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Culture Growth (culture + growth)
Selected AbstractsIsolation and characterization of a Lactobacillus amylovorus mutant depleted in conjugated bile salt hydrolase activity: relation between activity and bile salt resistanceJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2000J.P. Grill Growth experiments were conducted on Lactobacillus amylovorus DN-112 053 in batch culture, with or without pH regulation. Conjugated bile salt hydrolase (CBSH) activity was examined as a function of culture growth. The CBSH activity increased during growth but its course depended on bile salts type and culture conditions. A Lact. amylovorus mutant was isolated from the wild-type strain of Lact. amylovorus DN-112 053 after mutagenesis with N-methyl-N,-nitro-N-nitrosoguanidine. An agar plate assay was used to detect mutants without CBSH activity. In resting cell experiments, the strain showed reduced activity. Differences between growth parameters determined for wild-type and mutant strains were not detected. Comparative native gel electrophoresis followed by CBSH activity staining demonstrated the loss of proteins harbouring this activity in the mutant. Four protein bands corresponding to CBSH were observed in the wild-type strain but only one was detected in the mutant. The specific growth rate of the mutant strain was affected more by bile salts than the wild-type strain. Nevertheless, bile was more toxic for the wild-type strain. In viability studies in the presence of nutrients, it was demonstrated that glycodeoxycholic acid exerted a higher toxicity than taurodeoxycholic acid in a pH-dependent manner. No difference was apparent between the two strains. In the absence of nutrients, the wild-type strain died after 2 h whereas no effect was observed for the mutant. The de-energization experiments performed using the ionophores nigericin and valinomycin suggested that the chemical potential of protons (Z,pH) was involved in Lactobacillus bile salt resistance. [source] Effect of growth hormone on in vitro osteogenesis and gene expression of human osteoblastic cells is donor-age-dependentJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2008Grasiele E. Crippa Abstract It has been demonstrated that the effect of GH on bone tissue is reduced with aging. In this study we tested the hypothesis that the action of GH on osteoblastic cells is donor-age-dependent by investigating the effect of GH on the development of osteoblastic phenotype in cultures of cells from adolescents (13,16 years old), young adults (18,35 years old), and adults (36,49 years old). Osteoblastic cells derived from human alveolar bone were cultured with or without GH for periods of up to 21 days, and parameters of in vitro osteogenesis and gene expression of osteoblastic markers were evaluated. GH increased culture growth, collagen content and alkaline phosphatase (ALP) activity in cultures from adolescents and young adults, whereas non-significant effect was observed in cultures from adults. While GH significantly increased the bone-like formation in cultures from adolescents, a slightly effect was observed in cultures from young adults and no alteration was detected in cultures from adults. Results from real-time PCR demonstrated that GH upregulated ALP, osteocalcin, type I collagen, and Cbfa1 mRNA levels in cultures from adolescents. In addition, cultures from young adults showed higher ALP mRNA expression and the expression of all evaluated genes was not affected by GH in cultures from adults. These results indicate that the GH effect on both in vitro osteogenesis and gene expression of osteoblastic markers is donor-age-dependent, being more pronounced on cultures from adolescents. J. Cell. Biochem. 104: 369,376, 2008. © 2007 Wiley-Liss, Inc. [source] Comparison of Texture of Yogurt Made from Conventionally Treated Milk and UHT Milk Fortified with Low-heat Skim Milk PowderJOURNAL OF FOOD SCIENCE, Issue 6 2004W. Krasaekoopt ABSTRACT: The textures of yogurt made from ultra-high temperature (UHT) treated and conventionally treated milks at high total solids were investigated. The yogurt premixes, fortified with low-heat skim milk powder to 16%, 18%, and 20% total solids, were UHT processed at 143°C for 6 s and heated at 85°C for 30 min using the conventional method. The onset of gelation was delayed in the UHT-processed milk compared with conventionally heated milk. During fermentation, the viscosity of yogurt made from UHT-treated milk at 20% total solids was close to that of yogurt made from conventionally treated milk with 16% total solids. However, after storage for , 1 d, the yogurt made from UHT-treated milk had lower viscosity and gel strength than the yogurt made from conventionally treated milk. The solids level had no influence on yogurt culture growth. [source] Simulation of microalgae growth in limiting light conditions: Flow effectAICHE JOURNAL, Issue 5 2002J. Pruvost Effect of hydrodynamical conditions on a microalgae culture growth was investigated in a photobioreactor with annular light chambers, with the focus on the relation between the cell displacement and the amount of light received by microorganisms, by comparing two different flow conditions in light chambers: an axial flow generating a poor radial mixing and a 3-D swirling motion. To determine microorganism trajectories, a Lagrangian approach was retained, allowing light received to be considered from a single microalga point of view. The light distribution was calculated using Beer,Lambert law, and a biological modeling of the culture growth was proposed, with consideration of light/dark cycle effects induced by cell displacement in the depth of the culture. Finally, batch cultures of Porphyridium purpureum were simulated for both hydrodynamical conditions in light chambers. The advantage of applying a three-dimensional motion to generate cell renewal in front of the light source, allowing microorganisms to use light more efficiently, is clearly shown. [source] VP22-mediated intercellular transport correlates with enhanced biological activity of MybEngrailed but not (HSV-I) thymidine kinase fusion proteins in primary vascular cells following non-viral transfectionTHE JOURNAL OF GENE MEDICINE, Issue 3 2005Paul J. Sheridan Background The intercellular transport properties of the herpes simplex virus (HSV) protein VP22 have been harnessed to enhance the effectiveness of viral gene transfer. We investigated the intercellular transport and biological effects of VP22 fused with the dominant negative c-Myb chimera, MybEngrailed (MybEn) and HSV-I thymidine kinase (TK), in primary vascular smooth muscle cells (VSMC) following non-viral transfection. Materials and methods Porcine VSMC transfected with plasmids encoding MybEn, TK and their respective N- and C-terminal VP22 fusion proteins were assayed for the extent and distribution of transgene expression (by immunohistochemistry), culture growth and apoptosis. Results The N-terminal MybEn fusion with VP22 (MybEnVP22) and both TK fusions, but not VP22MybEn, exhibited intercellular spread from primary transfected to up to 200 surrounding cells. pMybEnVP22 -transfected cultures exhibited growth inhibition and apoptosis rates that were 10.6 ± 3.6 and 3.2 ± 1.0 fold higher than in pMybEn -transfected cultures; pVP22MybEn -transfected cultures showed no difference in these parameters. pTK -transfected cultures underwent 60,70% cell death in the presence of ganciclovir despite <2% primary transfection, which was not increased in cultures transfected with plasmids encoding VP22-TK fusions. Conclusions The close correlation between immunocytochemical and biological assays suggests that intercellular transport is crucial to the enhanced biological activity of the MybEnVP22 fusion. The ,intrinsic' bystander activity of TK was 4-fold greater than was ,engineered' by VP22 fusion, probably reflecting the abundance of gap junctions between VSMC. VP22 fusion may enhance the efficiency of non-viral gene delivery when combined with the appropriate therapeutic transgene, target tissue and transfection method. Copyright © 2004 John Wiley & Sons, Ltd. [source] IL-1 Activity is Expressed Differently During Pregnancy in the Rat Uterine Artery than in Aortic or Uterine TissuesAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 3 2002Mahmoud Huleihel PROBLEM:,Uterine artery was shown to be unique in its capacity to change in size and function during pregnancy. As interleukin-1 (IL-1) was shown to be involved in reproduction processes, the aim of this study was to determine the levels of IL-1 activity of the uterine artery tissue in pregnant rat. METHOD OF STUDY:,Nine virgins and nine midpregnant rats were selected. Both uterine arteries were obtained, together with reference tissues from aorta and uterus. The levels of IL-1 were examined in the above tissues after culturing with media alone (control; CT), and media that contained stimulants like tumor necrosis factor-alpha (TNF-,) or lipopolysaccharide (LPS). IL-1-like activity was evaluated by its capacity to promote the culture growth of 1A-5 and cytotoxic T lymphocyte derived (CTLD) cell lines. This activity was expressed as optical density (OD)/mg protein of the examined organ. RESULTS:,Uterine artery tissue, of pregnant rats, cultured in medium alone produced significantly higher levels of IL-1 than uterine artery of virgin animals under the same conditions (16.2 S.E. 1.3 versus 0.6 S.E. 0.05 OD/mg protein, respectively; P < 0.02). Stimulation of uterine artery in vitro by LPS and TNF increased their capacity to secrete IL-1. In comparison with uterine artery, aorta produced higher levels of IL-1 in virgin rats compared with pregnant rats (13.6 S.E. 1.2 versus 1.6 S.E. 0.1; P < 0.02). Stimulation of aorta tissues (from both virgin and pregnant rats) with LPS, in vitro, significantly decreased their capacity to secrete IL-1 (P < 0.04). Stimulation of aorta tissues from virgin rats with TNF-,, in vitro, did not change their capacity to secrete IL-1 activity. However, stimulation of aorta tissues from pregnant rats with TNF-, decreased the secretion of bioactive IL-1. The levels of IL-1 produced by uterine tissues from virgin and pregnant rats were similar, and stimulation with either LPS or TNF-, significantly decreased their capacity to secrete IL-1 (P < 0.04). CONCLUSIONS:,The high level of IL-1 activity detected during pregnancy in the uterine artery may suggest its unique involvement in the changes occurring throughout pregnancy in those blood vessels. [source] Toxic Effects of Chromium(VI) on Anaerobic and Aerobic Growth of Shewanella oneidensis MR-1BIOTECHNOLOGY PROGRESS, Issue 1 2004Sridhar Viamajala Cr(VI) was added to early- and mid-log-phase Shewanella oneidensis ( S. oneidensis) MR-1 cultures to study the physiological state-dependent toxicity of Cr(VI). Cr(VI) reduction and culture growth were measured during and after Cr(VI) reduction. Inhibition of growth was observed when Cr(VI) was added to cultures of MR-1 growing aerobically or anaerobically with fumarate as the terminal electron acceptor. Under anaerobic conditions, there was immediate cessation of growth upon addition of Cr(VI) in early- and mid-log-phase cultures. However, once Cr(VI) was reduced below detection limits (0.002 mM), the cultures resumed growth with normal cell yield values observed. In contrast to anaerobic MR-1 cultures, addition of Cr(VI) to aerobically growing cultures resulted in a gradual decrease of the growth rate. In addition, under aerobic conditions, lower cell yields were also observed with Cr(VI)-treated cultures when compared to cultures that were not exposed to Cr(VI). Differences in response to Cr(VI) between aerobically and anaerobically growing cultures indicate that Cr(VI) toxicity in MR-1 is dependent on the physiological growth condition of the culture. Cr(VI) reduction has been previously studied in Shewanellaspp., and it has been proposed that Shewanella spp.may be used in Cr(VI) bioremediation systems. Studies of Shewanella spp. provide valuable information on the microbial physiology of dissimilatory metal reducing bacteria; however, our study indicates that S. oneidensis MR-1 is highly susceptible to growth inhibition by Cr(VI) toxicity, even at low concentrations [0.015 mM Cr(VI)]. [source] | |||||||||||||