Reduced natriuretic response to acute sodium loading in COMT Gene deleted mice

Background  

The intrarenal natriuretic hormone dopamine (DA) is metabolised by catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO). Inhibition of COMT, as opposed to MAO, results in a potent natriuretic response in the rat. The present study in anaesthetized homozygous and heterozygous COMT gene deleted mice attempted to further elucidate the importance of COMT in renal DA and sodium handling. After acute intravenous isotonic sodium loading, renal function was followed.     

Global phylogeographic limits of Hawaii's avian malaria

The introduction of avian malaria (Plasmodium relictum) to Hawaii has provided a model system for studying the influence of exotic disease on naive host populations. Little is known, however, about the origin or the genetic variation of Hawaii's malaria and traditional classification methods have confounded attempts to place the parasite within a global ecological and evolutionary context. Using fragments of the parasite mitochondrial gene cytochrome b and the nuclear gene dihydrofolate reductase-thymidylate synthase obtained from a global survey of greater than 13000 avian samples, we show that Hawaii's avian malaria, which can cause high mortality and is a major limiting factor for many species of native passerines, represents just one of the numerous lineages composing the morphological parasite species. The single parasite lineage detected in Hawaii exhibits a broad host distribution worldwide and is dominant on several other remote oceanic islands, including Bermuda and Moorea, French Polynesia. The rarity of this lineage in the continental New World and the restriction of closely related lineages to the Old World suggest limitations to the transmission of reproductively isolated parasite groups within the morphological species.     

Natural history and information overload: The case of Linnaeus

Natural History can be seen as a discipline paradigmatically engaged in 'data-driven research.' Historians of early modern science have begun to emphasize its crucial role in the Scientific Revolution, and some observers of present day genomics see it as engaged in a return to natural history practices. A key concept that was developed to understand the dynamics of early modern natural history is that of 'information overload.' Taxonomic systems, rules of nomenclature, and technical terminologies were developed in botany and zoology to catch up with the ever increasing amount of information on hitherto unknown plant and animal species. In our contribution, we want to expand on this concept. After all, the same people who complain about information overload are usually the ones who contribute to it most significantly. In order to understand this complex relationship, we will turn to the annotation practices of the Swedish naturalist Carl Linnaeus (1707-1778). The very tools that Linnaeus developed to contain and reduce information overload, as we aim to demonstrate, facilitated a veritable information explosion that led to the emergence of a new research object in botany: the so-called 'natural' system.     

Expression of the infectious salmon anemia virus receptor on atlantic salmon endothelial cells correlates with the cell tropism of the virus

Infectious salmon anemia (ISA) is a World Organization for Animal Health (OIE)-listed disease of farmed Atlantic salmon, characterized by slowly developing anemia and circulatory disturbances. The disease is caused by ISA virus (ISAV) in the Orthomyxoviridae family; hence, it is related to influenza. Here we explore the pathogenesis of ISA by focusing on virus tropism, receptor tissue distribution, and pathological changes in experimentally and naturally infected Atlantic salmon. Using immunohistochemistry on ISAV-infected Atlantic salmon tissues with antibody to viral nucleoprotein, endotheliotropism was demonstrated. Endothelial cells lining the circulatory system were found to be infected, seemingly noncytolytic, and without vasculitis. No virus could be found in necrotic parenchymal cells. From endothelium, the virus budded apically and adsorbed to red blood cells (RBCs). No infection or replication within RBCs was detected, but hemophagocytosis was observed, possibly contributing to the severe anemia in fish with this disease. Similarly to what has been done in studies of influenza, we examined the pattern of virus attachment by using ISAV as a probe. Here we detected the preferred receptor of ISAV, 4-O-acetylated sialic acid (Neu4,5Ac(2)). To our knowledge, this is the first report demonstrating the in situ distribution of this sialic acid derivate. The pattern of virus attachment mirrored closely the distribution of infection, showing that the virus receptor is important for cell tropism, as well as for adsorption to RBCs.     

Screening and identification of Shigella flexneri 2a virulence-related genes induced after invasion of epithelial cells

~~Screening and identification of Shigella flexneri 2a virulence-related genes induced after invasion of epithelial cells1. Jin, Q., Yuan, Z., Xu, J., Wang, Y., Shen, Y., Lu, W., Wang, J., Liu, H., Yang, J., Yang, P., Zhang, X., Zhang, J., Yang, G, Wu, H., Qu, D., Dong, J., Sun, L., Xue, Y, Zhao, A., Gao, Y., Zhu, J., Kan, B., Ding, K.. Chen, S., Cheng, H., Yao, Z., He, B., Chen, R., Ma, D., Qiang, B., Wen, Y, Hou, Y., Yu, J., Genome sequence of Shigella flexneri 2…     

Anti-actin antibodies generated against profilin:actin distinguish between non-filamentous and filamentous actin, and label cultured cells in a dotted pattern

Actin polymerization is a prominent feature of migrating cells, where it powers the protrusion of the leading edge. Many studies have characterized the well-ordered and dynamic arrangement of filamentous actin in this submembraneous space. However, less is known about the organization of unpolymerized actin. Previously, we reported on the use of covalently coupled profilin:actin to study actin dynamics and presented evidence that profilin-bound actin is a major source of actin for filament growth. To locate profilin:actin in the cell we have now used this non-dissociable complex for antibody generation, and obtained monospecific anti-actin and anti-profilin antibodies from two separate immunizations. Fluorescence microscopy revealed drastic differences in the staining pattern generated by the anti-actin antibody preparations. With one, distinct puncta appeared at the actin-rich leading edge and sometimes aligned with microtubules in the interior of the lamella, while the other displayed typical actin filament staining. Labelling experiments in vitro demonstrated failure of the first antibody to recognize filamentous actin and none of the two bound microtubules. The two anti-profilin antibodies purified in parallel generated a punctated pattern similar to that seen with the first anti-actin antibody. All antibody preparations labelled the nuclei.     

Analysis of amino acid phenylthiohydantoins by high-performance liquid chromatography using gradient elution with ethanol

The use of gradient elution with acetate-buffered ethanol for high-performance liquid chromatographic analysis of phenylthiohydantoins (PTHs) is described. The system separates all commonly encountered PTH derivatives in a total analysis time of 20 min on columns of Spherisorb 5 S ODS (4.6 × 250 mm) packed in the laboratory at moderate expense. Experience with routine operation of the method, particularly with regard to column stability is discussed. Ethanol is considerably cheaper and less toxic than previously described solvent systems.     

Diurnal variations in the kinetics of delayed luminescence from Scenedesmus obtusiusculus after exposure to various light and CO2 regimes

Delayed luminescence was measured from samples of a synchronously growing cell culture of the unicellular green alga, Scenedesmus obtusiusculus Chod., every second hour during the 24 h cell cycle under a 15/9 h lighi/dark regime. Both high (air + 2.5% CO₂) and low (0.03% CO₂) CO₂ conditions were used. Under high CO₂ conditions, while light excitation induces formation of a late (maximum reached after 10–60 s) transient peak in delayed luminescence in cells sampled after 10–16 h in the cell cycle. During most of the cell cycle low CO₂ conditions stimulate a late transient peak formation. Excitation with 700 nm light, but not with 680 nm light, induces a late transient peak in delayed luminescence under high CO₂ conditions. The transient peak is more or less pronounced depending on the cell stage. The variations might be due to a changing capacity for light-induced state I/stale II transitions during the cell cycle. It is assumed that the formation of a late transient peak in delayed luminescence is due to ATP hydrolyzation and is thus favoured by a high ATP/NADPH ratio. Hydrolyzation of ATP affects the transthylakoidal ΔpH, which regulates the reverse electron flow to the plastoquinone-pool and Q_A/Q_B, thus affecting the decay kinetics of the delayed luminescence.     

Cycles of famine and feast: the starvation and outgrowth strategies of a marineVibrio

Studies of starvation survival in non-differentiating bacteria have largely focused on physiological changes and regulatory aspects of a few master regulators such as the signal molecule ppGpp and the stationary phase alternative sigma factor, sigma S. Recent findings have implicated a series of novel key events for the entry as well as exit from starvation. The importance of alternative sigma factors other than sigma S is emerging. In addition, low molecular weight extracellular signals have been demonstrated to be essential for the induction and mediation of several adaptive responses. The importance of mRNA modification and stability for starvation survival as well as outgrowth is receiving renewedinterest. In this paper, we present the results obtained from studies of starvation survival and recovery ofVibrio sp. strain S14.