Visualization of myelination in GFP‐transgenic zebrafish

Jung, Seung‐,Hyun,Kim, Suhyun,Chung, Ah‐,Young,Kim, Hyun‐,Taek,So, Ju‐,Hoon,Ryu, Jaeho,Park, Hae‐,Chul,Kim, Cheol‐,Hee Wiley‐Liss, Inc. 2010 Developmental dynamics Vol.239 No.2

<P><B>Abstract</B></P><P>The insulation of axons in the vertebrate nervous system by myelin is essential for efficient axonal conduction. Myelination disruption and remyelination failure can cause human diseases, such as multiple sclerosis and hereditary myelin diseases. However, despite progress in understanding myelination regulation, many important questions remain unanswered. To investigate the mechanisms underlying myelination in vivo, we generated transgenic zebrafish expressing enhanced green fluorescent protein (EGFP) under the control of the mbp promoter. This transgenic fish displayed faithful EGFP expression in oligodendrocytes and Schwann cells in embryonic and adult zebrafish. Interestingly, although myelination progressed continuously in the postembryonic central nervous system, some of the spinal cord regions were filled with unmyelinated axons even in the adult spinal cord, suggesting functional differences between myelinated and unmyelinated axons. Our results suggest that this transgenic zebrafish could be a valuable animal model to study oligodendrocyte differentiation and myelination in vivo. Developmental Dynamics 239:592–597, 2010. © 2009 Wiley‐Liss, Inc.</P>

A circulatory transcriptional regulation among <i>daf‐9, daf‐12</i>, and <i>daf‐16</i> mediates larval development upon cholesterol starvation in <i>Caenorhabditis elegans</i>†

Jeong, Myung‐,Hwan,Kawasaki, Ichiro,Shim, Yhong‐,Hee Wiley‐Liss, Inc. 2010 Developmental dynamics Vol.239 No.7

<P><B>Abstract</B></P><P><I>C. elegans</I> shows dauer‐like larvae formation upon cholesterol starvation (CS), but the genetic epistasis among abnormal dauer formation (<I>daf</I>) genes during the process remains unclear. To clarify the genetic interactions among <I>daf‐9, daf‐12</I>, and <I>daf‐16</I> in this process, mRNA levels of these genes upon CS were measured. CS increased the mRNA levels of <I>daf‐9, daf‐12</I>, and <I>daf‐16</I>. CS also induced DAF‐16 nuclear localization, which was positively and negatively regulated by DAF‐12 and DAF‐9 activities, respectively. Activated DAF‐16, a FOXO transcription factor, enhanced <I>daf‐12</I> but suppressed <I>daf‐9</I> expression, whereas DAF‐9 inhibited <I>daf‐12</I> expression. Concomitantly, CS‐induced larval arrest was regulated positively by DAF‐12 and DAF‐16, but negatively by DAF‐9. The larval arrest in <I>daf‐9</I> mutant was suppressed by <I>daf‐12</I> RNAi, placing DAF‐12 downstream of DAF‐9. These results altogether suggest that circulatory mutual regulation among <I>daf‐9, daf‐12</I>, and <I>daf‐16</I> at the expression level mediates cholesterol signal to control larval development upon CS. Developmental Dynamics 239:1931–1940, 2010. © 2010 Wiley‐Liss, Inc.</P>

Essential role of clusterin in pancreas regeneration

Lee, Song,Hong, Seok‐,Woo,Min, Bon‐,Hong,Shim, Young‐,Jun,Lee, Ki‐,Up,Lee, In‐,Kyu,Bendayan, M.,Aronow, Bruce J.,Park, In‐,Sun Wiley‐Liss, Inc. 2011 Developmental dynamics Vol.240 No.3

<P><B>Abstract</B></P><P>Based on our previous observations that clusterin induction accompanies pancreas regeneration in the rat, we sought to determine if regeneration might be impaired in mice that lacked clusterin. We studied the impact of absent clusterin on morphogenic and functional features of regenerating pancreas. Clusterin induction was accompanied in the regenerating pancreas by a robust development of new lobules with ductules, acini, and endocrine islets in wild type after partial pancreatectomy. In clusterin knock‐out mice, however, pancreatectomy resulted in a poor formation of regenerating lobule. In particular, regeneration of beta‐cells was also significantly reduced and was associated with persistent hyperglycemia. Duct cells obtained from pancreatectomized clusterin knock‐out mice exhibited impaired beta‐cell formation in vitro; this was restored by administration of exogenous clusterin. We suggest that clusterin plays a critical role to promote both exocrine and endocrine regeneration following pancreas injury, as well as for in vitro beta‐cell regeneration. Developmental Dynamics 240:605–615, 2011. © 2011 Wiley‐Liss, Inc.</P>

Neuron‐specific expression of <i>atp6v0c2</i> in zebrafish CNS

Chung, Ah‐,Young,Kim, Myoung‐,Jin,Kim, Dohyun,Bang, Sangsu,Hwang, Sun Wook,Lim, Chae Seung,Lee, Sanggyu,Park, Hae‐,Chul,Huh, Tae‐,Lin Wiley‐Liss, Inc. 2010 Developmental dynamics Vol.239 No.9

<P><B>Abstract</B></P>10.1002/dvdy.22383.abs<P>Vacuolar ATPase (V‐ATPase) is a multi‐subunit enzyme that plays an important role in the acidification of a variety of intracellular compartments. ATP6V0C is subunit c of the V<SUB>0</SUB> domain that forms the proteolipid pore of the enzyme. In the present study, we investigated the neuron‐specific expression of <I>atp6v0c2</I>, a novel isoform of the V‐ATPase c‐subunit, during the development of the zebrafish CNS. Zebrafish <I>atp6v0c2</I> was isolated from a genome‐wide analysis of the zebrafish <I>mib</I><SUP><I>ta52b</I></SUP> mutant designed to identify genes differentially regulated by Notch signaling. Whole‐mount in situ hybridization revealed that <I>atp6v0c2</I> is expressed in a subset of CNS neurons beginning several hours after the emergence of post‐mitotic neurons. The ATP6V0C2 protein is co‐localized with the presynaptic vesicle marker, SV2, suggesting that it is involved in neurotransmitter storage and/or secretion in neurons. In addition, the loss‐of‐function experiment suggests that ATP6V0C2 is involved in the control of neuronal excitability. Developmental Dynamics 239:2501–2508, 2010. © 2010 Wiley‐Liss, Inc.</P>

Chromosome remodeling and differentiation of tetraploid embryos during preimplantation development

Park, Mi‐,Ryung,Lee, Ah‐,Reum,Bui, Hong‐,Thuy,Park, Chankyu,Park, Keun‐,Kyu,Cho, Ssang‐,Goo,Song, Hyuk,Kim, Jae‐,Hwan,Van Thuan, Nguyen,Kim, Jin‐,Hoi Wiley‐Liss, Inc. 2011 Developmental dynamics Vol.240 No.7

<P><B>Abstract</B></P><P>Although it is known that the tetraploid embryo contributes only to the placenta, the question of why tetraploid embryos differentiate into placenta remains unclear. To study the effect of electrofusion on the development of mouse tetraploid oocytes, mouse two‐cell embryos were fused and cultured in vitro in Chatot‐Ziomek‐Bavister medium. After electrofusion, two chromosome sets from the tetraploid blastomere were individually duplicated before nuclear fusion. At 8–10 hr after electrofusion, each chromosome set was condensing and the nuclear membrane was breaking down. Around 12–14 hr after electrofusion, the two chromosome sets had combined together and had reached the second mitotic metaphase, at this point with 8n sets of chromosomes. Interestingly, we discovered that expression of OCT4, an inner cell mass cells biomarker, is lost by the tetraploid expanded blastocysts, but that CDX2, a trophectoderm cells biomarker, is strongly expressed at this stage. This observation provides evidence clarifying why tetraploid embryos contribute only to trophectoderm. Developmental Dynamics 240:1660–1669, 2011. © 2011 Wiley‐Liss, Inc.</P>

The distribution of neuron‐specific gene family member 1 in brain and germ cells: Implications for the regulation of germ‐line development by brain

Rengaraj, Deivendran,Lee, Bo Ram,Park, Kyung Je,Lee, Sang In,Kang, Kyung Soo,Choi, Jin Won,Kang, Seok Jin,Song, Gwonhwa,Han, Jae Yong Wiley‐Liss, Inc. 2011 Developmental dynamics Vol.240 No.4

<P><B>Abstract</B></P><P>Vesicular acidification at early endosomes dissociates endocytosed receptor‐ligand complexes. The ligands, receptors, or both are then directed to late endosomes for degradation or recycled back to the plasma membrane. Of neuron‐specific gene (NSG) family members, early endosomal protein neuron‐specific gene family member 1 (NSG1) is the most important in receptor recycling. In this study, we characterized chicken NSG1 (cNSG1). We found several functional sites related to endocytotic machinery in cNSG1 that were highly conserved with most other vertebrate NSG1 proteins. We examined the tissue and duration specificity and the temporal and spatial patterns of c<I>NSG1</I> expression<I>.</I> c<I>NSG1</I> expression was preferentially located in all regions of the brain, neuroendocrine glands, and spinal cord. Unexpectedly, c<I>NSG1</I> expression was strongly detected during male and female germ‐line development. Expression of <I>NSG1</I> in two apparently unrelated cell types such as neurons and germ cells suggests <I>NSG1</I> roles in neurons and germ‐cells chemotaxis and endocytotic machinery. Developmental Dynamics 240:850–861, 2011. © 2011 Wiley‐Liss, Inc.</P>

Rab3d is required for <i>Xenopus</i> anterior neurulation by regulating noggin secretion

Kim, Hyunjoon,Han, Jin‐,Kwan Wiley‐Liss, Inc. 2011 Developmental dynamics Vol.240 No.6

<P><B>Abstract</B></P><P>Rab3d is a member of the Ras‐related small GTPase family of secretory Rab, Rab3. In this study, we showed that <I>Xenopus</I> Rab3d is expressed specifically in the anterior border of the neural plate when the neural plate converges and folds to initiate neural tube formation. Morpholino‐mediated knockdown of Rab3d resulted in neurulation defects both in neural plate convergence and folding. Interestingly, perturbation of BMP signaling rescued neurulation defects of Rab3d morphants, suggesting that Rab3d inhibits BMP signaling during neurulation. By secretion assay in the <I>Xenopus</I> animal cap, we found that Rab3d specifically regulates secretion of a BMP antagonist, Noggin, but not Chordin and Wnts. We also found that Rab3d is co‐localized with Noggin and that this interaction is dependent on the GTP/GDP cycle of Rab3d. Collectively, these findings suggest that Rab3d‐mediated secretion regulation of a BMP antagonist, Noggin, is one of the mechanisms of BMP antagonism during <I>Xenopus</I> anterior neurulation. Developmental Dynamics 240:1430–1439, 2011. © 2011 Wiley‐Liss, Inc.</P>

Halogenated nucleotide labeling of nascent RNAs reveals dynamic transcription in growing pig oocytes

Oqani, Reza K.,Lee, Min Gu,Diao, Yun Fei,Han, Rong Xun,Jin, Dong Il Wiley‐Liss, Inc. 2013 Developmental dynamics Vol.242 No.1

<P><B>Abstract</B></P><P><B>Background</B>: Germ cells differentiate into oocytes in females and are arrested at the first meiotic prophase. However, during arrest, oocytes undergo a growth phase leading to a dramatic increase in size, which is under control of transcription events. In the current study, we examined the transcriptional activity of growing pig oocytes using an immunocytochemical approach. Our data showed that fluorouridine (FU), a halogenated nucleotide, can be successfully incorporated into synthesizing RNAs and detected using a specific monoclonal antibody. <B>Results</B>: Using this method, we identified dynamic changes in transcriptional activity patterns in growing pig oocytes. Oocytes obtained from small follicles exhibited the highest level of transcription, while at the final phase of growth, transcription was no longer detected. These transcriptional changes were concomitant with chromatin compaction resulting in a tightly packed ring‐like chromatin conformation surrounding the nucleolar structure. Also, FU incorporation appeared sensitive to the biochemical manipulation of transcription, because transcriptional inhibitors induced a decrease in signal intensity from FU labeling and transcriptional activation caused an increase in FU signal intensity. <B>Conclusions</B>: Our data collectively support that a direct link exists between chromatin configuration and transcriptional activity in pig oocytes, and support the suitability of FU for studies on transcription‐related events in mammalian oocytes. Developmental Dynamics 242:16–22, 2013. © 2012 Wiley Periodicals, Inc.</P>