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91.
92.
Both the drag force and the horizontal eddy viscosity play a dominant role in the tidal-scale hydrodynamics in mangrove wetlands. Using field observations and basic fluid mechanics laws, the drag coefficient and the coefficient of dynamic eddy viscosity are found to be predictable as a function of the Reynolds Number based on the characteristic length scale of the vegetation. The characteristic length scale of the vegetation varies greatly with vegetation species, vegetation density and tidal elevation. Both these coefficients decrease with increasing values of the Reynolds Number. At the low range of the Reynolds Number both these coefficients reach much higher values than those typical of vegetation-poor estuaries and rivers. Consequently, the tidal flow within mangrove areas depends to a large degree upon the submerged vegetation density that varies with the tidal stage. These findings may be applied also in other vegetated tidal wetlands, including salt marshes.  相似文献   
93.
GGAs (Golgi-localizing, gamma-adaptin ear domain homology, ADP-ribosylation factor (ARF)-binding proteins) are a family of monomeric adaptor proteins involved in membrane trafficking from the trans-Golgi network to endosomes. The GAT (GGA and Tom1) domains of GGAs have previously been shown to interact with GTP-bound ARF and to be crucial for membrane recruitment of GGAs. Here we show that the C-terminal subdomain of the GAT domain, which is distinct from the N-terminal GAT subdomain responsible for ARF binding, can bind ubiquitin. The binding is mediated by interactions between residues on one side of the alpha3 helix of the GAT domain and those on the so-called Ile-44 surface patch of ubiquitin. The binding of the GAT domain to ubiquitin can be enhanced by the presence of a GTP-bound form of ARF. Furthermore, GGA itself is ubiquitinated in a manner dependent on the GAT-ubiquitin interaction. These results delineate the molecular basis for the interaction between ubiquitin and GAT and suggest that GGA-mediated trafficking is regulated by the ubiquitin system as endosomal trafficking mediated by other ubiquitin-binding proteins.  相似文献   
94.
95.
Tom1 (target of Myb1) is a protein of unknown function. Tom1 and its relative Tom1L1 have an N-terminal VHS (Vps27p/Hrs/Stam) domain followed by a GAT (GGA and Tom1) domain, both of which are also found in the GGA (Golgi-localizing, gamma-adaptin ear domain homology, ADP-ribosylation factor-binding protein) family of proteins. Although the VHS and GAT domains of GGA proteins bind to transmembrane cargo proteins and the small GTPase ADP-ribosylation factor, respectively, the VHS and GAT domains of Tom1 are unable to interact with these proteins. In this study, we show that the GAT domains of Tom1 and Tom1L1 interact with ubiquitin and Tollip (Toll-interacting protein). Ubiquitin bound the GAT domains of Tom1, Tom1L1, and GGA proteins, whereas Tollip interacted specifically with Tom1 and Tom1L1. Ubiquitin and Tollip bound to an overlapping region of the Tom1-GAT domain in a mutually exclusive manner. Tom1 was predominantly cytosolic when expressed in cells. On the other hand, Tollip was localized on early endosomes and recruited Tom1 and ubiquitinated proteins. These observations suggest that Tollip and Tom1 form a complex and regulate endosomal trafficking of ubiquitinated proteins.  相似文献   
96.
Recent studies have shown that bone marrow (BM) cells, including the BM side population (BM-SP) cells that enrich hematopoietic stem cells (HSCs), are incorporated into skeletal muscle during regeneration, but it is not clear how and what kinds of BM cells contribute to muscle fiber regeneration. We found that a large number of SP cells migrated from BM to muscles following injury in BM-transplanted mice. These BM-derived SP cells in regenerating muscles expressed different surface markers from those of HSCs and could not reconstitute the mouse blood system. BM-derived SP/Mac-1(low) cells increased in number in regenerating muscles following injury. Importantly, our co-culture studies with activated satellite cells revealed that this fraction carried significant potential for myogenic differentiation. By contrast, mature inflammatory (Mac-1(high)) cells showed negligible myogenic activities. Further, these BM-derived SP/Mac-1(low) cells gave rise to mononucleate myocytes, indicating that their myogenesis was not caused by stochastic fusion with host myogenic cells, although they required cell-to-cell contact with myogenic cells for muscle differentiation. Taken together, our data suggest that neither HSCs nor mature inflammatory cells, but Mac-1(low) early myeloid cells in the BM-derived SP fraction, play an important role in regenerating skeletal muscles.  相似文献   
97.
Recently, we created a lysine-deficient mutant tumor necrosis factor-alpha [mTNF-alpha-Lys(-)] with full bioactivity in vitro compared with wild-type TNF-alpha (wTNF-alpha), and site-specific PEGylation of mTNF-alpha-Lys(-) was found to selectively enhance its in vivo antitumor activity. In this study, we attempted to optimize this PEGylation of mTNF-alpha-Lys(-) to further improve its therapeutic potency. mTNF-alpha-Lys(-) was site-specifically modified at its N-terminus with linear polyethylene glycol (LPEG) or branched PEG (BPEG). While randomly mono-PEGylated wTNF-alpha (ran-LPEG5K-wTNF-alpha) with 5 kDa of LPEG (LPEG5K) had about only 4% in vitro bioactivity of wTNF-alpha, mono-PEGylated mTNF-alpha-Lys(-) [sp-PEG-mTNF-alpha-Lys(-)] with LPEG5K, LPEG20K, BPEG10K, and BPEG40K had 82%, 58%, 93%, and 65% bioactivities of mTNF-alpha-Lys(-), respectively. sp-LPEG-mTNF-alpha-Lys(-) and sp-BPEG10K-mTNF-alpha-Lys(-) had much superior antitumor activity to those of both unmodified TNF-alphas and ran-LPEG5K-wTNF-alpha, though sp-BPEG40K-mTNF-alpha-Lys(-) did not show in vivo antitumor activity. Thus, the molecular shape and weight of PEG may strongly influence the in vivo antitumor activity of sp-PEG-mTNF-alpha-Lys(-).  相似文献   
98.
The effects of temperature, salinity and irradiance on the growth of the red tide dinoflagellate Gyrodinium instriatum Freudenthal et Lee were examined in the laboratory. Exposed to 45 different combinations of temperature (10–30 °C) and salinity (0–40) under saturating irradiance, G. instriatum exhibited its maximum growth rate of 0.7 divisions/day at a combination of 25 °C and a salinity of 30. Optimum growth rates (>0.5 divisions/day) were observed at temperatures ranging from 20 to 30 °C and at salinities from 10 to 35. The organism could not grow at ≤10 °C. In addition, G. instriatum burst at a salinity of 0 at all temperatures, but grew at a salinity of 5 at temperatures between 20 and 25 °C. It is noteworthy that G. instriatum is a euryhaline organism that can live under extremely low salinity. Factorial analysis revealed that the contributions of temperature and salinity to its growth of the organism were almost equal. The irradiance at the light compensation point (I0) was 10.6 μmol/(m2 s) and the saturated irradiance for growth (Is) was 70 μmol/(m2 s), which was lower than Is for several other harmful dinoflagellates (90–110 μmol/(m2 s)).  相似文献   
99.
We previously found that transplantation with bone marrow cells (BMCs) improves liver function and liver fibrosis in cirrhotic mice. In the presence of liver damage induced by carbon tetrachloride (CCl4), transplanted BMC migrated into the peri-portal region and trans-differentiated into hepatocytes that produce albumin. Thus under these conditions, BMC transplantation induces liver regeneration. Detecting serum marker proteins is important to monitor the recovery of liver function of cirrhotic mice after BMC transplantation. We therefore initially resolved proteins extracted from serum samples at 48 h after BMC transplantation by 2-DE and compared spot intensity between control and BMC groups of mice. Six protein spots increased in the BMC group compared with the control group. MS revealed that these spots comprised apolipoprotein A1 (apoA1), apolipoprotein C3 (apoC3), vitamin D-binding protein, alpha-1-antitrypsin and proteasome subunit alpha type 1. We subsequently confirmed the levels of apoA1 in serum and liver samples by immunoblotting. ApoA1 increased at early stage (48 h and 1 wk) after BMC transplantation in this mouse model of liver cirrhosis. The early elevation of apoA1 might be useful to predict liver regeneration in cirrhotic mice after BMC transplantation.  相似文献   
100.
8-Oxoguanosine (8-oxoG) is a representative metabolite derived by the oxidation of guanosine (G) and is regarded as a marker of oxidative stress in the cells. We previously reported the 8-oxoG-clamp as the first fluorescent probe for detection of 8-oxoG. In this study, new 8-oxoG-clamp derivatives having a variety of N-functional groups were synthesized and their recognition properties were investigated. The sp3 oxygen atom of the carbamate unit was revealed to play a significant role in the hydrogen bonding interactions, and the pyrene group produced higher stability with 8-oxoG compared with the original 8-oxoG-clamp.  相似文献   
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