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Karlheinz Grillitsch Pablo Tarazona Lisa Klug Tamara Wriessnegger Günther Zellnig Erich Leitner Ivo Feussner Günther Daum 《生物化学与生物物理学报:生物膜》2014
Despite similarities of cellular membranes in all eukaryotes, every compartment displays characteristic and often unique features which are important for the functions of the specific organelles. In the present study, we biochemically characterized the plasma membrane of the methylotrophic yeast Pichia pastoris with emphasis on the lipids which form the matrix of this compartment. Prerequisite for this effort was the design of a standardized and reliable isolation protocol of the plasma membrane at high purity. Analysis of isolated plasma membrane samples from P. pastoris revealed an increase of phosphatidylserine and a decrease of phosphatidylcholine compared to bulk membranes. The amount of saturated fatty acids in the plasma membrane was higher than in total cell extracts. Ergosterol, the final product of the yeast sterol biosynthetic pathway, was found to be enriched in plasma membrane fractions, although markedly lower than in Saccharomyces cerevisiae. A further characteristic feature of the plasma membrane from P. pastoris was the enrichment of inositol phosphorylceramides over neutral sphingolipids, which accumulated in internal membranes. The detailed analysis of the P. pastoris plasma membrane is discussed in the light of cell biological features of this microorganism especially as a microbial cell factory for heterologous protein production. 相似文献
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Márcia M. Medeiros Henrique B. da Silva Aramys S. Reis Renato Barboza Joanne Thompson Maria Regina D'Império Lima Cláudio R. F. Marinho Carlos E. Tadokoro 《PloS one》2013,8(11)
It is postulated that accumulation of malaria-infected Red Blood Cells (iRBCs) in the liver could be a parasitic escape mechanism against full destruction by the host immune system. Therefore, we evaluated the in vivo mechanism of this accumulation and its potential immunological consequences. A massive liver accumulation of P. c. chabaudi AS-iRBCs (Pc-iRBCs) was observed by intravital microscopy along with an over expression of ICAM-1 on day 7 of the infection, as measured by qRT-PCR. Phenotypic changes were also observed in regulatory T cells (Tregs) and dendritic cells (DCs) that were isolated from infected livers, which indicate a functional role for Tregs in the regulation of the liver inflammatory immune response. In fact, the suppressive function of liver-Tregs was in vitro tested, which demonstrated the capacity of these cells to suppress naive T cell activation to the same extent as that observed for spleen-Tregs. On the other hand, it is already known that CD4+ T cells isolated from spleens of protozoan parasite-infected mice are refractory to proliferate in vivo. In our experiments, we observed a similar lack of in vitro proliferative capacity in liver CD4+ T cells that were isolated on day 7 of infection. It is also known that nitric oxide and IL-10 are partially involved in acute phase immunosuppression; we found high expression levels of IL-10 and iNOS mRNA in day 7-infected livers, which indicates a possible role for these molecules in the observed immune suppression. Taken together, these results indicate that malaria parasite accumulation within the liver could be an escape mechanism to avoid sterile immunity sponsored by a tolerogenic environment. 相似文献
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Stereometry in very close-range stereophotogrammetry with non-metric cameras for human movement analysis 总被引:1,自引:0,他引:1
In this paper a stereophotogrammetric algorithm based on a black-box approach to the modelling of object to image spaces relationship is proposed. The algorithm is well suited for 'very close-range photogrammetry', with respect to experiments in which the measurement field is 0.5 X 0.5 X 0.5 m or smaller, as in the analysis of a few or small body segments movements. The attainable accuracy is high, better than 0.1% of the observation distance. Non-professional and even different cameras can be used. Consequently an inexpensive experimental set-up can be realized. A very simple, cheap and easily usable calibration object is needed. Computation time for the reconstruction of object-space co-ordinates of point body landmarks is one order of magnitude lower than in the case of the Direct Linear Transformation (DLT) (Abdel Aziz and Karara, Proceedings of the ASP/U1 Symposium on Close-Range Photogrammetry, pp. 1-18. American Society of Photogrammetry, 1971; Marzan and Karara, Proceedings of the Symposium on close-range Photogrammetric Systems, pp. 420-467. American Society of Photogrammetry, 1975). Computation time for calibration is two-fold in respect of the DLT. An example of application to the recording of the movements of the index finger with respect to the metacarpophalangeal joint is given. 相似文献
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Parthenogenesis in Tubificidae 总被引:2,自引:2,他引:0
Tamara L. Poddubnaya 《Hydrobiologia》1984,115(1):97-99
The ability of tubificids to reproduce parthenogenetically following or in place of bisexual reproduction has been proved. During parthenogenesis the spermatogenesis ceases at an early stage of sexual cell development, which, together with some peculiarities of the structure of the sexual system, rules out the possibility of self-fertilization in the worms. For two years of cultivation the life cycles of 3 parthenogenetic generations in Tubifex tubifex and 2 in Limnodrilus hoffmeisteri were traced. 相似文献
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