Changes in Ribonucleic Acid Turnover During Aerobic and Anaerobic Growth in Rhodopseudomonas spheroides

Differences in the rate and extent of degradation of ribonucleic acid (RNA) labeled by a 30-sec pulse in aerobically or anaerobically grown Rhodopseudomonas spheroides have been studied by using rifampin to block RNA synthesis. In anaerobic cultures, unstable RNA is degraded with a half-life of 1.25 to 2.0 min, and about 40% of the pulse-labeled RNA is stable. In aerobic cultures, the half-life of unstable RNA is increased to 2.5 to 4.0 min, and 50% of the RNA is stable. When aerobic cultures are transferred to anaerobic conditions, there is a rapid drop in half-life and in the proportion of stable RNA. When anaerobic cultures are made aerobic, the reverse changes occur after a lag of about 30 min. Addition of puromycin to either aerobic or anaerobic cultures caused the pulse-labeled RNA to be degraded at the same rate and to the same extent as the RNA in an anaerobic control culture. In contrast, addition of chloramphenicol enhanced the difference in RNA half-life and increased the proportion of stable RNA by about 10% in each case. It is concluded that there is a difference in the stability of an RNA component under aerobic and anaerobic conditions.     

Ascorbic Acid Turnover in Developing Chick Embryonic Tissues and its Metabolic Significance

A histochemical investigation on the content of ascorbic acid in chick embryonic tissues was undertaken using an improved technique. The concentration of ascorbic acid was found to be higher in the tissues which are involved in active biosynthetic mechanisms. Although the overall localization of ascorbic acid in intestine and proventriculus was less yet their secretory areas were rich in this vitamin. A significant successive increase in intensity of staining for ascorbic acid in the tissues from 15th to 21st day was evident from the data. The maximum ascorbic acid deposition was found in almost all the tissues of 21st day embryo as compared to the other age groups. This increase is correlated with the hatching process.     

Biochemical Changes in Sorghum Seeds Affected by Accelerated Aging

Examination of the initial rates of enzyme activities in variousseed lots demonstrated that amylase, glutamic-pyruvic-transaminase,RNase, and glutamate decarboxylase follow the vigour profile,namely, an increase after 6 d of aging treatment followed bya decrease up to 48 d of aging time. Acid phosphatase, tetrazoliumreduction, and [¹⁴C]leucine incorporation decline directly withthe time of aging and no increase in those activities at 6 daging could be observed. Proteinase is the only enzyme foundso far that increases during accelerated aging. It is postulatedthat this enzyme may be the cause of the drop in all other enzymeactivities and therefore may play an important role in the lossof seed vigour. Examination of the components released from seeds into water,and of the rates of their leakage, led to the conclusion thatthe efflux reflects severely damaged seeds rather than vigourlessones.     

Ascorbic Acid Turnover in Cotton Boll as Affected by Foliar Application of Sucrose

Excision of main stem leaf subtending the sympodium decreasedascorbic acid turnover in the developing boll (cotton fruit)on the first node of this sympodium in var. Suvin Gossypiumbarbadense L). Ascorbic acid turnover increased substantiallyin seed cotton and carpels of the boll when sucrose was appliedto the source leaf even though the main stem leaf remained excised.The role of ascorbic acid if any in boll growth appeared tobe linked with sucrose transport. Ascorbic acid, sympodial leaf, sucrose, boll     

Chlorophylls and Nitrate Reductase Activity in Relation to Heterosis in Coconut seedlings

The F₁ progeny of Chowghat Dwarf Orange (CDO) and West CoastTall (WCT) cross tend to be highly heterozygous with respectto the colour of petiole and seedling vigour. The study indicatedthat the greenish brown coloured vigorous plants had higherchlorophyll (a + b) content and nitrate reductase (NR) activitycompared to the orange coloured vigorous plants and the dwarfs.The greenish brown seedlings were also characterized by a largerleaf area and shoot d. wt. The results provide biochemical evidencein support of the morphological criteria being used at presentin the selection of hybrid coconut seedlings. Cocos nucifera L. (Coconut), Chowghat Dwarf Orange, West Coast Tall, heterosis, chlorophyll, nitrate reductase, leaf area, shoot dry weight     

晚熟脐橙果实发育过程中抗坏血酸含量及相关酶活性的变化

以‘鲍威尔’脐橙为试材, 研究了果实发育期间果皮和果肉中抗坏血酸（AsA）含量及相关酶活性的变化。结果表明, 果皮中总抗坏血酸（T-AsA）和AsA含量显著高于果肉, 且在发育期间T-AsA和AsA的变化趋势一致; 果皮中L-半乳糖内酯脱氢酶（g·LLDH）活性与T-AsA和AsA积累速率的变化趋势基本一致, 呈显著正相关关系, 而在果肉中的变化趋势却不明显; 在发育过程各阶段中果皮的抗坏血酸氧化酶（AAO）、抗坏血酸过氧化物酶（APX）、脱氢抗坏血酸还原酶（DHAR）和单脱氢抗坏血酸还原酶（MDHAR）活性均高于果肉; 相关性分析显示, 果皮中AsA含量积累主要取决于g·LLDH活性, 而果肉中AsA含量水平可能取决于AsA的再生循环系统。     

Changes in Levels of alpha-Amylase Components in Barley Tissues during Germination and Early Seedling Growth

Kernels of Klages barley (Hordeum vulgare L.) were germinated for 1 to 4 days on moist sand at 18°C. Representative kernels from each time period were dissected to give the following fractions: scutellum, subscutellar endosperm, aleurone-scutellum interface, remaining aleurone, subaleurone endosperm, and core endosperm. These tissues were analyzed for α-amylase components by isoelectric focusing and rocket-line immunoelectrophoresis. Although aleurone and scutellar tissues appeared to synthesize the same α-amylase components, enzyme was detected first in the scutellum. A larger proportion of scutellar α-amylase was excreted into the endosperm compared to aleurone synthesized α-amylase. Aleurone cells appeared to synthesize appreciably more α-amylase than did scutellar tissue.     

Biochemical Changes in Cultures of Nectria galligena during the Autolytic Phase of Growth

Some biochemical changes occurring in cultures of Nectria galligenaduring its autolytic phase of growth have been investigated.In nitrate-grown and autolysed cultures of this fungus the degreeof autolysis amounted to 57 per cent. The amount of myceliallipids decreased continuously with the age of the culture. Totalmycelial nitrogen did not substantially change within the first50 days of autolysis. The constancy in the amount of bound aminoacids released from mycelium of Nectria galligena strongly suggeststhat mycelial protein are not affected by autolysis.     

Respiratory Mechanisms and the Changes of Glutathione and Ascorbic Acid in Germinating Peas

The respiration of pea seeds during the early stages of germinationwas studied by manometric methods. From analyses of the germinatingseeds estimates were obtained of the oxidized and reduced formsof glutathione and ascorbic acid. Thus it was possible to explorethe relationship between these oxidation-reduction systems andthe resumption of respiratory activities in the dormant seed. Several lines of evidence indicate that partial anaerobiosisis an important feature of metabolism during the first phasesof germination in air. The intact testa, acting as a barrierto diffusion, limits the uptake of oxygen by the seed. Splittingof the testa by the development of the embryo leads to rapidchanges in the mechanism and rate of respiration. An increase in the relative proportions of the reduced formsof both glutathione and ascorbic acid is associated with theestablishment of anaerobic conditions in the seed. This andother available evidence indicate that the glutathione-ascorbicacid carrier system plays only a minor part in aerobic oxidationsduring the early stages of germination. The possibility thatglutathione has an important influence on the activation ofenzymes in the first phase of germination is briefly considered.     

烟草茄尼醇含量的品种间差异及其在生长期内的变化

用超声破碎乙醇提取和HPLC分析方法,检测红花烟草品种‘K326’、‘云烟85’、‘NC89’、‘NC82’、‘红花大金元’、‘漂河1号’、‘龙江911’和黄花烟草品种‘蛤蟆头’叶中的茄尼醇含量以及‘云烟85’、‘漂河1号’在不同生长期叶中茄尼醇含量的结果表明:不同烟草品种叶中茄尼醇含量差异显著,以‘红花大金元’烟草的茄尼醇含量为最高。不同生长期的‘云烟85’和‘漂河1号’烟草叶中茄尼醇含量随着烟株苗龄的增加而逐渐上升,66d左右苗龄,即烟株现蕾时的叶中茄尼醇含量达到最大值,此后逐渐下降,并趋于平缓。因此当以新鲜烟叶为茄尼醇生产原料时,烟株现蕾期采收烟叶比较合适。     

Nitrogen Metabolism of Tamarindus indica: Changes in γ-Methyleneglutamine and its Corresponding Acid γ-Methyleneglutamic Acid During Seedling Growth

Changes in γ-methyleneglulamine, a third non-protein amide, γ-methyleneglutamic acid, its corresponding acid, other free aminoacids and amides, and protein and soluble-nitrogen during the seedling growth of tamarind (Tamarindus indica L.), were studied. The changes in the prolein-N content in different parts of the seedling, during growth parallel closely the growth pattern expressed as changes in fresh weight. γ-Meythyleneglutamine is the principal amide during the early stages of seedling growth, but later on when its content starts declining, asparagini’ takes over its function. Thus, γ-methyleneglutamine seems to spare the utilization of amide asparagine, during the early growth period. During later stages of seedling growth, asparagine content also shows a decline, indicating that during this period, asparagine contributes to the protein synthesis and growth. γ-Methyleneglutamic acid was also recorded in large amounts in various parts of the seedling and its concentration was not found to be less than the amide at any stage of seedling growth. The two peaks observed for some of the key aminoacids including γ-methyleneglulamic acid, γ-methylglulamic acid, α-alanine, glutamic acid, aspartic acid, glycine and serine, are interesting, in that the first corresponds to the active growth period of roots and the hypocotyl in the first eleven days, and the second with the active growth of the epicotyl.     

Sorghum Seedling Growth as a Function of Sodium Chloride Salinity and Seed Size

Sodium chloride salinity in the range 0–90 mM inhibitedgrowth of sorghum seedlings. Seedlings derived from small seedswere most sensitive to salinity. Salinity, seed size, seedling growth, sorghum, Sorghum bicolor L. Moench     

Biochemical changes during seed development in sorghum (Sorghum bicolor)

Grain dry weight accumulation, soluble sugars, starch, protein, fat and ash contents were studied in developing grains of eight sorghum cultivars. The     

Biochemical Alterations of Dermatophytes during Growth

Alterations in the biochemical constituents of mycelia were studied during the growth, development, and starvation of Microsporum quinckeanum. On the basis of dry weight, growth of this dermatophyte could be divided into four phases: lag, log, stationary, and death. The percentage of total nitrogen, inorganic phosphorus, ribonucleic acid (RNA), and protein increased rapidly during the lag phase. The percentage of protein remained constant after the initial increase; however, inorganic phosphate and RNA decreased in older mycelia. Acid-soluble materials in the cells increased in concentration as the organism aged. Chitin was present in the spores at a much higher concentration than in the mycelia. The percentage of this compound decreased rapidly until the end of the lag phase. An increase and subsequent decrease in per cent chitin occurred during the log phase. Inorganic phosphorus in the mycelia increased from the value in the spore stage to a maximum in the early log phase, and then decreased rapidly during the remainder of the growth cycle. Compounds involved in protein synthesis increased rapidly during the lag phase of growth. Changes in chemical composition of the mold during starvation indicate that carbohydrate does not form the principal endogenous reserve of M. quinckeanum, whereas lipids may represent the primary reserve material.     

抗坏血酸对植物生长发育的作用及其缺失突变体的研究进展

抗坏血酸（ascorbic acid,AsA）是植物组织内广泛存在的高丰度小分子物质。近年的研究表明它可能通过复杂的信号转导网络来调节植物生长、诱导开花以及延缓衰老。本文介绍了AsA对植物生长发育的作用及其缺失突变体的研究进展,为深入利用AsA缺失突变体来发掘AsA新的生物学功能提供参考。