Transformation and retention of nitrogen in a coastal forest ecosystem

Transformations and fluxes of N were examined in three forested sites located along a gradient of soil texture in the coastal forests of the Waquoit Bay watershed on Cape Cod. Total N leaching losses to ground water were 0.5 kg ha^-1 yr^-1 in the loamy sand site and 1.5 kg ha^-1 yr^-1 in the fine sand site. Leaching loss to groundwater was not measured in the coarse sand site due to the prohibitive depth of the water table but total N leaching loss to 1m depth in the mineral soil was 3.9 kg ha^-1 yr^-1. DON accounted for most of the leaching losses below the rooting zone (77–89%) and through the soil profile to ground water (60%–80%). Differences in DON retention capacity of the mineral soil in the sites along the soil texture gradient were most likely related to changes in mineral soil particle surface area and percolation rates associated with soil texture. Forests of the watershed functioned as a sink for inorganic N deposited on the surface of the watershed in wet and dry deposition but a source of dissolved organic N to ground water and adjoining coastal ecosystems.     

Lizard herbivory in a sand dune environment: the diet of Angolosaurus skoogi

Summary Early observations of the feeding habits of Angolosaurus skoogi (Andersson), a 50–120 g lizard inhabiting the almost vegetationless dunes of the northern Namib Desert, indicated that this species was herbivorous. Less than two percent of living lizard species are predominantly herbivorous and these species tend to have a high body mass (>100 g). We therefore analysed fecal pellets of A. skoogi to obtain dietary details of this relatively rare lizard. Eighteen food taxa were identified: 81 percent by mass was composed of vegetable matter, of which 56 percent was an endemic, perennial cucurbit Acanthosicyos horrida. Both spatial and temporal variation in dietary composition were apparent. Ready access to water in the form of A. horrida is postulated to have allowed Angolosaurus to occupy this extreme habitat and to forage on components of the windblown detritus, a food source that would probably not be usable in other circumstances.     

Production of neosolaniol monoacetate by an undescribedFusarium species resemblingF camptoceras

Cultures of 12 South African isolates of an undescribedFusarium species resembling but distinct fromF camptoceras were analysed for the presence of diacetoxyscirpenol (DAS), neosolaniol monoacetate (NMA), and T-2 toxin, by capillary gas chromatography utilizing electron capture detection. No DAS or T-2 toxin could be detected in any of the cultures of the isolates. NMA was, however, detected in 10 of the 12 isolates at levels ranging from 310 to 2060 ng/g. The method used, was primarily developed for the determination of DAS and T-2 toxin in fungal cultures and grain samples but was found to be suitable for the coextraction of NMA at an average recovery of 80.8%, with a detection limit in the order of 100 ng/g. Supportive evidence for the presence of the NMA was obtained by capillary gas chromatography / mass spectrometry. Regarded as a relatively rare trichothecene, NMA has never been reported to occur naturally and has previously been shown to be produced by only a fewFusarium strains.     

Receptor binding and Nb2 cell mitogenic activities of glycosylated vs. unglycosylated porcine prolactin

Purified fractions of glycosylated (pGPrl) and unglycosylated (pUGPrl) porcine prolactin were prepared by affinity chromatography on Concanavalin A-Sepharose. The relative binding activities of these two forms of prolactin for receptors from porcine mammary, adrenal cortex and rabbit mammary, as well as their Nb2 cell mitogenic activity were determined. In both the porcine mammary and adrenal cortex receptor binding assays pGPrl had a 2-3 fold lower activity than pUGPrl. In the rabbit mammary binding assay pGPrl had a about a 5 fold lower activity than pUGPrl. Similarly, pGPrl had only about 20% of the activity of pUGPrl in the Nb2 cell proliferation assay.     

Thirty years of chlorophyll modeling

This paper summarizes the progress over approximately thirty-year’s work of the author in developing a model of photosynthesis involving chlorophyll on polymeric substrates that would photosensitize endergonic electron transfer. The system finally achieved might, with proper modifications, serve as a means of generating power from solar energy.     

Glycine oxidation and conversion into amino acids in Saccharomyces cerevisiae and Candida albicans

Humans are exposed much more often to exogenous Saccharomyces cerevisiae (a baker’s yeast) than exogenous Candida albicans (a highly infectious yeast) but suffer no apparent complications from S. cerevisiae. We hypothesize that variations in characteristics between these two species may be due, in part, to differences in glycine metabolism. In this study, we examined differences in glycine oxidation between C. albicans and S. cerevisiae. Both C. albicans and S. cerevisiae were cultured in glycine enriched media, followed by determination of glycine oxidation and amino acid concentrations in cells. Glycine was degraded to a much greater extent in C. albicans than in S. cerevisiae. Threonine concentrations and glycine oxidation were also elevated in C. albicans. Almost all of the disappearance of glycine from incubation media was accounted for by the formation of serine, threonine, and CO₂ in S. cerevisiae, whereas these products represented only 50% of the metabolized glycine in C. albicans. The unidentified metabolites of glycine in C. albicans, presumably purines, could contribute to its infectious capacity and this warrants further study.     

Evaluation of Hydroxyatrazine in the Endocrine Disruptor Screening and Testing Program's Male and Female Pubertal Protocols

Two critical components of the validation of any in vivo screening assay are to demonstrate sensitivity and specificity. Although the Endocrine Disruptor Screening Program's Tier 1 Male and Female Pubertal Protocols have been shown to be sensitive assays for the detection of weak endocrine disrupting chemicals (EDCs), there are concerns that the assays lack specificity for EDC effects when a chemical induces systemic toxicity. A lack of specificity, or the ability to correctly identify an inactive or “negative” chemical, would increase the probability of identifying false positives. Here, we orally exposed rats to hydroxyatrazine (OH‐ATR), a biotransformation by‐product of the chlorotriazine herbicides that produced nephrotoxicity following a 13‐week dietary exposure. Based on a previous study in our laboratory, males were dosed with 11.4 to 183.4 mg/kg OH‐ATR and females were dosed with 45.75 to 183.4 mg/kg OH‐ATR. Following exposure in both sexes, there was a dose–response increase in mean kidney weights and the incidence and severity of kidney lesions. These lesions included the deposition of mineralized renal tubule concretions, hydronephrosis, renal tubule dilatation, and pyelonephritis. However, no differences in body weight, liver weight, or reproductive tissue weights, reproductive or thyroid histology, hormone concentrations or the age of pubertal onset were observed. Therefore, the results demonstrate that the endpoints included in the pubertal assay are useful for nonendocrine (systemic) effects that define an no observable effect level (NOEL) or lowest observable effect level (LOEL) and provide one example where an impact on kidney function does not alter any of the endocrine‐specific endpoints of the assay.     

Naturopathic medicine for the prevention of cardiovascular disease: a randomized clinical trial

Background:Although cardiovascular disease may be partially preventable through dietary and lifestyle-based interventions, few individuals at risk receive intensive dietary and lifestyle counselling. We performed a randomized controlled trial to evaluate the effectiveness of naturopathic care in reducing the risk of cardiovascular disease.Methods:We performed a multisite randomized controlled trial of enhanced usual care (usual care plus biometric measurement; control) compared with enhanced usual care plus naturopathic care (hereafter called naturopathic care). Postal workers aged 25–65 years in Toronto, Vancouver and Edmonton, Canada, with an increased risk of cardiovascular disease were invited to participate. Participants in both groups received care by their family physicians. Those in the naturopathic group also received individualized care (health promotion counselling, nutritional medicine or dietary supplementation) at 7 preset times in work-site clinics by licensed naturopathic doctors. The body weight, waist circumference, lipid profile, fasting glucose levels and blood pressure of participants in both groups were measured 3 times during a 1-year period. Our primary outcomes were the 10-year risk of having a cardiovascular event (based on the Framingham risk algorithm) and the prevalence of metabolic syndrome (based on the Adult Treatment Panel III diagnostic criteria).Results:Of 246 participants randomly assigned to a study group, 207 completed the study. The characteristics of participants in both groups were similar at baseline. Compared with participants in the control group, at 52 weeks those in the naturopathic group had a reduced adjusted 10-year cardiovascular risk (control: 10.81%; naturopathic group: 7.74%; risk reduction −3.07% [95% confidence interval (CI) −4.35% to −1.78%], p < 0.001) and a lower adjusted frequency of metabolic syndrome (control group: 48.48%; naturopathic care: 31.58%; risk reduction −16.90% [95% CI −29.55% to −4.25%], p = 0.002).Interpretation:Our findings support the hypothesis that the addition of naturopathic care to enhanced usual care may reduce the risk of cardiovascular disease among those at high risk. Trial registration: ClinicalTrials.gov, no. NCT0071879.Cardiovascular disease is the second leading cause of death in Canada.¹ Observational studies, including a large international case–control study, have shown that several modifiable behavioural factors contribute to the risk of cardiovascular disease.² Metabolic syndrome, a cluster of modifiable risk factors for atherosclerotic cardiovascular disease, is strongly associated with increased risk of cardiovascular-related mortality.^3,4 Guidelines by the American Heart Association and the United States Preventive Services Task Force recommend lifestyle interventions as an important part of cardiovascular disease prevention.^5,6 Although the importance of lifestyle intervention is widely recognized, few individuals with, or at risk of, cardiovascular disease receive intensive dietary and lifestyle counselling.^7,8A variety of health care practitioners routinely deliver diet and health promotion advice to patients at risk of cardiovascular disease. Naturopathic doctors in North America are trained and regulated practitioners who emphasize this form of self-directed care. Several retrospective analyses have suggested that patients at risk of cardiovascular disease receive lifestyle counselling routinely as part of naturopathic care.^9–11 However, no rigorous studies have examined the effectiveness of these approaches. To evaluate the effectiveness of representative naturopathic approaches to reducing the risk of cardiovascular disease, we conducted a randomized clinical trial of a multimodality nutritional and physical activity intervention in a workplace setting.     

Hypolithic and soil microbial community assembly along an aridity gradient in the Namib Desert

The Namib Desert is considered the oldest desert in the world and hyperarid for the last 5 million years. However, the environmental buffering provided by quartz and other translucent rocks supports extensive hypolithic microbial communities. In this study, open soil and hypolithic microbial communities have been investigated along an East–West transect characterized by an inverse fog-rainfall gradient. Multivariate analysis showed that structurally different microbial communities occur in soil and in hypolithic zones. Using variation partitioning, we found that hypolithic communities exhibited a fog-related distribution as indicated by the significant East–West clustering. Sodium content was also an important environmental factor affecting the composition of both soil and hypolithic microbial communities. Finally, although null models for patterns in microbial communities were not supported by experimental data, the amount of unexplained variation (68–97 %) suggests that stochastic processes also play a role in the assembly of such communities in the Namib Desert.