Predation by the sea urchin Strongylocentrotus droebachiensis on capsular egg masses of the whelk Buccinum undatum

We evaluated sea urchin Strongylocentrotus droebachiensis predation on egg masses of the whelk Buccinum undatum. The urchin actively grazes on the egg masses, even as they are being deposited on the bottom. Whelks preferentially lay their egg masses on vertical areas where urchin densities are 4-fold less than on flat areas. This strategy is advantageous, as experimental trials showed that the loss in the mass of capsules was 4 fewer on walls than on flat areas. Nevertheless, a high proportion of egg masses on walls show damage from predation. Urchins provided with egg masses in the laboratory, ingested the capsules at a steady rate over a 9-d period (5 urchins ingested 2.8 g.d-1). Urchins provided agar discs that included a preferred alga and whelk capsule walls ingested the discs at a rate that was half that observed for discs that only included the alga. Discs that included the preferred alga and capsule contents were eaten at the same rate as discs that only included the alga. Thus, capsule walls, but not the capsule contents, provide a defence against urchin predation. Laying aggregate egg masses likely provides only a limited advantage, as the attachment surface does not increase with the number of egg masses deposited together, so the risk of detachment increases. Consideration of the interactions between urchins and whelks is important in managing the fisheries of the two species. Copyright © Marine Biological Association of the United Kingdom 2008.published_or_final_versio

Feeding spectra and activity of the freshwater crab Trichodactylus kensleyi (Decapoda: Brachyura: Trichodactylidae) at La Plata basin

Background: In inland water systems, it is important to characterize the trophic links in order to identify the ‘trophic species’ and, from the studies of functional diversity, understand the dynamics of matter and energy in these environments. The aim of this study is to analyze the natural diet of Trichodactylus kensleyi of subtropical rainforest streams and corroborate the temporal variation in the trophic activity during day hours. Results: A total of 15 major taxonomic groups were recognized in gut contents. The index of relative importance identified the following main prey items in decreasing order of importance: vegetal remains, oligochaetes, chironomid larvae, and algae. A significant difference was found in the amount of full stomachs during day hours showing a less trophic activity at midday and afternoon. The index of relative importance values evidenced the consumption of different prey according to day moments. Results of the gut content indicate that T. kensleyi is an omnivorous crab like other trichodactylid species. Opportunistic behavior is revealed by the ingestion of organisms abundant in streams such as oligochaetes and chironomid larvae. The consumption of allochthonous plant debris shows the importance of this crab as shredder in subtropical streams. However, the effective assimilation of plant matter is yet unknown in trichodactylid crabs. Conclusions: This research provides knowledge that complements previous studies about trophic relationships of trichodactylid crabs and supported the importance of T. kensleyi in the transference of energy and matter from benthic community and riparian sources to superior trophic levels using both macro- and microfauna.Fil: Williner, Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; ArgentinaFil: de Azevedo Carvalho, Debora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Collins, Pablo Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; Argentin

Quantitative modeling of the physiology of ascites in portal hypertension

Although the factors involved in cirrhotic ascites have been studied for a century, a number of observations are not understood, including the action of diuretics in the treatment of ascites and the ability of the plasma-ascitic albumin gradient to diagnose portal hypertension. This communication presents an explanation of ascites based solely on pathophysiological alterations within the peritoneal cavity. A quantitative model is described based on experimental vascular and intraperitoneal pressures, lymph flow, and peritoneal space compliance. The model's predictions accurately mimic clinical observations in ascites, including the magnitude and time course of changes observed following paracentesis or diuretic therapy

Effect of staurosporine on the mobility and invasiveness of lung adenocarcinoma A549 cells: an in vitro study

<p>Abstract</p> <p>Background</p> <p>Lung cancer is one of the most malignant tumors, representing a significant threat to human health. Lung cancer patients often exhibit tumor cell invasion and metastasis before diagnosis which often render current treatments ineffective. Here, we investigated the effect of staurosporine, a potent protein kinase C (PKC) inhibitor on the mobility and invasiveness of human lung adenocarcinoma A549 cells.</p> <p>Methods</p> <p>All experiments were conducted using human lung adenocarcinoma A549 cells that were either untreated or treated with 1 nmol/L, 10 nmol/L, or 100 nmol/L staurosporine. Electron microscopy analyses were performed to study ultrastructural differences between untreated A549 cells and A549 cells treated with staurosporine. The effect of staurosporine on the mobility and invasiveness of A549 was tested using Transwell chambers. Western blot analyses were performed to study the effect of staurosporine on the levels of PKC-α, integrin β1, E-cadherin, and LnR. Changes in MMP-9 and uPA levels were identified by fluorescence microscopy.</p> <p>Results</p> <p>We demonstrated that treatment of A549 cells with staurosporine caused alterations in the cell shape and morphology. Untreated cells were primarily short spindle- and triangle-shaped in contrast to staurosporine treated cells which were retracted and round-shaped. The latter showed signs of apoptosis, including vacuole fragmentation, chromatin degeneration, and a decrease in the number of microvilli at the surface of the cells. The A549 cell adhesion, mobility, and invasiveness significantly decreased with higher staurosporine concentrations. E-cadherin, integrin β1, and LnR levels changed by a factor of 1.5, 0.74, and 0.73, respectively compared to untreated cells. In addition, the levels of MMP-9 and uPA decreased in cells treated with staurosporine.</p> <p>Conclusion</p> <p>In summary, this study demonstrates that staurosporine inhibits cell adhesion, mobility, and invasion of A549 cells. The staurosporine-mediated inhibition of PKC-α, induction of E-Cad expression, and decreased integrin β1, LnR, MMP-9, and uPA levels could all possibly contribute to this biological process. These results represent a significant step forward in the ongoing effort to understand the development of lung carcinoma and to design novel strategies to inhibit metastasis of the tumor by targeting the cell-adhesion, mobility and invasion of tumor cells.</p

Skeletal Muscle Modulates Huntington's Disease Pathogenesis in Mice: Role of Physical Exercise

Huntington's disease (HD) is a monogenic fatal neurodegenerative disorder. However, there is increasing evidence that HD is a pleiotropic systemic disorder. In particular, skeletal muscle metabolism is greatly affected in HD, which in turn can have a major impact on whole-body metabolism and energetic balance. Throughout an unbiased mutagenesis approach in HD mice, we have found that Scn4a, a skeletal muscle-specific sodium channel gene, is a modifier of the disease. Mutations in Scn4a enhance HD disease progression and weight loss by accelerating muscle waste and cachexia, increasing skeletal muscle activity and energy demands. At the molecular level, Scn4a mutations activate AMP-activated protein kinase (AMPK), leading to a fibre switch towards more oxidative types. These adaptations seen in HD; Scn4a double mutant muscles are similar to those observed in healthy individuals after endurance exercise training regimes. This prompted us to assess the effects of an endurance exercise regime in HD mice, independently showing that skeletal muscle adaptations leading to the activation of AMPK are detrimental for HD pathogenesis. Although it is undeniable that physical exercise can lead to many health benefits, our work shows that, at least under certain situations such as in HD, an endurance exercise routine could be a detrimental therapeutic option

Health Aspects of the Pre-Departure Phase of Migration

In the second article in a six-part PLoS Medicine series on Migration & Health, Brian Gushulak and Douglas MacPherson discuss the pre-departure phase of migration and the specific health risks and policy needs associated with this phase

Population level determinants of acute mountain sickness among young men: a retrospective study

<p>Abstract</p> <p>Background</p> <p>Many visitors, including military troops, who enter highland regions from low altitude areas may suffer from acute mountain sickness (AMS), which negatively impacts workable man-hours and increases healthcare costs. The aim of this study was to evaluate the population level risk factors and build a multivariate model, which might be applicable to reduce the effects of AMS on Chinese young men traveling to this region.</p> <p>Methods</p> <p>Chinese highland military medical records were used to obtain data of young men (n = 3727) who entered the Tibet plateau between the years of 2006-2009. The relationship between AMS and travel profile, demographic characteristics, and health behaviors were evaluated by logistic regression. Univariate logistic models estimated the crude odds ratio. The variables that showed significance in the univariate model were included in a multivariate model to derive adjusted odds ratios and build the final model. Data corresponding to odd and even years (2 subsets) were analyzed separately and used in a simple cross-validation.</p> <p>Results</p> <p>Univariate analysis indicated that travel profile, prophylactic use, ethnicity, and province of birth were all associated with AMS in both subsets. In multivariate analysis, young men who traveled from lower altitude (600-800 m <it>vs</it>. 1300-1500 m, adjusted odds ratio (AOR) = 1.32-1.44) to higher altitudes (4100-4300 m <it>vs</it>. 2900-3100 m, AOR = 3.94-4.12; 3600-3700 m <it>vs</it>. 2900-3100 m, AOR = 2.71-2.74) by air or rapid land transport for emergency mission deployment (emergency land deployment <it>vs</it>. normal land deployment, AOR = 2.08-2.11; normal air deployment <it>vs</it>. normal land deployment, AOR = 2.00-2.20; emergency air deployment <it>vs</it>. normal land deployment, AOR = 2.40-3.34) during the cold season (cold <it>vs</it>. warm, AOR = 1.25-1.28) are at great risk for developing AMS. Non-Tibetan male soldiers (Tibetan <it>vs</it>. Han, AOR = 0.03-0.08), born and raised in lower provinces (eastern <it>vs</it>. northwestern, AOR = 1.32-1.39), and deployed without prophylaxis (prophylactic drug <it>vs</it>. none, AOR = 0.75-0.76), also represented a population at significantly increased risk for AMS. The predicted model was built; the area under receiver operating characteristic curve was 0.703.</p> <p>Conclusion</p> <p>Before a group of young men first enter a high altitude area, it is important that a health service plan should be made referring to the group's travel profile and with respect to young men's ethnicity and province of birth. Low-cost Chinese traditional prophylactic drugs might have some effect on decreasing the risk of AMS, although this needs further verification.</p

Identification of GBV-D, a Novel GB-like Flavivirus from Old World Frugivorous Bats (Pteropus giganteus) in Bangladesh

Bats are reservoirs for a wide range of zoonotic agents including lyssa-, henipah-, SARS-like corona-, Marburg-, Ebola-, and astroviruses. In an effort to survey for the presence of other infectious agents, known and unknown, we screened sera from 16 Pteropus giganteus bats from Faridpur, Bangladesh, using high-throughput pyrosequencing. Sequence analyses indicated the presence of a previously undescribed virus that has approximately 50% identity at the amino acid level to GB virus A and C (GBV-A and -C). Viral nucleic acid was present in 5 of 98 sera (5%) from a single colony of free-ranging bats. Infection was not associated with evidence of hepatitis or hepatic dysfunction. Phylogenetic analysis indicates that this first GBV-like flavivirus reported in bats constitutes a distinct species within the Flaviviridae family and is ancestral to the GBV-A and -C virus clades

Caenorhabditis elegans Cyclin B3 Is Required for Multiple Mitotic Processes Including Alleviation of a Spindle Checkpoint–Dependent Block in Anaphase Chromosome Segregation

The master regulators of the cell cycle are cyclin-dependent kinases (Cdks), which influence the function of a myriad of proteins via phosphorylation. Mitotic Cdk1 is activated by A-type, as well as B1- and B2-type, cyclins. However, the role of a third, conserved cyclin B family member, cyclin B3, is less well defined. Here, we show that Caenorhabditis elegans CYB-3 has essential and distinct functions from cyclin B1 and B2 in the early embryo. CYB-3 is required for the timely execution of a number of cell cycle events including completion of the MII meiotic division of the oocyte nucleus, pronuclear migration, centrosome maturation, mitotic chromosome condensation and congression, and, most strikingly, progression through the metaphase-to-anaphase transition. Our experiments reveal that the extended metaphase delay in CYB-3–depleted embryos is dependent on an intact spindle assembly checkpoint (SAC) and results in salient defects in the architecture of holocentric metaphase chromosomes. Furthermore, genetically increasing or decreasing dynein activity results in the respective suppression or enhancement of CYB-3–dependent defects in cell cycle progression. Altogether, these data reveal that CYB-3 plays a unique, essential role in the cell cycle including promoting mitotic dynein functionality and alleviation of a SAC–dependent block in anaphase chromosome segregation

Unlike for Human Monocytes after LPS Activation, Release of TNF-α by THP-1 Cells Is Produced by a TACE Catalytically Different from Constitutive TACE

Tumor necrosis factor-alpha (TNF-α) is a pro-inflammatory cytokine today identified as a key mediator of several chronic inflammatory diseases. TNF-α, initially synthesized as a membrane-anchored precursor (pro-TNF-α), is processed by proteolytic cleavage to generate the secreted mature form. TNF-α converting enzyme (TACE) is currently the first and single protease described as responsible for the inducible release of soluble TNF-α.Here, we demonstrated the presence on THP-1 cells as on human monocytes of a constitutive proteolytical activity able to cleave pro-TNF-α. Revelation of the cell surface TACE protein expression confirmed that the observed catalytic activity is due to TACE. However, further studies using effective and innovative TNF-α inhibitors, as well as a highly selective TACE inhibitor, support the presence of a catalytically different sheddase activity on LPS activated THP-1 cells. It appears that this catalytically different TACE protease activity might have a significant contribution to TNF-α release in LPS activated THP-1 cells, by contrast to human monocytes where the TACE activity remains catalytically unchanged even after LPS activation.On the surface of LPS activated THP-1 cells we identified a releasing TNF-α activity, catalytically different from the sheddase activity observed on human monocytes from healthy donors. This catalytically-modified TACE activity is different from the constitutive shedding activity and appears only upon stimulation by LPS