Genetic diversity and population parameters of sea otters, Enhydra lutris, before fur trade extirpation from 1741-1911.

All existing sea otter, Enhydra lutris, populations have suffered at least one historic population bottleneck stemming from the fur trade extirpations of the eighteenth and nineteenth centuries. We examined genetic variation, gene flow, and population structure at five microsatellite loci in samples from five pre-fur trade populations throughout the sea otter's historical range: California, Oregon, Washington, Alaska, and Russia. We then compared those values to genetic diversity and population structure found within five modern sea otter populations throughout their current range: California, Prince William Sound, Amchitka Island, Southeast Alaska and Washington. We found twice the genetic diversity in the pre-fur trade populations when compared to modern sea otters, a level of diversity that was similar to levels that are found in other mammal populations that have not experienced population bottlenecks. Even with the significant loss in genetic diversity modern sea otters have retained historical structure. There was greater gene flow before extirpation than that found among modern sea otter populations but the difference was not statistically significant. The most dramatic effect of pre fur trade population extirpation was the loss of genetic diversity. For long term conservation of these populations increasing gene flow and the maintenance of remnant genetic diversity should be encouraged.

Energetics of nose and mouth breathing, body size, body composition, and nose volume in young adult males and females.

This research tests the relative ability of body size factors and sex to explain variation in nose volume and to explain metabolic measures during rest and moderate exercise in 50 young adults. It uses standard anthropometric measures plus two new measures of nose morphology (nose/face angle and nose volume) and evaluates body composition with a device for air displacement plethysmography. Standard physiological measures were obtained in nose-only and mouth-only breathing conditions with subjects at rest and using moderate exercise. A factor representing linear and bulk measures of body size and a factor representing lean body mass explain subjects' variation in nose volume, resting volume of oxygen consumed (VO2), and resting ventilation volume (VV) better than subject's sex does. By contrast, during exercise, sex explains VO2 and VV better than do body size factors, probably because hormone-mediated muscularity in males produced greater work output. Nose breathing was found to be more energetically efficient in most but not all subjects, but additional research is needed to explore this finding further. Qualitative comparisons between modes of breathing and the application of this research protocol to studies of climate-related patterns of nasal variation are discussed.

Using stable isotope analysis to obtain dietary profiles from old hair: a case study from Plains Indians.

Stable isotope composition of human tissue reflects that of foods consumed, and can provide information about diet independent of artifactual remains. Here we refine and test this method by analyzing nitrogen (delta(15)N) and carbon (delta(13)C) isotope ratios in historic North American Plains Indians hair. Gas-source isotope-ratio mass spectrometry provides high-precision data for both delta(15)N and delta(13)C (+/-0.2 per thousand, 1 sigma) in single hair strands as short as 2 cm (100-150 mug). Because hair contains more carbon than nitrogen, if only delta(13)C data are needed, shorter strands (<1 cm) can be analyzed. This reduction in sample size opens new opportunities for analysis of small hair fragments found in archaeological excavations, as well as for analysis of seasonal variations in long hair strands. We find distinct isotope profiles (delta(15)N vs. delta(13)C) for two cultural groups, the Lower Brule reservation Sioux of 1892 and the reservation Blackfoot of 1892 and 1935. The resultant dietary profiles indicate a higher consumption of meat by the Blackfoot and a higher consumption of maize (or of animals that had fed on maize or other C(4) plants) by the Lower Brule. The two groups of Blackfoot yield similar isotopic profiles despite the passage of four decades, suggesting a strong role for cultural preference even as food sources change. Such stable isotope profiles can be used to link samples from the same cultural tradition based on their similar diets.

An energetics-based approach to understanding the menstrual cycle and menopause.

To explain the menstrual cycle and menopause, human biologists during the past several decades have developed new models of the evolutionary origins and maintenance of female reproductive patterns that address both ultimate and proximate causation. Hypotheses proposed for these processes generally offer explanations for menstruation or for menopause, but not for both; ultimately, these explanations must be integrated. Reviewing current explanations, this paper offers an energetics-based evolutionary rationale compatible with past adaptations of Homo sapiens and with ecological patterns in small-scale, preindustrial social systems in which food resources vary and sometimes are scarce.

UV-induced changes in pigment content and light penetration in the fruticose lichen Cladonia arbuscula ssp. mitis.

The response of the lichen, Cladonia arbuscula (Wallr.) Flot. ssp. mitis (Sandst.) Ruoss to enhanced UV-B (280-315 nm) radiation was investigated with respect to: (a) changes in phenolic content; (b) differential pigment accumulation under visible and UV radiation with increasing distance from thallus apices; and (c) the internal distribution of UV-B radiation within the thallus measured with quartz optical fibres. In a short-term experiment, lichens were exposed for 7 days in a growth chamber to visible light with or without additional UV-B radiation. For a longer term experiment, lichens were grown outdoors under both natural UV radiation, and supplemental UV-A (315-400 nm)+UV-B provided by lamps. Controls were placed under filters that removed the radiation below 290 nm from the natural sunlight. The concentration of total phenolic compounds was measured spectrophotometrically at the termination of the experiments, in different parts of the lichen podetia. UV-exposed lichens showed increased accumulation of phenolics compared to those not grown under UV. At the termination of the long-term experiment, fibre optic measurements of the penetration of radiation into lichen thallus reflected the influence of growth under UV radiation, whereby UV was more strongly attenuated as compared to that in lichens not exposed to enhanced levels of UV-B radiation. Results indicated that in Cladonia, UV-B radiation induces the accumulation of phenolic compounds that may have a protective role. In addition, the morphological distribution of phenolic compounds was different under visible and supplemental UV-B radiation. Internal radiation measurements served to visualise the attenuation of radiation with thallus depth for different wavelengths in the UV-B waveband.

Continuous Infusion Ranitidine in Postoperative Pediatric Liver Transplant Patients: Effects on Intragastric pH, Gastrointestinal Bleeding and Metabolic Alkalosis.

The effects of ranitidine, an H(2)-receptor antagonist, on gastric pH, incidence of upper gastrointestinal hemorrhage and postoperative metabolic alkalosis were evaluated in 23 pediatric liver transplant recipients. Intragastric pH probes were inserted postoperatively and pH was monitored for 48 h. Ranitidine was infused for 48 h at 0.2 mg kg(minus sign1) h(minus sign1) (0.15 with renal impairment) and increased once by 0.05 mg kg(minus sign1) if the pH was less than 4.0 for 4 h. The pretreatment gastric pH was 2.1 plus minus 0.7; ranitidine infusion raised the pH to 6.8 plus minus 0.6 (p greater-than-or-equal 0.05). An intragastric pH > 4 was achieved in 64 plus minus 36 min, with a median ED(50) (50% of maximum response) of 0.24 mg kg(minus sign1). The pH was < 4 for 5.3 plus minus 4.8% of the time after the initial response. Loss of pH control occurred in three patients, two of whom had bacterial sepsis. The incidence of upper gastrointestinal bleeding and metabolic alkalosis was evaluated by comparing the study patients to age- and weight-matched historic controls from our center. Bleeding occurred in 1 of 23 (4%) study patients compared to 7 of 23 (30%) controls (p greater-than-or-equal 0.05). Metabolic alkalosis did not develop in the study patients at 24 or 48 h postoperatively (p greater-than-or-equal 0.05 versus controls). Whole blood cyclosporine levels and hepatocellular enzymes were similar in the two groups. We conclude that continuous intravenous infusion of ranitidine in the postoperative pediatric liver transplant recipient raises intragastric pH, decreases the incidence of upper gastrointestinal hemorrhage and prevents the development of metabolic alkalosis.