L'acide borique,inhibiteur de la copulation gamétique chezAllomyces

Summary Addition of a tiny crystal of boric acid to a drop of buffered water containing male and female gametes ofEuallomyces javanicus completely inhibits copulation in this water mold.Pure gametophytic growth can thus be secured by addition of 1/15,000 boric acid to the starch-yeast extract medium.

---

---

Communication annoncée mais non présentée au VIII^e Congrès international de Botanique, Paris 1954.     

Aberrant,canavanyl protein formation and the ability to tolerate or utilize L-canavanine

Summary L-Canavanine, 2-amino-4-(guanidinooxy)butyric acid, and L-arginine incorporation into de novo synthesized proteins was compared in six organisms. Utilizing L-[guanidinooxy¹⁴C]canavanine and L-[guanidino¹⁴C]arginine at substrate saturation, the canavanine to arginine incorporation ratio was determined in de, novo synthesized proteins.Caryedes brasiliensis andSternechus tuberculatus, canavanine utilizing insects;Canavalia ensiformis, a canavanine storing plant; and to a lesser extentHeliothis virescens, a canavanine resistant insect, failed to accumulate significant canavanyl proteins. By contrast,Manduca sexta, a canavanine-sensitive insect, andGlycine max, a canavanine free plant, readily incorporated canavanine into newly synthesized proteins. This study supports the contention that the incorporation of canavanine into proteins in place of arginine contributes significantly to canavanine's antimetabolic properties.     

Regulatory steps in sex pheromone biosynthesis inMamestra brassicae L. (Lepidoptera: Noctuidae)

Summary The de novo biosynthesis of (Z)-11-hexadecenyl acetate, the most abundant pheromone component inM. brassicae, starting from acetate via palmitic acid, requires the presence of a pheromone-biosynthesis-activating neurohormone. Moreover, the conversion of palmitic acid to (Z)-11-hexadecenyl acetate is strongly dependent on the presence of the neurohormone. However, no significant dependence was found for the conversion of (Z)-11-hexadecenoic acid to (Z)-11-hexadecenyl acetate. This indicates that the neurohormonal control of pheromone biosynthesis inM. brassicae occurs at the level of palmitic acid.     

Isolation of indole-3-acetic acid methyl ester,a metabolite of indole-3-acetic acid fromPseudomonas amygdali

From the culture filtrates ofPseudomonas amygdali the methyl ester of indole-3-acetic acid (IAA), a product of indole-3-acetic acid metabolism which has the same auxin activity as the free acid, has been isolated. This is the first report of its occurrence as a microbial metabolite.     

Primitive actimoterigian fishes can synthesize ascorbic acid

Amphibians and reptiles evolved with the capacity to synthesize ascorbic acid. Some higher vertebrates, like bats, guinea pigs, primates, and humans have lost the microsomal enzyme gulonolactone oxidase, and in cases of ascorbic acid deficiency suffer from symptoms of scurvy. The question of whether the capacity to synthesize ascorbate is also present in lower vertebrates could throw light on the evolution of this pathway. In order to find out whether ascorbic acid synthesis took place in two primitive Actinopterigian fish, the paddlefish (Polydon spathula) and the white sturgeon (Acipenser transmontanus) were fed with a scorbutogenic diet or diet(s) supplemented with a graded level of ascorbic acid. We found no growth depression nor external symptoms of scurvy, which would be pronounced in modern bony fishes (Teleostei) under similar conditions. The tissue level of ascorbate in both these primitive species indicated that vitamin C in intestine and liver is not depleted when fed a scorbutogenic diet. Gulonolactone oxidase activity was found in the kineys of the Actinopterigian fishes. Thus, I question the accepted evolutionary pathway for ascorbic acid biosynthesis in lower vertebrates and suggest that the modern bony fishes,Teleostei, lost their ability to express the gulonolactone oxidase genes after they had separated during the Silurian from their common ancestor with the coelacanths (Latimeria) and Dipnoi.     

Gonyauline: A novel endogenous substance shortening the period of the circadian clock of a unicellular alga

Summary The circadian clock in the unicellular algaGonyaulax polyedra is accelerated by a substance in extracts from the cells themselves. The extracts have been fractionated using the circadian rhythm of bioluminescence as bioassay. The active substance, termed gonyauline, has been isolated and characterized as a novel low molecular weight cyclopropanecarboxylic acid (S-methyl-cis-2-(methylthio) cyclopropanecarboxylic acid). Synthetic gonyauline has a similar shortening effect on the period of the circadian clock.     

Isolation and characterization of hemagglutinins from the spongeDysidea herbacea

Summary The spongeDysidea herbacea (Keller) was found to possess hemagglutinins. The major component, DHA-I, is a protein with a mol.wt of 26,000, which dissociates into subunits of equal size (14,000). It contains large amounts of glutamic acid and aspartic acid residues, but no half-cystine, methionine or histidine residues. DHA-I reacted with rabbit and human AB0 erythrocytes. D-galactose and lactose were effective inhibitors of DHA-I. The sponge also contained a minor component(s) which reacted preferentially with rabbit erythrocytes but not with human AB0 erythrocytes.Acknowledgment. We thank Dr. M. Yamazaki, Faculty of Pharmaceutical Sciences, Teikyo University, for testing mitogenic activity ofDysidea agglutinins. This study was partly supported by a grant-in-aid for Overseas Scientific Survey from the Ministry of Education, Science and Culture, Japan.     

Insect tissues,not microorganisms,produce linoleic acid in the house cricket and the American cockroach

Summary Biosynthesis of linoleic acid, 182(n–6), was unambiguously demonstrated to occur in the cockroach,Periplaneta americana, and the cricket,Acheta domesticus. Axenic tissue from both of these insect species was demonstrated by radio-gas-liquid chromatography (radio-GLC) and radio-high-performance liquid chromatography (radio-HPLC) to incorporate [1-¹⁴C]acetate and [1-¹⁴C]oleate into this essential fatty acid.This work was supported by the National Science Foundation under grant DCB-8914417. We would like to thank Coby Schal for his generous gift of American cockroaches and Tania Kellermeyer for her excellent technical assistance.     

A possible metabolic role foro-diphenoloxidase inMycobacterium leprae

Summary Among mycobacteria,Mycobacterium leprae is unique in its ability to oxidize a variety of diphenols to quinones in vitro. What physiologic roleo-diphenoloxidase has in the organism remained unknown. Reducing substrates like NADPH, NADH and ascorbic acid reacted with the quinone formed from dopa (3,4-dihydroxyphenylalanine); the substrates were oxidized and the quinone was reduced back to diphenol in the process. Since the quinone undergoes reversible oxidation-reduction, diphenoloxidase might serve as an alternative respiratory mechanism inM. leprae for the utilization of other substrates, as has been reported in plants.     

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).     

Furan fatty acid steryl esters from the marine spongeDictyonella incisa which show inflammatory activity

Summary Three new furan fatty acids, (9Z, 19Z)-3, 6-epoxyhexacosa-3,5,19-tetraenoic acid (1a), (8Z, 11Z, 14Z, 17Z)-3, 6-epoxyeicosa-3,5,8,11,14,17-hexaenoic acid (2a), and (8Z, 11Z, 14Z, 17E)-3, 6-epoxyeicosa-3,5,8,11,14,17-hexaenoic acid (3a), and a new polyunsaturated fatty acid (5Z, 8Z, 11Z, 14Z, 17E)-eicosa-5,8,11,14,17-pentaenoic acid (6a), present in the spongeDictyonella incisa as the respective steryl esters, have been isolated as methyl esters and their structures have been determined by spectral and chemical analysis. The furan fatty acid esters have shown a high inflammatory activity, which suggests their potential role as feeding deterrents.     

Partial sequence of the gene for a serine protease from a halophilic archaeumhaloferax mediterranei R4, and nucleotide sequences of 16S rRNA encoding genes from several halophilic archaea

A part of the gene coding for a halophilic serine protease from a halophilic archaeumHaloferax mediterranei R4 was amplified by PCR and its 672 nucleotide sequence was determined. Tentative translation to the amino acid sequence suggested that the enzyme was quite similar to halolysin produced by another halophilic archaeum strain 172P1. Nucleotide sequences of 16S rRNA encoding genes from 9 halophilic archaea were determined. Alignment of 19 sequences known so far showed that there are more than 20 positions carrying bases or deletions specific for each halobacterial genus:Halobacterium, Haloarcula, Haloferax, andHalococcus.     

The histones ofDictyostelium discoideum

Summary The histones of the cellular slime mouldDictyostelium discoideum have been separated by electrophoresis using both acid urea and sodium dodecyl sulphate systems, and the gel pattern compared with that of histones fromPhysarum polycephalum and calf thymus.Dictyostelium is found to possess a full complement of H1, H2A, H2B, H3 and H4.     

Antibacterial effect of 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine onStaphylococcus aureus

The mechanism by which a new naphthoquinone derivative, the 2-hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine (INQI-E) has antibacterial effect againstStaphylococcus aureus was studied. The interaction of INQI-E with the bacteria was followed by absorption spectroscopy at 323 and 490 nm. The absorption band of INQI-E at 490 nm undergoes a hypochromic shift with a decrease of intensity. This effect was found to be reversible by oxygenation during the first hours of incubation. The participation of an oxidation-reduction process related to the respiratory chain was demonstrated by oxygen consumption. An increase in O₂ uptake and inhibition ofS. aureus growth was observed. Experiments with three inhibitors of the respiratory chain demonstrated that the pathway induced by INQI-E was antimycin-resistant and KCN- and salicylhydroxamic acid (SHAM)-sensitive, which suggests that INQI-E is capable of diverting the normal electron flow to an alternate superoxide-producing route. On the other hand, experiments with Tiron, a specific scavenger of superoxide, hindered the effect of INQI-E againstS. aureus, indicating that the inhibitory growth effect of this quinone-imine is mainly due to the production of the cytotoxic superoxide radical.     

Hepatic acid hydrolases of albino rats,Mastomys natalensis and albino mice duringPlasmodium berghei infection

Summary Changes in liver acid hydrolase activities during the infection of albino rats,Mastomys or mice withPlasmodium berghei are described. B-Glucosidase, B-galactosidase and N-acetyl-B-D-glucosaminidase exhibited widely different responses with acid phosphatase and cathepsin-B the least responsive and are likely to be causally related to immunity of animals.     

Inhibition of lipid peroxidation by diterpenoid fromPodocarpus nagi

A diterpenoid, totarol (1), fromPodocarpus nagi was evaluated as an antioxidant. This diterpenoid inhibited autoxidation of linoleic acid. Mitochondrial and microsomal lipid peroxidation induced by Fe(III)-ADP/NADH or Fe(III)-ADP/NADPH were also inhibited. Nagilactone E (2), a norditerpene lactone isolated from the same source, had no antioxidative activity. Furthermore, totarol protected red cells against oxidative hemolysis. This diterpene was shown to be effective in protecting biological systems against oxidative stresses.     

Interaction ofRhizobium loti strain and host on the biosynthesis of unusual amino acids in leguminous plants

Summary The effect of differentRhizobium loti strains on the biosynthesis of 2,3-diamino-butanoic acid and 2,4-diamino-3-methyl-butanoic acid in root nodules ofLotus tenuis, Anthyllis vulneraria andLupinus densiflorus has been investigated. Results suggest that biosynthesis isRhizobium strain dependent, that the bacteroid is the site of synthesis of the compounds and that their biosynthesis is confined to the symbiosis.     

Molecular characterization and expression of the antimicrobial peptide defensin from the housefly (Musca domestica)

A 430-bp cDNA encoding the insect antimicrobial peptide defensin was cloned from the housefly, and designated Musca domestica defensin (Mdde). The open reading frame of the cDNA encoded a 92-amino acid peptide with an N-terminal signal sequence followed by a propeptide that is processed by cleavage to a 40-amino acid mature peptide. Northern analysis and in situ hybridization identified the corresponding mRNA in the fat body of bacterially challenged houseflies and in the epidermis of the body wall of naive and challenged houseflies. The Gram-negative bacterium (Escherichia coli) is a strong inducer of the gene. By RT-PCR, Mdde mRNA was also detected in naive and challenged insects. These findings suggest that the defensin gene is constitutively expressed in the epidermis of the housefly body wall. The predicted mature form of Mdde was expressed as a recombinant peptide in E. coli and Pichia pastoris. The recombinant Mdde expressed in Pichia was active against Gram-positive and some Gram-negative bacteria. Received 20 June 2006; received after revision 3 October 2006; accepted 30 October 2006