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961.
Prostaglandins (PGs) play a pivotal role in maternal recognition of pregnancy and implantation in pigs. In the present study, PGE2, PGF2α, and PGFM (PGF2α metabolite) content, as well as PGE2 synthase (mPGES-1) and PGF2α synthase (PGFS) expression was investigated in early pregnant gilts with natural (n = 21) and PMSG/hCG-stimulated (n = 19) estrus. Endometrial tissue samples, uterine luminal flushings (ULFs), and blood serum were collected on days 10-11, 12, and 15 after insemination. Additionally, day 15 conceptuses were collected for mPGES-1 and PGFS protein expression. Effect of estrus induction was observed on day 15 of pregnancy, when the content of PGE2 in the uterine lumen was fourfold lower in gonadotropin-stimulated gilts in comparison to controls (P < 0.001). Decreased PGE2 content in ULFs of gonadotropin-treated pigs was preceded by lower endometrial mPGES-1 gene expression in hormonally-stimulated animals in comparison to control gilts (P < 0.01). On the other hand, estrus induction with PMSG/hCG resulted in higher PGE2 accumulation in the endometrial tissue on day 15 of pregnancy (P < 0.01). Furthermore, PGF2α content in the endometrium and PGFM levels in blood serum were lower in gonadotropin-treated gilts, especially on day 12 after insemination when compared to control gilts (P < 0.01). Finally, PGFS expression in day 15 conceptuses was decreased in animals with hormonally-induced estrus. We conclude that PMSG/hCG stimulation of prepubertal gilts to induce estrus results in changes of PG production and secretion during early pregnancy, which, in turn, may affect conceptus development, implantation, and the course of pregnancy. 相似文献
962.
Balla Sylla Karine Descroix Christophe Pain Cédric Gervaise Frank Jamois Laurent Legentil Caroline Nugier-Chauvin Richard Daniellou Vincent Ferrières 《Carbohydrate research》2010,345(10):1366-1370
It is known that 3-O-glycosylation of glucosidic acceptors bearing acyl groups in the 4 and 6 positions instead of a 4,6-O-benzylidene ring mainly affords α-glycosides. Described here is an unexpected stereochemical outcome for elongation at glucose O-3 of a β-d-Glcp-(1→3)-α-d-Manp disaccharide using peracetylated ethyl thioglucoside as a donor. This unexpected reaction was correlated with match-mismatch effects, as shown by efficient coupling of the same acceptor by a donor of l-configuration. 相似文献
963.
Jason N. Bazil Gregery T. Buzzard Ann E. Rundell 《Journal of theoretical biology》2010,265(4):672-690
Mitochondrial permeability transition (MPT) is a highly regulated complex phenomenon that is a type of ischemia/reperfusion injury that can lead to cell death and ultimately organ dysfunction. A novel population transition and detailed permeability transition pore regulation model were integrated with an existing bioenergetics model to describe MPT induction under a variety of conditions. The framework of the MPT induction model includes the potential states of the mitochondria (aggregated, orthodox and post-transition), their transitions from one state to another as well as their interaction with the extra-mitochondrial environment. The model encodes the three basic necessary conditions for MPT: a high calcium load, alkaline matrix pH and circumstances which favor de-energization. The MPT induction model was able to reproduce the expected bioenergetic trends observed in a population of mitochondria subjected to conditions that favor MPT. The model was corroborated and used to predict that MPT in an acidic environment is mitigated by an increase in activity of the mitochondrial potassium/hydrogen exchanger. The model was also used to present the beneficial impact of reducing the duration mitochondria spend in the orthodox state on preserving the extra-mitochondrial ATP levels. The model serves as a tool for investigators to use to understand the MPT induction phenomenon, explore alternative hypotheses for PTP regulation, as well as identify endogenous pharmacological targets and evaluate potential therapeutics for MPT mitigation. 相似文献
964.
Alejandra Hernández-Santoyo Luis del Pozo Yauner Deyanira Fuentes-Silva Enrique Rudiño-Piñera Eduardo Horjales Adela Rodríguez-Romero 《Journal of molecular biology》2010,396(2):280-292
Systemic amyloid light-chain (LC) amyloidosis is a disease process characterized by the pathological deposition of monoclonal LCs in tissue. All LC subtypes are capable of fibril formation although λ chains, particularly those belonging to the λ6 type, are overrepresented. Here, we report the thermodynamic and in vitro fibrillogenic properties of several mutants of the λ6 protein 6aJL2 in which Pro7 and/or His8 was substituted by Ser or Pro. The H8P and H8S mutants were almost as stable as the wild-type protein and were poorly fibrillogenic. In contrast, the P7S mutation decreased the thermodynamic stability of 6aJL2 and greatly enhanced its capacity to form amyloid-like fibrils in vitro. The crystal structure of the P7S mutant showed that the substitution induced both local and long-distance effects, such as the rearrangement of the VL (variable region of the light chain)-VL interface. This mutant crystallized in two orthorhombic polymorphs, P212121 and C2221. In the latter, a monomer that was not arranged in the typical Bence-Jones dimer was observed for the first time. Crystal-packing analysis of the C2221 lattice showed the establishment of intermolecular β-β interactions that involved the N-terminus and β-strand B and that these could be relevant in the mechanism of LC fibril formation. Our results strongly suggest that Pro7 is a key residue in the conformation of the N-terminal sheet switch motif and, through long-distance interactions, is also critically involved in the contacts that stabilized the VL interface in λ6 LCs. 相似文献
965.
MAXIMILIAN WEIGEND MARKUS ACKERMANN TILO HENNING 《Biological journal of the Linnean Society. Linnean Society of London》2010,100(1):124-131
Reward partitioning and replenishment and specific mechanisms for pollen presentation are all geared towards the maximization of the number of effective pollinator visits to individual flowers. An extreme case of an apparently highly specialized plant–pollinator interaction with thigmonastic pollen presentation has been described for the morphologically complex tilt‐revolver flowers of Caiophora arechavaletae (Loasaceae) pollinated by oligolectic Bicolletes pampeana (Colletidae, Hymenoptera). We studied the floral biology of Nasa macrothyrsa (Loasaceae) in the field and in the glasshouse, which has very similar floral morphology, but is pollinated by polylectic Neoxylocopa bees (Apidae, Hymenoptera). We investigated the presence of thigmonastic anther presentation, visitor behaviour (pollinators and nectar robbers), co‐ordination of pollinator visits with flower behaviour and the presence of nectar replenishment. The aim of this study was to understand whether complex flower morphology and behaviour can be explained by a specialized pollination syndrome, or whether alternative explanations can be offered. The results showed that Nasa macrothyrsa has thigmonastic pollen presentation, i.e. new pollen is rapidly (<< 10 min) presented after a pollinator visit. Nectar secretion is independent of removal and averages 7–14 µL h–1. The complex flowers, however, fail to exclude either native (hummingbirds) or introduced (honeybees) nectar robbers, nor does polylectic Neoxylocopa actively collect the pollen presented. The findings do not support a causal link between complex flower morphology and functionality in Loasaceae and a highly specialized pollination. Rapid pollen presentation is best explained by the pollen presentation theory: the large proportion of pollinators coming shortly after a previous visit find little nectar and are more likely to move on to a different plant. The rapid presentation of pollen ensures that all these valuable ‘hungry pollinators’ are dusted with small pollen loads, thus increasing the male fitness of the plant by increasing the likelihood of siring outcrossed offspring. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 124–131. 相似文献
966.
967.
在甘蓝型双低油菜品种与播娘蒿原生质体融合杂种的自交后代群体中,实施定向选择和品质鉴定,在F3收获的247株中筛选获得9份含油量大于45%、芥酸含量小于0.5%、硫苷含量小于30μmol/g的高油双低甘蓝型油菜新种质,其中有2份是黄籽高油双低材料,这些材料的F4仍保持高含油量双低性状。在F4群体收获的905株中新选出了15份高含油量双低油菜新种质,其中有5份是黄籽高油双低材料。因此,通过播娘蒿与油菜原生质体融合及其后代选择可以获得高含油量优质油菜新种质。 相似文献
968.
Explaining the Tragedy of the Commons of the 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 systems,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... 相似文献
969.
杜仲叶片愈伤组织诱导的激素优化研究 总被引:8,自引:0,他引:8
以杜仲优树L33的幼叶为材料,在B5培养基上添加不同浓度的生长素与细胞分裂素进行愈伤组织诱导研究,结果表明:无激素的培养基上不能诱导出愈伤组织,单独加入2,4-D、NAA和IBA均可诱导出愈伤组织,以0.5 mg·L-1 2,4-D、0.5~1.0 mg·L-1 NAA、1.0 mg·L-1 IBA出愈率最高,达100%,且愈伤组织生长较好;在适宜浓度的生长素的培养基上加入细胞分裂素时,KT的加入对愈伤组织的诱导及生长起抑制作用;1.0 mg·L-1 NAA+0.3~0.5 mg·L-1 BA与1.0 mg·L-1 IBA+0.3~0.5 mg·L-1 BA 的组合可明显促进愈伤组织的诱导和生长,适合进一步继代培养。 相似文献
970.
The effect of temperature on the formation of recombinant protein,apolipoprotein A-IMilano was investigated in the present study.The temperature of the initial growth phase was set at 30℃,while temperature variation in induction phase was arranged in three modes.High cell-density culture of Escherichia coli and high expression of recombinant human by twice temperature-shifted induction were carried out.Experimental results showed that ApoA-IMilano reached 4.8 g/L with the final cell density of OD600,150.It was found that twice temperature-shifted induction could successfully avoid the effect of acetic acid on cell density and the expression of the product.The present study provides a basic procedure for the production of recombinant ApoA-IMilano. 相似文献