Effect of labuctril 25 and three other herbicides on wild soil isolates and mutant strains of streptomycetes

Labuctril 25 (3,5-dibromo-4-hydroxybenzonitrile, LAB) at concentrations up to 100μg/mL inhibits effectively growth, morphology, and pigmentation of most soil streptomycete isolates grown under laboratory conditions. Oxytril CM (OXT), Basagran (BAS) and Faneron 50 WP (FAN) applied at the same concentrations had no detectable effect on growth of substrate mycelium but suppressed both aerial mycelium and pigment formation, the effectivity decreasing in the order OXT—BAS—FAN. The LAB-sensitivity of mutant strains was markedly higher as compared with that of the soil isolates. A wild strain resistant to 100–400μg of LAB per mL (depending on the medium composition) was isolated. It was capable of supporting the growth and development of sensitive strains on the LAB-containing medium. A stimulatory effect of low doses of LAB (10–20μg/mL) on the antibiotic activity of streptomycetes was observed.     

Passage of foreign proteins across the intestinal wall of newborn rabbits

Foreign proteins penetrate across the wall of rabbit jejunum takes place within the first eight hours after birth. Sensitization by foreign protein (cow's milk protein) during early postnatal ontogeny is the cause of death of artificially fed germfree rabbits at the age of 21-23 d.     

Identification of natural tricetin-derived C-glycosides through synthesis

C-Glycosylation of 5,7-dihydroxy-3′,4′,5′-trimethoxyflavone was carried out with acetobromo-α-d-glucose, -α-d-galactose, -α-d-xylose, -β-l-arabinose and -αt-L-rhamnose. The respective 6-C-glycosides and 6, 8-di-C-glycosides (excepted for galactose) were isolated and permethylated. MS and TLC comparison confirmed the proposed structures of five natural tricetin-derived C-glycosides.     

Sugar ring isomerization in C-arabinosylflavones

6-C-α-l-Arabinopyranosyl- and furanosylacacetins have been synthesized. They are isomerized by short acid treatment to give a mixture of the four anomer/ring size combinations without any Wessely-Moser isomerization. In the same conditions molludistin (8-C-α-l-arabinopyranosylgenkwanin) led only to a mixture of molludistin and 8-C-α-l-arabinofuranosylgenkwanin. This is the first demonstration of ring sugar isomerization in C-glycosylflavones. In usual solvent systems, α-anomers are easily separated from β-anomers, whereas corresponding pyranosyl and furanosyl anomers are not. However, they are easily separated after permethylation and characteristic features are found in the mass spectra of PM 6-C-arabinofuranosyl isomers.     

Restriction map of Tn7

Tn7, a transposon of 14 kb, encodes resistance to trimethoprim (Tp) and streptomycin (Sm). A cleavage site map of this transposon for twenty-two different restriction enzymes as determined by comparison of restriction enzyme cleavage patterns of the plasmids ColE1 and ColE1::Tn7 is presented. The precise localization of these sites was facilitated by the use of two deletion derivatives of ColE1::Tn7: pGB2 and ColE1::Tn7Δ6, and by the use of pOB14 and pOB15 which contain a part of Tn7 cloned into the plasmid pBR322. This map should aid in the study of the structural and genetic organization of this transposon.     

Distribution of corticotropin-releasing factor in ovine brain determined by radioimmunoassay

We have developed and used a sensitive and specific radioimmunoassay to demonstrate the presence of CRF-like immunoreactivity in extra-hypothalamic areas of ovine brain. Synthetic CRF displaced antibody bound tracer at an ED50 value of 200 pg and there was no cross-reactivity with LHRH, TRH, ACTH, beta-endorphin and several other peptides. Displacement of bound 125I-CRF by brain extracts exhibited curves parallel to synthetic CRF standards. Highest concentrations (1 ng/mg tissue) of CRF-like immunoreactivity were found in the median eminence but surprisingly, high concentrations of CRF-like immunoreactivity were found in frontal, parietal, occipital and particularly temporal areas of cerebral cortex. Much lower concentrations were found in other brain areas including the basal ganglia, limbic system and brain stem.     

Characterization of a 45-kDa polypeptide as the precursor of subunit 1 of cytochrome c oxidase in Neurospora crassa

In a previous paper (Van 't Sant, P., Mak, J.F.C. and Kroon, A.M. (1981) Eur. J. Biochem. 121, 21–26) we showed the existence of three elongated precursor proteins (45, 36 and 25 kDa) of mitochondrial translation products in Neurospora crassa. We presented some indications that the largest precursor could be related to subunit 1 of cytochrome c oxidase. Here we present conclusive evidence that the 45-kDa polypeptide is indeed this precursor by demonstrating that an immunodetectable 45-kDa polypeptide displays the same behaviour as the labeled 45-kDa precursor; both accumulate after long incubation with cycloheximide or by decreasing the temperature and both are not tightly membrane bound. Moreover the antibody against subunit 1 of cytochrome c oxidase also recognizes, in immunoadsorption experiments, besides subunit 1, the 45-kDa polypeptide accumulated by cycloheximide incubation. Furthermore, we developed a small scale purification of antibodies against subunit 1 of cytochrome c oxidase. By means of these purified antibodies it is demonstrated that the 45-kDa polypeptide and subunit 1 have corresponding antigenic determinants. Under the various conditions tested, all three precursors are less firmly membrane-bound than the mature subunits. Finally, it is observed that in short incubations in vivo, chloramphenicol inhibits the processing of the mitochondrially synthesized precursors, under conditions where mitochondrial translation is only partially inhibited.     

Diminished dietary thermogenesis in exercise-trained human subjects

The influence of exercise-training on dietary-induced thermogenesis (DIT) was investigated in humans. The resting metabolic rate was identical in trained and non-trained subjects, but the response to a meal containing 1,636 kcal (6.9 MJ) was markedly lower in trained subjects. Mean dorsal skin temperature, as measured by thermography, was not influenced by training. A significant correlation was observed between postprandial RQ and DIT, which indicates that the reduced energy expenditure noted in trained subjects is related to a greater lipid oxidation. This sparing effect of exercise-training on energy utilization in the form of carbohydrate, is interpreted as adaptive in the sense that energy is preserved for the purpose of producing work.