The aim of our study was to determine the antioxidant activities, cytotoxicity and proliferative properties in Stevia rebaudiana leaves and stems. Leaves extracts exhibited a higher antioxidant activity than stems extract, through oxygen radical absorbance capacity (ORAC) and cellular antioxidant activity (CAA) assays. Stevioside and rebaudioside A, the main sweetening metabolites in stevia leaves, exhibited a low ORAC value in comparison with plant extracts, while did not elicit any CAA. Stevia rebaudiana did not exhibit toxicity against HepG2 (hepatocellular carcinoma) human cells. No proliferative nor catalase modulations were observed in cells treated with such extracts. Our findings support the promising role of stevia that, apart from its sweetness, can act as a source of antioxidants, even at the intracellular level. This activity makes S. rebaudiana crude extract an interesting resource of natural sweetness with antioxidant properties which may find numerous applications in foods and nutritional supplements industries.

Pacific halibut collected in the Aleutian Islands, Bering Sea and Gulf of Alaska were used to test the hypothesis of genetic panmixia for this species in Alaskan marine waters. Nine microsatellite loci and sequence data from the mitochondrial (mtDNA) control region were analyzed. Eighteen unique mtDNA haplotypes were found with no evidence of geographic population structure. Using nine microsatellite loci, significant heterogeneity was detected between Aleutian Island Pacific halibut and fish from the other two regions (F ST range = 0.007-0.008). Significant F ST values represent the first genetic evidence of divergent groups of halibut in the central and western Aleutian Archipelago. No significant genetic differences were found between Pacific halibut in the Gulf of Alaska and the Bering Sea leading to questions about factors contributing to separation of Aleutian halibut. Previous studies have reported Aleutian oceanographic conditions at deep inter-island passes leading to ecological discontinuity and unique community structure east and west of Aleutian passes. Aleutian Pacific halibut genetic structure may result from oceanographic transport mechanisms acting as partial barriers to gene flow with fish from other Alaskan waters.

A total of 452 largemouth bass Micropterus salmoides (mostly adults) from 78 reservoirs, lakes, rivers, and state fish hatcheries in

We investigated the genetic diversity of steelhead Oncorhynchus mykiss in 74 wild populations and 5 hatchery stocks in Idaho's Snake River basin at the drainage, watershed, and population spatial scales using 11 microsatellite loci. We found significant genetic diversity at multiple spatial scales. Analysis of molecular variance showed that genetic diversity was greater among watersheds within drainages (3.66%) than among drainages (1.97%). Over 94% of the genetic diversity found in the Clearwater, Salmon, and Snake River drainages occurred within individual populations. Estimated effective population sizes ranged from 213 to 486.6 at the drainage scale, from 81.2 to 610.4 at the watershed scale, and from 8.4 to 4,845 at the population scale. The Middle Fork Salmon, South Fork Salmon, Lochsa, and Selway rivers—watersheds managed for wild fish—formed distinct groups in our consensus neighbor‐joining (NJ) trees. At the watershed scale our analyses support differentiation of all hatchery and wild stocks. However, this was not the case for analyses at the population scale, where 236 FST pairwise comparisons out of 3,081 (wild and hatchery) were not significantly different. The distribution of genetic diversity across the landscape does not appear to be organized by the A run or B run management designations for anadromous steelhead. The Dworshak hatchery stock was significantly different from all but one population (O'Hara Creek, Selway River) in pairwise FST comparisons and grouped with other Clearwater River drainage populations in our NJ trees. The Oxbow, Sawtooth, and Pahsimeroi hatchery stocks were indistinguishable from each other based on FST analysis. Currently, this study represents the most comprehensive evaluation of genetic diversity in Idaho's steelhead populations across multiple scales with different management histories.

Molecular genetic methods were used to quantify natural hybridization between rainbow trout Oncorhynchus mykiss or steelhead (anadromous rainbow trout) and coastal cutthroat trout O. clarkii clarkii collected in the Copper River delta, Southeast Alaska. Eleven locations were sampled to determine the extent of hybridization and the distribution of hybrids. Four diagnostic nuclear microsatellite loci and four species‐specific simple sequence repeat markers were used in combination with restriction fragment length polymorphism analyses of NADH dehydrogenase 5/6 (ND5/6) mitochondrial DNA (mtDNA) to investigate the genetic structure of trout from both species and identify putative interspecific hybrids. Hybrids were found in 7 of the 11 streams sampled in the Copper River delta, the extent of hybridization across all streams varying from 0% to 58%. Hybrid trout distribution appeared to be nonrandom, most individuals of mixed taxonomic ancestry being detected in streams containing rainbow trout rather than in streams containing coastal cutthroat trout. Genotypic disequilibrium was observed among microsatellite loci in populations with high levels of hybridization. We found no significant correlation between unique stream channel process groups and the number of hybrid fish sampled. Eighty‐eight percent of fish identified as first‐generation hybrids (F1) in two populations contained coastal cutthroat trout mtDNA, suggesting directionality in hybridization. However, dominance of coastal cutthroat trout mtDNA was not observed at a third location containing F1 hybrids, indicating that interspecific mating behavior varied among locations. Backcrossed individuals were found in drainages lacking F1 hybrids and in populations previously thought to contain a single species. The extent and distribution of backcrossed individuals suggested that at least some hybrids are reproductively viable and backcrossed hybrid offspring move throughout the system.