Differential Adhesion and Infection of Nematodes by the Endoparasitic Fungus Meria coniospora (Deuteromycetes)

The conidia of the endoparasitic fungus Meria coniospora (Deuteromycetes) had different patterns of adhesion to the cuticles of the several nematode species tested; adhesion in some species was only to the head and tail regions, on others over the entire cuticle, whereas on others there was a complete lack of adhesion. After adhesion, the fungus usually infected the nematode. However, adhesion to third-stage larvae of five animal parasitic nematodes, all of which carry the cast cuticle from the previous molt, did not result in infection. M. coniospora infected animal parasitic nematodes when this protective sheath was removed. Seven preparations of sialic acid (N-acetylneuraminic acid) gave three types of response in adhesion-infection of nematodes: (i) a significant reduction in conidial adhesions; (ii) no interference with adhesion, but a 10-day delay in infection; and (iii) a delay in infection by 2 to 3 days. The current results support previous findings indicating involvement of sialic acids localized on nematode cuticles in recognition of prey by M. coniospora.     

Purification and characterization of a new form (RLM2) of liver microsomal cytochrome P-450 from untreated rat

A new cytochrome P-450 isozyme (RLM2) has been purified to electrophoretic homogeneity from liver microsomes of the untreated rat. It has an apparent minimum molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis of 49,000. Absolute spectrum of the oxidized form indicates that this isozyme is essentially all in the low spin state. The maximum of the reduced CO complex is at 449 nm. Amino-terminal partial amino acid sequence and amino acid composition are different from those of RLM3 and RLM5, two other native forms of cytochrome P-450 previously reported from this laboratory as well as other forms reported in the literature. RLM2 is capable of oxidizing a variety of drug substrates, like benzphetamine and aminopyrine, and to a lesser extent ethoxycoumarin. With the steroid substrate multiple isomeric products are formed differentially. Progesterone is preferentially hydroxylated at the 15-position (15 beta-hydroxylation (34%) and 15 alpha-hydroxylation (13%) of the total) and at the 6 beta-position (21%). The major metabolite when testosterone was the substrate, 15 alpha-hydroxytestosterone, comprised 43% of the total, while a modest amount of 6 beta-hydroxytestosterone (12%) is formed. Another major metabolite (31%) has yet to be unequivocally identified, but is suggested to be 7 beta-hydroxytestosterone. Examination of the substrate dependence of major and minor isomeric metabolites provides evidence for a single substrate-binding site on RLM2. Regardless of the position hydroxylated, a common Km value was obtained. It is suggested that differences in formation of the isomeric and epimeric products relate to differences in distance from the active oxygen center and the position of attack.     

Bombesin, neurotensin and pro-gamma-melanotropin immunoreactants in human milk

The concentration of bombesin-like, neurotensin-like and pro-gamma-melanotropin-like immunoreactants in human skim milk was measured by radioimmunoassay and found to be 235 pg/ml (mean, n = 13, range 60-430 pg/ml), 63 pg/ml (mean, n = 13, range 20-105 pg/ml) and 2.4 ng/ml (mean, n = 6, range 1.2-5 ng/ml), respectively. The concentrations were 5-10 times higher than in plasma. High performance liquid chromatography showed that the neurotensin and pro-gamma-melanotropin immunoreactants co-eluted with the authentic peptides. Bombesin gave three peaks, one co-eluting with authentic bombesin and one with porcine gastrin releasing peptide 14-27, whereas another one had a shorter elution time, suggesting a less hydrophobic fragment, possibly even smaller than gastrin releasing peptide 14-27.     

Molecular organisation of the genes involved in the production of F7(2) fimbriae, causing mannose-resistant haemagglutination, of a uropathogenic Escherichia coli 06:K2:H1:F7 strain

Summary The genes responsible for the formation of the F7₂ fimbriae of the uropathogenic E. coli strain AD110 (O6:K2:H1:F7) have been cloned on the recombinant plasmid pPIL110-35 (Van Die et al. 1983). The F7₂ fimbriae, like the F7₁ fimbriae of AD110, are responsible for mannose resistant haemagglutination (MRHA).The molecular organisation of the genes of pPIL110-35 involved in the expression of MRHA was studied by: (a) analysis of transposon and Tn5 insertion mutants. Mutations that cause an MRHA-deficient phenotype were located in discrete groups within an 11.5 kb restriction fragment of pPIL110-35, separated by insertion mutations that do not inactivate MRHA. (b) complementation experiments. Restriction fragments of pPIL110-35 subcloned in the vector pBR322 were tested for their ability to complement transposon insertion mutations in the corresponding regions of pPIL110-35. Five complementation groups were distinguished.Five genes (designated A-E) involved in the expression of MRHA can be distinguished by these results. The products of these genes were analysed in minicells. The results indicate that gene B codes for a 75 K dalton protein, gene C for a 23 K dalton protein and gene E for a 36 K dalton protein. No product of gene D was observed. Gene A probably codes for the 17 K dalton subunit polypeptide of the F7₂ fimbriae, as will be discussed.     

Parasitism ofLeptinotarsa decemlineata [Coleoptera: Chrysomelidae] byEdovum puttleri [Hymenoptera: Eulophidae] in different cultivars of eggplant

Experiments were conducted to quantify parasitism of Colorado potato beetle,Leptinotarsa decemlineata (Say), by the egg parasitoid,Edovum puttleri Grissell, on 3 different cultivars of eggplant,Solanum melongena L. Levels of parasitism were higher (P<0.05) on ‘Black Pride’ than on other cultivars. The percentage of egg masses that were parasitized was 1.2-fold higher (P<0.05) on ‘Black Pride’ than on ‘Harris Special’ and ‘White’. The number of eggs per mass that were parasitized was 1.3- and 1.4- fold greater (P<0.05) on ‘Black Pride’ than on ‘Harris Special’ and ‘White’, respectively. The percentage of eggs that were parasitized per mass and percentage of emerged adult parasitoids did not differ (P>0.05) among cultivars; between 2.1- to 2.6- fold more females than males emerged from eggs on all cultivars during the growing season.Edovum puttleri suppressed the 2nd generation ofL. decemlineata on ‘Black Pride’ and ‘Harris Special’, but did not suppress populations on ‘White’.      

Isolation and characterization of a 23 kDa protein essential for photosynthetic oxygen evolution

A 23 kDa protein has recently been demonstrated to participate in photosynthetic oxygen evolution by reconstitution experiments on inside-out thylakoid vesicles (Åkerlund H-E, Jansson C and Andersson B (1982) Biochim Biophys Acta 681:1–10). Here we describe the isolation of the 23 kDa protein from a spinach chloroplast extract using ion-exchange chromatography. The protein was obtained in a yield of 25% and with less than 1% of contaminating proteins. The ability of the protein to stimulate oxygen evolution in inside-out thylakoids was preserved throughout the various fractionation steps. The isolated protein was highly water soluble and appeared as a monomer. Its isoelectric point was at pH=7.3. The amino acid composition showed a high content of polar amino acids, resulting in a polarity index of 49%. The isolated protein lacked metals and other prosthetic groups. Its function as a catalytic or regulating subunit in the oxygen evolving complex is discussed.     

Simulated and measured nitrogen conditions in a manured and fertilised soil

The governing factors for soil nitrogen dynamics were identified with a simulation model. In addition, the model was used to interpret measurements from a plot fertilisation experiment in southwest Sweden.Simulated moisture and temperature conditions were the driving variables for the simulation of soil nitrogen dynamics and leaching during a 6-year period. The results of the simulation were compared with monthly observations on two plots with grain crops, one with liquid manure and commercial fertilisers applied and one with commercial fertilisers only.Simulated temporal variations of the nitrate and ammonium storages generally agreed with observations. The dominant role of the crops as a determinant of soil nitrogen conditions was demonstrated. A higher leaching loss from the plot with application of commerical fertilisers only occurred both in simulations and measurements compared to the plot with application of both commercial fertilisers and manure. The main reason was the higher N-application in the former treatment.The effect of water flows in macropores was interpreted as a delay of simulated leaching compared to observed leaching on some occasions in summer and early autumn. No direct effect of the macropores on the yearly rates of leaching could be seen.     

Myoglobin content and citrate synthase activity in different parts of the normal human heart

Myoglobin (Mb) content and citrate synthase (CS) activity were determined in myocardial samples from nine human brain-dead organ donors with normal hearts. Six regions of each heart were analyzed: right and left atria, right ventricle, left ventricular subepicardium, subendocardium, and anterior papillary muscle. The Mb content was similar, whereas the CS activity was higher in the left than in the right heart at both atrial and ventricular levels. Mb content and CS activity were higher in ventricles than in atria. The subendocardial layer and papillary muscle of the left ventricle had a higher Mb content than the subepicardial layer, whereas CS activity was similar in these three locations. The results suggested a closer relationship between CS activity (oxidative potential) and work load than between Mb content and work load. Mb content may, instead, be related to intramuscular oxygen tension (PO2) on the basis of a comparison between our Mb data and those of others on regional variations in myocardial PO2.     

Specific monitoring by PCR amplification and bioluminescence of firefly luciferase gene-tagged bacteria added to environmental samples

Abstract The firefly luciferase gene, luc , was demonstrated to hold promise as a specific marker for monitoring of genetically modified bacteria in the environment. PCR amplification and bioluminescence procedures were modified and compared for environmental monitoring of luc -tagged bacteria, using Escherichia coli as a model. The methods were used to track luc -tagged bacterial cells added to intact sediment core microcosms. Detection limits for the luc -tagged cells were the following, expressed as cells per 0.5 g of sediment: 10², by PCR amplification; 10³, by whole cell luminescence; and 10³−10⁴, by measurement of luminescence in cell extracts.