Glutelin accumulation and changes in the levels of its mRNA in the superior and inferior spikelets of rice ear during ripening

Glutelin accumulation in the apical spikelet of the top primary branch (superior spikelet) and the second spikelet of the lowest secondary branch (inferior spikelet) of the ear of the rice plant (Oryza sativa L.) was characterized during grain filling.In the superior spikelet, the accumulation of dry matter and nitrogen started immediately after flowering and rapidly reached the maturation level by 20 days after heading (DAH). At 7 DAH, total RNA content had already reached its maximum level and glutelin mRNA content 70% of its maximum. The increase in glutelin mRNA was followed by a rapid increase in glutelin between 7 and 16 DAH.In the inferior spikelet dry matter, nitrogen and glutelin accumulation were low immediately after flowering and increased only after grain filling of the superior spikelet was almost complete. Total RNA and glutelin mRNA increased much later at slower rates than in the superior spikelet.It is very likely that the retardation of dry matter, total nitrogen and glutelin accumulation in the inferior spikelet is due to retardation of differentiation and development of endosperm tissue, and to glutelin gene expression in endosperm cells. It is suggested that the delayed development resulted from limited partitioning of nutrients to the inferior spikelet at the early stage of ripening.     

The specific expression of tenascin in the synovial membrane of the temporomandibular joint with internal derangement: An immunohistochemical study

 The expression of tenascin (TN) in the temporomandibular joint (TMJ) disc and synovial membrane was examined in 18 human TMJ samples from patients with internal derangement of the TMJ and ten control specimens by an immunohistological technique using paraffin-embedded tissue and specific anti-human TN monoclonal antibody (RCB-1). The expression of TN was observed in all 28 samples, but it was limited to the walls of blood vessels, the perineurium, and the surface of the TMJ disc. The expression of TN was diffuse in the stroma of mildly hypertrophic synovial membranes and focal in the surface of severely hypertrophic synovial membranes. The clinical symptoms of internal derangement of the TMJ are thought to be related to the degree of synovitis. The present study demonstrates that TN is expressed specifically in the portion of the TMJ synovial membrane affected with internal derangement. Accepted: 17 December 1996     

Seasonal Changes in Activities of Enzymes Responsible for the Formation of C6-aldehydes and C6-alcohols in Tea Leaves, and the Effects of Environmental Temperatures on the Enzyme Activities

When tea leaves were homogenized and incubated, the volatileC₆-compounds hexanal, cis-3-hexenal, cis-3-hexenol and trans-2-hexenalwere formed much more by summer leaves than by winter leavesof tea plants (Camellia sinensis). The enzymes lipolytic acylhydrolase (LAH), lipoxygenase, fatty acid hydroperoxide lyase(HPO lyase) and alcohol dehydrogenase (ADH) and an isomerizationfactor were responsible for the sequential reactions of C₆-compoundformation from linoleic and linolenic acids in tea leaf lipids,and there were seasonal changes in their activities. The tealeaf enzymes were of 3 types: LAH and lipoxygenase, which hadhigh activities in summer leaves and low activities in winterleaves; ADH, which had low activity in summer leaves and highactivity in winter ones; and HPO lyase and the isomerizationfactor, which did not seem to have any effect on the rate ofC₆-compound formation throughout the year. Changes in enzymeactivities were induced by shifts in the environmental air temperaturerather than by the age of the leaves. The combined activitiesof these enzymes determined the amounts and compositions ofthe volatile C₆-compounds formed, which are the factors thatcontrol the quality of the raw leaves processed for green tea. (Received October 6, 1983; Accepted December 20, 1983)     

Relation between Nitrogen and Ribulose-1,5-bisphosphate Carboxylase in Rice Leaves from Emergence through Senescence

The relation between N content and ribulose-l,5-bisphosphate(RuBP) carboxylase protein was examined in the 12th leaf bladeof rice. Plants were grown under different amounts of N afterthe emergence of the 12th leaf blade. RuBP carboxylase proteinincreased with leaf N during leaf expansion. The synthesis ofRuBP carboxylase predominated during this period, and changesin the amounts of carboxylase synthesized until leaf death paralleledchanges in the N influx to the leaves. When the carboxylasereached its maximum content, the proportion of RuBP carboxylaseto leaf N was 27 to 28% irrespective of N treatment. As theleaf senesced, however, this proportion differed significantlywith the treatment. It was higher in the N-deficient leaf thanin the N-sufficient leaf. This was due to different patternsof RuBP carboxylase degradation for the treatments during senescence.RuBP carboxylase was degraded actively during the early stageof senescence in the N-sufficient leaf, whereas its degradationproceeded almost constantly in the N-deficient leaf during senescence. (Received October 17, 1983; Accepted January 27, 1984)     

Participation and Properties of Lipoxygenase and Hydroperoxide Lyase in Volatile C6-Aldehyde Formation from C18-Unsaturated. Fatty Acids in Isolated Tea Chloroplasts

Isolated tea chloroplasts utilized linoleic acid, linolenicacid and their 13-hydroperoxides as substrates for volatileC₆-aldehyde formation. Optimal pH values for oxygen uptake,hydroperoxide lyase and the overall reaction from C₁₈-fattyacids to C₆-aldehydes were 6.3, 7.0 and 6.3, respectively. Methyllinoleate, linoleyl alcohol and -linolenic acid were poor substratesfor the overall reaction, but linoleic and linolenic acids weregood substrates. The 13-hydroperoxides of the above fatty acidsand alcohol also showed substrate specificity similar to thatof fatty acids. Oxygen uptakes (relative V_max) with methyl linoleate,linoleyl alcohol, linolenic acid, -linolenic acid and arachidonicacid were comparable to or higher than that with linoleic acid.In winter leaves, the activity for C₆-aldehyde formation fromC₁₈-fatty acids was raduced to almost zero. This was due tothe reduction in oxygenation. The findings presented here provideevidence for the involvement of lipoxygenase and hydroperoxidelyase in C₆-aldehyde formation in isolated chloroplasts. (Received July 11, 1981; Accepted November 5, 1981)     

Formation of 12-oxo-trans-10-dodecenoic acid in chloroplasts from Thea sinensis leaves

Linolenic acid-[1-¹⁴C] was converted to 12-oxo-trans-10-dodecenoic acid, via 12-oxo-cis-9-dodecenoic acid by incubation with chloroplasts of Thea sinensis leaves. Thus, it was confirmed that linolenic acid is split into a C₁₂-oxo-acid, 12-oxo-trans-10-dodecenoic acid, and a C₆-aldehyde, trans-2-hexenal, leaf aldehyde, by an enzyme system in chloroplasts of tea leaves.     

Changes in the Levels of Chlorophyll and Light-Harvesting Chlorophyll a/b Protein of PS II in Rice Leaves Aged under Different Irradiances from Full Expansion through Senescence

Effects of irradiance on changes in the amounts of chlorophyll(Chl) and light-harvesting chlorophyll a/b protein of PS II(LHCII) were examined in senescing leaves of rice (Oryza sativaL.). Results of treatments at two irradiances (100% and 20%natural sunlight) were examined after the full expansion ofthe 13th leaf throughout the course of senescence. With 20%sunlight, the Chl content decreased only a little during leafsenescence, while with 100% sunlight it decreased appreciably.Similarly, the amount of LHCII protein during treatment with20% sunlight remained almost constant. However, the ratio ofChl a/b during the shade treatment decreased significantly andthe rate of decrease was greater than during the full-sunlighttreatment. The ratio of Chl a/b for Chl a and b bound to LHCIIwas about 1.2, irrespective of leaf age or irradiance treatment.When the amounts of Chl bound to LHCII were calculated fromthe total leaf content of Chl and the ratio of Chl a/b, assuminga ratio of Chl a/b bound to LHCII of 1.2, they were well correlatedwith the amounts of LHCII protein. Changes in the amounts of LHCII synthesized during the two irradiancetreatments were examined using an ¹⁵ tracer. Incorporation of¹⁵N into LHCII declined dramatically during both treatmentsfrom full expansion through senescence, suggesting that therewas little synthesis of LHCII protein during that time. In addition,the amount of LHCII synthesized during senescence was lowerduring the shade treatment than during the 100% sunlight treatment.These results indicate that the absence of an apparent changein levels of LHCII with shade treatment during senescence wascaused by the very low rate of turnover of LHCII protein. (Received June 17, 1992; Accepted September 28, 1992)     

The Remobilization of Nitrogen Related to Leaf Growth and Senescence in Rice Plants (Oryza sativa L.)

Rice plants (Oryzae sativa L.) grown in a nutrient solutionwere fed with (¹⁵NH₄)₂SO₄ during the 5 days of their young panicleformation. At the end of that time in the youngest leaf blade, which hadstarted to emerge during the labelling, absorbed-nitrogen accountedfor 37% of the increased nitrogen of the tissue; in the nextdeveloping leaf blade it accounted for 55%. Thus, remobilized-nitrogenoriginating from older patrs of the plant made up 63 and 45%,respectively, of their total nitrogen. The important contributionof the remobilized-nitrogen to the development of a leaf isevident. The remobilization of nitrogen in the 12th leaf blade on themain stem was examined in detail after labelling during itsdeveloping stage. The ¹⁵N level started to decrease soon afterthe end of the labelling period and continued to decrease untilfull senescence, although the total nitrogen in the same leafincreased until just after its complete expansion, suggestingthat even a young leaf plays a role as a supplier of remobilized-nitrogen. During the rapid decrease in the total nitrogen after its peakat full expansion of the leaf, the actual proportion of labelledabsorbed nitrogen remained nearly the same, indicating thatinflux of new nitrogen into a senescing leaf is very limited. (Received March 13, 1981; Accepted July 13, 1981)     

Genetic studies on site-specific endodeoxyribonucleases in Bacillus subtilis: multiple modification and restriction systems in transformants of Bacillus subtilis 168

Summary We transformed B. subtilis 168 with DNA from B. subtilis IAM1231, IAM1192 and ATCC6633. When we examined the restriction activities of the transformants in vivo and in vitro using phage 105C we found the following: (1) Cells of either IAM1231 or IAM1192 have two modification and restriction systems (Bsu1231(1)-system and Bsu1231(II)-system in IAM1231, and Bsu1192(I)-system and Bsu1192(II)-systems in IAM1192), and cells of ATCC6633 have only one system (Bsu6633-system). (2) The restriction enzymes of all of these five systems are site-specific endonucleases. (3) The nucleotide sequence specificities of the enzymes involved in Bsu1231(I)-system, Bsu1192(I)-system and Bsu6633-system are the same; and those of Bsu1231(II)-system and Bsu1192(II)-system are the same. The sequence specificities of these two groups are different from each other and also different from those of the Bsu168-system of B. subtilis 168, the BsuR-system of B. subtilis R and the Bsu1247(I)-and Bsu1247(II)-systems which are systems of B. subtilis IAM1247. (4) Transformants possessing four different modification and restriction systems (Bsu1231(I)-, Bsu1247(I)-, BsuR- and Bsu168-systems) were constructed. (5) Transformation of two derivatives of 168 that were m _R ⁺ r _R ⁺ by DNA from IAM1231 produced 16 transformants that had the Bsu1231(II) restriction system, but had lost the BsuR system. Transformation of a derivative of 168 that was m _1247(II) ⁺ r _1247(II) ⁺ by DNA from m _1231(II) ⁺ r _1231(II) ⁺ -or m _R ⁺ r _R ⁺ -derivative of 168 produced about 100 each of transformants that had the Bsu1231(II)-restriction system or the BsuR-restriction system. But all these transformants lost the Bsu1247(II)-system.