Transfer of Bisected Cattle Embryos within the Same Zona Pellucida*

Cattle embryos at the compact morula and blastocyst stages were bisected by two different methods. In some embryos the embryo bisection was performed outside of the zona pellucida and both halves were replaced into it. Other embryos were bisected within the zona pellucida and no pipetting of the halves was required. They were transferred to synchronized recipient cows and the pregnancy rates and twinning rates were evaluated.     

Herbicidal activity and selectivity of new 3-alkyl-4-amino-6-aryl-1,2,4-triazin-5-ones

3-Alkyl-4-amino-6-phenyl-1,2,4-triazin-5-ones are herbicidal compounds which act by inhibition of the electron transport in photosynthesis (Hill reaction). There is some correlation between phytotoxicity and photosynthesis inhibition data. An exception is found with sugar beets which are very tolerant towards triazinones with a methyl group in 3-position and an amino group in 4-position. The best compound from this series, 4-amino-4,5-dihydro-3-methyl-6-phenyl-1,2,4-triazin-5-one, metamitron, shows very promising properties as a selective herbicide in sugar beet crops.     

Biology of the European bitterling Rhodeus sericeus (pisces: cyprinidae) in the Bronx River,New York,USA: An apparently benign exotic species

Selected aspects of the biology of the European bitterling Rhodeus sericeus in southern New York were investigated as a preliminary determination of the impact of this species on the native ecosystem. There are about 900 bitterlings in the only extant North American population. The oldest specimen was in its fourth summer (III +) and all were mature in their first year. Fecundity is low, less than 60 eggs per female. Bitterlings feed primarily on diatoms and the digestive system is typical of a surface-scraping herbivore. Impact of this exotic species on the ecosystem appears minimal. It is unlikely that the species would cause appreciable negative impact on any habitat in the northeastern United States.