Immunotoxicity Effect of Benzo[α]Pyrene on Scallop Chlamys farreri

The toxic effects of benzo[α]pyrene (B[α]P) at different concentrations (0.1, 0.5, 1, 2.5 and 7.5 ugL-1) on scallop (Chla-mys farreri) immune system were studied. The results showed that B[a]P had significant toxic effects on the haemocyte counts, neu-tral red uptake, phagocytosis, bacteriolytic and antibacterial activity (P<0.05), while the seawater control and acetone control had no significant differences. The haemocyte counts, neutral red uptake, phagocytosis and bacteriolvtic activity in all B[α]P treatment groups as well as antibacterial activity, in groups of 0.5, 1, 2.5 and 7.5 ugL-1 B[α]P decreased significantly (P<0.05). Some of these indices tended to be stable on the sixth day and others on the ninth day, and the indices showed clear time- and concentra-tion-response to B[α]P. Bacteriolytic activity in 0.1ugL-1 B[α]P treatment group and antibacterial activity in 0.1 ugL-1 and 0.5 ugL-1 B[α]P treatment groups increased at the beginning of exposure and reached their peaks on day 1 and day 6, respectively. Following that, both activities decreased gradually and became stable after day 9. When all the indices reached stability, they were significantly lower than those in control group (P<0.05), except for antibacterial activity in 0.1 ugL-1 B[α]P treatment group (P<0.05). Thus, B[α]P has evident toxic effects on scallop immune system, which supports the view that a relationship exists between pollution and immu-nomodulation in aquatic organisms.     

Immunotoxicity effect of benzo[α]pyrene on scallop Chlamys farreri

The toxic effects of benzo[α]pyrene (B[α]P) at different concentrations (0.1, 0.5, 1, 2.5 and 7.5 μgL⁻¹) on scallop (Chlamy farreri) immune system were studied. The results showed that B[α]P had significant toxic effects on the haemocyte counts, neutral red uptake, phagocytosis, bacteriolytic and antibacterial activity (P<0.05), while the seawater control and acetone control had no significant differences. The haemocyte counts, neutral red uptake, phagocytosis and bacteriolytic activity in all B[α]P treatment groups as well as antibacterial activity in groups of 0.5, 1, 2.5 and 7.5 μgL⁻¹ B[α]P decreased significantly (P<0.05). Some of these indices tended to be stable on the sixth day and others on the ninth day, and the indices showed clear time- and concentration-response to B[α]P. Bacteriolytic activity in 0.1μgL⁻¹ B[α]P treatment group and antibacterial activity in 0.1 μgL⁻¹ and 0.5 μgL- B[α]P treatment groups increased at the beginning of exposure and reached their peaks on day 1 and day 6, respectively. Following that, both activities decreased gradually and became stable after day 9. When all the indices reached stability, they were significantly lower than those in control group (P<0.05), except for antibacterial activity in 0.1 μgL⁻¹ B[α]P treatment group (P>0.05). Thus, B[α] has evident toxic effects on scallop immune system, which supports the view that a relationship exists between pollution and immunomodulation in aquatic organisms.     

Effect of Fouling Organisms on Food Uptake and Nutrient Release of Scallop （Chlamys nobilis, Reeve） Cultured in Daya Bay

Biofouling is an important factor that affects the bivalve farming industry. Fouling organisms may reduce growth and survival rate of the cultured species. Fouler are often filter feeders, so they are potential competitors for food resource with the cultured species. The present study was conducted to measure the impact of fouling on food uptake and nutrient release in April and June, 2006 in Daya Bay near Guangzhou, China. Results showed that fouling organisms had significant effect on food uptake and nutrient release. The chlorophyll a uptake rate of fouled scallops was 7.53Lh-1±1.416Lh-1 and 11.94Lh-1±2.497Lh-1 in April and June, respectively, significantly higher than those of cleaned scallops, i.e., 4.23 Lh-1 ±2.744Lh-1 and 2.57Lh-1± 1.832 Lh-1 respectively.The consumption of total particulate matter by fouled scallops in April and June was 5.52Lh-1±0.818Lh-1 and 3.07Lh-1±0.971 Lh-1,respectively; the corresponding results for cleaned scallops are 2.49Lh-1 ±0.614Lh-1 and 2.37± 1.214Lh-1, respectively. Fouling increased ammonia release significantly. The ammonia release rate of fouled scallops was 33.81Lh-1±7.699Lh-1 and 76.39Lh-1 ±9.251Lh-1 in April and June, while cleaned scallops released 2.46Lh-1± 0.5 1 1Lh-1 and 7.23Lh-1± 1.026Lh-1 ammonia, respectively. Phosphate release of fouled scallops was 22.72Lh-1 ± 9.978 Lh-1 in June and cleaned scallops released phosphate 6.01Lh-1 ±0.876 Lh-1 in April. Therefore, fouling contributed much to food reduction and concentration increase of ammonia and phosphate in water.     

Characterization,Expression and Function Analysis of DAX1 Gene of Scallop （Chlamys farreri Jones and Preston 1904） During Its Gametogenesis

DAX 1,a member of nuclear receptor superfamily,has a function in the sex determination and gonadal differentiation of several vertebrate species.However,little information about DAX1 of invertebrates is available.Here we cloned a homolog of scallop （Chlamys farreri Jones and Preston 1904） dax1,Cf-dax1,and determined its expression characteristics at mRNA and protein levels.The cDNA sequence of Cf-dax1 was 2093 bp in length,including 1404 bp open reading frame （ORF） encoding 467 amino acids.Unlike those of vertebrates,no conserved LXXLL-related motif was found in the putative DNA binding region of Cf-DAX1.Fluorescence in situ hybridization showed that Cf-dax1 located on the short arm of a pair of subtelocentric chromosomes.Tissue distribution analysis using semi-quantitative RT-PCR revealed that Cf-dax1 expressed widely in adult scallop tissues,with the highest expression level found in adductor muscle,moderate level in mantle,gill and testis,and low level in kidney,ovary and hepatopancreas.The result of quantitative real-time PCR indicated that the expression of Cf-dax1 was significantly higher （P＜0.05） in testis than in ovary at the same stage,showing a sex-dimorphic expression pattern.Furthermore,immunohistochemical detection found that Cf-DAX1 mainly located in spermatogonia and spermatocytes of testis and in oogonia and oocytes of ovary,implying that DAX1 may involve in gametogenesis of bivalves.     

大亚湾华贵栉孔扇贝[Chlamys nobilis（Reeve）]繁殖和生长的初步观察

扇贝是我国的主要海水养殖品种之一。扇贝的闭壳肌干制品俗称“干贝”，是畅销的出口珍品，换汇率高。据国外最新研究报导，扇贝的医药价值更高，其韧带浸出物可治癌病，其卵巢对白血病有较高的疗效。