Biological activity of a red-tide alga - A-tamarense under co-cultured condition with bacteria

The relationship between Alexandrium tamarense (Lebour) Balech, one of red-tide alga, and two strains of marine bacteria, Bacillius megaterium(S-7) and B. halmapulus(S-10) isolated from Xiamen Western Sea, was investigated by evaluating the growth state of A. tamarense and the variation of P-glucosidase activity in co-culture system. The results showed the growth and multiplication of the alga were related with the concentration, genus speciality of the bacteria, and growth stage of the alga itself. The growth of A. tamarense was obviously inhibited by S7 and S, at high concentration. Either inhibition or promotion contributed much more clearly in earlier than in later stage of the growth of the alga. Furthermore, there was a roughly similar variation trend of the activity of extra-cellular enzyme, beta-glucosidase, in the water of the separately co-cultured bacteria S-7 and S-10 with the alga. The beta-glucosidase activity (beta-GlcA) rapidly increased during the later algal growth accompanying the increase of the lysis of the alga cells. The obvious inhibition of A. tamarense by marine bacteria at high concentration and evident increase of beta-GlcA in co-colture system would help us in better understanding the relationship between red-tide alga and bacteria, and also enlightened us the possible use of bacteria in the bio-control of red-tide.

Intracellular copper/zinc superoxide dismutase from bay scallop Argopecten irradians: Its gene structure, mRNA expression and recombinant protein

Superoxide dismutases are an ubiquitous family of enzymes that function to efficiently catalyze the dismutation of superoxide anions. Two unique and highly compartmentalized bay scallop Argopecten irradians superoxide dismutases: MnSOD and ecCuZnSOD, have been molecularly characterized in our previous study. To complete characterize the SOD family in A. irradians, a novel intracellular copper/zinc SOD from the A. irradians (Ai-icCuZnSOD) was obtained and characterized. The full-length cDNA of Ai-icCuZnSOD was 1047 bp with a 459 bp open reading frame encoding 152 amino acids. The genomic length of the Ai-icCuZnSOD gene was about 4279 bp containing 4 exons and 3 introns. The promoter region containing many putative transcription factor binding sites were analyzed. Furthermore, quantitative reverse transcriptase real-time PCR (qRT-PCR) analysis indicated that the highest expression of the Ai-icCuZnSOD was detected in gill and the expression profiles in hemocytes of bay scallops challenged with bacteria Vibrio anguillarum and lipopolysaccharide (LPS) were different. The result presented an increased expression after injection with LPS whereas no significant changes were observed after V. anguillarum injection. A fusion protein containing Ai-icCuZnSOD was produced in vitro. The rAi-icCuZnSOD is a stable enzyme, retaining more than 80% of its activity between 10 and 60 degrees C and keeping above 88% of its activity at pH values between 5.8 and 9. Ai-icCuZnSOD is more stable under alkaline than acidic conditions. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.

A new brominated phenylpropylaldehyde and its dimethyl acetal from red alga Rhodomela confervoides

A new brominated phenylpropylaldehyde and its dimethyl acetal together with a new natural brominated phenol were isolated from Rhodomela confervoides. Their structrues were elucidated as 2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propylaldehyde, 2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl) propylaldehyde dimethyl acetal and 3-bromo-4,5-dihydroxybenzoic acid methyl ester by spectroscopic techniques including IR, HRFABMS, ID and 2DNMR experiments.

根据外部形态特征试论鹅观草属的亲缘演化关系

鹅观草属的一些性状是有演化意义的, 其中外部形态上小穗柄、颖、芒的演化趋势不仅可以作为判断属下类群演化的依据, 而且可以作为推证属间类群渊源的旁证。分析结果表明: 鹅观草属中最原始的半颖组可能既派生了颖体瘦小的小颖组, 又派生了颖体宽大的大颖组, 并在大颖组的基础上演化产生了长颖组; 鹅观草属中颖无芒的系原始, 颖具芒的系进化, 外稃具直伸芒的系原始于外稃无芒(包括芒尖) 或外稃芒弯曲的系, 高级进化系直接或间接来源于低级原始系; 鹅观草属可能起源于族外的短柄草属, 尤其短芒短柄草最接近鹅观草属古老祖先的起源类群; 鹅观草属在小麦族中的演化水平不是太高, 在系统发育的长河中其一支经小颖组衍变成了披碱草属, 以至猬草属, 另一支经大颖组或长颖组衍变成了以礼草属, 乃至冰草属。

一种实用的基于直线对应的摄象机标定方法

以摄象机针孔模型为基础,研究了立体视觉系统中摄象机的非畸变模型标定问题,指出了一种实用的基于直线对应的摄象机标定方法.该方法不仅数学推导简单易懂,而且在推导过程中没有对直线加以任何的假设约束条件,可大大拓宽线对应标定方法的应用范围.文中讨论了这一标定方法中投影距阵的两种求解方法,并将求解结果与传统的基于点对应的摄象机标定方法进行了比较.实验结果表明,该方法的精度明显高于传统的点对应摄象机标定方法。

河水样品中硼的分离及其同位素组成测定

对河水样品中低含量硼的分离方法及硼同位素组成的测定进行了研究。将约1000mL河水样品分别用硼特效树脂，混合树脂富集和纯化后，紫外灯照射去除有机质，蒸发浓缩至小体积，采用正热离子质谱法进行硼同位素组成的测定。全流程回收率在95％以上，同位素稀释法测得全流程空白为41ng。经该方法处理后的样品能满足同位素质谱测定的需要。不产生同位素分馏，测试精度基本在0.6‰以内。