Binding of anti-H-Y monoclonal antibodies to separated X and Y chromosome bearing porcine and bovine sperm

Studies designed to answer the question whether or not H-Y antigen is preferentially expressed on Y chromosome bearing sperm have resulted in conflicting results. This is probably due to the absence of reliable methods for estimating the percentage of X and Y chromosome bearing sperm in fractions, enriched or depleted for H-Y antigen positive sperm. In recent years a reliable method for separating X and Y chromosome bearing sperm has been published. With this method, separation is achieved by using a flow cytometer/cell sorter, which detects differences in DNA content. This technique provided the first opportunity for testing anti-H-Y antibody binding to fractions enriched for X and Y chromosme bearing sperm, directly. A total of 7 anti-H-Y monoclonal antibodies were tested using sorted porcine sperm and in one experiment also sorted bovine sperm. All monoclonal antibodies bound only a fraction of the sperm (20 to 50%). However, no difference in binding to the X and Y sperm enriched fractions was found. Therefore, the present experiments do not yield evidence that H-Y antigen is preferentially expressed in Y chromosome bearing sperm. © 1993 Wiley-Liss, Inc.     

Accelerated organic matter decomposition in thermokarst lakes upon carbon and phosphorus inputs

Mineralization of dissolved organic matter (DOM) in thermokarst lakes plays a non-negligible role in the permafrost carbon (C) cycle, but remains poorly understood due to its complex interactions with external C and nutrient inputs (i.e., aquatic priming and nutrient effects). Based on large-scale lake sampling and laboratory incubations, in combination with ¹³C-stable-isotope labeling, optical spectroscopy, and high-throughput sequencing, we examined large-scale patterns and dominant drivers of priming and nutrient effects of DOM biodegradation across 30 thermokarst lakes along a 1100-km transect on the Tibetan Plateau. We observed that labile C and phosphorus (P) rather than nitrogen (N) inputs stimulated DOM biodegradation, with the priming and P effects being 172% and 451% over unamended control, respectively. We also detected significant interactive effects of labile C and nutrient supply on DOM biodegradation, with the combined labile C and nutrient additions inducing stronger microbial mineralization than C or nutrient treatment alone, illustrating that microbial activity in alpine thermokarst lakes is co-limited by both C and nutrients. We further found that the aquatic priming was mainly driven by DOM quality, with the priming intensity increasing with DOM recalcitrance, reflecting the limitation of external C as energy sources for microbial activity. Greater priming intensity was also associated with higher community-level ribosomal RNA gene operon (rrn) copy number and bacterial diversity as well as increased background soluble reactive P concentration. In contrast, the P effect decreased with DOM recalcitrance as well as with background soluble reactive P and ammonium concentrations, revealing the declining importance of P availability in mediating DOM biodegradation with enhanced C limitation but reduced nutrient limitation. Overall, the stimulation of external C and P inputs on DOM biodegradation in thermokarst lakes would amplify C-climate feedback in this alpine permafrost region.     

The ClpE protein involved in biogenesis of the CS31A capsule-like antigen is a member of a periplasmic chaperone family in Gram-negative bacteria

Abstract The putative chaperone-like protein ClpE, required for biogenesis of the Escherichia coli capsule-like antigen CS31A, was compared with ten known periplasmic chaperones from E. coli, Klebsiella pneumoniae, Bordetella pertussis, Haemophilus influenzae and Yersinia pestis . The amino acid sequence alignment was superimposed onto the three-dimensional structure of the PapD chaperone of uropathogenic E. coli , and amino acid residues involved in maintaining the structure integrity of the suggested binding site were found identical in most of the 11 chaperones. Construction of a phylogenetic tree to investigate the relationship within the chaperone family has revealed interesting degrees of relatedness between the different proteins.     

LDL的氧化修饰和氧化修饰LDL的组成和结构变化

与低密度脂蛋白(LDL)相比,氧化修饰LDL(O-LDL)的组成、结构和生物学特性发生了深刻的变化,而组成和结构的改变是生物学特性改变的基础.本文根据最近文献资料.结合我们实验室的工作.对LDL的氧化修饰、O-LDL的组成、结构改变,以及它们的机理作一简要综述.     

鼠兔核质杂交胚胎早期发育的研究

细胞核移植技术已被证明是研究发育中核质相互关系的非常重要的手段之一,电融合技术也是近十年发展起来的新型细胞融合技术。本实验运用这两项技术,进行了鼠、兔目间核质杂交实验,小鼠8-细胞核在激活的兔去核卵母细胞中,发生了染色体超前凝聚及核膨胀,融合卵移植到小鼠输卵管4.5天后,冲洗出,有5.4%的重构卵发育到囊胚期,通过染色体检查,囊胚细胞中均为小鼠染色体,其中一个囊胚为正常小鼠核型(2 n=40,XX)。通过本实验,我们认为:鼠兔远缘核质杂交胚胎的早期发育是可能的。     

Correlation between rainfall in the dry season and the occurrence of the white rice borer (Scirpophaga innotata Wlk.) in Java

The amount of rain which falls sporadically in the relatively dry season at the time that the white rice borer is diapausing as a full grown larva in the rice stubble, has a very important influence on the size of population of the borers in the following wet season when rice is grown. If this dry season is wet or very wet (according to our standard, based on the figures of rainfall and borer damage over 26 years in five regions of Eastern Java), no damage can be expected in the following planting season. If the dry season is really dry or very dry, outbreaks of borers may occur (in the period under survey this occurred in nine out of fourteen years). We have tried to give an outline of a method of prediction of borer damage in the planting season, based on the rainfall dates of the foregoing dry season.

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Zusammenfassung Der Weisse Reisbohrer (Scirpophaga innotata Wlk.) kommt nur in Gebieten vor, wo jährlich eine ausgeprägte Regen- und Trockenzeit (Monsun) auftritt. Am Ende der Regenzeit gehen die vollerwachsenen Raupen, die im Stengel der reifenden Reispflanze leben, in Diapause. Während der folgenden relativ trockenen Jahreszeit, wenn nur gelegentlich Regenschauer fallen, ruhen die Raupen in der Stoppel. Bald nachdem die ersten heftigen Regenfälle der neuen Regenzeit einsetzen, verpuppen sich die Larven und alle Falter schlüpfen gemeinsam zum Stoppelflug.Dieser Zünsler ist in gewissen Gebieten Javas einer der Hauptschädlinge des Reises, obwohl sein Auftreten sehr unregelmäßig ist. Jahrelang war man allgemein der Auffassung, daß relativ reichlicher Regenfall während der Trockenzeit die Reisbohrerpopulation erheblich vermindere und daß in diesem Falle keine schweren Schäden durch Reisbohrerbefall erwartet werden können.Während eines Zeitraums von 26 Jahren (1915–1940) wurden in fünf Gebieten Ost-Javas sowolhl der Niederschlag wie der Bohrerschaden untersucht und Berechnungen der jährlichen Niederschlagsmenge in der Trockenzeit und des Bohrerschadens verglichen. Dies erhärtete die alte Auffassung, daß nach einer relativ feuchten oder sehr feuchten Trockenzeit kein Bohrerbefall von Bedeutung während des Beobachtungszeitraumes auftritt. Dagegen folgten in neun von 14 Jahren mit einer trockenen oder sehr trockenen Trockenzeit schwere oder ziemlich schwere Ausbrüche der Weißen Reisstengelbohrer während der folgenden feuchten Jahreszeiten. Obwohl auch andere Faktoren von einiger Bedeutung sein dürften, wird geschlossen, daß die Niederschlagsmenge während der Trockenzeit einen sehr entscheidenden Einfluß auf die Möglichkeit des Auftrétens einer Reisbohrer Kalamität im darauffolgenden Jahre hat. Diesen Daten entsprechend wird auf der Grundlage der Niederschlagszahlen in der vorangegangenen Trockenzeit ein Prognose-Schema entwickelt, wann Bohrerschaden zu erwarten ist.

     

Effects of temperature,salinity and agitation on byssus thread formation of zebra musselDreissena polymorpha

Byssus thread production ofD. polymorpha under different conditions of temperature, salinity and agitation were studied in the laboratory. The acclimation to salinity and temperature greatly affects the byssus production ofD. polymorpha. Byssus production of mussels was significantly reduced when temperature increased beyond 20°C and decreased below 10°C. Mussels with cut threads (for counting), produced a substantially increased number of threads. However, mussels with uncut byssus threads were comparatively more mobile. Byssus production of mussels did not vary significantly at salinities up to 3. Beyond this salinity byssus production was reduced significantly. Mussels increased their byssus production with increasing frequency of agitation.     

细叶马先蒿根系发育形态学研究

细叶马先蒿为玄参科多年生草本植物。年生产周期明显缩短。根系营养生长至花期为粗壮主根与纤细侧根并存,果期侧根几乎全部枯萎脱落,所存留根系皆呈乳白色。由胚根形成的初生主根根毛密集,初生木质部二原型。侧生分生组织只有形成层而无木栓形成层。根表皮细胞经解离后略呈不规则方形片状,横切面为平周长梭形,进行垂周分裂增加梭形根表皮细胞长度,以适应根的增粗生长。根表皮脱落时,外皮层以同样生长方式代替脱落的表皮。在年