) that hydrolyses the acetylcholine after its releasing. This work is presenting results of histochemical study of the NADPH-d and AChE expression (nitrergic and cholinergic neurons) in the spinal cord (SC) during various periods in its development. Specimens from Wistar rat pups in the age ranging from 1st to 21st postnatal days (P1-P21) have been compared with those of adult rats (P90). Transverse sections of the SC were evaluated by light microscope. In adults, the NADPH-d positivity was detectable in the neurons of superficial and deep layers of the dorsal horn, pericentral area and in the area of preganglionic autonomic nuclei. AChE positive structures were seen in the same locations as previous ones with the exception of two locations: in superficial layers of the dorsal horn AChE staining was absent, while in the ventral horn the groups of AChE positive motoneurons were found. At the perinatal period both NADPH-d and AChE positive neurons were stained from slight to moderate intensity only. During later developmental periods the staining gradually increased and achieved adult level of intensity on the day P21. Our results confirmed the presence of nitrergic and cholinergic neurons in investigated areas of the SC and indicated their fully functioning of NADPH-d and AChE positive structures in SC from the third postnatal week.     

Hybridization between diploid Centaurea pseudophrygia and tetraploid C. jacea (Asteraceae): the role of mixed pollination,unreduced gametes,and mentor effects

We studied hybridization between the diploid Centaurea pseudophrygia and the tetraploid C. jacea by performing crossing experiments and screening natural populations using flow cytometry. The experiments confirm that the studied species exhibit strong reproductive isolation. Interspecific hybrids were formed at a low frequency, including triploids (originating from reduced gametes) and tetraploids (involving unreduced gametes of the diploids). In contrast, hybrids were almost absent among seeds and adult plants of natural mixed populations and among the offspring from experimental pollinations with a mixture of pollen of both ploidy levels. We found that mixed pollination is an important mechanism for preventing hybridization between plants of different ploidy levels and sustaining the reproduction of the tetraploids. A mentor effect (induced selfing in the presence of pollen of different ploidy levels) was observed in both diploids and tetraploids, reinforcing the reproductive isolation between cytotypes. Higher ploidy levels (pentaploid, hexaploid) involving unreduced gametes of the tetraploid species were identified. Notably, pentaploids were discovered for the first time in Centaurea sect. Jacea. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 93–106.     

Proteomic analysis of MOLT-4 cells treated by valproic acid

The effect of valproic acid (VA) on protein expression in human T-lymphocytic leukemia cells MOLT-4 was studied. VA is an inhibitor of histonedeacetylases and has a potential use as antitumor agent in leukemia treatment. The authors in this work prove that 4 h long incubation with 2 mmol/l VA causes phosphorylation of histone H2A.X and its colocalization with 53BP1 in nuclear foci. Their co-localization is typical for DSB signaling machinery. These foci were detected in cells after 4 h exposure without increase of Annexin V positive apoptotic cells. Slight increase in apoptosis (Annexin V positivity) after 24 h is accompanied by more intensive increase in phosphorylation of H2A.X and also by formation of nuclear foci containing γH2A.X and 53BP1. Treatment of cells with 2 mmol/l VA resulted in induction of apoptosis affecting about 30% of cells after incubation for 72 h. The changes in protein expression were examined after cell incubation with 2 mmol/l VA for 4 h. Proteins were separated by two-dimensional electrophoresis and quantified using image evaluation system. Those exhibiting significant VA-induced abundance alterations were identified by mass spectrometry. Changes in expression of 22 proteins were detected, of which 15 proteins were down-regulated. Proteomic analysis resulted in successful identification of three proteins involving alfa-tubulin 3, tubulin-specific chaperone and heterogeneous nuclear ribonucloprotein F. Expression of seven proteins was up-regulated, including heterogeneous nuclear ribonucloprotein A/B. Identified proteins are related to microtubular system and hnRNP family. Suppression of microtubular proteins and changes of balance among hnRNPs can contribute to proliferation arrest and apoptosis induction.