Robert W. Chandler

Estimation of nuclear DNA content by flow cytometry in fishes of the genus Xiphophorus

1. By use of flow cytometry we measured nuclear DNA content in cells from 16 stocks representing 9 species of the genus Xiphophorus. 2. Significant differences were detected between certain stocks and species with respect to DNA content. 3. Male-female differences were apparent in 5 of 7 stocks in which males and females were studied. 4. Estimation of nuclear DNA content is of potential significance in connection with the genetics of sex determination and the study of taxonomic relationships.

Stability of genome size among stocks of the channel catfish

Abstract Nuclear DNA content of erythrocytes from male and female channel catfish ( Ictalurus punctatus ) was determined by flow cytometry. Fourteen stocks of catfish were studied ( n =115), including domesticated and wild fish, fish from sex-reversed populations and those produced by gynogenesis. Mean DNA content was 1.977±0.010 (SD) pg DNA per cell, and mean within-stock variation was 1.28%. The stocks had an average difference of 0.19% from the species mean; no significant differences in DNA content were detected among the stocks or between males and females. The intraspecific variation among the channel catfish stocks examined is lower than that reported for other fish species. This may reflect artificial stabilization of genome size by human intervention, or alternatively, evolutionary conservatism within the genome of the channel catfish.

Chicken Erythrocytes as an Internal Reference for Analysis of DNA Content by Flow Cytometry in Grass Carp

Abstract We estimated the nuclear DNA content of unfixed erythrocytes of the grass carp Ctenopharyngodon idella by fluorescence flow cytometry using propidium iodide as a fluorochrome. Frozen erythrocytes from the domestic chicken Gallus gallus were thawed and used as an internal reference for simultaneous analysis with grass carp samples. The nuclear DNA content of erythrocytes from diploid grass carp (mean ± SD) was 2.00 ± 0.01 pg/cell, whereas triploids possessed 2.97 ± 0.03 pg/cell. Variations in the nuclear DNA content ofdifferent chickens were standardized in relation to the DNA content of fresh human leukocytes (7.00 pg/cell). The value for DNA content of the chicken erythrocytes (around 2.5 pg/cell) occupied a position intermediate between the two grass carp values, and thus provided a clear reference for discrimination between diploids and triploids.

HLA-B27 antigen and rheumatoid factor negative (seronegative) peripheral arthritis. Studies in younger patients with early-diagnosed arthritis.

Abstract HLA-B27, a valuable genetic marker for spondyloarthritis, offers a means for improved definition of rheumatoid factor negative (seronegative) peripheral arthritis. A group of 109 early-diagnosed patients with seronegative peripheral arthritis, who were under 45 years of age at the onset of disease, were studied prospectively. HLA-B27 prevalence was 23 per cent in the total group (25 of 109) and in those initially diagnosed as having rheumatoid arthritis (seven of 30) as compared to 7 per cent in normal subjects (six of 91). The age at onset of B27-associated arthritis was significantly concentrated in those 12 to 24 years of age (p

Inability to Detect Fetal Metaphases in Flow-Sorted Lymphocyte Cultures Based on Maternal-Fetal HLA Differences

Separation of fetal cells from maternal blood could provide a means for prenatal diagnosis that would not endanger the fetus. In this pursuit, we attempted cytogenetic analysis of candidate fetal cells flow sorted on the basis of parental HLA disparity. Metaphases showing 46,XY or aneuploidy and concordant with prenatal diagnostic studies (i.e., amniocentesis, chorionic villus sampling) would presumably be fetal in origin. Blood samples were obtained from 78 pregnant women and their partners. Among 18 HLA informative cases in which metaphases were recovered, 15 involved fetuses that were 46,XY or aneuploid. From these 15 cases, 2,483 metaphases were analyzed. All metaphases were 46,XX. Cytogenetic analysis of flow-sorted fetal cells thus probably will need to emphasize not metaphase analysis but in situ hybridization with chromosome-specific probes.

Relative deoxyribonucleic acid content of interphase leukocytes by flow cytometry: A method for indirect diagnosis of chromosomal abnormalities with potential for prenatal diagnosis

A major goal of prenatal cytogenetic analysis is the development of minimally invasive techniques by which all pregnancies may be screened. That nucleated fetal cells exist in the maternal circulation raises the possibility that their cytogenetic status could be determined. However, these cells may not respond to commonly used mitogens. Thus it will probably be necessary to develop methods to analyze nondividing (interphase) cells. We therefore evaluated the use of flow cytometry as a means of determining whether the relative deoxyribonucleic acid content of G0-G1 leukocytes (expressed as the deoxyribonucleic acid index) could be used to verify aneuploidy or other chromosomal abnormalities. Our findings indicate this is indeed possible. We determined that the mean deoxyribonucleic acid index of circulating leukocytes from normal adult men (n = 15) was significantly different from that of leukocytes from normal adult women (n = 15). Similar results were obtained in leukocytes from umbilical cord blood of normal male neonates (n = 15) and normal female neonates (n = 15). Most importantly, values for leukocytes from each of 13 aneuploid individuals fell outside the range of values for leukocytes from normal adults of the same sex.

Use of flow cytometry to screen for the effects of environmental mutagens: Baseline DNA values in cottonmouth snakes

Since the late 1970s flow cytometry has been accepted as a fast and accurate technique for the quantification of nuclear DNA content (Deaven 1982). However, use of the technology has typically been confined to clinical settings due to the high cost of the instrumentation and the requirement for trained personnel. Flow cytometry recently has been applied to the study of genetic damage in wild populations. McBee and Bickham (1988) detected DNA damage in wild rodents inhabiting a dumpsite contaminated with petrochemicals, and Bickham et al. (1988) detected DNA aneuploidy in turtles found in seepage basins contaminated with radiation. Given these few studies, there is a need to establish a data base for the application of flow cytometry to environmental screening.