Synthesis of sulfated bioactive peptides using immobilized arylsulfotransferase from Eubacterium sp.

Summary An arylsulfotransferase from Eubacterium sp. was immobilized on agarose gels by multipoint covalent attachment. The yield of immobilization was 80% with an activity of 11 UA/ml of derivative. After 19 days of incubation, the loss of activity of the derivative was 36%. The immobilized preparation was used to transfer selectively a sulfate group from p-nitrophenolsulfate to selected tyrosine containing biologically active peptides in 92–99% of yield.     

Mode of Action of Lomofungin

Lomofungin inhibited the growth of some yeasts and mycelial fungi at concentrations between 5 and 10 μg/ml. At such concentrations, there was no decrease in endogenous and exogenous oxygen consumption, and even 50 μg of antibiotic per ml caused only slight decreases. The permeation of the cell membrane was changed so that leakage of ninhydrin-positive substances was reduced, and the uptake of ¹⁴C-labeled glucose, amino acids, uracil, and thymidine was decreased at concentrations as low as 4 μg/ml. Protein synthesis in whole cells of Saccharomyces cerevisiae was reduced 35% at 10 μg/ml. However, the antibiotic did not reduce the incorporation of phenylalanine-U-¹⁴C into polypeptides with cell-free systems of Rhizoctonia solani and S. cerevisiae. The synthesis of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) was inhibited even at concentrations of lomofungin of 4 μg/ml. Since RNA synthesis was inhibited at lower concentrations and earlier than DNA synthesis, the primary site of action of the antibiotic appears to be the synthesis of RNA.     

Schistosoma japonicum: Infection characteristics in mice of various strains and a difference in the response to eggs

Female mice of 12 inbred strains were exposed to 20–25 cercariae of Schistosoma japonicum and infection status determined at day 40 by counting numbers of adult worms, eggs in faeces and eggs in a segment of liver. Most mouse strains appeared to be ‘permissive’ hosts although at least one strain (129/J) was shown to be relatively resistant in terms of day 40 adult worm numbers. In a radioisotopic lung assay for sensitivity to eggs, and developed as a rapid means of assessing granuloma formation, CBA/H mice were shown to differ from C57BL/6 mice in being non-responders. Histological examination of lungs of sensitized CBA/H and C57BL/6 mice injected intravenously with eggs established that granuloma formation was much more intense in C57BL/6 than CBA/H mice. Preliminary indications are that infected CBA/H mice are also low anti egg circumoval precipitin (COP) responders. Analysis of immune responses to isolated egg antigens in these two strains, and identification of the antigens of eggs to which such responses are directed in C57BL/6 mice, should provide insights into immunological disease processes (such as granulomatous inflammation) in this model system of japonicum schistosomiasis.     

Expression of three ABA-regulated clones and their relationship to maturation processes during the embryogenesis of chick-pea seeds

Water stress inhibits germination of chick-pea seeds and produces specific changes in gene expression. some of which are coincident with those induced by the exogenous application of abscisic acid (ABA). Three cDNA clones, GAB-8, GAB-9 and GAB-11, were previously identified as under the regulation of ABA and osmotic stress in embryonic axes of germinating chick-pea. Here we try to establish a relationship between the changes in gene expression induced by ABA and stress conditions during germination and those naturally occurring during the desiccation process that leads to seed maturation. Our results show that the germinative capacity of chick-pea is related to the water content of the organ. In vitro translation of the mRNAs from developing seed reveals that in the later stages of seed maturation some polypeptides appear that previously were found to be regulated by ABA and by water deficit in germinating seeds. Hybridization by northern blot of embryogenic mRNAs with GAB-8. GAB-9 and GAB-11 clones shows that the mRNAs corresponding to such clones only appear in the later phases of seed formation, coinciding with seed dehydration, and persisting until seeds became fully mature. The results suggest that these mRNAs are probably related to the response to dehydration that occurs during seed maturation, and that the pattern of expression of these ABA-regulated clones coincides with that of the established late embryogenesis-abundant (LEA) genes.     

Tissue specific expression of cell wall proteins of seedlings of Prosopis chilensis during development and wound stress

Four cell wall proteins of seedling cotyledons of Prosopis chilensis were characterized by SDS-polyacrylamide gel electrophoresis. The molecular masses of these proteins were 180, 126, 107 and 63 kDa. All of them immuno-crossreacted with polyclonal antibodies raised against extensin from soybean seed coats. Immuno-dot blot analysis demonstrated that the minimum expression of cotyledonary cell wall proteins was 48 h after seed imbibition, while 24 h after wound stress the expression of these wall proteins increased four-fold. Tissue immuno-prints and immuno-histochemistry showed that the proteins are expressed in the cell wall of all tissues. However, the epidermis and vascular bundles of cotyledons, hypocotyls and roots, and the living cells surrounding the wounded areas highly expressed the wall proteins. When the primary roots of the seedlings were injured by performing cuts with razor blades, the seedlings achieved a growth three times faster than control seedlings and secondary roots developed in sites close to the injuries. Immuno-histochemistry of secondary roots revealed that the root tips and the area of the cortical tissue of the primary roots being pressed by the the emerging root tip, highly expressed the cell wall proteins.     

Shifts in pH affect the maltose/glycerol co-fermentation by Lactobacillus reuteri

In aerated cultures of Lactobacillus reuteri using maltose/glycerol, lactate was the main product followed by acetate at all pH (4.7, 5.5 and 6.5) tested while anaerobic cultures produced 1,3-propanediol besides lactate, acetate and ethanol. 1,3-Propanediol was the main product at pH 5.5 and 6.5. The high amount of acetate and the low concentration of ethanol found in anaerobic cultures was closely related to the synthesis of 1,3-propanediol.     

Exopolysaccharide production by Lactobacillus casei under controlled pH

Summary The exopolysaccharide (EPS) production and growth characteristics of Lactobacillus casei CRL 87 under pH control were studied. Maximum polymer synthesis (488 mg/l) and cell viability (2.4×10¹⁰ cfu/ml) occurred when L. casei was cultured at a constant pH of 6.0 and 30°C for 24 h. However, the optimum specific EPS production (3.9×10^-5 g EPS/g cell dry weigt) and EPS yield (4.3%) were found at a pH of 4.0.