Antagonistic Interactions and Biofilm Forming Capabilities Among Bacterial Strains Isolated from the Egg Surfaces of Lake Sturgeon (Acipenser fulvescens).

Characterization of interactions within a host-associated microbiome can help elucidate the mechanisms of microbial community formation on hosts and can be used to identify potential probiotics that protect hosts from pathogens. Microbes employ various modes of antagonism when interacting with other members of the community. The formation of biofilm by some strains can be a defense against antimicrobial compounds produced by other taxa. We characterized the magnitude of antagonistic interactions and biofilm formation of 25 phylogenetically diverse taxa that are representative of isolates obtained from egg surfaces of the threatened fish species lake sturgeon (Acipenser fulvescens) at two ecologically relevant temperature regimes. Eight isolates exhibited aggression to at least one other isolate. Pseudomonas sp. C22 was found to be the most aggressive strain, while Flavobacterium spp. were found to be one of the least aggressive and the most susceptible genera. Temperature affected the prevalence and intensity of antagonism. The aggressive strains identified also inhibited growth of known fish pathogens. Biofilm formations were observed for nine isolates and were dependent on temperature and growth medium. The most aggressive of the isolates disrupted biofilm formation of two well-characterized isolates but enhanced biofilm formation of a fish pathogen. Our results revealed the complex nature of interactions among members of an egg associated microbial community yet underscored the potential of specific microbial populations as host probiotics.

Genetic assessment of the effects of streamscape succession on coho salmon Oncorhynchus kisutch colonization in recently deglaciated streams.

Measures of genetic diversity within and among populations and historical geomorphological data on stream landscapes were used in model simulations based on approximate Bayesian computation (ABC) to examine hypotheses of the relative importance of stream features (geomorphology and age) associated with colonization events and gene flow for coho salmon Oncorhynchus kisutch breeding in recently deglaciated streams (50-240 years b.p.) in Glacier Bay National Park (GBNP), Alaska. Population estimates of genetic diversity including heterozygosity and allelic richness declined significantly and monotonically from the oldest and largest to youngest and smallest GBNP streams. Interpopulation variance in allele frequency increased with increasing distance between streams (r = 0·435, P < 0·01) and was inversely related to stream age (r = -0·281, P < 0·01). The most supported model of colonization involved ongoing or recent (<10 generations before sampling) colonization originating from large populations outside Glacier Bay proper into all other GBNP streams sampled. Results here show that sustained gene flow from large source populations is important to recently established O. kisutch metapopulations. Studies that document how genetic and demographic characteristics of newly founded populations vary associated with successional changes in stream habitat are of particular importance to and have significant implications for, restoration of declining or repatriation of extirpated populations in other regions of the species' native range.

Regulation of DCIS to invasive breast cancer progression by Singleminded-2s (SIM2s).

Singleminded-2s (SIM2s) is a member of the bHLH/PAS family of transcription factors and a key regulator of mammary epithelial cell differentiation. SIM2s is highly expressed in mammary epithelial cells and downregulated in human breast cancer. Loss of Sim2s causes aberrant mouse mammary ductal development, with features suggestive of malignant transformation, whereas overexpression of SIM2s promotes precocious alveolar differentiation in nulliparous mouse mammary glands, suggesting that SIM2s is required for establishing and enhancing mammary gland differentiation. To test the hypothesis that SIM2s regulates tumor cell differentiation, we analyzed SIM2s expression in human primary breast ductal carcinoma in situ (DCIS) samples and found that SIM2s is lost with progression from DCIS to invasive ductal cancer (IDC). Using a MCF10DCIS.COM progression model, we have shown that SIM2s expression is decreased in MCF10DCIS.COM cells compared with MCF10A cells, and reestablishment of SIM2s in MCF10DCIS.COM cells significantly inhibits growth and invasion both in vitro and in vivo. Analysis of SIM2s-MCF10DCIS.com tumors showed that SIM2s promoted a more differentiated tumor phenotype including the expression of a broad range of luminal markers (CSN2 (ß-casein), CDH1 (E-cadherin), and KER18 (keratin-18)) and suppressed genes associated with stem cell maintenance and a basal phenotype (SMO (smoothened), p63, SLUG (snail-2), KER14 (keratin-14) and VIM (vimentin)). Furthermore, loss of SIM2s expression in MCF10DCIS.COM xenografts resulted in a more invasive phenotype and increased lung metastasis likely due to an increase in Hedgehog signaling and matrix metalloproteinase expression. Together, these exciting new data support a role for SIM2s in promoting human breast tumor differentiation and maintaining epithelial integrity.

Environmental and lunar cues are predictive of the timing of river entry and spawning-site arrival in lake sturgeon Acipenser fulvescens.

The associations were quantified between daily and interannual variation in the timing of a closed population of lake sturgeon Acipenser fulvescens migration and arrival at spawning sites with stream environmental and lunar covariates. Spawning data were gathered from 1262 fish in Black Lake, Michigan 2001 to 2008 and by video monitoring 2000 to 2002. Sex-specific variation in responses to external cues was also tested. Results showed that a greater number of individuals initiated migration from lake to riverine habitats at dawn and dusk relative to other times of the day. Current and lagged effects of water temperature and river discharge, and periods in the lunar cycle were important variables in models quantifying movements into the river and timing of adult arrival at spawning sites. Different suites of covariates were predictive of A. fulverscens responses during different periods of the spawning season. The timing of initiation of migration and spawning, and the importance of covariates to the timing of these events, did not differ between sexes. Stream flow and temperature covaried with other variables including day length and the lunar cycle. Anthropogenic disruption of relationships among variables may mean that environmental cues may no longer reliably convey information for Acipenseriformes and other migratory fishes.

Bacterial infections of Chinook salmon, Oncorhynchus tshawytscha (Walbaum), returning to gamete collecting weirs in Michigan.

Herein, we describe the prevalence of bacterial infections in Chinook salmon, Oncorhynchus tshawytscha (Walbaum), returning to spawn in two tributaries within the Lake Michigan watershed. Ten bacterial genera, including Renibacterium, Aeromonas, Carnobacterium, Serratia, Proteus, Pseudomonas, Hafnia, Salmonella, Shewanella and Morganella, were detected in the kidneys of Chinook salmon (n = 480) using culture, serological and molecular analyses. Among these, Aeromonas salmonicida was detected at a prevalence of ∼15%. Analyses revealed significant interactions between location/time of collection and gender for these infections, whereby overall infection prevalence increased greatly later in the spawning run and was significantly higher in females. Renibacterium salmoninarum was detected in fish kidneys at an overall prevalence of >25%. Logistic regression analyses revealed that R. salmoninarum prevalence differed significantly by location/time of collection and gender, with a higher likelihood of infection later in the spawning season and in females vs. males. Chi-square analyses quantifying non-independence of infection by multiple pathogens revealed a significant association between R. salmoninarum and motile aeromonad infections. Additionally, greater numbers of fish were found to be co-infected by multiple bacterial species than would be expected by chance alone. The findings of this study suggest a potential synergism between bacteria infecting spawning Chinook salmon.

Patterns of invasion and colonization of the sea lamprey (Petromyzon marinus) in North America as revealed by microsatellite genotypes.

Invasions by exotic organisms have had devastating affects on aquatic ecosystems, both ecologically and economically. One striking example of a successful invader that has dramatically affected fish community structure in freshwater lakes of North America is the sea lamprey (Petromyzon marinus). We used eight microsatellite loci and multiple analytical techniques to examine competing hypotheses concerning the origins and colonization history of sea lamprey (n = 741). Analyses were based on replicated invasive populations from Lakes Erie, Huron, Michigan, and Superior, populations of unknown origins from Lakes Ontario, Champlain, and Cayuga, and populations of anadromous putative progenitor populations in North America and Europe. Populations in recently colonized lakes were each established by few colonists through a series of genetic bottlenecks which resulted in lower allelic diversity in more recently established populations. The spatial genetic structure of invasive populations differed from that of native populations on the Atlantic coast, reflecting founder events and connectivity of invaded habitats. Anadromous populations were found to be panmictic (theta(P) = 0.002; 95% CI = -0.003-0.006; P > 0.05). In contrast, there was significant genetic differentiation between populations in the lower and upper Great Lakes (theta(P) = 0.007; P < 0.05; 95% CI = 0.003-0.009). Populations in Lakes Ontario, Champlain, and Cayuga are native. Alternative models that describe different routes and timing of colonization of freshwater habitats were examined using coalescent-based analyses, and demonstrated that populations likely originated from natural migrations via the St Lawrence River.

Chronic stress-induced effects of corticosterone on brain: direct and indirect.

Acutely, glucocorticoids act to inhibit stress-induced corticotrophin-releasing factor (CRF) and adrenocorticotrophic hormone (ACTH) secretion through their actions in brain and anterior pituitary (canonical feedback). With chronic stress, glucocorticoid feedback inhibition of ACTH secretion changes markedly. Chronically stressed rats characteristically exhibit facilitated ACTH responses to acute, novel stressors. Moreover, in adrenalectomized rats in which corticosterone was replaced, steroid concentrations in the higher range are required for facilitation of ACTH responses to occur after chronic stress or diabetes. Infusion of corticosterone intracerebroventricularly into adrenalectomized rats increases basal ACTH, tends to increase CRF, and allows facilitation of ACTH responses to repeated restraint. Therefore, with chronic stressors, corticosterone seems to act in brain in an excitatory rather than an inhibitory fashion. We believe, under conditions of chronic stress, that there is an indirect glucocorticoid feedback that is mediated through the effects of the steroid +/- insulin on metabolism. Increased energy stores feedback on brain to inhibit hypothalamic CRF and decrease the expression of dopamine-beta-hydroxylase in the locus coeruleus. These changes would be expected to decrease the level of discomfort and anxiety induced by chronic stress. Moreover, central neural actions of glucocorticoids abet the peripheral effects of the steroids by increasing the salience and ingestion of pleasurable foods.

Genetic variation over space and time: analyses of extinct and remnant lake trout populations in the Upper Great Lakes.

Lake trout (Salvelinus namaycush) in the upper Laurentian Great Lakes of North America experienced striking reductions in abundance and distribution during the mid-twentieth century. Complete collapse of populations was documented for Lake Michigan, and a few remnant populations remained only in lakes Huron and Superior. Using DNA obtained from historical scale collections, we analysed patterns of genetic diversity at five microsatellite loci from archived historical samples representing 15 populations (range 1940-1959) and from three contemporary remnant populations across lakes Huron and Superior (total n = 893). Demographic declines in abundance and the extirpation of native lake trout populations during the past 40 years have resulted in the loss of genetic diversity between lakes owing to extirpation of Lake Michigan populations and a temporal trend for reduction in allelic richness in the populations of lakes Superior and Huron. Naturally reproducing populations in Lake Superior, which had been considered to be remnants of historical populations, and which were believed to be responsible for the resurgence of lake trout numbers and distribution, have probably been affected by hatchery supplementation.

Comparisons of likelihood and machine learning methods of individual classification.

Classification methods used in machine learning (e.g., artificial neural networks, decision trees, and k-nearest neighbor clustering) are rarely used with population genetic data. We compare different nonparametric machine learning techniques with parametric likelihood estimations commonly employed in population genetics for purposes of assigning individuals to their population of origin ("assignment tests"). Classifier accuracy was compared across simulated data sets representing different levels of population differentiation (low and high F(ST)), number of loci surveyed (5 and 10), and allelic diversity (average of three or eight alleles per locus). Empirical data for the lake trout (Salvelinus namaycush) exhibiting levels of population differentiation comparable to those used in simulations were examined to further evaluate and compare classification methods. Classification error rates associated with artificial neural networks and likelihood estimators were lower for simulated data sets compared to k-nearest neighbor and decision tree classifiers over the entire range of parameters considered. Artificial neural networks only marginally outperformed the likelihood method for simulated data (0-2.8% lower error rates). The relative performance of each machine learning classifier improved relative likelihood estimators for empirical data sets, suggesting an ability to "learn" and utilize properties of empirical genotypic arrays intrinsic to each population. Likelihood-based estimation methods provide a more accessible option for reliable assignment of individuals to the population of origin due to the intricacies in development and evaluation of artificial neural networks.

Group-structured genetic models in analyses of the population and behavioral ecology of poikilothermic vertebrates.

Estimates of gene correlations among individuals within and among populations are frequently derived from statistical analyses of genetic data (e.g., F statistics). These measures can be important tools in molecular ecology and conservation, and offer important insights into population breeding structure. Using recently derived theory developed for group-structured populations, we show that fixation indices, when combined with basic population ecological and demographic data can be used to investigate population mating systems and to predict dispersal rates, trajectories and asymptotic levels of fixation indices, and effective population size. Four case studies of poikilothermic vertebrates are used to demonstrate the broad utility of evolutionary and ecological inferences afforded by group-structured models.

Sex-biased gene flow in spectacled eiders (Anatidae): inferences from molecular markers with contrasting modes of inheritance.

Genetic markers that differ in mode of inheritance and rate of evolution (a sex-linked Z-specific microsatellite locus, five biparentally inherited microsatellite loci, and maternally inherited mitochondrial [mtDNA] sequences) were used to evaluate the degree of spatial genetic structuring at macro- and microgeographic scales, among breeding regions and local nesting populations within each region, respectively, for a migratory sea duck species, the spectacled eider (Somateria fisheri). Disjunct and declining breeding populations coupled with sex-specific differences in seasonal migratory patterns and life history provide a series of hypotheses regarding rates and directionality of gene flow among breeding populations from the Indigirka River Delta, Russia, and the North Slope and Yukon-Kuskokwim Delta, Alaska. The degree of differentiation in mtDNA haplotype frequency among breeding regions and populations within regions was high (phiCT = 0.189, P < 0.01; phiSC = 0.059, P < 0.01, respectively). Eleven of 17 mtDNA haplotypes were restricted to a single breeding region. Genetic differences among regions were considerably lower for nuclear DNA loci (sex-linked: phiST = 0.001, P > 0.05; biparentally inherited microsatellites: mean theta = 0.001, P > 0.05) than was observed for mtDNA. Using models explicitly designed for uniparental and biparentally inherited genes, estimates of spatial divergence based on nuclear and mtDNA data together with elements of the species' breeding ecology were used to estimate effective population size and degree of male and female gene flow. Differences in the magnitude and spatial patterns of gene correlations for maternally inherited and nuclear genes revealed that females exhibit greater natal philopatry than do males. Estimates of generational female and male rates of gene flow among breeding regions differed markedly (3.67 x 10(-4) and 1.28 x 10(-2), respectively). Effective population size for mtDNA was estimated to be at least three times lower than that for biparental genes (30,671 and 101,528, respectively). Large disparities in population sizes among breeding areas greatly reduces the proportion of total genetic variance captured by dispersal, which may accelerate rates of inbreeding (i.e., promote higher coancestries) within populations due to nonrandom pairing of males with females from the same breeding population.

Masoprocol decreases serum triglyceride concentrations in rats with fructose-induced hypertriglyceridemia.

Historically, extracts of the creosote bush have been used by native healers of the Southwest region of North America to treat symptoms of type 2 diabetes. More recently, we have shown that masoprocol (nordihydroguaiaretic acid), a pure compound isolated from the creosote bush (Larrea tridentata), decreases serum glucose and triglyceride (TG) levels when administered orally in rodent models of type 2 diabetes. The present studies were undertaken to determine if masoprocol also decreases TG concentrations in rats with fructose-induced hypertriglyceridemia (HTG), a nondiabetic model of HTG associated with insulin resistance and hyperinsulinemia. Serum TG levels, which were significantly higher after rats ate a fructose-enriched (60% by weight) diet for 14 days as compared with chow-fed controls (411 v 155 mg/dL, P < .01), decreased in a stepwise fashion in fructose-fed rats treated orally with masoprocol for 4 to 8 days over a dose range of 10 to 80 mg/kg twice daily. Using the nonionic detergent Triton WR 1339 to compare TG secretion rates in masoprocol- and vehicle-treated rats, masoprocol at a dose of 40 or 80 mg/kg twice daily, significantly reduced hepatic TG secretion (P < .01) and liver TG content (P < .001), whereas lower doses of masoprocol decreased serum TG without an apparent reduction in hepatic TG secretion. Administration of Intralipid (a fat emulsion) showed that the half-time for removal of TG from serum was also shorter in masoprocol-treated rats versus vehicle-treated controls (31 v 64 minutes, P < .05). In addition adipose tissue lipoprotein lipase (LPL) activity was increased in masoprocol-treated rats and adipose tissue hormone-sensitive lipase (HSL) activity was decreased. We conclude that masoprocol administration to rats with fructose-induced HTG results in lower serum TG levels associated with reduced hepatic TG secretion and increased peripheral TG clearance.

Nutrient Intake Report: a coordination of patient dietary assessment between physicians and registered dietitians.

The Nutrient Intake Report (NIR) is based on a 7-day dietary recall questionnaire used previously in research for dietary assessment and adapted for clinical use. Used to provide information and counseling as part of total patient care, the NIR acts as a cornerstone for dietary education and interaction between physician, registered dietitian, and patient. The NIR is ordered by physicians or registered dietitians, scanned and assessed by a registered dietitian, and incorporated into the laboratory section of the medical record. It documents the patient's dietary intake in the context of his or her diagnosis and general health status. The NIR also opens a dialogue between physicians and registered dietitians. Incorporation of the NIR into the medical record makes the work of the registered dietitian available to other health practitioners, which is welcome in an era when licensing and reimbursement are contingent on systematic documentation of dietary assessment and its role in patient care.

Effective number of breeding adults in Bufo bufo estimated from age-specific variation at minisatellite loci.

Estimates of the effective number of breeding adults were derived for three semi-isolated populations of the common toad Bufo bufo based on temporal (i.e. adult-progeny) variance in allele frequency for three highly polymorphic minisatellite loci. Estimates of spatial variance in allele frequency among populations and of age-specific measures of genetic variability are also described. Each population was characterized by a low effective adult breeding number (Nb) based on a large age-specific variance in minisatellite allele frequency. Estimates of Nb (range 21-46 for population means across three loci) were approximately 55-230-fold lower than estimates of total adult census size. The implications of low effective breeding numbers for long-term maintenance of genetic variability and population viability are discussed relative to the species' reproductive ecology, current land-use practices, and present and historical habitat modification and loss. The utility of indirect measures of population parameters such as Nb and Ne based on time-series data of minisatellite allele frequencies is discussed relative to similar measures estimated from commonly used genetic markers such as protein allozymes.

Lekking without a paradox in the buff-breasted sandpiper.

Females in lek-breeding species appear to copulate with a small subset of the available males. Such strong directional selection is predicted to decrease additive genetic variance in the preferred male traits, yet females continue to mate selectively, thus generating the lek paradox. In a study of buff-breasted sandpipers (Tryngites subruficollis), we combine detailed behavioral observations with paternity analyses using single-locus minisatellite DNA probes to provide the first evidence from a lek-breeding species that the variance in male reproductive success is much lower than expected. In 17 and 30 broods sampled in two consecutive years, a minimum of 20 and 39 males, respectively, sired offspring. This low variance in male reproductive success resulted from effective use of alternative reproductive tactics by males, females mating with solitary males off leks, and multiple mating by females. Thus, the results of this study suggests that sexual selection through female choice is weak in buff-breasted sandpipers. The behavior of other lek-breeding birds is sufficiently similar to that of buff-breasted sandpipers that paternity studies of those species should be conducted to determine whether leks generally are less paradoxical than they appear.