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The Regulation of Root Hair-specific Expansin Genes
Cho, Hyung-Taeg The Korean Society of Plant Pathology 2004 Plant Pathology Journal Vol.20 No.1
The root hair provides a major entering spot for the symbiotic legume rhizobia. It is obvious that dynamic cell wall modification occurs in the plant root hair during the early microbe invasion. Expansins are nondestructive cell wall-modifying proteins that are involved in cell growth and differentiation. Among about 40 expansin genes in Arabidopsis, two expansin genes are expressed specifically in the root hair cell. Orthologous genes of this Arabidopsis root hair expansins have been found in other Brassica members, rice, and Medicago truncatula (a legume). In this review, I discuss the probable function of expansins during the early symbiotic process between the root hair and microbes and the regulation of root hair expansin genes in a comparative approach.
Charaterization of Plasma Membrane $H^{+}$-ATPase from Sunflower Hypocotyls
Cho, Hyung-Taeg,Hong, Young-Nam 생화학분자생물학회 1994 한국생화학회지 Vol.27 No.4
Plasma membrane (PM) $H^{+}$-ATPase of sunflower (Helianthus annuus L.) hypocotyls with plasma membrane vesicles prepared by aqueous two-phase partitioning was characterized. Microsomal fraction proteins were partitioned into lower and upper phases using a polymer concentration of 6.4%. The ATPase activity was dependent on $Mg^{2+}$, but was slightly influenced by $K^+$. Molybdate, azide, and nitrate, which inhibit unspecific phosphatase, mitochondrial ATPase, and tonoplast ATPase, respectively, had little effect on the enzyme, reflecting the purity of the plasma membrane. However, $100{\mu}M$ vanadate inhibited enzyme activity by more than 90%. $Ca^{2+}$ also increasingly inhibited enzyme activity with increasing concentration, and the inhibitory effect was considerable below pH 7. The ATPase had a $K_m$ value of 0.38 mM ATP, an optimum pH of 6.5, and an optimum temperature of $40^{\circ}C$. Optimum removal of enzyme latency occurred with 0.01% Triton X-100 or 0.0025% lysolecithin, but Triton X-100 above 0.01% was inhibitory.
Characterization of Plasma Membrane H+ ATPase from Sunflower Hypocotyls
Hyung Taeg Cho,Young Nam Hong 생화학분자생물학회 1994 BMB Reports Vol.27 No.4
Plasma membrane (PM) H^+-ATPase of sunflower (Helianthus annuus L.) hypocotyls with plasma membrane vesicles prepared by aqueous two-phase partitioning was characterized. Microsomal fraction proteins were partitioned into lower and upper phases using a polymer concentration of 6.4%. The ATPase activity was dependent on Mg^(2+), but was slightly influenced by K^+. Molybdate, azide, and nitrate, which inhibit unspecific phosphatase, mitochondrial ATPase, and tonoplast ATPase, respectively, had little effect on the enzyme, reflecting the purity of the plasma membrane. However, 100 μM vanadate inhibited enzyme activity by more than 90%. Ca^(2+) also increasingly inhibited enzyme activity with increasing concentration, and the inhibitory effect was considerable below pH 7. The ATPase had a Km value of 0.38 mM ATP, an optimum pH of 6.5, and an optimum temperature of 40℃. Optimum removal of enzyme latency occurred with 0.01% Triton X-100 or 0.0025% lysolecithin, but Triton X-100 above 0.01% was inhibitory.
Landes Bioscience 2007 Plant signaling & behavior Vol.2 No.2
<P>Three types of root hair cell distribution patterns are observed in vascular plants. These distinctive patterning types indicate that the fate of the hair/nonhair cell of the root epidermis in each of these patterns is decided by different fate-determining machineries. The cell fate determiners ultimately control the hair or nonhair cell-specific genes so as to modulate hair morphogenesis. Here, we address the issue of whether or not the hair cell specificity of gene expression, i.e., the regulatory cis-element for hair cell specificity, has been conserved despite the divergence of the upstream fate-determining machineries. Our recent study in Plant Cell (the November issue online) reported that orthologs and paralogs of Arabidopsis expansin A7 (AtEXPA7) from angiosperms with different hair-distribution types have maintained a common cis-element (RHE for Root Hair Element) for root hair cell specificity. The study also identified the same functional RHE among root hair-specific cell wall genes other than those coding for expansins. These findings suggest that the same regulatory module of RHE and its transcription factor partner, which endows cell morphogenetic worker genes with hair cell specificity, have been coopted by different upstream fate-determining masters over angiosperm evolution.</P>
Cho, Hyung-Yong,Choi, Hyeong-Taeg 기전여자대학 1996 論文集 Vol.16 No.-
Evalution of food quality changes requires an accurate treatment of the time-temperature history during processing, distribution and storage. The effectiveness of three different numerical methods were assessed to predict kinetic parameters from published and experimental data sets. The generalized one-step procedure using equivalent time at a reference temperature(t_(eq)), which provides a method-for converting any variable temperature history to equivalent time at a specified reference temperature, gave the smallest sum of squares for error and a computing rate 6~5 times faster than that estimated by the conventional one-step method.