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1.
L-Lactate dehydrogenase (L-LDH, E.C. 1.1.1.27) is encoded by two or three loci in all vertebrates examined, with the exception of lampreys, which have a single LDH locus. Biochemical characterizations of LDH proteins have suggested that a gene duplication early in vertebrate evolution gave rise to Ldh-A and Ldh-B and that an additional locus, Ldh-C arose in a number of lineages more recently. Although some phylogenetic studies of LDH protein sequences have supported this pattern of gene duplication, others have contradicted it. In particular, a number of studies have suggested that Ldh-C represents the earliest divergence among vertebrate LDHs and that it may have diverged from the other loci well before the origin of vertebrates. Such hypotheses make explicit statements about the relationship of vertebrate and invertebrate LDHs, but to date, no closely related invertebrate LDH sequences have been available for comparison. We have attempted to provide further data on the timing of gene duplications leading to multiple vertebrate LDHs by determining the cDNA sequence of the LDH of the tunicate Styela plicata. Phylogenetic analyses of this and other LDH sequences provide strong support for the duplications giving rise to multiple vertebrate LDHs having occurred after vertebrates diverged from tunicates. The timing of these LDH duplications is consistent with data from a number of other gene families suggesting widespread gene duplication near the origin of vertebrates. With respect to the relationships among vertebrate LDHs, our data are not consistent with previous claims that Ldh-C represented the earliest divergence. However, the precise relationships among some of the main lineages of vertebrate LDHs were not resolved in our analyses.   相似文献   
2.
Growing evidence has shown that pulsed electromagnetic fields (PEMF) can modulate bone metabolism in vivo and regulate the activities of osteoblasts and osteoclasts in vitro. Osteocytes, accounting for 95% of bone cells, act as the major mechanosensors in bone for transducing external mechanical signals and producing cytokines to regulate osteoblastic and osteoclastic activities. Targeting osteocytic signaling pathways is becoming an emerging therapeutic strategy for bone diseases. We herein systematically investigated the changes of osteocyte behaviors, functions, and its regulation on osteoclastogenesis in response to PEMF. The osteocyte-like MLO-Y4 cells were exposed to 15 Hz PEMF stimulation with different intensities (0, 5, and 30 Gauss [G]) for 2 hr. We found that the cell apoptosis and cytoskeleton organization of osteocytes were regulated by PEMF with an intensity-dependent manner. Moreover, PEMF exposure with 5 G significantly inhibited apoptosis-related gene expression and also suppressed the gene and protein expression of the receptor activator of nuclear factor κB ligand/osteoprotegerin (RANKL/OPG) ratio in MLO-Y4 cells. The formation, maturation, and osteoclastic bone-resorption capability of in vitro osteoclasts were significantly suppressed after treated with the conditioned medium from PEMF-exposed (5 G) osteocytes. Our results also revealed that the inhibition of osteoclastic formation, maturation, and bone-resorption capability induced by the conditioned medium from 5 G PEMF-exposed osteocytes was significantly attenuated after abrogating primary cilia in osteocytes using the polaris siRNA transfection. Together, our findings highlight that PEMF with 5 G can inhibit cellular apoptosis, modulate cytoskeletal distribution, and decrease RANKL/OPG expression in osteocytes, and also inhibit osteocyte-mediated osteoclastogenesis, which requires the existence of primary cilia in osteocytes. This study enriches our basic knowledge for further understanding the biological behaviors of osteocytes and is also helpful for providing a more comprehensive mechanistic understanding of the effect of electromagnetic stimulation on bone and relevant skeletal diseases (e.g., bone fracture and osteoporosis).  相似文献   
3.

Aims

Accumulation of carbon dioxide (CO2) in cucumber fermentations is known to cause hollow cavities inside whole fruits or bloaters, conducive to economic losses for the pickling industry. This study focused on evaluating the use of a malic acid decarboxylase (MDC)‐deficient starter culture to minimize CO2 production and the resulting bloater index in sodium chloride‐free cucumber fermentations brined with CaCl2.

Methods and Results

Attempts to isolate autochthonous MDC‐deficient starter cultures from commercial fermentations, using the MD medium for screening, were unsuccessful. The utilization of allochthonous MDC‐deficient starter cultures resulted in incomplete utilization of sugars and delayed fermentations. Acidified fermentations were considered, to suppress the indigenous microbiota and favour proliferation of the allochthonous MDC‐deficient Lactobacillus plantarum starter cultures. Inoculation of acidified fermentations with L. plantarum alone or in combination with Lactobacillus brevis minimally improved the conversion of sugars. However, inoculation of the pure allochthonous MDC‐deficient starter culture to 107 CFU per ml in acidified fermentations resulted in a reduced bloater index as compared to wild fermentations and those inoculated with the mixed starter culture.

Conclusions

Although use of an allochthonous MDC‐deficient starter culture reduces bloater index in acidified cucumber fermentations brined with CaCl2, an incomplete conversion of sugars is observed.

Significance and Impact of the Study

Economical losses due to the incidence of bloaters in commercial cucumber fermentations brined with CaCl2 may be reduced utilizing a starter culture to high cell density.  相似文献   
4.
Activation of the PI3K–Akt–FoxO pathway induces cell growth, whereas its inhibition reduces cell survival and, in muscle, causes atrophy. Here, we report a novel mechanism that suppresses PI3K–Akt–FoxO signaling. Although skeletal muscle lacks desmosomes, it contains multiple desmosomal components, including plakoglobin. In normal muscle plakoglobin binds the insulin receptor and PI3K subunit p85 and promotes PI3K–Akt–FoxO signaling. During atrophy, however, its interaction with PI3K–p85 is reduced by the ubiquitin ligase Trim32 (tripartite motif containing protein 32). Inhibition of Trim32 enhanced plakoglobin binding to PI3K–p85 and promoted PI3K–Akt–FoxO signaling. Surprisingly, plakoglobin overexpression alone enhanced PI3K–Akt–FoxO signaling. Furthermore, Trim32 inhibition in normal muscle increased PI3K–Akt–FoxO signaling, enhanced glucose uptake, and induced fiber growth, whereas plakoglobin down-regulation reduced PI3K–Akt–FoxO signaling, decreased glucose uptake, and caused atrophy. Thus, by promoting plakoglobin–PI3K dissociation, Trim32 reduces PI3K–Akt–FoxO signaling in normal and atrophying muscle. This mechanism probably contributes to insulin resistance during fasting and catabolic diseases and perhaps to the myopathies and cardiomyopathies seen with Trim32 and plakoglobin mutations.  相似文献   
5.
This study investigated the effect of sunlight-dark conditions on volatile fatty acids (VFAs), total ammonium nitrogen (TAN), total alkalinity (TA) and pH during pig manure (PM) digestion and then the subsequent influence on biogas yield of PM. PM1 and PM2 were performed in a transparent reactor and a non-transparent reactor, respectively. Two sets of experiments were conducted with a temperature of 35.0±2.0 °C and a total solid concentration of 8.0% to the digestion material. The dynamic change of the four parameters in response to sunlight-dark conditions resulted in variations of the physiological properties in the digester and affected the cumulative biogas production (CBP). PM1 obtained higher CBP (15020.0 mL) with a more stable pH and a lower TAN concentration (1414.5 mg/L) compared to PM2 (2675.0 mL and 1670.0 mg/L, respectively). The direct path coefficients and indirect path coefficients between the four parameters and CBP were also analyzed.  相似文献   
6.
Sorafenib is the standard first-line therapeutic treatment for patients with advanced hepatocellular carcinoma (HCC), but its use is hampered by the development of drug resistance. The activation of Akt by sorafenib is thought to be responsible for this resistance. Bufalin is the major active ingredient of the traditional Chinese medicine Chan su, which inhibits Akt activation; therefore, Chan su is currently used in the clinic to treat cancer. The present study aimed to investigate the ability of bufalin to reverse both inherent and acquired resistance to sorafenib. Bufalin synergized with sorafenib to inhibit tumor cell proliferation and induce apoptosis. This effect was at least partially due to the ability of bufalin to inhibit Akt activation by sorafenib. Moreover, the ability of bufalin to inactivate Akt depended on endoplasmic reticulum (ER) stress mediated by inositol-requiring enzyme 1 (IRE1). Silencing IRE1 with siRNA blocked the bufalin-induced Akt inactivation, but silencing eukaryotic initiation factor 2 (eIF2) or C/EBP-homologous protein (CHOP) did not have the same effect. Additionally, silencing Akt did not influence IRE1, CHOP or phosphorylated eIF2α expression. Two sorafenib-resistant HCC cell lines, which were established from human HCC HepG2 and Huh7 cells, were refractory to sorafenib-induced growth inhibition but were sensitive to bufalin. Thus, Bufalin reversed acquired resistance to sorafenib by downregulating phosphorylated Akt in an ER-stress-dependent manner via the IRE1 pathway. These findings warrant further studies to examine the utility of bufalin alone or in combination with sorafenib as a first- or second-line treatment after sorafenib failure for advanced HCC.  相似文献   
7.
8.
Human VLDLs assembled in the liver and secreted into the circulation supply energy to peripheral tissues. VLDL lipolysis yields atherogenic LDLs and VLDL remnants that strongly correlate with CVD. Although the composition of VLDL particles has been well-characterized, their 3D structure is elusive because of their variations in size, heterogeneity in composition, structural flexibility, and mobility in solution. Here, we employed cryo-electron microscopy and individual-particle electron tomography to study the 3D structure of individual VLDL particles (without averaging) at both below and above their lipid phase transition temperatures. The 3D reconstructions of VLDL and VLDL bound to antibodies revealed an unexpected polyhedral shape, in contrast to the generally accepted model of a spherical emulsion-like particle. The smaller curvature of surface lipids compared with HDL may also reduce surface hydrophobicity, resulting in lower binding affinity to the hydrophobic distal end of the N-terminal β-barrel domain of cholesteryl ester transfer protein (CETP) compared with HDL. The directional binding of CETP to HDL and VLDL may explain the function of CETP in transferring TGs and cholesteryl esters between these particles. This first visualization of the 3D structure of VLDL could improve our understanding of the role of VLDL in atherogenesis.  相似文献   
9.
昆虫抗菌物质研究进展   总被引:23,自引:4,他引:19  
翟朝阳 《昆虫学报》1996,39(1):99-104
昆虫抗菌物质研究进展翟朝阳(华西医科大学医学分子生物学研究室成都610044)昆虫是自然界中种类和数量繁多,生长繁殖迅速的一类动物。做为在自然界中长期生存的牛物,各种昆虫在适应环岛与环境的变化上各有其独特的方式,构成一幅丰富多彩,令人惊叹的画卷,而在...  相似文献   
10.
Molecular Breeding - Apple mildew, caused by the fungus Podosphaera leucotricha, is an ongoing problem for apple growers in most world production regions. To manage apple foliar mildew with less...  相似文献   
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