Chromosomal localization of the major histocompatibility complex (MHC) in the rhesus monkey and chimpanzee by fluorescence in situ hybridization.

Genes for the major histocompatibility complex (MHC) were localized by fluorescence in situ hybridization to the long arm of rhesus monkey chromosome 5. This localization contradicts previous reports, based on genetic investigation of somatic cell hybrids, that placed the MHC on chromosome 2 of this species. In the chimpanzee, the MHC loci were localized to 5p21.3, corresponding precisely to their location on human chromosome 6p21.3.     

Acquisition of an additional internal cleavage site differentially affects the ability of pseudorabies virus to multiply in different host cells.

The translocation of the 325 leftmost bp of the genome of pseudorabies virus (PrV) to the internal junction between the L and S components confers upon the virus a growth advantage relative to wild-type PrV in chicken embryo fibroblasts (CEFs) and chickens and a growth disadvantage in rabbit kidney (RK) cells and mice. To clarify the molecular basis for the species-specific growth characteristics of the translocation mutants, we have compared several parameters of the virus growth cycle in CEFs and RK cells infected with wild-type PrV and with translocation mutants. The salient findings are as follows. (i) The synthesis of early-late and late proteins is not as effective in CEFs as it is in RK cells, and these proteins, in particular, the major capsid proteins, accumulate less abundantly in CEFs than in RK cells. (ii) Cleavage of concatemeric DNA to genome-size molecules is also not as effective in CEFs as it is in RK cells. (iii) The internal junction present in translocation mutants is a functional cleavage site. (iv) In RK cells, translocation mutants are hypercleaved and a significant proportion of the total viral DNA is cleaved into subgenomic fragments. (v) In CEFs infected with translocation mutants, subgenomic fragments also accumulate but most of the viral DNA remains in concatemeric form. A model which postulates that the cell-specific growth advantage or disadvantage of the translocation mutants is related to the presence of a second cleavage site within their genomes and is affected by the efficiency of cleavage of concatemeric DNA in particular infected cell types is presented. The significance of these findings as they relate to the evolution of herpesviruses with class 2- and class 3-like genomes is discussed.     

Determination of amphetamine in human urine by dansyl derivatization and high-performance liquid chromatography with fluorescence detection

A simple procedure for the determination of amphetamine in urine with minimal sample preparation is described. This method involves direct addition of human urine to an acetone-dansyl chloride solution for simultaneous deproteinization and fluorescence derivatization. The derivatized amphetamine is then measured by HPLC with fluorescence detection. It eliminates the extraction procedures often required by other HPLC or GC methods. The effects of pH, temperature and reaction time on the derivatization reaction were investigated. The stability of amphetamine-dansyl chloride in different storage conditions was examined. The detection limit and linearity associated with this assay are discussed.     

An immuno-electron-microscopic study of human thymic B cells

Thymic B cells are a constituent of normal human thymic medulla. They are supposed to play a role in T cell maturation. Thymic B cells have been characterized morphologically and immunohistochemically at the light-microscopic level. Their ultrastructural appearance in vivo has not been demonstrated. Six normal infantile thymi were immunolabelled with the pan-B cell marker CD20 using a pre-embedding technique and viewed at the electron-microscopic level. Cells expressing CD20 had long cytoplasmic processes. They were all ”asteroid” in shape and in close contact with thymocytes. Also, their long cytoplasmic processes intermingled with cytoplasmic processes of cells that were presumed to be interdigitating reticulum cells (IDC) based on morphological criteria. Thymic B cells may act in concert with IDC during T cell maturation. Received: 20 October 1995 / Accepted: 10 January 1996     

A search for quantitative trait loci for ovulation rate in cattle

Seventy-seven polymorphic microsatellites were analysed in offspring of three elite sires that were part of the foundation of an experimental population selected for twinning rate at the US Meat Animal Research Center, Clay Center, Nebraska. All females were assessed for ovulation rate by rectal palpation of corpora lutea over 8–10 consecutive oestrous cycles from approximately 12 to 18 months of age, and associations between ovulation rate and sire allele were examined in each of the three sire groups. A preliminary analysis was performed using selectively genotyped daughters of each sire. Markers found significant or approaching significance were also genotyped in all daughters, sons and granddaughters of these sires. A test of marker associations limited to the granddaughter data provided an independent confirmation of marker effect and significance relative to the initial test with daughter data. Putative ovulation rate quantitative trait loci were detected on chromosomes 7 and 23. Marker UWCA20 on chromosome 7 was associated with an effect in excess of one phenotypic standard deviation and accounted for approximately 10% of phenotypic variation ovulation rate. Marker CYP21 (steroid 21-hydroxylase) on chromosome 23 was associated with an effect of slightly less than half a phenotypic standard deviation and accounted for approximately 4% of phenotypic variation.     

Linkage between the loci for serum albumin and vitamin D binding protein (GC) in the Japanese quail

Vitamin D binding protein ( GC ) and serum protease inhibitor ( PI ) have been added to genetic markers in the Japanese quail. Both loci were controlled by autosomal codominant alleles named GC^A, GC^B and PI^A, PI^B, PI^C, respectively. Close linkage between the loci for serum albumin ( ALB ) and GC protein is reported. Two recombinants were observed in 145 informative offspring of 14 families. The recombination frequency between the loci was estimated as 0.014±0.006. Thus, GC was assigned to linkage group II in the Japanese quail. No signs of linkage were observed among the loci for the ALB-GC complex, PI. serum prealbumin 2 ( PA2 ), phosphoglucose isomerase ( PG1 ), 6-phosphogluconate dehydrogenase ( PGD ) and esterase-D ( ESD ).