Characterization of gibberellins from dark-grown Phaseolus coccineus seedlings by gas-liquid chromatography and combined gas chromatography-mass spectrometry

Summary An extract from 6000 dark-grown Phaseolus coccineus seedlings was purified by countercurrent distribution and G-10 Sephadex followed by gradient elution from a silicic acid partition column with increasing amounts of ethyl actetate in n-hexane. 25 fractions were collected and tested with the barley-aleurone, Tan-ginbozu dwarf-rice, lettuce, cucumber, dwarf-pea, d-1, d-2, d-3 and d-5 maize, oat first-internode, and sugarcane-spindle bioassays. Major gibberellin (GA)-like activity was detected in fractions 4 (500g GA₃-equivalents) and 12–13 (270 g GA₃-equivalents) with smaller amounts in fractions 6, 8–9, 15–16, 18, 20, 23 and 25. The extracts were also applied to AMO-1618=dwarfed Ph.-coccineus seedlings. Fractions 4, 8 and 12 promoted the growth of both light- and dark-grown seedlings. GA₁, GA₃, GA₄ and GA₈ were active in the Phaseolus bioassay but GA₈-glucoside was inactive.The biological and chromatographic properties of fractions 4, 8–9 and 12–13 correspond with those of GA₄, GA₁₉ and GA₁. The identity of GA₄ in fraction 4 was conclusively established by combined gas chromatography-mass spectrometry (GC-MS) of the methyl ester and the trimethylsilyl ether of the methyl ester. Gasliquid-chromatography peaks corresponding to these derivatives of GA₁₉ and GA₁ were detected on QF-1 and SE-33 columns but their intensities were too weak to permit conclusive identification by GC-MS.Supported by an S.R.C. StudentshipSupported by a NATO Grant.Supported by NRC Grant A-5727.     

A model for studying the initiation of normal calcification in vivo

1. Rat costal cartilage was found to begin to calcify normally when the rats weigh 35-45g. 2. The cartilage is suggested as a model for the study in vivo of mechanisms concerned with normal calcification. 3. The model was tested by studying the incorporation of fluoride into the mineral deposited in the tissue. 4. The percentage of inorganic material in cartilage rose from approx. 3% of the dry weight in the uncalcified tissue to 62% in the tissue from rats weighing 300g. 5. Mineral deposited had a calcium/phosphorus molar ratio of 1.65. 6. After the oral administration of sodium fluoride to rats, fluoride was incorporated into cartilage mineral. 7. The concentration of fluoride in cartilage ash increased rapidly with calcification and the mineral became more highly fluoridated than the corresponding rib bone. 8. Fluoridated mineral showed a marked decrease in citrate concentration.     

Comparison of the protein-synthesizing machinery in the skeletal muscle of normal and dystrophic Bar Harbor mice

1. Although the total weight of leg muscle increased with the age of a normal mouse the DNA and RNA content per leg did not change significantly. 2. The weight of leg muscle from a dystrophic mouse was only about 45% of that from a normal mouse but the DNA and RNA contents were the same and hence similar DNA/RNA ratios were obtained. 3. The total ribosome contents of normal and dystrophic mice were the same on a whole-leg basis, and for both the free ribosomes were about 60% of the total. However, comparison with similar data from liver suggested that some loss of ribosomes occurred during the isolation procedure. 4. The polyribosome patterns obtained by density-gradient centrifugation were the same for normal and dystrophic muscle, and comparable polyribosome fractions of different sizes obtained from such gradients had similar capacities for the incorporation of radioactive amino acids in a standard protein-synthesizing system. 5. By using a standard protein-synthesizing system with normal polyribosomes similar extents of incorporation were found with normal- or dystrophic-muscle pH5 fraction or partially purified transfer RNA preparation. 6. It is concluded that there is no absolute difference between the protein-synthesizing systems of normal and dystrophic mouse muscle and that the observed apparent differences result from concentration differences caused by changes in muscle volume. 7. A possible cause of the failure of dystrophic muscle to resynthesize myofibrils is also suggested.     

Persistence of Salmonella typhimurium on Fabrics

The objective of this study was to determine the feasibility of using airborne T3 coliphage as a viral tracer in microbial aerosols. Although T3 coliphage was relatively stable when stored either at temperatures ranging from 21 to 37 C or in the frozen state at -20 C, there was a 2-log loss in infectivity when stored for 72 days at 4 C. Either agitation of stored coliphage suspensions held at 31 C or wide fluctuations in storage temperature produced an increased loss of infectivity. In the airborne state, freshly prepared coliphage and stored coliphage behaved similarly, with survival diminishing as the relative humidity (RH) was lowered. The greatest loss occurred during the first five min following aerosolization. The results showed that only under certain conditions of temperature and relative humidity can T3 coliphage be used as a satisfactory aerosol tracer.     

An Analytical Model of the Counter-Current Heat Exchange Phenomena

An analytical model for the counter-current heat exchange mechanism in animals has been formulated and a solution has been obtained. The nondimensional parameters that govern the mechanism have been determined in terms of the properties of the animal. The normalized temperatures are functions of normalized distance and, in general, three nondimensional heat transfer conductances. Graphical results are presented for two representative physiological systems. These results allow a delineation of those situations in which counter-current heat transfer is important, and also a quantitative prediction of the heat transfer and temperature distributions. The theory is compared to the available experimental results.     

Floral Inhibition of Biloxi Soybean During a 72-hour Cycle

The inhibitory effect of light interruptions given during the photophobe phases of a 72-hour cycle was studied with Biloxi soybean [Glycine max (L.) Merr.]. The basic 72-hour cycle consisted of 8 hours of light followed by 64 hours of darkness and was repeated 7 times. Supplementary white light treatments given at the twenty-fourth and/or forty-eighth hour of the cycle (photophil phases) promoted the flowering levels of the controls and kept light treatments given at the most inhibitory points from inhibiting flowering completely. Such supplementary light treatments did not affect the time of maximum sensitivity to light interruptions. When 30-minute light breaks were used, maximum inhibition occurred at the 16-, 43-, and 63-hour points. The duration of the light breaks affected the time of maximum inhibition when given during the second photophobe phase. The time of maximum inhibition occurred earlier with 4-hour light breaks than with either 3-minute or 2-hour light interruptions.

Three-minute red light interruptions produced essentially the same effect as 3-minute white light interruptions. Such treatments inhibited flowering completely in the first photophobe phase, inhibited flowering to only a small degree in the second photophobe phase, and inhibited flowering to an intermediate degree in the third photophobe phase. Far-red light interruptions strongly inhibited flowering in the first photophobe phase, especially when given early in the dark period. Three minutes of supplementary white light given at the twenty-fourth or forty-eighth hour of the cycle partially overcame the inhibitory effect of far-red light. Four hours of supplementary white light at these times completely overcame the far-red inhibition.