Grain size and weight are closely related to the yield of cereal crops. Abnormal development of the embryo, an important part of the grain, not only affects crop yield but also impacts next-generation survival. Here, we found that maize GSK3-like kinase ZmSK2, a homolog of BIN2 in Arabidopsis, is involved in embryonic development. ZmSK2 overexpression resulted in severe BR defective phenotypes and arrested embryonic development at the transition stage, while the zmsk2 knockout lines showed enlarged embryos. ZmSK2 interacts with Aux/IAA-transcription factor 28 (ZmIAA28), a negative regulator of auxin signaling, and the interaction region is the auxin degron "GWPPV" motif of ZmIAA28 domain II. Coexpression of ZmSK2 with ZmIAA28 increased the accumulation of ZmIAA28 in maize protoplasts, which may have been due to phosphorylation by ZmSK2. In conclusion, this study reveals the function of ZmSK2 in maize embryonic development and proposes that ZmSK2-ZmIAA28 may be another link in the signaling pathway that integrates BR and auxin.

Background: Pneumocystis jirovecii is the cause of Pneumocystis pneumonia (PCP) in immunosuppressed humans. Asymptomatic colonisation with P jirovecii may occur in patients with minor immunosuppression or chronic lung disease. The aim of this study was to describe the molecular epidemiology of P jirovecii in Britain over a period of 12.5 years.Methods: Between January 1989 and July 2001 161 samples of P jirovecii were obtained from patients with PCP (n = 119), patients colonised by P jirovecii ( n = 35), and from air spora ( n = 6). Genotyping of samples was performed at the mitochondrial large subunit rRNA (mt LSU rRNA).Results: Genotype 1 (38%) was the most frequently identified genotype: genotypes 2 (26.6%), 3 (20.3%), and 4 (5%) were less common. Mixed infection ( more than one genotype) was identified in 10% of samples. While genotype 1 was the most frequently detected type in both patients with PCP and those colonised by P jirovecii ( 38% and 42%, respectively), these groups differed in the relatively lower rate of detection of genotype 4 (2% v 17%) and the higher detection of mixed infection in those with PCP (13% v 3%). Detection of specific genotypes of P jirovecii was associated with the patient's place of residence ( p = 0.02). There was no association between specific genotypes and severity of PCP as measured by arterial oxygen tension ( p = 0.3).Conclusions: The evidence of clustering of specific genotypes with patient's postcode of residence is consistent with the hypothesis of person to person transmission of P jirovecii via the airborne route. The lack of association between specific mt LSU rRNA genotypes and severity of PCP suggests that this locus is not implicated in the virulence of the organism.

Pneumocystis jirovecii is the cause of Pneumocystis pneumonia (PCP) in humans. Isolates of P. jirovecii obtained from patients in Harare, Zimbabwe were genotyped at the superoxide dismutase locus. High genotypic similarity to isolates of P. jirovecii obtained from patients in London, UK was observed. These data provide additional support for the hypothesis that P. jirovecii is genetically indistinguishable in isolates from geographically diverse locations.

In the fungus Pneumocystis carinii, at least three gene families (PRT1, MSR, and MSG) have the potential to generate high-frequency antigenic variation, which is likely to be a strategy by which this parasitic fungus is able to prolong its survival in the rat lung. Members of these gene families are clustered at chromosome termini, a location that fosters recombination, which has been implicated in selective expression of MSG genes. To gain insight into the architecture, evolution, and regulation of these gene clusters, six telomeric segments of the genome were sequenced. Each of the segments began with one or more unique genes, after which were members of different gene families, arranged in a head-to-tail array. The three-gene repeat PRT1-MSR-MSG was common, suggesting that duplications of these repeats have contributed to expansion of all three families. However, members of a gene family in an array were no more similar to one another than to members in other arrays, indicating rapid divergence after duplication. The intergenic spacers were more conserved than the genes and contained sequence motifs also present in subtelomeres, which in other species have been implicated in gene expression and recombination. Long mononucleotide tracts were present in some MSR genes. These unstable sequences can be expected to suffer frequent frameshift mutations, providing P. carinii with another mechanism to generate antigen variation.

AbstractIn the fungus Pneumocystis carinii, at least three gene families (PRT1, MSR, and MSG) have the potential to generate high-frequency antigenic variation, which is likely to be a strategy by which this parasitic fungus is able to prolong its survival in the rat lung. Members of these gene families are clustered at chromosome termini, a location that fosters recombination, which has been implicated in selective expression of MSG genes. To gain insight into the architecture, evolution, and regulation of these gene clusters, six telomeric segments of the genome were sequenced. Each of the segments began with one or more unique genes, after which were members of different gene families, arranged in a head-to-tail array. The three-gene repeat PRT1-MSR-MSG was common, suggesting that duplications of these repeats have contributed to expansion of all three families. However, members of a gene family in an array were no more similar to one another than to members in other arrays, indicating rapid divergence after duplication. The intergenic spacers were more conserved than the genes and contained sequence motifs also present in subtelomeres, which in other species have been implicated in gene expression and recombination. Long mononucleotide tracts were present in some MSR genes. These unstable sequences can be expected to suffer frequent frameshift mutations, providing P. carinii with another mechanism to generate antigen variation.

Pneumocystis carinii has a multigene family, PRT1 , that encodes proteins with homology to KEX2-like proteases. PRT1 genes cluster with MSG genes near the telomeres and, like MSG, PRT1 proteins seem to be surface-expressed. The clustering of PRT1 and MSG genes suggested that expression of the two multigene families might be coordinated. Studying gene expression in P. carinii has been hampered by the lack of a culture system, and by lack of clonality in P. carinii populations in naturally infected rats, the host of this fungus. Heterogeneity can be reduced, however, by low-dose intratracheal inoculation, which can produce P. carinii populations dominated by organisms derived from a single progenitor. To study PRT1 expression, nude rats were inoculated with approximately 10 P. carinii each. The clonality of the P. carinii populations from inoculated rats was assessed by analysis of the UCS locus, a site in the genome that is known to be very heterogeneous in naturally infected rats, but nearly homogeneous in rats infected by low-dose intratracheal inoculation. Each of the populations had the same MSG gene at the UCS locus in at least 80 % of the organisms. To investigate PRT1 gene expression, RNA was amplified using primers that amplify numerous PRT1 genes. Seventy-four cloned cDNAs were sequenced, including at least 12 clones from each population of P. carinii . Many differently expressed PRT1 sequences were identified in each population, and a total of 45 different sequences were detected. However, the same PRT1 sequence was present in 15 of 74 plasmids and was found in 3 of the 5 P. carinii populations, suggesting that some PRT1 genes may be either more commonly expressed or expressed at a higher level. These data show that many members of the PRT1 gene family can be expressed in populations of P. carinii derived from few progenitors and suggest that the regulation of this family is different from that governing expression of the MSG gene family.

Background: The opportunistic fungus Pneumocystis jiroveci is a common cause of respiratory infection in immunocompromised patients. By contrast, pneumocystis pneumonia (PCP) occurs only rarely in immunocompetent individuals. Asymptomatic colonisation with P jiroveci has recently been described in patients who are either minimally immunosuppressed or who have underlying lung disorders such as bronchiectasis. We sought to determine the prevalence of asymptomatic colonisation by P jiroveci in a cohort of adult patients undergoing diagnostic bronchoscopy.Methods: A prospective observational cohort study was performed in patients who required bronchoscopy and bronchoalveolar lavage (BAL) as part of their routine clinical assessment. All the samples underwent standard microbiological analysis and a Grocott methenamine silver stain was performed where clinically indicated to detect the presence of P jiroveci. Polymerase chain reaction for detection of P jiroveci specific DNA was also performed.Results: Ninety three consecutive BAL fluid samples were analysed, 17 (18%) of which contained P jiroveci DNA. Of the potential predictors examined, only glucocorticoid use was significantly associated with detectable P jiroveci DNA. Eighteen patients were receiving oral glucocorticoids (equivalent to >20 mg/day prednisolone) at the time of bronchoscopy, of whom eight (44%) had detectable P jiroveci DNA. In contrast, P jiroveci was detected in only nine of 75 patients (12%) who were not receiving glucocorticoids (difference between proportions 32%, 95% CI 8 to 57; p=0.004, two tailed Fisher's exact test).Conclusions: P jiroveci colonisation, as determined by detection of P jiroveci DNA in BAL fluid, is common in HIV negative patients with primary respiratory disorders undergoing bronchoscopy and BAL. The higher prevalence in patients receiving corticosteroids suggests that oral glucocorticoid therapy is an independent risk factor for colonisation. In contrast, underlying lung cancer or COPD did not appear to be risk factors.

Veterinary RecordVolume 152, Issue 26 p. 811-813 Short Communication Assessment of Pneumocystis species carriage in captive primates C. Demanche, C. Demanche Equipe de Mycologie, UMR 956, INRA-AFSSAENVA- Paris XII Biologie Moleculaire et Immunologie Parasitaires et Fongiques, Ecole Nationale Vétérinaire d'Alfort, 94704 Maisons- Alfort, FranceSearch for more papers by this authorT. Petit DVM, T. Petit DVM Parc Zoologique de la Palmyre, Les Mathes, FranceSearch for more papers by this authorP. Moisson DVM, P. Moisson DVM Parc Zoologique de Mulhouse, FranceSearch for more papers by this authorF. Ollivet DVM, F. Ollivet DVM Parc Zoologique de Vincennes, FranceSearch for more papers by this authorJ. Rigoulet DVM, J. Rigoulet DVM Jardin des Plantes de Paris, FranceSearch for more papers by this authorR. Chermette DVM, R. Chermette DVM Equipe de Mycologie, UMR 956, INRA-AFSSAENVA- Paris XII Biologie Moleculaire et Immunologie Parasitaires et Fongiques, Ecole Nationale Vétérinaire d'Alfort, 94704 Maisons- Alfort, FranceSearch for more papers by this authorE. Dei-Cas MD, PhD, E. Dei-Cas MD, PhD Ecologie du Parasitisme, Institut Pasteur de Lille, FranceSearch for more papers by this authorA. E. Wakefield PhD, A. E. Wakefield PhD Molecular Infectious Diseases Group, Institute of Molecular Medicine, University of Oxford, OxfordSearch for more papers by this authorJ. Guillot DVM, PhD, J. Guillot DVM, PhD Equipe de Mycologie, UMR 956, INRA-AFSSAENVA- Paris XII Biologie Moleculaire et Immunologie Parasitaires et Fongiques, Ecole Nationale Vétérinaire d'Alfort, 94704 Maisons- Alfort, FranceSearch for more papers by this author C. Demanche, C. Demanche Equipe de Mycologie, UMR 956, INRA-AFSSAENVA- Paris XII Biologie Moleculaire et Immunologie Parasitaires et Fongiques, Ecole Nationale Vétérinaire d'Alfort, 94704 Maisons- Alfort, FranceSearch for more papers by this authorT. Petit DVM, T. Petit DVM Parc Zoologique de la Palmyre, Les Mathes, FranceSearch for more papers by this authorP. Moisson DVM, P. Moisson DVM Parc Zoologique de Mulhouse, FranceSearch for more papers by this authorF. Ollivet DVM, F. Ollivet DVM Parc Zoologique de Vincennes, FranceSearch for more papers by this authorJ. Rigoulet DVM, J. Rigoulet DVM Jardin des Plantes de Paris, FranceSearch for more papers by this authorR. Chermette DVM, R. Chermette DVM Equipe de Mycologie, UMR 956, INRA-AFSSAENVA- Paris XII Biologie Moleculaire et Immunologie Parasitaires et Fongiques, Ecole Nationale Vétérinaire d'Alfort, 94704 Maisons- Alfort, FranceSearch for more papers by this authorE. Dei-Cas MD, PhD, E. Dei-Cas MD, PhD Ecologie du Parasitisme, Institut Pasteur de Lille, FranceSearch for more papers by this authorA. E. Wakefield PhD, A. E. Wakefield PhD Molecular Infectious Diseases Group, Institute of Molecular Medicine, University of Oxford, OxfordSearch for more papers by this authorJ. Guillot DVM, PhD, J. Guillot DVM, PhD Equipe de Mycologie, UMR 956, INRA-AFSSAENVA- Paris XII Biologie Moleculaire et Immunologie Parasitaires et Fongiques, Ecole Nationale Vétérinaire d'Alfort, 94704 Maisons- Alfort, FranceSearch for more papers by this author First published: 28 June 2003 https://doi.org/10.1136/vr.152.26.811Citations: 3 Correspondence to Professor Guillot Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume152, Issue26June 2003Pages 811-813 RelatedInformation

Forty-seven bronchoalveolar lavage fluid samples from 16 human immunodeficiency virus (HIV)-infected patients were used to test the latency model of Pneumocystis infection in the human host. Identification of DNA sequence polymorphisms at 4 independent loci were used to genotype Pneumocystis jiroveci from the 35 samples that contained detectable P. jiroveci DNA. Eighteen of those 35 samples came from patients who did not have Pneumocystis pneumonia (PCP) and had confirmed alternative diagnoses. Seven patients had asymptomatic carriage of P. jiroveci over periods of less than or equal to9.5 months after an episode of PCP, and in all 7 cases, a change in genotype from that in the original episode of PCP was observed. The absence of P. jiroveci DNA in one-fourth of the 47 samples and the observed changes in genotype during asymptomatic carriage do not support the latency model of infection. Asymptomatic carriage in HIV-infected patients may play a role in transmission of P. jiroveci and may even supply a reservoir for future infections.

Journal of Eukaryotic MicrobiologyVolume 50, Issue s1 p. 654-655 Multilocus Genotyping of Pneumocystis jirovecii from Adult HIV-Infected Patients with Pneumocystis Pneumonia ROBERT F. MILLER, Corresponding Author ROBERT F. MILLER Department of Sexually Transmitted Diseases, Windeyer Institute of Medical Sciences, Royal Free and University College Medical School, University College London, United KingdomCorresponding author: R. Miller. Telephone: +44 207 380 9945; Fax: +44 207 380 9669; Email: rmiller@gum.ucl.ac.ukSearch for more papers by this authorAUSTIN R. LINDLEY, AUSTIN R. LINDLEY Molecular Infectious Diseases Group, Weatherall Institute of Molecular Medicine, University of Oxford, United KingdomSearch for more papers by this authorHELEN E. AMBROSE, HELEN E. AMBROSE Molecular Infectious Diseases Group, Weatherall Institute of Molecular Medicine, University of Oxford, United KingdomSearch for more papers by this authorCECILE-MARIE ALIOUAT-DENIS, CECILE-MARIE ALIOUAT-DENIS Molecular Infectious Diseases Group, Weatherall Institute of Molecular Medicine, University of Oxford, United Kingdom Faculté Libre des Scietzces, Lille, FranceSearch for more papers by this authorANN E. WAKEFIELD, ANN E. WAKEFIELD Molecular Infectious Diseases Group, Weatherall Institute of Molecular Medicine, University of Oxford, United KingdomSearch for more papers by this author ROBERT F. MILLER, Corresponding Author ROBERT F. MILLER Department of Sexually Transmitted Diseases, Windeyer Institute of Medical Sciences, Royal Free and University College Medical School, University College London, United KingdomCorresponding author: R. Miller. Telephone: +44 207 380 9945; Fax: +44 207 380 9669; Email: rmiller@gum.ucl.ac.ukSearch for more papers by this authorAUSTIN R. LINDLEY, AUSTIN R. LINDLEY Molecular Infectious Diseases Group, Weatherall Institute of Molecular Medicine, University of Oxford, United KingdomSearch for more papers by this authorHELEN E. AMBROSE, HELEN E. AMBROSE Molecular Infectious Diseases Group, Weatherall Institute of Molecular Medicine, University of Oxford, United KingdomSearch for more papers by this authorCECILE-MARIE ALIOUAT-DENIS, CECILE-MARIE ALIOUAT-DENIS Molecular Infectious Diseases Group, Weatherall Institute of Molecular Medicine, University of Oxford, United Kingdom Faculté Libre des Scietzces, Lille, FranceSearch for more papers by this authorANN E. WAKEFIELD, ANN E. WAKEFIELD Molecular Infectious Diseases Group, Weatherall Institute of Molecular Medicine, University of Oxford, United KingdomSearch for more papers by this author First published: 11 July 2005 https://doi.org/10.1111/j.1550-7408.2003.tb00672.xCitations: 11Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume50, Issues1July 2003Pages 654-655 RelatedInformation

We present a patient who collapsed with chest pain and dyspnoea on a transatlantic flight. She was found to have Pneumocystis carinii pneumonia (PCP) and human immunodeficiency virus infection. Platypnoea and orthodeoxia, which have not been previously reported in association with PCP, were major features of her illness. The PCP predominantly affected her lung bases and it is likely that gravity increased intrapulmonary blood flow through poorly ventilated lung bases with failure of pulmonary vasoconstriction to increase upper zone perfusion, exacerbating desaturation on sitting up. The partial DNA sequence of the infecting P carinii was identical to previously described isolates.

ABSTRACT Isolates of Pneumocystis jiroveci from sulfa-exposed and nonexposed patients from London, United Kingdom, and Harare, Zimbabwe, were genotyped. At the dihydropteroate synthase (DHPS) locus, there was evidence of selection pressure from sulfa drug exposure, and reversal of DHPS genotype ratios occurred when selection pressure was absent or was removed.

ABSTRACT A mother and her 4.5-week-old infant had Pneumocystis carinii pneumonia contemporaneously. Genotyping of P. carinii f. sp. hominis DNA at three independent loci showed the same genotype in samples from mother and infant. These data suggest transmission of P. carinii organisms from the mother to her infant.

Pneumocystis carinii is an atypical fungus that causes pneumonia in immunocompromised individuals. P. carinii comprises a heterogeneous group of organisms that have been isolated from a wide range of mammalian host species. P. carinii infection is host species specific, the P. carinii organisms that infect humans have only been found in humans. This review discusses the application of molecular techniques to the study of the biology and epidemiology of P. carinii infection. It addresses the use of DNA amplification for the detection and diagnosis of P. carinii pneumonia. Studies investigating the reservoir of infectious P. carinii organisms, the routes of transmission of the infection, and the emergence of drug resistant strains of P. carinii are also discussed.

The disease known as Pneumocystis carinii pneumonia (PCP) is a major cause of illness and death in persons with impaired immune systems. While the genus Pneumocystis has been known to science for nearly a century, understanding of its members remained rudimentary until DNA analysis showed its extensive diversity. Pneumocystis organisms from different host species have very different DNA sequences, indicating multiple species. In recognition of its genetic and functional distinctness, the organism that causes human PCP is now named Pneumocystis jiroveci Frenkel 1999. Changing the organism’s name does not preclude the use of the acronym PCP because it can be read “Pneumocystis pneumonia.” DNA varies in samples of P. jiroveci, a feature that allows reexamination of the relationships between host and pathogen. Instead of lifelong latency, transient colonization may be the rule.

The dihydropteroate synthase (DHPS) gene from Pneumocystis carinii isolated from non-human primates was amplified using a polymerase chain reaction (PCR) and sequenced to analyse point mutations associated with sulfa resistance. P. carinii DHPS gene amplification was obtained from eight lung samples from five New World primate species and one Old World primate species. None of the animals had been exposed to sulfa drugs and only the wild-type P. carinii DHPS sequence at codons 55 and 57 was observed. These data support the hypothesis that high rates of DHPS mutants in P. carinii f. sp. hominis have arisen with increased use of sulfa drugs for P. carinii pneumonia prophylaxis.

Pneumocystis is an enigmatic organism, the clinical significance of which remained unrecognised until recently. It is a respiratory pathogen, causing pneumonia which, if untreated, is fatal. For many years its very nature was shrouded in uncertainty, but we now know unequivocally that it is a fungus and an important agent of fungal disease in certain specific settings. Pneumocystis was first seen in the lungs of guinea pigs by Carlos Chagas in 1909, and then in rat lungs by Antonio Carini. Both thought it was a type of trypanosome. In 1912, the Delanoë husband-and-wife team recognised that it was a distinct organism and named it Pneumocystis carinii, on account of the cyst-like morphology of the organism and in honour of Antonio Carini. It was first seen as an infection in humans in the 1920s, among infants with interstitial plasma cell pneumonia.

Pneumocystis carinii is an atypical fungus that causes pneumonia in immunocompromised individuals. P. carinii comprises a heterogeneous group of organisms that have been isolated from a wide range of mammalian host species. P. carinii infection is host species specific, the P. carinii organisms that infect humans have only been found in humans. This review discusses the application of molecular techniques to the study of the biology and epidemiology of P. carinii infection. It addresses the use of DNA amplification for the detection and diagnosis of P. carinii pneumonia. Studies investigating the reservoir of infectious P. carinii organisms, the routes of transmission of the infection, and the emergence of drug resistant strains of P. carinii are also discussed.

The disease known as Pneumocystis carinii pneumonia (PCP) is a major cause of illness and death in persons with impaired immune systems. While the genus Pneumocystis has been known to science for nearly a century, understanding of its members remained rudimentary until DNA analysis showed its extensive diversity. Pneumocystis organisms from different host species have very different DNA sequences, indicating multiple species. In recognition of its genetic and functional distinctness, the organism that causes human PCP is now named Pneumocystis jiroveci Frenkel 1999. Changing the organism's name does not preclude the use of the acronym PCP because it can be read "Pneumocystis pneumonia." DNA sequence variation exists among samples of R jiroveci, a feature that allows reexamination of the relationships between host and pathogen. Instead of lifelong latency, transient colonization may be the rule.

The single name Pneumocystis carinii consists of an heterogeneous group of specific fungal organisms that colonize a very wide range of mammalian hosts. In the present study, mitochondrial large subunit (mtLSU) and small subunit (mtSSU) rRNA sequences of P. carinii organisms from 24 different mammalian species were compared. The mammals were included in six major groups: Primates (12 species), Rodents (5 species), Carnivores (3 species), Bats (1 species), Lagomorphs (1 species), Marsupials (1 species) and Ungulates (1 species). Direct sequencing of PCR products demonstrated that specific mtSSU and mtLSU rRNA Pneumocystis sequence could be attributed to each mammalian species. No animal harbored P. carinii f. sp. hominis. Comparison of combined mtLSU and mtSSU aligned sequences confirmed cospeciation of P. carinii and corresponding mammalian hosts. P. carinii organisms isolated from mammals of the same zoological group systematically clustered together. Within each cluster, the genetic divergence between P. carinii organisms varied in terms of the phylogenetic divergence existing among the corresponding host species. However, the relative position of P. carinii groups (rodent, camivore or primate-derived P. carinii) could not be clearly determined. Further resolution will require the integration of additional sequence data.