Effects of sand burial on biomass, chlorophyll fluorescence and extracellular polysaccharides of man-made cyanobacterial crusts under experimental conditions

Soil cyanobacterial crusts occur throughout the world, especially in the semiarid and arid regions. It always encounters sand burial, which is an important feature of mobile sand dunes. A greenhouse 41 study was conducted to determine the effects of sand burial on biomass, chlorophyll fluorescence and extracellular polysaccharides of man-made cyanobacterial crusts in six periods of time (0, 5, 10, 15, 20 and 30 d after burying) and at five depths (0, 0.2, 0.5, 1 and 2cm). The results indicated that with the increase of the burial time and burial depth extracellular polysaccharides content and Fv/Fm decreased correspondingly and there were no significant differences between 20 and 30 burial days under different burial depths. The degradation of chlorophyll a content appeared only at 20 and 30 burial days and there was also no significant difference between them under different burial depths. It was also observed a simultaneous decrease of the values of the Fv/Fm and the content of extracellular polysaccharides happened in the crusted cyanobacterium Microcoleus vaginatus Gom. It may suggest that there exists a relationship between extracellular polysaccharides and recovery of the activity of photosystem II (PS II) after rehydration.

Growth and antioxidant system of the cyanobacterium Synechococcus elongatus in response to microcystin-RR

Microcystins, one type of the cyanobacterial toxins, show a broad range of hazardous effects on other organisms. Most of the researches on the toxic effects of microcystins have involved in animals and higher plants. Little work, however, has been done on evaluating the mechanisms of microcystin toxicity on algae. In this study, the toxicological effects of microcystin-RR (MC-RR) on the cyanobacterium Synechococcus elongatus were investigated. For this purpose, six physio-biochemical parameters (cell optical density, reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GSH-Px) and glutathione S-transferase (GST)) were tested in algal cells when exposed to 100 mug(-1) microcystin-RR. The results showed that the growth of Synechococcus elongatus ( expressed as optical density) was significantly inhibited compared with the control. At the same time, the treated algae exhibited a pronounced increase in production of ROS and MDA after 6 days exposure to microcystin-RR. Signi. cant changes in GSH levels and GSH-Px, GSH activities were also detected in algal cells, with higher values being observed in the toxin treated algae after 6 days exposure. GST activities in the treated algae exhibited a decline after exposure and rapid augmentation on day 3, thereafter, they kept at a high level when compared to the control group. GSH contents and GSH-Px activities were also significantly raised in the toxin-treated algae cells from day 3, but they showed a sharp decrease on day 4, which was the onward of cell proliferation. These results suggested that oxidative stress manifested by elevated ROS levels and MDA contents might be responsible for the toxicity of microcystin to Synechococcus elongatus and the algal cells could improve their antioxidant ability through the enhancement of enzymatic and non-enzymatic preventive substances.

cDNA cloning and characterization of a novel SNX gene differentially expressed in previtellogenic oocytes of gibel carp

To understand the molecular events governing fish oogenesis, a multiple technique was used to identify the genes differentially expressed at different phases during fish oogenesis. This technique is a combination of suppression subtractive hybridization, SMART cDNA synthesis and RACE-PCR. Here we report the cDNA cloning and expression characterization of a novel SNX gene based on its differential transcription between previtellogenic and fully mature oocytes in naturally gynogenetic gibel carp. First, a cDNA fragment selectively expressed in previtellogenic oocytes was identified and used to screen a SMART cDNA library prepared from the same mRNA sample by RACE-PCR for cloning fully length cDNA. The full length cDNA was 1392-bp long and coded for a novel SNX protein with 225 amino acids. The 5' UTR had 72 bp and 3' UTR had 642 bp. Unlike most of maternal genes that are transcribed after vitellogenesis and stored in oocytes, this gene is expressed at a higher level in the previtellogenic oocytes and at a much lower level in fully matured oocytes. However, RT-PCR analysis of tissues showed it was ubiquitous transcription. The novel gene is named fish sorting nexin (fSNX), because it contains a conserved PX domain. The fact which major expression of the gene occurs in the previtellogenic oocytes suggests that it might have an important function in the oogenesis. (C) 2003 Elsevier Inc. All rights reserved.

Comparative ontogenetic behavior and migration of kaluga, Huso dauricus, and Amur sturgeon, Acipenser schrenckii, from the Amur River

We conducted laboratory experiments with kaluga, Huso dauricus, and Amur sturgeon, Acipenser schrenckii, to develop a conceptual model of early behavior. We daily observed embryos (first life phase after hatching) and larvae (period initiating exogenous feeding) to day-30 (late larvae) for preference of bright habitat and cover, swimming distance above the bottom, up- and downstream movement, and diel activity. Day-0 embryos of both species strongly preferred bright, open habitat and initiated a strong, downstream migration that lasted 4 days (3 day peak) for kaluga and 3 days (2 day peak) for Amur sturgeon. Kaluga migrants swam far above the bottom (150 cm) on only 1 day and moved day and night; Amur sturgeon migrants swam far above the bottom (median 130 cm) during 3 days and were more nocturnal than kaluga. Post-migrant embryos of both species moved day and night, but Amur sturgeon used dark, cover habitat and swam closer to the bottom than kaluga. The larva period of both species began on day 7 (cumulative temperature degree-days, 192.0 for kaluga and 171.5 for Amur sturgeon). Larvae of both species preferred open habitat. Kaluga larvae strongly preferred bright habitat, initially swam far above the bottom (median 50-105 cm), and migrated downstream at night during days 10-16 (7-day migration). Amur sturgeon larvae strongly avoided illumination, had a mixed response to white substrate, swam 20-30 cm above the bottom during most days, and during days 12-34 (most of the larva period) moved downstream mostly at night (23-day migration). The embryo-larva migration style of the two species likely shows convergence of non-related species for a common style in response to environmental selection in the Amur River. The embryo-larva migration style of Amur sturgeon is unique among Acipenser yet studied.

Differential expression and characterization analysis of a new gene with WD domains in fish oogenesis

A new gene with WD domains is cloned and characterized according to its differential transcription and expression between previtellogenic oocytes (phase I oocytes) and fully-grown oocytes (phase V oocytes) from natural gynogenetic silver crucian carp (Carassius auratus gibelio) by using the combinative methods of suppressive subtraction hybridization, SMART cDNA synthesis and RACE-PCR. The full-length cDNA is 1870 bp. Its 5 ' untranslated region is 210 bp, followed by an open reading frame of 990 bp, which has the typical vertebrate initiator codon of ANNATG. The open reading frame encodes a protein with 329 amino acids. It has 670 bp of 3 ' untranslated region and an AATAAA polyadenylation signal. Because it has 92% homology to STRAP (serine-threonine kinase receptor-associated protein), a recently reported gene, we named it FSTRAP (fish STRAP). Virtual Northern blotting indicated that the FSTRAP was transcribed in fully-grown oocytes (phase V oocytes), but not in previtellogenic oocytes (phase I oocytes). RT-PCR analysis showed that FSTRAP was transcribed in brain, heart, kidney, muscle, ovary, spleen and testis, but not in liver. And its mRNA could be detected in the oocytes from phase II to phase V. Western blotting also showed that FSTRAP protein could be detected in brain, heart, kidney, muscle, ovary, spleen and testis except liver. Results of Western blotting on various oocytes were also similar to the RT-PCR data. FSTRAP protein was not expressed in the previtellogenic oocytes. Its expression initiated from phase II oocytes after vitellogenesis, and was consistent with the mRNA transcription.

Proton irradiation-induced defects in undoped GaSb studied by positron lifetime spectroscopy and photoluminescence

Undoped GaSb was irradiated by 2.6 MeV protons. The irradiation-induced defects were studied by positron lifetime spectroscopy (PLS) and photoluminescence (PL). Positron lifetime measurements showed that vacancy-type defects were introduced after irradiation, and divacancies were formed at higher irradiation dose. Annealing experiments revealed there were different annealing steps between the as grown and proton-irradiated samples, the reason for which was tentatively attributed to the formation of divacancies in the proton-irradiated samples during annealing. All the vacancy defects could be annealed out at around 500 degrees C. The PL intensity quickly fell down after proton irradiation and decreased with increasing irradiation dose, indicating that irradiation induced non-irradiative recombination centers, whose candidates were assigned to the vacancy defects induced by proton irradiation.

Early effects of carbon-ion irradiation on murine lymphocytes and thymocytes

To estimate the biological risks from space radiation encountered by cosmonauts in outer space, the effects from whole-body exposure to carbon ions or X-rays irradiations at 0, 0.39, 0.55 and 1 Gy at a dose rate of 0.2 Gy/min were investigated in BALB/c mice. The relative thymus and spleen weights were measured at 24 h after exposure, and the cell cycle distribution and percentage of apoptosis of thymocytes and spleen and peripheral blood lymphocytes were determined by flow cytometry. The data showed that exposure to carbon ions delayed cell progression of peripheral blood lymphocytes in S-phase, and delayed thymocytes and spleen lymphocytes in G(0)/G(1)-phase. Apoptosis of thymocytes and peripheral blood lymphocytes induced by carbon ions increased more rapidly with dose than was the case for X-rays. There were some differences between the relative weight loss of the thymus and the spleen with increasing dose of either carbon ions or X-rays. The results obtained provide evidence of dose- and organ-specific differences induced by carbon ions compared to X-rays, with increased apoptosis in peripheral blood lymphocytes and thymocytes, but not spleen lymphocytes. Our data may suggest that further work would be of interest to estimate risk of changes in immune function during particle radiation exposures in space travel. (c) 2007 COSPAR

On-line hyphenation of capillary isoelectric focusing and capillary gel electrophoresis by a dialysis interface

An on-line two-dimensional (2D) capillary electrophoresis (CE) system consisting of capillary isoelectric focusing (CIEF) and capillary gel electrophoresis (CGE) was introduced. To validate this 2D system, a dialysis interface was developed by mounting a hollow fiber on a methacrylate resin plate to hyphenate the two CE modes. The two dimensions of capillary shared a cathode fixated into a reservoir in the methacrylate plate; thus, with three electrodes and only one high-voltage source, a 2D CE framework was successfully established. A practical 2D CIEF-CGE experiment was carried out to deal with a target protein, hemoglobin (Hb). After the Hb variants with different isoelectric points (pIs) were focused in various bands in the first-dimension capillary, they were chemically mobilized one after another and fed to the second-dimension capillary for further separation in polyacrylamide gel. During this procedure, a single CIEF band was separated into several peaks due to different molecular weights. The resulting electrophoregrarn is quite different from that of either CIEF or CGE; therefore, more information about the studied Hb sample can be obtained.

Cloning and expression of glucose regulated protein 78 (GRP78) in Fenneropenaeus chinensis

GRP78 (78 kDa glucose-regulated protein), also known as BiP (immunoglobulin heavy-chain-binding protein), is an essential regulator of endoplasmic reticulum (ER) homeostasis because of its multiple functions in protein folding, ER calcium binding, and controlling of the activation of transmembrane ER stress sensors. In this report, we cloned the full length cDNA of GRP78 (FcGRP78) from Chinese shrimp Fenneropenaeus chinensis. This cDNA revealed a 2,325 bp with 1,968 bp open reading frame encoding 655 amino acids. This is the first reported GRP78 gene in Crustacea. The deduced amino acid sequence of FcGRP78 shared high identity with previously reported insect GRP78s: 86, 87 and 85% identity with GRP78s of Drosophila melanogaster, Aedes aegypti and Bombyx mori, respectively. Northern blot analysis shows that FcGRP78 is ubiquitously expressed in tissues of shrimp. Heat shock at 35A degrees C significantly enhanced the expression of FcGRP78 at the first hour, reached the maximum at 4 h post heat shock, dropped after that and resumed to the normal level until 48 h of post recovery at 25A degrees C. Additionally, differential expression of FcGRP78 was detected in haemocytes, hepatopancreas and lymphoid organ when shrimp were challenged by white spot syndrome virus (WSSV). We inferred that FcGRP78 may play important roles in chaperoning, protein folding and immune function of shrimp.

Molecular cloning, characterization and expression of heat shock protein 90 gene in the haemocytes of bay scallop Argopecten irradians

Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone that plays key roles in the folding, maintenance of structural integrity and regulation of a subset of cytosolic proteins. In the present study, the cDNA of Argopecten irradians HSP90 (designated AiHSP90) was cloned by the combination of homology cloning and rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of AiHSP90 was of 2669 bp, including an open reading frame (ORF) of 2175 bp encoding a polypeptide of 724 amino acids with predicted molecular weight of 83.08 kDa and theoretical isoelectric point of 4.81. BLAST analysis revealed that AiHSP90 shared high similarity with other known HSP90s, and the five conserved amino acid blocks defined as HSP90 protein family signatures were also identified in AiHSP90, which indicated that AiHSP90 should be a cytosolic member of the HSP90 family. Fluorescent real-time quantitative PCR was employed to examine the expression pattern of AiHSP90 mRNA in haemocytes of scallops challenged by Gram-negative bacteria Vibrio anguillarum and Gram-positive bacteria Micrococcus luteus. In both bacterial challenged groups, the relative expression level of AiHSP90 transcript was up-regulated and reached maximal. level at 9 h after injection, and then dropped progressively to the original level at about 48 h post challenge. The results indicated that AiHSP90 was potentially involved in the immune responses against bacteria challenge in scallop A. irradian. (c) 2007 Elsevier Ltd. All rights reserved.

Molecular cloning and immune responsive expression of a novel C-type lectin gene from bay scallop Argopecten irradians

C-type lectins are Ca2+-dependent carbohydrate-recognition proteins that play crucial roles in innate immunity. The cDNA of C-type lectin (AiCTL1) in the bay scallop Argopecten irradians was cloned by expressed sequence tag (EST) and RACE techniques. The full-length cDNA of AiCTL1 was 660 bp, consisting of a T-terminal. untranslated region (UTR) of 30 bp and a 3' UTR of 132 bp with a polyadenylation signal sequence AATAAA and a poly(A) tail. The AiCTL1 cDNA encoded a polypeptide of 166 amino acids with a putative signal peptide of 20 amino acid residues and a mature protein of 146 amino acids. The deduced amino acid sequence of AiCTL1 was highly similar to those of the C-type lectins from other animals and contained a typical carbohydrate-recognition domain (CRD) of 121 residues, which has four conserved disulfide-bonded cysteine residues that define the CRD and two additional cysteine residues at the amino terminus. AiCTL1 mRNA was dominantly expressed in the hemocytes of the bay scallop. The temporal expression of AiCTL1 mRNA in hemocytes was increased by 5.7-and 4.9-fold at 6 h after injury and 8 h after injection of bacteria, respectively. The structural features, high similarity and expression pattern of AiCTL1 indicate that the gene may be involved in injury heating and the immune response in A. irradians. (c) 2008 Elsevier Ltd. All rights reserved.

Molecular cloning, characterization and expression of a serine protease with clip-domain homologue from scallop Chlamys farreri

Serine proteases play critical roles in a variety of invertebrate immune defense responses, including hemolymph coagulation, antimicrobial peptide synthesis, and melanization. The first mollusk serine protease with clip-domain (designated CFSP1) cDNA was obtained from the scallop Chlamys farreri challenged with Vibrio anguillarum by randomly sequencing a whole tissue cDNA library and rapid amplification of cDNA ends (RACE). The full-length cDNA of the C. farreri serine protease was 1211 bp, consisting of a 5-terminal untranslated region (UTR) of 72 bp, a 3'-terminal UTR of 77 bp with a canonical polyadenylation signal sequence AATAAA and a poly (A) tail, and an open reading frame of 1062 bp. The CFSP1 cDNA encoded a polypeptide of 354 amino acids with a putative signal peptide of 19 amino acids and a mature protein of 335 amino acids. The deduced amino acid sequence of CFSP1 contained an amino-terminal clip domain, a low complexity region, and a carboxyl-terminal serine protease domain. CFSP1 mRNA was mainly expressed constitutively in the hemocytes and was up-regulated and increased 2.9- and 1.9-fold at 16 h after injury and injection of bacteria. (c) 2006 Elsevier Ltd. All rights reserved.

Investigations of the characteristics and mode of action of an algalytic bacterium isolated from Tai Lake

An algalytic bacterium provisionally designated as TL1 was isolated from Tai Lake, a large freshwater lake in the Yangtze Delta plain on the border of the Jiangsu and Zhejiang provinces and close to Wuxi city in the People's Republic of China. Strain TL1 was identified as Achromobacter sp. based on its biophysical and biochemical properties and the analysis of its 16S rRNA sequence. Microcystis aeruginosa, which is the most common toxic cyanobacterium in eutrophic freshwater, could be decomposed by strain TL1. The results showed that after inoculation with the algalytic bacterium, the content of chlorophyll-a, maximum PSII quantum yield, and maximum electron transport rates of the alga decreased sharply. At first, the algal cells enhanced the activities of some antioxidative enzymes, but subsequently, the activities of antioxidative enzymes fell sharply once damage of the algal cells was achieved. The filtrate from strain TL1 culture suspension, after autoclaving and treatments with proteinase K, strongly inhibited algal growth, indicating that the lytic metabolites were extracellular and thermostable, not a protein.

Cultivation of the brown alga Hizikia fusiformis (Harvey) Okamura: controlled fertilization and early development of seedlings in raceway tanks in ambient light and temperature

Commercial cultivation of the dioecious brown macroalga Hizikia fusiformis (Harvey) Okamura in East Asia depends on the supply of young seedlings from regenerated holdfasts or from wild population. Recent development of synchronized release of male and female gametes in tumble culture provides a possibility of mass production of young seedlings via sexual reproduction. In this paper, we demonstrate that controlled fertilization can be efficiently realized in ambient light and temperature in a specially designed raceway tank in which the sperm-containing water has been recirculated. The effective fertilization time of eggs by sperm was found to be within six hours. Fast growth and development of the young seedlings relied on the presence of water currents. Velocity tests demonstrated that young seedlings of 2-3 mm in length could withstand a water current of 190 cm s(-1) stop without detachment. Culture experiments at 24 h postfertilization showed that elongation of both the seedlings and their rhizoids were not hampered by high irradiance up to 600 mu mol photons m(-2) stop s(-1) stop. However, growth was slightly retarded if cultured at a temperature of 16 degrees C compared to other culture temperatures of 22, 25 and 29 degrees C. No seedling detachment was observed after transfer of the young seedlings to raft cultivation in the sea after one and 1.5 months post-fertilization, indicating the feasibility of obtaining large quantity of seedlings in such a system.

The cDNA cloning and mRNA expression of a potential selenium-binding protein gene in the scallop Chlamys farreri

Selenium binding proteins (SeBP) represent a family of proteins that are believed to be involved in controlling the oxidation/reduction in many physiological processes. The cDNA of Zhikong Scallop Chlamys farreri selenium binding protein (zSeBP) was cloned by expressed sequence tag (EST) and RACE techniques. The high similarity of zSeBP deduced amino acid sequence with the SeBP in other organisms, such as bird, fish, frog, mosquito, fruit fly, mammalian, and even nematode and microorganism indicated that zSeBP should be a member of SeBP family. The temporal expression of zSeBP in the hemocytes was measured by semi-quantitative RT-PCR after scallops were stimulated by either oxidative stress or microbial challenge. The expression of zSeBP was up-regulated progressively after stimulation, and then dropped gradually to the original level. Meanwhile, malondialdehyde (MDA) measured by the colorimetric method in the microbial challenged scallops increased immediately after scallops was challenged by microbes, and was significantly higher than that in the control scallops. Results indicated that the microbial infection could incense the disorder of oxidation/reduction and may result in high MDA production. The negative correlation between the expression level of zSeBP and the MDA content suggested that zSeBP could play an important role in mediating the anti-oxidation mechanisms and immune response in marine invertebrates. (c) 2005 Published by Elsevier Ltd.