Pharmacological comparison of bPTH-(1–34) and other hypotensive peptides in the dog

The purpose of the present study was to compare the potency, effectiveness and duration of action of synthetic bPTH-(1–34) with those of other known hypotensive peptides in the anesthetized dog. Of sixteen peptides tested in the present study only 8 were demonstrated to possess hypotensive activity. While bPTH-(1–34) was one of the least potent of the hypotensive peptides, it was equal to or greater than the other peptides in terms of effectiveness and duration of action. Of all the peptides studied, substance P and eledoisin were the most potent in terms of their hypotensive action. It is suggested that perhaps substance P and eledoisin might act at a different site or through different mechanisms than do vasoactive intestinal peptide (V.I.P.), corticotropin inhibiting peptide (C.I.P.), neurotensin, xenopsin, bradykinin and bPTH-(1–34).     

Genetic diversity and climatic determinants of tree frogs in Israel

Summary Allozymic variation in proteins encoded by 27 loci was analyzed electrophoretically in 218 adult specimens, mostly males, representing 8 populations, 5 central and 3 marginal, of lemon yellow treefrogs, Hyla arborea savignyi, in Israel along two transects of increasing aridity: (a) north to south and (b) west to east. The results indicate that (a) Of the 27 loci examined, 5 are monomorphic in all 8 populations; 9 are locally and weakly polymorphic; 6 are regionally and weakly polymorphic; and 7 are regionally and strongly polymorphic; (b) In the populations studied, no alternative fixations were found in any of the 27 loci, except in the Wasit population. The commonest allele predominates across all populations, except Wasit, central as well as marginal; (c) Clinal patterns associated with increasing aridity southwards and eastwards occur in polymorphism, P, heterozygosity, H, and in allele frequencies of Ldh-1, Fum, Got-1, and Sdh; (d) For habitat generalists, treefrogs have above average number of alleles per locus, A, and polymorphism, P, while the heterozygosity, H, is average. All three estimates A, P, and H exhibit wide geographic variation decreasing progressively southwards and eastwards; (e) Central populations harbor more genic variation then marginal populations; (f) Genic similarity between populations is high; (g) Significant gametic phase disequilibria were found in several tests in 2 populations; (h) P, H, and allozymic variation in several gene loci are significantly correlated and predictable by environmental variables, primarily those related to water; (i) Morphological and allozymic variations are uncorrelated.The spatial patterns and environmental correlates and predictors of genic variation in Hyla arborea savignyi in Israel suggest that (i) protein polymorphisms are largely adaptive and are molded primarily by climatic selection rather than by stochastic processes or neutrality, and (ii) the environmental variation model seems to be the best predictor of genic variation in treefrogs.     

Auxin-induced Ethylene Production and Its Inhibition by Aminoethyoxyvinylglycine and Cobalt Ion

Auxin is known to stimulate greatly both C₂H₄ production and the conversion of methionine to ethylene in vegetative tissues, while amino-ethoxyvinylglycine (AVG) or Co²⁺ ion effectively block these processes. To identify the step in the ethylene biosynthetic pathway at which indoleacetic acid (IAA) and AVG exert their effects, [3-¹⁴C]methionine was administered to IAA or IAA-plus-AVG-treated mung bean hypocotyls, and the conversion of methionine to S-adenosylmethionine (SAM), 1-amino-cyclopropane-1-carboxylic acid (ACC), and C₂H₄ was studied. The conversion of methionine to SAM was unaffected by treatment with IAA or IAA plus AVG, but active conversion of methionine to ACC was found only in tissues which were treated with IAA and which were actively producing ethylene. AVG treatment abolished both the conversion of methionine to ACC and ethylene production. These results suggest that in the ethylene biosynthetic pathway (methionine → SAM → ACC → C₂H₄) IAA stimulates C₂H₄ production by inducing the synthesis or activation of ACC synthase, which catalyzes the conversion of SAM to ACC. Indeed, ACC synthase activity was detected only in IAA-treated tissues and its activity was completely inhibited by AVG. This conclusion was supported by the observation that endogenous ACC accumulated after IAA treatment, and that this accumulation was completely eliminated by AVG treatment. The characteristics of Co²⁺ inhibition of IAA-dependent and ACC-dependent ethylene production were similar. The data indicate that Co²⁺ exerts its effect by inhibiting the conversion of ACC to ethylene. This conclusion was further supported by the observation that when Co²⁺ was administered to IAA-treated tissues, endogenous ACC accumulated while ethylene production declined.     

Pharmacological comparison of bPTH-(1–34) and other hypotensive peptides in the dog

The purpose of the present study was to compare the potency, effectiveness and duration of action of synthetic bPTH-(1–34) with those of other known hypotensive peptides in the anesthetized dog. Of sixteen peptides tested in the present study only 8 were demonstrated to possess hypotensive activity. While bPTH-(1–34) was one of the least potent of the hypotensive peptides, it was equal to or greater than the other peptides in terms of effectiveness and duration of action. Of all the peptides studied, substance P and eledoisin were the most potent in terms of their hypotensive action. It is suggested that perhaps substance P and eledoisin might act at a different site or through different mechanisms than do vasoactive intestinal peptide (V.I.P.), corticotropin inhibiting peptide (C.I.P.), neurotensin, xenopsin, bradykinin and bPTH-(1–34).     

Rapid release of protease inhibitors from soybeans: immunochemical quantitation and parallels with lectins

Specific antisera were prepared against the Bowman-Birk trypsin inhibitor and four other trypsin inhibitors of low molecular weight isolated from soybeans (Glycine max L. cv. Tracy). These antisera were used to detect the presence and amount of the inhibitors in: (a) seeds and protein extracts of soybean meal; (b) seedlings; and (c) the water surrounding the seeds and roots of seedlings. Lectin activities in seeds, seedlings, and water were also determined at the same time as the protease inhibitor activities. By competitive inhibition of immunoprecipitation, the combined five low molecular weight protease inhibitors were found to constitute the following percentages of proteins (w/w): 6.3% in defatted soybean meal; 8.1% of the protein extracted from the meal by a buffer of pH 8.6; 8.3, 14.7, 15.2, 16.1, 17.2, and 18.9% of the protein in a lyophilisate of water in which seeds were incubated for 4, 8, 12, 16, 20, and 24 hours, respectively; 8.2% in a lyophilisate of water in which roots of seedlings grew for 20 days; 1.5% in cotyledons; and less than 0.1% in epicotyls, hypocotyls, and roots of 12-day-old seedlings. Hemagglutination activities, expressed as the lowest amount of protein required to give a positive agglutination of 0.2 ml of 2% rabbit red blood cells, were as follows: purified soybean lectin, 0.08 μg; lyophilisate of water in which seeds were incubated for 4, 8, 12, 16, 20, and 24 hours, 10, 2.5, 5, 5, and 2.5 μg, respectively; lyophilisate of water in which roots grew for 20 days, 5 μg; 12-day-old cotyledons, roots, epicotyls, and hypocotyls, 12.5, 100, >1,000, and >500 μg, respectively. The results indicate that a large amount of protease inhibitors as well as lectins are released from seeds during the first 8 hours of imbibition. Neither lima bean trypsin inhibitor (mol wt, 10,000) nor Kunitz soybean trypsin inhibitor (mol wt, 21,500) showed competitive inhibition in tests with antisera against low molecular weight soybean protease inhibitors.     

Induction of phenylalanine ammonia-lyase and increase in phenolics in lettuce leaves in relation to the development of russet spotting caused by ethylene

Russet spotting (RS), consisting of numerous small brown spots on the midrib of head lettuce (Lactuca sativa), is a physiological disorder induced by exposure to ethylene. In leaves suffering RS, the increase in spotting was accompanied by a parallel increase in the amount of phenolic compounds. Of these, chlorogenic acid and isochlorogenic acid were identified. Ethylene induced high phenylalanine ammonia-lyase (PAL) activity and RS formation in the susceptible cultivar Salinas, but not in the resistant cultivar Calmar. In the absence of ethylene neither significant PAL induction nor RS occurred. No correlation was found between the increase in polyphenol oxidase or peroxidase and the development of RS. The increase in PAL activity, however, was closely correlated with the development of RS. The increase in PAL activity preceded the development of RS, and the extent of RS was directly related to the level of PAL. Three temperatures (0.5, 5.5, and 12.5 C) were compared on the basis of their influence on both RS and PAL induction. At the lowest temperature (0.5 C) neither PAL induction nor RS occurred to a significant extent. At the highest temperature (12.5 C) an initial rapid increase in PAL activity and an earlier development of spotting were observed, but subsequently there was a decrease in both PAL activity and the rate of development of RS. At the medium temperature (5.5 C) both PAL activity and RS increased progresively with time. The decline of PAL activity at a higher temperature might be attributed to inactivation of the enzyme. Thus, a temperature favorable for induction of PAL activity by ethylene was also favorable for RS. These observations indicate a close interrelationship between the induction of PAL activity and the development of RS in response to ethylene, and suggest a causal relationship between the two events. PAL serves as a useful biochemical marker for the RS reaction.     

Computation of the fraction of induced cells in enzyme induction systems

A theoretical model is developed for continuous multistage enzyme production systems, which consist of a growth fermentor used for growing microorganisms rapidly without enzyme production and a subsequent system of induction reactors in which enzymes induction and production occurs. The model allows the computation of the fraction of induced cells residing in the induction reactor for organisms exhibiting a lag phase in enzyme induction. For this model a general analytical solution was obtained for the cumulative internal residence time distribution of a series of n well-stirred vessels with a recycle. The theoretical results are compared in a preliminary way with experimentally measured cellulase productivities of continuous multistage cellulose fermentations with Trichoderma viride QM 9414.     

“C-751”激素在植物组织培养中的生物学效应初步观察

植物激素,按作用性质分为二大类:一为生长素类(如吲哚乙酸,奈乙酸,2,4—D等),一为激动素类(kinetin)(如6—苄基嘌呤,甲氨基嘌呤等)。从石油废渣中提取的长春产C—751激素是相当于哪一类激素呢?通过胡萝卜,菊芋,蓖麻胚乳的诱导愈伤组织实验和通过对小麦,向日葵,绿豆的发芽、生根实验,我们做了同6—苄基嘌呤,6—(?)基嘌呤,吲哚乙酸,萘乙酸,2,4—D药剂的作用对比,实验初步结果:C—751激素在诱导愈伤组织形成和生长以及种子发芽和幼苗生根中,其性质多接近生长素类。     

Release of heat pretreatment-induced dormancy in lettuce seeds by ethylene or cytokinin in relation to the production of ethylene and the synthesis of 1-aminocyclopropane-1-carboxylic acid during germination

The germination of lettuce (Lactuca sativa L.) seeds was greatly reduced when the seeds were heated at 97°C for 30 h prior to imbibition. This dormancy was effectively released when ethylene (1–100 ppm) or benzyladenine (BA) (0.005–0.05 mM) was applied during the imbibition period. Ethylene was not required during the early part of imbibition, but was essential during the period immediately prior to radicle protrusion. Treatment with 1-aminocyclopropane-1-carboxylic acid (ACC) (0.1–10 mM) stimulated germination, but was not as effective as ethylene or cytokinin treatment. During the germination of nondormant lettuce seeds, ethylene production increased rapidly and reached a peak at 24 h, which coincided with the emergence of the radicle, and then declined; the level of ACC increased as ethylene production rate increased, but remained at a high level after radicle protrusion. In heat-pretreated dormant lettuce seeds, the increases in percent germination, ethylene production, and ACC levels were all delayed and lower than those of nondormant seeds, and these increases were accelerated by treatment with ethylene or cytokinin.