NIH Public Access

Department of Biological Sciences, Hopkins Marine Station of Stanford University, Pacific Grove, California, USA.
Developmental Dynamics (Impact Factor: 2.38). 12/2005; 234(4):997-1005. DOI: 10.1002/dvdy.20583
Source: PubMed


Development via regeneration or budding shares some known genetic pathways with embryogenesis, but no concerted effort has been made to identify genes unique to asexual development. We have identified a novel gene that plays a role in cyclical bud formation and asexual organogenesis in the colonial ascidian Botryllus schlosseri. Athena mRNA is transcribed at high levels during the 24- to 36-hr interval of programmed cell death and new bud initiation at the conclusion of the budding cycle (takeover). Knockdown of Athena by RNAi and antisense morpholinos induced defects in the development of new buds ranging from retardation in growth and abnormal organogenesis to hollow buds lacking organs. As genetic intervention in this organism has not been possible, this study establishes the use of RNAi and morpholinos in Botryllus as well as describing the knockdown phenotype of a new gene.

Download full-text


Available from: Robert Lauzon, Sep 02, 2014
16 Reads
  • Source
    • "Because single zooids, or even pieces of blood vessels, extracted from a colony reconstitute a full colony, experiments employing a large number of animals of identical genetic background can be carried out. Gene function in Botryllus can be inhibited by injection of short interfering RNAs (siRNAs) into the blood vasculature (Laird et al., 2005b). O. dioica is the reference species for appendicularians. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The tunicates, or urochordates, constitute a large group of marine animals whose recent common ancestry with vertebrates is reflected in the tadpole-like larvae of most tunicates. Their diversity and key phylogenetic position are enhanced, from a research viewpoint, by anatomically simple and transparent embryos, compact rapidly evolving genomes, and the availability of powerful experimental and computational tools with which to study these organisms. Tunicates are thus a powerful system for exploring chordate evolution and how extreme variation in genome sequence and gene regulatory network architecture is compatible with the preservation of an ancestral chordate body plan.
    Development 06/2011; 138(11):2143-52. DOI:10.1242/dev.048975 · 6.46 Impact Factor
  • Source
    • "The function of BsVEGFR has been studied by genetic knockdowns using short interfering double stranded RNA (siRNA), delivered by injection and soaking (Laird et al., 2005). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Angiogenesis, the growth and remodeling of a vascular network, is an essential process during development, growth and disease. Here we studied the role of the vascular endothelial growth factor receptor (VEGFR) in experimentally-induced angiogenesis in the colonial ascidian Botryllus schlosseri (Tunicata, Ascidiacea). The circulatory system of B. schlosseri is composed of two distinct, but interconnected regions: a plot of sinuses and lacunae which line the body, and a transparent, macroscopic extracorporeal vascular network. The vessels of the extracorporeal vasculature are morphologically inverted in comparison to the vasculature in vertebrates: they consist of a single layer of ectodermally-derived cells with the basal lamina lining the lumen of the vessel. We found that when the peripheral circulatory system of a colony is surgically removed, it can completely regenerate within 24 to 48 h and this regeneration is dependent on proper function of the VEGF pathway: siRNA-mediated knockdown of the VEGFR blocked vascular regeneration, and interfered with vascular homeostasis. In addition, a small molecule, the VEGFR kinase inhibitor PTK787/ZK222584, phenocopied the siRNA knockdown in a reversible manner. Despite the disparate germ layer origins and morphology of the vasculature, the developmental program of branching morphogenesis during angiogenesis is controlled by similar molecular mechanisms, suggesting that the function of the VEGF pathway may be co-opted during the regeneration of an ectoderm-derived tubular structure.
    Developmental Biology 04/2008; 315(1):243-55. DOI:10.1016/j.ydbio.2007.12.035 · 3.55 Impact Factor
  • Source
    • "The specific primers used to synthesize these siRNAs were as follows: A15 5Ј-AACAAGAG- CAATATCGCGGACCCTGTCTC-3Ј and A13 5Ј-AAGTCCGCGATATT- GCTCTTGCCTGTCTC-3Ј; A25 5Ј- AATGGGATGAAAGACGAGGAGC- CTGTCTC-3Ј and A23 5Ј-AACTC- CTCGTCTTTCATCCCACCTGTCTC-3Ј; A35 5Ј-AAGATTGGAATATAGCTCTC- CCCTGTCTC-3Ј and A33 5Ј-AAG- GAGAGCTATATTCCAATCCCTGTC- TC-3Ј; A55 5Ј-AAATACGACGATAT- ACCAGTGCCTGTCTC-3Ј and A53 5Ј- AACACTGGTATATCGTCGTATCCT- GTCTC-3Ј. An additional set of primers was used to synthesize an unrelated control siRNA (Laird et al., 2005) derived from plasmid sequence: Control5 5Ј-AACCATCTGCTAATCTGTAAC- CCTGTCTC-3Ј and Control3 5Ј-AAGT- TACAGATTAGCAGATGGCCTGTC- TC-3Ј. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Proteins of the highly conserved PL-10 (Ded1P) subfamily of DEAD-box family, participate in a wide variety of biological functions. However, the entire spectrum of their functions in both vertebrates and invertebrates is still unknown. Here, we isolated the Botryllus schlosseri (Urochordata) homologue, BS-PL10, revealing its distributions and functions in ontogeny and colony astogeny. In botryllid ascidians, the colony grows by increasing the number of modular units (each called a zooid) through a whole colony synchronized and weekly cyclical astogenic budding process (blastogenesis). At the level of the colony, both BS-PL10 mRNA and its protein (78 kDa) fluctuate in a weekly pattern that corresponds with the animal's blastogenic cycle, increasing from blastogenic stage A to blastogenic stage D. At the organ/module level, a sharp decline is revealed. Primary and secondary developing buds express high levels of BS-PL10 mRNA and protein at all blastogeneic stages. These levels are reduced four to nine times in the new set of functional zooids. This portrait of colony astogeny differed from its ontogeny. Oocytes and sperm cells express high levels of BS-PL10 protein only at early stages of development. Young embryos reveal background levels with increased expressions in some organs at more developed stages. Results reveal that higher levels of BS-PL10 mRNA and protein are characteristic to multipotent soma and germ cells, but patterns deviate between two populations of differentiating stem cells, the stem cells involved in weekly blastogenesis and stem cells involved in embryogenesis. Two types of experimental manipulations, zooidectomy and siRNA assays, have confirmed the importance of BS-PL10 for cell differentiation and organogenesis. BS-PL10 (phylogenetically matching the animal's position in the evolutionary tree), is the only member of this subfamily in B. schlosseri, featuring a wide range of biological activities, some of which represent pivotal roles. The surprising weekly cyclical expression and the participation in cell differentiation posit this molecule as a model system for studying PL10 protein subfamily.
    Developmental Dynamics 06/2006; 235(6):1508-21. DOI:10.1002/dvdy.20728 · 2.38 Impact Factor
Show more