Evaluation of the flocculation potential and characterization of bioflocculant produced by Micrococcus sp. Leo

Bioflocculants are safe, biodegradable and environmentally friendly biopolymeric materials. These merits portend it as preferred alternative to inorganic and organic synthetic polymeric flocculants. The culture conditions optimal for the production of bioflocculant by Micrococcus sp. Leo with subsequent evaluation of the properties of the produced compound were investigated. Optimum culture conditions for bioflocculant production included 2% (vol/vol) inoculum size, incubation temperature of 28°C, agitation speed of 160 rpm and initial pH of 4.0. Glucose and (NH₄)₂SO₄ and Al³⁺ were the best as sole carbon, nitrogen and cation sources, respectively. The purified bioflocculant flocculated kaolin suspension optimally at a dosage of 0.2 mg/mL following jar test, and flocculating activity of about 70% was retained after heat treatment of 100°C. Chemical analysis showed that the bioflocculant was composed of 28.4% polysaccharide, 2.6% protein and 9.7%. uronic acid. Thermogravimetric analysis demonstrated that the bioflocculant could not decompose completely at 400°C. FTIR spectra revealed the presence of hydroxyl, carboxyl and amino groups as the main functional groups. The bioflocculant produced by Micrococcus sp. Leo appears to hold promise as an alternative to conventional flocculants commonly used in water/wastewater treatment.     

Prevalence and distribution of Listeria pathogens in the final effluents of a rural wastewater treatment facility in the Eastern Cape Province of South Africa

We assessed the prevalence of free-living and plankton-associated Listeria species in the final effluents of a South African wastewater treatment facility and its receiving watershed between August 2007 and July 2008 as well as the antibiotic susceptibilities of effluent isolates. The physicochemical quality of the raw sewage and treated effluents was also determined. Free-living Listeria were more prevalent (96%), compared to plankton-associated Listeria species (58–67%). Listeria pathogens were sensitive to 11 (55%) of the 20 tested antibiotics, and showed varying (7–71%) levels of resistance to eight antibiotics. Turbidity, COD, NO₃, PO₄ and Listeria density fell short of recommended standards after treatment; while pH, temperature, TDS, DO and NO₂ were compliant with target quality after treatment. We conclude that final effluents of wastewater treatment plants are potential sources of Listeria pathogens in the aquatic milieu of South Africa.     

卡托普利对高血压大鼠动脉血管平滑肌细胞内质网相关因子葡萄糖调节蛋白78和C/EBP同源蛋白表达的影响

目的:研究卡托普利对早期高血压大鼠动脉血管平滑肌细胞内质网相关因子葡萄糖调节蛋白78(glucose-regulated protein of 78kd,GRPT8)和C/EBP同源蛋白(CAAT/enhancer binding protein homologous protein,CHOP)表达的影响.方法:将18只成年雄性Sprague-Dawley(SD)大鼠随机分为对照组、模型组和卡托普利组(n=6),模型组和卡托普利组均采用大鼠腹主动脉结扎建立高血压大鼠模型.4周后测量血压,应用免疫组化方法检测主动脉血管平滑肌细胞GRP78和CHOP的表达;缺口末端标记法(TUNEL)检测细胞凋亡.结果:(1)模型组平均动脉压(mean arterial blood pressure,MAP)明显增加,卡托普利组血压低于模型组,高于对照组,差异具有统计学意义(P<0.05);(2)模型组内质网因子GRP78、CHOP表达均增加,卡托普利组GRP78、CHOP表达低于模型组,高于对照组,差异具有统计学意义(P<0.01);(3)模型组血管平滑肌细胞凋亡率减少,卡托普利组血管平滑肌细胞凋亡率高于模型组,低于对照组,差异具有统计学意义(P<0.01).结论:卡托普利可降低高血压大鼠动脉血管平滑肌细胞GRP78和CHOP的表达,增加细胞凋亡.可能与其减弱高血压所致内质网反应,维持血管平滑肌细胞的增殖/凋亡平衡有关.     

Antibiotic susceptibility profiles of some <Emphasis Type="Italic">Vibrio</Emphasis> strains isolated from wastewater final effluents in a rural community of the Eastern Cape Province of South Africa

Background  

To evaluate the antibiogram and antibiotic resistance genes of some Vibrio strains isolated from wastewater final effluents in a rural community of South Africa. V. vulnificus (18), V. metschnikovii (3), V. fluvialis (19) and V. parahaemolyticus (12) strains were isolated from final effluents of a wastewater treatment plant (WWTP) located in a rural community of South Africa. The disk diffusion method was used for the characterization of the antibiogram of the isolates. Polymerase chain reaction (PCR) was employed to evaluate the presence of established antibiotic resistance genes using specific primer sets.     

Reduction of marginal mass required for successful islet transplantation in a diabetic rat model using adipose tissue–derived mesenchymal stromal cells

Background aims

Adipose tissue–derived mesenchymal stromal cells (AT-MSCs), widely known as multipotent progenitors, release several cytokines that support cell survival and repair. There are in vitro and in vivo studies reporting the regenerative role of AT-MSCs possibly mediated by their protective effects on functional islet cells as well as their capacity to differentiate into insulin-producing cells (IPCs).

鄂西南五种野生荚蒾属植物种群结构与动态特征研究

为探明鄂西南地区野生荚蒾属(Viburnum)植物的种群数量特征及区域分布状况，并揭示宜昌荚蒾(V.erosum)、桦叶荚蒾(V.betulifolium)、合轴荚蒾(V.sympodiale)、茶荚蒾(V.setigerum)、荚蒾(V.dilatatum)5种荚蒾属植物种群的生存现状及发展趋势，在鄂西南金子山国有林场、木林子国家级自然保护区及七姊妹山国家级自然保护区，共布设27 hm²固定动态监测样地对荚蒾属植物进行调查，通过对5种荚蒾属植物种群进行年龄结构、动态量化分析和静态生命表以及相关曲线等研究，探讨荚蒾属植物种群结构与动态特征及未来发展潜力。结果表明：(1)鄂西南荚蒾属植物在分布区域及种群数量大小上均存在明显差异。(2)种群结构与动态分析显示，5种荚蒾属植物种群年龄结构呈现为金字塔型，幼龄阶段种群个体数量较多，具有较强的增长潜力，但对外界干扰均具有较强的敏感性。(3)静态生命表显示，5种荚蒾属植物存活量均随着龄级的增加而单调递减；消失率与死亡率曲线变化趋势相似，但不同植物消失率与死亡率曲线波动具有差异性；种群存活曲线均趋近于Deevey-Ⅱ型。(4)4...     

绵羊GDF9和BMP15基因多态性检测

以绵羊GDF9基因FecG^H突变和BMP15基因FecX^B和FecX^G突变为候选基因,采用PCR—RFLP方法研究其在湖羊、夏洛来、陶赛特、萨福克、中国美利奴肉用多胎品系、中国美利奴羊和罗米丽羊7个品种中的多态性．结果发现,湖羊群体中存在GDF和BMP15基因的FecG^H和FecX^B突变,但发生率极低,分别为0．645％(2／310)和0．968％(3／310)：而其它品种中则没有发现GDF9和BMP15基因的相应突变．这一发现对于建立绵羊基因标记辅助选择方法具有重要意义．     

Differences in cellulose digestive systems among castes in two termite lineages

Abstract.  Termites (Isoptera) are eusocial insects and express polyphenism. Soldiers have specialized morphology for colony defense, but their feeding activity is dependent on other colony members. To determine differences in cellulose degradation between soldier and worker termites, enzymatic activity and cellulase gene expression, as well digestive tract histology, are examined in two phylogenetically distant species. In Hodotermopsis sjostesti (family Termopsidae) , endo-β-1,4-glucanase activity is identified in the salivary glands, whereas β-glucosidase activity is identified in salivary glands and hindgut. The relative expression levels of endo-β-1,4-glucanase genes in soldiers are significantly lower than in workers. Thin sections of salivary gland of workers and soldiers are different in H. sjostedti . In Nasutitermes takasagoensis (family Termitidae), the endo-β-1,4-glucanase activity is restricted to the midgut in four tested castes (i.e. three types of workers and soldier). Examination of activity per termite reveals the highest activity in minor workers and the lowest activity in major workers and soldiers. The β-glucosidase activity is also concentrated on the midgut in all four castes. The relative expression level of the endo-β-1,4-glucanase gene does not correspond with its activity in the midgut. In thin sections prepared from N. takasagoensis , the folds and pulvillus in the gizzards, and cuticle structure of soldiers are less developed compared with the other three worker castes. The differences in digestive system among termite castes in terms of caste development in each species are discussed.     

鄂西南天然林主要乔木树种物种组成及林分空间结构动态变化研究

该研究以鄂西南木林子国家级自然保护区内天然林为研究对象,以森林内胸径≥5 cm的乔木个体为具体分析对象,通过乔木树种重要值及其角尺度、大小比、混交度等林分空间结构参数的一元分布,阐述林分空间分布格局、大小分化程度、林木混交程度及变化,并通过分析林分空间结构参数的二元分布,探究各参数之间的联系,揭示5年间其林分空间结构特...