Methylation analysis of extracellular polysaccharides from suspension-cultured cells of Nicotiana tabacum

The soluble extracellular polysaccharides (ECP) of suspension-cultured tobacco cells were fractionated by DEAE-Sephadex CC into seven sub-fractions. Su     

The effect of cotyledons on hypocotyl elongation in light-grown bean seedlings: Comparison between dwarf and tall varieties

Hypocotyl sections with and without the cotyledons were cutfrom bean seedlings and incubated under white light of 6000lux. The cotyledons had an inhibitory effect as well as a promotiveeffect on hypocotyl growth. The former effect was more strikingin the dwarf variety, and the latter in the tall variety. Whenthe hypocotyl units were exposed to light for shorter times(6 hr or less) or incubated under weaker light (1600 and 50lux), the inhibitory effect of the cotyledons decreased greatly,and in the tall variety the presence of cotyledons producedno inhibition, but a promotion of hypocotyl growth. GA treatmentenhanced hypocotyl growth and counteracted the growth inhibitioncaused by the cotyledons. On the whole, the GA effect was moremarked in the tall variety than in the dwarf. The elongation of bean hypocotyls may be controlled by a balancebetween the inhibitory and promotive effects of cotyledons,and the predominance of the former over the latter may be oneof the causes for expressing dwarfing. (Received November 13, 1976; )     

Functional morphology of Gené's organ inHaemaphysalis longicornis (Acari: Ixodidae)

The structure and function of Gené's organ, which secretes the egg wax, were investigated inHaemaphysalis longicornis. The hatching rates of eggs deposited before and after the prevention of the eversion of Gené's organ were compared at the conditions of 30°C, 100% RH and soaking in liquid paraffin. The movement of Gené's organ was observed, and the structures of this organ in unfed and ovipositing females were examined with both light and scanning electron microscopes.The hatching rates of eggs without contact with Gené's organ were markedly lower (4.9%) than that of normal eggs (94.5%) even at the suitable condition for eggs (30°C, 100% RH). In contrast, the hatching rates of eggs soaked in liquid paraffin without contact of Gené's organ were considerably higher (71.8%) than that of eggs without both Gené's organ contact and soaking in liquid paraffin.When oviposition commenced, the camerostome of the female was widened by a downswing of the capitulum, the paired horns of Gené's organ emerged through it, and the oviposited egg from the genital aperture was coated with egg wax. At the same time of retraction of the horns which grip an egg, the capitulum was swung up and the egg was loaded on the scutum.Gené's organ included the outer and inner cuticles, and the outer one is highly folded like bellows when the horns of this organ were retracted into the haemocoel. The undeveloped glands lying in the peripheral region of Gené's organ in the unfed stage commenced their enlargement at the time of the onset of feeding, and they became large tubular glands in the 1-day ovipositing female. The columnar glandular cells of the tubular glands extended their domed apical region into the lumen and contained numerous secretory granules during oviposition.These results suggest that the tubular glands secrete the egg wax which is indispensable for egg survival by serving as a waterproofing agent.     

Solubilization of UDPglucose-ceramide glucosyltransferase from the Golgi apparatus

The choice of a suitable detergent for solubilization of UDPglucose-ceramide glucosyltransferase from Golgi membranes has been investigated. Among the various classes of detergent, CHAPS, a zwitterionic detergent, was used as it produced a substantial activation of the enzyme activity. 30% of the enzyme activity and 50% of proteins were solubilized in the first attempts. Further experiments were conducted with addition of a second detergent, Zwittergent 3-14 which increased enzyme recovery to 45%. Lastly, reducing the concentrations of buffer and divalent cations Mn2+, Mg2+ and introducing glycerol (20%, v/v) allowed 80% of proteins to be solubilized together with 68% of the ceramide glucosyltransferase activity.     

Evidence for the mannosylation of a non-histone protein in monkey liver chromatin

Summary Mannose is incorporated in monkey liver chromatin by the means of a nuclear membrane mannosyl-transferase.¹⁴C-labelled chromatin is dissociated either by sulfuric acid or 6 M urea and 0.4 M GuCl. The fractions then enriched in non-histone¹⁴C-labelled proteins are excluded from Ultro-gel AcA 202, their analysis in SDS-polyacrylamide gel electrophoresis shows that radioactivity fits with one major protein band, confirming the presence of at least a non-histone protein labelled with mannose in monkey liver chromatin, with an apparent molecular weight of 13 000.     

Quantitative analysis of the metabolism in the isolated pupal abdomens of the silkworm, Bombyx mori, infected with nuclear polyhedrosis virus

The rate of oxygen uptake and the amount of several main cell constituents were determined in NPV-infected and uninfected isolated pupal abdomens of the silkworm, Bombyx mori. The oxygen uptake in uninfected isolated abdomens increases for the first 2 days due to the effect of water injection, but thereafter it remains almost unchanged at a relatively low level. When isolated abdomens are infected with an NPV, the oxygen uptake increases markedly from 3 days postinfection onward, being about three times that of uninfected isolated abdomens at late stages of infection. The amounts of cell constituents analyzed in the present study change little in uninfected isolated abdomens throughout the experiment. Infection of NPV leads to a marked accumulation of both DNA and RNA, and a loss of glycogen. The amount of protein, lipid, and sugar are scarcely affected by NPV infection. These results indicate that the activity of metabolism in uninfected isolated abdomens is not only low but also stable, and that infection of NPV results in an activation of host cell metabolism. It is considered that such isolated pupal abdomens provide an excellent opportunity to analyze both the process of NPV replication and the alteration of host cell metabolism resulting from NPV infection.     

Changes in endogenous cytokinin levels in partially synchronized cultured tobacco cells

During the course of partially synchronized cell divisions in cultured tobacco (Xanthi) cells the amount of endogenous cytokinins in the butanol-soluble fraction increased 5 to 10 times in 3 hours and paralleled the increase in frequency of mitosis. Among three cytokinins detected in tobacco cells, the activity corresponding to the R_F of authentic zeatin in thin layer chromatography changed in parallel with the mitotic index.     

Présence des enzymes catalysant la biosynthèse d'UDP glucose dans une fraction légère de l'appareil de Golgi des hépatocytes de chat

A Golgi-rich fraction is prepared from cat hepatocytes by the means of a four-step sucrose density gradient. The material applied to this gradient is composed either of smooth microsomes prepared from healthy animals, or of total microsomes prepared from cat treated by 50 per cent ethanol (0.6 g/100 g body weight, administered by stomach tube).A light fraction (d : 1.10) is obtained by the two procedures. It does not show any glucose-6-phosphatase activity, but is enriched in sialyltransferase, known as a marker enzyme for Golgi apparatus. It also contains the three enzymes implicated in the biosynthetic pathway for UDP-glucose (glucokinase, phosphoglucomutase and UTP : glucose-1-phosphate uridylyltransferase).UDP-glucose being the ultimate substrate in membranous glucosylation reactions, these results could support the hypothesis that sugar-nucleotides necessary for the glycoprotein biosynthesis are produced in the Golgi vesicles directly.     

Formation of hypsorhodopsin in frog retina

Hypsorhodopsin was formed in frog retina by irradiation at liquid helium temperature and converted into bathorhodopsin above about 29 K.