城市生态系统承载力理论与评价方法

城市作为一个复杂的人工生态系统,其承载力的意义与生态学中的种群承载力意义有了很大差别。定义了城市生态系统承载力,强调其对维系城市生态系统健康的能动性特征,并在比较生物免疫力与城市生态系统承载力的相似性的基础上,构建了“城市生态系统承载力免疫学模型”作为其理论模型。在理论模型基础上设计其计量模型,分为天然承载力和获得性承载力两部分。并通过承载力与压力的相对变化趋势表达城市生态系统维系其健康水平的能力。以广州市为例,计算了广州市城市生态系统承载力与压力,获得二者的动态关系。结果表明,自1992年以来,广州市基本上处于一种经济发展与城市生态系统支持力同步发展的良性状态,所采取的发展模式具有可持续性     

广州、深圳地区蔬菜生产基地土壤中邻苯二甲酸酯(PAEs)研究

对广州 (含增城、花都 )和深圳地区的 9个代表性蔬菜生产基地进行调查采样 ,利用超声波提取 -硅胶柱净化 -气相色谱 /质谱联机检测技术 (GC/ MS) ,分析了土壤中属于 U.S.EPA优控污染物的 6种邻苯二甲酸酯 (PAEs)化合物。结果表明 ,6种PAEs化合物总含量 (Σ PAEs)在 3.0 0～ 4 5 .6 7mg/ kg之间 ,其中 37%样品的Σ PAEs在 10～ 2 0 mg/ kg,2 2 %样品的Σ PAEs在2 0～ 30 m g/ kg。各蔬菜基地中以联兴基地的 Σ PAEs平均值最高 (35 .6 2 m g/ kg) ;广清基地的 Σ PAEs平均值最低 (10 .31m g/kg)。各 PAEs化合物中以 DEHP的含量最高 ,Dn BP次之 ,两者共占 Σ PAEs的 90 %以上。BBP、DEP、DMP和 Dn OP的含量均在 2 .0 mg/ kg以下。与美国土壤 PAEs控制标准相比 ,除了 Dn OP外 ,其余 5个化合物均不同程度超标 ,其中 DEP、Dn OP、DEHP超标较普遍且较严重。但所有 PAEs化合物的含量均低于美国土壤 PAEs治理标准。总体上看 ,上述蔬菜基地土壤中PAEs的含量较高 ,说明受到了不同程度的污染     

Prognostic Value of E-cadherin-, CD44-, and MSH2-associated Nomograms in Patients With Stage II and III Colorectal Cancer

BACKGROUND: To evaluate the prognostic value of E-cadherin, CD44, and MSH2 expression for colorectal cancer (CRC) and construct nomograms that can predict prognosis. METHODS: We retrospectively analyzed the expression of E-cadherin, CD44, and MSH2 in 223 paraffin-embedded stage II and III CRC specimens using immunohistochemistry in the training cohort. Their prognostic values were assessed using Kaplan–Meier curves and univariate and multivariate COX regression models. Moreover, a number of risk factors were used to form nomograms to evaluate survival, and Harrell's concordance index (C-index) was used to evaluate the predictive accuracy. Further validation of the nomograms was performed in an independent cohort of 115 cases. RESULTS: Low E-cadherin expression and low CD44 expression were significantly associated with diminished overall survival (OS) and disease-free survival (DFS) in stage II and III CRC patients and patients with negative MSH2 expression had better clinical outcomes. Moreover, the multivariate COX analysis identified E-cadherin, CD44 and MSH2 expression as independent prognostic factors for DFS and OS. Using these three markers and three clinicopathological risk variables, two nomograms were constructed and externally validated for predicting OS and DFS (C-index: training cohort, 0.779 (95% CI 0.722–0.835) and 0.771 (0.720–0.822), respectively; validation cohort, 0.773 (0.709–0.837) and 0.670 (0.594–0.747), respectively). CONCLUSION: The expression levels of E-cadherin, CD44 and MSH2 were independent prognostic factors for stage II and III CRC patients. By incorporating clinicopathological features and these biomarkers, we have established two nomograms that could be used to make individualized predictions for OS and DFS.     

广州市花地湾市场龟鳖类调查

通过对广州市花地湾花鸟鱼虫市场贸易龟鳖类进行为期3年27次调查,共记录了9科29属41种或亚种,包括鳖科(Trionychidae)2属2种,两爪鳖科(Carettochelyidae)1属1种,龟科(Emydidae)4属5种,淡水龟科(Geoemydidae)10属18种,侧颈龟科(Chelidae)3属3种,动胸龟科(Kinosternidae)2属3种,鳄龟科(Chelydridae)2属2种,陆龟科(Testudinidae)4属6种,海龟科(Cheloniidae)1属1种。其中,国内龟鳖类共13种,外来物种共28种。受保护种类30种,所占比例达73.17%,部分龟类来源为野外捕捉。大量实体商家转入互联网进行精确营销,尤其是针对高价值的濒危种类,未来将着重对该隐蔽领域进行深入调查。     

Heavy metals in surface sediments of lakes in Guangzhou public parks in China and their relations with anthropogenic activities and urbanization

This study aimed to investigate the pollution of heavy metals in the sediments of park lakes in Guangzhou, which is a large city with rapid urbanization, industrialization, and dense population in South China. Thirty-two surface sediment samples were collected from seven lakes in different districts of this city. The concentrations and distributions of Cr, Ni, Cu, Zn, Cd, and Pb were measured to assess the level of enrichment and toxicity in the sediments. The enrichment factor showed that Pb and Zn showed severe enrichment in all lakes except for the Dafu Shan Forest Park (DFS), and the geo-accumulation index (I_geo) showed that all lakes were polluted with Cu, Pb, Cd, Ni, and Zn in different levels. The results of risk assessment indicated that the DFS located in the suburbs represented moderate risks; however, other lakes in the city central represented high or very high risks. Moreover, Cd had the primary contribution to the risk of the sediments' environment in urban lakes. Multivariate statistical analyses are carried out to explore the correlativity between heavy metals and human development indices. This study indicated that the levels of heavy metals' contamination and ecological risk of urban lakes in Guangzhou have a close relationship with anthropogenic activities.     

广州地区犬蝠的食性

2004年5月-2006年4月采用拾遗法、粪便内容物分析法及实地观察对广州地区常见的食果蝙蝠-犬蝠(Cynopterus sphinx)进行了食性研究。对26份食物残留物和粪便样品的分析结果表明:犬蝠的食物包含13科21种的植物果实,3科3种的植物叶片,如:蒲桃(Syzygium jambos)、蒲葵(Livistona subglobosa)及龙眼(Dimocarous longan)的果实。其食性随果实的成熟季节而出现明显的季节性变化,夏秋两季大量食用各种水果,而在食物欠缺的春冬两季则主要食用棕榈科蒲葵的种子。广州地区犬蝠的繁殖期在每年的5-10月。     

The intracellular NPxY motif is critical in maintaining the function and expression of human organic anion transporting polypeptide 1B1

Organic anion transporting polypeptides (OATPs, gene symbol SLCO) mediate sodium-independent transport of endogenous compounds such as bile salts, hormones and their conjugates as well as toxins and drugs. OATP1B1 is the major OATP specifically expressed at the basolateral membrane of human hepatocytes and many clinically important drugs have been shown to be substrates of the transporter. According to the computer-based hydropathy analysis, a large intracellular loop 3 (IL3) is situated between transmembrane domain 6 and 7 of OATPs, in which a conserved NPxY motif is found. In the current study, HEK293 cells expressing the HA-tagged OATP1B1 was utilized to investigate the role of the NPxY motif for the function and expression of the transporter. Alanine replacement of N335 or P336 retained substantial uptake function; while simultaneous mutation of these residues resulted in a double mutant that lost almost all the transport activity. On the other hand, Y338A showed >80% reduction for estrone-3-sulfate uptake. Plasma membrane protein analysis revealed that N335/P336A completely lost its cell surface protein expression; while that of Y338A is dramatically reduced. Further investigation with pharmacological inhibitors and immunocytochemistry demonstrated that N335/336A is detained in the Golgi apparatus and Y338A exhibited accelerated protein degradation rate compared to that of the wild-type. Conservative replacement of Y338 with phenylalanine fully recovered uptake and expression of the transporter. In summary, a new role was observed for the NPxY motif located in the IL3 of OATP1B1, which may affect processing and stability of the transporter.     

Obesity is a common soil for premature cardiac aging and heart diseases - Role of autophagy

The advance in medical technology and healthcare has dramatically improved the average human lifespan. One of the consequences for longevity is the high prevalence of aging-related chronic disorders such as cardiovascular diseases, cancer and metabolic abnormalities. As the composition of aging population is raising in western countries, heart failure remains the number one cause of death with a more severe impact in the elderly. Obesity and aging are the most critical risk factors for increased susceptibility to heart failure in developing and developed countries. Numerous population-based and experimental data have depicted a close relationship between the age-related diseases and obesity. There is an overall agreement that obesity is causally linked to the development of cardiovascular disorders and severe premature cardiac aging. Accumulating evidence indicates that autophagy plays an important role in obesity, cardiac aging and diseases. In this review, we will focus on the role of autophagy in obesity-related cardiac aging and diseases, and how it regulates age-dependent changes in the heart.     

Learning about protein hydrogen bonding by minimizing contrastive divergence

Defining the strength and geometry of hydrogen bonds in protein structures has been a challenging task since early days of structural biology. In this article, we apply a novel statistical machine learning technique, known as contrastive divergence, to efficiently estimate both the hydrogen bond strength and the geometric characteristics of strong interpeptide backbone hydrogen bonds, from a dataset of structures representing a variety of different protein folds. Despite the simplifying assumptions of the interatomic energy terms used, we determine the strength of these hydrogen bonds to be between 1.1 and 1.5 kcal/mol, in good agreement with earlier experimental estimates. The geometry of these strong backbone hydrogen bonds features an almost linear arrangement of all four atoms involved in hydrogen bond formation. We estimate that about a quarter of all hydrogen bond donors and acceptors participate in these strong interpeptide hydrogen bonds.     

The kestrel (Falco tinnunculus L.) in Berlin: investigation of breeding biology and feeding ecology

Approximately 200–250 pairs of kestrels (Falco tinnunculus) breed in Berlin, preferentially in nest boxes. From 2002 to 2004, ten monitoring sites (breeding sites) characterised by different housing structure, land utilisation, vegetation cover and degree of building density were studied in Berlin: four in the city centre, three in a mixed zone and three in the outskirts. All pairs bred in nest boxes, so the reproductive success could easily be determined. Pellets, and feathers of bird prey species, were collected during the breeding seasons, and the food spectrum was determined based on these remains. There was no significant difference in the reproductive success of the kestrels between the three zones. Data on the number of fledged young indicated a sufficient food supply. In total, 9 species of mice and shrews, 23 bird species and 31 beetle species were identified as prey of kestrels. Urban kestrels specialise in hunting birds if mice and shrews are not readily available, with the house sparrow (Passer domesticus) as the favoured prey bird. Of note are anthropogenic food items, such as cutlet bones, that were found only in the city centre. This shows that the kestrel can adapt itself to humans with regard to its diet. There was no urban gradient with regard to reproductive success, but there was with the composition of food, such as the domination of bird prey in the city centre. The number of individual items of bird prey decreased from the centre to the outskirts. In conclusion, the results show that the kestrel is an opportunistic species which survives well anywhere in the city of Berlin.