五唇兰胚胎发生与几种同工酶变化的相关性研究

用聚丙烯酰胺凝胶电泳的方法研究了五唇兰（Phaius tankervilliae Lindl.）授粉后合子形成过程中同工酶的变化情况。结果发现,有些位点在这一发育过程中始终表达,如Est-2、Est-4、AAT-3;球形胚形成时,Est-1、Est-3消失;Pgi-3只在合子形成时出现。同工酶位点的变化说明五唇兰受精后合子的形成是相关基因时序性表达的结果。     

ELOVL2 controls the level of n-6 28:5 and 30:5 fatty acids in testis, a prerequisite for male fertility and sperm maturation in mice

ELOVL2 is a member of the mammalian microsomal ELOVL fatty acid enzyme family, involved in the elongation of very long-chain fatty acids including PUFAs required for various cellular functions in mammals. Here, we used ELOVL2-ablated (Elovl2(-/-)) mice to show that the PUFAs with 24-30 carbon atoms of the ω-6 family in testis are indispensable for normal sperm formation and fertility in male mice. The lack of Elovl2 was associated with a complete arrest of spermatogenesis, with seminiferous tubules displaying only spermatogonia and primary spermatocytes without further germinal cells. Furthermore, based on acyl-CoA profiling, heterozygous Elovl2(+/-) male mice exhibited haploinsufficiency, with reduced levels of C28:5 and C30:5n-6 PUFAs, which gave rise to impaired formation and function of haploid spermatides. These new insights reveal a novel mechanism involving ELOVL2-derived PUFAs in mammals and previously unrecognized roles for C28 and C30 n-6 PUFAs in male fertility. In accordance with the function suggested for ELOVL2, the Elovl2(-/-) mice show distorted levels of serum C20 and C22 PUFAs from both the n-3 and the n-6 series. However, dietary supplementation with C22:6n-3 could not restore male fertility to Elovl2(+/-) mice, suggesting that the changes in n-6 fatty acid composition seen in the testis of the Elovl2(+/-) mice, cannot be compensated by increased C22:6n-3 content.     

Biophysical models of cardiac electrical activity

A system for 3D simulation of heart electrical activity at different structural levels based on fundamental knowledge on the spatiotemporal organization of extracellular electric fields in the myocardium is being developed at the Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences. The system is based on a biophysical model of the genesis of electrocardiosignals (ECSs) in the form of a double electric layer on the surface of the electrically active myocardium, which was proposed earlier and then modified. The system combines a model of the activation and repolarization of the heart ventricles, an advanced model for determining the parameters of the heart electric field, which makes it possible to obtain model ECSs both by direct calculation of the potentials and calculation of ECSs from preliminarily determined components of a multipole equivalent heart generator, a database of model parameters and their combinations in the form of cards of simulated “patients,” and a database of simulated ECSs. This paper (the first in a series of three on the subject) briefly describes simulation methods used in electrocardiology and the biophysical model of heart electrical activity that forms the basis of the system for computer simulation of direct and inverse problems concerning the heart electric field. Electrophysiological, anatomical, and biophysical characteristics of the heart are the parameters of the model.     

卵母细胞成熟发生机制的研究进展

卵母细胞体外成熟培养已成为现代胚胎生物技术的重要内容之一,是体外受精、核移植等生物技术的重要环节。卵母细胞体外成熟受到众多因素的调控,其调控机制十分复杂。本文主要针对卵母细胞成熟过程中卵母细胞胞质成熟、核成熟及其主要调控因子等方面的发生发展机制进行总结。     

The role of factors from the head in the regulation of egg development in the mosquito Aedes aegypti

The relationships between the release of factors from the head after blood-feeding, subsequent levels of ecdysteroids and vitellin, and the ultimate maturation of eggs in Aedes aegypti were investigated. Females were decapitated at various times after a blood meal, at 20 or 48 h after feeding the animals were dissected and divided into two groups, those with arrested oöcytes (yolk length < 100 μm) and those with maturing oöcytes (yolk length > 100 μm). These yolk lengths correspond with the levels of oöcyte growth believed to accompany the proposed initiation and promotion phases of egg development. Animals dissected at 20 h were assayed for ecdysteroid by radioimmunoassay; those dissected at 48 h were assayed for vitellin by rocket immunoelectrophoresis.Non-blood-fed unoperated females contained 8% as much ecdysteroid as blood-fed controls and no measurable vitellin. Females with arrested oöcytes (< 100 μm) were obtained only if decapitations were performed before 8 h; these females had about 20% of the ecdysteroids and 8% of the vitellogenin normally found in blood-fed animals. Females decapitated between 2 and 8 h with maturing oöcytes contained 50–60% as much ecdysteroid and vitellin as blood-fed unoperated controls. Normal ecdysteroid and vitellin levels were reached only when decapitations were delayed for 12 and 24 h, respectively. The number of developing oöcytes was also decreased by early decapitation and was closely correlated with vitellin levels.We conclude that the egg development neurosecretory hormone is released twice, once before 8 h and once after 8 h, to control ecdysteroid levels. We also suggest the presence of other factors from the head that control vitellin levels, the number of developing oöcytes, and the early growth of the oöcyte (initiation).     

Nature of heterosis and combining ability in the silkworm

Summary The isogenic, highly heterotic parthenoclone 29, originating from a hybrid silkworm female, was transformed via unisexual reproduction (meiotic and ameiotic parthenogenesis) into four genotypical variants differing in well-known various levels of hetero zygosity and combinations of useful and harmful genes. A comparison of these changes with the heterosis level made it possible to discover that both heterosity for adaptively neutral genes (overdominance hypothesis) and the number of allelic pairs, each of them being heterozygous for a favourable, completely dominant gene (dominance hypothesis) play no decisive role in the intensity of heterosis. The level of heterosis is largely determined by the relationship between the effects of useful and harmful genes, the first falling into the category of semidominant, cumulatively acting genes which control viability. Their favourable, joint well-coordinated effects, unlike those of genes which control quantitative characters, increase in relation to the number of genes in a geometric rather than an arithmetic progression. The interaction between semilethal genes is subjected to the same regularity. The high combining ability of parthenoclone 29 variants is determined by the number and homozygosity of the useful genes.     

Effects of egg availability and egg maturity on the ovipositional activity of the parasitic wasp, Coccophagus atratus

ABSTRACT. Effects of egg availability on daily ovipositional activity were determined for Coccophagus atratus Compere (Hymenoptera: Aphelinidae). Females were observed for 6 h per day for their entire adult lives. Observed ovipositional activity was analysed in relation to egg maturation before and after emergence, egg depletion during oviposition and egg replenishment after oviposition. Ovipositional activity, including oviposition, inconsequential probes and searching for hosts, occurred predominantly in the first 30 min of exposure to hosts on the 2nd, 4th, 7th, 10th and 13th days after emergence. The remaining time was spent on non-ovipositional activities (preening, drinking honeydew and sitting on the glass of the experimental arena). Peaks of ovipositional activity were associated with high numbers of mature eggs in the ovaries. Eggs that remained in the ovaries after a bout of oviposition were apparently not mature even though they had attained their maximum size. Non-ovipositional activity continued until females had built up a reserve of about eighteen mature eggs. After each successive bout of oviposition, the rate of oogenesis slowed down. Consequently females took longer to accumulate a supply of eggs and periods of non-ovipositional activity increased.
We conclude that (1) the availability of eggs and the tendency of females to store mature eggs influences ovipositional activity, (2) full-sized eggs are not necessarily mature, (3) future experiments with C.atratus could be restricted to days of high ovipositional activity, and (4) the terms syn- and pro-ovigenic formulated by Flanders (1950) to describe apparent differences in oogenesis between various parasitic Hymenoptera do not apply to C. atratus and are therefore not universally applicable.     

Nup154, a New Drosophila Gene Essential for Male and Female Gametogenesis Is Related to the Nup155 Vertebrate Nucleoporin Gene

The Nup154 gene of Drosophila encodes a protein showing similarity with known nucleoporins: rat Nup155 and yeast Nup170 and Nup157. Hypomorphic mutant alleles of Nup154 affected female and male fertility, allowing investigation of the gene function in various steps of oogenesis and spermatogenesis. Nup154 was required in testes for cyst formation, control of spermatocyte proliferation and meiotic progression. In ovaries, Nup154 was essential for egg chamber development and oocyte growth. In both the male and female germ line, as well as in several other cell types, the Nup154 protein was detected at the nuclear membrane, but was also present inside the nucleus. Intranuclear localization has not previously been described for rat Nup155 or yeast Nup170 and Nup157. In mutant egg chambers the Nup154 protein accumulated in the cytoplasm, while it was only barely detected at the nuclear envelopes. FG repeats containing nucleoporins detected with mAb414 antibody were also mislocalized to a certain extent in Nup154 mutant alleles. This suggests that Nup154 could be required for localizing other nucleoporins within the nuclear pore complex, as previously demonstrated for the yeast Nup170. On the other hand, no evident defects in lamin localization were observed, indicating that Nup155 mutations did not affect the overall integrity of the nuclear envelope. However, ultrastructural analyses revealed that in mutant cells the morphology of the nuclear envelope was altered near the nuclear pore complexes. Finally, the multiplicity of phenotypes observed in Nup154 mutant alleles suggests that this gene plays a crucial role in cell physiology.     

Extracellular β-1,3-glucanases are induced during early somatic embryogenesis in Cichorium

In leaf tissues of the Cichorium hybrid clone `474' (C. intybus L. var. sativum × C. endivia L. var. latifolia), the acquisition and expression of embryogenic competence was characterised by the appearance of 15 polypeptides (Boyer et al., 1993, Plant Sci 93: 41–53). The 38-kDa proteins were found to be abundantly present in conditioned embryogenic medium after the first division of the induced cells. These proteins seemed to be glycosylated as indicated by general carbohydrate detection methods. Internal amino-acid sequences obtained after microsequencing tryptic peptides appeared to be 36–57% homologous with plant β-1,3-endoglucanases. In addition, these 38-kDa proteins were recognised by antibodies raised against the pathogenesis-related tobacco glucanase PR2a and their β-1,3-glucanase activity was demonstrated by direct detection in polyacrylamide gels after electrophoresis. These results strongly suggested that the 38-kDa somatic-embryogenesis-related (SER) polypeptides are β-1,3-glucanases. Moreover, the level of glucanase activity was nearly three times higher in the medium of the embryogenic `474' line than in the medium of a non-embryogenic line. The possible involvement of the extracellular 38-kDa proteins in callose degradation during somatic embryogenesis is discussed. Received: 5 May 1997 / Accepted: 25 September 1997     

Postmortale bildung von 5,7-dihydroxychromon-7-rutinosid in Mentha longifolia

5,7-Dihydroxychromone 7-rutinoside isolated from Mentha longifolia must be considered to be a product of postmortem processes. It is only formed after heating fresh plant material and its production is connected with the degradation of flavonoids, and particularly of eriodictyol 7-rutinoside. Investigations with four other Mentha species confirm these results. Eriodictyol 7-rutinoside and eriodictyol are degraded up to 50%, by horseradish peroxidase but 5,7-dihydroxychromone-7-rutinoside cannot be detected.