Morphogenesis and cell wall changes in maize shoots under simulated microgravity conditions.

Various plant organs show a spontaneous curvature on a three-dimensional clinostat. Changes in the cell wall metabolism underlying the curvature were examined in maize shoots. In coleoptile nodes, no differences were detected in either the level or the composition of cell wall polysaccharides between the convex and the concave halves. However, the convex side showed a higher activity of (1 --> 3),(l --> 4)-beta-glucan breakdown, which appears to be associated with the curvature. In the elongating region of coleoptiles, the accumulation of wall polysaccharides occurred in the convex side. There was no significant difference in the glucanase activity between both sides. Thus, the spontaneous curvature in different regions of maize shoots may be brought about through different mechanisms under simulated microgravity conditions.     

Studies on subfractions of hemoglobin A1b and hemoglobin A1c in diabetic subjects

Hemoglobin (Hb) obtained from the hemolysate of normal subjects and diabetic patients was separated into HbA1a1, HbA1a2, HbA1b, HbA1c and HbA0 (major Hb) by Bio-Rex 70 cation exchange column chromatography. The glycosylated Hbs were further separated reproductively by cation exchange high performance liquid chromatography (HPLC), using 50 mM sodium phosphate buffer pH 5.80 with 0-0.2 M NaCl linear gradient system. HbA1b and HbA1c were separated into two subfractions (HbA1b1 and HbA1b2) and three subfractions (HbA1c1, HbA1c2, HbA1c3), respectively. The percentages of each subfraction except HbA1c1 in diabetic patients were significantly higher than those in normal subjects. Furthermore, HbA1c1, HbA1c2 and HbA1c3 correlated well with fasting blood glucose levels in the prior 5 month period, while subfractions in HbA1b revealed no significant correlation with blood glucose levels. The percentages of each subfraction of HbA1c in patients either with diabetic cataracts or with diabetic neuropathy were almost the same as those in the patients without complications. However, the percentages of each of the three groups were markedly higher than those of the normal subjects. These results suggest that glycosylation of hemoglobin in diabetic patients may be increased in various sites of the molecule in parallel with the blood glucose levels during the preceding 4-5 months.     

Inhibitory effects of active vitamin D preparations on PTH secretion in rats

To study the effects of various vitamin D preparations on PTH secretion, serum calcium and urinary excretion of cAMP were monitored in conscious perfused rats, and the influences of a bolus iv injection of the preparations on these parameters were examined. Three hours after the administration of 0.25 microgram/kg (0.6 nmol/kg) of 1 alpha, 24(R)-dihydroxycholecalciferol [1 alpha, 24(OH)2D3], the urinary excretion of cAMP decreased to a level compatible with that of parathyroidectomized (PTX) rats (50% of initial value; p less than 0.05) with no change in the concentration of serum calcium (total and ionized). In PTX rats supplemented with bovine PTH (1 U/h), the vitamin D preparation showed no significant effects either on the urinary excretion of cAMP or on serum calcium. These effects were rather specific for active vitamin D preparations, i.e. 1 alpha, 25(OH)2D3 (0.25 micrograms/kg) and 1 alpha OHD3 (1.25-6.25 micrograms/kg). However, 24,25(OH)2D3 (up to 25 micrograms/kg) had no significant effect on these parameters. These results suggest that, in rats, active vitamin D preparations specifically inhibit PTH secretion without causing a significant increase in the serum calcium concentration, reflecting a direct feedback mechanism between active vitamin D metabolite and the parathyroid glands.     

Regulation of cyclic AMP levels in canine thyroid slices by alpha-adrenergic action.

In an attempt to clarify the role of adrenergic receptors in metabolic responses, interaction of norepinephrine with TSH was studied in canine thyroid slices with regard to cyclic AMP levels. Norepinephrine caused a very rapid (within 1 min), but quite transient increase in cyclic AMP levels. The elevation of cyclic AMP levels induced by TSH was markedly inhibited by norepinephrine. Phentolamine, an α-adrenergic blocker, not only prevented the decline of cyclic AMP levels that followed the rise by norepinephrine, but also abolished the norepinephrine effect on the TSH-induced elevation of cyclic AMP levels. Propranolol, a β-adrenergic blocker, exhibited no such effects. These results indicate that the α-adrenergic receptors control cyclic AMP levels in the thyroid gland.     

Oligo-glycine synthesis in an aqueous solution of glycine under oxidative conditions

Di-and tri-glycine were synthesized in 1M aqueous solution of glycine by bubbling for 90 hr with oxygen discharged in the path from an oxygen cylinder. The peptides were also produced by an incubation at 37°C of 2M glycine solution prepared with 75% hydrogen peroxide, and the yields were traced for 200 days. The final yields were about 0.25% and 0.01% for di-and tri-glycine, respectively. The solution at 166 days of incubation was applied to a Sephadex G 10 column, and the fractions around the top of the chromatogram were found to increase the intensity of ninhydrin color about 45 times after hydrolysis, indicating an existence of oligo-glycine. The solutions of 1M glycine and 0.5M diglycine prepared with 30% hydrogen peroxide were incubated at 37°C for 38 days, and di-and tetra-glycine were detected in the yields of 0.12% and 0.33%, respectively.     

Transformation-defective mutants of Rous sarcoma virus with longer sizes of genome RNA and their highly frequent occurrences.

Transformation-defective (td) mutants with different sizes of genomic RNA were isolated from the Prague strain of Rous sarcoma virus, subgroup C(PR-C). All six td viruses (tdTYPR-C) isolated from a single UV-irradiated stock of PR-C (clone 2 of TYPR-C) had slightly longer RNA than did the ordinary class b RNA of tdB77 and Rous-associated virus-7. td viruses spontaneously segregated in uncloned TYPR-C also contained genomic RNA of a size similar to tdTYPR-C RNA. On the other hand, two td mutants isolated from another stock of PR-C (LAPR-C) had the class b RNA. Fingerprint analysis confirmed that tdTYPR-C and tdLAPR-C were derived by deletion from clone 2 of TYPR-C and LAPR-C, respectively, and also showed that clone 2 of TYPR-C had sequences in its genome RNA different from those of LAPR-C, although it gave a fingerprinting pattern similar to the latter. These results strongly suggest that differences between the nucleotide sequences in TYPR-C and LAPR-C RNA may result in different extents of deletion.     

Urinary oligosaccharides of fucosidosis. Evidence of the occurrence of X-antigenic determinant in serum-type sugar chains of glycoproteins.

Urine of a fucosidosis patient contained a large amount of fucosyl oligosaccharides and fucose-rich glycopeptides. Six major oligosaccharides were purified by a combination of Bio-Gel P-2 and P-4 column chromatographies and paper chromatography. Structural studies by sequential exoglycosidase digestion and by methylation analysis revealed that their structures were as follows: Fucalpha1 leads to 6GlcNAc, Fucalpha1 leads to 2Galbeta1 leads to 4(Fucalpha1 leads to 3)GlcNAcbeta1 leads to 2Manalpha1 leads to 3Manbeta1 leads to 4GlcNAc, Galbeta1 leads to 4(Fucalpha1 leads to 3)GlcNAcbeta1 leads to 4Manalpha1 leads to 4GlcNAc, Galbeta1 leads to 4(Fucalpha1 leads to3)GlcNAcbeta1 leads to 2Manalpha1 leads to 6Manbeta1 leads to 4GlcNAc, and Galbeta1 leads to 4(Fucalpha1 leads to 3)GlcNAcbeta1 leads to 4Manalpha1 leads to 6Manalpha1 leads to 6Manbeta1 leads to 4GlcNAc. In additon, the structure of a minor decasaccharide was found to be Galbeta1 leads to (Fucalpha1 leads to)GlcNAcbeta1 leads to Manalpha1 leads to [Galbeta1 leads to (Fucalpha1 leads to)GlcNAcbeta1 leads to Manalpha1 leads to]Manbeta1 leads to 4GlcNAc.     

Flash reactivation of Tris-inactivated chloroplasts

The light conditions required for reactivation of the oxygen-evolvingsystem in Tris-treated chloroplasts were studied by means ofrepetitive flashes. Inactive Tristreated chloroplasts were washedwith reduced 2,6-dichlorophenolindophenol, suspended in a reactivationmedium containing Mn²⁺⁺ and Ca²⁺⁺ ions, then illuminated withflashes. Flashes at dark intervals of 2 sec were most effectivefor reactivation, while those at shorter or longer intervalswere less effective. It was deduced that more than two sequentiallight reactions with dark reactions in between were involvedin the reactivation. (Received December 28, 1977; )