Lantern fish (Benthosema pterotum) resources as a target for commercial exploitation in the Oman Sea

The skinnycheek lantern fish Benthosema pterotum (Myctophidae) represents a virgin resource in the Oman Sea. Because of its potential importance for fishmeal production there has been great interest during the last decade in starting commercial exploitation. Acoustic surveys to estimate stock biomass and trial fishing using pelagic trawls were carried out in Iranian waters of the Oman Sea from 1992 to 1998. Lantern fish schools are found in offshore waters, on the edge of the continental shelf wherever sea depth is more than 100 m. During the day the fish occur in two vertical layers, with the densest schools in the shallower layer (80–130 m), whereas at night B. pterotum occur in a single dispersed layer closer to the surface (mainly at 30–70 m). Biomass estimates range from 1 to 4 million tonnes (t), with an average of 2.3 million t. Densities vary seasonally, with the highest densities recorded in spring (May–June) and lowest in autumn (October–November). The highest densities were seen in the western Oman Sea. Although recommendations can be made with regard to the best fishing seasons, areas and depths, trial catch rates were too low (<30 t daily per boat) to support a commercially viable fishery. Further trials are needed to identify the best gear and vessel size.     

Effects of hyperosmotic stress on cultured airway epithelial cells

Inhalation of hyperosmotic solutions (salt, mannitol) has been used in the treatment of patients with cystic fibrosis or asthma, but the mechanism behind the effect of hyperosmotic solutions is unclear. The relation between osmolarity and permeability changes was examined in an airway cell line by the addition of NaCl, NaBr, LiCl, mannitol, or xylitol (295–700 mOsm). Transepithelial resistance was measured as an indicator of the tightness of the cultures. Cell-cell contacts and morphology were investigated by immunofluorescence and by transmission electron microscopy, with lanthanum nitrate added to the luminal side of the epithelium to investigate tight junction permeability. The electrolyte solutions caused a significant decrease in transepithelial resistance from 450 mOsm upwards, when the hyperosmolar exposure was gradually increased from 295 to 700 mOsm; whereas the nonelectrolyte solutions caused a decrease in transepithelial resistance from 700 mOsm upwards. Old cultures reacted in a more rigid way compared to young cultures. Immuno-fluorescence pictures showed weaker staining for the proteins ZO-1, claudin-4, and plakoglobin in treated samples compared to the control. The ultrastructure revealed an increased number of open tight junctions as well as a disturbed morphology with increasing osmolarity, and electrolyte solutions opened a larger proportion of tight junctions than nonelectrolyte solutions. This study shows that hyperosmotic solutions cause the opening of tight junctions, which may increase the permeability of the paracellular pathway and result in increased transepithelial water transport. This study was supported by the Swedish Asthma and Allergy Association and the Swedish Heart Lung Foundation.     

<Emphasis Type="Italic">Burkholderia</Emphasis> Hep_Hag autotransporter (BuHA) proteins elicit a strong antibody response during experimental glanders but not human melioidosis

Background  

The bacterial biothreat agents Burkholderia mallei and Burkholderia pseudomallei are the cause of glanders and melioidosis, respectively. Genomic and epidemiological studies have shown that B. mallei is a recently emerged, host restricted clone of B. pseudomallei.     

Analysis of chlormequat in human urine as a biomarker of exposure using liquid chromatography triple quadrupole mass spectrometry

In this study, a method using liquid chromatography triple quadrupole mass spectrometry (LC/MS/MS) is described for the analysis of the plant growth regulator chlormequat (CCC) in human urine. Analysis was carried out using selected reaction monitoring (SRM) in the positive ion mode. [(2)H(4)] labeled CCC as internal standard (IS) was used for quantification of CCC. The limit of detection (LOD) was determined to 0.1 ng/mL. The method was linear in the range 0.3-800 ng/mL urine and had a within-run precision of 4-9%. The between-run precision was determined at urine levels of 7.0 and 31 ng/mL and found to be 5 and 6% respectively. The reproducibility was 3-6%. To validate CCC as a biomarker of exposure, the method was applied in a human experimental oral exposure to CCC. Two healthy volunteers received 25 μg/kg b.w. CCC in a single oral dose followed by urine sampling for 46 h post-exposure. The CCC was estimated to follow a first order kinetic and a two compartment model with an elimination half-life of 2-3h and 10-14 h respectively. One hundred 24h urine samples were collected from non-occupationally exposed individuals in the general population in southern Sweden. All samples had detectable levels above the LOD 0.1 ng/mL urine. The median levels were 4 ng/mL of CCC in unadjusted urine. The levels found in the population samples are several magnitudes lower than those found in the experimental exposure, which corresponds to an oral exposure of 50% of the ADI for CCC.     

Glacial history of the North Atlantic marine snail, Littorina saxatilis, inferred from distribution of mitochondrial DNA lineages

The North Atlantic intertidal gastropod, Littorina saxatilis (Olivi, 1792), exhibits extreme morphological variation between and within geographic regions and has become a model for studies of local adaptation; yet a comprehensive analysis of the species' phylogeography is lacking. Here, we examine phylogeographic patterns of the species' populations in the North Atlantic and one remote Mediterranean population using sequence variation in a fragment of the mitochondrial cytochrome b gene (607 bp). We found that, as opposed to many other rocky intertidal species, L. saxatilis has likely had a long and continuous history in the Northwest Atlantic, including survival during the last glacial maximum (LGM), possibly in two refugia. In the Northeast Atlantic, several areas likely harboured refugial populations that recolonized different parts of this region after glacial retreat, resulting in strong population structure. However, the outlying monomorphic Venetian population is likely a recent anthropogenic introduction from northern Europe and not a remnant of an earlier wider distribution in the Mediterranean Sea. Overall, our detailed phylogeography of L. saxatilis adds an important piece to the understanding of Pleistocene history in North Atlantic marine biota as well as being the first study to describe the species' evolutionary history in its natural range. The latter contribution is noteworthy because the snail has recently become an important model species for understanding evolutionary processes of speciation; thus our work provides integral information for such endeavours.     

Initial fungal colonizer affects mass loss and fungal community development in Picea abies logs 6 yr after inoculation

Picea abies logs were inoculated with Resinicium bicolor, Fomitopsis pinicola or left un-inoculated and placed in an old-growth boreal forest. Mass loss and fungal community data were collected after 6 yr to test whether simplification of the fungal community via inoculation affects mass loss and fungal community development. Three techniques were used to survey communities: (1) observation of fruiting structures; (2) culturing on media; and (3) cloning and sequencing of ITS rDNA. Fruit body surveys detected the smallest number of species (18, 3.8 per log), DNA-based methods detected the most species (72, 31.7 per log), and culturing detected an intermediate number (23, 7.2 per log). Initial colonizer affected community development and inoculation with F. pinicola led to significantly greater mass loss. Relationships among fungal community composition, community richness and mass loss are complex and further work is needed to determine whether simplification of fungal communities affects carbon sequestration in forests.     

Airway Surface Liquid Volume Regulation Determines Different Airway Phenotypes in Liddle Compared with βENaC-overexpressing Mice

Studies in cystic fibrosis patients and mice overexpressing the epithelial Na⁺ channel β-subunit (βENaC-Tg) suggest that raised airway Na⁺ transport and airway surface liquid (ASL) depletion are central to the pathogenesis of cystic fibrosis lung disease. However, patients or mice with Liddle gain-of-function βENaC mutations exhibit hypertension but no lung disease. To investigate this apparent paradox, we compared the airway phenotype (nasal versus tracheal) of Liddle with CFTR-null, βENaC-Tg, and double mutant mice. In mouse nasal epithelium, the region that functionally mimics human airways, high levels of CFTR expression inhibited Liddle epithelial Nat channel (ENaC) hyperfunction. Conversely, in mouse trachea, low levels of CFTR failed to suppress Liddle ENaC hyperfunction. Indeed, Na⁺ transport measured in Ussing chambers (“flooded” conditions) was raised in both Liddle and βENaC-Tg mice. Because enhanced Na⁺ transport did not correlate with lung disease in these mutant mice, measurements in tracheal cultures under physiologic “thin film” conditions and in vivo were performed. Regulation of ASL volume and ENaC-mediated Na⁺ absorption were intact in Liddle but defective in βENaC-Tg mice. We conclude that the capacity to regulate Na⁺ transport and ASL volume, not absolute Na⁺ transport rates in Ussing chambers, is the key physiologic function protecting airways from dehydration-induced lung disease.