Mutant of the glutamine transfer RNA gene as UGA suppressor in Escherichia coli

Summary A UGA suppressor derived from a glutamine tRNA gene of Escherichia coli K 12 was isolated and characterized. Phages carrying the suppressor su⁺2_UGA could be obtained only from a hybrid transducing phage, h ⁸⁰ cI ₈₅₇psu ⁺2_oc, but not from the original transducing phage cI ₈₅₇psu ⁺2_oc. By DNA sequence analysis, it was found that the su ⁺2 UGA suppressor obtained has two mutations; one is in the anticodon (TTATCA), as expected, and the other (CT) is at the 7th position from the 3 end of tRNA ₂ ^Gln . The significance of these mutations and the lethal effect on phage of the increased amounts of UGA suppressor tRNAs are discussed.     

Synthesis of Aminoethyl Glycosides of the Ganglioside GM1 and Asialo-GM1 Oligosaccharide Chains

4-O-Glycosylation of 2-azidoethyl 2,3,6-tri-O-benzyl-4-O-(2,3-di-O-benzyl-6-O-benzoyl--D-galactopyranosyl)--D-glucopyranoside with a disaccharide donor, 4-trichloroacetamidophenyl 4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-1-thio-2-trichloroacetamido--D-galactopyranoside, in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid resulted in a tetrasaccharide, 2-azidoethyl (2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-(1 3)-(4,6-di-O-acetyl-2-deoxy-2-trichloroacetamido--D-galactopyranosyl)-(1 4)-(2,3-di-O-benzyl-6-O-benzoyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside, in 69% yield. The complete removal of O-protecting groups in the tetrasaccharide, the replacement of N-trichloroacetyl by N-acetyl group, and the reduction of the aglycone azide group to amine led to the target aminoethyl glycoside of -D-Gal-(1 3)--D-GalNAc-(1 4)--D-Gal-(1 4)--D-Glc-OCH₂CH₂NH₂ containing the oligosaccharide chain of asialo-GM₁ ganglioside in 72% overall yield. Selective 3-O-glycosylation of 2-azidoethyl 2,3,6-tri-O-benzyl-4-O-(2,6-di-O-benzyl--D-galactopyranosyl)--D-glucopyranoside with thioglycoside methyl (ethyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero--D-galacto-2-nonulopyranosyl)oate in acetonitrile in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid afforded 2-azidoethyl [methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero--D-galacto-2-nonulopyranosyl)oate]-(2 3)-(2,6-di-O-benzyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside, the selectively protected derivative of the oligosaccharide chain of GM₃ ganglioside, in 79% yield. Its 4-O-glycosylation with a disaccharide glycosyl donor, (4-trichloroacetophenyl-4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl--D-galactopyranosyl) 1-thio-2-trichloroacetamido--D-galactopyranoside in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid gave 2-azidoethyl (2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-(1 3)-(4,6-di-O-acetyl-2-deoxy-2-trichloroacetamido--D-galactopyranosyl)-(1 4)-{[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero--D-galacto-2-nonulopyranosyl)onate]-(2 3)}-(2,6-di-O-benzyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside in 85% yield. The resulting pentasaccharide was O-deprotected, its N-trichloroacetyl group was replaced by N-acetyl group, and the aglycone azide group was reduced to afford in 85% overall yield aminoethyl glycoside of -D-Gal-(1 3)--D-GalNAc-(1 4)-[-D-Neu5Ac-(2 3)]--D-Gal-(1 4)--D-Glc-OCH₂CH₂NH₂ containing the oligosaccharide chain of GM₁ ganglioside.     

Interrelationships Between Nitrogen Supply and Photosynthetic Parameters in Vicia faba L.

We determined for Vicia faba L the influence of nitrogen uptake and accumulation on the values of photon saturated net photosynthetic rate (P _Nmax), quantum yield efficiency (), intercellular CO₂ concentration (C _i), and carboxylation efficiency (C _e). As leaf nitrogen content (N_L) increased, the converged onto a maximum asymptotic value of 0.0664±0.0049 mol(CO₂) mol(quantum)^–1. Also, as N_L increased the C _i value fell to an asymptotic minimum of 115.80±1.59 mol mol^–1, and C _e converged onto a maximum asymptotic value of 1.645±0.054 mol(CO₂) m^–2 s^–1 Pa^–1 and declined to zero at a N_L-intercept equal to 0.596±0.096 g(N) m^–2. fell to zero for an N_L-intercept of 0.660±0.052 g(N) m^–2. As N_L increased, the value of P _Nmax converged onto a maximum asymptotic value of 33.400±2.563 mol(CO₂) m^–2 s^–1. P _N fell to zero for an N_L-intercept of 0.710±0.035 g(N) m^–2. Under variable daily meteorological conditions the values for N_L, specific leaf area (_L), root mass fraction (R_f), P _Nmax, and remained constant for a given N supply. A monotonic decline in the steady-state value of R_f occurred with increasing N supply. _L increased with increasing N supply or with increasing N_L.     

Osmotic potential and turgor maintenance in Spartina alterniflora Loisel.

Summary The dependence of leaf water potential (), osmotic potential () and turgor pressure (P) on relative water content (RWC) was determined for leaves of tall and short growth forms of Spartina alterniflora Loisel. from a site on Canary Creek marsh in Lewes, Delaware. Tall plants (ca. 1.5 m) occured along a drainage ditch where interstitial water salinity was approximately 20, and short plants (ca. 0.2 m) were 13 m away near a pan and exposed to 80 salinity during the most stressful period. Leaves were collected at dawn and pressure-volume measurements were made as they desiccated in the laboratory. Pressure equilibrium was used to measure , RWC was determined from weight loss and dry weight, was determined from the pressure volume curve, and P was calculated as the difference between and . Physical properties of the bulk leaf tissue that have a role in regulating water balance of the two growth forms were estimated: relative water content of apoplastic water (RWC_a) relative water content at zero turgor (RWC₀), the bulk modulus of elasticity (E), and water capacity (C _w). There were no detectable temporal trends in any of the parameters measured from Nune through September and no significant differences between the two growth forms when compared on the basis of RWC_a, RWC₀, E, and C _w. There was a clear difference between the two growth forms with respect to ; at RWC₀, was-4.5±0.40 MPa for short form plants and-3.3±0.40 MPa for tall form.Turgor pressure of plants in the field (P) was lower in leaves from short form than for the tall form plants with average difference of about 0.4 MPa. In July, P in short form leaves dropped to zero by mid-morning as expected for leaves experiencing water stress.These results show that S. alterniflora is capable of reducing osmotic potential in response to increased salinity and that turgor pressure was lower in short growth form than in tall forms.     

Responses of nitrogen-fixing and nitrate-supplied alfalfa (Medicago sativa L.) to iron chelates in an alkaline hydroponic medium

Ferric ethylenediamine di-(o-hydroxyphenylacetate) (FeEDDHA) and ferric hydroxyethylethylenediaminetriacetic acid (FeHEDTA) were evaluated as Fe sources for hydroponic growth of alfalfa (Medicago sativa L., cv. Mesilla), either dependent on N₂ fixation or supplied with NO₃. The hydroponic medium was maintained at pH 7.5 by addition of CaCO₃. Nitrogen-fixing cultures were inoculated with Rhizobium meliloti 102 F51 and grown in medium without added nitrogen. After five to seven weeks of growth under greenhouse conditions, plants were harvested. Nitrogen fixation was measured by the acetylene reduction method.When FeEDDHA was supplied, growth of alfalfa, whether dependent on N₂ fixation or supplied with NO₃, was severely limited at concentrations typically used in hydroponic medium (10 or 20 M). Maximum yield of NO₃-supplied alfalfa was obtained at 100 M while maximum yield of N₂-fixing alfalfa was obtained in the range of 33 to 200 M FeEDDHA. Nodule fresh weights and N₂ fixation rates increased with FeEDDHA concentration up to 33 M and remained essentially constant up to 200 M. With FeHEDTA, maximum yields of both NO₃-grown and N₂-fixing alfalfa were obtained at 10 M. Growth of NO₃-supplied plants was inhibited at 200 M FeHEDTA while growth of N₂-fixing plants was inhibited at 100 M FeHEDTA. The numbers of nodules per plant increased between 3.3 and 10 M FeHEDTA; however, inhibition of nodule formation occurred at a concentration of 33 M or higher. Nodule weights per plant and N₂ fixation rates were depressed at 3.3 M as well as at 100 M FeHEDTA. The results suggest that alfalfa dependent on N₂ fixation is more sensitive to limited Fe availability than alfalfa supplied with NO₃.     

Large-scale expression of recombinant sialyltransferases and comparison of their kinetic properties with native enzymes

Values ofK _m were determined for three purified sialyltransferases and the corresponding recombinant enzymes. The enzymes were Gal1-4GlcNAc 2-6sialyltransferase and Gal1-3(4)GlcNAc 2-3sialyltransferase from rat liver; these enzymes are responsible for the attachment of sialic acid to N-linked oligosaccharide chains; and the Gal1-3GalNAc 2-3sialyltransferase from porcine submaxillary gland that is responsible for the attachment of sialic acid to O-linked glycoproteins and glycolipids. A procedure for the large scale expression of active sialyltransferases from recombinant baculovirus-infected insect cells is described. For the liver enzymes values ofK _m were determined using rat and human asialo₁ acid glycoprotein andN-acetyllactosamine as variable substrates; lacto-N-tetraose was also used with the Gal1-3(4)GlcNAc 2-3sialyltransferase. Antifreeze glycorprotein was used as the macromolecular acceptor for the porcine enzyme. Values forK _m were also determined using CMP-NeuAc as the variable substrate.Abbreviations NeuAc N-acetylneuraminic acid - Gal galactose - GlcNAc N-acetylglucosamine Enzymes: Gal1-4GlcNAc 2-6sialyltransferase, EC 2.4.99.1; Gal1-3(4)GlcNAc 2-3sialyltransferase, EC 2.4.99.5; Gal1-3GalNAc 2-3sialyltransferase, EC 2.4.99.4.     

The major histocompatibility complex of tassel-eared squirrels

The complexity and polymorphism of sequences related to the class I and class II genes of mammalian major histocompatibility complexes (MHCs) were investigated in the tassel-eared squirrel subspecies Sciurus aberti kaibabensis or Kaibab squirrel. Kaibab squirrels are geographically isolated on the Kaibab plateau north of the Grand Canyon in Arizona. Genomic DNA from 22 individuals was digested with Eco RI and Barn HI, electrophoresed, blotted, and hybridized with a panel of human class I and class II probes. Sequences homologous to DR, DR , DQ, and DQ probes were observed. A single, nonpolymorphic DR-related sequence and multiple, polymorphic DQ-related sequences were observed. Hybridization with DR and DQ probes revealed multiple, polymorphic sequences with such specificity that no bands were observed to hybridize with both probes. The level of polymorphism of sequences exceeded that observed with sequences. Further, three Eco RI bands apparently included at least parts of both and sequences. Hybridization of genomic blots with the HLA-B7 class I probe revealed a number of bands comparable in size range and number to other mammalian species. However, only a minor percentage of bands were observed to segregate. The inheritance of these five families of sequences appeared to be neither concordant nor random in the sample population. Based on prior conclusions in other species, these class I and class II sequences are presumed to map to the Kabib MHC, TLSA. Although DQ- and DQ -related sequences were concordantly inherited, segregating sequences in the other families could not be assigned to identifiable, segregating haplotypes. These observations suggest that the present-day TSLA haplotypes have been derived from a limited number of progenitor haplotypes through repeated, intra-TSLA recombination.     

Sugar nucleotides dissipate ATP-generated transmembrane pH gradient in Golgi vesicles from suspension-cell protoplasts ofChenopodium rubrum L.

A microsomal vesicle fraction (GV) markedly enriched by the Golgi marker enzyme latent inosine diphosphatase (IDPase) has been isolated from photoautotrophic suspension-cell protoplasts ofChenopodium rubrum L. Addition of ATP creates a substantial pH gradient across the GV membrane as measured by accumulation of acridine orange. The GV showed a density of 1.14 g·cm^-3 by equilibrium density centrifugation on sucrose gradients. Coincidence of acridine-orange accumulation and IDPase activity was confirmed on Percoll gradients. Formation of the pH gradient half-saturates at 0.3 mM MgATP, peaks at pH 7, and is competitively inhibited by ADP (k _i0.1 mM), but not by P_i; it is hardly inhibited by orthovanadate, quickly dissipated by monensink ₂=18 nM), nigericin (k _1/2=25 nM), and sluggishly by N-ethylmaleimide (k _1/235 M). Inhibition by KNO₃ (k _1/26.7 mM) is incomplete (60%). Uridine 5-diphosphate (UDP)-glucose, UDP-galactose, but not UDP-mannose and the pertinent sugars, dissipate the ATP-generated pH gradient (k _1/210–20 mM UDP-glucose; optimum pH at 7.8). This UDP-glucose activity is accompanied by release of P_i, but not of glucose or sucrose. UDP-glucoseinduced P_i release from the GV saturates (k _1/2=1 mM UDP-glucose; optimum pH at 7) and is completely inhibited by the anion-channel blocker 4,4-diisothiocyano-2,2-stilbene disulfonic acid (DIDS;k _1/2=140 M). The GV incorporates UDP-[U-¹⁴C]glucose into an acid-labile, alkaline-stable macromolecular compound; this process is like-wise inhibited by DIDS. We propose a model including, inter alia, a UDP-glucose/uridine-5-monophosphate translocator and a phosphate-permeable anion channel to operate in Golgi vesicles ofChenopodium rubrum.Abbreviations AO acridine orange - DIDS 4,4-diisothiocyano-2,2-stilbene disulfonic acid - FCCP carbonyl cyanidep-trifluoromethyoxyphenyl hydrazone - GV Golgi-vesicle-enriched microsomal fraction - IDPase mosine diphosphatase     

Energetic basis of cadmium toxicity in Staphylococcus aureus

In washed cells of cadmium-sensitive Staphylococcus aureus 17810S oxidizing glutamate, initial Cd²⁺⁺⁺ influx via the Mn²⁺ porter down membrane potential () was fast due to involvement of energy generated by two proton pumps—the respiratory chain and the ATP synthetase complex working in the hydrolytic direction. Such an unusual energy drain for rapid initial Cd²⁺ influx is suggested to be due to a series of toxic events elicited by Cd²⁺ accumulation down generated via the redox proton pump: (i) strong inhibition of glutamate oxidation accompanied by a decrease of electrochemical proton gradient ( _H ⁺) formation via the respiratory chain, (ii) automatic reversal of ATP synthetase from biosynthetic to hydrolytic mode, which was monitored by a decrease of _H ⁺-dependent ATP synthesis, (iii) acceleration of the initial Cd²⁺ influx down generated the reversed ATP synthetase, the alternative proton pump hydrolyzing endogenous ATP. The primary, cadmium-sensitive targets in strain 17810S seem to be dithiols located in the cytoplasmic glutamate oxidizing system, prior to the membrane-embedded NADH oxidation system. Inhibition by Cd²⁺ of _H ⁺-dependent ATP synthesis and of pH gradient (pH)-linked [¹⁴C]glutamate transport is a secondary effect due to cadmium-mediated inhibition of _H ⁺ generation at the cytoplasmic level. In washed cells of cadmium-resistant S. aureus 17810R oxidizing glutamate, Cd²⁺ accumulation was prevented due to activity of the plasmid-coded Cd²⁺ efflux system. Consequently, _H ⁺-producing and -requiring processes were not affected by Cd²⁺.     

Structure and orientation of Apo B-100 peptides into a lipid bilayer

Peptides corresponding to lipid binding domains of Apo B-100 were synthesized, purified, and incubated with dimyristoylphosphatidylcholine (DMPC) liposomes. The secondary structure of the apo B-100 peptide-lipid complexes was evaluated by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Those peptides belonging to the hydrophobic core domain of apo B-100 when associated with phospholipids were rich in sheet structure; a predominant helical conformation was shown to be associated with one peptide located in a surface region of apo B-100. IR dichroic spectra revealed, in the case of the core peptides, that the sheet component is the only oriented structure with respect to the phospholipid acyl chains. This orientation of the sheet was recently found in LDL particles after proteolytic digestion by trypsin (Goormaghtigh, E., Cabiaux, V., De Meutter, J., Rosseneu, M., and Ruysschaert, J. M., 1993,Biochemistry 32, 6104–6110). Altogether, the data suggest that sheet, present in a high proportion in the native apo B-100, is probably another protein structure in addition to the amphipathic helix which strongly interacts with the lipid outer layer surrounding the LDL particle.Abbreviations used Apo apolipoprotein - ATR attenuated total reflection - CD circular dichroism - DMPC dimyris-toylphosphatidylcholine - DMSO dimethylsulfoxide - FTIR Fourier transform infrared spectroscopy - HPLC high-performance liquid chromatography - LDL low density lipoprotein - TFA trifluoroacetic acid - C_x apoB-100 core peptide corresponding to the following residues: C₂, 2462–2482; C₃, 4208–4231; C₅, 4493–4513; and C₇, 4271–4288 - S₆ apoB-100 surface Peptide Corresponding to Residues 374–400     

The tryptic peptide composition of the beta chains of hemoglobins A and B of the domestic cat (Felis catus)

Summary The tryptic peptides from the ^A and ^B chains of cat hemoglobins A and B have been isolated and the amino acid compositions determined. Differences between the two chains were found in two peptides,T-1 (GlySer) andT-14 (AsnSer and LysArg). The GlySer and LysArg substitutions are placed at-1 and-144 respectively from earlier work, and the third substitution, AsnSer at-139 is suggested from this work. In addition, the presence of a blocked amino terminus in ^B has been confirmed. Tentative sequences constructed by homology with known-chain structures suggest the occurrence of substitutions at _{1 1} contacts in ^A and ^B that may be functionally significant. There are at least 18 differences in amino acid composition between cat ^A and dog-chains and 22 differences between cat ^A and normal adult human-chains.     

Coupling between H+ transport and anaerobic glycolysis in turtle urinary bladder: Effects of inhibitors of H+ ATPase

Summary The coupling between H⁺ transport (J _H) and anaerobic glycolysis was examinedin vitro in an anaerobic preparation of turtle urinary bladder.J _H was measured as the short-circuit current after Na⁺ transport was abolished with ouabain and by pH stat titration. The media were gassed with N₂ and 1% CO₂ (PO₂<0.5 mm Hg) and contained 10mm glucose. Under these conditions,J _H was not inhibited by 3mm serosal (S) cyanide or by 0.1mm mucosal (M) dinitrophenol. Control anerobic lactate production (J _lac) of 47 bladders was plotted as a function of simultaneously measuredJ _H. The slope ofJ _lac onJ _H was 0.58±0.12 with an intercept forJ _lac atJ _H=0 of 0.55 mol/hr. Values for J _lac/J _H were determined in groups of individual bladders whenJ _H was inhibited by an opposing pH gradient (0.55±0.16), by acetazolamide (0.58±0.19) and by dicyclohexylcarbodiimide, DCCD (0.58±0.14). The constancy of J _lac/J _H indicates a high degree of coupling betweenJ _H andJ _lac. Since the anaerobic metabolism of glucose produces one ATP for each lactate formed, the J _lac/J _H values can be used to estimate the stoichiometry of H⁺ translocation. The movement of slightly less than 2 H⁺ ions is coupled to the hydrolysis of one ATP. During anaerobiosis (absence of mitochondrial ATPase function) the acidification pump was not inhibited byM addition of oligomycin but was inhibited byM addition of DCCD and Dio-9, inhibitors of H⁺ flow in the proteolipid portion of H⁺-translocating ATPases. DCCD inhibited anaerobicJ _H without change in J _lac/J _H or basalJ _lac and, therefore, acted primarily on the H⁺ pump.S addition of vanadate also inhibitedJ _H, but the inhibition was associated with an increase inJ _lac. The site of this apparent uncoupling remains to be defined. The acidification pump of the luminal cell membrane of the turtle bladder has H⁺-ATPase characteristics that differ from mitochondrial ATPase in that H⁺ transport is oligomycin-resistant and vanadate-sensitive. As judged from the flows of H⁺ and lactate, the H⁺/ATP stoichiometry of the pump is about 2.     

Isolation of α and β Brain Tubulin Subunits after Alkaline Treatment of the Protein

We demonstrate here that brain purified tubulin can be dissociated into and subunits at pH > 10 and that the subunits can be separated by using the Triton X-114 phase separation system. After phase partition at pH > 10, tubulin but not tubulin behaves as a hydrophobic compound appearing in the detergent rich phase. After three extractions of the alkaline aqueous phase with Triton X-114, about 90% of the tubulin was recovered in the detergent rich phase. The hydrophobic behavior observed for tubulin after its dissociation at pH 11.5 was not due to an irreversible change of the protein, because when the detergent rich phase containing tubulin was diluted with a buffer solution at pH 7.3 and the solution allowed to partition again, -tubulin is recovered in the aqueous phase. The detergent in the aqueous phase of the and tubulin preparations can be removed up to 90% by 12 h dialysis. The and subunits of tubulin from kidney and liver behave, in this phase separation system, like those of brain tubulin.     

Design of superactive and selective integrin receptor antagonists containing the RGD sequence

Summary Integrins play a major role in cell-cell and cell-matrix interactions. The majority of the different types of integrins recognize the tripeptide sequence arginine-glycine-aspartic acid (RGD). To explore the spatial requirements of the pharmacophore for receptor selectivity and high activity, a new procedure, spatial screening, was used. The procedure is based on the experience that the conformation of small cyclic peptides is mainly determined by the chirality of the amino acids (and glycine or proline). For example, cyclic pentapeptides with one d and four l amino acids prefer a II'/ conformation. The sequence RGDFV was shifted around this spatial II'/ template by synthesis of five peptides in which one of the amino acids was used in d-configuration. It turned out that cyclo(-RGDfV-) is a selective inhibitor for the _v3 integrin, which is strongly expressed in cancer cells. Systematic variations with different turn mimetics, retro-inverso structures, modified peptide bonds and sugar amino acids are discussed.     

Enzymhistotopochemische Studien an inaktiven Salzdrüsen von Hausenten (Anas platyrhynchus)

Zusammenfassung In der sog. inaktiven Salzdrüse von Hausenten wurden die Glykosidasen -d-Glucuronidase, -d-Glucosaminidase, -Glucosidase und -d-Galaktosidase sowie die Hydrolasen unspezifische saure Phosphatase, unspezifische alkalische Phosphatase, Esterase, ATPase und Leucinaminopeptidase mit enzymhistochemischen Methoden untersucht. Die Drüsenzellen zeigen deutliche, wenn auch quantitativ unterschiedliche Esteraseaktivitäten. Besonders auffallend ist die hohe Aktivität der lysosomal lokalisierten sauren Phosphatase in den Epithelzellen der Zentralkanäle und Ausführungsgänge. Die Bedeutung der Befunde in bezug auf sekretorische und resorptive Leistungen der Salzdrüse wird diskutiert.

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Enzyme histochemical studies on the salt gland of ducks (Anas platyrhynchus)II. Cytochemical localization of some hydrolases

Summary Studying the site of hydrolytic enzymes in the salt gland of domestic ducks the glycosidases -d-glucuronidase, -d-glucosammidase, -glucosidase and -d-galactosidase as well as the hydrolases non-specific phosphatases, esterases, ATPase and leucinaminopeptidase have been investigated with histochemical techniques. The epithelia of the salt gland show distinct activities of non-specific esterases, that differ quantitatively. Furthermore we noticed a strong granular activity of non-specific acid phosphatase in the central canal and in the glandular duct system. The meaning of these findings in relation to secretion and absorption is discussed.

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Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft (Ku-210/2).     

Inheritance of resistance to potato viruses Y and A in progeny obtained from potato cultivars containing gene Ry:evidence for a new gene for extreme resistance to PVA

Extreme resistance in cultivated potato (Solanum tuberosum) to potato viruses Y and A (PVY and PVA) conditioned by the presence of Ry genes introduced from Solanum stoloniferum was described by Cockerham (1970). Cockerham detailed a number of genes which controlled a variety of reactions, including extreme resistance to both viruses (i.e. little or no visible reaction of plants and no viral replication following graft and manual inoculation) controlled by gene Ry _sto. In the present study, cvs Pirola and Barbara, which contain a Ry gene, were found to have extreme resistance to PVY isolates from the ordinary (PVY°), veinal necrosis (PVY^N) and potato tuber necrotic ringspot (PVY^NTN) subgroups, and PVA. The inheritance of this phenotype was examined in seedling progenies obtained by crossing Barbara and Pirola with susceptible cultivars. Segregation data for resistance to PVY and PVA in a progeny involving cv Pirola best fitted a genetical model of one gene controlling extreme resistance to both PVY and PVA, although the possibility that there are two genes, each controlling resistance to one virus but closely linked, cannot be excluded. Segregation data from progenies involving cv Barbara best fitted a genetical model in which there are two independent genes, one controlling extreme resistance to PVA and PVY and a second gene controlling extreme resistance to PVA but not to PVY. This previously unrecognised gene conferring extreme resistance to PVA only, should be given the notation Ra in keeping with nomenclature used for other resistance genes.     

Genetic organization of the E. coli chromosome around the structural gene for initiation factor IF3 (infC).

Summary A set of transducing phages carrying varying lengths of the E. coli chromosome around the structural gene for initiation factor IF3 (infC) was derived from p2 which is known to cary, besides infC, the structural genes for the subunit of phenylalanyl-tRNA synthetase (pheS), the subunit of phenylalanyl-tRNA synthetase (phetT) and the structural gene for threonyl-tRNA synthetase (thrS). The E. coli coding content of these derived phages was analysed by genetic complementation of a set of mutants and by SDS-polyacrylamide gel analysis of the proteins synthesized in UV irradiated cells infected with these phages. The segregation pattern of the different genes among these derived phages indicates that the order of the genes is pheT-pheS-P12-(infC, thrS) where infC is probably between P12 and thrS. P12 is the structural gene of a 12,000 molecular weight unidentified protein.Abbreviations PRS (EC 6.1.1.20) phenylalanyl-tRNA synthetase - TRS (EC 6.1.1.3) threonyl-tRNA synthetase - IF3 Initiation factor IF3 - SDS Sodium dodecyl sulfate - PP^R pyrophosphate resistant - PP^S pyrophosphate sensitive     

Biological reasons for the unsuitability of growth parameters and indices for comparing fish growth

Parameters k and L in the Von Bertalanffy equation and their derivatives =kL, = logk + 2logL; as well as slopes b_L/t of the regression L=at^b (t, years), relative increments (CI=[L₂–L₁]/L₁), specific growth rates (C_v=InL₂–InL₁), growth characteristics (Clh = CvxL₁) and growth constants (Clt=Cvx[t₂ + t₁]/2) were analyzed. A total of 121 bream Abramis brama stocks in the first 10 years of life were studied. At the same real growth rate (the average absolute linear annual increments, mm year^–1) the values of k, L, , , b_L/t, CI, Cv and Clt in different stocks vary within almost the whole range. The main reason is the natural process of growth self-regulation: the relation between the average body lengths in the first year (L₁) and the relative growth rates (slopes b_L/t) is negative (b_L/t = exp[0.1183–0.0053L₁], r=0.76). The above relation defines 4 principal types of the Ford-Walford lines. Thirty four percent of the stocks have rather steep slopes of the lines and even parallel the absolute slope of 45°, so the L values of these stocks have no biological significance. The authors recommend a simple and more precise, from a biological point of view, approach for comparing fish population growth rates.     

Effector mechanism of human monocyte-mediated cytotoxicity: role of a new tumor cytotoxic factor distinct from interleukin 1 and tumor necrosis factorα

Human blood monocytes activated to the tumoricidal state were previously found to release a factor(s) responsible for tumor cell killing. The activity of the tumor cytotoxic factor(s) (TCF) was determined by release assay of radioactivity from human A375 melanoma cells. On fractionation of the supernatant of activated monocytes by Ultrogel AcA34 and TSK-G3000SW gel chromatographies two major peaks of the material with TCF activity with MWs of 30,000 and 15,000, called TCF-I and TCF-11, respectively were obtained. TCF-II could be neutralized by polyclonal anti-IL-1 antiserum, but anti-IL-1 antiserum did not neutralize either factor. TCF-I was separated by ampholine column electrofocusing into three major fractions with TCF activity at pI 5, 6 and 6.8, named TCF-1, TCF-1 and TCF-1, respectively. The cytotoxic and IL-1 activities of TCF-1 were neutralized by anti-IL-1 serum, whereas those of TCF-1 and TCF-1 were not completely neutralized by anti-IL-1 or anti-IL-1 antiserum. On DEAE ion-exchange chromatography (TSK DEAE 5PW) TCF-I gave two peaks with TCF activity (TCF-I1 and TCF-I2). TCF-I1 was slightly neutralized by anti-TNF antibody, but TCF-I2 was not affected by antisera against IL-1 and IL-1, or anti-TNF antibody, thus ruling out the possibility that tumor necrosis factor (TNF) might be involved in tumor cell killing mediated by TCF-I2. These results indicate that human monocyte-mediated cytotoxicity against human A375 melanoma cells is mediated in part by a tumor cytotoxic factor (TCF; MW, 30,000; pI 6), differing from IL-1 and TNF.