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141.
Amino acid sulfur as a source of sulfate for sulfated proteoglycans produced by Swiss mouse 3T3 cells 总被引:3,自引:0,他引:3
The uptake of sulfate by Swiss mouse 3T3 cells is blocked in the presence of 1 mM 4-isothiocyano-4'-acetamido-stilbene-2,2-disulfonic acid (SITS). In the absence of an exogenous source of sulfate, glycosaminoglycans produced by cells in the presence of the inhibitor are sulfated to the same extent as those produced by cells grown in its absence. The sulfate utilized in the absence of medium sulfate has been identified as that produced by the oxidation of the sulfur present in the amino acids cysteine and methionine. This finding indicates that, under conditions of restricted exogenous sulfate, caution is needed in the interpretation of data obtained with the use of [35S]methionine and/or [35S]cysteine as a general protein label, since both tyrosine and a variety of types of protein-linked carbohydrate chains may be modified by sulfation. 相似文献
142.
143.
Levels of 7.8, 18.5 and 26 mole % deuterium oxide were administered sequentially to (Japanese quail) via the drinking water. The primary effect observed was on egg frequency, which decreased from a normal level of 0.89 for 7.8 mole % D2O to a low of 0.38 during the administration of 26 mole % D2O. Adverse symptoms, such as hyperexcitability, convulsions, skin ulcerations, comatosity, weight loss, or death, which have been associated with deuterium toxicity in other animals, were not observed in these experiments. The amount of deuterium deposited in the water of the egg was 6.9, 13.98, and 19.83 mole % when 7.8, 18.5 and 26 mole % deuterium respectively was administered. For each period, the deuterium content of egg water rapidly reached a maximum concentration after which the concentration decreased slightly. This dilution effect has not been noted previously in body fluids from other animals. 相似文献
144.
Shailesh Kumar Atma P. Dwivedi Vivek Kr. Kashyap A.K. Saxena A.K. Dwivedi Ranjana Srivastava Devi P. Sahu 《Bioorganic & medicinal chemistry letters》2013,23(8):2404-2407
Synthesis of a library of novel trans 6-methoxy-1,1-dimethyl-2-phenyl-3-aryl-2,3-dihydro-1H-inden-4-yloxy alkyl amines and their antimycobacterial activity against drug sensitive and multidrug resistant strains of Mycobacterium tuberculosis have been reported. All the new compounds in the series exhibited MIC between 1.56 and 6.25 μg/ml. Two compounds 1i and 1j with low MIC and low cytotoxicity showed significant reduction in CFU in infected mouse macrophages at 1× MIC concentration. The compound 1i inhibited the growth of M. tuberculosis in mice at 100 mg/kg dose with 1.35 log10 reduction of CFU in lungs tissue and was active against non-replicating Mycobacterium tuberculosis under anaerobic condition. 相似文献
145.
The potential for and constraints on the evolution of compensatory ability in Asclepias syriaca 总被引:2,自引:0,他引:2
To investigate the potential for and constraints on the evolution of compensatory ability, we performed a greenhouse experiment
using Asclepias syriaca in which foliar damage and soil nutrient concentration were manipulated. Under low nutrient conditions, significant genetic
variation was detected for allocation patterns and for compensatory ability. Furthermore, resource allocation to storage was
positively, genetically correlated both with compensatory ability and biomass when damaged, the last two being positively,
genetically correlated with each other. Thus, in the low nutrient environment, compensatory ability via resource allocation
to storage provided greater biomass when damaged. A negative genetic correlation between compensatory ability and plant biomass
when undamaged suggests that this mechanism entailed an allocation cost, which would constrain the evolution of greater compensatory
ability when nutrients are limited. Under high nutrient conditions, neither compensatory ability nor allocation patterns predicted
biomass when damaged, even though genetic variation in compensatory ability existed. Instead, plant biomass when undamaged
predicted biomass when damaged. The differences in outcomes between the two nutrient treatments highlight the importance of
considering the possible range of environmental conditions that a genotype may experience. Furthermore, traits that conferred
compensatory ability did not necessarily contribute to biomass when damaged, demonstrating that it is critical to examine
both compensatory ability and biomass when damaged to determine whether selection by herbivores can favor the evolution of
increased compensation.
Received: 2 April 1999 / Accepted: 21 September 1999 相似文献
146.
Methods for inducing high-frequency somatic embryos in cassava on cotyledons and 33 clonal accessions by the addition of supplementary copper sulphate to the induction medium were investigated. The addition of copper sulphate enhanced primary embryo induction and significantly increased secondary embryo production. All accessions from Latin America (CIAT) were embryogenically competent on medium supplemented with 8 mg l-1 2,4-dichlorophenoxyacetic acid (2,4-D) plus 1 µM copper sulphate as were 15 of the 18 accessions from Africa. The percentage of calli producing somatic embryos ranged from 7.5% in M. Bra 12 to 100% in M. Col. 1505, while the number of embryos produced per callus ranged from 0.3 in M. Bra 383 to 13.5 in TEK. The frequency of embryo production was dependent on the concentration of copper sulphate. The number of primary embryos produced per callus was also comparatively higher in the medium supplemented with copper sulphate than in the controls. The optimal concentration of copper sulphate for number of embryos produced in most accessions was 5 µM, and at this concentration the number of embryos produced was double that of the controls. Copper sulphate also reduced the maturation time of somatic embryos to 25 days from embryo initiation. High levels of 2,4-D were detrimental to embryo production. Similarly, fragmented embryos incubated in the dark produced more embryos tan those incubated under light conditions. On the basis of these results, the use of cassava somatic embryo micropropagules for germplasm conservation and synthetic seed development seems to be a strong possibility. 相似文献
147.
Yongbo Hu Erin Webb Jasbir Singh Barry A Morgan James A Gainor Thomas D Gordon Teruna J Siahaan 《The Journal of biological chemistry》2002,277(10):8366-8371
The molecular basis of the substrate specificity of Clostridium histolyticum beta-collagenase was investigated using a combinatorial method. An immobilized positional peptide library, which contains 24,000 sequences, was constructed with a 7-hydroxycoumarin-4-propanoyl (Cop) fluorescent group attached at the N terminus of each sequence. This immobilized peptide library was incubated with C. histolyticum beta-collagenase, releasing fluorogenic fragments in the solution phase. The relative substrate specificity (k(cat)/K(m)) for each member of the library was determined by measuring fluorescence intensity in the solution phase. Edman sequencing was used to assign structure to subsites of active substrate mixtures. Collectively, the substrate preference for subsites (P(3)-P(4)') of C. histolyticum beta-collagenase was determined. The last position on the C-terminal side in which the identity of the amino acids affects the activity of the enzyme is P(4)', and an aromatic side chain is preferred in this position. The optimal P(1)'-P(3)' extended substrate sequence is P(1)'-Gly/Ala, P(2)'-Pro/Xaa, and P(3)'-Lys/Arg/Pro/Thr/Ser. The Cop group in either the P(2) or P(3) position is required for a high substrate activity with C. histolyticum beta-collagenase. S(2) and S(3) sites of the protease play a dominant role in fixing the substrate specificity. The immobilized peptide library proved to be a powerful approach for assessing the substrate specificity of C. histolyticum beta-collagenase, so it may be applied to the study of other proteases of interest. 相似文献
148.
Kondeti Subramanyam K. V. Sailaja Koona Subramanyam D. Muralidhara Rao K. Lakshmidevi 《Plant Cell, Tissue and Organ Culture》2011,105(2):181-192
Plants, when exposed to abiotic or biotic stress, produce several pathogenesis-related proteins to counteract the effects
of stress. Osmotin is one of the important pathogenesis-related proteins induced during several stress conditions. We have
developed improved salt stress tolerant transgenic chilli pepper plants (Capsicum annum L. var. Aiswarya 2103) by ectopic expression of the Nicotiana tabaccum osmotin gene using Agrobacterium
tumefaciens EHA105 as a vector. Four-week-old chilli pepper leaves were used as an explant and A. tumefaciens EHA105 harboring pBINASCOSM plasmid that contains osmotin gene under the control of CaMV 35S promoter and npt II as a selectable marker was used in co-cultivation. Transgene integration and expression were analyzed using molecular,
immunochemical, and biochemical assays. PCR and Southern blot analysis confirmed that osmotin gene has been successfully integrated
into the genome of chilli pepper plants. The osmotin gene was stably segregated and expressed in T2 generation transgenic chilli pepper plants, and it was confirmed by Western blot analysis. Biochemical assays of these putative
transgenic plants revealed enhanced levels of chlorophyll, proline, glycinebetaine, APX, SOD, DHAR, MDHAR, GR, and relative
water content. Yield potential of the putative transgenic chilli pepper plants was evaluated under salinity stress conditions
in a green house. The putative transgenic chilli pepper plants overexpressing the osmotin gene were morphologically similar
to wild-type plants and produced 3.32 kg chilli pepper fruits per plant at 300 mM NaCl concentration. 相似文献
149.
Carmen de Sena-Tomás Mónica Navarro-González Ursula Kües José Pérez-Martín 《Genetics》2013,195(1):47-57
The fungal fruiting body or mushroom is a multicellular structure essential for sexual reproduction. It is composed of dikaryotic cells that contain one haploid nucleus from each mating partner sharing the same cytoplasm without undergoing nuclear fusion. In the mushroom, the pileus bears the hymenium, a layer of cells that includes the specialized basidia in which nuclear fusion, meiosis, and sporulation occur. Coprinopsis cinerea is a well-known model fungus used to study developmental processes associated with the formation of the fruiting body. Here we describe that knocking down the expression of Atr1 and Chk1, two kinases shown to be involved in the response to DNA damage in a number of eukaryotic organisms, dramatically impairs the ability to develop fruiting bodies in C. cinerea, as well as other developmental decisions such as sclerotia formation. These developmental defects correlated with the impairment in silenced strains to sustain an appropriated dikaryotic cell cycle. Dikaryotic cells in which chk1 or atr1 genes were silenced displayed a higher level of asynchronous mitosis and as a consequence aberrant cells carrying an unbalanced dose of nuclei. Since fruiting body initiation is dependent on the balanced mating-type regulator doses present in the dikaryon, we believe that the observed developmental defects were a consequence of the impaired cell cycle in the dikaryon. Our results suggest a connection between the DNA damage response cascade, cell cycle regulation, and developmental processes in this fungus. 相似文献
150.
Study of the posterior abdominal epidermis in hypophysectomized/thyroidectomized male and female tokays following surgery, and subsequent androgen therapy, indicates that, contrary to a previous model, all aspects of β-gland differentiation are under direct androgenic control. On the other hand, another epidermal specialization, the digital foot-pad, shows a pattern of histogenesis directly comparable to that of β-glands, but is unaffected by androgens. These data are discussed with respect to the evolution of glandular epidermal specializations in gekkonid lizards and the possible role of androgens in modifying the control of cell differentiation in lizard epidermis. 相似文献