Identification of an additional two-cysteine containing type I interferon in rainbow trout Oncorhynchus mykiss provides evidence of a major gene duplication event within this gene family in teleosts

Multiple type I interferons (IFNs) have recently been identified in salmonids, containing two or four conserved cysteines. In this work, a novel two-cysteine containing (2C) IFN gene was identified in rainbow trout. This novel trout IFN gene (termed IFN5) formed a phylogenetic group that is distinct from the other three salmonid IFN groups sequenced to date and had a close evolutionary relationship with IFNs from advanced fish species. Our data demonstrate that two subgroups are apparent within each of the 2C and 4C type I IFNs, an evolutionary outcome possibly due to two rounds of genome duplication events that have occurred within teleosts. We have examined gene expression of the trout 2C type I IFN in cultured cells following stimulation with lipopolysaccharide, phytohaemagglutinin, polyI:C or recombinant IFN, or after transfection with polyI:C. The kinetics of gene expression was also studied after viral infection. Analysis of the regulatory elements in the IFN promoter region predicted several binding sites for key transcription factors that potentially play an important role in mediating IFN5 gene expression.

Mitochondrial molecular clocks and the origin of the major Otocephalan clades (Pisces : Teleostei): A new insight

The Otocephala, a clade including ostariophysan and clupeomorph telcosts, represents about a quarter of total fish species diversity, with about 1000 gencra and more than 7000 species. A series of recent papers have defended that the origin of this clade and of its major groups may be significantly older than the oldest fossils of each of these groups suggest. Some of these recent papers explicitly defend a Pangean origin for some otocephalan groups Such as the Siluriformes or Cypriniformes. To know whether or not the otocephalans as a whole, and particularly the mainly freshwater, cosmopolitan otophysans could have originated before the splitting of the Pangean Supercontinent is of extreme importance, since otophysan fishes are among the most useful animal groups for the determination of historical continental relationships. In the present work we examined divergence times for each major otocephalan group by an analysis of complete mtDNA sequences, in order to investigate if these divergence times support the hypotheses advanced in recent studies. The complete mtDNA sequences of nine representative non-otocephalan fish species and of twenty-one representative otocephalan species was compared. The present study is thus, among the studies dealing with molecular divergence times of telcosts, the one in which a greater number of otocephalan species are included. The divergence times obtained support that the major otocephalan groups had a much older origin than the oldest fossil records available for these groups suggest. The origin of the Otocephala is estimated as having occurred about 282 Mya, with the origin of the Otophysi being estimated at about 251 Mya. (c) 2005 Elsevier B.V. All rights reserved.

Identification of immune genes in grass carp Ctenopharyngodon idella in response to infection of the parasitic copepod Sinergasilus major

The parasitic copepod Sinergasilus major is an important pathogen of grass carp Ctenopharyngodon idella. To understand the immune response of grass carp to the copepod infection, suppression subtractive hybridization method was employed to characterize genes up-regulation during the copepod infection in liver and gills of the fish. One hundred and twenty-two dot blot positive clones from infected subtracted library were sequenced. Searching available databases by using these nucleotide sequences revealed that 23 genes are immune-related, including known acute-phase reactants, and four novel genes encoding proteins such as source of immunodominant MHC-associated peptides (SIMP), TNF receptor-associated factor 2 binding protein (T2BP), poliovirus receptor-related protein 1 precursor, glycoprotein A repetitions predominant (GARP). The differential expression of seven immune genes, i.e. GARP, alpha-2-macroglobulin, MHC class I, C3, SIMP, T2BP, transferrin, as a result of infection was further confirmed by RT-PCR, with the up-regulation of alpha-2-macroglobulin, MHC class I, C3, SIMP and T2BP in the liver of infected fish, and down-regulation of SIMP in the gills of infected fish. The present study provides foundation for understanding grass carp immune response and candidate genes for further analysis.

Retroposon analysis of major cetacean lineages: The monophyly of toothed whales and the paraphyly of river dolphins

SINE (short interspersed element) insertion analysis elucidates contentious aspects in the phylogeny of toothed whales and dolphins (Odontoceti), especially river dolphins. Here, we characterize 25 informative SINEs inserted into unique genomic loci during evolution of odontocetes to construct a cladogram. and determine a total of 2.8 kb per taxon of the flanking sequences of these SINE loci to estimate divergence times among lineages. We demonstrate that: (i) Odontocetes are monophyletic; (ii) Ganges River dolphins, beaked whales, and ocean dolphins diverged (in this order) after sperm whales; (iii) three other river dolphin taxa, namely the Amazon, La Plata, and Yangtze river dolphins, form a monophyletic group with Yangtze River dolphins being the most basal; and (iv) the rapid radiation of extant cetacean lineages occurred some 28-33 million years B.P., in strong accord with the fossil record. The combination of SINE and flanking sequence analysis suggests a topology and set of divergence times for odontocete relationships, offering alternative explanations for several long-standing problems in cetacean evolution.

Effect of cryoprotectants on hatching rate of red seabream (Pagrus major) embryos

The objectives were to investigate the effect of cryoprotectants on the hatching rate of red seabream embryos. Heart-beat embryos were immersed in: five permeable cryoprotectants, dimethyl sulfoxide (DMSO), glycerol (Gly), methanol (MeOH), 1,2-propylene glycol (PG), and ethylene glycol (EG). in concentrations of 5-30% for 10, 30, or 60 min; and two non-permeable cryoprotectants: polyvinylpyrrolidone (PVP), and sucrose (in concentrations of 5-20% for 10 or 30 min). The embryos were then washed and incubated in filtered seawater until hatching occurred. The hatching rate of the embryos treated with permeable cryoprotectants decreased (P < 0.05) with increased concentration and duration of exposure. In addition, PG was the least toxic permeable cryoprotectant, followed by DMSO and EG, whereas Gly and MeOH were the most toxic. At a concentration of 15% and 30 min exposure, the hatching rate of the embryos immersed in PG was 93.3 +/- 7.0% (mean +/- S.D.), however. in DMSO. EG, Gly. and MeOH, it was 82.7 +/- 10.4, 22.0 +/- 5.7, 0.0 +/- 0.0, and 0.0 +/- 0.0%, respectively. Hatching rate of embryos treated with PVP decreased (P < 0.05) with the increase of concentration and exposure time, whereas for embryos treated with sucrose, there was no significant decrease in comparison with the control at the concentrations used. (C) 2008 Elsevier Inc. All rights reserved.