High impact information on OTC

• The gene for rat ornithine transcarbamylase (OTC), an ornithine cycle enzyme, is mainly expressed in the liver and is under the control of the promoter and the 11-kilobase upstream enhancer, both of which are liver-selective [1].
• We suggest that the absence of P-5-C synthase and ornithine carbamoyltransferase in enterocytes is the metabolic basis for the nutritional requirement of arginine in the chick [2].
• This has been used in the diagnosis of heterozygosity for ornithine carbamoyltransferase deficiency for many years by measuring the subsequent excretion of orotic acid in urine [3].
• Ornithine carbamoyltransferase deficiency: improved sensitivity of testing for protein tolerance in the diagnosis of heterozygotes [3].
• Linkage analysis has suggested reassignment of the chicken OTC gene from the suggested Z chromosome to chromosome 1q [4].

Biological context of OTC

• We cloned the OTC cDNA from chicken kidney and found 77% homology between the deduced amino acid sequence of the mature protein and that of mammals [4].
• The 5'-flanking region contains a putative TATA box and two potential regulatory sites, but neither the 5'-flanking region nor the splice sites correlated with variation in OTC activity [4].
• The chicken OTC gene spans 26 kb, consists of 10 exons and 9 introns, and utilizes the same exon-intron boundaries as the human gene [4].
• It was suggested that egg yolk or an ingredient(s) induces chick kidney OTC and that utilization of egg yolk promotes the formation of OTC in chick kidney during embryonic development and during subsequent growth of the chick [5].
• Chicken ornithine transcarbamylase gene, structure, regulation, and chromosomal assignment: repetitive sequence motif in intron 3 regulates this enzyme activity [4].

Anatomical context of OTC

• A 90% egg yolk diet resulted in an increase of about 2.5-fold in kidney OTC activity [5].
• The results of this study suggest that, unlike mammals, chickens are more organ specific with regard to the ability to incorporate precursor OTC into mitochondria [6].
• Since a chick develops during embryonic life by utilizing egg yolk from the yolk sac, the variation of OTC activity among chicken breeds and within a breed in 2-day-old chicks seems to depend on a genetically controlled difference of inducibility by egg yolk [7].
• When an extract of small intestine containing only precursor OTC was treated with a kidney extract, the precursor was converted into OTC [6].
• No treatment differences were observed for heart or pancreas weights or for their weights as % OTC [8].

Associations of OTC with chemical compounds

• Ornithine transcarbamylase (OTC) is one of the urea cycle enzymes [4].
• The enzyme was partially purified from three different chicken breeds, the White Leghorn B line, the Cochin Bantam breed, and a commercial line named "G," by the following steps: (i) extraction of OTC with Triton X-100 and cetyl-trimethylammonium bromide, (ii) heating, and (iii) salting-out column chromatography [9].
• Individual large yellow yolks (> or = 0.2 g) and a pool of 5 small yellow yolks (< 0.2 g) were collected for determination of ampicillin or OTC content [10].
• It was concluded, however, that dietary spermine was more toxic to chicks than was previously seen for putrescine, that any growth-promoting effects of dietary spermine are small, and that supplements of dietary cysteine or OTC are unlikely to increase these effects by overcoming spermine toxicosis [11].
• In two separate experiments, 16 hens were divided into equal groups (n = 8) and injected only once with either 400 mg/kg ampicillin or 200 mg/kg oxytetracycline (OTC: total hens = 32) approximately 1 h after oviposition [10].

Other interactions of OTC

• OTC was assigned to GGA1; ARG2 to GGA5; CPS1 to GGA7; and CRYD2 to GGA19 [12].

Analytical, diagnostic and therapeutic context of OTC

• An attempt was made to assign five genes, CPS1, OTC, ASS, CRYD2, and ARG2, to chicken chromosomes (GGA) by radiation-hybrid mapping [12].

References