Interactions between janus and bcd cortical pattern mutants in Tetrahymena thermophila

Summary An analysis of bcd, janA; bcd, janB; and bcd, janC double-mutant phenotypes in Tetrahymena thermophila has allowed us to examine patterning processes affected by two different classes of mutations. bcd brings about a broadening of the oral and contractile vacuole pore domains in the ciliate cortex, while the janus mutations generate a mirror-image duplication of the ventral cortical pattern. We observed both bcd and janus characteristics expressed in the double mutants, as well as features unique to the double-mutant. Temperature-shift experiments employing the temperature-sensitive janB mutation in a double-mutant (bcd, janB) combination allowed us to observe the changes in pattern as a mirror-image geometry was brought into expression and subsequently removed within the bcd, janB double homozygote. These experiments suggest that there are multiple pattern-mechanisms at work with differing kinetics of expression in the ciliate cortex. We discuss how the bcd mutation could influance expression of the janus mutations in light of a model previously proposed to account for the janus phenotype.     

Categorical Default Uncertainty Factors-Interspecies Variation and Adequacy of Database

The potential application of categorical (i.e., species, pathway, or group specific) defaults for several components of uncertainty relevant to development of tolerable or reference concentrations/doses is considered-namely, interspecies variation and adequacy of database. For the former, the adequacy of allometric scaling by body surface area as a species-specific default for oral tolerable or reference doses is considered. For the latter, the extent to which data from analyses of subchronic:chronic effect levels, LOAELs/NOAELs, and critical effect levels for complete versus incomplete datasets informs selection of defaults is examined. The relative role of categorical defaults for these aspects is considered in the context of the continuum of increasingly data-informed approaches to characterization of uncertainty and variability that range from default (“presumed protective”) to “biologically based predictive”.     

Nonpeptide HIV protease inhibitors designed to replace a bound water

Cyclic nonpeptide molecules were designed and synthesized with the goal of displacing the conserved flap-associated water of HIV-1 protease. Several such molecules were competitive inhibitors with micromolar inhibition constants, and their structure-activity relationships were consistent with the design hypothesis.     

Sequencing improves our ability to study threatened migratory species: Genetic population assignment in California's Central Valley Chinook salmon

Effective conservation and management of migratory species requires accurate identification of unique populations, even as they mix along their migratory corridors. While telemetry has historically been used to study migratory animal movement and habitat use patterns, genomic tools are emerging as a superior alternative in many ways, allowing large‐scale application at reduced costs. Here, we demonstrate the usefulness of genomic resources for identifying single‐nucleotide polymorphisms (SNPs) that allow fast and accurate identification of the imperiled Chinook salmon in the Great Central Valley of California. We show that 80 well‐chosen loci, drawn from a pool of over 11,500 SNPs developed from restriction site‐associated DNA sequencing, can accurately identify Chinook salmon runs and select populations within run. No other SNP panel for Central Valley Chinook salmon has been able to achieve the high accuracy of assignment we show here. This panel will greatly improve our ability to study and manage this ecologically, economically, and socially important species and demonstrates the great utility of using genomics to study migratory species.     

Isolation of Legume Glycosyltransferases and Active Site Mapping of the <Emphasis Type="Italic">Phaseolus lunatus</Emphasis> Zeatin O-glucosyltransferase ZOG1

O-Glycosides of the cytokinin zeatin are found in many plant tissues. They provide protection against degradative enzymes and may serve as cytokinin reserves. Two zeatin glycosyltransferase (GT) genes, an O-glucosyltransferase (ZOG1) from Phaseolus lunatus and an O-xylosyltransferase (ZOX1) from P. vulgaris, were previously isolated. Five novel bean and soybean GT genes with high sequence identity to ZOG1 were isolated, sequenced, and expressed, along with two such genes from rice and one from tomato. None of the recombinant proteins showed GT activity with zeatin. By comparing the ZOG1 sequence to the 3D model of Medicago truncatula UGT71G1, four regions possibly important to zeatin binding were identified, and mutation studies identified one amino acid within each region (R59, D87, L127, and F149) whose mutation strongly impaired enzyme activity. The new bean and soybean GTs differ from ZOG1 in one (PlGT2 and GmGT2) to three (GmGT1) of these residues. Mutation of one such GT (PlGT2) to render it identical to ZOG1 at the four implicated residues conferred low enzyme activity, providing further support for the importance of these amino acids in recognizing zeatin as substrate. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.