Exclusion of epidermal growth factor and high-resolution physical mapping across the Rieger syndrome locus.

We have evaluated the 4q25-4q26 region where the autosomal dominant disorder Rieger syndrome has been previously mapped by linkage. We first excluded epidermal growth factor as a candidate gene by carrying out SSCP analysis of each of its 24 exons using a panel of seven unrelated individuals with Rieger syndrome. No evidence for etiologic mutations was detected in these individuals, although four polymorphic variants were identified, including three that resulted in amino acid changes. We next made use of two apparently balanced translocations, one familial and one sporadic, to identify a narrow physical localization likely to contain the gene or to be involved in regulation of gene function. Somatic cell hybrids were established from individuals with these balanced translocations, and these hybrids were used as a physical mapping resource for, first, preliminary mapping of the translocation breakpoints using known sequence tagged sites from chromosome 4 and then, after creating YAC and cosmids contigs encompassing the region, for fine mapping of those breakpoints. A cosmid contig spanning these breakpoints was identified and localized the gene to within approximately 150 kb of D4S193 on chromosome 4. The interval between the two independent translocations is approximately 50 kb in length and provides a powerful resource for gene identification.     

Caprine blood groups. 1. The B system

Twelve of 24 monospecific caprine reagents produced by absorption of alloimmune antisera identified a complex blood group system of goats which was designated B, based on the results of a small comparison test with ovine reagents. The frequencies of the 12 B factors differed significantly among the Australian Angora, Texan Angora, Cashmere, and Dairy goat breeds. Three of the antigens detected by the reagents were shown to be related as linear subtypes, designated Ba₁, Ba₂, and Ba₃, and inherited as alleles. The segregations of B factors in 80 sire groups involving 1086 offspring demonstrated that groups of B factors (phenogroups) segregated as products of allelic genes. This work was supported by a grant from the Australian Stud Book, Alison Road, Randwick, New South Wales 2031, Australia.     

Use of tumour marker immunoreactivity to identify primary site of metastatic cancer.

OBJECTIVES--To determine whether variations in the expression of tumour related antigens can predict the origin of tumours. DESIGN--Immunohistological study of tumour marker expression in primary adenocarcinomas and respective metastatic deposits. Antibodies to the following tumour markers were used: polymorphic epithelial mucin (NCRC-11 and SM3), carcinoembryonic antigen, carcinoembryonic antigen with non-specific antigen co-specificity, CA125, CA19.9, prostate specific antigens, and thyroglobulin. SETTING--Histopathology department of teaching hospital. SUBJECTS--100 pathology sections of metastatic adenocarcinoma and their related primary tumours. MAIN OUTCOME MEASURES--Concordance of reactivity between primary and metastatic tumours. Reactivity profiles of tumour sites. RESULTS--The correct primary site of origin was predicted in 70% (33/47) of tumours in men and 54% (27/43) tumours in women with antibodies SM3, 288, CA19.9, CA125, and PSA (men only). Specificities ranged from 68% for breast tumour to 98% for prostate tumour. CONCLUSION--Use of tumour markers in patients presenting with metastatic adenocarcinoma of unknown origin can help localise the probable primary sites and reduce the need for extensive and expensive imaging techniques.     

Bacterial adaptation to low-nutrient conditions as studied with algal extracellular products

Kinetic analyses indicate that members of natural bacterial populations from 2 marine environments near Woods Hole, MA, possess enzyme-mediated transport systems which permit utilization of¹⁴C-labeled extracellular organic C (¹⁴C-EOC) prepared from the algae,Skeletonema costatum, Thalassiosira pseudonana, andDunaliella tertiolecta, and supplied over a concentration range of 15–150C·liter^–1. It is shown that previous exposure of the bacteria to the EOC from these algae cannot explain the linear kinetic patterns obtained. Therefore, the ability to utilize algal EOC at low concentrations is a general feature of metabolically active bacterial populations. Further, as the native bacteria do not restrict this ability to a specific EOC pool, the results are consistent with the hypothesis that bacteria adapted to low nutrient environments possess uptake systems of high substrate affinity and low substrate specificity. Elevation of substrate levels with as little as 10 mg·1^–1 peptone is shown to favor development of a bacterial population that lacks these adaptations. Standard enrichment techniques typically result in the isolation of bacteria that are poor models for evaluating the ecology of native microbiota.Contribution No. 1523 from the University of Maryland Center for Environmental and Estuarine Studies.     

Effect of dextran-charcoal treatment on the dissociation kinetics of glucocorticoid-receptor complexes: possible involvement of lipid

Dissociation kinetics were determined at 0 degrees C for molybdate-stabilized glucocorticoid-receptor complexes in rat thymus cytosol. Exposure of complexes to dextran-coated charcoal had no effect on their chromatographic properties or transformation status, but dissociation rates measured after charcoal treatment were significantly lower than those determined by displacement with excess competing steroid. The dissociation rate of the [2,4,6,7-3H]prednisolone-receptor complex was similarly modified by chromatography on Lipidex 1000, but not by chromatography on Sephadex G-25 or G-75. It is concluded that treatment of glucocorticoid-receptor complexes with dextran-charcoal or Lipidex 1000 brings about a change in dissociation rate as a consequence of the removal of a lipid component from the complex.     

Characterization of liver cholic acid coenzyme A ligase activity. Evidence that separate microsomal enzymes are responsible for cholic acid and fatty acid activation.

Investigations on the cholic acid CoA ligase activity of rat liver microsomes were made possible by the development of a rapid, sensitive radiochemical assay based on the conversion of [3H]choloyl-CoA. More than 70% of the rat liver cholic acid CoA ligase activity was associated with the microsomal subcellular fraction. The dependencies of cholic acid CoA ligase activity on pH, ATP, CoA, Triton WR-1339, acetone, ethanol, magnesium, and salts were investigated. The hypothesis that the long chain fatty acid CoA ligase activity and the cholic acid CoA ligase activity are catalyzed by a single microsomal enzyme was investigated. The ATP, CoA, and cholic (palmitic) acid kinetics neither supported nor negated the hypothesis. Cholic acid was not an inhibitor of the fatty acid CoA ligase and palmitic acid was not a competitive inhibitor of the cholic acid CoA ligase. The cholic acid CoA ligase activity utilized dATP as a substrate more effectively than did the fatty acid CoA ligase activity. The cholic acid and fatty acid CoA ligase activities appeared to have different pH dependencies, differed in thermolability at 41 degrees, and were differentially inactivated by phospholipase C. Moreover, fatty acid CoA ligase activity was present in microsomal fractions from all rat organs tested while cholic acid CoA ligase activity was detected only in liver microsomes. The data suggest that separate microsomal enzymes are responsible for the cholic acid and the fatty acid CoA ligase activities in liver.     

Nearest-neighbor and next-nearest-neighbor effects in the proton NMR spectra of the oligoribonucleotides ApGpX and CpApX

The variable-temperature proton nmr spectra of the oligoribonucleotides in the series CpApX and the series ApGpX, X = A, G, C, U, together with the parent dimers CpA and ApG have been measured. A complete analysis of all the nonexchangeable base proton resonances and ribose H-1′ proton resonances was made. The presence of trends in the shielding abilities of the various bases at both the nearest-neighbor and next-nearest-neighbor positions were identified. The observed shieldings could be used to predict the chemical shifts of protons in related systems. Based on the empirical results from ribodinucleoside monophosphates, the temperature-dependent behavior of the J_1′2′ coupling constants of the triribonucleotides suggested that the compounds in the CpApX series stacked from the 5′-end to the 3′-end, while those in the ApGpX series stacked from the 3′-end to the 5′-end.