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81.
Summary Lipases from plant and microbial sources were screened for lipolysis of rice bran oil (RBO). Oat lipase was found to give reproducibly 60% lipolysis. Factors affecting the efficiency of lipolysis such as oil:emulsifier ratio, duration of homogenization for the substrate preparation, substrate:enzyme ratio, substrate pH, kinetics of lipolysis and efficiency of lipase as a function of pH, oat particle size, its quality and reuseability were studied to assess the feasibility of using of oat lipase for splitting RBO commercially. The efficiency of lipolysis was optimal at (a) RBO:emulsifier (0.5:1) ratio, homogenized for 2.5 min, (b) pH 7.5 and (c) substrate:enzyme ratio of 5 ml: 2 g. 相似文献
82.
Filamentous growth is a microbial differentiation response that involves the concerted action of multiple signaling pathways. In budding yeast, one pathway that regulates filamentous growth is a Cdc42p-dependent mitogen-activated protein kinase (MAPK) pathway. Several transmembrane (TM) proteins regulate the filamentous growth pathway, including the signaling mucin Msb2p, the tetraspan osmosensor Sho1p, and an adaptor Opy2p. The TM proteins were compared to identify common and unique features. Msb2p, Sho1p, and Opy2p associated by coimmunoprecipitation analysis but showed predominantly different localization patterns. The different localization patterns of the proteins resulted in part from different rates of turnover from the plasma membrane (PM). In particular, Msb2p (and Opy2p) were turned over rapidly compared to Sho1p. Msb2p signaled from the PM, and its turnover was a rate-limiting step in MAPK signaling. Genetic analysis identified unique phenotypes of cells overexpressing the TM proteins. Therefore, each TM regulator of the filamentous growth pathway has its own regulatory pattern and specific function in regulating filamentous growth. This specialization may be important for fine-tuning and potentially diversifying the filamentation response. 相似文献
83.
Vascular endothelial growth factor (VEGF), initially detected in bovine pituitary follicular cells, is widely localized in hypertrophic zones of chondrocytes in various tissues where focus is on bone growth. Similarly, VEGF found in chondrocytes of articular cartilage of osteo-arthritic/rheumato-arthritic joints reflected need for bone repair. Members of VEGF family of human origin are seven homo-dimeric, heparin-binding glyco-proteins, encoded by different genes located on different chromosomes. They encode seven isoforms: VEGF-A, -B, -C, -D, -E, -F, and PLGF, each catalyzing distinct functions. They are compared with VEGFs derived from bovine origin in biochemical composition and functions. Each isoform and subtype has specific receptors for binding, necessary for expression of specific functions in bone growth or repair. VEGF control is by diffusion of isoforms, hypoxic conditions, and bone (mandibular) positioning. Thus, transformation of cartilage into bone involves proliferation of mesenchymal cells, hypertrophy in chondrocytes, capillary invasion, and calcification by extra cellular matrix (ECM). Inherent limitations of in vitro/in vivo models and chronology of appearance of different isoforms have eluded precise mechanism of VEGF action and regulation. Nonetheless, central role of VEGF in bone growth is quite obvious. 相似文献
84.
85.
Rangaswami H Schwappacher R Tran T Chan GC Zhuang S Boss GR Pilz RB 《The Journal of biological chemistry》2012,287(25):21509-21519
Mechanical loading of bone induces interstitial fluid flow, leading to fluid shear stress (FSS) of osteoblasts. FSS rapidly increases the intracellular calcium concentration ([Ca(2+)]) and nitric oxide (NO) synthesis in osteoblasts and activates the protein kinase Akt. Activated Akt stimulates osteoblast proliferation and survival, but the mechanism(s) leading to Akt activation is not well defined. Using pharmacological and genetic approaches in primary human and mouse osteoblasts and mouse MC3T3 osteoblast-like cells, we found that Akt activation by FSS occurred through two parallel pathways; one required calcium stimulation of NO synthase and NO/cGMP/protein kinase G II-dependent activation of Src, and the other required calcium activation of FAK and Src, independent of NO. Both pathways cooperated to increase PI3K-dependent Akt phosphorylation and were necessary for FSS to induce nuclear translocation of β-catenin, c-fos, and cox-2 gene expression and osteoblast proliferation. These data explain how mechanical stimulation of osteoblasts leads to increased signaling through a growth regulatory pathway essential for maintaining skeletal integrity. 相似文献
86.
Hypoxia regulates cross-talk between Syk and Lck leading to breast cancer progression and angiogenesis 总被引:6,自引:0,他引:6
Chakraborty G Rangaswami H Jain S Kundu GC 《The Journal of biological chemistry》2006,281(16):11322-11331
Hypoxia is a key parameter that controls tumor angiogenesis and malignant progression by regulating the expression of several oncogenic molecules. The nonreceptor protein-tyrosine kinases Syk and Lck play crucial roles in the signaling mechanism of various cellular processes. The enhanced expression of Syk in normal breast tissue but not in malignant breast carcinoma has prompted us to investigate its potential role in mammary carcinogenesis. Accordingly, we hypothesized that hypoxia/reoxygenation (H/R) may play an important role in regulating Syk activation, and Lck may be involved in this process. In this study, we have demonstrated that H/R differentially regulates Syk phosphorylation and its subsequent interaction and cross-talk with Lck in MCF-7 cells. Moreover, Syk and Lck play differential roles in regulating Sp1 activation and expressions of melanoma cell adhesion molecule (MelCAM), urokinase-type plasminogen activator (uPA), matrix metalloproteinase-9 (MMP-9), and vascular endothelial growth factor (VEGF) in response to H/R. Overexpression of wild type Syk inhibited the H/R-induced uPA, MMP-9, and VEGF expression but up-regulated MelCAM expression. Our data also indicated that MelCAM acts as a tumor suppressor by negatively regulating H/R-induced uPA secretion and MMP-9 activation. The mice xenograft study showed the cross-talk between Syk and Lck regulated H/R-induced breast tumor progression and further correlated with the expressions of MelCAM, uPA, MMP-9, and VEGF. Human clinical specimen analysis supported the in vitro and in vivo findings. To our knowledge, this is first report that the cross-talk between Syk and Lck regulates H/R-induced breast cancer progression and further suggests that Syk may act as potential therapeutic target for the treatment of breast cancer. 相似文献
87.
Comparative genomic evidence for a close relationship between the dimorphic prosthecate bacteria Hyphomonas neptunium and Caulobacter crescentus
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Badger JH Hoover TR Brun YV Weiner RM Laub MT Alexandre G Mrázek J Ren Q Paulsen IT Nelson KE Khouri HM Radune D Sosa J Dodson RJ Sullivan SA Rosovitz MJ Madupu R Brinkac LM Durkin AS Daugherty SC Kothari SP Giglio MG Zhou L Haft DH Selengut JD Davidsen TM Yang Q Zafar N Ward NL 《Journal of bacteriology》2006,188(19):6841-6850
The dimorphic prosthecate bacteria (DPB) are alpha-proteobacteria that reproduce in an asymmetric manner rather than by binary fission and are of interest as simple models of development. Prior to this work, the only member of this group for which genome sequence was available was the model freshwater organism Caulobacter crescentus. Here we describe the genome sequence of Hyphomonas neptunium, a marine member of the DPB that differs from C. crescentus in that H. neptunium uses its stalk as a reproductive structure. Genome analysis indicates that this organism shares more genes with C. crescentus than it does with Silicibacter pomeroyi (a closer relative according to 16S rRNA phylogeny), that it relies upon a heterotrophic strategy utilizing a wide range of substrates, that its cell cycle is likely to be regulated in a similar manner to that of C. crescentus, and that the outer membrane complements of H. neptunium and C. crescentus are remarkably similar. H. neptunium swarmer cells are highly motile via a single polar flagellum. With the exception of cheY and cheR, genes required for chemotaxis were absent in the H. neptunium genome. Consistent with this observation, H. neptunium swarmer cells did not respond to any chemotactic stimuli that were tested, which suggests that H. neptunium motility is a random dispersal mechanism for swarmer cells rather than a stimulus-controlled navigation system for locating specific environments. In addition to providing insights into bacterial development, the H. neptunium genome will provide an important resource for the study of other interesting biological processes including chromosome segregation, polar growth, and cell aging. 相似文献
88.
89.
Joseph Selvin S. Shanmughapriya R. Gandhimathi G. Seghal Kiran T. Rajeetha Ravji K. Natarajaseenivasan T. A. Hema 《Applied microbiology and biotechnology》2009,83(3):435-445
The sponge-associated actinomycetes were isolated from the marine sponge Dendrilla nigra, collected from the southwest coast of India. Eleven actinomycetes were isolated depending upon the heterogeneity and stability
in subculturing. Among these, Nocardiopsis dassonvillei MAD08 showed 100% activity against the multidrug resistant pathogens tested. The culture conditions of N. dassonvillei MAD08 was optimized under submerged fermentation conditions for enhanced antimicrobial production. The unique feature of
MAD08 includes extracellular amylase, cellulase, lipase, and protease production. These enzymes ultimately increase the scope
of optimization using broad range of raw materials which might be efficiently utilized. The extraction of the cell free supernatant
with ethyl acetate yielded bioactive crude extract that displayed activity against a panel of pathogens tested. Analysis of
the active thin layer chromatography fraction by Fourier transform infrared and gas chromatography-mass spectrometry evidenced
11 compounds with antimicrobial activity. The ammonium sulfate precipitation of the culture supernatant at 80% saturation
yielded an anticandidal protein of molecular weight 87.12 kDa. This is the first strain that produces both organic solvent
and water soluble antimicrobial compounds. The active extract was non-hemolytic and showed surface active property envisaging
its probable role in inhibiting the attachment of pathogens to host tissues, thus, blocking host–pathogen interaction at an
earlier stage of pathogenesis. 相似文献
90.
Joseph Selvin R. Gandhimathi G. Seghal Kiran S. Shanmugha Priya T. Rajeetha Ravji T. A. Hema 《Helgoland Marine Research》2009,63(3):239-247
Culturable heterotrophic bacterial composition of marine sponge Dendrilla nigra was analysed using different enrichments. Five media compositions including without enrichment (control), enriched with sponge
extract, with growth regulator (antibiotics), with autoinducers, and complete enrichment containing sponge extract, antibiotics,
and autoinducers were developed. DNA hybridization assay was performed to explore host specific bacteria and ecotypes of culturable
sponge-associated bacteria. Enrichment with selective inducers (AHLs and sponge extract) and regulators (antibiotics) considerably
enhanced the cultivation potential of sponge-associated bacteria. It was found that Marinobacter (MSI032), Micromonospora (MSI033), Streptomyces (MSI051), and Pseudomonas (MSI057) were sponge-associated obligate symbionts. The present findings envisaged that “Micromonospora–Saccharomonospora–Streptomyces” group was the major culturable actinobacteria in the marine sponge D. nigra. The DNA hybridization assay was a reliable method for the analysis of culturable bacterial community in marine sponges.
Based on the culturable community structure, the sponge-associated bacteria can be grouped (ecotypes) as general symbionts,
specific symbionts, habitat flora, and antagonists. 相似文献