[Show abstract][Hide abstract]ABSTRACT: Bone morphogenetic proteins (BMPs) are responsible for regulating embryo development and tissue homeostasis beyond osteogenesis. However, the precise biological roles of BMP3 and BMP3b remain obscure to a certain extent. In the present study, we cloned an orthologous gene (AmphiBMP3/3b) from amphioxus (Branchiostoma japonicum) and found its exon/intron organization is highly conserved. Further, in situ hybridization revealed that the gene was strongly expressed in the dorsal neural plate of the embryos. The gene also appeared in Hatschek's left diverticulum, neural tube, preoral ciliated pit and gill slit of larvae, and adult tissues including ovary, neural tube and notochordal sheath. Additionally, real-time quantitative polymerase chain reaction (RTqPCR) analysis revealed that the expression displayed two peaks at gastrula and juvenile stages. These results indicated that AmphiBMP3/3b, a sole orthologue of vertebrate BMP3 and BMP3b, might antagonize ventralizing BMP2 orthologous signaling in embryonic development, play a role in the evolutionary precursors of adenohypophysis, as well as act in female ovary physiology in adult.
Full-text · Article · Feb 2010 · Development Growth and Regeneration
[Show abstract][Hide abstract]ABSTRACT: Green fluorescent protein (GFP) has been widely used as a molecular marker in modern biological research. Before the recent report of one GFP gene in Branchiostoma floridae, GFP family members were cloned only from other two groups of species: Cnidaria and Copepoda. Here we describe the complete GFP gene repertoire of B. floridae which includes 13 functional genes and 2 pseudogenes, representing the largest GFP family found so far. Coupling with nine other GFP sequences from another two species of genus Branchiostoma and the sequences from Cnidaria and Copepoda, we made a deep-level phylogenetic analysis for GFP genes in cephalochordates and found: 1) GFP genes have experienced a divergent evolution in cephalochordates; 2) all amphioxus GFP genes form four main clades on the tree which had diverged before the radiation of the last common ancestor of all extant cephalochordates; 3) GFP genes in amphioxus shared a common ancestor with that in Copepoda rather than being derived from horizontal gene transfer, which indicates that our ancestor was derived from a fluorescent organism and lost this ability after its separation from Cephalochordata, and also makes GFP a rare gene which has a rather unusual evolutionary path. In addition, we also provided evidence indicating that GFP genes have evolved divergent functions by specializing their expression profile, and different fluorescent spectra by changing their emission peaks. These findings spark two interesting issues: what are GFP in vivo functions in cephalochordates and why they are lost in other examined deuterostomes?
[Show abstract][Hide abstract]ABSTRACT: Amphioxus has an important evolutionary position as a result of their phylogenetic position relative to vertebrates. Understanding their chromosomes would provide key points in the study of evolutionary biology and comparative genomics. The difficulty in preparing amphioxus chromosomes currently provides a significant hurdle in this research. In the current study, we describe an improved method for metaphase preparation from amphioxus embryos and methodology for preparing metaphase spreads from regenerative somatic cells. Chromosomes of two amphioxus species from Xiamen waters in China are also observed. The diploid chromosome number was found to be 40 in Branchiostoma belcheri , while B. japonicum has 36, confirming the two are distinct species from cytotaxonomic viewpoint.
Full-text · Article · Jul 2009 · Zoological Research
[Show abstract][Hide abstract]ABSTRACT: Previous studies showed that the vertebrate ABCA subfamily, one subgroup of the ATP-binding-cassette superfamily, has evolved rapidly in terms of gene duplication and loss. To further uncover the evolutionary history of the ABCA subfamily, we characterized ABCA members of two amphioxus species (Branchiostoma floridae and B. belcheri), the closest living invertebrate relative to vertebrates. Phylogenetic analysis indicated that these two species have the same set of ABCA genes (both containing six members). Five of these genes have clear orthologs in vertebrate, including one cephalochordate-specific duplication and one vertebrate-specific duplication. In addition, it is found that human orthologs of amphioxus ABCA1/4/7 and its neighboring genes mainly localize on chromosome 1, 9, 19 and 5. Considering that most of analyzed amphioxus genes have clear orthologs in zebrafish, we conclude these four human paralogous regions might derive from a common ancestral region by genome duplication occurred prior to teleost/tetrapod split. Therefore, the present results provide new evidence for 2R hypothesis.
[Show abstract][Hide abstract]ABSTRACT: The lancelet is considered to be a promising laboratory model animal. To establish laboratory colonies of lancelet, we collected parental lancelets of Branchiostoma belcheri and B. japonicum (previously named as B. belcheri tsingtauense) with fully developed gonads from Xiamen Rare Marine Creature Conservation Areas (Fujian, China) on dates just before their spawning in the field in 2005. Those parental lancelets spawned spontaneously in the laboratory and produced thousands upon thousands of fertilized eggs. After carefully hatching and maintaining for almost 1 year, we successfully obtained about 500 first generation (F1) adults of B. belcheri and 3,300 of B. japonicum. Part of those F1 lancelets ripened and spontaneously spawned in 2006, and several thousands of second generation (F2) individuals of both species were produced. The young F2 lancelets are growing in good condition and some of B. japonicum initiated gonad development in December, 2006. Our experience emphasizes that cleanness of settlement substratum and sufficient food supply are important factors for long-term culture of lancelets in the laboratory.
Full-text · Article · Jul 2007 · Journal of Experimental Zoology Part B Molecular and Developmental Evolution
[Show abstract][Hide abstract]ABSTRACT: Lancelets in Xiamen were reported as Branchiostoma belcheri in 1932, and subsequently were believed to comprise a single species. However, recent studies revealed that Xiamen lancelets actually represent two species, B. belcheri and B. japonicum. We observed thousands of lancelets from Xiamen beach to recognize these two species. Our observations showed that at least three morphological characters distinguish them: 1) the rostral fin is slightly round with the end obtuse in B. belcheri but elliptic with the end cuspate in B. japonicum; 2) the number of preanal fin-chambers is more than 80 in B. belcheri but less than 64 in B. japonicum, and the chambers are slender in the former but stout in the latter; 3) the caudal fin of B. belcheri is narrower than that of B. japonicum, and the angle between the dorsal and super-caudal fins, and between preanal and sub-caudal fins, is obtuse in B. belcheri but acute in B. japonicum. We also provide some ecological and distributional evidence to support the conclusion that there are two separate species in Xiamen waters.