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11.
Background
Hydrogenases catalyze reversible reaction between hydrogen (H2) and proton. Inactivation of hydrogenase by exposure to oxygen is a critical limitation in biohydrogen production since strict anaerobic conditions are required. While [FeFe]-hydrogenases are irreversibly inactivated by oxygen, it was known that [NiFe]-hydrogenases are generally more tolerant to oxygen. The physiological function of [NiFe]-hydrogenase 1 is still ambiguous. We herein investigated the H2 production potential of [NiFe]-hydrogenase 1 of Escherichia coli in vivo and in vitro. The hya A and hya B genes corresponding to the small and large subunits of [NiFe]-hydrogenase 1 core enzyme, respectively, were expressed in BL21, an E. coli strain without H2 producing ability. 相似文献12.
13.
Carol HY Wu Julie YH Chan Jimmy Li-Jer Chou Samuel HH Chan Alice YW Chang 《Journal of biomedical science》2012,19(1):48
Background
Whereas brain death is a vitally important clinical phenomenon, our contemporary understanding on its underlying cellular mechanisms remains elusive. This study evaluated whether the ubiquitin-proteasome system (UPS) in the rostral ventrolateral medulla (RVLM), a neural substrate that our laboratory identified previously to be intimately related to brain death, is engaged in this fatal process.Methods
We performed proteomics, Western Blot, real-time PCR, ELISA and pharmacological experiments in conjunction with a clinically relevant experimental endotoxemia model of brain death based on intravenous administration of Escherichia coli lipopolysaccharide in adult male Sprague–Dawley rats.Results
Proteomics, Western blot and enzyme activity analyses demonstrated that polyubiquitination was preserved and de-ubiquitination by ubiquitin C-terminal hydrolase isozyme-L1 (UCH-L1) was sustained, alongside increased monoubiquitin availability or proteasome activity in RVLM over the course of experimental endotoxemia. However, real-time PCR revealed no significant alteration in proteasome subunit alpha type-1, ubiquitin or UCH-L1 at mRNA level. Functionally, whereas microinjection into the bilateral RVLM of proteasome inhibitors (lactacystin or proteasome inhibitor II) potentiated survival, an inhibitor of ubiquitin-recycling (ubiquitin aldehyde) or an UCH-L1 inhibitor exacerbated mortality.Conclusions
We proposed previously that the progression towards brain death entails a tug-of-war between pro-death and pro-life programs in RVLM. It is conceivable that ubiquitination or de-ubiquitination in RVLM participate in brain death by regulating the degradation of the proteins involved in those programs. 相似文献14.
The seasonality of primary productivity by phytoplankton in relation to physico-chemical and biological variables was studied in Lake Hora-Kilole from August 2007 to May 2008. In 1989, the Mojo River was temporarily diverted to flow into the lake, which substantially changed its physico-chemical conditions and the composition of the phytoplankton. Primary productivity was controlled primarily by soluble reactive phosphorus (SRP), ammonia (NH3), temperature and euphotic depth (Zeu). The light-saturated rate of photosynthesis (Amax) varied from 370 to 3 843?mg O2 m?3 h?1 with the maximum value corresponding to the seasonal maximum of phytoplankton biomass. Compared to the period before the diversion of the river, Amax was reduced by more than ninety-fold in early 1990s and by less than five-fold in 2007 and 2008. Similarly, average phytoplankton chlorophyll a was reduced by more than 2.5 × in the early 1990s and to less than 50% in 2007 and 2008. This highlights the importance of the diversion river water on the physico-chemical and biological environment of the lake. 相似文献
15.
It is commonly assumed that creatine kinase (CK) activity in plasma is related to the state of an inflammatory response at 24-48 h, and also it has shown biphasic patterns after a marathon run. No information is available on CK isoenzymes after an ultra-marathon run. The purpose of the present study is to examine the CK isoenzymes after a 200 km ultra-marathon run and during the subsequent recovery. Blood samples were obtained during registration 1 2 h before the 200-km race and during the race at 100 km, 150 km and at the end of 200 km, as well as after a 24 h period of recovery. Thirty-two male ultra-distance runners participated in the study. Serum CPK showed a marked increase throughout the race and 24 h recovery period (p < 0.001). Serum CK during the race occurs mostly in the CK-MM isoform and only minutely in the CK-MB isoform and is unchanged in the CK-BB isoform. High-sensitivity C-reactive protein (hs-CRP), oestradiol, AST and ALT increased significantly from the pre-race value at 100 km and a further increase took place by the end of the 200 km run. The results of our study demonstrate a different release pattern of creatine kinase after an ultra-distance (200 km) run compared to the studies of marathon running and intense eccentric exercise, and changes in several biomarkers, indicative of muscle damage during the race, were much more pronounced during the latter half (100–200 km) of the race. However, the increases in plasma concentration of muscle enzymes may reflect not only structural damage, but also their rate of clearance. 相似文献
16.
Eric O Williams Yuanyuan Xiao Heather M Sickles Paul Shafer Golan Yona Jean YH Yang David M Lin 《BMC developmental biology》2007,7(1):48
Background
In the mouse olfactory system, the role of the olfactory bulb in guiding olfactory sensory neuron (OSN) axons to their targets is poorly understood. What cell types within the bulb are necessary for targeting is unknown. What genes are important for this process is also unknown. Although projection neurons are not required, other cell-types within the external plexiform and glomerular layers also form synapses with OSNs. We hypothesized that these cells are important for targeting, and express spatially differentially expressed guidance cues that act to guide OSN axons within the bulb. 相似文献17.
Isolation of two populations of sperm cells and microelectrophoresis of pairs of sperm cells from pollen tubes of tobacco (Nicotiana tabacum) 总被引:1,自引:1,他引:0
Prior research has indicated that the two sperm cells of Nicotiana tabacum are dimorphic, suggesting that they may participate in preferential fertilization during in vivo fusion with the egg and
central cells. To probe the mechanism of potential preferential fertilization in this plant, it will be necessary to use modern
sensitive molecular techniques. For this purpose, two individual populations of two sperm cells, constituting the Svn (associated
with the vegetative nucleus) and Sua (unassociated with the vegetative nucleus), were isolated in the thousands from tobacco
pollen tubes with a micromanipulator as a preliminary step toward research on gametic recognition using molecular techniques.
Microelectrophoresis of paired sperm cells from a single pollen tube was conducted at different developmental stages. Sperm
cells isolated from 1-, 2-, 3- and 4-cm stylar lengths migrated to the negative pole, with the Sua displaying significantly
greater electrophoretic mobility than the Svn, reflecting a more positively charged cell surface on the Sua. The sperm cells
isolated from 1-cm style are very sensitive to electron potential in an electrophoretic field, presumably reflecting that
they are still in a young state. Differences in cell surface charge between the Sua and Svn may be related with cell fate
during fertilization.
Supported by National Natural Science Foundation of CHINA (30170060) 相似文献
18.
Harry JGM Crijns Lori D Bash Fran?ois Chazelle Jean-Yves Le Heuzey Thorsten Lewalter Gregory YH Lip Aldo P Maggioni Alfonso Martín Piotr Ponikowski M?rten Rosenqvist Prashanthan Sanders Mauricio Scanavacca Alexandra A Bernhardt Sreevalsa Unniachan Hemant M Phatak Anselm K Gitt 《BMC cardiovascular disorders》2012,12(1):1-13
Background
Cigarette exposure increases brain oxidative stress. The literature showed that increased brain oxidative stress affects cardiovascular regulation. However, no previous study investigated the involvement of brain oxidative stress in animals exposed to cigarette and its relationship with cardiovascular regulation. We aimed to evaluate the effects of central catalase inhibition on baroreflex and cardiovascular responses in rats exposed to sidestream cigarette smoke (SSCS).Methods
We evaluated males Wistar rats (320-370 g), which were implanted with a stainless steel guide cannula into the fourth cerebral ventricle (4th V). Femoral artery and vein were cannulated for mean arterial pressure (MAP) and heart rate (HR) measurement and drug infusion, respectively. Rats were exposed to SSCS during three weeks, 180 minutes, 5 days/week (CO: 100-300 ppm). Baroreflex was tested with a pressor dose of phenylephrine (PHE, 8 ??g/kg, bolus) to induce bradycardic reflex and a depressor dose of sodium nitroprusside (SNP, 50 ??g/kg, bolus) to induce tachycardic reflex. Cardiovascular responses were evaluated before, 5, 15, 30 and 60 minutes after 3-amino-1,2,4-triazole (ATZ, catalase inhibitor, 0.001 g/100 ??L) injection into the 4th V.Results
Central catalase inhibition increased basal HR in the control group during the first 5 minutes. SSCS exposure increased basal HR and attenuated bradycardic peak during the first 15 minutes.Conclusion
We suggest that SSCS exposure affects cardiovascular regulation through its influence on catalase activity. 相似文献19.
Jonathan WF Mant Suzanne H Richards FD Richard Hobbs David Fitzmaurice Gregory YH Lip Ellen Murray Miriam Banting Kate Fletcher Joy Rahman Teresa Allan James Raftery Stirling Bryan 《BMC cardiovascular disorders》2003,3(1):1-10
Background
Statins effectively lower blood cholesterol and the risk of cardiovascular death. Immunomodulatory actions, independent of their lipid-lowering effect, have also been ascribed to these compounds. Since macrophages participate in several vascular pathologies, we examined the effect of statin treatment on the survival and differentiation of primary human monocytes.Methods
Peripheral blood mononuclear cells (PBMCs) from healthy individuals were cultured in the presence or absence of mevastatin. Apoptosis was monitored by annexin V / PI staining and flow cytometry. In parallel experiments, cultures were stimulated with LPS in the presence or absence of mevastatin and the release of IL-1β and IL-1Ra was measured by ELISA.Results
Among PBMCs, mevastatin-treated monocytes were particularly susceptible to apoptosis, which occurred at doses >1 microM and was already maximal at 5 microM. However, even at the highest mevastatin dose used (10 microM), apoptosis occurred only after 24 h of culture, possibly reflecting a requirement for cell commitment to differentiation. After 72 h of treatment the vast majority (>50%) of monocytes were undergoing apoptosis. Stimulation with LPS revealed that mevastatin-treated monocytes retained the high IL-1β output characteristic of undifferentiated cells; conversely, IL-1Ra release was inhibited. Concurrent treatment with mevalonolactone prevented the induction of apoptosis and suppressed both IL-1β and IL-1Ra release in response to LPS, suggesting a rate-limiting role for HMG-CoA reductase in monocyte differentiation.Conclusions
Our findings indicate that statins arrest the functional differentiation of monocytes into macrophages and steer these cells into apoptosis, suggesting a novel mechanism for the vasculoprotective properties of HMG-CoA reductase inhibitors. 相似文献20.
Kate Jolly Gregory YH Lip Josie Sandercock Sheila M Greenfield James P Raftery Jonathan Mant Rod Taylor Deirdre Lane Kaeng Wai Lee AJ Stevens 《BMC cardiovascular disorders》2003,3(1):1-11