Marker-assisted selection for low phytic acid (lpa1-1) with single nucleotide polymorphism marker and amplified fragment length polymorphisms for background selection in a maize backcross breeding programme

The level of phytic acid is difficult to assess in a maize breeding programme, therefore a co-dominant single nucleotide polymorphism (SNP) marker was used to detect the single recessive low phytic acid (lpa1-1) gene in a BC2F1 population developed from a locally adapted tropical normal inbred line (P 16) and CM 32 (lpa1-1 donor). High-resolution melt analysis of the lpa1-1 SNP marker was able to identify 11 homozygous recessive and 17 heterozygote genotypes for the lpa1-1 mutation. The SNP R ² values for the heterozygotes were higher (90.95?C99.59%) than the lpa1-1 recessives (82.81?C99.58%). The selected BC2F1 lines were fingerprinted with six amplified fragment length polymorphism (AFLP) EcoRI/MseI primer combinations to determine the amount of recurrent parent genome present. The 277 AFLP markers were clearly able to differentiate all the BC2F1 lines from each other and the parental controls with a similarity range from 62.12 to 92.15%. It is expected in the BC2 generation to find 87.5% similarity to the recurrent parent, however in this study higher levels of similarity in 13 BC2F1 lines (six heterozygotes and seven homozygous recessive) with 92.15?C83.33% similarity were observed. The use of marker-assisted selection for foreground and background selection greatly increased the efficiency of detection of the homozygous recessive (99.58%) and heterozygous (99.59%) genotypes as well as improving the recovery of the recurrent parent (92.15%) in the BC2F1 generation of the maize backcross breeding programme.     

Phenolic and flavonoid production and antimicrobial activity of <Emphasis Type="Italic">Gymnosporia buxifolia</Emphasis> (L.) Szyszyl cell cultures

Gymnosporia buxifolia (Celastraceae) is a well-known traditional medicinal plant used to treat various diseases. The aim of the study was to quantify the total phenolic and flavonoid content of cell biomass of G. buxifolia developed in vitro using plant growth regulators (PGRs), phloroglucinol (PG) and an antagonist of cytokinin activity 6-(2-hydroxy-3-methylbenzylamino) purine (PI55). The antibacterial activity of calli was also evaluated. The accumulation of phenolic contents and its antibacterial activity in the cell biomass varied between the treatments as well as the mother plant. Generally, a higher accumulation of phenolic contents translated to improved activity against selected pathogenic bacteria. This was apparent in biomass derived from solid and liquid MS media containing combinations of 5 µM PG, 1.5 µM benzyladenine (BA) or meta-topolin (mT) with or without 1 µM picloram (Pic) and 5 µM PG or PI55, 1 µM BA with or without 0.5 µM Pic respectively. The choice of PGRs, PG and PI55 treatments used during in vitro cell culture systems influenced the therapeutic potential of G. buxifolia. Our results indicate that the cell biomass from suspension and/or solid culture of G. buxifolia could be promising as antibacterial agents with possible applications in the pharmaceutical industry.     

Evidence of viral adaptation to HLA class I-restricted immune pressure in chronic hepatitis C virus infection

Cellular immune responses are an important correlate of hepatitis C virus (HCV) infection outcome. These responses are governed by the host's human leukocyte antigen (HLA) type, and HLA-restricted viral escape mutants are a critical aspect of this host-virus interaction. We examined the driving forces of HCV evolution by characterizing the in vivo selective pressure(s) exerted on single amino acid residues within nonstructural protein 3 (NS3) by the HLA types present in two host populations. Associations between polymorphisms within NS3 and HLA class I alleles were assessed in 118 individuals from Western Australia and Switzerland with chronic hepatitis C infection, of whom 82 (69%) were coinfected with human immunodeficiency virus. The levels and locations of amino acid polymorphisms exhibited within NS3 were remarkably similar between the two cohorts and revealed regions under functional constraint and selective pressures. We identified specific HCV mutations within and flanking published epitopes with the correct HLA restriction and predicted escaped amino acid. Additional HLA-restricted mutations were identified that mark putative epitopes targeted by cell-mediated immune responses. This analysis of host-virus interaction reveals evidence of HCV adaptation to HLA class I-restricted immune pressure and identifies in vivo targets of cellular immune responses at the population level.     

Waterlogging responses of Schoenoplectus scirpoides (Schrad) Browning (Cyperaceae)

Waterlogging responses of an emergent freshwater macrophyte, Schoenoplectus scirpoides, were investigated by carrying out laboratory and field experiments. Soil cores containing uniform plants of S. scirpoides were subjected to drained, 1/3 flooded, alternately flooded and drained at weekly intervals, and continuously flooded treatments for 6 months. Mean soil redox potential of the drained soil was 225 ± 29 mV and was significantly lower in the other treatments. Total dry biomass, above‐ground biomass and number of culms in the flooded/drained and flooded treatments were significantly higher than those in the drained and 1/3 flooded treatments. Below‐ground/above‐ground biomass ratios were highest in the drained treatment and significantly lower in the waterlogged treatments. Plant height and the growth rate of culms were least in the drained treatment and significantly higher in the other treatments. Culm specific gravity decreased significantly with increase in soil moisture. In the field study, soil redox potentials were moderately reduced in the inland and streamside sites, while culm elongation rate was significantly higher by 94% in the streamside compared with the inland site. Optimum growth occurred under flooded conditions, suggesting that the species could flourish with increasing water intrusion in estuarine areas, as predicted by global climate change.     

Cloning, expression, purification, and biological activity of recombinant native and variant human alpha 1-antichymotrypsins

Human alpha 1-antichymotrypsin has been cloned, sequenced and expressed in Escherichia coli and recombinant protein as well as point-specific mutants have been purified and characterized. The corrected gene-deduced amino acid sequence has 45% overall identity with alpha 1-protease inhibitor, which is higher than the 42% previously reported (Chandra, T., Stackhouse, R., Kidd, V. J., Robson, J. H., and Woo, S. L. C. (1983) Biochemistry 22, 5055-5060). Recombinant antichymotrypsin (rACT) is similar to natural antichymotrypsin with respect to the specificity of its interactions with proteases. Its second-order rate constant for association with bovine chymotrypsin is 6-8 x 10(5) M-1 s-1, which is identical to that of the serum-derived inhibitor. Site-specific mutagenesis has been used to produce two variants of rACT in which the P1 position has been changed from leucine to either methionine (L358M-rACT) or arginine (L358R-rACT). L358M-rACT has a specificity of inhibitory activity toward serine proteases closely similar to that of native rACT. By contrast, the specificity of L358R-rACT is quite different from that of native rACT, most notably in efficiently inhibiting trypsin and human thrombin while showing a decreased ability to inhibit chymotrypsin.     

Effects of Community-Based Natural Resource Management on Household Welfare in Namibia

Biodiversity conservation, as an environmental goal, is increasingly recognized to be connected to the socioeconomic well-being of local communities. The development of a widespread community-based natural resource management (CBNRM) program in Namibia makes it an ideal location to analyze the connection between conservation and socioeconomic well-being of local communities. Namibia’s CBNRM program involves the formation of communal conservancies within rural communities and previous studies have found it to be successful on both ecological and economic fronts. In order to broaden the understanding of the program’s impact to include social factors, we have conducted a comparative analysis to determine the effects of this program on household welfare outcomes. Data from two rounds of the Namibia Demographic and Health Surveys (2000 and 2006/07) and quasi-experimental statistical methods were used to evaluate changes in various health, education and wealth outcomes of those living in conservancies, relative to non-conservancy comparison groups. Regression results indicate mixed effects of the conservancy program at the household level. The program had positive effects on some health outcome variables, including bednet ownership, which was twice as likely to increase over time in conservancy compared to non-conservancy households. Program impacts were negative for education outcomes, with the proportion of school attendance of conservancy children being 45% less likely to increase over time than non-conservancy children. Wealth outcome results were inconclusive. Our findings highlight the importance of analyzing community conservation programs at a variety of scales when evaluating overall impact, as community-level benefits may not necessarily extend down to the household level (and vice versa).