Long term culture of mesenchymal stem cells in hypoxia promotes a genetic program maintaining their undifferentiated and multipotent status

Background  

In the bone marrow, hematopietic and mesenchymal stem cells form a unique niche in which the oxygen tension is low. Hypoxia may have a role in maintaining stem cell fate, self renewal and multipotency. However, whereas most studies addressed the effect of transient in vitro exposure of MSC to hypoxia, permanent culture under hypoxia should reflect the better physiological conditions.     

Intrinsic innervation of the ovary and its variations in the rat senescence process

Journal of Molecular Histology - Ovarian functions decrease with perimenopause. The ovary has extrinsic innervation, but the neural influence on ovarian functions and dysfunction is not...     

An integrated health risk assessment of indigenous children exposed to arsenic in Sonora,Mexico

Exposure to inorganic arsenic (InAs) through drinking water, even at low to moderate concentrations, is a global public health problem. The objectives of this study were to estimate the risk ratio (HQ), cancer risk (R), and DNA damage (comet assay) of children from three indigenous Yaqui populations located in southern Sonora, Mexico, who were exposed to InAs through drinking water. A cross-sectional study was employed, and analysis of InAs in water and urine was performed via HPLC/ICP-MS. InAs levels in drinking water from Pótam, Vícam, and Cócorit were 108.2, 36.0, and 6.2 μg/L^?1 respectively. Children from Pótam had arsenic concentrations in urine of 107.1 μg As L^?1 compared with 40.3 μg As L^?1 for the children of Cócorit. The HQ values for the children of Pótam, Vícam, and Cócorit were 16.64, 6.02, and 0.94, while the R values were 9.4E-04, 3.5E-04, and 5.7E-05, respectively. Children with the highest arsenic exposure had significantly increased DNA damage (OTM = 14.4 vs. 4.3) [p < 0.0005] which positively correlated with urinary arsenic levels (r = 0.56, p < 0.0001). In conclusion, children of Pótam and Vícam are at significant risk of developing chronic diseases and cancers associated with chronic exposure to this metalloid.     

Use and nutritive value of talet beans,Amphicarpaea bracteata (Fabaceae: Phaseoleae) as human food in Puebla, México

Species of the genus Amphicarpaea have been reported as edible (for human consumption or as fodder) in Asia and North America. In northern Puebla, México, talet, A. bracteata, grows as a weed in multiple cropping systems, and its subterranean fruits are used as food by Nahuas, Totonacs, and Mestizos. This study documents how the seed is harvested during agricultural practices, the way in which the pleasant-tasting seeds are prepared for consumption, and how the plants are integrated in the management of the maizebean agroecosystem. We provide data on the chemical composition of talet beans, which is similar to that reported for other food legumes. Talet beans are recommended for development as a casually eaten protein supplement to the human diet in northern Puebla.     

Metabolic flux balance analysis during lactate and glucose concomitant consumption in HEK293 cell cultures

At early stages of the exponential growth phase in HEK293 cell cultures, the tricarboxylic acid cycle is unable to process all the amount of NADH generated in the glycolysis pathway, being lactate the main by-product. However, HEK293 cells are also able to metabolize lactate depending on the environmental conditions. It has been recently observed that one of the most important modes of lactate metabolization is the cometabolism of lactate and glucose, observed even during the exponential growth phase. Extracellular lactate concentration and pH appear to be the key factors triggering the metabolic shift from glucose consumption and lactate production to lactate and glucose concomitant consumption. The hypothesis proposed for triggering this metabolic shift to lactate and glucose concomitant consumption is that HEK293 cells metabolize extracellular lactate as a response to both extracellular protons and lactate accumulation, by means of cotransporting them (extracellular protons and lactate) into the cytosol. At this point, there exists a considerable controversy about how lactate reaches the mitochondrial matrix: the first hypothesis proposes that lactate is converted into pyruvate in the cytosol, and afterward, pyruvate enters into the mitochondria; the second alternative considers that lactate enters first into the mitochondria, and then, is converted into pyruvate. In this study, lactate transport and metabolization into mitochondria is shown to be feasible, as evidenced by means of respirometry tests with isolated active mitochondria, including the depletion of lactate concentration of the respirometry assay. Although the capability of lactate metabolization by isolated mitochondria is demonstrated, the possibility of lactate being converted into pyruvate in the cytosol cannot be excluded from the discussion. For this reason, the calculation of the metabolic fluxes for an HEK293 cell line was performed for the different metabolic phases observed in batch cultures under pH controlled and noncontrolled conditions, considering both hypotheses. The main objective of this study is to evaluate the redistribution of cellular metabolism and compare the differences or similarities between the phases before and after the metabolic shift of HEK293 cells (shift observed when pH is not controlled). That is from a glucose consumption/lactate production phase to a glucose-lactate coconsumption phase. Interestingly, switching to a glucose and lactate cometabolization results in a better-balanced cell metabolism, with decreased glucose and amino acids uptake rates, affecting minimally cell growth. This behavior could be applied to further develop new approaches in terms of cell engineering and to develop improved cell culture strategies in the field of animal cell technology.     

Bioemulsifier production by Aspergillus niger MYA 135: presumptive role of iron and phosphate on emulsifying ability

Microbial emulsifiers are compounds employed in primary mechanisms for bioremediation of petroleum and other hydrocarbon pollutants from the environment. Although emulsifiers of biological origin are produced by microorganisms generally in response to growth on hydrocarbons, Aspergillus niger MYA 135 produced a bioemulsifier during fermentation in a sucrose-based culture medium at an initial pH of 5.0 and at 30°C. The production of bioemulsifiers can be strongly influenced by environmental factors. In this connection, a study of the effect of initial pH, the incubation temperature and presence of CaCl₂ or FeCl₃ in the culture medium was conducted. Emulsification index was increased by 112 and 206% at an initial pH 2.0 or in medium supplemented with FeCl₃, respectively. On the other hand, emulsifying ability of Aspergillus niger supernatants was detected during the exponential phase, suggesting that bioemulsifiers accumulation and microbial growth would be related. Interestingly, this study suggests that iron and/or phosphate ions would play a key role in maintaining the emulsifying ability. Finally, factorial design was also employed to study the effects of the initial pH, the presence of FeCl₃ and the concentration of KH₂PO₄ on the emulsification index.