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81.
82.
From ligulate flowers of Matricaria chamomilla was isolated a mixture of apigenin 7-O-β-glucoside diacetates, which was shown to be based on (2″, 3″)- and (3″, 4″)-diacetates. 相似文献
83.
L. Rodrigues de Miranda 《Antonie van Leeuwenhoek》1979,45(3):479-483
In Candida lusitaniae van Uden et do Carmo-Sousa (1959), strains of opposite sex have been found. Cells of the opposite mating types conjugate and form asci with one to four clavate spores. These are easily liberated from the ascus. The type strain of Candida obtusa (Dietrichson) van Uden et do Carmo-Sousa ex van Uden et Buckley (1970) also produces ascospores after mating with one of the strains of Candida lusitaniae. As clavate ascospores are unknow in yeasts, a new genus, Clavispora, is proposed with Clavispora lusitaniae spec. nov. as type species. 相似文献
84.
Ettore Benedetti Benedetto Di Blasio Vincenzo Pavone Carlo Pedone Claudio Toniolo Gian Maria Bonora 《International journal of biological macromolecules》1980,2(4):217-224
The X-ray diffraction and i.r. absorption conformational analysis of has showed the absence of intramolecularly hydrogen-bonded peptide conformations in the solid state. The molecules are held together in rows of ‘cyclic dimer’ motifs through intermolecular NH … OC (acid) and OH … OC {urethane} hydrogen bonds, the secondary amide-like group of the urethane moiety being in the unusual cis conformation, whereas the carboxylic acid group in the common syn conformation. The two molecules in the unit cell present a centrosymmetric set of ?, ψ1, and ψ2 values. In polar solvents solvated species largely predominate. In saturated hydrocarbon solution non-associated and associated (mostly involving the carboxylic acid CO as the proton acceptor) species simultaneously occur. The extent of association decreases with dilution. The amount of intramolecularly hydrogen-bonded oxy-C7 and C5 forms if any, should be extremely small. The type of association at saturation seems to differ from that found in the crystalline compound obtained by precipitation with saturated aliphatic hydrocarbons (from a diethyl ether solution). 相似文献
85.
Elisabetta Colletti Laura Frontali Claudio Palleschi Micheline Wesolowski Hiroshi Fukuhara 《Molecular & general genetics : MGG》1979,175(1):1-4
Summary In S. cerevisiae four isoacceptor mitochondrial tRNAs for serine have been separated by reversed phase chromatography. At least two of these species are products of different genes. In this work the deletion mapping technique has been used to locate two genes for tRNAser. The gene for tRNAser previously localized in the oli I region of the mitochondrial genome has been found to code for tRNA
ser
2
, and another gene coding for tRNA
ser
1
has been detected in the region where most of other tRNA genes are found. Results of fine mapping experiments allowed to localize this gene in the proximity of the gene for tRNAarg. 相似文献
86.
87.
A temperature-sensitive mutant of BHK, designated is BN-2, shows a rapid drop in 3H-thymidine incorporation along with accumulation of the cells in the G1 phase of the cycle when asynchronous cultures are shifted from 33.5°C to the nonpermissive temperature of 39.5°C. Synchronized cultures of ts BN-2 cells did not enter DNA synthesis when shifted up in G1. Shift-up of cultures at the beginning of the S phase resulted in an approximately normal rate of DNA synthesis for about 2 hr. The rate of DNA synthesis then quickly declined, and the cells became arrested in mid-S after completion of approximately 0.5 rounds of DNA replication. At the same time, the majority of the cells were observed to lose the nuclear membrane and displayed premature chromosome condensation. These events were followed by the appearance of cells containing several micronuclei and eventual cell disruption and death. The nonpermissive temperature appeared to have no effect on either the elongation of short fragments of DNA or the execution of mitosis after the completion of the S phase under permissive conditions. The ts defect in this mutant may directly limit the initiation of DNA synthesis or alter the regulation of chromatin condensation. 相似文献
88.
Giancarlo Lunazzi Claudio Tiribelli Bruno Gazzin Gianluigi Sottocasa 《生物化学与生物物理学报:生物膜》1982,685(2):117-122
Bilitranslocase, a plasma membrane protein involved in bilirubin and other organic anion uptake by the liver, exhibits a high molecular weight (170 000) when isolated in the presence of deoxycholate. This value is decreased to approx. 100 000 if deoxycholate is not included in the isolation medium. Both preparations can be resolved into two kinds of subunit, α and β, of 37 000 and 35 500, respectively, by reduction with 2-mercaptoethanol and addition of sodium dodecyl sulfate. Under these conditions the two subunits are still capable of high-affinity sulfobromophthalein binding and, despite the presence of the detergent, may be isolated by preparative polyacrylamide gel electrophoresis still associated with the dye. It may be suggested that the physiological subunit composition of bilitranslocase is α2-β. 相似文献
89.
Studies were performed to determine the development of cell-mediated cytotoxic response at tumor site in C57BL/6 mice bearing progressively growing FBL-3 ascites leukemia. The effectors isolated from tumor ascites are found to be highly cytotoxic for leukemic target cells. The levels of cytotoxicity obtained with effectors isolated from tumor site are generally higher than those obtained with immune mice. This cytotoxicity is both specific and nonspecific. The specific cytotoxicity against tumor-associated antigen is mainly mediated by T cells and the nonspecific cytotoxicity against unrelated tumor cells is mediated largely by macrophages. The T-cell-enriched preparation did not give significant natural killer activity. When testing the ability of these effectors to produce in vivo immunity against the challenge of FBL-3, it was found that only T cells could confer the transplantation-type immunity, but the immunity was transient. The macrophage-enriched preparation isolated from tumor ascites failed to give in vivo protection. These findings indicate that in FBL-3 system, mice with progressively growing tumors are able to develop immune response against tumor cells. However, this immunity is probably interfered with by a suppressor factor(s) or suppressor cells which restrict their activity to eliminate the tumor cells effectively. 相似文献
90.
Claudio D. Stern 《Experimental cell research》1982,140(2):468-471
The dorso-ventral polarity of cells within sheets of epiblast from early chick embryos can be experimentally reversed by applying low voltages across them in experimental chambers. The induced reversal is stable and affects the position of histochemically and ultrastructurally demonstrable markers. 相似文献