Elimination of protein-food ingested into the crop, and failure of ovarian development in female mosquitoes, Culex pipiens pollens.

ABSTRACT. Sugar-free egg albumin solution was 'force fed' to female C.pipiens pallens Coquillett, by first stimulating their labella briefly with 1.0 M sucrose, so that they then took the protein meal into the crop. This protein-food was nevertheless easily eliminated by the females, totally undigested, so that it failed to activate oogenesis, just as sugared albumin fails to do so also.     

An activity-dependent determinant of synapse elimination in the mammalian brain

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On connectedness of ordinary two-way elimination of heterogeneity designs

For certain subclasses of ordinary, not necessarily equireplicated, two-way elimination of heterogeneity designs, necessary and sufficient conditions are established for row connectedness and column connectedness of a design to imply its connectedness. The criteria obtained strengthen earlier results pertaining to this problem.     

Natural Selection or the Non-survival of the Non-fit

The effects of natural selection as a process in natural populations differs from 'survival of the fittest' as it was formulated by Darwin in his 'Origin of Species'. The environment of a population exists of continuous changing conditions, which are heterogeneous in space. During its life each individual successively meets with differing conditions. During these confrontations the individual may appear to be 'unfit' or 'unlucky' and may die. If it survives it will meet the following conditions to which it is 'tested' anew, a.s.o. Hence, many individuals being less fit under certain conditions will survive and reproduce, because they did not meet a deadly moment. Therefore, being 'fit' only refers to special prevalent conditions. In each generation the individuals thus being 'unfit' will be eliminated together with the 'unlucky' ones. All other individuals will survive and reproduce, notwithstanding their properties.Hence, natural selection results in the 'non-survival of the non-fit' rather than in 'survival of the fittest', because being 'fit' simply means 'having survived and reproduced', whereas being 'unfit' can be connected with many kinds of properties and environmental conditions, e.g. being killed by a predator. Only after many generations (hundreds or even thousands) the effect of eventually dominating properties of the survivors may result in a set of properties suggesting an overall 'survival of the fittest'. This was what Darwin wanted to explain as he was mainly interested in evolutionary processes.As natural selection, as an ecological process, cannot be considered in each generation to be 'survival of the fittest', many ecological concepts supposed to be connected with selection resulting in 'survival of the fittest' within a few generations, such as the dominant role of competition, the critical level of the costs of reproduction, the need of optimization and of optimal life-history traits have to be reconsidered more critically in a less deterministic context. Moreover, these aspects of natural selection, which usually lead to impoverishment of the genepool, contradict the need of a high level of genetic heterogeneity as a base for an effective natural selection.The author gives examples of cases to which these concepts do not apply. On the other hand, natural selection resulting in 'non-survival of the non-fit' allows a continuous reshuffling of all kinds of genes and gene combinations over all kinds of genomes, also many genes with temporarily or even permanently unfavourable effects can be kept in the genepool of the population during a long series of generations. Therefore, natural selection resulting in 'non-survival of the non-fit' leads to spreading of the risk of extinction of the population over genotypes and to the gradual development and accumulation of highly sophisticated adaptations. Only in an environment that has been stationary or even almost constant and homogeneous for a long time may natural selection ultimately lead to 'survival of the fittest'.     

Protein serine/threonine phosphatases as binding proteins for okadaic acid

Recently, many potent inhibitors of protein serine/threonine phosphatases (PPs) have been found. Some of them have proven to be tumor promoters in mouse skin two-step carcinogenesis and rat liver medium-term tests. Among these inhibitors, okadaic acid (OA) selectively inhibits PP2A, and its use has therefore been proposed to facilitate analysis of biological roles of this phosphatase. OA shows bimodal effects on in vitro transformation and, in addition to such epigenetic changes, also induces marked genetic changes. OA treatment for more than 1 week flattened NIH 3T3 transformants irreversibly, with loss of the transfected genes. It is also known to induce diphtheria toxin-resistant mutations in Chinese hamster lung cells and sister chromatid exchanges (SCEs) in Chinese hamster ovary cells and human lymphocytes. To analyze roles of protein phosphatases in gene stability, we isolated OA-resistant mutants. They were proven to have a mutation in the PP2A catalytic subunit, in which cysteine 269 had beensubstituted for glycine; and it was demonstrated that this region interacts with OA. The recombinant mutant protein was 4 9-fold more resistant to OA than the wild type. Although the OA resistant mutants of CHO cells expressed high levels of P-glycoprotein, inhibition of PP2A itself was suggested to lead to SCE induction. However, the number of molecular species of PP which are known to be sensitive to OA continues to increase, and we have isolated cDNA for a novel type of OA sensitive PP. Our studies indicate that the fact that the roles of PP2A cannot be elucidated using only OA is of crucial importance.     

Dense Transposon Integration Reveals Essential Cleavage and Polyadenylation Factors Promote Heterochromatin Formation

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The Importance of the Manganese-Oxidizing Microorganism Metallogenium personatum for the Retention of Manganese in the Wahnbach Reservoir

The retention of manganese in the water of the Wahnbach reservoir was determined in mass balance calculations. The retention properties for manganese drastically decreased after the phosphorus elimination plant was taken into service. Processes controlling the distribution and mobility of manganese in the reservoir were based on the results of tests conducted to evaluate the role of the microorganism Metallogenium personatum. A substantial retention of manganese in the Wahnbach reservoir was found to be dependent on the presence of this planktonic manganese-oxidizing bacterium. The test results clearly indicate the importance of Metallogenium spec. as catalyst in the removal and oxidation of dissolved Mn(II).     

Influence of the Addition of Different Metals to an Activated Sludge System on the Enhanced Biological Phosphorus Removal

Activated sludge systems can be operated to select bacteria which accumulate phosphorus as polyphosphate. By these means, phosphate can be removed without the addition of chemical precipitants. This contribution presents results of experiments with a bench-scale purification plant for domestic sewage. The goal was to find the concentrations of relevant metal cations at which the biological P removal may be affected by competing chemical (precipitation) or physical (adsorption) processes. For this goal, increasing amounts of iron and calcium, respectively, were added into the pilot plant. During the addition of iron, the proportion of chemically (iron-) bound phosphorus increased from 10 to more than 50%. The P-release rate substantially decreased with increasing amount of added iron. An addition of small amounts of iron enhanced the long-term stability of the P elimination as a whole. During the experimental period with addition of calcium, the proportion of Ca-bound phosphorus increased from 1 to 2% to almost 15%. In batch experiments a measurable Ca-phosphate precipitation took place at a pH value of at least 8.0 and a Ca-concentration of at least 100 mg/l. The increase in hardness of the influent waste water didn't produce any positive effect on the stability of the enhanced biological phosphorus removal. The metal ions Ca²⁺, Mg²⁺ and K⁺ serve as counter-ions in the polyhosphate chains. They were identified and quantified by X-ray spectrometry in combination with scanning transmission electron microscopy. A release of Mg²⁺ and K⁺ occured simultaneously with the degration of polyphosphates (PP). The PP bound to Ca was not redox sensitive.     

Lysophosphatidic acid mediates migration of human mesenchymal stem cells stimulated by synovial fluid of patients with rheumatoid arthritis

Migration of mesenchymal stem cells plays a key role in regeneration of injured tissues. Rheumatoid arthritis (RA) is a chronic inflammatory disease and synovial fluid (SF) reportedly contains a variety of chemotactic factors. This study was undertaken to investigate the role of SF in migration of human bone marrow-derived mesenchymal stem cells (hBMSCs) and the molecular mechanism of SF-induced cell migration. SF from RA patients greatly stimulated migration of hBMSCs and the SF-induced migration was completely abrogated by pretreatment of the cells with the lysophosphatidic acid (LPA) receptor antagonist Ki16425 and by small interfering RNA- or lentiviral small hairpin RNA-mediated silencing of endogenous LPA₁/Edg2. Moreover, SF from RA patients contains higher concentrations of LPA and an LPA-producing enzyme autotoxin than normal SF. In addition, SF from RA patients increased the intracellular concentration of calcium through a Ki16425-sensitive mechanism and pretreatment of the cells with the calmodulin inhibitor W7 or calmodulin-dependent protein kinase II inhibitor KN93 abrogated the SF-induced cell migration. These results suggest that LPA-LPA₁ plays a key role in the migration of hBMSCs induced by SF from RA patients through LPA₁-dependent activation of calmodulin-dependent protein kinase II.     

A facile method for the direct synthesis of lanthionine containing cyclic peptides

A series of disulfide bridged peptides were designed as potential inhibitors of protein-protein interactions. Following solid phase synthesis, completely deprotected linear peptides were first oxidized to their disulfide analogs and then transformed into their lanthionine equivalents via a base-assisted reaction in water. Peptides consisting of cystine bridges of length i, i+3, with and without discrimination of the chiral centers, were studied for this transformation. Lanthionine peptides were also obtained directly from the reduced linear peptides under mild alkaline treatment, and the reaction proceeded via disulfide bond formation. The extent of conversion of a disulfide bridge into its lanthionine counterpart varied according to the primary sequence. Product characterization revealed diastereomeric lanthionine formation. The presence of D-amino acids, peptide conformation, and/or position of the cystine bridge are among the factors determining the facility of this reaction. Elimination of the backbone proton beta to the sulfur atom followed by intramolecular thiol Michael addition is the most likely mechanism for this transformation.