Real-time ichthyoplankton drift in Northeast Arctic cod and Norwegian spring-spawning herring

Background

Individual-based biophysical larval models, initialized and parameterized by observations, enable numerical investigations of various factors regulating survival of young fish until they recruit into the adult population. Exponentially decreasing numbers in Northeast Arctic cod and Norwegian Spring Spawning herring early changes emphasizes the importance of early life history, when ichthyoplankton exhibit pelagic free drift. However, while most studies are concerned with past recruitment variability it is also important to establish real-time predictions of ichthyoplankton distributions due to the increasing human activity in fish habitats and the need for distribution predictions that could potentially improve field coverage of ichthyoplankton.

Methodology/Principal Findings

A system has been developed for operational simulation of ichthyoplankton distributions. We have coupled a two-day ocean forecasts from the Norwegian Meteorological Institute with an individual-based ichthyoplankton model for Northeast Arctic cod and Norwegian Spring Spawning herring producing daily updated maps of ichthyoplankton distributions. Recent years observed spawning distribution and intensity have been used as input to the model system. The system has been running in an operational mode since 2008. Surveys are expensive and distributions of early stages are therefore only covered once or twice a year. Comparison between model and observations are therefore limited in time. However, the observed and simulated distributions of juvenile fish tend to agree well during early fall. Area-overlap between modeled and observed juveniles September 1^st range from 61 to 73%, and 61 to 71% when weighted by concentrations.

Conclusions/Significance

The model system may be used to evaluate the design of ongoing surveys, to quantify the overlap with harmful substances in the ocean after accidental spills, as well as management planning of particular risky operations at sea. The modeled distributions are already utilized during research surveys to estimate coverage success of sampled biota and immediately after spills from ships at sea.     

Accelerated antigen sampling and transport by airway mucosal dendritic cells following inhalation of a bacterial stimulus

An increase in the tempo of local dendritic cell (DC)-mediated immune surveillance is a recognized feature of the response to acute inflammation at airway mucosal surfaces, and transient up-regulation of the APC functions of these DC preceding their emigration to regional lymph nodes has recently been identified as an important trigger for T cell-mediated airway tissue damage in diseases such as asthma. In this study, using a rat model, we demonstrate that the kinetics of the airway mucosal DC (AMDC) response to challenge with heat-killed bacteria is considerably more rapid and as a consequence more effectively compartmentalized than that in recall responses to soluble Ag. Notably, Ag-bearing AMDC expressing full APC activity reach regional lymph nodes within 30 min of cessation of microbial exposure, and in contrast to recall responses to nonpathogenic Ags, there is no evidence of local expression of APC activity within the airway mucosa preceding DC emigration. We additionally demonstrate that, analogous to that reported in the gut, a subset of airway intraepithelial DC extend their processes into the airway lumen. This function is constitutively expressed within the AMDC population, providing a mechanism for continuous immune surveillance of the airway luminal surface in the absence of "danger" signals.     

Thymidine secretion by hybridoma and myeloma cells

Secretion of thymidine appeared to be a common property of hybridoma and myeloma cells, but not of other cell types, which were tested. Of three hybridoma cell lines tested, all secreted thymidine in amounts resulting in the accumulation of thymidine to concentrations of 10-20microM in the culture medium. Also three of five myeloma cell lines that were analyzed secrete thymidine, but none of the other cell types that were studied. Thymidine was purified to homogeneity (4mg purified from 3l of culture medium) and identified as such by nuclear magnetic resonance spectroscopy. The cells that secreted thymidine showed high resistance to the growth inhibitory effect of thymidine.     

Subunit-specific modulation of [(3)H]MK-801 binding to NMDA receptors mediated by dopamine receptor ligands in rodent brain

Dopamine D1 receptor (D1R) ligands may directly interact with the NMDA receptor (NMDAR), but detailed knowledge about this effect is lacking. Here we identify D1R ligands that directly modulate NMDARs and examine the contributions of NR2A and NR2B subunits to these interactions. Binding of the open channel blocker [(3)H]MK-801 in membrane preparations from rat- and mouse brain was used as a biochemical measure of the functional state of the NMDAR channel. We show that both D1R agonist A-68930 and dopamine receptor D2 antagonist haloperidol can decrease [(3)H]MK-801 binding with increased potency in membranes from the NR2A(-/-) mice (i.e. in membranes containing NR2B only), as compared to the inhibition obtained in wild-type membranes. Further, a wide range of D1R agonists such as A-68930, SKF-83959, SKF-83822, SKF-38393 and dihydrexidine were able to decrease [(3)H]MK-801 binding, all showing half maximal inhibitory concentrations ~20 μM, and with significant effects occurring at or above 1 μM. With membranes from D1R(-/-) mice, we demonstrate that these effects occurred through a D1R-independent mechanism. Our results demonstrate that dopamine receptor ligands can selectively influence NR2B containing NMDARs, and we characterize direct inhibitory NMDAR effects by different D1R ligands.     

Sex allocation in relation to host races in the brood-parasitic common cuckoo (Cuculus canorus)

Sex allocation theory and empirical evidence both suggest that natural selection should favour maternal control of offspring sex ratio in relation to their ability to invest in the offspring. Generalist parasites constitute a particularly interesting group to test this theory as different females commonly utilize different host species showing large variation in provisioning ability. The common cuckoo (Cuculus canorus) is a generalist brood parasite that lays its eggs in the nest of many different passerine birds, but each female tends to specialize on one particular host species giving rise to highly specialized host races. The different host species show large variation in their ability to invest in the parasitic offspring, presenting an opportunity for female cuckoos to bias offspring sex ratio in relation to host species quality. Here, we investigate host-race specific sex allocation controlling for maternal identity in the common cuckoo. We found no evidence of any significant relationship between host race and sex ratio in one sympatric population harbouring three different host races, or in a total of five geographically separated populations. There was also no significant association between host quality, as determined by species-specific female host body mass, and cuckoo sex ratio. Finally, we found no significant relationship between individual cuckoo maternal quality, as determined by her egg volume, and sex ratio within each host race. We conclude that the generalist brood-parasitic common cuckoo show no significant sex-ratio bias in relation to host race and discuss this finding in light of gene flow and host adaptations.     

FE65 as a link between VLDLR and APP to regulate their trafficking and processing

Background

Loss-of-function mutations in PTEN-induced kinase 1 (PINK1) have been linked to familial Parkinson??s disease, but the underlying pathogenic mechanism remains unclear. We previously reported that loss of PINK1 impairs mitochondrial respiratory activity in mouse brains.

Results

In this study, we investigate how loss of PINK1 impairs mitochondrial respiration using cultured primary fibroblasts and neurons. We found that intact mitochondria in PINK1?/? cells recapitulate the respiratory defect in isolated mitochondria from PINK1?/? mouse brains, suggesting that these PINK1?/? cells are a valid experimental system to study the underlying mechanisms. Enzymatic activities of the electron transport system complexes are normal in PINK1?/? cells, but mitochondrial transmembrane potential is reduced. Interestingly, the opening of the mitochondrial permeability transition pore (mPTP) is increased in PINK1?/? cells, and this genotypic difference between PINK1?/? and control cells is eliminated by agonists or inhibitors of the mPTP. Furthermore, inhibition of mPTP opening rescues the defects in transmembrane potential and respiration in PINK1?/? cells. Consistent with our earlier findings in mouse brains, mitochondrial morphology is similar between PINK1?/? and wild-type cells, indicating that the observed mitochondrial functional defects are not due to morphological changes. Following FCCP treatment, calcium increases in the cytosol are higher in PINK1?/? compared to wild-type cells, suggesting that intra-mitochondrial calcium concentration is higher in the absence of PINK1.

Conclusions

Our findings show that loss of PINK1 causes selective increases in mPTP opening and mitochondrial calcium, and that the excessive mPTP opening may underlie the mitochondrial functional defects observed in PINK1?/? cells.     

A study of candidate genes for day blindness in the standard wire haired dachshund

Background

A genetic study was performed to identify candidate genes associated with day blindness in the standard wire haired dachshund. Based on a literature review of diseases in dogs and human with phenotypes similar to day blindness, ten genes were selected and evaluated as potential candidate genes associated with day blindness in the breed.

Results

Three of the genes, CNGB3, CNGA3 and GNAT2, involved in cone degeneration and seven genes and loci, ABCA4, RDH5, CORD8, CORD9, RPGRIP1, GUCY2D and CRX, reported to be involved in cone-rod dystrophies were studied. Polymorphic markers at each of the candidate loci were studied in a family with 36 informative offspring. The study revealed a high frequency of recombinations between the candidate marker alleles and the disease.

Conclusion

Since all of the markers were at the exact position of the candidate loci, and several recombinations were detected for each of the loci, all ten genes were excluded as causal for this canine, early onset cone-rod dystrophy. The described markers may, however, be useful to screen other canine resource families segregating eye diseases for association to the ten genes.

     

Correlation of the content of hepatotoxin nodularin and glycosidic carotenoids, 4-ketomyxol-2′-fucoside and novel 1′-O-methyl-4-ketomyxol-2′-fucoside,in 20 strains of the cyanobacterium Nodularia spumigena

The carotenoids of 19 different strains of Nodularia spumigena and one Nodularia sphaerocarpa from different global locations were investigated. The molecular structure of the diagnostic pigment in N. spumigena of the Baltic Sea, tentatively named ‘4-keto-myxoxanthophyll-like pigment’ in Schlüter, L., Garde, K., Kaas, H., [2004. A 4-keto-myxoxanthophyll-like pigment is a diagnostic pigment for the toxic cyanobacteria Nodularia spumigena in the Baltic Sea. Mar. Ecol. Prog. Ser. 275, 69–78.] was determined to be a 4-ketomyxol-2′-fucoside. In most of the strains an additional carotenoid was found, identified as the novel 1′-O-methyl-4-ketomyxol-2′-fucoside by 2D NMR. This glycosidic carotenoid methyl ether was found to be a more important diagnostic pigment than the 4-ketomyxol-2′-fucoside for the toxic N. spumigena in the Baltic Sea. Out of the 20 strains 15 were found to produce the hepatotoxin nodularin. The content of carotenoids and nodularin was found to increase relative to chlorophyll a at increasing light intensity and at stationary growth, and nodularin was significantly correlated to both 4-ketomyxol-2′-fucoside and 1′-O-methyl-4-ketomyxol-2′-fucoside, and particular to the sum of these two pigments.     

Evidence for numerous analogs of yessotoxin in Protoceratium reticulatum

A solid-phase extract from Protoceratium reticulatum was partitioned between water and butanol and the two fractions purified on an alumina column. Fractionation was monitored by ELISA and LC–MS. Results indicate that while almost all yessotoxin (1) was extracted into butanol, large amounts of yessotoxin analogs remained in the aqueous extract along with lesser amounts in the butanolic extract. NMR analysis of selected fractions from reverse-phase chromatography of the extracts confirmed the presence of yessotoxin analogs, although structure determinations were not possible due to the complexity of the mixtures. Analysis of fractions with LC–MS³ and neutral-loss LC–MS/MS indicated the presence of more than 90 yessotoxin analogs, although structures for most of these have not yet been determined. These analogs provide a mechanism to rationalise the discrepancy between ELISA and LC–MS analyses of algae and shellfish.