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Search Results: 1 - 10 of 198416 matches for " Rodney D Adam "
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Phylogenetic status of Pneumocystis from corticosteroid-treated gerbils
XianMin Feng,ChaoJun Wei,Rodney D. Adam,ZiHui Li,SiQi Lu
Science China Life Sciences , 2010, DOI: 10.1007/s11427-010-4074-5
Abstract: Pneumocystis spp. infect the lungs of multiple mammalian species and cause disease in immunosuppressed individuals. The Pneumocystis isolates that have been studied to date fall into two major clades, those from primates and those from rodents. Within each of these clades, different species have been described on the basis of host specificity and differences in sequence and morphology. Here, we demonstrate that dexamethasone immunosuppression consistently results in histologically apparent lung infection in gerbils (28/35 animals). Sequence analysis of the 18S, 5.8S and internal transcribed spacer regions of the rDNA and a portion of the mitochondrial large subunit rDNA demonstrated that this gerbil Pneumocystis is grouped with other rodent Pneumocystis spp., but is distinct from them. Our results suggest that gerbil Pneumocystis differs sufficiently from Pneumocystis species found in other rodents to be considered a separate species.
免疫抑制沙鼠源肺孢子菌的分类地位
冯宪敏, 魏超君, Rodney D. Adam, 李自慧, 卢思奇
中国科学 生命科学 , 2010,
Abstract: 肺孢子菌能够感染多种哺乳动物的肺脏,并在免疫受抑制的个体引起肺孢子菌肺炎.研究表明,肺孢子菌分离株在系统进化树上分为两大枝,二者所含菌株分别来源于灵长类和啮齿类.基于宿主特异性以及DNA序列和形态学差异,每一分枝内的菌株又可分为不同的种.本研究采用地塞米松免疫抑制法,导致沙鼠(28/35)肺组织感染.对18S,5.8SrRNA和rRNA内转录间隔区基因序列,以及线粒体核糖体大亚基基因的部分序列分析表明,本实验沙鼠源肺孢子菌与啮齿类动物来源的同属一枝,但明显区别于其他啮齿类动物来源的菌株,应考虑是一个独立的菌种.
Core histone genes of Giardia intestinalis: genomic organization, promoter structure, and expression
Janet Yee, Anita Tang, Wei-Ling Lau, Heather Ritter, Dewald Delport, Melissa Page, Rodney D Adam, Miklós Müller, Gang Wu
BMC Molecular Biology , 2007, DOI: 10.1186/1471-2199-8-26
Abstract: We identified two copies each of the core histone H2a, H2b and H3 genes, and three copies of the H4 gene, at separate locations on chromosomes 3, 4 and 5 within the genome of Giardia intestinalis, but no gene encoding a H1 linker histone could be recognized. The copies of each gene share extensive DNA sequence identities throughout their coding and 5' noncoding regions, which suggests these copies have arisen from relatively recent gene duplications or gene conversions. The transcription start sites are at triplet A sequences 1–27 nucleotides upstream of the translation start codon for each gene. We determined that a 50 bp region upstream from the start of the histone H4 coding region is the minimal promoter, and a highly conserved 15 bp sequence called the histone motif (him) is essential for its activity. The Giardia core histone genes are constitutively expressed at approximately equivalent levels and their mRNAs are polyadenylated. Competition gel-shift experiments suggest that a factor within the protein complex that binds him may also be a part of the protein complexes that bind other promoter elements described previously in Giardia.In contrast to other eukaryotes, the Giardia genome has only a single class of core histone genes that encode replication-independent histones. Our inability to locate a gene encoding the linker histone H1 leads us to speculate that the H1 protein may not be required for the compaction of Giardia's small and gene-rich genome.Giardia species are binucleated parasitic protists of the group diplomonads [1]. Members of this group differ extensively in their cytology and biochemistry from most other eukaryotes. G. intestinalis is the best explored species of this group [2], and its small genome of 12 Mb containing >9,000 ORFs has been completely sequenced recently [3]. As an important human pathogen of the upper intestinal tract, it was in the center of attention of medical parasitologists for many years [4]. Its peculiar cytology, mos
The Giardia lamblia vsp gene repertoire: characteristics, genomic organization, and evolution
Rodney D Adam, Anuranjini Nigam, Vishwas Seshadri, Craig A Martens, Gregory A Farneth, Hilary G Morrison, Theodore E Nash, Stephen F Porcella, Rima Patel
BMC Genomics , 2010, DOI: 10.1186/1471-2164-11-424
Abstract: The WB Giardia isolate has been sequenced at 10× coverage and assembled into 306 contigs as large as 870 kb in size. We have used this assembly to evaluate the genomic organization and evolution of the vsp repertoire. We have identified 228 complete and 75 partial vsp gene sequences for an estimated repertoire of 270 to 303, making up about 4% of the genome. The vsp gene diversity includes 30 genes containing tandem repeats, and 14 vsp pairs of identical genes present in either head to head or tail to tail configurations (designated as inverted pairs), where the two genes are separated by 2 to 4 kb of non-coding DNA. Interestingly, over half the total vsp repertoire is present in the form of linear gene arrays that can contain up to 10 vsp gene members. Lastly, evidence for recombination within and across minor clades of vsp genes is provided.The data we present here is the first comprehensive analysis of the vsp gene family from the Genotype A1 WB isolate with an emphasis on vsp characterization, function, evolution and contributions to pathogenesis of this important pathogen.Giardia lamblia (syn. G. duodenalis, G. intestinalis) is an anaerobic protist that is medically important as a common cause of intestinal infection and diarrhea [1]. Humans and other susceptible mammals become infected when cysts are ingested from contaminated water or food and excyst into trophozoites in the proximal small intestine. These trophozoites replicate and cause the symptoms of diarrhea. Infections with Giardia are frequently prolonged and malabsorption with weight loss may last for months in the absence of treatment, despite an immune response that would be expected to eradicate the infection. One of the possible reasons for the persistence of infection is antigenic variation of the variant-specific surface proteins (VSPs).A single trophozoite expresses only a single member of this protein family at any one time [2], but may switch expression from one VSP to another in vitro at a r
The HIPASS survey of the Galactic plane in Radio Recombination Lines
Marta I. R. Alves,Mark Calabretta,Rodney D. Davies,Clive Dickinson,Lister Staveley-Smith,Richard J. Davis,Tianyue Chen,Adam Barr
Physics , 2014, DOI: 10.1093/mnras/stv751
Abstract: We present a Radio Recombination Line (RRL) survey of the Galactic Plane from the HI Parkes All-sky Survey and associated Zone of Avoidance survey, which mapped the region l=196degr -- 0degr --52degr and |b| < 5degr at 1.4 GHz and 14.4 arcmin resolution. We combine three RRLs, H168$\alpha$, H167$\alpha$, and H166$\alpha$ to derive fully sampled maps of the diffuse ionized emission along the inner Galactic plane. The velocity information, at a resolution of 20 km/s, allows us to study the spatial distribution of the ionized gas and compare it with that of the molecular gas, as traced by CO. The longitude-velocity diagram shows that the RRL emission is mostly associated with CO gas from the molecular ring and is concentrated within the inner 30degr of longitude. A map of the free-free emission in this region of the Galaxy is derived from the line-integrated RRL emission, assuming an electron temperature gradient with Galactocentric radius of $496\pm100$ K/kpc. Based on the thermal continuum map we extracted a catalogue of 317 compact (<15 arcmin) sources, with flux densities, sizes and velocities. We report the first RRL observations of the southern ionized lobe in the Galactic centre. The line profiles and velocities suggest that this degree-scale structure is in rotation. We also present new evidence of diffuse ionized gas in the 3-kpc arm. Helium and carbon RRLs are detected in this survey. The He line is mostly observed towards HII regions, whereas the C line is also detected further away from the source of ionization. These data represent the first observations of diffuse C RRLs in the Galactic plane at a frequency of 1.4 GHz.
Seasonal activity of the Denali caribou herd, Alaska
Rodney D. Boertje
Rangifer , 1985,
Abstract: Activity of female and young caribou in the Denali herd was studied from June 1978 through April 1980 to help assess the food availability/nutritional status of this reduced population. No nutritional stress was evident as inferred by the greater activity of Denali caribou in late winter compared with starving caribou in West Greenland and by the low proportion of time spent grazing in spring compared with reindeer on overgrazed ranges in Norway. Also, low proportions of time were spent running from insects due to relatively few insects and a high availability of insect-relief sites. A low proportion of time was spent cratering due to windswept conditions. Activity budgets calculated from complete active-rest cycles and accompanied by the duration of active and rest periods may be useful indicators of relative food availability/nutritional status, particularly in late winter/early spring. Duration of active periods is presumably most strongly related to rumen fill, and, thus, food availability. Duration of rest periods was not significantly different among seasons (P<0.05), except when insects, rutting bulls, and, presumably, mushroom-searching altered active-rest cycles. Sesongmessige svingninger av aktiviteten i Denali karibu-flokk, Alaska. Abstract in Norwegian / Sammendrag: Aktiviteten hos simler og ungdyr i Denali karibouflokk ble studert fra juni 1978 til utgangen av april 1980 som hjelpemiddel for bestemme n ringstilbud/ern ringsstatus i denne reduserte karibustamme. Ingen ern ringsmessig stress var penbar, noe som kan utledes av den st rre aktivitet hos Denali karibu p senvinteren sammenlignet med sultende karibu i Vest-Gr nland samt den lave andel av beiting sammenlignet med rein p overbelastede beiter i Norge. Videre ble en lav andel av tiden brukt til r mme fra insekter, fordi insektplagen var relativt liten og at det var lett adgang til omr der der dyrene kunne befri seg fra insektene. Graving krevde ogs liten andel av tid takket v re vindbl ste sn forhold. Aktivitetsbudsjetter beregnet ut fra totale aktivitets-/hvilesykluser kan v re nyttige indikatorer p relativ n ringstilbud/ern ringsstatus, s rlig p senvinter og tidlig v r. Varigheten av aktive perioder er sannsynligvis mest knyttet til vomfylde og, derfor, til n ringstilbud eller n ringstilgjengelighet. Varigheten av hvileperioder var ikke signifikant forskjellig mellom sesonger (P<0.05), unntatt n r insekter, brunstige bukker og, sannsynligvis ogs , sopps king forandret aktivitet-/hvilesykluser.
Structure and Strength of Dislocation Junctions: An Atomic Level Analysis
D. Rodney,R. Phillips
Physics , 1998, DOI: 10.1103/PhysRevLett.82.1704
Abstract: The quasicontinuum method is used to simulate three-dimensional Lomer-Cottrell junctions both in the absence and in the presence of an applied stress. The simulations show that this type of junction is destroyed by an unzipping mechanism in which the dislocations that form the junction are gradually pulled apart along the junction segment. The calculated critical stress needed for breaking the junction is comparable to that predicted by line tension models. The simulations also demonstrate a strong influence of the initial dislocation line directions on the breaking mechanism, an effect that is neglected in the macroscopic treatment of the hardening effect of junctions.
Phase Field Methods and Dislocations
D. Rodney,A. Finel
Physics , 2001,
Abstract: We present a general formalism for incorporating dislocations in Phase Field methods. This formalism is based on the elastic equivalence between a dislocation loop and a platelet inclusion of specific stress-free strain related to the loop Burgers vector and normal. Dislocations are thus treated as platelet inclusions and may be coupled dynamically to any other field such as a concentration field. The method is illustrated through the simulation of a Frank-Read source and of the shrinkage of a loop in presence of a concentration field.
Writing and Rewriting the Instructional Design Case: A View from Two Sides
Craig D. Howard, Rodney Myers
International Journal of Designs for Learning , 2011,
Abstract: This article analyzes five problem areas educators grapple with when writing designs cases about learning interventions. The article is written from the vantage point of IJDL’s assistant editor who edited, reviewed, and coordinated the reviews of design cases over a period of two years while also writing his own design case (Howard & Myers, 2010: International Journal of Designs for Learning). The knowledge building genre of the instructional design case is viewed from the perspective of commonalities between articles published in a Tech Trends feature, the Instructional Design Portfolio, and this venue. The areas of concern common among reviews for these publications shed light on how the design case is developing into a rigorous form of educational inquiry. The areas of concern brought up in reviews of cases are discussed in light of the author’s first hand experiences of satisfying reviewers’ concerns and, in turn, coaching other educators through the process of a finalized design case. Those common areas are: (1) situating the design, (2) describing the design, (3) depicting the experience of the design, (4) developing trustworthiness through transparency, analysis, and reflection (5) removing aspects of design cases which confound their purpose. Specific examples from design cases that have gone through peer review describe how author-educators may approach the dissemination of design precedent through the careful documentation of pedagogical designs.
Creating video-annotated discussions: An asynchronous alternative
Craig D. Howard,Rodney Myers
International Journal of Designs for Learning , 2010,
Abstract: In this article the authors illustrate the design and development of a pedagogical intervention using video annotations in a pre-service teacher education courrse. An annotation platform was selected and video was shot to create a video backdrop on which asynchronous discussions would take place. The article addresses design considerations in the selection of video, the editing process, and the development of a tutorial to lead learners through their first experience with this form of discussion. Learner participation samples were collected, and an analysis of the design process concludes the article.
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