Density-dependence and within-host competition in a semelparous parasite of leaf-cutting ants

Background  

Parasite heterogeneity and within-host competition are thought to be important factors influencing the dynamics of host-parasite relationships. Yet, while there have been many theoretical investigations of how these factors may act, empirical data is more limited. We investigated the effects of parasite density and heterogeneity on parasite virulence and fitness using four strains of the entomopathogenic fungus, Metarhizium anisopliae var. anisopliae, and its leaf-cutting ant host Acromyrmex echinatior as the model system.     

Did elevated atmospheric CO2 alter soil mineral weathering?: an analysis of 5‐year soil water chemistry data at Duke FACE study

A principal driver of biogeochemical weathering of the Earth's crust is soil CO₂, produced mainly by plant roots and soil heterotrophs, a water‐soluble gas that forms carbonic acid which reacts with soil minerals via cation exchange and mineral dissolution. We examined effects of elevated atmospheric CO₂ (ambient + 200 ppmv) in a young pine forest on belowground carbonic acid chemistry of soil water. Soil water was collected every 2–3 weeks over a 5‐year period from O horizons and at 15, 70, and 200 cm in mineral soils at the Duke free air CO₂ enrichment facility located in a warm temperate climate in North Carolina, USA. Concentrations of major ions were volume‐weighted and statistically analyzed using linear mixed‐effects models. Experimental interest was placed on interactive effects of CO₂ treatment and time: to test effects of gradually increasing CO₂ in deep soil horizons where CO₂ is highest in concentration, and to protect against inherent plot‐to‐plot differences in soil water chemistry being interpreted as responses to CO₂ treatments. Although significant time‐dependent interactive effects were reported for soil CO₂, interactive effects were not significant for soil water constituents. These data, combined with limited pretreatment sampling of soil water chemistry and recently determined large heterogeneity in soil solid chemistry at this site, indicate that CO₂‐weathering response is smaller than the more‐than‐doubling of weathering reported previously and that increases in weathering are masked by in situ soil heterogeneity. Although the hypothesis that elevated CO₂ increases cation leaching and weathering dissolution is supported in laboratory experiments and field studies, quantifying the stimulation of chemical weathering by elevated atmospheric CO₂ remains to be tested rigorously in the field.     

External microstructure of the ambrosia beetle Platypus koryoensis (Coleoptera: Curculionidae: Platypodinae)

Platypus koryoensis is a minute ambrosia beetle found in forests. It can cause significant economic damage to oak trees. Recently in Korea, it has been reported as a major pest of oak trees, because it causes sooty mold of oak by introducing the pathogenic fungus Raffaelea sp. In this paper, we demonstrate the fine structural aspects of the external body of the ambrosia beetle using field emission scanning electron microscopy, as a part of basic research into this pest so that strategies for its control might be developed. This beetle has a sensory system well developed to respond to both visual and chemical stimuli. Both sexes have a pair of faceted compound eyes and a pair of knobbed antennae, but simple eyes are absent. The mouthparts on its distinct snouts are effective devices for penetration and for boring holes. The mouthparts consist of the labrum, a pair of mandibles, a pair of maxillae and the labium. Both the maxillary and the labial palpi have the function of directing the food to the mouth and holding it while the mandibles chew the food. The distal ends of these palpi are flattened and have shovel‐like setae. The thorax has a particularly hard exoskeleton and hard elytra, including powerful muscles that operate both the wings and the legs. The legs are multi‐segmented and have a strong femur and tibia, including one pair of claws on the end of each tarsal segment. Characteristically, both male and female beetles have mycangial cavities for storing spores and other microorganisms, but only females have three pairs of large depressions on their dorsal thorax.     

Phylogenetic relationships, taxonomy, character evolution and biogeography of the lacertid lizards of the genus Takydromus (Reptilia: Squamata): a molecular perspective

Historical relationships were inferred for the oriental lizards of the genus Takydromus Daudin 1802 (Lacertidae) on the basis of DNA sequences. Of the 17 species currently recognized for the genus, 13 species represented by 42 specimens from 29 localities were examined. Maximum-likelihood and maximum-parsimony analyses of data for 829 aligned sites from parts of the mitochondrial 12S and 16S rRNA genes yielded relationships that, while showing no substantial discrepancy with each other, were strikingly different from a currently prevailing phylogenetic hypothesis from a parsimony analysis of morphological characters. Based on the results of these molecular analyses, supplemented by results of the morphological analysis that offered robust evidence for positions of two additional species ( T. khasiensis and T. sylvaticus ), the following interrelationships were hypothesized as the most preferred phylogeny: ( kuehnei ( sexlineatus khasiensis ))( tachydromoides (( smaragdinus ( sauteri ( dorsalis sylvaticus ))) ( amurensis ((( formosanus wolteri ) hsuehshanensis )( toyamai ( septentrionalis stejnegeri )))))). These interrelationships indicate: (1) invalidity of Platyplacopus Boulenger 1917 , which was recently resurrected as a subgenus of Takydromus on the basis of the morphological analysis; (2) homoplasy in states of some morphological characters, such as green dorsal coloration, that were considered as synapomorphs of certain nodes in the morphological analysis; and (3) involvement of the genus in a series of vicariances in both the continental and insular parts of eastern Eurasia. Due to the paucity of available samples, phylogenetic status of T. intermedius and T. haughtonianus remain to be examined in future studies.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 76 , 493–509.     

Statin-Associated Polymyalgia Rheumatica. An Analysis Using WHO Global Individual Case Safety Database: A Case/Non-Case Approach

Objective

To assess whether there is an association between statin use and the occurrence of polymyalgia rheumatic (PMR) in the spontaneous reporting database of the World Health Organisation (WHO).

Methods

We conducted a case/non-case study based on individual case safety reports (ICSR) in the WHO global ICSR database (VigiBase). Case reports containing the adverse event term polymyalgia rheumatica (WHOART or MedDRA Preferred Term) were defined as cases. Non-cases were all case reports containing other adverse event terms. Each case was matched to five non-cases by age, gender, and time of reporting. Case reports regarding a statin as suspected or concomitant drug were identified using the Anatomical Therapeutic Chemical (ATC) classification. Multivariate logistic regression was used to calculate reporting odds ratios (RORs) with 95% confidence intervals (CI).

Results

We identified 327 reports of PMR as cases and 1635 reports of other ADRs as non-cases. Among cases, statins were more frequently reported as suspected agent (29.4%) compared to non-cases (2.9%). After adjustment for several covariates, statins were significantly associated with reports of PMR (ROR 14.21; 95% CI 9.89–20.85).

Conclusion

The results of this study lends support to previous anecdotal case reports in the literature suggesting that the use of a statin may be associated with the occurrence of PMR. Further studies are needed to study the strength of the association in more detail and to elucidate the underlying mechanism.     

Extensive genetic divergence in the East Asian natricine snake,Rhabdophis tigrinus (Serpentes: Colubridae), with special reference to prominent geographical differentiation of the mitochondrial cytochrome b gene in Japanese populations

We investigated intraspecific phylogenetic relationships in the natricine snake, Rhabdophis tigrinus. A partial sequence of mitochondrial cytochrome b gene (990 bp) was sequenced for 220 individuals from 112 populations. The phylogeny indicated monophyly of the Japanese populations against the continental and Taiwanese populations, sister relationships of the Japanese and continental populations, and monophyly of the whole species. The results strongly suggested substantial genetic divergences among population assemblages from those three regions. We thus consider both lateralis from the continent, which is often synonymized to R. tigrinus, and formosanus from Taiwan, which is usually regarded as a subspecies of the latter, as distinct full species based on the evolutionary species concept. In the Japanese populations, haplotypes were classified to in two major clades (I and II) that were parapatric to each other. Clade I consisted of three distinct subclades (I‐A, I‐B, and I‐C), of which the former two were parapatric with each other, whereas the latter was sympatric with each of the former two subclades. The geographical haplotype structure exhibited by the Japanese populations is likely to have resulted from a series of allopatric differentiations with rapid range extensions of resultant lineages, leading to secondary contact or further admixture of mitochondrial haplotype clades and subclades. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 395–408.     

Pharmacogenetics of glucose-lowering drug treatment: a systematic review

Intensive blood glucose lowering can significantly reduce the risk of micro- and macrovascular complications in patients with diabetes mellitus. However, 30% of all treated patients do not achieve optimal blood glucose levels. Genetic factors may influence the response to glucose-lowering medication. A search of MEDLINE-indexed literature published between January 1966 and July 2007 revealed 37 studies reporting data on genetic polymorphisms and response to glucose-lowering drugs. Most studies involving cytochrome P450 (CYP) genes had small sample sizes (21 studies <50 subjects) and were among healthy volunteers. Multiple studies indicated that the CYP2C9 *3 allele (Ile359Leu polymorphism) was associated with decreased clearance of sulfonylurea drugs. Supporting this, one study reported an increased insulin secretion in CYP2C9*3 allele carriers when using the sulfonylurea agent glyburide. The CYP2C9*3 allele was also associated with a decreased clearance of meglitinides, whereas the CYP2C8*3 (Arg139Lys; Lys399Arg) variant increased the clearance of meglitinides. Polymorphisms in genes encoding the inwardly rectifying potassium channel Kir6.2 (KCNJ11) and the insulin receptor substrate-1 (IRS1) were reported to be associated with an increased risk of (secondary) failure to respond to sulfonylurea therapy. A significant decrease in fasting plasma glucose and hemoglobin A(1c) (HbA(1c)) in response to rosiglitazone was seen in subjects carrying the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor-gamma (PPARG) gene. Conversely, carriers of this polymorphism also had a higher conversion to diabetes mellitus when treated with acarbose; this effect was also seen in adiponectin (ADIPOQ) gene polymorphism carriers. Future studies with adequate sample sizes in which several SNPs in multiple candidate genes are genotyped in patients with diabetes should provide reliable information on genetic variants and response to glucose-lowering drugs.     

A Microscopic Characterization of the Infection of Green and Red Pepper Fruits by an Isolate of Colletotrichum gloeosporioides

Colletotrichum gloeosporioides is a common pathogenic fungus in many plants. To investigate the specificity of the isolate C. gloeosporioides to green fruits, fungal behaviours and anthracnose development on green and red pepper fruits were compared using light and stereo microscopic techniques. When the isolate of C. gloeosporioides was inoculated on both green and red fruits, conidial germination, appressoria, and infection hyphae were observed on both fruits within 24 h after inoculation. The fungal invasion and colonization continued to the epidermal cells of green fruits, but not to those of red ones. Initial anthracnose symptoms were detected only on green fruits at 2 days after inoculation resulting in typical sunken necrosis within 5 days after inoculation. Thus the specificity of the isolate to green fruits may be due to successful invasion and colonization of the infection hyphae from appressoria into the epidermal cells through epicuticular layers of green pepper fnats, but not on red ones.