A test of the hypothesis of pheromone attraction in salmonid migration

Synopsis We tested the hypothesis that anadromous salmonids are guided on their homeward migration by population-specific pheromones. Our findings do not support the hypothesis. Wild migrant Arctic charr,Salvelinus alpinus, from Ikarut River, Labrador were transferred and held in a tributary previously uninhabited by anadromous fish. None of the charr migrating up Ikarut River entered the tributary after fish were transferred. Similarly, migrant charr, which were caught in Ikarut River and released in the tributary below the captive fish, did not remain in the tributary. We re-evaluated the data which have been used to uphold the concept of pheromone attraction in salmonid migration and concluded that support for the hypothesis is unsubstantiated.     

Spatial and temporal distributions of salmonids in two ponds in Newfoundland, Canada

Spatial and temporal distributions of salmonids were examined in Junction Pond, Northeast River, Placentia and Conne Pond, Conne River, Newfoundland using Lundgren multiple-mesh experimental gillnets. Both ponds contain populations of Atlantic salmon and brook trout with Junction Pond also possessing brown trout and resident Arctic charr. For salmon parr there was a significant month effect in distribution of catch rates in both ponds, and in Junction Pond, there was a significant diel effect. There was also significant variation in catch rates by lentic zone. For brook trout, there was a significant lentic zone × month interaction in Junction Pond; in Conne Pond, the main effects lentic zone and month were significant. Highest benthic catch rates of Atlantic salmon parr occurred in the littoral zone of both ponds. Most captures of brook trout also occurred benthically in both ponds; similar to salmon parr, littoral zone catch rates were higher than those of the deeper benthic area in Conne Pond but the reverse was true for Junction Pond. For both salmon parr and brook trout, the deeper benthic area and the pelagic area were relatively important rearing habitats in each pond. The distribution of catches for brown trout (few in number relative to the other species) in Junction Pond was similar to that of brook trout while Arctic charr were found mainly pelagically. Within the benthic area, most Arctic charr were caught at depths beyond the littoral zone. There was a tendency for Altantic salmon parr and brook trout found in the deeper benthic area and the pelagic area to be significantly larger and older than those in littoral zone in each pond. Sizes of Arctic charr did not differ significantly among lentic zones.     

Salinity tolerance of freshwater acclimated, small-sized Arctic charr, Salvelinus alpinus from northern Labrador

Arctic charr, Salvelinus alpinus , less than 150 mm in size were frequently captured at sea in northern Labrador in areas where salinities of 30‰ or higher had been recorded. These captures were inconsistent with many earlier reports for other areas that indicated Arctic charr less than 150 mm in size were not found at sea. A series of salinity challenge tests was carried out in the field, using wild Ikarut River charr, and in the laboratory, using cultured Fraser River charr, to understand more about the potential fate of these small fish. The results of challenge tests with small Arctic charr (< 120 mm) indicated that at intermediate salinities (10–20‰), these fish can readily survive. In laboratory tests with salinities at 30‰, survival was size dependent and would suggest that in natural situations, small charr would require periodic access to fresh or brackish water to stay alive. The influence of water temperature on salinity tolerance may be important when fish are exposed to temperatures that are below 0° C.     

Diel activity patterns in overwintering Labrador anadromous Arctic charr

Hydrobiologia - Anadromous Arctic charr, Salvelinus alpinus, migrate back to freshwater in late summer to spawn and/or overwinter. While seasonal movement patterns during the freshwater residency...     

Thermal habitat use and growth in young-of-the-year Arctic charr from proximal fluvial and lacustrine populations in Labrador,Canada

Predicted increases in temperature associated with climate change are expected to have consequences for fish, in particular for Arctic charr, Salvelinus alpinus, a cold-adapted fish species. Despite differences in predicted hydroecological responses to climate change in fluvial and lacustrine environments, little is known of whether fluvial and lacustrine Arctic charr populations may respond differently to increasing temperatures. In order to compare growth and thermal habitat use between habitat types, otolith-inferred average water temperatures estimated from whole otoliths and fork lengths at capture were measured for young-of-the-year (YOY) Arctic charr obtained from two proximal fluvial and lacustrine sites in Labrador, Canada. Otolith-inferred average experienced water temperatures were not significantly correlated with air temperatures at both sites, suggestive of behavioural thermoregulation by YOY. The majority of Kogluktokoluk Brook (fluvial) YOY were found using water temperatures consistent with laboratory determined preferred temperatures for juvenile Arctic charr, whereas most Tom's Pond (lacustrine) YOY were found using temperatures ranging between preferred temperatures and optimal temperatures for growth. There was no consistent difference between mean water temperatures used between YOY from the two sites. Otolith-inferred average experienced water temperatures were only correlated to fork lengths in Tom's Pond YOY. The lack of correlation in Kogluktokoluk Brook YOY is argued to reflect resource partitioning occurring as a result of territoriality known to occur among stream salmonids. The limited range of temperatures used by fluvial YOY in this study, particularly the lack of cooler temperatures, also suggests that fluvial YOY may face barriers to thermal refugia, and as a result may be particularly vulnerable to climate change.     

Patterns of population genetic variation in sympatric chiltoniid amphipods within a calcrete aquifer reveal a dynamic subterranean environment

Calcrete aquifers from the Yilgarn region of arid central Western Australia contain an assemblage of obligate groundwater invertebrate species that are each endemic to single aquifers. Fine-scale phylogeographic and population genetic analyses of three sympatric and independently derived species of amphipod (Chiltoniidae) were carried out to determine whether there were common patterns of population genetic structure or evidence for past geographic isolation of populations within a single calcrete aquifer. Genetic diversity in amphipod mitochondrial DNA (cytochrome c oxidase subunit I gene) and allozymes were examined across a 3.5 km² region of the Sturt Meadows calcrete, which contains a grid of 115 bore holes (=wells). Stygobiont amphipods were found to have high levels of mitochondrial haplotype diversity coupled with low nucleotide diversity. Mitochondrial phylogeographic structuring was found between haplogroups for one of the chiltoniid species, which also showed population structuring for nuclear markers. Signatures of population expansion in two of the three species, match previous findings for diving beetles at the same site, indicating that the system is dynamic. We propose isolation of populations in refugia within the calcrete, followed by expansion events, as the most likely source of intraspecific genetic diversity, due to changes in water level influencing gene flow across the calcrete.     

Beverage specific alcohol intake in a population-based study: Evidence for a positive association between pulmonary function and wine intake

Background  

Lung function is a strong predictor of cardiovascular and all-cause mortality. Previous studies suggest that alcohol exposure may be linked to impaired pulmonary function through oxidant-antioxidant mechanisms. Alcohol may be an important source of oxidants; however, wine contains several antioxidants. In this study we analyzed the relation of beverage specific alcohol intake with forced expiratory volume in one second (FEV₁) and forced vital capacity (FVC) in a random sample of 1555 residents of Western New York, USA.     

DNA integrity and transgene expression after passage through the NOGA needle catheter used for therapeutic myocardial angiogenesis

BACKGROUND: The NOGA (Biosense Webster, Markham, ON, Canada) injection catheter is an innovative navigational device that provides an ideal platform for intra-myocardial injection material. However, injection through a long (1.91 m), narrow (27G) nitinol needle could result in deterioration in the integrity and functionality of DNA. METHODS: To test this possibility, DNA in plasmid form (pcDNA3.1) containing the Lac Z transgene (250 micro l) was passed through the NOGA needle using a hand-held 1 cc syringe at a gentle hand injection pressure (43 +/- 3 PSI, 3.0 +/- 0.2 kg/cm(2)) or at maximal manual pressure (90 +/- 6 PSI, 6.3 +/- 0.4 kg/cm(2)), either once or 20 times. This DNA, compared to DNA not passed through the NOGA needle (control), was then used to transfect primary cultures of rat skin fibroblasts (FB) from Fisher 344 rats and the cells were subsequently stained for beta galactosidase (betagal). RESULTS: Transfection efficiency was significantly reduced by passing the DNA through the needle at both 43 +/- 3 PSI (78 +/- 4% of control, n = 10, P < 0.05 versus control) and 90 +/- 6 PSI (66 +/- 4 % of control, n = 10, P < 0.01 versus control, P < 0.02 versus 43 +/- 3 PSI). Passage of the DNA through the NOGA needle 20 times resulted in a transfection efficiency of only 5 +/- 1% of control (n = 20, P < 0.1 x 10(-11) versus control). Capillary Electrophoresis revealed that the reduction in transfection efficiency was due to a conformational change in the DNA from predominantly supercoiled to nicked and linearized DNA. Transfection efficiency as compared with control decreased as the concentration of the DNA solution which was passed through the needle was increased from 0.3 micro g/ micro l to 2.4 micro g/ micro l. Recovery experiments confirmed that the reduction in transfection efficiency was not due to loss of DNA by binding to the NOGA needle. CONCLUSION: These results suggest that DNA is susceptible to shear forces when injected through the NOGA needle even at nominal clinical injection pressures, suggesting that careful and controlled injections will be required to achieve optimal gene integrity and expression.     

Molecular evolution of P transposable elements in the genus Drosophila. III. The melanogaster species group

Phylogenetic relationships were determined for 76 partial P-element sequences from 14 species of the melanogaster species group within the Drosophila subgenus Sophophora. These results are examined in the context of the phylogeny of the species from which the sequences were isolated. Sequences from the P-element family fall into distinct subfamilies, or clades, which are often characteristic for particular species subgroups. When examined locally among closely related species, the evolution of P elements is characterized by vertical transmission, whereby the P-element phylogeny traces the species phylogeny. On a broader scale, however, the P-element phylogeny is not congruent with the species phylogeny. One feature of P-element evolution in the melanogaster group is the presence of more than one P-element subfamily, differing by as much as 36%, in the genomes of some species. Thus, P elements from several individual species are not monophyletic, and a likely explanation for the incongruence between P-element and species phylogenies is provided by the comparison of paralogous sequences. In certain instances, horizontal transfer seems to be a valid alternative explanation for lack of congruence between species and P-element phylogenies. The canonical P-element subfamily, which represents the active, autonomous transposable element, is restricted to D. melanogaster. Thus, its origin clearly lies outside of the melanogaster species group, consistent with the earlier conclusion of recent horizontal transfer.      

Structural organization of the beta-globin locus of B-haplotype sheep

Goats and some sheep synthesize a juvenile hemoglobin, Hb C (alpha 2 beta C2), at birth and produce this hemoglobin exclusively during severe anemia. Sheep that synthesize this juvenile hemoglobin are of the A haplotype. Other sheep, belonging to a separate group, the B haplotype, do not synthesize hemoglobin C and during anemia continue to produce their adult hemoglobin. To understand the basis for this difference we have determined the structural organization of the beta- globin locus of B-type sheep by constructing and isolating overlapping genomic clones. These clones have allowed us to establish the linkage map 5' epsilon I-epsilon II-psi beta I-beta B-epsilon III-epsilon IV- psi beta II-beta F3' in this haplotype. Thus, B sheep lack four genes, including the BC gene, and have only eight genes, compared with the 12 found in the goat globin locus. The goat beta-globin locus is as follows: 5' epsilon I-epsilon II-psi beta X-beta C-epsilon III-epsilon IV-psi beta Z-beta A-epsilon V-epsilon VI-psi beta Y-beta F3'. Southern blot analysis of A-type sheep reveals that these animals have a beta- globin locus similar to that of goat, i.e., 12 globin genes. Thus, the beta-globin locus of B-haplotype sheep resembles that of cows and may have retained the duplicated locus of the ancestor of cows and sheep. Alternatively, the B-sheep locus arrangement may be the result of a deletion of a four-gene set from the triplicated locus.