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1.
In order to study intact red cell membrane skeletons, we developed two methods for the electron microscopic study of stress-ruptured and partially opened glutaraldehyde pre-fixed Triton shells of red cell ghosts. Both methods showed continuous networks of fine filaments decorated and apparently crosslinked by elongated particles. Our electron micrographs show a filamentous component that is morphologically consistent with F-actin. Quantitative considerations, including the dimensions of the elongated particles and published estimates of the number of particles in situ, suggest that compact spectrin decamers or dodecamers may exist in intact red cells. Long filaments consistent with F-actin appear to be decorated with the putative spectrin particles. 相似文献
2.
The Drosophila melanogaster gene flightless-I, involved in gastrulation and
muscle degeneration, has Caenorhabditis elegans and human homologues. In
these highly conserved genes, two previously known gene families have been
brought together, families encoding the actin- binding proteins related to
gelsolin and the leucine-rich-repeat (LRR) group of proteins involved in
protein-protein interactions. Both these gene families exhibit
characteristics of molecular changes involving replication slippage and
exon shuffling. Phylogenetic analyses of 19 amino acid sequences of 6
related protein types indicate that actin- associated proteins related to
gelsolin are monophyletic to a common ancestor and include flightless
proteins. Conversely, comparison of 24 amino acid sequences of LRR proteins
including the flightless proteins indicates that flightless proteins are
members of a structurally related subgroup. Included in the flightless
cluster are human and mouse rsp-1 proteins involved in suppressing v-Ras
transformation of cells and the membrane-associated yeast (Saccharomyces
cerevisae) adenylate cyclase whose analogous LRRs are required for
interaction with Ras proteins. There is a strong possibility that ligands
for this group could be related and that flightless may have a similar role
in Ras signal transduction. It is hypothesized that an ancestral monomeric
gelsolin precursor protein has undergone at least four independent gene
reorganization events to account for the structural diversity of the extant
family of gelsolin-related proteins and that gene duplication and exon
shuffling events occurred prior to or at the beginning of multicellular
life, resulting in the evolution of some members of the family soon after
the appearance of actin-type proteins.
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3.
Magnesium-induced inner membrane aggregation in heart mitochondria: prevention and reversal by carboxyatractyloside and bongkrekic acid
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Mg(2+) at an optimal concentration of 2mM (ph 6.5) induces large increases (up to 30 percent) in the optical density of bovine heart mitochondria incubated under conditions of low ionic strength (< approx. 0.01). The increases are associated with aggregation (sticking together) of the inner membranes and are little affected by changes in the energy status of the mitochondria. Virtually all of a number of other polyvalent cations tested and Ag(+) induce increases in mitochondrial optical density similar to those induced by Mg(2+), their approximate order of concentration effectiveness in respect to Mg(2+) being: La(3+) > Pb(2+) = Cu(2+) > Cd(2+) > Zn(2+) > Ag(+) > Mn(2+) > Ca(2+) > Mg(2+). With the exception of Mg(2+), all of these cations appear to induce swelling of the mitochondria concomitant with inner membrane aggregation. The inhibitors of the adenine nucleotide transport reaction carboxyatratyloside and bongkrekic acid are capable of preventing and reversing Mg(2+)-induced aggregation at the same low concentration required for complete inhibition of phosphorylating respiration, suggesting that they inhibit the aggregation by binding to the adenine nucleotide carrier. The findings are interpreted to indicate (a) that the inner mitochondrial membrane is normally prevented from aggregating by virtue of its net negative outer surface change, (b) that the cations induce the membrane to aggregate by binding at its outer surface, decreasing the net negative charge, and (c) that carboxyatractyloside and bongkrekic acid inhibit the aggregation by binding to the outer surface of the membrane, increasing the net negative charge. 相似文献
4.
CD40 is thought to play a central role in T cell-dependent humoral responses through two distinct mechanisms. CD4+ T helper cells are activated via CD40-dependent Ag presentation in which CD80/CD86 provides costimulation through CD28. In addition, engagement of CD40 on B cells provides a direct pathway for activation of humoral responses. We used a model of adenovirus-mediated gene transfer of beta-galactosidase (lacZ) into murine lung to evaluate the specific CD40-dependent pathways required for humoral immunity at mucosal surfaces of the lung. Animals deficient in CD40L failed to develop T and B cell responses to vector. Activation of Th2 cells, which normally requires CD40-dependent stimulation of APCs, was selectively reconstituted in CD40 ligand-deficient mice by systemic administration of an Ab that is agonistic to CD28. Surprisingly, this resulted in the development of a functional humoral response to vector as evidenced by formation of germinal centers and production of antiadenovirus IgG1 and IgA that neutralized and prevented effective readministration of vector. The CD28-dependent B cell response required CD4+ T cells and was mediated via IL-4. These studies indicate that CD40 signals to the B cells are not necessary for CD4+ Th2 cell-dependent humoral responses to be generated. 相似文献
5.
Rates and patterns of evolution in partial sequences of five mitochondrial
genes (cytochrome b, ATPase 6, NADH dehydrogenase subunit 5, tRNA(Glu), and
the control region) were compared among taxa in the passerine bird genera
Fringilla and Carduelis. Rates of divergence do not vary significantly
among genes, even in comparisons with the control region. Rate variation
among lineages is significant only for the control region and NADH
dehydrogenase subunit 5, and patterns of variation are consistent with the
expectations of neutral theory. Base composition is biased in all genes but
is stationary among lineages, and there is evidence for directional
mutation pressure only in the control region. Despite these similarities,
patterns of substitution differ among genes, consistent with alternative
regimes of selective constraint. Rates of nonsynonymous substitution are
higher in NADH dehydrogenase subunit 5 than in other protein-coding genes,
and transitions exist in elevated proportions relative to transversions.
Transitions appear to accumulate linearly with time in tRNA(Glu), and
despite exhibiting the highest overall rate of divergence among species,
there are no transversional changes in this gene. Finally, for resolving
phylogenetic relationships among Fringilla taxa, the combined
protein-coding data are broadly similar to those of the control region in
terms of phylogenetic informativeness and statistical support.
相似文献
6.
7.
Hendrik-Jan Megens Richard PMA Crooijmans John WM Bastiaansen Hindrik HD Kerstens Albart Coster Ruud Jalving Addie Vereijken Pradeepa Silva William M Muir Hans H Cheng Olivier Hanotte Martien AM Groenen 《BMC genetics》2009,10(1):1-11
Background
Toll like receptors (TLR) play the central role in the recognition of pathogen associated molecular patterns (PAMPs). Mutations in the TLR1, TLR2 and TLR4 genes may change the ability to recognize PAMPs and cause altered responsiveness to the bacterial pathogens.Results
The study presents association between TLR gene mutations and increased susceptibility to Mycobacterium avium subsp. paratuberculosis (MAP) infection. Novel mutations in TLR genes (TLR1- Ser150Gly and Val220Met; TLR2 – Phe670Leu) were statistically correlated with the hindrance in recognition of MAP legends. This correlation was confirmed subsequently by measuring the expression levels of cytokines (IL-4, IL-8, IL-10, IL-12 and IFN-γ) in the mutant and wild type moDCs (mocyte derived dendritic cells) after challenge with MAP cell lysate or LPS. Further in silico analysis of the TLR1 and TLR4 ectodomains (ECD) revealed the polymorphic nature of the central ECD and irregularities in the central LRR (leucine rich repeat) motifs.Conclusion
The most critical positions that may alter the pathogen recognition ability of TLR were: the 9th amino acid position in LRR motif (TLR1–LRR10) and 4th residue downstream to LRR domain (exta-LRR region of TLR4). The study describes novel mutations in the TLRs and presents their association with the MAP infection. 相似文献8.
9.
THE EXPRESSION OF APELIN AND ITS RECEPTOR APJ DURING DIFFERENT PHYSIOLOGICAL STAGES IN THE BOVINE OVARY 总被引:1,自引:0,他引:1
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Stefanie Schilffarth Bernadette Antoni Dieter Schams Heinrich HD Meyer Bajram Berisha 《International journal of biological sciences》2009,5(4):344-350
Recent studies implicate that apelin and its receptor APJ may have important role for the modulation of angiogenesis. The aim of this study was to further characterise the regulation of apelin/APJ system in bovine ovary. Experiment 1: corpora lutea (CL) were assigned to the following stages: days 1-2, 3-4, 5-7, 8-12, 13-16, >18 (after regression) of oestrous cycle and of gravidity (month <3, 3-5, 6-7 and >8). Experiment 2: Follicles during maturation were divided into granulosa cells (GC) and theca interna (TI) and were examined separately. Classification of follicles occurred by follicle size and oestradiol-17β (E2) concentration in the follicular fluid (FF) (<0.5 ng/ml, 0.5-5 ng/ml; 5-40 ng/ml; 40-180 ng/ml; >180 ng/ml). Real-time RT-PCR (qPCR) was applied to investigate mRNA expression of examined factors. In general, the expression level of apelin during the oestrous cycle was significantly higher compared to the one during pregnancy. Apelin mRNA levels were always high during the cycle with a tendency of decrease after CL regression. The APJ mRNA in the CL was significantly up regulated on days 5-7 and 8-12 followed by a decrease on days 13-16, and further on days >18. The expression of APJ does not show any significant regulation in the CL throughout pregnancy. The expression of apelin and APJ was not statistically regulated in GC, but was significantly up regulated in follicles with an E2 concentration of more than 5 ng/ml and showed an increase according to growth and maturation of follicles. In conclusion, our data suggest that apelin/APJ system is involved in the mechanism regulating angiogenesis during follicle maturation as well as during CL formation and function in the bovine ovary. 相似文献
10.
Oi K Davies WR Tazelaar HD Bailey KR Federspiel MJ Russell SJ McGregor CG 《The journal of gene medicine》2006,8(7):795-803
BACKGROUND: To facilitate the application of adenoviral gene therapy in clinical heart transplantation, we developed an ex vivo hypothermic recirculatory adenoviral gene transfer method to the transplanted pig heart. METHODS: Experimental animals were assigned into three groups; controls, 1x10(8) plaque-forming units (pfu)/ml group and 1x10(9) pfu/ml group. During the 30 min gene transfer perfusion, 200 ml of University of Wisconsin solution containing the adenoviral vector was recirculated through the coronary vessels. The myocardial temperature was maintained below 4 degrees C and the perfusion pressure was adjusted at 50 mmHg. RESULTS: Cardiac myocyte transduction efficiencies in the 1x10(8) pfu/ml group were 0.04% and 0.07%, whereas transduction efficiencies in the 1x10(9) pfu/ml group were widely distributed from 0.45% to 22.62%. The gene transduction efficiency increased with the virus titer. Additionally, no difference in the transduction efficiency was observed between different segments of the left ventricle. The current gene transfer method at 1x10(9) pfu/ml of adenovirus titer enabled homogeneous gene transduction into the transplanted pig heart up to a maximum of 22.62%. CONCLUSIONS: This model can be applied to a large isolated heart and will greatly facilitate the investigation of gene therapy in large animal models of heart transplantation. 相似文献