Adhesive papillae on the brachiolar arms of brachiolaria larvae in two starfishes, Asterina pectinifera and Asterias amurensis, are sensors for metamorphic inducing factor(s)

It has been hypothesized by Barker that starfish brachiolaria larvae initiate metamorphosis by sensing of metamorphic inducing factor(s) with neural cells within the adhesive papillae on their brachiolar arms. We present evidence supporting Barker's hypothesis using brachiolaria larvae of the two species, Asterina pectinifera and Asterias amurensis. Brachiolaria larvae of these two species underwent metamorphosis in response to pebbles from aquaria in which adults were kept. Time-lapse analysis of A. pectinifera indicated that the pebbles were explored with adhesive papillae prior to establishment of a stable attachment for metamorphosis. Microsurgical dissections, which removed adhesive papillae, resulted in failure of the brachiolaria larvae to respond to the pebbles, but other organs such as the lateral ganglia, the oral ganglion, the adhesive disk or the adult rudiment were not required. Immunohistochemical analysis with a neuron-specific monoclonal antibody and transmission electron microscopy revealed that the adhesive papillae contained neural cells that project their processes towards the external surface of the adhesive papillae and they therefore qualify as sensory neural cells.     

Regulators of protein metabolism are affected by cyclical nutritional treatments with diets varying in protein and energy content

There is evidence that the E3 ubiquitin ligases muscle ring finger-1 (MuRF1) and atrogin-1, which mediate the ubiquitination of certain proteins and thereby their proteolysis, are regulated by cyclical nutritional treatments varying in lysine content. In order to explore further the regulatory mechanisms involved in metabolic adaptation to dietary changes, we investigated the effects of daily variations in energy [2800 (E?) followed by 3200 kcal/kg (E+)], protein [230 (P+) followed by 150g/kg (P?)] or both [E?P+ followed by E+P?] on muscle protein metabolism in 2-week-old male broiler chickens. Growth performance was similar for all treatments. Expression of atrogin-1 and MuRF1 was changed by alternation of diets varying in protein (higher expression with P? vs. P+) and energy content (higher expression with E? vs. E+). The expression of atrogin-1 was regulated with mixed diets (increase in E+P? vs. E?P+) but not that of MuRF1. Such regulation may involve the mammalian target of rapamycin (mTOR), which was more phosphorylated with P+ than with P?. Eukaryotic initiation factor 4E binding protein, p70S6 kinase and ribosomal protein S6, which are mTOR targets known to control protein synthesis, were highly activated by increased protein content (P+ vs. P?). The mechanisms coordinating the protein synthesis/proteolysis balance remain to be characterized.     

Solution structure of the recombinant penaeidin-3, a shrimp antimicrobial peptide

Penaeidins are a family of antimicrobial peptides of 47-63 residues isolated from several species of shrimp. These peptides display a proline-rich domain (N-terminal part) and a cysteine-rich domain (C-terminal part) stabilized by three conserved disulfide bonds whose arrangement has not yet been characterized. The recombinant penaeidin-3a of Litopenaeus vannamei (63 residues) and its [T8A]-Pen-3a analogue were produced in Saccharomyces cerevisiae and showed similar antimicrobial activity. The solution structure of the [T8A]-Pen-3a analogue was determined by using two-dimensional 1H NMR and simulated annealing calculations. The proline-rich domain, spanning residues 1-28 was found to be unconstrained. In contrast, the cysteine-rich domain, spanning residues 29-58, displays a well defined structure, which consists of an amphipathic helix (41-50) linked to the upstream and the downstream coils by two disulfide bonds (Cys32-Cys47 and Cys48-Cys55). These two coils are in turn linked together by the third disulfide bond (Cys36-Cys54). Such a disulfide bond packing, which is in agreement with the analysis of trypsin digests by ESI-MS, contributes to the highly hydrophobic core. Side chains of Arg45 and Arg50, which belong to the helix, and side chains of Arg37 and Arg53, which belong to the upstream and the downstream coils, are located in two opposite parts of this globular and compact structure. The environment of these positively charged residues, either by hydrophobic clusters at the surface of the cysteine-rich domain or by sequential hydrophobic residues in the unconstrained proline-rich domain, gives rise to the amphipathic character required for antimicrobial peptides. We hypothesize that the antimicrobial activity of penaeidins can be explained by a cooperative effect between the proline-rich and cysteine-rich features simultaneously present in their sequences.     

Expression of band 3 anion exchanger induces chloride current and taurine transport: structure-function analysis.

Most, but not all, cell types release intracellular organic solutes (e.g. taurine) in response to cell swelling to achieve cell volume regulation. Although this efflux is blocked by classical inhibitors of the electroneutral anion exchanger band 3 (AE1), it is thought to involve an anion channel. The role of band 3 in volume-dependent taurine transport was determined by expressing, in Xenopus oocytes, band 3 from erythrocytes which do (trout) or do not (mouse) release taurine when swollen. AE1 of both species elicited anion exchange activity, but only trout band 3 showed chloride channel activity and taurine transport. Chimeras constructed from trout and mouse band 3 allowed the identification of some protein domains critically associated with channel activity and taurine transport. The data provide evidence that swelling-induced taurine movements occur via an anion channel which is dependent on, or controlled by, band 3. They suggest the involvement of proteins of the band 3 (AE) family in cell volume regulation.     

Slight influence of the estrous cycle stage on the mucosal and systemic specific antibody response induced after vaginal and intraperitoneal immunization with protoxin Cry1Ac from Bacillus thuringiensis in mice

Since the immune response appears to be variable according to the hormonal stage of the mammalian female, the aim of this study was to determine whether estrous cycle stage modifies the mucosal and systemic immune responses induced by intraperitoneal and vaginal immunization of mice with protoxin Cry1Ac. We tested the influence of three immunizations on the specific antibody response elicited at estrus and diestrus, that were the same estrous cycle stages at which the antigen was applied. Both intraperitoneal and vaginal immunization of mice with Cry1Ac either at estrus or diestrus induces specific antibody responses at serum, vagina and large intestine. The stage of the estrous cycle have little or non influence in the magnitude of the response induced, since only at serum the IgM was slightly higher at estrus than at diestrus by both routes. At the large intestine only the IgA response elicited via the intraperitoneal route changed, being higher at diestrus, whereas at the vagina IgA response induced did not change significantly due to the cycle stage. Present results suggest that Cry1Ac may be used as an antigen carrier as it can elicit antibody responses at systemic level and at several mucosal sites including the vagina that are not modified significantly throughout the reproductive cycle.     

Étude d'un extrait de Sporothrix schenckii (forme levure). Analyse électrophorétique et immunoélectrophorétique; caracterisation des activités enzymatiques

Résumé Un extrait de S. schenckii a été préparé à partir de levures vivantes provenant d'une culture agitée pendant 3 jours à 35° C et à l'obscurité dans du milieu BHI (brain heart infusion). Il a été obtenu par broyage au broyeur cellulaire MSK et amélioré par une congélation-décongélation. Ses constituants, séparés par électrophorèse, ont été révélés par leur activité enzymatique; 30 bandes ont ainsi pu être caractérisées. Ces activités enzymatiques ont été recherchées au niveau des fractions de l'extrait révélées par un hyperimmunsérum de lapin: 16 sur les 22 précipités sont identifiés par leur pouvoir catalytique. L'ordre d'apparition des premiers anticorps chez le lapin immunisé et leur identification complètent cette étude. Les conditions de culture et de préparation permettant d'améliorer la qualité de l'extrait sont également précisées.

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An extract from living yeast forms of S. schenckii was prepared. The yeasts originated from a shake culture in B.H.I. broth (Difco) incubated for 3 days at 35°C in darkness; they were harvested, washed and disrupted with glass beads in a model MSK Braun mechanical cell homogenizer; a freezing-thawing was added to improve the extract.After electrophoretic separation in agarose gel, the extract's components were characterized by their enzymic activity; with this technique, 30 bands were revealed. These enzymic activities were also investigated on the antigenic fractions of the extract revealed by a rabbit hyperimmunserum: 16 among 22 immunoprecipitates are identified by their catalytic properties. Study of the earliest precipitating antibodies (appearing-order and enzymic caracterization) in rabbits just immunized completes this work. How to ameliorate the quality of the extract by culture and extraction conditions is also specified.

     

Formation of transient oxygen complexes of cytochrome p450 BM3 and nitric oxide synthase under high pressure

The kinetics of formation and transformation of oxygen complexes of two heme-thiolate proteins (the F393H mutant of cytochrome P450 BM3 and the oxygenase domain of endothelial nitric oxide synthase, eNOS) were studied under high pressure. For BM3, oxygen-binding characteristics (rate and activation volume) matched those measured for CO-binding. In contrast, pressure revealed a different CO- and oxygen-binding mechanism for eNOS, suggesting that it is hazardous to take CO-binding as a model for oxygen-binding. With eNOS, a ferric NO complex is formed as an intermediate in the second reaction cycle. Here we report the pressure stability of this compound. Furthermore, in the presence of 4-amino-tetrahydrobiopterin (ABH(4)), an analog to the natural second electron donor tetrahydrobiopterin (BH(4)), biphasic pressure profiles of the oxygen-binding rates were observed, both in the first and the second reaction cycles, indicative of the formation of an additional reaction intermediate. This was confirmed by experiments where ABH(4) was replaced by ABH(2), a cofactor which cannot deliver an electron. Altogether, high pressure appears to be a useful tool to characterize elementary steps in the reaction cycle of heme-thiolate proteins.     

A chlorinated coumarinolignan from the African medicinal plant, Mondia whitei

The unusual chlorinated coumarinolignan, 5-chloropropacin, along with several other known compounds have been isolated from the roots of Mondia whitei. The structure of the chlorinated coumarinolignan was determined by NMR and mass spectroscopic analyses.     

Preliminary Study of the Fungal Ecology at the Haematology and Medical-Oncology Ward in Bamako,Mali

Data on fungal epidemiology in sub-Saharan African countries are scarce. This exploratory study aimed to characterize the fungal flora at the Onco-Haematology ward of the National Teaching Hospital of Point G in Bamako, Mali. A cross-sectional survey was conducted in the dry and in the rainy seasons. Nasal swab and sputum samples were collected from the hospitalized patients while airborne fungal spores were collected using electrostatic dust-fall collectors. Fungi were identified by their morphological characteristics and MALDI-TOF mass spectrometry. Candida albicans was the most frequent yeast species colonizing patients; Aspergillus species were isolated in 86 % of the patients and were the main airborne environmental contaminants. Overall, airborne fungal contamination rates increased from 33.8 % in the dry to 66.2 % in the rainy season (p < 0.001). The most frequent Aspergillus species were Aspergillus niger (36.6 %) and Aspergillus flavus (32.92 %). In contrast, Aspergillus fumigatus (5.43 %) was relatively rare. This high level of fungal exposure raises concern regarding the management of at-risk patients in this Onco-Haematology ward and stresses the need for strengthening the mycological diagnostic capacities to accompany the implementation of adapted fungal infection prevention and management policies.