Fungitoxicity of m-fluorophenylalanine-containing peptides towards Pythium ultimum

The tripeptide L-m-fluorophenylalanyl-L-alanyl-L-alanine was much more fungitoxic towards Pythium ultimum than the dipeptide L-m-fluorophenylalanyl-L-alanine or m-fluorophenylalanine. The fungitoxicity of the tripeptide was reduced by L-alanyl peptides and phenylalanine, but not by other amino acids. In contrast, the fungitoxicity of m-fluorophenylalanine was unaffected by peptides, and was antagonized by several amino acids. These results suggest the effective delivery of m-fluorophenylalanine into the cell by a tripeptide carrier.     

Genetic studies on gynandromorphism (sgm,gm) inCulex pipiens fatigans

Summary Individuals showing anterior-posterior gynandromorphism or somatic mosaicism of palpi respectively have been found in a laboratory strain ofCulex pipiens fatigans. The origin of the gynanders on the basis of binucleated eggs bearing anm factor and independently fertilized by male gemetes ofM andm genotype respectively has been suggested.This study was supported by the grant (No. 7/112/919/81 EMR-1), Council of Scientific and Industrial Research Govt., of India.     

Changes in the free amino acids of the haemolymph of diapause and non-diapause pupae of the cotton bollworm,Heliothis armigera Hbn. (Lepidoptera: Noctuidae)

Summary The concentration of free amino acids in the haemolymph of non-diapausing and diapausing pupae ofHeliothis armigera was investigated. 20 amino acids were detected in the haemolymph of the studied stages. Asparagine, glutamine, cystine, ornithine, histidine and valine were the predominant free amino acids at all stages. The diapause resulted in increased levels of most of the amino acids.     

Single amino acid substitutions insn-glycerol-3-phosphate dehydrogenase allozymes fromDrosophila virilis

Summary The amino acid sequence was compared among the three allelic variants (allozymes) ofsn-glycerol-3-phosphate dehydrogenase inD. virilis, which are detected by one-dimensional electrophoresis. The GPDH^f variant was different from the GPDH^m by only one substitution of 68-lysine for asparagine; GPDH^s differed from GPDH^m by substitution of 127-glycine for arginine. No electrophoretically silent substitutions were found in a total of 352 amino acid residues.     

Antimutagenic unusual amino acids from plants

Summary Five unusual amino acids were identified as antimutagens against spontaneous mutation ofSalmonella typhimurium TA100: L-azetidine-2-carboxylic acid (1) from Liliaceae plants, -(methylenecyclopropyl)glycine (2) fromLitchi chinensis seeds, and 2-amino-4-methylhex-5-ynoic acid (3), hypoglycin A (4), and (2S, 4R)-2-amino-4-hydroxyhept-6-ynoic acid (5) fromEuphoria longana seeds. The absolute stereochemistry of5 was determined by its chiral synthesis from L-allylglycine, proving that5 is the C-4 epimer of the amino acid previously isolated from dried longan seeds.This work was partly supported by a Grant-in-Aid form the Ministry of Education, Science, and Culture, Japan, No. 57740283 (to HK).     

Hydroxydihydroergosine,a new ergot alkaloid analogue from directed biosynthesis bySphacelia sorghi

Summary A new ergot alkaloid, 9-hydroxydihydroergosine, has been produced by axenic cultures ofSphacelia sorghi to which 4-hydroxy-proline was added when biomass accumulation was complete. Evidence for a lack of biosynthetic specificity for the first, second and third amino acid in cyclic tripeptide alkaloids has now been found amongst ergot fungi.Supported by the Science Research Council and Roche Products Ltd.     

High affinity recognition of a <Emphasis Type="Italic">Phytophthora</Emphasis> protein by <Emphasis Type="Italic">Arabidopsis</Emphasis> via an RGD motif

The RGD tripeptide sequence, a cell adhesion motif present in several extracellular matrix proteins of mammalians, is involved in numerous plant processes. In plant-pathogen interactions, the RGD motif is believed to reduce plant defence responses by disrupting adhesions between the cell wall and plasma membrane. Photoaffinity cross-linking of [¹²⁵I]-azido-RGD heptapeptide in the presence of purified plasma membrane vesicles of Arabidopsis thaliana led to label incorporation into a single protein with an apparent molecular mass of 80 kDa. Incorporation could be prevented by excess RGD peptides, but also by the IPI-O protein, an RGD-containing protein secreted by the oomycete plant pathogen Phytophthora infestans. Hydrophobic cluster analysis revealed that the RGD motif of IPI-O (positions 53–56) is readily accessible for interactions. Single amino acid mutations in the RGD motif in IPI-O (of Asp⁵⁶ into Glu or Ala) resulted in the loss of protection of the 80-kDa protein from labelling. Thus, the interaction between the two proteins is mediated through RGD recognition and the 80-kDa RGD-binding protein has the characteristics of a receptor for IPI-O. The IPI-O protein also disrupted cell wall-plasma membrane adhesions in plasmolysed A. thaliana cells, whereas IPI-O proteins mutated in the RGD motif (D56A and D56E) did not.Received 23 October 2003; received after revision 5 December 2003; accepted 12 December 2003     

Importance de la lysine et du tryptophane dans la nutrition deTenebrio molitor L.

Summary Experiments were undertaken in order to ascertain whether an insect,Tenebrio molitor, requires lysine and tryptophane for growing. Young larvæ were fed, from the day of hatching, on a diet containing a purified protein as sole source for amino acids and all the other nutrients required by this species.It was found that lysine and tryptophane are both essential for the growing ofTenebrio. The various protteins tested can be listed from point of view of their nutritive value according to their content of both amino acids. Further evidence for this relationship is presented by the fact that zein, a protein deficient in both lysine and tryptophane, is incapable to sustain growth unless it is supplemented with both amino acids. On the other hand, gliadin which is devoid of lysine but contains small amounts of tryptophane can be improved when lysine only is added.     

Stimulation of sporulation by ppApp in a conditionally asporogenous rifampin-resistant mutant ofBacillus subtilis

Summary Addition of ppApp to Sterlini-Mandelstam medium stimulates sporulation of a conditionally asporogenous rifampin-resistant mutant ofBacillus subtilis to the same extent as the effect of 4 amino acids. Mutant cells sporulating in the presence of amino acids also produce 2 phosphorylated nucleotides one of which comigrated with ppApp on PEI thin layer chromatogram.Acknowledgment. This work was supported in part by a grant from Research Corporation, New York, New York.     

Directed biosynthesis of analogues of ergot peptide alkaloids withClaviceps purpurea

Summary Analogues of peptide ergot alkaloids can be obtained by feeding a producing culture ofClaviceps purpurea with an analogue of one of the amino acids of the peptide chain of the alkaloid.     

Free amino acid composition of the intestinal contents,intestinal cells and hemolymph ofPhilosamia cynthia larvae

Summary Free amino acid composition of the intestinal contents, intestinal cells and hemolymph has been determined in larvae of the mothPhilosamia cynthia. From the hemolymph/lumen concentration ratio, an active transport could be inferred for neutral and basic amino acids. The values of cell/lumen and hemolymph/cell ratios suggested that the active step in the transport mechanism could be localized at the luminal pole of the enterocyte for neutral amino acids (except aromatic amino acids) and at the basolateral pole of the enterocyte for basic amino acids (except arginine).This work was supported by grants from Italian Consiglio Nazionale delle Ricerche and from Ministero della Pubblica Istruzione, Rome. The authors are indebted to Prof. V. Capraro for helpful discussion.     

Free amino acids of the haemolymph of the cotton leaf-worm,Spodoptera littoralis Boisduval full-grown larvae,infected with nuclear-polyhedrosis virus

Summary Free amino acids in the haemolymph ofSpodoptera littoralis full-grown larvae infected with a nuclearpolyhedrosis virus were compared with those in the haemolymph of normal insects. Amino acids were separated by 2-dimensional paper chromatography and quantified colorimetrically. Most of the amino acids in the haemolymph of diseased full-grown larvae decreased markedly in concentration but proline, lysine, aspartic acid and histidine occurred in greater concentration in the haemolymph of diseased full-grown larvae than in the haemolymph of healthy insects.     

Synthesis, structure and function of poly-α-amino acids – the simplest of protein models

During the 1950s, linear and multichain poly-α-amino acids were synthesized by polymerization of the corresponding N-carboxyamino acid anhydrides in solution in the presence of suitable catalysts. The resulting homo- and heteropolymers have since been widely employed as simple protein models. Under appropriate conditions, poly-α-amino acids, in the solid state and in solution, were found to acquire conformations of an α-helix and of β-parallel and antiparallel pleated sheets, or to exist as random coils. Their use in experimental and theoretical investigations of helix-coil transitions helped to shed new light on the mechanisms involved in protein denaturation. Conformational fluctuations of peptides in solution were analysed theoretically and studied experimentally by nonradiative energy-transfer techniques. Poly-α-amino acids played an important role in the deciphering of the genetic code. In addition, analysis of the antigenicity of poly-α-amino acids led to the elucidation of the factors determining the antigenicity of proteins and peptides. The synthetic procedures developed made possible the preparation of immobilized enzymes which were shown to be of considerable use as heterogeneous biocatalysts in the chemical and pharmaceutical industry. Interest in the biological and physicochemical characteristics of poly-α-amino acids was recently renewed because of the reported novel findings that some copolymers of amino acids are effective as drugs in multiple sclerosis, and that glutamine repeats and reiteration of other amino acids occur in inherited neurodegenerative diseases.     

Possible involvement of the phloem sealing system in the acceptance of a plant as host by an aphid

Possible reasons for the rejection of some lines ofTriticum monococcum (Tm44 and Tm46) by the aphidSitobion avenae were explored. In allT. monococcum lines studied, whether unfavourable (non-host/resistant plant) or favourable (host/susceptible plant), the concentrations of hydroxamic acids, a family of aphid-resistance factors in cereals, were significantly lower than the levels in the favourable host-plantTriticum aestivum cv. Therefore, hydroxamic acids did not account for the host/non-host patterns observed. Phloem sap was collected by stylectomy from young seedlings of favourable and unfavourable plants. In non-aphid-resistant genotypes, the success in stylectomy, the proportion of amputated stylets resulting in long (>1 min) exudations, the average duration of exudation, and the final volume of sap exuded, were higher than in the aphid-resistant genotypes. It is concluded that aphid interference with the phloem sealing system of the plant is a likely mechanism of rejection ofT. monococcum lines Tm44 and Tm46 as hosts byS. avenae.     

Nest cell lining of the solitary beeHylaeus bisinuatus (Hymenoptera: Colletidae)

The nest cell lining ofHylaeus bisinuatus (Hymenoptera: Colletidae) was shown by high-resolution solidstate [¹³C]NMR to be composed of lipid polymer and protein. The lipid polymer was shown by reduction and subsequent GC/MS analysis to be comprised of -hydroxy fatty acids (C₂₀, C₂₂, C₂₄ and C₂₆) and fatty alcohols (C₁₆ to C₃₀). The protein portion of the lining had a silk-like amino acid composition.     

Genetisch bedingte Tumoren und der Gehalt an freien Aminosäuren beiNicotiana

Summary The amphidiploid hybrid ofNicotiana glauca ×N. langsdorffi, producing tumors spontaneously, contains essentially more of the following free amino acids than the inital species: cystine, histamine, oxyproline, alanine, kynurenine, tryptophane, and a non-identified ninhydrine positive substance. It is supposed that the abnormally high content of free amino acids is connected with the spontaneous formation of tumors.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Amino acid requirements of the bugDysdercus similis freeman (hemiptera: Heteroptera)

Summary The amino acid requirements for moulting, growth and development ofDysdercus similis have been investigated. The insects could not moult and reach maturity when given 10 essential amino acids only. However, if these were supplemented either with glutamic acid, glycine or aspartic acid growth and moulting was found to be normal.Dysdercus has an unusual synthetic mechanism for converting tyrosine into phenylalanine.The author is grateful to Prof.R. S. Saini for his guidance, critical discussions and encouragement.     

Occurrence of biopterin in the wings ofMorpho butterflies

A blue fluorescent compound was isolated fromMorpho butterfly wings. Based on thin layer chromatographic, UV and CD-spectrophotometric and HPLC analyses, the blue fluorescent compound was identified as L-erythro biopterin. Biopterin is a major component of blue fluorescent pteridines in bothM. sulkowskyi andM. adonis. Pterin and isoxanthopterin can also be detected as minor components in these species. This paper is the first to report the presence of biopterin in butterfly wings.     

Gesteigerte Saugfrequenz vonDactynotus jaceae L. (Homoptera,Aphididae) bei Erhöhung des Aminosäurengehaltes in der Wirtspflanze

Summary In isolated shoots ofCentaurea jacea, placed in a solution of 0.5% glutamic acid for 15 h, the concentration of free amino acids in the stems is more than doubled. Compared with the controls, these shoots with an increased amino acid concentration are preferred by aphids in the preference-test.     

Inhibitory tripeptide,Lys-Phe-Tyr,as a fragment of physalaemin

Summary Several peptides were separated from-chymotrypsin-treated physalaemin by high voltage paper electrophoresis, and inhibition of the excitability of a molluscan giant neurone (tonically autoactive neurone) by the tripeptide, Lys-Phe-Tyr, was demonstrated.We thank Dr Sadaaki Iwanaga of Osaka University and Dr Atsuo Inoue of Daiichi Pharmaceutical CO for their helpful advice and the donation of the tripeptide (Lys-Phe-Tyr).