Occurrence of pppApp-synthesizing activity in actinomycetes and isolation of purine nucleotide pyrophosphotransferase

The occurrence of adenosine 5-triphosphate-3-diphosphate-synthesizing activity was detected in five strains of actinomycetes; Streptomyces morookaensis, Streptomyces aspergilloides, Streptomyces hachijoensis, Actinomyces violascens and Streptoverticillium septatum, out of 825 strains of actinomycetes, bacteria, fungi and imperfecti. Purine nucleotide pyrophosphotransferase were extracellularly excreted associating with the cell growth, and were purified partially or to apparent homogeniety from the culture filtrate. The enzymes are a monomeric protein with a molecular weight of 18000–26000 and synthesize adenosine, guanosine and inosine 5-phosphate (mono, di or tri)-3-diphosphate such as pApp, ppApp, pppApp, pGpp, ppGpp, pppGpp and pppIpp by transferring a pyrophosphoryl group from the 5-position of ATP, dATP and pppApp to the 3-position of purine nucleotides in the presence of a divalent cation and in alkaline state.Abbreviations pppApp adenosine 5-triphosphate 3-diphosphate - ppApp adenosine 5-diphosphate 3-diphosphate - pApp adenosine 5-monophosphate 3-diphosphate - pppGpp guanosine 5-triphosphate 3-diphosphate     

Genetic and biochemical studies on flavonoid 3′-hydroxylation in flowers of Petunia hybrida

Summary In flower extracts of defined genotypes of Petunia hybrida, an enzyme activity was demonstrated which catalyses the hydroxylation of naringenin and dihydrokaempferol in the 3-position. Similar to the flavonoid 3-hydroxylases of other plants, the enzyme activity was found to be localized in the microsomal fraction and the reaction required NADPH as cofactor. A strict correlation was found between 3-hydroxylase activity and the gene Ht1, which is known to be involved in the hydroxylation of flavonoids in the 3-position in Petunia. Thus, the introduction of the 3-hydroxyl group is clearly achieved by hydroxylation of C₁₅-intermediates, and the concomitant occurrence of the 3,4-hydroxylated flavonoids quercetin and cyanidin (paeonidin) in the presence of the functional allele Ht1 is due to the action of one specific hydroxylase catalysing the hydroxylation of common precursors for both flavonols and anthocyanins.     

Enzymic synthesis,chemical characterisation and Sda activity of GalNAcß1-4[NeuAcα2-3]Galß1-4GlcNAc and GalNAcß1-4[NeuAcα2-3]Galß1-4Glc

The tetrasaccharides GalNAcß1-4[NeuAc2-3]Galß1-4Glc and GalNAcß1-4[NeuAc2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3-sialyllactose (NeuAc2-3Galß1-4Glc) and 3-sialyl-N-acetyllactosamine (NeuAc2-3Galß1-4GlcNAc). The structures of the products were established by methylation and¹H-500 MHz NMR spectroscopy. In Sd^a serological tests the product formed with 3-sialyl-N-acetyllactosamine was highly active whereas that formed with 3-sialyllactose had only weak activity.     

Full 1H NMR assignment of a 24-nucleotide RNA hairpin: Application of the 1H 3D-NOE/2QC experiment

The subject RNA models the binding site for the coat protein of the R17 virus, as well as the ribosome recognition sequence for the R17 replicase gene. With an RNA of this size, overlaps among the sugar protons complicate assignments of the ¹H NMR spectrum. The cross peaks that overlap significantly in 2D-NOE spectra can frequently be resolved by introducing a third, in our approach the double-quantum, frequency axis. In particular the planes in a 3D-NOE/2QC spectrum perpendicular to the 2Q axis are extremely useful, showing a highly informative repeating NOE-2Q pattern. In this experiment substantial J-coupling confers special advantages. This always occurs for geminal pairs (H5/H5 for RNA plus H2/H2 for DNA), as well as for H5/H6, for H3/H4 in sugars with substantial populations of the N-pucker, for H1/H2 for S-puckered sugars, and usually for H2/H3. For the 24-mer RNA hairpin the additional information from the 3D-NOE/2QC spectrum allowed assignment of all of the non-exchangeable protons, eliminating the need for stable-isotope labeling.     

Cyanine dye structural and voltage-induced variations in photo-voltages of bilayer membranes

Summary Flash illumination alters the voltage across bilayer lipid membranes in the presence of certain cyanine dyes. The waveforms of the photo-voltage vary systematically with dye structure and imposed transmembrane voltage. Experimental results are reported for 27 positively charged cyanine dyes, primarily oxazole derivatives, using lecithin/oxidized cholesterol bilayer membranes and 10-mm sodium chloride solutions. Several dyes do not induce any photo-voltages. Examples are 3,3 diethyl 9 ethyl 2,2 oxacarbocyanine iodide, 3,3 diethyl 2 oxa 2 thiacyanine iodide, and 3,3 dimethyl 2,2 indocarbocyanine iodide. Several dyes, when added to one side of the membranes, induce monophasic waveforms. Examples are 3,3 dimethyl 2,2 oxacarbocyanine chloride, and 3,4,3,4 tetramethyl 2,2 oxazalinocarbocyanine iodide. Other dyes induce a photo-voltage only if transmembrane voltages are imposed. These waveforms are biphasic with some dyes (3,3 diethyl 2,2 oxacarbocyanine iodide, for example) and monophasic with other dyes (3,3 dibutyl 2,2 oxacarbocyanine iodide, for example).The photo-voltage waveforms are explained by models that consider the movement of charged dye molecules within the membrane, following optical excitation. The dye movements are probably induced through charge rearrangements in the dye associated with long-lived triplet states, isomerization, or through excimer formation. These results provide information on the location and orientation of the dye molecules within bilayer membranes. The variations which occur in the waveforms with applied voltage indicate that these membranes are fluid in the direction perpendicular to the membrane plane.     

Formation of the imidazolides of dinucleotides under potentially prebiotic conditions

Summary Imidazolides of dinucleotides such as ImpApA can be formed from the corresponding dinucleotides in a two-stage process, which gives up to 15% yields under potentially prebiotic conditions. First a solution of the dinucleotide and sodium trimetaphosphate is dried out at constant temperature and humidity. This produces polyphosphates such as pnApA in excellent yield (80%). The products are dissolved in water, imidazole is added, and the solution is dried out again. This yields the 5-phosphorimidazolides.Abbreviations P₃! trimetaphosphate - A adenosine - U uridine - EDTA ethylenediaminetetraacetic acid - Ap adenosine 2(3)-phosphate - Ap! adenosine cyclic 2:3-phosphate - pA adenosine 5-phosphate - pA²p adenosine 2, 5-diphosphate - pA³p adenosine 3, 5-diphosphate - pAp! 5-phospho-adenosine cyclic 2:3-phosphate - ATP adenosine 5-triphosphate - ImpA adenosine 5-phosphorimidazolide - A²pA adenylyl-[25]-adenosine - A³pA adenylyl-[35]-adenosine - A²pU adenylyl-[25]-uridine - A³pU adenylyl-[35]-uridine - pA²pA 5-phosphoadenylyl-[25]-adenosine - pA³pA 5-phospho-adenylyl-[35]-adenosine - pA²pU 5-phospho-adenylyl-[25]-uridine - pA³pU 5-phospho-adenylyl-[35]-uridine - pApN (N= A, U) 5-phosphate of a dinucleoside phosphate - p_nApN (N = A, U; n = 2, 3, 4.) 5-polyphosphate of a dinucleoside phosphate - ImpA²pA imidazolide of pA²pA - ImpA³pA imidazolide of pA³pA - ImpA²pU imidazolide of pA²pU - ImpA³pU imidazolide of pA³pU - ImpApN imidazolide of pApN     

Untersuchungen zum C′3-Polymorphismus (β 1c-Globulin)

Zusammenfassung Serumproben von 1322 Blutspendern aus Hessen, 40 Familien mit 89 Kindern, 20 Mutter-Kind-Kombinationen und 268 Sera einer Bantupopulation aus Portugiesisch Angola wurden mit einer modifizierten Technik der Hochspannungs-Dünnschichtelektrophorese auf Agarosegel hinsichtlich des C3-Polymorphismus untersucht. Die Genfrequenzen für Weiße (C3^S=0.779, C3^F=0.215) und Neger (C3^S=0.95, C3^F=0,048) stimmen gut mit den Werten anderer Autoren überein. Insgesamt ließen sich bei Weißen 9 Phänotypen sicher abgrenzen, bei Negern 3. Familienstudien bestätigten den für die Allele C3^S und C3^F angenommenen Vererbungsmodus (autosomal codominant) ausnahmslos. Die Frage der Lagerungsstabilität des C3 wurde abschließend untersucht.

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Investigations on C3-polymorphism ( _1c-Globulin)Gene frequencies and family studies in blood donors from Hessen and a Bantu population

Summary Serum samples of 1322 unrelated individuals from Hessen (Germany), 40 families with 89 children, 20 mother-child-combinations and 268 sera of a Bantu population from Angola were examined for C3 polymorphism using a modified technique of high voltage agarose gel electrophoresis. The gene frequencies for Caucasians (C3^S=0.779, C3^F=0.215) and negroes (C3^S=0.95, C^F=0.048) are in good accordance with those obtained by other authors. In total 9 different phenotypes were observed in Caucasians, 3 phenotypes in negroes. Family studies verify the supposed way of inheritance (autosomal codominant for C3^S and C3^F) without exception. Finally the problem of C3-inactivation by storage was investigated.

     

Changes in brain components during the development of mice homozygous for the locus “dwarf” (dw)1,5

Brain composition and developmental changes were investigated in mice homozygous for the locus dwarf, and characterized by a reduced level of growth hormone, thyroid stimulating hormone, and prolactin, and by secondary hypothyroidism. The difference in adult brain weight (–32%) between the dwarf and the normal mice was not found to parallel the difference in body weight (–71%), whereas the differences in the weight of the liver (–79%) and that of the kidney (–75%) did. Several biochemical parameters of brain development were assayed in dwarf and normal mice between the ages of 15 and 210 days. Levels of cerebrosides, sulfatides, gangliosides, phospholipids, cholesterol, protein, and RNA (per gram wet weight) were the same for the dwarf and the controls, but the net difference in total brain DNA was less than the net total brain RNA difference (–11% vs. –27%). Total brain lipids (absolute quantities) were the same at 15 days. The difference was –37% by the 50th day, and remained constant thereafter. No change in the specific activity of 2,3-cyclic nucleotide 3-phosphohydrolase or 3-phosphoadenosine-5-phosphosulfate: galactocerebroside sulfotransferase was observed. These data suggest that the regulation of the development of brain structures is maintained, but the level of the synthesis of the various brain constituents is reduced in proportion to the brain weight. The development of the dwarf brain seems to proceed harmoniously.Abbreviations used PAPS 3-phosphoadenosine-5-phosphosulfate - PAPS-CST 3-phosphoadenosine-5-phosphosulfate:galactocerebroside sulfotransferase - CNP 2, 3-cyclic nucleotide 3-phosphohydrolase - Neu NAc N-acetylneuraminic acid This paper is part of the Doctorat d'Etat thesis of L. L. Sarliève.     

Sensitive 1H-31P correlations with 5′ methylene protons of DNA via homonuclear double-quantum coherence

A novel pulse sequence is presented for the correlation of 5 and 5 protons in DNA with phosphorus. Double-quantum coherence between the methylene protons is used to generate ¹H5-³¹P and ¹H5-³¹P cross peaks in an HMQC-type experiment. The resolution for these cross peaks is significantly improved over that of conventional HSQC experiments, as cross peaks between ¹H4 and ³¹P are largely suppressed and a 3D version of the experiment can be performed with little penalty in sensitivity. In addition, sensitivity is favoured by slower relaxation of the double-quantum coherence and a more favourable multiplet fine structure in the acquisition dimension.     

The investigation of the hcn derivative diiminosuccinonitrile as a prebiotic condensing agent. The formation of phosphate esters

Diiminosuccinonitrile (DISN) is formed readily by the Fe³⁺ oxidation of diaminomaleonitrile, a tetramer of HCN. DISN effects the phosphorylation of uridine in 13% yield to a mixture of the isomers of UMP when the reaction is performed in dimethylformamide solution. A 4% yield of the UMP isomers is obtained in neutral aqueous solution using 2 times the DISN concentration and 7 times the phosphate concentration used in DMF. DISN did not effect the conversion of adenosine to AMP or 5-AMP to 5-ADP in aqueous solution. The cyclization of 3-AMP and 3-UMP to the corresponding 2,3-cyclic phosphates proceeds in yields as high as 40–50% at 60°C in pH 6 aqueous solutions in the presence of divalent metal ions. Lower yields of the cyclic phosphate are observed when 2-AMP is the starting material. Substitution of acetate buffer for imidazole buffer results in a decrease in the yield of cyclic phosphate, the extent of which depends on the metal ion used in the reaction. No 3,5-cyclic AMP was detected as a reaction product with either 5-AMP or 3-AMP as the starting material except for a 2.4% yield from 3-AMP in the presence of Zn²⁺. BrCN effects the conversion of 3-AMP to the 2,3-cyclic AMP in 37–65% yield depending on the divalent cation used as catalyst. A mechanism has been proposed for these cyclization reactions and their potential significance to the prebiotic synthesis of ribonucleic acid derivatives is discussed.Chemical Evolution 41. For previous paper see Ferris, J.P., Hagan, W.J., Jr., Alwis, K. W., and McCrea, J.: 1982,J. Mol. Evol. 18, 304–309.Presented at the 7th International Conference on The Origins of Life, Mainz, F.R.G., 1983.     

Synthesis of affinity chromatography resins for the purification of brain glutamate decarboxylase

In the present paper we describe the synthesis of Sepharose-boundN-(5-phosphopyridoxyl)-amino-oxyacetic acid,N-(5-phosphopyridoxyl)-canaline, andN-(5-phosphopyridoxyl)-,-diaminobutyric acid (Seph-DAB-PLP), designed for binding specifically brain glutamate decarboxylase (GAD). The three Sepharose-N-(phosphopyridoxyl)-amino acids were capable of binding GAD from a mouse brain soluble preparation. The enzyme can be purified up to 25-fold in one step by affinity chromatography on Seph-DAB-PLP.Part of this work was presented at the VI Meeting of the American Society for Neurochemistry, Mexico City, March 10–14, 1975.     

Sugar conformation of a stereospecific 2′-R or 2′-S deuterium-labeled DNA decamer studied with proton-proton J coupling constants

The sugar conformation of a DNA decamer was studied with proton-proton ³J coupling constants. Two samples, one comprising stereospecifically labeled 2-R-²H for all residues and the other 2-S-²H, were prepared by the method of Kawashima et al. [J. Org. Chem. (1995) 60, 6980–6986; Nucleosides Nucleotides (1995) 14, 333–336], the deuterium labeling being highly stereospecific 99% for all 2-²H, 98% for 2-²H of A, C, and T, and 93% for 2-²H of G). The ³J values of all H1-H2 and H1-H2 pairs, and several H2-H3 and H2-H3 pairs were determined by line fitting of 1D spectra with 0.1–0.2 Hz precision. The observed J coupling constants were explained by the rigid sugar conformation model, and the sugar conformations were found to be between C3-exo and C2-endo with _m values of 26° to 44°, except for the second and 3 terminal residues C2 and C10. For the C2 and C10 residues, the lower fraction of S-type conformation was estimated from J_H1H2 and J_H1H2 values. For C10, the N–S two-site jump model or Gaussian distribution of the torsion angle model could explain the observed J values, and 68% S-type conformation or C1-exo conformation with 27° distribution was obtained, respectively. The differences between these two motional models are discussed based on a simple simulation of J-coupling constants.     

The catalysis of nucleotide polymerization by compounds of divalent lead

Summary Soluble lead salts and a number of lead-containing minerals catalyze the formation of oligonucleotides from nucleoside 5-phosphorimidazolides. The effectiveness of lead compounds correlates strongly with their solubility. Under optimal conditions we were able to obtain 18% of pentamer and higher oligomers from ImpA. Reactions involving ImpU gave smaller yields.Abbreviations A adenosine - U uridine - Im imidazole - MeIm 1-methyl-imidazole - EDTA ethylenediaminetetraacetic acid - pA adenosine 5-phosphate - pU uridine 5-phosphate - Ap adenosine cyclic 2:3-phosphate - ATP adenosine 5-triphosphate - AppA P₁,P₂-diadenosine 5-diphosphate - pNp (N = A,U) nucleotide 2(3), 5-diphosphate - ImpA adenosine 5-phosphoreimidazolide - ImpU uridine 5-phosphorimidazolide - A ²pA adenylyl-[25]-adenosine - A ³pA adenylyl-[35]-adenosine - pA ²pA 5-phospho-adenylyl-[25]-adenosine - pA ³pA 5-phospho-adenylyl-[35]-adenosine - pUpU 5-phospho-uridylyl-uridine - pApU 5-phospho-adenylyl-uridine - pUpA 5-phospho-uridylyladenine - (pA)n (n, 2,3,4,) oligoadenylates with 5 terminal phosphate - ImpApA 5-phosphorimidazolide of adenylyl adenosine - (pA) ₅₊ pentamer and higher oligoadenylates with 5 terminal phosphate - (Ap)nA (n = 2,3,4) oligoadenylates without terminal phosphates In the following we do not specify the nature of the internucleotide linkageIn the following we do not specify the nature of the internucleotide linkage     

The formation of peptides from the 2′(3′)-glycyl ester of a nucleotide

Summary We have synthesized 2(3)-O-(glycyl)-adenosine-5-(O-methylphos-phate), an analogue of the 3-terminus of aminoacylated tRNA. A 0.4M solution of this compound maintained at pH 8.2, yields 5.5% of diglycine and 11.5% of diketopiperazine, in addition to the hydrolysis products glycine and adenosine-5-(O-methylphosphate). Under the same conditions, glycine ethyl ester reacts much more slowly, but ultimately gives similar yields of diglycine and diketopiperazine.The aminolysis of 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) by free glycine is relatively inefficient, but serine reacts 20 times more rapidly and yields up to 50% of N-glycylserine. The prebiotic significance of these reactions is discussed.Abbreviations MepA adenosine-5-(O-methylphosphate) - MepA-gly 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) - MepA-bis-gly 2,3-O-(bis-glycyl)-adenosine-5-(O-methylphosphate) - DKP diketopiperazine - gly Et glycine ethyl ester - gly-ser N-glycylserine - O-gly-ser O-glycylserine - O-(gly)-gly-ser O-(glycyl)-glycylserine - Boc-gly N-tert-butyloxycarbonylglycine - MepA-Boc-gly 2(3)-O-(Boc-glycyl)-adenosine-5-(O-methylphosphate) - MepA-bis-Boc-gly 2,3-O-(bis-Boc-glycyl)-adenosine-5(O-methylphosphate) - (gly)₂ diglycine - (gly)₃ triglycine     

Geometry of the dry-state oligomerization of 2′,3′-cyclic phosphates

Summary Evaporation of a solution of thymidine plus either theexo or theendo diastereomer of uridine cyclic 2,3-O, O-phosphorothioate (U > p(S) in 1,2-diaminoethane hydrochloride buffer gave the 2,5 and 3,5 isomers of (P-thio) uridylylthymidine (Up(S)dT) in a ratio of 1:2 with a combined yield of about 20%. These isomers were re-converted to U > p(S) and dT by a reaction that is known to proceed by an in-line mechanism. Both the 2,5 and 3,5 isomers gave as product the same diastereomer of U > p(S) that had been used originally in their formation. These dry-state prebiotic reactions (Verlander, Lohrmann, and Orgel 1973) are thus shown to be stereospecific, and both the 2,5 and 3,5 internucleotide bonds are formed by an in-line mechanism.Abbreviations DAE 1,2-diaminoethane - HPLC high pressure liquid chromatography - RNase bovine pancreatic ribonuclease A, EC 3.1.4.22 - TEAB triethylammonium bicarbonate - tris tris(hydroxymethyl)aminomethane - UMP(S) uridine monophosphorothioate - U > p uridine cyclic 2,3-phosphate - U > p(S) uridine cyclic 2,3-O, O-phosphorothioate - Up(S)dT (P-thio)uridylylthymidine - U2p(R_p-S)5dT (P-thio)uridylylthymidine with theR configuration at phosphorous, and a 2,5 internucleotide linkage     

Formation of P1, P2-dinucleoside 5′-pyrophosphates under potentially prebiological conditions

Summary Organic pyrophosphates such as UppA and NAD are formed when a solution containing a nucleotide, a nucleoside 5-polyphosphate, Mg²⁺ and imidazole are allowed to dry out. We suggest that this synthesis may have occured concurrently with oligonucleotide formation.Abbreviations Im Imidazole - CDI 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride - EDTA ethylenediaminetetraacetic acid - A adenosine - U uridine - p_nA adenosine 5-poly-phosphate containing n phosphate residues - pU uridine 5-phosphate - AppA P₁,P₂-diadenosine 5-pyrophosphate - UppA P₁-(uridine 5)-P₂-(adenosine 5)-pyrophosphate - ImpA adenosine 5-phosphorimidazolide - NMN nicotinamide mononucleotide - NAD nicotinamide-adenine dinucleotide     

Adenosine-5′-phosphosulfate (APS) as sulfate donor for assimilatory sulfate reduction in Rhodospirillum rubrum

Crude extracts of Rhodospirillum rubrum catalyzed the formation of acid-volatile radioactivity from (³⁵S) sulfate, (³⁵S) adenosine-5-phosphosulfate, and (³⁵S) 3-phosphoadenosine-5-phosphosulfate. An enzyme fraction similar to APS-sulfotransferases from plant sources was purified 228-fold from Rhodospirillum rubrum. It is suggested here that this enzyme is specific for adenosine-5-phosphosulfate, because the purified enzyme fraction metabolized adenosine-5-phosphosulfate, however, only at a rate of 1/10 of that with adenosine-5-phosphosulfate. Further, the reaction with 3-phosphoadenosine-5-phosphosulfate was inhibited with 3-phosphoadenosine-5-phosphate whereas this nucleotide had no effect on the reaction with adenosine-5-phosphosulfate. For this activity with adenosine-5-phosphosulfate the name APS-sulfotransferase is suggested. This APS-sulfotransferase needs thiols for activity; good rates were obtained with either dithioerythritol or reduced glutathione; other thiols like cysteine, 2-3-dimercaptopropanol or mercaptoethanol are less effective. The electron donor methylviologen did not catalyze this reaction. The pH-optimum was about 9.0; the apparent K _m for adenosine-5-phosphosulfate was determined to be 0.05 mM with this so far purified enzyme fraction. Enzyme activity was increased with K₂SO₄ and Na₂SO₄ and was inhibited by 5-AMP. These properties are similar to assimilatory APS-sulfotransferases from spinach and Chlorella.Abbreviations APS adenosine-5-phosphosulfate - PAPS 3-phosphoadenosine-5-phosphosulfate - 5-AMP adenosine-5-monophosphate - 3-AMP adenosine-3-monophosphate - 3-5-ADP 3-phosphoadenosine-5-phosphate (PAP) - DTE dithiorythritol - GSH reduced glutathione - BAL 2-3-dimercaptopropanol     

Prebiotic Formation of ADP and ATP from AMP,Calcium Phosphates and Cyanate in Aqueous Solution

Adenosine-5-triphosphate was synthesized by the phosphorylation of adenosine-5-diphosphate in aqueous solution containing cyanate as a condensing reagent and insoluble calcium phosphate produced from phosphate and calcium chloride. In a similar manner, adenosine-5-diphosphate was synthesized from adenosine-5-monophosphate. When the experiment was carried out in the conditions of 4 °C and pH 5.75, the formation of adenosine-5-diphosphate and adenosine-5-triphosphate from adenosine-5-monophosphate was observed in the yields of 19 and 7%, respectively. The other nucleoside-5-triphosphates were also produced from their respective diphosphates.     

A measure of response to perturbation used to assess structural change in some polluted and unpolluted stream fish communities

Summary A new method for measuring structural change in sets of species which have been subjected to natural or experimental perturbation is developed and is shown to be superior to static diversity and evenness measures for this purpose. Three parameters, H, J, and X;} are shown to provide necessary and sufficient information on the severity of a perturbation as well as the uniformity of its effect on all species in the set. When positive and negative changes in species abundance are considered separately, the method is sensitive to compensatory changes which are not detected by static measures.The parameters are then calculated for some data sets on polluted and unpolluted fish communities in second and third order streams from the Clemons Fork watershed in eastern Kentucky. Results indicate that H, the diversity of change over two sampling seasons, is high for perturbed and unperturbed systems, but J the eveness of change is lower for the communities which were polluted in the second sampling season. Severe pollution results in the suppression of most major fish species, whereas more moderate pollution results in a large number of compensatory changes. The biological basis for such an outcome is discussed, and the notion of these three parameters as the vital signs of a healthy ecosystem is presented.     

Non-coordinate synthesis of RNA polymerase beta beta'' subunits in a temperature-sensitive beta''-subunit mutant of Escherichia coli

Summary On exposure to high temperature of a temperature-sensitive RNA polymerase subunit (rpoC92) mutant of Escherichia coli, selective reduction was observed in the rate of synthesis of a group of proteins including RNA polymerase subunit. The finding that the synthesis of subunit but not subunit was specifically repressed in this mutant grown at non-permissive temperature indicates that the functionally intact RNA polymerase is required for the synthesis of subunits be coordinated. In addition, the assembly of newly synthesized RNA polymerase subunits was inefficient in this mutant at the steps where altered subunit was involved, and the unassembled enzyme subunits were rapidly and preferentially degraded. During recovery to non-restricted growth, the synthesis of both and subunits was transiently enhanced in parallel leading to recovery of the intracellular concentration of functional RNA polymerase.