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A non-pigmented, unicellular alga isolated from the faeces of British anuran tadpoles and which is associated with growth inhibition in these tadpoles, was described and identified using cytological, ultrastructural, nutrient assimilation and immunological studies. The alga possessed all the distinctive morphological features of the genus Prototheca, it grew weakly on Prototheca Isolation Medium (PIM), it required thiamine for continued growth and replication, and it could assimilate the five major substrates used to speciate the protothecans. All of these characteristics, together with previous nucleic acid hybridisation studies, indicated that the microorganism belonged to the genus Prototheca. There are currently five species recognised as valid (Pore, 1985 & 1986): Prototheca zopfii Kruger, 1884, P. wickerhamii Tubaki & Soneda, 1959, P. moriformis Kruger, 1884, P. stagnora Cooke, 1968 and P. ulmea Pore, 1986.The immunology showed that the new species was related to two of the protothecans, but overall it showed that the alga was antigenically distinct from the other protothecans tested in the immunoassay. This, together with its inability to grow strongly on PIM, its ability to assimilate a wide rage of carbon substrates and its ability to mediate growth inhibition in anuran tadpoles, indicated a new species of Prototheca. We therefore propose the name Prototheca richardsi sp. n. 相似文献
3.
Odile Ozier-Kalogeropoulos Marie-Thérèse Adeline Weng-Lang Yang George M. Carman François Lacroute 《Molecular & general genetics : MGG》1994,242(4):431-439
In the pyrimidine biosynthetic pathway, CTP synthetase catalyses the conversion of uridine 5-triphosphate (UTP) to cytidine 5-triphosphate (CTP). In the yeast Saccharomyces cerevisiae, the URA7 gene encoding this enzyme was previously shown to be nonessential for cell viability. The present paper describes the selection of synthetic lethal mutants in the CTP biosynthetic pathway that led us to clone a second gene, named URA8, which also encodes a CTP synthetase. Comparison of the predicted amino acid sequences of the products of URA7 and URA8 shows 78% identity. Deletion of the URA8 gene is viable in a haploid strain but simultaneous presence of null alleles both URA7 and URA8 is lethal. Based on the codon bias values for the two genes and the intracellular concentrations of CTP in strains deleted for one of the two genes, relative to the wild-type level, URA7 appears to be the major gene for CTP biosynthesis. Nevertheless, URA8 alone also allows yeast growth, at least under standard laboratory conditions. 相似文献
4.
Abla A. Creasey Helene S. Smith Adeline J. Hackett Kimie Fukuyama William L. Epstein Stewart H. Madin 《In vitro cellular & developmental biology. Plant》1979,15(5):342-350
Summary Three human melanoma cell lines derived from one primary and two metastatic tumors from three different patients were characterized
for growth properties usually associated with malignant transformation; these include cell morphology, growth rate, saturation
density, growth in semisolid media, colony-forming ability on contact-inhibited monolayers of normal fibroblasts and epithelial
cells, and tumorigenicity in immunosuppressed mice. Variations in expression of aberrant properties were evident among the
lines. One of the metastatic lines satisfied all the parameters of malignancy tested and the other showed a number of these
properties, whereas the primary essentially fulfilled only one. These results suggest that cultured melanoma cells reflect
the clinical variability often observed among melanoma patients and the metastatic melanoma seems to display a higher degree
of malignant transformation than the primary.
THis work was supported in part by USPHS Grant No. 5 T01 AI00332-06 from the National Institutes of Health, Contract E73-2001-N01-CP-3-3237
from the Virus Cancer Program of the National Cancer Institute, and USPHS Grant No. 0H00714-02 from the National Institute
for Occupational Safety and Health. 相似文献
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Substrate Specificity-Conferring Regions of the Nonribosomal Peptide Synthetase Adenylation Domains Involved in Albicidin Pathotoxin Biosynthesis Are Highly Conserved within the Species Xanthomonas albilineans 下载免费PDF全文
Adeline Renier Eric Vivien Stphane Cociancich Philippe Letourmy Xavier Perrier Philippe C. Rott Monique Royer 《Applied microbiology》2007,73(17):5523-5530
Albicidin is a pathotoxin produced by Xanthomonas albilineans, a xylem-invading pathogen that causes leaf scald disease of sugarcane. Albicidin is synthesized by a nonribosomal pathway via modular polyketide synthase and nonribosomal peptide synthetase (NRPS) megasynthases, and NRPS adenylation (A) domains are responsible for the recognition and activation of specific amino acid substrates. DNA fragments (0.5 kb) encoding the regions responsible for the substrate specificities of six albicidin NRPS A domains from 16 strains of X. albilineans representing the known diversity of this pathogen were amplified and sequenced. Polymorphism analysis of these DNA fragments at different levels (DNA, protein, and NRPS signature) showed that these pathogenicity loci were highly conserved. The conservation of these loci most likely reflects purifying selective pressure, as revealed by a comparison with the variability of nucleotide and amino acid sequences of two housekeeping genes (atpD and efp) of X. albilineans. Nevertheless, the 16 strains of X. albilineans were differentiated into several groups by a phylogenetic analysis of the nucleotide sequences corresponding to the NRPS A domains. One of these groups was representative of the genetic diversity previously found within the pathogen by random fragment length polymorphism and amplified fragment length polymorphism analyses. This group, which differed by three single synonymous nucleotide mutations, contained only four strains of X. albilineans that were all involved in outbreaks of sugarcane leaf scald. The amount of albicidin produced in vitro in agar and liquid media varied among the 16 strains of X. albilineans. However, no relationship among the amount of albicidin produced in vitro and the pathotypes and genetic diversity of the pathogen was found. The NRPS loci contributing to the synthesis of the primary structure of albicidin apparently are not involved in the observed pathogenicity differences among strains of X. albilineans. 相似文献
7.
Polysaccharide intercellular adhesin (PIA) protects Staphylococcus epidermidis against major components of the human innate immune system 总被引:4,自引:0,他引:4
Vuong C Voyich JM Fischer ER Braughton KR Whitney AR DeLeo FR Otto M 《Cellular microbiology》2004,6(3):269-275
The skin commensal and opportunistic pathogen Staphylococcus epidermidis is the leading cause of nosocomial and biofilm-associated infections. Little is known about the mechanisms by which S. epidermidis protects itself against the innate human immune system during colonization and infection. We used scanning electron microscopy to demonstrate that the exopolysaccharide intercellular adhesin (PIA) resides in fibrous strands on the bacterial cell surface, and that lack of PIA production results in complete loss of the extracellular matrix material that has been suggested to mediate immune evasion. Phagocytosis and killing by human polymorphonuclear leucocytes was significantly increased in a mutant strain lacking PIA production compared with the wild-type strain. The mutant strain was also significantly more susceptible to killing by major antibacterial peptides of human skin, cationic human beta-defensin 3 and LL-37, and anionic dermcidin. PIA represents the first defined factor of the staphylococcal biofilm matrix that protects against major components of human innate host defence. 相似文献
8.
Thorsten Langner Adeline Harant Luis B. Gomez-Luciano Ram K. Shrestha Angus Malmgren Sergio M. Latorre Hernn A. Burbano Joe Win Sophien Kamoun 《PLoS genetics》2021,17(2)
Supernumerary mini-chromosomes–a unique type of genomic structural variation–have been implicated in the emergence of virulence traits in plant pathogenic fungi. However, the mechanisms that facilitate the emergence and maintenance of mini-chromosomes across fungi remain poorly understood. In the blast fungus Magnaporthe oryzae (Syn. Pyricularia oryzae), mini-chromosomes have been first described in the early 1990s but, until very recently, have been overlooked in genomic studies. Here we investigated structural variation in four isolates of the blast fungus M. oryzae from different grass hosts and analyzed the sequences of mini-chromosomes in the rice, foxtail millet and goosegrass isolates. The mini-chromosomes of these isolates turned out to be highly diverse with distinct sequence composition. They are enriched in repetitive elements and have lower gene density than core-chromosomes. We identified several virulence-related genes in the mini-chromosome of the rice isolate, including the virulence-related polyketide synthase Ace1 and two variants of the effector gene AVR-Pik. Macrosynteny analyses around these loci revealed structural rearrangements, including inter-chromosomal translocations between core- and mini-chromosomes. Our findings provide evidence that mini-chromosomes emerge from structural rearrangements and segmental duplication of core-chromosomes and might contribute to adaptive evolution of the blast fungus. 相似文献
9.
Tomáš Bílý Shaghayegh Sheikh Adeline Mallet Philippe Bastin David Pérez-Morga Julius Lukeš Hassan Hashimi 《The Journal of eukaryotic microbiology》2021,68(3):e12846
The mitochondrion is crucial for ATP generation by oxidative phosphorylation, among other processes. Cristae are invaginations of the mitochondrial inner membrane that house nearly all the macromolecular complexes that perform oxidative phosphorylation. The unicellular parasite Trypanosoma brucei undergoes during its life cycle extensive remodeling of its single mitochondrion, which reflects major changes in its energy metabolism. While the bloodstream form (BSF) generates ATP exclusively by substrate-level phosphorylation and has a morphologically highly reduced mitochondrion, the insect-dwelling procyclic form (PCF) performs oxidative phosphorylation and has an expanded and reticulated organelle. Here, we have performed high-resolution 3D reconstruction of BSF and PCF mitochondria, with a particular focus on their cristae. By measuring the volumes and surface areas of these structures in complete or nearly complete cells, we have found that mitochondrial cristae are more prominent in BSF than previously thought and their biogenesis seems to be maintained during the cell cycle. Furthermore, PCF cristae exhibit a surprising range of volumes in situ, implying that each crista is acting as an independent bioenergetic unit. Cristae appear to be particularly enriched in the region of the organelle between the nucleus and kinetoplast, the mitochondrial genome, suggesting this part has distinctive properties. 相似文献
10.
Adeline C Ledoux Hélène Sellier Katie Gillies Alessio Iannetti John James Neil D Perkins 《Cell cycle (Georgetown, Tex.)》2013,12(18):3052-3062
Activation of the NFκB signaling pathway allows the cell to respond to infection and stress and can affect many cellular processes. As a consequence, NFκB activity must be integrated with a wide variety of parallel signaling pathways. One mechanism through which NFκB can exert widespread effects is through controlling the expression of key regulatory kinases. Here we report that NFκB regulates the expression of genes required for centrosome duplication, and that Polo-like kinase 4 (PLK4) is a direct NFκB target gene. RNA interference, chromatin immunoprecipitation, and analysis of the PLK4 promoter in a luciferase reporter assay revealed that all NFκB subunits participate in its regulation. Moreover, we demonstrate that NFκB regulation of PLK4 expression is seen in multiple cell types. Significantly long-term deletion of the NFκB2 (p100/p52) subunit leads to defects in centrosome structure. This data reveals a new component of cell cycle regulation by NFκB and suggests a mechanism through which deregulated NFκB activity in cancer can lead to increased genomic instability and uncontrolled proliferation. 相似文献