Analyse von zwei Legumin-Genfamilien der Ackerbohne (Vicia faba L.)

DNA clones representing two subfamilies A and B of legum in genes and a recombinant phage containing a complete legumin B gene have been isolated and characterized by DNA sequencing. A DNA fragment harbouring the legumin B gene and adjacent sequences was used for Ti-mediated transfer into tobacco cells.     

Role of 2-deoxy-D-glucose in the inhibition of phagocytosis by mouse peritoneal macrophage

2-Deoxy-D-glucose inhibits Fc and complement receptor-mediated phagocytosis of mouse peritoneal macrophages. To understand the mechanism of this inhibition, we analyzed the 2-deoxy-D-glucose metabolites in macrophages under phagocytosis inhibition conditions and conditions of phagocytosis reversal caused by glucose, mannose and 5-thio-D-glucose, and compared their accumulations under these conditions. Macrophages metabolized 2-deoxy-D-glucose to form 2-deoxy-D-glucose 6-phosphate, 2-deoxy-D-glucose 1-phosphate, UDP-2-deoxy-D-glucose, 2-deoxy-D-glucose 1, 6-diphosphate, 2-deoxy-D-gluconic acid and 2-deoxy-6-phospho-D-gluconic acid. The level of bulk accumulation as well as the accumulation of any of these 2-deoxy-D-glucose metabolites did not correlate with changes in macrophage phagocytosis capacities caused by the reversing sugars. 2-Deoxy-D-glucose inhibited glycosylation of thioglycolate-elicited macrophage by 70-80%. This inhibition did not cause phagocytosis inhibition, since (1) the reversal of phagocytosis by 5-thio-D-glucose was not followed by increases in the incorporation of radiolabelled galactose, glucosamine, N-acetylgalactosamine or fucose; (2) cycloheximide at a concentration that inhibited glycosylation by 70-80% did not affect macrophage phagocytosis. The inhibition of protein synthesis by 2-deoxy-D-glucose similarly could not account for phagocytosis inhibition, since cycloheximide, when used at a concentration that inhibited protein synthesis by 95%, did not affect phagocytosis. 2-Deoxy-D-glucose lowered cellular nucleoside triphosphates by 70-99%, but their intracellular levels in the presence of different reversing sugars did not correlate with the magnitude of phagocytosis reversal caused by these sugars. The results show that 2-deoxy-D-glucose inhibits phagocytosis by a mechanism distinct from its usual action of inhibiting glycosylation, protein synthesis and depleting energy supplies, mechanisms by which 2-deoxy-D-glucose inhibits other cellular processes.     

Immunohistochemical studies on the localization of cellular retinol-binding protein in rat testis and epididymis

The immunohistochemical localization of cellular retinol-binding protein (CRBP) was studied in rat testis and epididymis. Parallel studies were also carried out on the localization of plasma retinol-binding protein (RBP) and transthyretin (TTR) in testis. The studies employed antibodies purified by immunosorbent affinity chromatography, permitting the specific staining and localization of each antigen by the unlabeled peroxidase-antiperoxidase method. For RBP and TTR, specific immune staining was found in the interstitial spaces between the seminiferous tubules, and not in the tubules themselves. In contrast, strong specific immune staining for CRBP was found in the seminiferous tubules, with a striking localization within Sertoli cells. Moreover, a distinct cyclic variation of specific staining for CRBP within Sertoli cells was observed during the spermatogenic cycle. This cyclic variation was seen with regard to both the intensity of staining and to the anatomic distribution of CRBP within the Sertoli cells. Within the epididymis CRBP was selectively localized to the proximal portion of the caput epididymidis, with variations in intensity of the staining of the epithelium of the ducts in different histological zones. Specific immune staining for CRBP was very weak or absent in the other portions of the epididymis. These results were confirmed by radioimmunoassay. Vitamin A-deficient rats showed markedly reduced specific immune staining for CRBP in both testes and epididymides, and greatly reduced levels of CRBP in these tissues on radioimmunoassay. These studies on the localization of CRBP provide information concerning the specific cells and anatomic loci within the testis and epididymis where retinol may be playing an important role in sperm formation and maturation.     

G-11 staining in Turner's syndrome with mos 45,X/46,X,r(?)

Mos 45,X/46,X,r(?) in 4 patients with Turner's syndrome and no signs of virilization, and in one pair of monozygotic twins, one of them with clitoral hypertrophy, was studied using combined cytogenetic techniques and specially G-11 staining for the characterization of the X or Y origin of the rings. In all 6 patients the ring was G-11 positive, attesting its Y origin. Both twins were operated and bilateral streak gonads with a bilateral nodule of testicular tissue were found. Similar small rings were also studied in one patient with mos 46,XX/46,X,r(X) and in one nonvirilized Turner's syndrome patient with a larger ring; in these two cases the ring was G-11 negative. It seems that the small rings occasionally found in Turner's syndrome are more frequently from Y origin and therefore prophylactic gonadectomy should be considered.     

Survival of Bacteria and Fungi in Relation to Water Activity and the Solvent Properties of Water in Biopolymer Gels

Survival of bacteria (Rhizobium, Agrobacterium, and Arthrobacter spp.), fungal spores (Penicillium sp.), and yeasts (Saccharomyces sp.) was studied in relation to water activity (a_w) and the presence of nutritive solutes. The cells were entrapped in polysaccharide gels, as is done to immobilize cells or enzymes, and then dehydrated. The number of living cells (10¹⁰ g of dry polymer⁻¹) remained constant for periods of storage of >3 years at 28°C when the inocula were kept at an a_w of <0.069. At a_w values between 0.069 and 0.83 the number of survivors diminished more and more rapidly as the a_w was raised. For a given a_w and organism, there were large differences in survival rate as a function of the nutritive solutes used to culture the microorganisms. Low-molecular-weight compounds (with three or five carbon atoms) had a deleterious effect on survival, whereas compounds of higher molecular weight (C₆ to C₁₂) had a protecting effect. Thus, the a_w alone was not a sufficient explanation for the deterioration of the inocula. Survival seemed to be more directly related to some properties of the water in the biopolymer. New concepts such as the discontinuity of properties of water and the point of mobilization of solutes, already proposed by Duckworth and Kelly (J. Food Technol. 8:105-113, 1973) and Seow (J. Sci. Food Agric., 26:535-536, 1975), have been taken into consideration to explain the interactions of water with the biopolymer and their specific effects on the microorganisms.     

Identification of the polypeptide encoded by the URF-1 gene of Neurospora crassa mtDNA

Two peptides, potentially representing antigenic determinants of a proposed gene product, were synthesized. The peptide sequences were deduced from the nucleotide sequence of the unidentified reading frame (URF)1 of the Neurospora crassa mitochondrial genome. Specific antisera to the synthetic peptides were produced. The antibodies recognized a single polypeptide species with an apparent relative molecular mass of about 30 000. The mitochondrial origin of this polypeptide was verified by in vivo labelling experiments in the presence of cycloheximide, as well as by in vitro translation using isolated mitochondria. The chemical identification of the protein was performed by partial radiosequencing of the N-terminal portion of the immunoprecipitated URF-1 product. The amount of URF-1 polypeptide present in N. crassa mitochondria is in the range of 1-2%. The protein is a constituent of the inner envelope of the organelle and probably part of a more complex membrane unit.     

In-vitro pulsatile flow visualization studies in a pulmonary artery model

In-vitro pulsatile flow visualization studies were conducted in an adult-sized pulmonary artery model to observe the effects of valvular pulmonic stenosis on the flow fields of the main, left and right pulmonary arteries. The flow patterns revealed that as the degree of stenosis increased, the jet-type flow created by the valve became narrower, and it impinged on the far (distal) wall of the left pulmonary artery further downstream from the junction of the bifurcation. This in turn led to larger regions of disturbed turbulent flow, as well as helical-type secondary flow motions in the left pulmonary artery, compared to the right pulmonary artery. The flow field in the main pulmonary artery also became more disturbed and turbulent, especially during peak systole and the deceleration phase. The flow visualization observations have been valuable in helping to conduct further quantitative studies such as pressure and velocity field mapping. Such studies are important to understanding the fluid mechanics characteristics of the main pulmonary artery and its two major branches.     

Plant growth regulation with triazoles of the dioxanyl type

The plant growth retarding activities of several dioxanylalkyl and dioxanylalkenyl triazoles were determined in seedlings of barley, rice, and oilseed rape. Out of these groups some substances proved to be among the most efficient growth retardants known. The compound 1-(4-trifluormethyl)-2-(1,2,4-triazolyl-(1))-3-(5-methyl-1,3-dioxan-5-yl)-propen-3-ol was investigated more closely. Shoot growth is reduced more intensively than root growth by this compound. At lower dosages root growth may even be stimulated. The action of this retardant can be antagonized by gibberellin A₃ and byent-kaurenoic acid. It is suggested that its main biochemical action is to block the reactions that lead froment-kaurene toent-kaurenoic acid in the course of gibberellin biosynthesis.     

Concordance of experimentally mapped or predicted Z-DNA sites with positions of selected alternating purine-pyrimidine tracts.

The recent electronmicroscopic and biochemical mapping of Z-DNA sites in phi X174, SV40, pBR322 and PM2 DNAs has been used to determine two sets of criteria for identification of potential Z-DNA sequences in natural DNA genomes. The prediction of potential Z-DNA tracts and corresponding statistical analysis of their occurrence have been made on a sample of 14 DNA genomes. Alternating purine and pyrimidine tracts longer than 5 base pairs in length and their clusters (quasi alternating fragments) in the 14 genomes studied are under-represented compared to the expectation from corresponding random sequences. The fragments [d(G X C)]n and [d(C X G)]n (n greater than or equal to 3) in general do not occur in circular DNA genomes and are under-represented in the linear DNAs of phages lambda and T7, whereas in linear genomes of adenoviruses they are strongly over-represented. With minor exceptions, potential Z-DNA sites are also under-represented compared to random sequences. In the 14 genomes studied, predicted Z-DNA tracts occur in non-coding as well as in protein coding regions. The predicted Z-DNA sites in phi X174, SV40, pBR322 and PM2 correspond well with those mapped experimentally. A complete listing together with a compact graphical representation of alternating purine-pyrimidine fragments and their Z-forming potential are presented.     

Sodium-alanine cotransport in oocytes ofXenopus laevis: Correlation of alanine and sodium fluxes with potential and current changes

Summary The sodium-dependentl-alanine transport across the plasma membrane of oocytes ofXenopus laevis was studied by means of [¹⁴C]-l-alanine,²²Na⁺ and electrophysiological measurements. At fixed sodium concentrations, the dependence of alanine transport on alanine concentration follows Michaelis-Menten kinetics; at fixed alanine concentrations, the transport varies with sodium concentration with a Hill coefficient of 2. In the presence of sodium the uptake of alanine is accompanied by a depolarization of the membrane. Under voltage-clamp conditions this depolarization can be compensated by an inward-directed current. Assuming that this current is carried by sodium we arrive at a 21 stoichiometry for the sodium-alanine cotransport. The assumption was confirmed by direct measurements of both sodium and alanine fluxes at saturating concentrations of the two substrates, which also yielded a stoichiometry close to 21. The sodium-l-alanine cotransport is neither inhibited by furosemide (0.5 mmol/liter) nor by N-methyl amino isobutyric acid (5 mmol/liter). A 20-fold excess ofd-alanine overl-alanine caused about 60% inhibition.