bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Coding and Spacer Region Sequences of Chromosomal rRNA‐Coding Genes of Two Sequevars of Pneumocystis carinii
Authors: ORTIZ‐RIVERA MARIA , LIU YONG , FELDER REGINA , LEIBOWITZ MICHAEL J. 
Published: May 2007

ABSTRACTTwo distinct sequevars, denoted Pc1 and Pc2, of the opportunistic pathogen Pneumocystis carinii have been previously identified based on the sequence of their 26S rRNA genes, the location of group I self‐splicing introns and pulsed field electrophoretic patterns of chromosomal DNA. This study shows that the sequences of 16S and 5.8S rRNA genes also vary between these sequevars, and that greater variation was seen in the internal transcribed spacer regions. Polymerase chain reaction and restriction analysis can distinguish between these sequevars.
A Redescription of the Morphology of Onychodromus grandis Stein 1859 and the Systematic Implications of its Morphogenesis
Authors: SZABÓ ANDRÁS , WILBERT NORBERT 
Published: May 2007

ABSTRACTMorphology and morphogenesis of Onychodromus grandis (Hypotrichida, Ciliata) were studied in vivo and in protargolimpregnated preparations. The species was isolated from halophyte communities in astatic shallow waters of the Hortobágy National Park, Hungary. The species has two well developed dorsal horns. According to some characteristics (number and situation of ventral cirri) our findings differ from Stein's description in 1859. Individuals of the population studied had 9 ventral cirri in 3 rows. Nine rows of dorsal kineties were found on the back. It was found that the oral primordium develops in the vicinity of the transverse cirri. In O. grandis marginal primordia are formed in the marginal rows with the participation of parental cirri. This is also true for Laurentiella acuminata. Dorsal fragmentation of O. grandis displays similarity to that of L. acuminata, considering especially the development of the numerous small dorso‐marginal kineties. There are certain similarities among O. quadricornutus, O. indica, L. acuminata, Stylonychia vorax and O. grandis in the development of the ventral and dorsal pattern and in some morphogenetical events. The remarkable differences in the interphase cells can be related simply to the significantly different numbers of cortical units (number of cirri). and also to the various cell sizes.
Phylogenetic Relationships Among Anuran Trypanosomes as Revealed by Riboprinting
Authors: CLARK C. GRAHAM , MARTIN DONALD S. , DIAMOND LOUIS S. 
Published: May 2007

ABSTRACTTwenty trypanosome isolates from Anura (frogs and toads) assigned to several species were characterized by riboprinting–restriction enzyme digestion of polymerase chain reaction amplified small subunit ribosomal RNA genes. Restriction site polymorphisms allowed distinction of all the recognized species and no intraspecific variation in riboprint patterns was detected. Phylogenetic reconstruction using parsimony and distance estimates based on restriction fragment comigration showed Trypanosoma chattoni to be only distantly related to the other species, white T. ranarum and T. fallisi appear to be sister taxa despite showing non‐overlapping host specificities.
Ecological Genetics of Tetrahymena thermophila: Mating Types, i‐Antigens, Multiple Alleles and Epistasis
Authors: DOERDER F. PAUL , ARSLANYOLU MUHITTIN , SAAD YASSER , KACZMAREK MICHELLE , MENDOZA MANUEL , MITA BARRY 
Published: May 2007

ABSTRACTUntil recently, Tetrahymena thermophila has rarely been isolated from nature. With improved sampling procedures, T. thermophila has been found in ponds in many northeastern states. The availability of resident populations makes possible both population and ecological genetic studies. All seven known mating types have been recovered; no eighth mating type has been found. Crosses among whole‐genome homozygotes derived from Pennsylvania isolates reveal a spectrum genotypes with mating type alleles resembling traditional A (IV‐ and VII‐) and B(I‐) categories. The genotypes differ significantly with respect to mating type frequency, both among themselves and from previously described genotypes. One A‐category genotype appears to lack mating type II, while one A‐category and all B‐category genotypes have low frequencies of mating type III, thus accounting for the low frequency of III in the pond. The low frequency of III in all five B‐category genotypes examined suggests that the founding allele in this region was low for III. These and other differences are discussed both in terms of mating type frequencies in the pond and in terms of the possible molecular structure of mat alleles. By contrast, numerous variants of the cell surface immobilization antigen are found in addition to the previously described i‐antigens. Variants of the known SerH alleles include those with restriction fragment length polymorphisms and temperature sensitivity as well as alleles with new antigenic specificity. Multiple alleles are present in single ponds. Genes exhibiting serially dominant epistasis over SerH genes also are found. In two instances (K and C), families of antigenically similar polypeptides are expressed in place of H i‐antigen. Molecular weight differences suggest that these paralogous i‐antigen genes evolve by gene duplication and unequal crossing over within central repeats. The existence of complex patterns of epistasis together with seasonal changes in i‐ag frequencies suggest that i‐ag play an important, but as yet unknown, ecological role related to the occurrence of frequent conjugation.
Molecular Identification of Nanoplanktonic Protists Based on Small Subunit Ribosomal RNA Gene Sequences for Ecological Studies1
Authors: LIM EE LIN 
Published: May 2007

ABSTRACTNanoplanktonic protists are comprised of a diverse assemblage of species which are responsible for a variety of trophic processes in marine and freshwater ecosystems. Current methods for identifying small protists by electron microscopy do not readily permit both identification and enumeration of nanoplanktonic protists in field samples. Thus, one major goal in the application of molecular approaches in protistan ecology has been the detection and quantification of individual species in natural water samples. Sequences of small subunit ribosomal RNA (SSU rRNA) genes have proven to be useful towards achieving this goal. Comparison of sequences from clone libraries of protistan SSU rRNA genes amplified from natural assemblages of protists by the polymerase chain reaction (PCR) can be used to examine protistan diversity. Furthermore, oligonucleotide probes complementary to short sequence regions unique to species of small protists can be designed by comparative analysis of rRNA gene sequences. These probes may be used to either detect the RNA of particular species of protists in total nucleic acid extracts immobilized on membranes, or the presence of target species in water samples via in situ hybridization of whole cells. Oligonucleotide probes may also serve as primers for the selective amplification of target sequences from total population DNA by PCR. Thus, molecular sequence information is becoming increasingly useful for identifying and enumerating protists, and for studying their spatial and temporal distribution in nature. Knowledge of protistan species composition, abundance and variability in an environment can ultimately be used to relate community structure to various aspects of community function and biogeochemical activity.
Oxidation of Alanine, Acetate, Glutamate, and Succinate by Digitonin‐Permeabilized Leishmania major Promastigotes
Authors: BLUM J. J. 
Published: May 2007

ABSTRACT Leishmania major promastigotes were treated with digitonin and the rates at which [1 ‐14C]acetate, [1,4‐14C]succinate, [1‐14C]glutamate, and [U‐14C]alanine are oxidized were measured in the presence of suitable cofactors. Acetate was oxidized at the lowest rate of the four substrates examined, even in the presence of added NAD, CoA, ADP and acetyl‐CoA synthase. Its rate of oxidation was negligible if the permeabilized cells were washed before the cofactors were added, indicating the requirement for an as yet unknown factor. Succinate was oxidized at a rate much higher than the very slow rate at which it is oxidized by intact cells. Its rate of oxidation was strongly inhibited by antimycin A, but that of glutamate was scarcely affected. Fumarate inhibited the rate of oxidation of acetate, glutamate, and succinate, but increased that of alanine, Ca++ inhibited the rates of oxidation of alanine and succinate, but not of acetate or glutamate. Increasing the osmolality by addition of mannitol partially inhibited the rate of oxidation of alanine but had little effect on that of glutamate. These results show that appreciable transaminase activity remains in the permeabilized cells and support earlier data indicating the presence of a branched NAD‐to‐cytochrome oxidase system. These results also provide preliminary information on the sensitivity of the two branches to Ca++, hyperosmolality, and Krebs cycle intermediates
A Nucleoside Diphosphate Kinase from Paramecium tetraurelia with Protein Kinase Activity
Authors: ANN KYOUNG‐SOOK , NELSON DAVID L. 
Published: May 2007

ABSTRACTNucleoside diphosphate kinase (NDP kinase) from Paramecium was purified to homogeneity. The native enzyme was 80 kDa (by gel filtration), with subunits of 18 and 20 kDa. Near the amino terminus, 15 of 20 residues were identical with those in human NDP kinase, and 17 of 20 with the awd gene product from Drosophila. NDP kinase bound α‐labeled ATP and GTP, and a photoreactive GTP analog labeled both subunits. Purified NDP kinase underwent autophosphorylation on a histidine and a serine residue using either ATP or GTP as a substrate. The enzyme also catalyzed acid‐stable phosphorylation of casein and phosvitin. This protein kinase activity is distinct from the histidine phosphorylation that is part of the NDP kinase catalytic cycle. Antiserum against the purified protein from Paramecium cross‐reacted with 16‐ to 20‐kDa proteins in most species tested, and with a larger protein (44 kDa) in Paramecium, Xenopus, and two human lines. The multiple forms (20 and 44 kDa) of the NDP kinase in Paramecium and its protein kinase activity, suggest that the protein is more than a housekeeping enzyme; it may have regulatory roles such as those of the NDP kinase‐like awd protein of Drosophila and Nm23 protein of humans.
In Vitro Cultivation of the Vascular Phase of Sarcocystis singaporensis
Authors: JÄKEL THOMAS , HENKE MARION , WEINGARTEN BERND , KLIEMT DAMARIS , SEIDINGER SILVIA 
Published: May 2007

ABSTRACT.To establish an in vitro culture system for the precystic phase of Sarcocystis singaporensis, we initially tested various excysting fluids for sporocysts. An excysting fluid containing 2.5% bovine taurocholate and 10% bile of the specific intermediate host, Rattus norvegicus, in RPMI medium was the most suitable resulting in excystation of 80% of the sporozoites. Subsequently, we identified brain endothelial cells and pneumonocytes of the rat to promote growth of sporozoites to schizonts. Hepatoma, fibroblastic, or myoblastic cells were not suitable for the parasite's development. First‐generation schizonts were seen at days 3‐10 postinoculation (PI); a distinct second peak of schizogonic development only occurred in endothelial cells at days 14‐18 PI. First‐generation schizonts were 26.0 (± 3.8) μm in diameter and contained 32‐50 merozoites, second‐generation schizonts measured 34.4 (± 10.6) μm and contained 54‐72 merozoites. Merozoite yield at large‐scale culture conditions (75 cm2 flasks) using pneumonocytes as host cells was relatively low. Ultrastructurally, sporozoites and merozoites were quite similar to corresponding stages of other Sarcocystis species. With regard to host cell specificity and developmental kinetics, in vitro cultivation showed close similarities to the situation in vivo.
A Novel Member of the Cyclin‐Dependent Kinase Family in Paramecium tetraurelia
Authors: ZHANG HONG , BERGER JAMES D. 
Published: May 2007

ABSTRACTPassage through the cell cycle in eukaryotes requires the successive activation of different cyclin‐dependent protein kinases. Here, we describe the identification and characterization of a novel class of cyclin‐dependent protein kinase, termed Cdk2, in the ciliate Paramecium tetraurelia. It is 301 amino acids long, 7 amino acids shorter than Cdk1, the CDK that is associated with macronuclear DNA synthesis. All the catalytic domains typical of protein kinases can be located within the sequence and putative regulatory phosphorylation sites equivalent to Thr14, Tyr15, and Thr161 in human CDK1 are also conserved. The‘PSTAIRE’region characteristic of most CDKs is perfectly conserved. Cdk2 shares only 48% homology to Cdk1 at the amino acid level, suggesting that the evolutionary separation of Cdk1 and Cdk2 is ancient, and implying that they have different roles in cell cycle regulation. Like Cdk1, Cdk2 does not bind to yeast pl3suc1, even though it has better conservation of pl3suc1 binding sites than Cdk1 does. The Cdk2 protein level is relatively constant throughout the vegetative cell cycle. Cdk2 exhibits kinase activity towards bovine histone H1 in vitro with the maximal level late in the cell cycle, suggesting it may be involved in the regulation of cytokinesis. Our results further support the view that an analogue of the cyclin‐dependent kinase cell cycle regulatory system like that of yeast and higher eukaryotic cells operates in Paramecium and that a family of cyclin‐dependent kinases may control different aspects of the Paramecium cell cycle.
Characterization of an α‐Tubulin Gene of Cryptosporidium parvum
Authors: BONAFONTE MARÍA‐TERESA , GARMON DEANNA , MEAD JAN R. 
Published: May 2007

ABSTRACTA gene encoding an α‐tubulin of Cryptosporidium parvum was isolated and characterized. It had no introns, and encoded a 441‐amino acid protein whose predicted ORF represented a typical α‐tubulin protein with a MW of 50.5 kDa. This tubulin had an amino acid sequence similarity with Apicomplexa Plasmodium falciparum and Toxoplasma gondii higher than 88% and shared a number of conserved motifs.
The Influence of UV Radiation on Protistan Evolution
Authors: ROTHSCHILD LYNN J. 
Published: May 2007

ABSTRACTUtraviolet radiation has provided an evolutionary challenge to life on Earth. Recent increases in surficial ultraviolet B fluxes have focused attention on the role of UV radiation in protistan ecology, cancer, and DNA damage. Exploiting this new wealth of data, I examine the possibility that ultraviolet radiation may have played a significant role in the evolution of the first eukaryotes, that is, protists. Protists probably arose well before the formation of a significant ozone shield, and thus were probably subjected to substantial ultraviolet A, ultraviolet B, and ultraviolet C fluxes early in their evolution. Evolution consists of the generation of heritable variations and the subsequent selection of these variants. Ultraviolet radiation has played a role both as a mutagen and as a selective agent. In its role as a mutagen, it may have been crucial in the origin of sex and as a driver for molecular evolution. As a selective agent, its influence has been broad. Discussed in this paper are the influence of ultraviolet radiation on biogeography, photosynthesis, and desiccation resistance.
Direct loading of Nobel Direct® and Nobel Perfect® one‐piece implants: a 1‐year prospective clinical and radiographic study
Authors: Östman Per‐Olov , Hellman Mats , Albrektsson Tomas , Sennerby Lars 
Published: May 2007

AbstractObjectives: The aim of this prospective study was to evaluate the Nobel Direct® and Nobel Perfect® one‐piece implants (OPIs) when used for immediate function.Material and methods: Forty‐eight patients were provided with 115 OPIs for loading with a provisional crown or a bridge within 24 h and followed for at least 12 months with clinical and radiographic examinations. A group of 97 patients previously treated under identical conditions by the same team with 380 two‐piece implants (TPIs) for immediate loading in the mandible and maxilla served as the reference group.Results: Six (5.2%) OPIs failed during the follow‐up due to extensive bone loss. Five (1.3%) implants failed in the reference group. After 1 year, the mean marginal bone loss was 2.1 mm (SD 1.3) for OPIs and 0.8 mm (SD 1) for TPIs. 20% of OPIs showed more than 3 mm of bone loss compared with 0.6% for TPIs. When compensating for vertical placement depth, OPIs still showed a lower marginal bone level and thus more exposed threads than TPIs. Depending on the criteria used, the success rate for OPIs was 46.1% or 72.2% compared with 85% or 91.6% for TPIs.Conclusions: The Nobel Direct® and Nobel Perfect® OPIs show lower success rates and more bone resorption than TPIs after 1 year in function. Factors such as implant design, insertion depth, rough surface towards the mucosa, in situ preparation and immediate loading may have an influence on the clinical outcome.
Gingival crevicular fluid and serum leptin: their relationship to periodontal health and disease
Authors: Karthikeyan B. V. , Pradeep A. R. 
Published: May 2007

AbstractBackground & Aims: Leptin is a pleiotrophic hormone produced by adipose tissue and it plays an important role in protection of the host from inflammation and infection. The purpose of this study is to determine the presence of leptin in gingival crevicular fluid (GCF) and serum samples and to find out their association, if any.Methods: Forty two subjects were selected based on their body mass index and were divided into three groups of 14 each; healthy (Group I), chronic gingivitis (Group II) and chronic periodontitis (Group III). GCF samples (by microcapillary pipettes) and serum samples (by venipuncture) were collected to estimate the levels of leptin using enzyme linked immunosorbent assay kit.Results: The highest mean leptin concentration in GCF was obtained for Group I (2658 pg/ml) and the least for Group III (1312 pg/ml). In contrast, the lowest serum leptin concentration was obtained for the Group I (8783 pg/ml), and the highest for Group III (12082 pg/ml). This suggests a negative correlation of GCF leptin concentration and a positive correlation of serum leptin concentration as the clinical attachment level progresses (p<0.05).Conclusion: These results suggest that greater the periodontal destruction, lesser is the GCF leptin concentration and greater the serum leptin concentration.
Are there common human leucocyte antigen associations in juvenile idiopathic arthritis and periodontitis?
Authors: Reichert Stefan , Stein Jamal , Fuchs Corinna , John Vera , Schaller Hans‐Günter , Machulla Helmut K. G. 
Published: May 2007

AbstractAim: The aim of this study was to evaluate common human leucocyte antigen (HLA) associations in patients with juvenile idiopathic arthritis (N=110), in patients with generalized aggressive periodontitis (N=50) and in patients with chronic periodontitis (N=102) in comparison to healthy controls (no periodontitis, no arthritis N=102).Material and methods: HLA‐class I and II markers were determined using microlymphocytotoxicity test and polymerase chain reaction with sequence specific primers. Statistical analyses were carried out by χ2‐test and Yates' correction. If n<5 Fisher's exact test was performed. In the arthritis group the influence of HLA on attachment loss was determined by using backwards logistic regression considering age, gender, smoking, plaque level, and the duration of the disease.Results: In comparison with the controls HLA‐DRB3* occurred more frequently in both females suffering from juvenile idiopathic arthritis (74.58%versus 54.54%, p=0.024) and females suffering from chronic periodontitis (73.02%versus 54.54%, p=0.035). Furthermore, among patients with juvenile idiopathic arthritis an increased odds ratio (OR) for attachment loss was found in subjects who expressed HLA‐A*01 (OR=4.6, p=0.014) or HLA‐A*01:DRB3* (OR=4.3, p=0.031).Conclusion: HLA‐DRB3* could be a common putative risk indicator for juvenile idiopathic arthritis and chronic periodontitis among females.
Literature, Social Science, and the Development of American Migration Narratives in the Twentieth Century
Authors: Royston Battat Erin 
Published: May 2007

AbstractThis article traces the complementary relationship between social science and American migration narratives in the twentieth century, with particular attention to texts produced in the Depression era, and to more recent scholarship on the literature of African‐American migration. While social scientists borrowed the tools of literary artists to understand migration in the 1920s, writers in the Depression era employed sociological and anthropological methods to bring the plight of the southern migrant into the public consciousness. Narratives of southern white, Mexican‐American, and African‐American migration proliferated within a social scientific paradigm that depicted the migrant as a marginal figure, and the emergence of the concept of ‘ethnicity’ shaped the representation of internal migrants. Social science continues to influence literary criticism, as critics employ sociological and anthropological concepts to understand migration narratives.
Clinical outcomes of magnetic resonance imaging in blunt cervical trauma
Authors: Labattaglia Matthew P , Cameron Peter A , Santamaria Mark , Varma Dinesh , Thomson Kevin , Bailey Michael , Kossmann Thomas 
Published: May 2007

AbstractObjectives:  To determine whether MRI of the cervical spine resulted in a change in management of patients with blunt trauma and normal plain X‐ray (XR)/CT of the cervical spine.Methods:  An explicit chart review was conducted of patients seen at a Level 1 trauma centre over a 1 year period. Clinical details were extracted from the charts of patients with blunt trauma who had a normal plain XR and CT scan of the cervical spine and who underwent cervical spine MRI. A comparison of clinical details was made between those with a normal/abnormal MRI secondary to the acute injury.Results:  One hundred and thirty‐four patients met entry criteria. Discharge non‐operative management of the cervical spine was associated with a change in management by the MRI result (P < 0.0001) where MRI of the cervical spine occurred a median of 3 days (interquartile range 0–4.5, range 0–137) after the injury. The MRI occurred before discharge 90% of the time in both groups. Operative management occurred in three patients and was delayed until after first outpatient review in two patients.Conclusions:  An abnormal MRI after normal plain XR and CT cervical spine studies resulted in a change in non‐operative management at discharge. Early MRI resulted in one patient receiving surgery before discharge. No unstable injuries were detected by MRI that were not evident on plain XR or CT cervical spine.
A polymorphism in FAS gene promoter correlated with circulating soluble FAS levels
Authors: Mahfoudh W. , Bel Hadj Jrad B. , Romdhane A. , Chouchane L. 
Published: May 2007

SummaryThe −670FAS (A/G) polymorphism and elevated concentrations of the soluble form of FAS (sFAS) have been associated with neoplasic and autoimmune diseases. This polymorphism in the Fas promoter gene could modulate the transcription of Fas expression and therefore, contribute to these pathologies. The in vivo functional significance of the FAS polymorphism was investigated by assessing the correlation between FAS genotypes and the serum‐circulating FAS (sFAS) levels. We determined the FAS polymorphism distributions by restriction fragment‐length polymorphism–polymerase chain reaction in 170 normal subjects. We used enzyme‐linked immunosorbent assay to evaluate the sFAS levels in 44 of these individuals. Assessment of the concentration of sFAS indicated that the level of sFAS in subjects carrying the FAS‐A/A genotype was significantly higher than that of those carrying the G/G genotype (3.90 ng mL−1 vs. 3.12 ng mL−1, P = 0.035).Our results demonstrated that FAS promoter polymorphism was significantly associated with the level of soluble FAS production in normal subjects.