Role of inhibitors in the induction of differentiation in callus cultures of Brassica,Datura and Nicotiana

The effect of various inhibitors on differentiation (shoot morphogenesis) in callus cultures of Brassica, Datura and Nicotiana has been investigated. Hormone medium without any inhibitor (control), resulted in 6% shoot formation. Addition of inhibitors such as actinomycin D, cordycepin, abscisic acid, trigonelline and theophylline greatly enhanced shoot formation. The results suggest that inhibitors play a regulatory role in the control of differentiation.Abbreviations ABA Abscisic acid - BA Benzyl adenine - Kn Kinetin - MS Murashige Skoog's - NAA 1-naphthalene acetic acid     

Inhibition of reverse transcriptase activity of RNA-tumor viruses by fagaronine+.

Fagaronine, a benzophenanthridine alkaloid from roots of $\text{Fagara zanthoxyloides}$ (Rutaceae), has been reported to possess anti-leukemic activity. It inhibited RNA-directed DNA polymerase activity from avian myeloblastosis virus, Rauscher leukemia virus and simian sarcoma virus. With poly rA·oligo dT, the alkaloid concentration for 50% inhibition of the enzyme activity from these viruses was in the range of 6–12 μg (15 – 31 nmoles) per ml of reaction mixture. The enzyme reaction was also inhibited with activated DNA and 70S RNA as templates; however, with poly rC·oligo dG no inhibition of enzyme activity was obtained. These results suggest that fagaronine inhibits enzyme activity by interaction with the A:T templateprimer.     

Parathyroid hormone and calcitonin secretion in man: effect of dopamine agonists and antagonists

This study was undertaken to evaluate the physiological role, if any, of dopamine (DA) in modulating parathyroid hormone (PTH) and calcitonin (CT) secretion in man. Infusion of DA (5 micrograms/kg/min) into 6 normal men, decreased serum immunoreactive prolactin (iPRL) and concomitantly increased serum iPTH to 140 +/- 6.8% of baseline (P less than 0.01) at 30 min, with decline thereafter, despite continuation of the DA infusion. Serum iCT levels did not significantly change. Chlorpromazine (50 mg IM), decreased serum iPTH to 75 +/- 5.4% and 79 +/- 3.7% of baseline (P less than 0.01) at 30 and 60 min, respectively, associated with an increase in iPRL. There was subsequent return of iPTH to baseline even though iPRL remained elevated. iCT levels did not significantly change. These observations would suggest that DA may play a physiological role in iPTH, but not iCT, secretion. However, infusion of more nearly physiological doses of DA (0.02, 0.2, and 2.0 micrograms/kg/min) lowered serum iPRL to levels similar to those after the larger DA dose, but with no concomitant increase in either iPTH or iCT. Also, 1) the DA agonist bromocriptine decreased serum iPRL without modifying iPTH or iCT; 2) the DA precursor, levodopa, and the DA antagonist, metoclopramide, had no effect on serum iPTH or iCT levels. These studies suggest that 1) the transient stimulatory effect of DA on iPTH secretion is pharmacological, and 2) DA does not have a physiological role in secretion of iPTH or iCT in man.     

Role of amino acids, betaine and choline in vitamin B12 biosynthesis by strains of Propionibacterium

This paper reports the role of amino acids, betaine and choline on vitamin B₁₂ biosynthesis in Propionibacterium shermanii 566, P. shermanii and Propionibacterium arl AKU 1251. l-Glutamic acid supplemented at the 0.05% (w/v) level in whey permeate stimulated vitamin B₁₂ production in the three organisms, whereas the influence of other amino acids differed in the three strains. A uniform increase in product formation in Propionibacterium cultures with increasing doses of betaine and choline was recorded, but with variable relative effectiveness. However, no significant difference at the 0.50 and 0.75% (w/v) levels of these two compounds was observed. The addition of betaine at 0.5% (w/v) concentration was considered optimal for maximum fermentation efficiency in the cultures. An increase of 2.8–25.7% and 5.1–40.8% in vitamin B₁₂ yield as compared to the control was observed by supplementing whey permeate medium with l-glutamic acid and betaine, respectively, at their optimum values in the organisms studied.     

Transport of amino acids in gamma-glutamyl transpeptidase-implanted human erythrocytes

gamma-Glutamyl transpeptidase purified from hog kidney cortex was implanted in the human erythrocyte membrane by incubation of erythrocytes at 37 degrees c with gamma-glutamyl transpeptidase-incorporated dipalmitoyl phosphatidylcholine vesicles. Membranes prepared from these implanted cells exhibited 4- to 5-fold increase in gamma-glutamyl transpeptidase activity. The association/insertion of gamma-glutamyl transpeptidase into erythrocyte membrane was further demonstrated by antibody to gamma-glutamyl transpeptidase. Implantation of gamma-glutamyl transpeptidase into erythrocyte membrane led to stimulation of uptake of glutamate and alanine, which are normally transported at a slow rate in human erythrocytes. The uptake of these amino acids in the implanted system was inhibited by inhibitors (serine-borate and azaserine) of transpeptidase activity as well as by antibody to gamma-glutamyl transpeptidase. These results in the implanted human erythrocytes demonstrate that gamma-glutamyl transpeptidase enzyme can mediate the translocation of amino acids and provide further evidence in support of its postulated role in the transport of amino acids in natural membranes.     

Histopathology of Mycotoxicosis produced in Swiss albino mice by metabolites of some fungal isolates.

Of 199 fungal cultures isolated from some of the common cereals collected from different parts of Uttar Pradesh and Madhya Pradesh, 70 produced toxic metabolites. Of the 70 fungi isolated, 59 produced toxins which caused visible lesions in livers, kidneys, and spleens but did not cause mortality. Toxicity, graded in terms of the mortality rate and the extent of lesions in livers, kidneys, and spleens, was found to be highest in various species of Aspergillus (40%), followed by Chaetomium spp. (31%).     

Experimental intestinal histoplasmosis of hamsters

Summary In order to elicit primary intestinal histoplasmosis, hamsters and mice were given the infective agent by drinking a suspension of yeast cells, eating infected mouse liver, and through injection into the wall of the lumen of the cecum after laparotomy.Histologic examination and isolation by cultures were made, maximally 6 weeks after infection.No clear-cut histoplasmic primary complex in the intestine was confirmed, but a fungus disease was achieved in a few animals, suggesting the intestinal tract as a possible portal of entrance of the infection.Some of the animals fed with a fungus suspension developed primary pulmonary lesions, a remarkable fact to be considered in evaluation of feeding experiments.The lack of confirmed evidence of intestinal primary lesions as contrasted with the constant demonstration, when searched for, of pulmonary lesions, would suggest that the intestinal tract should not be considered a major portal of entrance in histoplasmosis.This project was supported in part by Grant 986 from the National Institutes of Health.