The Genetics of DROSOPHILA SUBOBSCURA Populations. Xiv. Further Data on Linkage Disequilibria

Data coming from one natural population of D. subobscura, that of Crete, are presented in detail and examined for nonrandom associations of genes and gene arrangements. This population and four others previously studied are reanalyzed for the detection of higher than first-order interactions. Only first-order interactions are important and statistically significant, especially those concerning genes and inversions in which these genes are included. The paucity of linkage disequilibria detected is remarkable, and we argue that it does not depend on the methods of study, rather it is genuine. We further argue that most of the disequilibria detected are probably due to mechanisms based on epistatic selection.

Native type II collagen-induced arthritis in the rat. I. Incidence and humoral response to collagen

An acute inflammatory arthritis has been induced in 76% of rats injected intradermally with native bovine type II collagen emulsified in Freund's complete (CFA) or incomplete (ICFA) adjuvant. The arthritis became chronic in 14 out of 31 rats, and ear and tail lesions were noted in some rats. No arthritis was induced by native type I collagen, denatured type II collagen, rabbit IgG, or buffer alone injected intradermally with adjuvant. Using a solid-phase radioimmunoassay for serum antibodies we have shown that IgM and IgG levels to native bovine type II collagen were significantly higher in arthritic than nonarthritic rats. Antiglobulin antibody levels were not raised in arthritic rats. Equivalent antibody levels to native type II collgen were obtained whether this antigen was emulsified in ICFA or CFA. However, native type I collagen produced high antibody levels only when emulsified in CFA, indicating a difference in the immunogenicity of these collagens. These studies suggest that native type II collagen possesses arthritogenic properties in the rat and that humoral immunity may play a role in the induction of this arthritis.

Genetic variability of HLA in the Dariusleut Hutterites. A comparative genetic analysis of the Hutterities, the Amish, and other selected Caucasian populations

There are three endogamous subdivisions of the Hutterite population, a North American religious isolate. These individuals live on communal farms, and residence is strictly patrilocal. We report on the distributions of HLA-A and B alleles and haplotypes in 203 married women from one subdivision--the Dariusleut--in Alberta, Canada. We demonstrate that there is significant linkage disequilbrium among a large fraction of the distinct haplotypes in the Dariusleut Hutterite data; there is a restriction in the number of distinct haplotypes present in the Dariusleut; the Hutterites and the Old Order Amish (Lancaster County, Pennsylvania) are the most genetically distant pair of populations in an ensemble of 11 Caucasian populations; and, finally, the Old Order Amish and the Hutterites are approximately as distant from the Indiana Amish as they are from the eight other Caucasian populations, which are tightly clustered in the space of gene frequencies. These results are consistent with the fact that the Amish and the Hutterites are genetic isolates with small numbers of founders. Certain haplotypes show significant linkage disequilibrium in these as well as in other Caucasian samples. Thus, some of the linkage disequilibrium antedates the formation of these Anabaptist sects.

Migration of human lymphocytes. II. Variation of lymphocyte distribution

Variations in the distribution of 51Cr-labelled human lymphocytes from several donors and from one donor on several occasions have been determined after their injection into carbon-treated mice and reasons for the variation discussed. Natural alteration of the lymphocyte surface (leukaemic lymphocytes) or induced change (trypsin-treatment) reduced lymph node localisation as did treatment with formalin, sodium azide and antilymphocyte globulin. We have concluded that the presence of radioactivity in the lymph nodes is due to the presence of viable, metabolically active lymphocytes with normal surfaces capable of interacting with the endothelium of the post-capillary venules.

Migration of human lymphocytes. I. A model using the mouse as host

The distribution of radioactivity after the intravenous injection of 51Cr-labelled human lymphocytes has been examined in normal mice, irradiated mice, mice treated with anti-platelet antiserum and in mice treated with colloidal carbon. Pre-treatment with carbon and anti-platelet antiserum appears to protect the human lymphocytes from uptake by the host's reticuloendothelial system (RES). Comparison of tissue radioactivity in carbon-treated mice after the injection of viable human lymphocytes with that found after the injection of dead cells and soluble or insoluble cell debris showed that radioactivity recovered in the spleen and lymph nodes is primarily due to the migration of viable lymphocytes into these tissues. Thus the measurement of radioactivity in lymph nodes of carbon-treated mice after the injection of 51Cr-labelled human lymphocytes can be used as a model of these lymphocytes' ability to migrate into the lymph nodes during recirculation and to study factors influencing this migration.

Cancer incidence in a religious isolate of Alberta, Canada, 1953-74

Members of a religious isolate who live in approximately 240 farming colonies in the Canadian prairie provinces and the United States border states were studied. The sect's 6,700 members living in the province of Alberta, Canada, comprise more than 30% of this sect's population of North America. The numbers of their cancer cases ascertained from 1953 to 1974 in Alberta were compared to those expected from Alberta Cancer Registry rates. The overall incidence of registered cases of cancer among the religious isolate's females was significantly less than expected (48 observed, 74.2 expected), and in the males the overall incidence of cancer did not differ from that expected (52 observed, 56.5 expected). Significantly fewer cases of lung cancer than expected were found in males, and significantly fewer cases of carcinoma in situ of the cervix uteri were found in females. Finally, significantly higher incidence of stomach cancer was found in the sect's males. Data on a family with two cases of stomach cancer contributed to this observed excess of stomach cancer.

THE EFFECT OF INTRAGENIC RECOMBINATION ON THE NUMBER OF ALLELES IN A FINITE POPULATION

A two-site infinite allele model is constructed to study the effect of intragenic recombination on the number of neutral alleles and the distribution of their frequencies in a finite population. The results of theory and Monte Carlo simulation of the two-site model demonstrate that intragenic recombination significantly increases the mean and variance of the number of alleles when the rates of mutation and recombination are as large as the reciprocal of the population size. Data from natural populations indicate that this may be a significant process in generating variation and determining its distribution.

On the persistence of random genetic drift

It is demonstrated that standard Brownian motion in the tangent plane at the centroid of frequency space does not well approximate the discrete Wright—Fisher process for more than 2N generations where N is the effective population size. This result is obtained using Wright's concept of negligible mutation rate for the study of systematic evolutionary effects together with Ludwig's notion of the persistence of a dynamical system. This work may be viewed as a mathematical elaboration of a portion of Wright's shifting balance theory of evolution.

DEGRADATIVE STUDIES ON λ-CARRAGEENIN

λ-Carrageenin was subjected to partial acetolysis. Chromatography of the deacetylated products on charcoal led to the isolation of D-galactose, 3-O-α-D-galactopyranosyl-D-galactose (A), and a crystalline trisaccharide (B) tentatively identified as O-α-D-galactopyranosyl-(1 → 3)-O-α-D-galactopyranosyl-(1 → 3)-D-galactose. Periodate oxidation of the polysaccharide indicated the presence of more than one type of linkage in the polymer.