Evolutionary transfer of ORF-containing group I introns between different subcellular compartments (chloroplast and mitochondrion)

We describe here a case of homologous introns containing homologous open reading frames (ORFs) that are inserted at the same site in the large subunit (LSU) rRNA gene of different organelles in distantly related organisms. We show that the chloroplast LSU rRNA gene of the green alga Chlamydomonas pallidostigmatica contains a group I intron (CpLSU.2) encoding a site-specific endonuclease (I-CpaI). This intron is inserted at the identical site (corresponding to position 1931-1932 of the Escherichia coli 23S rRNA sequence) as a group I intron (AcLSU.m1) in the mitochondrial LSU rRNA gene of the amoeboid protozoon Acanthamoeba castellanii. The CpLSU.2 intron displays a remarkable degree of nucleotide similarity in both primary sequence and secondary structure to the AcLSU.m1 intron; moreover, the Acanthamoeba intron contains an ORF in the same location within its secondary structure as the CpLSU.2 ORF and shares with it a strikingly high level of amino acid similarity (65%; 42% identity). A comprehensive survey of intron distribution at site 1931 of the chloroplast LSU rRNA gene reveals a rather restricted occurrence within the polyphyletic genus Chlamydomonas, with no evidence of this intron among a number of non- Chlamydomonad green algae surveyed, nor in land plants. A parallel survey of homologues of a previously described and similar intron/ORF pair (C. reinhardtii chloroplast CrLSU/A. castellanii mitochondrial AcLSU.m3) also shows a restricted occurrence of this intron (site 2593) among chloroplasts, although the intron distribution is somewhat broader than that observed at site 1931, with site-2593 introns appearing in several green algal branches outside of the Chlamydomonas lineage. The available data, while not definitive, are most consistent with a relatively recent horizontal transfer of both site-1931 and site- 2593 introns (and their contained ORFs) between the chloroplast of a Chlamydomonas-type organism and the mitochondrion of an Acanthamoeba- like organism, probably in the direction chloroplast to mitochondrion. The data also suggest that both introns could have been acquired in a single event.      

A comparison of the illness beliefs of people with angina and their peers: a questionnaire study

Background  

What people believe about their illness may affect how they cope with it. It has been suggested that such beliefs stem from those commonly held within society . This study compared the beliefs held by people with angina, regarding causation and coping in angina, with the beliefs of their friends who do not suffer from angina.     

<Emphasis Type="Italic">Candida albicans</Emphasis>genome sequence: a platform for genomics in the absence of genetics

Publication of the complete diploid genome sequence of the yeast Candida albicans will accelerate research into the pathogenesis of Candida infections. Comparative genomic analysis highlights genes that may contribute to C. albicans survival and its fitness as a human commensal and pathogen.     

The robustness of two phylogenetic methods: four-taxon simulations reveal a slight superiority of maximum likelihood over neighbor joining

The robustness (sensitivity to violation of assumptions) of the maximum- likelihood and neighbor-joining methods was examined using simulation. Maximum likelihood and neighbor joining were implemented with Jukes- Cantor, Kimura, and gamma models of DNA substitution. Simulations were performed in which the assumptions of the methods were violated to varying degrees on three model four-taxon trees. The performance of the methods was evaluated with respect to ability to correctly estimate the unrooted four-taxon tree. Maximum likelihood outperformed neighbor joining in 29 of the 36 cases in which the assumptions of both methods were satisfied. In 133 of 180 of the simulations in which the assumptions of the maximum-likelihood and neighbor-joining methods were violated, maximum likelihood outperformed neighbor joining. These results are consistent with a general superiority of maximum likelihood over neighbor joining under comparable conditions. They extend and clarify an earlier study that found an advantage for neighbor joining over maximum likelihood for gamma-distributed mutation rates.      

Expression of N-linked sialyl Le(x) determinants and O-glycans in the carbohydrate moiety of human amniotic fluid transferrin during pregnancy

Transferrin, a glycoprotein involved in iron transport in body fluids, was isolated from amniotic fluid of a hydramniospatient by sequential anion-exchange chromatography and gel filtration. The N-glycans of human amniotic fluid transferrin (hAFT) were enzymatically liberated by PNGase-F digestion, isolated by gel filtration and fractionated by (high-pH) anion-exchange chromatography. After alkaline borohydride treatment of native hAFT, the released O-glycans were isolated by gel filtration and fractionated by anion-exchange chroma-tography. Structure elucidation of 14 N- and 2 O-glycans was performed by 500 or 600 MHz1H-NMR spectroscopy. Besides conventional N-glycans established earlier for human serum transferrin (hST), new (alpha1-3)-fucosylated N- glycans were found, representing sialyl Le(x) elements. Furthermore, as compared to hST, a higher degree of (alpha1-6)-fucosylation and an increase in branching from di- to triantennary compounds has been detected. The presence of O-glycans is demonstrated for the first time in transferrin.      

Consequences of concurrent Ascaridia galli and Escherichia coli infections in chickens

   

The principal aim of this study was to evaluate dissociative anaesthesia for castration of colts during field conditions. Three dissociative anaesthetic protocols were evaluated during castration of colts in an animal hospital. The protocol considered to be the most suitable was thereafter evaluated during castration of colts under field conditions. Respiratory and haemodynamic parameters and the response to surgery were determined during anaesthesia. All horses breathed air spontaneously during anaesthesia. Under hospital conditions 26 colts were randomised to receive one of three anaesthetic protocols: Romifidine and tiletamine-zolazepam (RZ); acepromazine, romifidine and tiletamine-zolazepam (ARZ); or acepromazine, romifidine, butorphanol and tiletamine-zolazepam (ARBZ). The surgeon was blinded to the anaesthetic protocol used and decided whether supplemental anaesthesia was needed to complete surgery. Under field conditions 31 colts were castrated during anaesthesia with the ARBZ protocol. All inductions, anaesthesia and recoveries were calm and without excitation under both hospital and field conditions. Surgery was performed within 5–20 minutes after the horses had assumed lateral recumbency during both hospital and field castrations. Under hospital conditions some horses needed supplemental anaesthesia with all three anaesthetic protocols to complete surgery. Interestingly, none of the horses castrated with protocol ARBZ under field conditions needed additional anaesthesia. Cardiorespiratory changes were within acceptable limits in these clinically healthy colts.     

Microbial signaling and systems biology

A report of the symposium on Signaling and Systems Biology held during the Society for General Microbiology Spring Meeting, 29-30 March 2010, Edinburgh, UK.