Adaptive laboratory evolution recruits the promiscuity of succinate semialdehyde dehydrogenase to repair different metabolic deficiencies.

Promiscuous enzymes often serve as the starting point for the evolution of novel functions. Yet, the extent to which the promiscuity of an individual enzyme can be harnessed several times independently for different purposes during evolution is poorly reported. Here, we present a case study illustrating how NAD(P)-dependent succinate semialdehyde dehydrogenase of Escherichia coli (Sad) is independently recruited through various evolutionary mechanisms for distinct metabolic demands, in particular vitamin biosynthesis and central carbon metabolism.

Spermatogenesis in the Roborovski hamster (Phodopus roborovskii) and the Chinese hamster (Cricetulus griseus).

Background: Spermatogenesis is an elaborately organized and tightly regulated differentiation process. The spermatogenesis duration is stable within a certain species but highly variable between species of the same family.

Objectives: In this study, the spermatogenesis duration of the Roborovski hamster was measured for the first time, and the spermatogenesis duration of the Chinese hamster was re-assessed.

No Increased DNA Damage Observed in the Brain, Liver, and Lung of Fetal Mice Treated With Ethylnitrosourea and Exposed to UMTS Radiofrequency Electromagnetic Fields.

The widespread use of mobile phones and Wi-Fi-based communication devices makes exposure to radiofrequency electromagnetic fields (RF-EMF) unavoidable. Previous experiments have revealed the tumor-promoting effects of non-ionizing RF-EMF in adult carcinogen-treated mice in utero. To extend these investigations, we tested whether these effects are due to the co-carcinogenicity of RF-EMF which would manifest as elevated DNA damage.

Temperature-Dependent Network Modules of Soil Methanogenic Bacterial and Archaeal Communities.

Temperature is an important factor regulating the production of the greenhouse gas CH. Structure and function of the methanogenic microbial communities are often drastically different upon incubation at 45°C versus 25°C or 35°C, but are also different in different soils. However, the extent of taxonomic redundancy within each functional group and the existence of different temperature-dependent microbial community network modules are unknown.

Structure, function and resilience to desiccation of methanogenic microbial communities in temporarily inundated soils of the Amazon rainforest (Cunia Reserve, Rondonia).

The floodplain of the Amazon River is a large source for the greenhouse gas methane, but the soil microbial communities and processes involved are little known. We studied the structure and function of the methanogenic microbial communities in soils across different inundation regimes in the Cunia Reserve, encompassing nonflooded forest soil (dry forest), occasionally flooded Igapo soils (dry Igapo), long time flooded Igapo soils (wet Igapo) and sediments from Igarape streams (Igarape). We also investigated a Transect (four sites) from the water shoreline into the dry forest.

Response of Methanogenic Microbial Communities to Desiccation Stress in Flooded and Rain-Fed Paddy Soil from Thailand.

Rice paddies in central Thailand are flooded either by irrigation (irrigated rice) or by rain (rain-fed rice). The paddy soils and their microbial communities thus experience permanent or arbitrary submergence, respectively. Since methane production depends on anaerobic conditions, we hypothesized that structure and function of the methanogenic microbial communities are different in irrigated and rain-fed paddies and react differently upon desiccation stress.

Structure and function of methanogenic microbial communities in sediments of Amazonian lakes with different water types.

Tropical lake sediments are a significant source for the greenhouse gas methane. We studied function (pathway, rate) and structure (abundance, taxonomic composition) of the microbial communities (Bacteria, Archaea) leading to methane formation together with the main physicochemical characteristics in the sediments of four clear water, six white water and three black water lakes of the Amazon River system. Concentrations of sulfate and ferric iron, pH and δ C of organic carbon were usually higher, while concentrations of carbon, nitrogen and rates of CH production were generally lower in white water versus clear water or black water sediments.

Crop rotation of flooded rice with upland maize impacts the resident and active methanogenic microbial community.

Crop rotation of flooded rice with upland crops is a common management scheme allowing the reduction of water consumption along with the reduction of methane emission. The introduction of an upland crop into the paddy rice ecosystem leads to dramatic changes in field conditions (oxygen availability, redox conditions). However, the impact of this practice on the archaeal and bacterial communities has scarcely been studied.

Tumor promotion by exposure to radiofrequency electromagnetic fields below exposure limits for humans.

The vast majority of in vitro and in vivo studies did not find cancerogenic effects of exposure to electromagnetic fields (RF-EMF), i.e. emitted by mobile phones and base stations.

Distance-decay and taxa-area relationships for bacteria, archaea and methanogenic archaea in a tropical lake sediment.

The study of of the distribution of microorganisms through space (and time) allows evaluation of biogeographic patterns, like the species-area index (z). Due to their high dispersal ability, high reproduction rates and low rates of extinction microorganisms tend to be widely distributed, and they are thought to be virtually cosmopolitan and selected primarily by environmental factors. Recent studies have shown that, despite these characteristics, microorganisms may behave like larger organisms and exhibit geographical distribution.

Effects of early-onset radiofrequency electromagnetic field exposure (GSM 900 MHz) on behavior and memory in rats.

Female Wistar rats, from an age of 14 days to 19 months, were exposed in the head region for 2 h per day, 5 days per week, to a GSM-modulated 900 MHz radiofrequency electromagnetic field (RF-EMF). The average specific absorption rates (SAR) in the brain were 0 (sham), 0.7, 2.

Noninvasive assessment of metabolic effects of exposure to 900 MHz electromagnetic fields on Djungarian Hamsters ( Phodopus sungorus ).

Sixteen male Djungarian hamsters, serving as their own controls, were individually exposed to RF-EMF (900 MHz, GSM modulation) at 0 (sham), 0.08, 0.4 or 4 W/kg specific absorption rate (SAR) in specially constructed rectangular waveguides.

Response of the methanogenic microbial communities in Amazonian oxbow lake sediments to desiccation stress.

Methanogenic microbial communities in soil and sediment function only when the environment is inundated and anoxic. In contrast to submerged soils, desiccation of lake sediments happens only rarely. However, some predictions suggest that extreme events of drying will become more common in the Amazon region, and this will promote an increase in sediments drying and exposure.

Structure and function of the methanogenic microbial communities in Uruguayan soils shifted between pasture and irrigated rice fields.

Irrigated rice fields in Uruguay are temporarily established on soils used as cattle pastures. Typically, 4 years of cattle pasture are alternated with 2 years of irrigated rice cultivation. Thus, oxic upland conditions are rotated with seasonally anoxic wetland conditions.

Methanogenic pathway and archaeal communities in three different anoxic soils amended with rice straw and maize straw.

Addition of straw is common practice in rice agriculture, but its effect on the path of microbial CH(4) production and the microbial community involved is not well known. Since straw from rice (C3 plant) and maize plants (C4 plant) exhibit different δ(13)C values, we compared the effect of these straw types using anoxic rice field soils from Italy and China, and also a soil from Thailand that had previously not been flooded. The temporal patterns of production of CH(4) and its major substrates H(2) and acetate, were slightly different between rice straw and maize straw.

Temporal control of spermatogenesis is independent of the central circadian pacemaker in Djungarian hamsters (Phodopus sungorus).

In mammals, the duration of the cycle of the seminiferous epithelium (DCSE) largely differs between species, but is remarkably stable within a species, usually showing variations of 1%-3%. It is difficult to change the DCSE, e.g.

Effect of temperature change on the composition of the bacterial and archaeal community potentially involved in the turnover of acetate and propionate in methanogenic rice field soil.

The microbial community structure was investigated together with the path of methane production in Italian rice field soil incubated at moderate (35 degrees C) and high (45 degrees C) temperature using terminal restriction fragment length polymorphism and stable isotope fractionation. The structure of both the archaeal and bacterial communities differed at 35 degrees C compared with 45 degrees C, and acetoclastic and hydrogenotrophic methanogenesis dominated, respectively. Changing the incubation of the 45 degrees C soil to different temperatures (25, 30, 35, 40, 45, 50 degrees C) resulted in a dynamic change of both microbial community structure and stable isotope fractionation.

Functional and structural response of the methanogenic microbial community in rice field soil to temperature change.

The microbial community in anoxic rice field soil produces CH(4) over a wide temperature range up to 55°C. However, at temperatures higher than about 40°C, the methanogenic path changes from CH(4) production by hydrogenotrophic plus acetoclastic methanogenesis to exclusively hydrogenotrophic methanogenesis and simultaneously, the methanogenic community consisting of Methanosarcinaceae, Methanoseataceae, Methanomicrobiales, Methanobacteriales and Rice Cluster I (RC-1) changes to almost complete dominance of RC-1. We studied changes in structure and function of the methanogenic community with temperature to see whether microbial members of the community were lost or their function impaired by exposure to high temperature.

Pathway of CH4 formation in anoxic rice field soil and rice roots determined by 13C-stable isotope fractionation.

In anoxic rice fields methane is produced by either reduction of CO2 or cleavage of acetate. We measured the delta 13C-values of CH4 and CO2, acetate and organic carbon during time course experiments with anoxic methanogenic soil and root samples and used these values to calculate the fractions of CH4 (and acetate) produced from CO2 reduction. Comparison with radiotracer and/or inhibitor studies constrained the kinetic fractionation factors used for calculation.