Departure behaviour of juvenile southern bluefin tuna (Thunnus maccoyii) from southern Western Australia temperate waters in relation to the Leeuwin Current

The arrival of the warm tropical Leeuwin Current (LC) into southern Western Australia (SWA) may influence the movement timing and foraging habitat of juvenile southern bluefin tuna (SBT). Seasonal and interannual changes in the strength of the LC lead to thermal differences and potential changes in food availability between tropical and temperate waters in SWA. This phenomenon could influence the habitat utilization of SBT in these summer grounds. Movement characteristics determined from SBT tagged with acoustic transmitters (N = 244) using cross‐shelf lines of automated receivers for three summer‐autumn seasons (2004/2005, 2005/2006, 2006/2007) in SWA revealed interannual variability. Each year, the eastward movements of tagged fish increased as temperatures increased, and fish left the region when temperatures exceeded 20.0°C, a temperature indicative of the leading edge of the LC in SWA waters. Interannual fluctuations in the timing of movements were detected. When the LC was narrow and restricted to the shelf edge in 2004/2005, the distribution of SBT in shelf waters did not change before or after LC intrusion. In contrast, long distance eastward movements frequently occurred when the LC intrusion was spread wide over the continental shelf in 2005/2006 and 2006/2007. This suggests that, off SWA, juvenile SBT move quickly out of local foraging habitats defined by cool sub‐tropical temperate waters ahead of the tropical LC intrusion, despite these waters not being physiologically limiting. These results suggest that the behavioural response of SBT may be related to changes in prey availability as a result of changes in oceanographic conditions.     

1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging by protein hydrolyzates from tuna cooking juice

ABSTRACT: Protease XXIII, from Aspergillus oryzae , was used to hydrolyze tuna cooking juice at 37°C for up to 6 h. The hydrolyzate obtained at the degree of hydrolysis of 25.68% (after hydrolysis for 2.5 h) displayed the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging effect, reaching 82.19%. Six major fractions (A, B, C, D, E, and F) of this hydrolyzate were obtained by Sephadex G-25 column chromatography using a 0.05 M phosphate buffer (pH 6.5) as the mobile phase. All six fractions displayed a scavenging effect for the DPPH radical, but the scavenging effect was only obvious in two fractions (B and C). After the solid content of hydrolyzates was concentrated from one to five times, the scavenging effect of the DPPH radical increased from 17% to 75% for fraction B, and from 13% to 66% for fraction C. Seven anti-oxidative peptides were isolated from the hydrolyzates (mixture of B and C fractions) by reversed-phase HPLC. The peptide sequences comprised four to eight amino acid residues, including Val, Ser, Pro, His, Ala, Asp, Lys, Glu, Gly, or Tyr.     

Post-Death Cloning of Endangered Jeju Black Cattle (Korean Native Cattle): Fertility and Serum Chemistry in a Cloned Bull and Cow and Their Offspring

To preserve Jeju black cattle (JBC; endangered native Korean cattle), a pair of cattle, namely a post-death cloned JBC bull and cow, were produced by somatic cell nuclear transfer (SCNT) in a previous study. In the present study, we examined the in vitro fertilization and reproductive potentials of these post-death cloned animals. Sperm motility, in vitro fertilization and developmental capacity were examined in a post-death cloned bull (Heuk Oll Dolee) and an extinct nuclear donor bull (BK94-13). We assessed reproductive ability in another post-death cloned cow (Heuk Woo Sunee) using cloned sperm for artificial insemination (AI). There were no differences in sperm motility or developmental potential of in vitro fertilized embryos between the post-death cloned bull and its extinct nuclear donor bull; however, the embryo development ratio was slightly higher in the cloned sperm group than in the nuclear donor sperm group. After one attempt at AI, the post-death cloned JBC cow became pregnant, and gestation proceeded normally until day 287. From this post-death cloned sire and dam, a JBC male calf (Heuk Woo Dolee) was delivered naturally (weight, 25 kg). The genetic paternity/maternity of the cloned JBC bull and cow with regard to their offspring was confirmed using International Society for Animal Genetics standard microsatellite markers. Presently, Heuk Woo Dolee is 5 months of age and growing normally. In addition, there were no significant differences in blood chemistry among the post-death cloned JBC bull, the cow, their offspring and cattle bred by AI. This is the first report showing that a pair of cattle, namely, a post-death cloned JBC bull and cow, had normal fertility. Therefore, SCNT can be used effectively to increase the population of endangered JBC.