Characterization of the interaction of Escherichia coli heat-stable enterotoxin (STa) with its putative receptor on the intestinal tract of newborn calves

Enterotoxigenic Escherichia coli (ETEC) induces severe diarrhea in newborn calves through the elaboration of heat-stable enterotoxin (STa). We investigated the distribution and characteristics of the STa-specific receptors on enterocytes and brush border membrane vesicles (BBMVs) prepared from anterior jejunum, posterior jejunum, ileum and colon of newborn calves. We found that density of the receptors and their affinity to STa were higher on enterocytes and BBMVs that were derived from the ileum than enterocytes and BBMVs prepared from other segments of the calf intestine. This study suggests that, in newborn calves, the ileum is the major part of the intestinal tract that is affected in the course of secretory diarrhea caused by STa-producing ETEC strains.     

Evaluation of neem seed powder for Fusarium wilt and Meloidogyne control on tomato

Fusarium wilt and root-knot are important diseases of tomato. The use of chemical is becoming less appealing because of the health implications. Also, the chemicals required are often not within the reach of farmers in most of the developing part of the world. This research is aimed at finding an alternative mode of control. Tomato variety Roma VF inoculated with Meloidogyne and Fusarium were treated with 2 g/kg soil neem seed powder in the screenhouse and 2 Mg ha ^{? 1} in the field. An untreated and Furadan treated plot in the field served as control. Neem seed powder significantly reduced the disease severity of Fusarium and root-knot in both screenhouse and field. Results suggest the possible use of neem seed powder for control of the root-knot nematodes - Fusarium wilt disease complex.     

Testing statistical significance scores of sequence comparison methods with structure similarity

Background  

In the past years the Smith-Waterman sequence comparison algorithm has gained popularity due to improved implementations and rapidly increasing computing power. However, the quality and sensitivity of a database search is not only determined by the algorithm but also by the statistical significance testing for an alignment. The e-value is the most commonly used statistical validation method for sequence database searching. The CluSTr database and the Protein World database have been created using an alternative statistical significance test: a Z-score based on Monte-Carlo statistics. Several papers have described the superiority of the Z-score as compared to the e-value, using simulated data. We were interested if this could be validated when applied to existing, evolutionary related protein sequences.     

Identifying dynamical modules from genetic regulatory systems: applications to the segment polarity network

Background  

It is widely accepted that genetic regulatory systems are 'modular', in that the whole system is made up of smaller 'subsystems' corresponding to specific biological functions. Most attempts to identify modules in genetic regulatory systems have relied on the topology of the underlying network. However, it is the temporal activity (dynamics) of genes and proteins that corresponds to biological functions, and hence it is dynamics that we focus on here for identifying subsystems.     

Increased levels of (class switched) memory B cells in peripheral blood of current smokers

There is increasing evidence that a specific immune response contributes to the pathogenesis of COPD. B-cell follicles are present in lung tissue and increased anti-elastin titers have been found in plasma of COPD patients. Additionally, regulatory T cells (Tregs) have been implicated in its pathogenesis as they control immunological reactions. We hypothesize that the specific immune response in COPD is smoke induced, either by a direct effect of smoking or as a result of smoke-induced lung tissue destruction (i.e. formation of neo-epitopes or auto antigens). Furthermore, we propose that Tregs are involved in the suppression of this smoke-induced specific immune response.The presence of B cells, memory B cells and Tregs was assessed by flow cytometry in peripheral blood of 20 COPD patients and 29 healthy individuals and related to their current smoking status.COPD patients had lower (memory) B-cell percentages and higher Treg percentages in peripheral blood than healthy individuals, with a significant negative correlation between these cells. Interestingly, current smokers had higher percentages of (class-switched) memory B cells than ex-smokers and never smokers, irrespective of COPD.This increase in (class-switched) memory B cells in current smokers is intriguing and suggests that smoke-induced neo-antigens may be constantly induced in the lung. The negative correlation between B cells and Tregs in blood is in line with previously published observations that Tregs can suppress B cells. Future studies focusing on the presence of these (class switched) memory B cells in the lung, their antigen specificity and their interaction with Tregs are necessary to further elucidate the specific B-cell response in COPD.     

<Emphasis Type="Italic">In vitro</Emphasis> and <Emphasis Type="Italic">ex vivo</Emphasis> effect of hyaluronic acid on erythrocyte flow properties

Background  

Hyaluronic acid (HA) is present in many tissues; its presence in serum may be related to certain inflammatory conditions, tissue damage, sepsis, liver malfunction and some malignancies. In the present work, our goal was to investigate the significance of hyaluronic acid effect on erythrocyte flow properties. Therefore we performed in vitro experiments incubating red blood cells (RBCs) with several HA concentrations. Afterwards, in order to corroborate the pathophysiological significance of the results obtained, we replicated the in vitro experiment with ex vivo RBCs from diagnosed rheumatoid arthritis (RA) patients, a serum HA-increasing pathology.     

Assessment of the relative contribution of asexual propagation in a population of the coral-excavating sponge Cliona delitrix from the Bahamas

Cliona delitrix is a very destructive coral-excavating sponge in Caribbean coral reef systems, particularly for Montastraea species. Little is known about how these excavating sponges propagate across coral reefs. In this study a hypothesis was tested that coral breakage caused by the bioeroding activity facilitates the asexual propagation of this sponge and in turn favors the spread of the most aggressive sponge genotypes. An allozyme analysis, involving 12 loci systems of 52 sponge individuals from a total of 13 Montastraea heads, found that no two sponges possessed identical multi-locus genotypes. Contrary to the pattern expected for fragmenting species, the incidence of clonality and asexual propagation at the population level was minimal. The lack of correlation between genetic and physical distances for the studied sponges also suggests that population maintenance appears to derive from larval dispersal, with a spatial range of dispersal larger than the average distance between the coral heads (10–10² m).     

Programmed cell death during development of cowpea (Vigna unguiculata (L.) Walp.) seed coat

The seed coat develops primarily from maternal tissues and comprises multiple cell layers at maturity, providing a metabolically dynamic interface between the developing embryo and the environment during embryogenesis, dormancy and germination of seeds. Seed coat development involves dramatic cellular changes, and the aim of this research was to investigate the role of programmed cell death (PCD) events during the development of seed coats of cowpea [Vigna unguiculata (L.) Walp.]. We demonstrate that cells of the developing cowpea seed coats undergo a programme of autolytic cell death, detected as cellular morphological changes in nuclei, mitochondria, chloroplasts and vacuoles, DNA fragmentation and oligonucleosome accumulation in the cytoplasm, and loss of membrane viability. We show for the first time that classes 6 and 8 caspase‐like enzymes are active during seed coat development, and that these activities may be compartmentalized by translocation between vacuoles and cytoplasm during PCD events.