We found that the basolateral surface of the gill epithelium of the marine mussel Mytilus californianus possesses a carrier-mediated process capable of concentrating taurine within epithelial cells. ...We used retrograde perfusion of gill sections to demonstrate the kinetics, specificity and ion-dependence of taurine transport. 3Htaurine was concentrated relative to a space marker (14Cmannitol); this accumulation was blocked by the inclusion of 10 mmol l-1 unlabeled taurine in the perfusate. The drop in 3Htaurine uptake at increasing concentrations of unlabeled taurine was fitted to Michaelis-Menten kinetics and indicated a basolateral process with a taurine concentration at which transport is half-maximal (Kt) of 35.3 mumol l-1 and a maximal flux (Jmax) of 0.35 mumol g-1 wet mass h-1. Taurine accumulation on the apical surface had a higher affinity (Kt = 9.5 mumol l-1) and a higher maximum rate of transport (Jmax = 1.23 mumol g-1 h-1). Basolateral transport was inhibited by inclusion in the perfusate of 1 mmol l-1 of another beta-amino acid (beta-alanine), but not by inclusion of alpha-alanine, glutamic acid or betaine. The dependence of basolateral taurine transport on Na+ (when replaced with N-methyl-D-glucamine) was sigmoidal with an apparent Hill coefficient of 2.3, indicating that more than one Na+ is necessary for the transport of each taurine molecule. Complete substitution of Cl- in bathing media reduced taurine accumulation by 90% and 70% on the apical and basolateral surfaces, respectively. Taurine accumulation on both surfaces was reduced by only 20% when Cl- was reduced from 496 to 73 mmol l-1, suggesting that taurine uptake is not significantly influenced by the changes in Cl- concentration accompanying the salinity fluctuations normally encountered by mussels. We estimate that the various Na+ and Cl- gradients naturally encountered by epithelial cells are capable of providing ample energy to maintain a high intracellular concentration of taurine. We suggest that the ability of epithelial cells to accumulate taurine across the basolateral surface from the hemolymph plays a significant role in the intracellular regulation of this important osmolyte and may effect osmolality-dependent changes in the intracellular concentration of taurine.
Using an approach based on polymerase chain reaction (PCR), we examined the diversity of polyketide synthase (PKS) genes present in 160 marine fungal isolates, representing 142 species. We obtained ...ketosynthase (KS) domain PCR products from 99 fungal isolates, representing Dothideomycetes, Sordariomycetes, Eurotiomycetes, and incertae sedis. Sequence similarity searches and phylogenetic analysis of 29 marine partial-KS-encoding sequences revealed domains predicted to encode reducing, nonreducing, and 6-methylsalicylic acid PKSs. Bioinformatic analysis of an alignment of the KS sequences from marine-derived fungi revealed no unique motifs in this region. However, several specificity-determining positions were apparent between fungal 6-methylsalicylic acid PKSs as compared with either reducing or nonreducing PKSs. Evaluation of these positions in the context of a modelled three-dimensional protein structure highlighted their potential use as PKS classification markers. Evaluating primer-binding sites was necessary to obtain KS domain fragments from putative PKSs while maintaining a level of sequence information adequate to properly classify and characterize them.
The zero-age main sequence (ZAMS) is a critical phase for stellar angular
momentum evolution, as stars transition from contraction-dominated spin-up to
magnetic wind-dominated spin-down. We present ...the first robust observational
constraints on rotation for FGK stars at $\approx40$ Myr. We have analyzed TESS
light curves for 1410 members of five young open clusters with ages between
25-55 Myr: IC 2391, IC 2602, NGC 2451A, NGC 2547, and Collinder 135. In total,
we measure 868 rotation periods, including 96 new, high-quality periods for
stars around 1 ${M_{\odot}}$. This is an increase of ten times the existing
literature sample at the ZAMS. We then use the $\tau^2$ method to compare our
data to models for stellar angular momentum evolution. Although the ages
derived from these rotation models do not match isochronal ages, we show these
observations can clearly discriminate between different models for stellar wind
torques. Finally, $\tau^2$ fits indicate that magnetic braking and/or internal
angular momentum transport significantly impact rotational evolution even on
the pre-main sequence.
This survey was conducted to learn how the career decisions of women and men in cardiology influenced their professional and personal lives.
Women represent only 5% of practicing adult cardiologists ...and 10% of trainees. Yet, women and men now enter medical school at nearly equal numbers. The factors that contribute to career satisfaction in cardiology should be identified to permit the development of future strategies to ensure that the best possible candidates are attracted to the profession.
A questionnaire developed by the Ad Hoc Committee on Women in Cardiology of the American College of Cardiology (ACC) was mailed in March 1996 to all 964 female ACC members and an age-matched sample of 1,199 male members who had completed cardiovascular training.
Women were more likely to describe their primary or secondary role as a clinical/noninvasive than invasive cardiologist (p < 0.0001 women vs. men). Men and women both reported a high level of satisfaction with family life, but women were less satisfied with their work as cardiologists (88% vs. 92%, p < 0.01) and with their level of financial compensation. Compared with men, women expressed less overall satisfaction (69% vs. 84%) and more dissatisfaction with their ability to achieve professional goals (21% vs. 9%). These differences were most pronounced for women in academic practice. Women reported greater family responsibilities, which may limit their opportunities for career advancement. Women were more likely to alter training or practice focus to avoid radiation. A majority of women (71%) reported gender discrimination, whereas only 21% of men reported any discrimination, largely due to race, religion or foreign origin.
Women cardiologists report overall lower satisfaction with work and advancement, particularly within academic practice. They report more discrimination, more concerns about radiation and more limitations due to family responsibilities, which may ultimately explain the low percentage of women in cardiology. Attention to these issues may result in programs to improve professional satisfaction and attract the best candidates into cardiology in the future.
Cronbach’s alpha is one of the most widely used measures of reliability in the social and organizational sciences. Current practice is to report the sample value of Cronbach’s alpha reliability, but ...a confidence interval for the population reliability value also should be reported. The traditional confidence interval for the population value of Cronbach’s alpha makes an unnecessarily restrictive assumption that the multiple measurements have equal variances and equal covariances. We propose a confidence interval that does not require equal variances or equal covariances. The results of a simulation study demonstrated that the proposed method performed better than alternative methods. We also present some sample size formulas that approximate the sample size requirements for desired power or desired confidence interval precision. R functions are provided that can be used to implement the proposed confidence interval and sample size methods.
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