Bumblebee foraging rhythms under the midnight sun measured with radiofrequency identification

<p>Abstract</p> <p>Background</p> <p>In the permanent daylight conditions north of the Arctic circle, there is a unique opportunity for bumblebee foragers to maximise intake, and therefore colony growth, by remaining active during the entire available 24-h period. We tested the foraging rhythms of bumblebee (<it>Bombus terrestris </it>and <it>B. pascuorum</it>) colonies in northern Finland during the summer, when the sun stays above the horizon for weeks. We used fully automatic radio-frequency identification to monitor the foraging activity of more than 1,000 workers and analysed their circadian foraging rhythms.</p> <p>Results</p> <p>Foragers did not use the available 24-h foraging period but exhibited robust diurnal rhythms instead. A mean of 95.2% of the tested <it>B. terrestris </it>workers showed robust diurnal rhythms with a mean period of 23.8 h. Foraging activity took place mainly between 08:00 and 23:00, with only low or almost no activity during the rest of the day. Activity levels increased steadily during the morning, reached a maximum around midday and decreased again during late afternoon and early evening. Foraging patterns of native <it>B. pascuorum </it>followed the same temporal organisation, with the foraging activity being restricted to the period between 06:00 and 22:00.</p> <p>Conclusions</p> <p>The results of the present study indicate that the circadian clock of the foragers must have been entrained by some external cue, the most prominent being daily cycles in light intensity and temperature. Daily fluctuations in the spectral composition of light, especially in the UV range, could also be responsible for synchronising the circadian clock of the foragers under continuous daylight conditions.</p

Codon bias at the 3 `-side of the initiation codon is correlated with translation initiation efficiency in Escherichia coli

The codon that follows the AUG initiation tripler (+2 codon) affects gene expression in Escherichia coli. We have extended this analysis using two model genes lacking any apparent Shine-Dalgamo sequence. Depending on the identity of the +2 codon a difference in gene expression up to 20-fold could be obtained. The effects did not correlate with the levels of intracellular pools of cognate tRNA for the +2 codon, with putative secondary mRNA structures, or with mRNA stability. However, most +2 iso-codons that were decoded by the same species of tRNA gave pairwise similar effects, suggesting that the effect on gene expression was associated with the decoding tRNA. High adenine content of the +2 codon was associated with high gene expression. Of the fourteen +2 codons that mediated the highest efficiency, all except two had an adenine as the first base of the codon. Analysis of the 3540 E. coli genes from the TransTerm database revealed that codons associated with high gene expression in the two expression systems are over-represented at the +2 position in natural genes. Codons that are associated with low gene expression are under-represented. The data suggest that evolution has favored codons at the +2 position that give high translation initiation. (C) 2001 Elsevier Science B.V. All rights reserved

Ghrelin in the regulation of feeding and energy balance

Ghrelin, the first identified endogenous ligand for the growth hormone secretagogue receptor 1A, is a 28 amino acid peptide produced mainly by the stomach. Pharmacological studies indicate a role for ghrelin in the regulation of growth hormone secretion from the pituitary and also in the regulation of body weight, fat accumulation and food intake. Using a classical endocrine deletion/replacement approach we found support for the notion that endogenous ghrelin is required for the maintenance of normal body weight and adiposity. Gastrectomy (Gx) surgery, that depleted animals of ~80% of circulating ghrelin, caused a reduction in body weight, fat mass and lean mass in adult mice. Ghrelin replacement (at a dose that restores circulating ghrelin levels in Gx mice and that is without effect on body weight in sham animals) fully or partially reversed the decrease in body weight, fat mass and lean mass following Gx. To further investigate the central mechanism behind these effects on body weight and fat mass following Gx-surgery and ghrelin treatment key hypothalamic genes involved in energy homeostasis were analysed by in situ hybridisation. Surprisingly the marked changes in body composition following Gx did not effect expression of the hypothalamic genes studied, to any large extent. By contrast ghrelin treatment increased mRNA expression of NPY and AgRP and decreased POMC mRNA expression in accordance with ghrelin s effects to increase fat mass and body weight. Using growth hormone receptor (GHR) knockout animals we investigated the importance of a functional GHR signalling system for the acute effects of ghrelin on food intake. Ghrelin treatment increased food intake in wild type animals but not in GHR knockouts indicating that a functional GHR signalling system is needed for the acute effects of ghrelin on food intake. In addition to impacting upon the hypothalamic circuits controlling energy balance, ghrelin was found to interact with the mesolimbic reward circuits (reflected by increased locomotor activity and dopamine release after ghrelin injection to the brain ventricles). In conclusion, endogenous ghrelin from the stomach is important for maintaining normal body weight and body composition. Long term treatment with ghrelin increases body fat by a mechanism that appears to be independent of its acute affects on food intake. Long term ghrelin treatment still impacts upon hypothalamic genes regulating energy balance. Ghrelin s acute effect on food intake is dependant on a functional GHR signalling system. Moreover, this effect may be linked to dopamine release in areas of the brain intimately associated with reward-seeking activities

Resection of Pheochromocytoma Improves Diabetes Mellitus in the Majority of Patients

BackgroundCatecholamine excess in patients with pheochromocytoma often results in impaired glucose tolerance, leading to diabetes mellitus. Little data are available on the long-term effect of surgery on diabetes.ObjectiveThe primary aim of this study was to determine the likelihood of diabetes cure after surgery, while secondary objectives were to determine risk factors for development of diabetes preoperatively and persistence of diabetes postoperatively.MethodsAll patients undergoing surgery for pheochromocytoma from 1996 to 2015 were retrospectively reviewed to identify those with a preoperative diagnosis of diabetes. Demographic and diabetes-specific data were collected. Median follow-up was 52.1&nbsp;months.ResultsOverall, 153 patients underwent surgery. Diabetes was seen in 36 (23.4%) patients. Eight patients met the exclusion criteria and were removed from the final analysis, while 22 (78.6%) patients had complete resolution of diabetes. Four patients remained on medication with improved control. Overall, 93.0% of patients had improvement of their diabetes; two patients did not improve. Patients with large, symptomatic tumors were more likely to develop preoperative diabetes, and diabetes was more likely to persist in patients who had an elevated body mass index (BMI).ConclusionsDiabetes was found concurrently with pheochromocytoma in 23% of patients, more often in those with large, symptomatic tumors. The majority of patients had long-term resolution of diabetes after successful resection; however, some patients may continue to require treatment of diabetes after operation, especially those with a higher BMI

Unlocking Potentials of Microwaves for Food Safety and Quality

Abstract: Microwave is an effective means to deliver energy to food through polymeric package materials, offering potential for developing short-time in-package sterilization and pasteurization processes. The complex physics related to microwave propagation and microwave heating require special attention to the design of process systems and development of thermal processes in compliance with regulatory requirements for food safety. This article describes the basic microwave properties relevant to heating uniformity and system design, and provides a historical overview on the development of microwave-assisted thermal sterilization (MATS) and pasteurization systems in research laboratories and used in food plants. It presents recent activities on the development of 915 MHz single-mode MATS technology, the procedures leading to regulatory acceptance, and sensory results of the processed products. The article discusses needs for further efforts to bridge remaining knowledge gaps and facilitate transfer of academic research to industrial implementation

Testosterone is associated with self-employment among Australian men

Testosterone has pronounced effects on men’s physiological development and smaller, more nuanced, impacts on their economic behavior. In this study of 1199 Australian adult males, we investigate the relationship between the self-employed and their serum testosterone levels. Because prior studies have identified that testosterone is a hormone that is responsive to external factors (e.g. competition, risk-taking), we explicitly control for omitted variable bias and reverse causality by using an instrumental variable approach. We use insulin as our primary instrument to account for endogeneity between testosterone and self-employment. This is because prior research has identified a relationship between insulin and testosterone but not between insulin and self-employment. Our results show that there is a positive association between total testosterone and self-employment. Robustness checks using bioavailable testosterone and another similar instrument (daily alcohol consumption) confirm this positive finding