C.-J. Chang

Bio: C.-J. Chang is an academic researcher. The author has contributed to research in topics: Mollicutes & Citric acid cycle. The author has an hindex of 3, co-authored 3 publications receiving 362 citations.

Purine and Pyrimidine Metabolism in Mollicutes Species

Abstract: We studied the purine enzyme activities in dialyzed cytoplasmic extracts from the following eight species, representing four genera, of Mollicutes: Mycoplasma pneumoniae FHT (T = type strain) and M129, Mycoplasma bovigenitalium PG-11T, Mycoplasma hominis PG-21T and 1620, Mycoplasma genitalium G-37T, Mycoplasma hyopneumoniae JT, Ureaplasma urealyticum T960T, Spiroplasma citri Maroc-R8A2T, and Anaeroplasma intermedium 5LA. In an investigation of purine nucleoside kinase activity we also included M. hominis 13408, 10144, 13428, 1612, 1184, and Botte. All of these Mollicutes species except U. urealyticum had purine phosphoribosyltransferase activity for adenine, hypoxanthine, and guanine; U. urealyticum had only adenine phosphoribosyltransferase activity. All of the organisms had nucleoside phosphorylase activity which used either ribose 1-phosphate or deoxyribose 1-phosphate and adenine, hypoxanthine, or guanine for the synthesis of nucleosides and adenosine, deoxyadenosine, guanosine, deoxyguanosine, inosine, or deoxyinosine in the reverse direction. All had 5′-nucleotidase activity for adenosine monophosphate, deoxyadenosine monophosphate, inosine monophosphate, or guanosine monophosphate. Only M. hominis 1620, 13408, 10144, and 13428, A. intermedium, and S. citri had pyrophosphate-dependent nucleoside kinase activity. Only S. citri had nucleoside kinase activity with adenosine triphosphate and deoxyguanosine. We studied pyrimidine enzyme activities in all of the Mollicutes species except M. hominis and M. bovigenitalium. All of the Mollicutes species assayed had thymidine, thymidylate, and deoxycytidine kinase and thymidine and uridine phosphorylase activities. All of the Mycoplasma spp. had deoxycytotidine monophosphate and cytidine-deoxycytidine deaminase activities. All of the Mycoplasma spp. and U. urealyticum lacked deoxyuridine triphosphatase activity. U. urealyticum lacked deoxycytidine monophosphate deaminase activity, but otherwise it resembled all of the Mycoplasma spp. A. intermedium and S. citri differed from each other and from Mycoplasma spp. and U. urealyticum in the patterns of pyrimidine enzyme activities. Pyrophosphate-dependent nucleoside kinase activity was the most variably detected activity. None of the Mycoplasma spp. except four of eight strains of M. hominis had this kinase activity. Likewise, U. urealyticum did not have the pyrophosphate-dependent nucleoside kinase activity; however, A. intermedium and S. citri did have this enzyme activity. The absence of deoxyuridine triphosphatase activity in all Mycoplasma spp. may be related to their proposed rapid evolution and the relative lack of conserved sequences in their 5S ribosomal ribonucleic acids.

Metabolism of members of the Spiroplasmataceae

Abstract: Cell-free extracts from 10 strains of Spiroplasma species were examined for 67 enzyme activities of the Embden-Meyerhof-Parnas pathway, pentose phosphate shunt, tricarboxylic acid cycle, and purine and pyrimidine pathways. The spiroplasmas were fermentative, possessing enzyme activities that converted glucose 6-phosphate to pyruvate and lactate by the Embden-Meyerhof-Parnas pathway. Substrate phosphorylation was found in all strains. A modified pentose phosphate shunt was present, which was characterized by a lack of detectable glucose 6-phosphate and 6-phosphogluconate dehydrogenase activities. Spiroplasmas could synthesize purine mononucleotides by using pyrophosphate (PPi) as the orthophosphate donor. All spiroplasmas except Spiroplasma floricola used adenosine triphosphate (ATP) to phosphorylate deoxyguanosine; no other nucleoside could be phosphorylated with ATP by any spiroplasma tested. These results contrast with those reported for other mollicutes, in which PPi serves as the orthophosphate donor in the nucleoside kinase reaction. The participation of ATP rather than PPi in this reaction is unknown in other mollicutes regardless of the nucleoside reactant. Deoxypyrimidine enzyme activities were similar but varied in the reactions involving deamination of deoxycytidine triphosphate and deoxycytidine. All Spiroplasma spp. strains had deoxyuridine triphosphatase activity. Uridine phosphorylase activity varied among strains and is possibly group dependent. As in all other mollicutes, a tricarboxylic acid cycle is apparently absent in Spiroplasma spp. Reduced nicotinamide adenine dinucleotide oxidase activity was localized in the cytoplasmic fraction of all Spiroplasma species tested. Our assays indicate that the members of the Spiroplasmataceae are essentially metabolically homogeneous in the highly conserved pathways which we studied, but differ from other mollicutes in several important respects. These differences are of probable phylogenetic significance and may provide tools for recognition of higher taxonomic levels of mollicutes.

'Candidatus Phytoplasma', a taxon for the wall-less, non-helical prokaryotes that colonize plant phloem and insects

Abstract: The trivial name ‘phytoplasma’ has been adopted to collectively name wall-less, non-helical prokaryotes that colonize plant phloem and insects, which were formerly known as mycoplasma-like organisms. Although phytoplasmas have not yet been cultivated in vitro, phylogenetic analyses based on various conserved genes have shown that they represent a distinct, monophyletic clade within the class Mollicutes. It is proposed here to accommodate phytoplasmas within the novel genus ‘Candidatus (Ca.) Phytoplasma’. Given the diversity within ‘Ca. Phytoplasma’, several subtaxa are needed to accommodate organisms that share <97?5 % similarity among their 16S rRNA gene sequences. This report describes the properties of ‘Ca. Phytoplasma’, a taxon that includes the species ‘Ca. Phytoplasma aurantifolia’ (the prokaryote associated with witches’-broom disease of small-fruited acid lime), ‘Ca. Phytoplasma australiense’ (associated with Australian grapevine yellows), ‘Ca. Phytoplasma fraxini’ (associated with ash yellows), ‘Ca. Phytoplasma japonicum’ (associated with Japanese hydrangea phyllody), ‘Ca. Phytoplasma brasiliense’ (associated with hibiscus witches’-broom in Brazil), ‘Ca. Phytoplasma castaneae’ (associated with chestnut witches’-broom in Korea), ‘Ca. Phytoplasma asteris’ (associated with aster yellows), ‘Ca. Phytoplasma mali’ (associated with apple proliferation), ‘Ca. Phytoplasma phoenicium’ (associated with almond lethal disease), ‘Ca. Phytoplasma trifolii’ (associated with clover proliferation), ‘Ca. Phytoplasma cynodontis’ (associated with Bermuda grass white leaf), ‘Ca. Phytoplasma ziziphi’ (associated with jujube witches’-broom), ‘Ca. Phytoplasma oryzae’ (associated with rice yellow dwarf) and six species-level taxa for which the Candidatus species designation has not yet been formally proposed (for the phytoplasmas associated with X-disease of

Phytoplasma-specific PCR primers based on sequences of the 16S-23S rRNA spacer region.

Abstract: In order to develop a diagnostic tool to identify phytoplasmas and classify them according to their phylogenetic group, we took advantage of the sequence diversity of the 16S-23S intergenic spacer regions (SRs) of phytoplasmas. Ten PCR primers were developed from the SR sequences and were shown to amplify in a group-specific fashion. For some groups of phytoplasmas, such as elm yellows, ash yellows, and pear decline, the SR primer was paired with a specific primer from within the 16S rRNA gene. Each of these primer pairs was specific for a specific phytoplasma group, and they did not produce PCR products of the correct size from any other phytoplasma group. One primer was designed to anneal within the conserved tRNA(Ile) and, when paired with a universal primer, amplified all phytoplasmas tested. None of the primers produced PCR amplification products of the correct size from healthy plant DNA. These primers can serve as effective tools for identifying particular phytoplasmas in field samples.

Phytoplasmas: bacteria that manipulate plants and insects

Abstract: SUMMARY Taxonomy: Superkingdom Prokaryota; Kingdom Monera; Domain Bacteria; Phylum Firmicutes (low-G+C, Gram-positive eubacteria); Class Mollicutes; Candidatus (Ca.) genus Phytoplasma. Host range: Ca. Phytoplasma comprises approximately 30 distinct clades based on 16S rRNA gene sequence analyses of ~200 phytoplasmas. Phytoplasmas are mostly dependent on insect transmission for their spread and survival. The phytoplasma life cycle involves replication in insects and plants. They infect the insect but are phloem-limited in plants. Members of Ca. Phytoplasma asteris (16SrI group phytoplasmas) are found in 80 monocot and dicot plant species in most parts of the world. Experimentally, they can be transmitted by approximately 30, frequently polyphagous insect species, to 200 diverse plant species. Disease symptoms: In plants, phytoplasmas induce symptoms that suggest interference with plant development. Typical symptoms include: witches’ broom (clustering of branches) of developing tissues; phyllody (retrograde metamorphosis of the floral organs to the condition of leaves); virescence (green coloration of non-green flower parts); bolting (growth of elongated stalks); formation of bunchy fibrous secondary roots; reddening of leaves and stems; generalized yellowing, decline and stunting of plants; and phloem necrosis. Phytoplasmas can be pathogenic to some insect hosts, but generally do not negatively affect the fitness of their major insect vector(s). In fact, phytoplasmas can increase fecundity and survival of insect vectors, and may influence flight behaviour and plant host preference of their insect hosts. Disease control: The most common practices are the spraying of various insecticides to control insect vectors, and removal of symptomatic plants. Phytoplasma-resistant cultivars are not available for the vast majority of affected crops.

Genus and species- specific identification of mycoplasmas by 16s rrna amplification

Abstract: Systematic computer alignment of mycoplasmal 16S rRNA sequences allowed the identification of variable regions with both genus- and species-specific sequences. Species-specific sequences of Mycoplasma collis were elucidated by asymmetric amplification and dideoxynucleotide sequencing of variable regions, using primers complementary to conserved regions of 16S rRNA. Primers selected for Mycoplasma pneumoniae, M. hominis, M. fermentans, Ureaplasma urealyticum, M. pulmonis, M. arthritidis, M. neurolyticum, M. muris, and M. collis proved to be species specific in the polymerase chain reaction. The genus-specific primers reacted with all mycoplasmal species investigated as well as with members of the genera Ureaplasma, Spiroplasma, and Acholeplasma. No cross-reaction was observed with members of the closely related genera Streptococcus, Lactobacillus, Bacillus, and Clostridium or with any other microorganism tested. On the basis of the high copy number of rRNA, a highly sensitive polymerase chain reaction assay was developed in which the nucleic acid content equivalent to a single organism could be detected.