Distinct modulation of the endothelin-1 pathway in iNOS-/- and eNOS-/- mice

We hypothesized that constitutive endothelial NO synthase (eNOS) and inducible NO synthase (iNOS) have opposite effects on the regulation of endothelin and its receptors. We therefore sought to determine whether deletions of iNOS or eNOS genes in mice modulate pressor responses to endothelin and the expression of ETA and ETB receptors in a similar fashion. Despite unchanged baseline hemodynamic parameters, anesthetized iNOS-/- mice displayed reduced pressor responses to endothelin-1, but not to that of IRL-1620, a selective ETB agonist. Protein content of cardiac ETA receptors was reduced in iNOS-/- mice compared with wild-type mice, but that of ETB receptors was unchanged. Anesthetized eNOS-/- mice presented a hypertensive state, accompanied by an enhanced pressor response to intravenous endothelin-1, whereas the pressor response to IRL-1620 was reduced. Protein levels were also found to be increased for ETA receptors, but reduced for ETB receptors, in cardiac tissues of eNOS-/- mice. In conscious animals, both strains responded equally to the hypotensive effect of an ETA antagonist, ABT-627, whereas orally administered A-192621, an ETB antagonist, increased MAP to a greater extent in eNOS-/- than in wild-type mice. Furthermore, significant levels of immunoreactive endothelin were found in mesenteric arteries in eNOS-/- but not in iNOS-/- or wild-type congeners. Our study shows that repression of iNOS or eNOS has differential effects on endothelin-1 and its receptors. We have also shown that the heart is the main organ in which iNOS or eNOS repression induces important alterations in protein content of endothelin receptors in adult mice.     

Sexual dimorphism in the andromonoecious Euphorbia nicaeensis: effects of gender and inflorescence development

BACKGROUND AND AIMS: In andromonoecious taxa with separate floral types along the inflorescence, architectural or plastic effects can simulate floral sexual dimorphism. Both the primary and secondary sexual characteristics of the cyathia of the protogynous andromonoecious species Euphorbia nicaeensis were analysed according to their sex and arrangement on the inflorescence. METHODS: The production of male and hermaphrodite cyathia at each inflorescence level was surveyed in two natural populations. The longevity, size, pollen production and viability, and nectar secretion of both types of cyathia were checked between inflorescence levels and between sexes at the only level at which they occur together. This sampling method makes it possible to know whether differences between cyathia types are based on sex or are attributable to inflorescence development. KEY RESULTS: Male cyathia were produced predominantly at the first and second inflorescence levels, whereas at levels 3-5, the cyathia were almost exclusively hermaphrodite. Viable pollen production by male cyathia at the second inflorescence level was higher than that of hermaphrodite cyathia at the third level but, when males and hermaphrodites at the same level were compared, their pollen production was similar. Male and hermaphrodite cyathia were similar in size, irrespective of the inflorescence level, although the exclusively hermaphrodite cyathia of the last level were smaller. Both cyathium types produced similar amounts of sugar. However, male cyathia produced nectar during their whole lifespans, whereas hermaphrodites produced it exclusively during their male phase. Moreover, the nectary activity of male cyathia started earlier in the day than that of hermaphrodites. CONCLUSIONS: An apparent floral dimorphism exists in the primary sexual characteristics of Euphorbia nicaeensis because differences in pollen production between cyathium types are due to theirs positions. Similarly, differences affecting most secondary sexual characteristics are only apparent between the two cyathium types. However, E. nicaeensis shows a true but slight floral dimorphism in some of the secondary sex characters related to nectar secretion. The lack of nectar production by the female phase of the hermaphrodite cyathia of E. nicaeensis indicates that this is a deceit-pollinated species.     

Stabilization studies of Fomes sclerodermeus laccases

Stability of laccase isoenzymes from a crude extract obtained from Fomes sclerodermeus grown on wheat bran medium was studied. The variables assessed were temperature, pH and additives. As revealed by PAGE, three bands of laccase, each with different thermal inactivation pattern, were detected in the crude extract: after 6h at 50 degrees C and pH 8, Lc2 was the most resistant, while the Lc1 and Lc3 bands were almost completely inactivated. This pattern of inactivation was observed at all temperatures and pH tested. Laccase activity was more stable in the 5-10 pH range when incubated at 40 and 50 degrees C; at 30 degrees C and 24h the enzyme remained fully active in the 3-11 pH range. The effect of additives (veratryl alcohol, trehalose, glycerol, mannitol, glutaraldehyde, CuSO(4) and 1-HBT) on laccase stability was tested. The stability was enhanced with CuSO(4) (1.25 mM), glycerol (0.2%) and mannitol (1%). The presence of both CuSO(4) and glycerol caused a 3-fold increase in the half-life values.     

Solids and nutrients removals from the liquid fraction of swine slurry through screening and flocculation treatment and influence of these processes on anaerobic biodegradability

A correct separation of solids from liquid fraction is crucial for a successful treatment of swine manure. For this reason an in-depth study of flocculant addition on different livestock wastewaters was carried out. Two flushed swine manure matrices, namely the mixture from nursery and feeder-to-finish pigs and the feeder-to-finish slurry alone, were tested for solids and nutrients removals from liquid fractions. The separation techniques applied were sieving and flocculation. A range of 80-200 ppm of polyacrylamide (PAM) followed by screening was employed in the case of flocculation treatment. The best results were observed when using the highest PAM dose in the matrix correspondent to the mixture of slurries. The removal rates in the liquid fraction were 73% for total solids, 87% for volatile solids, 98% for suspended total and volatile solids, 71% for chemical oxygen demand, 40% for total Kjeldahl nitrogen, and 34% for soluble phosphorus. Once the best PAM dose (120 ppm) was chosen, an anaerobic biodegradability study was performed in order to check the increase of methane production in the separated fractions by using the flocculant and the screen. The assay determined that the solid fractions biodegradability was constant at 79%. Meanwhile for the liquid fractions, an increase of 9% points was achieved with PAM-amendment when compared with 82% reached for the liquid fraction obtained by screening.     

Fungal endophyte infection changes growth attributes in Lolium multiflorum Lam

Abstract Lolium multiflorum is a successful invader of postagricultural succession in the Inland Pampa grasslands in Argentina, becoming a dominant species in the plant community. Individual plants of this annual species are naturally highly infected with fungal endophytes (Neotyphodium sp.) from early successional stages. We assessed the effect of Neotyphodium infection on the biology of L. multiflorum. We evaluated growth attributes between endophyte infected (E+) and uninfected (E–) plants under non‐competitive conditions during the normal growing season. E+ plants produced significantly more vegetative tillers and allocated more biomass to roots and seeds. Although seed germination rates were greater in endophyte free plants, the rate of emergence and the final proportion of emerged seedlings were similar between the biotypes. The greater production of vegetative tillers, and the greater resource allocation to roots and seeds are likely to confer an ecological advantage to E+ plants, thus enabling their dominance over the E– individuals in natural grasslands.     

Leaf phyllotaxis: Does it really affect light capture?

The intriguing mathematical properties of leaf phyllotaxis still attract scientific attention after centuries of research. Phyllotaxis, and in particular the divergence angle between successive leaves, have been frequently interpreted in terms of maximization of light capture, although certain model simulations of light capture by vertical shoots revealed minor effects of phyllotaxis in comparison with the effect of other morphological features of the plant. However, these simulations assumed a number of simplifications, did not take into account diffuse light, and were not based on real plants with their natural range of morphological variation. This study was aimed at filling these gaps by examining the influence on light harvesting of shoot architecture and divergence angle in four species with spiral phyllotaxis (Quercus ilex, Arbutus unedo, Heteromeles arbutifolia and Daphne gnidium) with a realistic 3-D model (Y-plant). A wide range of divergence angles (from 100° to 154°) was observed within each species, with 144° being the most frequent one. These different divergence angles rendered very different vertical projections of the shoot due to contrasting patterns of leaf overlap as seen from above, but they rendered indistinguishable light interception efficiencies (Ea). Setting the leaves with an opposite-decussate phyllotaxis led, however, to a 40–50% decrease of Ea. The interplay of internode length, leaf size and shape, and leaf elevation angle led to significant species differences in Ea. Thus, only particular phyllotaxis (e.g., decussate) might be functionally inefficient under certain combinations of the various morphological variables that influence light capture of a shoot. This revised version was published online in June 2006 with corrections to the Cover Date.     

Visceral Fat Accumulation as a Risk Factor for Prostate Cancer

Objective: No clear association between obesity or body fat distribution and prostate cancer has been shown. We investigated the relation between visceral fat accumulation as measured by computed tomography (CT) and the occurrence of prostate cancer. Research Methods and Procedures: We compared body fat distribution assessed by a direct method (CT) in 63 prostate cancer cases with 63 age‐matched healthy community controls. A CT scan at the level of the fourth lumbar vertebra was performed in all participants. Results: Patients presented a significantly higher mean total abdominal fat area (509.2 ± 226.1 vs. 334.3 ± 132.9 cm², p < 0.001), mostly because of a higher mean visceral fat area (VF; 324.7 ± 145.6 vs. 177.4 ± 88.4 cm², p < 0.001) and a significantly higher mean ratio between visceral and subcutaneous fat areas (V/S ratio; 1.8 ± 0.4 vs. 1.2 ± 0.4, p < 0.001). A significantly higher risk of prostate cancer was found for participants with higher VF (odds ratio = 4.6; 95% confidence interval = 2.6 to 8.2 per SD increase) and V/S ratio (odds ratio = 6.0; 95% confidence interval = 2.3 to 11.0 per SD increase). Discussion: These results suggest a role for visceral obesity, quantified by CT, as a risk factor for prostate cancer. The action of the adipocytokines secreted by visceral fat cells, steroid hormone disturbances, and increased levels of insulin or other hormones noted in visceral obesity may explain this association.