The first record of Ophioleila elegans (Echinodermata:Ophiuroidea) from a deep-sea seamount in the Northwest Pacific Ocean

The rare ophiuroid species, Ophioleila elegans, was collected by the submersible Jiaolongfrom 1 660 m depth on the Caiwei Guyot located in the Magellan Seamount Chain in the Northwest Pacific Ocean. This is the first published record of this species since the types were described from similar habitat off Hawaii. We provide more detailed morphologic characteristics of arm skeleton and a phylogenetic analysis based on CO 1 sequences. Both morphology and phylogeny results suggest that the genus Ophioleila is more closely related to Ophiactids than Hemieuryalids.

Constructing Genetic Linkage Maps Using the Whole Genome Sequence of Pacific Bluefin Tuna (Thunnus orientalis) and a Comparison of Chromosome Structure among Teleost Species

Pacific bluefin tuna (Thunnus orientalis) is one of the most economically important species in the Percomorpha group of teleost fishes. Their migrations are extensive and depend upon continuous swimming at a high rate of speed throughout their life. The draft genome sequence of this species has been reported but remains highly fragmented. We constructed a Pacific bluefin tuna genetic linkage map using microsatellite markers developed on each of the scaffolds from the draft genome sequence to link these genome fragments and understand the genomic structure of species in Percomorpha. Of the 606 polymerase chain reaction microsatellite primer pairs tested, 473 were polymorphic in the mapping populations for the linkage analysis. We constructed sex-specific maps for 24 linkage groups consisting of 470 markers, which allowed us to place scaffolds that cumulatively represented 20.8% (153.8 Mb) of the sequenced genome onto the linkage groups. The distribution of orthologous genes on the chromosomes of tuna and four other teleost fish species suggested that the constitution of tuna chromosomes is closest to that of medaka. Both species have the 24 chromosomes of the ancestral teleost, including several chromosomal inversions. The integrated map developed in this study will be useful to construct a complete physical map to conduct comparative teleost genomics and genetic studies on economically useful traits in Pacific bluefin tuna.

Growth Rate Assessment of Alcyonacean Sarcophyton glaucum from Northern Hurghada, Red Sea, Egypt

Eighteen specimens of the soft coral Sarcophyton glaucum have been collected and tagged to determine the growth rate using the weight variations technique and to investigate the reproductive season histologically. Six colonies were totally weighed and 12 fragments (produced from three colonies) were marked and weighed. Some samples showed sever shrinkage that lead to death. The maximum semiannual growth rate was recorded in summer (30.05 gm/6 m). The average monthly growth reached 3.95 gm/month. Many factors affect the growth rate such as water currents, turbidity, sedimentation, temperature and reproduction process. The studied species is a dioecious species (unisex), where the Autozooid polyps are the reproductive organs while siphonozooids are sterile. Female gonads were observed to develop at late July before male gonads which began at late September. Larvae releasing started at late January and the gonads are completely spawned in February. Fertilization occurs internally to form planulae larvae which librated completely in February. The oogenesis exhibited prolonged about 23 months, which gave rise to oocytes of different developmental stages in female colonies at any given time, and a spermatogenic cycle of only 10 - 12 months.