Neurotoxins in a toxic red tide of Heterosigma akashiwo (Raphidophyceae) in Kagoshima Bay, Japan

In April 1995, an unusual large-scale red tide of Heterosigma akashiwo (Hada) Hada occurred, causing massive fish kills in Kagoshima Bay, Japan. Four neurotoxic components, HaTx-i , HaTx-ii a, HaTx-ii b and HaTx-iii , which corresponded to brevetoxin components. PbTx-2. PbTx-9, PbTx-3 and oxidized PbTx-2, were inferred from analysis of Heterosigma red tide toxins on TLC and HPLC.     

Protein markers of Marteilia sydneyi infection in Sydney rock oysters, Saccostrea glomerata

Marteilia sydneyi is the causative agent of QX disease in Sydney rock oyster, Saccostrea glomerata . It is responsible for disease outbreaks among oysters that occur during summer and can result in up to 95% mortality. QX disease has significantly decreased S. glomerata production in some areas of Australia's eastern seaboard over the past 30 years. Marteilia sydneyi sporulates in the digestive gland of oysters leading to complete disorganization of the infected tissues. The current study used proteomics to identify potential molecular markers of sporulating M. sydneyi infection during a field trial undertaken in the Georges River, Sydney, between December 2006 and May 2007. Early stages of M. sydneyi infection were detected by polymerase chain reaction, whilst cytological examination was used to identify sporulating M. sydneyi in the gut. Protein expression in oyster haemolymph was assessed during the M. sydneyi infection period by two dimensional electrophoresis. Proteome maps identified significant differences in the expression of four proteins in oysters with sporulating M. sydneyi infections.     

Vaccination of rainbow trout, Oncorhynchus mykiss (Walbaum), with recombinant and DNA vaccines produced to Flavobacterium psychrophilum heat shock proteins 60 and 70

Flavobacterium psychrophilum heat shock proteins (Hsp) 60 and 70 are highly immunogenic and were therefore investigated as potential vaccine candidates. Recombinant Hsps were purified from Escherichia coli and rainbow trout ( Oncorhynchus mykiss ) were intraperitoneally injected with phosphate buffered saline/Freunds complete adjuvant (FCA), 8 μg of rHsp60/FCA, rHsp70/FCA or a combination of 4 μg each of rHsp60 and rHsp70/FCA. Antibody responses against recombinant Hsp60 and Hsp70 8 weeks post-immunization were observed, but only fish immunized with rHsp70 exhibited highly elevated antibody levels against F. psychrophilum whole cell lysate. Some cross reactivity occurred, which may have been due to the V5 tag common to both proteins. Protection against F. psychrophilum challenge was not observed in any treatments at 8 weeks post-immunization. To further investigate any protective effect of these proteins, hsps were polymerase chain reaction amplified and cloned into pVAX1. Rainbow trout were intramuscularly injected with 8 μg of pVAX1hsp60, pVAX1hsp70 or a combination of 4 μg each of pVAX1hsp60 and pVAX1hsp70. Antibody responses at 4 weeks post-immunization were low and protection was not observed following challenge at 6 or 10 weeks post-immunization. Although Hsps of F. psychrophilum have been shown to be immunodominant, these antigens do not appear to be good vaccine candidates when delivered alone or in combination.     

Distribution and abundance of overwintering Calanus finmarchicus in the Faroe–Shetland Channel

The distribution and abundance of overwintering Calanus finmarchicus in the Faroe–Shetland Channel was studied during December 1994 and January 1995. Maximum abundance of animals in the Channel was approximately 50 000 m⁻², with a peak concentration of 627 m⁻³ at a depth of 930 m. Copepodite stages IV and V accounted for > 98% of the population. A clear association was found between the horizontal and vertical distribution of animals and the Arctic water masses in the bottom of the Faroe–Shetland Channel. The Wyville–Thomson Ridge formed a barrier to the southern distribution of Arctic waters and the abundance of overwintering C. finmarchicus was 25 times lower to the south of the Ridge than to the north. Spatial variability in lipid content and composition indicated that overwintering C. finmarchicus in the southern Norwegian Sea were in poorer condition with respect to wax ester content, and in a more advanced state of emergence from overwintering, than the animals within the Channel. The overwintering stock in the Channel probably originated from the Norwegian Sea or from north of the Faroe Islands. The Faroe–Shetland Channel is an important source of animals advected into the northern North Sea in the spring (March/April). The population abundance in the Faroe–Shetland Channel was estimated to be 4.5 × 10¹⁴ individuals, which is more than adequate to account for the mean concentration of adult stages observed in the northern North Sea in April.     

Inhibitory effects of a monoclonal antibody (MAb-001) on in vitro oxygen consumption and multiplication of the pathogenic haemoflagellate, Cryptobia salmositica Katz

A monoclonal antibody (MAb-001), against a surface glycoprotein on Cryptobia salmositica inhibited the multiplication and oxygen consumption of both virulent and avirulent strains of the parasite. The classical cysteine proteinase inhibitor (E-64) and a cysteine proteinase activator (EDTA) affected the in vitro multiplication of C. salmositica . Concentrations of E-64 higher than 10 μ M reduced the multiplication of C. salmositica while 5 m M of EDTA enhanced its multiplication. We propose that the cysteine proteinase is an important metabolic enzyme in C. salmositica and that binding of MAb-001 to the enzyme inhibited parasite multiplication and reduced oxygen consumption.     

Comparison of dietary essential amino acid requirements determined from group‐housed versus individually‐housed juvenile bluegill,Lepomis macrochirus

Two 60‐day experiments were conducted sequentially to determine (i) lysine requirement of juvenile bluegill, Lepomis macrochirus based on the dose–response method, (ii) requirements for other essential amino acids (EAAs) using whole‐body amino acid profile and (iii) whether differences in growth rates of group‐housed versus individually‐housed bluegills lead to different lysine requirement levels because of the presence and absence, respectively, of social hierarchies. Seven, semi‐purified, experimental diets (isonitrogenous, isocaloric) were prepared to contain graded levels of digestible lysine (10–31 g kg⁻¹). Experiment‐1 involved group‐housed bluegills (approximately 27 g, n = 10 fish/chamber, 4 chambers/diet) whereas experiment‐2 involved individually‐housed bluegills (approximately 30 g, n = 1 fish/chamber, 14 chambers/diet). Fish were fed twice daily to apparent satiation. Bluegill growth responses in both experiments generally improved (P < 0.05, anova ) with increasing dietary lysine levels from 10 to 16 g kg⁻¹, and then levelled off with further increase in lysine level (P > 0.05). Optimal dietary lysine level (digestible basis) was estimated to be 15 g kg⁻¹ based on broken‐line regression analyses of relative growth rate and feed conversion ratio with no differences being observed between the two rearing methods. Determined dietary requirement levels for other EAAs ranged from 2.4 g kg⁻¹ (tryptophan) to 15.3 g kg⁻¹ (leucine).     

Superoxide dismutase and catalase activities in Photobacterium damselae ssp. piscicida

The ability of a set of Photobacterium damselae ssp. piscicida strains isolated from different fish species to produce different superoxide dismutase (SOD) and catalase enzymes was determined. Unlike other bacterial pathogens, P. damselae ssp. piscicida is not able to produce different isoforms of SOD or catalase containing different metal cofactors when cultured under oxidative stress induced by hydrogen peroxide or methyl viologen, or under iron depleted conditions. However, iron content of the growth medium influenced the levels of SOD and catalase activity in cells, these levels decreasing with iron availability of the medium. Comparison of virulent and non-virulent strains of P. damselae ssp. piscicida showed similar contents of SOD, but higher levels of catalase were detected in cells of the virulent strain. Incubation of bacteria with sole, Solea senegalensis (Kaup), phagocytes has shown that survival rates range from 19% to 62%, these rates being higher for the virulent strain. The increased levels of catalase activity detected in the virulent strain indicates a possible role for this enzyme in bacterial survival.     

An evaluation of potential diets for the culture of postpueruli spiny lobsters Panulirus argus (Palinuridae)

Provision of a suitable feed is paramount for the ongoing success of spiny lobster culture. This study compared and evaluated the performance of seven diets for first instar juvenile spiny lobster Panulirus argus [5–6 mm carapace length (CL)] based on growth rates, survival, and feed conversion ratio. Results demonstrated that a seafood-based juvenile formulation produced the fastest growth rate (3.49% weight gain day⁻¹ and 0.90% CL increase day⁻¹ over a 28-day period). These growth rates were also reflected by a low feed conversion rate (3.04) for this formulated feed. Similar results were also obtained for juveniles fed a frozen seafood diet, however, frozen brine shrimp, Artemia salina (both enriched and un-enriched), frozen enriched mysis shrimp, a dry pellet, and a meal-based juvenile formulation did not produce consistent growth rates. Survival rates ranged between 38% and 85% and demonstrate that juvenile lobsters have better likelihoods of survival in captive culture environments compared to the wild. Although further nutritional refinement is recommended, the results from this research have significant implication for the possible expansion of juvenile spiny lobster growout to a larger scale.