Trade-off between reciprocal mutualists: local resource availability-oriented interaction in fig/fig wasp mutualism

The mechanisms that prevent competition (conflict) between the recipient and co-operative actor in co-operative systems remain one of the greatest problems for evolutionary biology. Previous hypotheses suggest that self-restraint, dispersal or spatial con

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.

Identification of Differentially Expressed Genes Between Cloned and Zygote-Developing Zebrafish (Danio rerio) Embryos at the Dome Stage Using Suppression Subtractive Hybridization

Comparative analyses of differentially expressed genes between somatic cell nuclear transfer (SCNT) embryos and zygote-developing (ZD) embryos are important for understanding the molecular mechanism underlying the reprogramming processes. Herein, we used the suppression subtractive hybridization approach and from more than 2900 clones identified 96 differentially expressed genes between the SCNT and ZD embryos at the dome stage in zebrafish. We report the first database of differentially expressed genes in zebrafish SCNT embryos. Collectively, our findings demonstrate that zebrafish SCNT embryos undergo significant reprogramming processes during the dome stage. However, most differentially expressed genes are down-regulated in SCNT embryos, indicating failure of reprogramming. Based on Ensembl description and Gene Ontology Consortium annotation, the problems of reprogramming at the dome stage may occur during nuclear remodeling, translation initiation, and regulation of the cell cycle. The importance of regulation from recipient oocytes in cloning should not be underestimated in zebrafish.

Identification of differentially expressed genes from the cross-subfamily cloned embryos derived from zebrafish nuclei and rare minnow enucleated eggs

Cross-species nuclear transfer (NT) has been used to retain the genetic viability of a species near extinction. However, unlike intra-species NT, most embryos produced by cross-species NT were unable to develop to later stages due to incompatible nucleocytoplasmic interactions between the donor nuclei and the recipient cytoplasm from different species. To study the early nucleocytoplasmic interaction in cross-species NT, two laboratory fish species (zebrafish and rare minnow) from different subfamilies were used to generate cross-subfamily NT embryos in the present study. Suppression subtractive hybridization (SSH) was performed to screen out differentially expressed genes from the forward and reverse subtractive cDNA libraries. After dot blot and real-time PCR analysis, 80 of 500 randomly selective sequences were proven to be differentially expressed in the cloned embryos. Among them, 45 sequences shared high homology with 28 zebrafish known genes, and 35 sequences were corresponding to 22 novel expressed sequence tags (ESTs). Based on functional clustering and literature mining analysis, up-and down-regulated genes in the cross-subfamily cloned embryos were mostly relevant to transcription and translation initiation, cell cycle regulation, protein binding, etc. To our knowledge, this is the first report on the determination of genes involved in the early development of cross-species NT embryos of fish. (C) 2007 Elsevier Inc. All rights reserved.

Cytoplasmic impact on cross-genus cloned fish derived from transgenic common carp (Cyprinus carpio) nuclei and goldfish (Carassius auratus) enucleated eggs

In previous studies of nuclear transplantation, most cloned animals were obtained by intraspecies nuclear transfer and are phenotypically identical to their nuclear donors; furthermore, there was no further report on successful fish cloning since the report of cloned zebrafish. Here we report the production of seven cross-genus cloned fish by transferring nuclei from transgenic common carp into enucleated eggs of goldfish. Nuclear genomes of the cloned fish were exclusively derived from the nuclear donor species, common carp, whereas the mitochondrial DNA from the donor carp gradually disappeared during the development of nuclear transfer (NT) embryos. The somite development process and somite number of nuclear transplants were consistent with the recipient species, goldfish, rather than the nuclear donor species, common carp. This resulted in a long-lasting effect on the vertebral numbers of the cloned fish, which belonged to the range of goldfish. These demonstrate that fish egg cytoplasm not only can support the development driven by transplanted nuclei from a distantly related species at the genus scale but also can modulate development of the nuclear transplants.

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.

Nuclear transplantation in different strains of zebrafish

Single later blastula nuclei from AB strain of zebrafish (Danio rerio) were transplanted into enucleated unfertilized eggs of Long fin strain. Of 1119 cloning embryos, 14 reconstructed embryos developed into fry. DNA fingerprinting systems of the cloned fish were similar to those of the nuclear donor fish, but were distinctly different from those of the unclear recipient fish. It confirmed that the genetic material originated from nuclear donor cell other than from nuclear recipient egg. The research suggested that the basic technique for nuclear transplantation performed with different strains of zebrafish has made a breakthrough. It should be helpful for the study of some important developmental problems such as gene function, the regulation of gene expression during animal development, the developmental potential of a nucleus and the interactions between the donor nucleus and the recipient cytoplasm, etc.

Nuclear transfer in leach (Paramisgurnus dabryanus Sauvage) by cell-to-cell electrofusion

To study nuclear transfer in the leach (Paramisgurnus dabryanus Sauvage), blastula and gastrula cells were fused with UV-inactivated oocytes by cell-to-cell electrofusion. To facilitate nuclear transfer, blastula and gastrula cells were cultured or incubated at 4 degreesC in different solutions. TC-199 medium supplemented with 20% calf serum was the best culture solution, and effectively retained the totipotence of blastula or gastrula cells for up to 10 days, It was found that gastrula cells incubated at 4 degreesC had the same totipotence as blastula cells, The optimal UV dosage for inactivation of the oocyte chromatin was 180-240 mJ cm(-2). Electrofusion was carried out in a cone-shaped fusion chamber, which permitted the recipient oocyte and the donor blastula cell to contact one another. The electrofusion procedure resulted in a 10% success rate of normal-appearing fish. Genetic analysis indicated that the nuclear material originated from the donor cell (blastomere) and the oocyte pronucleus did not take part in development.

影响杜泊羊胚胎移植妊娠率和新生个体生长发育的因素：受体和移植季节

胚胎移植具有加速家畜良种推广的潜力。胚胎移植能直接引入纯种动物，并且能避免直接进口动物时可能会带来一些较大传染病（例如口蹄疫）的风险，因此具有成本低、安全性高、直接引入良种的特点。但是胚胎移植的成功率可能会受到很多因素的影响。这些因素可归纳为三个方面：胚胎因素；胚胎和受体的相互作用；受体因素。另一方面，胚胎移植目的是为了获得优秀生产性能的良种个体，但是出生的后代的生长发育情况也会和很多因素有关，例如出生大小、当地气候条件、饲养条件和胚胎移植季节等。因此，研究影响胚胎移植妊娠率以及出生后代生长发育的因素对胚胎移植在生产中的应用有重要意义。杜泊羊作为一种肉用绵羊，品种优良，经济价值很高，被认为应予以积极推广。用胚胎工程对杜泊羊进行推广可能是一个较好的办法。绵羊胚胎工程近年来已经取得了较大进展，例如超数排卵、体外胚胎生产、胚胎冷冻和胚胎移植的研究都取得了一系列的成果。在影响绵羊胚胎移植效果的具体因素中，已有一些关于不同胚胎移植数目、胚龄、冻胚和鲜胚、胚胎移植方法等报道，但是受体品种对杜泊羊的胚胎移植的研究还未见报道，季节对杜泊羊胚胎移植的影响的研究结果也不一致。因此本实验应用质量稳定的胚胎，采用单胚移植，以移植的妊娠率为指标，研究了受体品种和季节因素对杜泊羊冷冻胚胎移植成功率影响，结果发现在三个不同品种的受体中，胚胎移植妊娠率无显著差异（P＞0．05）；但是季节对胚胎移植成功率有显著影响，秋季移植妊娠率（68.6％）显著高于春季（58.5％，P＜0.05）。在山羊等其他动物的研究中表明，受体情况不影响胚胎移植出生的后代的生长发育。本实验以羔羊的出生重、1个月体重和断乳时（2个月时）体重为指标，分析了受体体重和季节对胚胎移植出生杜泊羊羔羊的早期生长发育的影响，结果表明，不同体重的受体会影响羔羊的出生重（P＜0.05），即体重较大的受体出生的羔羊的体重也较大，但经过两个月的哺乳期生长后，羔羊的生长发育情况已无明显差异（P＞0.05）。有研究表明羔羊早期的生长发育情况和外界条件有关。不同季节进行胚胎移植，羔羊出生时间也不同。因此，实验研究了不同季节对胚胎移植出生羔羊早期生长发育的影响。结果发现，季节显著影响了羔羊的生长发育，春季和秋季移植出生的羔羊在出生重方面差异不显著（P＞0.05），但春季移植出生的羔羊的后来的生长情况要明显好于秋季（P＜0.05）。

多接收者环境下的匿名性和密文长度缩短的匿名广播加密算法

形式化构建了在多用户环境和随机数复用多用户环境下的匿名性安全模型,并证明了其安全性;同时提出了2种针对匿名性的可复制测试.基于这些结果,构造了一个通用的密文长度缩短的匿名广播加密算法.

Intergeneric conjugation in holomycin-producing marine Streptomyces sp strain M095

Marine Streptomyces are potential candidates for novel natural products and industrial catalysts. In order to set up biosynthesis approach for a holomycin-producing strain M095 isotated from Jiaozhou Bay, China, a genetic transformation system was established using intergeneric conjugation. The plasmid pIJ8600 consists of an origin of replication for Escherichia coli, a phage integrase directing efficient site-specific integration in bacterial chromosome, thiostrepton-induced promoter and an attP sequence. Using E. coli ET12567 (pUZ8002) carrying pIJ8600 as a conjugal donor, while it was mated with strain M095, pIJ8600 was mobilized to the recipient and the transferred DNA was also integrated into the recipient chromosome. The frequency of exconjugants was 1.9 +/- 0.13 x 10(-4) per recipient cell. Analysis of eight exconjugants showed pIJ8600 was stable integrated at a single chromosomal site (attB) of the Streptomyces genome. The DNA sequence of the attB was cloned and shown to be conserved. The results of growth and antimicrobial activity analysis indicated that the integration of pIJ8600 did not seem to affect the biosynthesis of antibiotics or other essential amino acids. To demonstrate the feasibility of above gene transfer system, the allophycocyanin gene (apc) from cyanobacterium Anacystis nidulans UTEX625 was expressed in strain M095, and the results indicated heterologous allophycocyanin could be expressed and folded effectively. (c) 2006 Elsevier GmbH. All rights reserved.

Heterologous expression and purification of recombinant allophycocyanin in marine Streptomyces sp isolate M097

Allophycocyanin is one of the most important marine active peptides. Previous studies suggested that recombinant allophycocyanin (rAPC) could remarkably inhibit the S-180 carcinoma in mice, indicating its potential pharmaceutical uses. Based on intergeneric conjugal transfer, heterologous expression of rAPC was first achieved in marine Streptomyces sp. isolate M097 through inserting the apc gene into the thiostrepton-induced vector pIJ8600. The transformation frequency for this system was approximately 10(-4) exconjugants/recipient. In the transformed Streptomyces sp. isolate M097, the yield of purified rAPC could amount to about 38 mg/l using a simple purification protocol, and HPLC analysis showed that the purity of the protein reached about 91.5%. In vitro activity tests also revealed that the purified rAPC had effective scavenging abilities on superoxide and hydroxyl radicals. This would widen the usefulness of the marine Streptomyces as a host to express the rAPC and to offer industrial strain for the production of rAPC.

attB site disruption in marine Actinomyces sp M048 via DNA transformation of a site-specific integration vector

An efficient conjugation method has been developed for the marine Actinomyces sp. isolate M048 to facilitate the genetic manipulation of the chandrananimycin biosynthesis gene cluster. A phi C31-derived integration vector pIJ8600 containing oriT and attP fragments was introduced into strain M048 by bi-parental conjugation from Escherichia coli ET12567 to strain M048. Transformation efficiency was (6.38 +/- 0.41) x 10(-5) exconjugants per recipient spore. Analysis of eight exconjugants showed that the plasmid pIJ8600 was stably integrated at a single chromosomal site (attB) of the Actinomyces genome. The DNA sequence of the attB was cloned and shown to be conserved. The results of antimicrobial activity analysis indicated that the insertion of plasmid pIJ8600 seemed to affect the biosynthesis of antibiotics that could strongly inhibit the growth of E. coli and Mucor miehei (Tu284). HPLC-MS analysis of the extracts indicated that disruption of the attB site resulted in the complete abolition of chandrananimycin A-C production, proving the identity of the gene cluster. Instead of chandrananimycins, two bafilomycins were produced through disruption of the attB site from the chromosomal DNA of marine Actinomyces sp. M048.

Possible suppression of exogenous beta-1,3-glucanase gene gluc78 on rice transformation and growth

Three genes encoding for fungal cell wall degrading enzymes (CWDE), ech42, nag7O and gluc78 from the biocontrol fungus Trichoderma atroviride were transformed into rice mediated by Agrobacterium tumefaciens singly and in all possible combinations. A total of more than 1800 independently regenerated plantlets in seven different populations (for each of the three genes and each of the four gene combinations) were obtained. Our data indicated that gluc78 gene had negative effects on transformation frequency and plant growth. Some regenerated plants with gluc78 gene were stunted; spontaneously produced brown specks; could not tassel. The combination with either one of the two other genes (ech42, nag70) present in the same T-DNA region reduced the negative effect of gluc78 on plant growth. These results indicated that expression of several genes in one T-DNA region interfered with each other and expression of exogenous gene in recipient plant was a complex behavior. (c) 2007 Published by Elsevier Ireland Ltd.

成年女儿照料老年父母的心理体验及关系质量作用的研究

Previous researches about family caregiving revealed that caregiving has both negative and positive effects on caregivers’ well-being. Based on Lawton’s two-factor model, this study aims at examining how caring for old parents would affect adult daughters’ psychological well-being. According to Lawton, objective stressors as caregiving would arouse two different kinds of caregivers’ subjective appraisal, i.e., negative appraisal and positive appraisal, which in turn correlate with the negative and positive dimensions of caregivers’ psychological well-being, respectively. There were two main purposes of this study: a) to verify both the negative and positive paths in the two-factor model and their relatively independence; and b) to examine the effects of relationship quality between caregiver and care-recipient on those paths. The results are as follows: 1) Caregiving stressors have significant positive predictive effect on caregivers’ negative appraisal, but have no direct effect on caregivers’ positive appraisal. 2) Caregivers’ negative appraisal has significant positive predictive effect on their negative emotional experience, while caregivers’ positive appraisal has significant positive predictive effect on their positive emotional experience. 3) Certain dimensions of relationship quality, including the Appreciation and General Appraisal, have significant negative predictive effect on caregivers’ negative appraisal, and have significant positive predictive effect on caregivers’ positive appraisal. 4) The Appreciation dimension of relationship quality moderates the path from caregiving demands to caregivers’ burden; and the General Appraisal of relationship quality moderates the path from caregivers’ positive appraisal to life satisfaction. Based on the above results, the researcher concluded that a) both the negative path and positive path exist in caregiving process, and they are relatively independent from each other; and b) relationship quality does moderate certain paths in the model. Meanwhile, the main effect of relationship quality on caregivers’ experience is also significant and more remarkable. This study attempts to explain these results in terms of coping resources. Both relationship quality and many other factors might be explained as resources that caregivers utilize to cope with stress of caregiving. With more resources, caregivers tend to appraise more positively, and less negatively, and vice versa. However, the resources which might affect caregivers’ positive appraisal, as well as the ways they work, may be different from that affect caregivers’ negative appraisal.