<Emphasis Type="Italic">GST</Emphasis> (<Emphasis Type="Italic">phi</Emphasis>) gene from Macrophyte <Emphasis Type="Italic">Lemna minor</Emphasis> is involved in cadmium exposure responses

Reactive oxygen species (ROS) scavengers, including ascorbate peroxidase, superoxide dismutase, catalase and peroxidase, are the most commonly used biomarkers in assessing an organisms’ response to many biotic and abiotic stresses. In this study, we cloned an 866 bp GST (phi) gene in Lemna minor and investigated its characteristics, expression and enzymatic activities under 75 μmol/L cadmium concentrations in comparison with other ROS scavengers. GST (phi) gene expression patterns were similar to those of other scavengers of ROS. This suggests that GST (phi) might be involved in responding to heavy metal (cadmium) stress and that its expression level could be used as a bio-indicator in monitoring cadmium pollution.     

Changes of Biogenic Elements in <Emphasis Type="Italic">Phragmites australis</Emphasis> and <Emphasis Type="Italic">Suaeda salsa</Emphasis> from Salt Marshes in Yellow River Delta,China

Little information is available on biogenic elements (carbon, nitrogen, phosphorus and sulfur) and the ecological stoichiometric characteristics of plants in coastal wetlands. To investigate the contents of carbon, nitrogen, phosphorus and sulfur of plants, and their ecological stoichiometric characteristics in the Yellow (Huanghe) River Delta, plant samples were collected from two typical salt marshes (Suaeda salsa and Phragmites australis wetlands) during the period of from August to October in 2007, and the ratios of C/N, C/P, N/P, C/N/P and C/N/P/S were calculated. Results showed that during the studying period, plant C, N and P were lower than the global average values, and plant N and P were lower than the China’s average values. Leaf C and S in Suaeda salsa were significantly lower than those in Phragmites australis (P < 0.05), and leaf N and P in Suaeda salsa and Phragmites australis showed no significant differences (P > 0.05). Average C/N ratios were 23.75 in leaf, 73.36 in stem, 65.67 in root of Suaeda salsa, and 33.77 in leaf, 121.68 in stem, 97.13 in root of Phragmites australis. Average C/N ratios of Suaeda salsa and Phragmites australis were all great than 25, indicating the salt marsh in the Yellow River Delta is an N limitation system. Average C/P ratios were 276.78 in leaf, 709.28 in stem and 1031.32 in root of Suaeda salsa, and 536.94 in leaf, 768.13 in stem and 875.22 in root of Phragmites australis. The average N/P ratios of Suaeda salsa were 12.92 in leaf, 10.77 in stem and 10.91 in root, and the average N/P ratios of Phragmites australis were 16.40 in leaf, 7.40 in stem and 6.92 in root, indicating the Suaeda salsa wetlands were N limited and Phragmites australis wetlands were N limited in August and P limited in October in 2007. The average C/N, C/P and C/N/P ratios in Suaeda salsa and Pragmites australis were higher than the global average values, indicating the lower quality of organic matter provided by wetland plants in the Yellow River delta.     

Identification and characterization of a DnaJ gene from red alga <Emphasis Type="Italic">Pyropia yezoensis</Emphasis> (Bangiales,Rhodophyta)

Members of the DnaJ family are proteins that play a pivotal role in various cellular processes, such as protein folding, protein transport and cellular responses to stress. In the present study, we identified and characterized the full-length DnaJ cDNA sequence from expressed sequence tags of Pyropia yezoensis (PyDnaJ) via rapid identification of cDNA ends. This cDNA encoded a protein of 429 amino acids, which shared high sequence similarity with other identified DnaJ proteins, such as a heat shock protein 40/DnaJ from Pyropia haitanensis. The relative mRNA expression level of PyDnaJ was investigated using real-time PCR to determine its specific expression during the algal life cycle and during desiccation. The relative mRNA expression level in sporophytes was higher than that in gametophytes and significantly increased during the whole desiccation process. These results indicate that PyDnaJ is an authentic member of the DnaJ family in plants and red algae and might play a pivotal role in mitigating damage to P. yezoensis during desiccation.     

The characteristics of <Emphasis Type="Italic">vasa</Emphasis> gene from Japanese sea bass (<Emphasis Type="Italic">Lateolabrax japoni</Emphasis>cas) and its response to the external hormones

The RNA helicase Vasa is an important regulator of primordial germ cell development. Its function in mature fish, especially the hormone-related differences in maturing male fish has seldom been documented. In this study, a full length cDNA sequence of the vasa gene was cloned from Japanese sea bass, Lateolabrax japonicas, and it was named jsb-vasa. Homology analysis showed that jsb-vasa was closely related to its teleost homologs. The spatial distribution of jsb-vasa indicated that it was only highly expressed in testis, showing its germ cell-specific expression pattern. During the testicular development cycle, jsb-vasa was highly expressed during early period of spermatogenesis, and reduced when spermatogenesis advanced. In addition, the jsb-vasa gene expression was significantly inhibited at 6 h, 12 h and 24 h after injecting hCG (human chorionic gonadotropin) and GnRHa (Gonadotropin-releasing hormone analogue), indicating that jsb-vasa gene may play an important role in spermatogenesis of Japanese sea bass, and be under the regulation of external sex hormones.     

Response of phytoplankton community structure and size-fractionated Chlorophyll <Emphasis Type="Italic">a</Emphasis> in an upwelling simulation experiment in the western South China Sea

The South China Sea (SCS), which is the largest marginal sea in the western tropical Pacific, plays an important role in regional climate change. However, the research on the phytoplankton community structure (PCS) response to the upwelling remains inadequate. In January 2014, the upwelling simulation experiment was performed in the western SCS. Results indicate that the nutrient-rich bottom water not only increased the total Chlorophyll a (Chl a) concentrations, but would potentially altered the PCS. Due to new nutrients added, microphytoplankton had more sensitivity response to nutrient uptake than other phytoplankton groups. The variation of nutrients induced by formation, weakening and disappearance of upwelling resulted in phytoplankton species succession from cyanophyta to bacillariophyta. It may be the leading factor of the changes in PCS and size-fractionated Chl a. The initial concentration of DIP less than 0.1 μmolL^?1 could not sustain the phytoplankton growth. This indicates that phosphorus may be the limiting factor in the western SCS.     

Effects of different phosphorus concentrations and N/P ratios on the growth and photosynthetic characteristics of <Emphasis Type="Italic">Skeletonema costatum</Emphasis> and <Emphasis Type="Italic">Prorocentrum donghaiense</Emphasis>

The effects of different phosphorus (P) concentrations (0.36, 3.6, and 36 μmol/L corresponding to low-, middle-, and high-P concentration groups, respectively) and nitrogen (N)/P ratios on the growth and photosynthetic characteristics of Skeletonema costatum and Prorocentrum donghaiense were studied. For both species, the high-P (HP) concentration group showed the greatest algal density and highest specific growth rate. Changes in the maximum efficiency of photosystem II (F _v /F _m ) were monitored under the various P and N/P conditions. The largest decrease in F _v /F _m was in the low-P (LP) group in S. costatum and in the HP group in P. donghaiense. There were high rapid light curves and photochemical quantum yields (Φ _PSII) for S. costatum in the HP group, while the actual photosynthetic capacity was higher in P. donghaiense than in S. costatum in the MP group. Under eutrophic but relatively P-restricted conditions, P. donghaiense had higher photosynthetic activity and potential, which could cause this dinoflagellate to increasingly dominate the phytoplankton community in these conditions. Under the same P concentration and N/P ratio, P. donghaiense had a larger relative maximum rate of electron transport and higher Φ _{PS II} values than those of S. costatum. These differences between P. donghaiense and S. costatum may explain the interaction and succession patterns of these two species in the Changjiang (Yangtze) River estuary from a photosynthesis perspective.     

Determination of photosynthetic parameters in two seawater-tolerant vegetables

It is difficult to determine the photosynthetic parameters of non-flat leaves/green stems using photosynthetic instruments, due to the unusual morphology of both organs, especially for Suaeda salsa and Salicornia bigelovii as two seawater-tolerant vegetables. To solve the problem, we developed a simple, practical, and effective method to measure and calculate the photosynthetic parameters (such as P _N, g _s, E) based on unit fresh mass, instead of leaf area. The light/CO₂/temperature response curves of the plants can also be measured by this method. This new method is more effective, stable, and reliable than conventional methods for plants with non-flat leaves. In addition, the relative notes on measurements and calculation of photosynthetic parameters were discussed in this paper. This method solves technical difficulties in photosynthetic parameter determination of the two seawater-tolerant vegetables and similar plants.     

Heavy metals in sediments and their bioaccumulation in <Emphasis Type="Italic">Phragmites australis</Emphasis> in the Anzali wetland of Iran

Accumulation of metals in both sediments and Phragmites australis organs was studied. Samples were collected from seven stations located in Anzali wetland, Iran. The samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that concentration of the studied metals (except As and Cd) were higher in sediments than in P. australis organs. Metal accumulation was found to be significantly (P <0.05) higher in roots than in above-ground organs of P. australis. The bioaccumulation factor (BAF) and the transfer factor (TF) also verified the highest rate of metal accumulation in roots and their reduced mobility from roots to the above-ground organs. Pearson correlation coefficient showed significant relationships between metal concentrations in sediments and those in plant organs. It should be pointed out that sediment and plant samples exhibited higher metal concentrations in eastern and central parts than in western and southern parts of the wetland. The mean concentrations of all studied elements (except for Fe, V and Al) were higher in these sediment samples than in the Earth’s crust and shale. High accumulation of metals in P. australis organs (roots and shoots) is indicative of their high bioavailability in sediments of the wetland. The correlation between metal concentrations in sediments and in P. australis indicates that plant organs are good bioindicators of metal pollution in sediments of Anzali wetland.     

Immunogenicity and protective role of antigenic regions from five outer membrane proteins of <Emphasis Type="Italic">Flavobacterium columnare</Emphasis> in grass carp <Emphasis Type="Italic">Ctenopharyngodon idella</Emphasis>

Flavobacterium columnare causes columnaris disease in freshwater fish. In the present study, the antigenic regions of five outer membrane proteins (OMPs), including zinc metalloprotease, prolyl oligopeptidase, thermolysin, collagenase and chondroitin AC lyase, were bioinformatically analyzed, fused together, and then expressed as a recombinant fusion protein in Escherichia coli. The expressed protein of 95.6 kDa, as estimated by 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was consistent with the molecular weight deduced from the amino acid sequence. The purified recombinant protein was used to vaccinate the grass carp, Ctenopharyngodon idella. Following vaccination of the fish their IgM antibody levels were examined, as was the expression of IgM, IgD and IgZ immunoglobulin genes and other genes such as MHC Iα and MHC IIβ, which are also involved in adaptive immunity. Interleukin genes (IL), including IL-1β, IL-8 and IL-10, and type I and type II interferon (IFN) genes were also examined. At 3 and 4 weeks post-vaccination (wpv), significant increases in IgM antibody levels were observed in the fish vaccinated with the recombinant fusion protein, and an increase in the expression levels of IgM, IgD and IgZ genes was also detected following the vaccinations, thus indicating that an adaptive immune response was induced by the vaccinations. Early increases in the expression levels of IL and IFN genes were also observed in the vaccinated fish. At four wpv, the fish were challenged with F. columnare, and the vaccinated fish showed a good level of protection against this pathogen, with 39% relative percent survival (RPS) compared with the control group. It can be concluded, therefore, that the five OMPs, in the form of a recombinant fusion protein vaccine, induced an immune response in fish and protection against F. columnare.     

Variations in leaf functional traits and physiological characteristics of <Emphasis Type="Italic">Abies georgei</Emphasis> var. <Emphasis Type="Italic">smithii</Emphasis> along the altitude gradient in the Southeastern Tibetan Plateau

Variations in leaf functional traits of Abies georgei var. smithii at 3700, 3900, 4100, 4300, and 4390 m altitude were investigated in 15 typical plots in the Southeastern Tibetan Plateau. In each plot, three seedlings were selected, of which functional leaves in current-year sunny branches were chosen for the measurement of morphological, photosynthetic, and physiological and biochemical characteristics, and their variations were analyzed. Results showed that significant variations existed among the leaf functional traits of A. georgei var. smithii along the altitudinal gradient, as well as their physiological adaption indicators. Leaf area decreased, while the mass per area and thickness of leaf increased at an altitude above 4,100 m. The maxima of pigment, total nitrogen concentration, net photosynthesis rate during light-saturated, and when water use efficiency appeared at 4100 m altitude. In addition, A. georgei var. smithii seedlings regulated the activities of superoxide dismutase and ascorbate peroxidase to resist abiotic stress under 4100 m altitude. Meanwhile, malondialdehyde concentration and the dark respiration rate rapidly increased, which indicates that A. georgei var. smithii seedlings suffered from heavy abiotic stress from 4100 m to 4390 m altitude. Basing on variations in leaf functional traits along the altitude gradient, we inferred that 4100 m altitude was the suitable region for A. georgei var. smithii growth in the Sygera Mountain. Moreover, the harsh environment was the main limiting factor for A. georgei var. smithii population expansion to high altitude.     

Inbreeding depression on growth and survival of full-sib family of Manila clam (<Emphasis Type="Italic">Ruditapes philippinarum</Emphasis>)

In present study, the inbreeding depression (ID) of growth and survival of Manila clam (Ruditapes philippinarum) was investigated at larval and juvenile stages. Nine inbred families (A ₂, B ₂, C ₂, D ₂, E ₂, F ₂, G ₂, H ₂ and I ₂) were established by mating within nine full-sib families with expected inbreeding coefficient of 0.25. Inbred families showed significant differences in shell length and hatching rate of D-larvae (straight-hinged larvae). The larvae of the nine inbred families grew slower than those of control group (CG), and their ID value ranged from 0.81% ± 6.09% to 16.10% ± 1.49%. The ID value of larval survival rate varied between 27.47% ± 9.36% and 70.50% ± 13.66%. The ID was also detected for juvenile growth in A ₂, B ₂, C ₂, and D ₂, which ranged from 4.60 ± 2.21 to 17.71 ± 7.73. The A ₂ family maintained the highest juvenile survival rate, whereas the other inbred families exhibited ID values varying between 62.79% ± 4.54% and 96.14% ± 0.87%. The linear relationship of estimated ID between growth and survival was negatively correlated (R = ?0.434, P < 0.05). The results of this study suggested that the ID of growth was common at the larval stage but was less prevalent at juvenile stage. In contrast, the ID of survival increased from larval to juvenile stage. A better understanding of the effect of inbreeding may aid to selective breeding of Manila clam.     

A review of interaction between neon flying squid (<Emphasis Type="Italic">Ommastrephes bartramii</Emphasis>) and oceanographic variability in the North Pacific Ocean

The neon flying squid (Ommastrephes bartramii) is a short-lived opportunistic species widely distributed in subtropical and temperate waters in the North Pacific Ocean. The life cycle of O. bartramii from planktonic eggs to nektonic adults is closely linked to oceanographic conditions. The fluctuations in O. bartramii abundance and distribution tend to increase and widen continuously due to the heavy influences of ocean-climate events on various spatio-temporal scales. In this study, we reviewed the interaction between O. bartramii and oceanography variability in the North Pacific with respect to large-scale climatic-oceanic phenomena including El Niño, La Niña, Kuroshio, Oyashio and Pacific Decadal Oscillation (PDO), as well as regional environmental variables such as sea surface temperature (SST), sea surface height (SSH), sea surface salinity (SSS), chlorophyll-a (Chl-a) concentration, and plankton density. The population dynamics of O. bartramii is mediated mainly by meso- and large-scale climatic-oceanic events (e.g., Kuroshio and Oyashio Currents) rather than other local environmental conditions (e.g., SST and Chl-a concentration), because all of the oceanographic influences are imposed on the context of large-scale climate changes (e.g., PDO). An unstructured-grid finite-volume coastal ocean model coupled with an individual-based model is proposed to simulate relevant physical-biological oceanographic processes for identifying ocean-climate influence and predicting O. bartramii distribution and abundance in the North Pacific. Future research needs to be focused on improving the knowledge about early life history of O. bartramii and evaluating the relationship between marine physical environment and two separate passive drifting life stages of O. bartramii including free-floating eggs and planktonic paralarvae.     

Assessment and comparison of <Emphasis Type="Italic">in vitro</Emphasis> immunoregulatory activity of three astaxanthin stereoisomers

In recent years, the immune-modulatory role of all-trans astaxanthin from different pigment sources has been studied. It was reported that all-trans astaxanthin might exist as three stereoisomers, and the composition of all-trans stereoisomers in natural materials differs from that of synthetic products. However, the different biological effects of various all-trans stereoisomers still remain unclear. In the present study, we evaluated the bioactivity of three astaxanthin stereoisomers, (3S,3’S)-trans-, (3R,3’R)-trans-and meso-trans-astaxanthin, in regulating cell-mediated immune response using mice lymphocytes and peritoneal exudates cells (PECs) systems. After the treatment with three astaxanthin stereoisomers (20 μmol L^?1), the lymphocyte proliferation capacity, neutral red phagocytosis of PECs and natural killer (NK) cell cytotoxic activity were comparatively assessed. The results showed that all three astaxanthin stereoisomers significantly promoted lymphocyte proliferation, phagocytic capacity of PECs, and cytotoxic activity of NK cells. Moreover, the (3S,3’S)-trans-astaxanthin exhibited a much higher response than others.     

Significance of different microalgal species for growth of moon jellyfish ephyrae, <Emphasis Type="Italic">Aurelia</Emphasis> sp.1

The scyphozoan Aurelia aurita (Linnaeus) sp. l., is a cosmopolitan species-complex which blooms seasonally in a variety of coastal and shelf sea environments around the world. The effects of different microalgal species on the growth of newly-released Aurelia sp.1 ephyrae were studied under laboratory conditions. We fed ephyrae with four different microalgal species (diatom, autotrophic dinoflagellate, heterotrophic dinoflagellate, and chlorophyta) plus Artemia nauplii for 12-24 d at 18°C. Results showed that the growth rate diverged significantly for Artemia nauplii compared to other food types. In addition, there was no significant variation between the growth rates for Skeletonema costatum and Prorocentrum donghaiense, and no significant variation was found in the growth rates for N. scintillans and P. subcordiformis. Artemia nauplii could support the energy requirement for the newly-released ephyrae to develop to meduase, and the ephyrae with Artemia nauplii showed a significant average growth rate of 25.85% d^?1. Newly-released ephyrae could grow slightly with some species of microalgae in the earliest development stage. Chain diatom Skeletonema costatum and autotrophic dinoflagellate Prorocentrum donghaiense, could not support the growth of the ephyrae, while heterotrophic dinoflagellate Noctiluca scintillans and chlorophyta Platymonas subcordiformis could support the growth of the ephyrae. However, none of the ephyrae fed with the tested phytoplankton could mature to medusae.     

Effects of dietary genistein on GH/IGF-I axis of Nile tilapia <Emphasis Type="Italic">Oreochromis niloticus</Emphasis>

There is considerable concern that isoflavones, such as genistein in fish feed composed of soybean protein, aff ects somatic growth in fish. Our previous works demonstrated that 30 and 300 μg/g dietary genistein had no significant eff ect on growth performance in Nile tilapia (Oreochromis niloticus), but the higher level of genistein (3 000 μg/g) significantly depressed growth. This study was conducted to further examine the eff ects of dietary genistein on the endocrine disruption on growth hormone/insulin-like growth factor-I (GH/IGF-I) axis in Nile tilapia (O. niloticus). Juvenile fish were fed by hand twice daily to satiation with one of four isonitrogenous and isoenergetic diets, each containing either 0, 30, 300 or 3 000 μg/g genistein. Following an 8-week feeding period, plasma GH and IGF-I levels were investigated by radioimmunoassay and gene expression levels of gh, ghrelin, gnrhs, ghr, npy, npyrs, pacap, ghrs, igf-I, igf-Ir, and igfbp3 were examined by real-time PCR. The results show that no significant change in plasma GH and IGF-I levels in fish fed with diets containing 30 μg/g and 300 μg/g genistein. mRNA expression of genes along the GH/IGF-I axis remained unaff ected, except for igf-Ir, which was stimulated by the 300 μg/g genistein diet. While in fish fed the 3 000 μg/g genistein diet, the plasma GH and IGF-I levels decreased, and mRNA expression of gh, ghr2, npyr1, igf-I, and igf-Ir were also significantly depressed. In contrast, npy and igfbp3 mRNA expression were enhanced. This study provides convincing evidence for growth impediment by genistein by disturbing the GH/IGF-I axis in Nile tilapia O. niloticus.     

Impact of <Emphasis Type="Italic">Vibrio parahaemolyticus</Emphasis> and white spot syndrome virus (WSSV) co-infection on survival of penaeid shrimp <Emphasis Type="Italic">Litopenaeus vannamei</Emphasis>

White spot syndrome virus (WSSV) is an important viral pathogen that infects farmed penaeid shrimp, and the threat of Vibrio parahaemolyticus infection to shrimp farming has become increasingly severe. Viral and bacterial cross or superimposed infections may induce higher shrimp mortality. We used a feeding method to infect Litopenaeus vannamei with WSSV and then injected a low dose of V. parahaemolyticus (WSSV+Vp), or we first infected L. vannamei with a low-dose injection of V. parahaemolyticus and then fed the shrimp WSSV to achieve viral infection (Vp+WSSV). The eff ect of V. parahaemolyticus and WSSV co-infection on survival of L. vannamei was evaluated by comparing cumulative mortality rates between experimental and control groups. We also spread L. vannamei hemolymph on thiosulfate citrate bile salt sucrose agar plates to determine the number of Vibrio, and the WSSV copy number in L. vannamei gills was determined using an absolute quantitative polymerase chain reaction (PCR) method. LvMyD88 and Lvakt gene expression levels were detected in gills of L. vannamei by real-time PCR to determine the cause of the diff erent mortality rates. Our results show that (1) the cumulative mortality rate of L. vannamei in the WSSV+Vp group reached 100% on day 10 after WSSV infection, whereas the cumulative mortality rate of L. vannamei in the Vp+WSSV group and the WSSV-alone control group approached 100% on days 11 and 13 of infection; (2) the number of Vibrio in the L. vannamei group infected with V. parahaemolyticus alone declined gradually, whereas the other groups showed significant increases in the numbers of Vibrio (P<0.05); (3) the WSSV copy numbers in the gills of the WSSV+Vp, Vp+WSSV, and the WSSV-alone groups increased from 10⁵ to 10⁷ /mg tissue 72, 96, and 144 h after infection, respectively. These results suggest that V. parahaemolyticus infection accelerated proliferation of WSSV in L. vannamei and vice versa. The combined accelerated proliferation of both V. parahaemolyticus and WSSV led to massive death of L. vannamei.