Structural Analysis of HMGD-DNA Complexes Reveals Influence of Intercalation on Sequence Selectivity and DNA Bending

The ubiquitous, eukaryotic, high-mobility group box (HMGB) chromosomal proteins promote many chromatin-mediated cellular activities through their non-sequence-specific binding and bending of DNA. Minor-groove DNA binding by the HMG box results in substantial DNA bending toward the major groove owing to electrostatic interactions, shape complementarity, and DNA intercalation that occurs at two sites. Here, the structures of the complexes formed with DNA by a partially DNA intercalation-deficient mutant of Drosophila melanogaster HMGD have been determined by X-ray crystallography at a resolution of 2.85 Å. The six proteins and 50 bp of DNA in the crystal structure revealed a variety of bound conformations. All of the proteins bound in the minor groove, bridging DNA molecules, presumably because these DNA regions are easily deformed. The loss of the primary site of DNA intercalation decreased overall DNA bending and shape complementarity. However, DNA bending at the secondary site of intercalation was retained and most protein-DNA contacts were preserved. The mode of binding resembles the HMGB1 box A-cisplatin-DNA complex, which also lacks a primary intercalating residue. This study provides new insights into the binding mechanisms used by HMG boxes to recognize varied DNA structures and sequences as well as modulate DNA structure and DNA bending.     

Cicada ear geometry: species and sex effects

Many insect species rely on their sense of audition to find a mate, to localize prey or to escape from a predator. Cicadas are particularly known for their loud call and the conspicuous tympanal hearing system located in their abdomen. The vibration pattern of the tympanal membrane (TM) has been investigated recently revealing mechanical properties specific to species and sex. Although TM size and shape is likely to affect these patterns, the geometry of the cicada ear has never been examined per se. Focusing on three Mediterranean cicada species, namely Cicadatra atra, Cicada orni and Lyristes plebejus, we investigated the structure of TM shape variation at two levels, within and across species. Applying an elliptic Fourier analysis to the outlines of both male and female TMs, we estimated sexual dimorphism and species effects. Cicadatra atra showed a large TM compared with its small size, probably as a result of selective constraints related to the role of the TM in sound production. Sexual dimorphism seemed to be greater than interspecific variation, indicating that constraints operating on sex might be more selective than those acting on species identification. In addition, C. orni appeared to be significantly different from the two other species. This morphological peculiarity could be related to the unique vibrational pattern of its membrane. This would establish for the first time a direct link between the shape and mechanism of a hearing organ. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 922–934.     

Phylogeography of the mottled spinefoot Siganus fuscescens: Pleistocene divergence and limited genetic connectivity across the Philippine archipelago

Historical isolation during Pleistocene low sea level periods is thought to have contributed to divergence among marine basin populations across the Coral Triangle. In the Philippine archipelago, populations in the South China Sea, Sulu Sea–inland seas, and Philippine Sea‐Celebes Sea basins might have been partially isolated. Meanwhile, present‐day broadscale oceanographic circulation patterns suggest connectivity between these basins. To evaluate hypotheses regarding the influence of historical and contemporary factors on genetic structure, phylogeographic patterns based on mitochondrial control region sequences for a reef‐associated fish, Siganus fuscescens, were analysed. Three distinct lineages were recovered. One lineage was identified as the morphologically similar species Siganus canaliculatus, while two lineages are monophyletic with S. fuscescens. Clade divergence and demographic expansion in S. fuscescens occurred during the Pleistocene. A strong signal of latitudinal structure was detected (Φ_CT = 0.188), driven by marked differences in clade distribution: one clade is widely distributed (clade A), while a second clade (clade B) has a restricted northern distribution. Regional structure of clade A is consistent with the basin isolation hypothesis (Φ_CT = 0.040) and suggests isolation of the South China Sea (Φ_CT = 0.091). Fine‐scale structure was observed in the South China Sea and south Philippine Sea, while Sulu Sea and inland seas were unstructured. Genetic structure across multiple spatial scales (archipelagic, regional, and fine‐scale within basins) suggests the influence of vicariant barriers and contemporary limits to gene flow in S. fuscescens that may be influenced by oceanographic circulation, geographical distance between available habitats, and latitudinal temperature differences.     

<Emphasis Type="Italic">In vitro</Emphasis> and <Emphasis Type="Italic">ex vivo</Emphasis> effect of hyaluronic acid on erythrocyte flow properties

Background  

Hyaluronic acid (HA) is present in many tissues; its presence in serum may be related to certain inflammatory conditions, tissue damage, sepsis, liver malfunction and some malignancies. In the present work, our goal was to investigate the significance of hyaluronic acid effect on erythrocyte flow properties. Therefore we performed in vitro experiments incubating red blood cells (RBCs) with several HA concentrations. Afterwards, in order to corroborate the pathophysiological significance of the results obtained, we replicated the in vitro experiment with ex vivo RBCs from diagnosed rheumatoid arthritis (RA) patients, a serum HA-increasing pathology.     

Acidic NAADP-sensitive Calcium Stores in the Endothelium: AGONIST-SPECIFIC RECRUITMENT AND ROLE IN REGULATING BLOOD PRESSURE*

Accumulating evidence implicates nicotinic acid adenine dinucleotide phosphate (NAADP) in the control of Ca²⁺-dependent functions. Little, however, is known concerning its role in the vascular endothelium, a major regulator of blood pressure. Here, we show that NAADP acetoxymethyl ester (NAADP-AM), a cell-permeant NAADP analog, increases cytosolic Ca²⁺ concentration in aortic endothelial cells. We demonstrate that these signals and those evoked by acetylcholine are blocked by disrupting acidic organelles with bafilomycin A1. In contrast, Ca²⁺ signals in response to thrombin are only partially inhibited by bafilomycin A1 treatment, and those to ATP were insensitive, suggesting that recruitment of acidic stores is agonist-specific. We further show that NAADP-evoked Ca²⁺ signals hyperpolarize endothelial cells and generate NO. Additionally, we demonstrate that NAADP dilates aortic rings in an endothelium- and NO-dependent manner. Finally, we show that intravenous administration of NAADP-AM into anesthetized rats decreases mean arterial pressure. Our data extend the actions of NAADP to the endothelium both in vitro and in vivo, pointing to a previously unrecognized role for this messenger in controlling blood pressure.     

Off-territory movement of male American Redstarts (Setophaga ruticilla) in a fragmented agricultural landscape is related to song rate, mating status and access to females

Male songbirds often move off-territory to pursue extra-pair fertilizations. This movement represents a trade-off between paternity gain and loss and can be influenced by male quality and access to fertile females. Access to females could be reduced in fragmented landscapes that have small patches and low connectedness. We studied movement and extra-pair fertilization success of radio-tracked male American Redstarts (Setophaga ruticilla) in forest patches in an agricultural landscape in Alberta, Canada, over 2 years. Males spent an average of 18% of their time off-territory, mostly intruding onto adjacent territories and rarely moving between patches. They averaged 0.8 trips/h, with mean trip duration of 17 min and mean trip distance of 104 m. Less time was spent off-territory when their mate was nest-building and males intruded most often onto territories with nest-building females. Males with higher song rates and more nearby females intruded most onto other territories. Monogamous males in better condition with higher song rates spent the most time off-territory. However, males with more nearby females and higher local breeding synchrony spent the least time off-territory, suggesting these males face a trade-off between seeking extra-pair fertilizations and protecting against cuckoldry. Forest cover was not an important predictor of movement. Investment in off-territory movement did not predict extra-pair fertilization success or probability of cuckoldry. However, few tracked males achieved extra-pair fertilizations (1/22 tracked males vs 18/57 non-tracked males), possibly an artefact of low sample size or the effect of radio transmitters on female choice.     

1590名农村中老年人生存质量调查分析(英文)

目的:采用SF-36量表中文版评价农村中老年人生存质量,并为提高农村中老年人的生存质量和健康水平提供科学依据和建议。方法:采用随机抽样的方法,采用面对面访谈的形式,记分方法参照国际生存质量评价计划(IQOLA)的制定标准,评价其生理和心理健康状况。结果:1590名农村中老年人男性生存质量得分高于女性。经济水平对农村中老年人的生理健康的影响大于对其心理健康的影响。配偶健在的农村中老年人的各维度得分均高于无配偶者。农村中老年人的各维度得分随教育水平的升高呈升高趋势。结论:农村中老年人的生存质量与年龄成负相关,同时也受文化程度和经济水平等多个因素的影响。因而,对农村中老年人这一弱势群体应该给予更多关注。     

Structural model analysis of multiple quantitative traits

We introduce a method for the analysis of multilocus, multitrait genetic data that provides an intuitive and precise characterization of genetic architecture. We show that it is possible to infer the magnitude and direction of causal relationships among multiple correlated phenotypes and illustrate the technique using body composition and bone density data from mouse intercross populations. Using these techniques we are able to distinguish genetic loci that affect adiposity from those that affect overall body size and thus reveal a shortcoming of standardized measures such as body mass index that are widely used in obesity research. The identification of causal networks sheds light on the nature of genetic heterogeneity and pleiotropy in complex genetic systems.     

Characterization of a chloride current in the larval epidermis of the beetle Tenebrio molitor

Voltage-clamp analysis of single cuticle-attached epidermal cells dissected from the newly-ecdysed mealworm revealed the presence of a large inwardly-rectifying anion (i.e. outwardly-going) current. In many cells this current formed spontaneously on breaking into the cell with the patch pipette when the bath solution was isoosmotic with the pipette solution (415 mosmol/l). The current was evoked rapidly by electrical stimulation or by bathing the cells in hyposmotic saline (335 mosmol/l). The reversal potential of the activated current shifted in agreement with the Nernst prediction for Cl(-) when the transmembrane chloride gradient was altered by partially substituting bath or patch pipette Cl(-) with gluconate(-). Substitution of Na(+) with choline(+) or K(+) with TEA and Ba(+) in the bath or pipette solutions did not alter the reversal potential. Addition of 200 &mgr;mol/l cyclic AMP or 1 mmol/l cyclic GMP to the pipette solution increased the initial current strength and reduced the time taken to reach half peak amplitude from 117 sec to 49 sec and 41 sec, respectively. Cyclic AMP also raised the threshold at which the current developed under hyperosmotic conditions by about 20 mosmol/l. Addition of the Cl(-) channel blockers diphenylamine-2-carboxylic acid (200 &mgr;mmol/l) and diisothiocyanostilbene-2,2'-disulphonic acid (250 &mgr;mol/l) to the bath solution reduced the inwardly-rectifying anion current by 50%. This current was barely detectable in cells prepared from the mid-instar integument. This non-constitutive pattern of expression suggests that cellular Cl(-) efflux (and that of other anions) may be required during moult-cycle specific processes such as moulting fluid formation and cell volume regulation. As the strength of the epidermal anion current could be raised by the exogenous application of cytosolic cyclic nucleotides, the activity of the anion channels responsible for this current may normally be regulated by yet-to-be-identified hormone(s) or neuropeptide(s) acting on this tissue.