RESUMO
Advancements in the field of reintroduction biology are needed, but understanding of how to effectively conduct translocations, particularly with snakes, is lacking. We conducted a systematic review of snake translocation studies to identify potential tactics for reducing postrelease effects. We included studies on intentional, human-mediated, wild-wild, or captive-wild translocations to any location, regardless of motive or number of snakes translocated. Only studies that presented results for at least 1 of 4 outcomes (movement behavior, site fidelity, survival, or population establishment) were included. We systematically searched 4 databases for published studies and used 5 methods to search the gray literature. Our search and screening criteria yielded 121 data sources, representing 130 translocation cases. We quantified the association between 15 translocation tactics and short-term translocation outcomes by calculating odds ratios and used forest plots to display results. Snake translocations involved 47 species (from mainly 2 families), and most were motivated by research, were monitored for at least 6 months, occurred in North America, and took place from the 1990s onward. The odds of a positive snake translocation outcome were highest with release of captive reared or juvenile snakes, release of social groups together, delayed release, provision of environmental enrichment or social housing before release, or minimization of distance translocated. The odds of a positive outcome were lowest when snakes were released early in their active season. Our results do not demonstrate causation, but outcomes of snake translocation were associated with 8 tactics (4 of which were strongly correlated). In addition to targeted comparative studies, we recommend practitioners consider the possible influence of these tactics when planning snake translocations.
La biología de la reintroducción requiere de avances; sin embargo, hay muy poco conocimiento sobre cómo realizar efectivamente las reubicaciones, particularmente las de las serpientes. Revisamos sistemáticamente los estudios sobre reubicación de serpientes para identificar las potenciales maniobras de reducción del estrés postliberación. Incluimos estudios sobre las reubicaciones a cualquier localidad que hayan sido intencionales, mediadas por humanos, de ambiente silvestre a ambiente silvestre o de cautiverio a ambiente silvestre sin importar el motivo o el número de serpientes reubicadas. Sólo incluimos estudios que presentaran resultados para al menos 1 de los cuatro resultados posibles: conducta de movimiento, fidelidad al sitio, supervivencia o establecimiento poblacional. Buscamos sistemáticamente en cuatro bases de datos de estudios publicados y usamos cinco métodos para buscar en la literatura gris. Nuestros criterios de búsqueda y revisión resultaron en 121 fuentes de datos, las cuales representaron 130 casos de reubicación. Cuantificamos la asociación entre 15 maniobras de reubicación y los resultados a corto plazo de las reubicaciones mediante el cálculo de la razón de probabilidades y usamos diagramas de efecto para mostrar los resultados. La reubicación de serpientes incluyó a 47 especies (principalmente de dos familias) y la mayoría estuvo motivada por la investigación, fue monitoreada durante seis meses (al menos), se ubicó en América del Norte y ocurrieron a partir de la década de 1990. La probabilidad de que la reubicación de serpientes tuviera un resultado positivo fueron mayores con la liberación de serpientes criadas o juveniles, la liberación de grupos sociales en conjunto, la liberación retardada, el suministro de enriquecimiento ambiental o alojamiento previo a la liberación o la reducción de la distancia de reubicación. Esta misma probabilidad fue menor cuando las serpientes fueron liberadas tempranamente durante su temporada activa. Nuestros resultados no demuestran causalidad, pero los resultados de la reubicación de serpientes estuvieron asociados con ocho maniobras (cuatro de las cuales contaban con una correlación sólida). Además de los estudios comparativos focalizados, recomendamos que los practicantes consideren la posible influencia de estas maniobras cuando se planifiquen la reubicación de serpientes.
Assuntos
Conservação dos Recursos Naturais , Serpentes , Animais , Conservação dos Recursos Naturais/métodos , América do Norte , Serpentes/genéticaRESUMO
Investigation of the reproductive phenology and spawning behaviour of imperilled species in relation to environmental variability is needed to understand a critical component of species life history. In this study, we used redside dace (Clinostomus elongatus), a freshwater leuciscid listed as Endangered under Canada's Species at Risk Act, to model spawning phenology and make predictions about spawning initiation using historical and climate change projected thermal cues (measured as cumulative growing degree days), and provide an ethological description of spawning behaviour. Logistic regression models applied to 4 years of average daily stream water temperature data and field behavioural observations of the onset of spawning activity indicated a 50% probability of spawning initiation when cumulative growing degree days reached 214°C days and a 95% probability of spawning initiation at 288°C days. Using two climate change scenarios (i.e., a mid-century 1.6°C increase and an end of century 3.6°C increase), spawning initiation was predicted to advance 3 days by the year 2050 and 7 days by the year 2100. Underwater video cameras placed at two sites within an urban stream captured 73 unique spawning events revealing that redside dace spawn in pairs as well as in dense, tightly packed groups (more than 20 individuals). Moreover, there is evidence of redside dace having a polygynandrous mating system, as female redside dace spawned with multiple males in 45.2% of the total spawning events recorded. Taken together, this study provides important insights into redside dace spawning initiation and behaviour, key life-history traits having conservation implications for future reproductive success and, ultimately, population dynamics.
Assuntos
Cyprinidae , Rios , Masculino , Feminino , Animais , Reprodução , Mudança Climática , ÁguaRESUMO
Transcriptomic research provides a mechanistic understanding of an organism's response to environmental challenges such as increasing temperatures, which can provide key insights into the threats posed by thermal challenges associated with urbanization and climate change. Differential gene expression and alternative splicing are two elements of the transcriptomic stress response that may work in tandem, but relatively few studies have investigated these interactions in fishes of conservation concern. We studied the imperilled redside dace (Clinostomus elongatus) as thermal stress is hypothesized to be an important cause of population declines. We tested the hypothesis that gene expression-splicing interactions contribute to the thermal stress response. Wild fish exposed to acute thermal stress were compared with both handling controls and fish sampled directly from a river. Liver tissue was sampled to study the transcriptomic stress response. With a gene set enrichment analysis, we found that thermally stressed fish showed a transcriptional response related to transcription regulation and responses to unfolded proteins, and alternatively spliced genes related to gene expression regulation and metabolism. One splicing factor, prpf38b, was upregulated in the thermally stressed group compared with the other treatments. This splicing factor may have a role in the Jun/AP-1 cellular stress response, a pathway with wide-ranging and context-dependent effects. Given large gene interaction networks and the context-dependent nature of transcriptional responses, our results highlight the importance of understanding interactions between gene expression and splicing for understanding transcriptomic responses to thermal stress. Our results also reveal transcriptional pathways that can inform conservation breeding, translocation and reintroduction programs for redside dace and other imperilled species by identifying appropriate source populations.
Assuntos
Processamento Alternativo , Cyprinidae , Animais , Cyprinidae/fisiologia , Fatores de Processamento de RNA , Temperatura , TranscriptomaRESUMO
Estimating metabolic rate in wild, free-swimming fish is inherently challenging. Here, we explored using surgically implanted heart rate biologgers to estimate metabolic rate in two warmwater piscivores, bowfin Amia calva (Linneaus 1766) and largemouth bass Micropterus salmoides (Lacepède 1802). Fish were surgically implanted with heart rate loggers, allowed to recover for 24 h, exposed to a netting and air exposure challenge, and then placed into respirometry chambers so that oxygen consumption rate (MO2 ) could be measured in parallel to heart rate (fH ) for a minimum of 20 h (ca. 20 estimates of MO2 ). Heart rate across the duration of the experiment (at 19°C) was significantly higher in largemouth bass (mean ± s.d., 45 ± 14 beats min-1 , range 18-86) than in bowfin (27 ± 9 bpm, range 16-98). Standard metabolic rate was also higher in largemouth bass (1.06 ± 0.19 mg O2 kg-1 min-1 , range 0.46-1.36) than in bowfin (0.89 ± 0.17 mg O2 kg-1 min-1 , range 0.61-1.28). There were weak relationships between fH and MO2 , with heart rate predicting 28% of the variation in oxygen consumption in bowfin and 23% in largemouth bass. The shape of the relationship differed somewhat between the two species, which is perhaps unsurprising given their profound differences in physiology and life history, illustrating the need to carry out species-specific validations. Both species showed some potential for a role of fH in efforts to estimate field metabolic rates, although further validation experiments with a wider range of conditions (e.g., digestive states, swimming activity) would likely help improve the strength of the MO2 -fH relationship for use in field applications.
Assuntos
Bass , Consumo de Oxigênio , Animais , Frequência Cardíaca , NataçãoRESUMO
A decline in sperm quality with age is a common prediction of senescence-based hypotheses and empirical studies. While widely studied across taxa, there is little known on the effect of ageing on sperm quality in amphibians, especially in captive populations used for controlled propagation and reintroduction efforts. Here, we investigated variation in sperm quality metrics (i.e., motility, concentration, and morphology) in the endangered Mississippi gopher frog (Lithobates sevosus) among males of three age categories using individuals from captive breeding populations housed at three different zoological institutions. Different aged males across the species expectant lifespan (1-9, 1-2, 3-4, and 8-9-year-old subcategories) were chosen in an attempt to identify an optimal breeding age relevant for captive breeding programs. Moreover, we explored and statistically controlled for potential differences in sperm quality which may be attributed to the type of induction hormones and source populations that differed among institutions. Results indicated that males of different ages did not differ in sperm motility or concentration. However, we did find that older males (8-9 years old) had significantly longer sperm than other age categories and younger males (1-2 years old) had significantly more atypical sperm than other age categories. Furthermore, we found no significant differences in any sperm quality metrics between the different induction hormones or source populations used at the different institutions. Within a captive breeding program, this information is especially valuable as our results indicate that males that have only recently sexually matured may not be ready to breed, while older males maintain sperm quality metrics presumably related to fertilization success.
Assuntos
Espécies em Perigo de Extinção , Ranidae/fisiologia , Análise do Sêmen/veterinária , Envelhecimento , Animais , Animais de Zoológico , Conservação dos Recursos Naturais , Masculino , Espermatozoides/citologia , Espermatozoides/fisiologiaRESUMO
In species with limited opportunities for pre-ejaculatory sexual selection (behavioural components), post-ejaculatory mechanisms may provide opportunities for mate choice after gametes have been released. Recent evidence from a range of taxa has revealed that cryptic female choice (i.e., female-mediated differential fertilization bias), through chemical cues released with or from eggs, can differentially regulate the swimming characteristics of sperm from various males and ultimately determine male fertilization success under sperm competition. We assessed the potential role that such female-modulated chemical cues play in influencing sperm swimming characteristics in beach-spawning capelin (Mallotus villosus), an externally fertilizing fish that mates as couples (one male and one female) or threesomes (two males and one female) with presumably limited opportunities for pre-ejaculatory sexual selection. We assayed sperm swimming characteristics under varying doses and donor origins of egg cues and also examined the possibility of assortative mating based on body size. We found mating groups were not associated by size, larger males did not produce better quality ejaculates, and egg cues (regardless of dosage or donor identity) did not influence sperm swimming characteristics. Our findings suggest that intersexual pre-ejaculatory sexual selection and cryptic female choice mediated by female chemical cues are poorly developed in capelin, possibly due to unique natural selection constraints on reproduction.
Assuntos
Preferência de Acasalamento Animal , Osmeriformes/fisiologia , Animais , Tamanho Corporal , Feminino , Fertilização , MasculinoRESUMO
The objective of this study was to investigate variation in sperm quality metrics (motility, velocity, and concentration) in the critically endangered Mississippi gopher frog (Lithobates sevosus) over three sampling time points after a luteinizing hormone-releasing hormone analog (LHRHa) induction injection. Sperm was repeatedly collected from 11 individuals over three sampling times (30, 60, and 120 min) after injection. Variation in sperm quality was investigated using a repeated-measures mixed model approach. Repeated measures analyses of variance showed a significant effect of sampling time for percent motility and velocity. Concentration was found to be marginally related to sampling time, while progressive motility was not significantly related to time after injection. Our findings are important for optimizing assisted reproduction-related fertilization success and increasing the successful propagation of endangered species of imperiled frogs in captive breeding programs.
Assuntos
Hormônio Liberador de Gonadotropina/farmacologia , Ranidae/fisiologia , Espermatozoides/efeitos dos fármacos , Animais , Espécies em Perigo de Extinção , Hormônio Liberador de Gonadotropina/administração & dosagem , Masculino , Espermatozoides/fisiologiaRESUMO
In this study, we investigated the effects of acoustic tag implantation on standard and routine metabolic rate (SMR and RMR, estimated via oxygen consumption), critical swimming speed (Ucrit ), survival and growth in juveniles of rainbow trout Oncorhynchus mykiss and lake trout Salvelinus namaycush. Tag burdens ranged from 1.8% to 7.5% across the two species. Growth rates in acoustic-tagged fish were equal to or higher than those in other treatments. Acoustic-tagged S. namaycush had a marginally lower Ucrit than controls but that effect was not replicated in the O. mykiss experiment. Tagging did not have clear effects on metabolic rate but there was an interaction whereby SMR and RMR tended to increase with time since surgery in tagged O. mykiss but not in other treatments (the same trend did not occur in S. namaycush). Survival was high across treatments (mean 98% survival among O. mykiss, 97.5% among S. namaycush). There were no statistically significant effects of tag burden (percentage of body mass) except for a weak negative relationship with growth rate (across species) and a weak positive relationship with Ucrit but only in the O. mykiss. Collectively, our findings suggest there were minor, context-dependent effects of acoustic tagging in juvenile S. namaycush and O. mykiss during an eight-week laboratory experiment. Further research will be required to assess whether tagging can cause meaningful behavioural effects in these species in captivity or in the wild and whether there is a tag burden threshold above which deleterious effects consistently occur.
Assuntos
Sistemas de Identificação Animal , Consumo de Oxigênio/fisiologia , Natação/fisiologia , Truta/fisiologia , Animais , Metabolismo Energético , Especificidade da Espécie , Truta/classificaçãoRESUMO
In oviparous species, maternal carotenoid provisioning can deliver diverse fitness benefits to offspring via increased survival, growth and immune function. Despite demonstrated advantages of carotenoids, large intra- and interspecific variation in carotenoid utilization exists, suggesting trade-offs associated with carotenoids. In Chinook salmon (Oncorhynchus tshawytscha), extreme variation in carotenoid utilization delineates two colour morphs (red and white) that differ genetically in their ability to deposit carotenoids into tissues. Here, we take advantage of this natural variation to examine how large differences in maternal carotenoid provisioning influence offspring fitness. Using a full factorial breeding design crossing morphs and common-garden rearing, we measured differences in a suite of fitness-related traits, including survival, growth, viral susceptibility and host response, in offspring of red (carotenoid-rich eggs) and white (carotenoid-poor eggs) females. Eggs of red females had significantly higher carotenoid content than those of white females (6× more); however, this did not translate into measurable differences in offspring fitness. Given that white Chinook salmon may have evolved to counteract their maternal carotenoid deficiency, we also examined the relationship between egg carotenoid content and offspring fitness within each morph separately. Egg carotenoids only had a positive effect within the red morph on survival to eyed-egg (earliest measured trait), but not within the white morph. Although previous work shows that white females benefit from reduced egg predation, our study also supports a hypothesis that white Chinook salmon have evolved additional mechanisms to improve egg survival despite low carotenoids, providing novel insight into evolutionary mechanisms that maintain this stable polymorphism.
Assuntos
Carotenoides/administração & dosagem , Aptidão Genética , Pigmentação/genética , Pigmentação/fisiologia , Salmão/fisiologia , Ração Animal , Fenômenos Fisiológicos da Nutrição Animal , Animais , Feminino , Doenças dos Peixes/imunologia , Doenças dos Peixes/virologia , Humanos , Vírus da Necrose Hematopoética Infecciosa , Fenômenos Fisiológicos da Nutrição Materna , Óvulo , Reação em Cadeia da Polimerase em Tempo Real/veterinária , Infecções por Rhabdoviridae/imunologia , Infecções por Rhabdoviridae/veterinária , Infecções por Rhabdoviridae/virologia , Salmão/crescimento & desenvolvimentoRESUMO
The Dengue virus (DENV) envelope (E) protein is the major component of the viral surface and is structurally subdivided into three domains, ED1, ED2 and ED3. ED3 elicits potent neutralizing antibodies and contains two major antigenic sites: the DENV-type-specific and DENV-complex-reactive antigenic sites. Each site is composed of a limited subset of residues that are required for monoclonal antibody (mAb) binding. Here we show that DENV-2-type-specific mAb 9A3D-8 utilizes the functionally critical residues K307, V308, K310, I312, P332, L387, L389 and N390 for ED3 binding. Surprisingly, this DENV-type-specific epitope is predicted to overlap with the ED3 DENV-complex-reactive antigenic site on the viral surface. Further, this unique binding site enables mAb 9A3D-8 to neutralize virus infectivity at relatively low occupancy of virions compared to other ED3 mAbs identified to date. Together, the data in this study indicate that this is a new DENV-2-type-specific antigenic site on ED3.
Assuntos
Anticorpos Monoclonais/metabolismo , Anticorpos Antivirais/metabolismo , Epitopos de Linfócito B/metabolismo , Proteínas do Envelope Viral/imunologia , Proteínas do Envelope Viral/metabolismo , Animais , Anticorpos Neutralizantes/metabolismo , Chlorocebus aethiops , Ligação Proteica , Domínios Proteicos , Células VeroRESUMO
Alternative reproductive tactics (ARTs) are prevalent in nature, where smaller parasitic males typically have better sperm quality than larger territorial guard males. At present, it is unclear what is causing this phenomenon. Our objective was to gain insights into sperm form and function by examining flagellar beating patterns (beat frequency, wave amplitude, bend length, bend angle, wave velocity) and biomechanical sperm metrics (velocity, hydrodynamic power output, propulsive efficiency) of wild spawning Chinook salmon ARTs. Ovarian fluid and milt were collected to form a series of eight experimental blocks, each composed of ovarian fluid from a unique female and sperm from a unique pair of parasitic jack and guard hooknose males. Sperm from each ART were activated in river water and ovarian fluid. Flagellar parameters were evaluated from recordings using high-speed video microscopy and biomechanical metrics were quantified. We show that ART has an impact on flagellar beating, where jacks had a higher bend length and bend angle than hooknoses. Activation media also impacted the pattern of flagellar parameters, such that beat frequency, wave velocity and bend angle declined, while wave amplitude of flagella increased when ovarian fluid was incorporated into activation media. Furthermore, we found that sperm from jacks swam faster than those from hooknoses and required less hydrodynamic power output to propel themselves in river water and ovarian fluid. Jack sperm were also more efficient at swimming than hooknose sperm, and propulsive efficiency increased when cells were activated in ovarian fluid. The results demonstrate that sperm biomechanics may be driving divergence in competitive reproductive success between ARTs.
Assuntos
Ovário/fisiologia , Salmão/fisiologia , Motilidade dos Espermatozoides , Cauda do Espermatozoide/fisiologia , Animais , Fenômenos Biomecânicos , Feminino , Masculino , Ontário , Reprodução/fisiologiaRESUMO
Paternal, compared to maternal, contributions were believed to have only a limited influence on embryonic development and larval fitness traits in fishes. Therefore, the perspective of male influence on early life history traits has come under scrutiny. This study was conducted to determine parental effects on the rate of eyed embryos of Ide Leuciscus idus and Northern pike Esox lucius. Five sires and five dams from each species were crossed using a quantitative genetic breeding design and the resulting 25 sib groups of each species were reared to the embryonic eyed stage. We then partition variation in embryonic phenotypic performance to maternal, paternal, and parental interactions using the Restricted Maximum Likelihood (REML) model. Results showed that paternal, maternal, and the paternal×maternal interaction terms were highly significant for both species; clearly demonstrating that certain family combinations were more compatible than others. Paternal effects explained 20.24% of the total variance, which was 2-fold higher than the maternal effects (10.73%) in Ide, while paternal effects explained 18.9% of the total variance, which was 15-fold higher than the maternal effects (1.3%) in Northern pike. Together, these results indicate that male effects are of major importance during embryonic development for these species. Furthermore, this study demonstrates that genetic compatibility between sires and dams plays an important role and needs to be taken into consideration for reproduction of these and likely other economically important fish species.
Assuntos
Desenvolvimento Embrionário , Peixes/embriologia , Animais , Cruzamento , Cruzamentos Genéticos , Feminino , Larva/crescimento & desenvolvimento , Masculino , Fenótipo , Reprodução/fisiologia , Especificidade da EspécieRESUMO
Chinook salmon (Oncorhynchus tshawytscha) exhibit extreme differences in coloration of skin, eggs and flesh due to genetic polymorphisms affecting carotenoid deposition, where colour can range from white to bright red. A sympatric population of red and white Chinook salmon occurs in the Quesnel River, British Columbia, where frequencies of each phenotype are relatively equal. In our study, we examined evolutionary mechanisms responsible for the maintenance of the morphs, where we first tested whether morphs were reproductively isolated using microsatellite genotyping, and second, using breeding trials in seminatural spawning channels, we tested whether colour assortative mate choice could be operating to maintain the polymorphism in nature. Next, given extreme difference in carotenoid assimilation and the importance of carotenoids to immune function, we examined mate choice and selection between colour morphs at immune genes (major histocompatibility complex genes: MHC I-A1 and MHC II-B1). In our study, red and white individuals were found to interbreed, and under seminatural conditions, some degree of colour assortative mate choice (71% of matings) was observed. We found significant genetic differences at both MHC genes between morphs, but no evidence of MHC II-B1-based mate choice. White individuals were more heterozygous at MHC II-B1 compared with red individuals, and morphs showed significant allele frequency differences at MHC I-A1. Although colour assortative mate choice is likely not a primary mechanism maintaining the polymorphisms in the population, our results suggest that selection is operating differentially at immune genes in red and white Chinook salmon, possibly due to differences in carotenoid utilization.
Assuntos
Genes MHC da Classe II , Genes MHC Classe I , Preferência de Acasalamento Animal , Polimorfismo Genético , Salmão/genética , Animais , Cruzamento , Colúmbia Britânica , Carotenoides , Feminino , Genética Populacional , Genótipo , Masculino , Repetições de Microssatélites , Pigmentação/genética , Salmão/imunologia , Análise de Sequência de DNARESUMO
Chinook salmon, Oncorhynchus tshawytscha, exhibit alternative reproductive tactics (ARTs) where males exist in two phenotypes: large "hooknose" males and smaller "jacks" that reach sexual maturity after only 1 year in seawater. The mechanisms that determine "jacking rate"-the rate at which males precociously sexually mature-are known to involve both genetics and differential growth rates, where individuals that become jacks exhibit higher growth earlier in life. The additive genetic components have been studied and it is known that jack sires produce significantly more jack offspring than hooknose sires, and vice versa. The current study was the first to investigate both additive and non-additive genetic components underlying jacking through the use of a full-factorial breeding design using all hooknose sires. The effect of dams and sires descendant from a marker-assisted broodstock program that identified "high performance" and "low performance" lines using growth- and survival-related gene markers was also studied. Finally, the relative growth of jack, hooknose, and female offspring was examined. No significant dam, sire, or interaction effects were observed in this study, and the maternal, additive, and non-additive components underlying jacking were small. Differences in jacking rates in this study were determined by dam performance line, where dams that originated from the low performance line produced significantly more jacks. Jack offspring in this study had a significantly larger body size than both hooknose males and females starting 1 year post-fertilization. This study provides novel information regarding the genetic architecture underlying ARTs in Chinook salmon that could have implications for the aquaculture industry, where jacks are not favoured due to their small body size and poor flesh quality.
Assuntos
Variação Genética , Reprodução/genética , Salmão/genética , Animais , Tamanho Corporal , Peso Corporal , Feminino , Masculino , FenótipoRESUMO
The dengue virus (DENV) envelope protein domain 3 (ED3) is the target of potent virus neutralizing antibodies. The DENV-2 ED3 contains adjacent type-specific and DENV complex-reactive antigenic sites that are composed of a small number of residues that were previously demonstrated to be critical for antibody binding. Site-directed mutagenesis of a DENV-2 16681 infectious clone was used to mutate critical residues in the DENV-2 type-specific (K305A and P384A) and DENV complex-reactive (K310A) antigenic sites. The K305A mutant virus multiplied like the parent virus in mosquito and mammalian cells, as did the P384A mutant virus, which required a compensatory mutation (G330D) for viability. However, the K310A mutant virus could not be recovered. The DENV-2 type-specific critical residue mutations K305A and P384A+G330D reduced the ability of DENV-2 type-specific, but not DENV complex-reactive, mAbs to neutralize virus infectivity and this was directly correlated with mAb binding affinity to the rED3 mutants.
Assuntos
Vírus da Dengue/imunologia , Epitopos/imunologia , Proteínas do Envelope Viral/imunologia , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Análise Mutacional de DNA , Vírus da Dengue/genética , Epitopos/genética , Viabilidade Microbiana , Modelos Moleculares , Mutagênese Sítio-Dirigida , Conformação Proteica , Proteínas do Envelope Viral/genética , Replicação ViralRESUMO
Outbreeding, mating between genetically divergent individuals, may result in negative fitness consequences for offspring via outbreeding depression. Outbreeding effects are of notable concern in salmonid research as outbreeding can have major implications for salmon aquaculture and conservation management. We therefore quantified outbreeding effects in two generations (F1 hybrids and F2 backcrossed hybrids) of Chinook salmon (Oncorhynchus tshawytscha) derived from captively-reared purebred lines that had been selectively bred for differential performance based on disease resistance and growth rate. Parental lines were crossed in 2009 to create purebred and reciprocal hybrid crosses (n = 53 families), and in 2010 parental and hybrid crosses were crossed to create purebred and backcrossed hybrid crosses (n = 66 families). Although we found significant genetic divergence between the parental lines (FST = 0.130), reciprocal F1 hybrids showed no evidence of outbreeding depression (hybrid breakdown) or favorable heterosis for weight, length, condition or survival. The F2 backcrossed hybrids showed no outbreeding depression for a suite of fitness related traits measured from egg to sexually mature adult life stages. Our study contributes to the current knowledge of outbreeding effects in salmonids and supports the need for more research to better comprehend the mechanisms driving outbreeding depression.
Assuntos
Hibridização Genética , Salmão/genética , Animais , Vigor Híbrido , EndogamiaRESUMO
Reproductive potential of fish stocks is critically dependent on sperm performance in an aquatic environment. The aim of this study is to test hypotheses, which govern the initiation of sperm motility and swimming performance, through physiological functions of osmolality and Ca(2+) ion, in a threatened species of freshwater fish, the redside dace, Clinostomus elongatus. Spermatozoa motility was activated in either ionic or non-ionic media spanning a range of osmolalities. The role of Ca(2+) channels on induction of spermatozoa motility and velocity was experimentally investigated by diluting sperm in media that contain various Ca(2+) channel blockers. Results show that initiation of spermatozoa motility is a hypo-osmolality dependent mechanism. Inhibitors for L-type Ca(2+) channels partially prohibited initiation of spermatozoa motility, while velocity was significantly reduced in both L-type and T-type Ca(2+) channel blockers. Examination using W-7, an inhibitor for Ca(2+)-dependent calmodulin, showed significant decreases in spermatozoa motility and velocity. Involvement for Ca(2+) in axonemal beating was confirmed by significant increases in velocity after adding Ca(2+) into the activation media, while motility remained unchanged in Ca(2+) supplemented activation media. Together, these findings suggest the involvement of Ca(2+) in hypo-osmolality-dependent initiation of spermatozoa motility mediated by activation of Ca(2+) binding protein in the axoneme of a freshwater fish sperm. Blocking Ca(2+) exchange through L- or T-type Ca(2+) channel influences flagellar beating force and leads to decrease in spermatozoa velocity.
Assuntos
Cálcio/farmacologia , Cyprinidae/fisiologia , Motilidade dos Espermatozoides/efeitos dos fármacos , Natação/fisiologia , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Íons , Cinética , Masculino , Concentração Osmolar , RiosRESUMO
Aquatic contaminants, specifically polychlorinated biphenyls (PCBs), a class of persistent organic contaminants, have been associated with sublethal effects on reproduction in fishes. Female brown bullhead (Ameiurus nebulosus) were used to assess variation in reproductive traits across eight populations differing in sediment sum PCB concentrations in the Lower Great Lakes region. Differences in maternal carotenoid allocation patterns among these populations were also examined. No significant associations were found between sediment sum PCB concentrations corrected for organic content (OC) and reproductive traits. However, egg diameter was negatively correlated with sediment PCB concentrations not corrected for OC, suggesting that observed relationships between sediment sum PCB concentrations and reproductive traits are driven by classes of environmental contaminants whose bioavailability are not predicted by OC, such as metals. An unexpected positive relationship was also found between egg carotenoid concentrations and sediment PCB concentrations. This positive relationship was explained by the maternal allocation of carotenoids based on a negative correlation between female muscle and egg carotenoid concentrations, where females from less contaminated locations had lower egg and greater muscle carotenoid concentrations than those from more contaminated locations. The results of this study identify sublethal effects of environmental contaminants on reproductive life-history traits in female brown bullhead, and investigations of adaptive mechanisms underlying this variation are warranted.
Assuntos
Sedimentos Geológicos/química , Ictaluridae/fisiologia , Bifenilos Policlorados/análise , Reprodução/efeitos dos fármacos , Poluentes Químicos da Água/análise , Animais , Monitoramento Ambiental , Feminino , Óvulo/efeitos dos fármacos , Bifenilos Policlorados/toxicidade , Poluentes Químicos da Água/toxicidadeRESUMO
A blood-based integrated classifier (IC) has been clinically validated to improve accuracy in assessing probability of cancer risk (pCA) for pulmonary nodules (PN). This study evaluated the clinical utility of this biomarker for its ability to reduce invasive procedures in patients with pre-test pCA ≤ 50%. This was a propensity score matching (PSM) cohort study comparing patients in the ORACLE prospective, multicenter, observational registry to control patients treated with usual care. This study enrolled patients meeting the intended use criteria for IC testing: pCA ≤ 50%, age ≥40 years, nodule diameter 8-30 mm, and no history of lung cancer and/or active cancer (except for non-melanomatous skin cancer) within 5 years. The primary aim of this study was to evaluate invasive procedure use on benign PNs of registry patients as compared to control patients. A total of 280 IC tested, and 278 control patients met eligibility and analysis criteria and 197 were in each group after PSM (IC and control groups). Patients in the IC group were 74% less likely to undergo an invasive procedure as compared to the control group (absolute difference 14%, p <0.001) indicating that for every 7 patients tested, one unnecessary invasive procedure was avoided. Invasive procedure reduction corresponded to a reduction in risk classification, with 71 patients (36%) in the IC group classified as low risk (pCA < 5%). The proportion of IC group patients with malignant PNs sent to surveillance were not statistically different than the control group, 7.5% vs 3.5% for the IC vs. control groups, respectively (absolute difference 3.91%, p 0.075). The IC for patients with a newly discovered PN has demonstrated valuable clinical utility in a real-world setting. Use of this biomarker can change physicians' practice and reduce invasive procedures in patients with benign pulmonary nodules. Trial registration: Clinical trial registration: ClinicalTrials.gov NCT03766958.
Assuntos
Neoplasias Pulmonares , Nódulos Pulmonares Múltiplos , Humanos , Adulto , Estudos de Coortes , Estudos Prospectivos , Neoplasias Pulmonares/diagnóstico , Grupos Controle , Nódulos Pulmonares Múltiplos/diagnóstico por imagem , Pontuação de PropensãoRESUMO
The maternal provisioning of yolk to eggs transfers significant quantities of persistent organic pollutants (POPs). As yolk utilization progresses via metabolic activity, there is a potential to realize further increases in POP concentrations if yolk lipids are depleted at a faster rate than POPs, a condition referred to as bioamplification. This study investigated the bioamplification of POPs in Chinook salmon ( Oncorhynchus tshawytscha ) eggs and larvae. Chinook eggs were sampled from the Credit River, ON, Canada, and brought to an aquaculture facility where they were fertilized, incubated, and maintained posthatch until maternally derived lipid reserves became depleted (approximately 168 days). The loss of chemicals having an octanol-water partition coefficient (log K(OW)) greater than 5.8 was slow to negligible from days 0-135. However, during the increase in water temperatures in early spring, K(OW)-dependent elimination of POPs was observed. Bioamplification was maximized for the highest log K(OW) POPs, with an approximate 5-fold increase in lipid equivalents concentrations in 168 day old larvae as compared to newly fertilized eggs. This study demonstrates that later yolk-sac Chinook larvae (before exogenous feeding) are exposed to higher lipid equivalents POP concentrations than predicted by maternal deposition, which could lead to underestimates in the toxicity of critical life stages.