Genetic perspectives on northern population cycles: bridging the gap between theory and empirical studies

Many key species in northern ecosystems are characterised by high‐amplitude cyclic population demography. In 1924, Charles Elton described the ecology and evolution of cyclic populations in a classic paper and, since then, a major focus has been the underlying causes of population cycles. Elton hypothesised that fluctuations reduced population genetic variation and influenced the direction of selection pressures. In concordance with Elton, present theories concern the direct consequences of population cycles for genetic structure due to the processes of genetic drift and selection, but also include feedback models of genetic composition on population dynamics. Most of these theories gained mathematical support during the 1970s and onwards, but due to methodological drawbacks, difficulties in long‐term sampling and a complex interplay between microevolutionary processes, clear empirical data allowing the testing of these predictions are still scarce. Current genetic tools allow for estimates of genetic variation and identification of adaptive genomic regions, making this an ideal time to revisit this subject. Herein, we attempt to contribute towards a consensus regarding the enigma described by Elton almost 90 years ago. We present nine predictions covering the direct and genetic feedback consequences of population cycles on genetic variation and population structure, and review the empirical evidence. Generally, empirical support for the predictions was low and scattered, with obvious gaps in the understanding of basic population processes. We conclude that genetic variation in northern cyclic populations generally is high and that the geographic distribution and amount of diversity are usually suggested to be determined by various forms of context‐ and density‐dependent dispersal exceeding the impact of genetic drift. Furthermore, we found few clear signatures of selection determining genetic composition in cyclic populations. Dispersal is assumed to have a strong impact on genetic structuring and we suggest that the signatures of other microevolutionary processes such as genetic drift and selection are weaker and have been over‐shadowed by density‐dependent dispersal. We emphasise that basic biological and demographical questions still need to be answered and stress the importance of extensive sampling, appropriate choice of tools and the value of standardised protocols.     

Association of Hepatocyte Nuclear Factor 4 Alpha Polymorphisms with Type 2 Diabetes With or Without Metabolic Syndrome in Malaysia

This study investigated the association of hepatocyte nuclear factor 4 (HNF4) alpha single nucleotide polymorphisms (SNPs) with type 2 diabetes with or without metabolic syndrome in Malaysia. Nine HNF4 alpha SNPs were genotyped in 390 type 2 diabetic subjects with metabolic syndrome, 135 type 2 diabetic subjects without metabolic syndrome, and 160 control subjects. The SNPs rs4810424, rs1884613, and rs2144908 were associated with protection against type 2 diabetes without metabolic syndrome (recessive P = 0.018, OR 0.32; P = 0.004, OR 0.25; P = 0.005, OR 0.24, respectively). The 6-SNP haplotype2 CCCGTC containing the risk genotype of these SNPs was associated with higher risk for type 2 diabetes with or without metabolic syndrome (P = 0.002, OR 2.2; P = 0.004, OR 3.1). These data suggest that HNF4 alpha SNPs and haplotypes contributed to increased type 2 diabetes risk in the Malaysian population.     

Microsatellite markers for Saussurea gnaphalodes (Asteraceae), a native Himalayan mountain species

? Premise of the study: Microsatellite markers were developed in Saussurea gnaphalodes to investigate its genetic variation and population structure. ? Methods and Results: Using the combined biotin capture method, 46 microsatellite primer sets were isolated and characterized across 48 S. gnaphalodes individuals from three Tibetan populations. Seventeen of these markers showed polymorphism, and the number of alleles ranged from two to 17. The observed and expected heterozygosities per population ranged from 0 to 0.938 and from 0 to 0.905, respectively. ? Conclusions: These markers provide a useful tool to investigate the genetic diversity and population structure of S. gnaphalodes, and to facilitate further studies on conservation and utilization.     

Acute paralysis viruses of the honey bee

<正>The alarming decline of honey bee(Apis mellifera)colonies in the last decade drove the attention and research to several pathogens of the honey bee including viruses.Viruses challenge the development of healthy and robust colonies since they manage to prevail in an asymptomatic mode and reemerge in acute infections following external stresses,as well as they are able to infect new healthy colonies(de Miranda J R,et al.,2010a;de Miranda J R,et al.,2010b;Di Prisco G,et al.,2013;Nazzi F,et al.,2012;Yang X L,et al.,2005).     

Oxidative status and reduced glutathione levels in premature coronary artery disease and coronary artery disease

Identifying patients at risk of developing premature coronary artery disease (PCAD) which occurs at age below 45 years old and constitutes approximately 7–10% of coronary artery disease (CAD) worldwide remains a problem. Oxidative stress has been proposed as a crucial step in the early development of PCAD. This study was conducted to determine the oxidative status of PCAD in comparison to CAD patients. PCAD (<45 years old) and CAD (>60 years old) patients were recruited with age-matched controls (n?=?30, each group). DNA damage score, plasma malondialdehyde (MDA) and protein carbonyl content were measured for oxidative damage markers. Antioxidants such as erythrocyte glutathione (GSH), oxidised glutathione (GSSG), and glutathione peroxidase activity (GPx), superoxide dismutase (SOD) and catalase (CAT) were also determined. DNA damage score and protein carbonyl content were significantly higher in both PCAD and CAD when compared to age-matched controls while MDA level was increased only in PCAD (p<.05). In contrast, GSH, GSH/GSSG ratio, α-tocotrienol isomer, and GPx activity were significantly decreased, but only in PCAD when compared to age-matched controls. The decrease in GSH was associated with PCAD (OR?=?0.569 95%CI [0.375???0.864], p?=?.008) and cut-off values of 6.69?μM with areas under the ROC curves (AUROC) 95%CI: 0.88 [0.80–0.96] (sensitivity of 83.3%; specificity of 80%). However, there were no significant differences in SOD and CAT activities in all groups. A higher level of oxidative stress indicated by elevated MDA levels and low levels of GSH, α-tocotrienol and GPx activity in patients below 45 years old may play a role in the development of PCAD and has potential as biomarkers for PCAD.     

A New Cold-Adapted,Organic Solvent Stable Lipase from Mesophilic Staphylococcus epidermidis AT2

The gene encoding a cold-adapted, organic solvent stable lipase from a local soil-isolate, mesophilic Staphylococcus epidermidis AT2 was expressed in a prokaryotic system. A two-step purification of AT2 lipase was achieved using butyl sepharose and DEAE sepharose column chromatography. The final recovery and purification fold were 47.09 % and 3.45, respectively. The molecular mass of the purified lipase was estimated to be 43 kDa. AT2 lipase was found to be optimally active at pH 8 and stable at pH 6–9. Interestingly, this enzyme demonstrated remarkable stability at cold temperature (<30 °C) and exhibited optimal activity at a temperature of 25 °C. A significant enhancement of the lipolytic activity was observed in the presence of Ca²⁺, Tween 60 and Tween 80. Phenylmethylsulfonylfluoride, a well known serine inhibitor did not cause complete inhibition of the enzymatic activity. AT2 lipase exhibited excellent preferences towards long chain triglycerides and natural oils. The lipolytic activity was stimulated by dimethylsulfoxide and diethyl ether, while more than 50 % of its activity was retained in methanol, ethanol, acetone, toluene, and n-hexane. Taken together, AT2 lipase revealed highly attractive biochemical properties especially because of its stability at low temperature and in organic solvents.