Occludin phosphorylation: identification of an occludin kinase in brain and cell extracts as CK2

In epithelial and endothelial cells, tight junctions limit paracellular flux of ions, proteins and other macromolecules. However, mechanisms regulating tight junction function are not clear. Occludin, a tight junction protein, undergoes phosphorylation changes in several situations but little is known about occludin kinases. A recombinant C-terminal fragment of occludin is a substrate for a kinase in crude extracts of brain. This activity was purified about 10000-fold and identified as CK2 (casein kinase 2) by peptide mass fingerprinting, immunoblotting and mutation of CK2 sites within the occludin sequence. CK2 is therefore a candidate kinase for regulation of occludin phosphorylation in vivo.     

Genetics of social behaviour in charrs (Salvelinus species)

Juvenile brook charr (Salvelinus fontinalis) are territorial and have high levels of agonistic behaviour. Juvenile lake charr (S. namaycush) rarely show any indication of territoriality and have very low levels of agonistic behaviour. The inheritance of behaviour in their reciprocal hybrids was investigated by multivariate stepwise discriminant analysis. Lateral display, charge, chase, and forage composed the first canonical axis (87.2% of total dispersion). Pooled hybrid means were closer to that of brook charr, suggesting either directional dominance or modification of the behaviour of hybrids in response to water flow. The mean values of reciprocal hybrids were skewed towards the maternal parent, suggesting a maternal effect in the phenotypic expression of behaviour in these fish.     

Unravelling the genetic diversity of ruminal bacteria belonging to the CFB phylum

Molecular biology approaches were employed to examine the genetic diversity of bacteria from the Cytophaga/Flexibacter/Bacteroides (CFB) phylum in the rumen of cattle. By this means we were able to identify cultured strains that represent some of the larger CFB clusters previously identified only by PCR amplification and sequencing. Complete 16S rDNA sequences were obtained for 16 previously isolated rumen strains, including the type strains of Prevotella ruminicola, P. bryantii, P. brevis and P. albensis to represent a wide range of diversity. Phylogenetic analysis of cultured strains revealed the existence of three clusters of ruminal CFB: (i) a cluster of Prevotella strains, which have been found only in the rumen, including the two type strains, P. brevis GA33(T) and P. ruminicola 23(T); (ii) Prevotella spp. that cluster with prevotellas from other ecological niches such as the oral cavity and which include the type strains, P. bryantii B(1)4(T) and P. albensis M384(T); (iii) two Bacteroides spp. strains clustering with B. forsythus of oral origin. In order to establish whether the cultivated isolates cover the whole range of ruminal CFB genetic diversity, 16S rRNA gene sequences were amplified and cloned from DNA extracted from the same rumen samples (one cow in Slovenia, one in Scotland and three in Japan). Sequencing and phylogenetic analysis of 16S rRNA genes confirmed the existence of two superclusters of ruminal Prevotella, one exclusively ruminal and the other including non-ruminal species. In the case of ruminal Bacteroides spp., however, phylogenetic analysis revealed the existence of three new superclusters, one of which has as yet no cultivable counterpart. Interestingly, these Bacteroides clusters were represented almost exclusively by clone libraries from the Japanese cattle and only three sequences were from the European cattle. This study agrees with previous analyses in showing that rumen Prevotella/Bacteroides strains exhibit a remarkable degree of genetic diversity and suggests that different strain groupings may differ greatly in their recovery by cultural methods. The most important conclusion, however, is that cultured strains can be identified that represent some of the larger clusters previously identified only by PCR amplification and sequencing.     

Presymptomatic testing for Huntington's disease

Summary Presymptomatic testing for Huntington's disease (HD) is possible through the use of restriction fragment length polymorphisms (RFLPs) at the closely linked D4S10 locus. Recombination between the HD and D4S10 loci will occur in 4%–5% of meioses, and is a well-recognised complication of predictive testing. Recombination between RFLPs within the D4S10 locus is a rare event and can usually be ignored. We report a case where such an intra-locus recombination frustrated attempts to predict the chance of a high-risk individual inheriting the HD gene.     

DNA profile of a sixteenth century western North Atlantic right whale (Eubalaena glacialis)

Low levels of genetic variability identified within the North Atlantic right whale (Eubalaena glacialis), when compared to the Southern right whale (E. australis) and other large whales, have been suggested to result from population reductions due to whaling. Previous genetic analysis of 218 whale bones from sixteenth century Basque whaling sites in the western North Atlantic revealed only a single right whale bone. We determined the genotypes of 27 microsatellite loci using DNA isolated from this bone. All alleles from the historic specimen occur in the extant western North Atlantic population and both the probability of identity of the specimen and the number of heterozygous loci are similar to that in the extant population. Assessments of how genetically different the historical population might have been suggest genetic characteristics have not changed substantially over four centuries of whaling.     

Mechanical stimuli on C2C12 myoblasts affect myoblast differentiation, focal adhesion kinase phosphorylation and galectin-1 expression: a proteomic approach

Mechanical forces are crucial in the regulation of cell morphology and function. At the cellular level, these forces influence myoblast differentiation and fusion. In this study, we applied mechanical stimuli to embryonic muscle cells using magnetic microbeads, a method shown to apply stress to specific receptors on the cell surface. We showed that mechanical stimuli promote an increase in FAK (focal adhesion kinase) phosphorylation. In order to further shed light in the process of myoblast-induced differentiation by mechanical stimuli, we performed a proteomic analysis. Thirteen proteins were found to be affected by mechanical stimulation including galectin-1, annexin III and RhoGDI (Rho guanine-nucleotide-dissociation inhibitor). In this study, we demonstrate how the combination of this method of mechanical stimuli and proteomic analysis can be a powerful tool to detect proteins that are potentially interacting in biochemical pathways or complex cellular mechanisms during the process of myoblast differentiation. We determined an increase in expression and changes in cellular localization of galectin-1 in mechanically stimulated myoblasts. A potential involvement of galectin-1 in myoblast differentiation is presented.     

Molecular characterization of Clostridium perfringens isolates from humans with sporadic diarrhea: evidence for transcriptional regulation of the beta2-toxin-encoding gene

Clostridium perfringens type A food poisoning is caused by C. perfringens isolates carrying a chromosomal enterotoxin gene (cpe), while non-food-borne gastrointestinal (GI) diseases, such as antibiotic-associated diarrhea (AAD) and sporadic diarrhea (SD), are caused by C. perfringens plasmid cpe isolates. A recent study reported the association of beta2 toxin (CPB2) with human GI diseases, and particularly AAD/SD, by demonstrating that a large percentage of AAD/SD isolates, in contrast to a small percentage of food poisoning isolates, carry the beta2-toxin gene (cpb2). This putative relationship was further tested in the current study by characterizing 14 cpe+ C. perfringens fecal isolates associated with recent cases of human SD in England (referred to hereafter as SD isolates). These SD isolates were all classified as cpe+ type A, and 12 of the 14 cpe+ isolates carry their cpe gene on the plasmid and 2 carry it on the chromosome. Interestingly, cpb2 is present in only 12 plasmid cpe isolates; 11 isolates carry cpe and cpb2 on different plasmids, but cpe and cpb2 are located on the same plasmid in one isolate. C. perfringens enterotoxin is produced by all 14 cpe+ SD isolates. However, only 10 of the 12 cpe+/cpb2+ SD isolates produced CPB2, with significant variation in amounts. The levels of cpb2 mRNA in low- to high-CPB2-producing SD isolates differed to such an extent (30-fold) that this difference could be considered a major cause of the differential level of CPB2 production in vitro by SD isolates. Furthermore, no silent or atypical cpb2 was found in a CPB2 Western blot-negative isolate, 5422/94, suggesting that the lack of CPB2 production in 5422/94 was due to low expression of cpb2 mRNA. This received support from our observation that the recombinant plasmid carrying 5422/94 cpb2, which overexpressed cpb2 mRNA, restored CPB2 production in F4969 (a cpb2-negative isolate). Collectively, our present results suggest that CPB2 merits further study as an accessory toxin in C. perfringens-associated SD.     

First record of Alysia alticola Ashmead (Hymenoptera: Braconidae) in the Neotropical region

Alysia alticola Ashmead, 1890, is recorded for the first time in central Argentina, reared from pig carcasses. This is also the first mention of the genus Alysia Latreille, 1804, in Argentina, which represents the southernmost record in the Neotropical region.     

In the beginning: the initiation of meiosis

The most-critical point of reproductive development in all sexually reproducing species is the transition from mitotic to meiotic cell cycle. Studies in unicellular fungi have indicated that the decision to enter meiosis must be made before the beginning of the premeiotic S phase. Recent data from the mouse suggest that this timing of meiosis initiation is a universal feature shared also by multicellular eukaryotes. In contrast, the signaling cascade that leads to meiosis initiation shows great diversity among species.