Expression of cellular retinoic acid-binding protein I and II (CRABP I and II) in embryonic mouse hearts treated with retinoic acid

Cellular retinoic acid binding proteins are considered to be involved in retinoic acid (RA) signaling pathways. Our aim was to compare the expression and localization of cellular retinoic acid binding proteins I and II (CRABP I and II) in embryonic mouse hearts during normal development and after a single teratogenic dose of RA. Techniques such as real-time PCR, RT-PCR, Western blots and immunostaining were employed to examine hearts from embryos at 9-17 dpc. RA treatment at 8.5dpc affects production of CRABP I and II in the heart in the 48-h period. Changes in expression of mRNA for retinaldehyde dehydrogenase II (Raldh2), Crabp1 and Crabp2 genes also occur within the same time window (i.e. 10-11dpc) after RA treatment. In the embryonic control heart these proteins are localized in groups of cells within the outflow tract (OT), and the atrioventricular endocardial cushions. A gradient of labeling is observed with CRABP II but not for CRABP I along the myocardium of the looped heart at 11 dpc; this gradient is abolished in hearts treated with RA, whereas an increase of RALDH2 staining has been observed at 10 dpc in RA-treated hearts. Some populations of endocardial endothelial cells were intensively stained with anti-CRABP II whereas CRABP I was negative in these structures. These results suggest that CRABP I and II are independently regulated during heart development, playing different roles in RA signaling, essential for early remodeling of the heart tube and alignment of the great arteries to their respective ventricles.     

Disentangling the formation of contrasting tree-line physiognomies combining model selection and Bayesian parameterization for simulation models

Alpine tree-line ecotones are characterized by marked changes at small spatial scales that may result in a variety of physiognomies. A set of alternative individual-based models was tested with data from four contrasting Pinus uncinata ecotones in the central Spanish Pyrenees to reveal the minimal subset of processes required for tree-line formation. A Bayesian approach combined with Markov chain Monte Carlo methods was employed to obtain the posterior distribution of model parameters, allowing the use of model selection procedures. The main features of real tree lines emerged only in models considering nonlinear responses in individual rates of growth or mortality with respect to the altitudinal gradient. Variation in tree-line physiognomy reflected mainly changes in the relative importance of these nonlinear responses, while other processes, such as dispersal limitation and facilitation, played a secondary role. Different nonlinear responses also determined the presence or absence of krummholz, in agreement with recent findings highlighting a different response of diffuse and abrupt or krummholz tree lines to climate change. The method presented here can be widely applied in individual-based simulation models and will turn model selection and evaluation in this type of models into a more transparent, effective, and efficient exercise.     

Evaluation of the API ZYM system and RPMI agar plates supplemented with Tween 40 for detection of lipolytic enzymes of Candida spp

Lipolytic activity of 40 strains of Candida spp. was tested on API ZYM system and on RPMI agar plates supplemented with 1% Tween 40. Lipolytic activity was indicated by opaque zones around the inoculum cylindrical holes were punched in the medium. Clearing of the medium around the bacterial colonies indicated that an isolate produce lipase. Only 4 (21.1%) strains of C. albicans, and 3 (14.1%) strains of non-C. albicans which hydrolyzed 2-naftylomirystylan by use of the API ZYM system was observed. In contrast, 16 (78.9%) strains of C. albicans and 17 (80.7%) strains of non-C. albicans produced lipases on the agar plate using RPMI agar plates supplemented with 1.0% Tween 40. Determination oflipase activities with the API ZYM system were in no agreement with lipase tests in RPMI supplemented with Tween 40. Our study verify greater usefulness of RPMI supplemented with Tween 40 for detection of lipolytic enzymes of Candida species in comparison to the API ZYM.     

Extracellular hydrolytic enzymes produced by entomopathogenic fungi--role in an infection process

Entomopathogenic fungi have a great potential in biological control of insect pest population. Fungal pathogens are promising source of insecticides and notable alterative to chemical pesticides. These fungi possess a unique mechanism of insects paralysis. As natural enemies of insects they attack direct host cuticle via a combination of mechanical pressure and cuticle-degrading enzymes. Entomopathogenic fungi produce several proteo-, chitino- and lipolytic enzymes, which are accepted as key factors in insect mycosis. The role of extracellular enzymes in pathogenesis is still not well understood. Profound understanding the mechanisms of insect paralysis by entomopathogenic fungi will help in the production of safer for environment and more efficiency mycoinsecticides.     

Proinflammatory chemokine gene expression influences survival of patients with non-Hodgkin's lymphoma

The migration, survival and proliferation of cells is the basis for all physiologic and pathologic processes in the human body. All these reactions are regulated by a complex chemokine network that guides lymphocytes homing, chemotaxis, adhesion and interplay between immunologic system response cells. Chemokines are also responsible for metastatic dissemination of cancers, including Hodgkin's and non-Hodgkin's lymphomas. The purpose of this study was to determine chemokine gene expression (CXCL8, CXCL10, CCL2, CCL3, CCL4 and CCL5) in lymphoma lymph nodes compared to their expression in reactive lymph nodes. We also analyzed the influence of chemokine gene expression on the survival of lymphoma patients. Chemokine gene expression was evaluated in 37 lymphoma lymph nodes and in 25 samples of reactive lymph nodes. Gene expression of chemokines CXCL8, CXCL10, CCL2, CCL3, CCL4 and CCL5 was measured using the PCR method. Statistical analysis was performed using CSS Statistica for Windows (version 7.0) software. Probability values 〈 〈 0.05 were considered statistically significant and those between 0.05 and 0.1 as indicative of a trend. We found lower CXCL8 and CXCL10 gene expression in lymphoma lymph nodes compared to reactive lymph nodes. In the cases of CCL2 and CCL3, expression in lymphomas was higher than in reactive lymph nodes. Patients with high expression of CCL2 and CXCL10 had shorter survival.     

On the evolution of group-escape strategies of selfish prey

The phenomenon of group escape cannot be explained by an argument of risk dilution, applied to gregarious behaviour of passive prey whose risk of predation is equally shared by all group members (Hamilton, 1971). Instead, individuals at the tail of an escaping group suffer the bulk of the group’s predation risk, and thus have the highest incentive to desert it. Just because of this, desertion, in this case, may serve as a signal of vulnerability for the pursuing predator. Under wide conditions, it is therefore shown that the predator is always expected to prefer the chasing of a deserter, whenever it is observed. Consequently, an individual who finds himself at the tail of the herd must compare the risk of remaining there with that of deserting the herd and thereby becoming a likely target for predation. If the first risk is higher than the latter, the herd disperses; if the latter is higher, the herd cohesively follows the fastest individuals in its lead (we deal also with cases in which only part of the herd disperses). We see, however, that the question which risk is higher depends not only on the terrain, but also on the route of escape that is decided by the fastest members at the lead of the herd, those that are least likely to be caught. Concentrating on herds without family structure, we assume that the route of escape is selfishly chosen by these ad hoc leaders to minimize their own predation risk, regardless of the others’ welfare. However, the predation risk of the leader depends very much on the willingness of other herd members to follow him, thus providing a buffer between him and the pursuing predator. Consequently, when choosing an escape route, the leader has also to consider the cohesion of the herd, i.e., the reaction of slower individuals to his choice. Under some plausible conditions, this choice may force the herd to follow, while other conditions may lead to its dispersal. In some cases the leader may choose a route that serves the needs of the entire group, and sometime only those of its more vulnerable members. In other cases the leader may choose a route that sacrifices the weakest members, thereby improving the survival probability of the others.We employ a model of a k+1 players game, a single predator, and k heterogeneous prey individuals. The predator aims to maximize the probability of a successful catch, and each individual aims to minimize his probability of being caught.     

An exopolysaccharide produced by the novel halophilic bacterium <Emphasis Type="Italic">Halomonas stenophila</Emphasis> strain B100 selectively induces apoptosis in human T leukaemia cells

Microbial exopolysaccharides (EPSs) are highly heterogeneous polymers produced by fungi and bacteria and have recently been attracting considerable attention from biotechnologists because of their potential applications in many fields, including biomedicine. We have screened the antitumoural activity of a panel of sulphated EPSs produced by a newly discovered species of halophilic bacteria. We found that the novel halophilic bacterium Halomonas stenophila strain B100 produced a heteropolysaccharide that, when oversulphated, exerted antitumoural activity on T cell lines deriving from acute lymphoblastic leukaemia (ALL). Only tumour cells were susceptible to apoptosis induced by the sulphated EPS (B100S), whilst primary T cells were resistant. Moreover, freshly isolated primary cells from the blood of patients with ALL were also susceptible to B100S-induced apoptosis. The newly discovered B100S is therefore the first bacterial EPS that has been demonstrated to exert a potent and selective pro-apoptotic effect on T leukaemia cells, and thus, we propose that the search for new antineoplastic drugs should include the screening of other bacterial EPSs, particularly those isolated from halophiles.     

Iron(III) complexation by Vanchrobactin, a siderophore of the bacterial fish pathogen Vibrio anguillarum

The bacterial fish pathogen Vibrio anguillarum serotype O2 strain RV22 produces the mono catecholate siderophore Vanchrobactin (Vb) under conditions of iron deficiency. Vb contains two potential bidentate coordination sites: catecholate and salicylate groups. The iron(III) coordination properties of Vb is investigated in aqueous solutions using spectrophotometric and potentiometric methods. The stepwise equilibrium constants (log?K) for successive addition of Vb dianion to a ferric ion are 19.9; 13.3, and 9.5, respectively, for an overall association constant of 42.7. Based on the previous results, we estimated the equilibrium concentration of free iron(III) under physiological conditions for pH 7.4 solution containing 10(-6) M total iron and 10(-5) M total Vb as pFe = 20 (=-log[Fe(3+)]). The Vb model compounds catechol (Cat) and 2,4-dihydroxy-N-(2-hydroxyethyl)benzamide (Dhb) have also been examined, and the obtained results show that the interaction of the whole system of Vb that contains the ferric-chelating groups of both Dhb and Cat, is synergically greater than the separate parts; i.e. Vb is the best chelating agent either in acid or basic media. In summary, bacteria employing Vb-mediated iron transport thus are able to compete effectively for iron with other microorganisms within which they live.     

The phytoplankton Nannochloropsis oculata enhances the ability of Roseobacter clade bacteria to inhibit the growth of fish pathogen Vibrio anguillarum

Background

Phytoplankton cultures are widely used in aquaculture for a variety of applications, especially as feed for fish larvae. Phytoplankton cultures are usually grown in outdoor tanks using natural seawater and contain probiotic or potentially pathogenic bacteria. Some Roseobacter clade isolates suppress growth of the fish pathogen Vibrio anguillarum. However, most published information concerns interactions between probiotic and pathogenic bacteria, and little information is available regarding the importance of phytoplankton in these interactions. The objectives of this study, therefore, were to identify probiotic Roseobacter clade members in phytoplankton cultures used for rearing fish larvae and to investigate their inhibitory activity towards bacterial fish pathogens in the presence of the phytoplankton Nannochloropsis oculata.

Methodology/Principal Findings

The fish pathogen V. anguillarum, was challenged with 6 Roseobacter clade isolates (Sulfitobacter sp. (2 strains), Thalassobius sp., Stappia sp., Rhodobacter sp., and Antarctobacter sp.) from phytoplankton cultures under 3 different nutritional conditions. In an organic nutrient-rich medium (VNSS), 6 Roseobacter clade isolates, as well as V. anguillarum, grew well (10⁹ CFU/ml), even when cocultured. In contrast, in a phytoplankton culture medium (ESM) based on artificial seawater, coculture with the 6 isolates decreased the viability of V. anguillarum by approximately more than 10-fold. Excreted substances in media conditioned by growth of the phytoplankton N. oculata (NCF medium) resulted in the complete eradication of V. anguillarum when cocultured with the roseobacters. Autoclaved NCF had the same inhibitory effect. Furthermore, Sulfitobacter sp. much more efficiently incorporated ¹⁴C- photosynthetic metabolites (¹⁴C-EPM) excreted by N. oculata than did V. anguillarum.

Conclusion/Significance

Cocultures of a phytoplankton species and Roseobacter clade members exhibited a greater antibacterial effect against an important fish pathogen (V. anguillarum) than roseobacters alone. Thus, cooperation of N. oculata, and perhaps other phytoplankton species, with certain roseobacters might provide a powerful tool for eliminating fish pathogens from fish-rearing tanks.