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41.
Exogenous polyamines improve rooting of hazel microshoots 总被引:7,自引:0,他引:7
Manuel Rey Carmen Díaz-Sala Roberto Rodríguez 《Plant Cell, Tissue and Organ Culture》1994,36(3):303-308
A strong positive effect of polyamines on rooting of microshoots of adult hazel (Corylus avellana L., cv. Gironell) is described. The effect of polyamines, both in the root induction solution and in the actual rooting medium, was assessed in order to study the effect on the successive rooting phases. Polyamines improved rooting of indole-3-butyric acid-treated microshoots in a synergistic fashion, perhaps by favouring a better induction of roots, with an acceleration of the response (only half the time required for rooting compared to the control). When applied without indole-3-butyric acid, polyamines had only a limited positive effect on rooting, although longer exposure times and/or higher concentrations could increase their effect. Possible rapid uptake and translocation of polyamines in the xylem in our system is discussed. The results offer a new approach to enhance rooting ability of species that are normally difficult to root.Abbreviations BM
basal medium
- IAA
indole-3-acetic acid
- IBA
indole-3-butyric acid
- NAA
1-naphthaleneacetic acid
- Put
putrescine
- Spd
spermidine
- Spm
spermine 相似文献
42.
Fayazpour F Lucas B Alvarez-Lorenzo C Sanders NN Demeester J De Smedt SC 《Biomacromolecules》2006,7(10):2856-2862
In this study the physicochemical and transfection properties of cationic hydroxyethylcellulose/plasmid DNA (pDNA) nanoparticles were investigated and compared with the properties of DNA nanoparticles based on polyethylene imine (PEI), which is widely investigated as a gene carrier. The two types of cationic hydroxyethylcelluloses studied, polyquaternium-4 (PQ-4) and polyquaternium-10 (PQ-10), are already commonly used in cosmetic and topical drug delivery devices. Both PQ-4 and PQ-10 spontaneously interact with pDNA with the formation of nanoparticles approximately 200 nm in size. Gel electrophoresis and fluorescence dequenching experiments indicated that the interactions between pDNA and the cationic celluloses were stronger than those between pDNA and PEI. The cationic cellulose/pDNA nanoparticles transfected cells to a much lesser extent than the PEI-based pDNA nanoparticles. The low transfection property of the PQ-4/pDNA nanoparticles was attributed to their neutrally charged surface, which does not allow an optimal binding of PQ-4/pDNA nanoparticles to cellular membranes. Although the PQ-10/pDNA nanoparticles were positively charged and thus expected to be taken up by cells, they were also much less efficient in transfecting cells than were PEI/pDNA nanoparticles. Agents known to enhance the endosomal escape were not able to improve the transfection properties of PQ-10/pDNA nanoparticles, indicating that a poor endosomal escape is, most likely, not the major reason for the low transfection activity of PQ-10/pDNA nanoparticles. We hypothesized that the strong binding of pDNA to PQ-10 prohibits the release of pDNA from PQ-10 once the PQ-10/pDNA nanoparticles arrive in the cytosol of the cells. Tailoring the nature and extent of the cationic side chains on this type of cationic hydroxyethylcellulose may be promising to further enhance their DNA delivery properties. 相似文献
43.
Hernández-Montiel HL Meléndez-Herrera E Cepeda-Nieto AC Mejía-Viggiano C Larriva-Sahd J Guthrie S Varela-Echavarría A 《Developmental biology》2003,255(1):99-112
We have addressed the control of longitudinal axon pathfinding in the developing hindbrain, including the caudal projections of reticular and raphe neurons. To test potential sources of guidance signals, we assessed axon outgrowth from embryonic rat hindbrain explants cultured in collagen gels at a distance from explants of midbrain-hindbrain boundary (isthmus), caudal hindbrain, or cervical spinal cord. Our results showed that the isthmus inhibited caudally directed axon outgrowth by 80% relative to controls, whereas rostrally directed axon outgrowth was unaffected. Moreover, caudal hindbrain or cervical spinal cord explants did not inhibit caudal axons. Immunohistochemistry for reticular and raphe neuronal markers indicated that the caudal, but not the rostral projections of these neuronal subpopulations were inhibited by isthmic explants. Companion studies in chick embryos showed that, when the hindbrain was surgically separated from the isthmus, caudal reticulospinal axon projections failed to form and that descending pioneer axons of the medial longitudinal fasciculus (MLF) play an important role in the caudal reticulospinal projection. Taken together, these results suggest that diffusible chemorepellent or nonpermissive signals from the isthmus and substrate-anchored signals on the pioneer MLF axons are involved in the caudal direction of reticulospinal projections and might influence other longitudinal axon projections in the brainstem. 相似文献
44.
Gloria Alvarez-Sola Iker Uriarte Maria U. Latasa Maddalen Jimenez Marina Barcena-Varela Eva Santamaría Raquel Urtasun Carlos Rodriguez-Ortigosa Jesús Prieto Pedro Berraondo Maite G. Fernandez-Barrena Carmen Berasain Matías A. Avila 《生物化学与生物物理学报:疾病的分子基础》2018,1864(4):1326-1334
The liver has an extraordinary regenerative capacity rapidly triggered upon injury or resection. This response is intrinsically adjusted in its initiation and termination, a property termed the “hepatostat”. Several molecules have been involved in liver regeneration, and among them bile acids may play a central role. Intrahepatic levels of bile acids rapidly increase after resection. Through the activation of farnesoid X receptor (FXR), bile acids regulate their hepatic metabolism and also promote hepatocellular proliferation. FXR is also expressed in enterocytes, where bile acids stimulate the expression of fibroblast growth factor 15/19 (FGF15/19), which is released to the portal blood. Through the activation of FGFR4 on hepatocytes FGF15/19 regulates bile acids synthesis and finely tunes liver regeneration as part of the “hepatostat”. Here we review the experimental evidences supporting the relevance of the FXR-FGF15/19-FGFR4 axis in liver regeneration and discuss potential therapeutic applications of FGF15/19 in the prevention of liver failure. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen. 相似文献
45.
Purification, Characterization, and Functional Role of a Novel Extracellular Protease from Pleurotus ostreatus 总被引:3,自引:0,他引:3 下载免费PDF全文
Gianna Palmieri Carmen Bianco Giovanna Cennamo Paola Giardina Gennaro Marino Maria Monti Giovanni Sannia 《Applied microbiology》2001,67(6):2754-2759
A new extracellular protease (PoSl; Pleurotus ostreatus subtilisin-like protease) from P. ostreatus culture broth has been purified and characterized. PoSl is a monomeric glycoprotein with a molecular mass of 75 kDa, a pI of 4.5, and an optimum pH in the alkaline range. The inhibitory profile indicates that PoSl is a serine protease. The N-terminal and three tryptic peptide sequences of PoSl have been determined. The homology of one internal peptide with conserved sequence around the Asp residue of the catalytic triad in the subtilase family suggests that PoSl is a subtilisin-like protease. This hypothesis is further supported by the finding that PoSl hydrolysis sites of the insulin B chain match those of subtilisin. PoSl activity is positively affected by calcium. A 10-fold decrease in the Km value in the presence of calcium ions can reflect an induced structural change in the substrate recognition site region. Furthermore, Ca2+ binding slows PoSl autolysis, triggering the protein to form a more compact structure. These effects have already been observed for subtilisin and other serine proteases. Moreover, PoSl protease seems to play a key role in the regulation of P. ostreatus laccase activity by degrading and/or activating different isoenzymes. 相似文献
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We have developed a ligation and specificprimer radiolabeling method that allows the use of oligonucleotides as probes in blot-hybridization experiments. The major advantage of the protocol is that standard hybridization and washing conditions may be used and yield high signals and low background. The observed increase in the stability and intensity of the hybridization signals appears to result from both increased length and specific radioactivity of the hybridization probe. 相似文献
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