p53蛋白在周期调节蛋白A1变异引起的雄性小鼠生殖细胞凋亡中的作用

为研究p5 3蛋白在周期调节蛋白A1(cyclinA1)变异引起的雄性小鼠生殖细胞凋亡中的作用 ,以p5 3基因敲除的小鼠和周期调节蛋白A1基因敲除的小鼠杂交 ,获取同胎生单基因变异和双基因同时变异的雄性后代共 4组 12只 .比较它们的性腺和生殖细胞发育 ,并用TUNEL染色法观察和比较生殖细胞的凋亡情况 .在睾丸最大横切面上观察到 :周期调节蛋白A1变异组凋亡细胞最多 (348± 10 4个 ) ,明显高于p5 3 周期调节蛋白A1双基因变异组 (12 1± 38个 ) ,t=3 2 5 79,P =0 0 4 72 .p5 3变异组凋亡细胞最少 (45± 2 4个 ) ,配对t检验显示有非常显著性差异 ,t=8 4 0 13,P =0 0 0 35 .这一研究结果提示 ,p5 3基因可能在雄性生殖细胞的发育中起监视作用 ,并在周期调节蛋白A1变异引起发育异常时启动p5 3途径造成异常细胞的凋亡 .     

Activity of Plasma Membrane H<Superscript>+</Superscript>-ATPase in Coleoptile Cells during Development of Maize Seedlings

Hydrolytic activities of the H⁺-ATPase were compared for plasma membrane fractions isolated from coleoptile cells of 3-, 4-, and 5-day-old etiolated maize seedlings. The membrane preparations obtained by differential centrifugation were additionally purified in the gradient of sucrose density and in the polyethylene glycol-dextran system. The highest level of ATP-hydrolyzing activity was observed in the plasmalemma fraction obtained from 4-day-old seedlings. The pattern of age-dependent changes in H⁺-ATPase activity of the plasma membranes was clearly different from the monotonic deceleration of coleoptile cell elongation in the period examined. It is supposed that changes in ATPase activity reflect different regulatory roles of this principal ion-transporting enzyme of the plasma membrane at the stage of cell elongation and at a later developmental stage when the coleoptile has completed its physiological function.__________Translated from Fiziologiya Rastenii, Vol. 52, No. 4, 2005, pp. 566–572.Original Russian Text Copyright © 2005 by Rudashevskaya, Kirpichnikova, Shishova.     

Effect of Light Quality on Nitrogen Metabolism of Radish Plants

The long-term action of blue or red light on nitrogen metabolism was studied in radish (Raphanus sativus L.) plants. The potential activity of nitrate reductase (NR) in vivo and its maximum activity in vitro, the content of soluble protein and free amino acids were determined in the course of the growth of a third leaf of radish plants. The effect of light quality on NR activity was found to depend significantly on the stage of leaf development. Blue light (BL) stimulated NR activity in leaves, when their areas were about 11–13% of the fully developed leaves. The efficiency of red light (RL) was significantly lower, because the maximum NR activity was observed in the leaves developed to the stage, when their areas were 38–40% of the final one. The comparative analysis of the pool of free amino acids in expanding leaves of BL- or RL-grown plants revealed significant changes in the contents of individual amino acids. Despite a higher accumulation of two amino acids in the leaves of BL-grown plants, namely, Asp (27% as compared to 13–16% in the RL-grown leaves) and Gly (5% against 2.5% in RL-grown leaves), the BL-grown leaves also demonstrated a significant decrease in Ala (10% as compared to 23% in the RL-grown leaves) and some decrease in the amounts of Ser and Gly. The content of soluble protein in a juvenile BL-grown leaf was observed to decrease gradually during leaf development. However, the protein content in the BL-grown leaf was always higher than in the RL-grown leaf of the same age. We concluded that the photoregulatory action of BL on NR activity determined the different rates of nitrogen assimilation in BL- and RL-grown plants.__________Translated from Fiziologiya Rastenii, Vol. 52, No. 3, 2005, pp. 349–356.Original Russian Text Copyright © 2005 by Maevskaya, Bukhov.     

The Role of Plastids and Assimilate Transport System in the Control of Plant Development

Phylogenetic and ontogenetic relationships between the plastids, cell endoplasmic reticulum, and plant transport communication have been reviewed. The initiating role of plastids (endosymbionts) in the origin of endoplasmic reticulum (buffer zone of endosymbiogenesis) has been shown, as well as a similar role of endoplasmic reticulum in the development of transport communication of xylem and phloem. Plastids, sugars and transport system for their distribution can be interpreted as leading sections in the mechanism of developmental control: gene expression of nuclear genome and genome of organelles, cell and tissue differentiation, and plant morphogenesis. The conflict between the bulk of plant genome and low percentage of its realization is explained as a result of limitation of the nuclear genome realization by plastid genome. The concept of development as applied to plant ontogenesis has been critically analyzed. The possibilities of the concept correction by with the help of symbiogenetic hypothesis are discussed.__________Translated from Ontogenez, Vol. 36, No. 3, 2005, pp. 165–181.Original Russian Text Copyright © 2005 by Gamalei.     

Epistemology of living organisms in Aristotle’s philosophy

Summary For Aristotle, living entities are exemplars of substance being. This means that they show a unity of matter and form on the one hand and of potency and act on the other, in contrast to the duality shown in these respects by accidental beings, exemplified by artefacts. An animal, although composed of the same elements (arche) considered by presocratic philosophers, is defined as an individual unity, generated and maintained by an organisation which relates its parts in a hierarchical and functional way. Crucial to his understanding of the living is the hierarchy in which each part is defined by fitness to a function, as an instrument (organon), performing within the whole. The whole being is also an instrument (an organism) for a specific kind of life, which actualises an internal and specific principle (psuche). Both the regularity of appearance of each organism and its fitness to a specific function justify the introduction, in addition to the study of necessary causes, of an additional way of analysis in terms of hypothetical necessities, or necessary conditions for a goal to be attained. Fitness to a function and regularity of appearance make necessary the analysis not just of the elementary components, but of another principle (eidos, form) which defines a structure directed to a goal. While for accidental beings matter can survive their destruction, the corruption (pthora) of living entities causes the disruption of the entire unity of matter and form. Living entities, both as matter and form, show therefore a temporal limitation in being generated and corrupted, although they persist as specific forms since they generate offspring which regularly share their differential characteristics defined in their form. After reviewing recent interpretations of Aristotle’s biological writings, I will suggest the usefulness of this conceptual framework to analyse some problems approached by current developmental biology.     

Male behaviour over the season in a wild population of the field cricket Gryllus campestris L.

Abstract.  1. Cricket model systems have greatly enhanced our knowledge about mate choice and sexual selection. However, no studies exist that take seasonal dynamics into account and that follow individual males over the complete adult stage in the wild. In the present study, all adult field crickets ( Gryllus campestris L.) were individually marked and measured in a population in central Germany and their behaviour was followed over their life from May to July 2000.
2. The population reached a maximum of 108 males within 10 days and continuously declined thereafter. Daily mortality was positively correlated with burrow-changing activity, which was highest at high mean temperatures. Median burrow occupation time was short at 1 day but males stayed up to 34 days in one burrow. Heavy males stayed longer in burrows and achieved a higher age.
3.  Male displacement was on average 2.8 m per day and up to 284 m during their life. Displacement and lifespan were negatively correlated.
4. Burrows were highly aggregated at the meadow in areas of vegetation cover <85%. Aggregation of males increased with advancing season and declining population size. Consequently, nearest-neighbour distances remained stable at 5 m until the 50th day of the study.
5. About half of the 159 detected matings occurred 4–6 h after sunrise. An increased mating frequency was observed between the 30th and 50th day after adult moult.     

Appearance of ocular electrical responses during development of cavernicolous and epigaeic opilionids (Arachnida)

The appearance of the electroretinogram was established during the development of two species of opilionids, an epigaeic species, Pachylus chilensis, and a cavernicolous one, Ischyropsalis luteipes. In nymphs and adults of the two species, electroretinograms of about the same amplitude can be recorded. During embryonic and larval development they are quite different. In Ischyropsalis luteipes, it is impossible to record an electrical response before hatching. In Pachylus chilensis on the other hand an initial inconstant and very small response occurs from the 50th hour of development of the retina and can always be recorded from the 72nd hour. In older embryos, the response has a progressively greater amplitude, but remains a simple negative wave. On the tenth day, when the first synaptic relays appear, the electroretinogram takes the shape of that of the adult. Given that transmission electronic microscopy cannot detect differences between the microvilli of these two species, it is tempting to compare Ischyropsalis luteipes lack of response with that of the mutant norp A of Drosophila melanogaster in which transmission electron microscopy shows no marked difference, whereas freeze-etching shows a very low number of intramembranous particles.