The Regulatory Network Controlling Ethanol-Induced Expression of Alcohol Dehydrogenase in the Endophyte Azoarcus sp. Strain BH72.

The habitat of the nitrogen-fixing endophyte Azoarcus sp. strain BH72 is grass roots grown under waterlogged conditions that produce, under these conditions, ethanol. Strain BH72 is well equipped to metabolize ethanol, with eight alcohol dehydrogenases (ADHs), of which ExaA2 and ExaA3 are the most relevant ones. exaA2 and exaA3 cluster and are surrounded by genes encoding two-component regulatory systems (TCSs) termed ExaS-ExaR and ElmS-GacA. Functional genomic analyses revealed that i) expression of the corresponding genes was induced by ethanol, ii) the genes were also expressed in the rhizoplane or even inside of rice roots, iii) both TCSs were indispensable for growth on ethanol, and iv) they were important for competitiveness during rice root colonization. Both TCSs form a hierarchically organized ethanol-responsive signal transduction cascade with ExaS-ExaR as the highest level, essential for effective expression of the ethanol oxidation system based on ExaA2. Transcript and expression levels of exaA3 increased in tcs deletion mutants, suggesting no direct influence of both TCSs on its ethanol-induced expression. In conclusion, this underscores the importance of ethanol for the endophytic lifestyle of Azoarcus sp. strain BH72 and indicates a tight regulation of the ethanol oxidation system during root colonization.

Obesity as a perceived social signal.

Fat accumulation has been classically considered as a means of energy storage. Obese people are theorized as metabolically 'thrifty', saving energy during times of food abundance. However, recent research has highlighted many neuro-behavioral and social aspects of obesity, with a suggestion that obesity, abdominal obesity in particular, may have evolved as a social signal. We tested here whether body proportions, and abdominal obesity in particular, are perceived as signals revealing personality traits. Faceless drawings of three male body forms namely lean, muscular and feminine, each with and without abdominal obesity were shown in a randomized order to a group of 222 respondents. A list of 30 different adjectives or short descriptions of personality traits was given to each respondent and they were asked to allocate the most appropriate figure to each of them independently. The traits included those directly related to physique, those related to nature, attitude and moral character and also those related to social status. For 29 out of the 30 adjectives people consistently attributed specific body forms. Based on common choices, the 30 traits could be clustered into distinct 'personalities' which were strongly associated with particular body forms. A centrally obese figure was perceived as "lethargic, greedy, political, money-minded, selfish and rich". The results show that body proportions are perceived to reflect personality traits and this raises the possibility that in addition to energy storage, social selection may have played some role in shaping the biology of obesity.