Toad atrial natriuretic peptide : cDNA cloning and functional analysis in isolated perfused kidneys

Complementary DNA (cDNA) encoding Bufo marinus (toad) preproatrial natriuretic peptide (preproANP) was isolated by reverse-transcription polymerase chain reaction. Sequence analysis of toad preproANP cDNA revealed an open reading frame of 150 amino acid residues, which shared 72% and 66% identity with Rana catesbeiana and Xenopus laevis preproANP, respectively. The deduced amino acid sequence of toad ANP that corresponded to ANP 1&ndash;24 of R. catesbeiana and Rana ridibunda was identical, but it differed by four residues from that of X. laevis. ANP mRNA transcripts were also shown to be expressed in the toad kidney. Subsequently, the effect of frog ANP (1&ndash;24) on renal function in toad was examined using a perfused kidney preparation. The arterial infusion of frog ANP caused a dose-dependent decrease in the arterial perfusion pressure that was associated with an increase in the glomerular filtration rate (GFR) and a renal natriuresis and diuresis. The renal natriuresis and diuresis resulted predominantly from an increased GFR rather than from direct tubular effects. This study demonstrates that ANP can regulate renal function, which suggests it may be involved in overall fluid volume regulation.<br /

Overcoming the false-minima problem in direct methods: Structure determination of the packaging enzyme P4 from bacteriophage φ13

The problems encountered during the phasing and structure determination of the packaging enzyme P4 from bacteriophage φ13 using the anomalous signal from selenium in a single-wavelength anomalous dispersion experiment (SAD) are described. The oligomeric state of P4 in the virus is a hexamer (with sixfold rotational symmetry) and it crystallizes in space group C2, with four hexamers in the crystallographic asymmetric unit. Current state-of-the-art ab initio phasing software yielded solutions consisting of 96 atoms arranged as sixfold symmetric clusters of Se atoms. However, although these solutions showed high correlation coefficients indicative that the substructure had been solved, the resulting phases produced uninterpretable electron-density maps. Only after further analysis were correct solutions found (also of 96 atoms), leading to the eventual identification of the positions of 120 Se atoms. Here, it is demonstrated how the difficulties in finding a correct phase solution arise from an intricate false-minima problem. © 2005 International Union of Crystallography - all rights reserved

Global Journalist: Reporters on the Iraq War

This Global Journalist show from April 3, 2003 features several journalists discussing how they view the recent progress of the American and British forces in the Iraq war. Jennifer Hamarneh, at the time the editor-in-chief of The Jordan Times, talks about hearing from Matthew McAllester, a reporter who was held captive in Iraq for over a week. Host: Stuart Loory. Guests: Jennifer Hamarneh (Jordan), Reinhard Meier (Switzerland), Edward Lucas (London), Dan Sneider (California). Producers: Sara Andrea Fajardo, Augustine Pang. Director: Pat Akers

Co-expression and promoter content analyses assign a role in biotic and abiotic stress responses to plant natriuretic peptides

<p>Abstract</p> <p>Background</p> <p>Plant natriuretic peptides (PNPs) are a class of systemically mobile molecules distantly related to expansins. While several physiological responses to PNPs have been reported, their biological role has remained elusive. Here we use a combination of expression correlation analysis, meta-analysis of gene expression profiles in response to specific stimuli and in selected mutants, and promoter content analysis to infer the biological role of the <it>Arabidopsis thaliana </it>PNP, AtPNP-A.</p> <p>Results</p> <p>A gene ontology analysis of <it>AtPNP-A </it>and the 25 most expression correlated genes revealed a significant over representation of genes annotated as part of the systemic acquired resistance (SAR) pathway. Transcription of these genes is strongly induced in response to salicylic acid (SA) and its functional synthetic analogue benzothiadiazole S-methylester (BTH), a number of biotic and abiotic stresses including many SA-mediated SAR-inducing conditions, as well as in the constitutive SAR expressing mutants <it>cpr5 </it>and <it>mpk4 </it>which have elevated SA levels. Furthermore, the expression of <it>AtPNP-A </it>was determined to be significantly correlated with the SAR annotated transcription factor, <it>WRKY 70</it>, and the promoters of <it>AtPNP-A </it>and the correlated genes contain an enrichment in the core WRKY binding W-box <it>cis</it>-elements. In constitutively expressing <it>WRKY 70 </it>lines the expression of <it>AtPNP-A </it>and the correlated genes, including the SAR marker genes, <it>PR-2 </it>and <it>PR-5</it>, were determined to be strongly induced.</p> <p>Conclusion</p> <p>The co-expression analyses, both in wild type and mutants, provides compelling evidence that suggests <it>AtPNP-A </it>may function as a component of plant defence responses and SAR in particular. The presented evidence also suggests that the expression of <it>AtPNP-A </it>is controlled by WRKY transcription factors and WRKY 70 in particular. <it>AtPNP-A </it>shares many characteristics with PR proteins in that its transcription is strongly induced in response to pathogen challenges, it contains an N-terminal signalling peptide and is secreted into the extracellular space and along with PR-1, PR-2 and PR-5 proteins it has been isolated from the Arabidopsis apoplast. Based on these findings we suggest that <it>AtPNP-A </it>could be classified as a newly identified PR protein.</p

Ozone and nitric oxide induce cGMP-dependent and independent transcription of defence genes in tobacco

Here, we analyse the temporal signatures of ozone (O3)-induced hydrogen peroxide (H2O2) and nitric oxide (NO) and the role of the second messenger guanosine 3′,5′-cyclic monophosphate (cGMP) in transcriptional changes of genes diagnostic for biotic and abiotic stress responses. Within 90 min O3 induced H2O2 and NO peaks and we demonstrate that NO donors cause rapid H2O2 accumulation in tobacco (Nicotiana tabacum) leaf. Ozone also causes highly significant, late (> 2 h) and sustained cGMP increases, suggesting that the second messenger may not be required in all early (< 2 h) responses to O3, but is essential and sufficient for the induction of some O3-dependent pathways

The arabidopsis wall associated kinase-like 10 gene encodes a functional guanylyl cyclase and is coexpressed with pathogen defense related genes

Second messengers have a key role in linking environmental stimuli to physiological responses. One such messenger, guanosine 3′,5′-cyclic monophosphate (cGMP), has long been known to be an essential signaling molecule in many different physiological processes in higher plants, including biotic stress responses. To date, however, the guanylyl cyclase (GC) enzymes that catalyze the formation of cGMP from GTP have largely remained elusive in higher plants. We have identified an Arabidopsis receptor type wall associated kinase–like molecule (AtWAKL10) as a candidate GC and provide experimental evidence to show that the intracellular domain of AtWAKL10431–700 can generate cGMP in vitro. Further, we also demonstrate that the molecule has kinase activity indicating that AtWAKL10 is a twin-domain catalytic protein. A co-expression and stimulus-specific expression analysis revealed that AtWAKL10 is consistently co-expressed with well characterized pathogen defense related genes and along with these genes is induced early and sharply in response to a range of pathogens and their elicitors

The arabidopsis cyclic nucleotide interactome

Background: Cyclic nucleotides have been shown to play important signaling roles in many physiological processes in plants including photosynthesis and defence. Despite this, little is known about cyclic nucleotidedependent signaling mechanisms in plants since the downstream target proteins remain unknown. This is largely due to the fact that bioinformatics searches fail to identify plant homologs of protein kinases and phosphodiesterases that are the main targets of cyclic nucleotides in animals. Methods: An affinity purification technique was used to identify cyclic nucleotide binding proteins in Arabidopsis thaliana. The identified proteins were subjected to a computational analysis that included a sequence, transcriptional co-expression and functional annotation analysis in order to assess their potential role in plant cyclic nucleotide signaling. Results: A total of twelve cyclic nucleotide binding proteins were identified experimentally including key enzymes in the Calvin cycle and photorespiration pathway. Importantly, eight of the twelve proteins were shown to contain putative cyclic nucleotide binding domains. Moreover, the identified proteins are post-translationally modified by nitric oxide, transcriptionally co-expressed and annotated to function in hydrogen peroxide signaling and the defence response. The activity of one of these proteins, GLYGOLATE OXIDASE 1, a photorespiratory enzyme that produces hydrogen peroxide in response to Pseudomonas, was shown to be repressed by a combination of cGMP and nitric oxide treatment. Conclusions: We propose that the identified proteins function together as points of cross-talk between cyclic nucleotide, nitric oxide and reactive oxygen species signaling during the defence response

The Arabidopsis Wall Associated Kinase-Like 10 Gene Encodes a Functional Guanylyl Cyclase and Is Co-Expressed with Pathogen Defense Related Genes

Second messengers have a key role in linking environmental stimuli to physiological responses. One such messenger, guanosine 3′,5′-cyclic monophosphate (cGMP), has long been known to be an essential signaling molecule in many different physiological processes in higher plants, including biotic stress responses. To date, however, the guanylyl cyclase (GC) enzymes that catalyze the formation of cGMP from GTP have largely remained elusive in higher plants. is consistently co-expressed with well characterized pathogen defense related genes and along with these genes is induced early and sharply in response to a range of pathogens and their elicitors.We demonstrate that AtWAKL10 is a twin-domain, kinase-GC signaling molecule that may function in biotic stress responses that are critically dependent on the second messenger cGMP

trt-1 Is the Caenorhabditis elegans Catalytic Subunit of Telomerase

Mutants of trt-1, the Caenorhabditis elegans telomerase reverse transcriptase, reproduce normally for several generations but eventually become sterile as a consequence of telomere erosion and end-to-end chromosome fusions. Telomere erosion and uncapping do not cause an increase in apoptosis in the germlines of trt-1 mutants. Instead, late-generation trt-1 mutants display chromosome segregation defects that are likely to be the direct cause of sterility. trt-1 functions in the same telomere replication pathway as mrt-2, a component of the Rad9/Rad1/Hus1 (9–1–1) proliferating cell nuclear antigen–like sliding clamp. Thus, the 9–1–1 complex may be required for telomerase to act at chromosome ends in C. elegans. Although telomere erosion limits replicative life span in human somatic cells, neither trt-1 nor telomere shortening affects postmitotic aging in C. elegans. These findings illustrate effects of telomere dysfunction in C. elegans mutants lacking the catalytic subunit of telomerase, trt-1

Alemtuzumab preconditioning with tacrolimus monotherapy - The impact of serial monitoring for donor-specific antibody

BACKGROUND. Antibody preconditioning with tacrolimus monotherapy has allowed many renal allograft recipients to be maintained on spaced weaning. METHODS. Of 279 renal allograft recipients transplanted between March 2003 and December 2004, 222 (80%) had spaced weaning (i.e., reduction of tacrolimus monotherapy dosing to every other day, three times a week, twice a week, or once a week) attempted. Routine monitoring for donor-specific antibody (DSA) was begun in September 2004. Mean follow-up is 34±6.5 months after transplantation and 26±8.1 months after the initiation of spaced weaning. RESULTS. One hundred and twenty-two (44%) patients remained on spaced weaning. One- and 2-year actual patient/graft survival was 99%/99%, and 97%/96%. Fifty-six (20%) patients experienced acute rejection after initiation of spaced weaning. One- and 2-year actual patient/graft survival was 100%/98%, and 94%/78%. Forty-two (15%) patients with stable renal function had spaced weaning stopped because of the development of DSA, which disappeared in 17 (40%). One- and 2-year actual patient and graft survival was 100% and 100%. CONCLUSION. Adult renal transplant recipients who are able to be maintained on spaced weaning have excellent outcomes. Patients with stable renal function who have reversal of weaning because of the development of DSA also have excellent outcomes. Routine monitoring for DSA may allow patients to avoid late rejection after spaced weaning. © 2008 Lippincott Williams & Wilkins, Inc