Comparing the genetic population structure of two species of arctic lemmings: more local differentiation in Lemmus trimucronatus than in Dicrostonyx groenlandicus

Collared and brown lemmings ( Dicrostonyx groenlandicus and Lemmus trimucronatus ) are two largely sympatric and ecologically comparable species of arctic microtine rodents, differing however in some respects which allow us to hypothesise differences in the genetic structure of their populations. Collared lemmings are particularly well adapted to life at high latitude, they occasionally emerge to the surface of the snow and may disperse over larger distances than brown lemmings – possibly even over snow and ice. This should result in more local differentiation among populations of brown lemmings than among populations of collared lemmings. We compared the genetic population structure between the two lemming species in a fragmented landscape with small islands in the central Canadian Arctic using four microsatellite loci and partial mitochondrial control region sequences. Both types of genetic markers showed higher differentiation ( F _ST values) among local populations for brown lemmings than for collared lemmings. We discuss to what extent the observed genetic differences may be explained by differences in dispersal rates in addition to differences in average effective population size.     

The content and availability of information affects the evolution of social-information gathering strategies

Social animals can gather information by observing the other members of their groups. Strategies for gathering this type of social information have many components. In particular, an animal can vary the number of other animals it observes. European starlings (Sturnus vulgaris) in flight pay attention to a number of neighbors that allows the flock to reach consensus quickly and robustly. The birds may do this because being in such a flock confers benefits on its members, or the birds may use the strategy that is individually beneficial without regard for the flock’s structure. To understand when individual-level optimization results in a group-level optimum, we develop a model of animals gathering social information about environmental cues, where the cue can be about either predators or resources, and we analyze two processes through which the number of neighbors changes over time. We then identify the number of neighbors the birds use when the two dynamics reach equilibrium. First, we find that the equilibrium number of neighbors is much lower when the birds are learning about the presence of resources rather than predators. Second, when the information is about the presence of predators, we find that the equilibrium number of neighbors increases as the information becomes more widespread. Third, we find that an optimization process converges on strategies that allow the flock to reach consensus when the information is about the presence of abundant resources, but not when it is about the presence of scarce resources or predators.     

Evaluating the impact of scoring parameters on the structure of intra-specific genetic variation using RawGeno, an R package for automating AFLP scoring

Background  

Since the transfer and application of modern sequencing technologies to the analysis of amplified fragment-length polymorphisms (AFLP), evolutionary biologists have included an increasing number of samples and markers in their studies. Although justified in this context, the use of automated scoring procedures may result in technical biases that weaken the power and reliability of further analyses.     

Monitoring diabetes in patients with and without rheumatoid arthritis: a Medicare study

Introduction

Diabetes mellitus is a key predictor of mortality in rheumatoid arthritis (RA) patients. Both RA and diabetes increase the risk of cardiovascular disease (CVD), yet understanding of how comorbid RA impacts the receipt of guideline-based diabetes care is limited. The purpose of this study was to examine how the presence of RA affected hemoglobin A1C (A1c) and lipid measurement in older adults with diabetes.

Methods

Using a retrospective cohort approach, we identified beneficiaries ≥65 years old with diabetes from a 5% random national sample of 2004 to 2005 Medicare patients (N = 256,331), then examined whether these patients had comorbid RA and whether they received guideline recommended A1c and lipid testing in 2006. Multivariate logistic regression was used to examine the effect of RA on receiving guideline recommended testing, adjusting for baseline sociodemographics, comorbidities and health care utilization.

Results

Two percent of diabetes patients had comorbid RA (N = 5,572). Diabetes patients with comorbid RA were more likely than those without RA to have baseline cardiovascular disease (such as 17% more congestive heart failure), diabetes-related complications including kidney disease (19% higher), lower extremity ulcers (77% higher) and peripheral vascular disease (32% higher). In adjusted models, diabetes patients with RA were less likely to receive recommended A1c testing (odds ratio (OR) 0.84, CI 0.80 to 0.89) than those without RA, but were slightly more likely to receive lipid testing (OR 1.08, CI 1.01 to 1.16).

Conclusions

In older adults with diabetes, the presence of comorbid RA predicted lower rates of A1c testing but slightly improved lipid testing. Future research should examine strategies to improve A1c testing in patients with diabetes and RA, in light of increased CVD and microvascular risks in patients with both conditions.     

Diet,Obesity, and Hyperglycemia in LG/J and SM/J Mice

Objective: To examine the differential response of obesity‐ and diabetes‐related traits to a high‐ or low‐fat diet in LG/J and SM/J mice. We also examined food consumption in these strains. Research Methods and Procedures: Mice were placed on a high‐ or low‐fat diet after weaning. Animals were weighed once per week and subjected to glucose tolerance tests at 20 weeks. At sacrifice, fat pads and internal organs were removed along with serum samples. For food consumption, LG/J and SM/J mice of each sex were assigned to a high‐fat or low‐fat diet after reaching maturity. Mice were weighed three times per week, and food consumed was determined by subtraction. Results: LG/J animals consume more total food, but SM/J animals consume more food per gram of body weight. LG/J mice grow faster to 10 weeks but slower from 10 to 20 weeks, have higher cholesterol and free fatty acid levels, and have lower basal glucose levels and better response to a glucose challenge than SM/J mice. For most traits, SM/J mice respond more strongly to a high‐fat diet than LG/J mice, including body weight and growth, basal glucose levels, organ weights, fat distribution, and circulating triglycerides and cholesterol levels. Discussion: Obesity‐related phenotypes, as well as response to increased dietary fat, differ genetically between LG/J and SM/J and can, therefore, be mapped. This study indicates that the cross of SM/J and LG/J mice would be an excellent model system for the study of gene‐by‐diet interaction in obesity.     

Determination of acrylamide and glycidamide in rat plasma by reversed-phase high performance liquid chromatography

Acrylamide is a widely used monomer that produces peripheral neuropathy. It is metabolized to the epoxide, glycidamide, which is also considered to be neurotoxic. A new reversed-phase high-performance liquid chromatography (HPLC) method is described that permits simultaneous determination of acrylamide and glycidamide in rat plasma. Samples were deproteinized with acetonitrile and chromatography was performed using isocratic elution and UV absorption detection. The limits of detection for acrylamide and glycidamide were 0.05 and 0.25 μg/ml in plasma, respectively, and recovery of both analytes was greater than 90%. The assay was linear from 0.1 to 100 μg/ml for acrylamide and from 0.5 to 100 μg/ml for glycidamide. Variation over the range of the standard curve was less than 15%. The method was used to determine the concentration–time profiles of acrylamide and glycidamide in the plasma of acrylamide-treated rats.