CO2 (40, 200, 400 loM) was added to the root systém of 10-d-old pea plants (Pisum sativum L. cv. Ran). The Co2'''-excess caused a reduction in the plant fresh and diy masses and water and chlorophyll contents. The rates of photosynthesis and transpiration decreased, while proline content and stomata resistance increased. The dramatic effect of Co2+-toxicity was expressed both in an inhibition of ribulose 1,5- bisphosphate (RuBP) carboxylase activity and a stimulation of RuBP-oxygenase and phosphoenolpyruvate carboxylase activities on the 4‘h day of cnltivation of plants in a solution of 400 pM C6^*.
A new cucullanid nematode, Dichelyne mexicanus sp. n., is described from the intestine of three species of fishes, Agonostomus monticola (Bancroft) (Mugilidae, Perciformcs) (type host), Ictalurus balsanus (Jordan et Snyder) (Ictaluridac, Siluriformes) and Cichlasoma beani (Jordan) (Cichlidae, Perciformes), from three rivers (la Maquina River, Veracruz; Chontalcoatlán River, Guerrero and Santiago River, Nayaril) in central Mexico. This species is characterised by the absence of a ventral sucker in the male (subgenus Dichelyne) and it differs from its congeners mainly in possessing very unequal and dissimilar spicules (left 0.465-0.768 mm and right 293-548 mm long), an asymmetrical gubernaculum, and two intestinal caeca. Another cucullanid nematode, Cucullanus cabaUeroi Petter, 1977, is reported from Dormitator maculalus (Bloch) (Eleotridae, Perciformes) from the La Palma and La Maquina Rivers and Balzapote stream, Veracruz, being briefly described and illustrated; this represents a new host record. Findings of D. mexicanus and C. cabalteroi represent a new record of cucullanid nematodes from fishes in Mexican fresh waters.