Találati lista | Tudóstér

001-es BibID:	BIBFORM081447
Első szerző:	Rosa Márta Erzsébet
Cím:	Response of green hydra (Hydra viridissima) to variability and directional changes in food availability / Márta E. Rosa, Flóra Bradács, Jácint Tökölyi
Dátum:	2015
ISSN:	0006-3088 1336-9563
Megjegyzések:	Natural environments tend to be variable resulting in alternating periods of high and low food availability. Therefore, animals have to be able to accommodate to sudden environmental changes by adjusting their physiology and behaviour to new conditions. We investigated how simulated food variability affects life history traits (asexual reproduction and stress tolerance) and response to environmental change in laboratory experiments with green hydra (Hydra viridissima). We assigned hydra into four groups differing in feeding frequency (high or low) and food regularity (random or stable). After 21 days of accommodation, feeding frequency was changed (increased or decreased) in half of each group, the other half was kept as a control group. Hydra showed a delayed response to environmental change (increased or decreased feeding frequency). This delay in response was greater under an unpredictable feeding scheme. Animals on a random scheme had lower budding rates and lower stress tolerance. Follow-up experiments suggest that this might be due to receiving food on subsequent days, since we found that animals fed daily have lower budding rates than those fed on alternate days. We hypothesize that frequent feeding might cause high levels of oxidative/xenobiotic stress which could overwhelm the defence system of these animals.
Tárgyszavak:	Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk asexual reproduction environmental variability phenotypic flexibility life history trade-offs stress tolerance
Megjelenés:	Biologia. - 70 : 10 (2015), p. 1366-1375. -
További szerzők:	Bradács Flóra Tökölyi Jácint (1984-) (biológus)
Pályázati támogatás:	SROP-4.2.2.B15/1/KONV-2015-0001 Egyéb
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
Borító:
Saját polcon:

001-es BibID:	BIBFORM066149
035-os BibID:	(Scopus)84952637768 (WoS)000367196900009
Első szerző:	Tökölyi Jácint (biológus)
Cím:	Effects of food availability on asexual reproduction and stress tolerance along the fast-slow life history continuum in freshwater hydra (Cnidaria: Hydrozoa) / Jácint Tökölyi, Flóra Bradács, Nikolett Hóka, Noémi Kozma, Máté Miklós, Orsolya Mucza, Kinga Lénárt, Zsófia Ősz, Flóra Sebestyén, Zoltán Barta
Dátum:	2015
ISSN:	0018-8158
Megjegyzések:	Life history theory predicts that reproduction and somatic maintenance are negatively related, but the strength of this relationship is expected to depend on food availability. In this study, we investigated asexual reproduction (budding rate) and oxidative stress tolerance as two opposing facets of life history trade-offs in 17 strains of five freshwater hydra species under experimentally simulated low, medium, and high food availability. Stress tolerance was quantified by exposing animals to exogenous H2O2, which mimics reactive oxygen species arising in vivo. The five species differed in life history traits (low budding rate and high stress tolerance in Hydra vulgaris and H. circumcincta and the opposite in H. oligactis and H. viridissima; low budding rate combined with relatively low stress tolerance in H. oxycnida). Stress tolerance and asexual reproduction increased with food, but there were clear interspecific differences in this relationship. Across all strains, stress tolerance and budding rate were significantly negatively related on the low and medium, but not the high food level. These results suggest that resource allocation trade-offs are involved in determining life history traits in hydra; populations/species can be broadly positioned on a fast-slow life history continuum, and response to variation in food varies along this continuum.
Tárgyszavak:	Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban Dietary restriction Food variability Hydra Life history evolution Resource allocation trade-offs
Megjelenés:	Hydrobiologia. - 766 : 1 (2015), p. 121-133. -
További szerzők:	Bradács Flóra Hóka Nikolett Kozma Noémi Miklós Máté (1994-) (biológus) Mucza Orsolya Lénárt Kinga (1994-) (biológus) Ősz Zsófia Sebestyén Flóra (1993-) (biológus) Barta Zoltán (1967-) (biológus, zoológus)
Pályázati támogatás:	SROP-4.2.2.B-15/1/KONV-2015-0001 Egyéb
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
Borító:
Saját polcon:

001-es BibID:	BIBFORM054903
Első szerző:	Tökölyi Jácint (biológus)
Cím:	Life history trade-offs and stress tolerance in green hydra (Hydra viridissima Pallas 1766): the importance of nutritional status and perceived population density / Jácint Tökölyi, Márta E. Rosa, Flóra Bradács, Zoltán Barta
Dátum:	2014
ISSN:	0912-3814 1440-1703
Megjegyzések:	Clonally reproducing animals, such as fresh-water hydra, can achieve very quick population growth,potentially resulting in high density when dispersal islimited. The reproductive value of any offspring pro-duced clonally in such a high density population is lowbecause of the strong competition for food. Therefore,animals experiencing such conditions should allocatetheir resources to self-maintenance, to increase survivalchances. Increased allocation to self-maintenance in turnshould enable animals to withstand higher levels ofgenotoxic stress. To test this prediction, we exposedgreen hydra (Hydra viridissimaPallas 1766) to a per-ceived high density (by keeping them in crowded culturemedium) or low density (fresh culture medium) withoutaltering food availability. We also manipulated nutri-tional status (by starving animals for different timeperiods) and previous exposure to mild stress in a fullfactorial experimental design. At the end of the experi-ment we exposed animals to a high concentration ofhydrogen-peroxide and scored stress tolerance. Wefound that stress tolerance is greatly elevated in animalsperceiving high density, confirming our prediction. Stresstolerance decreased in animals starved for a few days,suggesting that the ability to maintain an elevated stresstolerance function has nutritional costs and is possibleonly when resource availability is high. On the otherhand, previous exposure to mild stress had a small effecton the ability to tolerate subsequent exposure to stress,and only in the low density treatment group. Thus, stresstolerance in hydra is dynamically modulated in respons to social, environmental and nutritional cues.
Tárgyszavak:	Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban Asexual reproduction Density depedence Somatic Maintenance Life-history evolution Oxidative stress Élettudományok - Biológiai tudományok
Megjelenés:	Ecological Research. - 29 : 5 (2014), p. 867-876. -
További szerzők:	Rosa Márta Erzsébet Bradács Flóra Barta Zoltán (1967-) (biológus, zoológus)
Pályázati támogatás:	MTA-DE Lendület MTA Viselkedésökológiai Kutatócsoport
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
Borító:
Saját polcon: