EFFECT OF GRAZING ON SOME PHYSIOLOGICAL PROPERTIES IN INTEGRATED FARMING SOILS.

The objective of this study was to investigate the effect of grazing on somesoil properties; bulk density (BD), true density, porosity, moisture content(Me) and pH. The effect of long term grazing (>20 yrs) was examined in acoconut - pasture - cattle integrated farming system in Kamburupitiya area.Short term grazing effect was compared with an adjoining coconut plantationpermitting 18 buffaloes to graze for 6 months. Another adjoining ungrazedcoconut farm soil was considered as control. Soil samples were taken fromthe topsoil using a core sampler (v = 98.21 em"). Four replicate samples weretaken three times with 30 days interval and analyzed in triplicates. Data werestatistically analyzed using SAS.Soils collected from the long term integrated farming site had a significantlyhigher (p < 0.05) average pH (5.58) than that of non-integrated sites (4.65).Reduction of acidity may be due to the improvement of soil nutrients viadung, urine and accumulation of litter. It was observed that the soil inintegrated sites were comparatively dark in color. BD of integrated soil(1.15g/cm3) was significantly lower than that of non-integeated soil (21.26%)due to the better ground cover by dominant prostate type herbages comparedto ungrazed soils where erect type herbages were prominent. Soil porosityalso improved due to integration (47.76%) with that of non-integrated soil(43.76%). There was no significant difference observed under the effect ofshort term grazing. A considerable time period may be required to change toimproved soil properties.It is concluded that long term crop-livestock integration could improve thesoil physiochemical properties

The Cytosolic Domain of Fis1 Binds and Reversibly Clusters Lipid Vesicles

Every lipid membrane fission event involves the association of two apposing bilayers, mediated by proteins that can promote membrane curvature, fusion and fission. We tested the hypothesis that Fis1, a tail-anchored protein involved in mitochondrial and peroxisomal fission, promotes changes in membrane structure. We found that the cytosolic domain of Fis1 alone binds lipid vesicles, which is enhanced upon protonation and increasing concentrations of anionic phospholipids. Fluorescence and circular dichroism data indicate that the cytosolic domain undergoes a membrane-induced conformational change that buries two tryptophan side chains upon membrane binding. Light scattering and electron microscopy data show that membrane binding promotes lipid vesicle clustering. Remarkably, this vesicle clustering is reversible and vesicles largely retain their original shape and size. This raises the possibility that the Fis1 cytosolic domain might act in membrane fission by promoting a reversible membrane association, a necessary step in membrane fission

Lymphatic endothelial S1P promotes mitochondrial function and survival in naive T cells

Effective adaptive immune responses require a large repertoire of naive T cells that migrate throughout the body, rapidly identifying almost any foreign peptide. Because the production of T cells declines with age, naive T cells must be long-lived. However, it remains unclear how naive T cells survive for years while constantly travelling. The chemoattractant sphingosine 1-phosphate (S1P) guides T cell circulation among secondary lymphoid organs, including spleen, lymph nodes and Peyer's patches, where T cells search for antigens. The concentration of S1P is higher in circulatory fluids than in lymphoid organs, and the S1P1 receptor (S1P1R) directs the exit of T cells from the spleen into blood, and from lymph nodes and Peyer's patches into lymph. Here we show that S1P is essential not only for the circulation of naive T cells, but also for their survival. Using transgenic mouse models, we demonstrate that lymphatic endothelial cells support the survival of T cells by secreting S1P via the transporter SPNS2, that this S1P signals through S1P1R on T cells, and that the requirement for S1P1R is independent of the established role of the receptor in guiding exit from lymph nodes. S1P signalling maintains the mitochondrial content of naive T cells, providing cells with the energy to continue their constant migration. The S1P signalling pathway is being targeted therapeutically to inhibit autoreactive T cell trafficking, and these findings suggest that it may be possible simultaneously to target autoreactive or malignant cell survival