Evolutionary fate of an unstable human minisatellite deduced from sperm-mutation spectra of individual alleles

Although mutation processes at some human minisatellites have been extensively characterized, the evolutionary fate of these unstable loci is unknown. Minisatellite instability is largely germline specific, with mutation rates up to several percent and with expansion events predominating over contractions. Using allele-specific small-pool polymerase chain reaction, we have determined sperm-mutation spectra of individual alleles of the highly unstable human minisatellite CEB1 (i.e., D2S90). We show that, as allele size increases, the proportion of contractions rises from <5% to 50%, with the average size of deletion increasing and eventually exceeding the average size of expansion. The expected net effect of these trends after many generations is an equilibrium distribution of allele sizes, and allele-frequency data suggest that this equilibrium state has been reached in some contemporary human populations.     

Birds of a feather clock together--sometimes: social synchronization of circadian rhythms

Biological systems use internal circadian clocks to efficiently organize physiological and behavioral activity within the 24-hour time domain. In the absence of time cues, circadian periods vary slightly from 24 hours, but in nature, ambient light serves as the most salient synchronizer for these rhythms, fine-tuning them to exactly 24 hours each day. For some species, social cues can serve to synchronize circadian rhythms in the absence of other time cues or to amplify ambiguous light cues. This has been demonstrated to various degrees in fruit flies, degus, birds, fish, bats, beavers and humans; however, studies in rats and hamsters have shown that social cues are less salient time cues for these species. Social influences on circadian timing might function to tightly organize the social group, thereby decreasing the chances of predation and increasing the likelihood of mating.     

Microbial Characterization of Biological Filters Used for Drinking Water Treatment

The impact of preozonation and filter contact time (depth) on microbial communities was examined in drinking water biofilters treating Ohio River water which had undergone conventional treatment (coagulation, flocculation, sedimentation) or solutions of natural organic matter isolated from groundwater (both ozonated and nonozonated). With respect to filter depth, compared to filters treating nonozonated waters, preozonation of treated water led to greater differences in community phospholipid fatty acid (PLFA) profiles, utilization of sole carbon sources (Biolog), and arbitrarily primed PCR fingerprints. PLFA profiles indicated that there was a shift toward anaerobic bacteria in the communities found in the filter treating ozonated water compared to the communities found in the filter treating nonozonated settled water, which had a greater abundance of eukaryotic markers.     

The Syk Protein Tyrosine Kinase Is Essential for Fcγ Receptor Signaling in Macrophages and Neutrophils

The cytoplasmic protein tyrosine kinase Syk has two amino-terminal SH2 domains that engage phosphorylated immunoreceptor tyrosine-based activation motifs in the signaling subunits of immunoreceptors. Syk, in conjunction with Src family kinases, has been implicated in immunoreceptor signaling in both lymphoid and myeloid cells. We have investigated the role of Syk in Fcγ receptor (FcγR)-dependent and -independent responses in bone marrow-derived macrophages and neutrophils by using mouse radiation chimeras reconstituted with fetal liver cells from Syk^−/− embryos. Chimeric mice developed an abdominal hemorrhage starting 2 to 3 months after transplantation that was ultimately lethal. Syk-deficient neutrophils derived from the bone marrow were incapable of generating reactive oxygen intermediates in response to FcγR engagement but responded normally to tetradecanoyl phorbol acetate stimulation. Syk-deficient macrophages were defective in phagocytosis induced by FcγR but showed normal phagocytosis in response to complement. The tyrosine phosphorylation of multiple cellular polypeptides, including the FcγR γ chain, as well as Erk2 activation, was compromised in Syk^−/− macrophages after FcγR stimulation. In contrast, the induction of nitric oxide synthase in macrophages stimulated with lipopolysaccharide and gamma interferon was not dependent on Syk. Surprisingly, Syk-deficient macrophages were impaired in the ability to survive or proliferate on plastic petri dishes. Taken together, these results suggest that Syk has specific physiological roles in signaling from FcγRs in neutrophils and macrophages and raise the possibility that in vivo, Syk is involved in signaling events other than those mediated by immunoreceptors.     

House Fly (Musca domestica L.) Attraction to Insect Honeydew

House flies are of major concern as vectors of food-borne pathogens to food crops. House flies are common pests on cattle feedlots and dairies, where they develop in and feed on animal waste. By contacting animal waste, house flies can acquire human pathogenic bacteria such as Escherichia coli and Salmonella spp., in addition to other bacteria, viruses, or parasites that may infect humans and animals. The subsequent dispersal of house flies from animal facilities to nearby agricultural fields containing food crops may lead to pre-harvest food contamination with these pathogens. We hypothesized that odors from honeydew, the sugary excreta produced by sucking insects feeding on crops, or molds and fungi growing on honeydew, may attract house flies, thereby increasing the risk of food crop contamination. House fly attraction to honeydew-contaminated plant material was evaluated using a laboratory bioassay. House flies were attracted to the following plant-pest-honeydew combinations: citrus mealybug on squash fruit, pea aphid on faba bean plants, whitefly on navel orange and grapefruit leaves, and combined citrus mealybug and cottony cushion scale on mandarin orange leaves. House flies were not attracted to field-collected samples of lerp psyllids on eucalyptus plants or aphids on crepe myrtle leaves. Fungi associated with field-collected honeydews were isolated and identified for further study as possible emitters of volatiles attractive to house flies. Two fungal species, Aureobasidium pullulans and Cladosporium cladosporioides, were repeatedly isolated from field-collected honeydew samples. Both fungal species were grown in potato dextrose enrichment broth and house fly attraction to volatiles from these fungal cultures was evaluated. House flies were attracted to odors from A. pullulans cultures but not to those of C. cladosporioides. Identification of specific honeydew odors that are attractive to house flies could be valuable for the development of improved house fly baits for management of this pest species.     

Modulation of Human Valve Interstitial Cell Phenotype and Function Using a Fibroblast Growth Factor 2 Formulation

Valve interstitial cells (VICs) are fibroblastic in nature however in culture it is widely accepted that they differentiate into a myofibroblastic phenotype. This study assessed a fibroblast culture media formulation for its ability to maintain the phenotype and function of VICs as in the intact healthy valve. Normal human VICs were cultured separately in standard DMEM and in fibroblast media consisting of FGF2 (10ng/ml), insulin (50ng/ml) and 2% FCS for at least a week. Cell morphology, aspect ratio, size, levels and distribution of protein expression, proliferation, cell cycle, contraction and migration were assessed. Some VICs and some valve endothelial cells expressed FGF2 in valve tissue and this expression was increased in calcified valves. VICs in DMEM exhibited large, spread cells whereas VICs in fibroblast media were smaller, elongated and spindly. Aspect ratio and size were both significantly higher in DMEM (p<0.01). The level of expression of α-SMA was significantly reduced in fibroblast media at day 2 after isolation (p<0.01) and the expression of α-SMA, SM22 and EDA-fibronectin was significantly reduced in fibroblast media at days 7 and 12 post-isolation (p<0.01). Expression of cytoskeletal proteins, bone marker proteins and extracellular matrix proteins was reduced in fibroblast media. Proliferation of VICs in fibroblast media was significantly reduced at weeks 1 (p<0.05) and 2 (p<0.01). Collagen gel contraction was significantly reduced in fibroblast media (p<0.05). VICs were found to have significantly fewer and smaller focal adhesions in fibroblast media (p<0.01) with significantly fewer supermature focal adhesions in fibroblast media (p<0.001). Ultrastructurally, VICs in fibroblast media resembled native VICs from intact valves. VICs in fibroblast media demonstrated a slower migratory ability after wounding at 72 hours (p<0.01). Treatment of human VICs with this fibroblast media formulation has the ability to maintain and to dedifferentiate the VICs back to a fibroblastic phenotype with phenotypic and functional characteristics ascribed to cells in the intact valve. This methodology is fundamental in the study of normal valve biology, pathology and in the field of tissue engineering.     

INTROGRESSION IN THE DROSOPHILA SUBOBSCURA—D. MADEIRENSIS SISTER SPECIES: EVIDENCE OF GENE FLOW IN NUCLEAR GENES DESPITE MITOCHONDRIAL DIFFERENTIATION

Species hybridization, and thus the potential for gene flow, was once viewed as reproductive mistake. However, recent analysis based on large datasets and newly developed models suggest that gene exchange is not as rare as originally suspected. To investigate the history and speciation of the closely related species Drosophila subobscura, D. madeirensis, and D. guanche, we obtained polymorphism and divergence data for 26 regions throughout the genome, including the Y chromosome and mitochondrial DNA. We found that the D. subobscura X/autosome ratio of silent nucleotide diversity is significantly smaller than the 0.75 expected under neutrality. This pattern, if held genomewide, may reflect a faster accumulation of beneficial mutations on the X chromosome than on autosomes. We also detected evidence of gene flow in autosomal regions, while sex chromosomes remain distinct. This is consistent with the large X effect on hybrid male sterility seen in this system and the presence of two X chromosome inversions fixed between species. Overall, our data conform to chromosomal speciation models in which rearrangements are proposed to serve as gene flow barriers. Contrary to other observations in Drosophila, the mitochondrial genome appears resilient to gene flow in the presence of nuclear exchange.     

Stratification in French Guiana: Cerambycid Beetles Go Up When Rains Come Down

When tropical rain forest insect species are associated with a particular season or forest stratum, it can imply tolerance for heat and drought—or moisture dependence; attributes that may predict their responses to global climate change. In French Guiana (1995–1996), wood‐boring cerambycid beetles made a seasonal shift in stratum. During the dry season, ground stratum bait branches were densely colonized, but during the rainy season almost all cerambycids emerged from canopy stratum branches. Because the same substrate was available at both levels, abiotic factors probably influenced branch selection. In this study, cerambycids were reared at the same site (2007–2008) to determine if the seasonal shift recurred. Microclimate data (temperature, relative humidity, and wind speed) were collected with portable weather meters to test the hypothesis that microclimate would be similar at ground stratum during the dry season, and at canopy stratum during the rainy season. The seasonal shift in stratum did recur; many cerambycid individuals (56%) belonged to species classified as ‘seasonal shifters’. Temperatures in the preferred microhabitats were intermediate, but relative humidity remained high during the rainy season (regardless of stratum) and it was windier in the canopy (regardless of season). The shifters preferentially colonized branches at moderate mean temperatures (23.0–24.3°C) and high mean relative humidities (91.3–100%). Shifters were considered season and stratum generalists because they were reared at both strata and were present in both seasons, but they may actually track a narrow microclimate window. Should the regional climate become warmer and drier, it would probably favor species currently restricted to the dry season or canopy stratum.     

Discovery and synthesis of 6,7,8,9-tetrahydro-5H-pyrimido-[4,5-d]azepines as novel TRPV1 antagonists

Utilization of a tetrahydro-pyrimdoazepine core as a bioisosteric replacement for a piperazine-urea resulted in the discovery a novel series of potent antagonists of TRPV1. The tetrahydro-pyrimdoazepines have been identified as having good in vitro and in vivo potency and acceptable physical properties.