Patterns of Adaptive and Neutral Diversity Identify the Xiaoxiangling Mountains as a Refuge for the Giant Panda

Genetic variation plays a significant role in maintaining the evolutionary potential of a species. Comparing the patterns of adaptive and neutral diversity in extant populations is useful for understanding the local adaptations of a species. In this study, we determined the fine-scale genetic structure of 6 extant populations of the giant panda (Ailuropoda melanoleuca) using mtDNA and DNA fingerprints, and then overlaid adaptive variations in 6 functional Aime-MHC class II genes (DRA, DRB3, DQA1, DQA2, DQB1, and DQB2) on this framework. We found that: (1) analysis of the mtDNA and DNA fingerprint-based networks of the 6 populations identified the independent evolutionary histories of the 2 panda subspecies; (2) the basal (ancestral) branches of the fingerprint-based Sichuan-derived network all originated from the smallest Xiaoxiangling (XXL) population, suggesting the status of a glacial refuge in XXL; (3) the MHC variations among the tested populations showed that the XXL population exhibited extraordinary high levels of MHC diversity in allelic richness, which is consistent with the diversity characteristics of a glacial refuge; (4) the phylogenetic tree showed that the basal clades of giant panda DQB sequences were all occupied by XXL-specific sequences, providing evidence for the ancestor-resembling traits of XXL. Finally, we found that the giant panda had many more DQ alleles than DR alleles (33∶13), contrary to other mammals, and that the XXL refuge showed special characteristics in the DQB loci, with 7 DQB members of 9 XXL-unique alleles. Thus, this study identified XXL as a glacial refuge, specifically harboring the most number of primitive DQB alleles.     

Theoretical insight into the multiple interactions of quinazoline inhibitors with breast cancer resistance protein (BCRP/ABCG2)

Communicated by Ramaswamy H. Sarma     

Ultrasonic Elastography Research Based on a Multicenter Study: Adding Strain Ratio after 5-Point Scoring Evaluation or Not

Background

This study aimed to confirm whether strain ratio should be added after evaluation of lesions with 5-point elasticity scoring for differentiating benign and malignant breast lesions on ultrasonographic elastography(UE).

Materials and Methods

From June 2010 to March 2012, 1080 consecutive female patients with breast lesions were recruited into a multicenter retrospective study, which involved 8 centers across China. Each institutional ethic review board approved the study, and all the patients gave written informed consent. All the patients underwent the UE procedure and the strain ratios were calculated and the final diagnosis was made by histological findings. The sensitivity, specificity, accuracy, PPV and NPV were calculated for each of the two evaluation systems and the areas under the ROC curve were compared.

Results

The strain ratios of benign lesions (mean, 2.6±2.0) and malignant lesions (mean,7.9±5.8) were significantly different (p <0.01). When the cutoff point was 3.01, strain ratio method had 79.8% sensitivity, 82.8% specificity, and 81.3% accuracy, while the 5-point scoring method had 93.1% sensitivity, 73.0% specificity, and 76.8% accuracy. The areas under the ROC curve with the strain ratio method and 5-point scoring method were 0.863 and 0.865, respectively(p>0.05). The strain ratio method shows better a diagnosis performance of the lesions with elasticity score 3 and 4.

Conclusions

Although the two UE methods have similar diagnostic performance, separate calculation of the strain ratios seems compulsory, especially for the large solid breast lesions and the lesions with elasticity score 3 and 4.     

荔枝蝽生物学及防治技术的研究进展

荔枝蝽Tessaratoma papillasa是荔枝和龙眼生产中的重要害虫,在中国南方及东南亚地区危害严重.该虫以若虫及成虫吸食寄主植物的嫩芽、嫩梢、花穗和幼果,成虫和3龄以上若虫是传播龙眼鬼帚病病原体的传病介体昆虫.本文综述了近60年来国内荔枝蝽的研究情况,旨在为广大科研工作者提供更详尽的荔枝蝽研究现状,以期为该虫...     

New insights into iron acquisition by cyanobacteria: an essential role for ExbB-ExbD complex in inorganic iron uptake

Cyanobacteria are globally important primary producers that have an exceptionally large iron requirement for photosynthesis. In many aquatic ecosystems, the levels of dissolved iron are so low and some of the chemical species so unreactive that growth of cyanobacteria is impaired. Pathways of iron uptake through cyanobacterial membranes are now being elucidated, but the molecular details are still largely unknown. Here we report that the non-siderophore-producing cyanobacterium Synechocystis sp. PCC 6803 contains three exbB-exbD gene clusters that are obligatorily required for growth and are involved in iron acquisition. The three exbB-exbDs are redundant, but single and double mutants have reduced rates of iron uptake compared with wild-type cells, and the triple mutant appeared to be lethal. Short-term measurements in chemically well-defined medium show that iron uptake by Synechocystis depends on inorganic iron (Fe′) concentration and ExbB-ExbD complexes are essentially required for the Fe′ transport process. Although transport of iron bound to a model siderophore, ferrioxamine B, is also reduced in the exbB-exbD mutants, the rate of uptake at similar total [Fe] is about 800-fold slower than Fe′, suggesting that hydroxamate siderophore iron uptake may be less ecologically relevant than free iron. These results provide the first evidence that ExbB-ExbD is involved in inorganic iron uptake and is an essential part of the iron acquisition pathway in cyanobacteria. The involvement of an ExbB-ExbD system for inorganic iron uptake may allow cyanobacteria to more tightly maintain iron homeostasis, particularly in variable environments where iron concentrations range from limiting to sufficient.     

克隆植物蛇莓基株的分子鉴定

采用随机扩增序列区间(ISSR)分子标记技术对蛇莓基株进行鉴定,结果表明6个ISSR引物在22个分株中共扩增出62个条带,每个引物扩增的条带数为4～16条,平均每个引物扩增的条带数为10.3条。采用6种引物对22个克隆分株的DNA扩增共产生28种带谱类型,其中有9种带谱为特异性带谱。综合分析这些带谱,确知这22个克隆分株分属16个基株。由带型可知,通过6个引物中的4种引物就可以把所有的基株鉴定出来,表明ISSR技术在分子水平上鉴定蛇莓的克隆基株是一种行之有效的方法。同时每个引物扩增出来的条带的多态性比例也比较高,平均达到90.3%。     

巢蛋白基因沉默通过激活细胞周期依赖性激酶（cdk5）促进大鼠神经胶质瘤细胞C6的迁移和增殖

中间纤维蛋白巢蛋白(nestin)在各种胚胎前体细胞及成熟组织中均有表达.近年一些研究显示,巢蛋白的表达上调和一些恶性肿瘤的病理特征有相关性.但是,巢蛋白在干细胞分化及肿瘤发生中的作用还不为人知.在本研究中,我们运用短发卡状的RNA为工具,以大鼠神经胶质瘤细胞系C6为模型,对巢蛋白的功能进行了研究.划痕实验和迁移实验的结果均显示,巢蛋白基因沉默可以促进C6细胞的迁移.同时,BrdU渗入实验显示,此过程伴随着细胞增殖的增加.进一步研究显示,细胞周期依赖性激酶cdk5的活性在此过程中有显著的增加.此外,巢蛋白基因沉默所引起的迁移改变可以被cdk5特异性抑制剂roscovitine所回复, 而对细胞增殖则没有显著影响.综上所述,本研究揭示了巢蛋白基因沉默与神经胶质瘤细胞的迁移和增殖相关,而cdk5是此过程的重要调节因子.     

Human red blood cell aging: correlative changes in surface charge and cell properties

Red blood cells (RBCs) during microcirculation, aging and storage, lose N-acetylneuraminic acid (NANA) and other biomaterials thereby altering cell structures, some properties and functions. Such cell damage very likely underlies the serious adverse effects of blood transfusion. However, a controversy has remained since 1961-1977 as to whether with aging, the RBCs, suffering loss of NANA, do have a decreased charge density. Any correlation between the changes in the cell properties with cell aging is also not clear. Therefore, to remove the ambiguity and uncertainty, we carried out multiparameteric studies on Percoll fractions of blood of 38 volunteers (lightest-young-Y-RBCs, densest-old-O-RBCs, two middle fractions).We found that there were striking differences between the properties of Y-RBCs and O-RBCs. The ζ-potential of Y-RBCs decreased gradually with aging. Studies in parallel on RBC fractions incubated with both positively charged quantum dots and Sambucus Nigra-fluorescein isothiocyanate (FITC) along with their ζ-potentials provide for the first time direct visual evidence about the lesser amount of charge density and NANA on O-RBCs, and a collinear decrease in their respective ζ-potentials. Close correlation was found between the surface charge on an aging RBC and its structure and functions, from the cell morphology, the membrane deformability to the intracellular Hb structure and oxidation ability. This quantitative approach not only clarifies the picture but also has implications in biology and medicine.