Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 71
Filtrar
1.
J Phys Condens Matter ; 33(44)2021 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-34348242

RESUMO

Atomic precision advanced manufacturing (APAM) leverages the highly reactive nature of Si dangling bonds relative to H- or Cl-passivated Si to selectively adsorb precursor molecules into lithographically defined areas with sub-nanometer resolution. Due to the high reactivity of dangling bonds, this process is confined to ultra-high vacuum (UHV) environments, which currently limits its commercialization and broad-based appeal. In this work, we explore the use of halogen adatoms to preserve APAM-derived lithographic patterns outside of UHV to enable facile transfer into real-world commercial processes. Specifically, we examine the stability of H-, Cl-, Br-, and I-passivated Si(100) in inert N2and ambient environments. Characterization with scanning tunneling microscopy and x-ray photoelectron spectroscopy (XPS) confirmed that each of the fully passivated surfaces were resistant to oxidation in 1 atm of N2for up to 44 h. Varying levels of surface degradation and contamination were observed upon exposure to the laboratory ambient environment. Characterization byex situXPS after ambient exposures ranging from 15 min to 8 h indicated the Br- and I-passivated Si surfaces were highly resistant to degradation, while Cl-passivated Si showed signs of oxidation within minutes of ambient exposure. As a proof-of-principle demonstration of pattern preservation, a H-passivated Si sample patterned and passivated with independent Cl, Br, I, and bare Si regions was shown to maintain its integrity in all but the bare Si region post-exposure to an N2environment. The successful demonstration of the preservation of APAM patterns outside of UHV environments opens new possibilities for transporting atomically-precise devices outside of UHV for integrating with non-UHV processes, such as other chemistries and commercial semiconductor device processes.

2.
Eur Rev Med Pharmacol Sci ; 23(21): 9625-9632, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31773713

RESUMO

OBJECTIVE: To investigate the effects of ranolazine on the cardiac function and myocardial apoptosis in rats with heart failure and its possible mechanisms. MATERIALS AND METHODS: Thirty Wistar rats were randomly divided into sham operation (negative control; NC), chronic heart failure (CHF), and ranolazine groups. Suprarenal abdominal aortic coarctation was used to induce CHF in rats. Five weeks later, rats in the ranolazine group received ranolazine (50 mg/kg) daily, whereas those in the CHF group received normal saline. After 4 weeks, changes in hemodynamic parameters, cardiac structure and pathology, myocardial apoptosis, and protein expression were assessed. RESULTS: The left ventricular end-diastolic pressure (LVEDP) significantly increased in the CHF group; whereas the maximal rate of left ventricular pressure rise and fall (±dp/dtmax) decreased, compared to those in the NC group. Ranolazine significantly reduced LVEDP and increased ±dp/dtmax (p<0.01), compared to those in the CHF group. Severe impairment of cardiomyocytes was observed in the CHF group with evident inflammation; however, ranolazine reversed these deficits. Rats in the CHF group exhibited an increase in TUNEL-positive cells, which was inhibited by ranolazine, where the apoptotic index significantly decreased in ranolazine-treated rats (p<0.01). Also, ranolazine downregulated caspase-9 expression and upregulated pAKT and Bcl-2 expression in rat cardiomyocytes. Moreover, ranolazine significantly inhibited myocardial apoptosis and caspase-9 expression, promoted AKT phosphorylation, and upregulated pAKT and Bcl-2 expression in vitro, compared to those in the control group (p<0.001). LY294002 inhibited ranolazine-induced suppression of myocardial apoptosis (p<0.001). CONCLUSIONS: Ranolazine improved cardiac function and inhibited myocardial apoptosis in rats with CHF, which could be attributed to the regulation of AKT phosphorylation.


Assuntos
Fármacos Cardiovasculares/farmacologia , Insuficiência Cardíaca/tratamento farmacológico , Ranolazina/farmacologia , Animais , Apoptose/efeitos dos fármacos , Fármacos Cardiovasculares/administração & dosagem , Células Cultivadas , Modelos Animais de Doenças , Insuficiência Cardíaca/metabolismo , Insuficiência Cardíaca/patologia , Injeções Intraperitoneais , Masculino , Ranolazina/administração & dosagem , Ratos , Ratos Wistar
3.
J Helminthol ; 94: e58, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-31272516

RESUMO

The order Onchoproteocephalidea (Eucestoda) was recently erected to accommodate the hook-bearing tetraphyllideans and the proteocephalideans, which are characterized by internal proglottization and a tetra-acetabulate scolex. The recognized subfamilies in the Proteocephalidae appeared to be non-monophyletic based on 28S recombinant DNA (rDNA) sequence data. Other molecular markers with higher phylogenetic resolution, such as large mitochondrial DNA fragments and multiple genes, are obviously needed. Thus the mitochondrial genome of Gangesia oligonchis, belonging to the putative earliest diverging group of the Proteocephalidae, was sequenced. The circular mitogenome of G. oligonchis was 13,958 bp in size, and contained the standard 36 genes: 22 transfer RNA genes, two rRNA genes and 12 protein-coding genes, as well as two major non-coding regions. A short NCR and a large NCR (lNCR) region were 216 bp and 419 bp in size, respectively. Highly repetitive regions in the lNCR region were detected with that of 11 repeat units. The mitogenome of G. oligonchis shared 71.1% nucleotide identity with Testudotaenia sp. WL-2016. Phylogenetic analyses of the complete mitochondrial genomes with Bayesian inference and maximum likelihood methods indicated that G. oligonchis formed a sister clade with Testudotaenia sp. WL-2016 with maximum support. The ordinal topology is (Caryophyllidea, (Diphyllobothriidea, (Bothriocephalidea, (Onchoproteocephalidea, Cyclophyllidea)))). The mitogenomic gene arrangement of G. oligonchis was identical to that of Testudotaenia sp. WL-2016. Both mitogenomic and nuclear sequence data for many more taxa are required to effectively explore the inter-relationships among the Onchoproteocephalidea.


Assuntos
Cestoides/classificação , Cestoides/genética , Genoma Mitocondrial , Filogenia , Animais , Teorema de Bayes , Peixes-Gato/parasitologia , DNA Mitocondrial/genética , Análise de Sequência de DNA
4.
Artigo em Chinês | MEDLINE | ID: mdl-30419681
5.
J Helminthol ; 92(4): 455-466, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28660842

RESUMO

Despite the worldwide distribution and pathogenicity of monogenean parasites belonging to the largest helminth genus, Dactylogyrus, there are no complete Dactylogyrinae (subfamily) mitogenomes published to date. In order to fill this knowledge gap, we have sequenced and characterized the complete mitogenome of Dactylogyrus lamellatus, a common parasite on the gills of grass carp (Ctenopharyngodon idella). The circular mitogenome is 15,187 bp in size, containing the standard 22 tRNA genes, 2 rRNA genes, 12 protein-encoding genes and a long non-coding region (NCR). There are two highly repetitive regions in the NCR. We have used concatenated nucleotide sequences of all 36 genes to perform the phylogenetic analysis using Bayesian inference and maximum likelihood approaches. As expected, the two dactylogyrids, D. lamellatus (Dactylogyrinae) and Tetrancistrum nebulosi (Ancyrocephalinae), were closely related to each other. These two formed a sister group with Capsalidae, and this cluster finally formed a further sister group with Gyrodactylidae. Phylogenetic affinity between Dactylogyrinae and Ancyrocephalinae was further confirmed by the similarity in their gene arrangement. The sequencing of the first Dactylogyrinae, along with a more suitable selection of outgroups, has enabled us to infer a much better phylogenetic resolution than recent mitogenomic studies. However, as many lineages of the class Monogenea remain underrepresented or not represented at all, a much larger number of mitogenome sequences will have to be available in order to infer the evolutionary relationships among the monogeneans fully, and with certainty.


Assuntos
Infecções por Cestoides/veterinária , Doenças dos Peixes/parasitologia , Genoma Helmíntico , Genoma Mitocondrial , Filogenia , Platelmintos/genética , Animais , Sequência de Bases , Carpas/parasitologia , Infecções por Cestoides/parasitologia , Brânquias/parasitologia , Masculino , Dados de Sequência Molecular , Platelmintos/classificação , Platelmintos/isolamento & purificação , Análise de Sequência de DNA
6.
Zhonghua Yi Xue Za Zhi ; 97(2): 127-130, 2017 Jan 10.
Artigo em Chinês | MEDLINE | ID: mdl-28088958

RESUMO

Objective: To discuss the clinical safety and efficacyof endovascular aneurysm repair (EVAR) for aortic pseudoaneurysms. Methods: From October 2008 to October 2015, 13 patients (11 male, 2 female, with a mean age of 55.6) with aortic pseudoaneurysms treated by EVAR wereenrolled. All the 13 casesunderwentcomputed tomographic arteriography (CTA). The etiology diagnosis withdescendingaortic pseudoaneurysms, infected abdominal aortic pseudoaneurysms, abdominal aortic pseudoaneurysmsin Behcet's syndrome, and uncertain reasons were 4, 4, 4, and 1 case, respectively. Results: In this group, 14 stentswere planted.All the patients hadno accidents and complications in perioperative period.Twelve patients were successfully followed up, 1 patient died of recurrent abdominal aortic pseudoaneurysmsin Behcet's syndrome, and 1 patient with recurrent infected abdominal aortic pseudoaneurysm wascured by pseudoaneurysm resection and extra-anatomic bypass grafting. Concluson: EVAR is a safe and effective option for aortic pseudoaneurysms.


Assuntos
Falso Aneurisma , Implante de Prótese Vascular , Procedimentos Endovasculares , Angiografia , Aorta Abdominal , Aneurisma da Aorta Abdominal , Síndrome de Behçet , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Tomografia Computadorizada por Raios X , Resultado do Tratamento
7.
J Biol Regul Homeost Agents ; 29(4): 841-6, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26753645

RESUMO

Traumatic shock is a serious threat to life and health. The aim of this study is to investigate the effect of different resuscitation fluid compositions on the emergency resuscitation for patients with traumatic shock. Sixty patients were enrolled and divided into two groups, Group A and Group B. The patients in Group A were treated with resuscitation fluid, with 2:1 ratio of crystal (0.9% sodium chloride injection) and colloid (hydroxyethyl starch 40 injection). The patients in Group B were treated with hypertonic sodium chloride hydroxyethyl starch 40 injection (HSH40). Both vital signs and fluid dosage were monitored and recorded. At the beginning of resuscitation (T0) and 30 min (T1), 60 min (T2) and 120 min (T3) after resuscitation, indicator parameters including hemoglobin (HB), hematocrit (HCT), prothrombin time (PT), arterial blood lacic acid (LA) and C-reactive protein (CRP) were monitored and recorded. Tissue oxygenation and hemodynamic profile were also analyzed. At T1, T2and T3after fluid resuscitation, the heart rates of the patients in Group B were lower than those in Group A, whereas the average arterial pressure in Group B was significantly higher than that in Group A. Notably, significant decreases of HB and HCT were detected at T1, T2and T3compared with T0 in Group A. In contrast, no significant difference was shown in detected HCT at T2and T3compared with T0 in Group B, while the detected HB value was smaller. a statistically significant decrease of LA was detected at T1, T2and T3in Group A and Group B compared with that at T0. At T2and T3in Group A and Group B, a statistically significant increase of PT was detected compared with the beginning of resuscitation. At T2and T3after resuscitation, CRP in both Group A and Group B was significantly increased compared with that upon admission to hospital, and was lower in Group B than in Group A.


Assuntos
Ressuscitação , Choque Traumático/terapia , Emergências , Feminino , Hematócrito , Hemoglobinas/análise , Humanos , Derivados de Hidroxietil Amido/administração & dosagem , Masculino , Solução Salina Hipertônica/administração & dosagem , Choque Traumático/sangue
8.
J Fish Dis ; 37(1): 11-20, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24341506

RESUMO

The original description of Myxobolus hearti is supplemented with new data on spore morphology, histopathology and molecular phylogeny. Myxobolus hearti are found in the heart ventricle of the gibel carp, Carassius gibelio (Bloch), where they form whitish oval or irregularly shaped plasmodia. Mature spores are oval or shortly ellipsoidal in frontal view, lemon-shaped in sutural view and eye-shaped in apical view. The spores are 14.12 ± 0.35 (13.6-15) µm long (mean ± SD), 11.85 ± 0.34 ± 0.36 (11-12) µm wide and 7.32 ± 0.36 (7-8) µm thick. The two polar capsules are equal in size, 6.11 ± 0.29 (6-7) µm long and 3.89 ± 0.31(3-4) µm wide, and are long pyriform in shape. Polar filaments have six or seven coils situated perpendicular to the longitudinal axis of the polar capsules. Histopathology indicates that the plasmodia are encased by the host connective tissue, and no inflammatory responses are found in the heart ventricles. Phylogenetic analysis based on the 18S small-subunit ribosomal DNA sequences indicates that M. hearti is, genetically, most similar to Henneguya doneci, a gill-infecting species.


Assuntos
Cyprinidae/parasitologia , Doenças dos Peixes/parasitologia , Coração/parasitologia , Myxobolus/classificação , Myxobolus/fisiologia , Doenças Parasitárias em Animais/parasitologia , Filogenia , Animais , Doenças dos Peixes/patologia , Dados de Sequência Molecular , Myxobolus/anatomia & histologia , Myxobolus/genética , Doenças Parasitárias em Animais/patologia , RNA Ribossômico 18S/genética , Esporos de Protozoários/citologia
9.
Nano Lett ; 12(6): 2877-82, 2012 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-22545811

RESUMO

We have investigated the correlated surface electronic and optical properties of [0001]-oriented epitaxial InN nanowires grown directly on silicon. By dramatically improving the epitaxial growth process, we have achieved, for the first time, intrinsic InN both within the bulk and at nonpolar InN surfaces. The near-surface Fermi-level was measured to be ∼0.55 eV above the valence band maximum for undoped InN nanowires, suggesting the absence of surface electron accumulation and Fermi-level pinning. This result is in direct contrast to the problematic degenerate two-dimensional electron gas universally observed on grown surfaces of n-type degenerate InN. We have further demonstrated that the surface charge properties of InN nanowires, including the formation of two-dimensional electron gas and the optical emission characteristics can be precisely tuned through controlled n-type doping. At relatively high doping levels in this study, the near-surface Fermi-level was found to be pinned at ∼0.95-1.3 eV above the valence band maximum. Through these trends, well captured by the effective mass and ab initio materials modeling, we have unambiguously identified the definitive role of surface doping in tuning the surface charge properties of InN.


Assuntos
Cristalização/métodos , Índio/química , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Eletricidade Estática , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Tamanho da Partícula , Propriedades de Superfície
10.
Nanotechnology ; 20(3): 035706, 2009 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-19417308

RESUMO

A new methodology for determining the radial elastic modulus of a one-dimensional nanostructure laid on a substrate has been developed. The methodology consists of the combination of contact resonance atomic force microscopy (AFM) with finite element analysis, and we illustrate it for the case of faceted AlN nanotubes with triangular cross-sections. By making precision measurements of the resonance frequencies of the AFM cantilever-probe first in air and then in contact with the AlN nanotubes, we determine the contact stiffness at different locations on the nanotubes, i.e. on edges, inner surfaces, and outer facets. From the contact stiffness we have extracted the indentation modulus and found that this modulus depends strongly on the apex angle of the nanotube, varying from 250 to 400 GPa for indentation on the edges of the nanotubes investigated.

11.
Acta Virol ; 53(1): 29-34, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19301948

RESUMO

Rubella virus (RUBV) infects cells via an acid-triggered membrane fusion process. RUBV virions contain two cysteine-rich glycoproteins, E2 and E1. The latter is believed to be involved in the membrane fusion. Using a recombinant plasmid containing RUBV E1 and E2, 11 of total 20 cysteines present in the ectodomain of wild type E1 were mutated to test their role in the fusion via the formation of disulfide bridges. The recombinant plasmids containing mutated E1 (Cys2-Cys20) or wild type (wt) E1 were expressed in BHK-21 cells. Their fusogenic and hemadsorption activities in addition to a potential of cell surface expression of E1 and E2 were assayed. The results showed that the fusogenic activity was lost in all tested mutants, while the hemadsorption activity and cell surface expression potential were affected differently in individual mutants. Since only the Cys5 and Cys8 mutations led to a reduction of both hemadsorption and cell surface expression, we assume that these mutations prevented the formation of the disulfide bridge, what led to a misfolding of E1 and consequently to a failure of recognition of E1 by E2. In conclusion, the disulfide bridges disrupted in all the tested mutants appear essential for the cell fusion, while only the disulfide bridge C(5)-C(8) seems to be crucial for the transport of E1 and E2 in the cell.


Assuntos
Dissulfetos/química , Vírus da Rubéola/química , Vírus da Rubéola/fisiologia , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/fisiologia , Internalização do Vírus , Substituição de Aminoácidos , Animais , Linhagem Celular , Cricetinae , Cisteína/genética , Hemadsorção , Mutagênese Sítio-Dirigida , Transporte Proteico , Proteínas do Envelope Viral/genética
12.
Parasitol Res ; 102(2): 299-306, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17940799

RESUMO

The phylogenetic relationships among the Ergasilidae genera are poorly understood. In this study, 14 species from four genera in the Ergasilidae including Sinergasilus, Ergasilus, Pseudergasilus, and Paraergasilus were collected in China, and their phylogenetic relationships were examined using neighbor-joining, maximum parsimony, maximum likelihood, and Bayesian inference methods based on partial sequences of 18S and 28S ribosomal deoxyribonucleic acid, respectively. All the analyses suggest that the Sinergasilus and Paraergasilus are both monophyletic, but the Ergasilus is polyphyletic rather than monophyletic. Considering the relationships among the four genera, the phylogenetic analyses and subsequent hypothesis tests all suggest that Pseudergasilus clustered with some Ergasilus species may have a closer relationship with Sinergasilus rather than with Paraergasilus. It is proposed that the Sinergasilus and the Pseudergasilus species might have evolved from Ergasilus species.


Assuntos
Copépodes/genética , Água Doce/parasitologia , Filogenia , RNA Ribossômico 18S/genética , RNA Ribossômico 28S/genética , Análise de Sequência de DNA , Animais , Teorema de Bayes , DNA Ribossômico/análise , Evolução Molecular , Funções Verossimilhança , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Especificidade da Espécie
13.
Science ; 318(5850): 615-9, 2007 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-17962556

RESUMO

Mott transitions, which are metal-insulator transitions (MITs) driven by electron-electron interactions, are usually accompanied in bulk by structural phase transitions. In the layered perovskite Ca(1.9)Sr(0.1)RuO4, such a first-order Mott MIT occurs in the bulk at a temperature of 154 kelvin on cooling. In contrast, at the surface, an unusual inherent Mott MIT is observed at 130 kelvin, also on cooling but without a simultaneous lattice distortion. The broken translational symmetry at the surface causes a compressional stress that results in a 150% increase in the buckling of the Ca/Sr-O surface plane as compared to the bulk. The Ca/Sr ions are pulled toward the bulk, which stabilizes a phase more amenable to a Mott insulator ground state than does the bulk structure and also energetically prohibits the structural transition that accompanies the bulk MIT.

14.
Vet Parasitol ; 147(1-2): 125-31, 2007 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-17459589

RESUMO

The seasonal population dynamics and maturation cycle of the nematode Camallanus cotti in the posterior intestine of Chinese hooksnout carp Opsariichthys bidens have been studied in the Danjiangkou Reservoir of the Hubei Province in central China from September 2004 to November 2005. The overall prevalence, mean abundance and intensity of C. cotti among fish sampled (n=700 fish) were 47%, 2.29+/-12.38 (+/-S.D.) and 1-307 (average 4.89+/-17.74), respectively. The overall sexual ratio of female to male nematodes (excluding L3 and L4 juveniles) was 1.17:1. Statistical results showed weakly positive correlations between fish length and the number of nematodes per host. The dynamics of infection of the nematode exhibited significant seasonal pattern in changes in mean abundance. A similar pattern was found for changes in nematode prevalence, although this was not statistically significant. Higher levels of infection were observed among fish sampled in summer months and the lower in the winter. Neither the prevalence nor the abundance of the parasite was significantly different between male and female hosts. The pattern of frequency distribution of the parasite in the host was found to be over-dispersed throughout the sampling period. In addition, studies on the development and maturation of the parasite in O. bidens revealed that development (maturation), recruitment of the next generation, and reproduction may be continuous year-round, although reproduction may peak during the winter.


Assuntos
Cyprinidae/parasitologia , Doenças dos Peixes/parasitologia , Infecções por Spirurida/veterinária , Espirurídios/fisiologia , Animais , Tamanho Corporal , China , Feminino , Doenças dos Peixes/epidemiologia , Masculino , Densidade Demográfica , Dinâmica Populacional , Prevalência , Espirurídios/crescimento & desenvolvimento , Espirurídios/isolamento & purificação , Infecções por Spirurida/epidemiologia , Infecções por Spirurida/parasitologia , Fatores de Tempo
15.
Parasitology ; 134(Pt 5): 695-703, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17166320

RESUMO

The phylogenetic relationship of 5 genera, i.e. Diplozoon Nordmann, 1832, Paradiplozoon Achmerov, 1974, Inustiatus Khotenovsky, 1978, Sindiplozoon Khotenovsky, 1981, and Eudiplozoon Khotenovsky, 1985 in the subfamily Diplozoinae Palombi, 1949 (Monogenea, Polyopisthocotylea) was inferred from rDNA ITS-2 region using neighbour-joining (NJ), maximum likelihood (ML) and Bayesian methods. The phylogenetic trees produced by using NJ, ML and Bayesian methods exhibit essentially the same topology. Surprisingly, freshwater species of Paradiplozoon from Europe clustered together with species of Diplozoon, but separated from Chinese Paradiplozoon species. The results of molecular phylogeny and lower level of divergence (4.1-15.7%) in ITS-2 rDNA among Paradiplozoon from Europe and Diplozoon and, on the other hand, high level of divergence (45.3-53.7%) among Paradiplozoon species from Europe and China might indicate the non-monophyletic origin of the genus Paradiplozoon. Also, the generic status of European Paradiplozoon needs to be revised. The species of Paradiplozoon in China is a basal group in Diplozoinae as revealed by NJ and Bayesian methods, and Sindiplozoon appears to be closely related to European Paradiplozoon and Diplozoon with their relationship to Eudiplozoon and Inustiatus being unresolved.


Assuntos
DNA Espaçador Ribossômico/genética , Filogenia , Platelmintos/classificação , Platelmintos/genética , Animais , Peixes/parasitologia , Variação Genética
16.
J Phys Chem B ; 109(27): 13210-3, 2005 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-16852647

RESUMO

The photoassisted charge behavior of hydrogen storage alloy modified with TiO2/Pt nanocomposites (HSA-TiO2/Pt electrode) was investigated. The HSA-TiO2/Pt electrode can be photocharged under current. The mechanism of photoassisted behavior of the HSA-TiO2/Pt electrode was explained through the results of cyclic voltammogram and impedance measurements of the HSA-TiO2/Pt electrode. Upon illumination, the photogenerated electrons can charge the electrode, but the photogenerated holes may oxidize the hydrogen storage alloy to form a layer of metal oxide. Because the current could keep the electrode active, the H atoms produced by photogenerated electrons diffused to the hydrogen storage alloy and a metal hydride formed. The electrode delivered a higher discharge capacity due to the assistance of photocharge.

17.
Parasitology ; 126(Pt 5): 493-501, 2003 May.
Artigo em Inglês | MEDLINE | ID: mdl-12793654

RESUMO

The genetic structure of populations of the fish cestode, Bothriocephalus acheilognathi collected from Bailianhe Reservoir (BLH), Changshou (CSH) and Liangzi (LZH) Lakes was investigated by using 8 microsatellite loci. A total of 108 adult worms were genotyped at each of the 8 loci. For the 3 populations, the mean number of alleles per locus ranged from 2.38 to 5.5, and the mean expected heterozygosity ranged from 0.432 to 0.559. The average polymorphic information content (PIC) was from 0.384 to 0.492. The significant Fis values indicated non-random mating within LZH and BLH populations. On the other hand, when samples were further classified into subpopulations at the level of host fish species, no or little heterozygote deficiency was detected at most loci, showing that cross-fertilization, predominantly, but not exclusively, must have occurred within the subpopulations. Microsatellite markers also revealed an unexpected high level of genetic differentiation, as measured by R(st) and N(m) values or by delta(u)2 genetic distance among subpopulations from different hosts. Factors influencing the population genetic structure and the parasite host specificity are discussed.


Assuntos
Cestoides/genética , Peixes/parasitologia , Variação Genética/genética , Repetições de Microssatélites/genética , Alelos , Animais , China , Polimorfismo Genético
18.
Parasitol Res ; 89(5): 419-21, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12632158

RESUMO

The genus Digramma (Cestoda: Pseudophyllidea) described by Cholodkovsky in 1915 differs from the genus Ligula only by the number of the reproductive organs per proglottis. However, the occurrence of transitional forms in Digramma raises much confusion concerning its generic validity. In the present study, cestodes previously designated as Digramma and Ligula were collected from lakes in the lower and middle reaches of the Yangtze River, and also from Qinghai Lake on Qingzang plateau, China. The entire internal transcribed spacer of the ribosomal DNA (ITS rDNA) and 5' end of 28S rDNA were compared between the Digramma and Ligula specimens. The low level of nucleotide variation between the two genera may imply that cestodes in the genus Digramma are paraphyletic to the Ligula genus, and Digramma is a synonym of Ligula. However, whether previously identified Digramma cestodes represent different species in the genus Ligula requires further investigation.


Assuntos
Cestoides/classificação , Filogenia , Região 5'-Flanqueadora/genética , Animais , Sequência de Bases , Cestoides/genética , Cestoides/isolamento & purificação , DNA Espaçador Ribossômico/genética , Dados de Sequência Molecular , RNA Ribossômico 28S , Alinhamento de Sequência
19.
Syst Parasitol ; 52(3): 159-66, 2002 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12075148

RESUMO

The molecular variation in Bothriocephalus acheilognathi Yamaguti, 1934 from 11 species of freshwater fish collected in Australia, China, the Czech Republic, England and Hawaii was investigated by determining the nucleotide sequences of the internal transcribed spacer region. The length of the first and second internal transcribed spacer sequences of multiple individuals ranged from 553 to 571 bp and 553 to 615 bp, and the G + C content from 53.1 to 53.5%. The percentage sequence divergence varied between 0 and 0.9% in the ITS1 and 0 and 6.6% in the ITS2, respectively, indicating the occurrence of intraspecific variation. It is demonstrated that the fragment length variation resulted primarily from microsatellite polymorphisms present in the ITS region, especially in the ITS2 region. Phylogenetic analyses revealed that B. acheilognathi examined in this study consisted of three closely related genotypes with certain degrees of host-specificity, and the genotype representing isolates from Cyprinus carpio L. was the most common and diverse form within the species B. acheilognathi.


Assuntos
Cestoides/genética , Cyprinidae/parasitologia , DNA de Helmintos/genética , DNA Espaçador Ribossômico/genética , Animais , Sequência de Bases , Cestoides/química , Cestoides/classificação , DNA de Helmintos/química , DNA Espaçador Ribossômico/química , Variação Genética , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase , Alinhamento de Sequência , Análise de Sequência de DNA
20.
Vet Parasitol ; 103(1-2): 109-17, 2002 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-11751006

RESUMO

An anthelmintic-sensitive Haemonchus contortus strain was selected for moxidectin and ivermectin resistance concurrently for 22 generations. Treatment with 0.002 mg moxidectin/kg BW or 0.02 mg ivermectin/kg BW produced >99% efficacy against the susceptible parent strain passaged for 22 generations without any anthelmintic exposure. However, to obtain similar efficacy the moxidectin-selected and the ivermectin-selected strains of H. contortus required 0.05 mg moxidectin/kg BW or 0.4 mg ivermectin/kg BW. These results indicate that development of resistance to one macrocyclic lactone, simultaneously results in resistance to another macrocyclic lactone. However, rates of resistance development differ between compounds and occurs more slowly with moxidectin than with ivermectin.


Assuntos
Anti-Helmínticos/farmacologia , Antibacterianos/farmacologia , Hemoncose/veterinária , Haemonchus/efeitos dos fármacos , Ivermectina/farmacologia , Doenças dos Ovinos/tratamento farmacológico , Animais , Anti-Helmínticos/uso terapêutico , Antibacterianos/uso terapêutico , Resistência a Medicamentos , Feminino , Hemoncose/tratamento farmacológico , Haemonchus/crescimento & desenvolvimento , Ivermectina/uso terapêutico , Macrolídeos , Masculino , Testes de Sensibilidade Parasitária/veterinária , Distribuição Aleatória , Seleção Genética , Sensibilidade e Especificidade , Ovinos , Doenças dos Ovinos/parasitologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA