Research

= Research =

  1. Unravelling bodyplan of Echinoderms (Prof. Akasaka, Dr. Omori)
  2. Gene networks involved in morphogenesis (Prof. Akasaka)
  3. Functional Analysis of a Novel Extracellular Matrix, Ars (Prof. Akasaka)
  4. Research of regeneration in feather stars (Prof. Akasaka, Dr. Kondo)
  5. Developmental evolution of echinoderms (Dr. Kondo, Dr. Omori)
  6. Mechanisms of Sperm Activation and Chemotaxis (Dr. Yoshida)
  7. Capacitation of Mammalian Sperm (Dr. Yoshida)
  8. Evolution of Vertebrate Otx2 enhancers (Dr. Kurokawa)
  9. Research about structure and function of the nervous system of crinoid (Dr. Omori)

1. Unravelling bodyplan of Echinoderms (Prof. Akasaka)

 Although echinoderms are members of deuterostomes, they possess very characteristic pentaradial bodies. How this bodyplan is produced continues to be a mystery. We are using different kinds of echinoderms, and through analyses of gene expression, such as of Hox which is involved in patterning along the body axis and genes involved in dorsalventral polarity, we aim to reveal the echinoderm bodyplan.
 The stalked crinoids (sea lilies) are generally accepted as the most ancient of living echinoderms, with a fossil record extending back some 500 million years. Thus this makes crinoids an important organism to study the evolution of the deuterostomes and echinoderms. Of the echinoderms, only crinoids have a ganglion. To study the evolutionary relationship of this ganglion and the central nervous system of chordates, we are also analyzing genes involved in the development of the central nervous system.


Bodyplans of echinoderms

2. Gene networks involved in morphogenesis (Prof. Akasaka)

 We are analyzing gene networks responsible for development of sea urchin which is the best model system to study molecular mechanisms development.


Gene regulatory network of
the micromere of sea urchin

3. Functional Analysis of a Novel Extracellular Matrix, Ars (Prof. Akasaka)

 Arylsulfatase (Ars) has been considered to be a lysosomal enzyme. However, using sea urchin embryos, we have shown that this protein has a role as an extracellular matrix, and that this is also true in mouse and rat. Though mutation of Ars leads to severe genetic disorders, the mechanism of pathogenesis is unclear and there is yet no cure. We are working in collaboration with medical researchers and private companies to elucidate the function of Ars and the mechanism of pathogenesis due to mutation in mammals.


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4. Research of regeneration in feather stars

 Molecular mechanisms of regeneration still remain unrevealed. Regeneration is observed widely among all animal phyla, but not in all species. Thus regeneration has been a topic also for evolutionary studies. Echinoderms possess strong regeneration abilities, and therefore, through comparative analysis, we may be able to understand the similarities and differences among/between different regeneration processes, and elucidate its evolutionary aspect. We are working on especially the feather star, to identify molecules involved in regeneration and development. Candidate genes are being isolated and investigated. Interestingly, feather stars are also able to regenerate their gonads. We are trying to find out where primordial germ cells arise from, if there are motile undifferentiated cells, if the process is analogous to development.

  
Regeneration of the arm of Anneissia japonica
  
Gonads of Anneissia japonica

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5. Developmental evolution of echinoderms (Dr. Kondo)

 Echinoderms exhibit diversity in their body plans between species. We are currently investing the Hox genes and its genomic structure (Hox cluster), which are considered to reflect body regionality. The sea urchin genome has been read and the Hox cluster has been revealed. Our study shows differences in the genomic structure. of the feather star. Conducting comparative analyses of the genome including Hox genes in various species, we may be able to find clues as to why echinoderms are so divergent.


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6. Mechanisms of Sperm Activation and Chemotaxis (Dr. Yoshida)

 Activation of the sperm motility and chemotactic behavior of sperm toward eggs are the first communication between spermatozoa and eggs at fertilization. We have determined the molecular structure of SAAF, the sperm-activating and attracting factor of the ascidian Ciona intestinalis, and now we are analyzing the molecular mechanisms of sperm activation and chemotaxis.

 


7. Capacitation of Mammalian Sperm (Dr. Yoshida)

 Mammalian sperm are infertile just after ejaculation, and capacitated in the female genital tract. On the other hand, some factors in seminal plasma is involved in the sperm capacitation. We are studying on the effect of a seminal vesicle, and we found that the protein released from the seminal vesicle acts as the decapacitation factor. Now we are analyzing the mechanisms of decapacitation.

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8. Evolution of Vertebrate Otx2 enhancers (Dr. Kurokawa)

 Otx2 is a paired-type homeobox gene that plays essential roles in each step and site of head development in vertebrates. We have identified enhancers that regulate the expression of Otx2 in developing embryos (Mouse, Softshelled turtle, chick, Xenopus, coelacanth, Fugu and Skate) and analyzing the conservation and diversification of cisacting elements during vertebrate evolution.





Spawning behavior of Takifugu niphobles

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9. Research about structure and function of the nervous system of crinoid (Dr. Omori)

 Crinoids are the most basal living echinoderms. They have three nervous systems including the aboral system, which is degraded in the other echinoderms. However, detailed research about structure and function of each nervous system of the crinoids was limited. We try to elucidate nerve cell distributions and developmental structures in the adult nervous systems of crinoids by using histological and molecular biological procedures.


Horizontal section of the calyx of the penta
-crinoid larva of Anneissia japonica

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