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- Holland, Linda Z, et al.
(författare)
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The amphioxus genome illuminates vertebrate origins and cephalochordate biology
- 2008
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 18:7, s. 1100-1111
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Tidskriftsartikel (refereegranskat)abstract
- Cephalochordates, urochordates, and vertebrates evolved from a common ancestor over 520 million years ago. To improve our understanding of chordate evolution and the origin of vertebrates, we intensively searched for particular genes, gene families, and conserved noncoding elements in the sequenced genome of the cephalochordate Branchiostoma floridae, commonly called amphioxus or lancelets. Special attention was given to homeobox genes, opsin genes, genes involved in neural crest development, nuclear receptor genes, genes encoding components of the endocrine and immune systems, and conserved cis-regulatory enhancers. The amphioxus genome contains a basic set of chordate genes involved in development and cell signaling, including a fifteenth Hox gene. This set includes many genes that were co-opted in vertebrates for new roles in neural crest development and adaptive immunity. However, where amphioxus has a single gene, vertebrates often have two, three, or four paralogs derived from two whole-genome duplication events. In addition, several transcriptional enhancers are conserved between amphioxus and vertebrates--a very wide phylogenetic distance. In contrast, urochordate genomes have lost many genes, including a diversity of homeobox families and genes involved in steroid hormone function. The amphioxus genome also exhibits derived features, including duplications of opsins and genes proposed to function in innate immunity and endocrine systems. Our results indicate that the amphioxus genome is elemental to an understanding of the biology and evolution of nonchordate deuterostomes, invertebrate chordates, and vertebrates.
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| 2. |
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| 3. |
- Nakanowatari, Takuya, et al.
(författare)
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Hydrographic observations by instrumented marine mammals in the Sea of Okhotsk
- 2017
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Ingår i: Polar Science. - : Elsevier BV. - 1873-9652 .- 1876-4428. ; 13, s. 56-65
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Tidskriftsartikel (refereegranskat)abstract
- The Sea of Okhotsk is a challenging environment for obtaining in situ data and satellite observation in winter due to sea ice cover. In this study, we evaluated the validity of hydrographic observations by marine mammals (e.g., seals and sea lions) equipped with oceanographic conductivity-temperaturedepth (CTD) sensors. During 4-yr operations from 2011 to 2014, we obtained total of 997 temperature-salinity profiles in and around the Soya Strait, Iony Island, and Urup Strait. The hydrographic data were mainly obtained from May to August and the maximum profile depth in shelf regions almost reaches to the seafloor, while valuable hydrographic data under sea ice cover were also obtained. In strong thermoclines, the seal-derived data sometimes showed positive biases in salinity with spikelike signal. For these salinity biases, we applied a new thermal mass inertia correction scheme, effectively reducing spurious salinity biases in the seasonal thermocline. In the Soya Strait and the adjacent region, the detailed structure of the Soya Warm Current including the cold-water belt was well identified. Dense water up to 27.0 sigma(theta), which can be a potential source of Okhotsk Sea Intermediate Water, has flowed from the Soya Strait into the Sea of Okhotsk in mid-winter (February). In summer, around the Iony Island and Urup Strait, remarkable cold and saline waters are localized in the surface layers. These regions are also characterized by weak stratification, suggesting the occurrence of tidally induced vertical mixing. Thus, CTD-tag observations have a great potential in monitoring data-sparse regions in the Sea of Okhotsk.
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