Hepatic ultrastructural specialization in Antarctic fishes

Summary Compared with those of other vertebrate animals, the livers of Antarctic fishes have a unique type of perisinusoidal (Ito) cell. These cells were studied in 9 species with emphasis on Dissostichus mawsoni. Perisinusoidal cells are found in large numbers throughout the liver, have long cytoplasmic arms and, in Dissostichus, contain numerous lipid droplets. The extensive rough endoplasmic reticulum and prominent nucleolus are ultrastructural characteristics indicating that these cells are engaged in protein synthesis. An evolutionary specialization, perisinusoidal cells may be partially responsible for the elevated levels of protein synthesis characteristic of fishes in the Antarctic marine environment.     

Oligomerization of the voltage-gated proton channel

The voltage-gated proton channel exists as a dimer, although each protomer has a separate conduction pathway, and when forced to exist as a monomer, most major functions are retained. However, the proton channel protomers appear to interact during gating. Proton channel dimerization is thought to result mainly from coiled-coil interaction of the intracellular C-termini. Several types of evidence are discussed that suggest that the dimer conformation may not be static, but is dynamic and can sample different orientations. Zn²⁺ appears to link the protomers in an orientation from which the channel(s) cannot open. A tandem WT-WT dimer exhibits signs of cooperative gating, indicating that despite the abnormal linkage, the correct orientation for opening can occur. We propose that C-terminal interaction functions mainly to tether the protomers together. Comparison of the properties of monomeric and dimeric proton channels speaks against the hypothesis that enhanced gating reflects monomer-dimer interconversion.Key words: voltage-gated proton channels, voltage gating, voltage-sensing domains, phagocytes, coiled-coil, oligomerization, proton currents, pH, dimerization, C-terminus     

Expression of CD1d molecules by human schwann cells and potential interactions with immunoregulatory invariant NK T cells

CD1d-restricted NKT cells expressing invariant TCR alpha-chains (iNKT cells) produce both proinflammatory and anti-inflammatory cytokines rapidly upon activation, and are believed to play an important role in both host defense and immunoregulation. To address the potential implications of iNKT cell responses for infectious or inflammatory diseases of the nervous system, we investigated the expression of CD1d in human peripheral nerve. We found that CD1d was expressed on the surface of Schwann cells in situ and on primary or immortalized Schwann cell lines in culture. Schwann cells activated iNKT cells in a CD1d-dependent manner in the presence of alpha-galactosylceramide. Surprisingly, the cytokine production of iNKT cells stimulated by alpha-galactosylceramide presented by CD1d+ Schwann cells showed a predominance of Th2-associated cytokines such as IL-5 and IL-13 with a marked deficiency of proinflammatory Th1 cytokines such as IFN-gamma or TNF-alpha. Our findings suggest a mechanism by which iNKT cells may restrain inflammatory responses in peripheral nerves, and raise the possibility that the expression of CD1d by Schwann cells could be relevant in the pathogenesis of infectious and inflammatory diseases of the peripheral nervous system.     

hierfstat,a package for r to compute and test hierarchical F‐statistics

The package hierfstat for the statistical software r , created by the R Development Core Team, allows the estimate of hierarchical F‐statistics from a hierarchy with any numbers of levels. In addition, it allows testing the statistical significance of population differentiation for these different levels, using a generalized likelihood‐ratio test. The package hierfstat is available at http://www.unil.ch/popgen/softwares/hierfstat.htm .     

Regeneration of multiple shoots from transgenic potato events facilitates the recovery of phenotypically normal lines: assessing a cry9Aa2 gene conferring insect resistance

Background

Tools for authenticating cell lines are critical for quality control in cell-based biological experiments. Currently there are methods to authenticate human cell lines using short tandem repeat (STR) markers based on the technology and procedures successfully used in the forensic community for human identification, but there are no STR based methods for authenticating nonhuman cell lines to date. There is significant homology between the human and vervet monkey genome and we utilized these similarities to design the first multiplex assay based on human STR markers for vervet cell line identification.

Results

The following STR markers were incorporated into the vervet multiplex PCR assay: D17S1304, D5S1467, D19S245, D1S518, D8S1106, D4S2408, D6S1017, and DYS389. The eight markers were successful in uniquely identifying sixty-two vervet monkey DNA samples and confirmed that Vero76 cells and COS-7 cells were derived from Vero and CV-1 cells, respectively. The multiplex assay shows specificity for vervet DNA within the determined allele range for vervet monkeys; however, the primers will also amplify human DNA for each marker resulting in amplicons outside the vervet allele range in several of the loci. The STR markers showed genetic stability in over sixty-nine passages of Vero cells, suggesting low mutation rates in the targeted STR sequences in the Vero cell line.

Conclusions

A functional vervet multiplex assay consisting of eight human STR markers with heterozygosity values ranging from 0.53-0.79 was successful in uniquely identifying sixty-two vervet monkey samples. The probability of a random match using these eight markers between any two vervet samples is approximately 1 in 1.9 million. While authenticating a vervet cell line, the multiplex assay may also be a useful indicator for human cell line contamination since the assay is based on human STR markers.     

金属框架结构材料MOF-199对漆酶的固定化及其性质

以金属框架结构材料MOF-199为载体对漆酶进行固定化,并对固定化酶的性质进行初步研究。首先,以3-氨基丙基三乙氧基硅烷对载体MOF-199进行表面氨基化修饰,再用戊二醛对载体进行活化,最后对漆酶进行固定化。固定化条件优化结果表明:在漆酶质量浓度0.3 g/L,戊二醛用量1%(体积分数),pH 4.8下固定7 h,制得固定化酶活性最高。对固定化酶的研究发现:最适反应温度为40℃,最适pH为5.2,在连续操作7次后,固定化酶的活力仍能保持在51%。固定化漆酶热稳定性,pH耐受性,贮存稳定性均明显高于游离漆酶。     

Poster Sessions BP02: Oligodendrocytes and Schwann Cells. RAS activation regulates angiogenic and anti‐angiogenic factor expression in NF1‐derived Schwann cells

Neurofibromatosis Type 1 tumors are highly vascularized and contain Schwann cells with hyperactivated Ras. In vitro, the NF1‐derived neurofibromin deficient Schwann cells have an angiogenic profile, which favors angiogenesis and sustains the growth of the NF1‐derived tumors. This study examined the relationship of the activation state of Ras as it related to the expression of angiogenic and antiangiogenic factors in both cultured NF1‐derived Schwann cells and normal human Schwann cells. Western blot analysis of normal human Schwann cells revealed low expression of angiogenic vascular endothelial growth factor (VEGF) as well as low expression of the antiangiogenic pigment epithelium derived factor (PEDF). Relative to normal human Schwann cells, NF1‐derived Schwann cells have increased RAS activity and a three‐fold increase in VEGF expression. Surprisingly, PEDF was also expressed in the NF1‐derived Schwann cells at approximately the same level as VEGF expression. Using a retroviral construct, we introduced the GAP‐related domain of neurofibromin into the NF1‐derived Schwann cells to reduce the level of activated Ras. Relative to the untreated NF1‐derived Schwann cells the Schwann cells expressing the GAP‐related domain expressed about one‐half the VEGF but twice the PEDF. We conclude that decreasing the Ras activity in NF1‐drived Schwann cells will not only decrease proliferation, but also slow tumor angiogenesis due to the decreased expression of angiogenic and increased expression of antiangiogenic factors.     

TRAINING NEEDS ASSESSMENT IN RESEARCH ETHICS EVALUATION AMONG RESEARCH ETHICS COMMITTEE MEMBERS IN THREE AFRICAN COUNTRIES: CAMEROON,MALI AND TANZANIA

Background: As actors with the key responsibility for the protection of human research participants, Research Ethics Committees (RECs) need to be competent and well‐resourced in order to fulfil their roles. Despite recent programs designed to strengthen RECs in Africa, much more needs to be accomplished before these committees can function optimally. Objective: To assess training needs for biomedical research ethics evaluation among targeted countries. Methods: Members of RECs operating in three targeted African countries were surveyed between August and November 2007. Before implementing the survey, ethical approvals were obtained from RECs in Switzerland, Cameroon, Mali and Tanzania. Data were collected using a semi‐structured questionnaire in English and in French. Results: A total of 74 respondents participated in the study. The participation rate was 68%. Seventy one percent of respondents reported having received some training in research ethics evaluation. This training was given by national institutions (31%) and international institutions (69%). Researchers and REC members were ranked as the top target audiences to be trained. Of 32 topics, the top five training priorities were: basic ethical principles, coverage of applicable laws and regulations, how to conduct ethics review, evaluating informed consent processes and the role of the REC. Conclusion: Although the majority of REC members in the targeted African countries had received training in ethics, they expressed a need for additional training. The results of this survey have been used to design a training program in research ethics evaluation that meets this need.