BlaB,a protein involved in the regulation of <Emphasis Type="Italic">Streptomyces cacaoi</Emphasis> β-lactamases,is a penicillin-binding protein

Streptomyces cacaoi -lactamase genes are controlled by two regulators named blaA and blaB. Whereas BlaA has been identified as a LysR-type activator, the function of BlaB is still unknown. Its primary structure is similar to that of the serine penicillin-recognizing enzymes (PREs). Indeed, the SXXK and KTG motifs are perfectly conserved in BlaB, whereas the common SXN element found in PREs is replaced by a SDG motif. Site-directed mutations were introduced in these motifs and they all disturb -lactamase regulation. A water-soluble form of BlaB was also overexpressed in the Streptomyces lividans TK24 cytoplasm and purified. To elucidate the activity of BlaB, several compounds recognized by PREs were tested. BlaB could be acylated by some of them, and it can therefore be considered as a penicillin-binding protein. BlaB is devoid of -lactamase, D-aminopeptidase, DD-carboxypeptidase or thiolesterase activity.Received 13 January 2003; received after revision 9 April 2003; accepted 11 April 2003     

Differential expression and dosage compensation of theα-amylase gene inDrosphila miranda

Summary The-amylase gene ofDrosophila miranda is located on the X²-and on the neo-Y-chromosome, both developing sex chromosomes. Crosses between strains carrying different electrophoretically distinguishable alleles of the-amylase gene were performed. Females of the F₁ offspring showed the expected heterozygosity, while the males proved to be hemizygous for this locus. Only the gene on the X²-chromosome is expressed, whereas the corresponding gene on the neo-Y-chromosome is not. Estimates of the-amylase activity in crude homogenates of male and female flies suggest strongly that the-amylase gene is dosage compensated inD. miranda. In contrast to this situation, in all otherDrosophila species the-amylase allele is autosomal and hence not dosage compensated.Acknowledgments. We would like to thank Betty C. Moore, for the kind supply ofD. miranda strains. For the help and advice in the electrophoretic separation of the-amylase variants we are indebted to Dr W. Pinsker. This work was supported by a grant from the Fonds zur Förderung der wissenschaftlichen Forschung, P5413 (Austria).     

Adrenal corticosteroidogenesis after removal of ventral prostate gland

Summary Removal of the ventral prostate gland in adult male rats causes an increase in adrenal weight, and stimulation of adrenal ⁵-3-hydroxysteroid dehydrogenase activity along with elevation of serum levels of corticosterone and prolactin.     

γ-Glutamyl-transpeptidase in lymphatic tissues ofMastomys natalensis during an infection withAcanthocheilonema viteae

Summary DuringAcanthocheilonema viteae infection, the specific activity of -glutamyltranspeptidase (-GT) increased in peritoneal exudate cells and bone marrow and decreased in lymphnodes ofMastomys natalensis throughout the course of infection. However, though there was an increase in specific activity of -GT in thymus and spleen during the prepatent phase ofA. viteae infection, the level either returned to normal or decreased during the latent phase of infection. A close correlation was observed between the host's immune status duringA. viteae infection and the level of -GT in lymphoid tissues.Communication No. 4535 from Central Drug Research Institute, Lucknow.     

Tissue-specific induction of intestinal glutathione S-transferases by αβ-unsaturated carbonyl compounds

Summary Glutathione S-transferase activity in rat intestinal mucosa was increased by the injection of -unsaturated carbonyl compounds such as phorone and diethylmaleate, but that in the liver and kidney was not. Since the administration of cycloheximide completely blocked the increase of the enzyme activity by phorone, the increase of the activity may be due to de novo synthesis rather than enzyme activation.     

Kelletinin I and kelletinin A from the marine molluscBuccinulum corneum are inhibitors of eukaryotic DNA polymeraseα

Summary The inhibitory effect of esters of p-hydroxybenzoic acid (kelletinins I and A), extracted from the marine gastropodBuccinulum corneum, have been tested on eukaryotic and prokaryotic enzymes of DNA metabolism such as DNA polymerases and , DNA polymerase I, Exo III, pancreatic DNAse I, micrococcal DNAse andE. coli RNA polymerase. Kelletinin I and kelletinin A inhibit preferentially DNA polymerase. The inhibitory effect of kelletinin I involves the hydroxyl group of p-hydroxybenzoic acid.     

Characterization of 17β-estradiol 3-(β-D-glucopyranoside) and 17-(α-D-glucopyranoside) as the metabolites of 17β-estradiol in the cultured ovaries of the silkworm,Bombyx mori

Summary The structures of the metabolites formed upon incubation of 17-estradiol with the ovaries of silkworm,Bombyx mori, have been determined as 17-estradiol 3-(-D-glucopyranoside) (1) and 17-(-D-glucopyranoside) (2) by spectroscopic means.     

(Z,E)-α-farnesene,main constitutent of the hypertrophied Dufour's gland of the major workers ofPheidole pallidula (Formicidae)

Summary In the European dimorphic ant,Pheidole pallidula, the Dufour's gland of the major workers is hypertrophied and secretes nearly pure (Z, E)--farnesene. This compound is also present in the Dufour's gland of the minor workers but constitutes only around 10% of the volatiles. Chemical polymorphism inP. pallidula is different from that already reported for species ofPheidole from the New World.Aspirante au Fonds National de la Recherche Scientifique.Maître de recherches du Fonds National de la Recherche Scientifique.     

A new indolic antiauxin, α-(5,7-dichloroindole-3-)isobutyric acid: its chemical synthesis and biological activity

Summary A new potent antiauxin, -(5,7-dichloroindole-3-)isobutyric acid has been synthesized and shown to inhibit auxin-mediated elongation ofAvena coleoptiles and to stimulate root growth of rice seedlings. Its activity is stronger than -(p-chlorophenoxy)isobutyric acid and is comparable to that of 2,3,5-triiodobenzoic acid, which are typical antiauxins.     

Hydra vulgaris ω10-lipoxygenase is used in vivo to synthesize new α-linolenic acid metabolites

Previous studies conducted in cytosolic extracts of the freshwater hydrozoanHydra vulgaris led to the finding of an abundant 11(R)-lipoxygenase catalyzing the peroxidation of polyunsaturated fatty acid (PUFAs) on the tenth carbon atom from the aliphatic end (10 peroxidation). Here we describe experiments aimed at identifying the actual metabolites generated in vivo by such enzymic activity. Homogenates ofH. vulgaris polyps were analyzed by HPLC. This showed the presence of three major components chromatographically identical to three metabolites obtained when incubating the homogenates with exogenous -linolenic acid (-LA). The presence, in extracts of polyps prelabelled with [¹⁴C]--linolenic acid, of radioactive metabolites displaying the same chromatographic properties, substantiated the hypothesis that the natural products isolated in vivo are derived from -LA. Gas chromatographic analyses revealed that this was the most abundant PUFA in both free and phosphoglyceride-bound fatty acid pools. [¹H]-NMR analysis of the endogenous substances, carried out in comparison with products obtained from exogenously incubated -LA, indicated that their structures were those of 9-hydroxy-, 9-hydroperoxy- and 9-keto-octadeca-10E-12Z-15Z-trienoic acids (9--HOTrE,-HPOTrE and-KOTrE).Hydra homogenates transformed 9--HPOTrE partly into 9--HOTrE and partly into 9--KOTrE. Chiral phase HPLC conducted on 9--HOTrE established that this metabolite was composed mostly of theR anantiomer. These observations, and the finding that the presence of exogenous arachidonic acid in incubated homogenates significantly reduces the production of -LA metabolites, provide strong evidence that these compounds are produced by an enzymic activity identical to the previously-describedH. vulgaris (R)-10-lipoxygenase. Further experiments suggested that -LA, acting as the native substrate for this enzyme, is mainly esterified on the 2 position ofHydra phosphoglycerides, and that the production of the -LA metabolites described here for the first time from natural sources, can be potentially enhanced in vivo by stimuli activating phospholipase A₂.     

Oviposition stimulants of aCitrus-feeding swallowtail butterfly,Papilio xuthus L

Summary A methanolic extract ofCitrus unshiu induces oviposition by females of aCitrus-feeding swallowtail butterfly,Papilio xuthus L. The chemical factors responsible for stimulating oviposition were isolated and characterized as 5-hydroxy-N-methyltryptamine, adenosine, vicenin-2, narirutin, hesperidin and rutin. An artificial blend of these six components elicited significant oviposition behavior, apparently identical to that induced by contact with intactCitrus leaves.     

Hymenin,a novel α-adrenoceptor blocking agent from the Okinawan marine spongeHymeniacidon sp.

Summary A novel bromine-containing alkaloid, hymenin, has been isolated from the Okinawan marine spongeHymeniacidon sp. as a potent -adrenoceptor blocking agent and its structure determined to be1 on the basis of the spectral data.     

Selective protection of cells against X-irradiation. Isoproterenol protects only those cells that possesβ-adrenoreceptors

Summary In mixed culture of Chinese hamster fibroblatst, clone 431, and transformed murine L fibroblasts, clone B-82, isoproterenol was found to protect only 431 cells against ionizing radiation. It was shown that 431 cells, in contrast to B-82 cells, possess-adrenoreceptors, and the radioprotective effect of isoproterenol can be realized only if this agent interacts with-adrenoreceptors coupled with the cAMP system. Since malignization often causes the disappearance of-adrenergic and other hormone receptors, the combined culturing and irradiation of the cells studied can be regarded as a model of the growth of malignant cells (B-82) among normal tissue cells (431 cells) under conditions of radiation therapy. A possibility of selective protection against radiation damage of normal tissue cells, with retention of the former radiosensitivity of tumor cells, is discussed.     

Horizontal gene transfer from Eukarya to Bacteria and domain shuffling: the α-amylase model

-Amylases are present in all kingdoms of the living world. Despite strong conservation of the tertiary structure, only a few amino acids are conserved in interkingdom comparisons. Animal -amylases are characterized by several typical motifs and biochemical properties. A few cases of such -amylases have been previously reported in some eubacterial species. We screened the bacterial genomes available in the sequence databases for new occurrences of animal-like -amylases. Three novel cases were found, which belong to unrelated bacterial phyla: Chloroflexus aurantiacus, Microbulbifer degradans, and Thermobifida fusca. All the animal-like -amylases in Bacteria probably result from repeated horizontal gene transfer from animals. The M. degradans genome also contains bacterial-type and plant-type -amylases in addition to the animal-type one. Thus, this species exhibits -amylases of animal, plant, and bacterial origins. Moreover, the similarities in the extra C-terminal domains (different from both the -amylase domain C and the starch-binding domain), when present, also suggest interkingdom as well as intragenomic shuffling.Received 17 October 2003; accepted 6 November 2003     

Anti-bovineβ-lactoglobulin antibodies react with a human lactoferrin fragment and bovineβ-lactoglobulin present in human milk

Human milk samples react against anti-bovine-lactoglobulin rabbit antibodies, as measured by a competitive radioimmunoassay. Immunoreactivity was positive even in milk from mothers consuming a diet free of cow's milk. An increase with a diet rich in cow's milk proteins was detected by immunoelectrophoresis. The human milk fraction cross-reacting with anti-bovine-lactoglobulin antibodies corresponds to the 20 kDa fragment from the N-terminal end of human lactoferrin. Three regions of this fragment exhibit sequence homology with a sequence contained in cow's-lactoglobulin (between residues 124 and 141).     

Muscle LIM protein promotes expression of the acetylcholine receptor <Emphasis Type="Italic">γ</Emphasis>-subunit gene cooperatively with the myogenin-E12 complex

Muscle LIM protein (MLP, also referred to as CRP3) is a muscle-specific LIM-only protein, which consists of two LIM motifs. MLP functions as a positive regulator during myogenesis. Here we report that MLP serves as a cofactor regulating the expression of the nicotinic acetylcholine receptor (AChR) -subunit gene in skeletal muscle cells. We found that MLP promoted the expression of the AChR -subunit gene in C2C12 myotubes, but not in C2C12 myoblasts or NIH3T3 fibroblasts. Furthermore, we showed that MLP interacted with myogenin in vivo and enhanced the binding ability of the myogenin-E12 heterodimer to the E boxes in the AChR -subunit gene promoter. Together, these results suggest that MLP promotes the specific expression of the AChR -subunit gene cooperatively with the myogenin-E12 complex during myogenesis.Received 17 May 2004; received after revision 22 July 2004; accepted 26 July 2004     

The role of zinc in regulating tabtoxin production

Summary The phytotoxin, tabtoxinine--lactam, is produced by severalPseudomonas syringae pathovars if adequate Zn is available, otherwise its biologically inactive form, tabtoxin, is produced. The Zn is required for the action of a peptidase which cleaves tabtoxin, releasing the toxic -lactam.This research was supported in part by U.S.D.A. Competitive Research Grant No. 83-CRCR-1-1201.     

Sclerotization of mosquito cuticle

Summary The mode of sclerotization ofAedes aegypti pupal and adult cuticle was examined by employing biochemical and radioactive techniques. During larval-pupal metamorphosis, tyrosine is converted to tanning precursors and is incorporated into aryl-amino adducts and -crosslinks. The major hydrolysis product of -crosslinks in pupal cases is identified to be arterenone. Examination of tanning modes in five different mosquito species shows that the ratio of quinone to -sclerotization not only differs within the life stages of the insects, but also differs between species.Study supported by N.I.H. Grant ROI-AI-14753.     

A simple method for in vivo testing of glandular enzymatic activity on potential precursors of larval defensive compounds inPhratora species (Coleoptera: Chrysomelinae)

The presence of glandular -glucosidase and oxidase-specific activities, and the possible role of phenolglucosides and related compounds as precursors for larval defensive compounds, were directly demonstrated by introducing salicin, saligenin and helicin into the defensive glands ofPhratora species.Ph. tibialis andPh. laticollis that normally secrete endogenously-produced iridoid monoterpenes and do not use phenolglucosides from their food sources as precursors, were able to produce salicyladehyde from helicin when the latter was introduced into the defensive glands.     

Chromosomal location of α-amylase structural genes in rye (Secale cereale L.)

Summary Rye (Secale cereale L.) -amylase isozymes are controlled by at least four loci located on the 5R (three) and 7R (one) chromosomes. In the case of Imperial and King II cultivars, two of the three 5R chromosome loci could be specifically located on the 5Rl chromosome arm; the other one was located on the 5RS. The locus of 7R chromosome was located on the 7RL chromosome arm of Imperial rye.