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131.
Thi Nguyen Quynh Kozai Toyoki Heo Jeongwook Xuan Thai Du 《Plant Cell, Tissue and Organ Culture》2001,66(3):217-225
Effects of two ventilation methods (forced and natural) and two photosynthetic photon fluxes (PPF, 150 and 250 μmol m−2 s−1) on the photoautotrophic growth of in vitro cultured coffee (Coffea arabusta) plantlets were investigated. Number of air exchanges was 2.7, 5.9 and 3.9 h−1 for forced low rate, forced high rate and natural ventilation, respectively. Single node cuttings of in vitro cultured coffee plantlets were cultured on Florialite, a mixture of vermiculite and cellulose fibers with high air porosity,
emerged in liquid half strength basal MS medium, without sucrose, vitamins and plant growth regulators. The study included
40 days in the in vitro stage and 10 days in the ex vitro stage. Mean fresh and dry weights, leaf area, shoot and root lengths and net photosynthetic rate per plantlet were significantly
greater in forced high rate treatments compared with those in natural and forced low rate treatments. PPF had a distinct effect
on shoot length suppression and root elongation of coffee plantlets in forced high rate treatments. The control of carbon
dioxide concentration inside the culture box according to the plant demand when growing was easy with the forced ventilation
method in photoautotrophic micropropagation.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
132.
Induction of Betalain Pigmentation in Hairy Roots of Red Beet under Different Radiation Sources 总被引:5,自引:0,他引:5
The effects of aluminum on lipid peroxidation and activities of antioxidative enzymes were investigated in detached rice leaves treated with 0 to 5 mM AlCl3 at pH 4.0 in the light. AlCl3 enhanced the content of malondialdehyde but not the content of H2O2. Superoxide dismutase activity was reduced by AlCl3, while catalase and glutathione reductase activities were increased. Peroxidase and ascorbate peroxidase activities were increased only after prolonged treatment, when toxicity occurred. The results give evidence that Al treatment caused oxidative stress and in turn, it caused lipid peroxidation. 相似文献
133.
Purification of recombinant human epidermal growth factor secreted from the methylotrophic yeast Hansenula polymorpha. 总被引:3,自引:0,他引:3
Joo-Hyung Heo Hye Soon Won Hyun Ah Kang Sang-Ki Rhee Bong Hyun Chung 《Protein expression and purification》2002,24(1):117-122
The gene encoding human epidermal growth factor (hEGF) was expressed as a fusion protein with the Saccharomyces cerevisiae-derived prepro alpha-factor leader in the methylotrophic yeast Hansenula polymorpha. The recombinant hEGF(1-53), when secreted by H. polymorpha, rapidly cleaved to hEGF(1-52) by carboxy-terminal proteolysis, resulting in the accumulation of C-terminal-truncated hEGF(1-52) in the culture medium. To solve this problem, we constructed a H. polymorpha mutant in which the KEX1 gene coding for carboxypeptidase ysc(alpha) was disrupted. The extent of C-terminal proteolysis of hEGF was significantly reduced when this kex1 disruptant was used as a host strain. After 24 h of shake-flask culture, most of the hEGF secreted by the kex1 disruptant remained intact, whereas more than 90% of the hEGF secreted by the wild-type was C-terminally cleaved. The recombinant hEGF was purified to >98% purity by two sequential steps of preparative scale anion exchange chromatography and reverse-phase HPLC. The authenticity of purified hEGF was confirmed by HPLC, N-terminal amino acid sequencing, and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy analyses. 相似文献
134.
To maintain embryogenic cell lines ofPimpinella brachycarpa, we suspension-cultured friable and rapidly growing yellowish calli in an MS liquid medium containing 0.2 ~ 2,4-D and 0.5pM BAP. Efficient somatic embryogenesis was achieved when selected cells were then transferred to an MS medium (0.2% gelrite)
that contained 0.2gM 2,4-D, 0.5 uM BAP, and 10.0 laM TDZ (thidiazuron). These cells were cultured at 27°C under continuous illumination (21.5
I~E m-2 s-l). Embryogenic calli expanded about four-fold, and developed into pale yellow calli. Somatic embryogenesis was initiated only
from glossy and nodular-type calli. After two more weeks of culture, globular embryos appeared on the surface of calli grown
in the MS medium that contained 10.0 /aM TDZ only, or in combination with 0.5 gM NAA. Experimenting with 2,4-D, an auxin,
to promote embryogenic calli resulted in excessive browning and death. We overcame this problem by growing glossy embryogenic
and nodular calli on media that contained 10.0 gM TDZ. Calli that were not treated with TDZ turned dark brown and were not
viable. Up to 74% of the calli showed somatic embryos when the medium was supplemented with 10.0 uM TDZ and 0.5 uM NAA. Embryos
from these TDZ-induced, somatic embryogenic calli grew efficiently, forming multiple shoots and developing into normal plants.
Therefore, efficient differentiation of suspension-cultured cell clusters into embryogenic calli, along with treatment of
subsequent somatic embryos by TDZ, suggests that TDZ probably helps in establishing the optimum cytokinin-auxin ratio required
for induction and expression of somatic embryogenesis. 相似文献
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138.
Leehyeon Kim Jiwon Heo Do Hoon Kwon Jin Seok Shin Se Hwan Jang ZeeYong Park Hyun Kyu Song 《Protein science : a publication of the Protein Society》2021,30(3):700
The N‐degron pathway determines the half‐life of proteins in both prokaryotes and eukaryotes by precisely recognizing the N‐terminal residue (N‐degron) of substrates. ClpS proteins from bacteria bind to substrates containing hydrophobic N‐degrons (Leu, Phe, Tyr, and Trp) and deliver them to the caseinolytic protease system ClpAP. This mechanism is preserved in organelles such as mitochondria and chloroplasts. Bacterial ClpS adaptors bind preferentially to Leu and Phe N‐degrons; however, ClpS1 from Arabidopsis thaliana (AtClpS1) shows a difference in that it binds strongly to Phe and Trp N‐degrons and only weakly to Leu. This difference in behavior cannot be explained without structural information due to the high sequence homology between bacterial and plant ClpS proteins. Here, we report the structure of AtClpS1 at 2.0 Å resolution in the presence of a bound N‐degron. The key determinants for α‐amino group recognition are conserved among all ClpS proteins, but the α3‐helix of eukaryotic AtClpS1 is significantly shortened, and consequently, a loop forming a pocket for the N‐degron is moved slightly outward to enlarge the pocket. In addition, amino acid replacement from Val to Ala causes a reduction in hydrophobic interactions with Leu N‐degron. A combination of the fine‐tuned hydrophobic residues in the pocket and the basic gatekeeper at the entrance of the pocket controls the N‐degron selectivity of the plant ClpS protein. 相似文献
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