Biosignatures and Bacterial Diversity in Hydrothermal Deposits of Solfatara Crater,Italy

We have combined mineralogy, organic geochemistry and molecular microbiology to study hydrothermal deposits from Solfatara Crater, a geologically young volcanic formation (～4,000 years old) displaying hot (45–95°C) and acidic (pH 1.7) mud pools and fumaroles. The search for inorganic (mineral) biosignatures revealed the presence of delicate structures, most likely mineralized extracellular polymers (EPSs), and the presence of potential biologically induced minerals: sulfides, sulfates (barite and alunite), elemental sulfur, and iron oxides. Geochemical analyses revealed a low total organic carbon content, 0.13 to 0.53%, displaying δ¹³C values from ?17.09 to ?27.39‰, and total nitrogen contents from 0.03 to 0.12%, which are characteristic of hydrothermal systems and suggest the presence of autotrophic carbon fixation. Lipid biomarker analysis showed the presence of hopanoids and linear alkanes, and the absence of detectable steroids, implying the occurrence of bacteria in our samples. We constructed 16S rRNA gene libraries from the environmental samples. Most environmental sequences obtained were affiliated to the Alpha- and Betaproteobacteria (Hydrogenophilus-like), the Acidobacteria, and to a lesser extent, the Gammaproteobacteria and Actinobacteria. When known, the closest cultivated relatives were often thermophilic or thermotolerant bacteria oxidizing iron, hydrogen, or methane/methanol, suggesting an important microbial contribution to the formation of biominerals.     

Pituitary adenylate cyclase-activating polypeptide stimulates nitric-oxide synthase type I expression and potentiates the cGMP response to gonadotropin-releasing hormone of rat pituitary gonadotrophs

Nitric-oxide synthase type I (NOS I) is expressed primarily in gonadotrophs and in folliculo-stellate cells of the anterior pituitary. In gonadotrophs, the expression and the activity of NOS I are stimulated by gonadotropin-releasing hormone (GnRH) under both experimental and physiological conditions. In the present study, we show that pituitary adenylate cyclase-activating polypeptide (PACAP) is twice as potent as GnRH at increasing NOS I levels in cultured rat anterior pituitary cells. The action of PACAP is detectable after 4-6 h and maximal at 24 h, this effect is mimicked by 8-bromo-cAMP and cholera toxin and suppressed by H89 suggesting a mediation through the cAMP pathway. Surprisingly, NADPH diaphorase staining revealed that these changes occurred in gonadotrophs exclusively although PACAP and cAMP, in contrast to GnRH, have the potential to target several types of pituitary cells including folliculo-stellate cells. There was no measurable alteration in NOS I mRNA levels after cAMP or PACAP induction. PACAP also stimulated cGMP synthesis, which was maximal within 15 min and independent of cAMP, however, only part resulted from NOS I/soluble guanylate cyclase activation implying that in contrast to GnRH, PACAP has a dual mechanism in cGMP production. Interestingly, induction of NOS I by PACAP markedly enhanced the capacity of gonadotrophs to produce cGMP in response to GnRH. The fact that PACAP may act on gonadotrophs to alter NOS I levels, generate cGMP, and potentiate the cGMP response to GnRH, suggests that cGMP could play important cellular functions.     

N-Carbamoyl-α-Amino Acids Rather than Free α-Amino Acids Formation in the Primitive Hydrosphere: A Novel Proposal for the Emergence of Prebiotic Peptides

Our previous kinetic and thermodynamic studies upon the reactional system HCHO/HCN/ NH₃ in aqueous solutions are completed. In the assumed prebiotic conditions of the primitive earth ([HCHO] and [HCN] near 1 g L^–1, T = 25 °C, pH = 8, [NH₃] very low), this system leads to 99.9% of -hydroxyacetonitrile and 0.1% of -aminoacetonitrile (precursor of the -amino acid). The classical base-catalyzed hydration of nitriles, slow and not selective, can not modify significantly this proportion. On the contrary, we found two specific and efficient reactions of -aminonitriles which shift the initial equilibrium in favor of the -aminonitrile pathway. The first reaction catalyzed by formaldehyde generates -aminoamides, precursors of -aminoacids. The second reaction catalyzed by carbon dioxide affords hydantoins, precursors of N-carbamoyl--aminoacids. In the primitive hydrosphere, where the concentration in carbon dioxide was estimated to be higher than that of formaldehyde, the formation of hydantoins was consequently more efficient. The rates of hydrolysis of the -aminoacetamide and of the hydantoin at pH 8 being very similar, the synthesis of the N-carbamoyl--amino acid seems then to be the fatal issue of the HCHO/HCN/NH₃ system that nature used to perform its evolution. These N-protected -amino acids offer new perspectives in prebiotic chemistry, in particular for the emergence of peptides on the prebiotic earth.     

Acute prooxidant effects of vitamin C in EDTA chelation therapy and long-term antioxidant benefits of therapy

Chelation therapy is thought to not only remove contaminating metals but also to decrease free radical production. EDTA chelation therapy, containing high doses of vitamin C as an antioxidant, is often used in the treatment of diseases such as diabetes and cardiovascular diseases but the effectiveness of this treatment may be variable and its efficacy has not been demonstrated conclusively. The objective of this work was to determine if the vitamin C added to standard chelation therapy cocktails was prooxidant. We administered a standard EDTA cocktail solution with or without 5 g of sodium ascorbate. One hour following the standard chelation therapy, there were highly significant prooxidant effects on lipids, proteins, and DNA associated with decreased activities of RBC glutathione peroxidase and superoxide dismutase while in the absence of sodium ascorbate, there were no acute signs of oxidative damage. After 16 sessions of standard chelation therapy, the acute prooxidant effects of vitamin C remained, but, even in the absence of nutrient supplements, there were beneficial long-term antioxidant effects of chelation therapy and plasma peroxide levels decreased. In conclusion, multiple sessions of EDTA chelation therapy protect lipids against oxidative damage. However, standard high amounts of vitamin C added to EDTA chelation solutions also display short term prooxidant effects. The added benefits of lower levels of vitamin C in chelation therapy need to be documented.     

Cadmium-induced oxidative stress and DNA damage in kidney of pregnant female rats

In the present study, we have investigated the influence of sub-acute treatment with cadmium (Cd) on some parameters indicative of oxidative stress and DNA damage in tissues of pregnant female rats. Pregnant female rats (n=6) were injected subcutaneously, daily with a dose of cadmium chloride of 3 mg/kg body weight (b.w.) from day 6 to day 19 of pregnancy, and they were allowed to deliver normally. MDA level and GPx, CAT and SOD activities were used as markers of oxidative stress in liver and kidney. The 8-oxo-dG level was measured by the HPLC-EC system. Cd treatment increased MDA (+116%, p<0.01) in kidney. Moreover, Cd treatment also decreased CuZn-SOD (-11%, p<0.05) and GSH level (-52%, p<0.05) in kidney. Treated rats displayed an increase of the liver metallothionein (MT) level. Induction of MT in liver was probably implicated in the detoxification of Cd. The high level of Cd (3 mg/kg) used in the present study is partially neutralized by MT in liver, whereas the free fraction could be implicated in the oxidative stress and DNA oxidation observed in kidney. Cd treatment failed to alter 8-oxodGuo, indicating the absence of DNA oxidation in liver; by contrast, the same treatment increased the 8-oxodGuo level (+51%, p<0.05) in the kidney of pregnant female rats, indicating an oxidative stress associated with DNA damage only in kidney.     

Influence of static magnetic field on cadmium toxicity: Study of oxidative stress and DNA damage in rat tissues

In the present study, we investigated the effect of co-exposure to static magnetic field (SMF) and cadmium (Cd) on the biochemical parameters, antioxidant enzymes activity and DNA damage in rat tissues. Animals were treated with cadmium (CdCl₂, 40 mg/L, per os) in drinking water during 4 weeks. Cd treatment induced an increase of plasma lactate dehydrogenase (LDH) and transaminases levels. Moreover, Cd treatment increased malondialdehyde (MDA) and 8-oxodGuo levels in rat tissues. However, the antioxidant enzymes activity such as the glutathione peroxidase (GPx), catalase (CAT) and the superoxide dismutase (SOD) were decreased in liver and kidney, while we noted a huge increase of hepatic and renal cadmium content. Interestingly, the combined effect of SMF (128mT, 1 h/day during 30 consecutive days) and Cd (40 mg/L, per os) decreased the GPx and CAT activities in liver compared to cadmium treated group. However, the association between SMF and Cd failed to alter transaminases, MDA and 8-oxodGuo concentration.

Cd treatment altered antioxidant enzymes and DNA in liver and kidney of rats. Moreover, SMF associated to Cd disrupt this antioxidant response in liver compared to Cd-treated rats.     

Improved immune functions with administration of a low-fat diet in a burn animal model

The purpose of this study was to characterize the impact of a low-fat (LF; 1% fat) diet, a high-fat (HF; 25% fat) diet, and a standard (SD; 5% fat) diet on immune and oxidative parameters in a 20% body surface area burn animal model fed ad libitum for 10 days postinjury. Although the mechanisms are poorly understood, the amount of dietary lipid in nutritional support has been shown to have immunomodulatory effects after burn injury. Burned mice fed the LF diet showed a normal response in activated splenocyte proliferation compared to burned animals that received the SD or HF diet. Animals fed the SD and HF diets presented increased production of nitric oxide and prostaglandin E2 response after burn injury, which is associated with inhibited splenocyte proliferation. The total thiol concentration in spleen cells from burned animals kept on the HF diet was significantly higher than that in unburned animals, while no increase in these oxidative parameters was observed in LF-fed burned animals. Moreover, the LF diet significantly reduced hepatic lipid peroxidation, as measured by malonaldehyde concentration, compared to the other two diets. These results suggest that the administration of a LF diet in mice after a burn injury prevents inhibition of in vitro splenocyte proliferation and reduces the intensity of oxidative stress.     

Direct evidence for the co-expression of URP and GnRH in a sub-population of rat hypothalamic neurones: anatomical and functional correlation

Urotensin-II-related peptide (URP) is an eight amino-acid neuropeptide recently isolated from rat brain and considered as the endogenous ligand for the GPR14 receptor. Using single and double immunohistochemical labelling, in situ hybridization and ultrastructural immunocytochemistry, we explored the cellular and subcellular localization of URP in the male rat brain. URP peptide was detected in numerous varicose fibres of the median eminence (ME) and organum vasculosum laminae terminalis (OVLT) as well as in neuronal cell bodies of the medial septal nucleus and diagonal band of Broca where corresponding mRNA were also detected. Combining in situ hybridization with immunohistochemistry, we showed that cell bodies of the rat anterior hypothalamus contained both URP mRNA and GnRH peptide. In addition, double ultrastructural immunodetection of URP and GnRH peptides clearly revealed, in the median eminence, the co-localization of both peptides in the same neuronal processes in the vicinity of fenestrated portal vessels. This remarkable cellular and subcellular distribution led us to test the effect of URP on the GnRH-induced gonadotrophins release in the anterior pituitary, and to discuss its putative role at the level of the median eminence.