Detection of Plasmodium falciparum DNA in a microtitration plate-based hybridization test

A rapid DNA-test, depending on the affinity based hybrid collection principle, was developed for the detection of Plasmodium falciparum DNA from clinical specimens. In this method, hybridization takes place in solution and the hybrids are collected onto a solid phase for measurement. Two probes are used, one labelled with an affinity tag (biotin) and the other with a detectable label (32P). In the present test a single oligonucleotide complementary to a 21-base pair sequence which is highly repeated in the parasite genome served both as capture and detector probe. The test is a 2-h hybridization performed in streptavidin coated microtitration plate wells, onto which the labelled hybrids simultaneously bind. The sensitivity of the assay with a crude erythrocyte lysate specimen was 1.6 x 10(9) repeat units corresponding to about 160 parasites in one microliter blood. The results allowed quantification of the repeat sequences and thus estimation of the degree of parasitemia in clinical specimens.     

The Fibrin Matrix Regulates Angiogenic Responses within the Hemostatic Microenvironment through Biochemical Control

Conceptually, premature initiation of post-wound angiogenesis could interfere with hemostasis, as it relies on fibrinolysis. The mechanisms facilitating orchestration of these events remain poorly understood, however, likely due to limitations in discerning the individual contribution of cells and extracellular matrix. Here, we designed an in vitro Hemostatic-Components-Model (HCM) to investigate the role of the fibrin matrix as protein factor-carrier, independent of its cell-scaffold function. After characterizing the proteomic profile of HCM-harvested matrix releasates, we demonstrate that the key pro-/anti-angiogenic factors, VEGF and PF4, are differentially bound by the matrix. Changing matrix fibrin mass consequently alters the balance of releasate factor concentrations, with differential effects on basic endothelial cell (EC) behaviors. While increasing mass, and releasate VEGF levels, promoted EC chemotactic migration, it progressively inhibited tube formation, a response that was dependent on PF4. These results indicate that the clot’s matrix component initially serves as biochemical anti-angiogenic barrier, suggesting that post-hemostatic angiogenesis follows fibrinolysis-mediated angiogenic disinhibition. Beyond their significance towards understanding the spatiotemporal regulation of wound healing, our findings could inform the study of other pathophysiological processes in which coagulation and angiogenesis are prominent features, such as cardiovascular and malignant disease.     

Distribution of newly synthesized DT-diaphorase in rat liver

The distribution, synthesis transport, and glycosylation of rat-liver DT-diaphorase has been investigated. The enzyme could be isolated using specific antibodies, mainly from the soluble supernatant but also from microsomal vesicles, Golgi membrane, and mitochondria. 40% of the microsomal enzyme was located in the lumen or on the interior side of the membrane, the rest remaining as an integral non-extractable part of the membrane. Synthesis of DT-diaphorase takes place on both free and bound ribosomes, although it was found to be transported in a sequential manner from the rough to the smooth endoplasmic reticulum and also subsequently to the mitochondria. The rough and smooth microsomal DT-diaphorase contains covalently bound carbohydrate, but no sugar moiety could be detected bound to the cytoplasmic form of the enzyme.     

Developmental matching and the numerical matching hypothesis for neuronal cell death

The nervous system contains some of the most precisely matching cell populations in an organism. It appears that a variety of ontogenetic buffer mechanisms ensure that precise matching develops reproducibly in all nervous systems. Selective cell death—one such neural ontogenetic buffer mechanism—operates by natural selection. Our mathematical model of matching by natural selection allows a detailed analysis of Hamburger's (1975) unique neuronal cell counts for the chick limb motor systems. We conclude that the numerical matching hypothesis is not a sufficient explanation for neuronal cell death—i.e., the excess neurons of the chick spinal motor column must have an additional developmental role besides ensuring numerical parity in the final neuro-muscular matching populations.     

Mice Lacking Platelet-Derived Growth Factor D Display a Mild Vascular Phenotype

Platelet-derived growth factor D (PDGF-D) is the most recently discovered member of the PDGF family. PDGF-D signals through PDGF receptor β, but its biological role remains largely unknown. In contrast to other members of the PDGF family of growth factors, which have been extensively investigated using different knockout approaches in mice, PDGF-D has until now not been characterized by gene inactivation in mice. Here, we present the phenotype of a constitutive Pdgfd knockout mouse model (Pdgfd^-/-), carrying a LacZ reporter used to visualize Pdgfd promoter activity. Inactivation of the Pdgfd gene resulted in a mild phenotype in C57BL/6 mice, and the offspring was viable, fertile and generally in good health. We show that Pdgfd reporter gene activity was consistently localized to vascular structures in both postnatal and adult tissues. The expression was predominantly arterial, often localizing to vascular bifurcations. Endothelial cells appeared to be the dominating source for Pdgfd, but reporter gene activity was occasionally also found in subpopulations of mural cells. Tissue-specific analyses of vascular structures revealed that NG2-expressing pericytes of the cardiac vasculature were disorganized in Pdgfd^-/- mice. Furthermore, Pdgfd^-/- mice also had a slightly elevated blood pressure. In summary, the vascular expression pattern together with morphological changes in NG2-expressing cells, and the increase in blood pressure, support a function for PDGF-D in regulating systemic arterial blood pressure, and suggests a role in maintaining vascular homeostasis.     

Lebensraum, Bestand und Nahrungsaufnahme der Zahntaube,Didunculus strigirostris

Zusammenfassung Die ZahntaubeDidunculus strigirostris (Jardine 1845) weist in ihrem sehr kräftigen Schnabelbau deutliche Unterschiede zu den übrigen Taubenarten auf. Die abweichende Schnabelkonstruktion wird als eine Anpassung an die Nutzung bestimmter Nahrungspflanzen dargestellt. Die Zahntaube lebt überwiegend von Früchten der GattungDysoxylum (Meliaceae), wobei sie nur die erbsengroßen Samen aus den zähen, kirschen- bis pflaumengroßen Früchten herausschält. Der mit Einbuchtungen versehene Unterschnabel führt dabei sägende Bewegungen aus. In Zusammenhang mit den sägenden Bewegungen wird auch die innerhalb der Columbiformes einmalige Umformung des Articulare mit einer längsgestellten Vertiefung anstelle einer quer stehenden Einbuchtung sowie der entsprechenden Erhebung am Quadratum aus der Lebensweise der Zahntaube erklärbar. Untersuchungen im Verbreitungsgebiet dieser Art auf den Inseln West-Samoas weisen die Zahntaube als Baumvogel aus. Der Bestand wird auf 4800 bis 7200 Vögel geschätzt; er ist durch Rodungen des primären Regenwaldes und Bejagung gefährdet.

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Habitat, population and feeding-habits of the Tooth-billed Pigeon,Didunculus strigirostris

Summary The Tooth-billed PigeonDidunculus strigirostris (Jardine 1845) shows considerable differences in the morphology of its stout curved bill in comparison to all other pigeon species. The aberrant bill construction is explained as an adaption to the use of specific food plants. The Tooth-billed Pigeon preferably feeds on fruits of theDysoxylum genus (Meliaceae). However, exclusively pea-sized seeds are taken by cutting the viscous fruits by hooking the tip of the upper jaw into the fruit, while the lower jaw with its projections performs a sawing movement. In connexion with this sawing movement of the mandible the unique feature of the quadrate and articulare showing an antero-posterior condyle and cavity instead of the transversal one being present in all other members of the Columbidae this is explicable by considering the feeding habits of this species. Studies in Tooth-billed Pigeon habitats on the Island of Western Samoa revealDidunculus as a tree-living species. The total number of individuals is estimated at 4800 to 7200; the species is threatened by clearcutting of native forest as well as by hunting.

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Die Drucklegung der Arbeit wurde von der Christian-Albrechts-Universität zu Kiel gefördert.     

Ecological significance of individual variability in copepod bioenergetics

High interstage variability in body length and mass, reproductive state, and metabolic activity is characteristic of copepod populations from the Barents Sea and coastal waters in Sweden and Norway. The dry weight of a given copepodite stage, sampled at a given time from a homogeneous water mass, may vary by a factor of 4–5 between extreme individuals, protein and particularly lipid content being even more variable. Similarly, high variability in gut fullness and grazing rate within defined copepodite stages typically occurs at all times of the year, both when measured as in situ rate or experimentally determined rate, using homogeneous food suspensions. In accordance with this, maturation state (measured as length of gonads) and spawning (measured as rate of egg production over 24 h) are highly variable factors at the individual level. Since all these factors also influence the metabolic rate of the animals the respiratory rate (measured as ETS activity) of comparable individuals may vary by a factor of 5 or more. The results indicate that high individual variability in size and activity parameters is universal. This can not be explained by existing models of feeding behaviour, growth and development, and calls for new models, in which the nutritional history of the individual may play an important role.     

Biometry and biology of Constempellina brevicosta (Chironomidae) in a subarctic lake

Grimås, U. and Wiederholm, T. 1979. Biometry and biology of Constempellina brevicosta (Chironomidae) in a subarctic lake. – Holarct. Ecol. 2: 119-124. Constempellina brevicosta Edw. made up about 50% of the chironomids emerging from the littoral of Lake Blåsjön. The lake is impounded for hydroelectrical purposes. Constempellina was less abundant at an earlier, smaller amplitude of water level fluctuations in the same lake and much less abundant in a nearby natural lake. The species is able to survive in a frozen substratum on ice-covered bottoms. Records of early life stages and emergence data indicated a one-year life cycle with peak emergence from the littoral zone occurring in mid July. Statistical comparisons were made of size characteristics with respect to time and site of emergence and swarming. Swarming individuals were found to be significantly larger than emerging ones as measured in length of body, wing, tibia, and tarsi. Individuals swarming from mid July to August were successively smaller in all characters except basal antennal segments. Individuals swarming in June were smaller than those occurring somewhat later. The changes in size seem to reflect differences in larval habitat, with early summer material emanating from areas exposed to winter freezing. Males swarming at different sites at the same date were similar in all respects except for body size. Individuals emerging from different depths within the littoral zone at a single date were different in most respects, those from more shallow areas being smaller. Linear regression of swarm material from different dates showed a positive correlation for most characters. The correlations were particularly strong, and applied to all characters, when the early summer material was excluded. Mean AR values were successively lower throughout the season and positively correlated with size. Mean LR values were slightly higher in early summer than later. The LR values varied independantly of size. AR and LR values in swarm material varied between extremes for single individuals which were usually within 20% of the arithmetic mean, or 0.92–1.36 for AR and 0.78–1.06 for LR. Confidence limits for population estimates were within 0.04 units of the means.