This complete and fully assembled genome sequence of Mycoplasma bovis type strain PG45 is the first available for this species and offers a framework for comparison with additional pathogenic isolates. The single circular chromosome of 1,003,404 bp reveals multiple gene sets and mechanisms involved in variable expression of surface antigens and the incursion of numerous and assorted mobile elements, despite its reduced size.Mycoplasma bovis is a major bacterial pathogen causing widespread respiratory disease, mastitis, and arthritis in cattle (1,5). A member of the wall-less Mollicutes class, it displays marked genome reduction and a parasitic lifestyle lacking key metabolic pathways. It is refractory to several classes of antibiotics, and bacterins for immunological control need continued improvement. Adaptive variation through high-frequency phase variation of surface lipoproteins (LPs) is known to occur through site-specific recombination among the family of vsp genes (8, 9). Horizontal gene transfer (HGT) of some gene sets (13), numerous classes of insertion-like sequences (IS elements) (7), and integrative conjugative elements (ICE) (10) are reported in M. bovis or its close phylogenetic relative M. agalactiae, a pathogenic species infecting caprine hosts. Complete sequencing and assembly of the M. bovis genome were pursued to better reveal its content and dynamics relevant to disease control measures. In order to minimize rearrangements or mutational heterogeneity in the genome sample, template DNA was prepared from an axenic culture propagated from a single colony isolate (MU clone A2, phenotype VspO ON; available under proper regulatory controls). The genome, comprising a single circular chromosome, was sequenced to closure using the Sanger random shotgun method (3), yielding approximately 8-fold sequence coverage.The genome has a 29.3% GϩC content, contains 826 open reading frames (ORFs; including 61 pseudogenes) with an 89% coding density, and has limited sets of 6 rRNA and 34 tRNA genes, characteristic of Mollicutes. A large set of 54 IS elements (comprising seven distinct categories) (7) is scattered throughout the chromosome. Two ICE occur. ICEB-1 (23,271 bp, 18 ORFs) is a counterpart to ICEA, an element similarly positioned in the highly syntenous M. agalactiae PG2 genome (11), thereby suggesting that integration occurred in a common ancestor prior to speciation. ICEB-2 (37,408 bp, 33 ORFs) is inserted into an IS element that is implicated in the inversion of a 483-kb region of the M. bovis PG45 chromosome, relative to M. agalactiae PG2. The potential for genome plasticity among strains of M. bovis is underscored by these features.The predicted LP surface proteome of M. bovis type strain PG45 was determined using established algorithms (2, 6) and an extended search pattern, {DERK}(6)- [LIVMFWSTAG](2)-[LIVMFYSTAGCQ]-[AGSTKRQ]-C, to include atypical residues (underlined) at the Ϫ1 position of the lipobox, previously demonstrated in this lineage of Mollicutes (4, 9). Of 96 predicted LPs, 40 contain at...

We are now showing that cultured human melanoma cells can synthesize steroids such as corticosterone from progesterone or deoxycorticosterone. Corticosterone production is strongly responsive to deoxycorticosterone substrate addition (12-fold increase), but unresponsive to the adrenal stimulating factors ACTH and angiotensin II. This is the first demonstration that skin cells (malignant melanocytes) have the capability to synthesize 11-deoxycorticosterone, corticosterone, and 18-hydroxydeoxycorticosterone.z 1999 Federation of European Biochemical Societies.

Endothelins are a group of potent vasoconstrictors whose structure was deduced from genomic DNA. ET-1 was first isolated from culture supernatants from porcine endothelial cells and ET-3 was identified from a rat DNA library. We report on the binding of '25l-ET-1 to zona glomerulosa celis in culture and on its ability to stimulate aldosterone secretion. Cultured calf adrenal zona glomerulosa cells have saturable, high affinity [Kd = 1.00±0.17 X 10`s M (SEM)j receptors which bind ET-1 in a temperature and time dependent manner. Binding was specific and angiotensin II, vasopressin, ANP, BNP, apamin, calcium channel agonists or antagonists did not interact with the receptor. ET-3 displaced 125I-ET-1 from the receptor with a relative potency of 0.39±0.1% (SEM) that of ET-1.ET-1 incubated with cultured glomerulosa cells stimulated aldosterone secretion in a dose dependent manner but it was less potent than angiotensin II. ET-3 had < 1% the relative potency of ET-1 stimulating aldosterone secretion. This data suggest that ET-1 is an independent stimulator of aldosterone secretion and we are speculating that it might be important in those situations, like in malignant hypertension, where endothelial damage might result in increased ET-1 production.

Objective. The U1-70-kd RNP is a prominent target of autoimmunity in connective tissue diseases. In this study, we explored whether its endogenous ligand, U1 RNA, mediates a proimmune signal and may be immunogenic.Methods. We assayed the proliferation of control and MyD88-knockout splenocytes in response to in vitro-synthesized U1 RNA, and measured interleukin-6 (IL-6) and IL-8 secretion induced by U1 RNA in a human cell line competent for signaling through Tolllike receptor 3 (TLR-3) and TLR-5. Conclusion. U1 RNA is capable of inducing manifestations consistent with TLR-3 activation. The ability of U1 RNA (which has a substantial double-stranded secondary structure) to activate TLR-3 may contribute to the immunogenicity of the U1-70-kd autoantigen.Stimulation of innate immunity by native RNA molecules with a double-stranded secondary structure may help explain the high prevalence of autoimmunity to RNA binding proteins.