Rhizome dynamics and resource storage in Phragmites australis

Seasonal changes in rhizome concentrations of total nonstructural carbohydrates (TNC), water soluble carbohydrates (WSC), and mineral nutrients (N, P and K) were monitored in two Phragmites australis stands in southern Sweden. Rhizome biomass, rhizome length per unit ground area, and specific weight (weight/ length ratio) of the rhizomes were monitored in one of the stands.Rhizome biomass decreased during spring, increased during summer and decreased during winter. However, changes in spring and summer were small (< 500 g DW m-2) compared to the mean rhizome biomass (approximately 3000 g DW m^–2). Winter losses were larger, approximately 1000 g DW m-2, and to a substantial extent involved structural biomass, indicating rhizome mortality. Seasonal changes in rhizome length per unit ground area revealed a rhizome mortality of about 30% during the winter period, and also indicated that an intensive period of formation of new rhizomes occurred in June.Rhizome concentrations of TNC and WSC decreased during the spring, when carbohydrates were translocated to support shoot growth. However, rhizome standing stock of TNC remained large (> 1000 g m^–2). Concentrations and standing stocks of mineral nutrients decreased during spring/ early summer and increased during summer/ fall. Only N, however, showed a pattern consistent with a spring depletion caused by translocation to shoots. This pattern indicates sufficient root uptake of P and K to support spring growth, and supports other evidence that N is generally the limiting mineral nutrient for Phragmites.The biomass data, as well as increased rhizome specific weight and TNC concentrations, clearly suggests that reloading of rhizomes with energy reserves starts in June, not towards the end of the growing season as has been suggested previously. This resource allocation strategy of Phragmites has consequences for vegetation management.Our data indicate that carbohydrate reserves are much larger than needed to support spring growth. We propose that large stores are needed to ensure establishment of spring shoots when deep water or stochastic environmental events, such as high rhizome mortality in winter or loss of spring shoots due to late season frost, increase the demand for reserves.     

Streptomycetes possess peptidyl-prolyl cis-trans isomerases that strongly resemble cyclophilins from eukaryotic organisms

A functionally active 17.5 kDa peptidyl-prolyl cis-trans isomerase was purified to homogeneity from Streptomyces chrysomallus, a Gram-positive filamentous bacterium. Characterization of the enzyme revealed inhibition and binding characteristics, against the immunsuppressive drug cyclosporin A, which were similar to cyclophilins from eukaryotes such as mammals, plants, fungi and yeasts, but different from those of cyclophilins from enterobacteria such as Escherichia coli. The amino acid sequence of the S. chrysomallus cyclophilin, as deduced from the gene sequence, revealed a striking degree of amino acid sequence identity with the corresponding 17 kDa proteins of humans (66%), Neurospora (70%) and yeast (69%). Comparison with cyclophilin sequences from the Gram-negative enterobacteria revealed much less homology (25% identity with E. coli b, 23% identity with E. coli a). Cyclophilin was detected in each of the four other Streptomyces species tested. The cyclophilins from the various streptomycetes differed in size, varying between 17 and 20.5 kDa. The cyclophilins were abundant in the Streptomyces cells, and present throughout growth.     

Monitoring and control of biotechnological production processes by Bio-FET-FIA-sensors

Summary Single and multisensor field effect transistors (FET) with a pH-sensitive Si/SiO₂/Si₃N₄/Ta₂O₅-gate and reference electrode (for single sensor) were developed and used for manufacturing the following biological (Bio)-FETs: for glucose analysis, glucose oxidase-FET (GOD-FET); for urea analysis, urease-FET; and for cephalosporin C analysis, cephalosporinase-FET. The GOD-FETs were integrated into flow injection analysis (FIA) of the Eppendorf variables analyser (EVA) system and used for monitoring the glucose concentration in microbial cultivation and production processes with recombinant Escherichia coli K12 MF, recombinant E. coli JM103, Saccharomyces cerevisiae H620, and Candida boidinii. Urease-FET-FIA was used to monitor the urea concentration in a simulated cultivation of Cephalosporium acremonium and urease-FET-FIA and GOD-FET-FIA for the monitoring of urea and glucose concentrations in simulated S. cerevisiae cultivations.     

Regulation of cellular immune response against autologous human melanoma. I. Evidence for cell-mediated suppression of in vitro cytotoxic immune response

The potential existence of down-regulation of cytotoxic immune response against an autologous human melanoma line was investigated as a possible explanation for cytotoxic unresponsiveness against the autologous melanoma cells. The melanoma cell line, PJ-M, was established and lymph node resident lymphocytes (LNL) were isolated from a lymph node which was partially infiltrated with the melanoma cells. Autologous peripheral blood lymphocytes (PBL) were sensitized in in vitro co-culture (IVC) against radiated PJ-M cells in the presence or absence of PJ-M-sensitized LNL and enriched suppressor (OKT8+) or inducer (OKT4+) LNL populations, and were assayed for cytotoxicity in a 4-hr 51Cr-release microcytotoxicity assay. Significant cytotoxic response against PJ-M could be generated in the PBL, but not in the LNL. The addition of sensitized, unfractionated LNL, OKT8+, or OKT4+ LNL populations abrogated cytotoxic response in the PBL against PJ-M. The suppression of cytotoxic response was induced selectively against the PJ-M targets, because IVC of PBL in the presence of the sensitized LNL did not affect the generation of polyclonal cytotoxic alloreactivities, nor did they abrogate the generation of cytotoxic response against allogeneic targets in IVC against the corresponding allogeneic targets. These results suggest the possibility that cytotoxic immune response against the autologous melanoma cells might have been suppressed by the individual's own immunoregulatory circuit.     

The involvement of the major surface glycoprotein (gp63) of Leishmania promastigotes in attachment to macrophages

The interaction between the macrophage and the parasite plays a central role in the continued success of Leishmania infection. The promastigote surface ligand, and its complementary macrophage membrane receptor, involved in attachment and phagocytosis are likely to exert considerable influence over the outcome of a new infection. In this study, we report experiments pertaining to one such parasite membrane protein. Initial examination of promastigote surface proteins by radiolabeling and two-dimensional-polyacrylamide gel electrophoresis revealed an abundant polypeptide with an apparent m.w. of 63,000. Lectin-binding studies indicated that it was a glycoprotein containing mannose, N-acetyl glucosamine, and N-acetyl galactosamine residues. Monospecific antiserum raised against this glycoprotein, gp63, decorated the entire promastigote plasmalemma. Univalent antibody fragments from this antiserum blocked the interaction between promastigotes and macrophages by inhibiting attachment. Anti-gp63-inhibition reduced parasite/macrophage binding to 30 to 35% of the control binding level. Additional evidence of the involvement of gp63 in attachment to macrophages was provided by studies that made use of gp63-containing proteoliposomes. These vesicles were avidly phagocytosed by macrophages. Uptake of the gp63-containing liposomes was suppressed by greater than 90% by both anti-gp63 F(ab) fragments and the oligosaccharide mannan, indicating that their phagocytosis was receptor dependent. These results demonstrate that the abundant glycoprotein gp63 plays an important role in attachment of promastigotes to macrophages, and attachment via this parasite ligand is sufficient to trigger phagocytosis.     

Nitrogen in shoot litter,root litter and root exudates from nitrogen-fixingAlnus incana

Summary A pot experiment withAlnus incana (L.) Moench growing in sand was set up to compare the amounts of nitrogen released from plants shoot litter with that released below ground as root litter and/or root exudation. No nitrogen fixation by free-living microorganisms was found in the sand and the increased nitrogen content of the plant + soil system was therefore due to nitrogen fixation byFrankia in the alder root-nodules. Most of the nitrogen released from the plants was in the nitrogen-rich leaf and other shoot litter. Only small amounts of nitrogen were found in the drainage water from the pots and were recorded as increased nitrogen content of the sand.     

Exceptionally high copy numbers of a staphylococcal plasmid in Bacillus subtilis revealed by a sandwich hybridization technique

Abstract The copy number of a pUB110 derivative, pKTH10, containing the α-amylase gene from Bacillus amyloliquefaciens , was determined, using an assay based on a sandwich hybridization technique. In this method, a known gene on the plasmid is hybridized between two non-overlapping fragments of that same gene, cloned into separate vectors. One fragment is used as a radiolabelled probe and the other bound to a filter, forming a three-component, 'sandwich' hybrid when the relevant gene is present in the sample. Since the hybridization can only take place in the presence of the relevant gene, the amount of radioactivity binding to the filters will be proportional to the concentration of this gene in the sample. We utilized the α-amylase gene on the plasmid to form the sandwich hybrid. The copy number was of a totally different magnitude from what has previously been reported, and ranged from 2500 copies/viable cell in early logrithimic growth phase to about 500 in late stationary phase.     

Two new species of Heterokrohnia (Chaetognatha) from Antarctic waters

Summary Two new species of the genus Heterokrohnia, H. longidentata and H. fragilis, are described and compared with the other three known Heterokrohnia species, H. mirabilis Ritter-Záhony 1911; H. bathybia Marumo and Kitou 1966 and H. involucrum Dawson 1968. The species have been found at great depths (1,000 m–2,000 m) near Elephant Island, north of the Antarctic Peninsula.