Showing papers by "National Jewish Health published in 1982"

Nucleotide sequence of Dictyostelium discoideum 5.8S ribosomal ribonucleic acid: evolutionary and secondary structural implications

Abstract: We have determined the nucleotide sequence of the Dictyostelium discoideum 5.8S ribosomal RNA (rRNA). The sequence has relatively low homology with other 5.8S rRNAs and is further distinguished by its lack of modified nucleotides. The homology data indicate that D. discoideum diverged from the mainstream of eukaryotic descent at the earliest branch yet characterized by molecular phylogeny. Taking advantage of the considerable divergence of the D. discoideum 5.8S rRNA sequence from those of other eukaryotes, we have concluded that there is very little phylogenetically conserved, intramolecular secondary structure. This conclusion is discussed in the light of the variety of evidence for a highly ordered structure of 5.8S rRNA in vitro. We also offer comparative evidence in support of a specific model for the base pairing between the 3' end of 5.8S rRNA and the 5' end of eukaryotic 28S rRNA.

Inhibition of specific immune responses by feeding protein antigens. V. Induction of the tolerant state in the absence of specific suppressor T cells.

Abstract: The effect of CY pretreatment on the ability of OVA feeding to induce both tolerance and active suppression was examined in mice. CY-pretreated, OVA fed mice were fully unresponsive in both OVA-specific DTH and antibody responses, but, in contrast to untreated OVA-fed mice, did not transfer suppression to normal recipients via splenic lymphocytes. Restoration of Ts activity in CY-pretreated mice was accomplished by reconstitution with normal T cells before antigen feeding, indicating that the CY effect was at the Ts precursor level. In addition, it was found that certain OVA-specific immune parameters (DTH and splenic PFC responses) in recipient mice were susceptible to suppression by transfer of spleen cells from OVA-fed donors, whereas other measures (antigen-induced T cell proliferation and serum antibody titers) were not. The data suggest that CY-sensitive Ts are not necessary for either induction or maintenance of specific tolerance after OVA feeding.

Enzymatic and chemical structure mapping of mouse 28S ribosomal ribonucleic acid contacts in 5.8S ribosomal ribonucleic acid.

Abstract: Secondary structure mapping experiments using S1 nuclease, RNase T1, and diethyl pyrocarbonate as conformational probes have identified those regions in mouse 5.8S rRNA containing major sites of interaction with 28S rRNA. One site encompasses the 3'-terminal 20 nucleotides and corresponds to the region identified previously as a component of an RNase-resistant 5.8S/28S rRNA junction complex. A second site, located at the 5' terminus, has not been defined precisely but is believed to involve approximately 20--30 nucleotides. The existence of these sites of interaction is supported by comparing sequences of eukaryotic 5.8S and 28S rRNA with those of the prokaryotic 23S rRNA. Evidence for the occurrence of at least three helical regions in the central portion of the mouse 5.8S rRNA molecule is also presented.

A comparison of anti-DNA antibodies from serum and kidney eluates of NZB x NZW F1 mice.

Abstract: The qualitative aspects of anti-DNA antibodies from the serum and those eluted from the kidney of (NZB x NZW)F1 (B/W) mice were evaluated in terms of their class and subclass specificity, avidity and isoelectric profile Serum anti-DNA binding was demonstrated in both the IgG and IgM classes In addition, all subclasses of IgG studied (IgG1, IgG2a, and IgG2b) were shown to bind DNA Avidity measurements indicate that the avidity of isolated serum IgG for 125I labeled DNA decreases with age in B/W mice, while the avidity of isolated serum IgM remains relatively unchanged Anti-DNA antibodies eluted from kidneys were found to be predominantly of the IgG1 and IgG2a subclasses Equal amounts of both high and low avidity antibodies to DNA were demonstrated in the kidney eluates at all ages studied Furthermore, the dissociation curves of these antibodies remained relatively unchanged with age The isoelectric spectrum of serum antibodies to DNA obtained from mice at 4 to 11 months of age demonstrated considerable heterogeneity covering the pH range of 6 to 85 In contrast, the anti-DNA antibodies eluted from the kidney are slightly more basic in nature having isoelectric points between 72 to 90 This study suggests that distinct subpopulations of anti-DNA antibodies exist and that these may play an important role in the development of murine lupus nephritis