Summary Auxin (indole-3-acetic acid) is considered to be an important signalling molecule in the regulation of plant growth and development but neither auxin synthesis nor its mode of action is clearly understood. To identify genes involved in these processes, mutations were sought that altered the auxin requirement of plant tissues for growth. For the first time mutant plants were obtained that carry a recessive mutation at a single nuclear locus (auxl) which results in an absolute requirement for exogenous auxin for normal growth. In the absence of auxin treatment, mutant plants undergo premature senescence and die.Abbreviations BAP
6-benzylaminopurine
- BUdR
5-bromodeoxyuridine
- 2,4-D
2,4-dichlorophenoxyacetic acid
- FUdR
5-fluorodeoxyuridine
- IAA-EE
indole-3-acetic acid ethyl ester
- IMS
indole-3-methanesulfonic acid 相似文献
We have studied 11 cases of acute human trichinosis; five of these patients were treated with thiabendazole. We have reviewed the laboratory data for these patients and described their course. This study has failed to show any definite effect of thiabendazole on the course of human trichinosis at the doses used. However, thiabendazole may have decreased the infectivity of the larvae which were embedded in the muscles of our patients. 相似文献
Summary We describe the in vitro influence of 3,5,3′-triiodo-l-thyronine (T3),l-thyroxine (T4), a thyroid-stimulating hormone (TSH), and/or estradiol (E2: chosen as the control of the methodology) on the cell kinetics (cell distribution in the S+G2+M phases) of mouse MXT and human MCF-7 mammary cancer cells. Experiments were performed by means of a cell image processor,
analyzing MCF-7 or MXT cells that had been grown on glass cover slips and whose nuclei had been stained by the Feulgen reaction,
which is selective and quantitative (stoichiometric) with respect to DNA. We show that T3, T4, and TSH at 0.01 μM dramatically stimulate the cell kinetics of the MXT mouse and the MCF-7 human mammary cancer cell lines. Indeed, the three
hormones bring about a significant transient increase in the S+G2+M fraction as does E2. Furthermore, our data indicate that E2 and TSH are antagonistic with regards to MXT or MCF-7 cell kinetics.
This work is supported by grants awarded by the IRSIA and the Fonds de la Recherche Scientifique Médicale (FRSM, Belgium). 相似文献
The phytochrome chromophore-deficient mutant, pew1, of Nicotiana plumbaginifolia exhibited decreased germination and slower dehydration of detached leaves during water stress as compared with the wild-type. These physiological processes are controlled by abscisic acid (ABA) and we examined, therefore, whether phytochrome plays a specific role in the regulation of ABA metabolism using the pew1 mutant. The ABA contents of mature seeds and young leaves were analysed and in both cases mutant material was found to contain higher amounts of ABA as compared with the wild-type. This indicates that the phytochrome activation can lead to a decrease of the ABA level in the wild-type plant. The role of phytochromes was investigated in greater detail using the ABA-deficient mutant aba1 of N. plumbaginifolia exhibiting an early and synchronous germination. This mutant accumulates at very high levels a metabolite derived from a precursor (ABA-aldehyde) in the ABA biosynthetic pathway. The first biochemical characterization of this molecule, which corresponds to the glucose-conjugated ABA-alcohol (ABA-AG) is described. A pew1-aba1 double mutant exhibiting both an etiolated growth and early germination was also obtained. The comparable accumulation of ABA-AG in the pew1-aba1 double mutant as compared with the aba1 mutant allowed the proposition that, in a wild-type plant, the phytochrome-mediated light signal enhances ABA degradation rather than inhibits its biosynthesis. 相似文献
Cadmium-113 nuclear magnetic resonance (113Cd nmr) was used to elucidate the structural properties of the cadmium binding sites in human liver metallothionein. The isotopically labeled 113Cd-metallothionein was prepared by the in vitro exchange of the native metals (greater than 94% zinc) for 113CdCl2 during isolation. The two isoproteins, MT-1 and MT-2, showed 113Cd nmr resonances in the chemical shift range 610–670 ppm. The multiplet structure of the resonances is due to two bond scalar interactions between adjacent 113Cd ions linked by cysteine thiolate ligands. Homonuclear 113Cd decoupling experiments allowed the determination of the metal cluster structure, which, similar to the rabbit liver metallothionein, consists of a four- and a three-metal cluster designated cluster A and cluster B, respectively. Chemical shift similarities in the 113Cd nmr spectra of the human, rabbit and calf liver MT-1 and MT-2 are observed, especially for cluster A. Small variations in chemical shifts are explained in terms of differences in the primary structure between the two human isoproteins. 相似文献
Environmental Biology of Fishes - Cortisol is recognized as a physiological indicator of stress in fish. However, this hormone is typically measured in plasma samples. In this study, cortisol... 相似文献
The skin secretions of amphibians are a rich source of bioactive peptides. We isolated chensirin-1 and chensirin-2 from the skin secretion of the Chinese frog Rana chensinensis. Sephadex-G-50 and RP-HPLC were employed to purify these peptides. The amino acid sequences of these peptides were VLPLVGNLLNDLLGE and IIPLPLGYFAKKT, respectively, as determined by Edman degradation. The molecular weights were 1578.7 and 1460.8 Da, respectively, as analyzed by HPLC-ESI-MS. The chensirin cDNA was cloned by 5′ and 3′ amplification of cDNA ends, synthesized and purified. The antibacterial activities of the chensirins were tested using minimum inhibitory concentration, the results indicated that chensirins inhibit the growth of gram-negative and gram-positive bacteria. Among them, chensirin-1 is a novel peptide with a higher antibacterial activity compared to other similar antimicrobial peptides. These low molecular weight peptides with good antimicrobial efficacy are considered potential sources for developing new antimicrobial agents to improve traditional drug resistance.