Bile acids as potential pheromones in pintado catfish Pseudoplatystoma corruscans (Spix & Agassiz, 1829): eletrophysiological and behavioral studies

Bile acids are potent olfactory and gustatory stimulants for fish. Electro-olfactogram recording was used to test whether the olfactory epithelium of pintado catfish Pseudoplatystoma corruscans is specifically sensitive to bile acids, some of which have been hypothesized to function as pheromones. Five out of 30 bile acids that had been pre-screened for olfactory activity in fish were selected. Cross-adaptation experiments demonstrated that sensitivity to bile acids is attributable to at least 3 independent classes of olfactory receptor sites. The taurocholic acid (TCA) and taurochenodeoxycholic acid (TCD) were the most potent compounds. By using avoidance/preference tests, we found that P. corruscans prefers water containing TCA. Bile acids are discriminated by olfactory epithelium of pintado, supporting that these compounds could function as pheromones.

Os ácidos biliares são potentes estimulantes olfatórios e gustatórios em peixes. Registros em eletro-olfactograma foram usados para testar se o epitélio olfatório de Pseudoplatystoma corruscans, pintado, é sensível aos ácidos biliares, alguns dos quais têm sido propostos como feromônios. Foram selecionados cinco de uma lista de trinta ácidos biliares previamente testados em atividade olfatória em peixes. Testes de adaptação cruzada demonstraram que a sensibilidade aos ácidos biliares se dá por 3 classes independentes de sites de receptores olfatórios. O ácido taurocólico (TCA) e o ácido tauroquenodesoxicólico (TCD) foram os compostos mais potentes. Em testes de evasão/preferência, P. corruscans prefere água contendo o ácido TCA. Os ácidos biliares são discriminadas por epitélio olfatório de pintado, evidenciando que estes compostos podem funcionar como feromônios.

Dispositivo baseado em eletrooculograma para auxílio de deficientes físicos na utilização do computador / Electrooculogram based device to aid disabled in computer

In this project we present a device for aid physically challenged people to use microcomputers. The base of this development is the signal called EOG (Eletrooculography) that it consists of the difference of potential between the cornea and the retina where the heaves horizontal and diagonal moviments of the eye can be registered way electrodes...

The Developement of An Objective Test for Visual Acuity Assessment Using Optokinetic Nystagmus Stimuli Presented Head-Mounted Display: Seohan Objective Visual Acuity Test

The objective visual acuity test is mandatory in certain cases, such as infants, nonverbal subjects and subjects who need legal judgements. To produce more reliable objective method, we made a new objective system for visual acuity test which is called Seohan visual acuity test(SVT). The SVT system has three elements such as stimuli, display and evaluation. For the visual stimuli, the computer program for optokinetic nystagmus(OKN)test was set up in personal computer to control the size, speed and direction of the stimuli easily. The visual stimuli are presented on HeadMounted-Display(HMD)to separate the stimuli from the environment to keep the uniform size and distance of screen to the eye of subjects and project the stimulus in full central field of patient. Electrooculography(EOG) was used to assess the visual acuity more objectively. To evaluate the usefulness of SVT, the smallest size of the stimulus to elicit OKN(objective visual acuity)with SVT was obtained in 10 eyes in each twelve grade of subjective visual acuity(decimal V). Objective visual acuity(VA)were distributed from 8.3+/-1.87 to 21.4+/-3.1 and showed high correlation(p<0.00 ). The relationship between the objective VA obtained from SVT and subjective VA make a regression line(y=-12.874X+21.303).Subjective VA could be obtained from conversion of objective VA with 95%confidence belt. In conclusion, the objective visual acuity with SVT is highly correlated with subjective visual acuity and SVT using the OKN response to stimuli presented on HMD by the computer program can be useful in assessing visual function objectively.