Seasonal succession in the plankton of a naturally acidic, highly humic lake in Northeastern Ohio, USA

A 13 month study of the plankton in a naturally acidic bog lakeshowed high algal biovohune, year-round dominance by flagellatesand mid-summer dominance by Gonyostomum semen. Zooplankton abundanceand species richness was very low. Rotifers were the year-rounddominants.     

Metallothionein induction by nonsteroidal antiinflammatory drugs

In the present study we report on the effects of commonly used nonsteroidal antiinflammatory drugs on metallothionein (MT) and MT-I mRNA levels. A single dose of chloroquine (100 mg/kg), diclofenac (100 mg/kg), indomethacin (10 mg/kg), or piroxicam (100 mg/kg) was administered ip to C57B1 mice. After 18 h, MT levels were determined with a Cd-saturation radioassay. MT-I mRNA levels were measured by Northern Blot analyses using a probe containing the mouse MT-I gene. All drugs tested caused an increase in the MT content of the liver but not of the kidneys and lung. The lowest and highest effects were observed with chloroquine (8 times the control value) and diclofenac (18 times), respectively. In accordance with the stimulation of MT synthesis, increased accumulation of hepatic MT-I mRNA could be demonstrated. These results indicate that elevated MT levels may contribute to the effectiveness of nonsteroidal antiinflammatory drugs in the treatment of rheumatoid arthritis (RA).     

Glucose as a substrate in recombinant strain fermentation technology

Summary Glucose supplements to complex growth media of Escherichia coli affect the production of a recombinant model protein under the control of a temperature-sensitive expression system. The bacterial Crabtree effect, which occurs in the presence of glucose under aerobic conditions, not only represses the formation of citric acid cycle enzymes, but also represses the formation of the plasmid-encoded product even though the synthesis of this protein is under the control of the temperature-inducible lambda P _R-promoter/cl857-repressor expression system. When the recombinant E. coli is grown at a moderate temperature (35° C) with protein hydrolysate and glucose as substrates, a biphasic growth and production pattern is observed. In the first phase, the cells grow with a high specific growth rate, utilizing glucose and forming glutamate as a byproduct. The intracellular level of recombinant protein is very low in this phase. Later, glutamate is consumed, indicating an active citric acid cycle. The degradation of glutamate is accompanied by the intracellular accumulation of high amounts of recombinant protein.     

Ethanol production from xylose with a pyruvate-formate-lyase mutant of Klebsiella planticola carrying a pyruvate-decarboxylase gene from Zymomonas mobilis

Summary Grown anaerobically on d-xylose, Klebsiella planticola ATCC 33531 produced acetate, formate, lactate, CO₂ and ethanol as major end-products. A Mu-insertion mutant which lacked pyruvate-formate-lyase showed among its fermentation products more than 70% d-lactate with residual acetate, 2,3-butanediol, and traces of ethanol, formate, and CO₂. After the introduction of a plasmid carrying the gene for the enzyme pyruvate decarboxylase from Zymomonas mobilis, this Klebsiella mutant became an efficient ethanol producer. The recombinant strain produced 387 mM ethanol from 275 mM xylose in 80 h, about 83% of the theoretical maximal yield. Furthermore, this mutant consumed more than double the amount of xylose (41 g/l) compared to the wild-type, due to reduced production of inhibiting acids during growth.Dedicated to Professor Dr. Zähner on the occasion of his 60th birthday     

Influence of ethanol on the activities of 3-hydroxy-3-methylglutaryl-coenzyme A-reductase and squalene-hopene-cyclase in Zymomonas mobilis

Summary The influence of different primary aliphatic alcohols on the activities of two key enzymes in hopanoid biosynthesis of Zymomonas mobilis was investigated. By use of ¹⁴C- and ³H-labelled substrates the enzymes 3-hydroxy-3-methylglutaryl-CoA-reductase and squalene-hopenecyclase were detected with activities of 1.6 pmol x (min x mg protein)^-1 and 2.3 pmol x- (min x mg protein)^-1, respectively. Cells grown in the presence of 6% (v/v) ethanol did not show higher activities of these enzymes than cells grown in the presence of 1% (v/v) ethanol. Furthermore, 3-hydroxy-3-methylglutaryl-CoA-reductase was not activated by ethanol. However, ethanol activated the squalene-hopene-cyclase when added to the enzyme test system. Besides ethanol, propanol also had a positive effect on the squalene-hopene-cyclase: the enzyme's activity increased 1.7-fold in the presence of either alcohol at a concentration of 6% (v/v). This corresponded with a similar increase of hopanoid content of whole cells when grown in the presence of 6% (v/v) added ethanol or propanol. These results indicated that the squalene-hopene-cyclase has a regulatory function in the alcohol dependent hopanoid biosynthesis of Z. mobilis.Abbreviation HMG-CoA-reductase 3-hydroxy-3-methylglutaryl-coenzyme A-reductase     

Protease activity and proteolytic modification of cellulases from a Trichoderma reesei QM 9414 selectant

Summary The secretion of multiple forms of cellulolytic enzymes by a Trichoderma reesei QM 9414 selectant exhibiting high protease activity (T. reesei QM 9414/A 30) was investigated using monoclonal, domain-specific antibodies against cellobiohydrolase (CBH) I, CBH II and -glucosidase, and a polyclonal antibody against endoglucanase I. The pattern of appearance of these proteins was followed during growth of the fungus on Avicel cellulose, using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE)/Western blotting/immunostaining. Evidence was obtained that, at late cultivation stages, CBH I and II became partially modified to lower molecular weight components, whereas -glucosidase and endoglucanase I appeared to remain largely intact. Modification of CBH I appeared to commence from the carboxy-terminal AB region, whereas CBH II appeared to become modified both from the amino- (ABB') and the carboxy-terminal. Evidence for a protease activity that modifies the already truncated cellobiohydrolases in the culture filtrate was obtained. These results show that proteolysis at late culture stages may contribute to the multiplicity of cellulases found in T. reesei culture fluids. Initial proteolytic cleavage of CBH I and II may, however, involve an unusual protease not detectable by the azocasein method.Offprint requests to: C. P. Kubicek     

Shifts in Methanogenic Subpopulations Measured with Antibody Probes in a Fixed-Bed Loop Anaerobic Bioreactor Treating Sulfite Evaporator Condensate

A fixed-bed loop, high-rate anaerobic bioreactor treating sulfite evaporator condensate was sampled when it reached steady state and afterwards following perturbations during a 14-month period. By using immunotechnology, it was observed that shifts in methanogenic subpopulations occurred in association with perturbations, such as restarting and relocating the biomass into a different tank. Methanogens related to Methanobacterium bryantii MoHG and Methanobrevibacter smithii ALI were numerous throughout the observation period, while Methanosarcina mazei S6 and Methanosarcina thermophila TM1 were found in the early and late samples, respectively. Also, Methanobacterium formicicum was more numerous at the top portion of the bioreactor, while Methanobrevibacter arboriphilus AZ and DC were at the bottom. Sample formalinization required for prolonged storage proved suitable for antigen preservation.     

Antibody-penicillin-V-amidase conjugates kill antigen-positive tumor cells when combined with doxorubicin phenoxyacetamide

Summary The two monoclonal antibodies (mAb), L6 (anti-carcinoma), and 1F5 [anti-(B-cell-lymphoma)], were chemically linked to the enzyme penicillin-V amidase (PVA), which hydrolyzes phenoxyacetamides, to explore the potential of using mAb-enzyme conjugates for the localizaton of chemotherapeutic drugs at tumor cells. The phenoxyacetamide derivatives of doxorubicin and melphalan were prepared, yielding the less toxic amides, doxorubicin-N-p-hydroxyphenoxyacetamide (DPO) and melphalan-N-p-hydroxyphenoxyacetamide (MelPO). These were hydrolyzed by PVA to doxorubicin and melphalan respectively.In vitro studies with the L6-positive lung carcinoma cell line, H2981, and the 1F5-positive B-cell lymphoma line, Daudi, showed that DPO was 80-fold less toxic to H2981 cells and 20-fold less toxic to Daudi cells than doxorubicin, and its toxicity was substantially increased when the H2981 cells were pretreated with L6-PVA or the Daudi cells were pretreated with 1F5-PVA. The cytotoxic effect was antigen-specific, since only the binding mAb-enzyme conjugate increased the cytotoxicity of the prodrug. MelPO was more than 1000-fold less toxic than melphalan to H2981 cells and more than 100-fold less toxic than melphalan to Daudi cells. Pretreatment with the mAb-PVA conjugates did not enhance the toxicity of MelPO in either cell line, because PVA hydrolyzes the phenoxyacetamide bond of MelPO too slowly to generate a toxic level of melphalan.     

The phylogenic position of Peptococcus niger based on 16S rRNA sequence studies

A 1330 base-pair fragment of a 16S rRNA gene has been amplified, cloned and sequenced. Comparison to other 16S rRNA sequences of eubacteria showed that P. niger represents a deep branch within the subdivision "Gram-positive with Gram-negative cell walls". It is not related to peptostreptococci, representatives of this genus studied so far are more closely related to clostridia.     

Nerve growth factor: Cellular localization and regulation of synthesis

1. The role of nerve growth factor (NGF) as a retrograde messenger between peripheral target tissues and innervating sympathetic and neural crest-derived sensory neurons is supported by the observations that (a) the interruption of retrograde axonal transport has the same effects as the neutralization of endogenous NGF by anti-NGF antibodies and (b) the close correlation between the density of innervation by fibers of NGF-responsive neurons and the levels of NGF and mRNANGF in their target organs. 2. In situ hybridization experiments have demonstrated that a great variety of cells in the projection field or NGF-responsive neurons is synthesizing NGF, among them epithelial cells, smooth muscle cells, fibroblasts, and Schwann cells. 3. The temporal correlation between the growth of trigeminal sensory fibers into the whisker pad of the mouse and the commencement of NGF synthesis initially suggested a causal relationship between these two events. However, in chick embryos rendered aneural by prior removal of the neural tube or the neural crest, it was shown that the onset of NGF synthesis in the periphery is independent of neurons, and is controlled by an endogenous "clock" whose regulatory mechanism remains to be established. 4. A comparison between NGF synthesis in the nonneuronal cells of the newborn rat sciatic nerve and that in the adult sciatic nerve after lesion provided evidence for the important regulatory role played by a secretory product of activated macrophages. The identity of this product is currently under investigation.