Chrysoperla carnea predation on Heliothis virescens larvae parasitized by Microplitis croceipes

Predation by third instar larvae of Chrysoperla (=Chrysopa) carnea (Stephens) (Chrysopidae) did not alter the ratio of unparasitized Heliothis virescens (F.) (Noctuidae) larvae to H. virescens larvae parasitized by Microplitis croceipes (Cresson) (Braconidae) when these second instar larvae were exposed together to the predator on cotton (Gossypium hirsutum L., Malvaceae) in field cages. This indicates that C. carnea larvae did not prefer either parasitized or unparasitized larvae.

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Prédation par Chrysopa carnea des chenilles d'Heliothis virescens parasitées par Microplitis croceipes

Résumé Les prédations de chenilles d'Heliothis virescens, parasitées ou saines, élevées sur coton (Gossypium hirsutum L.), de la variété Stoneville 213, ont été comparées, dans des cages de 10 m² chacune placées dans la nature. Des chenilles du second stade ont été placées sur des pieds de coton dans 10 cages, à raison de 160 chenilles préalablement exposées à M. croceipes pendant leur premier stade et 40 chenilles saines par cage. Des larves du troisième stade de Chrysopa carnea ont été ajoutées dans 6 cages, à raison de 500/cage, et 4 cages ont servi de témoins pour évaluer les autres causes de mortalité. L'expérience a été répétée 2 fois. Les chenilles d'H. virescens ont été retirées au bout d'un jour dans une expérience et au bout de 2 jours dans l'autre. C. carnea n'a fait aucun choix entre chenilles parasitées ou non; la fréquence moyenne de chenilles parasitées n'a pas présenté de différence significative entre les cages avec ou sans C. carnea. Qui qu'il en soit, C. carnea a réduit significativement la survie des chenilles d'H. virescens parasitées ou non.

     

Isolation and characterization of the TRM1 locus, a gene essential for the N2,N2-dimethylguanosine modification of both mitochondrial and cytoplasmic tRNA in Saccharomyces cerevisiae

The trm1 mutation of Saccharomyces cerevisiae is a single nuclear mutation that affects a specific base modification of both cytoplasmic and mitochondrial tRNA. Transfer RNA isolated from trm1 cells lacks the modified base N2,N2-dimethylguanosine, and extracts from these cells do not have detectable N2,N2-dimethylguanosine-specific tRNA methyltransferase activity. As part of our efforts to determine how this mutation affects enzyme activities in two different cellular compartments we have isolated the TRM1 locus by genetic complementation. The TRM1 locus restores the N2,N2-dimethylguanosine modification to both cytoplasmic and mitochondrial tRNA in trm1 cells. An open reading frame in this TRM1 gene is essential for complementation of the trm1 phenotype. Expression of this open reading frame in Escherichia coli converts the organism from one that neither makes N2,N2-dimethylguanosine nor has N2,N2-dimethylguanosine-specific tRNA methyltransferase activity into one that does. This result suggests that the TRM1 locus is the structural gene for the tRNA modification enzyme and that both nuclear/cytoplasmic and mitochondrial forms of the methyltransferase are produced from the same gene.     

Periplasmic location of p-cresol methylhydroxylase in Pseudomonas putida

The cellular location of the flavocytochrome c, p-cresol methylhydroxylase was investigated in two strains of Pseudomonas putida. In both cases the enzymes were shown to be located in the periplasmic fraction by their release during treatment of the bacteria with EDTA and lysozyme in a solution containing a high concentration of sucrose. For strain NCIB 9869 the finding is in accord with the suggestion that the physiological acceptor for the enzyme is azurin as this too was shown to be located mostly in the periplasm.     

Analysis of the inducible MEL1 gene of Saccharomyces carlsbergensis and its secreted product, alpha-galactosidase (melibiase)

We have determined both the nucleotide sequence of the MEL1 gene of Saccharomyces carlsbergensis and the N-terminal amino acid (aa) sequence of its extracellular gene product, alpha-galactosidase (melibiase) (alpha-Gal). The predicted translation product of MEL1 is a pre-alpha-Gal protein containing an 18 aa N-terminal signal sequence for secretion. The purified enzyme is a dimer consisting of two 50-kDal polypeptides, each of which is glycosylated with no more than eight side chains. The 5'-flank of the MEL1 gene contains a region (UASm) having certain areas of sequence homology to similar sites found upstream of the structural genes GAL1, GAL7 and GAL10, which are also regulated by the action of the products of genes GAL4 and GAL80. There are three TATA boxes between UASm and the initiation codon of pre-alpha-Gal, as well as a typical yeast cleavage/polyadenylation sequence in the 3'-flank of the gene.     

Structure of tomato bushy stunt virus: V. Coat protein sequence determination and its structural implications

We report the chemically determined sequence of most of the polypeptide chain of the coat protein of tomato bushy stunt virus. Peptide locations have been determined by comparison with the high-resolution electron density map from X-ray crystallographic analysis as well as by conventional chemical overlaps. Three small gaps remain in the 387-residue sequence. Positively charged side-chains are concentrated in the N-terminal part of the polypeptide (the R domain) as well as on inward-facing surfaces of the S domain. There is homology of S-domain sequences with structurally corresponding residues in southern bean mosaic virus.     

The bacterial metabolism of 2,4-xylenol

1. Measurements of the rates of oxidation of various compounds by a fluorescent Pseudomonas indicated that metabolism of 2,4-xylenol was initiated by oxidation of the methyl group para to the hydroxyl group. 2. 4-Hydroxy-3-methylbenzoic acid was isolated as the product of oxidation of 2,4-xylenol by cells inhibited with alphaalpha'-bipyridyl. 3. 4-Hydroxyisophthalic acid accumulated at low oxygen concentrations when either 2,4-xylenol or 4-hydroxy-3-methylbenzoic acid was oxidized by cells grown with 2,4-xylenol. 4. When supplemented with NADH, but not with NADPH, cell extracts oxidized 4-hydroxy-3-methylbenzoic acid readily. 2-Hydroxy-5-methylbenzoic acid was not oxidized. 5. Both 4-hydroxyisophthalic acid and p-hydroxybenzoic acid were oxidized to beta-oxoadipic acid by cell extracts supplemented with either NADH or NADPH. 4,5-Dihydroxyisophthalic acid was not oxidized. 6. From measurements of oxygen consumed and carbon dioxide evolved it was concluded that protocatechuic acid is an intermediate in the conversion of 4-hydroxyisophthalic acid into beta-oxoadipic acid.     

Aspects of the life cycle of marine nematodes

Summary 1. Life cycles of approximately one month are recorded for laboratory maintained cultures of chromadorid, monhysterid and oncholaimid nematodes.2. Amphimictic and parthenogenetic reproduction occurs in the species investigated. Reproduction inMonhystera parelegantula is by parthenogenesis.3. The chromadoridChromadorina epidemos and the oncholaimidViscosia macramphida are able to reproduce by either amphimixis or parthenogenesis.4.Acanthonchus cobbi, Chromadora macrolaimoides andEuchromadora gaulica are amphimitically reproducing species.

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Aspekte des Lebenszyklus mariner Nematoden

Kurzfassung Bei einigen marinen Nematoden, die in Biscayne Bay (Florida) gesammelt und im Labor gezüchtet worden sind, vollzieht sich der gesamte Lebenszyklus ungefähr innerhalb eines Monats. BeiAcanthonchus cobbi, Chromadora macrolaimoides undEuchromadora gaulica ist zweigeschlechtliche Fortpflanzung festgestellt worden.Monohystera parelegantula vermehrt sich parthenogenetisch. Ein möglicherweise durch Umwelteinflüsse bedingter Wechsel von bisexueller und parthenogenetischer Fortpflanzung tritt beiChromadora epidemos undViscosia macramphida auf.

     

Studies on marine fungal-nematode associations and plant degradation

Summary 1. Studies of the broad-leafed turtle grass,Thalassia testudinum König, have revealed a diverse range of fungal infestation different in generic composition and dynamics of attack from that found on submerged wood. Certain of the fungi, notably the AscomyceteLindra thalassiae, initiate considerable degradation of leaf tissue and show a developmental cycle in nature related to the physiological state of the host plant.2. Use of fungal-cellulose mats as a trapping substrate has been extremely effective for discernment of ecologically significant shifts in nematode concentrations, especially those of the omnivorous species,Metoncholaimus scissus.3. Patterns of activity ofM. scissus, as well as those of various foliicolous nematodes, suggest that loci of organic material, such as fungal infested leaves and decaying plant tissue, significantly affect biological activity of these animals.4. Laboratory analysis of degraded cotton cellulose filters show a striking incidence of fungal reproduction of the ascomycetous fungusLulworthia, along with development of a considerable associated nematode fauna, especially species ofViscosia (V. macramphida) andLeptolaimus (L. plectoides). Successional patterns in nematode development are noted with continued degradation of the cotton cellulose matrix.

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Studien über marine Pilz-Nematoden-Assoziationen und Pflanzendegradation

Kurzfassung Untersuchungen am SeegrasThalassia testudinum König haben ergeben, daß sich hier Pilzinfektionen hinsichtlich der Komposition der beteiligten Gattungen und der Dynamik des Befalls von den am untergetauchten Holz festgestellten Infektionen unterscheiden. Bestimmte Pilze, insbesondere der AscomycetLindra thalassiae, leiten eine erhebliche Degradation des Blattgewebes ein und zeigen einen Entwicklungszyklus, welcher in Beziehung steht zum physiologischen Zustand der Wirtspflanze. Die Anwendung von Pilz-Zellulose-Matten als Einfangsubstrat war außerordentlich erfolgreich für das Erkennen ökologisch signifikanter Verschiebungen in den Nematodenkonzentrationen, insbesondere bei der omnivoren ArtMetoncholaimus scissus. Die Aktivitätsmuster vonM. scissus — ebenso wie die verschiedener foliicolöser Nematoden — deuten darauf hin, daß pilzinfizierte und zerfallende Pflanzenteile in entscheidendem Maße die biologische Aktivität dieser Tiere beeinflussen. Laboratoriumsanalysen degradierter Wollzellulosefilter lassen eine überraschend starke Vermehrung des AscomycetenLulworthia erkennen und gleichzeitig die Entwicklung einer beachtlichen Fauna assoziierter Nematodenarten, insbesondere vonViscosia macramphida undLeptolaimus plectoides. Im Verlaufe der weiteren Degradation der Wollzellulosematrix kommt es bei der Nematodenfauna zu entsprechenden Sukzessionen.

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Contribution No. 768 from the Institute of Marine Science, University of Miami, Miami, Florida, and from the Canada Department of Agriculture, Ottawa, Canada. This work was supported at the IMS by grant GM 12842 from the National Institutes of Health, USA.     

Glutaredoxin from rabbit bone marrow. Purification, characterization, and amino acid sequence determined by tandem mass spectrometry

A glutaredoxin was purified from rabbit bone marrow, and its amino acid sequence was determined by high performance tandem mass spectrometry. The sequences of peptides generated by digestion with trypsin alone or in combination with thermolysin were determined from their collision-induced dissociation (CID) mass spectra. Alignment of these sequences and additional sequence information were obtained from the collision-induced dissociation mass spectra of peptides obtained from digestion of the intact protein with Staphylococcus aureus V8 protease and alpha-chymotrypsin. The resulting sequence of 106 amino acids is as follows: Ac-Ala-Gln-Glu-Phe-Val-Asn-Ser-Lys-Ile-Gln-Pro-Gly-Lys-Val-Val-Val-Phe- Ile-Lys-Pro-Thr-Cys-Pro-Tyr-Cys-Arg-Lys-Thr-Gln-Glu-Ile-Leu-Ser-Glu-Leu- Pro-Phe - Lys-Gln-Gly-Leu-Leu-Glu-Phe- Val-Asp-Ile-Thr-Ala-Thr-Ser-Asp-Met-Ser-Glu-Ile- Gln-Asp-Tyr-Leu-Gln-Gln-Leu-Thr-Gly-Ala-Arg- Thr-Val-Pro-Arg-Val-Phe-Leu-Gly-Lys-Asp-Cys-Ile- Gly-Gly-Cys-Ser-Asp-Leu-Ile-Ala-Met-Gln-Glu-Lys- Gly-Glu-Leu-Leu-Ala-Arg-Leu-Lys-Glu-Met-Gly- Ala-Leu-Arg-Gln. This glutaredoxin strongly resembles the corresponding calf and pig proteins (known as glutaredoxin and thioltransferase, respectively) with respect to its primary structure and enzymatic activity as a GSH:disulfide thioltransferase, an activity also found for the glutaredoxin from Escherichia coli. However, rabbit glutaredoxin was not active as a hydrogen donor for the reduction of ribonucleotides in the presence of the ribonucleotide reductases from rabbit bone marrow, Lactobacillus leichmannii, and Corynebacterium nephridii.