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21.
Synopsis Numbers of offspring produced by genetically marked male and female rainbow trout,Oncorhynchus mykiss were determined by an electrophoretic analysis of 1713 progeny from crosses produced by premixing gametes from different
parents prior to insemination and associated full- and half-sib controls. We examined whether male potency, defined as the
ability of males to sire progeny when their semen is pooled with that of other males, is affected by interaction with female
gametes, concentration of sperm cells and the timing of semen application. Male potency differed significantly and was not
affected by which of two females was involved in either of two sets of experiments. The differential between males decreased
significantly when sperm concentrations were equalized. The first male sired over 75% of progeny when semen from four males
was added sequentially to ova at 30 s intervals in each of two experiments. The lack of significant deviations of marker genotypes
from expected Mendelian segregation in full-sib families suggested that there was no differential survival of progeny with
specific marker genotypes. Furthermore, there was no correspondence between the survival of progeny of specific males in control
crosses and the number of progeny sired in matings where sperm was premixed prior to insemination. Thus. variation in male
reproductive success appeared the result of differential fertilization rates. 相似文献
22.
Synopsis Several years ago, we used a bioenergetics model to evaluate the impact of increasing salmonid stocking on the highly variable alewife forage base in Lake Michigan. At that time, we forecast an alewife population decline and the following system-wide effects: increased abundances of large zooplankton, decreased salmonid growth rates, increased diet breadth of salmonids, niche shifts among competitors of the alewife, increased alewife growth rates and increased densities of fishes suppressed by alewife. Alewives have continued to decline steadily since 1981 and are now reduced to a density similar to early outbreak levels in the early 1960s. Recent reports on fish growth rates, zooplankton size and fish community structure support our projections regarding system-wide responses to the alewife decline. 相似文献
23.
Kurt D. Fausch 《Biological invasions》2008,10(5):685-701
A paradox of invasion biology is that even though native species are locally adapted to environmental conditions, nonnative
species without this advantage often invade. Ecologists have advanced four main theories to explain why invaders are successful
in some places and not others: biotic resistance, environmental resistance, human disturbance, and natural enemies. However,
none of these theories alone can account for invasions by two trout species outside their native ranges in North America.
Brook trout (Salvelinus fontinalis) are able to displace native cutthroat trout (Oncorhynchus clarkii) in the inland western US, but are themselves displaced by nonnative rainbow trout (O. mykiss) in the southeastern US. An alternative hypothesis is that an interaction among zoogeography, evolutionary history, and environmental
resistance from the natural flow regimes can account for this paradox. The nonnative species invade successfully at the southern
edge of the ranges of the native species, which are farthest from their ancestral origins. Due to their evolutionary history,
the native species are poorly adapted to the natural disturbance regime at the southern limit of their ranges, but the nonnative
species are preadapted by chance due to theirs. This alternative hypothesis about the interaction between the historical contingency
of evolution and environmental resistance should be more widely tested, to inform both invasion biology and the conservation
of native trout. 相似文献
24.
The spermatozoa of most fish species are immotile in the testis and seminal plasma. Therefore, motility is induced after the spermatozoa are released into the aqueous environment during natural reproduction or into the diluent during artificial reproduction. There are clear relationships between seminal plasma composition and osmolality and the duration of fish sperm motility. Various parameters such as ion concentrations (K+, Na+, and Ca2+), osmotic pressure, pH, temperature and dilution rate affect motility. In the present paper, we review the roles of these ions on sperm motility in Salmonidae, Cyprinidae, Acipenseridae and marine fishes, and their relationship with seminal plasma composition. Results in the literature show that: 1. K+ is a key ion controlling sperm motility in Salmonidae and Acipenseridae in combination with osmotic pressure; this control is more simple in other fish species: sperm motility is prevented when the osmotic pressure is high (Cyprinidae) or low (marine fishes) compared to that of the seminal fluid. 2. Cations (mostly divalent, such as Ca2+) are antagonistic with the inhibitory effect of K+ on sperm motility. 3. In many species, Ca2+ influx and K+ or Na+ efflux through specific ionic channels change the membrane potential and eventually lead to an increase in cAMP concentration in the cell, which constitutes the initiation signal for sperm motility in Salmonidae. 4. Media that are hyper- and hypo-osmotic relative to seminal fluid trigger sperm motility in marine and freshwater fishes, respectively. 5. The motility of fish spermatozoa is controlled through their sensitivity to osmolality and ion concentrations. This phenomenon is related to ionic channel activities in the membrane and governs the motility mechanisms of axonemes. 相似文献
25.
26.
Haidle L Janssen JE Gharbi K Moghadam HK Ferguson MM Danzmann RG 《Marine biotechnology (New York, N.Y.)》2008,10(5):579-592
To identify quantitative trait loci (QTL) influencing early maturation (EM) in rainbow trout (Oncorhynchus mykiss), a genome scan was performed using 100 microsatellite loci across 29 linkage groups. Six inter-strain paternal half-sib families using three inter-strain F(1) brothers (approximately 50 progeny in each family) derived from two strains that differ in the propensity for EM were used in the study. Alleles derived from both parental sources were observed to contribute to the expression of EM in the progeny of the brothers. Four genome-wide significant QTL regions (i.e., RT-8, -17, -24, and -30) were observed. EM QTL detected on RT-8 and -24 demonstrated significant and suggestive QTL effects in both male and female progeny. Furthermore, within both male and female full-sib groupings, QTL on RT-8 and -24 were detected in two or more of the five parents used. Significant genome-wide and several strong chromosome-wide QTL for EM localized to different regions in males and females, suggesting some sex-specific control. Namely, QTL detected on RT-13, -15, -21, and -30 were associated with EM only in females, and those on RT-3, -17, and -19 were associated with EM only in males. Within the QTL regions identified, a comparison of syntenic EST markers from the rainbow trout linkage map with the zebrafish (Danio rerio) genome identified several putative candidate genes that may influence EM. 相似文献
27.
Leef MJ Harris JO Hill J Powell MD 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2005,175(7):523-532
The cardiovascular effects of amoebic gill disease (AGD) were investigated immediately following surgery in three salmonid species; Atlantic salmon (Salmo salar L.), brown trout (Salmo trutta L.) and rainbow trout (Oncorhynchus mykiss Walbaum). Fish, both naïve (control) and infected (AGD-affected) of each species, were fitted with dorsal aorta catheters and cardiac flow probes. Cardiac output and dorsal aortic pressures were then continuously measured over a 6-h period following surgery. Results showed that Atlantic salmon, brown trout and rainbow trout displayed similar dorsal aortic pressure, cardiac output, and systemic vascular resistance (mean dorsal aotic pressure divided by cardiac output) values. However, the only significant differences relating to disease status i.e. infected or control, were found in Atlantic salmon. Although no significant differences were seen in dorsal aortic pressure values, AGD-affected salmon displayed significantly elevated systemic vascular resistance at 4 and 6 h post surgery. Cardiac output was also approximately 35% lower in AGD-affected salmon compared to the non-affected control counterparts. These results comparatively examine cardiac function in response to AGD across three salmonid species and highlight species-specific cardiovascular responses that occur in association with disease. It is suggested that the apparent cardiac dysfunction seen in AGD-affected Atlantic salmon could, under stressful conditions, become exacerbated. Cardiac failure is therefore suggested to be a possible physiological mechanism by which AGD causes or contributes to mortality in Atlantic salmon. 相似文献
28.
Synopsis The age structures of brook charr (Salvelinus fontinalis) and ouananiche (Salmo salar) stocks inhabiting a large rapid the river Méo, tributary to the Caniapiscau River were used to compare population stability
and production of these species in north central Quebec. The brook chart stock was stable whereas ouananiche showed considerable
variation in year class strength. Stock estimates were not significantly different for the two species although the brook
charr estimate was 1.5 that of the ouananiche. Production estimates differed by a greater margin because of different growth
patterns. Brook chair production was estimated at 19.4 kg ha−1 yr−1. Above age 2+ it was 11.4 kg ha−1 yr−1 which compares with 4.8 kg ha−1 yr−1 for the same age groups of ouananiche. 相似文献
29.
Pakkasmaa S Penttinen OP Piironen J 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2006,176(5):387-391
The metabolic rate (specific heat output) of individual eyed-stage eggs of Arctic charr Salvelinus alpinus (Linnaeus, 1758) originating from different families was measured with direct microcalorimetry. Metabolic rates varied between 2.3–7.9 μW ind−1 and 0.06–0.22 μW mg−1. Absolute heat output was unrelated to egg size, but size-scaled or specific heat output was negatively correlated with egg size, measured as diameter, dry mass or fresh mass. Metabolic rates varied significantly between families, suggesting that genetic and/or maternal effects affect embryonic metabolism in Arctic charr. Heat output increased almost linearly from 3.4 to 16.7 μW ind−1 (0.09–0.67 μW mg−1) during the embryonic development. Although the metabolic rate varied between the families and egg metabolic rate increased during development, there was an unexpected disconnect between metabolic rate and hatching time. 相似文献
30.
D. Chourrout 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1986,72(5):627-632
Summary Experiments, supported by extensive karyology, were carried out to evaluate the different techniques used for chromosome manipulation in rainbow trout. Eggs, when subjected to early heat shocks, changed from haploidy to diploidy and from diploidy to triploidy. In this respect heat shocks differ from pressure shocks which induce gradual transitions between successive ploidy levels. Sperm treatment with dimethylsulphate yields haploid embryos containing residual sperm chromatin fragments, in contrast to treatment with ultraviolet rays. 相似文献