Culturable actinobacteria isolated from marine sponge <Emphasis Type="Italic">Iotrochota</Emphasis> sp.

The study describes the diversity of actinobacteria isolated from the marine sponge Iotrochota sp. collected in the South China Sea. Species and natural product diversity of isolates were analyzed, including screening for genes encoding polyketide synthases (PKS) and nonribosomal peptide synthetase (NRPS), and 16S rRNA gene restriction fragment length polymorphism (RFLP). PKS and NRPS sequences were detected in more than half of the isolates and the different “PKS-I–PKS-II–NRPS” combinations in different isolates belonging to the same species indicated a potential natural product diversity and divergent genetic evolution. The phylogenetic analysis based on 16S rRNA gene sequencing showed that the isolates belonged to genera Streptomyces, Cellulosimicrobium, and Nocardiopsis. The majority of the strains tested belonged to the genus Streptomyces and one of them may be a new species. To our knowledge, this is the first report of a bacterium classified as Cellulosimicrobium sp. isolated from a marine sponge. Key Laboratory of Marine Bio-recourses Sustainable Utilization (LMB-CAS), Guangdong Key Laboratory of Marine Materia Medica (LMMM-GD), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, People’s Republic of China.     

Investigation of cell proliferation and differentiation in the mantle of <Emphasis Type="Italic">Pinctada </Emphasis><Emphasis Type="Italic">fucata</Emphasis> (Bivalve,Mollusca)

The mantle of the pearl oyster Pinctada fucata was adopted for the proliferation profile study in our work and a proliferation hot spot was found in the outer epithelia of mantle central zone using the BrdU immunohistochemistry method. This result contradicts the previous research that the mantle has numerous growth centers all over the mantle epithelium, with the same proliferation activity throughout the whole mantle outer epithelial cells. This is the first report on the different proliferation features on the whole mantle where Alcian Blue/PAS staining analysis and ultrastructural observation with the aid of transmission electron microscope (TEM) demonstrated distinct features of the epithelium in four different regions of the mantle. Results from the present investigation displayed that in the outer epithelium of the marginal zone in mantle outer fold, organelles such as mitochondria and endoplasmic reticulum (ER) were well-developed and double membrane bounded vesicles were present; in the outer epithelia of mantle central zone, stem-like cells with a high ratio of nucleus to cytoplasm and comparatively undeveloped organelles were detected. Together with the observations of the cell proliferation profile of different regions of the mantle, a hypothetic model for the proliferation and differentiation of the pearl oyster’s mantle is proposed: there exists a proliferation “hot spot” in the outer epithelial cells of central zone and the proliferation ability decreases progressively from this “hot spot” towards the marginal zone; the whole mantle’s differentiation occurs continuously with its growth and the direction is from the proliferation ‘hot spot’ (central zone) towards the marginal zone. Furthermore, another interesting result was found when the proliferation rate was investigated together with the tidal rhythm: the proliferation activity was found to be closely correlated with the tidal rhythm, indicating that the mantle outer epithelia’s proliferation rhythm might be the impetus of the shell’s daily growth bands.     

惠州西湖沉积物营养盐的释放

惠州西湖为典型的南亚热带城市浅水湖泊,位于惠州市中心区域,近年来已采取了截留城市污水、引清水等治理措施,但西湖水体仍处于富营养化状态.以惠州西湖沉积物为研究对象,采用实验室原状泥柱静态培养法对惠州西湖各子湖沉积物氨氮和反应磷的释放通量进行了研究.结果表明,惠州西湖沉积物中氨氮(NH4 -N)释放通量为-31.64~69.73 mg·m-2 ·d-1,不同湖区释放通量差异较大,总体上沉积物为水中氨氮的源;各湖区沉积物中的反应磷(PO43-P)的平均释放通量为-6.42~-0.80 mg·m-2·d-1,惠州西湖沉积物为水中磷的汇.研究结果可为惠州西湖水质管理和生态修复提供科学依据.     

红壤坡地生态系统恢复过程植被群落的演变

应用样方调查方法,对湘北红壤坡地有人为干扰和无人为干扰两种方式下植被恢复情况进行了初步调查分析,结果表明:无人为干扰的坡地植被恢复在11年间经历了缓慢恢复和快速恢复两个阶段,不同坡位群落生物量稳步增长,正在逐步形成具有稳定群落结构的自然生态系统;人为干扰坡地植被恢复缓慢,由于水土流失,上坡位地下部生物量呈下降趋势,中坡位和下坡位地下部的生物量都大幅度的增加,此外人为干扰使得乔木类植物无法正常生长,从而不能形成具有明显垂直结构的稳定生态系统.     

长期单施NK肥条件下几种典型土壤磷的演化

为探讨我国典型土壤长期单施氮钾肥对土壤全磷和Olsen-P磷的影响,研究了不同气候条件、不同耕作制度下,7种典型土壤类型长期定位试验单施氮钾肥下土壤全磷和Olsen-P变化及其影响因素.结果表明,在长期单施氮钾肥条件下,除杭州水稻土全磷含量稳定在1.0g·kg-1左右外,其余6种耕作土壤全磷含量和土壤Olsen-P均呈显著下降趋势,全磷含量下降幅度在13.6%～44.9%之间;土壤Olsen-P下降速率比全磷高几倍,Olsen-P下降有一定阈值,这一阈值大约为5 mg·kg-1.土壤全磷含量与土壤Olsen-P含量呈极显著直线相关关系.因此,长期单施氮钾肥在很大程度上减少了土壤磷素养分库.     

珠江三角洲城市群大气微生物与环境相关性

运用生态学的方法,结合实地调查与数理统计分析,对珠江三角洲城市群的大气微生物与环境的相关性问题进行探讨,拟为珠江三角洲城市环境污染的综合防治和卫生防疫工作提供依据,研究结果表明.(1)珠江三角洲城市群中广州和东莞的大气微生物含量较高,其中细菌比真菌含量高;室内较室外,无绿化地较有绿化地的大气微生物含量高,在全年中,春、夏季节的大气微生物含量相对较高.(2)大气风速、湿度、气温、可吸入颗粒、总悬浮颗粒、人口流动,绿化状况等环境因子与大气微生物真菌、细菌的平均含量有较明显的相关关系,大气微生物含量与气象因子多数呈正或负的线性关系.相关分析的计算结果为:真菌、细菌平均含量在春、夏、秋、冬四个季度中与大气温度、湿度、风速大多数地区相关程度比较高,其值R在0.583～0.988之间,真菌、细菌与可吸人颗粒数和总悬浮颗粒数,R值分别为为0.525,0.388和0.081,-0.044.一元线性回归分析和多元线性回归分析计算结果为:大气微生物含量与气象因子有明显的正或负的线性关系.真菌、细菌的平均含量与温度、湿度、风速一元线性回归模型的置信水平较高,其p值大多在0.019～0.483之间,T值在0.001～0.246之间;多元线性回归模型的置信水平也较高,其P值大多数在0.083～0.220之间,T值在0.026～0.132之间;排序值显示:温度、风速变化是大气微生物含量高低影响重要性最大的环境因子.(3)统计数据比较分析表明:大气微生物含量与人口密集状况、人口流动大小和绿化状况好坏也有较明显的相关性,火车站,汽车客运站售票厅,人口流量大,绿化无,大气微生物(真菌细菌)平均含量高;而人口流量相对较少,但车流量大,有一定的绿化带的道路大气微生物平均含量较低;环境条件、绿化较好的公园绿地大气微生物含量低,车流、人流多,绿化少的地段、商业中心大气微生物含量较高.     

生态工业园中企业的动力机制分析

本文分析了生态工业园中企业的社会和经济属性以及其决策的关键约束条件,指出企业能够参与生态工业园建设是由于生态工业园合乎企业的基本性质的要求,能够使得企业实现经济价值的同时实现社会价值,这就是生态工业园中企业参与生态工业园建设的驱动力之所在。最后,根据生态工业园中企业的特性和生态工业园的特点提出了若干促进企业参与生态工业园建设的建议。     

声波清灰技术在袋式除尘器上的应用

利用声波清灰技术替代袋式除尘器传统的反吹、机械振打等清灰方式。运行结果表明:该技术运行可靠,维护量低,经济实用,解决了袋式除尘器易损坏,维护量大等问题。     

中孔分子筛Al-MCM-41催化裂解聚烯烃反应研究

采用水热合成法制备了不同硅铝比的中孔分子筛A l-MCM-41,将其应用于高密度聚乙烯(HDPE)和聚丙烯(PP)的催化裂解反应。通过改变硅铝比、反应温度和催化剂用量,对A l-MCM-41催化HDPE和PP裂解反应的规律进行了探讨,研究表明,HDPE裂解反应受硅铝比的影响较大;而对于PP裂解反应,硅铝比在一定范围内对催化剂活性的影响不明显。另外,与热裂解和HZSM-5小孔分子筛的催化裂解结果进行了比较,结果证明A l-MCM-41具有较高的催化活性和较高的液体产物收率,尤其适合于空间位阻较大的PP的催化裂解反应。