The sand rat, Psammomys obesus, develops type 2 diabetic retinopathy similar to humans.

PURPOSE: Diabetic retinopathy (DR) is a leading cause of blindness, yet pertinent animal models are uncommon. The sand rat (Psammomys obesus), exhibiting diet-induced metabolic syndrome, might constitute a relevant model. METHODS: Adult P. obesus (n = 39) were maintained in captivity for 4 to 7 months and fed either vegetation-based diets (n = 13) or standard rat chow (n = 26). Although plant-fed animals exhibited uniform body weight and blood glucose levels over time, nearly 60% of rat chow-raised animals developed diabetes-like symptoms (test group). Animals were killed, and their eyes and vitreous were processed for immunochemistry. RESULTS: Compared with plant-fed animals, diabetic animals showed many abnormal vascular features, including vasodilation, tortuosity, and pericyte loss within the blood vessels, hyperproteinemia and elevated ratios of proangiogenic and antiangiogenic growth factors in the vitreous, and blood-retinal barrier breakdown. Furthermore, there were statistically significant decreases in retinal cell layer thicknesses and densities, accompanied by profound alterations in glia (downregulation of glutamine synthetase, glutamate-aspartate transporter, upregulation of glial fibrillar acidic protein) and many neurons (reduced expression of protein kinase Cα and Cξ in bipolar cells, axonal degeneration in ganglion cells). Cone photoreceptors were particularly affected, with reduced expression of short- and mid-/long-wavelength opsins. Hypercaloric diet nondiabetic animals showed intermediate values. CONCLUSIONS: Simple dietary modulation of P. obesus induces a rapid and severe phenotype closely resembling human type 2 DR. This species presents a valuable novel experimental model for probing the neural (especially cone photoreceptor) pathogenic modifications that are difficult to study in humans and for screening therapeutic strategies.journal articleresearch support, non-u.s. gov't2011 Nov 212011 11 21importe

Enhancement of fermentative hydrogen production by Thermotoga maritima through hyperthermophilic anaerobic co-digestion of fruit-vegetable and fish wastes

International audienceIn this work, different proportions of model fruit and vegetable wastes (MFVW) and acid hydrolyzed fish wastes (AHFW) were used for hydrogen production in a minimum culture medium based on seawater. Experiments were performed in pH-controlled Stirred Tank Reactor (STR) with or without the addition of nitrogen and sulfur sources. The total H2 production and the maximum hydrogen productivity of T. maritima in the culture medium, containing MFVW and AHFW (45 mmol L−1 carbohydrates) at a C/N ratio of 12, were 132 mmol L−1 and 15 mmol h−1 L−1, respectively. However, tripling the concentration of carbohydrates to reach a C/N ratio of 22, has increased two times the maximum H2 productivity (28 mmol h−1 L−1) due to the improvement in nutrient balance. The cumulative H2 production was 285 mmol L−1, yielding a potential energy generation of 0.12103 MJ ton−1 wastes, which could be an interesting alternative for energy recovery

A simple gas pressure manometer for measuring hydrogen production by hydrogenogenic cultures in serum bottles

International audienceThis study investigated the determination of hydrogen production by three H2-producing microorganisms (Thermotoga maritima, Thermococcus kodakarensis KOD1 and Enterobacter cloacae) cultured in 116-mL serum bottles. A gas pressure manometer was used to measure total pressure in the serum-bottle headspace. It was demonstrated that total pressure is the sum of the saturation pressure of water, the pressure expansion of gases, and the partial pressures of H2 () and CO2 (). A linear relationship was established between the partial pressure of H2 measured by gas chromatography and the sum of the partial pressures of H2 and CO2 measured by the manometer. When pH of culture medium was not controlled (pH decreased from 7 to 5), the ratio was close to stoichiometric H2/CO2 yield ratio of the most plausible metabolic pathways of each strain. values were 1.7, 1.9 and 0.9 for T. maritima, T. kodakarensis and E. cloacae, respectively. In these experimental conditions, can be deduced from total pressure measured by manometer