Proline Oxidase and Water Stress-induced Proline Accumulation in Spinach Leaves

Spinach (Spinacia oleracea L.) leaf discs accumulated free proline when exposed to polyethylene glycol solutions of water potential less than −10 bars. At −20 bars, the accumulation was 11 micromoles per gram original fresh weight in a 24-hour period.     

The effect of a moving foveal target on the subjective sensation of motion

In this paper, we report on two experiments concerning the effect of the visual field of fovea on the subjective estimation of angular velocity. Experiment 1 investigates the effect of a slow moving target on the perception of self motion. The result of this experiment can be summarized as follows: a slow moving target seen in the visual field of fovea by a stationary person generates in this person a sensation of self rotation in the same direction as the motion of the target. This phenomenon will be called foveal induced ego motion. Experiment 2 investigates the latency for the detection of a self angular acceleration when the person focusses his fovea on a slowly moving target. From the results of this experiment we conclude that the latency for detection of a small self angular acceleration is shorter if the person sees a small foveal target moving with respect to the person in the direction of self rotation than if that small foveal target is moving (with respect to the person) in the opposite direction. The results of these experiments help us in refining existing models of visual-vestibular interaction, by providing a model which accounts for the phenomenon of oculogyral illusion.This research was conducted while serving as a Visiting Professor at the Man Vehicle Laboratory, Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA     

Microwave treatment of intracerebral l1210 leukemia: Schedule-dependent partial reversal of the effects of methotrexate

One-GHz microwave (MW) irradiation at a power density of 5 mW/cm² was combined with methotrexate (MTX) in an attempt to treat more effectively central nervous system (CNS) L1210 leukemia in DBA/2J mice. When mice with CNS leukemia were treated with the combination of MW and MTX, there was no improvement in survival compared with a group of animals treated with MTX alone; however, the group that received MTX before the MW exposure had a significantly reduced survival time compared with the group treated with MTX alone or with the group to which MTX was administered after MW.     

Autoradiographic studies with 3H 1,25 (OH)2 vitamin D3 and 3H 25 (OH) vitamin D3 in rat parathyroid glands

Summary After injection of radiolabeled 1,25 (OH)₂ vitamin D₃, nuclear concentration of radioactivity is observed in parenchymal cells of the parathyroid gland in pregnant, adult male, and 10-day male neonatal rats. In competition studies with unlabeled 1,25 (OH)₂ vitamin D₃, but not with 25 (OH) vitamin D₃, nuclear uptake is prevented. Experiments with ³H 25 (OH) vitamin D₃, in contrast to ³H 1,25 (OH)₂ vitamin D₃, do not show nuclear concentration in cells of the parathyroid. The results of the autoradiographic studies suggest the presence of receptors for a direct effect of 1,25 (OH)₂ vitamin D₃ on the parathyroid gland for modulation of parathyroid hormone secretion.     

Androgen glucuronides: I. Direct formation in rat accessory sex organs

A simple one-step procedure is described on the isolation of androgen glucuronides from various rat tissues. This procedure uses polyacrylamide gel electrophoresis, and permits a quantitative isolation of a single band containing the total androgen glucuronides without the contamination of free androgens and androgen sulfates. This procedure was used to determine the ability of various tissues of the rat to form androgen glucuronides directly when they were incubated with 1,2-[³H]-testosterone (0.1 μM) $\text{in}$$\text{vitro}$. Of eleven organs studied, only the accessory sex organs (ventral prostate, seminal vesicle, and coagulating gland), liver, and kidney were capable of forming androgen glucuronides. At the end of a one-hour incubation period, approximately 1% of the total radiolabeled steroids in the prostatic tissue minces were in the form of glucuronide conjugates. The predominant androgen glucuronide formed in the accessory sex organs was 5α-androstane-3α,17β-diol 17β-d-glucuronide. This is in contrast to the rat liver and kidney in which testosterone glucuronide was the predominant conjugate.A similar amount of labeled glucuronide conjugates was formed from either [³H]-testosterone, [³H]-dihydrotestosterone or [³H]-androstenedione, whereas negligible amount of steroid conjugates was formed from [³H]-cortisol. The formation of androgen glucuronides requires metabolically active tissues; furthermore, the conjugation process was inhibited by the antiandrogen, cyproterone acetate, or by metabolic inhibitors, such as oligomycin or N-ethylmaleimide.     

Concerning the biosynthesis of prostaglandin I2

Two diastereoisomers, 5R,6R-5-hydroxy-6(9α)-oxido-11α,15S-dihydroxyprost-13-enoic acid (7) and 5S,6S-5-hydroxy-6(9α)-oxido-11α,15S-dihydroxyprost-13-enoic acid (10) were synthesized for evaluation as possible biosynthetic intermediates in the enzymatic transformation of PGH₂ or PGG₂ into PGI₂. The synthetic sequence entails the stereospecific reduction of the 9-keto function in PGE₂ methyl ester after protecting the C-11 and C-15 hydroxyls as tbutyldimethylsilyl ethers. The resulting PGF_2α derivative was epoxidized exclusively at the C-5 (6) double bond to yield a mixture of epoxides, which underwent facile rearrangement with SiO₂ to yield the 5S,6S and 5R,6R-5-hydroxy-6(9α)-oxido cyclic ethers. It was found that dog aortic microsomes were unable to transform radioactive 9β-5S,6S[³H] or 9β-5R,6R[³H]-5-hydroxy-6(9α)-oxido cyclic ethers into PGI₂. Also, when either diastereoisomer was included in the incubation mixture, neither isomer diluted the conversion of [1-¹⁴C]arachidonic acid into [1-¹⁴C]PGI₂.     

Transfer of purified herpes virus thymidine kinase gene to cultured mouse cells.

Treatment of Ltk^?, mouse L cells deficient in thymidine kinase (tk), with Bam I restriction endonuclease cleaved DNA from herpes simplex virus-1 (HSV-1) produced tk⁺ clones with a frequency of 10^?6/2 μg of HSV-1 DNA. Untreated cells or cells treated with Eco RI restriction endonuclease fragments produced no tk+ clones under the same conditions. The thymidine kinase activities of four independently derived clones were characterized by biochemical and serological techniques. By these criteria, the tk activities were found to be identical to HSV-1 tk and different from host wildtype tk. The tk⁺ phenotype was stable over several hundred cell generations, although the rate of reversion to the tk^? phenotype, as judged by cloning efficiency in the presence of bromodeoxyuridine, was high (1–5 × 10^?3). HSV-1 DNA Bam restriction fragments were separated by gel electrophoresis, and virtually all activity, as assayed by transfection, was found to reside in a 3.4 kb fragment. Transformation efficiency with the isolated fragment is 20 fold higher per gene equivalent than with the unfractionated total Bam digest. These results prove the usefulness of transfection assays as a means for the bioassay and isolation of restriction fragments carrying specific genetic information. Cells expressing HSV-1 tk may also provide a useful model system for the detailed analysis of eucaryotic and viral gene regulation.     

Transport of 5-hydroxytryptamine by dense granules from porcine platelets

A method is described for the isolation of a homogeneous preparation of dense granules from procine platelets. The purified dense granule fraction contained approximately 400 nmol of 5-hydroxytryptamine/mg of protein and appeared to be homogeneous when examined by electron microscopy. Isolated dense granules transport exogenously added 5-hydroxytryptamine via two mechanisms: 1) a carrier-mediated process predominating at low substrate concentrations and 2) a diffusion-controlled process predominating at high substrate concentrations. Temperature studies revealed an apparent energy of activation of 14.9 kcal/mol for the carrier-mediated transport. Kinetic data yielded a Km of 3.3 micron and a Vmax of 0.79 nmol/min/mg of protein for the mediated transport process. Steady state uptake was sensitive to changes in medium osmotic pressure and a decline in uptake below 300 mosM was correlated with release of endogenous 5-hydroxytryptamine. The transport was inhibited by a number of structural analogs of 5-hydroxytryptamine. These results demonstrate the existence of a carrier-mediated transport system for 5-hydroxytryptamine in the membranes of the platelet dense granules.     

Aminopeptidase and lysozyme activity levels and serum protein concentrations in Biomphalaria glabrata (Mollusca) challenged with bacteria.

The total serum protein concentrations and levels of aminopeptidase and lysozyme activities in the sera of the gastropod Biomphalaria glabrata have been determined. The groups of snails from which hemolymph samples were taken for study included (1) untampered controls, (2) sham-injected snails, (3) heat-killed Bacillus megaterium-injected, and (4) live B. megaterium-injected ones. Our results indicate that there are significant elevations in the levels of aminopeptidase activity in 2 hr in the sera of snails that had been sham-, dead bacteria-, and liver bacteria-injected. The levels of lysozyme activity were not altered in sham-, dead bacteria-, and live bacteria-injected snails. This is contrary to an earlier finding (T. C. Cheng, M. J. Chorney, and T. P. Yoshino, 1977. J. Invertebr. Pathol., 29, 170–174), and the difference is believed to be due to the age of the snails employed. Comparisons of total serum proteins have revealed that the concentration in snails injected with live B. megaterium is significantly higher than in sham-injected ones. This may be due to increase of some yet undetermined serum protein fraction.