Isolation of Cuticle and Vascular Bundles of Leaves by Maceration in Rumen Fluid

We report a new macerating technique for plant leaves which permits the isolation of cuticle and vascular bundles. The maceration medium is rumen fluid, a complex mixture of interacting microorganisms, used full strength or diluted with a nutrient buffer solution in the ratio of 2:5. An incubation period of up to 72 hours at 39 C permits cuticle and vascular-bundle networks to be isolated. The technique is illustrated with fresh leaf samples from pearl millet, Pennisetum typhoides; orchardgrass, Dactylis glomerata; and alfalfa, Medicago sativa.     

Pathogenicity of Salmonella gallinarum After Metabolic Injury by Freezing

Freezing (-75 C) and storage (-20 C) of a cell suspension of Salmonella gallinarum resulted in a heterogeneous population of dead, metabolically injured, and unharmed cells. Injured cells constituted as much as 40% of those surviving freezing and storage for 1 day. Replica plating of frozen and thawed cells indicated metabolic injury was repairable and not a stable mutation. Penicillin was used to increase the ratio of injured to uninjured cells from a frozen and thawed cell suspension. Pathogenicity was evaluated by observing per cent mortality after injecting injured or uninjured cells into separate sets of chicks. Mortality differences between wholly uninjured and predominantly injured populations were small and consistent (5% level) with a hypothesis of no difference.     

The Statistical Mechanics for an Extended Nonlinear Epigenetic Dynamics. I

An extension of the control equations discussed by Goodwin is proposed which allows for arbitrary strong coupling and for arbitrary parallel coupling of metabolic pools and genetic loci. It is demonstrated that these generalized control equations can be put into canonical form and further that Liouville's theorem applies. In addition, it is demonstrated that after a suitable canonical transformation the resulting partition function can be solved in closed form, and this result, as well as that for the mean energy, is exhibited. Some remarks appropriate to additional extensions are presented.     

Observation of calcium uptake by isolated sarcoplasmic reticulum employing a fluorescent chelate probe

The fluorescent chelate probe technique is employed to observe the accumulation and binding of Ca⁺⁺ to isolated sarcoplasmic reticulum from skeletal and cardiac muscle. Chlorotetracycline serves as a fluorescent chelate probe which chelates to membrane bound Ca⁺⁺ giving rise to an intensely fluorescence adduct. An increase in fluorescence of chlorotetracycline is caused by ATP induced Ca⁺⁺ transport in both skeletal and cardiac muscle microsomes. The fluorescence spectra indicate that Ca⁺⁺ lies on the membrane surface in a relatively polar environment.     

Effect of Nalidixic Acid on Semiconservative Replication and Repair Synthesis After Ultraviolet Irradiation in Escherichia coli

Both semiconservative deoxyribonucleic acid replication and "extensive repair" synthesis, after ultraviolet irradiation, appear to be blocked by nalidixic acid. These findings suggest that the agent(s) responsible for both of these modes of replication, or some necessary common process or structure, is affected by this drug.     

Ultraviolet Light-Induced Division Delay in Synchronized Chinese Hamster Cells

The age-dependent, ultraviolet light (UVL) (254 nm)-induced division delay of surviving and nonsurviving Chinese hamster cells was studied. The response was examined after UVL exposures adjusted to yield approximately the same survival levels at different stages of the cell cycle, 60% or 30% survival. Cells irradiated in the middle of S suffered the longest division delay, and cells exposed in mitosis or in G₁ had about the same smaller delay in division. Cells irradiated in G₂, however, were not delayed at either survival level. It was further established, after exposures that yielded about 30% survivors at various stages of the cycle, that surviving cells had shorter delays than nonsurvivors. This difference was not observed for cells in G₂ at the time of exposure; i.e., neither surviving nor nonsurviving G₂ cells were delayed in division. The examination of mitotic index vs. time revealed that most cells reach mitosis, but all of the increase in the number of cells in the population can be accounted for by the increase of the viable cell fraction. These observations suggest strongly that nonsurviving cells, although present during most of the experiment, are stopped at mitosis and do not divide. Cells in mitosis at the time of irradiation complete their division, and in the same length of time as unirradiated controls. Division and mitotic delays after UVL are relatively much larger than after X-ray doses that reduce survival to about the same level.     

Effect of Prehumidification on Sampling of Selected Airborne Viruses

Studies were undertaken to determine if a prewetting device (humidifier bulb) used in combination with an all glass impinger (AGI-30) would increase the recovery of airborne mengovirus-37A, vesicular stomatitis virus (VSV), and the S-13 coliphage. Suspensions of T3 coliphage with mengovirus-37A, VSV, or S-13 were aerosolized and collected by using the AGI-30-humidifier bulb combination to sample the aerosols before and after shifts in relative humidities (RH). These studies revealed the following. (i) At low RH values there was a 3 to 4 log increase in recovery of airborne T3 phage; (ii) concomitantly, the recovery of mengovirus-37A and VSV decreased; and (iii) only at the mid-range RH values was the recovery of S-13 enhanced. The prehumidification technique significantly increased the recovery of airborne T3 phage but decreased the recovery of the two animal viruses tested.