Insufficient sleep is a risk factor for depression, suicidality, and substance use, yet little is known about gender, ethnic, and community-level differences in sleep and its associated outcomes, especially during adolescence. Further, much of the prior work has compared groups of teens getting plenty as opposed to insufficient amounts of sleep rather than examine sleep hours continuously. The present study examined adolescent weekday self-reported sleep duration and its links with hopelessness, suicidality, and substance use in a suburban community with very early high school start times. We utilized a large (N = 27,939, 51.2% female) and ethnically diverse sample of adolescents from the 2009 Fairfax County (Virginia) Youth Survey, an anonymous, self-report, population-level survey administered to all 8th, 10th and 12th grade students in public schools in the county. High-school students reported an average 6.5 h of sleep per school night, with 20% obtaining ≤5 h, and only 3% reporting the recommended 9 h/night. Females and minority youth obtained even less sleep on average, and the reduction in sleep in the transition from middle school to high school was more pronounced for females and for Asian students. Hierarchical, multivariate, logistic regression analyses, controlling for background variables, indicated that just 1 h less of weekday sleep was associated with significantly greater odds of feeling hopeless, seriously considering suicide, suicide attempts, and substance use. Relationships between sleep duration and suicidality were stronger for male teens, and sleep duration was more associated with hopelessness for white students compared to most ethnic minority groups. Implications for intervention at multiple levels are discussed.
Persistent adaptive challenges are often met with the evolution of novel physiological traits. Although there are specific examples of single genes providing new physiological functions, studies on the origin of complex organ functions are lacking. One such derived set of complex functions is found in the Lepidopteran bursa copulatrix, an organ within the female reproductive tract that digests nutrients from the male ejaculate or spermatophore. Here, we characterized bursa physiology and the evolutionary mechanisms by which it was equipped with digestive and absorptive functionality. By studying the transcriptome of the bursa and eight other tissues, we revealed a suite of highly expressed and secreted gene products providing the bursa with a combination of stomach-like traits for mechanical and enzymatic digestion of the male spermatophore. By subsequently placing these bursa genes in an evolutionary framework, we found that the vast majority of their novel digestive functions were co-opted by borrowing genes that continue to be expressed in nonreproductive tissues. However, a number of bursa-specific genes have also arisen, some of which represent unique gene families restricted to Lepidoptera and may provide novel bursa-specific functions. This pattern of promiscuous gene borrowing and relatively infrequent evolution of tissue-specific duplicates stands in contrast to studies of the evolution of novelty via single gene co-option. Our results suggest that the evolution of complex organ-level phenotypes may often be enabled (and subsequently constrained) by changes in tissue specificity that allow expression of existing genes in novel contexts, such as reproduction. The extent to which the selective pressures encountered in these novel roles require resolution via duplication and sub/neofunctionalization is likely to be determined by the need for specialized reproductive functionality. Thus, complex physiological phenotypes such as that found in the bursa offer important opportunities for understanding the relative role of pleiotropy and specialization in adaptive evolution.
How students manage their time is critical for academic performance and is an important component of self-regulated learning. The purpose of the present study was to examine relationships among first-year college students' (N = 589) time use, academic self-regulation, and target and actual grade point average (GPA) at three time points. Findings showed that students planned and spent less time on academics than socializing and work obligations in their first semester. Students generally planned to spend more time on academics in the second semester. Academic time use (planned and actual academic hours) related to higher self-regulated learning and target GPA in the first and second semester. Students who were farther away from their first-semester target lowered their second-semester target GPA instead of planning more time in academics. Students exceeding their target first-semester GPA planned to socialize more in the second semester. Orientation and transition programs that assist students may need to revisit time management and planning midway through the year to address potentially inadequate self-regulated learning in the first year of college. Keywords time use, time management, self-regulated learning, goals, college College is a time for pursuing a wide array of activities and interests, but each activity takes time. Recent surveys suggest that college students are spending time on vocational
Preterm birth is a heterogeneous entity that is mediated by obesity status and maternal age. Obesity among pregnant teenagers increases the risk for medically indicated preterm birth but not the risk for spontaneous preterm birth.
Reproductive traits experience high levels of selection because of their direct ties to fitness, often resulting in rapid adaptive evolution. Much of the work in this area has focused on male reproductive traits. However, a more comprehensive understanding of female reproductive adaptations and their relationship to male characters is crucial to uncover the relative roles of sexual cooperation and conflict in driving co-evolutionary dynamics between the sexes. We focus on the physiology of a complex female reproductive adaptation in butterflies and moths: a stomach-like organ in the female reproductive tract called the bursa copulatrix that digests the male ejaculate (spermatophore). Little is known about how the bursa digests the spermatophore. We characterized bursa proteolytic capacity in relation to female state in the polyandrous butterfly Pieris rapae. We found that the virgin bursa exhibits extremely high levels of proteolytic activity. Furthermore, in virgin females, bursal proteolytic capacity increases with time since eclosion and ambient temperature, but is not sensitive to the pre-mating social environment. Post copulation, bursal proteolytic activity decreases rapidly before rebounding toward the end of a mating cycle, suggesting active female regulation of proteolysis and/or potential quenching of proteolysis by male ejaculate constituents. Using transcriptomic and proteomic approaches, we report identities for nine proteases actively transcribed by bursal tissue and/or expressed in the bursal lumen that may contribute to observed bursal proteolysis. We discuss how these dynamic physiological characteristics may function as female adaptations resulting from sexual conflict over female remating rate in this polyandrous butterfly.
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