Marine benthic communities in the Upper Devonian of New York

Four distinctive benthic communities occur in the mid-shelf deltaic deposits of the Upper Devonian Sonyea Group: the Bellerophon Community, dominated by herbivorous gastropods and deposit-feeding bivalves; the Prodrtctella Community, dominated by brachiopods with adaptations for life on muddy substrata; the Cypricardella Community, dominated by bivalves and brachiopods with a variety of adaptations; and the Rhipidomella Community, dominated by brachiopods adapted for life on sandy substrata. The geographic and stratigraphic occurrence of the communities suggest that their distribution was controlled by two principal sets of environmental variables: (1) onshore to offshore gradients in salinity, dissolved oxygen concentrations, and sedimentary substrata, and (2) rate of delta progradation. A change in the rate of delta build-out during mid-Sonyea time led to a dramatic change in onshore to offshore community patterns. The change suggests that great care must be used in constructing generalized community models for longer intervals of Paleozoic time.     

Crystallization of Ribulose, 1,5-Bisphosphate Carboxylase of High Specific Activity from Anther-Derived Haploid Plants of Nicotiana tabacum

Haploid plants were generated from anther-culture of Nicotianatabacum cv. Burley Ky 14. Plants that developed from pollenwithout an intervening callus stage were grown to maturity.Ploidy of the anther-derived plants were verified by chromosomecounts in root tip squashes. Crystalline ribulose 1,5-bisphosphatecarboxylase was purified from leaves of mature haploid plantsgrown in a growth chamber. Crystals appeared to be similar tothose from the diploid parental line. The specific activityof the enzyme was higher than those reported earlier in theliterature using similar crystallization procedures in Nicotianatabacum Key words: Nicotiana, haploid, ribulose 1, 5-bisphosphate carboxylase