Heavy metal distribution in superficial sedimenta ta Saco, Gulf of Cariaco, Sucre, Venezuela

The Gulf of Cariaco is a marine ecosystem with high primary productivity, which gives it an ecological and socioeconomic importance. Nevertheless, anthropogenic activities around the Gulf produce wastes that are deposited directly or by runoff into the sediments, and consequently, increases concentrations of metals in this ecosystem. The objective of this study was to determine the distribution of cadmium, copper, lead, manganese, nickel and zinc in geochemical fractions of surface sediments, using modified BCR sequential extraction procedure. The concentrations were measured using flame atomic absorption spectroscopy. In addition, the contents of soluble and exchangeable metals associated to carbonate fractions, determined by BCR, were compared with those determined by the method of Campanella. Samples were collected in 12 stations during June 2007. The applied methodologies were evaluated with a certified reference material of marine sediments (HISS-1) and the results indicated that these methods provide adequate accuracy and precision for the extraction of metals. The total metal concentrations (microg g(-1)) were, Cd: < limit of detection (LD)-5.0; Pb: 1.79-60.41; Cu: no detected (ND)-42.18; Zn: 25.13-104.57; Mn: 66.31-80.29 and Ni: 3.29-24.58. Cd, Cu, Ni and Pb at several stations, exceeded the Canadian Sediment Quality Guidelines of the Lowest Effect Levels (LEL). Cadmium was identified as being the most mobile of the elements, having the highest concentrations in soluble and exchangeable cations and carbonates. However, Pb, Cu, Mn and Zn levels were found highly associated to organic matter and sulfide fractions. The methods did not show significant statistical differences for the extraction of soluble and exchangeable cations and the metals associated to carbonate fraction. There are several significant correlations between heavy metals, which suggest their common origin.     

Above- and below-ground vertebrate herbivory may each favour a different subordinate species in an aquatic plant community

At least two distinct trade-offs are thought to facilitate higher diversity in productive plant communities under herbivory. Higher investment in defence and enhanced colonization potential may both correlate with decreased competitive ability in plants. Herbivory may thus promote coexistence of plant species exhibiting divergent life history strategies. How different seasonally tied herbivore assemblages simultaneously affect plant community composition and diversity is, however, largely unknown. Two contrasting types of herbivory can be distinguished in the aquatic vegetation of the shallow lake Lauwersmeer. In summer, predominantly above-ground tissues are eaten, whereas in winter, waterfowl forage on below-ground plant propagules. In a 4-year exclosure study we experimentally separated above-ground herbivory by waterfowl and large fish in summer from below-ground herbivory by Bewick’s swans in winter. We measured the individual and combined effects of both herbivory periods on the composition of the three-species aquatic plant community. Herbivory effect sizes varied considerably from year to year. In 2 years herbivore exclusion in summer reinforced dominance of Potamogeton pectinatus with a concomitant decrease in Potamogeton pusillus, whereas no strong, unequivocal effect was observed in the other 2 years. Winter exclusion, on the other hand, had a negative effect on Zannichellia palustris, but the effect size differed considerably between years. We suggest that the colonization ability of Z. palustris may have enabled this species to be more abundant after reduction of P. pectinatus tuber densities by swans. Evenness decreased due to herbivore exclusion in summer. We conclude that seasonally tied above- and below-ground herbivory may each stimulate different components of a macrophyte community as they each favoured a different subordinate plant species.     

An intersubspecific genetic map of<Emphasis Type="Italic"> Lens</Emphasis>

A Lens map was developed based on the segregational analysis of five kinds of molecular and morphological genetic markers in 113 F₂ plants obtained from a single hybrid of Lens culinaris ssp. culinaris × L. c. ssp. orientalis. A total of 200 markers were used on the F₂ population, including 71 RAPDs, 39 ISSRs, 83 AFLPs, two SSRs and five morphological loci. The AFLP technique generated more polymorphic markers than any of the others, although AFLP markers also showed the highest proportion (29.1%) of distorted segregation. At a LOD score of 3.0, 161 markers were grouped into ten linkage groups covering 2,172.4 cM, with an average distance between markers of 15.87 cM. There were six large groups with 12 or more markers each, and four small groups with two or three markers each. Thirty-nine markers were unlinked. A tendency for markers to cluster in the central regions of large linkage groups was observed. Likewise, clusters of AFLP, ISSR or RAPD markers were also observed in some linkage groups, although RAPD markers were more evenly spaced along the linkage groups. In addition, two SSR, three RAPD and one ISSR markers segregated as codominant. ISSR markers are valuable tools for Lens genetic mapping and they have a high potential in the generation of saturated Lens maps.Communicated by H.C. Becker     

Interferon-gamma increases monocyte HLA-DR expression without effects on glucose and fat metabolism in postoperative patients.

Tissue injury is associated with decreased cellular immunity and enhanced metabolism. Immunodepression is thought to be counteracted by interferon (IFN)-gamma, which increases human leukocyte antigen (HLA)-DR expression. Hypermetabolism could be enhanced by IFN-gamma because cytokines induce a hypermetabolic response to stress. In healthy humans, IFN-gamma enhanced HLA-DR expression without effects on glucose and fat metabolism. In the present study, we evaluated whether IFN-gamma lacks potential harmful side effects on metabolic and endocrine pathways while maintaining its beneficial effects on the immune system under conditions in which the inflammatory response system is activated. In 13 patients scheduled for major surgery, we studied HLA-DR expression on peripheral blood monocytes before surgery and postoperatively randomized the patients into an intervention and a placebo group. Subsequently, we evaluated the effects of a single dose of IFN-gamma vs. saline on short-term monocyte activation, glucose and lipid metabolism, and glucose and lipid regulatory hormones. HLA-DR expression on monocytes was restored from postoperative levels of 54% (42-60%; median and interquartiles) to 92% (91-96%) 24 h after IFN-gamma administration but stayed low in the placebo-treated patients. IFN-gamma did not affect glucose metabolism (plasma glucose, rate of appearance and disappearance of glucose) and lipid metabolism (plasma glycerol, plasma free fatty acids, and rates of appearance and disappearance of glycerol). IFN-gamma had no effect on plasma cortisol, adrenocorticotropic hormone, growth hormone, insulin, C-peptide, glucagon, epinephrine, and norepinephrine concentrations. We conclude that IFN-gamma exerts a favorable effect on cell-mediated immunity in patients after major surgery without effects on glucose and lipid metabolism.     

Plant size,geitonogamy and seed set in Ipomopsis aggregata

Summary We used powdered fluorescent dyes to estimate receipt of self vs. outcross pollen in the self-incompatible species Ipomopsis aggregata (Polemoniaceae). Flowers on small and large plants received equal amounts of outcross pollen, whereas flowers on large plants received more self pollen, so the proportion of self pollen delivered through geitonogamy increased with plant size. In natural populations emasculation of all flowers on a plant raised average seed set per flower from 5.19 to 6.99 and also raised fruit set, though not significantly. From these results one expects a negative correlation between plant size and seeds per flower. The opposite trend was observed in a sample of plants in the field, suggesting that deleterious effects of geitonogamy on female fecundity in large plants can be overruled by other factors such as size-related fruit or seed abortion. Results are discussed in relation to the evolution of gynodioecy.     

Effect of exogenous hormones on leaf yellowing in cut flowering branches of Alstroemeria pelegrina L.

Inclusion of IAA in the vase water had little effect on leaf yellowing in cut flowering branches of Alstroemeria pelegrina L. while kinetin delayed leaf yellowing at 10^-4M (continuous treatment). Chlorophyll was effectively retained by 10^-7M gibberellic acid (GA) in the vase water or by a 20h pulse at 5°C with 10^-5/10^-4M GA. After 16h of ¹⁴C-GA, uptake at 20°C relatively high levels of ¹⁴C were found in leaves and low levels in stems and flowers. After this treatment about half of the ¹⁴C-GA, in leaves was metabolized into unknown compounds. Corrigendum. Owing to an error in the proofreading process, the article was published incorrectly. The article as it should have been published is presented here.     

HPLC analysis of free amino acids and amino acids of total proteins in cultured cells: an application to the study of rat Sertoli cell protein metabolism.

A simple, rapid and, sensitive HPLC method, coupled with fluorometric detection, has been worked out and employed to determine the intracellular free amino acid concentrations and the amino acid composition of total proteins in rat Sertoli cell primary culture. Sertoli cells were isolated enzymatically from testes of 20- and 28-day-old rats and cultured at 32 degrees C in Eagle's minimum essential medium. On the second day of culture, cell monolayers were quickly rinsed with ice-cold saline, immediately frozen in liquid nitrogen, accurately harvested, and homogenized in 10% trichloroacetic acid. Tissue free amino acids were determined in the acidic soluble fraction following neutralization, while the precipitate was hydrolyzed for the evaluation of the fractional content of amino acids into total proteins. Amino acid samples were derivatized with o-phthaldialdehyde/3-mercaptopropionic acid and resolved by a linear one-step acetonitrile gradient in 12.5 mM sodium phosphate buffer, pH 7.2, employing a 5-microns particle size reversed-phase column. Fluorescence was monitored with excitation at 330 nm and emission at 450 nm. Under these conditions all major physiological amino acids could be satisfactory separated, identified, and subsequently quantified with the aid of standards. The run time was about 50 min; the linearity was excellent over a large range of concentrations (1-800 pmol) and the lower limit of sensitivity appeared to be 0.5 pmol. This method permits us to demonstrate age-dependent modifications in the intracellular amino acid pool and to adequately evaluate the process of protein synthesis in cultured Sertoli cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

ETUDE DES COMPLEXES DE PIGMENTS CHLOROPHYLLIENS D'EUGLENA GRACILIS AU COURS DE LA CROISSANCE ET A L'ETAT ADULTE

Une tude des cellules d'Euglnes et de leurs extraits prparsavec les ultra-sons, chauffs ou non chauffs (quelques heures 35), montre que:

1. le chauffage ne dtruit pas la chlorophylle de faon notable;
2. en prsence d'alcool, un agrgat de chlorophylle ayant unebanded'absorption 740–750 mµ apparait dans lesextraitsd'Euglnes ges de plus de 11 jours;
3. les jeunesEuglnes et les Euglnes ges et chauffes ne peuventformerl'agrgat absorbant aux grandes longueurs d'ondes;
4. deux outrois complexes chlorophylliens diffrents sont impliqusdansla formation des agrgats qui absorbent 740 mµ.

¹ Travail rendu possible par l'attribution d'une bourse d'tudede l'universit de Montral l'un des auteurs (DE K.) et l'octroid'une subvention de recherches (A-1196) du Conseil Nationaldes Recherches du Canada.     

Endomycopsis montevidensis n. sp.

A new species of the genusEndomycopsis is proposed. It was isolated from wast water, at Montevideo-Uruguay.By its morphological and biochemical proprieties it differs from allEndomycopsis previously described.Este trabajo fue desarrollado en el Laboratorio de Micologia de la Facultad de Quimica de Montevideo, Uruguay y en uso de una beca de la Universidad Federal de Pernambuco para perfeccio bamiento en el estudo de las levaduras.