Macronuclear Molecules Encoding Actins in Spirotrichs

Abstract The nucleotide sequences of 16 newly reported and 8 previously reported actin-encoding macronuclear DNA molecules in spirotrichs have been compared. As described for the eight previously reported molecules, the first 50 bases (noncoding) inside the telomere at both 5′ strands in additional actin molecules are purine-rich. This anomalous base composition might serve as a signal to identify macronuclear molecules in micronuclear DNA during development. The 50-base segment upstream of the ATG in the 5′ leaders of the actin molecules contains extensive, conserved sequence motifs that are possibly promoter elements. The 3′ noncoding trailers contain virtually no conserved sequence motifs. With one exception, the 3′ trailers contain a second stop codon (TGA) 36 bases on average downstream of the primary stop codon. Excluding Moneuplotes crassus, amino acid identities in actin I range from 78 to 100%, with variations distributed nonrandomly along the sequence. Phylogenetic trees based on the actin nucleotide sequences of 22 spirotrichs define the evolutionary relationships of their actin-encoding molecules. The actin phylogeny, while well supported by posterior probabilities, does not always coincide with the phylogeny defined in rDNA analyses or classical taxonomic classifications.     

Dispersal between and colonization of apple byMetaseiulus occidentalis andTyphlodromus pyri (Acarina: Phytoseiidae)

Adult femaleMetaseiulus occidentalis Nesbitt immigrated faster and at higher rates than didTyphlodromus pyri Scheuten to mini-orchards of young apple trees at 0, 10 and 100 m downwind from four apple orchards in the Hood River Valley, Oregon. Colonization of mini-orchards also was faster byM. occidentalis. Rates of emigration were similar between species as measured by movement into trees placed within, but not in contact with source orchard trees. Dispersal and colonization may be influenced by intrinsic physiological and morphological attributes, food habits, and responses to prey and habitat requirements. Implications of dispersal and colonization by these mites to biological control and pesticide resistance management are discussed.     

Evolution of pesticide resistance in apple pests and their natural enemies

Evolution of pesticide resistance in 24 apple pest and natural enemy species was simulated with a computer model. Population ecology parameters were varied among species while physiological, biochemical and genetic assumptions were held constant. There was good agreement between the model's predictions and observed historical patterns of azinphosmethyl resistance among pests and natural enemies. Correspondence between predicted and observed was improved by assuming that natural enemies evolved resistance only after their prey/hosts became resistant, but not by assuming greater initial susceptibility in natural enemies. Results suggest that ecological factors may be important in determining rates of resistance evolution. This is paper no. 2843 of the Hawaii Institute of Tropical Agriculture & Human Resources journal series, and no. 7245 of the Oreg. Agric. Exp. Sta. journal series.     

The effect of host instar on the size and sex ratio of the endoparasitoidDacnusa sibirica

Older instars of the leafminer hostChromatomyia syngenesiae Hardy (Diptera: Agromyzidae) at parasitization resulted in larger female adults of the larval-pupal endoparasitoidDacnusa sibirica Telenga (Hymenoptera: Braconidae). The sex ratio in the parasitoid offspring became increasingly female biased and development period decreased with increasing age of the host at parasitization. Older host instars were therefore considered to produce a fitter parasitoid.     

OX40 and Bcl-xL promote the persistence of CD8 T cells to recall tumor-associated antigen

The molecular signals that allow primed CD8 T cells to persist and be effective are particularly important during cancer growth. With response to tumor-expressed Ag following adoptive T cell transfer, we show that CD8 effector cells deficient in OX40, a TNFR family member, could not mediate short-term tumor suppression. OX40 was required at two critical stages. The first was during CD8 priming in vitro, in which APC-transmitted OX40 signals endowed the ability to survive when adoptively transferred in vivo before tumor Ag encounter. The second was during the in vivo recall response of primed CD8 T cells, the stage in which OX40 contributed to the further survival and accumulation of T cells at the tumor site. The lack of OX40 costimulation was associated with reduced levels of Bcl-x(L), and retroviral expression of Bcl-x(L) in tumor-reactive CD8 T cells conferred greatly enhanced tumor protection following adoptive transfer. These data demonstrate that OX40 and Bcl-x(L) can control survival of primed CD8 T cells and provide new insights into both regulation of CD8 immunity and control of tumors.     

Reactome: a knowledge base of biologic pathways and processes

Reactome http://www.reactome.org, an online curated resource for human pathway data, provides infrastructure for computation across the biologic reaction network. We use Reactome to infer equivalent reactions in multiple nonhuman species, and present data on the reliability of these inferred reactions for the distantly related eukaryote Saccharomyces cerevisiae. Finally, we describe the use of Reactome both as a learning resource and as a computational tool to aid in the interpretation of microarrays and similar large-scale datasets.     

A data-driven demographic model to explore the decline of the Bathurst caribou herd

The Bathurst herd of barren-ground caribou (Rangifer tarandus groenlandicus) in the Canadian central arctic declined from an estimated 203,800 to 16,400 breeding females from 1986 to 2009, with the most rapid decline from 2006 to 2009. A key research and management question was whether the decline was mainly due to decreases in productivity alone or also due to reduced adult female survival. Investigating causes of the decline was hampered by a lack of direct estimates of caribou demographic parameters. We developed a demographic model that could be objectively fitted to field data to explore the mechanisms for the Bathurst decline, with a focus on the recent accelerated decline from 2006 to 2009. Our modeling indicated that the decline was driven by increasing negative trends in adult female and calf survival rates and possibly reduced fecundity The effect of a constant hunter harvest on the declining herd was one potential cause for the recent accelerated decline in adult survival. The demographic model detected negative trends in adult female survival that were not detected using standalone analyses of collar-based survival data. The model allowed rigorous interpretation of trends in productivity by controlling for the simultaneous influence of trends in adult, calf, and yearling survival and adult fecundity on field-based calf–cow ratios. Stochastic simulations suggested that large increases in adult survival and productivity would be needed for the herd to recover. Our methods enable objective modeling of caribou demography that can assist in caribou management based upon all sources of available data. © 2011 The Wildlife Society.     

Oxazolinone derivative of leucine for GC-MS: a sensitive and robust method for stable isotope kinetic studies of lipoproteins

Stable isotope labeled amino acids are commonly used as endogenous tracers to study the metabolism of lipoproteins. The determination of isotopic enrichment of particular amino acids in apolipoproteins is carried out by gas chromatography mass spectrometry (GC-MS). This report describes a robust and sensitive derivative for analysis of d3-leucine by GC-MS and its utility in studying the metabolism of human lipoproteins. The trifluoromethyloxazolinone (oxazolinone) derivative of leucine was formed in a rapid single step procedure using a mixture of trifluoroacetic anhydride (TFAA) and trifluoroacetic acid (TFA). Analysis of the oxazolinone by negative ion chemical ionization GC-MS gave excellent sensitivity and precision, which enabled accurate determination of low levels of isotopic enrichment from small amounts of protein. For example, enrichments between 0.05% and 100% in 100 pg leucine can be measured with a coefficient of variation of <3%. To demonstrate the utility of this procedure, we measured d3-leucine enrichment in apolipoprotein B (apoB) isolated from VLDL and LDL as well as apoA-I isolated from HDL by gel electrophoresis and western blotting. The derivatization procedure gave excellent enrichment data from a single intravenous bolus dose of 5 mg/kg, from which the fractional catabolic rate and production rate of the lipoproteins were calculated. In conclusion, the oxazolinone derivative provides a robust and simple procedure for the sensitive analysis of isotopic enrichment for metabolic studies of human lipoproteins.     

Investigation of the het genes that control heterokaryon incompatibility between members of heterokaryon-compatibility (h-c) groups A and G1 of Aspergillus nidulans

A chromosome assay method was used to determine the heterokaryon compatibility relationships between strains belonging to heterokaryon-compatibility (h-c) groups A and G1 of Aspergillus nidulans. A hybrid strain (RD15) was isolated following protoplast fusion of strains 65-5 (h-cA) and 7-141 (h-cG1). The morphology of RD15 was severely abnormal compared to diploid strains of A. nidulans produced from heterokaryon-compatible haploid parents. Inocula of RD15 were induced to haploidize on medium containing Benlate and a parasexual progeny sample of 291 haploid segregants was obtained. The progeny strains were genotyped for standard markers. Allelic ratios and pairwise marker segregations were determined. Pairs of progeny strains that carried different alleles for the standard markers on each linkage group in turn were tested for compatibility. Strain pairs that possessed different alleles for the markers on linkage groups II, III, V, VI and VII were incompatible indicating the presence of heterokaryon-incompatible (het) genes on these linkage groups. Backcrosses to an h-cGl strain showed that two het genes were located on linkage group III and confirmed a total of six het gene differences between the h-cA and h-cGl strains.