Reversible inactivation of soluble liver guanylate cyclase by disulfides

A new amino acid was isolated from the cuticle collagen of $\text{Ascaris lumbricoides}$ and characterized by ultraviolet, mass and nmr spectroscopies and chemical degradation. The results indicate that the compound is an isomer of trityrosine, having an ether linkage. The name “isotrityrosine” is proposed. Its structure suggests that it serves as a crosslink and plays a role in the organization of the collagen structure.     

Regulation of Rat Dopamine Transporter mRNA and Protein by Chronic Cocaine Administration

This study describes a direct comparison of dopamine transporter (DAT) mRNA and protein, as well as its binding sites, in tissue from the same animals after chronic cocaine administration. Rats were treated twice daily with 25 mg/kg cocaine or with saline. After 8 days of cocaine administration, changes in DAT mRNA levels in the substantia nigra pars compacta and ventral tegmental area were measured by in situ hybridization, and DAT protein in the striatum was quantified by immunoblotting. Whereas chronic cocaine treatment significantly reduced levels of DAT mRNA in the substantia nigra pars compacta and ventral tegmental area as compared with vehicle-treated controls, cocaine treatment did not alter DAT protein levels in the striatum. Furthermore, the density of DAT binding sites was also measured in the striatum by quantitative autoradiography using two DAT radioligands, 33-(4-[125I]iodophenyl)tropane-2-carboxylic acid methyl ester ([125I]RTI-55) and [3H]propanoyl-3beta-(4-tolyl)tropane ([3H]PTT). Similar to the results of immunoblotting of DAT protein, [1251]RTI-55 and [3H]PTT binding site levels also remained unaltered. These results indicate a dissociation in the regulation of DAT mRNA and its protein levels as a result of cocaine administration in rats. This study also indicates that the DAT ligands [3H]PTT and [125I]RTI-55 provide an accurate assessment of DAT protein levels.     

Minireview: Part II: Biochemical considerations of morbid obesity

Whereas the cardiorespiratory derangements of severe obesity have received careful scrutiny, the biochemical alterations unique to that state are not well known. This review will examine in morbidly obese patients the hepatic abnormalities related to morphology, function, and lipid metabolism. Altered xenobiotic biotransformation will then be discussed. Available studies in man will emphasize what is known about the biochemical aberrations exemplified by this abnormal biologic state.     

Role of plant parasitic nematodes and abiotic soil factors in growth heterogeneity of sugarcane on a sandy soil in South Africa

A feature of many sugarcane fields is the patchy growth. This is often thought to be due to physical or chemical differences in the soil. In this paper we investigate the causes of growth heterogeneity of sugarcane on a sandy soil in KwaZulu-Natal, South Africa. To identify the factors that were associated with the good and poor areas, soil texture, pH, organic matter content and a number of soil chemical elements and nematode community data were subjected to principal component analysis (PCA). The numbers of each of the nematode species (Meloidogyne sp., Pratylenchus zeae, Helicotylenchus dihystera, Xiphinema elongatum and Paratrichodorus sp.) were first converted to relative proportions of ectoparasites and endoparasites. The data were collected from the 2nd ratoon crop of a nematicide trial, where half of the plots had been treated with aldicarb in the preceding two crops. Yields of control plots varied from 34.7 to 126.8 t cane ha^–1 and from 85.4 to 138.7 for the treated plots. The yield data were centred and normalised separately for the treated and control plots and the values projected on the trial map to study spatial distribution. Plots with above-average yields, whether treated or untreated, occurred in the lower part of the trial site. The PCA factorial values were also projected onto the map of the trial. According to the first factor of the analysis of the abiotic soil characteristics in the 0–20 cm surface layer, the trial site could be divided into two areas, one on the left and one on the right. PCA of the soil data from the 0–20 and 20–40 cm layers showed that there was little or no difference between the two that might explain the two growth areas. However, analysis of the nematode community distinguished two main areas that largely corresponded to the distribution of the plots of low and high yielding cane. Correlation analysis confirmed the relationship between nematodes and yield. H. dihystera was positively correlated with yield of cane whereas the reverse was true for the Meloidogyne species.     

Nicotinic Receptor-Mediated Release of Noradrenaline in the Human Neuroblastoma SH-SY5Y

Abstract: Dimethylphenylpiperazinium iodide (a nicotinic agonist) evokes noradrenaline release from human neuroblastoma SH-SY5Y cells that have been pretreated with 12- O -tetradecanoylphorbol 13-acetate for 8 min. This effect of dimethylphenylpiperazinium iodide was inhibited by 1 μ M mecamylamine but not by 1 μ M atropine, which suggests that SH-SY5Y cells express nicotinic receptors coupled to the release of noradrenaline. Dimethylphenylpiperazinium iodide-evoked release was enhanced by 5 μ M Bay K 8644 (an L-type calcium agonist) and inhibited by 1 μ M nifedipine. Dimethylphenylpiperazinium iodide depolarised SH-SY5Y cells and enhanced the level of intracellular calcium in cells loaded with fura 2. The effects of dimethylphenylpiperazinium iodide on noradrenaline release, depolarisation, and intracellular calcium levels were all inhibited by 1 μ M desmethylimipramine. The results of this study show that nicotinic receptors in SH-SY5Y cells stimulate noradrenaline release by activation of L-type calcium channels.     

Tyrosine Hydroxylation in Betalain Pigment Biosynthesis Is Performed by Cytochrome P450 Enzymes in Beets (Beta vulgaris)

Yellow and red-violet betalain plant pigments are restricted to several families in the order Caryophyllales, where betacyanins play analogous biological roles to anthocyanins. The initial step in betalain biosynthesis is the hydroxylation of tyrosine to form L-DOPA. Using gene expression experiments in beets, yeast, and Arabidopsis, along with HPLC/MS analysis, the present study shows that two novel cytochrome P450 (CYP450) enzymes, CYP76AD6 and CYP76AD5, and the previously described CYP76AD1 can perform this initial step. Co-expressing these CYP450s with DOPA 4,5-dioxygenase in yeast, and overexpression of these CYP450s in yellow beets show that CYP76AD1 efficiently uses L-DOPA leading to red betacyanins while CYP76AD6 and CYP76AD5 lack this activity. Furthermore, CYP76AD1 can complement yellow beetroots to red while CYP76AD6 and CYP76AD5 cannot. Therefore CYP76AD1 uniquely performs the beet R locus function and beets appear to be genetically redundant for tyrosine hydroxylation. These new functional data and ancestral character state reconstructions indicate that tyrosine hydroxylation alone was the most likely ancestral function of the CYP76AD alpha and beta groups and the ability to convert L-DOPA to cyclo-DOPA evolved later in the alpha group.