Control of feeding by Piezo-mediated gut mechanosensation in Drosophila

Across animal species, meals are terminated after ingestion of large food volumes, yet underlying mechanosensory receptors have so far remained elusive. Here, we identify an essential role for Drosophila Piezo in volume-based control of meal size. We discover a rare population of fly neurons that express Piezo, innervate the anterior gut and crop (a food reservoir organ), and respond to tissue distension in a Piezo-dependent manner. Activating Piezo neurons decreases appetite, while Piezo knockout and Piezo neuron silencing cause gut bloating and increase both food consumption and body weight. These studies reveal that disrupting gut distension receptors changes feeding patterns, and identify a key role for Drosophila Piezo in internal organ mechanosensation.

Control of feeding by Piezo-mediated gut mechanosensation in Drosophila

SUMMARYAcross animal species, meals are terminated after ingestion of large food volumes, yet underlying mechanosensory receptors have so far remained elusive. Here, we identify an essential role for Drosophila Piezo in volume-based control of meal size. We discover a rare population of fly neurons that express Piezo, innervate the anterior gut and crop (a food reservoir organ), and respond to tissue distension in a Piezo-dependent manner. Activating Piezo neurons decreases appetite, while Piezo knockout and Piezo neuron silencing cause gut bloating and increase both food consumption and body weight. These studies reveal that disrupting gut distension receptors changes feeding patterns, and identify a key role for Drosophila Piezo in internal organ mechanosensation.

Activity of selected hydrolytic enzymes from leeches (Clitellata: Hirudinida) with different feeding strategies

Hydrolase activities of extracts from different parts of the bodies of parasitic (Theromyzon tessulatum, Piscicola geometra) and predatory (Erpobdella octoculata, Glossiphonia complanata) leeches were examined. The highest activity was detected in the extracts from sections containing the intestine. Hydrolase activities in the crop and intestine of parasitic leeches were higher than in predatory leeches. The high activity of most of hydrolases in those segments may indicate the intensity of digestion and absorption processes in leeches. A lack of trypsin activity and low chymotrypsin activity are likely to result from the presence of inhibitors of these enzymes. The high activity of the majority of the analyzed hydrolases in extracts derived from the head segment of predatory leeches enables, through digestion of tissues, their easy access to physiological fluids of a host. In turn, in extracts from the head segment of predatory leeches, only four hydrolases were shown to be active. Lipase activity was not found in any of the samples, while α-galactosidase activity was found only in extracts from the head segment of T. tessulatum and P. geometra. Trypsin activity was detected in the extract from the intestine contents of H. sanguisuga and in the extract from the head segment of P. geometra. The results demonstrate the presence of majority of hydrolases occurring in other animals in the alimentary tract of leeches. The study also shows that the crop of leeches is not only a food reservoir, but also the site where digestion and absorption processes take place.

SOROEPIDEMIOLOGIA E FATORES ASSOCIADOS À TRANSMISSÃO DO Toxoplasma gondii EM SUÍNOS DO NORTE DO PARANÁ

Devido à importância do suíno como fonte de infecção da toxoplasmose humana e aos problemas reprodutivos gerados por esta enfermidade, objetivou-se traçar o perfil soroepidemiológico e os fatores associados à transmissão do Toxoplasma gondii no rebanho de suínos da região Norte do Paraná. Coletaram-se amostras de 521 animais (324 matrizes, 157 marrãs e 40 cachaços), de 22 propriedades suinícolas. Foi aplicado um questionário epidemiológico para verificar as características em relação aos manejos adotados. Realizou-se Imunofluorescência Indireta (IFI) para detecção de anticorpos anti-T. gondii (IgG) e considerou-se positivas as amostras que apresentaram título ³ 64. De 521 amostras de soro analisadas pela IFI, resultaram em 15,35% reagentes (80/521), sendo 54 (10,37%) matrizes, 20 (3,83%) marrãs e seis (1,15%) cachaços. A análise das variáveis evidenciou que o sistema de criação intensivo foi um fator de proteção para a presença de T. gondii. Entretanto, o acesso de outros animais ao cocho de ração e ao reservatório de água, a utilização do bebedouro tipo canaleta, presença de lâmina d’água nas baias e a existência de áreas alagadiças, foram fatores que contribuíram para a infecção pelo T. gondii. Serumepidemiology and associated factors on swine transmission of Toxoplasma gondii at Northern Paraná – Brazil Abstract Due to the importance of swine as an infection source of toxoplasmosis to man and the reproductive problems that this disease causes, it was defined the prevalence and the factors associated with the transmission of Toxoplasma gondii in swine herds of northern Paraná State. A total of 521 serum samples (324 sows, 157 gilts e 40 boars) from 22 herds were analyzed and an epidemiological questionnaire was applied to obtain the management employed in these properties. The indirect immunofluorescence (IFAT) test was performed to detect anti-T. gondii antibodies (IgG) and titers ³ 64 were considered positive. From the 521 analyzed serum samples, 15.35% (80/521) were reactive for the IFAT test – 54 (10.37%) sows, 20 (3.83%) gilts and 6 (1.15%) boars. The statistical analysis has shown that the intensive management system is a protective factor for T. gondii infection. However, the access of other animals to the water and food reservoir, the channel’s water-thought, the pens with water-blade and the presence of wet areas were factors which contributed to wards the infection by T. gondii.

Universal eating monitor for continuous recording of solid or liquid consumption in man

A universal eating monitor has been developed that permits covert continuous weighing of a subject's plate or other food reservoir by means of a concealed electronic balance. By coupling the device with a digital computer, it is possible to record precisely the amount consumed every 3 s throughout a single-course meal consisting of a relatively homogeneous mixture of foods. The monitor have been used to compare total intake, meal duration, initial rate of intake, and deceleration of intake in human subjects ingesting either a solid or liquid version of the same food after 3 or 6 h without food. It was found that the liquid form was eaten faster than the solid form, but that total amounts consumed in each form were not significantly different. These results suggest that when the rate of consumption is controlled by the physical consistency of the food, the amount eaten is not determined by the rate of consumption alone. Further studied are necessary to determine the relative roles of visual cues and interoceptive signals on quantity eaten.