Ecological biogeography of Malagasy non‐volant mammals: community structure is correlated with habitat

Aim To examine the relationship between ecoregions, as a proxy for regional climate and habitat type, and mammalian community structure, defined by species composition and richness (e.g. taxonomic structure) and ecological diversity (e.g. ecological structure) of non‐volant species. Location Madagascar. Methods Faunal lists of non‐volant mammal species occurring in 35 communities from five World Wildlife Fund ecoregions were collected from published and unpublished sources. Species were assigned to ecological groups defined by trophic status, locomotor habits, activity cycle and body mass. We used Mantel tests, cluster analysis and principal coordinates analysis to evaluate geographic patterning in taxonomic composition and species richness. We used stepwise multiple discriminant analysis to characterize patterns in the ecological diversity of the mammalian communities from each ecoregion. Communities from transitional habitats (e.g. representing more than one ecoregion) were used to test the predictive power of the analyses. Results Non‐volant mammal communities divided into clusters that correspond to ecoregions. There was a strong distance effect in the taxonomic structure of communities across the island and within both humid and dry forest communities, but this effect was weak within humid forest communities. Mammalian species richness was significantly lower in dry forest than in humid forest communities. The ecological structure of communities was also correlated with ecoregions. Changes in the relative percentages of omnivory, arboreal quadrupedalism, terrestrial/arboreal quadrupedalism and two body mass classes accounted for 98.1% of the variation in ecological structure. Transitional communities were projected in intermediate positions by the discriminant model. Main conclusions Our analysis demonstrates that the broad‐scale habitat and climate variables captured by the ecoregion model have shaped the assembly of non‐volant mammal communities in Madagascar over evolutionary time. The spatial pattern is consistent with ecological sorting of species ranges along environmental gradients. Historical processes, such as recent extinction and migration, may have also affected the structure of mammal communities, although these factors have played a secondary role.     

Inhibitory action of sphingosine, sphinganine and dexamethasone on glucose uptake: studies with hydrogen peroxide and phorbol ester

The mechanism of the inhibitory action of glucocorticoids on glucose uptake is incompletely understood. Treatment with corticosteroids of cells in which glucose uptake is stimulated at insulin postbinding and postreceptor sites may clarify the site of the steroid inhibitory action. Hydrogen peroxide, which has been shown to stimulate the insulin receptor tyrosine kinase, and phorbol myristate acetate (PMA) which stimulates protein kinase C were, therefore, used as stimulators of glucose transport in this study. These studies demonstrate that dexamethasone and the sphingoid bases, sphinganine and sphingosine, inhibit glucose uptake that has been stimulated at either the receptor kinase or protein kinase C level in both 3T3-L1 and 3T3-C2 cells. These data confirm glucocorticoid inhibitory action at a post binding level and support the suggestion that some corticosteroid inhibitory effects may be mediated by an action on sphingolipid metabolism.     

The measurement of changes in pH associated with electrochemically driven respiration in rat liver mitochondria

Using an optically transparant thin layer electrode, it has been possible to measure the pH changes associated with the electrochemical turnover of horse heart cytochrome c in the presence of rat liver mitochondria and oxygen. Direct electrochemistry of cytochrome c at a gold electrode modified with bis(4-pyridyl)bisulfide allowed electron flux (current) to be measured simultaneously with the differential change in absorbance associated with phenol red, a pH-sensitive dye. Although the alkalinization due to the reduction of oxygen to water was readily observed, any initial acidification associated with proton pumping was not detected. It is suggested that at the high ratios of oxidized-to-reduced cytochrome c present during the steady state attained, proton pumping may be absent or more localized.     

Ultraviolet difference spectroscopy of bovine carbonic anhydrase substituted with various divalent metals

The ultraviolet (uv) difference spectra of M(II)-apocarbonic anhydrase at pH 5–9 are reported. For Zn(II) at all pH's and Co(II) at pH ? 7.65 identical protein difference spectra are seen and a positive 300 nm feature is interpreted as consistent with interaction of a metal-bound hydroxyl with a Trp chromophore near the active site. Hg(II), Cu(II), and Cd(II) do not provoke a positive 300 nm band even at alkaline pH (although a Cd(II) spectral band at 300 nm becomes less negative, i.e., more like the holoenzyme with increasing pH) and the 280–292 nm spectral region is generally different from that of Zn(II) and high pH Co(II). A specific orientation of M-OH and, hence, an ordered solvent structure in the enzyme site is implied for enzyme activation. Ni(II) appears to bind to the vacated zinc site slowly, at low pH, in a manner similar to zinc. At higher pH's Ni(II) may be displaced toward a Tyr residue in the active site of apocarbonic anhydrase.     

7-Hydroxydehydroepiandrosterone epimers in the life span.

Evidence has been accumulated that 7-hydroxyepimers of dehydroepiandrosterone (7-OH-DHEA), may act as locally active immunomodulatory and immunoprotective agents, counteracting exaggerated actions of glucocorticoids. Since Skinner et al. (1977) developed the first unspecific RIA, it has been known that 7alpha-OH-DHEA is present in near nanomolar concentration in human blood. No data have been available, however, on its changes during the human life. Using recently developed specific radioimmunoassays for determination of both 7-OH-DHEA epimers, 7alpha- and 7beta-OH-DHEA were measured in sera from 252 males and 172 females, representing age groups from 10 to 91 years (males) and from 10 to 72 years (females). The dependence of 7-OH-DHEA levels on age was evaluated by using polynomial fitting of the 4th or 5th degree. In contrast to men, where a distinct decline with age occurred, two local maxima have been recorded round the age 22 and 53, respectively, in females. The curves of age dependence of 7-OH-DHEA levels in both sexes resembled those of previously determined unconjugated DHEA, but in the latter case the second maximum in women was found about 10 years earlier than 7-OH-DHEA, in a premenopausal period. The levels of both 7-OH-DHEA epimers correlated excellently with each other.     

Gender Ideology and Psychological Reality: An Essay on Cultural Reproduction

Gender Ideology and Psychological Reality: An Essay on Cultural Reproduction. Melford E. Spiro. New Haven, CT: Yale University Press, 1997. 220 pp.     

Salamanca and the city: culture credits, nature credits, and the modern moral economy of indigenous Bolivia

This article draws on fieldwork carried out in a Guaraní-speaking community in the Bolivian Chaco – Isoso – between 1997 and 2000. At the time, some Isoseño people were employed in urban-headquartered projects that revolved around Isoso's environment, culture, or identity and that were funded multilaterally by grants, loans, or other foreign aid. The article describes a set of fantastic discourses circulating in rural Isoso that seem to compare a magical place called Salamanca to the city where some Isoseño people now work. The article argues that these Salamanca discourses are an Isoseño-specific way of talking about a general set of unprecedented processes. It takes up the fact that undertakings of the kind in which the Isoseño are involved create new calibrations among radically different systems for moral/qualitative and material/ quantitative evaluation which can most 'economically' be expressed in terms of credit and debt. Finally, it considers why it is that for all their strange magic, Isoseño 'Salamanca and the city' discourses put an extremely recognizable suite of moral considerations at their centre.     

Casein fermentate of Lactobacillus animalis DPC6134 contains a range of novel propeptide angiotensin-converting enzyme inhibitors

This work evaluated the angiotensin-converting-enzyme (ACE)-inhibitory activities of a bovine sodium caseinate fermentate generated using the proteolytic capabilities of the porcine small intestinal isolate Lactobacillus animalis DPC6134 (NCIMB deposit 41355). The crude 10-kDa L. animalis DPC6134 fermentate exhibited ACE-inhibitory activity of 85.51% (+/-15%) and had a 50% inhibitory concentration (IC50) of 0.8 mg protein/ml compared to captopril, which had an IC50 value of 0.005 mg/ml. Fractionation of the crude L. animalis DPC6134 fermentate by membrane filtration and reversed-phase high-performance liquid chromatography (HPLC) generated three bioactive fractions from a total of 72 fractions. Fractions 10, 19, and 43 displayed ACE-inhibitory activity percentages of 67.53 (+/-15), 83.71 (+/-19), and 42.36 (+/-11), respectively, where ACE inhibition was determined with 80 microl of the fractions with protein concentrations of 0.5 mg/ml. HPLC and mass spectrometry analysis identified 25 distinct peptide sequences derived from alpha-, beta-, and kappa-caseins. In silico predictions, based on the C-terminal tetrapeptide sequences, suggested that peptide NIPPLTQTPVVVPPFIQ, corresponding to beta-casein f(73-89); peptide IGSENSEKTTMP, corresponding to alpha(s1)-casein f(201212); peptide SQSKVLPVPQ, corresponding to beta-casein f(166-175); peptide MPFPKYPVEP, corresponding to beta-casein f(124133); and peptide EPVLGPVRGPFP, corresponding to beta-casein f(210-221), contained ACE-inhibitory activities. These peptides were chosen for chemical synthesis to confirm the ACE-inhibitory activity of the fractions. Chemically synthesized peptides displayed IC50 values in the range of 92 microM to 790 microM. Additionally, a simulated gastrointestinal digestion confirmed that the ACE-inhibitory 10-kDa L. animalis DPC6134 fermentation was resistant to a cocktail of digestive enzymes found in the gastrointestinal tract.     

Construction of p16Slux, a novel vector for improved bioluminescent labeling of gram-negative bacteria

A novel vector has been constructed for the constitutive luminescent tagging of gram-negative bacteria by site-specific integration into the 16S locus of the bacterial chromosome. A number of gram-negative pathogens were successfully tagged using this vector, and the system was validated during murine infections of living animals.