Southern flounder (Paralichthys lethostigma) exhibit environmental sex determination (ESD), where environmental factors can influence phenotypic sex during early juvenile development but only in the ...presumed XX female genotype. Warm and cold temperatures masculinize fish with mid-range conditions producing at most 50% females. Due to sexually dimorphic growth, southern flounder fisheries are dependent upon larger females. Wild populations could be at risk of masculinization from ESD due to globally increasing water temperatures. We evaluated the effects of habitat and temperature on wild populations of juvenile southern flounder in North Carolina, USA. While northern habitats averaged temperatures near 23 °C and produced the greatest proportion of females, more southerly habitats exhibited warmer temperatures (>27 °C) and consistently produced male-biased sex ratios (up to 94% male). Rearing flounder in the laboratory under temperature regimes mimicking those of natural habitats recapitulated sex ratio differences observed across the wild populations, providing strong evidence that temperature is a key factor influencing sex ratios in nursery habitats. These studies provide evidence of habitat conditions interacting with ESD to affect a key demographic parameter in an economically important fishery. The temperature ranges that yield male-biased sex ratios are within the scope of predicted increases in ocean temperature under climate change.
As the number of patients with congenital heart disease (CHD) continues to increase, the burden of heart failure (HF) in this population requires innovative strategies to individualize management. ...Given the success of implanted invasive hemodynamic monitoring (IHM) with the CardioMEMSTM HF system in adults with acquired HF, this is often suggested for use in patients with CHD, though published data are limited to case reports and case series. Therefore, this review summarizes the available published reports on the use of IHM in patients with complex CHD, describes novel applications, and highlights future directions for study. In patients with CHD, IHM has been used across the lifespan, from age 3 years to adulthood, with minimal device-related complications reported. IHM uses include (1) prevention of HF hospitalizations; (2) reassessment of hemodynamics after titration of medical therapy without repeated cardiac catheterization; (3) serial monitoring of at-risk patients for pulmonary hypertension to optimize timing of heart transplant referral; (4) and hemodynamic assessment with exercise (5) or after ventricular assist device placement. IHM has the potential to reduce the number of cardiac catheterizations in anatomically complex patients and, in patients with Fontan circulation, IHM pressures may have prognostic implications. In conclusion, though further studies are needed, as patients with CHD age and HF is more prevalent, this tool may assist CHD physicians in caring for this complex patient population.
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The generation of genome‐scale data is critical for a wide range of questions in basic biology using model organisms, but also in questions of applied biology in nonmodel organisms (agriculture, ...natural resources, conservation and public health biology). Using a genome‐scale approach on a diverse group of nonmodel organisms and with the goal of lowering costs of the method, we modified a multiplexed, high‐throughput genomic scan technique utilizing two restriction enzymes. We analysed several pairs of restriction enzymes and completed double‐digestion RAD sequencing libraries for nine different species and five genera of insects and fish. We found one particular enzyme pair produced consistently higher number of sequence‐able fragments across all nine species. Building libraries off this enzyme pair, we found a range of usable SNPs between 4000 and 37 000 SNPS per species and we found a greater number of usable SNPs using reference genomes than de novo pipelines in STACKS. We also found fewer reads in the Read 2 fragments from the paired‐end Illumina Hiseq run. Overall, the results of this study provide empirical evidence of the utility of this method for producing consistent data for diverse nonmodel species and suggest specific considerations for sequencing analysis strategies.
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•Historic data indicate mild valvar PS in adults does not progress.•The prevalence of older adults with CHD is increasing.•Valvular calcification may lead to progression of PS in ...later life.•Echocardiography should be used for routine follow-up for PS.
Southern flounder (
Paralichthys lethostigma) support valuable North American fisheries and show great promise for aquaculture. Because females grow faster and reach larger adult sizes than males, ...monosex culture of females is desirable for commercial operations. A detailed understanding of sexual development and its timing is critical to control sex and optimize culture. Structural and cellular sex-distinguishing markers were identified histologically, and then used to describe ovarian development in female and testicular development in male flounder. In presumptive ovaries of southern flounder, development of an ovarian cavity first occurs in fish ranging from 75 to 100 mm total length (TL). This is considerably delayed relative to that observed in the Japanese congener,
Paralichthys olivaceus, where an ovarian cavity is seen in fish as small as 40 mm TL. The smallest southern flounder that possessed primary oocytes in the early perinucleolus stage was 115 mm TL. In presumptive testes, the formation of seminiferous tubules first occurs in fish of approximately 100 mm TL. Spermatogonia remained quiescent until most fish were over 100 mm TL. Overall, gonads from southern flounder greater than 120 mm TL commonly possess gonial cells undergoing meiosis, clearly differentiating sex. The effect of temperature on sex determination in southern flounder was addressed in a separate experiment. Juvenile southern flounder were grown at 18, 23, or 28°C for 245 days. High and low temperatures induced phenotypic sex reversal in juvenile southern flounder, producing a higher proportion of males (96% males at high temperature,
P<0.001, 78% males at low temperature,
P<0.01). Raising southern flounder at the midrange temperature held sex ratios close to 1:1. Sex ratios from these trials suggest that southern flounder possess a temperature-sensitive mechanism of sex determination similar to that shown for
P. olivaceus, but possibly shifted towards warmer temperatures. These findings indicate that sex differentiation in southern flounder is distinguishable in most fish by 100–120 mm TL and that sex determination is sensitive to temperature. This information is critical to the development of strategies to maximize the number of faster-growing females for commercial flounder culture.
Objective
This study was performed to determine whether students who are trained in developing a personal formulary become more competent in rational prescribing than students who have only learned ...to use existing formularies.
Methods
This was a multicentre, randomised, controlled study conducted in eight universities in India, Indonesia, the Netherlands, the Russian Federation, Slovakia, South Africa, Spain and Yemen. Five hundred and eighty-three medical students were randomised into three groups: the personal formulary group (PF; 94), the existing formulary group (EF; 98) and the control group (C; 191). The PF group was taught how to develop and use a personal formulary, whereas e the EF group was taught how to review and use an existing formulary. The C group received no additional training and participated only in the tests. Student’s prescribing skills were measured by scoring their treatment plans for written patient cases.
Results
The mean PF group score increased by 23% compared with 19% for the EF group (
p
< 0.05) and 6% for controls (
p
< 0.05). The positive effect of PF training was only significant in universities that had a mainly classic curriculum.
Conclusion
Training in development and use of a personal formulary was particularly effective in universities with a classic curriculum and with traditional pharmacology teaching. In universities with a general problem-based curriculum, pharmacotherapy teaching can be based on either existing or personal formularies.
Effective methods for induction of diploid gynogenesis in North American flounder of the genus
Paralichthys are needed to initiate monosex culture, which will allow growers to take advantage of the ...more rapid growth and larger size attained by females. To test methods for inducing diploid gynogenesis in southern flounder (
Paralichthys lethostigma) using homologous sperm, four treatments, named for their expected outcome, were employed: haploid, diploid, triploid, and gynogenetic diploid. Diploid gynogenesis was induced by activating egg development with UV-irradiated flounder sperm (70 J/cm
2) for 3–4 min in seawater, and then subjecting the eggs to cold shock in 0–2 °C seawater for 45–50 min. Cold shock was used to prevent extrusion of the second polar body. Control treatments omitted one or more of these steps to separately assess the effectiveness of UV irradiation and cold shock. Larvae were observed for physical abnormalities and then histologically processed for ploidy determination. Haploid larvae exhibited abnormal external morphology while diploid, gynogenetic diploid, and triploid larvae showed normal morphologies. Cross-sectional areas of erythrocyte nuclei were measured for larvae in each treatment group and significant differences were found. Nuclear areas for treatment groups corresponded to predicted ploidy (triploid>diploid>haploid) and did not differ between normal diploid controls and gynogenetic diploids. These results suggest that the procedures of sperm irradiation and egg cold shock successfully generated gynogenetic diploids. Due to the low volumes of semen produced by male flounder, and to eliminate any potential genetic contribution by homologous sperm, activation of flounder eggs with heterologous sperm was also investigated. Induction of diploid gynogenesis was successful when flounder eggs were fertilized with irradiated (50 J/cm
2) sperm from striped mullet (
Mugil cephalus), and then cold shocked. This work provides procedures for induction of diploid gynogenesis in southern flounder using homologous and heterologous sperm, and validates a method for verification of ploidy in larval fish.
Environmental sex-determination (ESD) is the phenomenon by which environmental factors regulate sex-determination, typically occurring during a critical period of early development. Southern flounder ...(Paralichthys lethostigma) exhibit temperature-dependent sex-determination that appears to be restricted to the presumed XX female genotype with the extremes of temperature, both high and low, skewing sex ratios toward males. In order to evaluate other environmental factors that may influence sex-determination, we investigated the influence of background color and cortisol on sex-determination in southern flounder. Experiments involving three sets of tanks, each painted a different color, were conducted at different temperatures using southern flounder of mixed XX–XY genotype. The studies involved rearing juvenile southern flounder in either black, gray, or blue tanks and sex-determination was assessed by gonadal histology. In both studies, blue tanks showed significant male-biased sex ratios (95 and 75% male) compared with black and gray tanks. The stress corticosteroid cortisol may mediate sex-determining processes associated with environmental variables. Cortisol from the whole body was measured throughout the second experiment and fishes in blue tanks had higher levels of cortisol during the period of sex-determination. These data suggest that background color can be a cue for ESD, with blue acting as a stressor during the period of sex-determination, and ultimately producing male-skewed populations. In a separate study using XX populations of southern flounder, cortisol was applied at 0, 100, or 300 mg/kg of gelatin-coated feed. Fish were fed intermittently prior to, and just through, the period of sex-determination. Levels of gonadal P450 aromatase (cyp19a1) and forkhead transcription factor L2 (FoxL2) messenger RNA (mRNA) were measured by qRT–PCR as markers for differentiation into females. Müllerian-inhibiting substance mRNA was used as a marker of males’ gonadal development. Control fish showed female-biased sex ratios approaching 100%, whereas treatment with 100 mg/kg cortisol produced 28.57% females and treatment with 300 mg/kg cortisol produced only 13.33% females. These results suggest that cortisol is a critical mediator of sex-determination in southern flounder by promoting masculinization. This linkage between the endocrine stress axis and conserved sex-determination pathways may provide a mechanism for adaptive modification of sex ratio in a spatially and temporally variable environment.
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