Seven Gymnura altavela (Linnaeus, 1758) (Elasmobranchii, Myliobatiformes) caught off the Tunisian coast were examined for endoparasites during a three-year period (1995-1998). A phyllobothriid cestode new to science was found in the spiral intestine of all host specimens. The presence of a tetrabothridiate scolex, bothridia lacking an apical sucker, laciniate strobila, and possession of postvaginal testes are sufficient to place this species in the genus Anthobothrium Van Beneden, 1850. In this genus, we consider that only two species, both previously reported from carcharhiniform sharks, are valid: Anthobothrium cornucopia Van Beneden, 1850 and A. laciniatum Linton, 1890. Anthobothrium altavelae sp. n. can be distinguished from its congeners by its length, strobila morphology, and the number of testes. The taxonomic position of the species attributed to Anthobothrium parasitic in gymnurids is discussed.
Anthocyanins and nonphotochemical quenching (NPQ) are two important tools that provide photoprotection in plant leaves. In order to understand how plants use these tools for acclimation to changing seasonal conditions, we investigated pigments, antioxidative capacity, and photosynthesis in leaves of an evergreen tree (Acmena acuminatissima) in two contrasting seasons. Young leaves of A. acuminatissima appeared in distinct colors, being light green in summer and red in winter due to the presence of anthocyanins. In the winter young leaves, anthocyanins contributed less than 2% to the antioxidant pool. In the summer, young leaves had higher NPQ than that of mature leaves, but in the winter, they did not derive any NPQ-related advantage over mature leaves. These results suggest that the accumulation of anthocyanins in young leaves in the winter may compensate for the insufficient photoprotection afforded by NPQ and that anthocyanins function as a light attenuator to protect the photochemical apparatus against excess light., H. Zhu, T.-J. Zhang, J. Zheng, X.-D. Huang, Z.-C. Yu, C.-L. Peng, W. S. Chow., and Obsahuje bibliografické odkazy
From the year 2000, the environmental state and the impact of human activities on fluvial lakes in the central part of the Czech section of the Elbe River is evaluated. For that reason, three oxbow lakes were chosen: Lake Labiště pod Opočínkem (east of Pardubice), Lake Doleháj (near Kolín), and Lake Obříství (near Mělník). All of them are situated within an area with a well-developed chemical industry and the nearby lowlands are one of the most intensively farmed areas of the Czech Republic. In spite of the identical origin during the river canalization, major differences were found. E.g. very low oxygen saturation in Opočínek (mean saturation 46 %) was determined. Nutrient concentrations and their seasonal dynamics (nitrites, nitrates, ammoniated ions, and phosphates) differed in each lake as well. The lowest concentrations of heavy metals (Ag, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn) in sediment were found in the Doleháj. In samples from Obříství after a big flood in September 2002, the Index of Geoaccumulation increased only for Pb and decreased for Hg. This result indicated that the pollution has probably not been occurred during such floods. and Od roku 2000 jsou v oblasti středního Labe hodnoceny přírodní podmínky starých labských ramen a posuzován vliv antropogenní činnosti na ně. Z toho důvodu byly pro výzkum vybrány následující tři slepé opuštěné meandry: Labiště pod Opočínkem (východně od Pardubic), Doleháj (v blízkosti Kolína) a jezero Obříství (v blízkosti Mělníka). Všechna tato fluviální jezera leží v oblasti s velmi rozvinutým chemickým průmyslem, přilehlé nížiny jsou též jedny z nejintenzivněji obdělávaných zemědělských ploch v České republice. Ačkoliv jezera vznikla stejným způsobem při regulacích řeky, byly mezi nimi zjištěny značné rozdíly. Například lokalita Opočínek vykazovala značně nízké hodnoty nasycení vody kyslíkem (průměrné nasycení 46 %). Koncentrace živin a jejich sezónní dynamika (dusitany, dusičnany, amonné ionty a fosforečnany) se též v každém případě lišila. Nejnižší koncentrace těžkých kovů (Ag, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb a Zn) v sedimentu byly zaznamenány v Doleháji. Ve vzorcích z lokality Obříství po velké povodni v roce 2002 se zvýšil geoakumulační index jen v případě Pb, naopak hodnota u Hg poklesla. Výsledky proukázaly nepřítomnost výrazného znečištění po této povodni.