Cloning and Characterization of the Phytoene Desaturase(pds) Gene-a Key Enzyme for Carotenoids Synthesis in Dunaliella(Chlorophyta)

The unicellular green alga Dunaliella is outstanding for its ability of massive accumulation of carotenoids. To elucidate the carotenoids synthesis pathway in this alga,phytoene desaturase(pds) gene cDNA together with its DNA sequences were isolated and their structures and functions analyzed. The full-length pds cDNA of 2290 bp(GenBank Accession No. DQ243892) was de-duced from RACE results,including untranslated 21 bp 5'-and 520 bp 3'-flanking regions and an open reading frame of 582 amino acids,coding a protein of 64.196 kDa. The DNA sequence of 2908 bp(GenBank Accession No. DQ845248) including five introns was obtained. The fifth intron was uncompleted and complex,including two bases' perfect repeats(GT) 10 and large different-sized repeats within the last 400 bp. The Southern blot hybridization result demonstrated that this gene occurred as a single copy in this species,and the quantitative RT-PCR result showed that the transcription of this gene was constitutive. The evolutional significance of pds was discussed.

Effects of Ferrous Fumarate on Growth Performance,Blood Biochemical Parameters and Trace Elements of Oncorhynchus mykiss

[ Objective] The study aimed to discuss the effects of ferrous fumarate on growth performance, blood biochemical parameters and content of trace element of Oncorhynchus mykiss. [ Method ] Juvenile rainbow trout with an initial weight of （89.2 ±0.2） g were fed with the basal fodder supplemented with different levels of ferrous fumarate （0, 20, 40, 80,160 and 480 mg/kg iron） for 60 d, and the six groups were named DO, D20, D40, D80, D160 and D480, wherein DO was as the control group, actually containing 62.60, 79.50, 99.60, 139.30, 215.20 and 538.40 mg/kg iron respectively. [ Result] The growth performance of juvenile rainbow trout was not affected by different dietary iron levels obviously （ P 〉 0.05）. With the increase of dietary iron level, hemoglobin （Hb） content and number of red blood cells（RBC） rose firstly and then leveled off. No significance was found in hematocrit （Hct） among the six groups （P 〉0.05）. Iron content in the whole body, vertebrae and muscle increased significantly with the improvement of dietary iron level（ P 〈0.05）, and iron concentration in the liver increased firstly and then leveled off in groups from D40 to D480. No significant difference in zinc content of the whole body was found among the six groups （ P〉0.05）, while zinc content in the vertebrae and muscle in control group was significantly higher than that of other groups （ P〈0.05）, and zinc concentration in the liver in groups DO and 1320 was significantly higher than that of other groups （ P 〈0.05）. Copper content in the whole body increased significantly with the increase of dietary iron level （P 〈 0.05 ）, while no significant difference was observed in the vertebrae （ P 〉0.05）, and copper concentration in the muscle in control group was significantly lower than that of other groups （ P 〈0.05）. Serum lysozyme （LZM） activity of group DO was significantly lower than that of other groups （ P 〈 0.05） except for group D480 （ P 〉 0.05）. Catalase （CAT） activity of serum enhanced significantly （ P 〈 0.05） from DO to EH0 and then decreased obviously （P 〈0.05）. [ Conclusion] Based on hemoglobin and iron content in the liver, the broken-line model analysis showed that the dietary iron level provided by ferrous fumarate for juvenile rainbow trout was estimated to be 99.8 and 100.4 mg/kg respectively in the experiment.

Embryonic and larval development in barfin flounder Verasper moseri (Jordan and Gilbert)

Broodstock of Verasper moseri (Jordan and Gilbert) aged 3-4 years old were selected,and reinforced cultivation was conducted to promote maturation under controlled water temperature and photoperiod conditions.Fertilized eggs were obtained by artificial fertilization,and the development of embryos,larvae and juveniles was observed continuously.The results showed that the fertilized eggs of V.moseri were spherical,with transparent yolk and homogeneous bioplasm,and had no oil globule inside.The average diameter of the eggs was 1.77±0.02 mm.The eggs of V.moseri were buoyant in water with salinity above 35.The cleavage type was typical discoidal.Young pigment cells appeared when olfactory plates began to form.Hatching occurred at 187 h after fertilization at a water temperature of 8.5°C.The newly hatched larvae,floating on the water surface,were transparent with an average total length of 4.69±0.15 mm.During the cultivation period,when the water temperature was raised from 9 to 14.5°C,4-day old larvae showed more melanophores on the body surface,making the larvae gray in color.The pectoral fins began to develop,which enabled the larvae to swim horizontally and in a lively manner.On days 7-8,the digestive duct formed.The yolk sac was small and black.The yolk sac was absorbed on day 11.Larvae took food actively,and body length and body height clearly increased.The rudiments of dorsal and anal fin pterygiophores were discernible and caudal fin ray elements formed on day 19.On day 24,the larval notochord flexed upwards,and the rays of unpaired fins began to differentiate.Pigment cells converged on the dorsal and anal fin rays,and the mastoid teeth on the mandible appeared.On day 29,the left eyes of juveniles began to move upwards.Depigmentation began in some juveniles and they became sandy brown in color on day 37.Most juveniles began to settle on the bottom of the tank.The left eyes of juveniles migrated completely to the right side on day 50,when the average body length attained 2.5±0.18 cm,and juveniles accomplished metamorphosis to young.The embryonic and larval characters of several flounder species are compared.