Dennis D. Francis

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When Xenopus eggs and egg extracts replicate DNA, replication origins are positioned randomly with respect to DNA sequence. However, a completely random distribution of origins would generate some unacceptably large interorigin distances. We have investigated the distribution of replication origins in Xenopus sperm nuclei replicating in Xenopus egg extract.(More)
The effects of ascorbate (ASC) and dehydroascorbate (DHA) on cell proliferation were examined in the tobacco Bright Yellow 2 (TBY-2) cell line to test the hypothesis that the ASC-DHA pair is a specific regulator of cell division. The hypothesis was tested by measuring the levels of ASC and DHA or another general redox pair, glutathione (GSH) and glutathione(More)
Pteridophytes are not as well characterized at the molecular and biochemical level as some higher plants. However, to aid conservation efforts (4), there is growing interest in understanding the population biology of many fern species that are under threat. DNAbased studies offer excellent tools for such work, but are hampered in ferns by difficulties in(More)
A plant’s photosynthetic potential is directly proportional to the quantity of chlorophyll present in the leaf Measuring a crop’s physiological parameters provides information tissue. Rapid estimates of photosynthetic potential can for interpreting its response to the environment. Remote sensing is quickly becoming recognized as a valuable tool that has the(More)
Salinity is a major abiotic stress that limits plant productivity. Plants respond to salinity by switching on a coordinated set of physiological and molecular responses that can result in acclimation. Medicago truncatula is an important model legume species, thus understanding salt stress responses and acclimation in this species is of both fundamental and(More)
In plants of Silene coeli-rosa, induced to flower by 7 LD, synchronisation of cell division in 20 per cent or more of the cells in the shoot apical dome was found on the 8th and 9th days after the beginning of induction, during the plastochron before sepal initiation. Synchronisation was inferred from the changes in the proportions of cells with the 2C and(More)
resulting in an estimated 1066 kg ha 1 (17 bu ac 1) yield loss over 354 commercial fields. Lauer and Rankin Corn (Zea mays L.) grain yields are known to vary from plant to (2004) and Liu et al. (2004) had differing results, noting plant, but the extent of this variability across a range of environments has not been evaluated. This study was initiated to(More)
The basic components of the plant cell cycle are G1 (postmitotic interphase), S-phase (DNA synthesis phase), G2 (premitotic interphase) and mitosis/cytokinesis. Proliferating cells are phosphoregulated by cyclin-dependent protein kinases (CDKs). Plant D-type cyclins are sensors of the G0 to G1 transition, and are also important for G2/M. At G1/S, the(More)
Very little is known about the expression patterns in plants of genes that encode proteins involved in the initiation of DNA replication. Partial cDNA sequences that encode Cdc6 and Mcm3 in tobacco have been isolated. The sequences were used as probes in northern blots which suggested that, in the cell cycle of synchronized tobacco BY-2 cells, expression of(More)
Current technologies for measuring plant water status are limited, while recently remote sensing techniques for estimating N status have increased with limited research on the interaction between the two stresses. Because plant water status methods are time-consuming and require numerous observations to characterize a field, managers could benefit from(More)