Metabolism of Na2 75SeO4 in Astragalus bisulcatus Lima Bean, and Wheat: a Comparative Study

A comparative study of the metabolism of Na₂ ⁷⁵SeO₄ in Astragalusbisulcatus, luma bean, and wheat has been carried out. The resultsindicate that all three plants metabolize selenium extensively.Important differences were observed in the distribution of radioactivitybetween the various fractions isolated from the plants. Comparedto the protein fraction, the free amino acid fraction from A.bisulcatus contained a higher percentage of radioactivity. Theconverse was true for wheat and lima bean. As A. bisulcatusproteins contained a significant percentage of radioactivity,it is suggested, that the differences in the toxicity of seleniumtowards wheat, lime bean, and A. bisulcatus are difficult toexplain in terms of the differences in its incorporation intothe protein of the three species.     

A Review of the Biology and Ecology of the Quagga Mussel (Dreissena bugensis), a Second Species of Freshwater Dreissenid Introduced to North America

SYNOPSIS. North America's Great Lakes have recently been invadedby two genetically and morphologically distinct species of Dreissena.The zebra mussel (Dreissena polymorpha) became established inLake St. Clair of the Laurentian Great Lakes in 1986 and spreadthroughout eastern North America. The second dreissenid, termedthe quagga mussel, has been identified as Dreissena bugensisAndrusov, 1897. The quagga occurs in the Dnieper River drainageof Ukraine and now in the lower Great Lakes of North America.In the Dnieper River, populations of D. polymorpha have beenlargely replaced by D. bugensis; anecdotal evidence indicatesthat similar trends may be occurring in the lower LaurentianGreat Lakes. Dreissena bugensis occurs as deep as 130 m in theGreat Lakes, but in Ukraine is known from only 0–28 m.Dreissena bugensis is more abundant than D. polymorpha in deeperwaters in Dneiper River reservoirs. The conclusion that NorthAmerican quagga mussels have a lower thermal maximum than zebramussels is not supported by observations made of populationsin Ukraine. In the Dnieper River drainage, quagga mussels areless tolerant of salinity than zebra mussels, yet both dreissenidshave acclimated to salinities higher than North American populations;eventual colonization into estuarine and coastal areas of NorthAmerica cannot be ignored.