• Energy Research
• Closed Access close
• basic medicine close
• US close
• GB close
• CA close

The purpose of this study was to investigate the influence of increasing sulfate concentrations on chromium removal, to evaluate the effect of the presence of Cr(VI) on sulfate removal by Streptomyces sp. MC1 and to analyze the differential protein expression profile in the presence of this metal for the identification of proteins repressed or overexpressed. In the presence of Cr(VI) but in the absence of sulfate ions, bacterial growth was negligible, showing the Cr(VI) toxicity for this bacterium. However, the sulfate presence stimulated bacterium growth and Cr(VI) removal, regardless of its concentrations. Streptomyces sp. MC1 showed ability to remove chromium and sulfate simultaneously. Also, the sulfate presence favored the decrease of total chromium concentration from supernatants reaching a decrease of 50% at 48 h. In presence of chromium, seven proteins were down‐expressed and showed homology to proteins involved in protein biosynthesis, energy production and free radicals detoxification while two proteins involved in oxidation‐reduction processes identified as dihydrolipoamide dehydrogenase and S‐adenosyl‐l‐methionine synthase were overexpressed.

Since long ago, pelagic Sargassum mats have been known to be abundant in the Sargasso Sea, where they provide habitat to diverse organisms. However, over the last few years, massive amounts of pelagic Sargassum have reached the coast of several countries in the Caribbean and West Africa, causing economic and environmental problems. Aiming for lessening the impacts of the blooms, governments and private companies remove the seaweeds from the shore, but this process results expensive. The valorization of this abundant biomass can render Sargassum tides into an economic opportunity and concurrently solve their associated environmental problems. Despite the diverse fields where algae have found applications and the relevance of this recurrent situation, Sargassum biomass remains without large scale applications. Therefore, this review aims to present the potential uses of these algae, identifying the limitations that must be assessed to effectively valorize this bioresource. Due to the constraints identified for each of the presented applications, it is concluded that a biorefinery approach should be developed to effectively valorize this abundant biomass. However, there is an urgent need for investigations focusing on holopelagic Sargassum to be able to truly valorize this seaweed.

Experiments were carried out to determine the accuracy and validity of estimations of hepatic blood flow from systemic clearances of ethanol during very low dose (8 μmol∙min−1∙kg−1) infusions of ethanol in anesthetized cats. Systemic clearances were compared with directly measured hepatic blood flow using a hepatic venous long-circuit technique. This technique allowed direct measurement and alteration of hepatic blood flow and collection of arterial, portal, and hepatic venous blood samples without depletion of the animal's blood volume. In 18 cats, Vmax for ethanol was 93 ± 7 μmol∙min−1 per 100 g liver or 21 ± 2 μmol∙min−1∙kg·body weight−1 and Km was 144 ± 19 μM in terms of logarithmic mean sinusoidal concentration. At the dose of 8 μmol∙min−1∙kg body weight−1 used for estimation of hepatic blood flow, extraction was 0.95 ± 0.07 (mean ± SD). Systemic clearance of ethanol overestimated directly measured hepatic blood flow by 15 ± 16%. Hepatic blood flow changes expressed as percentages of the control level were accurately estimated from systemic ethanol clearance (100 ± 10%). Since 73 ± 12% of the infused ethanol was eliminated by the liver and 83 ± 11% was eliminated by the splanchnic bed, an extrasplanchnic uptake of 17% accounted for the overestimation of hepatic blood flow. Estimation of hepatic blood flow from systemic clearances of ethanol during very low dose infusions may have advantages over other clearance methods. Its use in cats was illustrated in a separate series of experiments and it was shown that surgery significantly reduced hepatic blood flow. The method may merit trial for estimation of hepatic blood flow in humans.

Abstract Synchronous cultures of the fission yeast Schizosaccharomyces pombe 972 h −1 are most sensitive to killing by 15 min, 49 °C pulses during a stage stretching from nuclear division through short G1 and S phases to a point early in G2. In this work the cell cycle position of the S phase has been altered by growing the cells in the presence of 2-phenylethanol. The heat sensitivity of these cells was greater at all stages of the cell cycle compared with the cells grown without 2-phenylethanol. However, the position of the most heat sensitive stage in the cell cycle was unaltered. This heat sensitive stage did not include S phase in the cells grown with 2-phenylethanol.

Abstract The effects of hCG (CR119) and ethanol (20% in saline, v/v) on the levels of gonadotropin receptor in mature rat testes are studied. The results indicate that 75 I.U. of hCG administered intraperitoneally is capable of depleting testicular tissue of all its gonadotropin binding sites within 24 hrs. after administration, and 11–14 days are required for these binding sites to be fully restored. The disappearance and reappearance patterns of testicular gonadotropin binding sites following in vivo ethanol administration are very similar to those seen after gonadotropin administration, the only difference being that ethanol is much less immediate in its effect. The level of hLH in the serum of these rats is unaffected by the ethanol administered which seems to indicate that reduction of the number of gonadotropin binding sites in testes brought about by ethanol is through membrane-mediated mechanism. For rats receiving gonadotropin injections, no correlation sseems to exist between the concentration of gonadotropin in serum and the level of detectable gonadotropin binding sites in the testis.

Structural and physiological changes that occur as trees grow taller are associated with increased hydraulic constraints on leaf gas exchange, yet it is unclear if leaf-level constraints influence whole-tree growth as trees approach their maximum size. We examined variation in leaf physiology, leaf area to sapwood area ratio (L/S), and annual aboveground growth across a range of tree heights in Eucalyptus regnans. Leaf photosynthetic capacity did not differ among upper crown leaves of individuals 61.1-92.4 m tall. Maximum daily and integrated diurnal stomatal conductance (g s) averaged 36 and 34% higher, respectively, in upper crown leaves of ~60-m-tall, 80-year-old trees than in ~90-m-tall, 300-year-old trees, with larger differences observed on days with a high vapor pressure deficit (VPD). Greater stomatal regulation in taller trees resulted in similar minimum daily leaf water potentials (Ψ L) in shorter and taller trees over a broad range of VPDs. The long-term stomatal limitation on photosynthesis, as inferred from leaf δ (13)C composition, was also greater in taller trees. The δ (13)C of wood indicated that the bulk of photosynthesis used to fuel wood production in the main trunk and branches occurred in the upper crown. L/S increased with tree height, especially after accounting for size-independent variation in crown structure across 27 trees up to 99.8 m tall. Despite greater stomatal limitation of leaf photosynthesis in taller trees, total L explained 95% of the variation in annual aboveground biomass growth among 15 trees measured for annual biomass growth increment in 2006. Our results support a theoretical model proposing that, in the face of increasing hydraulic constraints with height, whole-tree growth is maximized by a resource trade-off that increases L to maximize light capture rather than by reducing L/S to sustain g s.

Abstract An ATP-activated transhydrogenase which catalyzes the reduction of TPN + by DPNH has been demonstrated in the microsomal fraction from the endosperm of immature Echinocystis macrocarpa seeds. The activity is specifically dependent on the presence of ATP ( K m of approximately 0.1 m m ) of several nucleotides tested. The reaction is stimulated by MgCl 2 addition up to concentrations of 6 m m . When 10 −2 m EDTA is added to the assay mixture in the absence of added MgCl 2 , a transhydrogenation reaction is observed which no longer shows any dependence on added ATP. A TPN + -dependent ATPase activity can be demonstrated in these preparations, but no fixed stoichiometry between ATP cleavage and TPNH formation could be established. A lag in attaining the maximal rate of transhydrogenation is seen unless the enzyme is preincubated for 10 min with ATP before initiating the reaction. It can further be shown that preincubation of the enzyme with ATP followed by removal of the ATP on a Dowex 1 column produces an enzyme capable of catalyzing the transhydrogenation without the further addition of ATP. 2,4-Dinitrophenol and thyroxin are effective inhibitors of the transhydrogenase and 2,4-dinitrophenol was shown to inhibit the activating effect of ATP during the preincubation period. It is concluded that the role of ATP is in the modification of the enzyme rather than direct participation in the transhydrogenation. The transhydrogenase is inhibited by ADP and AMP. This results in a response of the enzyme to adenylate energy charge in a manner characteristic for regulatory enzymes which participate in ATP-utilizing metabolic sequences.

AbstractEcologists are increasingly aware of the importance of environmental variability in natural systems. Climate change is affecting both the mean and the variability in weather and, in particular, the effect of changes in variability is poorly understood. Organisms are subject to selection imposed by both the mean and the range of environmental variation experienced by their ancestors. Changes in the variability in a critical environmental factor may therefore have consequences for vital rates and population dynamics. Here, we examine ≥90‐year trends in different components of climate (precipitation mean and coefficient of variation (CV); temperature mean, seasonal amplitude and residual variance) and consider the effects of these components on survival and recruitment in a population of Eurasian beavers (n = 242) over 13 recent years. Within climatic data, no trends in precipitation were detected, but trends in all components of temperature were observed, with mean and residual variance increasing and seasonal amplitude decreasing over time. A higher survival rate was linked (in order of influence based on Akaike weights) to lower precipitation CV (kits, juveniles and dominant adults), lower residual variance of temperature (dominant adults) and lower mean precipitation (kits and juveniles). No significant effects were found on the survival of nondominant adults, although the sample size for this category was low. Greater recruitment was linked (in order of influence) to higher seasonal amplitude of temperature, lower mean precipitation, lower residual variance in temperature and higher precipitation CV. Both climate means and variance, thus proved significant to population dynamics; although, overall, components describing variance were more influential than those describing mean values. That environmental variation proves significant to a generalist, wide‐ranging species, at the slow end of the slow‐fast continuum of life histories, has broad implications for population regulation and the evolution of life histories.