Coumarins from Cedrelopsis grevei (Ptaeroxylaceae)

The stem bark of Cedrelopsis grevei Baill. has yielded the first reported examples of 5-prenylated coumarins, cedrecoumarin A and B as well as the known coumarins, cedrelopsin, scoparone, O-methylcedrelopsin and norbraylin, and the known chromones ptaeroglycol and ptaeroxylinol.     

Rapid assay for γ-carboxyglutamic acid in urine and bone by precolumn derivatization and reversed-phase liquid chromatography

A reversed-phase high-performance liquid chromatographic assay for the analysis of γ-carboxyglutamic acid (Gla) in urine and bone protein hydrolyzates is described. The method employs precolumn derivatization with o-phthalaldehyde and mercaptoethanol. Gla was quantified by reference to an internal standard (β-carboxyaspartic acid). The “within-run” coefficient of variation of the assay for Gla in urine was between 2.1 and 3.4%, and that for bone protein hydrolyzates was 3.2%. The “between-run” coefficient of variation ranged from 4.1 to 5.5%. There was good agreement between the measurement of urinary Gla by high-performance liquid chromatography and amino acid analyzer. Free Gla could not be detected in serum.     

Proliferative capacity of epitope-specific CD8 T-cell responses is inversely related to viral load in chronic human immunodeficiency virus type 1 infection

The relationship between the function of human immunodeficiency virus (HIV)-specific CD8 T-cell responses and viral load has not been defined. In this study, we used a panel of major histocompatibility complex class I tetramers to examine responses to frequently targeted CD8 T-cell epitopes in a large cohort of antiretroviral-therapy-na?ve HIV type 1 clade C virus-infected persons in KwaZulu Natal, South Africa. In terms of effector functions of proliferation, cytokine production, and degranulation, only proliferation showed a significant correlation with viral load. This robust inverse relationship provides an important functional correlate of viral control relevant to both vaccine design and evaluation.     

The terrestrial arthropods of Mauritius: a neglected conservation target

Entomology in Mauritius has historically been linked with the agricultural and medical fields but concern should now be directed towards the conservation of native forest insects given that they are key components of the local ecosystem. Despite its young age, small size and remoteness, the island has a well-developed native insect fauna with a high proportion of endemic species. A majority of the insect orders are represented on the island. We document the current state of knowledge for Mauritian arthropods, with particular focus on the Coleoptera. This is the most diverse order locally with 1,032 species. In addition, it is the best catalogued historically, providing a framework for future conservation studies to evaluate the current status of this group. We explore the current threats facing the native insect fauna and highlight the needs for concern on this vital component of local biodiversity. We recognize that the initial step for conserving the native insects will depend largely on the establishment of a local taxonomic knowledge base with international expert input.     

High frequency transformation of Bordetella by electroporation

Abstract The bioenergetic properties of a facultatively anaerobic alkalophile which contained no cytochrome component in the respiratory chain were studied. It is suggested that the bacterium is able to acidify the cytoplasm even in the absence of Na⁺ due to a Donnan potential, which results in the dissipation of the membrane potential.     

Elucidating the role of nutrients in C-phycocyanin production by the halophilic cyanobacterium <Emphasis Type="Italic">Euhalothece</Emphasis> sp.

In this study, a novel halophilic cyanobacterium was isolated and identified as Euhalothece sp. KZN. This fast-growing strain had the ability to synthesise high yields (12 mg g^?1) of C-phycocyanin (C-PC), a highly fluorescent blue light-harvesting pigment with numerous potential uses in the biotechnology and commercial sectors. This study elucidated the individual and interactive role of different nutrients in BG11 growth medium for enhancing C-PC production in Euhalothece sp. KZN. Nine components of BG11 medium were screened for their effects via fractional factorial design (FFD). The results revealed a significant influence of nutrients, viz. MgSO₄, NaNO₃ and minor nutrients (citric acid, EDTA-iron citrate, CaCl₂ and Na₂CO₃) on C-PC yield. These three components were further explored for their optimum concentration for enhancing C-PC production using a central composite design. The optimum values for these essential nutrients were found to be as follows: 0.10 g L^?1 of MgSO₄, 1.67 g L^?1 of NaNO₃ and 10 mL L^?1 of minor nutrients which resulted in a 280% increase in C-PC yield with predicted and actual values of 43.97 and 45 mg g^?1, respectively. Euhalothece sp. KZN is a strong potential candidate for C-PC production and can be further exploited to produce this industrially valuable compound.     

CD8+ T-cell responses to different HIV proteins have discordant associations with viral load

Selection of T-cell vaccine antigens for chronic persistent viral infections has been largely empirical. To define the relationship, at the population level, between the specificity of the cellular immune response and viral control for a relevant human pathogen, we performed a comprehensive analysis of the 160 dominant CD8(+) T-cell responses in 578 untreated HIV-infected individuals from KwaZulu-Natal, South Africa. Of the HIV proteins targeted, only Gag-specific responses were associated with lowering viremia. Env-specific and Accessory/Regulatory protein-specific responses were associated with higher viremia. Increasing breadth of Gag-specific responses was associated with decreasing viremia and increasing Env breadth with increasing viremia. Association of the specific CD8(+) T-cell response with low viremia was independent of HLA type and unrelated to epitope sequence conservation. These population-based data, suggesting the existence of both effective immune responses and responses lacking demonstrable biological impact in chronic HIV infection, are of relevance to HIV vaccine design and evaluation.     

HLA class I-driven evolution of human immunodeficiency virus type 1 subtype c proteome: immune escape and viral load

Human immunodeficiency virus type 1 (HIV-1) mutations that confer escape from cytotoxic T-lymphocyte (CTL) recognition can sometimes result in lower viral fitness. These mutations can then revert upon transmission to a new host in the absence of CTL-mediated immune selection pressure restricted by the HLA alleles of the prior host. To identify these potentially critical recognition points on the virus, we assessed HLA-driven viral evolution using three phylogenetic correction methods across full HIV-1 subtype C proteomes from a cohort of 261 South Africans and identified amino acids conferring either susceptibility or resistance to CTLs. A total of 558 CTL-susceptible and -resistant HLA-amino acid associations were identified and organized into 310 immunological sets (groups of individual associations related to a single HLA/epitope combination). Mutations away from seven susceptible residues, including four in Gag, were associated with lower plasma viral-RNA loads (q < 0.2 [where q is the expected false-discovery rate]) in individuals with the corresponding HLA alleles. The ratio of susceptible to resistant residues among those without the corresponding HLA alleles varied in the order Vpr > Gag > Rev > Pol > Nef > Vif > Tat > Env > Vpu (Fisher's exact test; P < or = 0.0009 for each comparison), suggesting the same ranking of fitness costs by genes associated with CTL escape. Significantly more HLA-B (chi(2); P = 3.59 x 10(-5)) and HLA-C (chi(2); P = 4.71 x 10(-6)) alleles were associated with amino acid changes than HLA-A, highlighting their importance in driving viral evolution. In conclusion, specific HIV-1 residues (enriched in Vpr, Gag, and Rev) and HLA alleles (particularly B and C) confer susceptibility to the CTL response and are likely to be important in the development of vaccines targeted to decrease the viral load.