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1.
J Altern Complement Med ; 24(5): 422-430, 2018 May.
Article in English | MEDLINE | ID: mdl-29356554

ABSTRACT

OBJECTIVE: To study the effect of homeopathic medicines (in higher potencies) in normal subjects, Peripheral Pulse Analyzer (PPA) has been used to record physiologic variability parameters before and after administration of the medicine/placebo in 210 normal subjects. METHODS: Data have been acquired in seven rounds; placebo was administered in rounds 1 and 2 and medicine in potencies 6, 30, 200, 1 M, and 10 M was administered in rounds 3 to 7, respectively. Five different medicines in the said potencies were given to a group of around 40 subjects each. Although processing of data required human intervention, a software application has been developed to analyze the processed data and detect the response to eliminate the undue delay as well as human bias in subjective analysis. This utility named Automatic Analysis of Intervention in the Field of Homeopathy is run on the processed PPA data and the outcome has been compared with the manual analysis. The application software uses adaptive threshold based on statistics for detecting responses in contrast to fixed threshold used in manual analysis. RESULTS: The automatic analysis has detected 12.96% higher responses than subjective analysis. Higher response rates have been manually verified to be true positive. This indicates robustness of the application software. The automatic analysis software was run on another set of pulse harmonic parameters derived from the same data set to study cardiovascular susceptibility and 385 responses were detected in contrast to 272 of variability parameters. It was observed that 65% of the subjects, eliciting response, were common. CONCLUSION: This not only validates the software utility for giving consistent yield but also reveals the certainty of the response. This development may lead to electronic proving of homeopathic medicines (e-proving).


Subject(s)
Homeopathy/methods , Monitoring, Physiologic/methods , Software , Automation , Humans , Pulse/methods
2.
Enzyme Microb Technol ; 95: 107-111, 2016 Dec.
Article in English | MEDLINE | ID: mdl-27866604

ABSTRACT

Nanotechnology is leading towards the development of low cost applications to improve the cultivation and growth of plants. The use of nanotechnology in agriculture will leads to a significant effect on food industry along with opening a new area of research in agroecosystem. In this paper gold nanoparticles were biosynthesized with Cassia auriculata leaf extract at room temperature and characterized by UV-vis spectroscopy, X-ray diffraction and transmission electron microscopy. The objective of this study was to investigate effect of synthesized bio-nanogold on an important food and biofuel producing plant Pennisetum glaucum. Positive effects were observed on percentage of seed germination and growth of seedlings. Improved germination and increased plant biomass have high economic importance in production of biofuel or raw materials, agriculture and horticulture. Although the impact of nanoparticles on plants depends on concentration, size and shape. The biological synthesized AuNPs can replace the chemically synthesized AuNPs used in gene transfer method. The study gives brief insight on nanoparticles effects on plants, brings attention on both positive and negative side of nanomaterial which can resolve phytopathological infections by stimulating nutrition and growth.


Subject(s)
Gold/chemistry , Metal Nanoparticles/chemistry , Pennisetum/drug effects , Pennisetum/growth & development , Agriculture , Biotechnology , Cassia/metabolism , Germination/drug effects , Green Chemistry Technology , Metal Nanoparticles/ultrastructure , Nanotechnology , Plant Extracts/metabolism , Plant Leaves/metabolism , Seedlings/drug effects
3.
J Altern Complement Med ; 19(3): 191-7, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23030429

ABSTRACT

BACKGROUND: In spite of the tremendous progress achieved in medical sciences in the last century, the management of diabetes mellitus, a disease as old as mankind, is poor. Diabetes is currently the world's largest endocrine disorder, and estimates are that it affects almost 5% of the population. Ayurveda, the Indian traditional system of medicine, is one of the world's oldest systems to have documented the diagnosis and treatment of diabetes. METHODS: Experimental studies performed in accordance with the modern medicine principles have shown that some of the medicinal plants and polyherbal preparations made using the plants used in Ayurveda are effective in preventing both hyperglycemia and its complications. Syzygium jambolanum (Syn Syzygium cumini, Eugenia cumini, Eugenia jambolana), commonly known as black plum and originally indigenous to India, is one of the important antidiabetic plants. RESULTS: Jamun has been used in various complementary and alternative systems of medicine and, before the discovery of insulin, was a frontline antidiabetic medication even in Europe. The brew prepared by boiling the Jamun seeds in boiling water has been used in the various traditional systems of medicine in India. CONCLUSIONS: This review includes the validated antidiabetic effects of Jamun and some of its compounds. Emphasis is also placed on addressing the various mechanisms of action contributing to the pharmacological effects and the aspects that need future investigations for Jamun to be of clinical use.


Subject(s)
Diabetes Mellitus/drug therapy , Hyperglycemia/prevention & control , Hypoglycemic Agents/therapeutic use , Phytotherapy , Plant Preparations/therapeutic use , Syzygium , Humans , Hypoglycemic Agents/pharmacology , Medicine, Ayurvedic , Plant Preparations/pharmacology
4.
Physiol Mol Biol Plants ; 19(2): 261-8, 2013 Apr.
Article in English | MEDLINE | ID: mdl-24431494

ABSTRACT

A system for in vitro selection of drought tolerant callus lines in sugarcane was developed. High molecular weight PEG was used as selective agent. Selected callus line grew better than non-selected callus when grown on different concentrations of PEG. The activity of antioxidant enzymes like CAT, POX, APX and SOD were high in selected callus than in non-selected callus. Osmolytes like proline and ascorbic acid were at higher levels in selected callus than in non-selected callus, however at higher concentrations (20-30 %) of PEG, levels of proline and ascorbic acid decreased. The frequency of organogenesis and number of plantlets decreased in selected callus than in non-selected callus. The results can be used for in vitro screening and manipulations of sugarcane for improvement of drought tolerance.

5.
FEBS Lett ; 586(7): 1049-54, 2012 Apr 05.
Article in English | MEDLINE | ID: mdl-22569262

ABSTRACT

Phosphoenolpyruvate carboxylase (PEPC) is a tightly controlled anaplerotic enzyme situated at a pivotal branch point of plant carbohydrate-metabolism. In developing castor oil seeds (COS) a novel allosterically-densensitized 910-kDa Class-2 PEPC hetero-octameric complex arises from a tight interaction between 107-kDa plant-type PEPC and 118-kDa bacterial-type PEPC (BTPC) subunits. Mass spectrometry and immunoblotting with anti-phosphoSer451 specific antibodies established that COS BTPC is in vivo phosphorylated at Ser451, a highly conserved target residue that occurs within an intrinsically disordered region. This phosphorylation was enhanced during COS development or in response to depodding. Kinetic characterization of a phosphomimetic (S451D) mutant indicated that Ser451 phosphorylation inhibits the catalytic activity of BTPC subunits within the Class-2 PEPC complex.


Subject(s)
Phosphoenolpyruvate Carboxylase/metabolism , Plant Proteins/metabolism , Ricinus/enzymology , Seeds/enzymology , Serine/metabolism , Amino Acid Sequence , Amino Acid Substitution , Antibodies, Phospho-Specific , Castor Oil/chemistry , Food Handling , Isoenzymes/chemistry , Isoenzymes/genetics , Isoenzymes/metabolism , Kinetics , Molecular Sequence Data , Mutagenesis, Site-Directed , Mutant Proteins/chemistry , Mutant Proteins/metabolism , Phosphoenolpyruvate Carboxylase/chemistry , Phosphoenolpyruvate Carboxylase/genetics , Phosphorylation , Plant Proteins/chemistry , Plant Proteins/genetics , Protein Processing, Post-Translational , Protein Subunits/chemistry , Protein Subunits/genetics , Protein Subunits/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Ricinus/genetics , Ricinus/growth & development , Seeds/growth & development , Sequence Alignment
6.
J Exp Bot ; 62(15): 5485-95, 2011 Nov.
Article in English | MEDLINE | ID: mdl-21841182

ABSTRACT

This study employs transcript profiling together with immunoblotting and co-immunopurification to assess the tissue-specific expression, protein:protein interactions, and post-translational modifications (PTMs) of plant- and bacterial-type phosphoenolpyruvate carboxylase (PEPC) isozymes (PTPC and BTPC, respectively) in the castor plant, Ricinus communis. Previous studies established that the Class-1 PEPC (PTPC homotetramer) of castor oil seeds (COS) is activated by phosphorylation at Ser-11 and inhibited by monoubiquitination at Lys-628 during endosperm development and germination, respectively. Elimination of photosynthate supply to developing COS by depodding caused the PTPC of the endosperm and cotyledon to be dephosphorylated, and then subsequently monoubiquitinated in vivo. PTPC monoubiquitination rather than phosphorylation is widespread throughout the castor plant and appears to be the predominant PTM of Class-1 PEPC that occurs in planta. The distinctive developmental patterns of PTPC phosphorylation versus monoubiquitination indicates that these two PTMs are mutually exclusive. By contrast, the BTPC: (i) is abundant in the inner integument, cotyledon, and endosperm of developing COS, but occurs at low levels in roots and cotyledons of germinated COS, (ii) shows a unique developmental pattern in leaves such that it is present in leaf buds and young expanding leaves, but undetectable in fully expanded leaves, and (iii) tightly interacts with co-expressed PTPC to form the novel and allosterically-desensitized Class-2 PEPC heteromeric complex. BTPC and thus Class-2 PEPC up-regulation appears to be a distinctive feature of rapidly growing and/or biosynthetically active tissues that require a large anaplerotic flux from phosphoenolpyruvate to replenish tricarboxylic acid cycle C-skeletons being withdrawn for anabolism.


Subject(s)
Isoenzymes/metabolism , Phosphoenolpyruvate Carboxylase/metabolism , Plant Proteins/metabolism , Ricinus/enzymology , Isoenzymes/genetics , Phosphoenolpyruvate Carboxylase/genetics , Phosphorylation , Plant Proteins/genetics , Protein Binding , Protein Processing, Post-Translational/genetics , Protein Processing, Post-Translational/physiology , Ricinus/genetics , Ricinus/metabolism
7.
Biochem J ; 433(1): 65-74, 2011 Jan 01.
Article in English | MEDLINE | ID: mdl-20950272

ABSTRACT

PEPC [PEP (phosphoenolpyruvate) carboxylase] is a tightly controlled anaplerotic enzyme situated at a pivotal branch point of plant carbohydrate metabolism. Two distinct oligomeric PEPC classes were discovered in developing COS (castor oil seeds). Class-1 PEPC is a typical homotetramer of 107 kDa PTPC (plant-type PEPC) subunits, whereas the novel 910-kDa Class-2 PEPC hetero-octamer arises from a tight interaction between Class-1 PEPC and 118 kDa BTPC (bacterial-type PEPC) subunits. Mass spectrometric analysis of immunopurified COS BTPC indicated that it is subject to in vivo proline-directed phosphorylation at Ser425. We show that immunoblots probed with phosphorylation site-specific antibodies demonstrated that Ser425 phosphorylation is promoted during COS development, becoming maximal at stage IX (maturation phase) or in response to depodding. Kinetic analyses of a recombinant, chimaeric Class-2 PEPC containing phosphomimetic BTPC mutant subunits (S425D) indicated that Ser425 phosphorylation results in significant BTPC inhibition by: (i) increasing its Km(PEP) 3-fold, (ii) reducing its I50 (L-malate and L-aspartate) values by 4.5- and 2.5-fold respectively, while (iii) decreasing its activity within the physiological pH range. The developmental pattern and kinetic influence of Ser425 BTPC phosphorylation is very distinct from the in vivo phosphorylation/activation of COS Class-1 PEPC's PTPC subunits at Ser11. Collectively, the results establish that BTPC's phospho-Ser425 content depends upon COS developmental and physiological status and that Ser425 phosphorylation attenuates the catalytic activity of BTPC subunits within a Class-2 PEPC complex. To the best of our knowledge, this study provides the first evidence for protein phosphorylation as a mechanism for the in vivo control of vascular plant BTPC activity.


Subject(s)
Phosphoenolpyruvate Carboxylase/metabolism , Ricinus communis/enzymology , Seeds/enzymology , Kinetics , Phosphoenolpyruvate Carboxylase/antagonists & inhibitors , Phosphorylation , Plant Proteins , Protein Processing, Post-Translational , Seeds/growth & development , Serine/metabolism
8.
J Biol Chem ; 284(37): 24797-805, 2009 Sep 11.
Article in English | MEDLINE | ID: mdl-19605358

ABSTRACT

Phosphoenolpyruvate carboxylase (PEPC) is a tightly regulated anaplerotic enzyme situated at a major branch point of the plant C metabolism. Two distinct oligomeric classes of PEPC occur in the triglyceride-rich endosperm of developing castor oil seeds (COS). Class-1 PEPC is a typical homotetramer composed of identical 107-kDa plant-type PEPC (PTPC) subunits (encoded by RcPpc3), whereas the novel Class-2 PEPC 910-kDa hetero-octameric complex arises from a tight interaction between Class-1 PEPC and distantly related 118-kDa bacterial-type PEPC (BTPC) polypeptides (encoded by RcPpc4). Here, COS BTPC was expressed from full-length RcPpc4 cDNA in Escherichia coli as an active PEPC that exhibited unusual properties relative to PTPCs, including a tendency to form large aggregates, enhanced thermal stability, a high K(m)((PEP)), and insensitivity to metabolite effectors. A chimeric 900-kDa Class-2 PEPC hetero-octamer having a 1:1 stoichiometry of BTPC:PTPC subunits was isolated from a mixture of clarified extracts containing recombinant RcPPC4 and an Arabidopsis thaliana Class-1 PEPC (the PTPC, AtPPC3). The purified Class-2 PEPC exhibited biphasic PEP saturation kinetics with high and low affinity sites attributed to its AtPPC3 and RcPPC4 subunits, respectively. The RcPPC4 subunits: (i) catalyzed the majority of the Class-2 PEPC V(max), particularly in the presence of the inhibitor l-malate, and (ii) also functioned as Class-2 PEPC regulatory subunits by modulating PEP binding and catalytic potential of its AtPPC3 subunits. BTPCs appear to associate with PTPCs to form stable Class-2 PEPC complexes in vivo that are hypothesized to maintain high flux from PEP under physiological conditions that would otherwise inhibit Class-1 PEPCs.


Subject(s)
Phosphoenolpyruvate Carboxylase/physiology , Arabidopsis/metabolism , Carbon/chemistry , Catalysis , Chromatography, Gel , Escherichia coli/metabolism , Eukaryota/metabolism , Hot Temperature , Kinetics , Models, Biological , Nitrogen/chemistry , Protein Binding , Protein Structure, Tertiary , Recombinant Proteins/chemistry , Temperature
9.
Plant J ; 52(5): 839-49, 2007 Dec.
Article in English | MEDLINE | ID: mdl-17894783

ABSTRACT

Two classes of phosphoenolpyruvate carboxylase (PEPC) sharing the same 107-kDa catalytic subunit (p107) were previously purified from developing castor oil seed (COS) endosperm. The association of p107 with an immunologically unrelated 64-kDa polypeptide (p64) causes pronounced physical and kinetic differences between the Class-1 PEPC p107 homotetramer and Class-2 PEPC p107/p64 hetero-octamer. Tryptic peptide sequencing matched p64 to the deduced C-terminal half of several bacterial-type PEPCs (BTPCs) of vascular plants. Immunoblots probed with anti-(COS p64 peptide or p107)-IgG established that: (i) BTPC exists in vivo as an approximately 118-kDa polypeptide (p118) that is rapidly truncated to p64 by an endogenous cysteine endopeptidase during incubation of COS extracts on ice, and (ii) mature and germinated COS contain Class-1 PEPC and p107, but no detectable Class-2 PEPC nor p118. Non-denaturing PAGE, in-gel PEPC activity staining and immunoblotting of developing COS extracts demonstrated that p118 and p107 are subunits of the non-proteolysed approximately 910-kDa Class-2 PEPC complex. As total PEPC activity of clarified COS extracts was unaffected following p118 truncation to p64, the BTPC p118 may function as a regulatory rather than catalytic subunit of the Class-2 PEPC. Moreover, recombinant AtPPC3 and AtPPC4 (Arabidopsis orthologs of COS p107 and p118) expressed as active and inactive PEPCs, respectively. Cloning of cDNAs encoding p118 (RcPpc4) and p107 (RcPpc3) confirmed their respective designation as bacterial- and plant-type PEPCs. Levels of RcPpc3 and RcPpc4 transcripts generally mirrored the respective amounts of p107 and p118. The collective findings provide insights into the molecular features and functional significance of vascular plant BTPCs.


Subject(s)
Phosphoenolpyruvate Carboxylase/metabolism , Plant Proteins/metabolism , Ricinus/embryology , Seeds/enzymology , Amino Acid Sequence , Arabidopsis/enzymology , Arabidopsis/genetics , Bacterial Proteins/chemistry , Cloning, Molecular , Cysteine Endopeptidases/metabolism , Immunoblotting , Molecular Sequence Data , Phosphoenolpyruvate Carboxylase/chemistry , Phosphoenolpyruvate Carboxylase/classification , Plant Proteins/chemistry , Plant Proteins/classification , Protein Isoforms/chemistry , Protein Isoforms/metabolism , RNA, Messenger/metabolism , Recombinant Fusion Proteins/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Ricinus/enzymology , Seeds/growth & development , Sequence Alignment , Sequence Analysis, Protein
10.
Photosynth Res ; 94(1): 43-57, 2007 Oct.
Article in English | MEDLINE | ID: mdl-17638114

ABSTRACT

Hydrilla verticillata has a facultative single-cell system that changes from C3 to C4 photosynthesis. A NADP+-dependent malic enzyme (NADP-ME) provides a high [CO2] for Rubisco fixation in the C4 leaf chloroplasts. Of three NADP-ME genes identified, only hvme1 was up-regulated in the C4 leaf, during the light period, and it possessed a putative transit peptide. Unlike obligate C4 species, H. verticillata exhibited only one plastidic isoform that may perform housekeeping functions, but is up-regulated as the photosynthetic decarboxylase. Of the two cytosolic forms, hvme2 and hvme3, the latter exhibited the greatest expression, but was not light-regulated. The mature isoform of hvme1 had a pI of 6.0 and a molecular mass of 64 kD, as did the recombinant rHVME1m, and it formed a tetramer in the chloroplast. The recombinant photosynthetic isoform showed intermediate characteristics between isoforms in terrestrial C3 and C4 species. The catalytic efficiency of rHVME1m was four-fold higher than the cytosolic rHVME3 and two-fold higher than recombinant cytosolic isoforms of rice, but lower than plastidic forms of maize. The Km (malate) of 0.6 mM for rHVME1 was higher than maize plastid isoforms, but four-fold lower than found with rice. A comprehensive phylogenetic analysis of 25 taxa suggested that chloroplastic NADP-ME isoforms arose from four duplication events, and hvme1 was derived from cytosolic hvme3. The chloroplastic eudicot sequences were a monophyletic group derived from a cytosolic clade after the eudicot and monocot lineages separated, while the monocots formed a polyphyletic group. The findings support the hypothesis that a NADP-ME isoform with specific and unusual regulatory properties facilitates the functioning of the single-cell C4 system in H. verticillata.


Subject(s)
Hydrocharitaceae/enzymology , Malate Dehydrogenase/genetics , Malate Dehydrogenase/metabolism , Cloning, Molecular , Computational Biology , DNA, Complementary/genetics , Gene Expression Regulation, Enzymologic , Gene Expression Regulation, Plant , Hydrocharitaceae/genetics , Isoenzymes/genetics , Isoenzymes/isolation & purification , Isoenzymes/metabolism , Kinetics , Malate Dehydrogenase/classification , Malate Dehydrogenase/isolation & purification , Phylogeny , Promoter Regions, Genetic/genetics , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Transcription, Genetic/genetics
11.
Plant Cell Physiol ; 47(9): 1206-16, 2006 Sep.
Article in English | MEDLINE | ID: mdl-16936335

ABSTRACT

The submersed monocot, Hydrilla verticillata (L.f.) Royle, is a facultative C(4) NADP-malic enzyme (NADP-ME) plant in which the C(4) and Calvin cycles co-exist in the same cell. Futile cycling is avoided by an intracellular separation of carboxylases between the cytosol and chloroplasts. Of the two sequenced H. verticillata phosphoenolpyruvate carboxylase (PEPC) isoforms, hvpepc3 and hvpepc4, transcript expression of the latter was substantially up-regulated during C(4) induction, especially in the light. Western blots revealed two PEPC-specific bands in C(3) and C(4) leaf extracts; the lower band dominated in the C(4) and underwent post-translational phosphorylation in the light as determined by immunological studies. This band probably represents the photosynthetic isoform, HVPEPC4, despite the lack of the C(4) signature serine (Flaveria residue 774; Hydrilla 779). In C(4) leaves, PEPC activity increased 14-fold, was enhanced by leaf exposure to light, and showed allosteric regulation. Glucose-6-phosphate acted as a positive effector, but malate was inhibitory, with I(50) values of 0.4 and 0.2 mM in the light and dark, respectively, similar to those of other C(4) PEPC isoforms. In contrast, in C(3) leaves, transcript expression of both isoforms was weak, with little evidence of diel regulation, and the PEPC proteins showed essentially no indication of phosphorylation. PEPC activity in C(3) leaves was low, light independent and followed Michaelis-Menten kinetics. It was tolerant to malate, with 10-fold higher I(50) values than the PEPC from C(4) leaves. These data suggest that hvpepc4 encodes the C(4) photosynthetic PEPC, and hvpepc3 encodes an anaplerotic form.


Subject(s)
Hydrocharitaceae/enzymology , Hydrocharitaceae/genetics , Phosphoenolpyruvate Carboxylase/genetics , Phosphoenolpyruvate Carboxylase/metabolism , Gene Expression Regulation, Plant , Genes, Plant , Isoenzymes/genetics , Isoenzymes/metabolism , Kinetics , Photosynthesis , Plant Leaves/enzymology , Plant Proteins
12.
Photosynth Res ; 88(2): 173-83, 2006 May.
Article in English | MEDLINE | ID: mdl-16622782

ABSTRACT

The aquatic monocot Hydrilla verticillata (L.f.) Royle is a well-documented facultative C4 NADP-malic enzyme species in which the C4 and Calvin cycles operate in the same cell with the specific carboxylases confined to the cytosol and chloroplast, respectively. Several key components had already been characterized at the molecular level, thus the purpose of this study was to begin to identify other, less obvious, elements that may be necessary for a functional single-cell C4 system. Using differential display, mRNA populations from C3 and C4 H. verticillata leaves were screened and expression profiles compared. From this study, 65 clones were isolated and subjected to a customized macroarray analysis; 25 clones were found to be upregulated in C4 leaves. Northern and semi-quantitative RT-PCR analyses were used for confirmation. From these screenings, 13 C4 upregulated genes were identified. Among these one encoded a previously recognized C4 phosphoenolpyruvate carboxylase, and two encoded distinct pyruvate orthophosphate dikinase isoforms, new findings for H. verticillata. Genes that encode a transporter, an aminotransferase and two chaperonins were also upregulated. Twelve false positives, mostly housekeeping genes, were determined from the Northern/semi-quantitative RT-PCR analyses. Sequence data obtained in this study are listed in the dbEST database (DV216698 to DV216767). As a single-cell C4 system that lacks Kranz anatomy, a better understanding of how H. verticillata operates may facilitate the design of a transgenic C4 system in a C3 crop species.


Subject(s)
Gene Expression Profiling , Gene Expression Regulation, Plant/physiology , Genes, Plant , Hydrocharitaceae/genetics , Hydrocharitaceae/physiology , Plant Leaves/metabolism , RNA, Plant/metabolism
13.
Plant Physiol ; 130(2): 876-86, 2002 Oct.
Article in English | MEDLINE | ID: mdl-12376652

ABSTRACT

The submersed monocot Hydrilla verticillata (L.f.) Royle is a facultative C(4) plant. It typically exhibits C(3) photosynthetic characteristics, but exposure to low [CO(2)] induces a C(4) system in which the C(4) and Calvin cycles co-exist in the same cell and the initial fixation in the light is catalyzed by phosphoenolpyruvate carboxylase (PEPC). Three full-length cDNAs encoding PEPC were isolated from H. verticillata, two from leaves and one from root. The sequences were 95% to 99% identical and shared a 75% to 85% similarity with other plant PEPCs. Transcript studies revealed that one isoform, Hvpepc4, was exclusively expressed in leaves during C(4) induction. This and enzyme kinetic data were consistent with it being the C(4) photosynthesis isoform. However, the C(4) signature serine of terrestrial plant C(4) isoforms was absent in this and the other H. verticillata sequences. Instead, alanine, typical of C(3) sequences, was present. Western analyses of C(3) and C(4) leaf extracts after anion-exchange chromatography showed similar dominant PEPC-specific bands at 110 kD. In phylogenetic analyses, the sequences grouped with C(3), non-graminaceous C(4), and Crassulacean acid metabolism PEPCs but not with the graminaceous C(4), and formed a clade with a gymnosperm, which is consistent with H. verticillata PEPC predating that of other C(4) angiosperms.


Subject(s)
Hydrocharitaceae/genetics , Phosphoenolpyruvate Carboxylase/metabolism , Photosynthesis/physiology , Amino Acid Sequence , Blotting, Western , Cloning, Molecular , DNA, Complementary , Gene Expression Regulation, Enzymologic , Gene Expression Regulation, Plant , Hydrocharitaceae/cytology , Hydrocharitaceae/enzymology , Isoenzymes/genetics , Isoenzymes/metabolism , Kinetics , Molecular Sequence Data , Phosphoenolpyruvate Carboxylase/genetics , Phosphoenolpyruvate Carboxylase/isolation & purification , Photosynthetic Reaction Center Complex Proteins/classification , Photosynthetic Reaction Center Complex Proteins/metabolism , Phylogeny , Plant Leaves/enzymology , Plant Leaves/genetics , Plant Roots/enzymology , Plant Roots/genetics
14.
Funct Plant Biol ; 29(3): 379-392, 2002 Apr.
Article in English | MEDLINE | ID: mdl-32689483

ABSTRACT

Aquatic C4 photosynthesis probably arose in response to dissolved CO2 limitations, possibly before its advent in terrestrial plants. Of over 7600 C4 species, only about a dozen aquatic species are identified. Amphibious Eleocharis species (sedges) have C3-C4 photosynthesis and Kranz anatomy in aerial, but not submersed, leaves. Aquatic grasses have aerial and submersed leaves with C4 or C3-C4 photosynthesis and Kranz anatomy, but some lack Kranz anatomy in the submersed leaves. Two freshwater submersed monocots, Hydrilla verticillata and possibly Egeria densa, are C4 NADP-malic enzyme (NADP-ME) species. A marine macroalga, Udotea flabellum (Chlorophyta), and possibly a diatom, are C4, so it is not confined to angiosperms. Submersed C4 species differ from terrestrial in that ß-carboxylation is cytosolic with chloroplastic decarboxylation and Rubisco carboxylation, so the C4 and Calvin cycles operate in the same cell without Kranz anatomy. Unlike terrestrial plants, Hydrilla is a facultative C4 that shifts from C3 to C4 in low [CO2]. It is well documented, with C4 gas exchange and pulse-chase characteristics, enzyme kinetics and localization, high internal [CO2], relative growth rate, and quantum yield studies. It has multiple phosphoenolpyruvate carboxylase isoforms with C3-like sequences. Hvpepc4 appears to be the photosynthetic form induced in C4 leaves, but it differs from terrestrial C4 isoforms in lacking a C4 signature Serine. The molecular mass of NADP-ME (72 kDa) also resembles a C3 isoform. Hydrilla belongs to the ancient Hydrocharitaceae family, and gives insight to early C4 development. Hydrilla is an excellent 'minimalist' system to study C4 photosynthesis regulation without anatomical complexities.

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