Demonstration of a proteolytic activity on intracellular origin in Aeromonas hydrophila LP 50

Aeromonas hydrophila LP 50, isolated from packaged pasteurized milk, was grown in glucose-polypeptone medium at 30 degrees C. The proteolytic activity of A. hydrophila LP 50, optimum at the stationary phase of growth, is attributed to extracellular or membrane protease; no intracellular proteolytic activity was shown.     

Translational regulation of light-induced ribulose 1,5-bisphosphate carboxylase gene expression in amaranth.

The regulation of the genes encoding the large and small subunits of ribulose 1,5-bisphosphate carboxylase was examined in amaranth cotyledons in response to changes in illumination. When dark-grown cotyledons were transferred into light, synthesis of the large- and small-subunit polypeptides was initiated very rapidly, before any increase in the levels of their corresponding mRNAs. Similarly, when light-grown cotyledons were transferred to total darkness, synthesis of the large- and small-subunit proteins was rapidly depressed without changes in mRNA levels for either subunit. In vitro translation or in vivo pulse-chase experiments indicated that these apparent changes in protein synthesis were not due to alterations in the functionality of the mRNAs or to protein turnover, respectively. These results, in combination with our previous studies, suggest that the expression of ribulose 1,5-bisphosphate carboxylase genes can be adjusted rapidly at the translational level and over a longer period through changes in mRNA accumulation.     

Organization of the nervous system of physonectid siphonophores

Summary An antiserum to the sequence Arg-Phe-amide (RFamide) was used to stain the nervous systems of various physonectid siphonophores. In the stem of Nanomia bijuga, this antiserum stained an ectodermal nerve net, which was interrupted, at regular intervals, by transverse collars of neurons. Injection of Lucifer yellow into the giant axon of the stem showed that this axon was dye-coupled to an ectodermal nerve net that resembled the RFamide-positive network. Ectodermal nets of neurons were also found in the pneumatophore, gastrozooids, tentacles and tentilla. At the junctions of the pneumatophore, the gastrozooids, the dactylozooids and the gonozooids with the stem, and at the junctions of tentacles and tentilla, collars or rings of neurons occurred. The stem was connected to the phyllozooids and nectophores by muscular lamellae, which were bordered by chains of neurons. At the margin of the nectophores, an immunoreactive nerve ring was found. Connected to this ring and located in theseitliche Zapfen (sidely-located patche), were two agglomerations of nerve cells. On the upper side of the bell margin, positioned at 90° relative to the seitliche Zapfen, a delta-shaped neuronal structure was found. This structure was connected to the nerve ring and was associated with a muscle, which ran a short distance along the exumbrellar surface.The nervous systems of Agalma elegans, Forskalia edwardsi, Forskalia leuckarti and Halistemma rubrum resembled that of Nanomia bijuga in all major respects.     

The effect of grazing intensity on phosphorus spiralling in autotropic streams

The effect of grazing on primary productivity and phosphorus cycling in autotrophic streams was studied using the snail Goniobasis clavaeformes. Snails were added to each of three replicate laboratory stream channels, receiving once-through flow of groundwater, in densities of 2.1, 3.0, and 4.2 g ash free dry mass (AFDM)/m². A fourth channel received no snails and served as an ungrazed control. Presence of snail grazers resulted in a large reduction in aufwuchs biomass, primary productivity, and biotic phosphorus uptake; a modest reduction in fine particulate organic matter (FPOM); and an increase in the fraction of stream particulate organic matter (POM) exported as seston. Although primary production and aufwuchs biomass continued to decline with increasing snail density, phosphorus uptake increased. This increased phosphorus uptake is attributed to abiotic sorption to inorganic surfaces exposed as a result of efficient removal of aufwuchs at high snail densities. Although snail densities were chosen to bracket the density measured in a natural stream, the experimental densities may result in considerably higher grazing pressure on aufwuchs due to the absence of alternate food sources (e.g., coarse particulate organic matter) usually found in natural streams. Presence of snail grazers increased the spiralling length of phosphorus, primarily by reducing aufwuchs biomass and consequently reducing uptake of phosphorus from the water. Presence of snails also increased downstream transport velocity of phosphorus bound to organic particles. These results follow the patterns predicted in a previous theoretical analysis for mildly phosphorus-limited streams.     

Isolation and characterization of the positive regulatory gene ADR1 from Saccharomyces cerevisiae.

The DNA segments containing the ADR1 gene and a mutant allele, ADR1-5c, have been isolated by complementation of function in Saccharomyces cerevisiae. The ADR1 gene is required for synthesis of the glucose-repressible alcohol dehydrogenase (ADHII) when S. cerevisiae cells are grown on a nonfermentable carbon source, whereas the ADR1-5c allele allows ADHII synthesis even during glucose repression. A plasmid pool consisting of yeast DNA fragments isolated from a strain carrying the ADR1-5c allele was used to transform a strain containing the adr1-1 allele, which prevents ADHII depression. Transformants were isolated which expressed ADHII during glucose repression. A plasmid isolated from one of these transformants was shown to carry the ADR1-5c allele by its ability to integrate at the chromosomal adr1-1 locus. The wild-type ADR1 gene was isolated by colony hybridization, using the cloned ADR1-5c gene as a probe. The ADR1-5c and ADR1 DNA segments were indistinguishable by restriction site mapping. A partial ADR1 phenotype could be conferred by a 1.9-kilobase region, but DNA outside of this region appeared to be necessary for normal activation of ADHII by the ADR1 gene.     

Varicose Veins,Deep Vein Thrombosis,and Haemorrhoids: Epidemiology and Suggested Aetiology

Current concepts on the aetiology of varicose veins, deep vein thrombosis, and haemorrhoids have been examined and, in the light of epidemiological evidence, found wanting.It is suggested that the fundamental cause of these disorders is faecal arrest which is the result of a low-residue diet.     

Further observations on the fine structure and development of the infracerebral complex (“infracerebral gland”) of Nereis limnicola (Annelida,Polychaeta)

Cell and Tissue Research - The infracerebral complex consists of: (a) two types of ependymoid infracerebral cells located on the ventral surface of the brain, adjacent to a coelomic sinus and blood...