Wound healing and collagen formation. III. A quantitative radioautographic study of the utilization of proline-H3 in wounds from normal and scorbutic guinea pigs

The sequence of incorporation and utilization of tritium-labeled proline has been examined in healing wounds from normal and scorbutic guinea pigs. Linear incisions in the skin of the animals were allowed to heal for 7 days. Each animal was given proline-H³, and the wounds were excised 30 minutes, 1 and 4 hours, 1, 3 and 7 days after proline administration. The tissues were fixed in osmium tetroxide, fixed again in neutral buffered formalin, embedded in epoxy resin, and sectioned at 1 micron thickness. The sections were coated with nuclear track emulsion, exposed, developed, and stained. The results of grain counts were quantitated as the number of counts per unit area overlying cells, fibers, etc. In both groups the proline reaches a maximum over the fibroblasts within 4 hours and subsequently disappears from the cells. Concomitantly, the proline reaches a maximum over the collagen (in normal animals) and extracellular fibrillar material (in scorbutic animals) by 4 hours, where it remains. The modified technique of radioautography used in this study allows not only resolution of approximately 1 micron, but also minimal background, decreased artifact, and a clear separation of the randomly situated elements within the wounds so that grain counting is facilitated. The results correlated with previous electron microscopic studies are consistent with the utilization of proline by the fibroblasts and its incorporation into collagen (in normal animals) and into the extracellular, fibrillar, non-collagenous material seen in scorbutic animals.

Proline control of the feeding reaction of Cordylophora

The colonial hydroid Cordylophora is a carnivore whose feeding is induced by substances released from captured prey. An active molecule, probably the only one, has been isolated from a fraction of the laboratory food of Cordylophora, brine shrimp larvae, and identified on paper chromatograms as the imino acid proline. Reagent proline induces the feeding reaction at 10^-5M. The reaction is specific in that only two α-imino acids very closely related to proline were found to possess significant activity: azetidine-2-carboxylic acid and pipecolic acid. The response to proline is inhibited by magnesium ions and enhanced by phosphate. Since previous studies have shown that the feeding reactions of Hydra, Physalia, and Campanularia are controlled by reduced glutathione, the phylogenetic implications of the proline control of feeding in Cordylophora are discussed. The feeding reactions of both Cordylophora and Hydra are also induced by proteases, suggesting similar mechanisms of induction in the two hydroids.

COLLAGEN METABOLISM IN THE NORMAL AND LATHYRITIC CHICK

1. Radioisotope incorporation studies of normal and lathyritic chick embryo bone collagen do not demonstrate any interference by lathyrism with collagen synthesis or fibril formation. 2. The results indicate that a portion of the extractable collagen from lathyritic chick embryo bone represents newly synthesized protein. Evidence from a double labeling experiment and from analysis of isotope flow between the extractable and non-extractable pools suggests the extractable lathyritic collagen is heterogeneous. We propose that the lathyritic process affects collagen in all states of aggregation, probably in varying degree. 3. Puromycin, administered intravenously, reduces the amount of extractable collagen in both normal and lathyritic chick embryo bone, and diminishes the incorporation of labeled proline into collagen. 4. Marked fluctuations in incorporation of labeled amino acids into chick embryo bone collagen suggests the occurrence of wide fluctuations in metabolism of this protein.

THE PERIODATE OXIDATION OF AMINO ACIDS WITH REFERENCE TO STUDIES ON GLYCOPROTEINS

1. All alpha-amino acids are oxidized by periodate, but at different rates. 2. The rates of oxidation of individual alpha-amino acids vary with pH. In general, oxidation proceeds more rapidly at alkaline pH. 3. Serine, threonine, cysteine, cystine, methionine, proline, hydroxyproline, tryptophan, tyrosine and histidine are rapidly and extensively oxidized by periodate. 4. Cysteine, cystine, methionine, tryptophan, tyrosine and histidine are oxidized by periodate when they are substituted in the carboxyl and amino groups, as in a polypeptide chain.

GLYCYL-PROLINE IN URINE OF HUMANS WITH BONE DISEASE

An unknown ninhydrin-reacting substance has been found in the urine of three human subjects with rickets. A sample of the substance separated from urine by elution chromatography was hydrolyzed in acid, and equimolar amounts of glycine and proline were released. The DNP reaction applied to the substance resulted in DNP-glycine and free proline. The isolated unknown substance and glycyl-L-proline cochromatographed and coelectrophoresed in a number of solvent and buffer systems. The substance was therefore identified as glycyl-proline.Glycyl-proline is apparently excreted from plasma into urine; it is poorly absorbed by the kidney and its transport is independent of either the glycine or the L-proline transport mechanisms.Glycyl-proline was not excreted by normal subjects. It was found only in patients with severe active rickets. Glycyl-proline excretion paralleled that of total bound hydroxyproline, both diminishing as the rickets healed. Bone collagen appears to be the likely source for glycyl-proline in these patients.

PHYSIOLOGY OF THE SPORULATION PROCESS IN CLOSTRIDIUM BOTULINUM. I. CORRELATION OF MORPHOLOGICAL CHANGES WITH CATABOLIC ACTIVITIES, SYNTHESIS OF DIPICOLINIC ACID, AND DEVELOPMENT OF HEAT RESISTANCE

Day, Lawrence E. (Michigan State University, East Lansing), and Ralph N. Costilow. Physiology of the sporulation process in Clostridium botulinum. I. Correlation of morphological changes with catabolic activities, synthesis of dipicolinic acid, and development of heat resistance. J. Bacteriol. 88:690-694. 1964.-A reasonable degree of synchrony in the sporulation of Clostridium botulinum 62-A was attained by using a large inoculum of a young culture into a medium containing 4% Trypticase and 1 ppm of thiamine. Sporulation was complete within 24 to 36 hr. Cells harvested at various intervals were studied for their fermentative activity with l-alanine and l-proline as substrates. The Q values (microliters of gas per hour per milligram of dry cells) were maximal at the time a large percentage of the cells had initiated sporulation as indicated by swelling. They declined to a plateau at about the same level as found in vegetative cells by the time 10% of the cells had completed sporulation, and finally to a much lower level when sporulation was completed. The rates of accumulation of volatile acids (acetic, valeric, and propionic acids) corresponded closely with the catabolic potential observed. However, in the case of acetic acid, there was a significant decrease in the total acid present as the number of mature spores increased to over 50% of the final number. The total acetic acid then increased at a slow rate. The production of basic compounds during growth and sporulation more than balanced the rate of acid production, because the hydrogen ion concentration decreased exponentially throughout the period as indicated by the steady increase in pH. The synthesis of dipicolinic acid coincided closely with the development of heat resistance. Refractility developed 3 to 5 hr in advance of heat resistance.

SELECTIVE INHIBITION OF PROLINE-INDUCED PIGMENTATION IN WASHED CELLS OF SERRATIA MARCESCENS

Blizzard, John L. (University of Houston, Houston, Texas) and G. E. Peterson. Selective inhibition of proline-induced pigmentation in washed cells of Serratia marcescens. J. Bacteriol. 85:1136-1140. 1963.-Streptomycin, chloramphenicol, and tetracyclines inhibited the synthesis of prodigiosin by Serratia marcescens strain D1. This occurred at concentrations of the antibiotic too low to inhibit the growth of the organism in either agar media or broth cultures. Nonpigmented cells were produced in broth by either adding streptomycin or incubating at 37 C. After being washed and resuspended in aqueous saline containing either casein hydrolysate, l-proline, or a glycine-succinate mixture and incubated at 27 C for 24 hr, these cells formed pigment. The appearance of pigment was preceded by a lag period of 10 hr. Prodigiosin production by these washed suspensions of cells was completely inhibited by either streptomycin or glucose, or by incubation at 37 C instead of 27 C. Even though pigmentation by washed-cell suspensions was induced by proline, the utilization of proline was not affected by streptomycin or glucose, or by incubation at 37 C. To block pigmentation completely, streptomycin had to be added to proline-supplemented cells before they were 10 hr old. Addition of the antibiotic after the end of the induction period caused either partial or no inhibition of pigment production. Streptomycin caused an increase in the endogenous respiration of S. marcescens but failed to affect the constitutive enzymes that oxidize glucose. The possible relationships of these phenomena are discussed. Weil (1952) reported that low concentrations of chloramphenicol and certain tetracyclines inhibit the synthesis of prodigiosin while permitting growth by Serratia marcescens. He noted the potential value to "mode-of-action" studies of an organism having certain functions selectively inhibited by antibiotics. We confirmed Weil's (1952) observations and found that streptomycin at low concentration would also inhibit the synthesis of prodigiosin without impeding growth. Further studies of the selective inhibition of prodigiosin synthesis by streptomycin were performed using nonproliferating suspensions of washed cells (Gott and Williams, 1961). Either a glycine-succinate mixture or l-proline could cause nonproliferating cells to form pigment. A period of induction preceded the formation of pigment. Either streptomycin or glucose, or an incubation temperature of 37 C, inhibited the proline-induced pigmentation by washed cells. Further investigations provided insights to these findings.

THE BIOSYNTHESIS OF GRAMICIDIN S IN A CELL-FREE SYSTEM

1. A cell-free system prepared from Bacillus brevis cells, harvested in the late phase of growth and consisting of the 11000g supernatant, has been shown to incorporate into gramicidin S the five constituent amino acids added in labelled form. The results are consistent with complete synthesis and not merely a completion of pre-existing intermediate peptides. 2. The incorporation of (14)C-labelled amino acids by the 11000g supernatant into gramicidin S requires an energy source. Omission of phosphoenolpyruvate and pyruvate kinase from the incubation mixture prevents incorporation into gramicidin S. The cell-free system incorporates [(14)C]-leucine, -proline and -phenylalanine over a period of 4hr. With [(14)C]leucine, incorporation into gramicidin S takes place in the range pH6-9 with maximum incorporation at pH7.0. High concentrations of chloramphenicol or puromycin decreased the incorporation into gramicidin S by only about 20%. 3. The 50000g supernatant exhibited no decrease in ability of incorporating [(14)C]valine into gramicidin S as compared with the 11000g supernatant. About 40% of the incorporating ability remained in the 105000g supernatant after 3hr. centrifugation. When recombining the 105000g sediment with the 105000g supernatant, some increase in incorporation over that obtained with the supernatant alone was obtained. The findings tend to support the view that gramicidin S is synthesized in a different manner from that of proteins.

DIFFERENTIAL MUTATION PRODUCTION BY THE DECAY OF INCORPORATED TRITIUM COMPOUNDS IN E. COLI

We have studied the differential mutation production by the decay of incorporated tritium compounds in E. coli (WWU) using DNA-seeking precursors (H(3)-thymidine), RNA-seeking precursors (H(3)-uracil, H(3)-uridine), and protein-seeking precursors (H(3)-histidine, H(3)-proline). In particular we have determined the reversion frequency of an arginine locus. The reversion frequency is measured in units of revertants/surviving bacteria/H(3) decay, and has an average value of 1.84 x 10(-8) for H(3)-uridine and H(3)-uracil, 0.67 x 10(-8) for H(3)-thymidine, and 0.28 x 10(-8) for H(3)-proline and H(3)-histidine. Thus, the revertants are produced most effectively by H(3) decays when the label is introduced in the form of an RNA precursor. The macromolecular distribution of the label shows that 5 to 8 per cent of the H(3)-uridine or H(3)-uracil is incorporated into DNA.

PHYSIOLOGY OF THE SPORULATION PROCESS IN CLOSTRIDIUM BOTULINUM. II. MATURATION OF FORESPORES

Day, Lawrence E., (Michigan State University, East Lansing) and Ralph N. Costilow. Physiology of the sporulation process in Clostridium botulinum. II. Maturation of forespores. J. Bacteriol. 88:695-701. 1964.-Clostridium botulinum, strain 62-A, did not sporulate endotrophically, but forespores matured to refractile, heat-resistant spores when replaced in solutions containing l-alanine and l-proline, l-isoleucine and l-proline, or l-alanine and l-arginine. Solutions of l-arginine or l-citrulline would not support the maturation process. Acetate, CO(2), and delta-amino valeric acid were produced during sporulation in a replacement solution of l-alanine and l-proline, indicating the operation of the Stickland reaction. There was no large uptake of either exogenous l-alanine or acetate during this process. Similarly, there was no apparent protein or nucleic acid synthesis, since high levels of chloramphenicol, 8-azaguanine, or mitomycin C failed to inhibit, and no significant amount of P(32) was incorporated into the spore nucleic acids. Dipicolinic acid (DPA) was synthesized during forespore maturation. It is believed that these final steps in sporulation of C. botulinum require only an exogenous source of energy which can be obtained via the Stickland reaction system, and that the synthesis of DPA and other unknown materials relies primarily on endogenous substrates.

BIOSYNTHESIS OF COLLAGEN AND NON-COLLAGEN PROTEIN DURING DEVELOPMENT OF THE CHICK CORNEA

The relationship between the rates of increase of corneal protein fractions and incorporation of labeled precursors has been examined during embryonic and early posthatching development of the chick corneal stroma. Non-collagen protein increased gradually from 9 through 20 days of incubation. Collagen accumulated approximately logarithmically through the 19th day, the most rapid rate occurring between 13 and 20 days of incubation. The rates at which labeled amino acids are incorporated into collagen in vivo and in vitro undergo marked changes during the last week of embryonic development, corresponding closely to the rate of collagen accumulation in vivo; whereas incorporation into non-collagen protein changes much less markedly. Changes in the rate of incorporation of precursors into collagen are not due to changes in the rate of conversion of collagen from the soluble to insoluble form, or to changes in the endogenous amino acid pool size. Chick embryo corneal stroma collagen turns over very slowly, if at all. Non-collagen protein turns over more rapidly. An increase in cell number, as indicated by DNA content, does not account for the increased rate of collagen synthesis between the 9th and 16th day of incubation. It is concluded that the observed changes in collagen synthesis reflect changing activities in the individual cornea fibroblasts. These activities are comparable in the intact tissue in vivo and in isolated corneas in vitro.

PREFERENTIAL SYNTHESIS OF ALPHA-AMYLASE BY BACILLUS STEAROTHERMOPHILUS IN THE PRESENCE OF 5-METHYL-TRYPTOPHAN

Welker, N. E. (Western Reserve University, Cleveland, Ohio), and L. Leon Campbell. Preferential synthesis of alpha-amylase by Bacillus stearothermophilus in the presence of 5-methyl-tryptophan. J. Bacteriol. 87:828-831. 1964.-Washed-cell suspensions of Bacillus stearothermophilus induced with pure maltose preferentially synthesized alpha-amylase in the presence of 5-methyl-tryptophan (5-MT). 5-MT did not inhibit the formation of active alpha-amylase or the incorporation of proline-C(14) into alpha-amylase. In contrast, p-fluorophenylalanine inhibited the formation of active alpha-amylase by 92% and the incorporation of proline-C(14) into the enzyme by 95%. p-Fluorophenylalanine and 5-MT inhibited cellular protein synthesis, as measured by proline-C(14) incorporation, by 74 and 72%, respectively.