Studies On The Variations Of Immune Effectors Involved In The Abalone, Haliotis Diversicolor Supertexta, Under Different Conditions

The roles and variation of cellular and humoral effectors involved in immune defense system of the abalone, Haliotis diversicolor supertexta, in duration of anti-infectious immune response against to Vibrio parahaemolyticus or exposed to hypoxic and starvation stress were studied in this paper, in addition, the variation in immune defense effecors and biochemical genetics among wild and cultivated populations were investigated either. The results showed that phagocytes involved in haemocytes and some humoral immune effectors of the analone acted the most important roles in immune response against toⅤ. parahaemolyticus infection, and reactive oxygen intermediates (ROIs) and reactive nitrogen intermediates (RNIs) produced by respiratory burst which occurred concurrently with phagocytosis employed the major effectors among bactericidal agents in phagocytes, and the bactericidal effects of ROIs highly enhanced by the way of intracellular myeloperoxidase (MPO) catalyzed the transformation of hydrogen peroxide (H2O2) to some subordinated reactive oxygen metabolites such as hypochlorous acid (HOCl) and chloramines (RNCl), while the intracellular acid phosphatase (ACP) acted in digestion and biodegradation for engulfed foreign microorganisms, and catalase (CAT) served as antioxidant in quenching and clearance to oxyradicals. All are they the main anti-infectious immune effectors in immunocytes. Furthermore, some effectors in haemolymph of the abaone such as agglutinin, lysozyme, and phenol oxidase were all took parts in the immune response against toⅤ. parahaemolyticus infection either. Agglutinin in haemolymph performed functions in recognition for foreign material, opsonization, inhibition and haemolysis. Lysozyme took effect in bacteriolysis for gram-positive bacteria, and phenol oxidase may contribute to bacteriostasis and foreign material recognition. There was a pathway of potentiation immune effection through haemocytes proliferation which had been found in H. diveersicolor supertexta in duration of infection with V. parahaemolyticus. In haemolymph of the abalones some kinds of substance similar to immunoglobulin, complement and C reaction protein had been found and been named IgG-like, IgA-like, IgM-like, C3-like, C4-like and CRP-like respectively. All of them had some dependencies in anti-infectious immune response against to V. parahaemolyticus certainly.The abalones of H.diversicolor supertexta with an average body weight 14.25g±2.21g can tolerate 120 hours exposure to a hypoxic condition while dissolved oxygen reduction from 7.49±0.14 mg·L-1 to 2.53±0.16 mg·L-1 without onset mortality occured at a water temperature 22.1℃±1.3℃, and a salinity level of 30.72±0.54%o, and pH 8.20±0.14, but they suffered 91.11±7.70% cumulative mortality rate which was 80% more than of the control animals duo to challenged withⅤ. parahaemolyticus at a dose of 5.0x105 cells-abalone-1, and a clearance efficiency in the haemolymph of H.diversicolor supertexta decreased to-(3340.47±298.57)% inhibition rate. Obviously, the resistance of the abalones against toⅤ. parahaemolyticus infection decreaced and the susceptivity inceassed correspondingly at the hypoxic stress above, in which the total haemocytes counts (THC) and percentage of phagocytosis and the amount of superoxide anion (O2-) produced by respiratory burst decreased at 30.62±4.87%,62.77±5.79%,22.21±5.89% respectively. What intracellular MPO activity and CAT activity went up from 9.63±7.59% to 22.90±13.73% and 7.68±6.83% to 56.28±13.96% respectively while dissolved oxygen reduction from 7.49±0.14 mg·L-1 to 2.53±0.16 mg-L"1 suggests that the intracellular oxidation introduced by hypoxic stress response intensified and there must be much more oxyradical. The trial abalones of H. diversicolor supertexta possessed a cumulative mortality rate of 37.78±3.85% and a haemolymph inhibition rate of -(883.56±123.22)%, and the maximal downtrends of 12.51±6.59%, 21.90±15.84%,12.93±5.74% in THC and percentage of phagocytosis and the amount of O2-production respectively, and a variation of MPO activity range from -(10.61±4.20)% to 7.13±6.45% and CAT activity from -(5.17±18.08)% to 16.26±10.85% while dissolved oxygen went down from 7.49±0.14 mg·L-1 to 4.51±0.12 mg·L-1 due to infection with V. parahaemolyticus.The abalones of H.diversicolor supertexta with an average body weight 14.25g±2.21g can survive in a period of 20 days starvation at 24.3℃±1.7℃water temperature, 30.42±1.63%o salinity level and pH 8.15±0.11. The concentration of haemolymph protein in the abalones increased slightly in 5 days exposure time to starvation and dropped progressively with a wide range from 7d. Based on this, it will be surmised that there was hardly any humoral protein consumed for living energy in early starvation and mass humoral protein consumed for life support from 7d to starvation. The abalones survived with decreases in phagocytosis activity of haemocytes and respiratory burst and haemolymph lysozyme activity and haemolymph agglutination titers and anti-infectious immunity in duration of starvation, however, rather than did not greatly alter, some immune parameters such as the haemolymph clearance efficiency and phagocytosis activity of haemocytes and respiratory burst and haemolymph lysozyme activity sometimes went up somewhat in 5 days early starvation. Consequently, it would be suggested that the abalones were born with functions of starvation stress adaptation. In early duration of starvation the abalones did protect themselves and adaptate to surroundings by improving immune effection owing to subnutrition, and this biophilia styles of stress adaptation and natural ability maintaining changed or degenerated from 7d to starvation resulted from serious poor nutritional state and overmuch intravital resources degradation. Perhaps the haemolymph lysozyme activity and agglutinating titers decreased resulting from reduction of haemolymph protein, while the intracellular granules reduction may result in the haemolymph lysozyme activity and agglutinating titers dropped down directly.Comparion of wild population with a body length ranged from 67.7mm to 76.7mm and cultivated population of the abalone, Haliotis diversicolor supertexta, in cellular and humoral immune effectors showed that there were clear differences both in activities of immune defense effectors and immune defense function either between wild population and cultivated population or between purification and rejuvenation cultivated population which gained a body length ranged from 51.8mm to 59.2mm in 10 months of cultivation and degenerate cultivated population which only gained a body length ranged from 37.4mm to 43.1mm in 20 months of cultivations. Comparing with degenerate population, activities of both cellular and humoral immune effectors in purification and rejuvenation cultivated abalone population of H. diversicolor supertexta were obviously higher. While, comparing with wild population, only activities of cellular immune effectors in the purification and rejuvenation cultivated abalone population were somewhat higher, but the activities of humoral immune effectors were obviously lower. The amount of reactive oxygen intermediates (ROIs) produced by respiratory burst which occurred concurrently with phagocytosis were much in relation to the physical states of the abalones themselves and the environmental temperatures and the quantities of the stimulants. Activity of both cellular and humoral immune effectors had a significant decrease as the environmental temperature dropped down from 25℃to 18℃, while the antibacterial activities of the degenerative abalone population only had a little difference under two kinds of surrounding temperatures. There was some phenol oxidase in the hemolymph of the abalones, but their activities were low and had no marked activity difference within three above different populations.Conducted an investigation into genetic variation and diversity of wild and cultivated abalone populations of Haliotis diversicolor supertexta from Shenzhen and wild population from Nanao and cultivated population from Guangdong Jieshi altogether 4 populations in 8 enzyme systems presumably encoded by 17 allozyme loci using the assay of vertical slab polyacrylamide gel electrophoresis, it was found that six loci(Sod-1、Aat、Me、Mdh-1、Est-1、Est-2) presented polymorphic (P0.95) in the four populations above, and the percentage of polymorphic loci (P) was 37.5%; the observed heterozygosity (Ho) in both of wild populations were 0.1604, and the cultivated populations were 0.1521(GDSZ C.) and 0.15629(SZ C.) respectively; the expected heterozygosity (He) in wild populations were 0.1697 (SZ W.) and 0.1766 (NA W.) respectively, the cultivated populations were 0.1534 (GDSZ C.) and 0.1557(SZ C.) respectively; mean effective number of alleles per locus (Ae) in wild populations were 1.3633 (SZ W.) and 1.3943 (NA W.) respectively, while the cultivated populations were 1.3072 (GDSZ C.) and 1.3120 (SZ C.) respectively. The genetic distance between the two wild populations above was 0.0052, while the genetic distance between the cultivated populations was 0.0131, and the average of the four populations were 0.011. All of these results showed that there were a loss of genetic variation in cultivated populations of H. diversicolor supertexta, low level of differentiation was found between wild and cultivated populations (Fst=0.0411, Nw=5.8340).