• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1503-1507
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• 2013

The two major symptoms characterizing Alzheimer's disease are the formation of amyloid-${\beta}$ extracellular deposits in the form of senile plaques and intracellular neurofibrillary tangles (NFTs) that consist of pathological hyperphosphorylated tau protein aggregated into insoluble paired helical filaments (PHFs). Neurons of the central nervous system have appreciable amounts of tau protein, a microtubule-associated protein. To maintain an optimal operation of nerves, the microtubules are stabilized, which is necessary to support cell structure and cellular processes. When the modified tau protein becomes dysfunctional, the cells containing misfolded tau cannot maintain cell structure. One of the pathological hallmarks of Alzheimer's disease is hyperphosphorylated tau protein. This paper shows that the small heat shock protein from humans (Hsp27) reduces hyperphosphorylated tau and prevents hyperphosphorylated tau-induced cell death of the human neuroblastoma cell line SH-SY5Y.

• Clinical and Experimental Reproductive Medicine
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• v.38 no.1
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• pp.1-5
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• 2011

The maturation process of mammalian oocytes accompanies an extensive rearrangement of the cytoskeleton and associated proteins. As this process requires a delicate interplay between the cytoskeleton and its regulators, it is often targeted by various external and internal adversaries that affect the congression and/or segregation of chromosomes. Asymmetric cell division in oocytes also requires specific regulators of the cytoskeleton, including formin-2 and small GTPases. Recent literature providing clues regarding how actin filaments and microtubules interact during spindle migration in mouse oocytes are highlighted in this review.

• Applied Microscopy
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• v.28 no.2
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• pp.181-191
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• 1998

The spermatogenesis of pale chub (Zacco platypus) was investigated morphologically. The testis of pale chub contained numerous testicular sacs. These testicular sacs were bounded on neighboring sacs by single layer of squamous cells. Also, differentiated sperms were filled in the sacs. In the stage of spermatogonium, the germ cells had a large nucleus and a distinct nucleolus, and mitochondrial development was prominent. In the primary and secondary spermatogonia, these cells had a round electron-dense nucleus, reduced cytoplasm, and mitochondria were congregated in the side of cytoplasm. The highly condensed chromatin of sperms was electron-dense, the acrosome was not found in the head of the sperm and a motile flagellum consisted of an axoneme with a typical 9+2 pattern of microtubules.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.5 no.1
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• pp.61-68
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• 2019

Purine type compounds has been recently reported to cause the death for lung cancer cell, related to microtubules-targeting agents (MTAs). Therefore it can be used to develop as theranostic radiopharmceuticals in nuclear medicine or gadolinium-based MRI imaging agents by chelate chemistry. In the study, we tried to chemically bind a DOTA chelate on the end of purine compound and obtained a specific conjugate of DOTA-purine for metal coordination. In particular, radiometal like Cu-64, for the development of MRI imaging agents, can be utilized to choice good candidates before the synthesis of gadolinium complexes. By the screening of radioisotope technique, Gd-DOTA-purine type complex was successfully prepared and showed MRI imaging for lung cancer cell into the mouse model.

• Advances in nano research
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• v.15 no.1
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• pp.15-23
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• 2023

Dynamics of protein filamentous has been an active area of research since the last few decades as the role of cytoskeletal components, microtubules, intermediate filaments and microfilaments is very important in cell functions. During cell functions, these components undergo the deformations like bending, buckling and vibrations. In the present paper, bending and buckling of microfilaments are studied by using Euler Bernoulli beam theory with nonlocal parametric effects in conjunction. The obtained results show that the nonlocal parametric effects are not ignorable and the applications of nonlocal parameters well agree with the experimental verifications.

• Korean Journal of Ichthyology
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• v.18 no.4
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• pp.311-318
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• 2006

Ultrastructure of germ cells, the cyst epithelial cells and interstitial cells during spermatogenesis of the stone flounder, Kareius bicoloratus (Pleuronectidae) sampled on the west coast of Korea were investigated by electron microscopic observations. In the primary spermatocyte, the synaptonemal complexes appear in the zygotene stage of the prophase during maturation division. In the growing testis, especially, the interstitial cells (Leydig cells) appear near the primary, secondary spermatocytes and spermatids. Well-developed interstitial cells (steroid hormone secreting cells) which are located in the interlobular space in growing testis have three morphological characteristics of a vesicular nucleus, mitochondria with tubular cristae and smooth endoplasmic reticulum. During spermatogenesis, the primary and secondary spermatocytes attach to the cyst epithelial cell (Sertoli cell) having an elongated ovoid or triangular nucleus and several mitochondria in the cytoplasm. In the growing testis, lipid droplets, the mitochondrial rosettes and glycogen particles appear in the cytoplasm of the cyst epithelial cells near the secondary spermatocytes and spermatids. Particularly, the mitochondria, endoplasmic reticulum, little lipid droplets and the large amount of glycogen particles are present in the cytoplasm of the cyst epithelial cell in the late growing testis. In the late stage of spermiogenesis, the proximal centriole is joined to the nuclear envelope, the distal centriole forms the basal body of the flagellum and gives rise to the axial filament of the flagellum. No acrosome of the sperm is formed as seen in other teleost fish. The head of the spermatozoon is approximately $3{\mu}m$ in length and its tail is about $30{\mu}m$ in length. The axoneme of the tail flagellum of the spermatozoon consists of nine outer doublet microtubules at the periphery and two centrial singlet microtubules at the center. The spermatozoon of this species has two axonemal lateral fins. Especially, the cyst epithelial cells which located near groups of gametes in the various stages, show three functions: nutrition, phagocytosis and steroidogenesis. Especially, the nuclei of cyst epithelial cells in the recovery stage of the testicular developmental stages appear to be irregular in shape after spermiation. Of three functions of the cyst epithelial cell, several characteristics of phagocytosis are showed in the cytoplasm of the cyst epithelial cells in the recovery stage of the testicular developmental stages. At this stage, therefore, it is assumed that the cyst epithelial cells are involved in degeneration and resorption of undischarged germ cells after spermiation.

• Applied Microscopy
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• v.25 no.2
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• pp.39-52
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• 1995

Pinealocytes in the lower vertebrate are known to have photoreceptive function. These photoreceptor cells have been characterized morphologically in various species of lower vertebrates. No such ultrastructural studies, however, were reported in fresh water turtle. The purpose of this study is to characterize the pinealocytes and the phylogenetic evoluton of these cells is discussed in terms of functional analogy. I. Light microscopy: The pineal body was divided into incomplete lobules by connective tissue septa containing blood vessels, and parenchymal cells were arranged as irregular cords or follicular pattern. In the lobules, glandular lumina were present and contained often densely stained materials. II. Electron microscopy: The pineal parenchyma had three categories of cells: photoreceptor cells, supportive cells and nerve cells. The photoreceptor cells had darker cytoplasm compared to the supportive cells, and the enlarged apical cytoplasm(inner segment) containing abundant mitochondria and dense cored vescles protruded into the glandular lumen in which lamellar membrane stacks(outer segment), dense membranous materials, and cilia were present. Some of these lamellated membrane stacks appeared to be dege-nerating while others were apparently newly formed. Constricted neck portion of the photoreceptor cells contained longitudinally arranged abundant microtubules. centrioles and cross-striated rootlets. Cell body had well developed Golgi apparatus, abundant mitochondria, dense granules($0.5{\sim}1{\mu}m$), dense cored vesicles($70{\sim}100nm$), and rough endoplasmic reticulum occasionally with dense material within its cisterna. Basal portion of the photoreceptor cells had basal processes often with synaptic ribbons, which terminate in the complicated zone of cellular and neuronal processes. Synatpic ribbons often made contact with the nerve processes and the cell processes of neighboring cells. In some instances, these ribbons were noted free within the basal process and were also present at the basal cell mem-brane facing the basal lamina. Obvious nerve endings with clear and dense cored vesicles were observed among the parenchymal cells. Photoreceptor cells of the snapping turtle pineal body were generally similar in fine structure to those of other lower verterbrates reported previously, and suggested to have both photoreceptive and secretory functions which were modulated by pinealofugal and pinealopedal nerves. The supportive cells were characterized by having large dense granules($0.3{\sim}1{\mu}m$), abundant ribosomes, well developed Golgi apparatus and rough endoplasmic reticulum. These cells were furnished with microvilli on the luminal cell surfaces, and often had centrioles, striated rootlets, abundant filaments especially around the nucleus, and scattered microtubules. Some supportive cells had cell body close to the lumen and extended a long process reaching to basal lamina, which appeared to be a glial cell. Nerve cells within the parenchyma were difficult to identify, but some large cells located basally were suspected to be nerve cells, since they had synaptic ribbon contact with photoreceptor cells.

• Applied Microscopy
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• v.30 no.2
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• pp.121-139
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• 2000

The morphogenesis of neuroblasts and plexiform layers, and establishment of its synapses were studied by electron microscopy in human embryos and fetuses ranging from 10 mm to 260 mm crown-rump length ($5\sim30$ weeks of gestational age). At 30 mm fetus the developing retina was composed of outer and inner neuroblastic layers . Cell division of outer neuroblast was occurred until 90 mm fetus. The transient layer of Chievitz was formed by 30 mm fetus, inner plexiform layer by 50 mm fetus, and outer plexiform layer by 150 mm fetus. The cytoplasm of differentiating ganglion cells contained ribosomes, rough endoplasmic reticula, Golgi complexes, microtubules and dense bodies. The processes of $M\ddot{u}ller$ cell penetrated between groups of ganglion cell axons, and formed the cellular component of the inner limiting membrane at 30 mm fetus. At 90 mm fetus radial fibers of M ller cells contained extensive smooth endoplasmic reticula and microtubules. In each specimen , apposing paired membrane specializations were classified as junctions without synaptic vesicles, conventional synapses and ribbon synapses. At 50 mm fetus the processes of neuroblasts in inner plexiform layer were interconnected by junctions without synaptic vesicles. Conventional synapses developed by addition of synaptic vesicles to initially vesicle-free junctions at 90 mm fetus. At 150 mm fetus ribbon synapses were first recognized by the inclusion of a prominent electron-dense material associated with synaptic vesicles. By 260 mm fetus conventional and ribbon synapses and junctions without synaptic vesicles formed similar to those found in the adult.

• Journal of Life Science
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• v.27 no.6
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• pp.673-679
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• 2017

Microtubules are long rods in the cytoplasm of cells that plays a role in cell motility and intracellular transport. Microtubule-based transport by motor proteins is essential in intracellular transport. Kinesin 1 is a molecular motor protein that mediates the intracellular transport of various membranous vesicles, mRNAs, and proteins along microtubules. It is comprised of two heavy chains (KHCs, also called KIF5s) and two light chains (KLCs). KIF5s bear a motor domain in their amino (N)-terminal regions and interact with various cargoes through the cargo-binding domain in their carboxyl (C)-terminal regions. To identify proteins interacting with KIF5B, yeast two-hybrid screening was performed, and a specific interaction with the cytoplasmic linker protein 170 (CLIP-170), a plus end microtubule-binding protein, was found. The coiled-coil domain of CLIP-170 is essential for interactions with KIF5B in the yeast two-hybrid assay. CLIP-170 bound to the cargo-binding domain of KIF5B. Also, other KIF5s, KIF5A and KIF5C, interacted with CLIP-170 in the yeast two-hybrid assay. In addition, glutathione S-transferase (GST) pull-downs showed that KIF5s specifically interacted with CLIP-170. An antibody to KIF5B specifically co-immunoprecipitated CLIP-170 associated with KIF5B from mouse brain extracts. These results suggest that kinesin 1 motor protein may transport CLIP-170 in cells.

• Development and Reproduction
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• v.2 no.1
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• pp.101-109
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• 1998

Spermatogenesis and reproductive cycle of the razor clam, solen grandis, were investigated monthly by histological and cytological observations. Samples were collected from natural intertidal population at Oshik-do, Kunsan, Korea, for one year, beginning from January to December, 1993. solen grandis is dioecious. Morphological structures of the spermatozoon of this species ar esimilar to those of other bivalve spermatozoa having a primitive type; i.e., a small head, a cap-shaped acrosome and a short mid-piece with four mitochondria surrounding axial filament. The head of spermatozoon is approximately 2 \mu m in length and sperm tail is about 20 \mu m long. The axoneme of tail flagellum consists of nine pairs of peripheral microtubules at the periphery and a pair of central microtubules at the center. Four spherical mitochondria form the paranucleus. Spawning occures once a year between early June and July, and the main spawning was observed in July when seawater temperature reaches above 20 \circ C. The reproductive cycle of male razor clam can be divieded into fivesuccessive stages; early active (December to january), late active (January to march), mature (March to early August), partially spawned (June to July), and spent/inactive stage (August to December).