Evidence for constraint on species coexistence in vegetation of the Park Grass experiment

Repeated patterns, of a type that would be expected to result from limitations to species coexistence (i.e. assembly rules) were sought in the Park Grass experiment. This classical grassland experiment was sampled in two years, using replicated biomass samples. Variance in a number of measures was examined, and compared to the variance expected under appropriate null models, the latter based on assumptions of no interactions between species. In each case, an assembly rule would result in low variance. Examining variance in species richness between quadrats within a treatment, there was no indication of constraint on species co-occurrences; variance in richness was actually greater than expected under the null model, attributable to environmental variation or perhaps positive interactions between species. However, there was control on biomass, evidenced by variance in total biomass (i.e. over all species) within a treatment being significantly lower than expected under the null model. There was no indication of community structure based on guilds (i.e. functional types). Although there was in 1991 some, non-significant, indication of a constant proportion of species from the legume guild, there was no sign of such an effect in 1992. Searches for intrinsic guilds failed to converge. There was no indication at all of constancy in the proportional representation of guilds by biomass. Thus, there is good evidence for competitive control on plant growth, but none for control of species occurrences. There is no convincing evidence for guild structure in this community at the scale sampled. Possible conflict is discussed between the existence of evidence for temporal stability but the absence of evidence for spatial uniformity. It is concluded that most of the mechanisms proposed for temporal stability will not necessarily lead to control on spatial variation. For many mechanisms, this would depend on the spatial scale examined.     

达斡尔族成人的体格,体型及半个多世纪来的变化

对内蒙古自治区莫力达瓦族３５３名（男１８７,女１６６）２０－６０岁达斡尔族进行了活体观察与测量,总结了达斡尔族的体格特征和类型。并在城乡之间和与半个世纪以前同一地区达斡尔族的体质资料之间进行了比较。     

蛇胆祛痰作用的实验研究

用２组小鼠,每组１０只。实验组用蛇胆酒灌胃,对照组用生理盐水灌胃,均以气管内酚红排泄法观察。结果示,酚红排泄量实验组比对照组明显为高。说明蛇胆确有增加小鼠气管分泌,稀释痰液的作用     

硬脂酸修饰超氧化物歧化酶的制备及其性质研究

报道了一种修饰ＳＯＤ的方法。所得硬脂酸修饰ＳＯＤ比活力为每毫克蛋白１００００单位,经鉴定已达均一程度。测得其分子量为３５０００．修饰ＳＯＤ和天然ＳＯＤ在紫外光区的最大吸收均在２６５ｎｍ。修饰ＳＯＤ对温度、ｐＨ、蛋白酶水解的稳定性比天然ＳＯＤ增强,且免疫原性消除。在低浓度的某些有机介质中活性比在水中高。     

人重组GM－CSF／HAS－D3嵌合蛋白（GM－HSA）在大肠杆菌中的表达及其产物稳定性的研究

将人粒细胞－巨噬细胞集落刺激因子（ＧＭ－ＣＳＦ）和人血清白蛋白第三功能区（ＨＡＳ－Ｄ３）的基因串联后,在Ｅ．ｃｏｌｉ中获高效表达,表达量占菌体蛋白的３２．６％．利用ＴＦ－１体外细胞活性测定表明,ＧＭ－ＨＳＡ的活性单位为１．０４×１０~６Ｕ／ｍｇ,虽然其比活性低于ＧＭ－ＣＳＦ,但比后者具有更高的体外热稳定性和储藏稳定性．     

Stream-dwelling insects and extremely low frequency electromagnetic fields: a ten-year study

Changes in the structure of benthic insect communities at an experimental site and at a reference site in the Ford River, Michigan were monitored over a 10-year period to determine whether extremely low frequency electromagnetic fields (ELF) affected those communities. Five of 10 biotic parameters monitored are presented: taxon evenness (J), richness (S), numerical dominance of chironomids, and total insect mass. Data were separated into three seasons because coefficient of variation values were lower in the summer than in the spring and fall. Two-way ANOVA tests for the biotic variables were often significantly different between sites and among years, but the interaction terms were less frequently significant. Biotic parameters were regressed against stream discharge, water temperatures, years, and ELF cumulative ground field exposures. At the experimental site, discharge accounted for more variation than did water temperature or years for all biotic parameters except chironomid numerical dominance in the fall. Intervention analyses, using the B.A.C.I parametric or the R.I.A non-parametric showed significant differences in three of 15 cases; namely, for the highly varying chironomid numerical dominance values in the spring and fall and for the low varying total insect mass values in the summer. For those tests, the Before Impact period spanned April 1984 through May 1986. The After Impact period (full ELF power) spanned June 1989 through August 1993. Trend analysis for total insect mass at the experimental site in the summer showed discharge to be more important than water temperatures or ELF ground field exposures. Natural physical factors appear to be more important than the anthropogenic ELF fields in accounting for seasonal and yearly changes in the community.     

X-ray structure of recombinant horse L-chain apoferritin at 2.0 Å resolution: implications for stability and function

The X-ray structure of recombinant horse L-chain (rL) apoferritin, solved at 2.0?Å resolution with a final R factor of 17.9%, gives evidence that the residue at position 93 in the sequence is a proline and not a leucine, as found in earlier sequencing studies. The structure is isomorphous with other apoferritin structures, and we thus draw particular attention to those structural features which can be related to the stability and function of the protein. Analysis of hydrogen bonding and salt bridge interactions shows that dimers and tetramers are the most stable molecular entities within the protein shell: a result confirming earlier biophysical experiments. The stability of horse rL apoferritin to both dissociation into subunits at acidic pH values and to complete unfolding in guanidine chloride solutions is compared with that of other apoferritins. This emphasizes the role played by the salt bridge in the stability of this protein family. The horse rL apoferritin is significantly more resistant to denaturation than horse spleen ferritin, which in turn is more resistant than any human rH apoferritins, even those for which a salt bridge is restored. Finally, this structure determination not only establishes that a preformed pocket exists in L-chain apoferritin, at a site known to be able to bind porphyrin, but also underlines the particular function of a cluster of glutamic acids (E53, E56, E57 and E60) located at the entrance of this porphyrin-binding pocket.     

Evaluation of PAPNET-assisted cervical rescreening

Evaluation of PAPNET-assisted cervical rescreening
We have compared the results of targeted manual rescreening of 1211 randomly selected smears with the results of PAPNET-assisted rescreening of 1613 cervical smears, containing at least 6.3% low-grade squamous intraepithelial lesion (SIL). PAPNET diagnosis and the targeted rescreening diagnosis were compared with the initial report, issued on the corresponding smear. Reproducibility scores for inadequacy, presence of endocervical and endometrial cells, specific infections and squamous cell abnormalities were determined. The reproducibility scores for the diagnosis of inadequate smears and specific infections were lower with the PAPNET-assisted rescreening. The detection of squamous cell abnormalities was excellent for both methods (>0.95), with a higher detection rate for false-negative smears with the PAPNET testing system.     

Axial loading induces rotation of the proximal carpal row bones around unique screw-displacement axes

The changes in carpal bone alignment secondary to the aplication of an axial compressive load through the major wrist motor tendons while the wrist is kept in neutral position (isometric loading) have been investigated on 13 fresh cadaver specimens using a biplanar radiographic method of kinematic analysis. The scaphoid, lunate and triquetrum rotate an average of 5.1, 4.2 and 3.8°, respectively, around different ‘screw displacement axes’, all implying flexion, radial deviation and supination. Based on these findings, a new interpretation of the mechanism by which the wrist remains stable under physiologic loads is provided.     

Variability of genetic serum protein markers in Austria

Haptoglobin (HP), transferrin (TF), group specific component (GC) and protease inhibitor (PI) polymorphisms were studied in a population sample (n=272) from Tyrol (Austria). Comparing the allele frequencies of these polymorphic serum protein systems with those reported on other Austrian population samples some heterogeneity in the regional distribution of allele frequencies was seen, especially concerning the GC system. The reasons for that may be due to different historical backgrounds in the various regions of Austria.