Mate quality influences multiple maternity in the sex-role-reversed pipefish Syngnathus typhle

In the pipefish Syngnathus typhle , pregnant males provide all parental care. Females are able to produce more eggs than males can brood, and consequently females compete more intensely for mates than do males, a phenomenon defined as sex-role reversal. As the genetic mating system influences the operation of sexual selection, we investigate variation in one phenotypic component of mate quality, female body size, as a possible proximate influence on mating system variation in S. typhle . Breeding trials were employed, each consisting of a single receptive male with four adult females. In each replicate, a focal male was paired either with a set of small or with a set of large females. Males were allowed to mate freely, and after several weeks of brood development, maternity of the progeny was resolved using three microsatellite loci. Males with access either to small or to large females successfully mated with a mean of 2.1 or 1.3 females, respectively, a significant difference. Results indicate that variation in female size can affect the mating system and thereby influence sexual selection in pipefish. Thus, the high rate of multiple mating by S. typhle males in the wild may be explained in part by the extensive size variation in naturally occurring, sexually mature females.     

In Vivo Microdialysis Studies on the Effects of Decortication and Excitotoxic Lesions on Kainic Acid-Induced Calcium Fluxes, and Endogenous Amino Acid Release, in the Rat Striatum

The in vivo effects of kainate (1 mM) on fluxes of 45Ca2+, and endogenous amino acids, were examined in the rat striatum using the brain microdialysis technique. Kainate evoked a rapid decrease in dialysate 45Ca2+, and an increase in the concentration of amino acids in dialysates in Ca2+-free dialysates. Taurine was elevated six- to 10-fold, glutamate two- to threefold, and aspartate 1.5- to twofold. There was also a delayed increase in phosphoethanolamine, whereas nonneuroactive amino acids were increased only slightly. The kainic acid-evoked reduction in dialysate 45Ca2+ activity was attenuated in striata lesioned previously with kainate, suggesting the involvement of intrinsic striatal neurons in this response. The increase in taurine concentration induced by kainate was slightly smaller under these conditions. Decortication did not affect the kainate-evoked alterations in either dialysate 45Ca2+ or amino acids. These data suggest that kainate does not release acidic amino acids from their transmitter pools located in corticostriatal terminals.     

Induced defence reaction in Scots pine following stem attacks by Tomicus piniperda

The induced defence reaction of Scots pine Pinus sylvestris to stem attacks by the common pine shoot beetle, Tomicus piniperda (Col, Scolytidae), was studied by inducing natural attacks on young Scots pine trees of different vigour Pruned trees were more heavily attacked by T piniperda than unpruned ones Vigorous trees successfully contained the attacking beetles within resinous lesions, whereas less vigorous trees failed to defend themselves The content of resin acids increased dramatically in the lesions on all trees, and the resin acid composition differed somewhat between some treatments Starch accumulation in the inner bark of the main stem was lower in pruned trees than in unpruned ones, and starch reserves were depleted in the most heavily attacked trees All but one of the unpruned trees survived the attack, whereas most of the severely pruned ones died following attack by beetles at densities exceeding c 300 egg galleries m⁻²     

Bioavailability of different phosphorus forms in freshwater systems

The recent literature on the bioavailability of different forms of P in freshwater systems is reviewed. Bioavailable P is defined as the sum of immediately available P and the P that can be transformed into an available form by naturally occurring processes. Methods used to estimate the bioavailable P pool, which vary between studies largely depending on the time perspective applied, are critically evaluated. Most studies on particulate P aim to determine the potentially available P pool. Potential bioavailability of particulate P is normally analysed in bioassays with algal yield determinations and the available P fraction is characterized from interpretations of results of sequential chemical extractions. NaOH-extractable P is in most studies the most algal-available P fraction. For soil samples and tributary water particulate matter, NaOH-P has often been found to be equal to algal extractable P. In other studies depletions of NaOH-P have accounted for the algal P uptake, but only a minor proportion of the fraction has been utilized. Organic P in lake water particulate matter and bed sediments of eutrophic lakes can also be algal-available to a significant extent.Studies on the bioavailability of dissolved P have often been concerned with immediate availability, or the minimum amount of available P. Such studies need other types of experimental design and normally assays with radiotracers are used. Immediately available P is frequently found to be less than P chemically assessed as dissolved reactive P (DRP) at low (< 10 µg DRP·l^-1) concentrations. However, immediate availability may also approach or exceed DRP concentrations, especially at higher concentrations. Potential bioavailability, assayed as for particulate P, may generally render higher bioavailability than P assayed as immediately available. Large fractions of dissolved P remain unutilized and are primarily found in the high molecular weight fraction of dissolved P.     

Particulate and dissolved phosphorus forms in freshwater: composition and analysis

In recent research, particulate and dissolved phosphorus components have been separated and characterized on the basis of their physical and chemical properties and partly by their origins.Classical operationally defined monitoring variables (dissolved reactive phosphorus, dissolved unreactive phosphorus and particulate phosphorus) are not congruent with known specific physical or chemical components of phosphorus in natural waters or with their bioavailability.Physical isolation of true particles, colloids and molecules of various sizes is possible at present although it is not recommended for routine use.Chemical characterization of particulate phosphorus is performed mainly by sediment extraction procedures (specialized for inorganic species) and — to a lesser degree — by cell extraction procedures (specialized for organic compounds). The extraction procedures are similar and physical preseparation or alternative procedures (e.g. enzymatic assays) are essential.Smaller colloids and dissolved compounds are physically separated by column chromatography and are often chemically characterized by degradation on the addition of specific enzymes.     

A Possible Interrelationship Between Extracellular Taurine and Phosphoethanolamine in the Hippocampus

The effect of guanidinoethane sulfonic acid (GES), an inhibitor of taurine uptake, was examined with respect to endogenous amino acids in the hippocampus of the freely moving rabbit. GES increased the extracellular levels of both taurine and phosphoethanolamine (PEA), other amino acids being unaffected. However, long-term oral administration of GES selectively reduced endogenous taurine levels. The effect of GES on PEA appeared to be a consequence of the elevated extracellular taurine as exogenously administered taurine per se increased PEA levels in the extracellular space. The findings are discussed in conjunction with the proposed membrane-stabilizing effects of taurine.     

Vergleichende Untersuchungen Der Wildtypen Verschiedener Drosophila-Arten An Hand Von Transplantationen Der Augenanlagen

Molecular Genetics and Genomics -     

Die Beeinflussung der Vitalität durch multiple Allele,untersucht an vestigial-allelen von Drosophila melanogaster

Ohne ZusammenfassungPhil. Diss. Greifswald, auf Anregung von Prof. G.Just, aus Mitteln derNotgemeinschaft der Deutschen Wissenschaft und derGesellschaft von Freunden und Förderern der Universität Greifswald unterstützt.     

Proteoglycan production in disomic and trisomy 7-carrying human synovial cells.

To gain further insight into the synthesis and structure of the synovial matrix of joints, we have established cell cultures from synovial specimens and elaborated their production of hyaluronan and proteoglycans. The cultures secreted mainly the small proteoglycan decorin, but also considerable amounts of the related biglycan and the large proteoglycan versican. Only minor amounts of heparan sulfate proteoglycans were found. All cultures also had a high production of hyaluronan, which highlights the important role for normal joint function of these cells. In joint diseases, a common feature is the presence of an extra chromosome 7 (trisomy 7) in the synovial cells. To study the possible consequences of trisomy 7 on the synovial cell function, we extended our study to cultures that had been sub-cloned to contain high amounts of trisomy 7-carrying cells. These cell cultures had approximately four times more versican than their disomic counterparts in the cell culture medium, indicating that versican may be a mediator in the processes of joint destructive disorders. To find an explanation for this increase in versican, we investigated the expression/secretion of PDGF-AA and IL-6, cytokines with their genes located to chromosome 7. Indeed, both these cytokines were increased in the cultures with high frequencies of trisomy 7. We then added the two cytokines to cell cultures of disomic synovial cells, but only cells treated with IL-6 displayed an increased amount of versican. Thus, we suggest that the increased amount of versican in cultures of trisomy 7-carrying cells relates to an autocrine loop involving an increased IL-6 production.