植被状况对乔木幼苗物种多样性的影响

运用灰色关联度分析亚热带常绿阔叶林植被状况对乔木幼苗物种多样性的影响。结果表明,所选取的植被状况参数对乔木幼苗物种多样性有不同的影响,对乔木幼苗物种多样性影响较大的是草本层的Simpson指数、灌木层Simpson指数和灌木层盖度,影响较小的为草本层盖度和灌木层Shannon-Wiener指数。乔木幼苗4个物种多样性指数受植被状况影响的顺序为：Pielou均匀性指数＞Shannon-Wiener指数＞物种丰富度指数＞Simpson指数。草本层、灌木层和乔木层对乔木幼苗的物种多样性有不同的影响,其影响方式也不一样。     

Phenol-oxidase (laccase) activity in strains of the hyphomycete Chalara paradoxa isolated from olive mill wastewater disposal ponds

Production of laccase activity by nine strains of Chalara paradoxa isolated from olive mill wastewater disposal ponds were studied. Enzyme extracts obtained from cultured broths by adsorption on hydroxyapatite showed a single band of laccase activity on ABTS after polyacrylamide gel electrophoresis (PAGE). They showed small mobility differences, with molecular masses of 67 to 68 kDa. Enzymes from the different strains oxidized a variety of phenolic and non-phenolic substances, and they could be divided into two groups according to their relative activities on substrates. All laccases showed a dual pH dependence of activity, with a maximum in the range of pH 3.0 to 4.5 for ABTS, o-dianisidine and 2,6-dimethoxyphenol, and pH 6.0 (Group 1) or pH 6.5 (Group 2) for syringaldazine and other substrates. Optimal temperatures were in the range of 10 to 28 degrees C for two strains (maximum at 10 degrees C) and 10 to 37 degrees C for the rest. The different enzymes were partially inactivated by heating at 60 degrees C and totally inactivated at 70 degrees C. Laccases were stable in a pH range of 3.0 to 9.0 (except for strain 36A, which was partially inactivated at pH 3.0), but became inactivated at pH 2.0. Altogether these data suggest that Ch. paradoxa strains produce different laccase isoenzymes.     

HOW AND WHEN DO LAMBS RECOGNIZE THE BLEATS OF THEIR MOTHERS?

ABSTRACT

In domestic sheep Ovis aries, the mother and the young display a preferential bond for each other that relies on multimodal inter-individual recognition. Lambs show a preference for their own dam shortly after birth, and this is important for their survival. The role of acoustic cues in this early preference for the mother is not clear. The aim of the present work was to analyze the timing of acoustic recognition of the mother and to identify the physical parameters used in the recognition of maternal bleats by the lamb.

In a first study, we investigated the ability of lambs to discriminate between the bleats of their own mother and an alien equivalent mother in a two-choice test. Both ewes were hidden behind a canvas sheet and lambs were not allowed to approach the dams closer than 1 m, thus preventing visual as well as olfactory perception. Tests were conducted 12 hr, 24 hr or 48 hr after birth (n=19 or 20/group). An indication of vocal discrimination was already present at 24 hr and at 48 hr lambs spent significantly more time near their mother than near the alien dam.

In a second step, we investigated which physical parameters of the bleats were important for recognition. For this, we conducted playback experiments with modified bleats at two weeks postpartum. Ours results show that lambs pay attention to a combination of various time, energy and frequency parameters: timbre (distribution of energy within the spectrum), amplitude and frequency modulations appear to be the most important parameters encoding the individual signature.

We conclude that vocal recognition between the ewe and her lamb plays an important role in the display of preferential mother-young bond from very early on. Our studies also demonstrate that the encoding of the individual signature is not limited to the frequency domain but rather involves a multiparametric encoding process.     

儿童过敏性紫癜早期肾损伤中VCAM-1的临床意义

目的：探讨血管细胞粘附分子-1（VCAM-1）的检测在儿童过敏性紫癜（AP）早期肾损伤中的临床意义。方法：选择明确诊断为AP 患儿85 例,均为早期无肾损害的AP病儿。根据第七版诸福棠实用儿科学有关章节的诊断标准和随访结果,进一步将研究对象分为有肾损害AP 为APN 组,无肾损害AP为AP 组,于同时间、同群体中选择健康儿童35 名为对照组。应用ELISA 法分别检测三组患儿早期无肾损害时血VCAM-1 的含量,分析血VCAM-1在儿童过敏性紫癜早期肾损伤中的临床意义。结果：APN 组血VCAM-1 水平均高于AP组和正常对照组;AP 组亦高于正常对照组,差异均有统计学意义（P〈0.01）。结论：对早期无肾损害的AP病儿,检测血浆VCAM-1 对AP发生APN 的预后诊断有重要的临床意义。     

Insights into the Function of YciM,a Heat Shock Membrane Protein Required To Maintain Envelope Integrity in Escherichia coli

The cell envelope of Gram-negative bacteria is an essential organelle that is important for cell shape and protection from toxic compounds. Proteins involved in envelope biogenesis are therefore attractive targets for the design of new antibacterial agents. In a search for new envelope assembly factors, we screened a collection of Escherichia coli deletion mutants for sensitivity to detergents and hydrophobic antibiotics, a phenotype indicative of defects in the cell envelope. Strains lacking yciM were among the most sensitive strains of the mutant collection. Further characterization of yciM mutants revealed that they display a thermosensitive growth defect on low-osmolarity medium and that they have a significantly altered cell morphology. At elevated temperatures, yciM mutants form bulges containing cytoplasmic material and subsequently lyse. We also discovered that yciM genetically interacts with envC, a gene encoding a regulator of the activity of peptidoglycan amidases. Altogether, these results indicate that YciM is required for envelope integrity. Biochemical characterization of the protein showed that YciM is anchored to the inner membrane via its N terminus, the rest of the protein being exposed to the cytoplasm. Two CXXC motifs are present at the C terminus of YciM and serve to coordinate a redox-sensitive iron center of the rubredoxin type. Both the N-terminal membrane anchor and the C-terminal iron center of YciM are important for function.     

家庭氧疗配合呼吸操治疗慢性阻塞性肺疾病患者的疗效

目的：观察长期家庭氧疗配合呼吸操治疗慢性阻塞性肺疾病（COPD）的临床效果。、方法：选择本院收治的COPD患者80例,随机分为研究组和对照组,各40例,两组均给予常规治疗,研究组同时由医务人员指导给予家庭氧疗和呼吸操训练,随访1年．观察两组治疗前、治疗后6个月和1年肺功能,应用StGeorge’S呼吸问卷（SGRQ）评价生存质量、结果：研究组1年内急性发作1次5人,2次2人,3次及以上1人,对照组1年内急性发作1次9人,2次7人,3次及以上4人（P〈0．05）;研究组治疗后6个月、1年用力肺活量（FVC）、第1秒用力呼气容积（FEVl）和FEVl／FVC均明显升高（P〈0．05）,对照组治疗后6个月、1年FVC、FEVI／FVC与治疗前比较无统计学差异（P〉0．05）;研究组治疗后6个月、1年SGRQ明显降低（P〈0．05）,对照组治疗后6个月、1年SGRQ与治疗前比较无统计学差异（P〉0．05）．结论：家庭氧疗配合呼吸操能明显改善COPD患者肺功能,延缓患者肺功能恶化,提高患者生存质量。     

Structural models of the snake venom factor V activators from Daboia russelli and Daboia lebetina

Blood coagulation factor V (FV) is a multifunctional protein that circulates in human plasma as a precursor molecule which can be activated by thrombin or activated factor X (FXa) in order to express its cofactor activity in prothrombin activation. FV activation is achieved by limited proteolysis after Arg709, Arg1018, and Arg1545 in the FV molecule. The venoms of Daboia russelli and Daboia lebetina contain a serine protease that specifically activates FV by a single cleavage at Arg1545. We have predicted the three-dimensional structure of these enzymes using comparative protein modeling techniques. The plasminogen activator from Agkistrodon acutus, which shows a high degree of homology with the venom FV activators and for which a high-quality crystallographic structure is available, was used as the molecular template. The RVV-V and LVV-V models provide for the first time a detailed and accurate structure of a snake venom FV activator and explain the observed sensitivity or resistance toward a number of serine protease inhibitors. Finally, electrostatic potential calculations show that two positively charged surface patches are present on opposite sides of the active site. We propose that both FV activators achieve their exquisite substrate specificity for the Arg1545 site via interactions between these exosites and FV.     

Spermatogenesis in the archaic hydrothermal vent bivalve,Bathypecten vulcani,and comparison of spermatozoon ultrastructure with littoral pectinids

Summary

Bathypecten vulcani is considered a relict species from the Paleozoic, based on shell characteristics such as the presence of calcite prisms. To date, it is the only pectinid species reported from hydrothermal ecosystems. Histological and ultrastructural studies show that spermatogenesis is identical to that of littoral pectinids. The spermatozoon has a 2.7 μm long pyriform head and a 40 μm flagellum. The four mitochondria of the mid-piece are about 1.2 μm in diameter. The nucleus contains dense chromatin fibres and possesses a wide, shallow (0.1 μm) anterior fossa and a narrow, deeper (0.2 μm) posterior nuclear fossa. Comparison of the ultrastructural characteristics of the spermatozoon of B. vulcani with those of littoral pectinids shows that they can be used as a diagnostic feature of this species. In particular, its acrosome characters will be a useful complement to the shell characters in the study of the phylogenetic position of this species in relation to other pectinids.