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31.
Roman Dial C Dial RJ Saunders R Lang SA Lee B Wimberger P Dinapoli MS Egiazarov AS Gipple SL Maghirang MR Swartley-McArdle DJ Yudkovitz SR Shain DH 《Molecular phylogenetics and evolution》2012,63(3):577-584
North American ice worms are the largest glacially-obligate metazoans, inhabiting coastal, temperate glaciers between southcentral Alaska and Oregon. We have collected ice worm specimens from 10 new populations, completing a broad survey throughout their geographic range. Phylogenetic analyses of 87 individuals using fragments of nuclear 18S rRNA, and mitochondrial 12S rRNA and cyctochrome c oxidase subunit 1 (CO1) identified 18 CO1 haplotypes with divergence values up to ~10%. Phylogeographic interpretations suggest a St. Elias Range, Alaskan ancestry from an aquatic mesenchytraeid oligochaete during the early-Pliocene. A gradual, northward expansion by active dispersal from the central St. Elias clade characterizes a northern clade that is confined to Alaska (with one exception on Vancouver Island, British Columbia), while a distinct southern clade representing worms from British Columbia, Washington and Oregon was likely founded by a passive dispersal event originating from a northern ancestor. The geographic boundary between central and southern clades coincides with an ice worm distribution gap located in southern Alaska, which appears to have restricted active gene flow throughout the species' evolutionary history. 相似文献
32.
Bioaerosol concentrations inside one naturally ventilated and one mechanically ventilated swine finishing barn were assessed
by sampling air using membrane filtration and impaction (six-stage Andersen sampler), and assayed by culture method. The barns,
located on the same commercial farm in northeast Kansas, did not show any significant difference (p > 0.05) in concentrations of total and respirable airborne microorganisms. The overall mean total concentrations inside the two barns
were 6.6 × 104 colony forming units (CFU)/m3 (SD = 3.8 × 104 CFU/m3) as measured by filtration and 8.6 × 104 CFU/m3 (SD = 5.1 × 104 CFU/m3) by impaction. The overall mean respirable concentrations were 9.0 × 103 CFU/m3 (SD = 4.1 × 103 CFU/m3) measured by filtration and 2.8 × 104 CFU/m3 (SD = 2.2 × 104 CFU/m3) by impaction. Total and respirable CFU concentrations measured by impaction were significantly (p < 0.05) higher than that by filtration. The persistent strains of microorganisms were various species of the following genera: Staphylococcus, Pseudomonas, Bacillus, Listeria, Enterococcus, Nocardia, Lactobacillus, and Penicillium. It appears that filtration sampling can be used for a qualitative survey of bioaerosols in swine barns while the Andersen
sampler is suitable for both quantitative and qualitative assessments.
Received: 2 April 2001 / Accepted: 13 June 2001 相似文献
33.
EB Adamah-Biassi Y Zhang H Jung S Vissapragada RJ Miller ML Dubocovich 《The journal of histochemistry and cytochemistry》2014,62(1):70-84
The pineal hormone melatonin activates two G-protein coupled receptors (MT1 and MT2) to regulate in part biological functions. The MT1 and MT2 melatonin receptors are heterogeneously distributed in the mammalian brain including humans. In the mouse, only a few reports have assessed the expression of the MT1 melatonin receptor expression using 2-iodomelatonin binding, in situ hybridization and/or polymerase chain reaction (PCR). Here, we described a transgenic mouse in which red fluorescence protein (RFP) is expressed under the control of the endogenous MT1 promoter, by inserting RFP cDNA at the start codon of MTNR1a gene within a bacterial artificial chromosome (BAC) and expressing this construct as a transgene. The expression of RFP in the brain of this mouse was examined either directly under a fluorescent microscope or immunohistochemically using an antibody against RFP (RFP-MT1). RFP-MT1 expression was observed in many brain regions including the subcommissural organ, parts of the ependyma lining the lateral and third ventricles, the aqueduct, the hippocampus, the cerebellum, the pars tuberalis, the habenula and the habenula commissure. This RFP-MT1 transgenic model provides a unique tool for studying the distribution of the MT1 receptor in the brain of mice, its cell-specific expression and its function in vivo. 相似文献
34.
Pregnancy block in mice requires exposure of recently mated females to
urinary pheromones of a strange male, and when working with inbred strains
this invariably requires urine from an outbred line. The pheromones which
induce oestrus and early puberty in mice have been identified as the
brevicomins and dihydrothiazoles. Since the same vomeronasal, neural and
neuroendocrine pathways are also activated in pregnancy block, these
compounds are likely candidates for pregnancy blocking pheromones. However,
these relatively simple chemicals lack the capacity to code for differing
mouse strains. Since large quantities of the polymorphic major urinary
proteins from the lipocalin family found in urine serve as transporters for
the dihydrothiazoles and brevicomins, and differ across strains, then these
proteins must participate in pheromone recognition in the context of
pregnancy block.
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