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271.
内蒙古石拐地区石拐群召沟组中的长腹鳍大青山鳕(新属、新种) Daqingshaniscus longiventralis gen. et sp. nov. 是在我国中侏罗世地层中发现的一比较原始的古鳕类.其头骨眶后部分短,鳃盖骨大于下鳃盖骨,背鳍位于腹鳍与臀鳍之间,腹鳍基线长,鳍条都从基部分节、远端分叉,棘鳞仅见于尾上叶,全歪型尾,鳞片呈菱形.大青山鳕既与苏联南哈萨克斯坦 Karatau 地区的 Pteroniscus 很接近,又与我国新疆的维吾尔鳕 Uighuroniscus 及西德北部的 Stadthagen 地区的 Indaginilepis 相似.  相似文献   
272.
The plant metabolite, 6-methoxybenzoxazolinone (6-MBOA), occurring in leaf tissue of rapidly growing monocots, cues reproduction in some mammals. In the pine vole, Microtus pinetorum, peripubertal females respond to this nonestrogenic compound with a 40% increase in serum levels of follicle-stimulating hormone (FSH). In addition, 6-MBOA significantly increases the weight of the ovary and uterus in both peripubertal and mature voles. This study is the first to offer evidence that 6-MBOA interacts with the pituitary to stimulate reproduction in voles.  相似文献   
273.
Monochlorobimane (syn-(ClCH2, CH3)-1,5-diazabicyclo-[3.3.0]-octa-3,6-dione-2,8-dione; mBCl) forms a fluorescent adduct with glutathione (GSH), which has been used as a basis for flow cytometric analysis. While mBCl will react nonspecifically with many different thiols, preferential derivatization of GSH can be achieved by using a low concentration of mBCl, since the reaction with GSH is catalyzed by GSH S-transferase, and the nonenzymatic reaction is very slow (k = 3.3 x 10(-1) M-1 s-1 at 37 degrees C, pH 7.5). The rate of derivatization of cellular GSH can be 1000 times greater than predicted from the nonenzymatic reaction rate, although this factor can vary among cell lines. GSH values obtained by flow cytometry (FCM) agree well with those obtained by an enzymatic assay, over a wide range of GSH values, for EMT6/SF cells treated with L-buthionine sulfoximine to vary GSH content. FCM analysis of the GSH content of cells obtained by disaggregation of EMT6/SF tumors, grown in BALB/c mice, revealed a wide variation in single-cell GSH content. The data suggest that there are distinct subpopulations within these tumors, which can be partially characterized by GSH content, but may also have other distinguishing characteristics, such as enhanced sensitivity or resistance to cytotoxic agents. Heterogeneity in single-cell GSH content was also observed by FCM analysis of cells obtained by disaggregation of a biopsy of a human renal cell carcinoma. This result points to the potential value of FCM analysis of GSH in the identification and characterization of human tumor subpopulations which may be of clinical significance in the treatment of cancer by radiation or chemotherapeutic agents.  相似文献   
274.
唐崇惕  顾嘉寿 《四川动物》1999,18(4):152-156
内蒙科尔沁草原是牛羊胰脏阔盘吸虫病及肝脏双腔吸虫病严重的流行区。作者从双腔吸虫的昆虫宿主(第二中间宿主) 黑玉蚂蚁(Formica gagates) 腹中查获索线虫幼虫, 检到从黑玉蚂蚁腹部自动弹出的后感染期的索幼虫。与此后感染期索幼虫同形态的索幼虫在黑玉蚂蚁巢窝土壤中也找到。黑玉蚂蚁巢窝土壤中有数种索科线虫, 仅中华二索线虫( Amphimermischinensis) 的雌雄成虫在长细大小以及形态结构上与黑玉蚂蚁索幼虫相像, 它们是否同一种类尚待实验证实。  相似文献   
275.
Elotuzumab is a monoclonal antibody in development for multiple myeloma (MM) that targets CS1, a cell surface glycoprotein expressed on MM cells. In preclinical models, elotuzumab exerts anti-MM efficacy via natural killer (NK)-cell-mediated antibody-dependent cellular cytotoxicity (ADCC). CS1 is also expressed at lower levels on NK cells where it acts as an activating receptor. We hypothesized that elotuzumab may have additional mechanisms of action via ligation of CS1 on NK cells that complement ADCC activity. Herein, we show that elotuzumab appears to induce activation of NK cells by binding to NK cell CS1 which promotes cytotoxicity against CS1(+) MM cells but not against autologous CS1(+) NK cells. Elotuzumab may also promote CS1–CS1 interactions between NK cells and CS1(+) target cells to enhance cytotoxicity in a manner independent of ADCC. NK cell activation appears dependent on differential expression of the signaling intermediary EAT-2 which is present in NK cells but absent in primary, human MM cells. Taken together, these data suggest elotuzumab may enhance NK cell function directly and confer anti-MM efficacy by means beyond ADCC alone.  相似文献   
276.
烟粉虱对不同寄主植物定向行为研究(英文)   总被引:3,自引:0,他引:3  
采用Y形嗅觉仪测定法和干燥器测定法研究了烟粉虱对一品红、地瓜、菜心、番茄和包菜 5种植物的定向行为 ,结果表明 :(1) 5种植物对烟粉虱均有引诱作用 ;(2 )不同种植物对烟粉虱有不同的引诱作用 ,其引诱力的顺序为 :一品红 >菜心 >地瓜 >包菜 >蕃茄 ,方差分析表明 :烟粉虱对 5种植物的定向行为差异极显著 ,LSD法测定进一步表明 :一品红与其余 4种植物差异极显著 ;菜心与包菜和番茄的差异达到显著水平 ,而与地瓜无显著差异 ;地瓜与包菜、番茄之间以及包菜与番茄之间均无差异显著性。  相似文献   
277.
While hybridization between Native and Introduced Phragmites australis has not been documented across much of North America, it poses an ongoing threat to Native P. australis across its range. This is especially true for native populations in the biologically rich, but sparsely distributed wetlands of the southwest United States, which are among the most imperiled systems in North America. We identified multiple Hybrid P. australis stands in the Las Vegas Wash watershed, NV, a key regional link to the Colorado River basin. Rapid urbanization in this watershed has caused striking changes in water and nutrient inputs and the distribution of wetland habitats has also changed, with urban wetlands expanding but an overall reduction in wetland habitats regionally. Native P. australis has likely been present in the Wash wetland community in low abundance for thousands of years, but today Hybrid and Native plants dominate the shoreline along much of the Wash. In contrast, Introduced P. australis is rare, suggesting that opportunities for novel hybridization events remain uncommon. Hybrid crosses derived from both the native and introduced maternal lineages are widespread, although the conditions that precluded their establishment are unknown and we did not find evidence for backcrossing. Spread of Hybrid plants is likely associated with flooding events as well as restoration activities, including revegetation efforts and construction for erosion control, that have redistributed sediments containing P. australis rhizomes. Downstream escape of Hybrid plants to Lake Mead and wetlands throughout the lower Colorado River basin is of management concern as these Hybrids appear vigorous and could spread rapidly.  相似文献   
278.
本文记述了在内蒙古沙拉木伦额尔登敖包地区第三系下渐新统乌兰戈楚组中发现的始巨犀的一个新种:寿氏始巨犀(Juxia shoui)。据其前臼齿及鼻切迹的位置等特点,这一新种当为始巨犀属中比较进步的一个成员,是包氏始巨犀和巨犀之间的过渡类型的犀类动物。  相似文献   
279.
280.
香港次生林下植物菌根的调查   总被引:6,自引:0,他引:6  
本文报道了香港64种野生植物根系天然感染菌根菌的状况:98.4%的植物都不同程度地感染上了菌根菌,98.1%的根样发现受内生菌根(VAM)的感染,其中小叶青冈(Quercusmyrsinaefolia)同时受外生菌根(ECM)和内生菌根的感染。该研究揭示了香港次生林植物在自然条件下受菌根菌感染的普遍性,为进一步探讨华南地区菌根与退化地区植物群落演替的关系提供了重要的本底资料。  相似文献   
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