Genetic basis of IgE responsiveness: relevance to the atopic diseases

Genetic analysis of 170 subjects in 11 extended Amish families revealed evidence for linkage of five markers in chromosome 5q31.1 with a gene controlling total serum IgE levels. No linkage was found between these markers and specific IgE antibody levels. Analysis of total IgE within a subset of 128 IgE-antibody-negative sib pairs confirmed evidence for linkage to 5q31.1, especially IL4 (p = 4 × 10--6). These and other data suggest that IL4 or a nearby gene regulates IgE production in a non-antigen-specific (noncognate) fashion and provide evidence for a possible link between asthma and the IL4 gene

Zonadhesin D3-Polypeptides Vary among Species but Are Similar in Equus Species Capable of Interbreeding1

Zonadhesin is a rapidly evolving protein in the sperm acrosome that confers species specificity to sperm-zona pellucida adhesion. Though structural variation in zonadhesin likely contributes to its species-specific function, the protein has not previously been characterized in organisms capable of interbreeding. Here we compared properties of zonadhesin in several animals, including the horse (Equus caballus), donkey (E. asinus), and Grevy's zebra (E. grevyi) to determine if variation in zonadhesin correlates with ability of gametes to cross-fertilize. Zonadhesin localized to the apical acrosomes of spermatozoa from all three Equus species, similar to its localization in other animals. Likewise, in horse and donkey testis, zonadhesin was detected only in germ cells, first in the acrosomal granule of round spermatids and then in the developing acrosomes of elongating spermatids. Among non-Equus species, D3-domain polypeptides of mature, processed zonadhesin varied markedly in size and detergent solubility. However, zonadhesin D3-domain polypeptides in horse, donkey, and zebra spermatozoa exhibited identical electrophoretic mobility and detergent solubility. Equus zonadhesin D3-polypeptides (p110/p80 doublet) were most similar in size to porcine and bovine zonadhesin D3-polypeptides (p105). Sequence comparisons revealed that the horse zonadhesin precursor's domain content and arrangement are similar to those of zonadhesin from other large animals. Partial sequences of horse and donkey zonadhesin were much more similar to each other (>99% identity) than they were to orthologous sequences of human, pig, rabbit, and mouse zonadhesin (52%–72% identity). We conclude that conservation of zonadhesin D3-polypeptide properties correlates with ability of Equus species to interbreed