XLαs, a variant of the stimulatory G protein α-subunit (Gsα), can mediate receptor-activated cAMP generation and, thus, mimic the actions of Gsα in transfected cells. However, it remains unknown whether XLαs can act in a similar manner in vivo. We have now generated mice with ectopic transgenic expression of rat XLαs in the renal proximal tubule (rptXLαs mice), where Gsα mediates most actions of PTH. Western blots and quantitative RT-PCR showed that, while Gsα and type-1 PTH receptor levels were unaltered, protein kinase A activity and 25-hydroxyvitamin D 1-α-hydroxylase (Cyp27b1) mRNA levels were significantly higher in renal proximal tubules of rptXLαs mice than wild-type littermates. Immunohistochemical analysis of kidney sections showed that the sodium-phosphate cotransporter type 2a was modestly reduced in brush border membranes of male rptXLαs mice compared to gender-matched controls. Serum calcium, phosphorus, and 1,25 dihydroxyvitamin D were within the normal range, but serum PTH was ∼30% lower in rptXLαs mice than in controls (152 ± 16 vs. 222 ± 41 pg/ml; P < 0.05). After crossing the rptXLαs mice to mice with ablation of maternal Gnas exon 1 (E1(m-/+)), male offspring carrying both the XLαs transgene and maternal Gnas exon 1 ablation (rptXLαs/E1(m-/+)) were significantly less hypocalcemic than gender-matched E1(m-/+) littermates. Both E1(m-/+) and rptXLαs/E1(m-/+) offspring had higher serum PTH than wild-type littermates, but the degree of secondary hyperparathyroidism tended to be lower in rptXLαs/E1(m-/+) mice. Hence, transgenic XLαs expression in the proximal tubule enhanced Gsα-mediated responses, indicating that XLαs can mimic Gsα in vivo.

e Salmonella is a major cause of food-borne disease in many countries. Serotype determination of Salmonella is important for disease assessment, infection control, and epidemiological surveillance. In this study, a microarray system that targets the O antigen-specific genes was developed for simultaneously detecting and identifying all 46 Salmonella O serogroups. Of these, 40 serogroups can be confidently identified, and the remaining 6, in three pairs (serogroups O67 and B, E1 and E4, and A and D1), need to be further distinguished from each other using PCR methods or conventional serotyping methods. The microarray was shown to be highly specific when evaluated against 293 Salmonella strains, 186 Shigella strains, representative Escherichia coli strains, and 10 strains of other bacterial species. The assay correctly identified 288 (98%) of the Salmonella strains. The detection sensitivity was determined to be 50 ng genomic DNA per sample. By testing simulated samples in a tomato background, 2 to 8 CFU per gram inoculated could be detected after enrichment. This newly developed microarray assay is the first molecular protocol that can be used for the comprehensive detection and identification of all 46 Salmonella O serogroups. Compared to the traditional serogrouping method, the microarray provides a reliable, high-throughput, and sensitive approach that can be used for rapid identification of multiple Salmonella O serogroups simultaneously.

We have recently generated a transgenic mouse line (termed hRen-Cre) that expresses Cre-recombinase under the control of a 12.2-kb fragment of the human renin promoter. In the present study, we have crossed hRen-Cre mice with a mouse strain in which exon 1 of the Gnas gene is flanked by loxP sites. Gnas encodes the alpha-subunit of the stimulatory G protein (Gs alpha). Our aim has been to generate a mouse model with locally restricted inactivation of Gs alpha to extend studies of the role of Gs alpha function in vivo. Mice with local Cre-mediated inactivation of Gs alpha (rCre-Gs alpha) are viable and fertile. Their most obvious phenotype consists of marked skeletal malformations of the forelimbs in which computer-tomography scans reveal shortened and fused extremity bones. Extraskeletal ossifications occur in the subcutis and in skeletal muscles associated with the affected long bones. Plasma calcium, phosphate and parathyroid hormone are normal. Skin histology has demonstrated diffuse mineralization and ossification associated with the basal cells of hair follicles. This phenotype in part resembles syndromes in humans associated with loss-of-function of Gs alpha, such as Albright hereditary osteodystrophy and progressive osseous heteroplasia. The renal phenotype of rCre-Gs alpha mice is inconspicuous. Plasma renin concentration, ambient urine osmolarity, and the glomerular filtration rate of rCre-Gs alpha mice do not differ from controls. The absence of measurable functional changes in the renin-angiotensin system indicates insufficient Cre expression in juxtaglomerular granular cells in this strain of mice. Nevertheless, the present report reaffirms the importance of Gs alpha signaling for bone development and the suppression of ectopic ossification.