Suppression of src transformation by overexpression of full-length GTPase-activating protein (GAP) or of the GAP C terminus.

Overexpression of the full-length GTPase-activating protein (GAP) has recently been shown to suppress c-ras transformation of NIH 3T3 cells but not v-ras transformation (36). Here, we show that focus formation induced by c-src was inhibited by approximately 80% when cotransfected with a plasmid encoding full-length GAP. In a similar assay, focus formation by the activated c-src (Tyr-527 to Phe) gene was inhibited by 33%. Cotransfection of the GAP C terminus coding sequences (which encode the GTPase-accelerating domain) with c-src or c-src527F inhibited transformation more efficiently than did the full-length GAP, while the GAP N terminus coding sequences had no effect on src transformation. When cells transformed by c-ras, c-src, c-src527F, or v-src were transfected with GAP or the GAP C terminus sequence in the presence of a selectable marker, 40 to 85% of the resistant colonies were found to be morphologically revertant. The GAP C terminus induced reversion of each src-transformed cell line more efficiently than the full-length GAP, but this was not the case for reversion of c-ras transformation. Biochemical analysis of v-src revertant subclones showed that the reversion correlated with overexpression of full-length GAP or the GAP C terminus. There was no decrease in the level of pp60src expression or the level of protein-tyrosine phosphorylation in vivo. We conclude that GAP can suppress transformation by src via inhibition of endogenous ras activity, without inhibiting in vivo tyrosine phosphorylation of cellular proteins induced by pp60src, and that src may negatively regulate GAP's inhibitory action on endogenous ras.     

Crystallographic characterization of a Cu,Zn superoxide dismutase from Photobacterium leiognathi

Crystals of a copper-zinc superoxide dismutase from Photobacterium leiognathi, a luminescent marine bacterium that is the species-specific symbiont of the ponyfish, have been obtained from 2-methyl-2,4-pentanediol solutions. The space group was determined using screenless small-angle precession photographs, and was confirmed by analyzing area detector diffraction data with the XENGEN programs for indexing and refinement. The crystals are monoclinic, space group C2 (a = 126.4 A, b = 87.0 A, c = 44.4 A, beta = 92.8 A), and have two 32,000 Mr dimers per asymmetric unit. The crystals diffract to at least 2.7 A resolution, are resistant to radiation damage, and are suitable for determination of the structure by X-ray diffraction.     

Correction to: Sex and race differences of cerebrospinal fluid metabolites in healthy individuals

Metabolomics - Metabolomics applications to the aquaculture research are increasing steadily. The use of standardized proton nuclear magnetic resonance (1H NMR) spectroscopy can provide the...     

Human StarD5, a cytosolic StAR-related lipid binding protein

Recently identified StarD5 belongs to the StarD4 subfamily, a subfamily of steroidogenic acute regulatory related lipid transfer (START) domain proteins that includes StarD4 and StarD6, proteins whose functions remain unknown. The objective of this study was to confirm StarD5's protein localization and sterol binding capabilities as measures to pursue function. Using rabbit polyclonal antibody against newly purified human histidine-tagged/StarD5 protein, StarD5 was detected in human liver. In parallel studies, increased expression of StarD5 in primary hepatocytes led to a marked increase in microsomal free cholesterol. Cell fractionation studies demonstrated StarD5 protein in liver cytosolic fractions only, suggesting StarD5 as a directional cytosolic sterol carrier. Supportive in vitro binding assays demonstrated a concentration-dependent binding of cholesterol by StarD5 similar to that of the cholesterol binding START domain protein StarD1. In contrast to selective cholesterol binding by StarD1, StarD5 bound the potent regulatory oxysterol, 25-hydroxycholesterol, in a concentration-dependent manner. StarD5 binding appeared selective for cholesterol and 25-hydroxycholesterol, as no binding was observed for other tested sterols. The ability of StarD5 to bind not only cholesterol but also 25-hydroxycholesterol, a potent inflammatory mediator and regulatory oxysterol, raises basic fundamental questions about StarD5's role in the maintenance of cellular cholesterol homeostasis.     

The Importance of Defining 'Forest': Tropical Forest Degradation, Deforestation, Long-term Phase Shifts, and Further Transitions

While research continues on the causes, consequences, and rates of deforestation and forest degradation in the tropics, there is little agreement about what exactly is being lost, what we want back, and to whom the 'we' refers. Particularly unsettling is that many analyses and well-intended actions are implemented in fogs of ambiguity surrounding definitions of the term 'forest'—a problem that is not solely semantic; with development of markets for biomass carbon, vegetation classification exercises take on new relevance. For example, according to the basic implementation guidelines of the Kyoto Protocol, closed canopy natural forest could be replaced by monoclonal plantations of genetically engineered exotic tree species and no deforestation would have occurred. Following these same guidelines, carbon credits for afforestation could be available for planting trees in species-rich savannas; these new plantations would count towards a country moving towards the 'forest transition,' the point at which there is no net 'forest' loss. Such obvious conflicts between biodiversity conservation and carbon sequestration might be avoided if 'forest' was clearly defined and if other vegetation types and other ecosystem values were explicitly recognized. While acknowledging that no one approach to vegetation classification is likely to satisfy all users at all scales, we present an approach that recognizes the importance of species composition, reflects the utility of land-cover characteristics that are identifiable via remote sensing, and acknowledges that many sorts of forest degradation do not reduce carbon stocks ( e.g ., defaunation) or canopy cover ( e.g ., over-harvesting of understory nontimber forest products).     

Plasma Epinephrine Predicts Fasting Glucose in Centrally Obese African‐American Women

The high prevalence of diabetes in African‐American (AA) women has been widely assumed to be related to the greater prevalence of obesity in this group. Catecholamine release acting on central adipose tissue has been proposed to be a contributing factor. The aim of this article was to examine the interaction of plasma catecholamines and central adiposity on fasting and nonfasting glucose levels in two separate samples. In both studies, the women were healthy, nondiabetic of similar age. In addition, both studies assessed plasma epinephrine (EPI) and norepinephrine (NOREPI) levels collected at three time points. In study 1, catecholamines were measured during a standardized laboratory mental stress task and in study 2, they were measured during the initial phase (10 min) of an intravenous glucose tolerance test (IVGTT). Results from both studies revealed significant effects of EPI on fasting glucose in the obese women. In study 1, mean EPI levels were significantly related to fasting glucose in AA women with high trunk fat (β = 0.60, P < 0.001). Because high BMI was associated with high trunk fat in women, we used BMI >30 as a proxy for high trunk fat (>32%) in study 2. In study 2, EPI response to the glucose bolus was a strong predictor of fasting glucose in AA women with BMI >30 (β = 0.75, P < 0.003). We conclude that the effect of central adiposity on fasting glucose may be moderated by plasma EPI. This suggests that adrenal medullary activity could play a role in the pathophysiology of type 2 diabetes.