Mangroves found in Dominica (West Indies)

Mangroves has been described for the whole Caribbean are in their different habitats. The island of Dominica (West Indies) has always been excluded from the distribution area due to supposed inadequated conditions for mangrove growth. However, there are small areas with proper edaphic conditions for mangal in which black mangrove (Avicennia germinans L.) and white mangrove (Laguncularia racemosa L.) has been found. Even the occurrence of an additional Avicennia species is under discussion.     

Culture analysis and external interaction models of mycelial growth

To investigate morphogenesis and in particular circularization mechanisms in young mycelia, we observe cultures of the zygomyceteMucor spinosus and develop discrete models of two-dimensional filamental branching growth. The models are based on the hypothesis that the fungus secretes a regulatory substance that diffuses into the surrounding medium and is detected by the growing hyphae. We also present a simple Markovian growth model without such a feedback, but yielding to analytical computations.     

The loss of culturability by Escherichia coli cells in seawater depends on availability of phosphate ions and phosphate transport systems

Using strains with or without the PhoE porin or different components of the phosphate regulon, we determined that maintenance of the culturability of Escherichia coli in seawater depended significantly on the presence of structures allowing access of phosphate ions to the periplasm, then to the cytoplasm of cells. Cells totally deprived of the two main phosphate transport systems (Pit, Pst) exhibited the highest loss of culturability. Most of this effect resulted from the loss of the high-affinity Pst system, and more specifically that of the periplasmic phosphate-binding protein PhoS. Survival was enhanced in seawater supplemented with phosphate (0.5 mm), whether or not these structures were present. From an ecological point of view, it is assumed that the presence of phosphate ions, even at low concentrations, can influence the behavior of E. coli cells in seawater. Offprint requests to: M.J. Gauthier     

Darwin's ‘mystery of mysteries’: the role of sexual selection in plant speciation

Sexual selection is considered one of the key processes that contribute to the emergence of new species. While the connection between sexual selection and speciation has been supported by comparative studies, the mechanisms that mediate this connection remain unresolved, especially in plants. Similarly, it is not clear how speciation processes within plant populations translate into large-scale speciation dynamics. Here, we review the mechanisms through which sexual selection, pollination, and mate choice unfold and interact, and how they may ultimately produce reproductive isolation in plants. We also overview reproductive strategies that might influence sexual selection in plants and illustrate how functional traits might connect speciation at the population level (population differentiation, evolution of reproductive barriers; i.e. microevolution) with evolution above the species level (macroevolution). We also identify outstanding questions in the field, and suitable data and tools for their resolution. Altogether, this effort motivates further research focused on plants, which might potentially broaden our general understanding of speciation by sexual selection, a major concept in evolutionary biology.     

Evaluation of Probiotic Properties of Novel Brazilian Lactiplantibacillus plantarum Strains

Probiotics and Antimicrobial Proteins - Beneficial effects of Lactiplantibacillus plantarum strains have been widely reported. Knowing that the effects of probiotic bacteria are strain-dependent,...     

Urinary excretion of PGE2 and renal function in acute myocardial infarction

In 17 hospitalized patients affected by acute myocardial infarction (AMI) PGE2 urinary excretion, renal function and, furthermore, cortisol urinary excretion were tested during a 21 days trial. In 12 patients all the parameters under consideration underwent a similar trend: PGE2 urinary excretion exactly like glomerular filtration rate, Na+ excretion and diuresis tended to be reduced during the first 5 days and they rapidly recovered the normality after this period. Cortisol urinary excretion displayed a characteristic pattern: i.e. the highest values were observed in the first days, followed by a progressive decrease towards physiological levels since the 4th day. Different findings were obtained in 5 cases treated with an antiinflammatory drug (Indoprophen i.m. 200 mg x2 die). In fact the low levels of urinary PGE2 on the first days did not display any increasing and GFR, urinary flow, and Na+ tubular balance underwent irregular and not significant variations. These data suggest that an impaired Prostaglandin synthesis may be related to a compromised renal function often occurring in AMI.     

The larval midgut of the cassava hornworm (Erinnyis ello)

Summary Columnar cells of the larval midgut of the cassava hornworm, Erinnyis ello, display microvilli with vesicles pinching off from their tips (anterior and middle midgut) or with a large number of double membrane spheres budding along their length (posterior midgut). Basal infoldings in columnar cells occur in a parallel array with many openings to the underlying space (posterior midgut) or are less organized with few openings (anterior and middle midgut). Goblet cells have a cavity, which is formed by invagination of the apical membrane and which occupies most of the cell (anterior and middle midgut) or only its upper part (posterior midgut). The infolded apical membrane shows modified microvilli, which sometimes (posterior midgut) or always (anterior and middle midgut) contain mitochondria. The cytoplasmic side of the membrane of the microvilli that contain mitochondria are studded with small particles. The results suggest that the anterior and middle region of the midgut absorbs water, whereas the posterior region secretes it. This results in a countercurrent flux of fluid, which is responsible for the enzyme recovery from undigested food before it is expelled. Intermediary and final digestion of food probably occur in the columnar cells under the action of plasma membrane-bound and glycocalix-associated enzymes.     

Demonstration of the correlation of the degree of synthesis and 4-aminobutyric acid levels in the central nervous system; effect of repeated convulsive seizures

GABA turnover rates have been determined in 15 brain areas in five inbred strains of Mice or sublines (DBA/2J, C57/6J, Swiss Rb1, Swiss Rb2, Swiss Rb3). GABA turnover rates and levels are correlated (2 P less than 0.05). After repeated seizures (twice a day for 15 days), induced by an acoustic stimulus in Swiss Rb1 Mice selected for audiogenic seizures, this correlation is no longer observed.     

Vegetative multiplication of sugarbeet through in vitro culture of inflorescence pieces

In vitro vegetative multiplication of sugarbeet was obtained by culturing of inflorescence explants. Subapical segments or 5-mm-long tips from nine varieties developed axillary shoots (up to 50 per tip) on a medium containing indolebutyric acid (IBA) and benzylaminopurine (BAP). Zeatin was ineffective as cytokinin. Gibberellic acid (GA₃) enhanced the process. Such vegetative shoots were subsequently isolated and were each allowed to develop up to 20 supplementary axillary shoots on a multiplication medium containing IBA, BAP, and naphthaleneacetic acid (NAA). Rooting of shoots was obtained in the absence of growth regulators and plants were established.