Summary

1.

Calcium-dependent exocytosis of catecholamines from intact and digitonin-permeabilized bovine adrenal chromaffin cells was investigated.

2.

⁴⁵Ca²⁺ uptake and secretion induced by nicotinic stimulation or depolarization in intact cells were closely correlated. The results provide strong support for Ca²⁺ entry being the trigger for exocytosis.

3.

Experiments in which the H⁺ electrochemical gradient across the intracellular secretory granule (chromaffin granule) membrane was altered indicated that the gradient does not play an important role in exocytosis.

4.

Ca²⁺ entry into the cells is associated with activation of phospholiphase C and a rapid translocation of protein kinase C to membranes.

5.

The plasma membrane of chromaffin cells was rendered permeable to Ca²⁺, ATP, and proteins by the detergent digitonin without disruption of the intracellular secretory granules. In this system in which the intracellular milieu can be controlled, micromolar Ca²⁺ directly stimulated catecholamine secretion.

6.

Treatment of the cells with phorbol esters and diglyceride, which activate protein kinase C, enhanced phosphorylation and subsequent Ca²⁺-dependent secretion in digitonin-treated cells.

7.

Phorbol ester-induced secretion could be specifically inhibited by trypsin. The experiments indicate that protein kinase C modulates but is not necessary for Ca²⁺-dependent secretion.

Based on the genetic model proposing thatH andSe are two structural genes, we predicted that the red cell H-deficient, salivary ABH secretor phenotype should be found on Reunion island, where a large series of H-deficient non-secretor families have been previously described. Two such Reunion individuals are now reported. POU [A_h, Le(a−b+), secretor of A, H, Le^a and Le^b in saliva] and SOU [O_h, Le(a−b+), secretor of H, Le^a and Le^b in saliva]. Both are devoid of H α-2-fucosyltransferase activity in serum. In addition, the preparation of total non-acid glycosphingolipids from plasma and red cells of POU revealed the type 1ALe^b heptaglycosylceramide and small amounts of the monofucosylated type 1 A hexaglycosylceramide. Both glycolipids possess an H structure probably synthesised by the product of theSe gene. No other blood group A glycolipids, with types 2, 3 or 4 chains, normally present in the presence of the product of theH gene, were found on red cells or plasma of POU.

TheH,Se andLe genetic control of the expression of ABH and related antigens in different tissue structures of the skin is described in 54 H-normal individuals of known ABO, secretor and Lewis phenotypes; in one red cell H-deficient salivary secretor (SOU); and in one H-deficient non-secretor (FRA). Sweat glands express ABH under the control of theSe gene. Sweat ducts express ABH under the control of bothH andSe genes and Lewis antigens under the control ofLe and bothH andSe genes. Epidermis, vascular endothelium and red cells express ABH under the control of theH gene. The products ofH andSe genes are usually expressed in different cells. However, the results illustrate that in some structures, like the epithelial cells of sweat ducts, both the products ofH andSe genes can contribute to the synthesis of the same Le^b structure.

Nine clones of Aphis gossypii Glover (Homoptera: Aphididae) collected from five localities in Japan were tested for esterase activity and resistance to two insecticides. These clones were classified into six types according to esterase pattern and activity detected by electrophoresis. Three clones with very high esterase activity (Type-1) were moderately resistant to malathion and very highly so to pirimicarb. Of six clones with moderate esterase activity one clone (T-4a) was susceptible to malathion but highly resistant to pirimicarb, whereas five clones (T-2, 3a, 3b and 4b) were susceptible to both insecticides. Thus malathion resistance is positively correlated with high esterase activity, whereas pirimicarb resistance is not necessarily so. It is suggested that high esterase activity plays an important role in resistance to these insecticides but that another mechanism is also responsible for resistance to pirimicarb.

There have been a number of significant changes in the UK paper and board industry over the last decade, in particular the increase in waste paper usage and the reduction in water consumption of mills per tonne of product. This review paper presents details of how these changes have affected the microbiological aspects of paper and board manufacture. Emphasis is directed to the reduction in water consumption ‘closing up’ in mill systems and methods of controlling microbial slime deposits. Details of microbial content of pulps, fibres and final products are also discussed.

External perfusion of the charophyte Lamprothamnium papulosum with medium containing 0.5 mM ferricyanide induced depolarization of the transmembrane potential. The depolarization was associated with a decrease in membrane resistance, presumably due to an increase in K⁺ conductance.

During the depolarization cytoplasmic streaming slowed down transiently. The decrease of streaming velocity could be overcome by lowering the external Ca²⁺ concentration or preconditioning the cells with the Ca²⁺ channel blocker La³⁺. Since cytoplasmic streaming is sensitive to the concentration of cytoplasmic free Ca²⁺ it seems as if Fe³⁺Cy stimulates Ca²⁺ influx. As a sequence of events we propose: The transmembrane reduction is a depolarizing current. The depolarization triggers the opening of voltage gated Ca²⁺ and/or K⁺ channels.

However, the Fe³⁺Cy stimulated net proton efflux was not a result of the membrane depolarization.

The aim of the study was to find resistant accessions within Brassicaceae to Phoma lingam and to evaluate whether resistance could be expressed on protoplast or cellular level in presence of the toxin, sirodesmin PL. A gene transfer system was designed, for transfer of genes for resistance to B. napus via protoplast fusions, using the toxin as a selective agent in the screening for resistant hybrid cells.

Long Term Delayed Luminescence (LDL) of green plants ranging from 0.3 s up to several minutes after irradiation has been found to exhibit complex decay kinetics which are highly dependent on nutritional deficiencies and environmental pollutive components. As a model organism we utilized the unicellular green algaScenedesmus obliquus with fairly well understood properties ofLDL probably involving both photosynthetic reaction centers PS I and PS II. It is shown thatLDL is strongly affected both by depletion of the growth medium of various essential elements such as N, Fe, Ca, Mg or K, as well as by growth in the presence of environmental stress factors such as Cu, Hg, Cd or NO ₂⁻ . Therefore,LDL offers itself as a convenient, highly sensitive and specific assay for a number of stress factors in photosynthesizing plantsin vivo and in the field.

Summary

The myxobacteria are among the simplest organisms with a developmental cycle that is dependent on cell cooperation, and they provide an outstanding system with which to study genes involved in cell interactions. Myxococcus xanthus cells which acquire a csg mutation (formerly known as spoC) lose three different traits, the ability to sporulate, the ability to stimulate adjacent Csg cells to sporulate, and the ability to ripple. The boundaries of the csg locus were determined by transferring a recombinant DNA molecule containing all or part of the locus to Csg mutants and examining the sporulation and rippling phenotypes of the transductants. Three methods were used to integrate the csg locus into the chromosome. First, the entire molecule was integrated into the chromosome by a single homologous crossover. Second, a portion of the molecule was integrated into the chromosome by two flanking homologous crossovers. Third, the entire molecule was integrated into the chromosome by site-specific recombination at a bacteriophage attachment site. Together, these techniques suggested that all of the functions of the csg locus are carried on a DNA fragment of 1.9 kbp or less. The locus appears to contain two smaller units of function. Transposon insertions or deletions in the right end of the locus disrupted sporulation and intercellular complementation of Csg mutants for sporulation, but did not disrupt rippling. The intercellular complementation of Csg mutants may reflect a natural and necessary step in the sporulation of wild-type cells, since the ability to sporulate and the ability to stimulate Csg mutants to sporulate were inseparable by any of these methods.

Summary

The hitherto unknown anatomy of Afropomus balanoideus is described. Its systematic position within the Ampullariidae is indicated by the possession of the following autapomorphic characters of the Ampullariidae: presence of a lung sac, an ampulla-shaped aorta anterior, a bipartite copulatory organ of pallial origin, a left-sided zygoneur nervous system, a bipartite kidney, a lamellate osphradium, labial tentacles, an ingestion and an egestion sipho and a radula with strong teeth. The pallial vas deferens is completely closed, while the pallial oviduct is anatomically open in its distal part but functionally closed, because it is embedded in the surrounding mantle tissue. The copulatory organ is of pallial origin and innervated by the right pleural ganglion. The plesiomorphic states of some characters indicate that Afropomus balanoideus might represent the adelphotaxon of the remaining Ampullariidae. The morphological structures show that this species is adapted to an amphibious mode of life and to aestivation, as has been shown for other species of Ampullariidae.