Draft genomes of Perkinsus olseni and Perkinsus chesapeaki reveal polyploidy and regional differences in heterozygosity.

Perkinsus spp. parasites have significant impact on aquaculture and wild mollusc populations. We sequenced the genomes of five monoclonal isolates of Perkinsus olseni and one Perkinsus chesapeaki from international sources. Sequence analysis revealed similar levels of repetitive sequence within species, a polyploid genome structure, and substantially higher heterozygosity in Oceanian-sourced isolates. We also identified tandem replication of the rRNA transcriptional unit, with high strain variation. Characterized gene content was broadly similar amongst all Perkinsus spp. but P. olseni Oceanian isolates contained an elevated number of genes compared to other P. olseni isolates and cox3 could not be identified in any Perkinsus spp. sequence. Phylogenetics and average nucleotide identity scans were consistent with all P. olseni isolates being within one species. These are the first genome sequences generated for both P. olseni and P. chesapeaki and will allow future advances in diagnostic design and population genomics of these important aquatic parasites.

Dietary tuna hydrolysate modulates growth performance, immune response, intestinal morphology and resistance to Streptococcus iniae in juvenile barramundi, Lates calcarifer.

This study investigated the effects of tuna hydrolysate (TH) inclusion in fishmeal (FM) based diets on the growth performance, innate immune response, intestinal health and resistance to Streptococcus iniae infection in juvenile barramundi, Lates calcarifer. Five isonitrogenous and isoenergetic experimental diets were prepared with TH, replacing FM at levels of 0% (control) 5%, 10%, 15% and 20%, and fed fish to apparent satiation three times daily for 8 weeks. The results showed that fish fed diets containing 5% and 10% TH had significantly higher final body weight and specific growth rate than the control. A significant reduction in blood glucose was found in fish fed 10%, 15% and 20% TH compared to those in the control whereas none of the other measured blood and serum indices were influenced by TH inclusion. Histological observation revealed a significant enhancement in goblet cell numbers in distal intestine of fish fed 5 to 10% TH in the diet. Moreover, fish fed 10% TH exhibited the highest resistance against Streptococcus iniae infection during a bacterial challenge trial. These findings therefore demonstrate that the replacement of 5 to 10% FM with TH improves growth, immune response, intestinal health and disease resistance in juvenile barramundi.

Use of propofol as an anesthetic and its efficacy on some hematological values of ornamental fish Carassius auratus.

The aim of this study was to determine the level of anesthesia attained in Carassius auratus using a propofol bath administration and using values of haematological profile of blood and examinations, to assess the effects of the fish exposure to that anaesthetic. Acute toxicity values of propofol for gold fish were found 96 h LC50 6.353 mg/L, 96 h LC1 2.966 mg/L and 96 h LC99 13.609 mg/L. Time to induce anesthesia in propofol experiment was significantly higher than Clove oil (p < 0.05), but there was no significant difference in recovery time between the experiments. No significant decrease was found in Total RBC, WBC, HCT, MCH, MCV and leukogram indices (p > 0.05). MCHC (%) level of propofol experiment (13.93 ± 1.36) showed significant (p < 0.05) decrease than Clove oil anesthesia (94.95 ± 24.50) and control (62.46 ± 21.90). Hb(g/dl) content (5.20 ± 0.73) showed decrease in propofol exposure compared with control (15.41 ± 4.76) and clove oil experiment (25.39 ± 5.73) (p < 0.05).