Minimum structure opioids-dipeptide and tripeptide analogs of the enkephalins

Through a systematic reduction of peptide structure, a series of 25 tripeptide and 5 dipeptide amide and alcohol analogs of enkephalin were synthesized and assayed in vitro on the stimulated guinea pig ileum. Tyr-Pro-Phe-NH2, Tyr-D-Ala-Phe-NH2, Tyr-D-Ala-Phe-ol and Tyr-D-Phe-Phe-NH2 had 20-25% the potency of Met-enkephalin. Four aromatic alkylamides of the dipeptide Tyr-D-Ala were made with benzylamine, phenethylamine, phenylpropylamine and phenylbutylamine. All had full naloxone reversible enkephalin-like activity in the ileum assay. Tyr-D-Ala-phenylpropylamide has about 80% the potency of Met-enkephalin in vitro, and is equipotent with Tyr-D-Ala-Gly-Phe-Met-NH2 in producing analgesia in mice after intraventricular administration. Tyr-D-Phe-NH2 is the smallest peptide to show full intrinsic enkephalin-like activity in vitro, although its potency is very low.     

The effect of essential-fatty-acid deficiency on the activity of liver phosphatidate phosphatase in rats

The activities of the soluble and microsomal phosphatidate phosphatases (EC 3.1.3.4) are greater in the livers of essential-fatty-acid-deficient rats than in rats fed diets containing linoleic acid.     

Light-harvesting pigment-protein complex deficiency in Hosta (Liliaceae)

A yellow-leaved plastome mutant of Hosta (Hosta sieboldii Ingram complex, Liliaceae) known as Wogan Gold lacks normal granal stacks, but has numerous stroma lamellae extending throughout the chloroplast. The chlorophyll a/b ratio is 0.76 in the mutant and 2.9 in wild type. The mutant contains a qualitatively normal pattern of other photosynthetic co-pigments. SDS-polyacrylamide gel electrophoresis showed a deficiency in the photosystem (PS) II light-harvesting complex. Since PS II is localized mainly in the granal region, the absence of the light-harvesting complex may explain the loss of granal stacking in this mutant.Abbreviation PS photosystem     

Prevention of fungal colonization and digestion of cellulose by the addition of methylcellulose

When the attachment of cellulolytic rumen fungi to cellulose is blocked by the addition of methylcellulose, cellulose digestion is entirely inhibited. Even after these fungi have colonized and penetrated the cellulosic fibers of filter paper, the addition of methylcellulose effectively halts cellulose digestion. This effect of methylcellulose is accompanied by the complete inhibition of fungal attachment to cellulose fibers; the addition of methylcellulose does not affect the growth of these organisms on soluble substrates. We conclude that fungal cellulose digestion, like bacterial cellulose digestion, requires the spatial juxtaposition of the cellulolytic organism and its insoluble substrate. The simultaneous inhibition of both attachment and digestion by the same inhibitor suggests that these two processes are functionally linked in the fungi.     

The disulfide bridge pattern of snake venom disintegrins, flavoridin and echistatin.

Flavoridin and echistatin, isolated from the venom of Trimeresurus flavoviridis and Echis carinatus, respectively, belong to the disintegrin family of integrin beta 1 and beta 3 inhibitors of low molecular weight RGD-containing, cysteine-rich peptides. Since disulfide bonds are critical for expression of biological activity, we sought to determine their location in these two proteins. In flavoridin, direct evidence for the existence of linkage between Cys4-Cys19 and between Cys45 and Cys64 was obtained by analysis of proteolytic products, and indirect evidence suggests links between Cys6-Cys14 and Cys13-Cys36. In echistatin, links between Cys8-Cys37 and Cys20-Cys39 were identified by direct chemical analysis.     

Nitrate regulation of anaerobic respiratory gene expression in narX deletion mutants of Escherichia coli K-12.

Previous studies have shown that narL+ is required for nitrate regulation of anaerobic respiratory enzyme synthesis, including formate dehydrogenase-N, nitrate reductase, and fumarate reductase. Insertions in the closely linked narX gene decrease, but do not abolish, nitrate regulation of anaerobic enzyme synthesis. Analysis of sequence similarities suggests that NarX and NarL comprise a two-component regulatory pair. We constructed lacZ operon and gene fusions to investigate the operon structure of narXL. We found evidence for a complex operon with at least two promoters; PXL-narX-PL-narL. We also investigated the role of NarX in nitrate regulation of anaerobic respiratory enzyme synthesis by constructing nonpolar loss of function narX alleles. These deletions were studied on narL+ lambda specialized transducing bacteriophage. The narX deletions had no effect on nitrate regulation in delta (narXL) strains. This finding suggest that the subtle effects of previously studied narX insertions are due to decreased expression of narL and that narX+ is not essential for normal nitrate regulation. The role of NarX in nitrate regulation remains to be determined.     

Q fever in maritime Canada.

Only nine cases of Q fever were recorded in Canada in the 20 years prior to 1978. In the 18 months from August 1979 to January 1981 the disease was diagnosed serologically in six patients from the Maritime provinces. All were epidemiologically unrelated and none had been exposed to animals. Five had pneumonia and one had chronic Q fever with probable prosthetic valve endocarditis. Three of the five pneumonia patients presented with signs and symptoms of an acute lower respiratory tract infection and were indistinguishable clinically from other patients with atypical pneumonias. The other two with pneumonia presented with nonresolving pulmonary infiltrates and complained of decreased energy. Four of the five pneumonia patients responded well to treatment with erythromycin; the fifth required two courses of tetracycline. The patient with chronic Q fever had a large amount of cryoglobulins in his serum and evidence of immune complex disease. These cases indicate that Q fever should be considered as a possible cause of atypical pneumonia in Canada.     

Anhydrobiosis in Nematodes II: Carbohydrate and Lipid Analysis in Undesiccated and Desiccate Nematodes

Glycogen, trehalose, glucose, and total lipid contents of six nematode species were studied. Anhydrobiotic Anguina tritici and Ditylencbus dipsaci stored trehalose in preference to glycogen and only small amounts of glucose were detected. Glycogen content was also reduced in anhydrobiotic Aphelenchus avenae. Conversely, Panagrellus redivivus and Turbatrix aceti contained large amounts of glycogen, appreciable amounts of glucose, and minimal amounts of trehalose. Ditylenchus myceliophagous "curds" contained low amounts of glycogen and very little trehalose; total lipid was 60% of that in fresh samples. The lipid contents of fresh samples of P. redivivus, T. aceti, and A. avenae were high (23.1, 21.9, and 36.7% dry weight, respectively), but in anhydrobiotic A. avenae larvae the level was reduced by over 60%. In contrast, lipid levels remained high in anhydrobiotic A. tritici and D. dipsaci larvae (40.6 and 38.3%, respectively). Analysis of lipid composition in anhydrobiotic A. tritici and A. avenae did not indicate any specific metabolic adaptations to desiccation survival.