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51.
Kazuo Ohtsuka Katsuhiko Hasegawa Kazunari Sato Katsumitsu Arai Hisami Watanabe Hitoshi Asakura Toru Abo 《Microbiology and immunology》1994,38(8):677-683
Two major populations of extrathymically differentiated T cells exist in the liver and intestine. Such T cells in the liver have TCR of intermediate intensity (i.e., intermediate TCR cells) and constitutively express IL-2 receptor β-chain (IL-2Rβ), whereas those in the intestine, especially intraepithelial lymphocytes, have TCR of bright intensity, consisting of a mixture of IL-2Rβ+ and IL-2Rβ–. All mature thymocytes and thymus-derived T cells seen in the peripheral immune organs are TCR-bright+IL-2Rβ– under resting conditions. When the expression pattern of adhesion molecules, including CD44, L-selectin, LFA-1 and ICAM-1, was compared among these T-cell populations, they displayed quite unique patterns of expression. All extrathymic T cells in the liver, intestine, and even other organs were CD44+L-selectin– LFA-1++ICAM-1+, whereas thymocytes and thymus-derived T cells were CD44– L-selectin+LFA-1+ICAM-1–. This inverted expression of adhesion molecules between extrathymic T cells and thymus-derived T cells might be associated with their unique tissue-localization. 相似文献
52.
Globular proteins have high packing densities as a result of residue side chains in the core achieving a tight, complementary packing. The internal packing is considered the main determinant of native protein structure. From that point of view, we present here a method of energy minimization using an automata network to predict a set of amino acid sequences and their side-chain conformations from a desired backbone geometry for de novo design of proteins. Using discrete side-chain conformations, that is, rotamers, the sequence generation problem from a given backbone geometry becomes one of combinatorial problems. We focused on the residues composing the interior core region and predicted a set of amino acid Sequences and their side-chain conformations only from a given backbone geometry. The kinds of residues were restricted to six hydrophobic amino acids (Ala, Ile, Met, Leu, Phe, and Val) because the core regions are almost always composed of hydrophobic residues. The obtained sequences were well packed as was the native sequence. The method can be used for automated sequence generation in the de novo design of proteins. © 1994 Wiley-Liss, Inc. 相似文献
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54.
Atsushi Hashimoto † Shin Kumashiro † Toru Nishikawa † Takae Oka † Kiyohisa Takahashi † Takashi Mito ‡ Sachio Takashima ‡ Nagafumi Doi § Yoshihiko Mizutani Tatsuji Yamazaki Tsuguo Kaneko Eiji Ootomo# 《Journal of neurochemistry》1993,61(1):348-351
Abstract: We have analyzed free chiral amino acids (aspartate and serine) in the human frontal cortex at different ontogenic stages (from 14 weeks of gestation to 101 years of age) by HPLC with fluorometric detection after derivatization with N-tert -butyl-oxycarbonyl- l -cysteine and o -phthaldialdehyde. Exceptionally high levels of free d -aspartate and d -serine were demonstrated in the fetal cortex at gestational week 14. The ratios of d -aspartate and of d -serine to the total corresponding amino acids were also high, at 0.63 and 0.27, respectively. The concentration of d -aspartate dramatically decreased to a trace level by gestational week 41 and then remained very low during all postnatal stages. In contrast, the frontal tip contained persistently high levels of d -serine throughout embryonic and postnatal life, whereas the d -amino acid content in adolescents and aged individuals was about half of that in the fetuses. Because d -aspartate and d -serine are known to have selective actions at the NMDA-type excitatory amino acid receptor, the present data suggest that these d -amino acids might play a pivotal role in cerebral development and functions that are related to the NMDA receptor. 相似文献
55.
The molecular events associated with decondensation of human sperm nuclei were analyzed by incubating sperm with egg extracts from an amphibian, Bufo japonicus . Acid-urea-Triton polyacrylamide gel electrophoresis (AUT-PAGE) showed that the nuclear basic proteins of human sperm consist mainly of protamines (HPI, HPII) with minor amounts of nucleosomal histones. On incubation of lysolecithin (LC)- and dithiothreitol (DTT)-treated human sperm with the egg extract, the nuclei lost HPI and HPII within 15 min in association with extensive nuclear decondensation, and the acquirement of a whole set of nucleosomal histones. Incubation of LC-DTT-sperm with nucleoplasmin purified from Bufo eggs also induced nuclear decondensation and loss of protamines within 30 min. Native-PAGE and Western blot analyses of incubation medium indicated tight association of the released protamines to nucleoplasmin, strongly suggesting that protamines are removed from sperm nuclei not enzymatically but by their specific binding to nucleoplasmin. On incubation of LC-DTT-sperm with nucleoplasmin and exogenous nucleosomal core histones, micrococcal nuclease-protected DNA fragments were released, although their unit repeat length was slightly less than that of somatic nucleosomes. Thus remodeling of human sperm during fertilization can be mimicked under defined conditions with nucleoplasmin and exogenous histones. 相似文献
56.
Mitsutoshi Kato Jie Yang Takaaki Iwai Akira Tanamura Toru Arino Osamu Kawashima Nobuakira Takeda 《Molecular and cellular biochemistry》1993,119(1-2):89-94
ADP/ATP carrier protein (AAC) is located in the mitochondrial inner membrane and has an important function in mitochondrial energy supply. This protein transports ATP to the cytoplasm and counter transports ADP into the mitochondria. J-2-N cardiomyopathic hamsters were investigated to determine the AAC content in cardiac mitochondria. After recording an electrocardiogram and collecting blood, the cardiac mitochondria were isolated. The mitochondrial membranes were labelled with eosin-5-maleimide (EMA) and separated on SDS polyacrylamide gels. The position of the AAC component was identified by exposing the gel under UV light, and the AAC content was determined by densitometry after staining with Coomassie blue. The AAC content ratio was significantly decreased in both 10-week-old and 1-year survived J-2-N hamsters when compared to control Golden hamster. Among 10-week-old J-2-N hamsters, the decrease in the AAC content ratio was more marked for the animals with more severe myocardial damage. The H+-ATPase activities of mitochondrial membrane were higher in 10-week-old J-2-N hamsters than in control hamsters. These results suggest that the decrease of AAC in J-2-N hamster plays an important role in the pathogenesis of cardiomyopathy in J-2-N hamsters. 相似文献
57.
Tobacco plants were transformed with derivatives of a binary vector pMON505 and two kanamycin resistant lines that were nopaline positive were selected for second transformation. The plasmids used for the second transformation were derivatives of pMON850 which carries the nopaline synthase gene in addition to a gene for gentamicin resistance. Insertion of each transgene was confirmed by Southern hybridization. Surprisingly, we found that more than 50% of the doubly transformed tobacco plants were nopaline negative. Tobacco plants that were transformed only by the second vector exhibited nopaline accumulation. DNA methylation patterns at the HpaII site in the promoter region of the nopaline synthase gene did not correlate with the nopaline phenotype. In some plant lines, seedlings of the R1 generation which segregated out the second T-DNA insertion recovered the nop+ phenotype. These results indicate that nopaline accumulation was inhibited by the presence of the second T-DNA.Abbreviations T-DNA
transferred DNA
- NPTII
neomycin phosphotransferase II
-
uidA
-glucuronidase
- Km
kanamycin
- Gm
gentamicin
- nop+
nopaline positive
- nop–
nopaline negative
- MS
medium, Murashige-Skoog medium 相似文献
58.
Toru Terachi 《Journal of plant research》1993,106(1):75-79
Recent advances in manipulating nucleic acids have opened a new research field called plant molecular systematics. This short
review provides an overview of molecular techniques which have been used in the analysis of DNA molecules for the study of
plant systematics, with a special emphasis on PCR. The early application of DNA analysis, DNA/DNA hybridization, has not become
popular with plant systematists, because of several disadvantages inherent in the method. The survey of restriction fragment
length polymorphisms (RFLPs), on the contrary, has become one of the preferred methods used by plant molecular systematists,
since the method is relatively easy to perform. Although unambiguous data can be obtained by both long-range restriction mapping
and nucleotide sequencing, these approaches may have limited use in plant molecular systematics because of their laborious
experimental procedures relying on conventional molecular cloning techniques. To date, PCR based analyses of the DNA molecule
seem to be the most suitable experimental approach for plant molecular systematics. Several advantages of the method have
changed both the quality and quantity of the DNA data. Further application of PCR to plant molecular systematics will open
up a new era in the field.
The present paper is based on the contribution which was read in a symposium entitled “Organellar DNA Variations in Higher
Plants and their Taxonomic Significance”, at the 50th Annual Meeting of the Botanical Society of Japan in Shizuoka on October
2, 1990, under the auspices of the Japan Society of Plant Taxonomists. 相似文献
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