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During the colonization of freshwater by marine fish, adaptation to hypoosmotic conditions may impact their ability to osmoregulate in seawater. The prickly sculpin (Cottus asper) is a euryhaline fish with marine ancestors that postglacially colonized many freshwater habitats. Previous work on C. asper suggested that isolation in freshwater habitats has resulted in putative adaptations that improve ion regulation in freshwater populations compared with populations with current access to estuaries. To determine whether long-term colonization of freshwater is associated with a reduced ability to ion regulate in seawater, we acclimated C. asper populations from three habitat types that vary in the extent to which they are isolated from marine habitats and compared their seawater osmoregulation. Seawater acclimation revealed that lake populations exhibited a reduced capacity to osmoregulate in seawater compared with coastal river populations with ongoing access to estuaries. In particular, when acclimated to seawater for several weeks, lake populations had lower gill Na+/K+-ATPase activity and lower intestinal H+-ATPase activity than coastal river populations. Lake populations also had a reduced ability to maintain plasma ion concentrations, and they produced lower quantities of intestinal carbonate precipitates in seawater than coastal river populations. Furthermore, there was a positive relationship between the anterior intestinal Na+/K+-ATPase activity and the amount of precipitate produced by the intestine, which suggests that the anterior intestine plays a role in seawater osmoregulation. Our results suggest that the extent of isolation from the sea could, in part, explain the reduced osmoregulation in seawater in postglacial freshwater populations of C. asper. [ABSTRACT FROM AUTHOR]

Methylation (me) patterns are diverse, including mono (me1)-, di (me2)-, and tri (me3)-methyla-tion, with lysines on histone 3 (H3) known to be especially important for regulating gene expression. Jumonji C domain-containing histone de-methylases (JMJs) are a major class of histone demethylases that use a-ketoglutarate as a rate-limiting substrate to remove methyl groups from histone lysines by oxidation (4-6). Methylation of histone-tail lysine (K) residues is a conserved mechanism for both activating and repressing gene expression (2, 3). [Extracted from the article]

A mixed‐stock fishery occurs when multiple populations of a fish species are exploited together in a common area where they aggregate outside the breeding season (e.g. for feeding or overwintering), and the aggregation is known as a mixture. Recreational fishing often exploits such mixtures, and estimating the proportional contributions of populations to fisheries promotes more sustainable resource use. Ten DNA microsatellites were assayed in a mixture of bull trout Salvelinus confluentus Suckley overwintering in the Nechako River, upper Fraser River, British Columbia, and in baseline population samples from 14 tributaries putatively contributing to the overwintering mixture. A DNA microsatellite‐based mixed‐stock fishery analysis suggested that five populations together contributed 0.80 to the mixture. Most of the errors associated with the mixture estimates were attributable to uncertainty in baseline allele frequencies. Radiotracking data confirmed that tributary populations contributing to the mixture estimated by genetic analysis also contained individuals that moved between spawning tributaries and overwintering sites. The results better resolve habitat use by potadromous bull trout in the upper Fraser River and, in combination with assessments of baseline population‐specific spawning abundances and productivity, will better inform a decision of whether or not allowing some harvest within the current catch‐and‐release fishery is biologically sustainable. [ABSTRACT FROM AUTHOR]

As humans cause the redistribution of species ranges, hybridization between previously allopatric species is on the rise. Such hybridization can have complex effects on overall fitness of native species as new allelic combinations are tested. Widespread species introductions provide a unique opportunity to study selection on introgressed alleles in independent, replicated populations. We examined selection on alleles that repeatedly introgressed from introduced rainbow trout (Oncorhynchus mykiss) into native westslope cutthroat trout (Oncorhynchus clarkii lewisi) populations in western Canada. We found that the degree of introgression of individual single nucleotide polymorphisms from the invasive species into the native is correlated between independent watersheds. A number of rainbow trout alleles have repeatedly swept to high frequency in native populations, suggesting parallel adaptive advantages. Using simulations, we estimated large selection coefficients up to 0.05 favoring several rainbow trout alleles in the native background. Although previous studies have found reduced hybrid fitness and genome‐wide resistance to introgression in westslope cutthroat trout, our results suggest that some introduced genomic regions are strongly favored by selection. Our study demonstrates the utility of replicated introductions as case studies for understanding parallel adaptation and the interactions between selection and introgression across the genome. We suggest that understanding this variation, including consideration of beneficial alleles, can inform management strategies for hybridizing species. [ABSTRACT FROM AUTHOR]

Heat waves, i.e., periods of extremely hot weather, are expected to increase in frequency and duration under climate change. Repeated exposure to thermal stress events such as heat waves can affect population dynamics and even population persistence. Understanding whether recent thermal history bolsters or hinders demographic responses such as survival or growth during heat waves is crucial for predicting population persistence in the face of climate change. We tested for differential mortality following an experimental heat wave in populations of the splash pool copepod, Tigriopus californicus , inhabiting pools that differ in their recent thermal history. We observed differences in survivorship that were correlated with differences in thermal history. Among multiple metrics of thermal history, daily degree-hours (a measure of heat accumulation) best explained heat wave survival such that a higher number of degree-hours resulted in reduced heat wave survival. This finding is consistent with the hypothesis that repeated exposure to sublethal temperatures reduces thermal tolerance. Increasing heat wave intensity and duration, or warmer conditions that increase heat accumulation followed by heat waves may negatively impact population persistence by exacerbating the demographic effects of heat waves. The results of this study emphasize the need to integrate mechanistic physiology within the realm of population ecology to bolster the ability to predict population-level responses to climate change. [ABSTRACT FROM AUTHOR]

The mitochondrial carrier system (MCS) transports small molecules between mitochondria and the cytoplasm. It is integral to the core mitochondrial function to regulate cellular chemistry by metabolism. The mammalian MCS comprises the transporters of the 53-member canonical SLC25A family and a lesser number of identified noncanonical transporters. The recent discovery and investigations of the mitochondrial pyruvate carrier (MPC) illustrate the diverse effects a single mitochondrial carrier may exert on cellular function. However, the transport selectivities of many carriers remain unknown, and most have not been functionally investigated in mammalian cells. The mechanisms coordinating their function as a unified system remain undefined. Increased accessibility to molecular genetic and metabolomic technologies now greatly enables investigation of the MCS. Continued investigation of the MCS may reveal how mitochondria encode complex regulatory information within chemical thermodynamic gradients. This understanding may enable precision modulation of cellular chemistry to counteract the dysmetabolism inherent in disease. [ABSTRACT FROM AUTHOR]

Metabolic reprogramming in cancer supports the increased biosynthesis required for unchecked proliferation. Increased glucose utilization is a defining feature of many cancers that is accompanied by altered pyruvate partitioning and mitochondrial metabolism. Cancer cells also require mitochondrial tricarboxylic acid cycle activity and electron transport chain function for biosynthetic competency and proliferation. Recent evidence demonstrates that mitochondrial pyruvate carrier (MPC) function is abnormal in some cancers and that increasing MPC activity may decrease cancer proliferation. Here we examine recent findings on MPC function and cancer metabolism. Special emphasis is placed on the compartmentalization of pyruvate metabolism and the alternative routes of metabolism that maintain the cellular biosynthetic pools required for unrestrained proliferation in cancer. [ABSTRACT FROM AUTHOR]

Hybridization has been documented in a many different pairs of cetacean species both in captivity and in the wild. The widespread occurrence of hybridization indicates that postmating barriers to interbreeding are incomplete within the order Cetacea, and therefore raises questions about how species integrity is maintained in the face of interspecific (and often intergeneric) gene flow. We examined hybridization across the order Cetacea (oceanic species included: N = 78; species with 44 chromosomes included: N = 52) to test for associations between the occurrence of hybridization and similarity across 13 ecological, morphological and behavioral traits in hybridizing vs. non-hybridizing species pairs. We found that species pairs that share a greater number of traits had a higher propensity to hybridize than pairs of species that did not. This trend was driven by behavioral and morphological traits such as vocalization frequency and body size. Together our findings suggest the importance of divergent selection on morphological and behavioral traits within sympatric species in constraining opportunities for hybridization and preventing the collapse of parental species. [ABSTRACT FROM AUTHOR]

The Nooksack dace (Pisces: an undescribed putative taxon within Rhinichthys) and longnose dace ( Rhinichthys cataractae) are two forms within the R. cataractae species complex that are distinguishable from one another by mitochondrial (mt) DNA divergence of 2-3%, as well as by subtle morphological differences. The two forms are found in allopatry in south-eastern British Columbia ( BC), Canada, and adjacent areas of western Washington, USA, and are sympatric in three streams in the lower Fraser River valley, BC, and may represent cryptic species. We assayed 12 morphometric traits and two meristic characters ( N = 582; 23 sampling locations) to test for diagnosability of the two dace, as well as to test for morphological differentiation by mt DNA type in sympatry. We then employed a 10-locus microsatellite DNA assay ( N = 374; 12 sampling locations) to test for genetic distinction between Nooksack dace and longnose dace in sympatry. We found that the two dace could not be reliably differentiated morphologically: there was overlap in all characters measured, and sampling location had a much larger effect on morphology than mt DNA group. Microsatellite analysis showed no distinction by mt DNA type in localities with sympatric dace, indicating complete admixture between the sympatric Nooksack dace and longnose dace. The Nooksack dace and longnose dace provide an example of 'ephemeral speciation': two lineages that, despite an estimated 1.1 Myr of isolation, have developed no apparent barriers to reproduction and appear to have collapsed into a single interbreeding population where they come into secondary contact. Nonetheless, the zone of secondary contact and the diagnosability of the Nooksack dace in terms of mt DNA represent significant aspects of the evolutionary legacy within R. cataractae and support its conservation importance. [ABSTRACT FROM AUTHOR]

The longnose dace ( Rhinichthys cataractae (Valenciennes, 1842); Cyprinidae) is one of the most widespread freshwater fishes in North America, and across its range there have been several divergent forms described that are of uncertain taxonomic status. One of these forms, the Nooksack dace, is found in southwestern British Columbia and adjacent portions of western Washington, and is distinguished from longnose dace by a lower number of lateral-line scales. We sequenced a total of approximately 1400 base pairs (bp) of mitochondrial DNA (mtDNA) and noted that the longnose dace found west of the Continental Divide and Nooksack dace constituted reciprocally monophyletic clades that differed from each other by between 2% and 3% sequence divergence. Sequence analysis at two nuclear loci (the S7 ribosomal protein intron 1 ( S7) and recombination activation gene 1 ( RAG1)), however, showed no consistent difference between longnose dace and Nooksack dace and several alleles were shared between them. By contrast, consistent differences at both mtDNA and nuclear DNA loci were resolved between R. cataractae samples from east and west of the Continental Divide. The Nooksack dace does not appear to warrant separate taxonomic status from the longnose dace, but the mtDNA differences support its recognition as an important component of the evolutionary and biogeographic legacy of R. cataractae. [ABSTRACT FROM AUTHOR]

Kokanee and sockeye salmon are the freshwater-resident and anadromous forms, respectively, of Oncorhynchus nerka. Unique populations of 'black' kokanee are found in Lake Saiko, Japan, and in Anderson and Seton lakes in the southwestern interior of British Columbia. They are distinct from other populations of O. nerka in that black kokanee display black nuptial colouration and they spawn between 20 to 70 m below the surface of lakes in the winter or early spring. Analysis of mitochondrial DNA and nine microsatellite loci supported the hypothesis that black kokanee in Lake Saiko and in Anderson and Seton lakes have had a diphyletic origin resulting from at least two episodes of divergence in the North Pacific basin. Further, black kokanee in the Anderson and Seton lakes system were genetically distinct from sympatric populations of sockeye salmon in Gates and Portage creeks (inlets to Anderson and Seton lakes, respectively) and were distinct from one another. Anderson and Seton lake black kokanee differed dramatically from one another in standard length at maturity, but no differences were found between the two populations in size-adjusted maximum body depth or in gill raker numbers. Independent origins of black kokanee represent novel diversity within O. nerka, are consistent with the importance of parallel evolution in the origin of biodiversity, and suggest that independent management regimes are required for the persistence of black kokanee biodiversity within a physically interconnected lake system. [ABSTRACT FROM AUTHOR]

Contact zones between divergent lineages of aquatic taxa have been described from the northeastern Pacific Ocean. We surveyed samples of Dolly Varden ( Salvelinus malma) from their North American range for variation at 14 microsatellite DNA loci. After accounting for hybridization between Dolly Varden and co-occurring bull trout ( Salvelinus confluentus) and Arctic char ( Salvelinus alpinus), we found evidence for two genetic lineages of Dolly Varden consistent with the previously recognized subspecies, northern Dolly Varden ( S. m. malma) and southern Dolly Varden ( S. m. lordii). We documented a contact zone between the two subspecies from the eastern Alaska Peninsula to Cook Inlet, Alaska, where admixture values (i.e., the proportion of the genome estimated to be composed of northern Dolly Varden, QNDV) ranged between QNDV = 0.245 and 0.754 across about 700 ocean kilometres. Populations of Dolly Varden showing low admixture (i.e., less than 5%) were located a minimum of 346 km to the west to 1200 km to the southeast, respectively, from the contact zone. The two lineages of Dolly Varden probably stem from isolation and subsequent divergence in, and dispersal from, distinct northern and southern Pleistocene glacial refugia and substantiate the treatment of S. malma as two subspecies and as at least two designatable units under Canada's Species at Risk Act. [ABSTRACT FROM AUTHOR]

Objective: Physical therapists develop patient-centered exercise prescriptions to help overcome the physical, emotional, psychosocial, and environmental stressors that undermine a person's health. Optimally prescribing muscle activity for people with disability, such as a spinal cord injury, is challenging because of their loss of volitional movement control and the deterioration of their underlying skeletal systems. This report summarizes spinal cord injury–specific factors that should be considered in patient-centered, precision prescription of muscle activity for people with spinal cord injury. This report also presents a muscle genomic and epigenomic analysis to examine the regulation of the proliferator-activated receptor γ coactivator 1α (PGC-1α) (oxidative) and myostatin (hypertrophy) signaling pathways in skeletal muscle during low-frequency (lower-force) electrically induced exercise versus higher-frequency (higher-force) electrically induced exercise under constant muscle recruitment (intensity). Methods: Seventeen people with spinal cord injury participated in 1 or more unilateral electrically induced exercise sessions using a lower-force (1-, 3-, or 5-Hz) or higher-force (20-Hz) protocol. Three hours after the exercise session, percutaneous muscle biopsies were performed on exercised and nonexercised muscles for genomic and epigenomic analysis. Results: We found that low-frequency (low-force) electrically induced exercise significantly increased the expression of PGC-1α and decreased the expression of myostatin, consistent with the expression changes observed with high-frequency (higher-force) electrically induced exercise. Further, we found that low-frequency (lower-force) electrically induced exercise significantly demethylated, or epigenetically promoted, the PGC-1α signaling pathway. A global epigenetic analysis showed that >70 pathways were regulated with low-frequency (lower-force) electrically induced exercise. Conclusion: These novel results support the notion that low-frequency (low-force) electrically induced exercise may offer a more precise rehabilitation strategy for people with chronic paralysis and severe osteoporosis. Future clinical trials are warranted to explore whether low-frequency (lower-force) electrically induced exercise training affects the overall health of people with chronic spinal cord injury. [ABSTRACT FROM AUTHOR]

The boundaries between oceanographic domains often function as dispersal barriers for many temperate marine species with a dispersive pelagic larval phase. Yelloweye rockfish (Sebastes ruberrimus, YR) are widely distributed across the northeastern Pacific Ocean, inhabiting coastal rocky reefs from the Aleutian Islands in Alaska through southern California. This species exhibits an extended pelagic larval duration and has the capacity for long distance larval transport. We assayed 2,862 YR individuals from 13 general areas in the northeast Pacific Ocean for allelic variation at nine microsatellite loci. Bayesian model-based clustering analyses grouped individuals from the Strait of Georgia (SG) into a distinct genetic cluster, while individuals from outer coastal water locations (OCLs) were partitioned equally across two genetic clusters, including the cluster associated with the SG fish. Pairwise FST values were consistently an order of magnitude higher for comparisons between the SG and OCLs than they were for all OCL-OCL comparisons (∼0.016 vs. ∼0.001). This same pattern was observed across two time points when individuals were binned into an “old” and “young” group according to birth year (old: ∼0.020 vs. 0.0003; young: ∼0.020 vs. ∼0.004). Additionally, mean allelic richness was markedly lower within the SG compared to the OCLs (8.00 vs. 10.54–11.77). These results indicate that the Strait of Georgia “deep-basin” estuary oceanographic domain acts as a dispersal barrier from the outer coastal waters via the Juan de Fuca Strait. Alternatively, selection against maladapted dispersers across this oceanographic transition may underlie the observed genetic differentiation between the Georgia basin and the outer coastal waters, and further work is needed to confirm the SG-OCL divide acts as a barrier to larval dispersal. [ABSTRACT FROM AUTHOR]

Defining units of conservation below the species level is a widely accepted conservation priority, but is especially challenging for widespread taxa that have experienced diverse geographic histories and exist across heterogenous environments. The lake chub (Pisces: Couesius plumbeus) is a widespread freshwater fish in North America and occurs from the southcentral USA to northwestern Alaska and Canada. We used mtDNA sequence analysis to test for divergent lineages predicted to occur as a result of survival of lake chub in distinct glacial refugia. Lake chub consisted of two major mtDNA lineages separated by 3.8% sequence divergence which are probably late to pre-Pleistocene in origin. We combined these data with those consistent with thermal adaptation in fish living in thermal springs versus those living in a lake with wide seasonal temperature variation, and with data on distribution of lake chub in major watershed units. We assessed these data against objective criteria developed to identify conservation units under Canadian endangered species legislation. Our analysis identified twelve major units of conservation within C. plumbeus that could be assessed under Canada's Species-at-Risk Act. Our study illustrates how different character traits manifested at very different spatial scales can be used to define conservation units within widely-distributed taxa. [ABSTRACT FROM AUTHOR]

Evaluation of legislation and procedures in place to help recover species at risk of extinction is an important component of conservation efforts. Despite its biological importance and key role in species protection and recovery legislation, identification of critical habitat is inconsistently applied. We analyzed data from 126 recovery strategies implemented under Canada's nascent (2002) Species at Risk Act (SARA) to determine how lead agency, Federal Court rulings, and the proportion of independent team members influenced identification of critical habitat. Only 17% of strategies led by the Department of Fisheries and Oceans included critical habitat, compared with 63% of strategies led by Environment Canada, indicating that aquatic species at risk are much less likely to have critical habitat identified. A 50% increase in recovery strategies that identified critical habitat following precedent-setting court judgments suggests that legal action by nongovernmental organizations played a key role in the evolution of recovery policy for species at risk in Canada. The proportion of independent scientists on a recovery team was statistically unrelated to identification of critical habitat at a national scale, but case studies indicate that independent team members may play an important role in ensuring compliance and transparency during recovery planning. [ABSTRACT FROM AUTHOR]

Brassy minnow ( Hybognathus hankinsoni Hubbs, 1929) have disjunct distributions in western Canada, making them a species of conservation concern. We assessed changes in the distribution of invasive species as factors influencing the distribution of brassy minnow and other native species by comparing historical and current distributions in the lower Fraser River in British Columbia. We tested effects of physical habitat parameters on local distributions of brassy minnow and for evidence of negative interactions between brassy minnow and invasive brown bullhead ( Ameiurus nebulosus (Lesueur, 1819)). Comparison of contemporary and historical (1956 and 1959) fish distributions indicated significant declines in native cypriniform (minnows and suckers) species, including brassy minnow, but no change in the number of invasive species, although there was some faunal turnover. Logistic regression suggested that conductivity, turbidity, and water temperature were important predictors of brassy minnow presence. Appearances of adult-sized brown bullhead at one site corresponded with reduced abundance of native fishes. In growth experiments with brassy minnow, brown bullhead, and redside shiner ( Richardsonius balteatus (Richardson, 1836)), brassy minnow exhibited mass loss and mortalities, suggesting that they were poor competitors. Our results contribute to a better understanding of abiotic and biotic factors affecting distribution and persistence of brassy minnow. [ABSTRACT FROM AUTHOR]

In northern Canada, lake chub (Cyprinidae: Couesius plumbeus) have colonized a variety of thermal springs that differ substantially from the ancestral environment in both mean temperature and thermal variation. To examine whether this environmental change is associated with differences in physiological traits, we compared the thermal breadth, capacity for acclimation of thermal tolerance, and metabolic enzymes in populations of lake chub from three habitats: a warm but variable hot spring, a thermally constant warm spring, and a seasonally variable temperate lake. Thermal breadth was generally lowest in fish from the constant environment, and this difference was statistically significant in fish acclimated at 10° and 25°C. Critical thermal maximum (CTmax) increased with increasing acclimation temperature in all populations. CTmax was similar among populations when acclimated at high temperatures but greater in the variablespring population acclimated to low temperature (10°C). Critical thermal minimum was also dependent on acclimation temperature in all populations but differed among populations such that fish from the stable-spring habitat were not as tolerant to cold temperature when acclimated to 25°C. Temperate- and variable- spring populations showed an increase in mitochondrial enzyme activities (citrate synthase and cytochrome c oxidase) with decreasing acclimation temperature, but this response was absent in the stable-temperature population. Protein content did not change with acclimation temperature in the stable-temperature population, while it increased with decreasing acclimation temperature in both variable thermal habitat populations. Our study suggests that interpopulation variation in thermal physiology is associated with habitat thermal variability. [ABSTRACT FROM AUTHOR]

Pyruvate constitutes a critical branch point in cellular carbon metabolism. We have identified two proteins, Mpc1 and Mpc2, as essential for mitochondrial pyruvate transport in yeast, Drosophila, and humans. Mpc1 and Mpc2 associate to form an ~150-kitodalton complex in the inner mitochondrial membrane. Yeast and Drosophila mutants lacking MPC1 display impaired pyruvate metabolism, with an accumulation of upstream metabolites and a depletion of tricarboxylic acid cycle intermediates. Loss of yeast Mpc1 results in defective mitochondrial pyruvate uptake, and silencing of MPC1 or MPC2 in mammalian cells impairs pyruvate oxidation. A point mutation in MPC1 provides resistance to a known inhibitor of the mitochondrial pyruvate carrier. Human genetic studies of three families with children suffering from lactic acidosis and hyperpyruvatemia revealed a causal locus that mapped to MPC1, changing single amino acids that are conserved throughout eukaryotes. These data demonstrate that Mpc1 and Mpc2 form an essential part of the mitochondrial pyruvate carrier. [ABSTRACT FROM AUTHOR]

Parapatric freshwater and anadromous parasitic lampreys (Petromyzontiformes) from southwestern Vancouver Island, British Columbia, have been described as distinct taxa (Vancouver lamprey ( (Beamish, 1982)) and Pacific lamprey ( (Richardson, 1836)), respectively), using morphology, life history, and physiology. We tested for genetic differentiation at microsatellite DNA loci between these taxa and similar freshwater parasitic lampreys from two other lakes. The number of alleles and expected heterozygosity averaged 3.8 and 0.50, respectively, across loci and populations, and anadromous populations were more variable than freshwater populations. Population subdivision was moderate ( FST = 0.096, P < 0.001) and 3% of the total variation was found between taxa and 1.7% was found among populations within taxa (both P < 0.001). Parapatric freshwater and anadromous parasitic lampreys separated by a maximum of 40 km were more distinct (mean FST = 0.042) than were anadromous populations located 800 km from one another (mean FST = 0.012). Localities within lakes with parasitic freshwater lampreys, however, showed little differentiation ( FST = 0.0-0.08). Our data support recognizing E. macrostomus and E. tridentatus as distinct species, but similar levels of differentiation between these taxa and other freshwater parasitic lampreys suggest a species complex where the taxonomy remains unclear. [ABSTRACT FROM AUTHOR]

Ecological speciation is the evolution of reproductive isolation as a direct or indirect consequence of divergent natural selection. Reduced performance of hybrids in nature is thought to be an important process by which natural selection can favor the evolution of assortative mating and drive speciation. Benthic and limnetic sympatric species of threespine stickleback ( Gasterosteus aculeatus) are adapted to alternative trophic niches (bottom browsing vs. open water planktivory, respectively) and reduced feeding performance of hybrids is thought to have contributed to the evolution of reproductive isolation. We tested this 'hybrid-disadvantage hypothesis' by inferring growth rates from otoliths sampled from wild, free-ranging benthic, limnetic, and hybrid sticklebacks in two lakes. There were significant differences in growth rate between lakes, life-history stages, and among years (maximum P = 0.02), as well as interactions between most factors, but not between hybrid and parental species sticklebacks in most comparisons. Our results provide little evidence of a growth disadvantage in hybrid sticklebacks when free-ranging in nature. Although trophic ecology per se may contribute less to ecological speciation than envisioned, it may act in concert with other aspects of stickleback biology, such as interactions with parasites, predators, competitors, and/or sexual selection, to present strong multifarious selection against hybrids. [ABSTRACT FROM AUTHOR]

Prioritization of efforts to maintain biodiversity is an important component of conservation, but is more often applied to ecosystems or species than within species. We assessed distinctiveness among 27 populations of rainbow trout (Salmonidae: Oncorhynchus mykiss) from British Columbia, Canada, using microsatellite DNA variation (representing historical or contemporary demography) and morphology (representing adaptive variation). Standardized genetic scores, that is, the average deviation across individuals within populations from the overall genetic score generated by factorial correspondence analysis, ranged from 1.05 to 4.90 among populations. Similar standardized morphological scores, generated by principal components analysis, ranged from 1.19 to 5.35. There was little correlation between genetic and morphological distinctiveness across populations, although one population was genetically and morphologically the most distinctive. There was, however, a significant correlation ( r = 0.26, P = 0.008) between microsatellite ( FST) and morphological ( PST) divergence. We combined measures of allelic richness, genetic variation within, and divergence among, populations and morphological variation to provide a conservation ranking of populations. Our approach can be combined with other measures of biodiversity value (habitat, rarity, human uses, threat status) to rationalize the prioritization of populations, especially for widespread species where geographic isolation across distinct environments promotes intraspecific variability. [ABSTRACT FROM AUTHOR]

Aim To assess how changing taxonomy and distribution data affect estimates of faunal homogenization and differentiation as agents of global change in freshwater fishes. Location Provinces and territories of Canada. Methods Species presence–absence data were collated in 2000 and 2005 from regional and national lists, and faunal homogenization and differentiation were calculated using Jaccard’s faunal similarity index. Differences between time periods and areas were summarized using principal coordinate analysis. Differences in faunal assemblages between native and total faunas were assessed via Whittaker’s (1960) beta diversity (βw) index and tests of differences in multivariate dispersion of fish species compositions. Results Among aquatic ecoregions in one province (British Columbia) there were four taxonomic changes and 18 distributional changes between the 2000 and 2005 databases. Pairwise Jaccard’s faunal similarity index between the eight aquatic ecoregions declined by an average of 4.8% from 35.9% in native faunas to 31.1% in total faunas (introductions – extinctions/extirpations) indicating overall faunal differentiation. Average pairwise similarity declined by 0.9% between 2000 and 2005. Across thirteen provinces and territories of Canada, there were five taxonomic changes and 61 distributional changes between the 2000 and 2005 databases. Generally, faunal homogenization increased; pairwise Jaccard’s increased by an average of 1.8% from 27.1% in native faunas to 28.9% in total faunas or an average of 0.6% per comparison. Main conclusions Despite changing taxonomy and fish distribution information, comparative analysis of 2000 and 2005 databases consistently show overall faunal differentiation at the smallest (provincial) spatial scale and homogenization at the largest scale (across Canada) and that these trends continued between time periods. Homogenization and differentiation followed expectations from conceptual models based on the relative prevalence of species invasions and extinctions within communities. General conclusions of the onset and extent of homogenization and differentiation were relatively insensitive to our changing understanding of taxonomy and distribution. [ABSTRACT FROM AUTHOR]

We assayed microsatellite DNA variation among 1013 broad whitefish. Coregonus nasus. from 36 localities within the lower Mackenzie River (Northwest Territories. Canada) to provide the first assessment of fine-scale population structuring of broad whitefish in this large system. Among sampling locations, averaged across all loci, the number of alleles ranged from 3.00 to 6.71 and heterozygosity averaged 0.54. Population subdivision was generally low. but significant (θ = 0.026. P < 0.05), although pairwise comparisons indicated that overall significance was heavily influenced by comparisons between anadromous and lacustrine groups. Bayesian-based STRUCTURE analysis suggested that there are two main genetic groups within our study area: anadromous and lacustrine broad whitefish. A mixture analysis indicated that all populations contribute to the lower Mackenzie River subsistence fishery, yet catches were dominated by Peel River fish, highlighting the importance of this tributary. Our data also supported the idea that there are several units of conservation among Mackenzie River system broad whitefish populations and that management strategies should be implemented accordingly. [ABSTRACT FROM AUTHOR]

TBC1D4 (also known as AS 160) regulates glucose transporter 4 (GLUT4) translocation and glucose uptake in adipocytes and skeletal muscle. Its mode of action involves phosphorylation of serine (S)/threonine (T) residues by upstream kinases resulting in inactivation of Rab-GTPase-activating protein (Rab-GAP) activity leading to GLUT4 mobilization. The majority of known phosphorylation sites on TBC1D4 lie within the Akt consensus motif and are phosphorylated by insulin stimulation. However, the 5'-AMP-activated protein kinase (AMPK) and other kinases may also phosphoiylate TBC1D4, and therefore we hypothesized the presence of additional phosphorylation sites. Mouse skeletal muscles were contracted or stimulated with 5-aminoimidazole-4-carboxamide1-13-D-ribofuranoside (AICAR), and muscle lysates were subjected to mass spectrometry analyses resulting in identification of novel putative phosphorylation sites on TBC1D4. The surrounding amino acid sequence predicted that S71 1 would be recognized by AMPK. Using a phosphospecific antibody against S71 1, we found that AICAR and contraction increased S711 phosphorylation in mouse skeletal muscle, and this increase was abolished in muscle-specific AJVIPKα2 kinase-dead transgenic mice. Exercise in human vastus lateralis muscle also increased TBC 1 D4 S711 phosphorylation. Recombinant AIvIPK, but not Aktl, Akt2, or PKCζ, phosphorylated purified muscle TBC 1D4 on S711 in vitro. Interestingly, S711 was also phosphoiylated in response to insulin in an Akt2and rapamycinindependent, but a wortmannin-sensitive, manner, suggesting this site is regulated by one or more additional upstream kinases. Despite increased S7 11 phosphorylation with AICAR, contraction, and insulin, mutation of S711 to alanine did not alter glucose uptake in response to these stimuli. S711 is a novel TBC1D4 phosphorylation site regulated by AMPK in skeletal muscle. [ABSTRACT FROM AUTHOR]

Abstract: Relationships among the species of Northern Hemisphere smelts (family Osmeridae) have long been debated in the fish systematics literature. Eight independent studies based on morphological characters failed to reach any consensus on osmerid interrelationships. We reconstruct the osmerid phylogeny based on DNA sequence data from three mitochondrial (cytb, 16S, 12S) and three nuclear (ITS2, S71, RAG1) gene regions from multiple individuals of the 14 species in 6 genera, using the Japanese ayu (Plecoglossus altivelis) as the outgroup. Analyses with different combinations of nuclear and mitochondrial datasets yielded a generally well-resolved phylogeny of the genera that conflicts with previous hypotheses of osmerid interrelationships, and Shimodaira–Hasegawa tests suggest our topology with the current molecular dataset is significantly better than earlier reconstructions. In addition, mapping 114 morphological characters used in previous studies onto our phylogeny shows widespread homoplasy, which is likely the source of the systematic disagreement produced in earlier works. [Copyright &y& Elsevier]

The Akt substrate of 160 kDa (AS160) is phosphorylated on Akt substrate (PAS) motifs in response to insulin and contraction in skeletal muscle, regulating glucose uptake. Here we discovered a dissociation between AS160 protein expression and apparent AS160 PAS phosphorylation among soleus, tibialis anterior, and extensor digitorum longus muscles. Immunodepletion of AS160 in tibialis anterior muscle lysates resulted in minimal depletion of the PAS band at 160 kDa, suggesting the presence of an additional PAS immunoreactive protein. By immunoprecipitation and mass spectrometry, we identified this protein as the AS160 paralog TBC1D1, an obesity candidate gene regulating GLUT4 translocation in adipocytes. TBC1D1 expression was severalfold higher in skeletal muscles compared with all other tissues and was the dominant protein detected by the anti-PAS antibody at 160 kDa in tibialis anterior and extensor digitorum longus but not soleus muscles. In vivo stimulation by insulin, contraction, and the AMP-activated protein kinase (AMPK) activator AICAR increased TBC1D1 PAS phosphorylation. Using mass spectrometry on TBC1D1 from mouse skeletal muscle, we identified several novel phosphorylation sites on TBC1D1 and found the majority were consensus or near consensus sites for AMPK. Semiquantitative analysis of spectra suggested that AICAR caused greater overall phosphorylation of TBC1D1 sites compared with insulin. Purified Akt and AMPK phosphorylated TBC1D1 in vitro, and AMPK, but not Akt, reduced TBC1D1 electrophoretic mobility. TBC1D1 is a major PAS immunoreactive protein in skeletal muscle that is phosphorylated in vivo by insulin, AICAR, and contraction. Both Akt and AMPK phosphorylate TBC1D1, but AMPK may be the more robust regulator. [ABSTRACT FROM AUTHOR]

Aim We address questions about trans-Pacific distributions of marine organisms and the North Pacific Ocean as a centre of marine biodiversity through a phylogenetic and biogeographical study of a pan-Pacific genus of Northern Hemisphere smelts ( Hypomesus, Pisces: Osmeridae). Location North Pacific Ocean. Methods Relationships of the five species of Hypomesus from throughout the North Pacific were reconstructed through maximum likelihood and Bayesian phylogenetic analyses of sequence data from two mitochondrial (cyt b, 16S) and three nuclear (ITS2, S71, RAG1) gene regions of five to 25 individuals per species, totalling 3588 characters. The resulting phylogenies were used to test hypotheses of species relationships and geographical origins using both dispersal-based and maximum likelihood methods for inferring ancestral areas (lagrange). Cyt b sequence divergence and a Bayesian approach (beast) were used to estimate the timeframe of Hypomesus evolution, which was compared with work on similarly distributed taxa. Results Hypothesized trans-Pacific Ocean relationships based on lateral line scale counts were not supported by the phylogeny, suggesting parallel evolution of this phenotype, although we found one such relationship between the western H. japonicus and the two eastern Pacific species ( H. pretiosus and H. transpacificus). Dispersalist approaches rejected an early proposal of a double-compression vicariant mechanism as well as an eastern Pacific origin. Results from thelagrange analysis suggested a more widespread ancestor, although also supporting a role for the western Pacific. Divergence estimates suggested that most splits between species occurred in the mid-Miocene, and the most recent speciation event, between the eastern Pacific species, occurred in the Pliocene to early Pleistocene. Main conclusions Our molecular data indicate that the character historically used to define relationships within Hypomesus, lateral line scale count, does not reflect ancestry within the genus. Biogeographical reconstructions suggest an important role for the western North Pacific in the diversification of Hypomesus. While uncertainty remains over the date of origin for this genus, estimates place the divergences during periods of climatic cooling that have been important in generating diversity in a number of similarly distributed organisms. Additional comparative data will provide further insight into the relative importance of the western region in generating diversity in the North Pacific Ocean. [ABSTRACT FROM AUTHOR]

OBJECTIVE--Insulin and contraction increase skeletal muscle glucose uptake through distinct and additive mechanisms. However, recent reports have demonstrated that both signals converge on the Akt substrate of 160 kDa (AS160), a protein that regulates GLUT4 translocation. Although AS160 phosphorylation is believed to be the primary factor affecting its activity, AS160 also possesses a calmodulin-binding domain (CBD). This raises the possibility that contraction-stimulated increases in Ca2+/calmodulin could also modulate AS160 function. RESEARCH DESIGN AND METHODS--To evaluate the AS160 CBD in skeletal muscle, empty-vector, wild-type, or CBD-mutant AS160 cDNAs were injected into mouse muscles followed by in vivo electroporation. One week later, AS160 was overexpressed by ∼14-fold over endogenous protein. RESULTS--Immunoprecipitates of wild-type and CBD-mutant AS160 were incubated with biotinylated calmodulin in the presence of Ca2+. Wild-type AS160, but not the CBD-mutant AS160, associated with calmodulin. Next, we measured insulin- and contraction-stimulated glucose uptake in vivo. Compared with empty-vector and wild-type AS160, insulin-stimulated glucose uptake was not altered in muscles expressing CBD-mutant AS160. In contrast, contraction-stimulated glucose uptake was significantly decreased in CBD-mutant--expressing muscles. This inhibitory effect on glucose uptake was not associated with aberrant contraction-stimulated AS160 phosphorylation. Interestingly, AS160 expressing both calmodulin-binding and Rab-GAP (GTPase-activating protein) domain point mutations (CBD + R/K) fully restored contraction-stimulated glucose uptake. CONCLUSIONS--Our results suggest that the AS160 CBD directly regulates contraction-induced glucose uptake in mouse muscle and that calmodulin provides an additional means of modulating AS160 Rab-GAP function independent of phosphorylation. These findings define a novel AS160 signaling component, unique to contraction and not insulin, leading to glucose uptake in skeletal muscle. Diabetes 56:2854-2862, 2007 [ABSTRACT FROM AUTHOR]

We used mitochondrial (cytb, 16S) and nuclear (ITS2, S71, RAG1) sequence data to assess the degree of genetic differentiation between the recently described lacustrine Hypomesus chishimaensis from the Kuril Islands and its anadromous congener H. nipponensis from Hokkaido, Japan. The results showed that the two species are not genetically distinct at these loci. Phylogenetic trees depicted an unstructured clade consisting of individuals of both species and sequence data showed haplotypes that are shared between putative species for all markers. We conclude that H. chishimaensis is an alternative life-history type of H. nipponensis that should not be recognized at either the species or the sub-species level. [ABSTRACT FROM AUTHOR]

The article reports on the role of AMP-activated protein kinase (AMPK) in the molecular adaptation to endurance exercise. It is noted that AMPK is activated in response to the contraction of the muscle, chronic chemical activation of AMPK results in increases in GLUT4, citric acid enzymes, UCP-3, and hexokinase, and mitochondrial DNA induced by chronic creatine phosphate depletion in wild-type mice are not observed in dominant-negative AMPK mice. These observations posit that AMPK activation induced by muscle contraction is responsible in part for adaptations to endurance exercise training.

Microsatellite DNA variation was assayed among 383 bull trout (Salvelinus confluentus) from 20 Pacific coastal localities from the Skeena River (central British Columbia) to the Olympic Peninsula (western Washington State). An average of 1.7 alleles was resolved per population and heterozygosity averaged 0.35. Twenty-six fish were identified as bull trout × Dolly Varden (Salvelinus malma) hybrids. Population subdivision was substantial (θ = 0.33), but subdivision was higher (θ = 0.46) when interior populations (N = 37) were included, indicating a major genetic distinction between "coastal" and "interior" bull trout. Bull trout populations north of the Squamish River were genetically more similar to interior bull trout than to other more southern coastal populations, suggesting that they had been founded by headwater transfers from interior populations. Individual assignment of bull trout averaged 53.4% correct assignment among populations (range: 12%–95%). Mixture analysis indicated that most fish from the lower Fraser River recreational fishery originated from major nearby tributaries (e.g., Pitt, upper Lillooet, and Chilliwack rivers). Our results substantiate the existence of two major evolutionary lineages of bull trout and highlight the importance of tributary habitats for the persistence of local populations, as well as for those that forage in downstream areas on the lower Fraser River. [ABSTRACT FROM AUTHOR]

Muscle contraction results in phosphorylation and activation of the AMP-activated protein kinase (AMPK) by an AMPK kinase (AMPKK). LKB1/STRAD/MO25 (LKB1) is the major AMPKK in skeletal muscle; however, the activity of LKB 1 is not increased by muscle contraction. This finding suggests that phosphorylation of AMPK by LKB1 is regulated by allosteric mechanisms. Creatine phosphate is depleted during skeletal muscle contraction to replenish ATP. Thus the concentration of creatine phosphate is an indicator of cellular energy status. A previous report found that creatine phosphate inhibits AMPK activity. The purpose of this study was to determine whether creatine phosphate would inhibit 1) phosphorylation of AMPK by LKB1 and 2) AMPK activity after phosphorylation by LKB1. We found that creatine phosphate did not inhibit phosphorylation of either recombinant or purified rat liver AMPK by LKB1. We also found that creatine phosphate did not inhibit 1) active recombinant α1β1γ1 or α2β2γ2 AMPK, 2) AMPK immunoprecipitated from rat liver extracts by either the α1 or α2 subunit, or 3) AMPK chromatographically purified from rat liver. Inhibition of skeletal muscle AMPK by creatine phosphate was greatly reduced or eliminated with increased AMPK purity. In conclusion, these results suggest that creatine phosphate is not a direct regulator of LKB1 or AMPK activity. Creatine phosphate may indirectly modulate AMPK activity by replenishing ATP at the onset of muscle contraction. [ABSTRACT FROM AUTHOR]

Recent research suggests that LKB1 is the major AMP-activated protein kinase kinase (AMPKK). Peroxisome-proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a master coordinator of mitochondrial biogenesis. Previously we reported that skeletal muscle LKB1 protein increases with endurance training. The purpose of this study was to determine whether training-induced increases in skeletal muscle LKB1 and PGC-1α protein exhibit a time course and intensity-dependent response similar to that of citrate synthase. Male Sprague-Dawley rats completed endurance- and interval-training protocols. For endurance training, rats trained for 4. 11, 25, or 53 days. Interval-training rats trained identically to endurance-trained rats, except that alter 25 days interval training was combined with endurance training. Time course data were collected from endurance-trained red quadriceps (RQ) after each time point. Interval training data were collected from soleus. RQ, and white quadriceps (WQ) muscle after 53 days only. Mouse protein 25 (MO25) and PGC-1α protein increased significantly after 4 days. Increased citrate synthase activity, increased LKB1 protein, and decreased AMPKK activity were found after 11 days. Maximal increases occurred after 4 days for hexokinase II, 25 days for MO25, and 53 days for citrate synthase, LKB1, and PGC-1α. In WQ, but not RQ or soleus, interval training had an additive effect to endurance training and induced significant increases in all proteins measured. These results demonstrate that LKB1 and PGC-1α protein abundances increase with endurance and interval training similarly to citrate synthase. The increase in LKB1 and PGC-1α with endurance and interval training may function to maintain the training-induced increases in mitochondrial mass. [ABSTRACT FROM AUTHOR]

This study was designed to examine activity of AMP-activated protein kinase kinase (AMPKK) in muscles from nontrained and endurance-trained rats. Rats were trained 5 days/wk, 2 h/day for 8 wk at a final intensity of 32 m/min up a 15% grade with 30-s sprints at 53 m/min every 10 min. Gastrocnemius muscles were stimulated in situ in trained and nontrained rats for 5 min at frequencies of 0.4/s and 1/s. Gastrocnemius LKB1 protein, a putative component of the AMPKK complex (LKB1, STRAD, and MO25), increased approximately twofold in response to training. Phosphorylation of AMP-activated protein kinase (AMPK) determined by Western blot and AMPK activity of immunoprecipitates (both isoforms) was increased at both stimulation rates in both trained and nontrained muscles. AMPKK activity was 73% lower in resuspended polyethylene glycol precipitates of muscle extracts from the trained compared with nontrained rats. AMPKK activity did not increase in either trained or nontrained muscle in response to electrical stimulation, even though phospho-AMPK did increase. These results suggest that AMPKK is activated during electrical stimulation of both trained and nontrained muscle by mechanisms other than covalent modification. [ABSTRACT FROM AUTHOR]

Introgressive hybridization is a common feature of many zones of contact between divergent lineages of fishes. This is particularly common when taxa that are normally allopatric come into artificial (human-induced) secondary contact. We examined 18 native populations of westslope cutthroat trout (Oncorhynchus clarki lewisi, WCT) to determine the extent of introgressive hybridization with introduced rainbow trout (O. mykiss, RBT) and the genetic structure of hybridizing populations in the upper Kootenay River, southeastern British Columbia, Canada. Using four diagnostic nuclear loci we calculated a hybrid index, inbreeding coefficient,FIS, and the linkage disquilibrium correlation coefficient,R ij, for each locality to determine the distribution of genotypes in each population. We also categorized the 142 hybrid individuals found across localities into four hybrid classes based on their genotypes. The majority of localities (11/18) showed a unimodal distribution of genotypes skewed towards genotypes of WCT. Two localities, however (lower Gold Creek and Lodgepole Creek) showed a flat to bimodal distribution and one site (lower Bull River) showed a unimodal distribution skewed towards RBT genotypes. The majority of hybrid individuals were classified genotypically as WCT backcrosses (59%) and post-F1 individuals (24%). We found a skewed ratio of pure WCT to pure RBT (17 : 1) and only four F1 hybrids (3%), suggesting that the spread of RBT alleles may be facilitated by hybrids straying to neighbouring populations. We also tested for the action of selection in one population using cohort analyses, but found little evidence of differential selection between pure WCT and hybrid individuals. Pooled across age classes there were significant differences in genotypic frequencies among loci suggesting differential introgression. There was no asymmetry to the hybridization between rainbow trout and westslope cutthroat trout because both species’ mitochondrial DNA haplotypes were observed at similar frequencies in the hybrids. Our analyses suggest that hybrid swarms are likely to form in the upper Kootenay River drainage and that certain native WCT populations in British Columbia are at risk of local genomic extinction. [ABSTRACT FROM AUTHOR]

How much of the variation in adaptive divergence can be explained by gene flow? The answer to this question should objectively reveal whether gene flow generally places a substantial constraint on evolutionary diversification. We studied multiple independent lake-stream population pairs of threespine stickleback (Gasterosteus aculeatus). For each pair, we quantified adaptive divergence based on morphological traits that have a genetic basis and are subject to divergent selection. We then estimated gene flow based on variation at five unlinked microsatellite loci. We found a consistent and significant pattern for morphological divergence to be positively correlated with genetic divergence and negatively correlated with gene flow. Statistical significance and the amount of variation explained varied within and among traits: 36.1-74.1% for body depth and 11.8-51.7% for gill raker number. Variation within each trait was the result of differences among methods for estimating genetic divergence and gene flow. Variation among traits likely reflects different strengths of divergent selection. We conclude that gene flow has a substantial effect on adaptive divergence in nature but that the magnitude of this effect varies among traits. An alternative explanation is that cause and effect are reversed: adaptive divergence is instead constraining gene flow. This effect seems relatively unimportant for our system because genetic divergence and gene flow were not correlated with ecologically relevant habitat features of lakes (surface area) or streams (width, depth, flow, canopy openness). [ABSTRACT FROM AUTHOR]

This study furthers the documentation of the geographical distribution of two divergent ( c. 3%) mitochondrial DNA clades in the threespine stickleback ( Gasterosteus aculeatus) and tests the hypotheses that the northeastern Pacific distribution has been influenced by post-glacial colonization and lake elevation and that clade identity is associated with certain morphological attributes such as reduction in body armour. Lakes and nearshore marine environments of the eastern Pacific Basin from southcentral Alaska to southeastern British Columbia, (BC) Canada. Restriction enzyme analysis of polymerase chain reaction-amplified mitochondrial DNA fragments (cytochrome b) from a total of 45 new populations combined with existing data for a further 45 populations. Lake elevation data were collected for 78 localities and tested for an association with mtDNA clade by contingency table analyses. Morphological data were collected on sticklebacks from eight samples representing four lake-stream systems and tested for differentiation among populations with different mtDNA clade identities using analyses of variance. We extend the known distribution of the haplotypes diagnostic of the Trans-North Pacific Clade (TNPC) southward to mid-Vancouver Island and, for the first time, on mainland BC, in other island populations far from putative refugia, and in nearby anadromous populations. A morphological analysis indicated that the mainland population with the TNPC was not characterized by reduced spine or lateral plate (‘armour’) traits that characterize some putative relict populations on the Queen Charlotte Islands. We found a significant association between lake elevation and the presence of the TNPC; the TNPC was present more often in lakes located at or lower than 42 m than in higher elevation lakes. Our data support the hypothesis that post-glacial colonization by TNPC-bearing marine sticklebacks and aspects of lake ‘accessibility’ were important in determining the distribution of mtDNA clades in the eastern Pacific Ocean basin. More generally, our study demonstrates how processes acting both across immense geographic scales (e.g. pan-Pacific dispersal) and local scales (lake accessibility contingent on timing and extent of isostatic rebound) may interact to explain biogeographical patterns. [ABSTRACT FROM AUTHOR]

The salamander, Dicamptodon tenebrosus, is threatened by habitat loss and fragmentation associated with forest harvest activities. We used three microsatellite loci and 38 amplified fragment length polymorphisms (AFLPs) to quantify population structure and indirectly evaluate the impacts of forest harvesting on this species. We sampled two old growth sites, three second growth sites and three recently clearcut sites in British Columbia, Canada. Microsatellite allelic richness and the percentage of polymorphic AFLPs were positively correlated with the age of forest stands. Similarly, heterozygosity estimated from both marker types was positively correlated with stand age. Population subdivision (Fst) estimated among forested sites using microsatellite and AFLP markers was 0.033 and 0.095, respectively. Lower genetic variation and heterozygosity in recent clearcuts suggest that clearcut logging may be associated with local population declines. Our genetic findings are consistent with previous studies that report lower salamander densities in recently clearcut sites. [Copyright &y& Elsevier]

Faunal homogenization and differentiation occur when geographic regions show increased or decreased, respectively, similarity to each other in species composition owing to introductions and extinctions or extirpations. I used species presence–absence data for "native" (i.e., estimated species compositions before European settlement) and "total" (i.e., including nonnative fishes and extinctions) faunas to examine faunal similarity of freshwater fishes among aquatic ecoregions of British Columbia and among Canadian provinces and territories. British Columbia ecoregions showed faunal differentiation as the mean Jaccard's faunal similarity coefficient for total faunas was significantly less than that for native faunas (31.4% versus 34.9%), but some ecoregions showed homogenization (e.g., Vancouver Island and Columbia River ecoregions). Comparisons across Canada showed low but significant homogenization; average pairwise Jaccard's coefficient was higher in total versus native faunas (29.1% similarity versus 27.8%, respectively). British Columbia's fish fauna increased the most in similarity to other areas (except the three territories), with an average increase of 4.9%. Native faunal similarity patterns are part of Canada's natural heritage but are threatened by human-mediated increases in nonnative species and extinctions. This analysis provides a baseline to track changes in inter regional faunal relationships at different geographic scales. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the interplay between natural selection and gene flow in the adaptive divergence of populations of threespine stickleback that reside parapatrically in lakes and streams. Details of the morphological analysis; Discussion on the reciprocal transplant enclosure experiments; Examination of the gene flow and its adaptive divergence.

Examines the hypothesis that Dolly Varden are subdivided into evolutionary lineages stemming form isolation in distinct glacial refugia. Definition of phylogeography; Factors that can influence phylogeographic inference within species; Historical component to hybridization in northwestern North America.

Dolly Varden char (Salvelinus malma) and bull trout (Salvelinus confluentus) hybridize in areas of secondary contact in northwestern North America but maintain their genetic integrity in spite of gene flow. We examined juvenile stream ecology and adult reproductive ecology of these species in sympatry to test for specializations to alternative niches that may act as a basis for natural selection against hybrids. Juvenile Dolly Varden occupied deeper, faster water and foraged more during daytime in the drift, whereas bull trout used shallower, slower water and made more nighttime foraging attempts towards the substrate. The species showed extensive diet overlap (Schoener's index = 0.7–0.9), and we found evidence for density compensation between species among sites. Our results suggest no obvious basis for selection against hybrids at the juvenile stream-rearing life-history stage. Bull trout, however, are adfluvial, whereas Dolly Varden are permanent stream residents. Bull trout are also much larger at maturity (50–80 cm vs. 12–15 cm) and build redds in faster, deeper water using larger substrate sizes. Consequently, hybrid genotypes may be selected against in these alternative life-history niches or during reproduction owing to their intermediate size at maturity and size-dependent spawning habitat use and mate choice.La Dolly Varden (Salvelinus malma) et l'Omble à tête plate (Salvelinus confluentus) s'hybrident dans les régions de contact secondaire dans le nord-ouest de l'Amérique du Nord, mais ils maintiennent leur intégrité génétique malgré le flux de gènes. Nous avons étudié l'écologie des juvéniles dans les cours d'eau et de l'écologie de la reproduction des adultes de ces espèces dans des situations de sympatrie pour vérifier l'existence de spécialisations à des niches de rechange qui pourraient servir de base à une sélection naturelle contre les hybrides. Les juvéniles de la Dolly Varden vivent en eau plus profonde et plus rapide et font plus de recherche de nourriture pendant le jour, alors que l'Omble à tête plate occupe des eaux moins profondes et moins rapides et fait plus de tentatives de recherche de nourriture sur le substrat la nuit. Les deux espèces ont des régimes alimentaires qui se chevauchent considérablement (indice de Schoener = 0,7–0,9) et il y a des indices de l'existence d'une compensation de densité entre les espèces parmi les sites. Nos résultats n'identifient aucune base évidente pour postuler l'existence d'une sélection négative des hydrides au cours de la partie du cycle biologique correspondant au développement des juvéniles en eau courante. L'Omble à tête plate, cependant, fait des migrations vers les eaux stagnantes (c'est une espèce « adfluviale »), alors que la Dolly Varden réside en permanence dans les eaux courantes. Les ombles sont aussi beaucoup plus grands à maturité (50–80 cm contre 12–15 cm) et construisent leurs gravières en eau plus profonde et plus rapide, utilisant des substrats plus grossiers. Conséquemment, il peut y avoir une sélection négative des génotypes hybrides dans ces niches de rechange de développement juvénile ou alors durant la reproduction; les hybrides possèdent, en effet, une taille intermédiaire à maturité et leur utilisation des habitats de fraie et leur choix de partenaire sont des comportements reliés à la taille.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Analyzes the genetic diversity of Dolly Varden and bull trout using mitochondrial DNA and microsatellite DNA. Hybrid zones; Phylogenetic structure within species across their native ranges; Levels of microsatellite diversity.

We present evidence of the first successful natural spawning of Atlantic salmon ( Salmo salar) documented on the Pacific coast of North America. Twelve juvenile Atlantic salmon composed of two year classes were captured in the Tsitika River, British Columbia. We analyzed restriction-length polymorphisms of PCR-amplified 5S rDNA and mtDNA to confirm that these individuals were Atlantic salmon. Scale analysis strongly suggested they were the products of natural spawning by feral adults. The gut contents, size, and condition of these individuals suggest that Atlantic salmon are successfully maturing in the Tsitika River, British Columbia. This event has raised concerns that the presence and possible establishment of feral Atlantic salmon may further jeopardize the continued persistence of already fragile native Pacific salmonids through competition for resources and occupation of niches that are currently underutilized. [ABSTRACT FROM AUTHOR]

The drug terazosin (TZ) binds to and can enhance the activity of the glycolytic enzyme phosphoglycerate kinase 1 (PGK1) and can increase ATP levels. That finding prompted studies of TZ in Parkinson's disease (PD) in which decreased neuronal energy metabolism is a hallmark feature. TZ was neuroprotective in cell-based and animal PD models and in large epidemiological studies of humans. However, how TZ might increase PGK1 activity has remained a perplexing question because structural data revealed that the site of TZ binding to PGK1 overlaps with the site of substrate binding, predicting that TZ would competitively inhibit activity. Functional data also indicate that TZ is a competitive inhibitor. To explore the paradoxical observation of a competitive inhibitor increasing enzyme activity under some conditions, we developed a mass action model of TZ and PGK1 interactions using published data on PGK1 kinetics and the effect of varying TZ concentrations. The model indicated that TZ-binding introduces a bypass pathway that accelerates product release. At low concentrations, TZ binding circumvents slow product release and increases the rate of enzymatic phosphotransfer. However, at high concentrations, TZ inhibits PGK1 activity. The model explains stimulation of enzyme activity by a competitive inhibitor and the biphasic dose-response relationship for TZ and PGK1 activity. By providing a plausible mechanism for interactions between TZ and PGK1, these findings may aid development of TZ or other agents as potential therapeutics for neurodegenerative diseases. The results may also have implications for agents that interact with the active site of other enzymes. [ABSTRACT FROM AUTHOR]

Classically, mitochondrial respiration responds to decreased membrane potential (ΔΨ) by increasing respiration. However, we found that for succinate‐energized complex II respiration in skeletal muscle mitochondria (unencumbered by rotenone), low ΔΨ impairs respiration by a mechanism culminating in oxaloacetate (OAA) inhibition of succinate dehydrogenase (SDH). Here, we investigated whether this phenomenon extends to far different mitochondria of a tissue wherein ΔΨ is intrinsically low, i.e., interscapular brown adipose tissue (IBAT). Also, to advance our knowledge of the mechanism, we performed isotopomer studies of metabolite flux not done in our previous muscle studies. In additional novel work, we addressed possible ways ADP might affect the mechanism in IBAT mitochondria. UCP1 activity, and consequently ΔΨ, were perturbed both by GDP, a well‐recognized potent inhibitor of UCP1 and by the chemical uncoupler carbonyl cyanide m‐chlorophenyl hydrazone (FCCP). In succinate‐energized mitochondria, GDP increased ΔΨ but also increased rather than decreased (as classically predicted under low ΔΨ) O2 flux. In GDP‐treated mitochondria, FCCP reduced potential but also decreased respiration. Metabolite studies by NMR and flux analyses by LC‐MS support a mechanism, wherein ΔΨ effects on the production of reactive oxygen alters the NADH/NAD+ ratio affecting OAA accumulation and, hence, OAA inhibition of SDH. We also found that ADP‐altered complex II respiration in complex fashion probably involving decreased ΔΨ due to ATP synthesis, a GDP‐like nucleotide inhibition of UCP1, and allosteric enzyme action. In summary, complex II respiration in IBAT mitochondria is regulated by UCP1‐dependent ΔΨ altering substrate flow through OAA and OAA inhibition of SDH. [ABSTRACT FROM AUTHOR]

Tests the hypothesis that behavioral domination by coho salmon promotes variability in habitat use and in the duration of freshwater use by chinook salmon. Use of principal components analysis; Degrees of emigration; Habitat preference between species; Sympatric evolution.

Addresses the issue of genetic divergence between the Misty lake-stream pair given the conflict between the allozyme and morphological data, while highlighting the testing of two alternative hypotheses concerning the evolutionary origin of the lake-stream pairs on the Queen Charlotte Islands, and northern Vancouver Islands. Indication that stiklebacks were collected in a number of areas; Indepth look at the study.