Showing papers on "Amylase published in 1972"

The Role of Insulin in the Regulation of α‐Amylase Synthesis in the Rat Pancreas

Abstract: . Changes in pancreatic exocrine enzyme activities were studied in different forms of experimental diabetes in rats. The effects of adrenalectomy on these changes were measured. The early actions of insulin on pancreatic enzyme activities and on incorporation of (4,5-3H)-leucine into amylase were also determined. The main results are: 1) Alloxan-diabetes leads to a decrease in amylase activity, a decreased rate of amylase synthesis and an increase in the activities of trypsinogen and chymotrypsinogen as described by Palla et al. [9]. Only the decrease in amylase activity correlates with the increase in blood glucose concentration. 2) Adrenalectomy does not reverse the changes in the activities of exocrine pancreatic enzymes induced by diabetes. 3) Diazoxide-diabetes is accompanied by an increase in all pancreatic enzyme activities, most probably due to the inhibition of enzyme secretion. 4) After treatment with streptozotozin a significant decrease in pancreatic amylase activity appears after 36 h. Amylase activity continues to fall during the following days, in contrast the increase in the activities of proteolytic enzymes is not significant until the 4th day. 5) Insulin treatment of severely diabetic, non-ketotic rats leads, as early as 90 min. after injection, to a significant increase in pancreatic amylase activity with no change in the other exocrine enzyme activities. A decrease in all enzyme activities, seen 6 h after insulin, is due to enhanced enzyme secretion. 6 As soon as 2 h after injection insulin leads to a significant increase in the incorporation of (4,5-3H)-leucine into pancreatic amylase but not into total pancreatic protein. This increase is completely abolished by actinomycin D. 7) Short-term effects of adrenalectomy (20 h) and effects of substitution with 6-α-fluoro-16α-methyl-prednisolon on the incorporation of (4,5-3H)-leucine into pancreatic amylase and total pancreatic protein result mainly from changes in the size of the cold leucine pool. According to these results insulin regulates pancreatic amylase synthesis mainly at the level of transcription. Insulin plays a permissive role in pancreatic amylase synthesis and is not involved in short-term regulation of amylase synthesis in the non-diabetic state. Clinical findings in juvenile diabetics indicate a similar type of regulation for amylase synthesis.

Biochemical Changes in the Rice Grain during Germination

Abstract: Changes in the content of starch, protein, and RNA and in the activity of their hydrolases in the rice endosperm (Oryza sativa L., variety IR8) were determined during the first week of germination without added nutrient both in the dark and in the light. Changes were generally more rapid in the dark than in the light. Oxygen uptake and RNase activity started to increase and the root protruded on the second day, followed by the coleoptile on the third day, and the primary leaf on the fourth day. ATP level was at a maximum on the fourth day. The activity of amylases and R enzyme increased progressively, but that of phosphorylase tended to decrease during starch degradation. A new alpha amylase isozyme band appeared during germination. Glucose was the major product of starch degradation. Sucrose, maltose, maltotriose, raffinose, and fructose were also detected. Protease activity reached a maximum on the fifth or sixth day and closely paralleled the increase in soluble amino N and soluble protein.In embryoless seed halves with 0.12 muM gibberellin As, peak protease activity occurred in 2.5 days and peak alpha amylase activity on the fifth day of incubation. The production of alpha amylase, protease, and R enzyme was inhibited by 40 muM cycloheximide, but only alpha amylase and R enzyme were inhibited by 20 mug/ml actinomycin D.

Secretion of acid hydrolases and its intracellular source in tetrahymena pyriformis

Abstract: Axenic Tetrahymena pyriformis, syngen 1, mating type II cells were grown in Cox's defined medium. When washed and transferred into nonnutrient dilute salt solution or resuspended in the defined medium, the intact cells secrete acid hydrolases into the medium. Cells starving in the salt solution release in 5 hr about two-thirds of their β-glucosidase, β-N-acetylglucosaminidase, α-glucosidase, and amylase activities, about one-third of their deoxyribonuclease and phosphatase activities, smaller amounts of ribonuclease, and only a negligible fraction of their proteinase activity and protein content. During this period there is practically no change in the enzyme activities (except for a sudden increase of ribonuclease activity) and protein content of cells and medium together. Cells resuspended in the nutrient medium secrete enzymes as do the starved cells, but replace this loss, so that there is a continuous increase of the activities in the total system. According to isopycnic centrifugation experiments performed in sucrose gradients, the source of the hydrolases is a special population of lysosomes which disappear from the cells during starvation. This population equilibrates in the high density region of the gradients and contains the various acid hydrolases in about the proportion in which these enzymes appear in the medium.

Calcium-dependent amylase release and electrophysiological measurements in cells of the pancreas.

Abstract: 1. Transmembrane potential, effective membrane resistance, and amylase output were recorded from acinar cells of rat pancreas perfused in vitro. 2. Both pancreozymin and acetylcholine hyperpolarized the acinar cells, increased effective membrane resistance, and augmented amylase output. 3. The omission of calcium from the perfusion medium increased effective membrane resistance and potential, and abolished the increase in amylase output in response to the drugs. 4. A quantitative relation was found between the amount of amylase released by pancreozymin and the concentration of calcium in the perfusion medium at values below the normal 2·5 mM calcium. Excess magnesium did not inhibit the increase in amylase output in response to the drug. 5. It is concluded that the release of amylase from the pancreas depends on the entry of calcium into the acinar cells. The entry of calcium seems to be mediated by a carrier in the membrane and may be considered as a ‘facilitated diffusion’. 6. The electrophysiological findings taken together with morphological evidence provided by scanning electron microscopy favour the view that pancreatic zymogens are released from the granules in the acinar cells to the lumen by the process known as exocytosis.

Characteristics and properties of a caldo-active bacterium producing extracellular enzymes and two related strains.

Abstract: The caldo-active strain YT-P was found to produce a variety of extracellular enzymes, including an amylase and a protease, which were further examined. With azo-casein as a substrate, optimum conditions with respect to enzyme and substrate concentration were determined for the protease. The optimum temperature was found to be 70°C, with a sharp decline to both lower and higher temperatures. The enzyme was found to be extremely heat-stabile, with unaltered activity after 8 hours at 80°C. Optimum conditions for the amylase were also examined. This enzyme was shown to be less heat-stabile, though the temperature optimum was again at 70°C. The activity or stability was not influenced by absence or presence of Ca-ions. The main activity of the amylase was found in the 20–40% ammonium sulfate fraction, which also contained the bulk of the proteolytic enzyme. This strain growth optimally on a variety of carbon sources at 72°C. Typical submicroscopical features are the double-layered cell wall, and a cytoplasmic membrane with a varying number of small dots and dot-free patches. Furthermore the nutritional requirements and submicroscopical features of two other strains, YT-G and YT-F, are described and compared to strain YT-P. Based on the fatty acid composition of the three spore forming caldo-active strains we suggest that they belong to the genus Bacillus, and propose the names B. caldolyticus for strain YT-P, B. caldovelox for strain YT-F, and B. caldotenax for strain YT-G.

Control of pancreatic amylase release in vitro: effects of ions, cyclic AMP, and colchicine

Abstract: 1. The time course and concentration-response relationship of amylase release from pieces of guinea-pig pancreas in vitro in response to bethanechol and pancreozymin was determined. 2. Removal of Ca++ from the medium had no effect on basal amylase release but abolished the stimulating effect on release of bethanechol. 3. Elevation of the concentration of Mg++ in the medium increased basal amylase release and reduced the response to bethanechol. 4. Elevation of the concentration of K+ in the medium increased amylase release; this effect was blocked by a concentration of atropine which blocked also the response to bethanechol. 5. Cyclic AMP, dibutyryl cyclic AMP and theophylline failed to stimulate amylase release. Pancreatic cyclic AMP concentrations were found not to be increased by bethanechol, pancreozymin or an elevated concentration of K+ in the medium. 6. Colchicine had no effect on basal amylase release or the response to bethanechol or pancreozymin. 7. It is concluded that the coupling of stimulus to secretion involves ionic control but that neither cyclic AMP production nor microtubular mechanisms play a major role in controlling exocytosis in the pancreatic acinar cell. These findings are discussed in relation to the stimulus-secretion coupling processes in other cells.

Isolation and Measurement of Pancreatic Amylase in Human Serum and Urine

Abstract: We describe a sensitive quantitative procedure for separating isoamylases in human serum, urine, and tissue homogenates. Two components have been discerned with chromatographic characteristics resembling those of pancreatic and salivary amylases, respectively. Several lines of evidence—derived from studies in normal subjects, pancreatectomized patients, and patients with acute pancreatitis—indicate that the pancreas is probably the source of the component in serum and urine that exhibits characteristics of pancreatic amylase. The source of the component resembling salivary amylase has not yet been fully defined. Isoamylase analysis of extracts of fallopian tube and liver revealed two amylase components with chromatographic properties similar to pancreatic and salivary amylases, respectively.

Morphology of starch granules in cereal grains and malts

Abstract: During malting, amylases have limited action on large starch granules of barley endosperm but rapidly degrade the small granules. In contrast, the small starch granules of wheat endosperm are resistant to enzymic attack. High levels of exogenous gibberellic acid increase the production of α-amylase and encourage the appearance of radial channels in the partially-degraded large starch granules. These endo-corroded granules are mainly found in the proximal (embryo) half of the endosperm where levels of α-amylase are much higher than at the distal end. Degradation of malt starch can therefore result from enzymic attack both outside and inside the granules. Malting of barley reduces the population of small starch granules which are slower to gelatinize than large granules at the infusion mashing temperatures of 65° C. During germination of barley multiple starch granules are rapidly synthesized in single amyloplasts in the scutellum. The endosperm of high amylose barley is devoid of small starch granules and the average size of the large granules is reduced. Steeliness in sorghum is related to the close packing of the starch-protein matrix rather than to unequal distribution of protein. The significance of these results is discussed, particularly in relation to the morphology of starch granules, the nature of their outer covering, the distribution of amylopectin and amylose within the granule, and the site of enzymic attack.

Continuous culture studies on the biosynthesis of alkaline protease, neutral protease and -amylase by Bacillus subtilis NRRL-B3411.

Abstract: SUMMARY: The amounts of three catabolite repressible enzymes, alkaline protease, neutral protease and α-amylase, produced by Bacillus subtilis NRRL-B3411 growing in a chemostat, depended on the growth-limiting substrate. Limiting growth with glucose was advantageous for α-amylase synthesis while nitrogen-limited growth was advantageous for synthesis of the two proteases. Under the conditions used, continuous cultures were unsuitable for large-scale production of the three enzymes since spontaneous mutations to less productive strains occurred in the long term.

Extracellular Alkaline Amylase from a Bacillus Species

Abstract: A selective medium was used to isolate a bacterium (Bacillus species NRRL B-3881) that produced extracellular alkaline amylase in an alkaline medium (pH 9.5). Maximal enzyme yield was obtained in an aerated medium after 21 hr at 36 C. The enzyme was purified 18-fold by ultrafiltration and ammonium sulfate precipitation. Three active isoenzymes (one major and two minor) of alkaline amylase were detected by disc electrophoresis in polyacrylamide gel. The enzyme was only 12% inactivated by 20 mm ethylenediaminetetraacetic acid after 1 hr at pH 9.2 and 32 C. The optimal temperature was 50 C at pH 9.2, and the optimal pH was 9.2 at 50 C. The enzyme was stable between pH 7.5 and 10. It had an endomechanism of substrate encounter. The products produced from amylose and amylopectin had the beta-configuration. Cyclomaltoheptaose was hydrolyzed to maltotriose, maltose, and glucose. The main final product produced from amylose and amylopectin was beta-maltose; the other final products were maltotriose and small quantities of glucose and maltotetraose. The predominant product at early stages of hydrolysis was maltotetraose; other products were maltose through maltonanaose.

Some Properties of Salivary Amylase: A Survey of the Literature and Some Observations:

Abstract: Properties of Amylase ACTIVITY.-Alpha-amylase catalyzes a random splitting of the a-1,4 glucosidic bonds of glucan (this is not true with maltose). The end products of amylolytic digestion of starches, therefore, are maltose, some glucose, and "limit dextrins" that contain branching linkages other than a-1,4 glucosidic linkages.2-4 The activity proceeds according to the "multiple attack" theory: each enzyme molecule is able to split a number of linkages on different glucose chains during one enzyme substrate complex formation. The degree of multiple attack is different for amylases from different sources (eg, salivary, pancreatic, bacterial); this is important when comparing the activity of different amylases.5,6 The activity of aamylase is different from that of P-amylase, which splits off maltose units from the nonreducing end of the glucan in a zipper fashion. Beta-amylase is not found in animal sources and is present in the oral cavity only as a microbial product. The catalytic range of a-amylase also probably extends to the synthesis of maltose and maltosaccharides from a-D-glucopyranosyl compounds; the amylases are part of a "glucosylase" group of enzymes.7'8 The activity and stability of a-amylase depends on the presence of chlorine ions and calcium; the latter probably form intra-

Origin of Pleural Fluid Amylase in Esophageal Rupture

Abstract: A patient with esophageal rupture and elevated pleural fluid amylase activity mimicking acute pancreatitis was studied to find the origin of the enzyme. Polyacrylamide gel electrophoretic ...

Effects of Fasting and Feeding on Protein Synthesis by the Rat Pancreas

Abstract: These experiments were designed to determine whether fasting and feeding were associated with differing rates of protein synthesis in the rat pancreas. It has been established that feeding, acetylcholine, or cholecystokinin-pancreozymin administration was associated with enhanced rates of digestive enzyme secretion; however, the literature is unclear as to effects of such stimulation on enzyme synthesis. Rats fed ad lib. or fasted 24, 48, or 72 hr were used for this study. Pancreases were removed and incubated in tissue culture medium with l-phenylalanine-14C, and incorporation into TCA-insoluble material as well as purified amylase was measured. Compared with fed controls, fasting 24, 48, and 72 hr was associated with 29%, 39%, and 35% decreases in incorporation of l-phenylalanine-14C into protein. Decreases of similar magnitudes were apparent whether the data were expressed in terms of protein or DNA. Pancreatic amylase isolated from rats fasted 48 hr contained 57% fewer counts of l-phenylalanine-14C than amylase isolated from fed rats. Moreover, rats fasted for 24 hr and given bethanechol chloride incorporated greater amounts of l-phenylalanine-14C into protein than fasted controls. Studies were performed to exclude changes in pool size of precursor (l-phenylalanine-14C) or product (amylase) in accounting for decreases associated with fasting. These studies demonstrate that fasting was associated with decreased rates of pancreatic amylase and protein synthesis in rats.

A fast technique for the separation and detection of amylase isoenzymes using a chromogenic substrate.

Abstract: The technique utilizes the principle of the release ofa soluble blue dye (Cibachron blue F3A) from an insoluble dye-starch polymer (Ceska, Hultman, and Ingelman, 1969) suspended in agar for the demonstration of amylase activity. Such a polymer is obtainable as Phadebas tablets. The isoenzymes are separated by electrophoresis on cellulose acetate in a discontinuous tris-barbitone buffer system. A similar method has been described by Rosalki (1970) using amylose azure (Calbiochem) as substrate, which is less sensitive than the method described below, and does not resolve the subcomponents.

Investigation of the active center of porcine-pancreatic amylase.

Abstract: 1 The effect of maltose was studied in porcine pancreatic amylase. At neutral pH 1% (29 mM) maltose produced with amylase a difference spectrum characteristic of the perturbation of tryptophan. The molar absorption difference at the maximum wavelength was Δ290= 1200. 2 The difference spectrum appeared to be specific for maltose. Perturbation difference spectra measurements in 20% polyethylene glycol indicated that one tryptophyl side chain per mol amylase was involved in the interaction with maltose. 3 The dissociation constant of the amylase · maltose complex calculated from the concentration dependence of the absorption difference at 290 nm was Ks= 13 mM. Maltose inhibited amylase activity competitively and an inhibition constant of Ki= 25 mM was obtained, a similar value to that found spectrophotometrically. It is assumed that the tryptophyl side chain interacting with maltose may be involved in the binding of substrate by pancreatic amylase.

Simultaneous study of the metabolic turnover and renal excretion of salivary amylase- 125 I and pancreatic amylase- 131 I in the baboon.

Abstract: The metabolic turnover of salivary and pancreatic amylase was studied in the baboon, an animal with a serum amylase level and renal clearance of amylase similar to man. Purified amylase was electrolytically iodinated. Although iodinated and uniodinated amylase had similar gel filtration, electrophoretic, enzymatic, glycogen precipitation characteristics, the labeled enzyme was cleared less rapidly by the kidney than was the unlabeled material. However, urinary iodinated amylase which had been biologically screened by the kidney had a renal clearance and serum disappearance rate indistinguishable from unlabeled amylase and thus can serve as a tracer in metabolic turnover studies. Administration of a mixture of salivary amylase-(125)I and pancreatic amylase-(131)I made it possible to simultaneously measure the serum disappearance and renal clearance of these two isoenzymes. The metabolic clearance of both isoenzymes was extremely rapid with half-times of about 130 min. This rapid turnover of serum amylase probably accounts for the transient nature of serum amylase elevation which frequently occurs in pancreatitis. Pancreatic amylase-(131)I was consistently cleared more rapidly (mean clearance ratio: 1.8) by the kidney than was salivary amylase-(125)I. This more rapid renal clearance of pancreatic amylase may help to explain the disproportionate elevation of urinary amylase relative to serum amylase observed in pancreatitis.

Trypsin inactivation by intact Hymenolepis diminuta.

Abstract: Using azoalbumin as a substrate, it was demonstrated that intact Hymenolepis diminuta inactivate trypsin when incubated with this enzyme. At a given enzyme concentration ([E]), the per cent inactivation (%I) was relatively constant as the substrate concentration ([S]) was varied. However, at a given [S], the %I increased as the [E] decreased. It was also demonstrated that inactivation was dependent upon the time worms were exposed to the enzyme, the total worm weight present in the assay, and the pH of the assay medium. The %I was not related to worm surface area, and was unaffected by polyions and calcium ions in the incubation medium. These results are discussed in relation to the possible mechanism and physiological significance of this phenomenon. The mucosal surface of the mammalian intestine and the outer surface of the syncytial epidermis of the cestode, Hymenolepis diminuta, contain intrinsic membrane-bound enzymes (Crane, 1962; Newey et al., 1963; Arme and Read, 1970; Dike and Read, 1971a). Both surfaces are reported to adsorb enzymes of pancreatic origin (Ugolev, 1965; DeLaey, 1966a; Goldberg et al., 1968, 1969; Read, 1972). According to DeLaey (1966b), adsorption of amylase involves interaction with the mucosal glycocalyx and is readily reversible (Jesuitova et al., 1964). Amylase adsorption to the surface of H. diminuta is also reversible and is partially blocked by polyions (Read, 1972). However, the adsorption of proteolytic enzymes to isolated mucosal cells or subcellular particles is not readily reversible (Goldberg et al., 1968, 1969). According to Ugolev (1965), the adsorption of amylase on the mammalian mucosa results in an increase in enzyme activity. However, doubt has been cast on Ugolev's interpretation with the demonstration that the mammalian mucosa has intrinsic membrane-bound amylases (McMichael and Dahlqvist, 1968; Alpers and Solin, 1970). On the other hand, while Hymenolepis does not exhibit intrinsic amylase or disaccharidase activity, adsorption of pancreatic amylase to the worm surface results in an increase in amylolytic activity (Taylor and Thomas, 1968; Read, 1972). Adsorption of trypsin and chymotrypsin to isolated human Received for publication 24 February 1972. * This study was supported by a grant (AI-01384) from the NIH, U. S. Public Health Service. t U. S. Public Health Service Postdoctoral Fellow, 1-F02-AI-45108-01. mucosal cells or subcellular particles does not ter the kinetic parameters of these enzymes (Goldberg et al., 1969). However, in the presence of intact mammalian mucosa, proteolytic enzymes of pancreatic origin are inctivated (Borgstrom et al., 1957; Goldberg et al., 1968, 1969; Pappas and Gallogly, unpublished). Reichenbach-Klinke and Reichenbach-Klinke (1970) reported that trypsin is inactivated in the presence of the tapeworm, Proteocephalus longicollis. The present investigation was concerned with the effects of the tapeworm, Hymenolepis diminuta, on pancreatic trypsin. MATERIALS AND METHODS Hymenolepis diminuta were reared in the beetle, Tenebrio molitor. Male Sprague-Dawley rats (Holtzman Co.) weighing 80 to 100 g were infected with 30 H. diminuta cysticercoids and the worms removed 11 days postinfection. Worms were rinsed in 3 changes of Krebs-Ringer solution containing 25 mM Tris(hydroxymethyl) aminomethane-maleate buffer (pH 7.2) (KRT of Read, Rothman, and Simmons, 1963), randomized into groups (usually 10 worms/group), and incubated in fresh KRT at 37 C for 15 min prior to their addition to the assay medium. The assay medium consisted of 4 ml of KRT and 1 ml of an enzyme solution (Trypsin-type XI: DCC treated. 8,000 BAEE units/mg. Sigma Chemical Co., St. Louis) maintained at 37 C in a shaking water bath. When groups of worms were to be used during assays they were removed from the previous incubation medium (KRT) and allowed to incubate in the KRT-enzyme solution for 15 min prior to the addition of substrate (this period in the KRT-enzyme solution is hereafter referred to as the preincubation period); after preincubation the worms were removed. The reaction was initiated by the addition of 1 ml of an azoalbumin (bovine origin, Sigma) solution prewarmed to 37 C, and allowed to continue for a prede-

Biological Sciences: Frequencies of Amylase Variants in Drosophila melanogaster

Abstract: THE selective significance of enzyme polymorphisms remains unsettled1,2. The frequencies of some enzyme variants are correlated with environmental factors3, which might cause frequency changes by acting on closely linked genes. We therefore studied amylase variants in Drosophila melanogaster. A major function of amylase in Drosophila is in the digestion of starch. Genetical and physiological investigations on amylase variants were made by Kikkawa4, Doane5,6 and Bahn7. Using electrophoresis they found five main bands of amylase activity. In homozygous flies one or two bands are present, caused by two closely linked genes on the second chromosome (2–78.1), presumably originated by duplication. Amylase activity of the variants differs on the same food medium, and also depends on the composition of the food6. Banding patterns in larvae and in adult flies are identical (ref. 6, and A. J. W. H., unpublished work).

Halophilic Amylase from a Moderately Halophilic Micrococcus

Abstract: A moderately halophilic Micrococcus sp., isolated from unrefined solar salt, produced a considerable amount of extracellular dextrinogenic amylase when cultivated aerobically in media containing 1 to 3 m NaCl. The Micrococcus amylase had maximal activity at pH 6 to 7 in 1.4 to 2 m NaCl or KCl at 50 C. Calcium ion and a high concentration of NaCl or KCl were essential for activity and stability of the amylase. The salt response of the amylase depended greatly on the pH and temperature of the enzyme assay.

The regulation of α-amylase production inBacillus licheniformis

Abstract: The production ofα-amylase (α-1,4 glucan-4-glucan hydrolase; E.C. 3.2.1.1.) by a strain ofBacillus licheniformis has been studied in batch and continuous cultures. The synthesis of this enzyme was shown to be repressed by glucose or other low-molecular-weight metabolisable sugars. Consequently, amylase production in a medium which contained “liquified” starch only began after the low-molecular-weight sugars had been dissimilated. Thereafter, the dextrins in the medium were degraded by amylase produced by the bacteria to yield further quantities of metabolisable sugars. These sugars were continuously dissimilated by the growing organisms and never accumulated to concentrations where they would repress further amylase synthesis. A clear analogy could thus be drawn with bacteria growing in a carbon-limited environment in a chemostat. Therefore,α-amylase production byB. licheniformis organisms growing in 3-litre chemostats was studied. No evidence was obtained to infer that an inducer was necessary for amylase production, and it was concluded that the prime factors influencing amylase production, in this species at least, were growth rate and catabolite repression.

Does Gibberellic Acid Stimulate Seed Germination via Amylase Synthesis

Abstract: Gibberellic acid is known to break dormancy of several types of seeds: (a) light-promoted seeds, such as Grand Rapids lettuce seed (Lactuca sativa L. var. Grand Rapids); (b) lightinhibited seeds, such as the seed of the honey-bee plant (Phacelia tanacetifolia Benth; (c) seeds requiring stratification (storage at low temperatures in a moist condition), such as the hazel nut (Corylus avellana L.); (d) seeds requiring after-ripening (storage at room temperature in dry condition), such as the wild oat (Avena fatua L.). Recent findings indicate that when dormant hazel nut seeds are soaked at 5 C for 28 days, which is a natural means of breaking dormancy, the gibbereilin-synthesizing mechanism is activated and that actual synthesis of gibberellins takes place when the seeds are transferred to a suitably higher temperature. Accumulation of GA results in germination (10). It has also been suggested that in the phytochrome-controlled germination of Grand Rapids lettuce seeds, the role of Pfr is to activate GA biosynthesis (8). One biochemical reaction known to be enhanced by GA is the synthesis of hydrolases (especially a-amylase) in the endosperm of cereal grains, such as barley (2, 9, 13). Since starch is a major food reserve in the cereal grains, its breakdown is generally assumed to be an essential process of germination. Many writers have implied that GA stimulates seed germination via amylase synthesis (1, 7, 12). Drennan and Berrie (5) compared the time course of amylase development in dormant and nondormant wild oats (Avena spp.). Their results indicated that both types of seeds contained traces of amylases. When dormant seeds were soaked, there was neither germination nor a change in the level of amylases. When nondormant seeds were soaked (in water), they germinated in 4 days and from the 6th day, amylase activity increased. Thus, they concluded that buildup of amylases is a postgermination phenomenon, and a lack of amylase synthesis must be eliminated as a possible cause of dormancy. We have investigated the time course relationship of GAinduced germination and amylase development in an attempt to find out if GA-induced germination is mediated by amylase production. The seeds of Avena fatua L. (wild oat) type Montana were obtained from Dr. G. M. Simpson of the University of Saskatchewan. These seeds were field-harvested in 1968 and stored at -15 C prior to use. Dry storage at low temperatures

Comparative study of a property of salivary amylase among various heteropterous insects.

Abstract: 1. 1. Various heteropterous species were compared with one another with respect to the type of activation of salivary amylase by Cl − and NO 3 − . 2. 2. The activation of the salivary amylase by these ions was divided into several types [(A), (B), (C), (D: D 1 , D 2 , D′, D″ and D‴), (E)]. 3. 3. Pentatomidae are represented by type (A), Lygaeidae by type (D 1 ) and Miridae by type (D 2 ). 4. 4. No characteristic feature has as yet been given to other families regarding the activation type of salivary amylase, for only a few species have so far been investigated.

Isolation and some properties of the digestive amylase of the American lobster (Homarus americanus).

Abstract: 1. 1. Gastric juice of lobster contains an amylase (2 per cent of the total protein) which can be isolated by affinity chromatography on a dextran gel followed by chromatography on a polycrylamide gel. 2. 2. The specific activity of the enzyme towards starch is 90 (μmoles maltose/min per mg protein), its molecular weight 41,000 and its optimum of activity is at pH 5/sd2. 3. 3. The purified enzyme is activated by sodium chloride, but does not require added calcium.