engleski

Distribution Of Migratory Zones In Optic Tectum Of Teleostea

Teleostea are well adapted to specific ecological niches and such adaptation is reflected in some brain regions, like optic tectum. The aim of this study was to investigate if fishes inhabiting different niches and having different style of food finding differ in distribution of migratory zones in optic tectum. Migratory zones were identified as expression of PSA-NCAM in optic tectum of fishes extensively using vision and living in clear water (trout Onchorincus mykiss, pike Esox lucius and perch Perca fluviatilis) or benthic zone species depending on sense of taste and smell (carp Cyprinus carpio, catfish Silurus glanis and zebrafish Danio rerio). PSA-NCAM expression is detected using antibodies (mAb735 and clone 2-2B) and compared with distribution of neuronal marker (NeuN) or marker of myelinated fibers (SMI312). Adult neurogenesis persist in periventricular layer of optic tectum and torus longitudinalis. Both regions are PSA-NCAM positive in all investigated species. Torus longitudinalis project unmyelinated parallel fibers to stratum marginale of tectum which is also strongly PSA-NCAM positive in all species. In sight dependant species (trout, perch and pike) PSA-NCAM negative are stratum opticum (containing dendrites of intrinsic projection neurons and retinal afferents) and stratum album (the major tectal efferent layer). The same layers are positive in catfish, carp and zebrafish. Retina and tectum continuously grow during Teleostean life what requires persistent remodeling in an effort to maintain a proper map of retinotectal afferents as well as map of extratectal projections. In species which do not have dominant sense of sight, due to PSA-NCAM expression, remodeling is sustained in all tectal layers. Species with dominant sense of sight have limited remodeling in one of incoming layers and also in the major outcoming zone. Therefore they have probably more stable circuitry for visiomotor coordination.

teleostea; optic tectum; migratory zones

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