大鼠离体乳头肌收缩末期张力—长度关系的曲线性

大鼠离体左室乳头肌固定于最适初长位,逐步递减“后荷”获得一系列等张收缩的张力、长度缩短程度和速度。结果发现:(1)收缩末期张力-长度关系(ESTLR)为指数曲线,回归方程 T=ar~(-bL)-K 拟合的优度明显高于线性方程拟合的优度(P<0.001),其中 a,k 分别代表总张力和静息张力,b 为曲线的弯曲度;(2)在高钙(4mmol/L)或去甲肾上腺素(NE10~(-6)mol/L)作用下,ESTLR 右上移位,a,b 和无张力缩短速度 L_O 均增大(P均<0.01),尤以高钙时的变化更明显,(3)NE 使张力-速度曲线的右上移位比高钙显著。这提示大鼠离体心肌的 ESTLR 呈非线性特征,参数 a,b 及长度轴截距 L_O 对收缩强度的变化敏感,但对收缩速度改变的敏感性可能比经典的力学指标低。     

Purification and characterization of a heat-stable enterotoxin of Vibrio mimicus

A heat-stable enterotoxin produced by Vibrio mimicus (VM-ST) was studied. VM-ST was purified from a culture supernatant of V. mimicus strain AQ-0915 by ammonium sulfate fractionation, hydroxyapatite treatment, ethanol extraction, column chromatography on both SP-Sephadex C-50 and DEAE-Sephadex A-25, and HPLC, and the recovery rate was about 15%. Purified VM-ST was heat-stable. VM-ST activity was cross-neutralized by anti-STh antiserum. The amino acid composition of the purified VM-ST was determined 17 amino acid residues in the following sequence: Ile-Asp-Cys-Cys-Glu-Ile-Cys-Cys-Asn-Pro-Ala-Cys-Phe-Gly-Cys-Leu-Asn. This composition and sequence were identical to those of V. cholerae non-O1-ST. These results clearly demonstrate the production of a characteristic VM-ST by V. mimicus.     

Issues related to mineralized tissue biology in human evolutionary research

This comunication has two primary aims concerned with mineralized tissue biology (e.g. hard tissue biology of bone and tooth) research in human evolutionary studies: First, to introduce the literature and the methods (at the time of this symposium) so that one has an idea of the nature of this research and where one can go for details of the methodologies, etc; Second — and of primary concern here — to discuss issues that have come to light as a result of these studies mainly because of its recent beginnings as a subfield within paleoanthropology. Issues related to skeletal studies include; 1) whether different cortical surface pattens and bone tissue types influence the appearance and interpretation of bone growth activity states; 2) if SEM analyses of cortical surfaces in fossil hominids allow one to construct meaningful representations of remodeling patterns; 3) whether these representations can be used in phylogenetic arguments; and 4) how intraspecific variability would affect these issues. Issues related to dental studies include: 1) the relationship between the rate and pattern of eraly hominid dental development; 2) experimental support for the calibration of eraly hominid dental developmental rates; and 3) whether replica techniques are suitable for microanatomical studies of these sorts.     

Serum protein polymorphisms (HP,GC, PI) in Muslims and Bodhs of Jammu and Kashmir,India

Two population groups of Jammu and Kashmir (India) — Muslims and Bodhs-have been typed for haptoglobin and for CG and PI subtype polymorphisms. The allele frequencies do not show significant differences between these two populations. HP and GC allele frequencies of Bodhs and Muslims differ considerably from with that observed in other North Indian populations. The PI allele frequencies of Bohds and Muslims differ considerably from those found in other Indian populations and are more similar to Mongoloid ones.     

Stature variation in the British American Colonies: French and Indian War records, 1755-1763

Personnel records kept by military units of American colonials during the French and Indian War (1755-1763) are analyzed for relationships between environmental factors and stature. A robust American economy and direct access to high-quality food were apparently critical to tallness of this white American male sample. American-born men were taller at all ages than those who had migrated from Europe. January temperatures, rural versus urban birth, and ethnicity also showed stature relationships within the American-born group; thermal effects were by far the strongest of the non-nutritional factors.     

Observations on the relation between phytoplankton diversity and environmental factors in the Vaal River at Balkfontein,South Africa

The relationship between specific environmental factors as independent variables and temporal changes in phytoplankton community structure in the Vaal River (a turbid system) during 1984 was investigated by employing different diversity indices. Temporal changes in community structure reflected temporal changes in certain environmental factors. Phytoplankton diversity, measured with Shannon-Wie H' and Hurlbert PIE indices, was related firstly to discharge and discharge derived variables (such as SO₄, Si, N and P loading) and secondly to turbidity derived variables (such as euphotic zone depth). Discharge appears to be of prime importance in affecting diversity. Observations were made that shed new light on conditions contributing to the development of an August peak (dominated by Stephanodiscus hantzschii fo. tenuis and Micractinium pusillum) in phytoplankton concentration. Increased environmental stress may reduce the number of sensitive species, thus reducing interspecific competition between tolerant species which could then exploit the — for them — more favourable conditions resulting in an increase in their numbers to peak concentrations.     

The influence of invertebrates on the breakdown ofPotamogeton pectinatus L. in a coastal marina (Zandvlei,South Africa)

The influence of invertebrates upon the decomposition ofPotamogeton pectinatus L. in a coastal Marina system was examined over 112 days using litter bags. Invertebrate inclusion bags (2 mm mesh, 5 mm holes) registered a dry mass loss of 1% d^–1, while exclusion litter bags (80 µm mesh) produced a 0.4% mass loss d^–1 (a 2.5 fold difference). Losses of ash and N from inclusion bags were greater than those from exclusion bags (p < 0.05). There was a three fold difference between the two treatments in the time taken for litter to breakdown to half the initial stock: T_1/2 for inclusion bags = 43 d, exclusion bags = 130 d. In both treatments, minerals showed an expected rapid loss, due to leaching, with a subsequent slow increase relative to the dry material remaining. A total of nine invertebrate taxa was recorded from inclusion bags, with a peak biomass of 64 mg g^–1 dry massPotamogeton bag^–1 reached at 64 days after immersion. Grazing amphipods,Melita zeylanica Stebbing andAustrochiltonia subtenuis (Barnard), numerically dominated the litter bag fauna, whileM. zeylanica and nymphs of the zygopteran predatorIschnura senegalensis (Rambur) formed most of the biomass. Scanning Electron Microscopy indicated heavy grazing of micro-organisms by invertebrates, with major qualitative differences occurring 112 days after immersion. Invertebrates significantly accelerated the rate of litter breakdown through their feeding activities, assisting fragmentation and thus contributing to plant losses and also by increasing the surface area for microbial colonisation and attack.     

Suivi pluriannuel du peuplement à Abra alba dans la partie méridionale de la Mer du Nord (région de Dunkerque-France)

The Abra alba community is considered as a faunistical unity well established on coastal areas of North Sea. This community shows, since several years, very important recruitments of certain species. Since 1978, recruitments of Abra alba, Tellina fabula, Phyllodoce (Anaïtides) mucosa, Lagis koreni or Lanice conchilega have been observed. However these demographic phenomena does not affect the structure of the community, which shows, through rank-frequency diagrams, the characteristic of a mature population, principally constituted of 7 species.An annual cycle study shows a succession of recruitments of several species. A correspondance factorial analysis was realised from grain size datas as well as abundances of 18 main species. This analysis shows an annual cycle which seems to be linked to the clay part. Maximal values of clay part appears in summer and minimal values at the end of winter or early springtime.The hydrological parameters studied, allowed to make the difference between external factors (continental contributions, phytoplanctonic activity etc...) and benthic activity.

     

Classification of types of ontogenetic reproduction

The object of this paper is to present an original classification of ontogenetic reproduction. The main general criterion used is the degree and type of phylogenetic differentiation. In relation to this criterion, criteria are given for the classification of the fundamental types of ontogenetic reproduction and for the classification of the types of ontogenetic generation cycles. Between the fundamental types of ontogenetic reproduction and the types of ontogenetic generation cycles there is a hierarchical relationship which shows that the former are components of the latter. Between the well-defined types of ontogenetic reproduction there exist many intermediate types.