Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 96
Filtrar
Más filtros

Bases de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Memory ; 25(3): 391-402, 2017 03.
Artículo en Inglés | MEDLINE | ID: mdl-27188831

RESUMEN

There is a growing body of literature that suggests that long-term memory (LTM) and short-term memory (STM) structures that were once thought to be distinct are actually co-dependent, and that LTM can aid retrieval from STM. The mechanism behind this effect is commonly argued to act on item memory but not on order memory. The aim of the current study was to examine whether LTM could exert an influence on STM for order by examining an effect attributed to LTM, the phonological neighbourhood effect, in a task that reduced the requirement to retain item information. In Experiment 1, 18 participants completed a serial reconstruction task where neighbourhood density alternated within the lists. In Experiment 2, 22 participants completed a serial reconstruction task using pure lists of dense and sparse neighbourhood words. In Experiment 3, 22 participants completed a reconstruction task with both mixed and pure lists. There was a significant effect of neighbourhood density with better recall for dense than sparse neighbourhood words in pure lists but not in mixed lists. Results suggest that LTM exerts an influence prior to that proposed by many models of memory for order.


Asunto(s)
Memoria a Corto Plazo/fisiología , Aprendizaje Seriado/fisiología , Aprendizaje Verbal/fisiología , Femenino , Humanos , Masculino , Pruebas Neuropsicológicas , Vocabulario
2.
Reprod Domest Anim ; 51(2): 287-93, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26939713

RESUMEN

This study was designed to test the hypothesis that sperm-bound IgG and IgA decrease binding of bull spermatozoa to oviductal epithelial cells in vitro. Three ejaculates were cryopreserved from each of four antisperm antibody (ASA)-negative satisfactory breeder bulls. Bulls were then immunized with autologous spermatozoa, and three ASA-positive ejaculates were cryopreserved from each bull post-immunization. First, microscopy methods were compared to select the most appropriate assay for evaluation of oviductal binding index (BI). The BI did not differ when the evaluation was performed under fluorescence microscopy (131.1 sperm/mm(2); 62.5-251.1 sperm/mm(2)), phase-contrast microscopy (160.5 sperm/mm(2); 56.8-397.4 mm(2)) or their combination (116.4 sperm/mm(2); 56.8-249.6 sperm/mm(2)) (Median; IQR). The combination of microscopy methods was selected as it allowed better visualization of cells. Then, BI was compared between ASA-negative and ASA-positive ejaculates, and the association between BI and ASA binding was evaluated. The BI was less in ASA-positive (114.9; 0 to 201.8 sperm/0.1 mm(2)) than ASA-negative samples (218.9; 24.7 to 276.8 sperm/0.1 mm(2)) (P = 0.0002). This reduction in BI was significant in three of the four bulls. Regression analysis identified a negative association between BI and the percentage of IgG-bound (p = 0.013) but not IgA-bound spermatozoa. In conclusion, sperm-bound IgG decreased the ability of bovine spermatozoa to bind to oviductal epithelial cells in vitro.


Asunto(s)
Bovinos/fisiología , Adhesión Celular/fisiología , Inmunoglobulina A/fisiología , Inmunoglobulina G/fisiología , Oviductos/citología , Espermatozoides/fisiología , Animales , Células Epiteliales/fisiología , Femenino , Masculino
3.
Waste Manag ; 29(6): 1838-43, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-19282166

RESUMEN

A 750,000litre fermenter was studied throughout one entire year by investigating the concentrations of volatile fatty acids (acetic, butyric, i-butyric, propionic, valeric and i-valeric acids), pH, concentrations of total C, N, S and NH(4)(+)-N, amounts of chemical and biological oxygen demand, and abundance of acetogenic microorganisms. Additionally several process parameters such as temperature, retention time, dry weight and input of substrate and liquids, and the concentrations and amounts of CH(4), H(2), CO(2) and H(2)S within the biogas were monitored continuously. Various volatile fatty acids and the ratio of acetic to propionic acid were shown to allow a rough indication on the fermentation but were not sufficiently precise to describe the fermenter performance. Nutrient compounds and special fractions, such as easily extractable carbohydrates or the concentration of total fats were more strongly correlated to the gas production of the fermenter. Results of an MPN-method for the determination of acetogenic microorganisms point to an important role of these microorganisms during the phase of restoration of the fermenter performance.


Asunto(s)
Anaerobiosis , Reactores Biológicos , Fermentación , Reactores Biológicos/microbiología , Análisis de Falla de Equipo , Volatilización
4.
Neuron ; 32(1): 151-60, 2001 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-11604146

RESUMEN

One of the brain's fundamental tasks is to construct and transform representations of an animal's environment, yet few studies describe how individual neurons accomplish this. Our results from correlated pairs in the auditory thalamocortical system show that cortical excitatory receptive field regions can be directly inherited from thalamus, constructed from smaller inputs, and assembled by the cooperative activity of neuronal ensembles. The prevalence of functional thalamocortical connectivity is strictly governed by tonotopy, but connection strength is not. Finally, spectral and temporal modulation preferences in cortex may differ dramatically from the thalamic input. Our observations reveal a radical reconstruction of response properties from auditory thalamus to cortex, and illustrate how some properties are propagated with great fidelity while others are significantly transformed or generated intracortically.


Asunto(s)
Corteza Auditiva/citología , Corteza Auditiva/fisiología , Cuerpos Geniculados/citología , Cuerpos Geniculados/fisiología , Estimulación Acústica , Potenciales de Acción/fisiología , Anestésicos Disociativos , Animales , Vías Auditivas/citología , Vías Auditivas/fisiología , Gatos , Electrofisiología , Ketamina , Inhibición Neural/fisiología
5.
Neuroscience ; 152(1): 151-9, 2008 Mar 03.
Artículo en Inglés | MEDLINE | ID: mdl-18222043

RESUMEN

Neurons in the center of cat primary auditory cortex (AI) respond to a narrow range of sound frequencies and the preferred frequencies in local neuron clusters are closely aligned in this central narrow bandwidth region (cNB). Response preferences to other input parameters, such as sound intensity and binaural interaction, vary within cNB; however, the source of this variability is unknown. Here we examined whether input to the cNB could arise from multiple, anatomically independent subregions in the ventral nucleus of the medial geniculate body (MGBv). Retrograde tracers injected into cNB labeled discontinuous clusters of neurons in the superior (sMGBv) and inferior (iMGBv) halves of the MGBv. Most labeled neurons were in the sMGBv and their density was greater, iMGBv somata were significantly larger. These findings suggest that cNB projection neurons in superior and iMGBv have distinct anatomic and possibly physiologic organization.


Asunto(s)
Corteza Auditiva/citología , Vías Auditivas/citología , Mapeo Encefálico , Neuronas/citología , Tálamo/citología , Estimulación Acústica , Animales , Gatos
6.
Osteoporos Int ; 19(9): 1251-65, 2008 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-18317862

RESUMEN

Bone mineral density is the gold-standard for assessing bone quantity and diagnosing osteoporosis. Although bone mineral density measurements assess the quantity of bone, the quality of the tissue is an important predictor of fragility. Understanding the macro- and nanoscale properties of bone is critical to understanding bone fragility in osteoporosis. Osteoporosis is a disease that affects more than 75 million people worldwide. The gold standard for osteoporosis prognosis, bone mineral density, primarily measures the quantity of bone in the skeleton, overlooking more subtle aspects of bone's properties. Bone quality, a measure of bone's architecture, geometry and material properties, is evaluated via mechanical, structural and chemical testing. Although decreased BMD indicates tissue fragility at the clinical level, changes in the substructure of bone can help indicate how bone quality is altered in osteoporosis. Additionally, mechanical properties which can quantify fragility, or bone's inability to resist fracture, can be changed due to alterations in bone architecture and composition. Recent studies have focused on examination of bone on the nanoscale, suggesting the importance of understanding the interactions of the mineral crystals and collagen fibrils and how they can alter bone quality. It is therefore important to understand alterations in bone that occur at the macro-, micro- and nanoscopic levels to determine what parameters contribute to decreased bone quality in diseased tissue.


Asunto(s)
Densidad Ósea , Huesos/ultraestructura , Fracturas Óseas/patología , Nanotecnología , Osteoporosis/patología , Animales , Colágeno/análisis , Fracturas Óseas/etiología , Humanos , Nanoestructuras , Osteoporosis/complicaciones , Osteoporosis/diagnóstico , Ratas , Estrés Mecánico
7.
Osteoporos Int ; 19(9): 1331-41, 2008 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-18385919

RESUMEN

INTRODUCTION: Strontium ranelate (SrR) is suggested to function as a dual-acting agent in the treatment of postmenopausal osteoporosis with anti-resorptive and anabolic skeletal benefits. We evaluated the effects of SrR on the skeleton in ovariectomized (OVX) rats and evaluated the influence of dietary calcium. METHODS: Three-month old virgin female rats underwent ovariectomy (OVX, n = 50) or SHAM surgery (SHAM, n = 10). Four weeks post-surgery, rats were treated daily by oral gavage with distilled water (10 ml/kg/day) or SrR (25 or 150 mg/kg/day) for 90 days. Separate groups of animals for each dose of SrR were fed a low (0.1%) or normal (1.19%) calcium (Ca) diet. Static and dynamic histomorphometry, DXA, mu-CT, mechanical testing, and serum and skeletal concentrations of strontium were assessed. RESULTS: SrR at doses of 25 and 150 mg/kg/day did not increase bone formation on trabecular or periosteal bone surfaces, and failed to inhibit bone resorption of trabecular bone regardless of Ca intake. There were no improvements in bone mass, volume or strength with either dose of SrR given normal Ca. CONCLUSION: These findings demonstrate that SrR at dosages of 25 and 150 mg/kg/day did not stimulate an anabolic bone response, and failed to improve the bone biomechanical properties of OVX rats.


Asunto(s)
Conservadores de la Densidad Ósea/farmacología , Compuestos Organometálicos/farmacología , Osteogénesis/efectos de los fármacos , Tiofenos/farmacología , Absorciometría de Fotón , Animales , Resorción Ósea/fisiopatología , Resorción Ósea/prevención & control , Huesos/metabolismo , Calcio de la Dieta/farmacología , Relación Dosis-Respuesta a Droga , Evaluación Preclínica de Medicamentos/métodos , Femenino , Fémur/efectos de los fármacos , Fémur/fisiopatología , Vértebras Lumbares/efectos de los fármacos , Vértebras Lumbares/fisiopatología , Compuestos Organometálicos/farmacocinética , Ovariectomía , Ratas , Ratas Sprague-Dawley , Estrés Mecánico , Estroncio/sangre , Tiofenos/farmacocinética
8.
Theriogenology ; 118: 212-218, 2018 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-29935460

RESUMEN

Antisperm antibodies (ASAs) have been associated with infertility in stallions. The objectives of this study were to investigate the frequency of ASA-positive semen samples in satisfactory and non-satisfactory breeder stallions, the association between ASA binding and semen quality, and factors that may affect the diagnosis. Breeding soundness examinations were performed in 21 stallions and the percentage of IgG- and IgA-bound spermatozoa was evaluated using flow cytometry. Median IgG and IgA binding did not differ between the first and second ejaculates. The percentage of IgA-bound spermatozoa was higher in non-satisfactory (n = 10) than satisfactory breeder stallions (n = 11). However, IgG binding or frequency of IgG-positive ejaculates did not differ with stallion classification. The IgG-positive stallions had significantly lower total sperm motility, concentration and total numbers than IgG-negative stallions in the first ejaculate, and lower sperm concentration in the second ejaculate. The IgA-positive stallions had lower total sperm motility, normal spermatozoa and total numbers than IgA-negative stallions in the first ejaculate, and lower total sperm motility, normal spermatozoa and total numbers in the second ejaculate. While IgG binding did not differ with season, IgA binding was higher in the non-breeding season (n = 6 stallions) than the breeding season (n = 15 stallions) in the first ejaculate. Stallion age did not differ with ASA classification. In conclusion, IgG binding was highly prevalent in both groups of stallions, while IgA binding was higher and more prevalent in non-satisfactory breeders. Both isotypes were associated with poor semen quality. Season and sexual rest had an effect on IgA but not IgG binding.


Asunto(s)
Anticuerpos/metabolismo , Enfermedades de los Caballos/inmunología , Infertilidad Masculina/veterinaria , Análisis de Semen/veterinaria , Espermatozoides/inmunología , Animales , Anticuerpos/análisis , Cruzamiento , Citometría de Flujo/veterinaria , Caballos , Inmunoglobulina A/análisis , Inmunoglobulina A/metabolismo , Inmunoglobulina G/análisis , Inmunoglobulina G/metabolismo , Infertilidad Masculina/inmunología , Masculino , Estaciones del Año , Recuento de Espermatozoides/veterinaria , Motilidad Espermática
9.
Nat Biotechnol ; 19(10): 952-7, 2001 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-11581661

RESUMEN

Although direct fragmentation of protein ions in a mass spectrometer is far more efficient than exhaustive mapping of 1-3 kDa peptides for complete characterization of primary structures predicted from sequenced genomes, the development of this approach is still in its infancy. Here we describe a statistical model (good to within approximately 5%) that shows that the database search specificity of this method requires only three of four fragment ions to match (at +/-0.1 Da) for a 99.8% probability of being correct in a database of 5,000 protein forms. Software developed for automated processing of protein ion fragmentation data and for probability-based retrieval of whole proteins is illustrated by identification of 18 archaeal and bacterial proteins with simultaneous mass-spectrometric (MS) mapping of their entire primary structures. Dissociation of two or three proteins at once for such identifications in parallel is also demonstrated, along with retention and exact localization of a phosphorylated serine residue through the fragmentation process. These conceptual and technical advances should assist future processing of whole proteins in a higher throughput format for more robust detection of co- and post-translational modifications.


Asunto(s)
Proteínas Arqueales/análisis , Proteínas Bacterianas/análisis , Biología Computacional , Modelos Estadísticos , Algoritmos , Fosfatasa Alcalina , Secuencia de Aminoácidos , Proteínas Arqueales/química , Proteínas Bacterianas/química , Biología Computacional/métodos , Quinasas Ciclina-Dependientes/genética , Bases de Datos Factuales , Almacenamiento y Recuperación de la Información , Iones , Espectrometría de Masas , Methanococcus/química , Datos de Secuencia Molecular , Mycoplasma pneumoniae/química , Probabilidad
10.
Theriogenology ; 89: 58-67, 2017 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-28043371

RESUMEN

It was hypothesized here that sperm-bound antisperm antibodies (ASAs) impair the ability of bovine spermatozoa to undergo capacitation, bind to the zona pellucida, and complete the acrosome reaction. The effect of ASA binding on these functions was evaluated in frozen/thawed spermatozoa from four bulls before and after induction of ASAs. Ejaculates were divided into ASA negative (<10% immunoglobulin [Ig]G- and IgA-bound spermatozoa) or ASA positive (≥20% IgG and/or IgA-bound spermatozoa). The percentage of capacitated (Merocyanine 540 positive) live spermatozoa in response to heparin was lower in ASA-positive than ASA-negative ejaculates (P < 0.0001). Treatment with heparin resulted in a higher percentage of capacitated spermatozoa compared with control treatments in ASA-negative but not ASA-positive ejaculates. The percentage of capacitated spermatozoa after heparin treatment was negatively correlated with IgA (P = 0.02, R2 = -0.48) but not IgG binding. Sperm binding to the zona pellucida was lower in IgA-positive (six spermatozoa/oocyte; 3-10 spermatozoa/oocyte) than IgA-negative ejaculates (seven spermatozoa/oocyte; 4-13 spermatozoa/oocyte) (P = 0.019). Zona binding was negatively correlated with the percentage of IgA-bound spermatozoa (P = 0.04; R2 = -0.24) but not IgG-bound spermatozoa. The percentage of acrosome-reacted spermatozoa was higher in calcium ionophore A23187-treated than control aliquots in both ASA-negative and ASA-positive ejaculates (P < 0.0001). However, the percentage of acrosome-reacted spermatozoa did not differ between ASA-positive and ASA-negative samples, and no correlation was identified with IgG or IgA binding. It was concluded that sperm-bound IgA affected the ability of bovine spermatozoa to undergo capacitation. ASAs inhibited the changes in plasma membrane fluidity associated with capacitation and binding of spermatozoa to the zona pellucida.


Asunto(s)
Bovinos/inmunología , Inmunoglobulina A/inmunología , Inmunoglobulina G/inmunología , Capacitación Espermática/inmunología , Espermatozoides/inmunología , Reacción Acrosómica/fisiología , Animales , Ionóforos de Calcio/farmacología , Membrana Celular/inmunología , Femenino , Congelación , Heparina/farmacología , Masculino , Espermatozoides/efectos de los fármacos , Zona Pelúcida/fisiología
11.
J Anim Sci ; 94(12): 5105-5113, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28046145

RESUMEN

Very little is known regarding the effects of cow exposure to toxic ergot alkaloids in late gestation and the subsequent, long-term effects on progeny. Therefore, the objectives were to determine the effects of grazing toxic endophyte-infected tall fescue () or novel endophyte-infected tall fescue during late gestation on cow BW, BCS, hair coat score (HCS), respiration rates, milk production, and reproduction and on growth performance and carcass characteristics of progeny. Eighty gestating, Angus × Simmental cows (age = 6.68 ± 0.32 yr; 588 ± 16 kg initial BW; initial BCS = 5.66 ± 0.28) were stratified by initial BW and allocated into 8 pasture groups (10 cows/group) with 4 groups per treatment. Each group was allotted to 1 of 2 grazing treatments: toxic endophyte-infected tall fescue ('Kentucky-31'; E+) or novel endophyte-infected tall fescue ('Jesup MaxQ'; NOV). Cows were placed on grazing treatments at 110 ± 6 d prepartum (May 28, 2014) and remained on treatment until the end of the calving period (October 8, 2014; 23 ± 6 d postpartum). Cow BW and BCS did not diverge ( ≥ 0.15) at any time point among grazing treatments. However, cows grazing E+ had increased ( < 0.05) respiration rates and HCS and reduced ( < 0.05) prolactin concentration compared with cows grazing NOV. Calf birth BW, Julian calving date, milk production, AI conception rate, and overall pregnancy rate did not differ ( ≥ 0.23) by grazing treatment. In a subsequent grazing period of the progeny, dam grazing treatment did not affect ( ≥ 0.14) respiration rates, HCS, or prolactin concentration of the progeny when all progeny grazed E+ pastures. However, progeny born to dams grazing NOV tended ( > 0.06 to ≤0.10) to have increased BW at 70 ± 6 d of age, 205 d (adjusted weaning BW), and throughout the postweaning calf grazing period. Despite a tendency for BW to differ throughout the postweaning calf grazing period, finishing phase performance and carcass characteristics of progeny did not differ ( ≥ 0.20) between dam grazing treatment. In conclusion, results indicate that by the time progeny enter the feedlot and are finished on a high-grain diet, any fetal programming effects are minimal.


Asunto(s)
Enfermedades de los Bovinos/inducido químicamente , Endófitos/metabolismo , Alcaloides de Claviceps/toxicidad , Festuca/microbiología , Alimentación Animal/análisis , Crianza de Animales Domésticos , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Composición Corporal , Bovinos , Dieta/veterinaria , Alcaloides de Claviceps/metabolismo , Femenino , Micotoxinas/toxicidad , Embarazo , Reproducción , Estaciones del Año , Destete
12.
J Neurosci ; 21(20): 8136-44, 2001 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-11588186

RESUMEN

Action potentials are a universal currency for fast information transfer in the nervous system, yet few studies address how some spikes carry more information than others. We focused on the transformation of sensory representations in the lemniscal (high-fidelity) auditory thalamocortical network. While stimulating with a complex sound, we recorded simultaneously from functionally connected cell pairs in the ventral medial geniculate body and primary auditory cortex. Thalamic action potentials that immediately preceded or potentially caused a cortical spike were more selective than the average thalamic spike for spectrotemporal stimulus features. This net improvement of thalamic signaling indicates that for some thalamic cells, spikes are not propagated through cortex independently but interact with other inputs onto the same target cell. We then developed a method to identify the spectrotemporal nature of these interactions and found that they could be cooperative or antagonistic to the average receptive field of the thalamic cell. The degree of cooperativity with the thalamic cell determined the increase in feature selectivity for potentially causal thalamic spikes. We therefore show how some thalamic spikes carry more receptive field information than average and how other inputs cooperate to constrain the information communicated through a cortical cell.


Asunto(s)
Potenciales de Acción/fisiología , Corteza Auditiva/fisiología , Vías Auditivas/fisiología , Interneuronas/fisiología , Tálamo/fisiología , Estimulación Acústica , Animales , Gatos , Cuerpos Geniculados/fisiología , Tiempo de Reacción/fisiología
13.
Biochim Biophys Acta ; 1527(1-2): 11-9, 2001 Jul 02.
Artículo en Inglés | MEDLINE | ID: mdl-11420138

RESUMEN

Measurements of bone mineral content and composition in situ provide insight into the chemistry of bone mineral deposition. Infrared (IR) micro-spectroscopy is well suited for this purpose. To date, IR microscopic (including imaging) analyses of bone apatite have centered on the nu(1),nu(3) PO(4)(3-) contour. The nu(4) PO(4)(3-) contour (500-650 cm(-1)), which has been extensively used to monitor the crystallinity of hydroxyapatite in homogenized bone samples, falls in a frequency region below the cutoff of the mercury-cadmium-telluride detectors used in commercial IR microscopes, thereby rendering this vibration inaccessible for imaging studies. The current study reports the first IR micro-spectroscopy spectra of human iliac crest cross sections in the nu(4) PO(4)(3-) spectral regions, obtained with a synchrotron radiation source and a Cu-doped Ge detector coupled to an IR microscope. The acid phosphate (HPO(4)(2-)) content and mineral crystallite perfection (crystallinity) of a human osteon were mapped. To develop spectra-structure correlations, a combination of X-ray powder diffraction data and conventional Fourier transform IR spectra have been obtained from a series of synthetic hydroxyapatite crystals and natural bone powders of various species and ages. X-ray powder diffraction data demonstrate that there is an increase in average crystal size as bone matures, which correlates with an increase in the nu(4) PO(4)(3-) FTIR absorption peak ratio of two peaks (603/563 cm(-1)) within the nu(4) PO(4)(3-) contour. Additionally, the IR results reveal that a band near 540 cm(-1) may be assigned to acid phosphate. This band is present at high concentrations in new bone, and decreases as bone matures. Correlation of the nu(4) PO(4)(3-) contour with the nu(2) CO (3)(2-) contour also reveals that when acid phosphate content is high, type A carbonate content (i.e., carbonate occupying OH(-) sites in the hydroxyapatite lattice) is high. As crystallinity increases and acid phosphate content decreases, carbonate substitution shifts toward occupation of PO(4)(3-) sites in the hydroxyapatite lattice. Thus, IR microscopic analysis of the nu(4) PO(4)(3-) contour provides a straightforward index of both relative mineral crystallinity and acid phosphate concentration that can be applied to in situ IR micro-spectroscopic analysis of bone samples, which are of interest for understanding the chemical mechanisms of bone deposition in normal and pathological states.


Asunto(s)
Huesos/química , Minerales/análisis , Adulto , Animales , Densidad Ósea , Humanos , Masculino , Ratones , Conejos , Espectrofotometría Infrarroja/métodos , Difracción de Rayos X
14.
Genetics ; 147(3): 1249-58, 1997 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-9383067

RESUMEN

Effective population size (Ne) of a natural fish population was estimated from temporal changes in allele frequencies at seven microsatellite loci. Use of a historical collection of fish scales made it possible to increase the precision of estimates by increasing the time interval between samples and to use an equation developed for discrete generations without correcting for demographic parameters. Estimates of Ne for the time intervals 1961-1977 and 1977-1993 were 35 and 72, respectively. For the entire interval, 1961-1993, the estimate of Ne was 48 when based on a weighted mean derived from the above two estimates or 125 when calculated from 1961 and 1993 samples only. Corresponding ratios of effective size to adult census size ranged from 0.03 to 0.14. An Ne of 48 over a 32-year period would imply that this population lost as much as 8% of its heterozygosity in that time. Results suggest the potential for using genetic methods based on microsatellite loci data to compare historical trends in Ne with population dynamic parameters. Such comparisons will help to evaluate the relationship between genetic diversity and long-term persistence of natural populations.


Asunto(s)
Esocidae/genética , Variación Genética , Animales , Repeticiones de Microsatélite , Densidad de Población
15.
Genetics ; 143(3): 1181-91, 1996 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-8807292

RESUMEN

We describe a genetic mosaic analysis procedure in which Caenorhabditis elegans mosaics are generated by spontaneous loss of an extrachromosomal array. This technique allows almost any C. elegans gene that can be used in germline transformation experiments to be used in mosaic analysis experiments. We identified a cosmid clone that rescues the mutant phenotype of ncl-1, so that this cell-autonomous marker could be used to analyze mosaic animals. To determine the sites of action for unc-29 and lin-31, an extrachromosomal array was constructed containing the ncl-1(+) cosmid linked to lin-31(+) and unc-29(+) cosmids. This array is mitotically unstable and can be lost to produce a clone of mutant cells. The specific cell division at which the extrachromosomal array had been lost was deduced by scoring the Ncl phenotypes of individual cells in genetic mosaics. The Unc-29 and Lin-31 phenotypes were then scored in these animals to determine in which cells these genes are required. This analysis showed that unc-29, which encodes a subunit of the acetylcholine receptor, acts in the body muscle cells. Furthermore, lin-31, which specifies cell fates during vulval induction and encodes a putative transcription factor similar to HNF-3/fork head, acts in the Pn.p cells.


Asunto(s)
Proteínas de Caenorhabditis elegans , Caenorhabditis elegans/genética , Proteínas de Unión al ADN/genética , Mosaicismo , Factores de Transcripción/genética , Animales , Herencia Extracromosómica , Mutación , Fenotipo , Receptores Colinérgicos/genética , Transformación Genética
16.
Genetics ; 156(4): 1595-602, 2000 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-11102360

RESUMEN

The lin-31 gene is required for the proper specification of vulval cell fates in the nematode Caenorhabditis elegans and encodes a member of the winged-helix family of transcription factors. Members of this important family have been identified in many organisms and are known to bind specific DNA targets involved in a variety of developmental processes. DNA sequencing of 13 lin-31 alleles revealed six nonsense mutations and two missense mutations within the DNA-binding domain, plus three deletions, one transposon insertion, and one frameshift mutation that all cause large-scale disruptions in the gene. The missense mutations are amino acid substitutions in the DNA-binding domain and probably disrupt interactions of the LIN-31 transcription factor with its DNA target. In addition, detailed phenotypic analysis of all 19 alleles showed similar penetrance for several characteristics examined. From our analysis we conclude: (1) the null phenotype of lin-31 is the phenotype displayed by almost all of the existing alleles, (2) the DNA-binding domain plays a critical role in LIN-31 function, and (3) direct screens for multivulva and vulvaless mutants will probably yield only null (or strong) alleles of lin-31.


Asunto(s)
Proteínas de Caenorhabditis elegans , Caenorhabditis elegans/genética , Proteínas de Unión al ADN/genética , Genes de Helminto , Proteínas del Helminto/genética , Factores de Transcripción/genética , Vulva/embriología , Alelos , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Animales , Sitios de Unión , Caenorhabditis elegans/embriología , Codón sin Sentido , Análisis Mutacional de ADN , ADN de Helmintos/genética , ADN de Helmintos/metabolismo , Proteínas de Unión al ADN/fisiología , Trastornos del Desarrollo Sexual , Femenino , Proteínas del Helminto/fisiología , Masculino , Datos de Secuencia Molecular , Morfogénesis , Familia de Multigenes , Mutación Missense , Fenotipo , Estructura Terciaria de Proteína , Alineación de Secuencia , Eliminación de Secuencia , Homología de Secuencia de Aminoácido , Factores de Transcripción/fisiología , Vulva/anomalías , Vulva/citología
17.
Genetics ; 124(3): 663-76, 1990 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-2155854

RESUMEN

Inbred lines derived from a strain called Sexi were analyzed for their abilities to repress P element-mediated gonadal dysgenesis. One line had high repression ability, four had intermediate ability and two had very low ability. The four intermediate lines also exhibited considerable within-line variation for this trait; furthermore, in at least two cases, this variation could not be attributed to recurring P element movement. Repression of gonadal dysgenesis in the hybrid offspring of all seven lines was due primarily to a maternal effect; there was no evidence for repression arising de novo in the hybrids themselves. In one of the lines, repression ability was inherited maternally, indicating the involvement of cytoplasmic factors. In three other lines, repression ability appeared to be determined by partially dominant or additive chromosomal factors; however, there was also evidence for a maternal effect that reduced the expression of these factors in at least two of the lines. In another line, repression ability seemed to be due to recessive chromosomal factors. All seven lines possessed numerous copies of a particular P element, called KP, which has been hypothesized to produce a polypeptide repressor of gonadal dysgenesis. This hypothesis, however, does not explain why the inbred Sexi lines varied so much in their repression abilities. It is suggested that some of this variation may be due to differences in the chromosomal position of the KP elements, or that other nonautonomous P elements are involved in the repression of hybrid dysgenesis in these lines.


Asunto(s)
Elementos Transponibles de ADN , Drosophila melanogaster/genética , Animales , Cruzamientos Genéticos , ADN/genética , Drosophila melanogaster/fisiología , Femenino , Fertilidad , Masculino , Mutación , Mapeo Restrictivo , Cromosoma X
18.
Theriogenology ; 84(1): 94-100, 2015 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-25784451

RESUMEN

The objectives of this study were to determine reference intervals (RIs) for sperm-bound immunoglobulins G and A (IgG and IgA), prevalence of antisperm antibodies (ASAs) in satisfactory and nonsatisfactory breeders, and association between ASAs and semen quality in beef bulls. It was hypothesized that ASA binding differed with breeding soundness classification and semen quality. The percentage of IgG- (IgGperc) and IgA-bound (IgAperc) spermatozoa was evaluated in satisfactory (n = 134) and nonsatisfactory (n = 71) breeder beef bulls using flow cytometry. The RI for IgGperc was 0% to 13.5%. The RIs for IgAperc were 0% to 25.8% in yearling Aberdeen Angus bulls and 0% to 12% in all other bulls. The prevalence of IgA-positive samples was higher in nonsatisfactory (14.1%) than that in satisfactory (1.5%) breeders (P = 0.0003). However, the prevalence of IgG-positive samples did not differ. Similarly, IgA binding was higher in nonsatisfactory (median; interquartile range; 2.18; 0.77%-8.57%) than that in satisfactory breeders (median; interquartile range; 1.11; 0.32%-3.16%; P = 0.0035), but IgG binding did not differ. Among ASA-positive bulls, median IgA and IgG binding was 39.7% (range, 18.8%-96.2%) and 24.8% (range, 14.2%-33.1%), respectively. Immunoglobulin A binding correlated with the percentage of total (P < 0.0001; r(2) = -0.345) and progressively motile spermatozoa (P < 0.0001; r(2) = -0.329), morphologically normal spermatozoa (P = 0.0004; r(2) = -0.256), sperm head abnormalities (P = 0.0416; r(2) = 0.149), proximal droplets (P = 0.0227; r(2) = 0.167), and coiled tails (P = 0.0338; r(2) = 0.156). Immunoglobulin G binding correlated with the percentage of total (P < 0.0001; r(2) = -0.373) and progressively motile spermatozoa (P < 0.0001; r(2) = -0.455) and sperm concentration (P = 0.0332; r(2) = -0.195). Reference intervals were established for determination of cutoffs for clinically significant sperm-bound IgA and IgG with flow cytometry. Immunoglobulin A binding was both higher and more prevalent in nonsatisfactory breeder bulls. Although IgG binding did not differ with breeding soundness classification, detection of surface-bound IgG and IgA was associated with changes in semen quality.


Asunto(s)
Bovinos/fisiología , Inmunoglobulina A/análisis , Inmunoglobulina G/análisis , Análisis de Semen/veterinaria , Espermatozoides/inmunología , Animales , Citometría de Flujo , Inmunoglobulina A/metabolismo , Inmunoglobulina G/metabolismo , Masculino , Espermatozoides/metabolismo
19.
Bone ; 30(3): 492-7, 2002 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-11882463

RESUMEN

Life postmenopausal women, ovariectomized cynomolgus monkeys (Macaca fascicularis) experience accelerated loss of bone mass. Treatment of ovariectomized monkeys with nandrolone decanoate results in an increase in bone mass to levels comparable to those of intact animals. The changes in bone composition that occur with these treatments, however, are less well characterized. In the present study, we used synchrotron Fourier-transform infrared microspectroscopy (FT-IRM) and curve-fitting methods to monitor specific changes at cortical, subchondral, and trabecular bone regions in the proximal tibia. Four groups were studied: (1) sham-operated (sham); (2) ovariectomized and treated with placebo for 2 years (ovx); (3) ovx + nandrolone decanoate for 2 years (NAN); and (4) ovx + nandrolone decanoate beginning 1 year after ovx (dNAN). The results demonstrate that ovariectomy and nandrolone treatment did not affect the degree of mineralization as defined by the phosphate/protein ratio, but acid phosphate content (HPO(4)(2-)) in cortical and subchondral bone was increased by ovariectomy, suggesting this bone to be less mature due to increased remodeling that occurs after ovariectomy. In the subchondral and cortical bone regions, ovariectomized monkeys showed a lower total carbonate content (CO(3)(2-)/matrix ratio) than sham controls, specifically due to the decrease in labile carbonate content. In the trabecular region, no change of carbonate content was observed. Treatment with nandrolone decanoate was found to restore the loss in carbonate, where the resulting mineral had a larger quantity of type B carbonate. Finally, we correlated carbonate content with dual-energy X-ray absorptiometry measurements, and found a positive correlation between bone mineral density and type A carbonate in bone, which is stoichiometrically related to the amount of calcium in bone. Therefore, the results presented herein identify significant differences in bone chemistry after ovariectomy and nandrolone treatment, which may help explain previous findings that, although nandrolone decanoate treatment increased bone mass, it could not reverse the decrease in bone strength due to ovariectomy.


Asunto(s)
Anabolizantes/farmacología , Densidad Ósea/efectos de los fármacos , Densidad Ósea/fisiología , Nandrolona/análogos & derivados , Nandrolona/farmacología , Ovariectomía , Tibia/efectos de los fármacos , Tibia/fisiología , Anabolizantes/uso terapéutico , Animales , Estrógenos/deficiencia , Femenino , Macaca fascicularis , Nandrolona/uso terapéutico , Nandrolona Decanoato , Ovariectomía/estadística & datos numéricos
20.
J Med Chem ; 21(1): 123-6, 1978 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22752

RESUMEN

The synthesis of several 3-alkylamino-2-hydroxypropyl heteroaryl ethers (13-15, 17, and 18) is described. These compounds were prepared by the alkylamination of the corresponding glycidyl ethers (6-8, 10, and 11), which in turn were obtained from the requisite heteroaryl halides and the sodium salt of glycidol. The above basic ethers exhibited beta-blocking activity, but the potency of the tested compounds was considerably less than that of propanolol. Only 3-tert-butylamino-2-hydroxyl-1-(1,2,4-thiadiazol-5-yl) propyl ether (13) showed some selective myocardial beta-blocking activity.


Asunto(s)
Antagonistas Adrenérgicos beta/síntesis química , Animales , Presión Sanguínea/efectos de los fármacos , Perros , Compuestos Epoxi/síntesis química , Compuestos Epoxi/farmacología , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Masculino , Propanolaminas/síntesis química , Propanolaminas/farmacología , Relación Estructura-Actividad
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA