Tissues from bony fish were screened with anti-mouse leptin antibodies to detect the presence of the fat-regulating hormone in fishes. Low molecular-weight (16 kDa) immunoreactive bands were detected in blood, brain, heart and liver of green sunfish (Lepomis cyanellus), bluegill sunfish (Lepomis macrochirus), largemouth bass (Micropterus salmoides), white crappie (Pomonix annularis), channel catfish (Ictalurus punctatus), and rainbow trout (Oncorhynchus mykiss). To further verify that we had identified leptin, the response of fish "leptin" was measured in fed and fasted green sunfish. Fed sunfish had approximately threefold higher concentration of leptin in blood than did fasted sunfish (fed vs. fasted; 0.599 ± 0.03 μg/μl vs. 0.196 ± 0.04 μg/μl; P > F = 0.0001), which is consistent with mammalian models of leptin function. Brain leptin concentration is also positively correlated with percent body fat in white crappie and bluegill. Based upon electrophoretic mobility, immunoreactivity, response to fasting, and correlation with adiposity, we believe we have the first evidence for leptin expression in an ectotherm.
The emphasis of this report is on participation patterns across activities and segments of our society. Versions 1 to 13 of NSRE cover more than 50 activities, from casual walking outdoors to more challenging activities such as mountain biking and scuba diving. In this report, we describe both general types of outdoor participation and participation in land, water, and snow or ice settings (for details regarding the history and methodology of the NSRE please refer to the Foreword and Introduction sections). A weighting strategy was also used in the reporting of the data that combined both multi-variate and multiplicative weights (i.e., age, race, sex * education * urban/rural strata) as this considered the most appropriate weighting adjustment. This weighting adjustment assured better estimates of recreation participation and trends across the general population. Version 12 of the NSRE focused only on people living in the southern Appalachians and hence data from this version is not included in this report.
Several polypeptides have been described in the past as components of gap junction fractions. Of these, a peptide of Mr 26,000 is found in gap junctions isolated from livers of different species under conditions that minimize proteolysis. Tryptic digestion of purified "intact" junctions causes the rapid disappearance of this peptide with a concomitant appearance of a band of Mr 10,000, which has previously been found to be characteristic of junctional fractions isolated with the aid of proteolytic treatment. Both the peptides of Mr 26,000 and 10,000 are missing from gap junction preparations after partial hepatectomy, when gap junctions are absent from the surface of the hepatocytes. They have reappeared in fractions from the livers of animals killed 3 days postoperatively, when gap junctions are again present in vivo.
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