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61.
Similarity of tetracycline resistance genes isolated from fish farm bacteria to those from clinical isolates 总被引:2,自引:0,他引:2
Furushita M Shiba T Maeda T Yahata M Kaneoka A Takahashi Y Torii K Hasegawa T Ohta M 《Applied and environmental microbiology》2003,69(9):5336-5342
Tetracycline-resistant (Tet(r)) bacteria were isolated from fishes collected at three different fish farms in the southern part of Japan in August and September 2000. Of the 66 Tet(r) gram-negative strains, 29 were identified as carrying tetB only. Four carried tetY, and another four carried tetD. Three strains carried tetC, two strains carried tetB and tetY, and one strain carried tetC and tetG. Sequence analyses indicated the identity in Tet(r) genes between the fish farm bacteria and clinical bacteria: 99.3 to 99.9% for tetB, 98.2 to 100% for tetC, 99.7 to 100% for tetD, 92.0 to 96.2% for tetG, and 97.1 to 100% for tetY. Eleven of the Tet(r) strains transferred Tet(r) genes by conjugation to Escherichia coli HB-101. All transconjugants were resistant to tetracycline, oxycycline, doxycycline, and minocycline. The donors included strains of Photobacterium, Vibrio, Pseudomonas, Alteromonas, Citrobacter, and Salmonella spp., and they transferred tetB, tetY, or tetD to the recipients. Because NaCl enhanced their growth, these Tet(r) strains, except for the Pseudomonas, Citrobacter, and Salmonella strains, were recognized as marine bacteria. Our results suggest that tet genes from fish farm bacteria have the same origins as those from clinical strains. 相似文献
62.
Chimeric gene library construction by a simple and highly versatile method using recombination-dependent exponential amplification 总被引:2,自引:0,他引:2
A simple and efficient method for the construction of chimeric gene libraries termed RDA-PCR (recombination-dependent exponential amplification polymerase chain reaction) was developed by modifying polymerase chain reaction. A chimeric gene library is generated from homologous parental genes with additional primer-annealing sequences at their "heads" and "tails". Two primers ("skew primers") are designed to exclusively anneal to either the heads of maternal genes or the tails of paternal genes. During the RDA-PCR, short annealing/extension periods facilitate homologous recombination. The chimeric sequences can be exponentially amplified to form the chimeric gene library, whereas parental sequences without crossovers are not amplified. As a model, we constructed a chimeric gene library of yellow and green fluorescent protein (yfp and gfp, respectively). The crossover point profile of RDA-PCR clones was compared with those obtained by (modified) family shuffling. PCR restriction fragment polymorphism (PCR-RFLP) analysis of the RDA-PCR clones showed a high content of chimeric genes in the library, whereas family shuffling required the modification using skew primers for selective enrichment of chimeric sequences. PCR-RFLP analysis also indicated that the crossover points of RDA-PCR chimeras were distributed over the entire protein-coding region. Moreover, as few as 2 bp of the continual identity of nucleotides were found at the crossover points at high frequency (30% of the tested clones), suggesting that RDA-PCR resulted in a higher diversity in crossover points than family shuffling. 相似文献
63.
Nosaka T Morita S Kitamura H Nakajima H Shibata F Morikawa Y Kataoka Y Ebihara Y Kawashima T Itoh T Ozaki K Senba E Tsuji K Makishima F Yoshida N Kitamura T 《Molecular and cellular biology》2003,23(8):2969-2980
Dorsoventral patterning depends on the local concentrations of the morphogens. Twisted gastrulation (TSG) regulates the extracellular availability of a mesoderm inducer, bone morphogenetic protein 4 (BMP-4). However, TSG function in vivo is still unclear. We isolated a TSG cDNA as a secreted molecule from the mouse aorta-gonad-mesonephros region. Here we show that TSG-deficient mice were born healthy, but more than half of the neonatal pups showed severe growth retardation shortly after birth and displayed dwarfism with delayed endochondral ossification and lymphopenia, followed by death within a month. TSG-deficient thymus was atrophic, and phosphorylation of SMAD1 was augmented in the thymocytes, suggesting enhanced BMP-4 signaling in the thymus. Since BMP-4 promotes skeletogenesis and inhibits thymus development, our findings suggest that TSG acts as both a BMP-4 agonist in skeletogenesis and a BMP-4 antagonist in T-cell development. Although lymphopenia in TSG-deficient mice would partly be ascribed to systemic effects of runtiness and wasting, our findings may also provide a clue for understanding the pathogenesis of human dwarfism with combined immunodeficiency. 相似文献
64.
Fumarate-reducing bacteria were sought from the main ruminal bacteria. Fibrobacter succinogenes, Selenomonas ruminantium subsp. ruminantium, Selenomonas ruminantium subsp. lactilytica, and Veillonella parvula reduced fumarate by using H(2) as an electron donor. Ruminococcus albus, Prevotella ruminicola, and Anaerovibrio lipolytica consumed fumarate, although they did not oxidize H(2). Of these bacteria, V. parvula, two strains of Selenomonas, and F. succinogenes had a high capacity to reduce fumarate. In all the fumarate-reducing bacteria examined, fumarate reductase existed in the membrane fraction. Based on the activity per cell mass and the affinity of fumarate reductase to fumarate, these bacteria were divided into two groups, which corresponded to the capacity to use H(2): A group of bacteria with higher activity and affinity were able to use H(2) as an electron donor for fumarate reduction. The bacteria in this group should gain an advantage over the bacteria in another group in fumarate reduction in the rumen. Cellulose digestion by R. albus was improved by fumarate reduction by S. lactilytica as a result of an increased growth of R. albus, which may have been caused by the fact that S. lactilytica immediately consumed H(2) produced by R. albus. Thus fumarate reduction may play an important role in keeping a low partial pressure of H(2) in the rumen. 相似文献
65.
Sohee Shin Shinichi Demura Tsuneo Watanabe Tamotsu Yabumoto Jae-Hyun Lee Naoki Sakakibara Toshio Matsuoka 《Journal of physiological anthropology》2015,34(1)
Background
This study aims to examine age-related and obstacle height-related differences in movements while stepping over obstacles.Methods
The participants included 16 elderly and nine young women. Obstacles that were either 5 or 20 cm high were positioned at the center of a 4-m walking path. The participants were instructed to walk along the path as quickly as possible. The participants’ movements were analyzed using a three-dimensional motion analysis system that recorded their movements as they walked and stepped over the obstacles.Results and conclusions
Seven joint angles and the distances between the ground and six markers were examined in the initial contact and swing instants of the leading and trailing limbs. In the initial contact instant, the elderly women prepared for stepping with a lower toe height than the young women when stepping over the 20-cm obstacle. Trunk rotation was greater in the young women than in the elderly women. In the swing instant, the elderly women showed greater ankle dorsiflexion and hip adduction angles for the leading limb when stepping over the 20-cm obstacle. They moved the trailing limb with increased ankle dorsiflexion, knee flexion, hip flexion, and foot inversion to ensure that they did not touch the obstacle as they stepped over it. These movement patterns are characteristic of elderly individuals who cannot easily lift their lower limbs because of decreased lower-limb strength. 相似文献66.
67.
68.
Calmodulin is known to transduce Ca2+ signals by interacting with specific target proteins. In order to determine the role of calmodulin in regulating neuronal
survival and death, we examined, whether calmodulin inhibitors induce caspase-dependent apoptotic cell death, and whether
glycogen synthase kinase-3 is involved in calmodulin inhibitor-induced cell death in PC12 cells. W13, a calmodulin specific
inhibitor increased apoptotic cell death with morphological changes characterized by cell shrinkage and nuclear condensation
of fragmentation. Glycogen synthase kinase-3 inhibitors prevented calmodulin inhibitor-induced apoptosis. In addition, nerve
growth factor and cycloheximide, a protein synthesis inhibitor, completely blocked cell death. Moreover, caspase-3 activation
was accompanied by calmodulin inhibitor-induced cell death and inhibited by nerve growth factor. These results suggest that
calmodulin inhibitors induce caspase-dependent apoptosis, and the activation of glycogen synthase kinase-3 is involved in
the death of PC12 cells. 相似文献
69.
Mutsuo Ichinomiya Masaki Honda Haruto Shimoda Kenji Saito Tsuneo Odate Mitsuo Fukuchi Akira Taniguchi 《Polar Biology》2007,30(10):1285-1293
Temporal variations in the microbial community structure of plankton, which is composed of autotrophic and heterotrophic pico-,
nano- and microplankton, were investigated during the austral summer of 2005/2006 under fast ice near Syowa Station, eastern
Antarctica. Autotrophic algal populations were composed almost entirely of diatoms followed by phytoflagellates such as autotrophic
dinoflagellates and cryptophytes. Among the microbial community, heterotrophic biomass was dominated by heterotrophic dinoflagellates
and naked ciliates and finally exceeded autotrophic biomass. Qualitative microscopic analysis revealed that heterotrophic
dinoflagellates were ingesting large number of diatoms. Synchronizing fluctuation of naked ciliates with phytoflagellates
suggested a predator–prey relationship between them. Our results suggest that the pelagic food webs under the extensive ice-covered
areas in coastal Antarctic regions are not short but complex. 相似文献
70.
Intra- and transcellular water movements in plants are regulated by the water permeability of the plasma membrane (PM) and vacuolar membrane (VM) in plant cells. In the present study, we investigated the osmotic water permeability of both PM (P ( f1)) and VM (P ( f2)), as well as the bulk osmotic water permeability of a protoplast (P ( f(bulk))) isolated from radish (Raphanus sativus) roots. The values of P ( f(bulk)) and P ( f2) were determined from the swelling/shrinking rate of protoplasts and isolated vacuoles under hypo- or hypertonic conditions. In order to minimize the effect of unstirred layer, we monitored dropping or rising protoplasts (vacuoles) in sorbitol solutions as they swelled or shrunk. P ( f1) was calculated from P ( f(bulk)) and P ( f2) by using the 'three-compartment model', which describes the theoretical relationship between P ( f1), P ( f2) and P ( f(bulk)) (Kuwagata and Murai-Hatano in J Plant Res, 2007). The time-dependent changes in the volume of protoplasts and isolated vacuoles fitted well to the theoretical curves, and solute permeation of PM and VM was able to be neglected for measuring the osmotic water permeability. High osmotic water permeability of more than 500 mum s(-1), indicating high activity of aquaporins (water channels), was observed in both PM and VM in radish root cells. This method has the advantage that P ( f1) and P ( f2) can be measured accurately in individual higher plant cells. 相似文献