Haliotis Diversicolor Supertexta Research Articles

Behavior and effect of manufactured nanomaterials in the marine environment

Estuary and coastal environments are a ‘‘sink’’ for contaminants, including manufactured nanomaterials (MNMs) (Klaine et al. 2008). MNMs may enter the marine environment via rainwater, wastewater, and river transportation. Harbor handling may also result in MNM leakage and deposition in harbor areas. Dumping wastes such as nanowaste, trash containing MNMs, and harbor-dredging, mudcontaining MNMs into the sea, atmospheric sedimentation, and others may all cause MNMs to enter the marine environment. Compared to those in fresh water, MNMs in marine environments may demonstrate different environmental behavior and effects. MNMs in a marine environment are less stable and more easily sink out of the water column than those in a freshwater environment. Multiwalled C nanotubes (MWCNTs) can disperse into an aqueous suspension in natural surface freshwater and remain stable for as long as 1 month after stirring (Hyung et al. 2007). However, we have found that MWCNTs sink to the bottom rapidly in seawater. Fullerene (C60) forms a faint yellow aqueous suspension in various experimental waters after stirring or with the assistance of a cosolvent that can remain stable for several weeks or months. This C60 aqueous suspension quickly sinks in seawater with 20% salinity; the sedimentation rate reaches 29% after mixing for 1 h (Blickley and McClennan-Green 2008). We similarly added C60 to neutral seawater, which was then stirred continuously. Although C60 formed a faint yellow suspension, it remained stable for only 48 h (Zhu and Cai 2011). Nanoscale titanium dioxide particles (nTiO2), zinc oxide particles (nZnO), and cerium oxide particles (nCeO2) were relatively stable in freshwater, and more than 90% of these nanomaterials remained in the water body even after standing for 6 h at 200mg/L concentrations (Keller et al. 2010). However, in seawater, less than 30% of them remained after 6 h. Consequently, the benthic ecosystem in those areas receiving elevated water column levels of MNMs may be affected. MNMs are more apt to agglomerate in larger average particle diameters in seawater than in freshwater. For example, nTiO2 rapidly agglomerates in seawater, and the average particle diameter of the agglomeration significantly increases with increased nTiO2 concentration and sedimentation time. At 10mg/L nTiO2, the agglomeration particle diameter rapidly increases from below 500nm to 1000 nm within 30min. At higher nTiO2 concentrations, the diameter rapidly increases from below 1000 nm to above 2000 nm within 30min (Keller et al. 2010). However, after entering freshwater, the average particle diameter of nTiO2 agglomeration is only slightly higher than 300 nm, which is far lower than the value in seawater. The diameter does not significantly change with increased nTiO2 concentration and sedimentation time within 6 h (Keller et al. 2010). The electric potential, electrophoretic mobility, and solubility of nanomaterials differ in freshwater and seawater. The electric potential of nTiO2 in natural seawater fluctuated between 0.0282 and 0.0148mV, whereas nTiO2 appeared relatively stable in natural freshwater. The electric potential of 15.88mV was obviously lower than that in seawater (Zhu and Cai 2011). The electrophoretic mobility of nTiO2 ( 2.40mm/s/V) in natural freshwater was also lower than that in seawater ( 0.04mm/s/V) (Keller et al. 2010). Moreover, approximately 3.5mg/L Zn2þ was released from 80mg/ L nZnO dissolved in seawater (Miller et al. 2010). In contrast, over 15mg/L Zn2þ was released from 100mg/L nZnO dissolved in freshwater (Franklin et al. 2007). The reason for this difference is unknown. Studies on the toxic effects of MNMs in marine species are limited. Toxicity of MNMs has everything to do with the category, concentration, particle diameter, suspension preparation method, and solubility in seawater of MNMs. Compared with those in freshwater, the different properties of MNMs in seawater may cause different toxic effects and mechanisms. For example, the mechanism of action of nZnO in freshwater green algae may be mainly by the Zn2þ it releases (Franklin et al. 2007). However, because the Zn2þ released by nZnO in seawater is less bioavailable than in freshwater, the toxic effects of nZnO in marine algae may be the compound toxic effects of nanoparticles and metal ions (Miller et al. 2010). nAg is widely used as an antibacterial agent, but it fails to have a significant influence on the diversity of natural bacterial colonies in river mouth sediments (Bradford et al. 2009). nTiO2 at concentrations up to 500mg/L was not acutely toxicity to zebrafish embryos in freshwater, but 10mg/L nTiO2 significantly reduced embryo hatching and increased the malformation rate of the abalone Haliotis diversicolor supertexta in seawater (Zhu et al. 2011). The possible ecological effects of MNMs in the marine environment should not be ignored. Acknowledgment—This study was supported by the National Natural Science Foundation of China (21107058), the Doctoral Education Funding of the Education Ministry of China (20100002120019), the Natural Science Foundation of Guangdong Province of China (S2011010005391), and the Basic Research Project of the SZSITIC Commission of Shenzhen, China (JC201005270289A).

Influence of a Marine Diatom on the Embryonic Toxicity of 17α-Ethynylestradiol to the Abalone Haliotis diversicolor supertexta

The embryos of a marine abalone, Haliotis diversicolor supertexta, were exposed to a typical environmental estrogen, 17α-ethynylestradiol (EE2), for 96 h, to examine the acute toxicity of EE2 to the embryogenesis of the abalone. A marine diatom, Navicula incerta, was used in the test media as settlement substrate and food for the abalone larvae. During the embryo culture, more than 30 % of EE2 could be removed from the test media by the diatom, mainly via biodegradation, leading to a decrease of water-borne exposure dose. Further, the exposure concentrations of EE2 around the living microenvironment of the abalone larvae could be magnified 350–468 times after the larvae settled on the diatom, as indicated by the bioconcentration factors of EE2 in the diatom. Increased bioaccumulation of EE2 in the diatom caused greater inhibition on the metamorphosis of the abalone larvae by enhancing the uptake of EE2 in the larvae via dietary exposure, while declined water-borne exposure dose did not affect the embryonic toxicity of EE2 and its uptake in the abalone larvae. The 96-h median effective concentration of EE2 to the metamorphosis of the abalone larvae was 10.01 μg L−1, when the exposure doses in both the test media and the diatom were controlled stable. The 96-h hazard concentration for 5 % of the species was 1.20 μg L−1, which was still higher than but close to the reported upper contamination level of EE2 and could be employed as the safety threshold for the metamorphosis of the abalone embryos.

Development of a polymerase chain reaction for the detection of abalone herpesvirus infection based on the DNA polymerase gene

A 5781-base pair (bp) fragment of genomic DNA from the Taiwanese abalone herpesvirus was obtained and showed 99% (5767/5779) homology in the nucleotide sequence and 99% (1923/1926) in the amino acid sequence with the DNA polymerase gene of the abalone herpesvirus strain Victoria/AUS/2007. Homology of the amino acid sequence with the DNA polymerase of ostreid herpesvirus 1 was 30% (563/1856). In this study, a PCR-based procedure for detecting herpesvirus infection of abalone, Haliotis diversicolor supertexta, in Taiwan was developed. The method employed primer sets targeting the viral DNA polymerase gene, and was able to amplify DNA fragments of the expected size from infected samples. Primer sets of 40f and 146r were designed for amplification of an expected PCR product of 606 bp. Combining the new PCR protocol with histopathology, this assay can serve as a reliable diagnostic for herpesvirus infections in abalone.

Molecular and functional characterization of ferritin in abalone Haliotis diversicolor supertexta

Ferritin is an iron storage protein that plays a key role in the processes of physiology and pathology. In the present study, the authors reported the ferritin gene from abalone Haliotis diversicolor supertexta, which we named hds-ferritin. The full-length of hds-ferritin cDNA consisted of 879 bp with an ORF encoding a 171 amino acids. Amino acid sequence analysis revealed that hds-ferritin shared highly homology with other species. Real time PCR and western blot analysis showed that hds-ferritin was distributed ubiquitously in abalone tissues and had the highest expression level in digestive glands, but its transcripts are not modified remarkably by the stimulation with LPS. The recombinant protein was successfully expressed in Escherichia coli BL21 (DE3), and the titre of anti-ferritin antibody was about 1:14 000. The effects of ROS and RNS on ferritin were analyzed in the present study. The results showed that H2O2 played an important role in decreasing hds-ferritin, however NO cation appeared to have a protecting effect on H2O2-medied reduction of hds-ferritin.

Cloning, characterization, and expression analysis of a putative 17 beta-hydroxysteroid dehydrogenase 11 in the abalone, Haliotis diversicolor supertexta

The 17-beta-hydroxysteroid dehydrogenases (17β-HSDs) are key enzymes for sex steroid biosynthesis. To date, relatively little is known about the presence and function of 17β-HSDs in marine gastropods. In the present study, a cDNA sequence encoding putative 17β-HSD type 11 (17β-HSD-11) was identified in marine abalone (Haliotis diversicolor supertexta). The full-length cDNA contains 1058bp, including an open reading frame (ORF) of 900bp that encodes a protein of 299 amino acids. Comparative structural analysis revealed that abalone 17β-HSD-11 shares relatively high homology with other 17b-HSD-11 hormologues, and a lesser degree of amino acid identity with other forms of 17b-HSD, especially in the functional domains, including the cofactor binding domain (TGxxxGxG) and catalytic site (YxxSK). Phylogenetic analysis showed that abalone 17β-HSD-11 belongs to the short-chain dehydrogenase/reductase (SDR) family. Functional analysis following transient transfection of the ORF into human embryonic kidney-293 (HEK-293) cells indicated that abalone 17β-HSD-11 has the ability to convert 5α-androstane-3α,17β-diol (3α-diol) to androsterone (A) and testosterone (T) to androstenedione (4A). Expression analysis in vivo demonstrated that abalone 17β-HSD-11 is differentially expressed during three stages (non-reproductive, reproductive, and post-reproductive). Taken together, these results indicate that ab-17β-HSD-11 is an SDR family member with a potential role in steroid regulation during the reproductive stage.

Effect of hypoxia on the immune response of the abalone Haliotis diversicolor supertexta and its susceptibility to pathogenVibrio parahaemolyticus

The abalone Haliotis diversicolor supertexta is the most important aquatic species in many marine farms in China.For the purpose of qualitative observation on the variation of immune defense and natural resistance of animals,the abalones were put into waters with different dissolved oxygen and some immune effectors involved in defense were detected.In this paper the immune response of the abalone and susceptibility to pathogen Vibrio parahaemolyticus under hypoxia stress condition were described.The abalones with an average body weight(14.25±2.21) g could tolerate 120 hours for exposure to a hypoxic condition when dissolved oxygen was reduced from(7.49±0.14) mg/L to(2.53±0.16) mg/L without onset mortality occured at a water temperature(22.1 ±1.3) °C,and a salinity level of 30.72±0.54,and pH 8.20±0.14,but they suffered 91.11%±7.70% cumulative mortality rate which was 80% higher than the control animals due to being challenged with V.parahaemolyticus at a dose of 5.0×105 cells per abalone,and a clearance efficiency in the haemolymph of H.diversicolor supertexta decreased to-(3 340.47% ± 298.57)% inhibition rate.Obviously,the resistance of the abalones to V.parahaemolyticus infection decreaced and the susceptivity inceassed correspondingly under 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 by 30.62%±4.87%,62.77%±5.79%,and 22.21%±5.89% respectively.That 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 reduced from(7.49± 0.14) mg/L to(2.53±0.16) mg/L suggests that the intracellular oxidation introduced by hypoxic stress response intensified and there must be much more oxyradicals.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 ranges from(10.61%±4.20%) to 7.13%±6.45% and CAT activity from(5.17%±18.08%) to 16.26%±10.85% while not only dissolved oxygen went down from(7.49±0.14) mg/L to(4.51±0.12) mg/L but also infection with V.parahaemolyticus occurred due to the obvious hypoxic stress.

Influences of DMP on the Fertilization Process and Subsequent Embryogenesis of Abalone (Haliotis diversicolor supertexta) by Gametes Exposure

Di-methyl phthalate (DMP), a typical endocrine disrupting chemical (EDC), is ubiquitously distributed in aquatic environments; yet studies regarding its impact on gametes and the resulting effects on embryogenesis in marine gastropods are relatively scarce. In this study, the influences of DMP on the gametes and subsequent developmental process of abalone (Haliotis diversicolor supertexta, a representative marine benthic gastropod) were assessed. Newborn abalone eggs and sperm were exposed separately to different DMP concentrations (1, 10 or 100 ppb) for 60 min. At the end-point of exposure, the DMP-treated eggs and sperm were collected for analysis of their ultra-structures, ATPase activities and total lipid levels, and the fertilized gametes (embryos) were collected to monitor related reproductive parameters (fertilization rate, abnormal development rate and hatching success rate). Treatment with DMP did not significantly alter the structure or total lipid content of eggs at any of the doses tested. Hatching failures and morphological abnormalities were only observed with the highest dose of DMP (100 ppb). However, DMP exposure did suppress sperm ATPase activities and affect the morphological character of their mitochondria. DMP-treated sperm exhibited dose-dependent decreases in fertilization efficiency, morphogenesis and hatchability. Relatively obvious toxicological effects were observed when both sperm and eggs were exposed to DMP. Furthermore, RT-PCR results indicate that treatment of gametes with DMP changed the expression patterns of physiologically-regulated genes (cyp3a, 17β-HSD-11 and 17β-HSD-12) in subsequent embryogenesis. Taken together, this study proofed that pre-fertilization exposure of abalone eggs, sperm or both to DMP adversely affects the fertilization process and subsequent embryogenesis.

Generation and analysis of cDNA library from lipopolysaccharide-stimulated gastropod abalone (Haliotis diversicolor supertexta) hemocytes

A cDNA Library of lipopolysaccharide-stimulated gastropod abalone hemocytes was constructed using switching mechanism at 5' end of RNA transcript (SMART) approach. 300 random clones were selected and sequenced. 180 ESTs was gained. After assembling, we obtained 24 contigs and 119 singlets finally, some of which were immune- related genes. These immune-related genes include cytidine deaminase, ferritin, nonmuscle myosin essential light chain, cytochrome c oxidase subunit I, CD63 antigen-like protein and lysosomal-associated transmembrane protein. This study may contribute to the understanding of the immune mechanism of gastropod abalone Haliotis diversicolor supertexta . Key words: Haliotis diversicolor supertexta, cDNA Library, gene expression, immune mechanism.

English

A cDNA Library of lipopolysaccharide-stimulated gastropod abalone hemocytes was constructed using switching mechanism at 5' end of RNA transcript (SMART) approach. 300 random clones were selected and sequenced. 180 ESTs was gained. After assembling, we obtained 24 contigs and 119 singlets finally, some of which were immune- related genes. These immune-related genes include cytidine deaminase, ferritin, nonmuscle myosin essential light chain, cytochrome c oxidase subunit I, CD63 antigen-like protein and lysosomal-associated transmembrane protein. This study may contribute to the understanding of the immune mechanism of gastropod abalone Haliotis diversicolor supertexta.   Key words: Haliotis diversicolor supertexta, cDNA Library, gene expression,immune mechanism.

Identification and functional characterization of a putative 17β-hydroxysteroid dehydrogenase 12 in abalone (Haliotis diversicolor supertexta)

The 17β-hydroxysteroid dehydrogenases (17β-HSDs) are key enzymes in the downstream process of steroid hormone biosynthesis. To date, relatively little is known about the role of 17β-HSDs in marine gastropods. In the present study, a putative cDNA sequence encoding type 12 17β-HSD (17β-HSD-12) was identified in abalone (Haliotis diversicolor supertexta). The full-length cDNA was 1,978 bp, including an open reading frame (ORF) of 963 bp that encoded a protein of 321 amino acids. Comparative structural analysis revealed that abalone 17β-HSD-12 shared 39.8-42.8% amino acid identity with other 17β-HSD-12 homologues and that the functional domains were well conserved. Phylogenetic analysis revealed that abalone 17β-HSD-12 belonged to the short-chain dehydrogenases/reductases (SDRs) family. Functional analysis following transient transfection of the ORF in human embryonic kidney-293 (HEK-293) cells indicated that abalone 17β-HSD-12 had the ability to convert estrone (E1) into estradiol (E2). Expression analysis in vivo demonstrated that abalone 17β-HSD-12 was differentially expressed during the three reproductive stages (pre-spawning, spawning, and post-spawning). These results indicate that abalone 17β-HSD-12 is an SDR family member with a key role in steroidogenesis during the reproductive period.

Acute toxicity of nonylphenols and bisphenol A to the embryonic development of the abalone Haliotis diversicolor supertexta

Acute toxic effects and mechanisms of two typical endocrine disrupting chemicals, nonylphenols (NPs) and bisphenol A (BPA), to the embryonic development of the abalone Haliotis diversicolor supertexta, were investigated by the two-stage embryo toxicity test. The 12-h median effective concentrations (EC(50)) of NPs and BPA to the trochophore development were 1016.22 and 30.72 μg L(-1), respectively, and the respective 96-h EC(50) values based on the completion of metamorphosis (another experimental endpoint) were reduced to 11.65 and 1.02 μg L(-1). Longer exposure time and magnified exposure concentrations in the benthic diatom, that serves as both food source and settlement substrate during the metamorphosis, via bioaccumulation, led to the higher sensitivity of metamorphosis to target EDCs compared with the trochophore development. The hazard concentrations for 5% of the species (HC(5)) could be employed as the safety thresholds for the embryonic development of the abalone. The 12-h HC(5) values of NPs and BPA were 318.68 and 13.93 μg L(-1), respectively, and the respective 96-h HC(5) values were 0.99 and 0.18 μg L(-1), which were at environmentally relevant levels. Results of proteomic responses revealed that NPs and BPA altered various functional proteins in the abalone larvae with slight differences between each chemical and affected various physiological functions, such as energy and substance metabolism, cell signalling, formation of cytoskeleton and cilium, immune and stress responses at the same time, leading to the failure of metamorphosis.

Assessing abalone growth inhibition risk to cadmium and silver by linking toxicokinetics/toxicodynamics and subcellular partitioning

The purpose of this study was to link toxicokinetics/toxicodynamics and subcellular partitioning for assessing the susceptibility and the growth inhibition risks of abalone Haliotis diversicolor supertexta exposed to waterborne and foodborne cadmium (Cd) and silver (Ag). We reanalyzed published data on growth inhibition and subcellular partitioning associated with the present mechanistic model to explore the correlations among elimination (k (e)), detoxification (k (d)), and recovery (k (r)) rate constants and to assess the growth inhibition risk. We found a positive correlation among k (e), k (d), and k (r) in abalone exposed to Ag. We also employed a life-stage based probabilistic assessment model to estimate the growth inhibition risk of abalone to environmentally relevant Cd (5-995μgl(-1)) and Ag (0.05-9.95μgl(-1)) concentrations in Taiwan. The results showed that abalone had a minimum 20% probability of the growth inhibition risk exposed to Cd, whereas Ag exposure was not likely to pose the risk. The maximum biomasses were estimated to be 0.0039 and 0.0038, 61.61 and 43.87, and 98.88 and 62.97g for larvae, juveniles, and adults of abalone exposed to the same levels of Cd and Ag, respectively. Our study provides a useful tool to detect potential growth biomass of abalone populations subjected to Cd and Ag stresses and mechanistic implications for a long-term ecotoxicological risk assessment in realistic situations.

TiO2 Nanoparticles in the Marine Environment: Impact on the Toxicity of Tributyltin to Abalone (Haliotis diversicolor supertexta) Embryos

Little information is available on the potential ecotoxicity of manufactured nanomaterials (MNMs) in the marine environment. To carefully address this issue, the toxicity of nanosized titanium dioxide (nTiO(2)) aggregates in the marine environment was evaluated using abalone (Haliotis diversicolor supertexta) embryonic development as a model. The effect of nTiO(2) aggregates on the toxicity of the highly toxic marine antifouling compound tributyltin (TBT) to abalone embryos was also investigated. No developmental effects of nTiO(2) were observed at 2 mg/L but concentrations ≥10 mg/L caused hatching inhibition and malformations. The presence of 2 mg/L nTiO(2) increased the toxicity of TBT up to 20-fold compared with TBT alone. This enhancement of TBT may be due to the combined effects of TBT adsorption onto nTiO(2) aggregates and the internalization of nTiO(2) aggregates by abalone embryos. These observations indicate that MNMs may have important indirect impacts on aquatic organisms by varying the toxicity of coexisting pollutants. Thus, risk assessments for MNMs should consider both their direct effects and possible indirect effects of interactions with other environmental contaminants.

Passive immune-protection of small abalone against Vibrio alginolyticus infection by anti- Vibrio IgY-encapsulated feed

Small abalone ( Haliotis diversicolor supertexta) is a high value-added shellfish. It however has been suffering Vibrio alginolyticus infections, which cause mass death of small abalone and thus great economic losses, particularly in artificial aquaculture. In this study, we attempted to treat small abalone with anti- Vibrio IgY to elicit a passive immunity directly against V. alginolyticus infections. Anti- Vibrio IgY was alginate encapsulated in egg powders as feed, which may avoid antibody inactivation in the gastrointestinal tract of small abalone. The feed was tested for the stability of anti- Vibrio IgY in a gastrointestinal mimic environment. The result showed anti- Vibrio IgY retained activity as high as 90% after 4 h exposure to pancreatic enzymes. Addition of 0, 5 or 10% anti- Vibrio IgY-encapsulated egg powders into a basal diet to form abalone diet formulae. Small abalones fed with the anti- Vibrio IgY formulae showed a relatively high respiratory burst activity than those without anti- Vibrio IgY treatments. The survival rates of small abalones fed with 5 or 10% anti- Vibrio IgY egg powders were in the range of 65–70% 14 days post- V. alginolyticus challenge (1 × 10 6 c.f.u.), which was significantly higher than 0% of those fed without anti- Vibrio IgY. The anti- Vibrio IgY-encapsulated formulae were thus concluded to be an effective means to prevent small abalone from V. alginolyticus infection, and may be practical in use in abalone aquaculture.

Identification and expression localization of a Ran homologue in mollusc abalone, Haliotis diversicolor supertexta

Ran protein is a central molecular in several key nuclear functions, including nucleocytoplasmic transport, cell-cycle progression and nuclear envelope assembly. In this study, we have isolated and characterized a Ran homologue from a gastropod abalone which we named ab-Ran. The full-length cDNA consists of 1239 bp with an ORF encoding a 220 amino acid protein. The deduced amino acid sequence of ab-Ran shows highly similar to that of other Ran members (84–88%). Moreover, the ab-Ran contains five conserved regions and four carboxy-terminal residues CAAX-box. RT-PCR analysis showed that the ab-Ran was ubiquitously expressed in abalone tissues. The intracellular localization examined by immunofluorescence and immunohistochemistry staining displayed that ab-Ran was largely concentrated in the nuclei and partially in the cytoplasm. To the best of our knowledge, this is the first identification and characterization of a Ran homologue in mollusk.

The toxicity and oxidative stress of TiO2 nanoparticles in marine abalone (Haliotis diversicolor supertexta)

The increasing use of nanotechnology highlights the need to understand and clarify the environmental impacts of nanomaterials. In this study, the acute toxicity and oxidative stress of titanium dioxide nanoparticles (nTiO2) in mature marine abalone (Haliotis diversicolor supertexta) were assessed. No acute effect was found in any of the treatment groups with nTiO2 concentration gradients ranging from 0.1 to 10mg/L. However, the activity of an antioxidant enzyme superoxide dismutase (SOD) significantly increased in the group that was exposed to 1.0mg/L nTiO2. The content of a non-enzymatic antioxidant, glutathione (GSH), significantly decreased in the groups with an nTiO2 concentration ⩾1.0mg/L. The level of lipid peroxidation (LPO) was found to increase as the nTiO2 dose increased. Furthermore, NO was produced in excess in abalone. These results demonstrated that, although nTiO2 is not acutely toxic to abalone, it does exert oxidative stress on abalone.

Karyological Studies of the Hybrid Larvae ofHaliotis Disversicolor SupertextaFemale andHaliotis Discus DiscusMale

ABSTRACT To determine the genomic composition of the interspecific hybrid between Haliotis diversicolor supertexta ♀ and H. discus discus ♂ at an early developmental stage, veliger larvae produced from hybrid (SJ-5 and SJ-50) and pure species crosses (SS and JJ) were sampled and analyzed using standard karyological methods and genomic in situ hybridization. In hybrid metaphase spreads, chromosomes from both parents were detected, except one metaphase, which showed the H. diversicolor supertexta haploid karyotype. The genomic composition of the hybrid was also confirmed through preliminary genomic in situ hybridization results. Many more aneuploids and chromosome fragments were found in the hybrids than those in the control pure species crosses, indicating genome instability and chromosome loss in the hybrids. In the hybrid hypodiploid metaphase spreads, two intact sets of H. diversicolor supertexta chromosomes and several H. discus discus chromosomes were detected by pairing. Spontaneous diploidization of...

Diatom diet selectivity by early post-larval abalone Haliotis diversicolor supertexta under hatchery conditions

Benthic diatoms constitute the primary diet of abalone during their early stages of development. To evaluate the dietary preferences of early post-larval abalone, Haliotis diversicolor supertexta, we analyzed the gut contents of post-larvae that settled on diatom films. We compared the abundance and species diversity of diatom assemblages in the gut to those of the epiphytic diatom assemblages on the attachment films, and identified 40 benthic diatom species in the gut contents of post-larvae 12 to 24 d after settlement. The most abundant taxa in the gut contents were Navicula spp., Amphora copulate, and Amphora coffeaeformis. Navicula spp. accounted for 64.0% of the cell density. In the attachment films, we identified 110 diatom species belonging to 38 genera. Pennate diatoms were the dominant members including the species Amphiprora alata, Cocconeis placentula var. euglypta, Cylindrotheca closterium, Navicula sp. 2, and A. coffeaeformis. Nano-diatoms (<20 μm in length) accounted for a considerable proportion of the total species number and cell density of the diatom assemblages in the gut contents and on the films. This suggests that nano-diatoms are important to the efficient production of abalone seed. The difference of the composition and abundance of diatoms between in the guts and on the biofilms suggests that early post-larval grazing was selective. An early post-larval abalone preferred nano-diatoms and the genera Navicula and Amphora during the month after settlement.

The impacts of bisphenol A (BPA) on abalone ( Haliotis diversicolor supertexta) embryonic development

The effects of bisphenol A (BPA) on abalone ( Haliotis diversicolor supertexta) embryonic development were investigated by exposing the fertilized eggs to four different concentrations of BPA (0.05, 0.2, 2 and 10 μg mL −1). Toxicity endpoints including the embryo development parameters, the physiological features and the expression profile of several reference genes (prohormone convertase 1, PC1; cyclin B, CB; and cyclin-dependent kinase 1, CDK1) were assessed. The results showed that BPA could markedly reduce embryo hatchability, increase developmental malformation, and suppress the metamorphosis behavior of larvae. The possible toxicological mechanisms hidden behind of these effects (i.e. disturbing the embryogenesis) might result from three aspects: (1) BPA disturbance the cellular ionic homeostasis and osmoregulation of abalone embryos by changing the Na +–K +-ATPase and Ca 2+–Mg 2+-ATPase levels; (2) BPA induced oxidative damage of embryos by significantly alterating the peroxidase (POD) activities and the malondialdehyde (MDA) production; and (3) the RT-PCR analysis further demonstrated that BPA perturbed the cellular endocrine regulation and cell cycle progression by down-regulating the PC1 gene, as well as over-expressing the CB and CDK1 genes. This is the first comprehensive study on the developmental toxicity of BPA to the marine abalone at morphological, physiological and molecular levels. The results in this study also indicated that the embryo tests can contribute to the ecological risk assessment of the endocrine disruptors in marine environment.

Identification and functional characterization of an Rbx1 in an invertebrate Haliotis diversicolor supertexta

Rbx1 (RING box1) is an evolutionarily conserved RING-H2 finger protein and belongs to the RING-finger family of Ubiquitin ligase E3, which determines the substrate specificity of ubiquitination and regulates a variety of biological processes. We report here the identification and functional characterization of an Rbx1 homologue in abalone, which we named ab-Rbx1. Ab-Rbx1 contains conserved cysteine/histidine residues which are the characteristics of Rbx proteins. Phylogenetic tree analysis further demonstrated that ab-Rbx1 belongs to the Rbx1 family other than Rbx2 family. Real-time PCR analysis revealed that ab-Rbx1 was ubiquitously expressed in all examined tissues of abalone and the expression level of ab-Rbx1 was significantly induced by mitogenic situation. Immunohistochemical and immunofluorescent staining showed that the ab-Rbx1 was expressed predominantly in epithelial cells and localized both in the cytoplasmic and nuclear compartment. Ubiquitination assay demonstrated that ab-Rbx1 had ubiquitin ligase activity and could auto-ubiquitinated itself. These results suggest that ab-Rbx1 is an Rbx1 homologue and may be indirectly involved in the immune response of abalone through ubiquitination.