Possible involvement of integrin signaling pathway in the process of recovery from restraint stress in rats

Objective To search novel genes or pathways involved in the recovery process after restraint stress in rats. Methods We compared the hypothalamus transcriptional profiles of two different recovery patterns （fast recovery vs slow recovery） from restraint stress in rats using oligonucleotide microarray, the recovery pattern was determined by the decrement of plasma adrenocorticotropic-hormone （ACTH） and corticosterone levels during one hour recovery period after stress. A real-time quantitative RT-PCR was applied to validate the differential expressed genes. Results Analysis of the microarray data showed that most of genes were not differentially expressed between fast recovery group and slow recovery group. Among the differentially expressed genes we found that talin, together with serine/threonine protein phosphatase PPl-beta catalytic subunit （PP-1B） and integrin α-6 precursor （VLA-6） genes, were at least 1.5 fold upregulated in the fast recovery group, while junctional adhesion molecule 1 （F11r） was 1.5 fold down-regulated in the fast recovery group. Conclusion The results implied that integrin signaling pathway may be involved in the recovery from restraint stress in rats. The present study provided a global overview of hypothalamus transcriptional profiles during the process of recovery from the restraint stress in rats. The integrin signaling pathway seems to be involved in the recovery process, which deserves further study to clarify the integrin-mediated recovery mechanism after restraint stress.

Physiological plasticity in eucalyptus clones in the vegetative stage contributes to drought tolerance

With the expansion of eucalyptus crops to areas with severe water limitations,physiological studies involving eucalyptus clones to identify those that are tolerant to water stress become important.The objective of this study was to assess morphological and physiological responses by eucalyptus clones subjected to drought stress and rehydration.The experiment consisted of three eucalyptus clones:VC865,I224 and I144 and two water regimes:control and water stress followed by rehydration,with six replicates.Leaf water potential,gas exchange,maximum quantum efficiency of photo systemⅡand plant height and stem diameter were evaluated under drought stress and rehydration.After6 d of rehydration,the number of leaves,leaf area and dry mass of root,leaf,stem and their total were evaluated.All clones showed intense reduction of gas exchange during the drought stress period,and only VC865 and 1144 showed rapid recovery with 3 d of rehydration.Clone 1224 showed greater reduction in height,stem diameter,number of leaves,water potential at midday(Ψ_(w)_(Midday)),and maximum quantum efficiency of photosystemⅡ(F_(v)/F_(m)).Clones VC865and T144 showed lower reductions inΨ_(wMidday)and F_(v)/F_(m) under stress.VC865 had lower reductions in leaf number,leaf area and higher leaf dry mass,while clone I144 had higher height and lower reduction in root dry mass under.Both these clones showed higher water use efficiency with 3d of rehydration.These different phenotypic plasticities gave the clones VC865 and 1144 efficient mechanisms of acclimatization to stress and more drought tolerance,enhancing their greater capacity for recovery after stress,which allowed lower dry mass reduction.Clone 1224,however,was more susceptible to drought stress,undergoing greater physiological damage with only partial recovery during rehydration.