Changes of alkaline phosphatase activity in response to different stressors in planarian Dugesia japonica

The aims of this work are to provide some properties of alkaline phosphatase (ALP) in the planarian Dugesia japonica and detect its activity in response to different stressors, as well as to introduce renatured SDS-PAGE to study enzyme activity in planarians. Our results indicate that ALPs in planarians are mainly membrane-bound form, identified as three mainly enzyme-bands (approximately MW 260 kD, 180 kD, 160 kD, respectively). Under our experimental conditions, ALPs activity had no apparent changes in response to low concentration of Hg²⁺ (25 μg L^?1) and Pb²⁺ (125 μg L^?1, 250 μg L^?1) exposure, but were severely inhibited in response to high concentration of Hg²⁺ (50 μg L^?1, 150 μg L^?1, 300 μg L^?1) and Pb²⁺ (500 μg L^?1, 1000 μg L^?1) exposure. Mild heat shock (25°C for 2 days) elevated ALP activity, but severely heat shock (25°C for 2 days, followed by 30°C for 2 days and 32°C for 2 days) inactivated ALP activity. Interestingly, ALP and other cytosolic phosphatases (MW from ～45 kD to ～60 kD) activity increased noticeably during the early stage of planarians regeneration, which may be involved in cell proliferation and differentiation. Contrary to regeneration, prolonged starvation suppressed ALP activity. The above findings provide valuable information about the role of ALP in planarian regeneration and for its use as an indicator in ecotoxicology.     

Effects of 1-octyl-3-methylimidazolium bromide on the antioxidant system of Lemna minor

Ionic liquids have gained more attention due to their excellent properties in many different scientific fields. However, previous researches indicated that ionic liquids have adverse effects on organisms. The objective of this study was to evaluate the effects of 1-octyl-3-methylimidazolium bromide ([C(8)mim]Br) on the aquatic plant duckweed (Lemna minor) by exposure of the plant to 0.25 to 2 mg L(-1) of [C(8)mim]Br for 28 days. Exposure to [C(8)mim]Br significantly decreased the photosynthetic pigment contents at 21 and 28 days. The activities of superoxide dismutase and catalase and the total antioxidant capacity level increased at 7 days of exposure and decreased at the termination of exposure. In contrast, the H(2)O(2) content and peroxidase activity in all treatments increased during the period of exposure. Furthermore, marked increase of malondialdehyde content occurred in duckweed after 21 to 28 days of exposure. In addition, reactive oxygen species (ROS) scavenger dimethyl thiourea prevents duckweed from oxidative damage caused by [C(8)mim]Br. These results suggest that ROS might be involved in the mechanism of ionic liquid-induced toxicity in L. minor.     

The histology and ultrastructure of the salivary glands of Neopanorpa longiprocessa (Mecoptera: Panorpidae)

The salivary glands of Panorpidae usually exhibit distinct sexual dimorphism and are closely related to the nuptial feeding behavior. In this study, the salivary glands of Neopanorpa longiprocessa were investigated using light microscopy and transmission electron microscopy. The salivary glands are tubular labial glands and consist of a scoop-shaped salivary pump, a common salivary duct, and a pair of salivary tubes. The male and female salivary glands are remarkably different in the bifurcation position of the common salivary duct and the length and shape of the secretory tubes. Compared with the simple female salivary glands, the male’s are more developed as their paired elongated salivary tubes can be divided into two parts, the glabrate anterior tube and the posterior tube with many secretory tubules. The ultrastructural study shows that the male salivary tubes have strong secretory function. The existence of different secretion granules indicates that there are some chemical reactions or mixing occurring in the lumen. Based on the ultrastructural characteristics, the functions of the different regions of the salivary tube have been speculated. The relationship between the salivary glands and nuptial feeding behavior of N. longiprocessa has been briefly discussed based on the structure of the salivary glands.

     

Seedling recruitment in response to artificial gaps: predicting the ecological consequence of forest disturbance

Plant Ecology - Artificial gaps are widely created for forest management. However, the interactive effects of gap sizes and within-gap locations on seedling regeneration are rarely tested....     

泡桐维管形成层及木质部区的转录组分析

采用Illumina HiSeqTM2500高通量测序技术,获得泡桐维管形成层及木质部区组织转录组的109021918条clean reads(16.35 Gb)。将clean reads从头组装得到104432个单基因簇(Unigene),平均长度662 nt。将组装得到的Unigenes与公共数据库进行序列比对,分别有40789(Nr:39.05%)、31675(NT:30.33%)、15539(COG:14.87%)、29168(GO:27.93%)、16316(KEGG:15.62%)、30499(SwissProt:29.20%)以及28828(Pfam:27.6%)个Unigenes获得功能注释。通过与GO数据库的比对分析,注释的29168个Unigenes归于生物过程、细胞组分及分子功能三大类的55个功能组;15539条Unigenes注释到COG数据库,被分为25个类别中;基于KEGG数据库可将16316个Unigenes归于130个代谢途径。此外,在泡桐的维管形成层及木质部区转录组中共检测出16118个简单序列重复(SSR)位点。为进一步挖掘泡桐重要功能基因提供了大量数据。     

藏北高寒草地土壤有机质化学组成对土壤蛋白酶和脲酶活性的影响

土壤酶作为生态系统的生物催化剂, 是土壤有机体的代谢驱动力, 在土壤物质循环和能量转化过程中起着重要作用。该研究以藏北5种不同类型高寒草地(高寒草甸、高寒草原、高寒草甸草原、高寒荒漠草原和高寒荒漠)为研究对象, 利用热裂解气质联用技术(Py-GC/MS)分析不同类型草地土壤有机质化学组成, 并建立其与土壤蛋白酶和脲酶活性之间的相互关系。结果表明, 5种高寒草地土壤(0-15 cm)的酶活性表现出一定差异性, 高寒荒漠草原土壤的脲酶活性显著高于蛋白酶活性, 而其余类型高寒草地的脲酶和蛋白酶活性之间的差异未达到显著水平; 蛋白酶活性在5种高寒草地土壤之间的差异显著, 而脲酶活性在5种草地土壤之间的差异未达到显著水平。相关分析发现, 土壤蛋白酶活性与土壤有机质烷烃、烯烃和芳香烃的相对丰度和糠醛:吡咯的值密切相关, 土壤脲酶活性与土壤有机质化学组成之间相关性未达到显著水平。综上所述, 高寒草地类型和土壤有机质化学组成是影响高寒草地土壤蛋白酶活性的重要因素, 而对土壤脲酶活性的影响均未达到显著水平, 其影响因素有待进一步深入的研究。     

Morphological and genomic characteristics of two novel halotolerant actinomycetes,Tomitella gaofuii sp. nov. and Tomitella fengzijianii sp. nov. isolated from bat faeces

Four white-pigmented, Gram-staining-positive, strictly aerobic, non-spore-forming, irregular rod-shaped bacteria were isolated from the faeces of bats collected from Guangxi autonomous region (22°20′54″N, 106°49′20″E; July 28, 2011) and Chongqing city (30°02′15″N, 107°07′4″E; September 1, 2011) of South China. The strains shared 99.3–99.9% 16S rRNA gene sequence similarity by BLAST search among them, and belonged to genus Tomitella according to 16S rRNA gene and genomic sequence-based phylogenetic/phylogenomic analyses. Strains HY172^T and HY188^T contained meso-diaminopimelic acid as the diagnostic diamino acid, and arabinose, glucose, galactose or ribose in their whole-cell hydrolysates. Besides sharing phosphatidylethanolamine, diphosphatidylglycerol and unidentified glycolipid(s) in their polar lipid profiles, additionally HY172^T had one unidentified phosphoglycolipid and three unidentified phospholipids whereas HY188^T had phosphatidyl inositol mannoside and four unidentified aminolipids. The main cellular fatty acids of strains HY172^T and HY188^T were C_16:0, C_18:0 10-methyl, C_18:1ω9c and summed feature 3. The genomic DNA G + C contents of both strains (HY172^T and HY188^T) were 70.9 %. The genus Tomitella contains 2311 core genes, and resuscitation promoting factor (rpf) genes can be found in all members of Tomitella. The digital DNA-DNA hybridization and average nucleotide identity values of the four novel strains with other members of the genus Tomitella were within the ranges of 20.1–45.2% and 74.8–91.9%, respectively, all below the respective recommended 70.0% and 95–96% cutoff point. Based on phylogenetic, chemotaxonomic and phenotypic analyses, these four strains could be classified as two novel species of the genus Tomitella, for which the names Tomitella gaofuii sp. nov. and Tomitella fengzijianii sp. nov. are proposed. The type strains are HY172^T (= CGMCC 1.18701^T = JCM 34231^T) and HY188^T (= CGMCC 1.16971^T = JCM 33467^T), respectively.