Homozygous tyrosinase gene mutation in an American black with tyrosinase-negative (type IA) oculocutaneous albinism

We have identified a tyrosinase gene mutation in an American black with classic, tyrosinase-negative oculocutaneous albinism. This mutation results in an amino acid substitution (Cys----Arg) at codon 89 of the tyrosinase polypeptide. The proband is homozygous for the substitution, suggesting that this mutation may be frequently associated with tyrosinase-negative oculocutaneous albinism in blacks.     

Biotransformation of aflatoxin B1 and its conjugated metabolites by rat gastrointestinal microfloras.

Rat cecal microflora from high- and low-fiber-fed animals hydrolyzed aflatoxin conjugates to metabolites indistinguishable from aflatoxin B1 and aflatoxin P1, but aflatoxicol was not a transformation product.     

Hepatitis B surface antigen in pregnant women

Screening of HBsAg in 289 randomly selected normal pregnant women was done with counterelectrophoresis. Ten percent were found to be HBsAg positive. All of the 289 cord blood samples were HBsAg negative. Babies born to the HBsAg positive mothers were followed 2-8 months (average 3.5 months) after delivery and 37.5% were positive for HBsAg. Accordingly, the vertical transmission of HBsAg was postulated to occur during labor or after birth.     

CONTRIBUTION OF POLLEN MORPHOLOGY TO SYSTEMATICS OF COLLOMIA (POLEMONIACEAE)

Pollen morphology of 14 species of Collomia (Polemoniaceae) was examined by light microscopy, and by both scanning and transmission electron microscopy. Four distinct pollen types were observed which are based principally upon 1) shape, number and distribution of apertures, and 2) surface sculpturing: Type 1—zonocolporate with striate ridges; Type 2—zonocolporate with striato-reticulate ridges; Type 3—pantoporate with radiate ridges; Type 4—pantoporate with irregularly reticulate ridges. Evaluation of pollen morphology reveals considerable discrepancy with respect to presently accepted sectional classification. Collomia grandiflora of sect. Collomia has a pollen type similar to that of members of sect. Collomiastrum and is now interpreted as representing an independent evolutionary line derived from the latter section. Collomia diversifolia of sect. Courtoisia has a pollen morphology similar to that of sect. Collomia. whereas C. heterophylla of the same section possesses pollen unique within the genus. This last pollen type shows close similarity to the pollen of members of Polemonium, Gilia, Leptodactylon, and Ipomopsis. Pollen of C. tinctoria and C. tracyi of sect. Collomia are anomalous within Polemoniaceae. No significant difference in exine stratification was discernible among the four pollen types.     

Growth of Chaetomium cellulolyticum on Alkali-Pretreated Hardwood Sawdust Solids and Pretreatment Liquor

The treatment of a hardwood sawdust with 1% NaOH solution at 121°C dissolved 19.7% of the dry matter, mainly hemicellulose and lignin. Fermentation of the treated solids by Chaetomium cellulolyticum for 48 h gave a product containing 12.5% crude protein (total N × 6.25) on a dry weight basis. The in vitro rumen digestibility of the 48-h fermentation product was 30%, compared to 24% for the alkali-treated but unfermented sawdust. Growth was independent of sawdust particle size in the range 40 to 100 mesh. Fermentation of the pretreatment liquor gave a product containing up to 50% crude protein (dry weight basis) with an in vitro rumen digestibility of 65 to 76%. Approximately 6.7 g of crude protein was obtained from the treated solids and 2.2 g from the pretreatment liquor per 100 g of sawdust treated. The product from the pretreatment liquor fermentation has potential as a high-protein animal feed supplement but could not be produced economically without an outlet for the relatively indigestible product from the solids fermentation. Growth on the pretreatment liquor was strongly pH dependent; there was a considerable increase in the lag phase when the pH was lowered from 7.5 to 5.2. This effect appears to be due to an inhibitor whose toxicity is reduced at high pH.     

Anthraquinones in the biosynthesis of sterigmatocystin by Aspergillus versicolor.

14C-labeled averufin, versiconal hemiacetal acetate, and versicolorin A were efficiently converted to sterigmatocystin by Aspergillus versicolor, thus providing experimental evidence that these anthraquinones are biosynthetic precursors of sterigmatocystin, a xanthone.     

Microbial Metabolism of a Parathion-Xylene Pesticide Formulation

A mixed bacterial culture was adapted to growth on a mixed carbon substrate consisting of the pesticide parathion and its xylene-based formulation. The environmental growth parameters of temperature, pH, and dissolved oxygen concentration were optimized to obtain complete metabolism of parathion from this mixed carbon substrate. This adapted culture grew rapidly (mu = 0.7 per h) on the pesticide formulation at high parathion suspensions (3,000 mg/liter). Carbon utilization from this mixed substrate was strongly dependent on pH. At slightly acidic pH, xylene was preferentially metabolized, whereas at slightly alkaline pH, parathion was preferentially metabolized. Diethylthiophosphoric acid, a metabolite from parathion, and toluic acid, a metabolite from xylene, also influenced the selection of the primary carbon source.     

Intercellular communication in the rat anterior pituitary gland: an in vivo and in vitro study

The concept of "stimulus-secretion coupling" suggested by Douglas and co-workers to explain the events related to monamine discharge by the adrenal medulla (5, 7) may be applied to other endocrine tissues, such as adrenal cortex (36), pancreatic islets (4), and magnocellular hypothalamic neurons (6), which exhibit a similar ion-dependent process of hormone elaboration. In addition, they share another feature, that of joining neighbor cells via membrane junctions (12, 26, and Fletcher, unpublished observation). Given this, and the reports that hormone secretion by the pars distalis also involves a secretagogue-induced decrease in membrane bioelectric potential accompanied by a rise in cellular [Ca++] (27, 34, 41), it was appropriate to test the possibility that cells of the anterior pituitary gland are united by junctions.     

Sequence dependence of Drosophila topoisomerase II in plasmid relaxation and DNA binding

The sequence dependence of Drosophila topoisomerase II supercoil relaxation and binding activities has been examined. The DNA substrates used in binding experiments were two fragments from Drosophila heat shock locus 87A7. One of these DNA fragments includes the coding region for the heat shock protein hsp70, and the other includes the intergenic non-coding region that separates two divergently transcribed copies of the hsp70 gene at the locus. The intergenic region was previously shown to have a much higher density of topoisomerase cleavage sites than the hsp70 coding region. Competition nitrocellulose filter binding assays demonstrate a preferential binding of the intergene fragment, and that binding specificity increases with increasing ionic strength. Dissociation kinetics indicate a greater kinetic stability of topoisomerase II complexes with the intergene DNA fragment. To study topoisomerase II relaxation activity, we used supercoiled plasmids that contained the same fragments from locus 87A7 cloned as inserts. The relative relaxation rates of the two plasmids were determined under several conditions of ionic strength, and when the plasmid substrates were included in separate reactions or when they were mixed in a single reaction. The relaxation properties of these two plasmids can be explained by a coincidence of high-affinity binding sites, strong cleavage sites, and sites used during the catalysis of strand passage events by topoisomerase II. Sequence dependence of topoisomerase II catalytic activity may therefore parallel the sequence dependence of DNA cleavage by this enzyme.     

Methodology for the analysis of fenbendazole and its metabolites in plasma, urine, feces, and tissue homogenates

New methodology for the extraction and analysis of the anthelmintic fenbendazole and its metabolites from plasma, urine, liver homogenates, and feces from several animal species is presented. Quantitation of fenbendazole and its metabolites was conducted by high-pressure liquid chromatography using ultraviolet detection at 290 nm. The combined extraction and analysis procedures give excellent recoveries in all of the different biological matrices examined. High specificity, low limits of detection, and excellent linearity, accuracy, and inter- and intrasample variability were also obtained. The study of fenbendazole pharmacokinetics in vitro and in vivo should be greatly enhanced through the utilization of these methods.