Changes in Ascorbic Acid Content during Growth and Development of Panicum miliaceum

The present paper deals with changes in the ascorbic acid content of the shoot apex during its transformation from the vegetative to the reproductive state and its further development in Panicum miliaceum var. Samai Co. 1. Seedlings were exposed to 24-hour illumination, natural day, and 8 hours of illumination per day. Ascorbic acid was determined for the growing apex, stem, and leaf of the main shoot and for the individual branches produced on it at successive developmental stages.     

内源抗坏血酸对水稻种子萌发及幼苗生长的影响

为了解内源抗环血酸在水稻(Oryza sativa)种子中的作用,以野生型品种‘中花11’(ZH-11)、抗坏血酸合成关键酶GLDH基因的上调(超表达)株系GO-2及下调(干涉)株系GI-2为材料,研究了抗环血酸含量对其种子萌发和幼苗生长的影响。结果表明,GO-2株系的种子萌发率比野生型ZH-11高6%,比干涉型GI-2高60%。外源添加1 mmol L–1抗坏血酸后,干涉型GI-2萌发率提高了22%,GO-2及ZH-11则没有明显增加。GO-2株系在幼苗的根长、株高、分蘖数和鲜重等指标上均高于ZH-11和GI-2。实时荧光定量测定结果表明,GO-2株系叶片的GLDH基因表达量显著上调,而GI-2株系则显著下调。这说明抗坏血酸有助于维持水稻种子活力和促进水稻种子发芽和幼苗生长。     

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.     

Changes in Enzyme Regulation during Growth of Maize: I. Progressive Desensitization of Homoserine Dehydrogenase during Seedling Growth

The sensitivity of homoserine dehydrogenase (EC 1.1.1.3) to inhibition by the feed-back modifier, l-threonine, was examined in preparations derived from etiolated shoots, roots, and lightgrown tissues of Zea mays L. var. earliking. A progressive decrease in enzyme sensitivity was observed during seedling growth. Enzyme derived from internode tissue retained a greater sensitivity to the effector than enzyme derived from apical portions of etiolated shoots, whereas enzyme from root tips was characteristically more sensitive than that prepared from mature cells of the root. Enzyme desensitization occurred rapidly during culture of excised shoots and the activities of both homoserine dehydrogenase and aspartokinase (EC 2.7.2.4) declined during shoot culture under a variety of conditions. The initial enzyme levels and the characteristic sensitivity of homoserine dehydrogenase were preserved during culture at 5 to 7 C, but desensitization was not prevented by inclusion of cycloheximide in the culture medium.Results of control experiments provide evidence that desensitization occurs in vivo. No alteration of the enzyme properties was detected during extraction or concentration of sensitive or insensitive enzyme or during coextraction of enzyme from mixed populations of different age shoots; nor was a differential distribution of inhibitors or activators indicated during assay of mixed preparations. The change in enzyme sensitivity was apparent under a variety of assay conditions and was not accompanied by changes in the apparent affinity of the enzyme for the substrate, homoserine. It is suggested that systematic changes in the regulatory characteristics of certain enzymes could be an important level of metabolic regulation during cellular differentiation.Three forms of maize homoserine dehydrogenaase were detected after acrylamide gel electrophoresis of samples derived from 72-hr shoots. Similar analysis of samples from older shoots revealed a broad asymmetric band of enzyme activity, suggesting that changes in the relative distribution of specific forms of the enzyme could be related to the growth-dependent changes in the sensitivity of maize homoserine dehydrogenase.     

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     

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。     

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     

3种禾草苗期生长和水分利用对土壤水分变化的反应

采用5种不同的水分处理,于室内生长箱内盆栽条件下对引种禾草柳枝稷(Panicum virgatum)、乡土禾草白羊草(Bothriochloa ischaemum)和栽培禾草谷子(Setaria italica)等苗期根冠生长和水分利用特征进行了比较分析.结果显示:(1)充分供水下3种禾草的苗期生物量和蒸腾效率均显著高于其它4种水分处理,而高水与低水处理下各自的根冠比无显著差异;(2)各水分处理下谷子苗期总生物量、蒸腾效率和耗水量均显著大于白羊草和柳枝稷;(3)在5种水分处理下,苗期根冠比谷子均最小,柳枝稷最大;(4)低降复水后,3种禾草生物量和蒸腾效率较低水处理分别显著提高16.7%-98.7%和28.2%-118.2%,显示出补偿效应,以白羊草增幅最大.结果表明,白羊草、谷子和柳枝稷在不同土壤水分处理下的苗期生物量、根冠分配比例以及水分利用效率差异反映了野生种、栽培种和引进种禾草苗期对半干旱环境条件水分生态适应性的异同.     

The HCN Potential of Chinese Sorghum and Sudangrass Varieties and the Changes of HCN Potential During the Growth of Seedling

In this paper, we measured the HCN potential (HCN-p) of 148 sorghum (Sorghum hicolor (L.) Moench) and sudangrass (Sorghum sudanense) varieties and the changes of HCN-P during seedling growth. The results showed that most of the varieties had their HCN-p more than 1000 ppm (94:59%). Among them, 33.11% belonged to 1400–1600 ppm, 22.97% to 1200–1400 ppm, 17.57% to 1000–1200 ppm, and 14.86% to 1600–1800 ppm. The varieties which HCN-p were less than 1000 ppm or higher than 1800 ppm had a little proportion (11.44%). The varieties with the lowest HCN-p were “Xinliang 80” (672 ppm), “sudancao” (753 ppm), “Huangke Sudancao” (856 ppm), “Limuji” (860 ppm), and “MI03” (876 ppm). Those with the highest HCN-p were “Yuanxin lA” (1967 ppm), “Shisanjie” (1904 ppm), “Mi- bangz” (Da Lai (1900 ppm), “7503 A” (1889 ppm), and Mijia Honggaoliang (1883 ppm). Sudangrass had the lowest HCN-p (about 700 ppm), sweet sorghum had higher HCN-p (about 1500 ppm). with the seedling growth, HCN-p reached its highest value in 4-day-old seedling. The first leaf had the highest HCN-p content, the second leaf and sheath had lower and root had the lowest.     

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.     

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。     

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.     

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