Life Sciences Commons^™

Electrophoretic Mobilities Of Topoisomers Of Φx174 Dna, Virginia Mckee Hanson

Loma Linda University Electronic Theses, Dissertations & Projects

The analysis of nucleic acid structure by zone electrophoresis in agarose gels has become an increasingly important method in studies requiring the separation and identification of species differing only slightly in molecular weight or conformation. We have demonstrated the existence of several circular DNA forms that appear in cells infected with the bacteriophage ΦX174.

Wt/am3 heteroduplex molecules containing a single base mismatch (relaxed RFI molecules) were constructed in vitro, purified by sedimentation, and analyzed by zone electrophoresis on 1.4% agarose gels. In order to verify that the band of denaturation-resistant heteroduplex was indeed relaxed RFI, we compared …

A Morphometrical Analysis Of The Guinea Pig Placenta After Chronic Exposure To Carbon Monoxide, Marcella J. Woolsey

Loma Linda University Electronic Theses, Dissertations & Projects

We used morphometric analysis to determine if placental structure is modified by carbon monoxide, Camm-Hartley guinea pigs were exposed throughout gestation to chronic conditions of carbon monoxide (averaging about 180 parts per million). Maternal weight, placental weight, fetal weight, and fetal length were recorded at the time of placental fixation. Using a computerized image analyzer on photomicrographs obtained through light microscopy, we measured maternal and fetal percent vessel volumes, surface areas, and vessel numbers. Maternal vessel numbers and surface area remained basically unchanged but decreased slightly. Maternal percent volume decreased 15%. However, fetal capillary number increased 35% (p < 0.01) from a control value of 2325 ± 184 per mm² (SE …

Effect Of Simulated Tidal Patterns On Growth And Growth Line Formation In The Little Neck Clam, Protothaca Staminea, Orlando Irsula

Loma Linda University Electronic Theses, Dissertations & Projects

Growth lines in bivalve mollusks have been thought to reflect solar days, circadian rhythms and/or tides. Tides seem to be the dominating influence in some intertidal species. This study provides laboratory evidence suggesting that tides are a major influence in the number of growth lines in the clam Protothaca staminea.

Clams were grown under 4 different "tidal" regimes, (0, 1, 2 and 3 tides per day) for forty-one days. Acetate peels of shell cross sections were used for growth line counting. Photomicrographs and measurements showed a striking difference in the growth and number of growth lines between the 4 tidal …

Vegetation Responses To Prescribed Burning In A Mixed-Conifer Woodland, Cuyamaca Rancho State Park, California, Bradford D. Martin

Loma Linda University Electronic Theses, Dissertations & Projects

This study reports the results of light intensity prescribed burning on the vegetation of 3 jeffrey pine-black oak woodland sites in Cuyamaca Rancho State Park, California. The 1.2 ha, 85 ha, and 6 ha burn plots were measured for tree and shrub density and basal area 6 months, 1% years, and 2 years following burning for the 3 sites respectively. Each burn site measured was compared against equivalent unburned control plots to help assess the effects of the burning. Density of saplings, seedlings, and herbaceous vegetation was also determined for the woodland understories. Dominance and relative dominance of herbaceous ground …

Palynological Correlation Of The Kentucky No. 12 Coal, Gerald E. Vyhmeister

Loma Linda University Electronic Theses, Dissertations & Projects

In attempting to analyze the depositional environment for the Kentucky No. 12 Coal three columns were sampled from a 1 km area. The columns yielded 76 miospore species belonging to 33 genera, and representing in decreasing order of abundance, arborescent lycopods, tree ferns, calamites, small ferns, gymnospermous trees, seed ferns, herbaceous lycopods, and others from unknown origin.

The pattern of spore distribution in the columns did not appear to be affected by the presence of several partings, a feature which calls into question several mechanisms proposed for the origin of partings and also creates difficulties for an autochthonous origin for …