Antiviral Effects of Stichopus japonicus Acid Mucopolysaccharide on Hepatitis B Virus Transgenic Mice

Hepatitis B virus(HBV) is a significant global pathogen and efficient cure for HBV patients is still a challenging goal. We previously reported that acidic mucopolysaccharide from stichopus japonicus selenka(SJAMP) could inhibit HBs Ag and HBe Ag expression in vitro. However, the potential anti-HBV effects of SJAMP in vivo have not yet been explored. In this study, we show that SJAMP exhibits potent anti-HBV activity in HBV transgenic mice in a dose-dependent manner. Specifically, sixty HBV transgenic male BALB/c mice were randomly selected to receive the treatment of PBS, low dose SJAMP(30 mg kg~(-1)), middle dose SJAMP(40 mg kg~(-1)), high dose SJAMP(50 mg kg~(-1)) and IFN(45 IU kg~(-1)) for 30 d. SJAMP treatment suppressed serum HBV-DNA, and liver HBs Ag and HBc Ag levels in HBV-transgenic mice. The present study highlights the potential application of SJAMP in HBV therapy.     

Molecular weight controllable degradation of <Emphasis Type="Italic">Laminaria japonica</Emphasis> polysaccharides and its antioxidant properties

In this study, molecular weight controllable degradation of algal Laminaria japonica polysaccharides（LPS） was investigated by ultrasound combined with hydrogen peroxide. Three main factors, i.e., ultrasonic power（A）, ultrasonic time（B）, and H₂O₂ concentration（C） were chosen for optimizing parameters by employing three-factors, three-levels BBD. The influence of degradation on structure change and antioxidant activities was also investigated. A second-order polynomial equation including molecular weight（Y） of Laminaria japonica polysaccharides and each variable parameter, i.e., ultrasonic power（A）, ultrasonic time（B）, and H₂O₂ concentration（C）, was established: Y=20718.67-4273.13A-4000.38B-1438.75C+2333.25AB+1511.00AC+873.00BC+2838.29A² + 2490.79B²+873.04C². The equation regression coefficient value（R² = 0.969） indicated that this equation was valid. The value of the adjusted determination coefficient（adjusted R² = 0.914） also confirmed that the model was highly significant. The results of selected experimental degradation conditions matched with the predicted value. FT-IR spectra revealed that the structures of LPS before and after degradation were not significantly changed. Antioxidant activities of LPS revealed that low Mws possessed stronger inhibitory than the original polysaccharides. The scavenging effects on superoxide radicals was the highest when IC50 of crude LPS was 4.92 mg mL^-1 and IC50 of Mw 18.576 KDa was 1.02 mg mL^-1, which was fourfold higher than initial polysaccharide.     

Effects of a Potential Autochthonous Probiotic <Emphasis Type="Italic">Bacillus subtilis</Emphasis> 2-1 on the Growth and Intestinal Microbiota of Juvenile Sea Cucumber, <Emphasis Type="Italic">Apostichopus japonicus</Emphasis> Selenka

The effects of Bacillus subtilis 2-1 from the intestine of healthy sea cucumber on the growth, digestive enzyme activities and intestinal microbiota of juvenile sea cucumber (Apostichopus japonicus) were determined in the present study. Sea cucumber was fed with Sargassum thunbergii powder supplemented with B. subtilis 2-1 at different concentrations varying among 0 (control), 10⁵, 10⁷, and 10⁹ CFU g^?1 for 8 weeks. Results showed that the growth performance and intestinal amylase and trypsin activities were significantly increased by dietary B. subtilis 2-1 at 10⁹ CFU g^?1 (P < 0.05). However, dietary B. subtilis 2-1 had no significant influence on the lipase activity in sea cucumber (P > 0.05). The polymerase chain reaction denaturing gradient gel electrophoresis and 16S rRNA gene sequencing analysis indicated that dietary B. subtilis 2-1 at 10⁵ and 10⁷ CFU g^?1 inhibited most of the Proteobacteria including those in genus Vibrio. Dietary B. subtilis 2-1 at 10⁹ CFU g^?1 not only decreased the abundance and species of genus Vibrio, but also increased the intensity of genera Psychrobacter and Bacillus. A specific dosage of dietary B. subtilis 2-1 could increase the growth and modulate the intestinal microbiota of sea cucumber; thus it might be a novel probiotic for keeping the health of sea cucumber.     

Temporal and spatial variations of abundance of phycocyanin- and phycoerythrin-rich <Emphasis Type="Italic">Synechococcus</Emphasis> in Pearl River Estuary and adjacent coastal area

Three surveys were carried out in Pearl River Estuary and adjacent coastal area in May, August, and November, 2013, to investigate the temporal and spatial variations of abundance of phycoerythrin-rich Synechococcus (PE-rich SYN) and phycocyanin-rich Synechococcus (PC-rich SYN). The effects of environmental factors on the alternation of the different Synechococcus groups were also elucidated. PE-rich SYN was detected in three surveys, whereas PC-rich SYN was detected in May and August, but not in November. The highest abundances of PE-rich SYN and PC-rich SYN were recorded in August and May, with mean values of 74.17×10³ and 189.92×10³ cells mL^?1, respectively. From May to November, the relative abundance of PE-rich SYN increased, whereas that of PC-rich SYN declined. PE-rich and PC-rich SYN presented similar horizontal distributions with high abundance in the southern estuary in May, and in the western estuary in August. The abundances of PE-rich and PC-rich SYN were high at 27–32°C and salinity of 10–20. PC-rich SYN was not detected at < 24°C, and PC:PE-rich SYN decreased in abundance with salinity increase. When less than 20 mg L^?1, suspended particulate matter (SPM) was helpful for Synechococcus growth. PE-rich SYN decreased in abundance when the concentration of dissolved inorganic nitrogen increased in May and November, and the concentration of phosphate increased in November. However, PC-rich SYN abundance and nutrients showed no correlation. Principal component analysis and regression analysis indicated that PE-rich SYN significantly correlated with the principal components that were affected by environmental factors.     

Distribution patterns of chlorophyll <Emphasis Type="Italic">a</Emphasis> in spring and autumn in association with hydrological features in the southern Yellow Sea and northern East China Sea

Two field studies were conducted to measure pigments in the Southern Yellow Sea (SYS) and the northern East China Sea (NECS) in April (spring) and September (autumn) to evaluate the distribution pattern of phytoplankton stock (Chl a concentration) and the impact of hydrological features such as water mass, mixing and tidal front on these patterns. The results indicated that the Chl a concentration was 2.43±2.64 (Mean ± SD) mg m^?3 in April (range, 0.35 to 17.02 mg m^?3) and 1.75±3.10 mg m^?3 in September (from 0.07 to 36.54 mg m^?3) in 2003. Additionally, four areas with higher Chl a concentrations were observed in the surface water in April, while two were observed in September, and these areas were located within or near the point at which different water masses converged (temperature front area). The distribution pattern of Chl a was generally consistent between onshore and offshore stations at different depths in April and September. Specifically, higher Chl a concentrations were observed along the coastal line in September, which consisted of a mixing area and a tidal front area, although the distributional pattern of Chl a concentrations varied along transects in April. The maximum Chl a concentration at each station was observed in the surface and subsurface layer (0–10 m) for onshore stations and the thermocline layer (10–30 m) for offshore stations in September, while the greatest concentrations were generally observed in surface and subsurface water (0–10 m) in April. The formation of the Chl a distributional pattern in the SYS and NECS and its relationship with possible influencing factors is also discussed. Although physical forces had a close relationship with Chl a distribution, more data are required to clearly and comprehensively elucidate the spatial pattern dynamics of Chl a in the SYS and NECS.     

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.     

Equality testing for soil grid unit resolutions to polygon unit scales with DNDC modeling of regional SOC pools

Matching soil grid unit resolutions with polygon unit map scales is important to minimize the uncertainty of regional soil organic carbon(SOC) pool simulation due to their strong influences on the modeling.A series of soil grid units at varying cell sizes was derived from soil polygon units at six map scales,namely,1:50 000(C5),1:200 000(D2),1:500 000(P5),1:1 000 000(N1),1:4 000 000(N4) and 1:14 000 000(N14),in the Taihu Region of China.Both soil unit formats were used for regional SOC pool simulation with a De Nitrification-DeC omposition(DNDC) process-based model,which spans the time period from 1982 to 2000 at the six map scales.Four indices,namely,soil type number(STN),area(AREA),average SOC density(ASOCD) and total SOC stocks(SOCS) of surface paddy soils that were simulated by the DNDC,were distinguished from all these soil polygon and grid units.Subjecting to the four index values(IV) from the parent polygon units,the variations in an index value(VIV,%) from the grid units were used to assess its dataset accuracy and redundancy,which reflects the uncertainty in the simulation of SOC pools.Optimal soil grid unit resolutions were generated and suggested for the DNDC simulation of regional SOC pools,matching their respective soil polygon unit map scales.With these optimal raster resolutions,the soil grid units datasets can have the same accuracy as their parent polygon units datasets without any redundancy,when VIV 1% was assumed to be a criterion for all four indices.A quadratic curve regression model,namely,y = – 0.80 × 10~(–6)x~2 + 0.0228 x + 0.0211(R~2 = 0.9994,P 0.05),and a power function model R? = 10.394?~(0.2153)(R~2 = 0.9759,P 0.05) were revealed,which describe the relationship between the optimal soil grid unit resolution(y,km) and soil polygon unit map scale(1:10 000x),the ratio(R?,%) of the optimal soil grid size to average polygon patch size(?,km~2) and the ?,with the highest R~2 among different mathematical regressions,respectively.This knowledge may facilitate the grid partitioning of regions during the investigation and simulation of SOC pool dynamics at a certain map scale,and be referenced to other landscape polygon patches' mesh partition.     

Genetic transformation of <Emphasis Type="Italic">Nannochloropsis oculata</Emphasis> with a bacterial phleomycin resistance gene as dominant selective marker

The gene ble from Streptoalloteichus hindustanus is widely used as a selective antibiotic marker. It can control the phleomycin resistance, and significantly increase the tolerance of hosts to zeocin. The unicellular marine microalga Nannochloropsis oculata is extremely sensitive to zeocin. We selected ble as the selective marker for the genetic transformation of N. oculata. After the algal cells at a density of 2×10⁷ cells mL^?1 was digested with 4% hemicellulase and 2% driselase for 1 h, the protoplasts accounted for 90% of the total. The ble was placed at the downstream of promoter HSP70A-RUBS2 isolated from Chlamydomonas reinhardtii, yielding a recombinant expression construct pMS188. The construct was transferred into the protoplasts through electroporation (1 kV, 15 μS). The transformed protoplasts were cultured in fresh f/2 liquid medium, and selected on solid f/2 medium supplemented with 500 ng mL^?1 zeocin. The PCR result proved that ble existed in the transformants. Three transformants had been cultured for at least 5 generations without losing ble. Southern blotting analysis showed that the ble has been integrated into the genome of N. oculata. The ble will serve as a new dominant selective marker in genetic engineering N. oculata.     

Antialgal and antilarval activities of bioactive compounds extracted from the marine dinoflagellate <Emphasis Type="Italic">Amphidinium carterae</Emphasis>

With the global ban on the application of organotin-based marine coatings by the International Maritime Organization, the development of environmentally friendly, low-toxic and nontoxic antifouling compounds for marine industries has become an urgent need. Marine microorganisms have been considered as a potential source of natural antifoulants. In this study, the antifouling potential of marine dinoflagellate Amphidinium carterae, the toxic and red-tide microalgae, was investigated. We performed a series of operations to extract the bioactive substances from Amphidinium carterae and tested their antialgal and antilarval activities. The crude extract of Amphidinium carterae showed significant antialgal activity and the EC₅₀ value against Skeletonema costatum was 55.4 μg mL^?1. After purification, the isolated bioactive substances (the organic extract C) exhibited much higher antialgal and antilarval activities with EC₅₀ of 12.9 μg mL^?1 against Skeletonema costatum and LC₅₀ of 15.1 μg mL^?1 against Amphibalanus amphitrite larvae. Subsequently, IR, Q-TOFMS, and GC-MS were utilized for the structural elucidation of the bioactive compounds, and a series of unsaturated and saturated 16- to 22-carbon fatty acids were detected. The data suggested the bioactive compounds isolated from Amphidinium carterae exhibited a significant inhibiting effect against the diatom Skeletonema costatum and Amphibalanus amphitrite larvae, and could be substitutes for persistent, toxic antifouling compounds.     

Carbon budget of bastard halibut<Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> in relation to body weight and temperature

The effects of body weight and temperature on the carbon budget of the juvenile bastard halibut ,Paralichthys olivaceus ,were studied at temperature 13.5,18,21.5 and 24℃,respectively.The carbon intake,faecal and growth carbon were measured ,and the carbon respiration was calculated using the carbon budget equation (Cc=Gc Fc Rc),The combined relationship between different components of the carbon budgent,body weight and temperature could be described by regression equations:Cc=1.0206 W^0.8126E^0.1483T;Gc=0.0042w^1.4096(-5.11 T^3 285.90T^2-5173.72T 30314.03);Fc=0.0485W^0.7711e^0.1624T;Uc=1.4333W^0.6715e^0.1487t,Body weight had no significant effect on the carbon absorption efficiency and the conversion efficiency.     

Biodegradation of <Emphasis Type="Italic">Enteromorpha</Emphasis> polysaccharides by intestinal micro-community from <Emphasis Type="Italic">Siganus oramin</Emphasis>

Micro-communities are supposed to have more potential functions of biodegradation of polysaccharides than single strain; however, the intestinal micro-communities involved in the biodegradation of Enteromorpha polysaccharides (EP) were seldom reported. In order to obtain the EP-degrading micro-community, the intestines of Siganus oramin was obtained to isolate the micro-communities, which were enriched by 0.3% of EP as the sole carbon source. A stable micro-community with EP degradative capability was achieved after seven generations of subculture, named H1. Results showed that H1 was able to degrade 75% of EP within 24 hours, and the activity of EP lyases reached 500 U mL^?1 in 32 hours. With denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone library analysis, ten bacteria closely related to Marinomonas pontica, Microbacterium sp., Leucobacter chironomi, Cyclobacterium sp., Algoriphagus winogradskyi, Pseudoalteromonas sp. and Vibrio sp. were determined. Furthermore, compared with the DGGE bands sequence and the clone library analysis, the dominant bacteria of the EP-biodegrading micro- community were Pseudoalteromonas sp. and Vibrio sp., with the respective proportion of 38% and 46%, and they should play an important role in EP degradation together with other degrading bacteria in the micro-community H1.     

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.     

Effects of nitrogen and phosphorus on the growth of <Emphasis Type="Italic">Levanderina fissa</Emphasis>: How it blooms in Pearl River Estuary

Effects of nitrogen (N) and phosphorus (P) from different sources and at different concentrations on the growth of Levanderina fissa (= Gyrodinium instriatum) were studied in laboratory conditions. The findings might explain the recurrent blooms of this species in Pearl River Estuary, China. Results showed that nutrient limitation significantly inhibited the growth of L. fissa. The values of specific growth rate (μ _max) and half-saturation nutrient concentration (K _S) were 0.37 divisions/d and 8.49 μmol L^?1 for N, and 0.39 divisions/d and 1.99 μmol L^?1 for P, respectively. Based on K _S values, dissolved inorganic N level in PRE was sufficient to support the high proliferation of L. fissa, while dissolved inorganic P concentration was far lower than the minimum requirement for its effective growth. L. fissa was not able to utilize dissolved organic N (DON) compounds such as urea, amino acids, and uric acid. However, it grew well by using a wide variety of dissolved organic P (DOP) sources like nucleotides, glycerophosphate, and 4-nitrophenylphosphate. The results from this study suggested that the ability in DOP utilization of L. fissa offers this species a competitive advantage in phytoplankton communities. The high level and continuous supply of DIN, enrichment of DOP, together with warm climate and low salinity in the Pearl River Estuary provided a suitable nutrient niche for the growth of L. fissa, and resulted in the recurrent blooms in the estuary.     

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.     

Distribution of sediment chloroplastic pigments in the Southern Yellow Sea,China

The distribution of sediment chloroplastic pigments (Chl-a, i.e. chlorophyll a and Pha-a, i.e. phaeophorbide a) in the Southern Yellow Sea of China was studied. Samples were collected from four cruises in January and June 2003, and January and June 2004. The results show that the vertical distribution of Chl-a and Pha-a in the sediment layers 0-2cm, 2-5cm and 5-8cm, follows a stable ratio, 5:3:2. The average ratio of Pha-a to Chl-a in sediment is 2.83. Spearman 2-tailed rank correlation analysis shows that Chl-a and Pha-a contents in each sediment layer have a highly significant correlation. The average contents of Chl-a and Pha-a in the sediment of the 0-8cm layer in the investigated area are 0.31 -0.47μgg-1 and 1.28-1.40 μgg-1 sediment (dry weight), respectively. The average Chl-a and Pha-a contents in sediment are higher in summer than in winter. ANOVA analysis shows that there is a highly significant variation among the Chl-a contents (P = 0.002 <0.01) of the four cruies, but this is not true for the case of Pha-a content (P = 0.766>0.05). The average Chl-a and Pha-a contents in the 2 sediment layers (0-2cm and 2-5cm) have significant or highly significant correlations with organic matter (OM), median diameter (Mdφ), silt plus clay percentage in the January 2003 cruise. In the June 2003 cruise, the average Chl-a content in the 3 sediment layers (0-2cm, 2-5cm, and 5-8cm) has a significant correlation with meiofauna biomass, and Pha-a content has highly significant correlations with water depth, bottom water temperature, OM and Mdφ The contents of Chl-a and Pha-a are lower than those in estuaries and intertidal areas, but close to those in the same area studied previously.     

Diel variation in metabolism and ammonia excretion of <Emphasis Type="Italic">Marphysa sanguinea</Emphasis> (Polychaeta: Eunicidae)

Polychaetes provide an excellent food resource for fish and represent the dominant zoobenthos in marine ecosystems. Diel variation in the rates of metabolism and ammonia-N excretion of Marphysa sanguinea were studied. The worms were grouped according to their wet body weight into small (S; 1.24±0.06 g), medium (M; 4.00±0.30 g), and large (L; 8.54±1.08 g) categories. Their weight-specific metabolic rates, based on aerobic respiration (R), were measured at 16°C (±0.2°C) and classed as either routine (R _R) or standard (R _S) rates. Both respiration types decreased with increasing body weight. Respiration was described by R = a W ^b, where b was -0.400 9 and -0.532 0 for R _R and R _S, respectively. Diurnal changes in R _S for each group was relatively flat, with a slightly increasing trend with time, but was relatively stable as a whole. R _R of the diurnal variation of worms was higher than R S, but both had similar overall trends. The peak values of specific dynamic action (SDA) (R _SDA) in the S, M, and L groups were 2.704, 1.149, and 0.682 mg/(g?h), respectively. The durations of SDA were 13, 6, and 6 h, respectively and the energy expenditures of SDA were 377.98, 117.34, and 74.94 J/g, respectively. These data indicate that the metabolic rates were higher in smaller individuals, which is advantageous for their rapid growth.     

Biochemical Composition and Nutritional Value of Different Shell Color Strains of Pacific Oyster <Emphasis Type="Italic">Crassostrea gigas</Emphasis>

The shell color of Pacific oyster (Crassostrea gigas) is a desirable trait; but the nutritional studies on C. gigas with different shell colors have not been conducted. Through successive selective breeding, five shell color strains of black (B), purple (P), orange (O), golden (G) and white (W) C. gigas have been developed. The aim of this study was to evaluate the chemical composition and nutritional value of five shell color strains and one commercial population with a common color. The biochemical composition including moisture, total protein, glycogen, ash, total fat, fatty acids (FA), amino acids and minerals was detected. The results indicated that the protein (50.76%–56.57%) was the major component. The content of glycogen showed a significant difference between orange shell and golden shell strains, as well as between commercial population and golden shell strain. In addition, all shell color strains contained a large amount of essential amino acids (12.20–14.15 g (100 g)^?1), of them leucine (2.81–3.29 g (100 g)^?1) and lysine (2.79–3.28 g (100 g)^?1) were predominant. The oysters were rich in polyunsaturated fatty acids (42.26%–45.24% of total fatty acid) with high levels of DHA (18.53%–21.16% of total fatty acid) and EPA (17.23%–18.68% of total fatty acid). Significant differences of mineral contents (Mg, Zn, Fe and Cu) were identified among the six populations. These results indicated that C. gigas with different shell colors presented rich nutritional value with high protein, glycogen, essential amino acids and polyunsaturated fatty acids. The biochemical composition obtained in this study is useful for selective breeding of C. gigas with different shell colors.     

Lipid oxidation and fatty acid composition in salt-dried yellow croaker (<Emphasis Type="Italic">Pseudosciaena polyactis</Emphasis>) during processing

Lipid oxidation in salt-dried yellow croaker (Pseudosciaena polyactis) was evaluated during processing with commonly used analytical indices, such as the peroxide value (POV), the thiobarbituric acid reactive substances (TBARS) value, and oxidative-relative lipoxygenase (LOX) activity. Additionally, fatty acids were analyzed using gas chromatography-mass spectrometry. Both POV and TBARS increased significantly (P < 0.05) at the rinsing stage. POV reached its peak value of 3.63 meq O₂ per kg sample at the drying stage, whereas TBARS constantly increased from 0.05 to 0.20 mg MDA per kg sample. Processing of salt-dried yellow croaker had an extremely significant (P < 0.01) effect on LOX activity. Twenty-six fatty acids were identified. Combined eicosapentaenoic acid (EPA; C20:5n3) and docosahexaenoic acid (DHA; C22:6n3) content varied between (19.20 ± 0.37) mg g^?1 and (23.45 ± 1.05) mg g^?1. The polyunsaturated fatty acid/saturated fatty acid (PUFA/SFA) ratio in yellow croaker was 0.73–1.10, and the n-6/n-3 PUFA ratio was approximately 0.13–0.20. The contents of most fatty acids varied significantly (P < 0.05) during the different processing stages, and these differences were caused by lipid oxidation. C18:0, C16:1n7, C19:0, and C22:6n3 showed clear changes in principle component one of a principle components analysis. These fatty acids are potential markers for evaluating lipid oxidation in fish muscle because there was a significant correlation between these markers and TBARS and LOX activity (P < 0.05) with Pearson’s coefficients > 0.931.     

Effect of benzo[a]pyrene on detoxification and the activity of antioxidant enzymes of marine microalgae

The objective of this study was to examine the effect of benzo[a]pyrene(Ba P) on the detoxification and antioxidant systems of two microalgae,Isochrysis zhanjiangensis and Platymonas subcordiformis.In our study,these two algae were exposed to Ba P for 4 days at three different concentrations including 0.5 μg~(L-1)(low),3 μg~(L-1)(mid) and 18 μg~(L-1)(high).The activity of detoxification enzymes,ethoxyresorufin O-deethylase(EROD) and glutathione S-transferase(GST) increased in P.subcordiformis in all Ba P-treated groups.In I.zhanjiangensis,the activity of these two enzymes increased at the beginning of exposure,and then decreased in the groups treated with mid-and high Ba P.The activity of antioxidant enzyme superoxide dismutase(SOD) increased in I.zhanjiangensis in all Ba P-treated groups,and then decreased in high Ba P-treated group,while no significant change was observed in P.subcordiformis.The activity of antioxidant enzyme catalase(CAT) increased in I.zhanjiangensis and P.subcordiformis in all Ba Ptreated groups.The content of malondialdehyde(MDA) in Isochrysis zhanjiangensis increased first,and then decreased in high Ba P-treated group,while no change occurred in P.subcordiformis.These results demonstrated that Ba P significantly influenced the activity of detoxifying and antioxidant enzymes in microalgae.The metabolic related enzymes(EROD,GST and CAT) may serve as sensitive biomarkers of measuring the contamination level of Ba P in marine water.     

Comparison of stem taper models for the four tropical tree species in Mount Makiling,Philippines

This study was conducted to evaluate the performance of six stem taper models on four tropical tree species, namely Celtis luzonica (Magabuyo), Diplodiscus paniculatus (Balobo), Parashorea malaanonan (Bagtikan), and Swietenia macrophylla (Mahogany) in Mount Makiling Forest Reserve (MMFR), Philippines using fit statistics and lack-of-fit statistics. Four statistical criteria were used in this study, including the standard error of estimate (SEE), coefficient of determination (R ²), mean bias \(( \bar E )\), and absolute mean difference (AMD). For the lack-offit statistics, SEE, \(\bar E\) and AMD were determined in different relative height classes. The results indicated that the Kozako2 stem taper model offered the best fit for the four tropical species in most statistics. The Kozako2 model also consistently provided the best performance in the lack-of-fit statistics with the best SEE, \(\bar E\) and AMD in most of the relative height classes. These stem taper equations could help forest managers and researchers better estimate the diameter of the outside bark with any given height, merchantable stem volumes and total stem volumes of standing trees belonging to the four species of the tropical forest in MMFR.