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1.
Persoonia ; 46: 313-528, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35935893

RESUMO

Novel species of fungi described in this study include those from various countries as follows: Algeria, Phaeoacremonium adelophialidum from Vitis vinifera. Antarctica, Comoclathris antarctica from soil. Australia, Coniochaeta salicifolia as endophyte from healthy leaves of Geijera salicifolia, Eremothecium peggii in fruit of Citrus australis, Microdochium ratticaudae from stem of Sporobolus natalensis, Neocelosporium corymbiae on stems of Corymbia variegata, Phytophthora kelmanii from rhizosphere soil of Ptilotus pyramidatus, Pseudosydowia backhousiae on living leaves of Backhousia citriodora, Pseudosydowia indooroopillyensis, Pseudosydowia louisecottisiae and Pseudosydowia queenslandica on living leaves of Eucalyptus sp. Brazil, Absidia montepascoalis from soil. Chile, Ilyonectria zarorii from soil under Maytenus boaria. Costa Rica, Colletotrichum filicis from an unidentified fern. Croatia, Mollisia endogranulata on deteriorated hardwood. Czech Republic, Arcopilus navicularis from tea bag with fruit tea, Neosetophoma buxi as endophyte from Buxus sempervirens, Xerochrysium bohemicum on surface of biscuits with chocolate glaze and filled with jam. France, Entoloma cyaneobasale on basic to calcareous soil, Fusarium aconidiale from Triticum aestivum, Fusarium juglandicola from buds of Juglans regia. Germany, Tetraploa endophytica as endophyte from Microthlaspi perfoliatum roots. India, Castanediella ambae on leaves of Mangifera indica, Lactifluus kanadii on soil under Castanopsis sp., Penicillium uttarakhandense from soil. Italy, Penicillium ferraniaense from compost. Namibia, Bezerromyces gobabebensis on leaves of unidentified succulent, Cladosporium stipagrostidicola on leaves of Stipagrostis sp., Cymostachys euphorbiae on leaves of Euphorbia sp., Deniquelata hypolithi from hypolith under a rock, Hysterobrevium walvisbayicola on leaves of unidentified tree, Knufia hypolithi and Knufia walvisbayicola from hypolith under a rock, Lapidomyces stipagrostidicola on leaves of Stipagrostis sp., Nothophaeotheca mirabibensis (incl. Nothophaeotheca gen. nov.) on persistent inflorescence remains of Blepharis obmitrata, Paramyrothecium salvadorae on twigs of Salvadora persica, Preussia procaviicola on dung of Procavia sp., Sordaria equicola on zebra dung, Volutella salvadorae on stems of Salvadora persica. Netherlands, Entoloma ammophilum on sandy soil, Entoloma pseudocruentatum on nutrient poor (acid) soil, Entoloma pudens on plant debris, amongst grasses. New Zealand, Amorocoelophoma neoregeliae from leaf spots of Neoregelia sp., Aquilomyces metrosideri and Septoriella callistemonis from stem discolouration and leaf spots of Metrosideros sp., Cadophora neoregeliae from leaf spots of Neoregelia sp., Flexuomyces asteliae (incl. Flexuomyces gen. nov.) and Mollisia asteliae from leaf spots of Astelia chathamica, Ophioceras freycinetiae from leaf spots of Freycinetia banksii, Phaeosphaeria caricis-sectae from leaf spots of Carex secta. Norway, Cuphophyllus flavipesoides on soil in semi-natural grassland, Entoloma coracis on soil in calcareous Pinus and Tilia forests, Entoloma cyaneolilacinum on soil semi-natural grasslands, Inocybe norvegica on gravelly soil. Pakistan, Butyriboletus parachinarensis on soil in association with Quercus baloot. Poland, Hyalodendriella bialowiezensis on debris beneath fallen bark of Norway spruce Picea abies. Russia, Bolbitius sibiricus on à moss covered rotting trunk of Populus tremula, Crepidotus wasseri on debris of Populus tremula, Entoloma isborscanum on soil on calcareous grasslands, Entoloma subcoracis on soil in subalpine grasslands, Hydropus lecythiocystis on rotted wood of Betula pendula, Meruliopsis faginea on fallen dead branches of Fagus orientalis, Metschnikowia taurica from fruits of Ziziphus jujube, Suillus praetermissus on soil, Teunia lichenophila as endophyte from Cladonia rangiferina. Slovakia, Hygrocybe fulgens on mowed grassland, Pleuroflammula pannonica from corticated branches of Quercus sp. South Africa, Acrodontium burrowsianum on leaves of unidentified Poaceae, Castanediella senegaliae on dead pods of Senegalia ataxacantha, Cladophialophora behniae on leaves of Behnia sp., Colletotrichum cliviigenum on leaves of Clivia sp., Diatrype dalbergiae on bark of Dalbergia armata, Falcocladium heteropyxidicola on leaves of Heteropyxis canescens, Lapidomyces aloidendricola as epiphyte on brown stem of Aloidendron dichotomum, Lasionectria sansevieriae and Phaeosphaeriopsis sansevieriae on leaves of Sansevieria hyacinthoides, Lylea dalbergiae on Diatrype dalbergiae on bark of Dalbergia armata, Neochaetothyrina syzygii (incl. Neochaetothyrina gen. nov.) on leaves of Syzygium chordatum, Nothophaeomoniella ekebergiae (incl. Nothophaeomoniella gen. nov.) on leaves of Ekebergia pterophylla, Paracymostachys euphorbiae (incl. Paracymostachys gen. nov.) on leaf litter of Euphorbia ingens, Paramycosphaerella pterocarpi on leaves of Pterocarpus angolensis, Paramycosphaerella syzygii on leaf litter of Syzygium chordatum, Parateichospora phoenicicola (incl. Parateichospora gen. nov.) on leaves of Phoenix reclinata, Seiridium syzygii on twigs of Syzygium chordatum, Setophoma syzygii on leaves of Syzygium sp., Starmerella xylocopis from larval feed of an Afrotropical bee Xylocopa caffra, Teratosphaeria combreti on leaf litter of Combretum kraussii, Teratosphaericola leucadendri on leaves of Leucadendron sp., Toxicocladosporium pterocarpi on pods of Pterocarpus angolensis. Spain, Cortinarius bonachei with Quercus ilex in calcareus soils, Cortinarius brunneovolvatus under Quercus ilex subsp. ballota in calcareous soil, Extremopsis radicicola (incl. Extremopsis gen. nov.) from root-associated soil in a wet heathland, Russula quintanensis on acidic soils, Tubaria vulcanica on volcanic lapilii material, Tuber zambonelliae in calcareus soil. Sweden, Elaphomyces borealis on soil under Pinus sylvestris and Betula pubescens. Tanzania, Curvularia tanzanica on inflorescence of Cyperus aromaticus. Thailand, Simplicillium niveum on Ophiocordyceps camponoti-leonardi on underside of unidentified dicotyledonous leaf. USA, Calonectria californiensis on leaves of Umbellularia californica, Exophiala spartinae from surface sterilised roots of Spartina alterniflora, Neophaeococcomyces oklahomaensis from outside wall of alcohol distillery. Vietnam, Fistulinella aurantioflava on soil. Morphological and culture characteristics are supported by DNA barcodes. Citation: Crous PW, Cowan DA, Maggs-Kölling, et al. 2021. Fungal Planet description sheets: 1182-1283. Persoonia 46: 313-528. https://doi.org/10.3767/persoonia.2021.46.11.

2.
Environ Sci Pollut Res Int ; 21(7): 4847-60, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23695856

RESUMO

The management of certain plant beneficial microorganisms [biological control agents (BCAs)] seems to be a promising and environmental friendly method to control plant pathogens. However, applications are still limited because of the lack of consistency of BCAs when they are applied in the field. In the present paper, the advantages and limitations of BCAs are seen through the example of Pythium oligandrum, an oomycete that has received much attention in the last decade. The biological control exerted by P. oligandrum is the result of a complex process, which includes direct effects through the control of pathogens and/or indirect effects mediated by P. oligandrum, i.e. induction of resistance and growth promotion. P. oligandrum antagonism is a multifaceted and target fungus-dependent process. Interestingly, it does not seem to disrupt microflora biodiversity on the roots. P. oligandrum has an atypical relationship with the plant because it rapidly penetrates into the root tissues but it cannot stay alive in planta. After root colonisation, because of the elicitation by P. oligandrum of the plant-defence system, plants are protected from a range of pathogens. The management of BCAs, here P. oligandrum, is discussed with regard to its interactions with the incredibly complex agrosystems.


Assuntos
Controle Biológico de Vetores/métodos , Pythium/crescimento & desenvolvimento , Adaptação Fisiológica , Biodiversidade , Fungos/efeitos dos fármacos , Fungos/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Pythium/microbiologia
3.
J Appl Microbiol ; 111(6): 1436-46, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21951641

RESUMO

AIMS: To predict the risk factors for building infestation by Serpula lacrymans, which is one of the most destructive fungi causing timber decay in buildings. METHODS AND RESULTS: The growth rate was assessed on malt extract agar media at temperatures between 1.5 and 45°C, at water activity (a(w)) over the range of 0.800-0.993 and at pH ranges from 1.5 to 11.0. The radial growth rate (µ) and the lag phase (λ) were estimated from the radial growth kinetics via the plots radius vs time. These parameters were then modelled as a function of the environmental factors tested. Models derived from the cardinal model (CM) were used to fit the experimental data and allowed an estimation of the optimal and limit values for fungal growth. Optimal growth rate occurred at 20°C, at high a(w) level (0.993) and at a pH range between 4.0 and 6.0. The strain effect on the temperature parameters was further evaluated using 14 strains of S. lacrymans. The robustness of the temperature model was validated on data sets measured in two different wood-based media (Quercus robur L. and Picea abies). CONCLUSIONS: The two-step procedure of exponential model with latency followed by the CM with inflection gives reliable predictions for the growth conditions of a filamentous fungus in our study. The procedure was validated for the study of abiotic factors on the growth rate of S. lacrymans. SIGNIFICANCE AND IMPACT OF THE STUDY: This work describes the usefulness of evaluating the effect of physico-chemical factors on fungal growth in predictive building mycology. Consequently, the developed mathematical models for predicting fungal growth on a macroscopic scale can be used as a tool for risk assessment of timber decay in buildings.


Assuntos
Basidiomycota/crescimento & desenvolvimento , Materiais de Construção/microbiologia , Modelos Biológicos , Temperatura , Água/fisiologia , Basidiomycota/fisiologia , Meios de Cultura , Concentração de Íons de Hidrogênio , Microbiologia da Água , Madeira/microbiologia
4.
Lett Appl Microbiol ; 51(1): 18-23, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20477955

RESUMO

AIMS: To evaluate and optimize the use of denaturing high-performance liquid chromatography (DHPLC) for yeasts identification in red smear cheese surfaces. METHODS AND RESULTS: The resolution of DHPLC was first evaluated and optimized using a mixture of PCR amplicons of the internal transcribed spacer 2 (ITS2) region of 19 yeast reference strains representing 18 species that are common in the cheese microbiota. Sixteen of the 18 yeast species could be resolved by combining runs at temperatures of 57.5 and 59 degrees C. Then, DHPLC was used to investigate the yeast microbiota of pasteurized Maroilles, Munster and Livarot cheese surfaces by comparing their peak profiles with our reference yeast database and by collecting/sequencing of peak fractions. Debaryomyces hansenii and Geotrichum candidum for Munster and Maroilles cheeses, and Candida catenulata, Candida intermedia and G. candidum for Livarot cheese were identified using the reference database and collecting/sequencing of peak fractions. CONCLUSIONS: DHPLC technique was found to have good resolution properties and to be useful for investigating the yeast microbiota of red smear cheese surfaces. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first time that DHPLC is applied to study the yeast microbiota of red smear cheese surfaces.


Assuntos
Queijo/microbiologia , Cromatografia Líquida de Alta Pressão/métodos , DNA Fúngico/genética , DNA Fúngico/isolamento & purificação , Micologia/métodos , Leveduras/classificação , Leveduras/genética , Biodiversidade , DNA Intergênico/genética , DNA Intergênico/isolamento & purificação , Análise de Sequência de DNA , Leveduras/isolamento & purificação
5.
J Fr Ophtalmol ; 24(4): 349-59, 2001 Apr.
Artigo em Francês | MEDLINE | ID: mdl-11351206

RESUMO

INTRODUCTION: Above -6 diopters, Lasik procedure has shown its superiority in term of predictibility, efficacy and stability. In the adverse, in the field of low myopia, Lasik and surface excimer photoablation (PRK) are very controversial. We compare quantitative and qualitative outcome achieved in series of 25 PRK operated patients and 25 Lasik. MATERIAL AND METHOD: 2 homogeneous groups were constituted: group A for Excimer patients and group B for Lasik. Initial ametropia had to be ranged between -2 and -6 diopters (D), eventually associated to a myopic astigmatism that needed to be under -1,75 D. Excimer laser model was a Visx (Visx 20/20 or Star S2). In case of Lasik, flap was performed with an Automated corneal shaper microkératom (Baush & Lomb) or with a Flap Maker (Ioltech). Evaluation of refraction and visual results was associated to measurements of contrast and glare sensitivities and collection of functional complaints. RESULTS: A retrospective analysis is performed with a 2 years follow-up. At that term, rate of eyes, that achieved 20/20 or better is comparable in the two groups (62% in group A and 64% in group B). However, profile of visual recovery goes faster after Lasik. Best corrected visual acuity is favorably preserved in two groups, but is altered with glare in Lasik group. Cycloplegic refraction shows a tendency to regression more important in case of surface ablation (10% versus 4%), especially above -4 D (28%). No significant difference is noted concerning contrast sensitivity, correctly unchanged in the two groups. No case of severe complication is mentioned after both surgical methods. DISCUSSION-CONCLUSION: In the field of low myopia, PRK and Lasik appear to guarantee same predictibility and safety, in conditions of preliminary learning curve. Stability and visual recovery are earlier achieved after Lasik, in addition to postoperative indolence. However, application of this technique to all degrees of myopia requires its perfect control and an adjustment of ablation nomograms.


Assuntos
Ceratomileuse Assistida por Excimer Laser In Situ , Miopia/cirurgia , Ceratectomia Fotorrefrativa , Adulto , Humanos , Ceratomileuse Assistida por Excimer Laser In Situ/efeitos adversos , Lasers de Excimer , Ceratectomia Fotorrefrativa/efeitos adversos , Estudos Retrospectivos
6.
J Fr Ophtalmol ; 24(2): 147-52, 2001 Feb.
Artigo em Francês | MEDLINE | ID: mdl-11240485

RESUMO

PURPOSE: To determine the profile and motivations of patients who are candidates for refractive surgery. MATERIAL: and METHODS: We studied 102 patients with low myopia (less than 6 diopters) in a single-center investigation. RESULTS: Among the total population studied, the motivation for refractive surgery was essentially comfort and appearance. Fewer men wore contact lenses than women and had worn them for a shorter period of time. Those involved in sports were more often in individual sports. Contact-lens wearers were most often students or in the paramedical professions. DISCUSSION: The population interested in refractive surgery was very young. The proportion of candidates who had never worn contact lenses was surprisingly high. CONCLUSION: This analysis suggests that patients too often consider refractive surgery as an easy option.


Assuntos
Lentes de Contato , Miopia/cirurgia , Adolescente , Adulto , Fatores Etários , Interpretação Estatística de Dados , Estética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Motivação , Ocupações , Fatores Sexuais , Esportes
7.
J Fr Ophtalmol ; 23(6): 555-62, 2000 Jun.
Artigo em Francês | MEDLINE | ID: mdl-10880920

RESUMO

PURPOSE: To compare effect of two topical non steroidal anti-inflammatory (NSAI) drugs: Indomethacin (Indocollyre)0.1 %, Chauvin Inc.) and Diclofenac (Voltaren 0.1%, Cibavision) on postoperative pain and epithelial regrowth following surface excimer photoablation. MATERIAL AND METHOD: Eighty-six excimer operated patients, were divided in two similar groups depending on the NSAI instilled postoperatively and for 3 days (4 drops daily). No patient was informed of any other available drug. Pain intensity was quantified between 1 and 10 according to an analog scale (reported from 1 to 10 hours, then 4 times a day during 7 days). Complementary medications and functional symptoms were also notified. Biomicroscopic evaluation using fluorescein test was performed to assess reepithelialization. RESULTS: In term of pain, no significative difference was observed between the two groups concerning intensity, associated medications, or numbers of days of discomfort. Controversially, retreated eyes might induce more pain than initial treatments. No delay in epithelial regrowth was noted and the difference between the two groups in functional complaints was no statistically significant. Pain appears to be not related to ablation depth. DISCUSSION- CONCLUSION: Our results are correlated to literature reported data. Introduction of NSAI constitutes a real advent in the care of excimer postoperative pain. Effect of indomethacin seems comparable to diclofenac effect, but might be of interest because of no anesthetic property that might guarantee of no delay in wound healing response.


Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Diclofenaco/uso terapêutico , Indometacina/uso terapêutico , Dor Pós-Operatória/tratamento farmacológico , Ceratectomia Fotorrefrativa/efeitos adversos , Adulto , Feminino , Humanos , Lasers de Excimer , Masculino , Medição da Dor , Estudos Prospectivos
8.
J Fr Ophtalmol ; 21(3): 191-208, 1998 Mar.
Artigo em Francês | MEDLINE | ID: mdl-9759405

RESUMO

OBJECTIVES OF THE STUDY: Intra-stromal rings (ICR) represent a new method for low myopic correction. An indirect central flattening is induced by a peripheral steepening related to the segments. This surgery was recently approved in Europe, but is still under evaluation in the multicenter study controlled by the FDA (Food and Drug Administration). We took part in that protocol and report our results at one year follow-up. MATERIAL AND METHOD: Twenty-five patients were included in the study with 47 operated eyes and a follow-up between 3 to 18 months. Data relative to refractive results, quality of the vision and anatomic changes induced by intrastromal segments will be collected at the issue of a rigorous survey. RESULTS: At one year, non-corrected visual acuity was 20/40 or better in 100% and 20/20 in 60%. We noted no loss in best visual acuity and an improvement of one or two lines in 20% of operated eyes. No significative changes were observed concerning: intraocular pressure, corneal sensitivity, central pachymetry or corneal endothelium. Three eyes had to be explanted and recovered the preoperative refraction. No severe complications were observed. DISCUSSION: Analysis of results is in favor of the efficacy, predictability and reproductibility of the surgery, which might be better with rings of a diameter under 0.40 mm. Occurrence of postoperative astigmatism appears to constitute the main limit suggesting discussion on etiologic factors and modalities of treatment. CONCLUSION: This concept of intra-corneal rings appears particularly promising for correction of low myopia and maybe in the near future for correction of others ametropia, requiring design of new specific segments. Essential interest of this surgery is the respect of the central area and its potential reversibility.


Assuntos
Córnea/cirurgia , Miopia/cirurgia , Próteses e Implantes , Adulto , Astigmatismo/etiologia , Feminino , Seguimentos , Humanos , Masculino , Teste de Materiais , Próteses e Implantes/efeitos adversos , Refração Ocular , Reprodutibilidade dos Testes , Resultado do Tratamento , Acuidade Visual
9.
Ophthalmology ; 105(7): 1182-8, 1998 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9663219

RESUMO

OBJECTIVE: The purpose of the study was to evaluate the precision, accuracy, and safety of three different modes of excimer laser surgery for myopic astigmatism. DESIGN: A prospective interventional case series. PARTICIPANTS: A total of 150 eyes with compound myopic astigmatism were treated. INTERVENTION: Ablation programs included the VISX Twenty/Twenty excimer laser using either the sequential mode (58 eyes) or the elliptical mode (54 eyes) and the Technolas-Chiron Keracor 116 hybrid scanning laser (38 eyes). MAIN OUTCOME MEASURES: Reduction in cylinder and sphere, vector analysis (polar values), uncorrected visual acuity, and best spectacle-corrected visual acuity were evaluated at 1, 6, and 12 months. RESULTS: By 12 months, sphere was reduced by 95.1%, 87.7%, and 75% in low-astigmatism eyes treated with the VISX sequential, VISX elliptical, and Technolas modes, respectively, and by 92.2%, 98%, and 77.6% in high-astigmatism eyes. By 12 months, cylinder was reduced by 51.5%, 72.2%, and 36.3% in low-astigmatism eyes and by 70%, 78%, and 45.6%, respectively, in high-astigmatism eyes. Vector analysis showed that the elliptical treatment produced more significant reductions in mean polar values than the other two treatments at various timepoints. CONCLUSION: These results suggest that the ablation approach may influence the clinical result.


Assuntos
Astigmatismo/cirurgia , Córnea/cirurgia , Miopia/cirurgia , Ceratectomia Fotorrefrativa , Adulto , Algoritmos , Feminino , Seguimentos , Humanos , Lasers de Excimer , Masculino , Ceratectomia Fotorrefrativa/métodos , Estudos Prospectivos , Reprodutibilidade dos Testes , Segurança , Resultado do Tratamento , Acuidade Visual
11.
J Fr Ophtalmol ; 20(10): 758-66, 1997.
Artigo em Francês | MEDLINE | ID: mdl-9587590

RESUMO

PURPOSE: In advanced keratoconus, when contact lenses become intolerant or provide insufficient vision, the only current available treatment is penetrating keratoplasty. But getting a graft takes a long time; we evaluated the eventual role of Excimer laser in taking care of those patients. MATERIAL AND METHODS: We present a series of 8 advanced keratoconus, at that time, intolerant to contact lens because of a major ectasia and/or apical opacities. An excimer photoablation, using the therapeutic or rarely the refractive one, was performed in order to flatten or resurface the cornea, allowing a new contact lens fitting. RESULTS: We noted no complication, except a denser and longer postoperative haze. Thanks to a good compliance, 4 patients benefited from a new contact lens fitting, leading to an optimal visual recovery. On the other hand, in 3 cases, a corneal graft had to be performed, without any side effect. An anatomo-pathologic analysis was achieved on the 3 corneal caps, giving some precisions about tissular changes. CONCLUSION: Excimer laser, under its therapeutic approach, might be an efficient treatment for advanced keratoconus, in conditions of cautious indications selection and of an inevitable coupling to contactology. Then, this surgery could delay or even avoid penetrating keratoplasty.


Assuntos
Ceratocone/cirurgia , Ceratectomia Fotorrefrativa , Adulto , Estudos de Avaliação como Assunto , Feminino , Seguimentos , Humanos , Lasers de Excimer , Masculino , Pessoa de Meia-Idade , Acuidade Visual
12.
J Cataract Refract Surg ; 22(10): 1423-6, 1996 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9051496

RESUMO

PURPOSE: To evaluate the visual and refractive results of photorefractive keratectomy (PRK) in eyes with atypical inferior corneal steepening (AICS). SETTING: Department of Ophthalmology, Hôpital Morvan, University of Breast, France. METHODS: Using videokeratopography, we screened 310 eyes that had PRK from November 1992 through November 1993 and found that 35 eyes exhibited topographic patterns consistent with AICS with no clinical findings. The results at 6 months and 1 year were compared with those of 185 eyes with normal topography treated concurrently. RESULTS: There were no statistically significant differences between the two groups in mean spherical equivalent, mean uncorrected visual acuity, and mean best spectacle-corrected visual acuity 6 months and 1 year after PRK. CONCLUSION: After 1 year, PRK in eyes with AICS appeared to give results similar to those in eyes with normal topography. Further follow-up is needed.


Assuntos
Córnea/cirurgia , Miopia/cirurgia , Ceratectomia Fotorrefrativa/métodos , Adulto , Córnea/fisiopatologia , Seguimentos , Humanos , Processamento de Imagem Assistida por Computador , Lasers de Excimer , Miopia/fisiopatologia , Oftalmoscopia , Refração Ocular , Reprodutibilidade dos Testes , Estudos Retrospectivos , Resultado do Tratamento , Acuidade Visual
14.
Behav Brain Res ; 70(1): 15-29, 1995 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-8519425

RESUMO

Learning a conditioned stimulus (CS)-unconditioned stimulus (US) association is accompanied by a variety of long-lasting changes in physiology and chemistry of the synapse in the dentate gyrus. To determine the time course of synaptic modification during learning, changes in the perforant path-dentate gyrus-evoked field potentials were measured in rats performing a classical conditioning (paired tone and footshock) or pseudoconditioning (unpaired tone and footshock) task. Over the course of 4 days of training, differential changes in the evoked response were observed in the two groups. In the conditioned group, there was an increase in the slope of the excitatory postsynaptic potential (EPSP) which started after five tone-shock paired trials and lasted for more than 40 min, outlasting the training session by 20 min. In contrast, a decrease in the slope of the EPSP which commenced after training and lasted for at least 1 h was observed in the pseudoconditioned group. In both groups there was a prolonged decrease in the amplitude of the population spike. The increase in the EPSP was reduced and the duration tended to shorten over days of training in the conditioned group, whereas in the pseudoconditioned group the decrease in the EPSP tended to increase. Off-line analysis of suppression of lever-pressing for food reward during the presentation of the tone, indicated that the conditioned rats had learned the tone-footshock association. Temperature was measured in the dentate gyrus of rats undergoing an identical procedure. In both groups slight temperature increases were observed, with no difference in amplitude and time-course between the groups. The differential effect of conditioning and pseudoconditioning on the evoked response and changes in temperature eliminate the possibility that effects of stress, arousal and muscular effort are the primary cause of the changes in the EPSP. The results suggest that behavioural events can exert bidirectional control of synaptic strength of entorhinal cortex inputs to the dentate gyrus and that the sign of synaptic modification is at least in part determined by the temporal relationship between these events. The data are discussed in terms of the type of neural activity that may mediate the processing of information in the dentate gyrus.


Assuntos
Condicionamento Clássico/fisiologia , Giro Denteado/fisiologia , Potenciação de Longa Duração/fisiologia , Plasticidade Neuronal/fisiologia , Sinapses/fisiologia , Animais , Comportamento Animal/fisiologia , Temperatura Corporal/fisiologia , Condicionamento Operante/fisiologia , Giro Denteado/citologia , Estimulação Elétrica , Eletrofisiologia , Potenciais Evocados/fisiologia , Masculino , Ratos , Ratos Sprague-Dawley
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