Screening of Amazonian plants from the Adolpho Ducke forest reserve, Manaus, state of Amazonas, Brazil, for antimicrobial activity

Tropical forests are species-rich reserves for the discovery and development of antimicrobial drugs. The aim of this work is to investigate the in vitro antimicrobial potential of Amazon plants found within the National Institute on Amazon Research's Adolpho Ducke forest reserve, located in Manaus, state of Amazonas, Brazil. 75 methanol, chloroform and water extracts representing 12 plant species were tested for antimicrobial activity towards strains of Mycobacterium smegmatis, Escherichia coli, Streptococcus sanguis, Streptococcus oralis, Staphylococcus aureus and Candida albicans using the gel-diffusion method. Active extracts were further evaluated to establish minimum inhibitory concentrations (MIC) and antimicrobial profiles using bioautography on normal-phase thin-layer chromatography plates. Diclinanona calycina presented extracts with good antimicrobial activity and S. oralis and M. smegmatis were the most sensitive bacteria. D. calycina and Lacmellea gracilis presented extracts with the lowest MIC (48.8 microg/ml). D. calycina methanol and chloroform leaf extracts presented the best overall antimicrobial activity. All test organisms were sensitive to D. calycina branch chloroform extract in the bioautography assay. This is the first evaluation of the biological activity of these plant species and significant in vitro antimicrobial activity was detected in extracts and components from two species, D. calycina and L. gracilis.     

The maize (Zea mays L.) roothairless 3 gene encodes a putative GPI-anchored, monocot-specific, COBRA-like protein that significantly affects grain yield

The rth3 ( roothairless 3 ) mutant is specifically affected in root hair elongation. We report here the cloning of the rth3 gene via a PCR-based strategy (amplification of insertion mutagenized sites) and demonstrate that it encodes a COBRA-like protein that displays all the structural features of a glycosylphosphatidylinositol anchor. Genes of the COBRA family are involved in various types of cell expansion and cell wall biosynthesis. The rth3 gene belongs to a monocot-specific clade of the COBRA gene family comprising two maize and two rice genes. While the rice ( Oryza sativa ) gene OsBC1L1 appears to be orthologous to rth3 based on sequence similarity (86% identity at the protein level) and maize/rice synteny, the maize ( Zea mays L.) rth3-like gene does not appear to be a functional homolog of rth3 based on their distinct expression profiles. Massively parallel signature sequencing analysis detected rth3 expression in all analyzed tissues, but at relatively low levels, with the most abundant expression in primary roots where the root hair phenotype is manifested. In situ hybridization experiments confine rth3 expression to root hair-forming epidermal cells and lateral root primordia. Remarkably, in replicated field trials involving near-isogenic lines, the rth3 mutant conferred significant losses in grain yield.     

p32 (gC1qBP) is a general protein kinase C (PKC)-binding protein; interaction and cellular localization of P32-PKC complexes in ray hepatocytes.

The aim of this study was to identify cellular proteins that bind protein kinase C (PKC) and may influence its activity and its localization. A 32-kDa PKC-binding protein was purified to homogeneity from the Triton X-100-insoluble fraction obtained from hepatocytes homogenates. The protein was identified by NH(2)-terminal amino acid sequencing as the previously described mature form of p32 (gC1qR). Recombinant p32 was expressed as a glutathione S-transferase fusion protein, affinity-purified, and tested for an in vitro interaction with PKC using an overlay assay approach. All PKC isoforms expressed in rat hepatocytes interacted in vitro with p32, but the binding dependence on PKC activators was different for each one. Whereas PKCdelta only binds to p32 in the presence of PKC activators, PKCzeta and PKCalpha increase their binding when they are in the activated form. Other PKC isoforms such as beta, epsilon, and theta bind equally well to p32 regardless of the presence of PKC activators, and PKCmu binds even better in their absence. It was also found that p32 is not a substrate for any of the PKC isoforms tested, but interestingly, its presence had a stimulatory effect (2-fold for PKCdelta) on PKC activity. We also observed in vivo interaction between PKC and p32 by immunofluorescence and confocal microscopy. A time course of phorbol ester treatment of cultured rat hepatocytes (C9 cells) showed that PKCtheta and p32 are constitutively associated in vivo, whereas PKCdelta activation is required for its association with p32. Our data also showed that phorbol ester treatment induces a transient translocation of p32 from the cytoplasm to the cell nucleus. Together, these findings suggest that p32 may be a regulator of PKC location and function.     

Effect of visible light on superoxide dismutase (SOD) activity in the red alga Gracilariopsis tenuifrons (Gracilariales, Rhodophyta)

Superoxide dismutase (SOD) was studied in the agarophyte Gracilariopsis tenuifrons. Similar SOD activity (130 ± 9U mg^-1) was observed in material from different regions of SouthAmerica, from different phases of the life cycle (gametophytes andtetrasporophytes), and from apical and basal sections of the thallus.In alga grown under a light-dark cycle, SOD activity in samples takenat different times exhibited a diurnal rhythm. The activity measured duringthe day phase was twice as much as during the night phase. This rhythm didnot persist under constant light, indicating light regulation of SOD activity.SOD activity was tested in algae submitted to different light intensities anddifferent wavelengths. It increased with the light intensity. The blue lightwavelength exerted a greater induction of SOD activity than other specificwavelengths.     

Vegetative compatibility and anastomosis formation within and among individual germlings of tropical isolates of arbuscular mycorrhizal fungi (Glomeromycota)

Hyphal anastomoses which play a key role in the formation of interconnected mycorrhizal networks and in genetic exchange among compatible individuals have been studied in a limited number of species and isolates of arbuscular mycorrhizal fungi (AMF), mainly in symbiotic mycelium. In this work, the occurrence and frequency of anastomosis between hyphae of the same and different germlings were assessed in tropical isolates belonging to Acaulospora, Claroideoglomus, Gigaspora, Glomus, Rhizophagus and Scutellospora. Germlings belonging to Acaulospora, Claroideoglomus, Glomus and Rhizophagus formed perfect hyphal fusions, with frequencies ranging from 9.29?±?3.01 to 79.84?±?4.39 % within the same germling and from 14.02?±?7.36 to 91.41?±?3.92 % between different germlings. Rare fusions, occurring within the same hypha, were detected in Gigaspora species, and no anastomoses were observed in Scutellospora species. The consistent detection of nuclei in perfect fusions suggests that nuclear migration is active both within and between germlings. Present data on anastomosis formation, nuclear migration and germling viability in tropical isolates of AMF widen our knowledge on the extensive and consistent occurrence of successful hyphal fusions in this group of beneficial symbionts. The ability to anastomose and establish protoplasm flow, fundamental for the maintenance of physiological and genetic continuity, may produce important fitness consequences for the obligately biotrophic AMF.     

A survey of ontogeny pericarp features as contribution to the infratribal characterization of Myrteae (Myrtaceae)

With the aim of correlating the pericarp structure with current phylogenies of Myrteae, this study describes the ontogeny in five species included in five out of the six South American clades of the tribe. In these taxa, the outer and inner ovarian epidermis gives rise to the exocarp and the endocarp, respectively, both with 1 layer. In the mesocarp, derived from the ovarian mesophyll, secretory cavities are arranged into a circle just below the exocarp and near the endocarp in Campomanesia adamantium; only below the exocarp in Eugenia pitanga and Myrcia multiflora; more internally in Myrciaria cuspidata, and below the exocarp and throughout the mesophyll in Myrceugenia alpigena. The promising traits for phylogenetic studies in the group include: direction of elongation of pericarp layers, regions that develop most in relation to the circle of larger vascular bundles, differentiation of spongy and sclerenchymatous tissues and position of secretory cavities.