Distribution of actin bundles in Bowman's capsule of rat kidney

In this study we define the distribution of actin bundle arrangement in Bowman's capsule of rat renal corpuscles. Parietal cells of Bowman's capsule were examined by conventional light microscopy, electron microscopy and confocal microscopy. Within each parietal cell individual actin bundles are arranged in a parallel fashion running the length of the cell. Computer reconstructions obtained using confocal microscopy clearly show the lengths of actin bundles to be arranged, on a capsule level, end-to-end, at angles and perpendicular to bundles in adjacent cells. The bundles stain positively for non-muscle myosin and vinculin. The presence and arrangement of actin bundles in parietal cells is consistent with a role in reinforcing capsule structure.     

Quivisianthone, an evodulone limonoid from the Madagascan Meliaceae Quivisia papinae

An investigation of the seeds of the Madagascan Meliaceae Quivisia papinae has yielded quivisianthone, a novel evodulone group limonoid, together with the known azadiradione and two novel derivatives: 6 alpha-hydroxyazadiradione and 7-deacetyl-7-angeloyl-6 alpha-hydroxyazadiradione. Quivisianthone is the first reported evodulone group limonoid possessing both a ring A lactone and an azadiradione-type ring D.     

A Cross-System Comparison of Bacterial and Fungal Biomass in Detritus Pools of Headwater Streams

The absolute amount of microbial biomass and relative contribution of fungi and bacteria are expected to vary among types of organic matter (OM) within a stream and will vary among streams because of differences in organic matter quality and quantity. Common types of benthic detritus [leaves, small wood, and fine benthic organic matter (FBOM)] were sampled in 9 small (1st-3rd order) streams selected to represent a range of important controlling factors such as surrounding vegetation, detritus standing stocks, and water chemistry. Direct counts of bacteria and measurements of ergosterol (a fungal sterol) were used to describe variation in bacterial and fungal biomass. There were significant differences in bacterial abundance among types of organic matter with higher densities per unit mass of organic matter on fine particles relative to either leaves or wood surfaces. In contrast, ergosterol concentrations were significantly greater on leaves and wood, confirming the predominance of fungal biomass in these larger size classes. In general, bacterial abundance per unit organic matter was less variable than fungal biomass, suggesting bacteria will be a more predictable component of stream microbial communities. For 7 of the 9 streams, the standing stock of fine benthic organic matter was large enough that habitat-weighted reach-scale bacterial biomass was equal to or greater than fungal biomass. The quantities of leaves and small wood varied among streams such that the relative contribution of reach-scale fungal biomass ranged from 10% to as much as 90% of microbial biomass. Ergosterol concentrations were positively associated with substrate C:N ratio while bacterial abundance was negatively correlated with C:N. Both these relationships are confounded by particle size, i.e., leaves and wood had higher C:N than fine benthic organic matter. There was a weak positive relationship between bacterial abundance and streamwater soluble reactive phosphorus concentration, but no apparent pattern between either bacteria or fungi and streamwater dissolved inorganic nitrogen. The variation in microbial biomass per unit organic matter and the relative abundance of different types of organic matter contributed equally to driving differences in total microbial biomass at the reach scale.     

Trichothecenes and zearalenone production by fusarium species isolated from Argentinean black beans

Isolates of Fusarium species obtained from freshly harvested bean grains for human consumption collected from different Argentinean regions, were investigated for their ability to biosynthesise trichothecenes and zearalenone either on rice grains or beans. Low incidence of toxigenic fungi was observed. These mycotoxigenic species produced several toxins when grown on rice but none or little amount when cultured on beans. The results of this report suggest that contamination of Argentinean beans with Fusarium mycotoxins will not be common and therefore people would be at low mycotoxicosis risk through consumption of beans.     

An association between the acute phase response and patterns of antigen induced T cell proliferation in juvenile idiopathic arthritis

The aim of this research was to determine whether all memory T cells have the same propensity to migrate to the joint in patients with juvenile idiopathic arthritis. Paired synovial fluid and peripheral blood mononuclear cell proliferative responses to a panel of antigens were measured and the results correlated with a detailed set of laboratory and clinical data from 39 patients with juvenile idiopathic arthritis. Two distinct patterns of proliferative response were found in the majority of patients: a diverse pattern, in which synovial fluid responses were greater than peripheral blood responses for all antigens tested; and a restricted pattern, in which peripheral blood responses to some antigens were more vigorous than those in the synovial fluid compartment. The diverse pattern was generally found in patients with a high acute phase response, whereas patients without elevated acute phase proteins were more likely to demonstrate a restricted pattern. We propose that an association between the synovial fluid T cell repertoire and the acute phase response suggests that proinflammatory cytokines may influence recruitment of memory T cells to an inflammatory site, independent of their antigen specificity. Additionally, increased responses to enteric bacteria and the presence of αEβ7 T cells in synovial fluid may reflect accumulation of gut associated T cells in the synovial compartment, even in the absence of an elevated acute phase response. This is the first report of an association between the acute phase response and the T cell population recruited to an inflammatory site.     

Ectopic expression of a tomato 9-cis-epoxycarotenoid dioxygenase gene causes over-production of abscisic acid

The tomato mutant notabilis has a wilty phenotype as a result of abscisic acid (ABA) deficiency. The wild-type allele of notabilis, LeNCED1, encodes a putative 9-cis-epoxycarotenoid dioxygenase (NCED) with a potential regulatory role in ABA biosynthesis. We have created transgenic tobacco plants in which expression of the LeNCED1 coding region is under tetracycline-inducible control. When leaf explants from these plants were treated with tetracycline, NCED mRNA was induced and bulk leaf ABA content increased by up to 10-fold. Transgenic tomato plants were also produced containing the LeNCED1 coding region under the control of one of two strong constitutive promoters, either the doubly enhanced CaMV 35S promoter or the chimaeric 'Super-Promoter'. Many of these plants were wilty, suggesting co-suppression of endogenous gene activity; however three transformants displayed a common, heritable phenotype that could be due to enhanced ABA biosynthesis, showing increased guttation and seed dormancy. Progeny from two of these transformants were further characterized, and it was shown that they also exhibited reduced stomatal conductance, increased NCED mRNA and elevated seed ABA content. Progeny of one transformant had significantly higher bulk leaf ABA content compared to the wild type. The increased seed dormancy was reversed by addition of the carotenoid biosynthesis inhibitor norflurazon. These data provide strong evidence that NCED is indeed a key regulatory enzyme in ABA biosynthesis in leaves, and demonstrate for the first time that plant ABA content can be increased through manipulating NCED.     

Limonoid derivatives from Astrotrichilia voamatata

The stem bark of Astrotrichilia voamatata (Meliaceae) has yielded the novel limonoids voamatins C and D. These compounds represent a new type of pentanortriterpenoid and are unique in containing a ring A cyclic ether.     

Sesquiterpene lactone and friedelane derivative from drypetes molunduana

A new sesquiterpene lactone, drypemolundein A and a new friedelane derivative, drypemolundein B, along with seven known compounds have been isolated from the whole stems of Drypetes molunduana Pax and Hoffm. Their structures were established on the basis of one- and two-dimensional NMR, homo- and hetero-nuclear spectroscopic evidence.