Differences in virulence of marine and freshwater isolates of viral hemorrhagic septicemia virus in vivo correlate with in vitro ability to infect gill epithelial cells and macrophages of rainbow trout (Oncorhynchus mykiss)

Two strains of viral hemorrhagic septicemia virus (VHSV) with known different virulence characteristics in vivo were studied (by a time course approach) for their abilities to infect and translocate across a primary culture of gill epithelial cells (GEC) of rainbow trout (RBT; Oncorhynchus mykiss). The strains included one low-virulence marine VHSV (ma-VHSV) strain, ma-1p8, and a highly pathogenic freshwater VHSV (fw-VHSV) strain, fw-DK-3592B. Infectivities toward trout head kidney macrophages were also studied (by a time course method), and differences in in vivo virulence were reconfirmed, the aim being to determine any correlation between in vivo virulence and in vitro infectivity. The in vitro studies showed that the fw-VHSV isolate infected and caused a cytotoxic effect in monolayers of GEC (demonstrating virulence) at an early time point (2 h postinoculation) and that the same virus strain had translocated over a confluent, polarized GEC layer by 2 h postinoculation. The marine isolate did not infect monolayers of GEC, and delayed translocation across polarized GEC was seen by 48 h postinoculation. Primary cultures of head kidney macrophages were also infected with fw-VHSV, with a maximum of 9.5% virus-positive cells by 3 days postinfection, while for the ma-VHSV strain, only 0.5% of the macrophages were positive after 3 days of culture. In vivo studies showed that the fw-VHSV strain was highly virulent for RBT fry and caused high mortality, with classical features of viral hemorrhagic septicemia. The ma-VHSV showed a very low level of virulence (only one pool of samples from the dead fish was VHSV positive). This study has shown that the differences in virulence between marine and freshwater strains of VHSV following the in vivo infection of RBT correlate with in vitro abilities to infect primary cultures of GEC and head kidney macrophages of the same species.     

Seasonal activity budget of adult baltic ringed seals

Although ringed seals are important components in oceanic and fresh water ecosystems at high latitudes, little is known about how they exploit these harsh environments. Seasonal activity and diving behaviour of 19 adult Baltic ringed seals were studied by satellite telemetry. We elaborated an activity budget for ten months of the year, extending over the period from moult to the breeding season. Seals from three main regions showed explicit site fidelity and the distributions of animals tagged from different areas did not overlap, suggesting separate stocks. Both the mean duration and the mean depth of dives peaked in June and July. Seals spent 70% (females) to 85% (males) of their time diving in June and July which decreased to 50% in late autumn. Less than one percent of dives exceeded 10 min in females, while 10% of male dives lasted longer than 10 min in June to September. Less than one percent of dives lasted for more than 25 min. Both females and males were most active during day time and hauled out predominantly during the night. Activity patterns during the summer are suggested to be correlated to energy accumulation and prey availability. The information on seasonal activity budget is crucial for developing population energetic models where interactions between ringed seals and other trophic levels can be evaluated.     

Collection and Use of Wild Edible Fungi in Nepal

Collection and Use of Wild Edible Fungi in Nepal. The significance of the contribution of wild edible mushrooms to rural livelihoods is acknowledged, but remains largely unexplored. This study investigates the collection of wild edible Nepalese fungi, which species are used, and what are the specific characteristics of the collectors and the collection. Data were collected using 282 structured questionnaires, interviews, and forest walks in 17 districts, environmental household accounts from 413 households in two communities, and a review of literature. A total of 228 species of wild fungi are confirmed to be used for food, and collection is most widespread among the high-mountain Tibeto-Nepalese ethnic groups, which collect an average of 18.1 kilograms (kg) fresh mushrooms per year per household, with some households collecting as much as 160 kg. We found no relation between wealth status and subsistence collection, although the commercial collectors are predominantly the poor earning up to six months of unskilled labor salary per season. Given the limited local trade and occurrence of globally marketed species, the scope for increasing contributions to rural livelihoods from collection of mushrooms, and risks in relation to this are briefly discussed.     

Renal nerves and nNOS: roles in natriuresis of acute isovolumetric sodium loading in conscious rats

It was hypothesized that renal sympathetic nerve activity (RSNA) and neuronal nitric oxide synthase (nNOS) are involved in the acute inhibition of renin secretion and the natriuresis following slow NaCl loading (NaLoad) and that RSNA participates in the regulation of arterial blood pressure (MABP). This was tested by NaLoad after chronic renal denervation with and without inhibition of nNOS by S-methyl-thiocitrulline (SMTC). In addition, the acute effects of renal denervation on MABP and sodium balance were assessed. Rats were investigated in the conscious, catheterized state, in metabolic cages, and acutely during anesthesia. NaLoad was performed over 2 h by intravenous infusion of hypertonic solution (50 micromol.min(-1).kg body mass(-1)) at constant body volume conditions. SMTC was coinfused in amounts (20 microg.min(-1).kg(-1)) reported to selectively inhibit nNOS. Directly measured MABPs of acutely and chronically denervated rats were less than control (15% and 9%, respectively, P < 0.005). Plasma renin concentration (PRC) was reduced by renal denervation (14.5 +/- 0.2 vs. 19.3 +/- 1.3 mIU/l, P < 0.005) and by nNOS inhibition (12.4 +/- 2.3 vs. 19.6 +/- 1.6 mlU/l, P < 0.005). NaLoad reduced PRC (P < 0.05) and elevated MABP modestly (P < 0.05) and increased sodium excretion six-fold, irrespective of renal denervation and SMTC. The metabolic data demonstrated that renal denervation lowered sodium balance during the first days after denervation (P < 0.001). These data show that renal denervation decreases MABP and renin secretion. However, neither renal denervation nor nNOS inhibition affects either the renin down-regulation or the natriuretic response to acute sodium loading. Acute sodium-driven renin regulation seems independent of RSNA and nNOS under the present conditions.     

Demonstration of Neuron-Glia Transfer of Precursors for Gaba Biosynthesis in a Co-Culture System of Dissociated Mouse Cerebral Cortex

Co-cultures of neurons and astrocytes were prepared from dissociated embryonic mouse cerebral cortex and cultured for 7 days. To investigate if these cultures may serve as a functional model system to study neuron-glia interaction with regard to GABA biosynthesis, the cells were incubated either in media containing [U-¹³C]glutamine (0.1, 0.3 and 0.5 mM) or 1 mM acetate plus 2.5 mM glucose plus 1 mM lactate. In the latter case one of the 3 substrates was uniformly ¹³C labeled. Cellular contents and ¹³C labeling of glutamate, GABA, aspartate and glutamine were determined in the cells after an incubation period of 2.5 h. The GABA biosynthetic machinery exhibited the expected complexity with regard to metabolic compartmentation and involvement of TCA cycle activity as seen in other culture systems containing GABAergic neurons. Metabolism of acetate clearly demonstrated glial synthesis of glutamine and its transfer to the neuronal compartment. It is concluded that this co-culture system serves as a reliable model in which functional and pharmacological aspects of GABA biosynthesis can be investigated. Special issue article in honor of Dr. Anna Maria Giuffrida-Stella. An erratum to this article can be found at     

Pyrosequencing as a Method for Grouping of Listeria monocytogenes Strains on the Basis of Single-Nucleotide Polymorphisms in the inlB Gene

By using pyrosequencing (i.e., sequencing by synthesis) 106 strains of different serovars of Listeria monocytogenes were rapidly grouped into four categories based on nucleotide variations at positions 1575 and 1578 of the inlB gene. Strains of serovars 1/2a and 1/2c constituted one group, and strains of serovars 1/2b and 3b constituted another group, whereas serovar 4b strains were separated into two groups.     

Early Environmental Influences on Growth of Arcto-Norwegian Cod, Gadus Morhua, From The 0-group To Adults

A high growth rate for Arcto-Norwegian cod, Gadus morhua, in the Barents Sea and adjacent areas from the larva period to the 0-group enhances survival and ultimately recruitment to the fishery. However, it appeared that high growth rates for a cohort through the 0-group were not continued as the cohort ages. Based on survey data, there was a significant negative correlation between the average length at the 0-group and its average length at ages 2 through 8. We provided evidence suggesting that this phenomenon was caused by the inter-annual variability in inflow of warm, prey-rich Atlantic water into the Barents Sea from the Norwegian Sea. Enhanced inflow provided favorable conditions for cod growth during the larva and juvenile pelagic intervals. However, this same strong inflow carried a proportion of the cohort farther to the east in the Barents Sea, where the bottom water is colder than in the west. The colder conditions experienced by such cohorts, as compared to cohorts that have a more westerly settlement, led to slower growth prior to age 2. Slow growth during this interval appeared to be the reason for these cohorts' relatively smaller mean length at older ages.     

Investigations on the Tetranychus urticae complex in north west Europe (Acari: Tetranychidae)

Two species of spider mite occur in greenhouses in the Netherlands. Tetranychus urticae Koch is usually green, can live on many plants, but cannot build up large populations on carnations; it may have a diapausing stage which is very resistant to cold. No biological races of T. urticae were found. T. cinnabarinus Boisd. is carmine-coloured, often found on carnations, and does not have a diapause. It is not resistant to cold.The two species do not interbreed. Growers of carnations have only T. cinnabarinus to deal with, and can arrange control measures accordingly.

---

Zusammenfassung Untersuchungen der Morphologie, der Wirtspflanzenwahl, der Überwinterungsweise und Kreuzingsexperimente haben gezeigt, daß in Gewächshäusern Hollands zwei Spinnmilben-Arten auftreten, nämlich Tetranychus urticae Koch und T. cinnabarinus Boids. Darüberhinaus wurde Material von Spinnmilben je einer Lokalität in Deutschland, der Schweiz und Belgien verwendet. T. urticae ist meistens grün gefärbt, lebt an einem großen Wirtspflanzenkreis, kann aber an Nelken (Dianthus caryophyllus L.) keine Populationen bilden. Diese Art geht unter dem Einfluß verschiedener biologischer Faktoren in Diapause. Während dieser Periode ist sie sehr kälteresistent. Der Winter wird an geschützten Orten verbracht. Kreuzungen zwischen Populationen verschiedener Herkunft ergaben stets eine normale Nachkommenschaft. Zucht-experimente mit diesen Populationen auf verschiedenen Wirtspflanzen ergaben keinen Hinweis für das Bestehen von biologischen Rassen bei T. urticae. T. cinnabarinus ist karminrot gefärbt und wird am häufigsten auf Nelken gefunden, obwohl in Laboratoriumsversuchen die Entwicklung an Buschbohnen (Phaseolus vulgaris L.) schneller verläuft. Diese Art tritt überhaupt nicht in Diapause ein, bleibt den Winter über an den Blättern und ist gegenüber Kältebedingungen entschieden weniger resistent als T. urticae. Kreuzungen zwischen Populationen verschiedener Herkunft ergaben immer eine normale Nachkommenschaft.Das Ausbleiben von Bastardierungen, das in Kreuzungsexperimenten zwischen den beiden Arten gefunden wurde, erbrachte den strengsten Nachweis, daß in den Gewächshäusern zwei verschiedene Arten vorkommen.Da T. cinnabarinus hauptsächlich auf Gewächshäuser mit Nelken beschränkt ist und T. urticae sich andererseits an diesen Pflanzen nicht vermehrt, haben es die Nelkenanbauer lediglich mit T. cinnabarinus zu tun, und es ergibt sich eine Möglichkeit, Nelken frei von Spinnmilbenbefall zu halten.

     

The Circadian Clock Gene Circuit Controls Protein and Phosphoprotein Rhythms in Arabidopsis thaliana

1. Download : Download high-res image (116KB)
2. Download : Download full-size image

     

Genetic affinities between adjacent populations of spider mites (Tetranychus urticae Koch)

The interbreeding potentials of nine populations of spider mites were examined. The populations were gathered from horticultural crops in different glasshouses in a limited area of Aalsmeer. A great variety of genetic incompatibilities between these populations was found. In most crossing a partial sterility of the hybrids, as measured by egg hatchability, occurred. Some crosses showed reciprocal differences. It was suggested that genetic divergence of these adjacent populations arises especially from the haplo-diploid nature of spider mites.

---

Zusammenfassung Die Kreuzbarkeit von neun Spinnmilben-Populationen wurde untersucht. Die Populationen wurden von Gartenpflanzen verschiedener Gewächshäuser in einem bestimmten Gebiet von Aalsmeer gesammelt. Es zeigte sich eine große Variabilität in der genetischen Verträglichkeit zwischen diesen Populationen. Bei den meisten Kreuzungen trat, gemessen an der Schlüpffähigkeit der Eier, eine partielle Sterilität der Hybriden auf. Einige Kreuzungen wiesen reziproke Unterschiede auf. Es wird vermutet, daß die genetische Divergenz dieser aneinandergrenzenden Populationen speziell auf der haplo-diploiden Natur der Spinnmilben beruht.