The role of ecotype‐environment interactions in intraspecific trophic niche partitioning subsequent to stocking

Worldwide, stocking of fish represents a valuable tool for conservation and maintenance of species exploited by recreational fishing. Releases of hatchery-reared fish are more and more recognized to have numerous demographic, ecological, and genetic impacts on wild populations. However, consequences on intraspecific trophic relationships have rarely been investigated. In this study, we assessed the impacts of supplementation stocking and resulting introgressive hybridization on the trophic niches occupied by stocked, local, and hybrid lake trout (Salvelinus namaycush) within populations of piscivorous and planktivorous ecotypes stocked from a wild piscivorous source population. We compared trophic niches using stable isotope analysis (δ13C and δ15N) and trophic position among the three genetic origins. Putative genetic effects were tested with phenotype–genotype association of “life history” ecological traits (body size, growth rate, condition index, and trophic niche) and genotypes (RADseq SNP markers) using redundant discriminant analysis (RDA). Results showed that sympatry resulting from the stocking of contrasting ecotypes is a risk factor for niche partitioning. Planktivorous populations are more susceptible to niche partitioning, by competitive exclusion of the local fish from a littoral niche to an alternative pelagic/profundal niche. Observed niche partitioning is probably a manifestation of competitive interactions between ecotypes. Our results emphasize that ecotypic variation should be considered for more efficient management and conservation practices and in order to mitigate negative impact of supplementation stocking

RAD-QTL mapping reveals both genome-level parallelism and different genetic architecture underlying the evolution of body shape in Lake Whitefish (Coregonus clupeaformis) species pairs

Parallel changes in body shape may evolve in response to similar environmental conditions, but whether such parallel phenotypic changes share a common genetic basis is still debated. The goal of this study was to assess whether parallel phenotypic changes could be explained by genetic parallelism, multiple genetic routes, or both. We first provide evidence for parallelism in fish shape by using geometric morphometrics among 300 fish representing five species pairs of Lake Whitefish. Using a genetic map comprising 3438 restriction site-associated DNA sequencing single-nucleotide polymorphisms, we then identified quantitative trait loci underlying body shape traits in a backcross family reared in the laboratory. A total of 138 body shape quantitative trait loci were identified in this cross, thus revealing a highly polygenic architecture of body shape in Lake Whitefish. Third, we tested for evidence of genetic parallelism among independent wild populations using both a single-locus method (outlier analysis) and a polygenic approach (analysis of covariation among markers). The single-locus approach provided limited evidence for genetic parallelism. However, the polygenic analysis revealed genetic parallelism for three of the five lakes, which differed from the two other lakes. These results provide evidence for both genetic parallelism and multiple genetic routes underlying parallel phenotypic evolution in fish shape among populations occupying similar ecological niches.Keywords : Adaptive radiation, Parallel evolution, Fish body shape, Geometric morphometrics, Genotyping-by-sequencing

Le mentorat en début de carrière : retombées sur la charge professorale et conditions de mise en œuvre d’un programme en milieu universitaire

Cette synthèse d’écrits a été menée dans le but de faire état des retombées du mentorat en milieu éducatif, plus précisément, le mentorat destiné aux enseignants universitaires en début de carrière et des conditions de mise en œuvre d’un programme. Les principaux constats tirés de cette synthèse montrent que la question du mentorat informel par rapport au mentorat formel reste sans réponse définitive quant à la supériorité d’une forme sur l’autre. De plus, en dépit des divergences de points de vue dans la littérature, il ressort que le mentorat joue un rôle positif dans le développement professionnel des nouveaux enseignants pour l’ensemble des fonctions composant leur charge professorale, incluant la fonction enseignement. Enfin, les expériences menées dans différents établissements nous permettent d’examiner des modalités d’implantation et de fonctionnement ainsi que de proposer un modèle de mentorat en trois étapes.This review of the literature was carried out in order to assess the impact of mentoring in educational settings and in particular mentoring addressing faculty in early stages of their academic career and the necessary requirements for implementing programmes. The main issues raised by our study indicate that as far as informal mentoring and formal mentoring are concerned there is no definite answer regarding the efficiency of one over the other. Furthermore despite contrasted views in the literature, it seems that mentoring does have a positive impact on professional development of early stage academics for most of the components of their professorial function including teaching. Last of all experiences carried out in various institutions allowed us to examine implementation and practise in mentoring and to devise a framework comprising three steps

Identification of Golgi-localized acyl transferases that palmitoylate and regulate endothelial nitric oxide synthase

Lipid modifications mediate the subcellular localization and biological activity of many proteins, including endothelial nitric oxide synthase (eNOS). This enzyme resides on the cytoplasmic aspect of the Golgi apparatus and in caveolae and is dually acylated by both N-myristoylation and S-palmitoylation. Palmitoylation-deficient mutants of eNOS release less nitric oxide (NO). We identify enzymes that palmitoylate eNOS in vivo. Transfection of human embryonic kidney 293 cells with the complementary DNA (cDNA) for eNOS and 23 cDNA clones encoding the Asp-His-His-Cys motif (DHHC) palmitoyl transferase family members showed that five clones (2, 3, 7, 8, and 21) enhanced incorporation of [3H]-palmitate into eNOS. Human endothelial cells express all five of these enzymes, which colocalize with eNOS in the Golgi and plasma membrane and interact with eNOS. Importantly, inhibition of DHHC-21 palmitoyl transferase, but not DHHC-3, in human endothelial cells reduces eNOS palmitoylation, eNOS targeting, and stimulated NO production. Collectively, our data describe five new Golgi-targeted DHHC enzymes in human endothelial cells and suggest a regulatory role of DHHC-21 in governing eNOS localization and function

T-cell homing therapy for reducing regulatory T cells and preserving effector T-cell function in large solid tumors

Purpose: Infused autologous tumor-infiltrating lymphocytes (TIL) and tumor-targeted chimeric antigen receptor (CAR) T cells typically surround malignant lesions or penetrate small tumor nodules but fail to penetrate large solid tumors, significantly compromising their antitumor impact. Strategies to overcome this primary challenge are largely required. Experimental Design: We tested the effects of IL12 plus doxorubicin on T-cell penetration and efficacy in solid tumors in a murine lung cancer model, a murine breast carcinoma lung metastasis model, and two human xenograft tumor models bearing large tumors (> 10 mm). Results: Intriguingly, this simple approach increased the numbers, the distribution, and the depth of penetration of infused CD8+ T cells in these tumors, including both TILs and CAR T cells. This combined treatment halted tumor progression and significantly extended survival time. Studies of the underlying mechanism revealed multiple effects. First, the combined treatment maintained the high ratios of immune-stimulatory receptors to immune-inhibitory receptors on infiltrated CD8+ T cells, reduced the accumulation of immunosuppressive regulatory T cells, and enhanced the numbers of T-bet+ effector T cells in the tumors. Second, doxorubicin induced chemokines CXCL9 and CXCL10, which may attract NKG2D+CD8+ T cells to tumors, and this effect was boosted by IL12-induced IFNg accumulation in tumors, promoting the penetration of NKG2D+CD8+ T cells. Conclusions: The deep penetration of infused T cells associated with combined IL12 plus doxorubicin yielded striking therapeutic effects in murine and human xenograft solid tumors. This approach might broaden the application of T-cell therapy to a wider range of solid tumors

Supplementation stocking of Lake Trout (Salvelinus namaycush) in small boreal lakes : Ecotypes influence on growth and condition

Supplementation stocking is a commonly used management tool to sustain exploited fish populations. Possible negative consequences of supplementation on local stocks are a concern for the conservation of wild fish populations. However, the direct impacts of supplementation on life history traits of local populations have rarely been investigated. In addition, intraspecific hybridization between contrasting ecotypes (planktivorous and piscivorous) has been seldom considered in supplementation plans. Here, we combined genetic (genotype-by-sequencing analysis) and life history traits to document the effects of supplementation on maximum length, growth rates, body condition and genetic admixture in stocked populations of two Lake Trout ecotypes from small boreal lakes in Quebec and Ontario, Canada. In both ecotypes, the length of stocked individuals was greater than local individuals and, in planktivorous-stocked populations, most stocked fish exhibited a planktivorous-like growth while 20% of fish exhibited piscivorous-like growth. The body condition index was positively related to the proportion of local genetic background, but this pattern was only observed in stocked planktivorous populations. We conclude that interactions and hybridization between contrasting ecotypes is a risk that could result in deleterious impacts and possible outbreeding depression. We discuss the implications of these findings for supplementation stocking

Genetic mixed stock analysis of an interceptory Atlantic salmonfishery in the Northwest Atlantic

Interceptory fisheries represent an ongoing threat to migratory fish stocks particularly when managed in the absence of stock specific catch and exploitation information. Atlantic salmon from the southern portion of the North American range may be subject to exploitation in the commercial and recreational salmon fisheries occurring in the French territorial waters surrounding St. Pierre and Miquelon off southern Newfoundland. We evaluated stock composition of Atlantic salmon harvested in the St. Pierreand Miquelon Atlantic salmon fishery using genetic mixture analysis and individual assignment with a microsatellite baseline (15 loci, 12,409 individuals, 12 regional groups) encompassing the species western Atlantic range. Individual salmon were sampled from the St. Pierre and Miquelon fishery over four years (2004, 2011, 2013, and 2014). Biological characteristics indicate significant variation among years in the size and age distribution. Nonetheless, estimates of stock composition of the samples showed consistent dominance of three regions (i.e., Southern Gulf of St. Lawrence, Gaspe Peninsula, and New-foundland). Together salmon from these regions accounted for more than 70% of annual harvest over the decade examined. Comparison of individual assignments and biological characteristics revealed a trend of declining fresh water age with latitude of assigned region. Moreover, locally harvested Newfoundland salmon were ten times more likely to be small or one sea winter individuals whereas Quebec and Gaspe Peninsula salmon were two-three times more likely to be harvested as large or two sea winter salmon.Estimates of region specific catch were highest for salmon from the southern Gulf of St. Lawrence region ranging from 242 to 887 individuals annually. This work illustrates how genetic analysis of interceptory marine fisheries can directly inform assessment and management efforts in highly migratory marines pecies

Solution structure of the inner DysF domain of myoferlin and implications for limb girdle muscular dystrophy type 2b

Mutations in the protein dysferlin, a member of the ferlin family, lead to limb girdle muscular dystrophy type 2B and Myoshi myopathy. The ferlins are large proteins characterised by multiple C2 domains and a single C-terminal membrane-spanning helix. However, there is sequence conservation in some of the ferlin family in regions outside the C2 domains. In one annotation of the domain structure of these proteins, an unusual internal duplication event has been noted where a putative domain is inserted in between the N- and C-terminal parts of a homologous domain. This domain is known as the DysF domain. Here, we present the solution structure of the inner DysF domain of the dysferlin paralogue myoferlin, which has a unique fold held together by stacking of arginine and tryptophans, mutations that lead to clinical disease in dysferlin

Rapid and adaptive evolution of MHC genes under parasite selection in experimental vertebrate populations

The genes of the major histocompatibility complex are the most polymorphic genes in vertebrates, with more than 1,000 alleles described in human populations. How this polymorphism is maintained, however, remains an evolutionary puzzle. Major histocompatibility complex genes have a crucial function in the adaptive immune system by presenting parasite-derived antigens to T lymphocytes. Because of this function, varying parasite-mediated selection has been proposed as a major evolutionary force for maintaining major histocompatibility complex polymorphism. A necessary prerequisite of such a balancing selection process is rapid major histocompatibility complex allele frequency shifts resulting from emerging selection by a specific parasite. Here we show in six experimental populations of sticklebacks, each exposed to one of two different parasites, that only those major histocompatibility complex alleles providing resistance to the respective specific parasite increased in frequency in the next host generation. This result demonstrates experimentally that varying parasite selection causes rapid adaptive evolutionary changes, thus facilitating the maintenance of major histocompatibility complex polymorphism