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1.
《水生昆虫》2012,34(2):139-155
In the Volga Basin, the small Baikalian amphipod Gmelinoides fasciatus was introduced in 1965 into the Gorky reservoir in order to enhance fish production; it appeared in 1986 in the Rybinsk reservoir and we recorded it during monitoring activities in 2006 at Tver. In total, at the monitoring site Tver/Migalovo 69 benthic invertebrate taxa were identified. We compared data from three summer seasons. During summer low flow period Gmelinoides fasciatus did not exceed a share of 12.6% considering individual (ind) densities (mean abundance 165 ± 104 ind m?2) and 14.2% considering biomass (mean biomass 0.39 ± 0.44 g m?2). Abundances and biomass of G. fasciatus were shown to be stable over three years and no increase was observed. The monthly dataset (March–November 2008) revealed dynamics in relation to the native benthic communities and it was shown that the maximal densities of Gmelinoides did not exceed 587 ind m–2. Understanding the effects on benthic communities caused by the invasive amphipod Gmelinoides fasciatus is crucial in order to predict further developments in European inland waters and to establish management strategies. 相似文献
2.
《Ethnic and racial studies》2012,35(6):971-987
Abstract Deploying liberal multiculturalist discourse, the media depicts professional basketball as a post-racial space where all talented players, regardless of their race, can thrive if they work hard. An analysis of the construction of non-white players in the 1930s and in 2010 demonstrates sport as modulated by racially charged discourse. As part of a liberal multiculturalist frame, the coding of basketball players as hero, threat and novelty serve to privilege whiteness and replicate racialized and gendered images that can be traced to the 1930s. In doing so, the article highlights how liberal multiculturalism involves racial triangulation and the simultaneous processes of hyper-racialization and de-racialization. 相似文献
3.
E. Cortés A.A. Kirk J.A. Goolsby P.J. Moran A.E. Racelis M.A. Marcos-García 《Biocontrol Science and Technology》2011,21(11):1369-1373
Arundo donax L. (Poaceae) is native to Mediterranean Europe and invasive in the Rio Grande Basin of North America. Rhizomes from nine sites in France and Spain infested with a candidate control agent, the armoured scale Rhizaspidiotus donacis (Hemiptera: Diaspididae) weighed 50% less than those from nine sites without scale. 相似文献
4.
R L Blakely 《American journal of physical anthropology》1989,80(2):173-185
Because plants and animals consume or absorb different amounts of strontium and calcium, anthropologists are able to use strontium/calcium (Sr/Ca) ratios from archaeologically recovered human bone to estimate the relative contributions of meat and plants to paleodiets. Often females exhibit higher Sr/Ca ratios than males, a fact usually attributed to lower meat intake among women. However, in vivo and in vitro experiments with laboratory animals show that pregnancy and lactation elevate maternal bone strontium and depress maternal bone calcium because 1) strontium is discriminated against in favor of calcium in the transport of ions to the placenta and mammary glands and 2) pregnancy and lactation facilitate absorption of alkaline earth metals from the gut. In this study, bone Sr/Ca ratios and strontium concentrations were compared between reproductive-age females, postmenopausal females, and adult males from two late prehistoric Native American sites in Georgia: the King site (N = 43) and the Etowah site (N = 51). At the King site, the mean Sr/Ca ratio of females was over 14% greater than that of males. At Etowah, the mean strontium level of reproductive-age females exceeded that of postmenopausal females by almost 25%. Most of the difference, it is argued, is due to pregnancy and lactation. A dietary preference among pregnant and lactating women for foods high in alkaline earths, particularly nuts and corn, may also be partially responsible. Until we assess the influence variables other than nutrition exert on trace element concentrations, our reconstructions of paleodiets will be suspect. 相似文献
5.
A cDNA probe for the low density lipoprotein (LDL) receptor gene was used to screen DNA samples from 52 unrelated Finnish patients with the heterozygous form of familial hypercholesterolemia (FH) and 51 healthy controls. Southern blot analysis using the restriction enzyme PvuII revealed an abnormal 11 kb (kilo base-pair) restriction fragment in 16 (31%) of the patients but none of the controls. A more detailed restriction enzyme analysis of the DNA from patients revealed a mutation which apparently is due to an 8 kb deletion extending from intron 15 to exon 18 of the LDL receptor gene. Co-segregation of FH with the mutated gene was demonstrated in three families. These data are consistent with a ‘founder gene effect’ and support the assumption that recombinant DNA methods may have great impact on the diagnostics of FH in genetically homogeneous populations. 相似文献
6.
本文对一次密度梯度超速离心获得的四种脂蛋白(VLDL、LDL、HDL_2、HDL_3)进行了理化性质的研究。超速离心分析LDL、HDL_2,HDL_3均呈现一个单一尖锐的上浮峰,上浮速率分别为S_1 6.9和F~0_(1.21) 5.7及2.6。等电点聚焦电泳显示,VLDL主要含载脂蛋白C族,E族和少量A-I,B。HDL_2、HDL_3二者载脂蛋白的种类很相似,但量上略有差异,均以载脂蛋白A-Ⅰ,A-Ⅱ为主,Apoc’s,E次之。VLDL、LDL、HDL_2和HDL_3的化学组分分析与文献报道相似。 作者用本法初步分析了不同性别的各脂蛋白分布图,获得有意义的结果。 相似文献
7.
Human monocyte-macrophages in culture express specific receptors for low density lipoproteins (LDL receptor) and human acetylated LDL (AcLDL receptors or scavenger receptors). After 24 h in lipoprotein-deficient serum, the cells expressed 2-3 fold more AcLDL receptors than LDL receptors as measured by trypsin releasable radioactivity after exposure to 125I-LDL or 125I-AcLDL at 37 degrees C. The efficiency of intracellular ligand delivery by the two receptors was evaluated as an internalization index (defined as intracellular + degraded/bound ligand). This index was several fold greater for 125I-AcLDL than for 125I-LDL, in the same cells exposed to either ligand under identical conditions. These results suggest that the scavenger receptors recycle more rapidly than do LDL receptors. 相似文献
8.
M. S. Awan 《BioControl》1990,35(2):203-210
Three species of hemipteran predators preyed differently upon 1st instarHeliothis punctiger Wallengren larvae.Cermatulus nasalis consumed more larvae thanOechalia schellenbergii which consumed more larvae thanTropiconabis nigrolineatus. All the species consumed significantly less 1st instar larvae on plants than what they consumed in Petri-dishes. Fifth instar predators showed significant differences in
terms of prey consumption due to sex independent of searching conditions. Only 4th and 5th instars ofT. nigrolineatus attacked and captured 2nd instars ofH. punctiger larvae. The other 2 species however readily attacked and consumed 2nd instarH. punctiger larvae. Their prey consumption was similar in Petri-dishes and on plants.
Only 5th instars ofT. nigrolineatus could subdue and capture 3rd instarH. punctiger larvae. Second instar pentatomids captured just one 3rd instar larva but older instars killed and ate more. Fourth instarH. punctiger larvae were immune to attacks by allT. nigrolineatus and younger pentatomids due to their defense ploys but 5th instar pentatomids could subdue and capture them.
None of the predators captured 5th instarH. punctiger larvae except few 5th instar females ofC. naslis andO. schellenbergii.
相似文献
9.
Cytochalasin B (CB) is known to interfere reversibly with the cytoplasmic contractile filamental network of mammalian cells. The role of the microfilament system in the mechanism of the reactive oxygen intermediates release of polymorphonuclear leukocytes (PMNL) was studied for different kinds of stimuli. PMNL from fresh human blood were treated with CB and stimulated by adherence on plastic surfaces, by opsonized zymosan, by phorbol myristate acetate and by N-formylmethionyl-phenylalaline. The production of reactive oxygen species were monitored by simultaneous detection of native, luminol-independent, luminescence (NL) and luminol-dependent luminescence (LDL) using a method of spectral discrimination. Different influences of CB on NL with respect to LDL as well stimuli-dependent influences of CB on the luminescence response of PMNL were observed. Especially phagocytosis-associated activation of PMNL was strongly inhibited by CB, whereas LDL was reduced to a much greater extent in comparison with NL. A firm involvement of the microfilament system is indicated, but it depends on the kind of stimulus engaged. 相似文献
10.
While soluble forms of the sialyltransferase (sialyl-T) enzyme have been detected in significant quantities in serum, the exact source(s) of the enzyme, or the factors controlling its secretion are poorly understood. In this study, we have examined the relationship between ambient plasma cholesterol concentrations and sialyl-T activities and also levels of constituent plasma sialoglycoproteins (SGP). There was an inverse relationship between levels of the 2,6 sialyl-T enzyme and both total plasma cholesterol and HDL, although no such relationship was observed for the 2,3 enzyme. While there was no correlation between total cholesterol and the levels of plasma SGPs, there was an inverse relationship between the HDL component and 2,3 SGPs. 相似文献