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E Neufeld

Publications and source records attributed to E Neufeld.

At least 37 records · Page 2Linked to original sources
PubMed1983

The origin of multiple sex chromosomes in the gerbil Gerbillus gerbillus (Rodentia: Gerbillinae).

The sex chromosomes of the partly sympatric species of gerbils Gerbillus pyramidum and G. gerbillus (Mammalia: Gerbillinae) were investigated by a variety of light- and electron-microscope methods, including DNA replication banding and synaptonemal complex (SC) techniques. The sex-chromosome mechanism of G. pyramidum is of the maleXY:femaleXX type, whereas that of G. gerbillus is of the less common maleXY1Y2:femaleXX system. The results include the demonstration that the X chromosomes of both species are compound. One segment is added to the X chromosome of G. pyramidum, leading to an increase in length from the standard 5% to approximately 7.3%, whereas two different extra segments increase the length of the X chromosome of G. gerbillus to approximately 11% of the length of the haploid genome. In both cases the extra material is autosomal and is also represented in the respective Y chromosomes. Classifying heterochromatin by the variation in staining quality was helpful in elucidating the possible origin of the different chromosome segments, including the pericentromeric regions. Observations on meiotic chromosome pairing and chiasma formation have confirmed the homologies established by band comparisons. The occurrence of chiasmata between the sex chromosomes supports the autosomal origin of the pairing segments. These and other findings have been interpreted in the framework of a multistep evolutionary model. This sequence starts from a hypothetical pair of sex chromosomes, the X element of which amounts to 5% of the haploid genome, and leads through three translocations involving two pairs of autosomes and one pericentric inversion to the most complex situation of this series, manifested in G. gerbillus. The adaptive value, if any, of autosome incorporation into the sex chromosomes repeatedly occurring here is unknown. It is, however, a remarkable fact that in one species, G. gerbillus, the complex sex-chromosome constitution is conserved over vast geographic distances, and in the other, G. pyramidum, the compound X and Y chromosomes withstand change in the face of extreme autosome restructuring.

Animals↗
PubMed1976

Iduronate sulfatase activity in serum, lymphocytes, and fibroblasts--simplified diagnosis of the Hunter syndrome.

A previously described assay for iduronate sulfatase has been adapted for use with serum, lymphocytes, and fibroblasts. The assay also gives a rough measure of iduronidase activity. We have evaluated the procedure for the diagnosis of the Hunter syndrome, for the detection of Hunter heterozygotes, and for the diagnosis of certain other disorders (mucolipidoses II and III and mucopolysaccharidosis I). Hunter patients had 1-2% normal iduronate sulfatase activity in the three sources tested. The serum assay is undoubtedly the method of choice to establish the diagnosis of the Hunter syndrome. Less that 1 ml serum and 3-4 days are required to complete the procedure. Serum could not be used for the detection of iduronidase deficiency diseases, but these could easily be recognized in lymphocyte and fibroblast preparations. The iduronate sulfatase activity of sera from patients with mucolipidoses II and III was elevated 20-fold, but their parents had a normal level of the enzyme. In fibroblasts of patients with mucolipidoses II and III, both iduronate sulfatase and iduronidase activities were markedly decreased. Serum assays were not informative about the Hunter heterozygote status. However, the mean activity in lymphocytes from mothers of Hunter patients was about half of the mean normal activity. A number of obligate heterozygotes had iduronate sulfatase activity so low that they were identifiable as carriers; others, unfortunately, had a clearly normal level. The possibility of carrier detection by the lymphocyte assay needs further development.

Female↗