Improved suppression of circulating complement does not block acute vascular rejection of pig-to-rhesus monkey cardiac transplants

At present, acute vascular rejection (AVR) remains a primary obstacle inhibiting long-term graft survival in the pig-to-non-human primate transplant model. The present study was undertaken to determine whether repetitive injection of low dose Yunnan-cobra venom factor (Y-CVF), a potent complement inhibitor derived from the venom of Naja kaouthia can completely abrogate hemolytic complement activity and subsequently improve the results in a pig-to-rhesus monkey heterotopic heart transplant model. Nine adult rhesus monkeys received a heterotopic heart transplant from wild-type pigs and the recipients were allocated into two groups: group 1 (n = 4) received repetitive injection of low dose Y-CVF until the end of the study and group 2 (n = 5) did not receive Y-CVF. All recipients were treated with cyclosporine A (CsA), cyclophosphamide (CyP) and steroids. Repetitive Y-CVF treatment led to very dramatic fall in CH50 and serum C3 levels (CH50 < 3 units/C3 remained undetectable throughout the experiment) and successfully prevented hyperacute rejection (HAR), while three of five animals in group 2 underwent HAR. However, the continuous suppression of circulating complement did not prevent AVR and the grafts in group 1 survived from 8 to 13 days. Despite undetectable C3 in circulating blood, C3 deposition was present in these grafts. The venular thrombosis was the predominant histopathologic feature of AVR. We conclude that repetitive injection of low dose Y-CVF can be used to continuously suppress circulating complement in a very potent manner and successfully prevent HAR. However, this therapy did not inhibit complement deposition in the graft and failed to prevent AVR. These data suggest that using alternative pig donors [i.e. human decay accelerating factor (hDAF)-transgenic] in combination with the systemic use of complement inhibitors may be necessary to further control complement activation and improve survival in pig-to-non-human primate xenotransplant model.

克隆植物绢毛匍匐委陵菜的生态对策研究

本文以匍匐茎草本绢毛匍匐委陵菜(Potentilla reptans L var. sericophylla)为研究对象，基于实验生态学研究方法和野外调查研究了该植物对异质性环境的生态适应对策。 　　对落叶松和油松群林下的绢毛匍匐委陵菜的基株特征和种群特征研究表明：在落叶松林下，绢毛匍匐委陵菜克隆分株具有更大叶面积和更长叶柄;在油松林下，绢毛匍匐委陵菜具有更多的匍匐茎和更多的克隆分株。两个生境中的绢毛匍匐委陵菜形成与其生境相适应的克隆形态和克隆生长特征。在两个群落中的绢毛匍匐委陵菜分株种群的密度和地上生物量没有差异。 　　应用GS+统计软件分析了绢毛匍匐委陵菜分株种群特征及其与所处的土壤基质九个指标（土壤有机质（SOC）、土壤全氮（STN）、土壤全磷（STP）、有效钾（K+）、有效磷（PO43-）、NH4+、NO3-、土壤含水量（SWC）、pH）的空间分布格局的关系，结果显示，绢毛匍匐委陵菜克隆分株种群呈斑块状分布，其克隆分株数的空间自相关尺度为1米;其生长的土壤基质的9个土壤养分及土壤性状指标也都显示了强烈的空间自相关，其自相关尺度（变程）范围在0.24 m ～1.05 m之间，大小顺序为STP>K+>SOC>pH>STN> NO3-> PO43->SWC> NH4+。 其中除STP外，其他8个土壤指标的空间自相关尺度都在0.5 m 左右，NH4+仅为24.4 cm。绢毛匍匐委陵菜野外克隆分株的匍匐茎节间长平均在7 cm 左右。由此表明绢毛匍匐委陵菜克隆分株种群的空间分布尺度大于其所在土壤基质养分及其物理性状的分布尺度，相互联结的克隆分株对异质性土壤资源表现出较大的缓冲能力。其原因之一有可能是克隆生理整合作用使克隆分株局部反应减弱，克隆分株表现趋于一致，克隆分株间实现资源共享，从而高效利用异质性土壤资源。 　　绢毛对匍匐委陵菜克隆特征的局部特化实验将生长在北京东灵山油松（Pinus tabulaeformis）林林窗和林下的绢毛匍匐委陵菜，进行生境间的交互移植-重植野外生态实验以验证绢毛匍匐委陵菜林窗和林下种群间的行为差异是完全由表型可塑性引起，还是局部分化的结果。研究结果表明，实验植物的叶片长度、叶片宽度、叶柄长度和匍匐茎节间长度等克隆形态特征在两生境间无差异。两个来源的植株，其基株生物量、基株分株数和基株匍匐茎总长度等克隆生长特征在林下生境中都比在林窗生境中小，表现出显著的可塑性。所研究的克隆形态特征和克隆生长特征及其可塑性在不同生境来源的实验植物间没有差异。绢毛匍匐委陵菜克隆形态特征和克隆生长特征及其可塑性在林下和林窗生境间没有发生局部分化，林窗为其较适生境，克隆生长特征的可塑性对绢毛匍匐委陵菜利用生境异质性可能具有主要意义。 　　绢毛匍匐委陵菜对土壤养分的克隆可塑性共进行了两个实验。实验1 探讨绢毛匍匐委陵菜对8个土壤基质养分梯度(N, P, K)的克隆可塑性。其结果表明，在植株能够生长的土壤基质养分条件下，随着土壤养分浓度增加，基株生物量、匍匐茎数、分株数增加;生物量分配可塑性反应格局为：随着土壤基质养分浓度的增加，对根生物量投资降低，对叶片的生物量投资增加，而对匍匐茎的投资没有改变。匍匐茎节间长、比叶片重没有对土壤养分梯度发生可塑性反应。随着土壤基质养分的增加，植株根冠比和比根重下降，而根系总长和叶片面积增加。实验2 设置与实验1相同的8个土壤养分梯度，分三个时期收获以探讨绢毛匍匐委陵菜不同发育时期对土壤养分梯度的克隆可塑性，其结果表明：随着植株发育年龄的增加，绢毛匍匐委陵菜的克隆可塑性有增强的趋势。生物量分配格局对土壤养分梯度的可塑性反应早于基株总生物量的可塑性反应;叶片面积、根系总长度和比根重在植物生长后期对土壤养分梯度发生可塑性反应;比叶面积在植物生长早期对土壤养分梯度发生可塑性反应，而在后期则没有;匍匐茎比节间重在生长之初和生长后期均对养分梯度发生可塑性反应。 　　绢毛匍匐委陵菜对局部遮荫的克隆可塑性实验是将采自林窗和林内生境的绢毛匍匐委陵菜“分株对”（即由一匍匐茎节间相连着的两个分株，其一为“目标分株”另一为“相连分株”）在一户外实验中进行全不遮荫、全部遮荫和局部遮荫处理。其结果表明，绢毛匍匐委陵菜基株生物量、匍匐茎总长度、分株数、匍匐茎比节间重、叶柄长、比叶柄重在遮荫条件下较小。匍匐茎节间长度没有对遮荫处理发生反应。在局部遮荫处理，遮荫斑块的分株的叶柄长度由于连着未遮荫斑块中分株而变得更长。这种克隆整合对克隆形态可塑性的修饰作用只在林窗生境来源的实验植物中观察到。其它克隆生长和克隆形态特征的可塑性在不同生境来源的实验植物间没有差异。

The evolution of cooperation in asymmetric systems

Explaining "Tragedy of the Commons" of evolution of cooperation remains one of the greatest problems for both biology and social science. Asymmetrical interaction, which is one of the most important characteristics of cooperative system, has not been sufficiently considered in the existing models of the evolution of cooperation. Considering the inequality in the number and payoff between the cooperative actors and recipients in cooperation systems, discriminative density-dependent interference competition will occur in limited dispersal systems. Our model and simulation show that the local but not the global stability of a cooperative interaction can be maintained if the utilization of common resource remains unsaturated, which can be achieved by density-dependent restraint or competition among the cooperative actors. More intense density dependent interference competition among the cooperative actors and the ready availability of the common resource, with a higher intrinsic contribution ratio of a cooperative actor to the recipient, will increase the probability of cooperation. The cooperation between the recipient and the cooperative actors can be transformed into conflict and, it oscillates chaotically with variations of the affecting factors under different environmental or ecological conditions. The higher initial relatedness (i.e. similar to kin or reciprocity relatedness), which is equivalent to intrinsic contribution ratio of a cooperative actor to the recipient, can be selected for by penalizing less cooperative or cheating actors but rewarding cooperative individuals in asymmetric systems. The initial relatedness is a pivot but not the aim of evolution of cooperation. This explains well the direct conflict observed in almost all cooperative systems.

受体品种、体重及移植季节对杜泊羊胚胎妊娠率和新生羔羊体重的影响

胚胎移植可以提高家畜良种扩大的速度, 但移植成功率会受到很多因素的影响。用615～715 日龄 杜泊羊冷冻胚胎作为移植胚胎, 研究了季节和受体状况对杜泊羊胚胎移植妊娠率以及出生羔羊生长发育的影 响。在比较春秋两季236 枚冷冻胚胎的移植效果发现: 秋季移植的妊娠率(6816 %) 显著高于春季(5815 %) ; 春季和秋季移植后出生羔羊的体重, 初生时无显著差异; 但在30 日和60 日(断乳) 时, 春季移植的羔羊显著 高于秋季。比较不同品种的受体发现, 昭通绵羊受体的胚胎移植妊娠率最高, 湖羊次之, 小尾寒羊最低, 但受 体羊3 种品种间无显著差异; 较大受体羊( ≥40 kg) 生产的羔羊出生和30 d 的体重显著高于较小受体( < 40 kg) ; 但60 d 羔羊体重差异不显著, 说明受体体重会影响羔羊的出生体重, 但是对哺乳期的生长发育影响不大。 春季移植出生的羔羊, 其早期生长发育情况明显优于秋季。

云南眼镜蛇毒因子用于预致敏大鼠同种心脏移植的实验研究

目的观察纯化的云南眼镜蛇毒因子(Y-CVF)对预致敏大鼠同种心脏移植急性体液排斥反应的作用。方法BN大鼠到Lewis大鼠连续3次皮肤移植预致敏后行颈部异位心脏移植。将15对大鼠用随机数字法分成2组,实验组(n=8)于心脏移植前24h静脉给予Y-CVF80μg/kg;对照组(n=7)不用Y-CVF。观察移植心的生存时间,移植心停跳后病理学检查排斥类型,免疫组织化学染色观察移植心IgG和补体C3的沉积。结果Lewis大鼠预致敏后抗BN大鼠抗体滴度由0升高至1∶1028~1∶2056。对照组移植心存活时间为12·71h±13·94h,实验组移植心存活时间为99·50h±38·72h,与对照组比较差异有统计学意义(t=5·599,P<0·01)。病理检查结果证实,实验组均未发生急性体液排斥,仅见以大量单核淋巴细胞浸润为特征的急性细胞排斥反应。对照组则见以小血管内血栓形成为特征的急性体液排斥反应。免疫组织化学IgG染色实验组和对照组均为阳性,C3染色对照组为阳性,而实验组为阴性。结论使用Y-CVF可克服预致敏大鼠同种心脏移植急性体液排斥反应的发生。

Prolonged cardiac xenograft survival in guinea pig-to-rat model by a highly active cobra venom factor

A highly active cobra venom factor (CVF) was isolated from the venom of Naja kaouthia by sequential column chromatography. It displays strong anticomplementary activity, and has 1515 U of anti complementary activity per mg protein. A single dose of 0.1 mg/kg CVF given i.v. to rats completely abrogated complement activity for nearly 5 days. Given 0.02 mg/kg of CVF. the complement activity of rats was reduced by more than 96.5% in 6 It. In guinea pig-to-rat heart transplant model, rats treated with a single dose of 0.05 mg/kg CVF had significantly prolonged xenograft survival (56.12 +/- 6.27 h in CVF-treated rats vs. 0.19 +/- 0.07 h in control rats, P < 0.001). (C) 2003 Elsevier Ltd. All rights reserved.

Factors affecting the efficiency of somatic cell nuclear transplantation in the fish embryo

Procedures to improve somatic cell nuclear transplantation in fish were evaluated. We reported effects of nonirradiated recipient eggs, inactivated recipient eggs, different combinations between recipient eggs and donor cells, duration of serum starvation, generation number, and passage number of donor cells on developmental rates of nuclear transplant (NT) embryos. Exposure to 25,000 R of gamma-rays inactivated recipient eggs. Single nucleus of cultured, synchronized somatic cell from gynogenetic bighead carp (Aristichthys nobilis) was transplanted into nonirradiated or genetically inactivated unfertilized egg of gibel carp (Carassius auratus gibelio). There was no significant difference in developmental rate between nonirradiated and inactivated recipient eggs (27.27% vs. 25.71%, respectively). Chromosome count showed that 70.59% of NT embryos contained 48 chromosomes. It showed that most NT embryos came from donor nuclei of bighead carp, which was supported by microsatellite analysis of NT embryos. But 23.53% of NT embryos contained more than 48 chromosomes. It was presumed that those superfluous chromosomes came from nonirradiated recipient eggs. Besides, 5.88% of NT embryos were chimeras. Eggs of blunt-snout bream (Megalobrama amblycephala) and gibel carp were better recipient eggs than those of loach (Misgurnus anguillicaudatus) (25% and 18.03% vs. 8.43%). Among different duration of serum starvation, developmental rate of NT embryos from somatic nuclei of three-day serum starvation was the highest, reaching 25.71% compared to 14.14% (control), 20% (five-day), and 21.95% (seven-day). Cultured donor cells of less passage facilitated reprogramming of NT embryos than those of more passage. Recloning might improve the developmental rate of NT embryos from the differentiated donor nuclei. Developmental rate of fourth generation was the highest (54.83%) and the lowest for first generation (14.14%) compared to second generation (38.96%) and third generation (53.01%). (C) 2002 Wiley-Liss, Inc.

Relationship between tissue concentrations of polycyclic aromatic hydrocarbons and DNA adducts in green-lipped mussels (Perna viridis)

Green-lipped mussels (Perna viridis) were collected from a site in Hong Kong which is relatively free from polycyclic aromatic hydrocarbon (PAH) contamination, and maintained in situ at this and three other sites with different degrees of PAH contamination. The transplanted mussels were retrieved after a 30-day field exposure. DNA adducts in the gill tissues were quantified, and tissue concentrations of benzo[a]pyrene as well as total PAHs (with potential carcinogenicity) determined for individual mussels. Results indicate that (1) tissue concentration of PAHs and adduct levels in mussels collected from a single site can be highly variable; and (2) adduct levels were related to tissue concentrations of benzo[a]pyrene as well as total PAHs of individual animals.

Genetic transformation in Kappaphycus alvarezii using micro-particle bombardment: a potential strategy for germplasm improvement

This study investigated the delivery of a SV40 promoter driving lacZ gene into cells of Kappaphycus alvarezii using particle bombardment. Thallus pieces 0.5-0.8 mm in diameter and 1 cm in length were prepared as gene recipients. Bombardment parameters of 450 psi (rupture pressures) x 6 cm (particle travel distances), 650 psi x 6 cm, 1,100 psi x 6 cm and 1,100 psi x 9 cm were used. A significant increase in transformation efficiency from about 33% under the rupture pressure of 450 psi to 87% at 650 psi was observed in transformed thalli. Most of the positive cells appeared in epidermal cells bombarded at 450 psi, whereas positive signals were seen in both epidermal and medullary cells at 650 psi. No positive transient expression was detected at a bombardment of 1,100 psi, or in negative or blank controls. For the conditions tested, the best parameter was obtained at 650 psi at a distance of 6 cm. Thus, the strategy of taking vegetative thalli as recipients, using particle bombardment, and combining this with micro-propagation, together with developing an in vivo selectable marker, is a viable way to produce stable transformants, to eliminate chimeric expression, and to achieve transgenic breeding in K. alvarezii.

在51单片机上移植uC/OS—II关键问题的解决

由于MCS-51系列微控制器存在着硬件堆栈小的结构缺陷,无法满足多任务环境下进行任务切换的需求,因此很难将uC/OS—II移植到MCS-51系列微控制器上。本文给出的"堆栈映射"方式很好的解决了这个问题。同时还对uC/OS—II移植过程中一些关键性问题给予了详细的论述。包括:uC/OS—II可移植的条件、内核配置和裁剪以及内核调试。