蚤数量与宿主数量关系

无论在自然条件下或在人为条件下,蚤指数和染蚤率的高低与宿主密度的高低是一致的.宿主密度的升降,会导致其寄生蚤指数和染蚤率的升降. 本文讨论了宿主数量下降导致其寄生蚤数量下降的原因,仅是分析推测,提出几方面的看法.     

Expression of MRF4, a myogenic helix-loop-helix protein, produces multiple changes in the myogenic program of BC3H-1 cells.

Expression of MRF4, a myogenic regulatory factor of the basic helix-loop-helix type, produced multiple changes in the myogenic program of the BC3H-1 cell line. BC3H-1 cells that stably expressed exogenous MRF4 were prepared and termed BR cell lines. Upon differentiation, the BR cells were found to have three muscle-specific properties (endogenous MyoD expression, myoblast fusion, and fast myosin light-chain 1 expression) that the parent BC3H-1 cells did not have. Of the four known myogenic regulatory factors (MyoD, myogenin, Myf-5, and MRF4), only MRF4 was capable of activating expression of the endogenous BC3H-1 myoD gene. In addition, the pattern of Myf-5 expression in BR cells was the opposite of that in BC3H-1 cells. Myf-5 expression was low in BR myoblasts and showed a small increase upon myotube formation, whereas Myf-5 expression was high in BC3H-1 myoblasts and decreased upon differentiation. Though the MRF4-transfected BR cells fused to form large myotubes and expressed fast myosin light-chain 1, the pattern of myosin heavy-chain isoform expression was the same in the BR and the nonfusing parent BC3H-1 cells, suggesting that factors in addition to the MyoD family members regulate myosin heavy-chain isoform expression patterns in BC3H-1 cells. In contrast to the changes produced by MRF4 expression, overexpression of Myf-5 did not alter BC3H-1 myogenesis. The results suggest that differential expression of the myogenic regulatory factors of the MyoD family may be one mechanism for generating cells with diverse myogenic phenotypes.     

FMRFamide modulates the action of phase shifting agents on the ocular circadian pacemakers of Aplysia and Bulla

Summary The eye of the marine mollusk Aplysia californica contains a photo-entrainable circadian pacemaker that drives an overt circadian rhythm of spontaneous compound action potentials in the optic nerve. Both light and serotonin are known to influence the phase of this ocular rhythm. The current study evaluated the effect of FMRFamide on both light and serotonin induced phase shifts of this rhythm. The application of FMRFamide was found to block serotonin induced phase shifts but, by itself, FMRFamide did not cause significant phase shifts. Furthermore, the effects of FMRFamide on light-induced phase shifts appeared to be phase dependent (i.e., the application of FMRFamide inhibited light-induced phase delays but actually enhanced the magnitude of phase advances). As in Aplysia, the eye of Bulla gouldiana also contains a circadian pacemaker. In Bulla, FMRFamide prevented light-induced phase advances and delays. Although FMRFamide alone generated phase dependent phase shifts, it did not cause phase shifts at the phases where it blocked the effects of light. These data demonstrate that FMRFamide can have pronounced modulatory effects on phase shifting inputs to the ocular pacemakers of both Aplysia and Bulla.Abbreviations ASW artificial seawater - CAP compound action potential - CT circadian time - 5-HT serotonin     

四川省西部鱼类寄生粘孢子虫——1.粘体虫属六新种(粘孢子纲:双壳目)

本文报导四川省西部鱼类寄生粘孢子虫粘体虫属六新种,即异型粘体虫,新种Myxosoma disparis sp.nov.,四川粘体虫,新种Myxosoma sichuanensis sp.nov.,光唇粘体虫,新种Myxosoma acrossochilusi sp.nov.鳅粘体虫,新种Myxosoma nemachilusi sp.nov.斜囊粘体虫,新种Myxosoma obliqua sp.nov.,雅安粘体虫,新种Myxosoma yaanensis sp.nov.。     

关于苦马豆属学名的讨论

本文根据国内外豆科研究文献的考证,讨论了苦马豆属(Sphaerophysa DC.)及其近缘属的区别,重新确认了国产苦马豆属和苦马豆的学名。     

Temporal events of gypsy moth vitellogenesis and ovarian development

Abstract The vitellogenic period of gypsy moth ovarian development starts on day 3 of the pupal stage and continues through adulthood. During this period, rapid increases occur in follicle size, protein content, and wet weight of the ovary. Patency is observed on day 3 of the pupal stage.
Pre-vitellogenic follicles are formed in the last larval stadium. Newly formed follicles detach from the germarium on day 4, and increase rapidly to 140 per ovariole at the end of the last larval stadium. The pre-vitellogenic follicles are uniformly around 50 um in diameter. No vitellogenin is incorporated into the oocytes until the pupal stage.
Polyacrylamide gel electrophosesis (PAGE) in the presence of sodium dodecylsulphate (SDS) analysis of male and female haemolymph samples and vitellogenic ovaries demonstrates the presence of two female-specific subunits of vitellogenin of 180 kD and 160 kD. These proteins are detected only in haemolymph and ovarian extracts of vitellogenic females. The molecular weight of the native protein determined by size exclusion chromatography is approximately 400–420 kD.
A highly sensitive double antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed to monitor the temporal changes in vitellogenin titre in haemolymph. Vitellogenin production starts on day 2 of the last larval stadium, reaching a maximum level by day 6 of the last larval stadium, and decreasing in the late pupal stage as vitellogenin was internalized into the oocytes. This is the first report of vitellogenin production occurring in the larval stage of a holometabolous insect. The fact that vitellogenin production and uptake occur during different stages of development in the gypsy moth, opens up some interesting questions concerning the underlying regulatory mechanisms controlling each process.     

消炎痛及PGF_(2α)对在体培养人子宫内膜出血的影响

利用甾体激素撤退方法造成移植在地鼠颊囊内人子宫内膜出血的动物模型,研究消炎痛和PGF_(2a)对内膜出血的作用。结果表明,注射三种不同剂量消炎痛并不能完全抑制内膜出血,但对内膜出血时间有延缓作用。用两种不同剂量的PGF_(2a)采取缓慢释放给药方法,虽然地鼠在给药后外周血液中PGF_(2a)水平比给药前显著增高,但内膜出血并不出现在撤退甾体激素之前。结果提示,PGF_(2a)对内膜血管破裂无直接作用,而纤溶活性变化可能是触子宫内膜出血更直接的原因。     

蟾蜍卵母细胞的Na~+/H~+交换

应用pH选择性徽电极和普通檄电极测量了蟾蜍卵母细胞内的pH值(pHi)。当用含NH_4~+而不含HCO_3~-的溶液培灌卵母细胞时,pHi逐渐下降,在停止培灌后,pHi恢复到对照值。这个pHi恢复过程是一个H~+的主动转运,用胆碱离子取代培灌液中的Na~+可以抑制pHi的恢复,这种抑制作用是可逆的。伴随着细胞内pH值的恢复,细胞内Na~+活度(Na_1~+)呈现暂时性增加,而细胞内Cl-活度(Cl_1~+)不变或稍有增加。实验结果提示在蟾蜍卵母细胞膜上存在着Na~+/H~+的交换。     

Localization of phosphatidylcholine in outer envelope membrane of spinach chloroplasts

We have examined the effects of phospholipase C from Bacillus cereus on the extent of phospholipid hydrolysis in envelope membrane vesicles and in intact chloroplasts. When isolated envelope vesicles were incubated in presence of phospholipase C, phosphatidylcholine and phosphatidylglycerol, but not phosphatidylinositol, were totally converted into diacylglycerol if they were available to the enzyme (i.e., when the vesicles were sonicated in presence of phospholipase C). These experiments demonstrate that phospholipase C can be used to probe the availability of phosphatidylcholine and phosphatidylglycerol in the cytosolic leaflet of the outer envelope membrane from spinach chloroplasts. When isolated, purified, intact chloroplasts were incubated with low amounts of phospholipase C (0.3 U/mg chlorophyll) under very mild conditions (12 degrees C for 1 min), greater than 80% of phosphatidylcholine molecules and almost none of phosphatidylglycerol molecules were hydrolyzed. Since we have also demonstrated, by using several different methods (phase-contrast and electron microscopy, immunochemical and electrophoretic analyses) that isolated spinach chloroplasts, and especially their outer envelope membrane, remained intact after mild treatment with phospholipase C, we can conclude that there is a marked asymmetric distribution of phospholipids across the outer envelope membrane of spinach chloroplasts. Phosphatidylcholine, the major polar lipid of the outer envelope membrane, is almost entirely accessible from the cytosolic side of the membrane and therefore is probably localized in the outer leaflet of the outer envelope bilayer. On the contrary, phosphatidylglycerol, the major polar lipid in the inner envelope membrane and the thylakoids, is probably not accessible to phospholipase C from the cytosol and therefore is probably localized mostly in the inner leaflet of the outer envelope membrane and in the other chloroplast membranes.