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991.
The configurations of (6′R)-β,ε-carotene, (3′R,6′R)-β,ε-caroten-3′-ol (α-cryptoxanthin), (3R,3′R,6′R)-β,ε-carotene-3,3′-diol (lutein), (3R)-β,β-caroten-3-ol (β-cryptoxanthin), (3R,3′R)-β,β-carotene-3,3′-diol (zeaxanthin) and all-trans (3S,5R,6S,3′R)-5,6-epoxy-5,6-dihydro-β,β-carotene-3,3′-diol (antheraxanthin) were established by CD and 1H NMR studies. The red algal carotenoids consequently possessed chiralities at each chiral center (C-3, C-5, C-6, C-3′, C-6′), corresponding to the chiralities established for the same carotenoids in higher plants. Two post mortem artifacts from Erythrotrichia carnea were assigned the chiral structures (3S,5R,8R,3′R)-5,8-epoxy-5,8-dihydro-β,β-carotene-3,3′-diol [(8R)-mutatoxanthin] and (3S,5R,8S,3′R)-5,8-epoxy-5,8-dihydro-β,β-carotene-3,3′-diol [(8S)-mutatoxanthin]. This is the first well documented report of a naturally occurring β,ε-caroten-3′-ol (1H NMR, CD, chemical derivatization). 相似文献
992.
CD72是一个重要的B细胞特异性受体,它以多种选择性剪切形式存在.在小鼠脾细胞中发现并鉴定了8种新的CD72选择性剪切形式,这些剪切形式中包含有2种独特的插入片段,一种选择性剪切保留了一个内含子(intron1),而这个内含子被翻译成氨基酸序列后并没有改变前后外显子的读码框,另一种使用了一个位于内含子之内的3′剪切位点,从而产生移码,提前终止了蛋白质的开放读码框,称为3′AS(3′alternative splicingsite).比较了CD72所有剪切形式在BALB/C小鼠和NZB/W小鼠中的差异表达,发现:a.含有3′AS的剪切形式的表达都很少;b.WT, In1, In1-Ex3和-Ex3的表达在BLAB/C小鼠中比在NZB/W小鼠中高;c.没有ITIM2的-Ex2-Ex3剪切形式在NZB/W小鼠中有特异性高表达.这些结果提示,CD72的多种选择性剪切形式在调控B细胞受体信号转导过程中可能发挥着不同的作用,并与系统性红斑狼疮的发病密切相关. 相似文献
993.
Motomu Shimizu Yasutaka Takeda Hideo Yagita Takayuki Yoshimoto Akio Matsuzawa 《Cancer immunology, immunotherapy : CII》1998,47(3):143-148
Lymph node (LN) cells of Fas-mutant mice lpr/lpr (lpr) and lpr
cg
/lpr
cg
(lpr
cg
) express an increased level of Fas ligand (FasL) (CD95L). We examined the antitumor potential of cell-bound FasL on these
LN cells against Fas+ tumor cells. Fas+ F6b and Fas− N1d cells were produced from murine hepatoma MH134 (Fas−) by gene transfection. lpr and lpr
cg
LN cells inhibited growth of F6b but not N1d cells in vitro. Neither gld/gld lpr/lpr (gld/lpr) LN cells, which lack both FasL and Fas, nor wild-type LN cells showed growth-inhibitory activities against F6b and N1d cells.
The effector cells and molecule were CD4−CD8− T cells and FasL, respectively. The tumor neutralization test and adoptive transfer demonstrated that lpr and lpr
cg
, but not gld/lpr, LN cells retarded the growth of F6b cells. Although anti-Fas antibody and FasL cause severe liver failure, wild-type mice
injected with lpr LN cells appeared clinically normal. Adoptive transfer of lpr LN cells to F6b-bearing mice exerted the same antitumor activity in wild-type and gld/lpr recipient mice, indicating the applicability of cell-bound FasL for Fas-mediated target therapy of cancer. These results
suggest that antitumor activity was dependent on the Fas-FasL system and that lymphoid cells overexpressing FasL can be powerful
antitumor effector cells against Fas+ tumor cells.
Received: 16 March 1998 / Accepted: 28 July 1998 相似文献
994.
K. Tanaka Akira Yamada Kiyoshi Noda Takashi Hasegawa Masao Okuda Yukihiro Shoyama Kikuo Nomoto 《Cancer immunology, immunotherapy : CII》1998,45(6):313-320
A glycoprotein extract (CVS), derived from the unicellular green alga Chlorella vulgaris, strain CK22, exhibited a pronounced antitumor effect against both spontaneous and experimentally induced metastasis in mice.
Inhibition of tumor metastasis was enhanced when intratumor administration of CVS was followed by s.c. injection of CVS. Anti-metastatic
immunopotentiation was observed in euthymic mice, but not in athymic nude mice. The antitumor activity of CVS was reflected
in antigen-specific, T-cell-mediated immunity. Both CD4 and CD8 T cells contributed to the antimetastatic effects, as shown
by in vivo depletion experiments with anti-T-cell subset antibodies. Furthermore, CVS caused the recruitment of T cells to
the regional lymph nodes and their proliferation in these organs. The CD4-positive population, following CVS injection at
the time of tumor rechallenge, displayed a pronounced increase in the proportion of T cells that were CD18 bright, CD44 bright,
CD25+, CD54+, CD69+ or CD71+ in the lymph nodes. Thus, CVS induces T cell activation in peripheral lymph nodes in tumor-bearing mice. We conclude that
CVS augments antimetastatic immunity through T cell activation in lymphoid organs and enhances recruitment of these cells
to the tumor sites. Presurgical treatment with CVS might prevent metastasis or tumor progression.
Received: 5 June 1997 / Accepted: 12 September 1997 相似文献
995.
Junji Sagara Tadafumi S. Tochikura Hajime Tanaka Yoshihiro Baba Shoichiro Tsukita Sachiko Tsukita Akihiko Kawai 《Microbiology and immunology》1998,42(4):289-297
In our monoclonal antibody (MAb) stocks prepared against the BHK-21 cell antigens, two (#11875 and 28276) recognized a 21-kDa polypeptide (referred to as VAP21) which is efficiently incorporated into the rabies virion. By using these MAbs, we isolated the cDNA clones that encoded a polypeptide of 144 amino acids from our BHK-21 cell cDNA library. Based on the following evidence, the cDNA was assumed to encode a full-length sequence of VAP21 antigen: i) expression of the cDNA in animal cells resulted in the production of a polypeptide recognized by the two MAbs, and its electrophoretic mobility was the same as that of authentic VAP21 antigen; and ii) immunization with the products from the cDNA-transformed E. coli cells raised specific antibodies in rabbits that recognized a 21-kDa polypeptide in the virion. From the deduced amino acid sequence, it is suggested that the VAP21 antigen has a molecular structure of type-I transmembrane protein containing characteristic proline-rich and glycine-rich regions in its ectodomain. Homology searches resulted in finding homologous sequences (totally about 40% homology) in the human MIC2 gene product (CD99; 32-kDa) of T lymphocytes. These results suggest that the VAP21 antigen in the rabies virion is a cellular CD99-related transmembrane protein. 相似文献
996.
Molecular structure of malate synthase and structural changes upon ligand binding to the enzyme 总被引:2,自引:0,他引:2
G Schmid H Durchschlag G Biedermann H Eggerer R Jaenicke 《Biochemical and biophysical research communications》1974,58(2):419-426
Malate synthase has a molecular weight of about 170 000 as shown by ultracentrifugation, sucrose gradient centrifugation, and thin layer gel-chromatography. High dilution, extremes of pH, succinylation, and treatment with sodium dodecylsulfate suggest the enzyme to be a tetramer. The CD spectrum is typical for a globular protein with moderate helical content (~30 %), and shows anomalous Cotton effects at 250–290 nm. Binding of substrates (acetyl-CoA, glyoxylate) or the substrate analog pyruvate causes slight conformational changes which are reflected in alterations of the CD bands in the range of aromatic absorption; binding of Mg2+ causes no structural effects, suggesting the metal ion to be involved in enzymatic catalysis rather than structural alterations. 相似文献
997.
In order to determine the effects of chronic exercise on the kidneys at different ages, young, adult, and old rats swam 1 hour either daily or twice a week for 10 weeks and then were killed along with unexercised controls. The kidneys were removed and sections were prepared for histometric analysis including planimetric measurements on camera lucida drawings of renal components and line sampling. With both degrees of exercise young rats showed lower kidney weight, fewer glomeruli and less medullary tissue than unexercised controls. In the adult group no significant differences were noted between exercised and unexercised rats. In old rats both degrees of exercise resulted in a loss of kidney weight and medullary and cortical mass, and a decrease in size of glomeruli while total number of glomeruli remained unchanged. Thus the effects of chronic exercise on the kidneys varied with age. Retarded kidney development occurred in young animals; a loss of renal tissue in old animals; and no change in adult animals. 相似文献
998.
The B to A transition of DNA in solution 总被引:31,自引:0,他引:31
999.
Yuko Kawabata Fuminori Kawabata Shotaro Nishimura Shoji Tabata 《Biochemical and biophysical research communications》2018,495(1):131-135
It has been reported that a functional fat-taste receptor, GPR120, is present in chicken oral tissues, and that chickens can detect fat taste in a behavioral test. However, although triglycerides need to be digested to free fatty acids to be recognized by fat-taste receptors such as GPR120, it remains unknown whether lipase activities exist in chicken oral tissues. To examine this question, we first cloned another fat-taste receptor candidate gene, CD36, from the chicken palate. Then, using RT-PCR, we determined that GPR120 and CD36 were broadly expressed in chicken oral and gastrointestinal tissues. Also by RT-PCR, we confirmed that several lipase genes were expressed in both oral and gastrointestinal tissues. Finally, we analyzed the lipase activities of oral tissues by using a fluorogenic triglyceride analog as a lipase substrate. We found there are functional lipases in oral tissues as well as in the stomach and pancreas. These results suggested that chickens have a basic fat-taste reception system that incorporates a triglycerides/oral-lipases/free fatty acids/GPR120 axis and CD36 axis. 相似文献
1000.
Jennifer Morton Maria Chrysina Vincent S.J. Craig Fusamichi Akita Yoshiki Nakajima Wolfgang Lubitz Nicholas Cox Jian-Ren Shen Elmars Krausz 《BBA》2018,1859(2):88-98
Photosystem II passes through four metastable S-states in catalysing light-driven water oxidation. Variable temperature variable field (VTVH) Magnetic Circular Dichroism (MCD) spectra in PSII of Thermosynochococcus (T.) vulcanus for each S-state are reported. These spectra, along with assignments, provide a new window into the electronic and magnetic structure of Mn4CaO5. VTVH MCD spectra taken in the S2 state provide a clear g = 2, S = 1/2 paramagnetic characteristic, which is entirely consistent with that known by EPR. The three features, seen as positive (+) at 749 nm, negative (?) at 773 nm and (+) at 808 nm are assigned as 4A → 2E spin-flips within the d3 configuration of the Mn(IV) centres present. This assignment is supported by comparison(s) to spin-flips seen in a range of Mn(IV) materials. S3 exhibits a more intense (?) MCD peak at 764 nm and has a stronger MCD saturation characteristic. This S3 MCD saturation behaviour can be accurately modelled using parameters taken directly from analyses of EPR spectra. We see no evidence for Mn(III) d-d absorption in the near-IR of any S-state. We suggest that Mn(IV)-based absorption may be responsible for the well-known near-IR induced changes induced in S2 EPR spectra of T. vulcanus and not Mn(III)-based, as has been commonly assumed. Through an analysis of the nephelauxetic effect, the excitation energy of S-state dependent spin-flips seen may help identify coordination characteristics and changes at each Mn(IV). A prospectus as to what more detailed S-state dependent MCD studies promise to achieve is outlined. 相似文献