Reversal of selenium and zinc deficiencies in chronic hemodialysis patients by intravenous sodium selenite and zinc gluconate supplementation

In six chronic dialyzed uremic patients, an intravenous sodium selenite (Se 50 μg during 5 wk and then 100 μg) and zinc gluconate (Zn 5 mg) supplementation was performed during 20 wk at each dialysis session three times weekly. Before supplementation, plasma Se and Zn, plasma and erythrocytes (RBC) antioxidant metalloenzymes glutathione peroxidase (GPX), and superoxide dismutase (SOD) were significantly decreased, whereas lipid peroxidation (as thiobarbituric acid reactants TBARs) was increased. To obtain a significative change in plasma selenium, we had to use an Se dose of 100 μg/dialysis session. Then, treatment-increased plasma Se (from 0.58 ±0.09 to 0.89±0.16 μmol/L) led to a repletion of RBC-GPX (from 29.6±6 to 43±5.8 U/g Hb) and increased plasma GPX levels (from 62±13 to 151±43 U/L). Plasma Zn and RBC-SOD did not vary significantly. The change of TBARs was not observed between wk 1 and 4. They decreased significantly between wk 4 (4.80±0.21μmol/L) and wk 20 (4.16±0.26 μmol/L). We noted a low correlation between TBARs and plasma GPX. A strong correlation was observed between Se and plasma GPX. The reversal of Se deficiencies should reduce oxidative damage observed in these patients.     

Global mangrove root production,its controls and roles in the blue carbon budget of mangroves

Mangroves are among the most carbon-dense ecosystems worldwide. Most of the carbon in mangroves is found belowground, and root production might be an important control of carbon accumulation, but has been rarely quantified and understood at the global scale. Here, we determined the global mangrove root production rate and its controls using a systematic review and a recently formalised, spatially explicit mangrove typology framework based on geomorphological settings. We found that global mangrove root production averaged ~770 ± 202 g of dry biomass m⁻² year⁻¹ globally, which is much higher than previously reported and close to the root production of the most productive tropical forests. Geomorphological settings exerted marked control over root production together with air temperature and precipitation (r² ≈ 30%, p < .001). Our review shows that individual global changes (e.g. warming, eutrophication, drought) have antagonist effects on root production, but they have rarely been studied in combination. Based on this newly established root production rate, root-derived carbon might account for most of the total carbon buried in mangroves, and 19 Tg C lost in mangroves each year (e.g. as CO₂). Inclusion of root production measurements in understudied geomorphological settings (i.e. deltas), regions (Indonesia, South America and Africa) and soil depth (>40 cm), as well as the creation of a mangrove root trait database will push forward our understanding of the global mangrove carbon cycle for now and the future. Overall, this review presents a comprehensive analysis of root production in mangroves, and highlights the central role of root production in the global mangrove carbon budget.     

Conformity in mate choice,the overlooked social component of animal and human culture

Although conformity as a major driver for human cultural evolution is a well-accepted and intensely studied phenomenon, its importance for non-human animal culture has been largely overlooked until recently. This limited for decades the possibility of studying the roots of human culture. Here, we provide a historical review of the study of conformity in both humans and non-human animals. We identify gaps in knowledge and propose an evolutionary route towards the sophisticated cultural processes that characterize humanity. A landmark in the study of conformity is Solomon Asch's famous experiment on humans in 1955. By contrast, interest in conformity among evolutionary biologists has only become salient since the turn of the new millennium. A striking result of our review is that, although studies of conformity have examined many biological contexts, only one looked at mate choice. This is surprising because mate choice is probably the only context in which conformity has self-reinforcing advantages across generations. Within a metapopulation, i.e. a group of subpopulations connected by dispersing individuals, dispersers able to conform to the local preference for a given type of mate have a strong and multigenerational fitness advantage. This is because once females within one subpopulation locally show a bias for one type of males, immigrant females who do not conform to the local trend have sons, grandsons, etc. of the non-preferred phenotype, which negatively and cumulatively affects fitness over generations in a process reminiscent of the Fisher runaway process. This led us to suggest a sex-driven origin of conformity, indicating a possible evolutionary route towards animal and human culture that is rooted in the basic, and thus ancient, social constraints acting on mating preferences within a metapopulation. In a generic model, we show that dispersal among subpopulations within a metapopulation can effectively maintain independent Fisher runaway processes within subpopulations, while favouring the evolution of social learning and conformity at the metapopulation scale; both being essential for the evolution of long-lasting local traditions. The proposed evolutionary route to social learning and conformity casts surprising light on one of the major processes that much later participated in making us human. We further highlight several research avenues to define the spectrum of conformity better, and to account for its complexity. Future studies of conformity should incorporate experimental manipulation of group majority. We also encourage the study of potential links between conformity and mate copying, animal aggregations, and collective actions. Moreover, validation of the sex-driven origin of conformity will rest on the capacity of human and evolutionary sciences to investigate jointly the origin of social learning and conformity. This constitutes a stimulating common agenda and militates for a rapprochement between these two currently largely independent research areas.     

Bacillus subtilis genome project: cloning and sequencing of the 97 kb region from 325° to 333deg;

In the framework of the European project aimed at the sequencing of the Bacillus subtilis genome the DNA region located between gerB (314°) and sacXV (333°) was assigned to the Institut Pasteur. In this paper we describe the cloning and sequencing of a segment of 97 kb of contiguous DNA. Ninety-two open reading frames were predicted to encode putative proteins among which only forty-two were found to display significant similarities to known proteins present in databanks, e.g. amino acid permeases, proteins involved in cell wall or antibiotic biosynthesis, various regulatory proteins, proteins of several dehydrogenase families and enzymes II of the phosphotransferase system involved in sugar transport. Additional experiments led to the identification of the products of new B. subtilis genes, e.g. galactokinase and an operon involved in thiamine biosynthesis.     

Bioguided Fractionation and Isolation of an Antiplasmodial Saponin from the Roots of Nauclea xanthoxylon (A.Chev.) Aubrév. (Rubiaceae)

The root extract of Nauclea xanthoxylon (A.Chev.) Aubrév. displayed significant 50 % inhibition concentration (IC₅₀s) of 0.57 and 1.26 μg/mL against chloroquine resistant and sensitive Plasmodium falciparum (Pf) Dd2 and 3D7 strains, respectively. Bio-guided fractionation led to an ethyl acetate fraction with IC₅₀s of 2.68 and 1.85 μg/mL and subsequently, to the new quinovic acid saponin named xanthoxyloside ( 1 ) with IC₅₀s of 0.33 and 1.30 μM, respectively against the tested strains. Further compounds obtained from ethyl acetate and hexane fractions were the known clethric acid ( 2 ), ursolic acid ( 3 ), quafrinoic acid ( 4 ), quinovic acid ( 5 ), quinovic acid 3-O-β-D-fucopyranoside ( 6 ), oleanolic acid ( 7 ), oleanolic acid 3-acetate ( 8 ), friedelin ( 9 ), β-sitosterol ( 10a ), stigmasterol ( 10b ) and stigmasterol 3-O-β-D-glucopyranoside ( 11 ). Their structures were characterised with the aid of comprehensive spectroscopic methods (1 and 2D NMR, Mass). Bio-assays were performed using nucleic acid gel stain (SYBR green I)-based fluorescence assay with chloroquine as reference. Extracts and compounds exhibited good selectivity indices (SIs) of >10. Significant antiplasmodial activities measured for the crude extract, the ethyl acetate fraction and xanthoxyloside ( 1 ) from that fraction can justify the use of the root of N. xanthoxylon in ethnomedicine to treat malaria.     

Partial characterization of β-glucosidase activity produced by Kluyveromyces marxianus IMB3 during growth on cellobiose-containing media at 45°C

Summary We report- the partial characterization of a -glucosidase produced during growth of the thermotolerant yeast, K. marxianus IMB3 on lactose-containing media at 45°C. The enzyme had Km values of 1.1mM and 14.8mM for the substrates p-nitrophenyl--D-glucoside and cellobiose, respectively. The enzyme had a pH optimum of 5.5 and was optimally active at 50°C. It was stable up to 125 hours at 25°C and 35°, with half-lives of 45 hours and 2 hours at 45°C and 50°C, respectively. The enzyme was inhibited to varying degrees in the presence of metal ions and was completely inactivated by Hg²⁺. Ethanol concentrations [1–10% (v/v)] had little effect on activity. Glucose (20mM) caused inhibition when p-nitrophenyl--D-glucoside was used as substrate, whereas lactose at similar concentrations had no effect.     

The effects of Mn2+ on ethanol production by Kluyveromyces marxianus IMB3 during growth on lactose-containing media at 45°C

Summary It has previously been demonstrated that the thermotolerant yeast strain, K. marxianus IMB3 is capable of growth and ethanol production on lactose containing media at 45°C. Although the organism is capable of producing a -galactosidase, that enzyme has been shown to be extremely thermolabile at 45°C and this has been reflected in reduced efficiencies with respect to conversion of lactose to ethanol. In this paper we demonstrate that addition of Mn²⁺ ions to enzyme preparations contributes significantly to enzyme stability at 45°C. We also demonstrate that addition of Mn²⁺ to fermentations results in increased efficiency of conversion of lactose to ethanol at this temperature.     

Studies on the use of a thermotolerant strain of Kluyveromyces marxianus in simultaneous saccharification and ethanol formation from cellulose

 The thermotolerant yeast strain, Kluyveromyces marxianus IMB3, was found to be capable of ethanol production during growth at 45°C on media containing milled paper and exogenously added commercial cellulase. At maximum achievable cellulose concentrations in shake-flask cultures, ethanol production increased to 6.6 g/l at 45°C, representing an overall level of conversion of 21% of the maximum theoretical yield. Subsequent studies involving variations in added cellulase concentrations to the batch systems demonstrated that ethanol yields could be increased to 10 g/l at 45°C, which represented 39% of the maximum theoretical yield. As a result of ethanol production at 45°C in the systems examined, we suggest that the thermotolerant ethanol-producing yeast strain K. marxianus represents a novel candidate for use in simultaneous saccharification and conversion of the resulting substrates to ethanol. Received: 9 June 1994/Received revision: 8 August 1994/Accepted: 12 August 1994