Correlation of cytokinins and abscisic acid with monocarpic senescence in soybeans

The involvement of cytokinins and abscisic acid (ABA) in themonocarpic senescence (foliar yellowing following fruit development)of soybeans was examined. Foliar sprays of cytokinin (10^–4M zeatin or 10^–5 M benzyladenine), begun when the plantsfirst set fruit and repeated every other day, significantlydelayed, but did not prevent, monocarpic senescence. Foliarsprays of 10^–4 M ABA, applied in the same manner, significantlyhastened senescence of fruiting soybeans but apparently hadno effect on depodded plants. Leaf and stem material from pre-senescentand senescent plants was extracted, chromatographed, and bioassayedfor cytokinin-lilce activity (Amaranthus betacyanin productionassay) and ABA-like activity (oat coleoptile straight growthassay for inhibitors). ABA-like activity increased, and cytokinin-likeactivity decreased in shoot tissue before the plants began tosenesce. Cytokinin-like activity in the fruit also declinedduring this period. These results implicate a decrease in cytokininsand an increase in ABA-like inhibitors in the control of monocarpicsenescence of soybeans, but neither alone is causal. ¹ Supported in part by Research Grant 416-15-79 from the USDACooperative State Research Service under PL 89–106. ² Present address: Biology Dept., College of St. Benedict'sSt. Joseph, Minn. 56374, U.S.A. (Received February 4, 1978; )     

Babysitting behavior by age/sex classification in squirrel monkeys (Saimiri sciureus)

The aunting behavior in a captive group of 22 squirrel monkeys containing three infants was done in terms of the age/sex classification of those animals involved. The time course of the aunting phenomena and the type and intensity of the interactions between the mothers and the aunts were recorded. Males as well as females were observed to ascertain if the babysitters were sex specific. Observations were gathered before, during, and after a particular threat to any monkey who was carrying an infant. Three categories of protective behavior (protect, retreat, and nothing) were tabulated. The results indicated that most aunting and protection occurred between infant ages 2-1/2-5 weeks when the infants were growing rapidly but not as yet socially self-sufficient. Mothers protected infants the most against juveniles, then subadult males, and least against other adult females. Subadult males were occasionally observed to carry and protect older infants. Aunting behavior was discussed in terms of the selective pressures by which it may have evolved.     

Steroid estrogen conjugates in hens' urine II. identifications of some minor conversion products of intramuscularly injected [4-14c]estrone

[4-¹⁴C]Estrone was injected intramuscularly into two mature laying Rhode Island Red hens. Radioactive steroids and steroid conjugates recovered from the urine on Amberlite XAD-2 columns were fractionated on columns (100 cm) of DEAE-Sephadex A-25 by NaCl gradients. The presences of the following were confirmed, the figures in brackets indicating average proportions as per cent of total radioactivity recovered after Sephadex column chromatography: -the 3-β-glucuronides of estrone (10. 9) and of estradiol-17α plus estradiol-17β(9.8); the 17-β-glucuronides of estradiol-17α plus estradiol-17β (2.1); the 3-sulfates of estrone (14. 5) and of estradiol-17α plus estradiol-17β (27. 4); and the disulfates of estradiol-17α plus estradiol-17β (2. 3). The following additional conjugates were identified:-a β-glucuronide of 16-epiestriol (0.2) and a β-glucuronide of 16-ketoestradiol-17β (0. 2); the 3-sulfates of 16-epiestriol (1. 4), of 17-epiestriol (0. 9), of 16, 17-epiestriol (0. 7), of 16-keto-estradiol-17β (1. 1), and of 2-methoxyestrone (0. 7). Some evidence was obtained for the presence of 16, 17-epoxy-estratrienol-3-sulfate (1.9).     

Further studies on non-H-2 histocompatibility alloantibodies in the mouse

Immunofluorescence tests indicate that alloantibodies specific for mouse histocompatibility antigens H-1^a, H-3^a, and H-13^a have been produced, using four different immunizations. Furthermore, an immunization employing donors and recipients which were H-2^k at the MHC produced stronger anti-H-3^a and anti-H-13^a than did immunizations where donors and recipients were H-2^b at the MHC.     

Pyruvate carboxylase from a thermophilic Bacillus. Studies on the specificity of activation by acyl derivatives of coenzyme A and on the properties of catalysis in the absence of activator

1. Oxaloacetate synthesis catalysed by pyruvate carboxylase from a thermophilic Bacillus in the absence of acetyl-CoA required addition of high concentrations of pyruvate, MgATP(2-) and HCO(3) (-), and at 45 degrees C occurred at a maximum rate approx. 20% of that in the presence of a saturating concentration of acetyl-CoA. The apparent K(m) for HCO(3) (-) at pH7.8 was 400mm without acetyl-CoA, and 16mm with a saturating activator concentration. The relationship between reciprocal initial rate and reciprocal MgATP(2-) concentration was non-linear (convex-down) in the absence of acetyl-CoA, but the extent of deviation decreased as the activator concentration was increased. The relationship between reciprocal initial rate and reciprocal pyruvate concentration was non-linear (convex-down) in the presence or absence of acetyl-CoA. 2. The optimum pH for catalysis of oxaloacetate synthesis was similar in the presence or absence of acetyl-CoA. The variation with pH of apparent K(m) for HCO(3) (-) implicated residue(s) with pK(a) 8.6 in catalysis of the activator-independent oxaloacetate synthesis. 3. Linear Arrhenius and van't Hoff plots were observed for the temperature-dependence of oxaloacetate synthesis in the absence of acetyl-CoA over the range 25-55 degrees C. E(a) (activation energy) was 56.3kJ/mol and DeltaH(double dagger) (HCO(3) (-)) (enthalpy of activation) was -38.6kJ/mol. In the presence of acetyl-CoA, biphasic Arrhenius and van't Hoff plots are observed with a change of slope at 30 degrees C in each case. E(a) was 43.7 and 106.3kJ/mol above and below 30 degrees C respectively. 4. Incubation of Bacillus pyruvate carboxylase with trinitrobenzenesulphonate caused specific inactivation of acetyl-CoA-dependent catalytic activity associated with the incorporation of 1.3+/-0.2 trinitrophenyl residues per subunit. Activator-independent catalysis and regulatory inhibition by l-aspartate were unaffected. The rate of inactivation of acetyl-CoA-dependent catalysis by trinitrobenzenesulphonate was specifically decreased by addition of acetyl-CoA and other acetyl-CoA and other acyl-CoA species, but complete protection was not obtained. 5. All alkylacyl derivatives of CoA tested activated Bacillus pyruvate carboxylase; acetyl-CoA was the most effective. The apparent K(a) exhibited a biphasic relationship with acyl-chain length for the straight-chain homologues. Certain long-chain acyl-CoA species showed additional activation at a high concentration. Weak activation occurred on addition of CoA or adenosine 3',5'-bisphosphate, but carboxyacyl-CoA species and derivatives containing a modified phosphoadenosyl group were inhibitory. Thioesters of CoA with non-carboxylic acids, e.g. methanesulphonyl-CoA, serve as activators of the thermophilic Bacillus and Saccharomyces cerevisiae pyruvate carboxylases, but as inhibitors of pyruvate carboxylases obtained from chicken and rat liver. 6. alpha-Oxoglutarate mimics the effect of l-aspartate as a regulatory inhibitor of the pyruvate carboxylases from both the thermophilic Bacillus and Saccharomyces cerevisiae. l-Glutamate was ineffective in both cases.     

Effects of PTH and Ca2+ on renal adenyl cyclase

The effects of calcium ion on the adenylate cyclase system was studied in isolated, renal basal-lateral plasma membranes of the rat. Bovine parathyroid hormone (bPTH) and a guanyl triphosphate analogue, Gpp(NH)p were used to stimulate cyclase activity. Under conditions of maximal stimulation, calcium ions inhibited cyclic adenosine monophosphate (cAMP) formation, the formation rate falling exponentially with the calcium concentration. Fifty percent inhibition of either bPTH- or Gpp(NH)p-stimulated activity was given by approximately 50 μM Ca⁺⁺. Also the Hill coefficient for the inhibition was close to unity in both cases. The concentration of bPTH giving half-maximal stimulation of cAMP formation (1.8 × 10^?8 M) was unchanged by the presence of calcium. These data suggest that calcium acts at some point other than the initial hormone-receptor interaction, presumably decreasing the catalytic efficiency of the enzymic moiety of the membrane complex.     

Critical adjustment of cysteine and glutamine concentrations for improved clonal growth of WI-38 cells

Summary Clonal growth of WI-38 cells with a plating efficiency of 45% has been achieved in a synthetic nutrient mixture (MCDB 102) supplemented with either whole or dialyzed fetal bovine serum. For optimum growth, the concentration of cysteine in the medium must be adjusted precisely. Deviation by a factor of three in either direction from the optimum concentration (9.0×10⁻⁵M) eliminates essentially all clonal growth. A high concentration of glutamine (2.5×10⁻³M) is also needed for, optimum clonal growth. Presented in preliminary form at the 26th Annual Meeting of the Tissue Culture Association, June 4, 1975. This work was supported by Grant No. HD-08181 from the National Institute of Child Health and Human Developement, Grant No. AG-00310 from the National Institute on Aging, and by Contract No. 223-74-1156 from the Bureau of Biologics, Food and Drug Administration.     

Seasonal Changes in the Content of Urotensin II in the Urophysis of the Goby,Gillichthys mirabilis

A seasonal study of urotensin II content of the urophysis of the goby, Gillichthys mirabilis. was conducted from March 1979 to June 1980 in relation to certain internal and environmental changes. Urotensin II content (lowest in November–January) is inversely correlated with female gonadosomatic index and to some extent with rainfall (and hence dilution of the environmental salinity). In addition, there appears to be a direct correlation between UII content and daylength and temperature.