Size heterogeneity of pituitary and plasma prolactin: Effect of chronic estrogen treatment

Pituitary homogenates and plasma from untreated and estrogen treated ovariectomized rats were subjected to gel filtration chromatography and the prolactin in fractions collected between the void and total elution volumes of the columns was determined by radio- immunoassay. Three components of prolactin, identified as “void volume”, “big” and “little” according to increasing elution volumes, were observed in pituitary homogenates of ovariectomized rats. These three components accounted for 4, 11 and 85% of the total prolactin activity respectively. Estrogen treatment of ovariectomized rats increased the total prolactin in the pituitary and also selectively increased the “big” component to 21% of the prolactin activity on the column. A smaller increase was also observed in the “void volume” component. Gel filtration of the plasma obtained from estrogen-treated rats before and during the estrogen-induced afternoon surge of prolactin showed that “little” prolactin was the predominate form being secreted and that the “void volume” and “big” components were also released. The release of the components was not in proportion to that observed in the pituitary and the larger components were released in a nonuniform manner. The “void volume” component appeared in the plasma as the surge began but then disappeared as the “big” component appeared at the peak of the surge. The big component decreased as the surge waned leaving primarily “little” component in plasma. The data indicate (1) that estrogen stimulates the formation of the larger components of prolactin in the pituitary (2) that the types of prolactin released into plasma of estrogen-treated ovariectomized rats is not in proportion to that found in the pituitary and (3) that the heterogeneous forms of prolactin are selectively released into plasma during the prolonged secretory episode of the afternoon surge of prolactin induced by estrogen.     

Rouleaux formation as a measure of the phase separating ability of plasma

The increased erythrocyte sedimentation rate (ESR) occurring in various diseases reflects a change in certain plasma proteins which causes erythrocytes to aggregate into rapidly sedimenting “piles of coins”, or rouleaux. In spite of some 300 years of study, the mechanism of the phenomenon and the adaptive significance, if any, of the change in properties of plasma, remain elusive. One hypothesis on the mechanism is that rouleaugenic agents in plasma act as multivalent “agglomerins”, which react with the erythrocyte surface and cross-link cells. Alternatively, a “phase separation” hypothesis can be derived by analogy with the phase separation of high molecular weight polymers from polymer mixtures at high polymer concentrations. Considering the cell surface to resemble that of a large polymer, it is postulated that there should be a separation of a cell phase from a solution phase in the presence of high concentrations of a high molecular weight polymer. In keeping with the available data, both hypotheses predict that rouleaux formation should increase with increasing polymer size. In addition, the phase separation hypothesis predicts (i) no need for reaction of a rouleaugenic agent with the erythrocyte surface, and (ii) that cells from different species, when mixed in the presence of a rouleaugenic agent, will form independent rouleaux. Current evidence is consistent with both predictions. We suggest that an increased ESR reflects a change in the physical properties of plasma such that particulate material (e.g. viruses, tumour cells), will tend to spontaneously aggregate in regions of stagnant blood flow (such as the sinusoids of the spleen). This change in the physical properties of plasma, tending to favour phase separations, will also favour antigen-antibody and other intermolecular reactions.     

A guide and guard: The many faces of T-cadherin

Cadherins are a superfamily of transmembrane proteins that mediate calcium-dependent intercellular adhesion. T-cadherin (T-cad, H-cadherin or cadherin-13) is an atypical member, lacking transmembrane and cytosolic domains and possessing a glycosylphosphatidylinositol moiety that anchors T-cadherin to the plasma membrane. This article reviews current knowledge on the biomolecular characteristics of T-cadherin, its expression and function in different tissues in health and disease and its mechanisms of signal transduction. The structural characteristics of T-cadherin protein predict that it is unlikely to function as a “true” adhesion molecule in vivo. Studies from different fields suggest that it may act rather as a signalling receptor participating in recognition of the environment and regulation of cell motility, proliferation and phenotype. Cellular expression levels of T-cadherin in various tissues frequently correlate (be it negatively or positively) with the proliferative potential of the cells. Loss- and gain-of-function studies demonstrate the ability of T-cadherin to modulate cell motility and growth. Gathering evidence suggests that the “functional predestination” of T-cadherin is in control of tissue architecture through “guiding” navigation of moving structures, segregating functional tissue compartments and “guarding” integrity of functionally connected tissue layers.     

Behavior of males in a reproductive aggregation of the banded demoiselle Calopteryx splendens (Insecta, Odonata)

The view according to which damselfly males practice two alternative reproductive tactics of access to females is critically discussed. It is widely accepted that some males (“territorial” ones) have priority as potential female partners, while others (“sneakers” or “wanderers”) are incapable of retaining an individual territory. They have a chance of mating only by intruding briefly into the area defended by a “territorial” male when a female is present there. Thus, the tactics of a “territorial” male consists in waiting for a female in its territory and copulating with it “by agreement,” whereas non-territorial males resort to forced copulations. By observation of individually marked males (48 out of 118) it was shown that every male could be regarded as “territorial” during a certain period and as a “wanderer” before and after it. Thus, no correlation between the modes of space use by a male (residence/mobility) and the characters of its external morphology and/or signal behavior appears to be possible in principle. According to the data obtained, a more plausible explanation is that the female chooses not the male but the best area for oviposition. In addition, it was ascertained that adherence to forced copulations cannot constitute successful “tactics” since they rarely result in insemination, neither by “territorial” nor “non-territorial” males. In other words, we are dealing not with certain alternative tactics (i.e., specialized adaptive mechanisms that have evolved in the species) but simply with the results of different sets of circumstances at a given moment.     

Is the “Ecological Fallacy” a Fallacy?

Ecological studies of health effects due to agent exposure are generally considered to be a blunt instrument of scientific investigation, unfit to determine the “true” exposure-effect relationship for an agent. Based on this widely accepted tenet, ecological studies of the correlation between the local air concentration of radon and the local lung cancer mortality as measured by Cohen have been criticized as being subject to the “Ecological Fallacy” and thus producing invalid risk data. Here we discuss the data that a risk assessment needs as a minimum requirement for making a valid risk estimate. The examination of these data and a “thought experiment” show that it is Cohen's raw ecological data, uncorrected for population characteristic factors, which are the proper data for a risk assessment. Consequently, the “true” exposure-effect relationship is less and less important the more population characteristic factors are identified and the larger they are. This reversal of the usual argument is due to our approach: Here, the prediction of the health effects in an exposed population is of primary importance, not the shape of the “true” exposure-effect relationship. The results derived in this paper hold for ecological studies of any agent causing any health or other effect.     

The limited depletion of cholesterol from erythrocyte membranes on treatment with incubated plasma

About 35% of the cholesterol of human erythrocyte membranes can be removed by the “preincubated plasma” technique (Murphy, J.R. (1962) J. Lab. Clin. Med. 60, 86–109), in which erythrocytes are extracted with plasma that has been preincubated to esterify a portion of its lipoprotein cholesterol. The limitation on the cholesterol depletion is shown not to be a result of insufficient plasma capacity to take up additional cholesterol or of changes in the plasma during the extraction.The maximum cholesterol depletion from “ghosts” was the same as that from whole cells. “Inside-out” membrane vesicles (Steck, T.L. (1974) in Methods in Membrane Biology (Korn, E., ed.), Vol. 2, pp. 245–281) were utilized to determine if the limitation to cholesterol depletion is a result of the remaining cholesterol being 1located at the membrane inner surface and therefore not accessible to the plasma. No further cholesterol depletion occurred when “inside-out” vesicles, prepared from erythrocytes which were depleted of cholesterol by the usual method, were extracted. Also, “inside-out” vesicles prepared from untreated erythrocytes gave the same cholesterol depletion as is usually attained.The maximal cholesterol depletion was unaffected by a number of modifications of the extracting preincubated plasma: addition of lysolecithin or albumin, dialysis against isotonic buffer, and variation in pH of the preincubated plasma from 6.0 to 9.0.It is concluded that the limitation on the cholesterol depletion is a result of a firm binding of the remaining cholesterol.     

Reduced models of the dynamics of light impurity stripping

“Closed” and “open” reduced models of two or three most abundant light impurity ions in an optically thin hydrogen plasma are considered. The models are shown to satisfactorily describe the average ion charge and radiative losses within a wide range of parameters typical of laboratory and astrophysical plasmas, including the case when the relaxation time of the impurity distribution over ionization states is comparable to or longer than the characteristic times of the most important dynamic processes. The potentialities of the models are demonstrated using the carbon impurity as an example. The models proposed make it possible to analytically study the dynamics of a radiating plasma, obtain qualitatively new results, and significantly reduce the computation time when solving complicated self-consistent dynamical problems.     

Characteristics of discharge disruptions in the T-10 tokamak

The results of experimental studies of discharge disruptions in the T-10 tokamak at the limiting plasma density are presented. On the basis of measurements of the generated soft X-ray emission, for a group of “slow” disruptions, the dynamics of the magnetic configuration of the central part of the plasma column is studied and the possible role of the m/n = 1/1 mode in the excitation of predisruptions or the final stage of disruption is analyzed. It is shown that the characteristics of plasma electron cooling in predisruptions correspond to those of electron cooling upon pellet injection into T-10 and in discharge predisruptions occurring in regimes with the “quiet mode.” It is found that, in the latter case, the reason for predisruptions and fast electron cooling in the plasma core is the instability of the m/n = 2/1 mode, its spontaneous spatial reconstruction, and the generation of a “cooling wave” during this process. Measurements of the electron temperature (determined from the plasma radiation intensity at the second electron cyclotron harmonic) in the zone of the m/n = 2/1 mode have shown that the transformation of the m/n = 2/1 mode leads to the excitation of predisruptions and the final phase of disruption not only in regimes with the “quiet mode,” but also in disruptions of ordinary ohmic discharges. The experimental results obtained in this work make it possible to determine the scenario of the development of “slow” discharge disruptions in the T-10 tokamak at the limiting plasma density.     

PIP1 aquaporins,sterols, and osmotic water permeability of plasma membranes from etiolated pea seedlings

Plasma membrane isolated from microsomal membranes of pea seedling root and shoot cells by means of aqueous two-phase polymer system was separated by flotation in discontinuous OptiPrep gradient into “light” (≤1.146 g/cm³) and “heavy” (≥1.146 g/cm³) fractions. Osmotic water permeability of plasma membrane and its two fractions was investigated by inducing transmembrane osmotic gradient on the vesicle membrane and recording the kinetics of vesicle osmotic shrinkage by the stopped-flow method. Rate constants of osmotic shrinkage and coefficients of osmotic water permeability of the membranes were estimated on the basis of the kinetic curve approximation by exponential dependencies and using electron microscope data on vesicles sizes. In plasma membrane and its fractions the content of sterols and PIP1 aquaporins was determined. It was found that in “light” PM fractions from both roots and shoots the content of PIP1 aquaporins and sterols was higher and the osmotic water permeability coefficient was lower than in “heavy” fractions of plasma membrane. The results indicate that plasma membrane of roots and shoots is heterogeneous in osmotic water permeability. This heterogeneity may be related with the presence of microdomains with different content of aquaporins and sterols in the membrane.     

Weakly ionized plasma in a supersonic plasma flow

The structure of the ion acoustic precursor of a shock wave in a weakly ionized collision-dominated plasma is studied numerically. It is shown that the simultaneous action of the nonlinearity, dispersion, and dissipation leads to the formation of an oscillating profile of the ion density in the precursor. There exist regimes in which the charged-particle density decreases abruptly and simultaneously the number of maxima in its profile within the precursor becomes smaller as the shock wave velocity increases in a jumplike manner. This effect is analogous to the corresponding hydrodynamic effect in narrow shallow channels (the “Houston's horse” effect). In the stage preceding this jumplike process, local regions may appear in which the degree of plasma ionization is elevated. Such plasma “bunches” give rise to the strong reverse action of the charged particles on the neutral component, resulting in the “stretching” of the precursor. This phenomenon is resonant in character and occurs in a narrow range of shock wave velocities.     

A Stochastic Model for Estimating Adolescent Sterility Among Married Women

In this paper a stochastic model is presented for the time to the first conception of a cohort of married women. By identifying three states “adolescent sterility”, “ovulation” and “conceived”, into which the women can be placed, the model incorporates individual differences for the women in the “adolescent sterility” state which allow for the individual characteristics to affect the conversion of these women into the “ovulation” state. Using straightforward probabilistic arguments it is shown that the model provides a close fit to recently published data, compares favorably with previously published models on the same subject and it is useful for planning purposes in predicting future developments.     

A mathematical model for the batch reactor kinetics of algae growth

A mathematical model based on the Einstein law of photochemical equivalence is proposed to describe the batch growth of unicellular algae. The model was applied in an integrated form to cell concentration versus growth time data taken over an extended range of cell concentrations which include both the regions of “exponential” and “linear” growth. It is shown that a certain function of cell concentration contained in the integrated form of the model is linearly dependent on the growth time over both the “exponential” and “linear” growth regions.     

Identification and classification of cut-flower “Huangyinghua”using DNA marker techniques

rch Laboratory, Nanjing Agricultural University, Nanjing 210095, China) Abstract “Huangyinghua” is a popular cut-flower in China, but it is unclear as to whether “Huangyinghua” is an invasive Solidago canadensis or not. The genetic relationship of a total of 45 samples of “Huangyinghua” with S. canadensis, and S. decurrens were investigated using AFLP technique so as to determine the identity of “Huangyinghua”. Genomic DNA was digested with EcoRI and MseI enzymes and amplified with six E+3 and M+3 primer combinations. AFLP analysis produced 661 endonucleotide discernable bands, of which 639 (96.61%) were polymorphic. Cluster analysis through using UPGMA method indicated that “Huangyinghua” and S. canadensis were clustered into the same group that was different from S. decurrens. Sequence analysis based on the ITS regions showed that their sequences of 5.8S rDNA were the same, and the differences were found only in the ITS1 and ITS2 regions. ITS phylogenetic trees of the tested samples and closely-related species were reconstructed based on our sequence data in combination with those from GenBank. Based on the trees, “Huangyinghua” was found to belong to S. canadensis complex, but not to S. decurrens. Moreover, it was found that there were considerable genetic variation in both “Huangyinghua” and S. canadensis. Therefore, the cut-flower “Huangyinghua” may be invasive, and proper measures should be taken to control the further spread of its propagules.     

基于中华鲟繁殖群体数量的长江中、下游生态环境考核指标

繁殖群体数量是中华鲟能否成功繁殖的重要影响因子, 建议作为长江生态考核的重要评价指标。根据重要种群参数和历史数据, 基于稳态转换理论和方法, 确定中华鲟繁殖群体数量指标的评估基准值和等级, 670尾以上为“优”、400—670尾为“良”、200—400尾为“中”、50—200尾为“差”、50尾以下为“极差”。水声学探测结果显示, 1998—2001年中华鲟繁殖群体数量指标评级为“良”; 2004—2012年三峡工程蓄水后至向家坝蓄水前评级为“中”; 2013—2020年评级为“极差”。为了复壮中华鲟野生种群, 建议修复葛洲坝下中华鲟产卵场功能, 大规模放流性成熟亲鱼和大规格个体, 建立国家级中华鲟保育中心。     

Logical-Semantic Analysis and the Development of L.S. Vygotsky's Ideas About “Units” and “Elements” of Psychological Systems

Based on an analysis of L.S. Vygotsky's concepts of “units” and “elements” of psychological systems, this article highlights five of their attributes. It shows that these attributes are logically symmetrical, since in their wording they can be converted into one another by negation or by replacing some words with their opposites. This suggests that the concepts of the “unit” and “element” of a system are different poles of one theoretical construct of the activity of human psychology. Thus methods for the study of psychological systems by breaking them down into elements or by separating them into units can be seen as complementary. The article describes differences among the concepts of “unit,” “minimal unit,” and “cell” of a psychological system. It reviews several problems that are solvable using the “method of units,” as well as some concepts of the theory of psychological systems that are understood as holistic, conceptual, and active processes and/or results of human interaction with the world. Among the examples of such systems are “systems of psychological functions” (according to Vygotsky), as well as separate activities (according to A.N. Leontiev), human actions and operations (interactions with the world on the level of objects and mental or physical means). The “component” of a psychological system is defined as any “something” that in some sense belongs to or is included in human interaction with the world. A component that belongs to the system is called an “element” of it, but a component that is included in the functioning and development of the system is called a “part” of it. The article presents the mathematical and psychological foundation of these definitions. It identifies and discusses the substantial (independently existing) components of psychological systems and their attributes (properties and conditions). It describes the relationships between them using the bipolar theoretical constructs “part-element” and “substantial-attributive” component of a system.     

Marked Point Process: Using Correlation Functions to Explore a Spatial Data Set

The relationship between the locations of the clumps of sprouts, some morphological characteristics of the clumps and the local soil environment in an old sweet chestnut coppice are studied. The theory of marked point process, which has not yet been used extensively in forestry studies, is shown to be adequate for the analysis of this type of spatial data. The marks correspond to morphological characteristics of the clumps: “diameter”, “number of sprouts”, “height at one year”, and “height at three years”. Several covariance functions are described which give a method for exploring the spatial relationships within the stand. Some of these functions are introduced for the first time in an actual statistical analysis. By using these functions, it is shown that the clumps are regularly distributed. The variables “diameter” and “number of sprouts” are strongly spatially negatively correlated, whereas the heights are slightly or not correlated. By categorising the individuals according to the mark values, it is shown that the small clumps tended to be aggregated in the gaps between medium and large clumps. Values of heights in the ties of the distribution are related as well as their spatial correlation to the local soil environment.