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D L Clayton

Publications and source records attributed to D L Clayton.

4 recordsLinked to original sources
PubMed1978

Comparison of determined and undetermined meristems of Selaginella willdenovii Baker.

Three types of meristems from Selaginella willdenovii were compared. Undetermined dorsal branch junction meristems were aseptically cultured for 0, 1, 3, 5, and 7 days on Knop's medium prior to fixation. Root tips and shoot tips, which have meristems already determiend developmentally, were excised from intact plants and fixed immediately. The cellular ultrastructure of each meristem was studied showing some differences in chloroplast structure, microtubule deposition, vesicle formation, degree of vacuolation, and invaginations of the plasma membrane. Some of these features, such as microtubule deposition and vesicle formation and vacuolation could be attributed to the different developmental states of the meristems.

Cell Membrane↗
PubMed1972

Selection for circadian eclosion time in Drosophila melanogaster.

Early and late eclosion strains were developed from Drosophila melanogaster cultures. The Oregon-R parent strains (isolated in 1925) showed significantly more selectability than the W(2) parent strain collected at the beginning of this study (1971). This is consistent with the hypothesis that the selective advantage of circadian behaviors is reduced in laboratory conditions.

Circadian Rhythm↗
PubMedDate not supplied

Circadian modification of drug-induced teratogenesis in rat fetuses.

Pregnant Sprague-Dawley rats were injected with hydroxyurea (750 mg/kg) or physiological saline on the 12th day of gestation. Hydroxyurea and saline (control) treated groups were each composed of six subgroups injected at consecutive 4-h intervals (i.e., group 1 at 00(00), group 2 at 04(00),...). All females were injected at the same circadian phase as they were mated. The developmental age of all fetuses was 288 +/- 2 hrs at the time of injection. The fetuses were taken by caesarean section on the 20th or 21st day of gestation. Teratogenesis was greatest when hydroxyurea was administered in the light phase (light-dark 12:12 cycle). Deformity rates correlate with motor activity, mitotic rates and DNA synthesis.

Abnormalities, Drug-Induced↗