scholarly journals Identification and Characterization of Rice OsHKT1;3 Variants

Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2006
Author(s):  
Shahin Imran ◽  
Yoshiyuki Tsuchiya ◽  
Sen Thi Huong Tran ◽  
Maki Katsuhara
Keyword(s):  
Expression System ◽  
Ion Homeostasis ◽  
Transcript Level ◽  
Absolute Quantification ◽  
Xenopus Laevis Oocytes ◽  
Japonica Rice ◽  
Na Currents ◽  
Mrna Variants ◽  
Identification And Characterization

In rice, the high-affinity K+ transporter, OsHKT1;3, functions as a Na+-selective transporter. mRNA variants of OsHKT1;3 have been reported previously, but their functions remain unknown. In this study, five OsHKT1;3 variants (V1-V5) were identified from japonica rice (Nipponbare) in addition to OsHKT1;3_FL. Absolute quantification qPCR analyses revealed that the transcript level of OsHKT1;3_FL was significantly higher than other variants in both the roots and shoots. Expression levels of OsHKT1;3_FL, and some variants, increased after 24 h of salt stress. Two electrode voltage clamp experiments in a heterologous expression system using Xenopus laevis oocytes revealed that oocytes expressing OsHKT1;3_FL and all of its variants exhibited smaller Na+ currents. The presented data, together with previous data, provide insights to understanding how OsHKT family members are involved in the mechanisms of ion homeostasis and salt tolerance in rice.

scholarly journals Expression and Ion Transport Activity of Rice OsHKT1;1 Variants

Plants ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 16 ◽  
Author(s):  
Shahin Imran ◽  
Tomoaki Horie ◽  
Maki Katsuhara
Keyword(s):  
Absolute Quantification ◽  
Inward Rectification ◽  
Xenopus Laevis Oocytes ◽  
Japonica Rice ◽  
Transport Activity ◽  
Salt Tolerant ◽  
High Affinity ◽  
Transporter Family ◽  
Mrna Variants ◽  
Electrode Voltage

OsHKT1;1 in rice, belongs to the high-affinity K+ Transporter family, has been found to be involved in salt tolerance. OsHKT1;1 in japonica rice (Nipponbare) produces mRNA variants, but their functions remain elusive. In salt tolerant rice, Pokkali, eight OsHKT1;1 variants (V1-V8) were identified in addition to the full-length OsHKT1;1 (FL) cDNA. Absolute quantification by qPCR revealed that accumulation of OsHKT1;1-FL mRNA is minor in contrast to that of OsHKT1;1-V1, -V2, -V4, and -V7 mRNAs, all of which are predominant in shoots, while only V1 and V7 mRNAs are predominant in roots. Two electrode voltage clamp (TEVC) experiments using Xenopus laevis oocytes revealed that oocytes-expressing OsHKT1;1-FL from Pokkali exhibited inward-rectified currents in the presence of 96 mM Na+ as reported previously. Further TEVC analyses indicated that six of eight OsHKT1;1 variants elicited currents in a Na+ or a K+ bath solution. OsHKT1;1-V6 exhibited a similar inward rectification to the FL protein. Contrastingly, however, the rests mediated bidirectional currents in both Na+ and K+ bath solutions. These data suggest possibilities that novel mechanisms regulating the transport activity of OsHKT1;1 might exist, and that OsHKT1;1 variants might also carry out distinct physiological roles either independently or in combination with OsHKT1;1-FL.

Identification and characterization of apocarotenoid modifiers and carotenogenic enzymes for biosynthesis of crocins in Buddleja davidii flowers

2021 ◽  
Vol 72 (8) ◽  
pp. 3200-3218
Author(s):  
Gianfranco Diretto ◽  
Alberto José López-Jiménez ◽  
Oussama Ahrazem ◽  
Sarah Frusciante ◽  
Jingyuan Song ◽  
...  
Keyword(s):  
Flower Development ◽  
Expression Patterns ◽  
Transcript Level ◽  
Crocus Sativus ◽  
Buddleja Davidii ◽  
Gardenia Jasminoides ◽  
Carotenoid Cleavage Dioxygenases ◽  
Identification And Characterization ◽  
Carotenoid Pathway

Abstract Crocetin biosynthesis in Buddleja davidii flowers proceeds through a zeaxanthin cleavage pathway catalyzed by two carotenoid cleavage dioxygenases (BdCCD4.1 and BdCCD4.3), followed by oxidation and glucosylation reactions that lead to the production of crocins. We isolated and analyzed the expression of 12 genes from the carotenoid pathway in B. davidii flowers and identified four candidate genes involved in the biosynthesis of crocins (BdALDH, BdUGT74BC1, BdUGT74BC2, and BdUGT94AA3). In addition, we characterized the profile of crocins and their carotenoid precursors, following their accumulation during flower development. Overall, seven different crocins, crocetin, and picrocrocin were identified in this study. The accumulation of these apocarotenoids parallels tissue development, reaching the highest concentration when the flower is fully open. Notably, the pathway was regulated mainly at the transcript level, with expression patterns of a large group of carotenoid precursor and apocarotenoid genes (BdPSY2, BdPDS2, BdZDS, BdLCY2, BdBCH, BdALDH, and BdUGT Genes) mimicking the accumulation of crocins. Finally, we used comparative correlation network analysis to study how the synthesis of these valuable apocarotenoids diverges among B. davidii, Gardenia jasminoides, and Crocus sativus, highlighting distinctive differences which could be the basis of the differential accumulation of crocins in the three species.

scholarly journals Characterization of the monocarboxylate transporter 1 expressed in Xenopus laevis oocytes by changes in cytosolic pH

1998 ◽  
Vol 333 (1) ◽  
pp. 167-174 ◽  
Author(s):  
Stefan BRÖER ◽  
Hans-Peter SCHNEIDER ◽  
Angelika BRÖER ◽  
Basim RAHMAN ◽  
Bernd HAMPRECHT ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Intracellular Ph ◽  
Expression System ◽  
Lactate Concentration ◽  
Monocarboxylate Transporter ◽  
Kinetic Properties ◽  
Xenopus Laevis Oocytes ◽  
Lactate Transport ◽  
Monocarboxylate Transporter 1

Several laboratories have investigated monocarboxylate transport in a variety of cell types. The characterization of the cloned transporter isoforms in a suitable expression system is nevertheless still lacking. H+/monocarboxylate co-transport was therefore investigated in monocarboxylate transporter 1 (MCT1)-expressing Xenopus laevis oocytes by using pH-sensitive microelectrodes and [14C]lactate. Superfusion with lactate resulted in intracellular acidification of MCT1-expressing oocytes, but not in non-injected control oocytes. The basic kinetic properties of lactate transport in MCT1-expressing oocytes were determined by analysing the rates of intracellular pH changes under different conditions. The results were in agreement with the known properties of the transporter, with respect to both the dependence on the lactate concentration and the external pH value. Besides lactate, MCT1 mediated the reversible transport of a wide variety of monocarboxylic acids including pyruvate, d,l-3-hydroxybutyrate, acetoacetate, α-oxoisohexanoate and α-oxoisovalerate, but not of dicarboxylic and tricarboxylic acids. The inhibitor α-cyano-4-hydroxycinnamate bound strongly to the transporter without being translocated, but could be displaced by the addition of lactate. In addition to changes in the intracellular pH, lactate transport also induced deviations from the resting membrane potential.

Identification and characterization of a major QTL responsible for erect panicle trait in japonica rice (Oryza sativa L.)

2007 ◽  
Vol 115 (8) ◽  
pp. 1093-1100 ◽  
Author(s):  
Chang-Jie Yan ◽  
Ji-Hua Zhou ◽  
Song Yan ◽  
Feng Chen ◽  
Martin Yeboah ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Oryza Sativa L ◽  
Japonica Rice ◽  
Identification And Characterization ◽  
Major Qtl

scholarly journals Identification and Characterization of a New Staphylococcal Enterotoxin-Related Putative Toxin Encoded by Two Kinds of Plasmids

2003 ◽  
Vol 71 (10) ◽  
pp. 6088-6094 ◽  
Author(s):  
Katsuhiko Omoe ◽  
Dong-Liang Hu ◽  
Hiromi Takahashi-Omoe ◽  
Akio Nakane ◽  
Kunihiro Shinagawa
Keyword(s):  
Escherichia Coli ◽  
Expression System ◽  
Staphylococcal Enterotoxin ◽  
Nucleotide Sequencing ◽  
Sequencing Analysis ◽  
T Cell Stimulation ◽  
Putative Toxin ◽  
Identification And Characterization ◽  
Related Plasmid

ABSTRACT We identified and characterized a novel staphylococcal enterotoxin-like putative toxin, which is named SER. Nucleotide sequencing analysis of the ser gene revealed that ser was most closely related to the seg gene. The ser gene product, SER, was successfully expressed as a recombinant protein in an Escherichia coli expression system, and recombinant SER (rSER) showed significant T-cell stimulation activity. The SER production in ser-harboring Staphylococcus aureus strains was confirmed by Western blot analysis using anti-rSER antibody. Moreover, ser was seen to be encoded by at least two types of plasmids. In particular, one kind of plasmid encoding the ser gene has been known as a sed- and sej-carrying pIB485-related plasmid.

scholarly journals Identification and Characterization of the Na+/H+ Antiporter NhaS3 from the Thylakoid Membrane of Synechocystis sp. PCC 6803

2009 ◽  
Vol 284 (24) ◽  
pp. 16513-16521 ◽  
Author(s):  
Kenta Tsunekawa ◽  
Toshiaki Shijuku ◽  
Mitsuo Hayashimoto ◽  
Yoichi Kojima ◽  
Kiyoshi Onai ◽  
...  
Keyword(s):  
Thylakoid Membrane ◽  
Ion Homeostasis ◽  
E Coli ◽  
Subjective Night ◽  
Genes Encoding ◽  
Ph Range ◽  
Identification And Characterization ◽  
Pcc 6803

Na+/H+ antiporters influence proton or sodium motive force across the membrane. Synechocystis sp. PCC 6803 has six genes encoding Na+/H+ antiporters, nhaS1–5 and sll0556. In this study, the function of NhaS3 was examined. NhaS3 was essential for growth of Synechocystis, and loss of nhaS3 was not complemented by expression of the Escherichia coli Na+/H+ antiporter NhaA. Membrane fractionation followed by immunoblotting as well as immunogold labeling revealed that NhaS3 was localized in the thylakoid membrane of Synechocystis. NhaS3 was shown to be functional over a pH range from pH 6.5 to 9.0 when expressed in E. coli. A reduction in the copy number of nhaS3 in the Synechocystis genome rendered the cells more sensitive to high Na+ concentrations. NhaS3 had no K+/H+ exchange activity itself but enhanced K+ uptake from the medium when expressed in an E. coli potassium uptake mutant. Expression of nhaS3 increased after shifting from low CO2 to high CO2 conditions. Expression of nhaS3 was also found to be controlled by the circadian rhythm. Gene expression peaked at the beginning of subjective night. This coincided with the time of the lowest rate of CO2 consumption caused by the ceasing of O2-evolving photosynthesis. This is the first report of a Na+/H+ antiporter localized in thylakoid membrane. Our results suggested a role of NhaS3 in the maintenance of ion homeostasis of H+, Na+, and K+ in supporting the conversion of photosynthetic products and in the supply of energy in the dark.

scholarly journals Identification and Characterization of a Trillin Rhamnosyltransferase From Dioscorea zingiberensis

2021 ◽  
Vol 12 ◽  
Author(s):  
Jia Li ◽  
Isidore Mosongo ◽  
Han Li ◽  
Yalun Wu ◽  
Changfu Li ◽  
...  
Keyword(s):  
Transcript Level ◽  
Efficient Production ◽  
Cytochrome P450 Enzymes ◽  
Steroidal Saponins ◽  
Pharmacological Activities ◽  
Dioscorea Zingiberensis ◽  
Wide Range ◽  
Genes Encoding ◽  
Identification And Characterization

Dioscorea zingiberensis accumulates abundant steroidal saponins, such as dioscin, which is the principal bioactive ingredient displaying a wide range of pharmacological activities. Diosgenin is the aglycone of dioscin, and recently, genes encoding cytochrome P450 enzymes in the late steps of diosgenin biosynthesis have been isolated. Diosgenin was successfully synthesized in the cholesterol-producing yeasts. From diosgenin to dioscin, one glucose and two rhamnose groups need to be added. Although genes encoding UDP-glucosyltransferases converting diosgenin to trillin were isolated, genes encoding UDP-rhamnosyltransferases involved in dioscin biosynthesis remain unknown. In this study, we isolated the cDNA encoding the trillin rhamnosyltransferase (designated DzGT1) from D. zingiberensis. Heterologous expression of DzGT1 in Escherichia coli cells showed that the gene product exhibits an enzyme activity that glycosylates the trillin to form prosapogenin A of dioscin (PSA). The transcript level of DzGT1 is in accord with PSA accumulation in different organs of D. zingiberensis. Integration of the biochemical, metabolic, and transcriptional data supported the function of DzGT1 in dioscin biosynthesis. The identification and characterization of DzGT1 will help understand the metabolism of steroidal saponins in D. zingiberensis and provide candidate UDP-rhamnosyltransferase for efficient production of PSA, dioscin, and relevant steroidal saponins in microbial hosts.

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