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排序方式: 共有112条查询结果,搜索用时 15 毫秒
1.
Cascade J. B. Sorte Ron J. Etter Robert Spackman Elizabeth E. Boyle Robyn E. Hannigan 《PloS one》2013,8(11)
As the climate warms, species that cannot tolerate changing conditions will only persist if they undergo range shifts. Redistribution ability may be particularly variable for benthic marine species that disperse as pelagic larvae in ocean currents. The blue mussel, Mytilus edulis, has recently experienced a warming-related range contraction in the southeastern USA and may face limitations to northward range shifts within the Gulf of Maine where dominant coastal currents flow southward. Thus, blue mussels might be especially vulnerable to warming, and understanding dispersal patterns is crucial given the species'' relatively long planktonic larval period (>1 month). To determine whether trace elemental “fingerprints” incorporated in mussel shells could be used to identify population sources (i.e. collection locations), we assessed the geographic variation in shell chemistry of blue mussels collected from seven populations between Cape Cod, Massachusetts and northern Maine. Across this ∼500 km of coastline, we were able to successfully predict population sources for over two-thirds of juvenile individuals, with almost 80% of juveniles classified within one site of their collection location and 97% correctly classified to region. These results indicate that significant differences in elemental signatures of mussel shells exist between open-coast sites separated by ∼50 km throughout the Gulf of Maine. Our findings suggest that elemental “fingerprinting” is a promising approach for predicting redistribution potential of the blue mussel, an ecologically and economically important species in the region. 相似文献
2.
Ron J. Etter 《Evolution; international journal of organic evolution》1988,42(2):322-334
Field and laboratory experiments were used to investigate the variation and phenotypic plasticity in the adhesive abilities of the intertidal snail Nucella lapillus between high- and low-wave-energy environments. Whelks from an exposed coast produced a larger pedal surface area and were more resistant to dislodgement than were similar-sized individuals from a protected shore. Tenacity (g/cm2) was similar between individuals from exposed and protected shores, indicating that variation in resisting dislodgement was solely a function of pedal surface area. Whelks from exposed and protected shores did not differ in pedal surface area as they emerged from egg capsules or when reared in the laboratory under uniform conditions, suggesting that variation between populations does not represent genetic differentiation. Individuals from high-and low-wave-energy environments reared intertidally produced a larger pedal surface area than did those reared in the laboratory. The extent to which pedal surface area increased corresponded to the intensity of wave action. These findings suggest that pedal surface area is a highly plastic character modulated or induced by the water turbulence accompanying breaking waves. A reciprocal-transplant experiment confirmed this notion but revealed an asymmetry in the plasticity. Snails from the protected site transplanted to an exposed shore formed a much larger pedal surface area than did controls reared on the protected shore. In contrast, whelks from a wave-swept shore transplanted to a protected shore differed little from their controls reared on the exposed shore. The asymmetric response parallels a possible asymmetry in the risks of acclimating to a temporally unpredictable environmental cue, such as wave action. 相似文献
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AB Kane RP Stanton EG Raymond ME Dobson ME Knafelc JL Farber 《The Journal of cell biology》1980,87(3):643-651
The relationship between intracellular lysosomal rupture and cell death caused by silica was studied in P388d(1) macrophages. After 3 h of exposure to 150 μg silica in medium containing 1.8 mM Ca(2+), 60 percent of the cells were unable to exclude trypan blue. In the absence of extracellular Ca(2+), however, all of the cells remained viable. Phagocytosis of silica particles occurred to the same extent in the presence or absence of Ca(2+). The percentage of P388D(1) cells killed by silica depended on the dose and the concentration of Ca(2+) in the medium. Intracellular lyosomal rupture after exposure to silica was measured by acridine orange fluorescence or histochemical assay of horseradish peroxidase. With either assay, 60 percent of the cells exposed to 150 μg silica for 3 h in the presence of Ca(2+) showed intracellular lysosomal rupture, was not associated with measureable degradation of total DNA, RNA, protein, or phospholipids or accelerated turnover of exogenous horseradish peroxidase. Pretreatment with promethazine (20 μg/ml) protected 80 percent of P388D(1) macrophages against silica toxicity although lysosomal rupture occurred in 60-70 percent of the cells. Intracellular lysosomal rupture was prevented in 80 percent of the cells by pretreatment with indomethacin (5 x 10(-5)M), yet 40-50 percent of the cells died after 3 h of exposure to 150 μg silica in 1.8 mM extracellular Ca(2+). The calcium ionophore A23187 also caused intracellular lysosomal rupture in 90-98 percent of the cells treated for 1 h in either the presence or absence of extracellular Ca(2+). With the addition of 1.8 mM Ca(2+), 80 percent of the cells was killed after 3 h, whereas all of the cells remained viable in the absence of Ca(2+). These experiments suggest that intracellular lysosomal rupture is not causally related to the cell death cause by silica or . Cell death is dependent on extracellular Ca(2+) and may be mediated by an influx of these ions across the plasma membrane permeability barrier damaged directly by exposure to these toxins. A23187相似文献
5.
Steven M. Gray Gary J. Roloff Daniel B. Kramer Dwayne R. Etter Kurt C. Vercauteren Robert A. Montgomery 《The Journal of wildlife management》2020,84(4):739-748
In North America, wild pigs (Sus scrofa; feral pigs, feral swine, wild boars) are a widespread exotic species capable of creating large-scale biotic and abiotic landscape perturbations. Quantification of wild pig environmental effects has been particularly problematic in northern climates, where they occur only recently as localized populations at low densities. Between 2016 and 2017, we assessed short-term (within ~2 yrs of disturbance) effects of a low-density wild pig population on forest features in the central Lower Peninsula of Michigan, USA. We identified 16 8-ha sites using global positioning system locations from 7 radio-collared wild pigs for sampling. Within each site, we conducted fine-scale assessments at 81 plots and quantified potential disturbance by wild pigs. We defined disturbance as exposure of overturned soil, often resulting from rooting behavior by wild pigs. We quantified ground cover of plants within paired 1-m2 frames at each plot, determined effects to tree regeneration using point-centered quarter sampling, and collected soil cores from each plot. We observed less percent ground cover of native herbaceous plants and lower species diversity, particularly for plants with a coefficient of conservatism ≥5, in plots disturbed by wild pigs. We did not observe an increase in colonization of exotic plants following disturbance, though the observed prevalence of exotic plants was low. Wild pigs did not select for tree species when rooting, and we did not detect any differences in regeneration of light- and heavy-seeded tree species between disturbed or undisturbed plots. Magnesium and ammonium content in soils were lower in disturbed plots, suggesting soil disturbance accelerated leaching of macronutrients, potentially altering nitrogen transformation. Our study suggested that disturbances by wild pigs, even at low densities, alters short-term native herbaceous plant diversity and soil chemistry. Thus, small-scale exclusion of wild pigs from vulnerable and rare plant communities may be warranted. © 2020 The Wildlife Society. 相似文献
6.
Andelfinger G Hitte C Etter L Guyon R Bourque G Tesler G Pevzner P Kirkness E Galibert F Benson DW 《Genomics》2004,83(6):1053-1062
Canine tricuspid valve malformation (CTVM) maps to canine chromosome 9 (CFA9), in a region syntenic with gene-dense human chromosome 17q. To define synteny blocks, we analyzed 148 markers on CFA9 using radiation hybrid mapping and established a four-way comparative map for human, mouse, rat, and dog. We identified a large number of rearrangements, allowing us to reconstruct the evolutionary history of individual synteny blocks and large chromosomal segments. A most parsimonious rearrangement scenario for all four species reveals that human chromosome 17q differs from CFA9 and the syntenic rodent chromosomes through two macroreversals of 9.2 and 23 Mb. Compared to a recovered ancestral gene order, CFA9 has undergone 11 reversals of <3 Mb and 2 reversals of >3 Mb. Interspecies reuse of breakpoints for micro- and macrorearrangements was observed. Gene order and content of the ctvm interval are best extrapolated from murine data, showing that multispecies genome rearrangement scenarios contribute to identifying gene content in canine mapping studies. 相似文献
7.
Victoria?BrankinEmail author Marcus?RP?Mitchell Bob?Webb Morag?G?Hunter 《Reproductive biology and endocrinology : RB&E》2003,1(1):55
Oocyte control of granulosa and theca cell function may be mediated by several growth factors via a local feedback loop(s)
between these cell types. This study examined both the role of oocyte-secreted factors on granulosa and thecal cells, cultured
independently and in co-culture, and the effect of stem cell factor (SCF); a granulosa cell derived peptide that appears to
have multiple roles in follicle development. Granulosa and theca cells were isolated from 2–6 mm healthy follicles of mature
porcine ovaries and cultured under serum-free conditions, supplemented with: 100 ng/ml LR3 IGF-1, 10 ng/ml insulin, 100 ng/ml
testosterone, 0–10 ng/ml SCF, 1 ng/ml FSH (granulosa), 0.01 ng/ml LH (theca) or 1 ng/ml FSH and 0.01 ng/ml LH (co-culture)
and with/without oocyte conditioned medium (OCM) or 5 oocytes. Cells were cultured in 96 well plates for 144 h, after which
viable cell numbers were determined. Medium was replaced every 48 h and spent medium analysed for steroids. 相似文献
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The deep sea is a vast and essentially continuous environment with few obvious barriers to gene flow. How populations diverge and new species form in this remote ecosystem is poorly understood. Phylogeographical analyses have begun to provide some insight into evolutionary processes at bathyal depths (<3000 m), but much less is known about evolution in the more extensive abyssal regions (>3000 m). Here, we quantify geographical and bathymetric patterns of genetic variation (16S rRNA mitochondrial gene) in the protobranch bivalve Ledella ultima, which is one of the most abundant abyssal protobranchs in the Atlantic with a broad bathymetric and geographical distribution. We found virtually no genetic divergence within basins and only modest divergence among eight Atlantic basins. Levels of population divergence among basins were related to geographical distance and were greater in the South Atlantic than in the North Atlantic. Ocean‐wide patterns of genetic variation indicate basin‐wide divergence that exceeds what others have found for abyssal organisms, but considerably less than bathyal protobranchs across similar geographical scales. Populations on either side of the Mid‐Atlantic Ridge in the North Atlantic differed, suggesting the Ridge might impede gene flow at abyssal depths. Our results indicate that abyssal populations might be quite large (cosmopolitan), exhibit only modest genetic structure and probably provide little potential for the formation of new species. 相似文献