Abstract:
:Botryllus schlosseri is a colonial marine urochordate in which all adult organisms (called zooids) in a colony die synchronously by apoptosis (programmed cell death) in cyclical fashion. During this death phase called takeover, cell corpses within the dying organism are engulfed by circulating phagocytic cells. The "old" zooids and their organs are resorbed within 24-36 h (programmed cell removal). This process coincides temporally with the growth of asexually derived primary buds, that harbor a small number of undifferentiated cells, into mature zooids containing functional organs and tissues with the same body plan as adult zooids from which they budded. Within these colonies, all zooids share a ramifying network of extracorporeal blood vessels embedded in a gelatinous tunic. The underlying mechanisms regulating programmed cell death and programmed cell removal in this organism are unknown. In this study, we extirpated buds or zooids from B. schlosseri colonies in order to investigate the interplay that exists between buds, zooids, and the vascular system during takeover. Our findings indicate that, in the complete absence of buds (budectomy), organs from adult zooids underwent programmed cell death but were markedly impaired in their ability to be resorbed despite engulfment of zooid-derived cell corpses by phagocytes. However, when buds were removed from only half of the flower-shaped systems of zooids in a colony (hemibudectomy), the budectomized zooids were completely resorbed within 36-48 h following onset of programmed cell death. Furthermore, if hemibudectomies were carried out by using small colonies, leaving only a single functional bud, zooids from the old generation were also resorbed, albeit delayed to 48-60 h following onset of programmed cell death. This bud eventually reached functional maturity, but grew significantly larger in size than any control zooid, and exhibited hyperplasia. This finding strongly suggested that components of the dying zooid viscera could be reutilized by the developing buds, possibly as part of a colony-wide recycling mechanism. In order to test this hypothesis, zooids were surgically removed (zooidectomy) at the onset of takeover, and bud growth was quantitatively determined. In these zooidectomized colonies, bud growth was severely curtailed. In most solitary, long-lived animals, organs and tissues are maintained by processes of continual death and removal of aging cells counterbalanced by regeneration with stem and progenitor cells. In the colonial tunicate B. schlosseri, the same kinds of processes ensure the longevity of the colony (an animal) by cycles of death and regeneration of its constituent zooids (also animals).
journal_name
Dev Bioljournal_title
Developmental biologyauthors
Lauzon RJ,Ishizuka KJ,Weissman ILdoi
10.1006/dbio.2002.0772subject
Has Abstractpub_date
2002-09-15 00:00:00pages
333-48issue
2eissn
0012-1606issn
1095-564Xpii
S0012160602907724journal_volume
249pub_type
杂志文章abstract::The inactivation of the prolactin receptor gene by homologous recombination has made it possible to investigate the role of prolactin signaling in mammary gland development without resort to ablative surgery of the endocrine glands. In knockout mice lacking the prolactin receptor, mammary development is normal up to p...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1999.9271
更新日期:1999-06-01 00:00:00
abstract::The myogenic basic helix-loop-helix transcription factor myogenin plays an essential role in the differentiation of skeletal muscle and, secondarily, in rib and sternum formation during mouse development. However, virtually nothing is known about the quantitative requirements for myogenin in these processes. Here, we ...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1998.9182
更新日期:1999-04-01 00:00:00
abstract::To investigate the molecular regulation of embryonic somite formation and development, we have cloned the full-length cDNA and characterized the embryonic expression profile of chicken Paraxis, a member of a novel family of basic helix-loop-helix (bHLH) proteins, which has been suggested to play a role in paraxial mes...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1997.8663
更新日期:1997-09-01 00:00:00
abstract::Treatment of metaphase II-arrested hamster eggs with activators of protein kinase C has been reported to promote resumption of the cell cycle, second polar body emission, and pronucleus formation (G.I. Gallicano, S.M. Schwarz, R.W. McGaughey, and D.G. Capco, 1993, Dev. Biol. 156, 94-106). In contrast, we have not obse...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1995.1233
更新日期:1995-08-01 00:00:00
abstract::All metazoan genomes encode multiple RAS GTPase activating proteins (RasGAPs) that negatively regulate the conserved RAS/MAPK signaling pathway. In mammals, several RasGAPs exhibit tumor suppressor activity by preventing excess RAS signal transduction. We have identified gap-3 as the to date missing Caenorhabditiseleg...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2008.08.026
更新日期:2008-11-15 00:00:00
abstract::Spermatogonia are adult germline stem cells that can both self-renew and differentiate into spermatocytes. Little is known about factors necessary for spermatogonial differentiation. We identified a novel germ-cell-specific transcription factor that we named Sohlh1 (testis and ovary expressed basic helix-loop-helix (b...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2006.02.027
更新日期:2006-06-01 00:00:00
abstract::Neural crest cells migrate extensively through a complex extracellular matrix (ECM) to sites of terminal differentiation. To determine what role the various components of the ECM may play in crest morphogenesis, quail (Coturnix coturnix japonica) neural crest cells have been cultured in three-dimensional hydrated coll...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/0012-1606(84)90094-0
更新日期:1984-08-01 00:00:00
abstract::Septins are guanosine triphosphate-binding proteins that are evolutionally conserved in all eukaryotes other than plants. They function as multimeric complexes that interact with membrane lipids, actomyosin, and microtubules. Based on these interactions, septins play essential roles in the morphogenesis and physiologi...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2016.09.012
更新日期:2016-11-15 00:00:00
abstract::Intestinal tract development is a coordinated process involving signaling among the progenitors and developing cells from all three germ layers. Development of endoderm-derived intestinal epithelium has been shown to depend on epigenetic modifications, but whether that is also the case for intestinal tract cell types ...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2019.08.002
更新日期:2019-11-15 00:00:00
abstract::Hedgehog (Hh) proteins and cAMP-dependent protein kinase A (PKA) generally play opposing roles in developmental patterning events. Humans and mice heterozygous for mutations in the sonic hedgehog (Shh) receptor gene patched-1 (ptc1) have an increased incidence of certain types of cancer, including medulloblastoma (MB)...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2007.10.031
更新日期:2008-01-01 00:00:00
abstract::Fetal human hepatocytes were isolated by collagenase digestion of liver fragments and cultured either alone or mixed with rat liver epithelial cells. Whereas they did not survive more than 2-3 weeks and showed rapid morphologic and functional alterations in conventional culture, fetal hepatocytes survived and retained...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/0012-1606(84)90276-8
更新日期:1984-09-01 00:00:00
abstract::In order to further our understanding of the biological role of desmin, the muscle-specific intermediate filament protein, a null mutation in the desmin gene was introduced into the germ line of mice. Despite the complete lack of desmin, these mice developed and reproduced. Since we show that skeletal, cardiac, and sm...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1996.0122
更新日期:1996-05-01 00:00:00
abstract::The GRAM domain was found in glucosyltransferases, myotubularins and other membrane-associated proteins. So far, functions for majority of these proteins are yet to be uncovered. In order to address the evolutionary and functional significance of this family members, we have performed a comprehensive investigation on ...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2007.11.031
更新日期:2008-02-15 00:00:00
abstract::Continuous communication between cells is necessary for development of any multicellular organism and depends on the recognition of secreted signals. A wide range of molecules including proteins, peptides, amino acids, nucleic acids, steroids and polylketides are used as intercellular signals in plants and animals. Th...
journal_title:Developmental biology
pub_type: 杂志文章,评审
doi:10.1016/j.ydbio.2014.04.001
更新日期:2014-07-01 00:00:00
abstract::Regulation of gene expression during early embryonic development in the rabbit was investigated by quantitative assay of firefly luciferase activity obtained by microinjection of three plasmid constructs using the regulatory region of polyomavirus promoter (PrPyV) with two different enhancer sequences (wild type or mu...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1994.1188
更新日期:1994-07-01 00:00:00
abstract::We have isolated a cDNA of the DEAD protein family from a Xenopus ovary cDNA library. Northern hybridization revealed that the mRNA corresponding to the cDNA [XVLG1 (Xenopus vasa-like gene)] was specifically expressed in adult testis and ovary. The deduced amino acid sequence of XVLG1 was relatively homologous to that...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1994.1093
更新日期:1994-04-01 00:00:00
abstract::The Drosophila Suppressor of Hairy wing [Su(Hw)] insulator protein has an essential role in the development of the female germline. Here we investigate the function of Su(Hw) in the ovary. We show that Su(Hw) is universally expressed in somatic cells, while germ cell expression is dynamic. Robust levels accumulate in ...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2011.05.666
更新日期:2011-08-15 00:00:00
abstract::Although the formation and maintenance of epithelial tubes are essential for the viability of multicellular organisms, our understanding of the molecular and cellular events coordinating tubulogenesis is relatively limited. Here, we focus on the activities of Ribbon, a novel BTB-domain containing nuclear protein, in t...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2008.05.541
更新日期:2008-08-01 00:00:00
abstract::The processes of myelination remain incompletely understood but are of profound biomedical importance owing to the several dysmyelinating and demyelinating disorders known in humans. Here, we analyze the zebrafish puma mutant, isolated originally for pigment pattern defects limited to the adult stage. We show that pum...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2010.07.035
更新日期:2010-10-15 00:00:00
abstract::Neural crest cells migrate along two pathways in the trunk: the ventral path, between the neural tube and somite, and the dorsolateral path, between the somite and overlying ectoderm. In avian embryos, ventral migration precedes dorsolateral migration by nearly 24 h, and the onset of dorsolateral migration coincides w...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1998.8963
更新日期:1998-08-15 00:00:00
abstract::During mouse fertilization the spermatozoon induces a series of low-frequency long-lasting Ca(2+) oscillations. It is generally accepted that these oscillations are due to Ca(2+) release through the inositol 1,4,5-trisphosphate (InsP(3)) receptor. However, InsP(3) microinjection does not mimic sperm-induced Ca(2+) osc...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.2000.9826
更新日期:2000-09-01 00:00:00
abstract::Superior cervical ganglia of postnatal mice with a targeted disruption of the gene for neurotrophin-3 have 50% fewer neurons than those of wild-type mice. In culture, neurotrophin-3 increases the survival of proliferating sympathetic precursors. Both precursor death (W. ElShamy et al., 1996, Development 122, 491-500) ...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1999.9269
更新日期:1999-06-15 00:00:00
abstract::T-box family transcription factors play many roles in Metazoan development. Here we characterise Tbx6r, a unique Tbx6 paralogue isolated from the amphibian Xenopus. The evolution and developmental integration of this divergent T-box gene within the vertebrates reveals an unexpected level of plasticity within this cons...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2010.01.013
更新日期:2010-04-01 00:00:00
abstract::Understanding the biology of somatic stem cells in self renewing tissues represents an exciting field of study, especially given the potential to harness these cells for tissue regeneration and repair in treating injury and disease. The mammalian cornea contains a population of basal epithelial stem cells involved in ...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2012.12.005
更新日期:2013-02-15 00:00:00
abstract::We have been studying oligodendrocyte generation in vitro to obtain insights into how the timely generation of these cells might be regulated. Our studies suggest the existence of timing mechanisms quite different from those of existing models, wherein it is proposed that timely oligodendrocyte generation is associate...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1996.0280
更新日期:1996-11-25 00:00:00
abstract::Developing cardiac myocytes divide a limited number of times before they stop and terminally differentiate, but the mechanism that stops their division is unknown. To help study the stopping mechanism, we defined conditions under which embryonic rat cardiac myocytes cultured in serum-free medium proliferate and exit t...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1999.9524
更新日期:1999-12-15 00:00:00
abstract::Previous studies from this laboratory have identified a novel alpha-D-mannosidase on the sperm plasma membranes of several species, including man, which may have a role in fertilization. The polyclonal antibody raised against an isoform of the enzyme purified from rat epididymal fluid was found to cross-react with the...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1995.1050
更新日期:1995-02-01 00:00:00
abstract::Polycomb group (PcG) proteins are best known for their role in maintaining stable, mitotically heritable silencing of the homeotic (HOX) genes during development. In addition to loss of homeotic gene silencing, some PcG mutants also have small imaginal discs. These include mutations in E(z), Su(z)12, esc and escl, whi...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2013.03.011
更新日期:2013-08-01 00:00:00
abstract::Initiation of the development of the anterior-posterior axis in the mouse embryo has been thought to take place only when the anterior visceral endoderm (AVE) emerges and starts its asymmetric migration. However, expression of Lefty1, a marker of the AVE, was recently found to initiate before embryo implantation. This...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1016/j.ydbio.2007.06.020
更新日期:2007-09-01 00:00:00
abstract::Smad4 is defined as the common-mediator Smad (co-Smad) required for transducing signals for all TGF-beta superfamily members. This paper describes two Smad4s in Xenopus: XSmad4alpha, which is probably the Xenopus orthologue of human Smad4, and a distinct family member, XSmad4beta, which differs primarily at the extrem...
journal_title:Developmental biology
pub_type: 杂志文章
doi:10.1006/dbio.1999.9430
更新日期:1999-10-15 00:00:00