Site fidelity of Atlantic cod Gadus morhua L. as deduced from telemetry and stable isotope studies

A study was performed to test the hypothesis that Atlantic cod Gadus morhua captured within fjords do not migrate across the sill into outer fjord segments or coastal waters. An 18 month long telemetry experiment, corroborated by recapture patterns, showed that 40% of the tagged fish crossed the sill. The majority of the fish that crossed the sill, however, returned after short excursions of only a few days. Many fish remained stationary at or near the release location, and migrations up the fjord into brackish water appeared more frequent than migration out of the fjord. The stable isotope analyses showed significant differences between the inner and the outer fjord segments, and this was seen for both adults and juveniles. This suggests that the Atlantic cod in the two areas have different diets and probably utilize different foraging ranges. Thus, both the isotope studies and the telemetry experiment suggest limited cross-sill migration and rather high site fidelity. Marketing restrictions only apply to fish caught in the fjord proper, not the comparatively clean outer fjord system beyond the sill. Based on this study of migratory tendencies, it is concluded that contamination levels in Atlantic cod in both the Frierfjord proper and the outer fjords probably result from local exposure and appear little affected by inter-fjord migration.     

Isolation and characterisation of 11 microsatellite loci in the abyssal carapine grenadier Coryphaenoides carapinus (Actinoperygii, Macrouridae) and cross-amplification in two other deep-sea macrourid species

Microsatellites represent an important tool for characterising population structure, for attributing individuals to stocks, and for revealing ecological processes taking place on population and meta-population levels. A sound knowledge of population structure is essential for sustainable management of exploited fish stocks, and helps to understand population connectivity and speciation. We developed for the first time primers for microsatellite loci in the carapine grenadier, Coryphaenoides carapinus, inhabiting the abyssal Atlantic. Eleven microsatellites were obtained from partial genomic DNA libraries enriched for tetranucleotide repeats. The loci were characterised in three unrelated individuals and nine loci were found to be polymorphic. Cross-amplification in two commercially exploited deep-sea macrourid species (Coryphaenoides rupestris and Macrourus berglax) resolved two polymorphic loci in each species.     

Genome architecture enables local adaptation of Atlantic cod despite high connectivity

Adaptation to local conditions is a fundamental process in evolution; however, mechanisms maintaining local adaptation despite high gene flow are still poorly understood. Marine ecosystems provide a wide array of diverse habitats that frequently promote ecological adaptation even in species characterized by strong levels of gene flow. As one example, populations of the marine fish Atlantic cod (Gadus morhua) are highly connected due to immense dispersal capabilities but nevertheless show local adaptation in several key traits. By combining population genomic analyses based on 12K single nucleotide polymorphisms with larval dispersal patterns inferred using a biophysical ocean model, we show that Atlantic cod individuals residing in sheltered estuarine habitats of Scandinavian fjords mainly belong to offshore oceanic populations with considerable connectivity between these diverse ecosystems. Nevertheless, we also find evidence for discrete fjord populations that are genetically differentiated from offshore populations, indicative of local adaptation, the degree of which appears to be influenced by connectivity. Analyses of the genomic architecture reveal a significant overrepresentation of a large ~5 Mb chromosomal rearrangement in fjord cod, previously proposed to comprise genes critical for the survival at low salinities. This suggests that despite considerable connectivity with offshore populations, local adaptation to fjord environments may be enabled by suppression of recombination in the rearranged region. Our study provides new insights into the potential of local adaptation in high gene flow species within fine geographical scales and highlights the importance of genome architecture in analyses of ecological adaptation.     

Exploring the species diversity of Trichoderma in Norwegian drinking water systems by DNA barcoding

A total of 123 Trichoderma strains were isolated from Norwegian surface-sourced drinking water. The water samples included raw water, treated water, and water from private homes and hospital installations. Trichoderma species are difficult to differentiate morphologically, but recent molecular identification tools, including DNA barcoding, successfully distinguish between closely related species. The diversity of Trichoderma spp. was explored by DNA sequencing of internal transcribed spacer (ITS) and translation elongation factor 1 alpha (TEF-1α). Sequence identification was performed in the TrichOKEY version 2.0 barcode program and in the multilocus similarity search database TrichoBLAST, combined with traditional blast searches in the EMBL/GenBank. A total of 11 known Trichoderma/Hypocrea species were identified. In addition, one group of unidentified Trichoderma strains was found to represent a separate, strongly supported subclade within the Pachybasium'A'/Hamatum clade, based on their TEF-1α haplotypes. Trichoderma viride comprised 49% of the identified strains, and was represented by four and eight slightly different ITS and TEF-1α haplotypes, respectively. Approximately 22% of the surface-derived water samples were positive for T. viride, and the species was frequently isolated throughout the surface-sourced drinking water distribution system. The results indicate that a broad range of Trichoderma species are present in Norwegian surface-sourced drinking. Water treatment has minor effect in removing Trichoderma from raw water, and active growth in the water distribution system is likely to occur.     

Vibrissal kinematics in 3D: tight coupling of azimuth, elevation, and torsion across different whisking modes

Perception is usually an active process by which action selects and affects sensory information. During rodent active touch, whisker kinematics influences how objects activate sensory receptors. In order to fully characterize whisker motion, we reconstructed whisker position in 3D and decomposed whisker motion to all its degrees of freedom. We found that, across behavioral modes, in both head-fixed and freely moving rats, whisker motion is characterized by translational movements and three rotary components: azimuth, elevation, and torsion. Whisker torsion, which has not previously been described, was large (up to 100 degrees), and torsional angles were highly correlated with whisker azimuths. The coupling of azimuth and torsion was consistent across whisking epochs and rats and was similar along rows but systematically varied across rows such that rows A and E counterrotated. Torsional rotation of the whiskers enables contact information to be mapped onto the circumference of the whisker follicles in a predictable manner across protraction-retraction cycles.     

Antagonists of the human adenosine A2A receptor. Part 1: Discovery and synthesis of thieno[3,2-d]pyrimidine-4-methanone derivatives

The (−)-(11R,2′S)-enantiomer of the antimalarial drug mefloquine has been found to be a reasonably potent and moderately selective adenosine A_2A receptor antagonist. Further investigation of this compound has led to the discovery of a series of keto-aryl thieno[3,2-d]pyrimidine derivatives, which are potent and selective antagonists of the adenosine A_2A receptor. These derivatives show selectivity against the A₁ receptor. Furthermore, some of these compounds have been shown to have in vivo activity in a commonly used model, suggesting the potential for the treatment of Parkinson’s disease.     

A rapid method for the separation and analysis of carrageenan oligosaccharides released by iota- and kappa -carrageenase

Based on the improved performances in speed of chromatographic separation on Superdex-type materials (Pharmacia) compared to conventional media such as Sephadex and Bio Gel-type, a rapid size-exclusion chromatography (SEC) method was developed for the separation and analysis of carrageenan oligosaccharides. It was used to evaluate the elution profiles of hydrolysates produced by carrageenases specific for kappa- and iota-carrageenans. Oligosaccharide peaks ranging from di- to dodeca-saccharides were obtained in about 20 min on an analytical scale, whereas preparative runs were completed in a few hours. The method may also be used to monitor polysaccharide degradation.     

SYNCHRONOUS GROWTH OF CHLAMYDOMONAS REINHARDTII (CHLOROPHYCEAE): A REVIEW OF OPTIMAL CONDITIONS1

Chlamydomonas reinhardtii Dangeard was synchronized at optimal growth conditions under a 12:4 LD regime at 35 C and 20,000 lx with serial dilution to a standard starting cell density of (1.4 ± 0.2) × 10⁶ cells/ml. Synchronous growth and division were characterized by measuring cell number, cell volume and size distribution, dry weight, protein, carbon, nitrogen, chlorophyll, carotenoids, nucleic acids, nuclear and cytoplasmic division during the vegetative life cycle. The main properties of the present system are: Exponential growth with high productivity, high degrees of synchrony and reproducibility during repeated life cycles. The degree of synchrony of this light-dark synchronization system was evaluated and compared with those described in the literature using probit analysis of the time course of DNA synthesis, nuclear and cytoplasmic division and sporulation (increase in cell number). The results showed that the degree of synchrony is highest for cells grown under optimal conditions.     

The Pillars of Hercules as a bathymetric barrier to gene flow promoting isolation in a global deep‐sea shark (Centroscymnus coelolepis)

Knowledge of the mechanisms limiting connectivity and gene flow in deep‐sea ecosystems is scarce, especially for deep‐sea sharks. The Portuguese dogfish (Centroscymnus coelolepis) is a globally distributed and near threatened deep‐sea shark. C. coelolepis population structure was studied using 11 nuclear microsatellite markers and a 497‐bp fragment from the mtDNA control region. High levels of genetic homogeneity across the Atlantic (Φ_ST = ?0.0091, F_ST = 0.0024, P > 0.05) were found suggesting one large population unit at this basin. The low levels of genetic divergence between Atlantic and Australia (Φ_ST = 0.0744, P < 0.01; F_ST = 0.0015, P > 0.05) further suggested that this species may be able to maintain some degree of genetic connectivity even across ocean basins. In contrast, sharks from the Mediterranean Sea exhibited marked genetic differentiation from all other localities studied (Φ_ST = 0.3808, F_ST = 0.1149, P < 0.001). This finding suggests that the shallow depth of the Strait of Gibraltar acts as a barrier to dispersal and that isolation and genetic drift may have had an important role shaping the Mediterranean shark population over time. Analyses of life history traits allowed the direct comparison among regions providing a complete characterization of this shark's populations. Sharks from the Mediterranean had markedly smaller adult body size and size at maturity compared to Atlantic and Pacific individuals. Together, these results suggest the existence of an isolated and unique population of C. coelolepis inhabiting the Mediterranean that most likely became separated from the Atlantic in the late Pleistocene.     

Elastin-insufficient mice show normal cardiovascular remodeling in 2K1C hypertension despite higher baseline pressure and unique cardiovascular architecture

Mice heterozygous for the elastin gene (ELN(+/-)) show unique cardiovascular properties, including increased blood pressure and smaller, thinner arteries with an increased number of lamellar units. Some of these properties are also observed in humans with supravalvular aortic stenosis, a disease caused by functional heterozygosity of the elastin gene. The arterial geometry in ELN(+/-) mice is contrary to the increased thickness that would be expected in an animal demonstrating hypertensive remodeling. To determine whether this is due to a decreased capability for cardiovascular remodeling or to a novel adaptation of the ELN(+/-) cardiovascular system, we increased blood pressure in adult ELN(+/+) and ELN(+/-) mice using the two-kidney, one-clip Goldblatt model of hypertension. Successfully clipped mice have a systolic pressure increase of at least 15 mmHg over sham-operated animals. ELN(+/+) and ELN(+/-)-clipped mice show significant increases over sham-operated mice in cardiac weight, arterial thickness, and arterial cross-sectional area with no changes in lamellar number. There are no significant differences in most mechanical properties with clipping in either genotype. These results indicate that ELN(+/+) and ELN(+/-) hearts and arteries remodel similarly in response to adult induced hypertension. Therefore, the cardiovascular properties of ELN(+/-) mice are likely due to developmental remodeling in response to altered hemodynamics and reduced elastin levels.