Izbjegavanje uzimanja hrane Oniscus assellusa kao pokazatelj kakvoće hrane

This paper describes a study of behavioural response in terrestrial isopod Oniscus asellus when offered two food pellets of different quality. One group had a choice of sterilised food and food pellets covered with mould. The other group had a choice of uncontaminated and cadmium-dosed food. During the behavioural test, the animals were monitored by a video camera and each visit to food pellets and time spent around it was counted. The results show that animals spent significantly less time near sterilised and cadmium-dosed food than with uncontaminated or mould-covered food. Discrimination between offered food pellets showed that avoidance behaviour can be used as an indicator of different food quality.Autori su istraživali ponašanje Oniscus asellusa (Crustacea, Izopoda) pri uzimanju različitih pripravaka hrane, a sa svrhom da se utvrdi mogućnost primjene ovakvih testova u vrednovanju kakvoće hrane. Ispitivanim pokusnim životinjama, pomno odabranim i razvrstanim u skupine, nuđena je hrana od usitnjenog sušenog lišća lijeske, želatine i hrane za ribe pomiješana s demineraliziranom vodom. Jednoj je skupini životinja nuđen izbor takve hrane kontaminirane plijesnima i jednake, ali sterilizirane hrane, a drugoj skupini jednaka hrana kojoj je dodan samo nitrat (koji je bio i u ispitivanoj hrani skupa s kadmijem) i ona kontaminirana kadmijevim nitratom (200 mg/kg hrane). Pri praćenju ponašanja pokusnih životinja autori su se koristili videokamerom. Utvrdili su da je skupina koja je imala na izbor pljesnivu i steriliziranu hranu preferirala pljesnivu, a druga je skupina očito izbjegavala hranu kojoj je pridodan kadmijev nitrat. Autori smatraju da bi ovakvi pokusi mogli pripomoći utvrđivanju onečišćenja hrane kadmijem

Armadillidium-fajok (Isopoda: Oniscidea) élőhelyi adaptációjának morfológiai háttere

A szárazföldi ászkarákok morfológiai, fiziológiai és viselkedésbeli adaptációik révén sokféle élőhelyen előfordulhatnak: a nedvestől a szárazig, a természetestől a zavartig. Mint talaj felszínén mozgó, röpképtelen, kisméretű gerincteleneknek igen nagy a helyhűségük. Így megjelenésük, túlélésük az élőhely adottságaitól és a fajok tűrőképességétől függ. Ökológiai jellemzőik (tolerancia viszonyaik) alapján fajaikat minősíthetjük, ami az egyes élőhelyek természetességi megítélésében segítségül szolgál. Vizsgálatainkat az Armadillidium nem négy hazai faján (Armadillidium zenckeri, A. nasatum, A. versicolor, A. vulgare) végeztük, melyek a földrajzi elterjedésükben található átfedések ellenére élőhelyi skálán jelentősen eltérnek. Az ászkarákok túlélésének szempontjából kulcsfontosságú a kiszáradás elleni védekezés. Vízháztartásuk szempontjából fontos tényező a kutikulájuk vastagsága, légzőszervük szerkezete. Kutatásunkban ezek különbségét vizsgáltuk a fajok élőhelyeinek változatossága szempontjából. Fénymikroszkópos vizsgálataink igazolták feltételezésünket: a négy faj karaktereik alapján egyértelműen elkülönül és sorrendbe állítható az élőhelygeneralista, szárazságtűrőbb A. vulgare fajtól a specialista, nagy nedvességtartalmat igénylő A. zenckeri fajig

Comparative ultrastructure of cells and cuticle in the anterior chamber and papillate region of Porcellio scaber (Crustacea, Isopoda) hindgut

Isopod hindgut consists of two anatomical and functional parts, the anterior chamber, and the papillate region. This study provides a detailed ultrastructural comparison of epithelial cells in the anterior chamber and the papillate region with focus on cuticle ultrastructure, apical and basal plasma membrane labyrinths, and cell junctions. Na+/K+-ATPase activity in the hindgut epithelial cells was demonstrated by cytochemical localisation. The main difference in cuticle ultrastructure is in the thickness of epicuticle which is almost as thick as the procuticle in the papillate region and only about one sixth of the thickness of procuticle in the anterior chamber. The apical plasma membrane in both hindgut regions forms an apical plasma membrane labyrinth of cytoplasmic strands and extracellular spaces. In the papillate region the membranous infoldings are deeper and the extracellular spaces are wider. The basal plasma membrane is extensively infolded and associated with numerous mitochondria in the papillate region, while it forms relatively scarce basal infoldings in the anterior chamber. The junctional complex in both hindgut regions consists of adherens and septate junctions. Septate junctions are more extensive in the papillate region. Na+/K+-ATPase was located mostly in the apical plasma membranes in both hindgut regions. The ultrastructural features of hindgut cuticle are discussed in comparison to exoskeletal cuticle and to cuticles of other arthropod transporting epithelia from the perspective of their mechanical properties and permeability. The morphology of apical and basal plasma membranes and localisation of Na+/K+-ATPase are compared with other arthropod-transporting epithelia according to different functions of the anterior chamber and the papillate region

Formation of the hindgut cuticular lining during embryonic development of Porcellio scaber (Crustacea, Isopoda)

The hindgut and foregut in terrestrial isopod crustaceans are ectodermal parts of the digestive system and are lined by cuticle, an apical extracellular matrix secreted by epithelial cells. Morphogenesis of the digestive system was reported in previous studies, but differentiation of the gut cuticle was not followed in detail. This study is focused on ultrastructural analyses of hindgut apical matrices and cuticle in selected intramarsupial developmental stages of the terrestrial isopod Porcellio scaber in comparison to adult animals to obtain data on the hindgut cuticular lining differentiation. Our results show that in late embryos of stages 16 and 18 the apical matrix in the hindgut consists of loose material overlaid by a thin intensely ruffled electron dense lamina facing the lumen. The ultrastructural resemblance to the embryonic epidermal matrices described in several arthropods suggests a common principle in chitinous matrix differentiation. The hindgut matrix in the prehatching embryo of stage 19 shows characteristics of the hindgut cuticle, specifically alignment to the apical epithelial surface and a prominent electron dense layer of epicuticle. In the preceding embryonic stage – stage 18 – an electron dense lamina, closely apposed to the apical cell membrane, is evident and is considered as the first epicuticle formation. In marsupial mancae the advanced features of the hindgut cuticle and epithelium are evident: a more prominent epicuticular layer, formation of cuticular spines and an extensive apical labyrinth. In comparison to the hindgut cuticle of adults, the hindgut cuticle of marsupial manca and in particular the electron dense epicuticular layer are much thinner and the difference between cuticle architecture in the anterior chamber and in the papillate region is not yet distinguishable. Differences from the hindgut cuticle in adults imply not fully developed structure and function of the hindgut cuticle in marsupial manca, possibly related also to different environments, as mancae develop in marsupial fluid. Bacteria, evenly distributed within the homogenous electron dense material in the hindgut lumen, were observed only in one specimen of early marsupial manca. The morphological features of gut cuticle renewal are evident in the late marsupial mancae, and are similar to those observed in the exoskeleton