Algal Chemical Defense Against Herbivores: Allocation of Phenolic Compounds in the Kelp Alaria marginata

Higher concentrations of phenolic compounds were found in the reproductive fronds (sporophylls) of the intertidal kelp Alaria marginata than were found in the vegetative blades. The sporophylls were consumed by herbivorous snails at a lower rate than were the vegetative blades, in both field and laboratory studies. These results indicate that differential internal production of defensive compounds in a marine alga can significantly affect the pattern of herbivory on the plant.     

Nucleon stability: a geochemical test independent of decay mode

By analyzing published geochemical data on xenon isotopes measured in a 2.46 x 10(9)-year-old telluride ore, a lower limit of 1.6 x 10(25) years has been obtained for the mean lifetime of the nucleons in the tellurium-130 nucleus. This result is insensitive to the particular mode by which the nucleons decay and therefore provides a rigorous limit on possible baryon number nonconservation. The new limit is about two orders of magnitude better than the previous rigorous limit on nucleon stability.     

Changes in metal speciation in a sediment core from an acidified Black Forest lake (Wildsee,Germany)

Wildsee is a small cirque lake in northern Black Forest, Fed. Rep. Germany. The recent acidification history was reconstructed by means of the paleolimnological diatom approach. Furthermore, the bonding stability of selected metals (Al, Fe, Pb, Zn, and Cd) within the sediment core has been evaluated by applying sequential chemical extraction, which differentiates between residual, labile and intermediate compounds. Increases in total concentrations of Al, Pb, and Zn as well as losses in bonding strength of these metals appear to be caused by acidification. Cd appears to be derived principally from direct deposition on the lake and its catchment rather than from acidification-mediated soil release.     

Survival and potential denitrifying activity of Azospirillum lipoferum and Bradyrhizobium japonicum inoculated into sterilized soil

Summary Potential denitrifying activity and population dynamics of Azospirillum lipoferum (137C) and Bradyrhizobium japonicum (G2sp) inoculated into a -sterilized soil were studied for a period of 3 weeks. The denitrifying enzyme potential of soil inoculated independently with each bacterial species was strongly stimulated by the presence of a plant (Zea mays L.). Simultaneous inoculation of both bacteria also produced a higher denitrifying enzyme potential than simple inoculation. Even with double inoculation, the presence of a plant did not modify the evolution of the activity. The response of the population dynamics to these treatments followed a different pattern. The population dynamics of A. lipoferum was not affected by the presence of the plant or by the presence of B. japonicum. In contrast, the presence of both a plant and of A. lipoferum seemed to promote the growth of B. japonicum.     

奶牛隐性乳房炎的研究进展

奶牛乳房炎是奶牛常见、多发的疾病之一,严重制约着奶牛养殖业的发展,文章对奶牛乳房炎的病因、发病机理、临床症状、诊断方法及防治措施等进行了综述,这将对内蒙古自治区奶牛养殖业的发展产生积极影响.     

华北土石山区森林枯落物与土壤水文效应研究

以河北省易县崇陵小流域3种不同林分的枯落物层和土壤层为研究对象,对其水文效应进行初步研究。结果表明:3种林分枯落物蓄积量差异较大,侧柏枯落物蓄积量最大,高达57.9t/hm2,油松枯落物蓄积量次之,为29.8t/hm2,刺槐枯落物蓄积量最小,是28.7t/hm2;3种林分枯落物中,侧柏林的枯落物持水能力最强,为114.5t/hm2,油松林的枯落物持最小,仅为60.1t/hm2;3种林分下土壤的平均容重和总孔隙度差别不大,容重的变化范围在1.46~1.66g/cm3;总孔隙度均偏低,具体表现为:侧柏(30.86%)油松(29.31%)刺槐(27.1%);3种林分林下土壤持水能力有所差异,表现为:侧柏油松刺槐。土壤持水能力与各林分林下土壤的孔隙度大小呈正相关,即土壤孔隙度越大,土壤的持水能力越强;3种林分的土壤稳渗速率相差较大,表现为:刺槐(10.50mm/min)油松(2.80mm/min)侧柏(0.80mm/min)。     

西南矮马矮小性状基因SHOX的克隆测序和多态性研究

本研究首次克隆出西南马矮小性状基因完整第二外显子序列,GenBank登录号为EU556739;通过PCR-SSCP方法对8个品种150匹马的该序列做了多态性分析,在P2位点上268处有1个G→A的突变,和431处有1个T→G的突变导致了等位基因B变为等位基因A.该位点除云南文山马(WS)的优势基因型和优势等位基因分别为AB型和B外,其余类群马均为BB型和B.云南丘北马(QB)、云南文山马(WS)、云南大理马(DL)、建昌马(JC)和设特兰马(ST)在P2位点上处于Hardy-Weinberg平衡状态.