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91.
Ken-ichi Nakamura Naoshi Ishikawa Naotaka Izumiyama Junko Aida Mie Kuroiwa Naoki Hiraishi Mutsunori Fujiwara Atsushi Nakao Tadashi Kawakami Steven S.S. Poon Masaaki Matsuura Motoji Sawabe Tomio Arai Kaiyo Takubo 《Gene》2014
Trisomies 18 and 21 are genetic disorders in which cells possess an extra copy of each of the relevant chromosomes. Individuals with these disorders who survive birth generally have a shortened life expectancy. As telomeres are known to play an important role in the maintenance of genomic integrity by protecting the chromosomal ends, we conducted a study to determine whether there are differences in telomere length at birth between individuals with trisomy and diploidy, and between trisomic chromosomes and normal chromosomes. We examined samples of peripheral blood lymphocytes (PBLs) from 31 live neonates (diploidy: 10, trisomy 18: 10, trisomy 21: 11) and estimated the telomere length of each chromosome arm using Q-FISH. We observed that the telomeres of trisomic chromosomes were neither shorter nor longer than the mean telomere length of chromosomes as a whole among subjects with trisomies 18 and 21 (intra-cell comparison), and we were unable to conclude that there were differences in telomere length between 18 trisomy and diploid subjects, or between 21 trisomy and diploid subjects (inter-individual comparison). Although it has been reported that telomeres are shorter in older individuals with trisomy 21 and show accelerated telomere shortening with age, our data suggest that patients with trisomies 18 and 21 may have comparably sized telomeres. Therefore, it would be advisable for them to avoid lifestyle habits and characteristics such as obesity, cigarette smoking, chronic stress, and alcohol intake, which lead to marked telomere shortening. 相似文献
92.
Summary In several cell types, an intriguing correlation exists between the position of the centrosome and the direction of cell locomotion. The centrosome is positioned between the leading edge pseudopod and the nucleus. This suggests that the polarized distribution of organelles in the cytoplasm is coupled spatially with structural and functional polarity in the cell cortex. To study cellular polarization with special interest in the roles of microtubules, we have analyzed the effects of microtubule-disrupting reagents and local laser irradiation on behaviors of both the nucleus and the centrosome in living amoebae ofPhysarum polycephalum. Physarum cells often have 2–3 pseudopods. One of the pseudopods keeps extending to become a stable leading edge while the rest retracts, a crucial step that reorients cells during locomotion. The nucleus, together with the centrosome, moves specifically toward the pseudopod that will become the leading edge. Disruption of microtubules with nocodazole randomizes positions of the nucleus, indicating the involvement of microtubules in the directional migration of the nucleus toward a specific pseudopod. The migration direction of the nucleus is reversed immediately after the UV laser is irradiated at regions between the nucleus and the future leading pseudopod. In contrast, irradiation at regions between the future tail and the nucleus does not affect nuclear migration. By immunofluorescence, we confirmed fragmentation of microtubules specifically in the irradiated region. These results suggest that the nucleus is pulled together with the centrosome toward the future leading-edge pseudopod in a microtubule-dependent manner. Microtubules seem to exert the pulling force generated in the cell cortex on the centrosome. They may serve as a mediator of shape changes initiated in the cell cortex to the organelle geometry in the endoplasm. 相似文献
93.
BTG/tob family proteins are thought to be a potential tumor suppressor due to their anti-proliferative activity. We cloned zebrafish btg-b, a member of the BTG1/2 subfamily, using in situ hybridization screening. The tissue-specific expression of btg-b is first observed in the organizer region at the early gastrula stage. Later in development, the forebrain, the hindbrain, the polster and the paraxial mesoderm transiently express btg-b. Recently, mouse Btg1 and Btg2 have been shown to be a cofactor for Hoxb9. Double in situ hybridization with zebrafish btg-b and hoxb9a indicates that the expression domains of these two genes overlap in the posterior paraxial mesoderm. 相似文献
94.
The courses of rRNA accumulation, DNA replication, and nuclear division were followed both in the chloroplast and the nucleocytosolic compartments during the cell cycle in synchronized populations of the chlorococcal alga Scenedesmus quadricauda. Control and nalidixic acid-treated cultures were compared. Nalidixic acid (150 mg/L) was added either at the beginning of the cell cycle or consecutively during the cell cycle to subcultures transferred into the dark. If the inhibitor was applied at the beginning of the cell cycle, chloroplast DNA did not replicate and nucleoids did not divide. Chloroplast division, however, was coordinated in a timely fashion with cytokinesis even under conditions of blocked chloroplast DNA replication. While the growth rate was slowed down, the courses of reproductive processes in the nucleocytosolic compartment were not affected and their timing and the number of rounds were coordinated with growth rate as in the control culture. The rate of cytosolic rRNA synthesis was lower but no apparent effect was seen on the amount of rRNA that accumulated during the cell cycle. In contrast, lower levels of chloroplast rRNA were found at the end of the cell cycle compared with the control culture. Experiments in which cells were transferred to the dark during the cell cycle showed that the inhibitor affected none of the reproductive events in the nucleocytosolic compartment. In the chloroplast compartment, DNA replication was inhibited in inhibitor-treated cultures, but was unaffected in controls. The chloroplast nucleoids themselves divided even in the presence of the inhibitor, reducing their DNA content to a level which corresponded to that in freshly formed control daughter cells. 相似文献
95.
A Kuroiwa K Matsubara T Nagase N Nomura J K Seong A Ishikawa R V Anunciado K Tanaka T Yamagata J S Masangkay V B Dang T Namikawa Y Matsuda 《The Journal of heredity》2001,92(3):282-287
The direct R-banding fluorescence in situ hybridization (FISH) method was used to map 18S-28S ribosomal RNA genes and 10 human cDNA clones on the chromosomes of the musk shrew (Suncus murinus). The chromosomal locations of 18S-28S ribosomal RNA genes were examined in the five laboratory lines and wild animals captured in the Philippines and Vietnam, and the genes were found on chromosomes 5, 6, 9, and 13 with geographic variation. The comparative mapping of 10 cDNA clones of human chromosome 1 demonstrated that human chromosome 1 consisted of at least three segments homologous to Suncus chromosomes (chromosomes 7, 10, and 14). This approach with the direct R-banding FISH method is useful for constructing comparative maps between human and insectivore species and for explicating the process of chromosomal rearrangements during the evolution of mammals. 相似文献
96.
The digestive tract exhibits region-specific morphology and cytodifferentiation along the anteroposterior axis. We analyzed the spatial expression patterns of Hox genes belonging to the HoxA and HoxB cluster (Hoxa-4 approximately a-9, Hoxb-5 approximately b-9) in the developing chick digestive tract. The expression domains of these Hox genes correlated with morphological subdivision of the digestive tract along the anteroposterior axis. 相似文献
97.
Summary We characterized the behavior of plastid (pt) and mitochondrial (mt) nucleoids during malegametogenesis inPlumbago auriculata in three dimensions. The behavior of pt-nucleoids and mt-nucleoids differed throughout male gametogenesis.Pt-nucleoids were
distibuted in a characteristic manner in three stages: in the early microspore, pt-nucleoids assemble around cell nucleus:
in the mid-generative cell,pt-nucleoids gather at the internal side of the pollen: in the late-generative cell, pt-nucleoids
aggregation turns its pole to the external side of the pollen. We also studied organelle nucleoids in the egg and the central
cell by a method in which semi-thick sections of resin-embedded anthers and ovaries were observed by confocal laser scanning
microscopy. The number of pt-nucleoids in the sperm cell did not differ significantly from that the behavior of DNA-containing
organelles is regulated strictly during male gametogenes inP. auriculata, and that a biparental inheritance of plastids in the Plumbago embryo is more favored than was previously thought. 相似文献
98.
Detection and characterization of a plastid envelope DNA-binding protein which may anchor plastid nucleoids. 总被引:6,自引:0,他引:6 下载免费PDF全文
Chloroplast DNA (cpDNA) binds to the envelope membrane of actively dividing chloroplasts (plastids) in young pea leaves. South-western blotting was used to identify and characterize the protein involved in the binding of cpDNA to the envelope membrane. A 130 kDa protein in the inner chloroplast (plastid) envelope membrane binds specific sequences within the cpDNA. These included a 0.41 kbp sequence located upstream of the psaAB gene, a 0.57 kbp sequence located downstream of the petA gene and a 1.2 kbp sequence located within the rpoC2 gene. The protein was detected in the envelope membrane of young pea leaves in which the cpDNA had been located by fluorescence microscopy at the chloroplast periphery, whereas it was undetectable in mature leaves. We therefore propose that the 130 kDa protein is involved in the binding of cpDNA to the envelope membrane, and named it plastid envelope DNA-binding protein. 相似文献
99.
Hydrolysis of galactosylceramide is catalyzed by two genetically distinct acid beta-galactosidases 总被引:2,自引:0,他引:2
T Kobayashi N Shinnoh I Goto Y Kuroiwa 《The Journal of biological chemistry》1985,260(28):14982-14987
Two genetically distinct acid beta-galactosidases are apparently involved in the hydrolysis of galactosylceramide in fibroblasts. These beta-galactosidases were activated by different bile salts. The classical galactosylceramidase (galactosylceramidase I, EC 3.2.1.46) was activated by sodium taurocholate, while the other galactosylceramidase (galactosylceramidase II) was activated by sodium cholate. The former was genetically lacking in globoid cell leukodystrophy (GLD) and the latter in GM1 gangliosidosis. Galactosylceramidase II cross-reacted with antibody raised against purified GM1 ganglioside beta-galactosidase (EC 3.2.1.23) from the human placenta. The purified beta-galactosidase had galactosylceramidase II activity, which was competitively inhibited by GM1 ganglioside. Thus, galactosylceramidase II seems to be identical to GM1 ganglioside beta-galactosidase and lactosylceramidase II. Galactosylceramidase II had a very low affinity for galactosylsphingosine. In the galactosylceramide-loading tests using fibroblasts from patients with GLD and GM1 gangliosidosis, both cell lines hydrolyzed the incorporated galactosylceramide, with lower rates than control fibroblasts but higher than the fibroblasts from patients with I-cell disease, in which both galactosylceramidase I and II were deficient. These results indicate that galactosylceramide is hydrolyzed by two genetically distinct beta-galactosidases and explain well that galactosylsphingosine but not galactosylceramide accumulates in the brain of patients with GLD. 相似文献
100.
Multiplication and Differentiation of Plastid Nucleoids during Development of Chloroplasts and Etioplasts from Proplastids in Triticum aestivum 总被引:2,自引:0,他引:2
The morphological changes of plastid nucleoids (pt nucleoids)in the shoot apex and along the axis of the leaf blade in Triticumaestivum L. cv. Asakaze were followed with fluorescence microscopyafter staining with 4'6-diamidino-2-phenylindole (DAPI) andquantified with supersensitive microspectrophotometry. Proplastidsin the shoot apex contained 110 spherical pt nucleoids.These pt nucleoids changed to a row of spherical and cup-shapedpt nucleoids in sausage-shaped plastids at the leaf base inboth dark and light conditions, in which active cell divisionwas observed. These structures have a higher copy number ofplastid DNA (pt DNA) (7278 copies) compared to proplastidsin the shoot apex (3245 copies) and, therefore, may reflectthat active pt DNA synthesis is in progression. In the dark,the cup-shaped pt nucleoids in the spherical etioplasts, whichoriginated from the sausage-shaped plastids, grew to form ring-shapedpt nucleoids. Each ring-shaped pt nucleoid is sub-divided intosmaller pt nucleoids. Under continuous illumination, similarmorphological changes of pt nucleoids occurred except for distributionof small pt nucleoids into young chloroplasts as well as inmature chloroplasts. However, pt nucleotids of leucoplasts inepidermal and vascular bundle sheath cells did not show conspicuouschanges along the axis of the leaf blade. The significance ofthese observations is discussed in relation to plastid differentiationand to the plastid division cycle.
4 Present address: Faculty of Science, University of Tokyo,Hongo, Bunkyo-ku, Tokyo, 113 (Received August 15, 1989; Accepted April 13, 1990) 相似文献