Postprandial morphological response of the intestinal epithelium of the Burmese python (Python molurus)

The postprandial morphological changes of the intestinal epithelium of Burmese pythons were examined using fasting pythons and at eight time points after feeding. In fasting pythons, tightly packed enterocytes possess very short microvilli and are arranged in a pseudostratified fashion. Enterocyte width increases by 23% within 24 h postfeeding, inducing significant increases in villus length and intestinal mass. By 6 days postfeeding, enterocyte volume had peaked, following as much as an 80% increase. Contributing to enterocyte hypertrophy is the cellular accumulation of lipid droplets at the tips and edges of the villi of the proximal and middle small intestine, but which were absent in the distal small intestine. At 3 days postfeeding, conventional and environmental scanning electron microscopy revealed cracks and lipid extrusion along the narrow edges of the villi and at the villus tips. Transmission electron microscopy demonstrated the rapid postprandial lengthening of enterocyte microvilli, increasing 4.8-fold in length within 24 h, and the maintaining of that length through digestion. Beginning at 24 h postfeeding, spherical particles were found embedded apically within enterocytes of the proximal and middle small intestine. These particles possessed an annular-like construction and were stained with the calcium-stain Alizarine red S suggesting that they were bone in origin. Following the completion of digestion, many of the postprandial responses were reversed, as observed by the atrophy of enterocytes, the shortening of villi, and the retraction of the microvilli. Further exploration of the python intestine will reveal the underlying mechanisms of these trophic responses and the origin and fate of the engulfed particles

Réponses morpho-fonctionnelles du système digestif du python de Birmanie (python molurus bivittatus) au jeûne et à la réalimentation

Le jeûne et la régulation des fonctions digestives sont des thèmes qui ont été longuement étudiés chez les Vertébrés supérieurs. La description des étonnantes capacités de jeûne du Python de Birmanie, Python molurus, a ainsi soulevé de nombreuses interrogPas de résum

Réponses morpho-fonctionnelles du système digestif du python de Birmanie (python molurus bivittatus) au jeûne et à la réalimentation

Le jeûne et la régulation des fonctions digestives sont des thèmes qui ont été longuement étudiés chez les Vertébrés supérieurs. La description des étonnantes capacités de jeûne du Python de Birmanie, Python molurus, a ainsi soulevé de nombreuses interrogations et laissé supposer l'existence de réponses physiologiques ajustées à la privation d'aliments différentes de celles des Mammifères. Cette thèse s'inscrit dans ce contexte d'exploration fonctionnelle du système digestif de Python molurus bivittatus. Elle a en effet pour objet de décrire les adaptations morpho-fonctionnelles requises par le jeûne et la réalimentation, d'en déterminer les mécanismes sous-jacents et de comprendre quelles en sont les portées écologiques [etc ]Pas de résum

Réponses morpho-fonctionnelles du système digestif du python de Birmanie (python molurus bivittatus) au jeûne et à la réalimentation

Le Python de Birmanie peut endurer de longues périodes de jeûne, à l instar d animaux migrants ou hibernants, en partie grâce à l atrophie de son système digestif. Il retrouve ses fonctionnalités gastro-intestinales quasi-simultanément à l ingestion de sa proie, ce qui implique des ajustements physiologiques amples et rapides. Cette flexibilité, étudiée au niveau de l estomac, de l intestin et du côlon repose sur des réversions de structures de la muqueuse qui sollicite une faible mobilisation des réserves énergétiques. L accroissement de la surface intestinale repose à la fois sur une incorporation massive de gouttelettes lipidiques dans les entérocytes et par une modulation remarquable de la longueur de leurs microvillosités. La synchronisation des processus digestifs permet, au moment où la disponibilité énergétique est maximale, la mise en réserve des effecteurs principaux de la digestion et de l absorption, le renouvellement cellulaire et le recyclage des structures intra-cellulaires. Considéré depuis 25 ans comme un excellent modèle d étude en physiologie digestive puis cardio-vasculaire, le Python de Birmanie pourrait aujourd hui s imposer comme un nouveau modèle d étude en biologie cellulaire de part la remarquable flexibilité des cellules de son tractus digestif et, de part la découverte de cellules intestinales particulières associées à des concrétions calciques, ou sphéroïdes, dont la fonction est discutée.The Burmese python can endure prolonged fasting periods, as migratory or hibernating animals, partly due to the atrophy of its digestive system. This snake species can recover its gastro-intestinal functionalities immediately after the ingestion of the prey. It implies large and rapid physiological adjustments. This flexibility, studied in the stomach, small and large intestine, relies on structural reversions of the mucosa requiring few energetically reserves. The increment of the intestinal surface is mostly due to the massive incorporation of lipid droplets in the enterocytes, but also to the modulation of the length of their microvilli. The tight synchronisation of the digestive processes permits cell renewal, intra-cellular structural recycling and storage of the major digestive and absorptive effectors inside the cell. Known for 25 years as an excellent model in digestive and then cardio-vascular physiology, the Burmese python could be considered today as a new model in cell biology because of the remarkable flexibility of its enterocytes and the discovery of a new intestinal cell type associated to calcium-rich concretions, the spheroids, and whose function is discussed.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

The effects of feeding on cell morphology and proliferation of the gastrointestinal tract of juvenile Burmese pythons (Python molurus)

The gastrointestinal tract of Burmese pythons ( Python molurus (L., 1758)) exhibits large morphological and physiological changes in response to feeding and extended periods of fasting. In this study the mucosa of the stomach, small intestine, and colon were examined for changes in structure and cellular proliferation. The mucosa of fasting pythons exhibited low levels of cellular replication, but after feeding, cellular replication was evident as early as 12 h in the small intestine and colon and 24 h in the stomach. Replication peaked 3 days postfeeding for the small intestine and colon, but was still increasing at 6 days postfeeding in the stomach. Interestingly, cell proliferation was still evident after 45 days in the colon. In these tissues, a stock of “ready-to-use” primary lysosomes is found in the mucosal cells of fasting animals, whereas profound intracellular recycling is typical of animals that have been fed. These findings indicate that during the postprandial period, the intestinal mucosa undergoes extensive remodelling in anticipation of the next fasting and feeding period. One key adaptive factor for the python’s ability to cope with infrequent feeding is a well-prepared digestive system in fasting animals that can quickly start functioning again when food becomes available.</jats:p

The effects of feeding on cell morphology and proliferation of the gastrointestinal tract of juvenile Burmese pythons (Python molurus)

International audienceFourati H., Manamanni N., Afilal L. & Handrich Y. (2010). A nonlinear filtering approach for the attitude and dynamic body acceleration estimation based on inertial and magnetic sensors: bio-logging application. IEEE Sensors Journal in press

The sunflower genome provides insights into oil metabolism, flowering and Asterid evolution

The domesticated sunflower, Helianthus annuus L., is a global oil crop that has promise for climate change adaptation, because it can maintain stable yields across a wide variety of environmental conditions, including drought. Even greater resilience is achievable through the mining of resistance alleles from compatible wild sunflower relatives, including numerous extremophile species. Here we report a high-quality reference for the sunflower genome (3.6 gigabases), together with extensive transcriptomic data from vegetative and floral organs. The genome mostly consists of highly similar, related sequences and required single-molecule real-time sequencing technologies for successful assembly. Genome analyses enabled the reconstruction of the evolutionary history of the Asterids, further establishing the existence of a whole-genome triplication at the base of the Asterids II clade and a sunflower-specific whole-genome duplication around 29 million years ago. An integrative approach combining quantitative genetics, expression and diversity data permitted development of comprehensive gene networks for two major breeding traits, flowering time and oil metabolism, and revealed new candidate genes in these networks. We found that the genomic architecture of flowering time has been shaped by the most recent whole-genome duplication, which suggests that ancient paralogues can remain in the same regulatory networks for dozens of millions of years. This genome represents a cornerstone for future research programs aiming to exploit genetic diversity to improve biotic and abiotic stress resistance and oil production, while also considering agricultural constraints and human nutritional needs