BackgroundStress influences many aspects of animal behaviour and is a major factor driving populations to adapt to changing living conditions, such as during domestication. Stress can affect offspring through non-genetic mechanisms, but recent research indicates that inherited epigenetic modifications of the genome could possibly also be involved.Methodology/Principal FindingsRed junglefowl (RJF, ancestors of modern chickens) and domesticated White Leghorn (WL) chickens were raised in a stressful environment (unpredictable light-dark rhythm) and control animals in similar pens, but on a 12/12 h light-dark rhythm. WL in both treatments had poorer spatial learning ability than RJF, and in both populations, stress caused a reduced ability to solve a spatial learning task. Offspring of stressed WL, but not RJF, raised without parental contact, had a reduced spatial learning ability compared to offspring of non-stressed animals in a similar test as that used for their parents. Offspring of stressed WL were also more competitive and grew faster than offspring of non-stressed parents. Using a whole-genome cDNA microarray, we found that in WL, the same changes in hypothalamic gene expression profile caused by stress in the parents were also found in the offspring. In offspring of stressed WL, at least 31 genes were up- or down-regulated in the hypothalamus and pituitary compared to offspring of non-stressed parents.Conclusions/SignificanceOur results suggest that, in WL the gene expression response to stress, as well as some behavioural stress responses, were transmitted across generations. The ability to transmit epigenetic information and behaviour modifications between generations may therefore have been favoured by domestication. The mechanisms involved remain to be investigated; epigenetic modifications could either have been inherited or acquired de novo in the specific egg environment. In both cases, this would offer a novel explanation to rapid evolutionary adaptation of a population.

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Medication with oral drugs has not been considered as a cause of esophageal lesions in the general literature of esophageal disease. This study demonstrates 40 patients with complaints of sudden onset of intense retrosternal pains and odynophagia during treatment with oral tetracyclines. All patients had distinct circumferential ulcers in the esophagus. Medical history, barium swallows, esophagoscopy, biopsies and esophageal manometry revealed no other apparent etiology but a local corrosive effect of the tetracyclines. Experimental tests on the esophagus of the cat verified a severe local corrosive effect of the tetracyclines. Another tetracycline, lymecycline, not reported previously to induce esophageal lesions in man, was significantly less ulcerogenic than doxycycline and oxytetracycline. Drug induced esophageal ulcerations are likely to be more numerous than previously suspected. The experimental model used appears to be sound for investigating ulcerogenic potentials of orally administered drugs.

Contrafreeloading (CFL), i.e. choosing food which requires work over free food, occurs at a higher rate in red jungle fowl (Gallus gallus) compared to White Leghorn layers. We examined whether this difference between breeds was altered by food deprivation and whether it affected the information gained about alternative food sources. In a first experiment, twenty birds of each breed were deprived for zero, three and six hours and then allowed a choice of feeding from freely available food or food mixed with wood shavings. In both breeds, CFL tended to decrease after deprivation, but jungle fowl consistently showed more CFL than Leghorns also after food deprivation. This shows that differences in CFL between breeds were not altered by food deprivation, and the larger CFL in jungle fowl may represent a genetically based difference in feeding strategy. In a second experiment, we examined whether the differences in CFL affected how the birds acquired information about alternative food sites of different quality. Twenty birds of each breed were allowed to forage during three 10 min sessions in a four armed maze, where symbols in each end of the arms indicated the location of four different quality food sources; 'high gain' (freely available food), 'medium gain' (70% food, 30% wood shavings), 'low gain' (30% food), and 'no gain' (100% wood shavings). Each bird was then tested in the same maze when the 'high gain' food source and its symbol had been removed, and the other three sources contained only the symbols and wood shavings. Jungle fowl chose the symbol indicating the best available food source significantly more often than the Leghorns. The results indicate that Leghorn gain less information during foraging, which may have consequences for their adaptation capacity in a production environment. This could either be a consequence of Leghorns showing less CFL, or a generally impaired learning capacity of Leghorns compared to jungle fowl.

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