Chemical synthesis of a tetradecamer in the deoxyribonucleic acid series

The chemical synthesis of a tetradecadeoxyribonucleotide, d-EtSp(A-T-G-G-A-A-A-C-T-G-C-G-G-C), is described. This oligomer, designated Fragment 4δ, constitutes the 5′-terminus of the plus strand of a projected duplex coding for S-Peptide_2–14 derived from Ribonuclease A. The Fragment was constructed by block condensation via a phosphorothioate anchor. Complications due to inadvertent phosphotriester condensations are discussed. Arguments justifying the sequence selection are presented.     

Endophytic fungi in wild and cultivated grasses in Finland

We examined the occurrence of vertically via host seeds transmitted endophyte infections of 14 grass species in natural populations in Finland and totally 97 agricultural cultivars of 13 grass species. Although endophyte infections were widespread in native grass species, overall endophyte occurrence and frequencies were lower than published reports have suggested. In natural populations, 10 out of 14 grass species examined harbor fungal endophytes in their seeds. The highest species-specific mean incidences of endophyte infected plants in infected populations were found in Agrostis capillaris. Festuca arundinacea. F. ovina. F. Pratensis. F. rubra and Phleum pratense (67%, 98%, 29%., 42%. 32% and 33%, respectively). Mean incidences were < 20% in Dactylis glomerata. Deschampsia flexuosa. D. cespitosa and Elymus repens. and no infections were detected in Calamagrostis lapponica. C. epigejos. Alopecurus pratensis and Phalaris arundinacea. However, we detected a very high variation in infection incidences among natural populations and a large proportion of populations was, indeed, endophyte-free. This supports the ideas that 1) endophytic fungi provide selective advantage of infected grasses to their uninfected eonspecifics in some habitats, and/or 2) fungi are occasionally transmitted horizontally by spores. In grass cultivars, endophyte infected seeds were detected only in F. Pratensis and Lolium perenne. and endophyte frequencies were either very high or very low. Cultivars of 11 other grass species were endophyte-free.     

Role of Ca2+-activated K+ channel in regulation of NaCl reabsorption in thick ascending limb of Henle's loop

1. Reabsorption of NaCl in the thick ascending limb of Henle's loop involves the integrated function of the Na+,K+,Cl- -cotransport system and a Ca2+-activated K+ channel in the luminal membrane with the Na+,K+-pump and a net Cl- conductance in the basolateral membrane. 2. Assay of K+ channel activity after reconstitution into phospholipid vesicles shows that the K+ channel is stimulated by Ca2+ in physiological concentrations and that its activity is regulated by calmodulin and phosphorylation from cAMP dependent protein kinase. 3. For purification luminal plasma membrane vesicles are isolated and solubilized in CHAPS. K+ channel protein is isolated by affinity chromatography on calmodulin columns. The purified protein has high Ca2+-activated K+ channel activity after reconstitution into vesicles. 4. The purified K+ channel consists of two proteins of 51 and 36 kDa. Phosphorylation from cAMP dependent protein kinase stimulates K+ channel activity and labels the 51 kDa band. The 36 kDa band is rapidly cleaved by trypsin and may be involved in Ca2+ stimulation. 5. Opening of the K+ channel by Ca2+ in physiological concentrations and regulation by calmodulin and phosphorylation by protein kinase may mediate kinetic and hormonal regulation of NaCl transport across the tubule cells in TAL.     

Degranulation and histamine release from murine mast cells sensitized with dengue virus-immune sera

Mice were immunized with dengue type 2 virus (DEN 2) under a schedule favoring the production of IgE antibody. The antibody obtained could sensitize peritoneal resident mast cells both in vitro and in vivo so that the sensitized cells were degranulated and released histamine on challenge with the DEN 2 antigen. It was also demonstrated that the antibody was cytophilic and heat-labile. The above observations suggest that the present experimental system can be used to detect anti-DEN 2 IgE antibody in mice.