• Animal cells and systems
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• v.13 no.4
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• pp.411-418
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• 2009

We are reporting the identification, expression patterns, and possible biological functions of zebrafish kif3b (kif3bz) encoding 475 amino acids. Kif3Bz contains the kinesin motor domain, catalytic domain, KISc domain, and one single coiled coil domain. Phylogenetic analysis indicates that kif3bz is a highly conserved gene among the tested vertebrates. First of all, both maternal and zygotic messages of kif3bz were evenly distributed in the blastomeres at 2-cell stage. Its ubiquitous expression throughout the blastomeres continued till 40% epiboly. However, kif3bz transcripts became restricted in Kupffer's vesicle at tailbud and 6-somite stages. At 13-somite stage, kif3bz expression pattern became specific to the telencephalon, diencephalon, trigeminal placode, and somites. Such expression patterns were further intensified in the telencephalon, diencephalons, hind brain, pronephric ducts, optic vesicles, and spinal cord neurons in the 23-somite stage embryos, and last till 24 hpf. We discussed possible functions of Kif3Bz related to the vertebrate embryonic development.

• Toxicological Research
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• v.13 no.4
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• pp.417-421
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• 1997

Synaptobrevin is a kind of vesicle associated membrane proteins (VAMPs) which plays a secretary role in the neuronal synapse and was recently known as the biochemical target of botulinum neurotoxin type B. The structural gene of the synaptobrevin was cloned from mouse brain using RT-PCR technique and was seqrtenced. The deduced amino acid sequence showed that the synaptobrevin protein from mouse brain is exactly the same with that of the rat brain in the amino acid level. The synaptobrevin gene was subcloned into pET3a vector and expressed in E. coli. The molecular weight of the recombinant protein was 19 kDa as expected. Moreover, when the recombinant synaptobrevin protein was incubated with the native neurotoxin of Clostridium botulinum type B, it was cleaved by the toxin in a time dependent manner. This implies that the recombinant synaptobrevin protein and the native toxin are reacted in the same way as the native synaptobrevin did in the neuronal cells.

• Toxicological Research
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• v.17
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• pp.11-16
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• 2001

The development of the central nervous system is a continuous process during the embryonic and fetal periods. For a better understanding of congenital anomalies of central nervous system, three major events of normal development, i.e., neurulation (3 to 4 weeks), brain vesicle formation (4 to 7 weeks) and mantle formation (over 8 weeks) should be kept in mind. The first category of anomalies is neural tube defect. Neural tube defects encompass all the anomalies arise in completion of neurulation. The second category of central nervous system anomalies is disorders of brain vesicle formation. This is anomaly that applies for "the face predicts the brain". Holoprosencephaly covers a spectrum of anomalies of intracranial and midfacial development which result from incomplete development and septation of midline structures within the forebrain or prosencephalon. The last category of central nervous system malformation is disorders involving the process of mantle formation. In the human, neurons are generated in two bursts, the first from 8 to 10 weeks and next from 12 to 14 weeks. By 16 weeks, most of the neurons have been generated and have started their migration into the cortex. Mechanism of migration disorders are multifactorial. Abnormal migration into the cortex, abnormal neurons, faulty neural growth within the cortex, unstable pial-glial border, degeneration of neurons, neural death by exogenous factors are some of the proposed mechanism. Agyria-pachygyria are characterized by a four-layerd cortex. Polymicrogyria is gyri that are too numerous and too small, and is morphologically heterogeneous. Cortical dysplasia is characterized by the presence Q[ abnormal neurons and glia arranged abnormally in focal areas of the cerebral cortex. Neuroglial malformative lesions associated with medically intractable epilepsy are hamartia or hamartoma, focal cortical dysplasia and microdysgenesis.ysgenesis.

• Journal of Photoscience
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• v.9 no.2
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• pp.37-40
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• 2002

Ascidians are lower chordates, and their tadpole-like larvae share a basic body plan with vertebrates. To study photoreceptive systems in ascidians, we have isolated and characterized cDNA clones for three opsins, five G protein ${\alpha}$ subunits (G${\alpha}$), catalytic and regulatory subunits of cGMP phosphodiesterase (PDE), and arrestin from the ascidian Ciona intestinalis tadpole larva. Ci-opsin1 and Ci-opsin2 are vertebrate-type opsins, while Ci-opsin3 is a retinal photoisomerase similar to retinochrome and mammalian RGR. Both Ci-opsin1 and arrestin are specifically localized in the photoreceptor cells of the ocellus, whereas Ci -opsin2 is not expressed in the photoreceptors, but is co-localized in another population of neurons in the brain with PDE (Ci-PDE9 and Ci-PDE$\delta$). Ci-opsin3 is present in the entire region of the brain. Though five different cDNAs encoding Ga have been cloned, no transducin-type G protein has been found yet. Interestingly, one of G${\alpha}$i isoform is conspicuously expressed in the entire region of the brain. The Ci-opsin3 gene expression was observed in a broad area of the brain vesicle as well as in the visceral ganglion. Genes encoding ascidian homologs of CRALBP and ${\beta}$-CD, whose function is required for the mammalian visual cycle, are co-expressed with Ci-opsin3 in the brain vesicle and visceral ganglion. Localization of Ci-opsin3, CRALBP, and ${\beta}$-CD in a broad area of the brain suggests that the brain of the ascidian larva has a visual cycle system similar to that of the vertebrate RPE. Based on these data, we discuss the evolution of vertebrate visual systems.

• Molecules and Cells
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• v.39 no.10
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• pp.762-767
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• 2016

Fasciclin II (FasII), the Drosophila ortholog of neural cell adhesion molecule (NCAM), plays a critical role in synaptic stabilization and plasticity. Although this molecule undergoes constitutive cycling at the synaptic membrane, how its membrane trafficking is regulated to ensure proper synaptic development remains poorly understood. In a genetic screen, we recovered a mutation in Drosophila mical-like that displays an increase in bouton numbers and a decrease in FasII levels at the neuromuscular junction (NMJ). Similar phenotypes were induced by presynaptic, but not postsynaptic, knockdown of mical-like expression. FasII trafficking assays revealed that the recycling of internalized FasII molecules to the cell surface was significantly impaired in mical-like-knockdown cells. Importantly, this defect correlated with an enhancement of endosomal sorting of FasII to the lysosomal degradation pathway. Similarly, synaptic vesicle exocytosis was also impaired in mical-like mutants. Together, our results identify Mical-like as a novel regulator of synaptic growth and FasII endocytic recycling.

• Biomedical Science Letters
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• v.6 no.1
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• pp.11-17
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• 2000

SNAP-25 was first investigated as a neuron-specific protein preferentially expressed in CA3 pyramidal neurons of mouse hippocampus. It is a presynaptic plasma membrane protein in the nerve cell and plays an important role in the synaptic vesicle membrane docking and fusion pathway. We have recently isolated SNAP-25 cDNA from a rat brain cDNA library using a probe of Z2 cDNA. It consisted of 2,101 bp and an open reading frame (ORF) was identified between nucleotides (nt) 209 and 827. The AUG codon (nt 209∼211) was surrounded by CTACCATGG, which corresponded to the consensus sequence of ribosomal binding site. The ORF was terminated by TAA (nt 827∼829) to encode a polypeptide of 206 amino acid residues. The 3'-untranslated region contained two extensive stretches of repeated (CA)28 and (CA)19 at positions 925∼980 and 1645∼1682. It is noteworthy that cysteine residues were clustered in the span of amino acid residues 84∼991 : Cys-Gly-Leu-Cys-Val-Cys-Pro-Cys. Rat SNAP-25 showed 88% and 97% identity in nucleotide sequences to that of human and mouse, respectively. Amino acid sequence of rat SNAP-25 showed 100% identity to that of mouse and human SNAP-21.

• KSBB Journal
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• v.7 no.4
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• pp.302-307
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• 1992

Protein phosphatase 2A was obtained from a cytosolic fraction of bovine brain homogenate. The phosphatase activity using phosphorylated histone Hl as substrate was suppressed in the presence of liposomes composed of dipalmitoylphosphatidylcholine(DPPC) or the mixture of phosphatidylserine and DPPC. The binding of protein phosphatase to liposome was indicated by the facts that the phosphatase activity of the supernatant of protein phosphatase/multilayer vesicle mixture was decreased with increasing amount of liposome, and that [$^{125}I$]-labeled protein phosphatase was coeluted with liposome. However, the affinity of the protein for phospholipid membrane was not so high. On the other hand, okadaic acid and liposome reduced the phosphatase activity synergistically, which means that okadaic acid binds neither to lipid membrane nor to the membrane-associated phosphatase, The inhibitory effect of liposome was, therefore, ascribed to association of the protein phosphatase 2A with the lipid bilayer membrane.

• BMB Reports
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• v.50 no.12
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• pp.597-598
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• 2017

Mitochondria have evolutionarily, functionally and structurally distinct outer- (OMM) and inner-membranes (IMM). Thus, mitochondrial morphology is controlled by independent but coordinated activity of fission and fusion of the OMM and IMM. Constriction and division of the OMM are mediated by endocytosis-like machineries, which include dynamin-related protein 1 with additional cytosolic vesicle scissoring machineries such as actin filament and Dynamin 2. However, structural alteration of the IMM during mitochondrial division has been poorly understood. Recently, we found that the IMM and the inner compartments undergo transient and reversible constriction prior to the OMM division, which we termed CoMIC, ${\underline{C}}onstriction$ ${\underline{o}}f$ ${\underline{M}}itochondrial$ ${\underline{I}}nner$ ${\underline{C}}ompartment$. In this short review, we further discuss the evolutionary perspective and the regulatory mechanism of CoMIC during mitochondrial division.

• Development and Reproduction
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• v.16 no.4
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• pp.371-378
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• 2012

Notch signaling plays fundamental roles in various animal development. It has been suggested that Hr-Notch, a Notch homologue in the ascidian Halocynthia roretzi, is involved in the formation of peripheral neurons by suppressing the neural fates and promoting the epidermal differentiation. However, roles of Notch signaling remain controversial in the formation of nervous system in ascidian embryos. To precisely investigate functions of Notch signaling, we have isolated and characterized Hr-Numb, a Numb homologue which is a negative regulator of Notch signaling, in H. roretzi. Maternal expression of Hr-Numb mRNAs was detected in egg cytoplasm and the transcripts were inherited by the animal blastomeres. Its zygotic expression became evident by the early neurula stage and the transcripts were detected in dorsal neural precursor cells. Suppression of Hr-Numb function by an antisense morpholino oligonucleotide resulted in larvae with defect in brain vesicle and palps formation. Similar results have been obtained by overexpression of the constitutively activated Hr-Notch forms. Therefore, these results suggest that Hr-Numb is involved in Notch signaling during ascidian embryogenesis.

• Animal cells and systems
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• v.7 no.3
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• pp.221-225
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• 2003

The tadpole larva of the ascidian Halocynthia roretzi has two sensory pigment cells in its brain vesicle. To elucidate the temporal requirement for FGF signaling in formation of the pigment cells, embryos were treated with an FGF receptor 1 inhibitor, SU5402, or an MEK inhibitor, U0126 during various embryonic stages. In the present study, it is shown that the embryos treated with SU5402 from the 16-cell stage to the early gastrula stage do not form pigment cells, whereas those treated after the early gastrula stage form pigment cells. In pigment cell formation, embryos suddenly exhibited the sensitivity to SU5402 only for 1 h at the neural plate stage(-4 h after the beginning of gastrulation). When U0126 treatment was carried out at various stages between the 8-cell and late neurula stages, the embryos scarcely formed pigment cells. Pigment cell formation occurred when the embryos were placed in U0126 at early tail bud stage. These results indicate that FGF signaling is involved in pigment cell formation at two separate processes during ascidian embryogenesis, whereas more prolonged period is required for MEK signaling.