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Biomedical subjects

C A Ryan

Publications and source records attributed to C A Ryan.

At least 217 records · Page 12Linked to original sources
PubMed1985

Wound-induced trypsin inhibitor in alfalfa leaves: identity as a member of the Bowman-Birk inhibitor family.

The primary structure of the wound-inducible trypsin inhibitor from alfalfa (ATI) establishes it as a member of the Bowman-Birk proteinase inhibitor family. The time course of induction of ATI in alfalfa following wounding is similar to the induction of the nonhomologous proteinase inhibitors I and II in tomato and potato leaves, and, like inhibitors I and II, ATI is induced to accumulate in excised leaves supplied with the proteinase inhibitor inducing factor from tomato leaves. The similarity of the wound induction of ATI to that of inhibitors I and II indicates that wound-regulated systems are present in Solanaceae and Leguminosae plant families that possess a common fundamental recognition system regulating synthesis of proteinase inhibitors in response to pest attacks. ATI is the first Bowman-Birk inhibitor that has been found in leaves and is the only member of this family known to be regulated by wounding.

Amino Acid Sequence↗
PubMed1985

Vacuolar localization of wound-induced carboxypeptidase inhibitor in potato leaves.

The wound-induced carboxypeptidase inhibitor in potato leaves was shown to be localized in the central vacuoles of the cells. The inhibitor was quantified by immunological assays (ELISA) in protoplasts and vacuoles isolated from upper unwounded leaves of 5- to 6-week old potato plants that had been wounded on their lower leaves 48 hours earlier to induce the accumulation of the carboxypeptidase inhibitor. The regulation of the synthesis and compartmentation of the inhibitor is similar to that of wound-induced serine proteinase Inhibitors I and II in potato and tomato leaves and appears to be part of an induced defense response against attacking pests.

Journal Article↗
PubMed1985

Stimulation of prostacyclin production in isolated rat adipocytes by angiotensin II, vasopressin, and bradykinin: evidence for two separate mechanisms of prostaglandin synthesis.

We compared the effects of three vasoactive peptides (angiotensin II, vasopressin, and bradykinin) and norepinephrine on the production of prostaglandin I2 [prostacyclin (PGI2)] and PGE2 by isolated rat adipocytes. Angiotensin II, vasopressin, and bradykinin stimulated PGI2 production but had minimal or no effect on PGE2 production or triglyceride lipolysis in isolated rat adipocytes, while norepinephrine stimulated PGI2 production, PGE2 production, and triglyceride lipolysis. The arachidonic acid that serves as substrate for PGI2 production in adipocytes in response to the vasoactive peptides appears to be derived from the cellular phospholipids rather than the triglycerides in these triglyceride-laden cells. The adipocyte contains two separate mechanisms for PG production: 1) a catecholamine-stimulated mechanism for the production of PGI2 and PGE2 that is activated concomitantly with triglyceride lipolysis, and 2) a mechanism activated by vasoactive peptides for the stimulation of PGI2 production independent of triglyceride lipolysis and PGE2 production. These mechanisms may have distinct functions.

Adipose Tissue↗
PubMed1984

Isolation and characterization of the proteinase inhibitor-inducing factor from tomato leaves. Identity and activity of poly- and oligogalacturonide fragments.

Mild acid hydrolysis of a small (Mr = 6 kDa) pectic polysaccharide isolated from tomato leaves, an inducer of the synthesis and accumulation of two proteinase inhibitors in excised tomato plants, yielded a alpha-D-polygalacturonic acid polymer with degree of polymerization = 20 that retained proteinase inhibitor-inducing activity. Enzymic and acid hydrolysis of this polygalacturonan yielded a series of alpha-1,4-D-galacturonic acid oligomers with degrees of polymerization from 2 to 6 which were purified to homogeneity and assayed for proteinase inhibitor-inducing activity in young excised tomato plants. All of the oligomers exhibited activity. The hexagalacturonide possessed the highest activity and the trimer the lowest. The evidence supports a possible role for plant cell wall fragments as systemic messengers that regulate the expression of proteinase inhibitor genes in plant leaves in response to pest attacks.

Carbohydrates↗
PubMed1984

Isolation and characterization of a wound-induced trypsin inhibitor from alfalfa leaves.

A trypsin inhibitor from leaves of field-grown alfalfa plants has been purified and shown to be the same trypsin inhibitor that is wound induced in leaves of young growth chamber grown plants. This inhibitor accounts for the major trypsin inhibitory activity found in both field-grown and wound-induced plants. The inhibitor exhibits a molecular weight of about 7500 and is specific for trypsin with a Ki of 1 X 10(-10) M. Analysis of the purified inhibitor by cation-exchange high-performance liquid chromatography revealed the presence of four isoinhibitor species that have identical immunological and inhibitory properties. The amino acid analysis of the four species indicates small but significant differences. Immunological double diffusion comparisons of the alfalfa inhibitor with the Bowman-Birk and Kunitz soybean inhibitors did not reveal any cross-reactivity although the amino acid content of the alfalfa inhibitor resembles those of Bowman-Birk family members.

Amino Acids↗
PubMed1984

Isolation and characterization of proteinase inhibitor I from etiolated tobacco leaves.

Proteinase Inhibitor I was induced to accumulate in tobacco (Nicotiana tabaccum) leaves by placing plants in darkness for 10 days at 27 degrees C. The inhibitor was isolated using ammonium sulfate precipitation, Sephadex G-75 chromatography, heating, and affinity chromatography with a chymotrypsin-Sepharose column. Inhibitor I was purified 232-fold with a yield of 34 mg from 2.5 kg of leaves. Affinity-purified tobacco Inhibitor I was shown to be homogeneous by gel electrophoresis in both nondissociating and dissociating buffers. The inhibitor has a molecular weight of 39,000 +/- 1000 determined by gel filtration and, like its potato and tomato counterparts, is composed of five subunits of molecular weight 8100. The tobacco Inhibitor I strongly inhibits chymotrypsin and weakly inhibits trypsin. The chemical, physical, and immunological properties of tobacco Inhibitor I indicate that it is structurally very similar to potato tuber Inhibitor I and tomato leaf Inhibitor I, although the synthesis and accumulation of the three inhibitors in their respective tissues are all under different developmental or environmental regulation.

Chemical Phenomena↗
PubMed1984

Nutritional studies of a carboxypeptidase inhibitor from potato tubers.

Carboxypeptidase inhibitor from potato tubers was fed to newly hatched chicks at a level equal to that present in diet containing 50% raw potato, which caused severe growth depression and 20% mortality. At this level the effects of the inhibitor on growth was small but the following effects were noted: (a) increased fecal protein (the increase mainly consisting of low molecular weight proteins); (b) poorer feed efficiency; and (c) a significant decrease in pancreatic digestive proenzyme levels, although no hypertrophy was noted. In addition, the inhibitor was not digested readily in the intestinal tract and it increased in concentration in intestinal contents as it progressed down the tract. Potato Inhibitor II, a potent trypsin inhibitor, when fed to chicks, also at the level found in a 50% raw potato diet, was severely growth depressing. It significantly increased fecal protein and caused pancreatic hypertrophy. The trypsin inhibitor may be a major growth depressing agent in raw potatoes whereas the carboxypeptidase inhibitor probably contributes little to the growth depression.

Animals↗
PubMed1984

Wound signals in plants: A systemic plant wound signal alters plasma membrane integrity.

Within 4 hr after wounding the lower leaves of young potato and tomato plants, a rapid and remarkable change is induced in the cells of upper undamaged leaves that results in extensive lysis of protoplasts during their isolation. Protoplast yields from unwounded upper leaves, 4 hr after wounding a lower leaf by crushing with a hemostat, decreased 25% below yields from leaves of unwounded plants. From 8 to >20 hr after wounding, protoplast yields were less than half of those from control plants. Multiple woundings decreased yields even further, as did chewing of the lower leaves by tobacco hornworms over a period of several minutes. In addition, within 4 hr of excising young tomato plants at their base with a razor blade, a 90% decrease in leaf protoplast yields was recorded. The major loss of protoplasts induced by wounding was primarily due to an increased cell lysis during protoplast isolation. Cell lysis was apparently due to a weakened cell membrane, because newly recovered protoplasts released from leaves of wounded plants were extremely fragile and exhibited 70% lysis during low speed centrifugation, compared to 20% lysis of protoplasts recovered from control plants. We conclude that a signal is released by wounding that is rapidly transmitted or transported through the plants to induce a profound change in the leaf cell membranes that renders them fragile during protoplast isolation. It is proposed that this signal may play a role in inducing cellular changes in the plant cells as part of their responses to environmental stress such as pest attacks.

Journal Article↗
PubMed1984

Proteinase inhibitor synthesis in tomato leaves : induction by chitosan oligomers and chemically modified chitosan and chitin.

Soluble chemical derivatives of chitin and chitosan including ethylene glycol chitin, nitrous acid-modified chitosan, glycol chitosan, and chitosan oligomers, produced from chitosan by limited hydrolysis with HCl, were found to possess proteinase inhibitor inducing activities when supplied to young excised tomato (Lycopersicon esculentum var Bonnie Best) plants. Nitrous acid-modified chitosans and ethylene glycol chitin exhibited about 2 to 3 times the activity of acid hydrolyzed chitosan and 15 times more activity than glycol chitosan. The parent chitin and chitosans are insoluble in water or neutral buffers and cannot be assayed. Glucosamine and its oligomers from degree of polymerization = 2 through degree of polymerization = 6 were purified from acid-fragmented chitosan and assayed. The monomer was inactive and dimer and trimer exhibited weak activities. Tetramer possessed higher activity and the larger pentamer and hexamer oligomers were nearly as active as the total hydrolyzed mixture. None of the fragments exhibited more than 2% acetylation (the limits of detection). The contents of the acid-fragmented mixture of oligomers was chemically N-acetylated to levels of 13% and 20% and assayed. The N-acetylation neither inhibited nor enhanced the proteinase inhibitor inducing activity of the mixture. These results, along with recent findings by others that chitinases and chitosanases are present in plants, provide further evidence for a possible role of soluble chitosan fragments as signals to activate plant defense responses.

Journal Article↗
PubMed1984

Comparison of proteinase inhibitor-inducing activities and phytoalexin elicitor activities of a pure fungal endopolygalacturonase, pectic fragments, and chitosans.

Rhizopus stolonifer endopolygalacturonase, an elicitor of casbene synthetase activity in castor bean seedlings, was found to be a potent elicitor of the phytoalexin pisatin in pea pods and of proteinase Inhibitor I in tomato leaves. The enzyme was an active elicitor or inducer only in its active native state; heat-denatured enzyme was inactive in all three systems. The activities of (a) the tomato pectic polysaccharide proteinase inhibitor-inducing factor, (b) a partially acid hydrolyzed proteinase inhibitor-inducing factor, (c) citrus pectic fragments, and (d) chitosan, were also compared in the three bioassay systems. The four oligosaccharide preparations were active in all three systems, but with different degrees of potency. In tomato leaves and pea pods, chitosans were most active, whereas in castor beans, the citrus pectic fragments were the best elicitors. The data presented support the hypothesis that plant and fungal cell wall fragments are important signals in mobilizing a wide variety of biochemically different types of plant defense responses, and that endopolygalacturonases play a key role in releasing the plant cell wall fragments during pest attacks.

Journal Article↗
PubMed1983

A rapid, large-scale method for purification of the metallo-carboxypeptidase inhibitor from potato tubers.

A rapid, large-scale procedure has been developed for the preparation of metallo-carboxypeptidase inhibitor (CPI) from potatoes. The inhibitor is extracted with 80% ethanol from partially cooked potato tubers. After the ethanol is removed and the salts are dialyzed away, the inhibitor is isolated in pure form by chromatography on sulfopropyl Sephadex. Ten pounds of potatoes yields 250 mg pure inhibitor, representing over 40% recovery. Commercial mashed potato flakes contain about 0.02% carboxypeptidase inhibitor and can be utilized as a starting material in the procedure described to yield over 70 mg inhibitor from a pound of flakes.

Hot Temperature↗
PubMed1983

Chitosans and pectic polysaccharides both induce the accumulation of the antifungal phytoalexin pisatin in pea pods and antinutrient proteinase inhibitors in tomato leaves.

The Proteinase Inhibitor Inducing Factor, PIIF, a pectic polysaccharide that induces synthesis and accumulation of proteinase inhibitor proteins in tomato and potato leaves, is an effective elicitor of the phytoalexin pisatin in pea pod tissues. The levels of pisatin induced by PIIF, and the time course of elicitation, are similar to those induced by chitosans, beta-1,4 glucosamine polymers, which are potent elicitors of pisatin in pea pods. Similarly, the chitosans, found in both insect and fungal cell walls, are the most potent inducers yet found of proteinase inhibitor accumulation in excised tomato cotyledons. The similarity in the induction of synthesis of proteinase inhibitors in tomato cotyledons and of pisatin in pea pods by pectic polysaccharides and chitosans suggests that the two polysaccharide types may be triggering a similar fundamental system present in pea and tomato plants that regulates the expression of genes for natural protection systems.

Benzopyrans↗
PubMed1983

Plant vacuoles.

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Cell Fractionation↗
PubMed1983

Effects of feeding a carboxypeptidase inhibitor from potatoes to newly hatched chicks.

For the first time, the effects on animal growth and protein digestion of a specific inhibitor of the pancreatic digestive exopeptidases carboxypeptidases A and B were studied. Carboxypeptidase inhibitor from potato tubers was fed to newly hatched chicks at a level equal to that present in a diet containing 50% raw potato solids, which was severely growth depressing. At this level the effect of the carboxypeptidase inhibitor on growth was insignificant but the following effects were noted: (1) increased fecal protein (the increase mainly consisting of low-molecular weight proteins); (b) poorer feed efficiency; and (c) a significant decrease in pancreatic digestive proenzyme levels, although no hypertrophy was noted. In addition, the inhibitor was not digested readily in the intestinal tract and increased in concentration in intestinal contents as it progressed down the tract. Potato Inhibitor II, a potent trypsin inhibitor, when fed to chicks, also at the level found in the diet containing 50% raw potato, was severely growth depressing. The inhibitor produced significantly increased fecal protein and caused pronounced pancreatic hypertrophy. Thus, the growth depressing effects of raw potato tubers is probably due in part to the trypsin inhibitor, with only a small contribution originating from the carboxypeptidase inhibitor.

Animals↗
PubMed1982

Primary structures of two low molecular weight proteinase inhibitors from potatoes.

The amino acid sequences of two low molecular weight proteinase inhibitors from Russet Burbank potatoes have been determined. One of these, a chymotrypsin inhibitor, is a peptide of 52 amino acid residues, while the second inhibitor, which is specific for trypsin, contains 51 amino acid residues. These peptides are highly homologous, differing at only nine positions. At position 38, the chymotrypsin inhibitor possesses leucine and the trypsin inhibitor an arginine. This difference probably represents the P1 sites, which are consistent with the respective specificities of the two inhibitors. The inhibitors are also homologous with potato inhibitor II and with an inhibitor previously isolated from eggplants.

Amino Acid Sequence↗