Role of actin in the cAMP-dependent activation of sodium/glucose cotransporter in renal epithelial cells

We examined whether actin filaments are involved in the cAMP-dependent activation of a high affinity sodium/glucose cotransporter (SGLT1) using epithelial expression systems. The expression of enhanced green fluorescent protein-tagged SGLT1 (EGFP-SGLT1) in Madin-Darby canine kidney (MDCK) cells was revealed by Western blotting and confocal laser microscopy. 8-Br-cAMP, a membrane permeable cAMP analog, enhanced [¹⁴C]-α-methyl glucopyranoside ([¹⁴C]-AMG) uptake. Both basal and 8-Br-cAMP-elicited [¹⁴C]-AMG uptakes were inhibited by N-(2{[3-(4-bromophenyl)-2-propenyl]-amino}-ethyl)-5-isoquinolinesulfonamide (H-89), a protein kinase A inhibitor, and cytochalasin D, an actin filament formation inhibitor. Furthermore, cytochalasin D inhibited the distribution of EGFP-SGLT1 at the apical surface. These results suggest that the EGFP-SGLT1 protein is functionally expressed in the apical membrane of MDCK cells, and is up-regulated by a cAMP-dependent pathway requiring intact actin filaments.     

Grouped sequential exploitation of food patches in a flock feeder,the feral pigeon

Feral and laboratory flocks of rock doves ($\text{Columba}$$\text{livia}$) show a pattern of grouped sequential exploitation when simultaneously presented with two dispersed, depleting patches of seed. This behavior contrasts with the ideal free distribution pattern shown when patches are small and concentrated. Grouped sequential exploitation consists of two phases: all pigeons first land together and feed at one patch, then leave one by one for the other patch. Departure times of individuals for the second patch are correlated with feeding rate at patch 1, which is in turn correlated with position in the dominance hierarchy. The decision to switch from patch 1 to patch 2 improves individual feeding rates in all cases, but is done slightly later than it should according to optimal foraging theory.     

Multi-lineage Lung Regeneration by Stem Cell Transplantation across Major Genetic Barriers

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Mechanistic studies on carboxypeptidase a from goat pancreas — part II: Evidence for carboxyl group

Studies with substrate analogues and the pH optimum indicated the involvement of carboxyl group in the active site of goat carboxypeptidase A. Chemical modification of the enzyme with 1-cyclohexyl-3-(2-morpholinoethyl) carbodiimide methoI -p-toluene sulphonate, a carboxyl specific reagent, led to loss of both esterase and peptidase activities. Protection studies showed that this carboxyl group was in the active site and was protected by Βp-phenylpropionic acid and glycyl-L-tyrosine. Kinetic studies also confirmed the involvement of carboxylic group because the enzyme modification with water soluble carbodiimide was a two step reaction which excluded the possibility of tyrosine or lysine which are known to give a one step reaction with this reagent     

Animal models for respiratory chain disease

Elucidation of the pathogenesis in respiratory chain diseases is of great importance for developing specific treatments. The limitations inherent to the use of patient material make studies of human tissues often difficult and the mouse has therefore emerged as a suitable model organism for studies of respiratory chain diseases. In this review, we present an overview of the field and discuss in depth a few examples of animal models reproducing pathology of human disease with primary and secondary respiratory chain involvement.     

Increased near-ultraviolet induced DNA fragmentation in xeroderma pigmentosum variants.

Immediate fragmentation of parental DNA by near-ultraviolet irradiation at 313 nm was measured in cultured skin fibroblasts from normal individuals, patients with Xeroderma pigmentosum of complementation group A (XPA) and Xeroderma pigmentosum variants (XPV) by the alkaline elution procedure. For a dose of 2.25 KJm^?2 given at O^o fragmentation was comparable in all cell strains. However, fragmentation was strongly increased relative to O^o in XPV but not in normal fibroblasts and the XPA strains when irradiation was carried out at 37^o. From our results it appears that a step in the repair of $\text{parental}$ DNA is abnormal in XPV.     

Synergistic action of co-expressed xylanase/laccase mixtures against milled sugar cane bagasse

The primary plant cell wall is composed of cellulose, hemicellulose, lignin and protein in a stable matrix. The concomitant depolymerization of lignin by laccase and of hemicelluloses by xylanase can improve lignocellulose degradation in the production of second generation biofuels. A thermophilic variant of xylanase A (XynAG3) and the thermostable laccase (CotA), both from Bacillus subtilis, were produced in co-transformed Pichia pastoris strain GS115. Mobility changes in SDS-PAGE after Endo H digestion indicated that both enzymes were glycosylated. The maximum catalytic activity of the XynAG3_Pp and the CotA_Pp was observed at 58 °C and 75 °C, respectively, and both enzymes presented high activity at pH 5.0. The half-life at 60 °C of XynAG3_Pp and CotA_Pp was 150 min and 540 min, respectively. The relative levels of CotA_Pp and XynAG3_Pp in culture broths were altered by the concentration of methanol used for induction, and CotA_Pp:XynAG3_Pp ratios of 1:1.5 and 1:2 were evaluated against milled sugar-cane bagasse. The highest activity was observed at a 1:2 ratio of CotA_Pp:XynAG3_Pp, and was 44% higher as compared to the sum of the activities of the individual enzymes in the same assay conditions. These results demonstrate the synergistic action between an endoxylanase and a laccase against the natural lignocellulosic substrate.