Immunisation against heterologous type II collagen induces arthritis in mice

The induction of polyarthritis in rats by intradermal immunisation with homologous or heterologous type II collagen incomplete or incomplete Freund's adjuvant was reported recently by Trentham et al. We have now produced a similar disease in certain strains of mice.     

Expression of N-myc in teratocarcinoma stem cells and mouse embryos

The N-myc gene, which is distantly related to the proto-oncogene c-myc, was first detected as an amplified sequence in human neuroblastoma cell lines and tumours. It has since been revealed that there is up to a 300-fold amplification of N-myc DNA in almost 50% of advanced metastatic human neuroblastomas, whereas amplification is not detected in less advanced tumours that have a better prognosis (ref.3 and M.S., unpublished data). Although expression of N-myc is detectable in all neuroblastoma cell lines and tumours examined, its level is greatly enhanced when the N-myc gene is amplified. Recently, it has been shown that on co-transfection with the c-Ha-ras (EJ) gene, N-myc can induce the malignant transformation of rat embryo fibroblasts. Taken together, these data imply a function for N-myc in the development and/or progression of human neuroblastomas. Surveys indicate that N-myc also may be amplified and/or expressed in two other types of human tumours and cell lines derived from them: retinoblastomas and small cell lung cancers. Here, we report that N-myc is expressed at high levels in mouse and human teratocarcinoma stem cells, thus identifying another tumour cell type that expresses the N-myc gene. In addition, we found that N-myc is abundantly expressed in mouse embryos at mid-gestation and that its expression appears to decrease as the embryo approaches term. In the adult mouse, N-myc is expressed at an approximately fivefold lower level in the brain than in teratocarcinoma stem cells and embryos, and at even lower levels in the adult testis and kidney. Our data represent the first demonstration of expression of the N-myc gene in normal cells, and suggest that N-myc may be involved in mammalian embryogenesis.     

Significance of enamel thickness in hominoid evolution

Enamel thickness has assumed unique importance in the debate about the hominid status of Ramapithecus, despite the fact that there is little agreement about the meaning of 'thick enamel' or the significance of enamel thickness for hominoid taxonomy. My aim here is to evaluate the usefulness of enamel thickness and microstructure as characteristics for determining the relationships of the later Miocene hominoids, based both on a quantitative study of enamel thickness in extant hominoids and four species of later Miocene Sivapithecus (including 'Ramapithecus') and on scanning electron microscope analysis of enamel microstructure. Four categories of enamel thickness are defined metrically here and have been related to enamel microstructure and developmental rates. Thin fast-formed (pattern 3) enamel represents the ancestral condition in hominoids; it increased developmentally to thick pattern 3 enamel in the great ape and human clade and that condition is primitively retained in Homo and in the fossil hominoid Sivapithecus (including 'Ramapithecus'). Enamel thickness has been secondarily reduced in the African apes and also, although at a different rate and extent, in the orang-utan. Thick enamel, previously the most important characteristic in arguments about the earliest hominid, does not therefore identify a hominid.     

Comparative chromosome mapping of a conserved homoeo box region in mouse and human

Specific genes are assumed to regulate pattern formation in the mammalian embryo, but as yet none has been identified unequivocally. It is possible that such genes in mammals may be identified by virtue of a conserved coding sequence, because many of the Drosophila melanogaster homoeotic and segmentation genes, which have crucial roles in the regulation of segmental pattern formation during embryonic development, contain a 180-base pair (bp) DNA sequence, the homoeo box, and that sequences homologous to the Drosophila homoeo box are also present in 6-10 copies in higher animals, including mammals. Although the assumption that the homoeo box identifies genes responsible for pattern formation in mammals remains to be validated, it is a particularly attractive hypothesis given the strong conservation of homoeo boxes over vast evolutionary distances. Here we report the localization of a human homoeo box region, previously cloned and shown to contain two homoeo boxes within a sequence of 5-kilobases (kb), to the long arm of chromosome 17. We show that two single-copy homoeo box-flanking probes derived from this region strongly hybridize to single-copy restriction fragments in mouse genomic DNA and that these conserved homoeo box-flanking sequences map to mouse chromosome 11. This may be significant as several genes that map to chromosome 17 in human also map to chromosome 11 in the mouse, implying that a segment of mouse chromosome 11 is homologous to a region of human chromosome 17. Taken together, these data suggest that the homoeo box region detected with our probes is highly conserved in human and mouse.     

Demonstration of high affinity binding of estradiol in adrenal cortex tissue]

Evidence is presented demonstrating the presence of a high affinity (Ka10(8)M-1), limited capacity (3-4 pmoles/mg protein) estradiol binder in the soluble fraction of the Bovine, Rat and Human adrenal cortex. The binding appears specific to the estrogen structure whereas C19 and C21 steroids do not bind. Upon sucrose density gradient centrifugation, the estradiol binder sedimented at 9 S at low ionic strength and was shifted to 4.5 S in the presence of 0.5 M KCl. This demonstration of a receptor-like moiety for estradiol in the adrenal cortex lends biochemical support to previous observations suggesting that adrenal cortex functions may be modulated by a direct effect of gonadal steroid hormones.