Vacuolar pH in radish cotyledonal mesophyll cells

The vacuolar pH in cotyledonal mesophyll cells from radish (Raphanus sativus L. var. sativus) seedlings was determined from vacuoles, isolated from protoplasts through osmotic shock, by means of measurement of vacuole extracts with a pH meter and the "methylamine method", and gave mean pH values of 6.28 and 6.26, respectively. Direct in situ measurements of the vacuolar pH from intact leaf tissue were recorded with pH-sensitive microelectrodes and gave a mean value of 6.0. The results are discussed with respect to possible erroneous pH measurements and the vacuolar location of specific anabolic reactions.

Enzymic synthesis of caffeoylglucaric Acid from chlorogenic Acid and glucaric Acid by a protein preparation from tomato cotyledons

The phenylpropane metabolism of tomato (Lycopersicon esculentum Mill) cotyledons was investigated. The HPLC analysis revealed two hydroxycinnamic-acid conjugates as major components, identified as chlorogenic acid (5-O-caffeoylquinic acid) and caffeoylglucaric acid (2-O- or 5-O-caffeoyl-glucaric acid). Quantitative analyses indicated a precursor-product relationship between the chlorogenic and caffeoylglucaric acids. Protein preparations from tomato cotyledons were found to catalyze the formation of caffeoylglucaric acid with chlorogenic acid as acyl donor and free glucaric acid as acceptor molecule. This enzyme activity, possibly to be classified as hydroxycinnamoylquinic acid:glucaric acid hydroxycinnamoyltransferase, acts together with hydroxycinnamoyl-CoA: quinic acid hydroxycinnamoyltransferase.

The role of malate in ammonia assimilation in cotyledons of radish (Raphanus sativus L.)

The relationships between the metabolism of malate, nitrogen assimilation and biosynthesis of amino acids in response to different nitrogen sources (nitrate and ammonium) have been examined in cotyledons of radish (Raphanus sativus L.). Measurements of the activities of some key enzymes and pulse-chase experiments with [(14)C]malate indicate the operation of an anaplerotic pathway for malate, which is involved in the synthesis of glutamine during increased ammonia assimilation. It is most likely that the tricarboxylicacid cycle is supplied with carbon through entry of malate, formed via the phosphoenolpyruvate (PEP)-carboxylation pathway, when 2-oxoglutarate leaves the cycle to serve as precursor for an increased synthesis of glutamine via glutamate. This might occur predominantly in the cytosol via the activity of the glutamine synthetase/glutamate synthase (GS/GOGAT) cycle, the NADH-dependent GOGAT being the rate-limiting activity.

Evidence for a relationship between malate metabolism and activity of 1-sinapoylglucose: L-malate sinapoyltransferase in radish (Raphanus sativus L.) cotyledons

The control of malate metabolism and stimulation of 1-sinapolyglucose: L-malate sinapoyltransferase (SMT) activity in radish (Raphanus sativus L. var. sativus) cotyledons has been studied. The light-induced and nitrate-dependent activity of SMT catalyzes the formation of O-sinapoly-L-malate via 1-O-sinapoyl-β-D-glucose. When dark-grown radish seedlings, cultivated in quartz sand with nutrient solution containing NO 3 (-) as the sole N source, were treated with light, SMT activity increased concomitantly with free malate in the cotyledons. This light effect was suppressed in seedlings grown in a culture medium which contained in addition to NO 3 (-) also NH 4 (+) . However, treatment with methionine sulfoximine neutralized this ammonium effect, resulting again in both rapid accumulation of malate and rapid increase in SMT activity. When seedlings grown on NO 3 (-) nitrogen were subsequently supplied with NH 4 (+) nitrogen, the accumulated level of L-malate rapidly dropped and the SMT increase ceased. The enzyme activity decreased later on, reaching the low activity level of plants which were grown permanently on NO 3 (-) /NH 4 (+) -nitrogen. An external supply (vacuum infiltration) of malate to excised cotyledons and intact seedings, grown on NO 3 (-) /NH 4 (+) -nitrogen medium, specifically promoted a dose-dependent increase in the activity of SMT. In summary these results provide evidence indicating that the SMT activity in cotyledons of Raphanus sativus might be related to the metabolism of malic acid.

Tissue distribution of phenylpropanoid metabolism in cotyledons of Raphanus sativus L

The tissue distributions of sinapic acid esters (1-sinapoylglucose, sinapolyl-L-malate, 6,3'-disinapoylsucrose), kaempferol glycosides, free malic acid and of the enzyme involved in the synthesis of sinapoyl-L-malate, 1-sinapoylglucose: L-malate sinapoyltransferase (SMT), have been investigated in cotyledons of Raphanus sativus L. seedlings. The kaempferol glycosides were mainly localized in the upper epidermis. The sinapoyl esters were found in all tissues, but differed markedly in their concentrations. While disinapoylsucrose was localized predominantly in the mesophyll, most sinapoylmalate was found in the epidermal layers, as was most SMT activity. Ultraviolet microscopy and microfluorospectrophotometry of isolated epidermal peels indicated that the epidermal sinapoyl esters were restricted to guard cells, guard mother cells and adjacent epidermal cells. Upon excitation by UV light (365 nm) these exhibited strong blue fluorescence with an emission maximum at about 480 nm. Our results indicate a highly tissue-and cell-specific secondary metabolism in Raphanus cotyledons and indicate that the biosynthesis of sinapoylmalate is intimately related to the malic-acid metabolism of the guard cells.

Vacuolar localization of 1-sinapolglucose: L-malate sinapoyltransferase in protoplasts from cotyledons of Raphanus sativus

The distribution of L-malate, sinapic acid esters and 1-sinapoylglucose: L-malate sinapoyltransferase (SMT) which catalyzes the synthesis of sinapoyl-L-malate were examined in preparations of protoplasts obtained from cotyledons of red radish (Raphanus sativus L. var. sativus). Vacuoles isolated from the protoplasts contained all of the SMT activity, all of the accumulated sinapic acid esters and about 50% of free L-malate present initially in the protoplasts. An esterase activity, acting on 1-sinapoyglucose, was found to be exclusively localized in the cytoplasm and a large proportion was found to be recoverable in a 100 000-g pellet obtained from protoplast lysates. The vacuoles were obtained after lysis of the protoplasts by osmotic shock and purification on a Ficoll gradient. The cytoplasmic contamination of vacuole preparations was found to be about 10%, as judged by enzymatic markers and microscopic inspection. No SMT activity was found in a 100 000-g pellet obtained from vacuole lysates. The results indicate that biosynthesis of sinapoyl-L-malate takes place within the central vacuoles of redradish cotyledons.

The systematic distribution of ferulic Acid-sucrose esters in anthers of the liliaceae1

In an anther survey of 157 di- and monocotyledons, two very rare cinnamic acid conjugates-di- and triferuloylsucrose-were found to occur exclusively in the Liliales and most predominantly in the Liliaceae (Tulipeae, Lilieae, Lloydieae). Whereas the triferuloyl ester was found to be abundant in most of the 20 species and cultivars of TULIPA investigated, only the diferuloyl ester could be detected by the applied methods in FRITILLARIA and LILIUM, in 12 and 9 species and cultivars, respectively. Di- and/or triferuloylsucrose could also be detected in one GAGEA and three ERYTHRONIUM species. Three out of 20 IRIS species investigated, also show the occurrence of these rare esters. This sporadic appearance in IRIS is, at present, considered to be erratic. We suggest that the ferulic acid-sucrose esters might be useful as marker substances for the Liliaceae.

Nitrogen nutrition and the accumulation of free and sinapoyl-bound malic acid in Raphanus sativus cotyledons

Seedlings of red radish (Raphanus sativus L. var. sativus) accumulated high amounts of free malic acid and sinapoylmalate, when grown on nitrate as the sole N-source. In the presence of ammonium (NO 3 (-) : NH 4 (+) , 1:2) both metabolites failed to accumulate, and the levels of arginine, asparagine, glutamine, histidine, and serine were greatly increased. The extractable activity of 1-sinapoylglucose: L-malate sinapoyltransferase, an enzyme which plays a key role in channelling malic acid into the sinapic-acid metabolism of this plant, was positively correlated with the malic-acid level in cotyledons. The possibility is discussed that free malic acid might be the likely candidate for regulating the activity of 1-sinapoylglucose: L-malate sinapoyltransferase.

High Performance Liquid Chromatographic Separation of Isoflavones and Structural Elucidation of Isoflavone 7-O-glucoside 6''-malonates from Cicer arietinum

An efficient separation by HPLC of isoflavone aglycones and glucosides on reversed - phase columns is described. The main isoflavone constituents of CICER ARIETINUM L., various TRIFOLIUM species, BAPTISIA AUSTRALIS L. and ONONIS SPINOSA L. are formononetin 7-O-glucoside 6''-malonate and biochanin A 7-O-glucoside 6''-malonate.

alpha-Adrenoreceptor stimulation of the systemic circulation in dogs

The influence of phenylephrine (an alpha-adrenoreceptor agonist) on the arterial and venous systems of the systemic circulation was studied in 10 anesthetized dogs during a right ventricular bypass procedure. Phenylephrine (1 microgram X kg-1 of body weight X min-1) produced a significant (P less than 0.001) increase in arterial resistance, no change in venous resistance, and a mild decrease in venous compliance. Seemingly in the clinically normal dog, a dose of phenylephrine sufficient to double total peripheral resistance will redistribute a small amount of blood volume from the venous to arterial systems with a slight decrease in venous return and concomitant attenuation of cardiac output.

Valved apico-aortic conduit for relief of left ventricular hypertension caused by discrete subaortic stenosis in dogs

A double-outlet left ventricle (LV), with a valved conduit interposed between the LV apex and the aorta, was created in 7 dogs with subaortic stenosis. Of 8 dogs in which the implantation was attempted, 1 died following thoracotomy but before conduit implantation could be performed, 1 died from hemorrhage 24 hours after surgery, 1 died from septicemia as a sequel to pneumonia 10 days after surgery, 1 died from "shock-lung" 4 days after surgery, and 4 were functionally normal 22, 12, 6, and 2 months after surgery. In the 7 dogs in which the implantation was completed, the mean LV to aorta (LV-Ao) pressure gradient was significantly (P less than 0.01) reduced by the implantation. Diastolic and systolic murmurs were detected over the prosthetic valve area in 3 of the 4 surviving dogs 1 to 4 days postoperatively, but the murmurs gradually decreased in intensity until they disappeared after 1 month. The 4 survivors had no angiographic evidence of prosthetic valve insufficiency at 2 months or at 1 year. In 3 of the survivors, the LV-Ao pressure gradients 2 months postoperatively were 45, 20, and 0 mm of Hg, as compared with 120, 90, and 50 mm of Hg preoperatively. Postoperative pressure measurements were not obtained on 1 surviving dog.

Effects of the spleen, epinephrine, and splenectomy on determination of blood volume in cats

Blood volume (BV), RBC mass, plasma protein (PP), and PCV were determined in (i) awake, nonsplenectomized (NSPX) cats before and after splenic contraction was induced by IV administration of epinephrine, (ii) in pentobarbital-anesthetized, NSPX cats before and after splenic contraction was induced by epinephrine and splenectomy, and (iii) in awake, splenectomized (SPX) cats before and after epinephrine was administered. Blood volume, absolute RBC mass in the spleen could not be determined accurately in awake or anesthetized, NSPX cats. Accurate BV and RBC mass determinations could only be obtained in cats without the spleen; mean BV and RBC mass of awake or anesthetized, SPX cats were 4.1% and 1.4% or body weight, respectively. The spleen was a dynamic sequestering organ for feline erythrocytes (RBC). Epinephrine (0.1 ml of 1:1,000) given IV resulted in the observed contraction of the spleen within 2 minutes. Relaxation of the spleen with RBC uptake began 3 minutes after epinephrine was given and it proceeded at a rate of approximately 0.93% of circulating PCV/min. At 20 minutes after epinephrine was given, a steady state of PCV occurred, and 20% of the maximum circulating PCV observed after the administration of epinephrine was stored within the spleen. At 60 minutes after epinephrine was given to awake, SPX cats, intravascular fluid influx of 4 ml/kg resulted in a decrease of PCV and PP. At 3 hours after splenectomy was done, intravascular fluid efflux resulted in hemoconcentration--a calculated fluid deficit of 2.5 ml/kg/hr occurring during the 3 hours after surgical removal of the spleen.

Blood volume of nonsplenectomized and splenectomized cats before and after acute hemorrhage

Blood volume (BV) was determined in awake, nonsplenectomized (NSPX) and splenectomized (SPX) cats before and after hemorrhage (6 ml/kg). Each NSPX cat had a determined BV at least 10 ml/kg greater than the same cat after splenectomy. The mean BV of SPX cats was 43.4 +/- 8.94. ml kg (4.3% of body weight). The calculated RBC masses of NSPX and SPX cats were 17.0 +/- 4.07 and 12.2 +/- 1.12 ml/kg, respectively. Each NSPX cat had apparent RBC masses of 5 ml/kg greater than that of the same cat after splenectomy was done. At 1 hour after a hemorrhage, the BV and RBC masses determined in SPX cats were 46.7 +/- 12.1 and 9.7 +/- 1.90 ml/kg, respectively. Extravascular-to-intravascular fluid flux (calculated from RBC masses and plasma protein dilution) was approximately 0.80% of body weight. The indirect method with 51Cr-labeled RBC for BV determination was accurate and precise in awake, SPX cats; in awake, NSPX cats, the 51Cr-labeled RBC dilution method was precise, but not accurate. The spleen in the cat resulted in marked overestimations of BV and RBC masses.

Development of 1-O-sinapoyl-β-D-glucose: L-malate sinapoyltransferase activity in cotyledons of red radish (Raphanus sativus L. var. sativus)

Protein preparations from cotyledons of red radish (Raphanus sativus L. var. sativus) catalyzed the the formation of depsides between cinnamic acids and L-malate, using 1-O-acyl glucose conjugates as the donors. This activity showed an absolute acceptor specificity towards L-malate and a pronounced donor specificity with 1-sinapoylglucose (1-O-sinapoyl-β-D-glucose). Maximal rate of sinapoyl-L-malate formation was found to be at pH 6.3, and there was no requirement for metal ions or sulfhydryl group reagents. The K m values were found to be 0.46 mM for 1-sinapoylglucose and 54 mM for L-malate. Protein extracts obtained from seedlings at different stages of seedling development did not significantly differ with respect to the properties of the enzymatic activity. Appearance and development of extractable activities correlated well with the in vivo transacylation kinetics of 1-sinapoylglucose to sinapoyl-L-malate during seedling growth. Maximal activity was extracted from 10-14-d-old seedlings and found to be at 67 pkat pair(-1) of cotyledons. This new enzymatic activity in phenylpropanoid metabolism refers to an enzyme which can be classified as 1-sinapoylglucose: L-malate sinapoyltransferase (SMT) (EC 2.3.1.-).

Application of liquid chromatography to a study on 4-coumarate: coenzyme A ligase activity

This report describes the separation of components from a 4-coumarate:CoA ligase assay by means of liquid chromatography. With the aid of polyamide column chromatography it is possible to enrich and isolate chromatographically and UV spectroscopically pure p-coumaroyl-CoA using as a solvent 0.01% NH4OH in methanol subsequent to water and methanol alone. High performance liquid chromatography on octadecylsilane-bonded silica stationary phase allows a discontinuous determination of ligase activity. All components - ATP, Coenzyme A, p-coumaric acid, and the products AMP and p-coumaroyl-CoA - can be separated and accurately quantified within 20 min using a water-acetonitrile gradient, containing 1% phosphoric acid. The presented HPLC method may be used to affirm the accuracy of optical tests.