Changes in Glycolipid and Phospholipid Compositions in Cotyledons of Germinating Soybeans

This investigation was conducted to observe changes in the compositions of fatty acids, glycolipids (GL) and phospholipids (PL) in cotyledons of soybean seeds which were germinated either in the dark or the light at 28°C for 8 days. The patterns of changes in lipid composition depended on the germinating conditions tested. In general, non-polar lipids were metabolized at a faster rate than polar lipids. Changes in lipid contents in cotyledons were also observed more clearly with the polar lipids than with the non-polar ones, especially in the light-grown seedlings. The major component of lipid, GL in chloroplasts, appeared rapidly at an earlier stage in the cotyledons of light-grown seedlings. During germination of soybean seeds, acyl sterylglucoside in cotyledons decreased rapidly, but monogalactosyl diglyceride and digalactosyl diglyceride (DGD) increased in the light-grown seedlings, whereas sterylglucoside and DGD increased in the dark-grown seedlings.

The major PL present immediately after immersion were phosphatidyl ethanolamine (PE), phosphatidyl choline (PC) and phosphatidyl inositol (PI). During germination under both conditions, light and dark, PE in cotyledons decreased with PC or PI, while phosphatidic acid increased rapidly, and phosphatidyl glycerol and diphosphatidyl glycerol also increased slightly. These changes in glycolipid and phospholipid compositions during germination seem to occur from the formation of photosynthetic tissues and the metabolic interconversion of phospholipids.     

Fatty Acid Distribution in Glycolipids and Phospholipids in Cotyledons of Germinating Soybeans

This investigation was conducted to observe changes in the fatty acid distributions of glycolipids (GL) and phospholipids (PL) in cotyledons of soybean seeds which were germinated either in the dark or the light at 28°C for 8 days. The GL isolated from the total lipids of cotyledons at different germinating stages were : acyl sterylglycoside (ASG), monogalactosyl diglyceride (MGD), digalactosyl diglyceride (DGD) and sulfolipid (SL). The PL isolated from the same total lipids as described above were : diphosphatidyl glycerol (DPG), phosphatidic acid (PA), phosphatidyl ethanolamine (PE), phosphatidyl glycerol (PG), phosphatidyl choline (PC) and phosphatidyl inositol (PI).

During germination of soybean seeds, the content of linoleic and linolenic acids in MGD or DGD was markedly higher than that of the other GL. The positional distribution of fatty acids in PE, PC and PI was shown in all PL, in which saturated fatty acids, especially palmitic acid, were highly concentrated in position 1 and unsaturated fatty acids, especially linoleic acid, mainly occupied position 2. A remarkable difference in the changing patterns of fatty acid composition, which depended on the germinating conditions tested, was observed between GL and PL. The changes in fatty acid composition of GL were more marked in the light-grown seedlings than in the dark-grown, whereas those of PL were more remarkable in the latter than in the former. Therefore, the positional distribution of fatty acids in PL was more evident in the light-grown seedlings than in the dark-grown ones.

These results suggest the metabolic fate of GL and PL in cotyledons of soybean seeds, probably owing to the differences in the two germinating conditions tested.     

The Effect of Helminthosporic Root Rot on the Composition of Acyl Lipids of Wheat Seedlings

The changes of the molecular species composition of esterified fatty acids (FAs) of total and nonextractable lipids were determined in roots and etiolated shoots of 3- to 10-day-old wheat (Triticum aestivumL.) seedlings infected with the fungus Bipolaris sorokiniana, the agent of helminthosporic root rot. A novel technique of assessing the extent of the infection-induced deviation of FA composition, mol %, from the control value was developed. It consists in the quantitative determination of both the deviations in this composition and the extent of contribution of separate FA species to the deviations observed. The application of this technique has shown that, for the total lipids, the maximum of such a deviation, in accordance with the membrane theory of stress, directly coincided in time with the onset of a decrease in the dry matter content in both roots and shoots. In each of these, the deviation was primarily caused by the change in the content of those FA species that usually dominate in a specific group of membrane lipids prevailing in a given organ, viz., plastid glycolipids in shoots and extraplastidal membrane phospholipids in roots. In both cases, C₂₀–C₂₂FAs significantly contributed to the deviations observed. This fact seems to reflect an enhanced formation of epicuticular waxes rich in these FAs on the shoot and root surfaces as an adaptive response of plants to fungal infection. Nonextractable (annular) membrane lipids, because of their vital importance for the survival of plant cells, differed from the total lipids with a far greater stability of their quantitative FA composition under conditions of infection-induced metabolic disturbances.     

宁夏枸杞柱头和萌发花粉中钙分布特征

用焦锑酸钾沉淀法对宁夏枸杞柱头和花粉中的钙离子分布进行了研究.结果显示,宁夏枸杞柱头表皮有一覆盖层,其中有许多含钙沉淀颗粒的小泡,当花粉落到柱头后从覆盖层中吸水,在萌发孔的表面上聚集了较多的钙沉淀颗粒.同时,花粉内部出现许多含钙的小液泡,使花粉体积增大,内部产生膨压,花粉萌发;生长在覆盖层中的花粉管顶端穿过覆盖层小泡时,附近聚集了较多的钙沉淀颗粒,在花粉管壁上也附着较多的细小钙沉淀颗粒.萌发的花粉粒中由大液泡占据,在其亚顶端的细胞质中,聚集较多钙沉淀颗粒的线粒体膨大形成了一些含钙沉淀颗粒的小液泡,由这些小液泡融合形成的大液泡,将花粉管细胞质挤到其顶端,使其极性生长.这是首次发现在植物柱头覆盖层中有钙离子的现象,从体内证明了钙离子在花粉萌发过程中的现象.讨论了枸杞柱头组织中钙的分布和花粉管的萌发与生长的关系.     

Barbiturate-induced Disorientation of Root and Shoot Geotropism in Germinating Cruciferous Seedlings

Cruciferous seedlings germinated on glass-distilled water andon barbital manifested normal root and shoot geotropisms whereastwisted roots and shoots were evident in seedlings germinatedon amobarbital and secobarbital, the roots often being completelysuspended in the air. The marked difference in germination anddevelopment behaviour of cress and white mustard seedlings germinatedon barbital compared with that on amobarbital and secobarbitalindicate that the Meyer-Overton principle of drug potency andlipid solubility was operative in both species of germinatingseedlings. Lepidium sativum L., Sinapsis alba L., seed germination, geotropism, barbiturates     

Survey of the Proteolytic Activities Degrading the Kunitz Trypsin Inhibitor and Glycinin in Germinating Soybeans (Glycine max)

The cotyledons of the soybean (Glycine max [L.] Merrill cv Amsoy 71) were examined for proteolytic activities capable of degrading soybean seed proteins. Three distinct activities were identified that attack the native Kunitz soybean trypsin inhibitor of Amsoy 71, Ti^a. Protease K1 cleaves Ti^a to Ti^a_m, the inhibitor form lacking the five carboxyl-terminal amino acid residues relative to Ti^a. Protease K1 is a cysteine protease that peaks in activity on day 4 after the beginning of imbibition, with maximal activity toward Ti^a at pH 4. The characteristics of protease K1 are consistent with the involvement of this protease in the initial proteolysis of the Kunitz inhibitor during germination. Protease K2 also degrades Ti^a at pH 4 but produces no electrophoretically recognizable products. It peaks later in seedling growth, at day 8. Protease K3 degrades Ti^a to products other than Ti^a_m. However, it is active at pH 8. Two proteolytic activities were identified that attack the major storage protein, glycinin. Protease G1 (which appears by 4 days after imbibition) specifically cleaves the acidic polypeptides of glycinin at pH 4, yielding a product approximately 1.5 kilodaltons smaller. Protease G1 is inhibited by metal chelators as well as by reagents reactive toward thiols. Protease G2 also degrades the glycinin acidic chains at pH 4, but without the appearance of electrophoretically recognizable products. Protease G2, while present at low levels in the dry seed, is found primarily in the cotyledons after 8 days of growth.     

胚轴对萌发豌豆子叶中淀粉酶活性表达的影响

萌发豌豆的上、下肢轴均能诱导子叶中淀粉酶活性,外源GA和6—BA具有类似胚轴的作用。离体子叶的淀粉酶凝胶电泳只有一条活性极低的酶带,连生子叶中有两条酶带,其中由胚轴诱导新出现了一条活性很高的同工酶带,它的活性受亚胺环己酮的强烈抑制,而受放线菌素D影响不大。推测豌豆子叶中存在淀粉酶的长寿命mRN—A,胚轴和外源激素的作用在于促进mRNA的翻译。     

Developmental Changes in the Sterol Composition and the Glycerol Content of Cuticular and Internal Lipids of Three Species of Flies

The glycerol concentration and the composition of cuticular and internal sterols in three medically and forensically important fly species, viz., Musca domestica, Sarcophaga carnaria, and Calliphora vicina, were analyzed. The cuticular and internal lipid extracts were separated by HPLC‐LLSD, after which the sterol fraction was characterized by GC/MS in total ion current (TIC) mode. The cuticular lipids of M. domestica larvae contained seven sterols, while in pupae and females, six sterols were identified. Five sterols were found in the cuticular lipids of M. domestica males. The internal lipids of M. domestica larvae and pupae contained six and seven sterols, respectively, while those of male and female flies contained only five sterols. Sitosterol, cholesterol, and campesterol were the dominant sterols in M. domestica, while campestanol, stigmasterol, sitostanol, and fucosterol were identified in low concentrations or in traces. In contrast, cuticular and internal lipids of S. carnaria and C. vicina contained only cholesterol. Glycerol was identified in all stages of M. domestica, S. carnaria, and C. vicina. For all the three examined fly species, the present study clearly showed species‐specific developmental changes in the composition of cuticular and internal sterols as well as in the glycerol concentration.     

Early Changes in the Nucleotide Pools of Germinating Rust Uredospores

Puccinia graminis uredospores were induced to germinate on a water surface and the nucleotide/nucleoside pools were determined by high performance liquid chromatography. Distinct phases of germination could be discriminated by correlating the changes of individual nucleotide pools with characteristic morphological changes. During the first 15 min no visible changes of the cell wall were observed whereas the adenine nucleotide pools increased strongly indicating an activation of the energy metabolism. The stage preceding hyphal growth revealed large increases in the precursor pool for cell wall synthesis (UDP-N-acetylglucosamine). The early phases of germination are obviously controlled by distinct metabolic transitions. Furthermore, correlations of pool contents and changes during germination with the germination efficiency of the three uredospore batches investigated are discussed.     

Changes in Total and Polar Lipids and Their Fatty Acid Composition in Tobacco Leaves during Growth and Senescence

Total lipids, total fatty acids and most polar lipids of tobaccoleaves increased and decreased almost concomitantly with changesin chlorophyll during leaf development and senescence. In individualpolar lipids, marked changes were observed in compounds associatedwith chloroplast membranes, i.e., monogalactosyldiglyceride(MGDG), digalactosyldiglyceride and sulfoquinovosyldiglyceride.Phosphatidylglycerol (PG) was the first to decrease during leafdvelopment. Green leaves contained a considerable amount ofhexadecatrienoic acid (16: 3) in MGDG, which suggests that tobaccobelongs to 16: 3- plants. The proportion of linolenic acid infour chloroplast lipids was lower in senescent leaves than ingreen leaves. Similar phenomena were also observed in 16: 3of MGDG and in hexadecenoic acid of PG. (Received April 27, 1981; Accepted July 11, 1981)     

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.     

瓯江彩鲤胚胎发育过程中脂、蛋白及 碳水化合物水平的变化

为了探究鱼类胚胎发育过程中主要营养物质消耗利用的规律,采用生物化学方法测定了瓯江彩鲤(Cyprinus carpio var.color)胚胎发育过程中7个发育期的主要生化成分.结果表明,(1)瓯江彩鲤受精卵期水分含量达70%以上,随着发育的进行,胚胎的含水量呈逐渐上升的趋势;(2)胚胎发育过程中脂质的利用主要集中在胚...     

Changes in the Activity of Acetyl CoA Carboxylase in Germinating and Ripening Sunflower Seeds

Activity of acetyl CoA carboxylase was determined in germinating and maturing sunflower (Helianthus annuus L.) cv. Rum Sun Record seeds. A constant decrease was observed in germi nating embryos. Exposure of etioplasts to light intensity of 500 (74 mW . cm^?2) lux for different time intervals decreased the activity of the enzyme in the embryos. A reverse trend was observed in ripening embryos where the ATP-Pi exchange rate was found to be directly correlated to the activity of acetyl CoA carboxylase.     

干旱条件下冬小麦幼苗根细胞膜脂组成的变化

干旱条件下小麦幼苗根膜脂总脂肪酸含量、磷脂含量及总脂肪酸双键指数均下降,而游离甾醇含量却明显增加,结果导致游离甾醇／磷脂比率上升。用薄层层析法测得小麦根细胞磷脂主要由磷脂酰胆碱(PC)、磷脂酰乙醇胺(PE)、磷脂酰肌醇(PI)及磷脂酸(PA)组成。干旱降低了各种磷脂的含量,但不改变其相对配比。文中讨论了膜脂代谢变化与植物抗旱性的关系。     

萌发中食松幼苗淀粉合酶同工酶与淀粉成分的关系

利用14C－ADPG标定法测定可溶性及与淀粉粒结合的淀粉合酶活性,采用过氯酸抽提、DMSO玻璃纤维纸层析、硫酸水解法定量测定各类淀粉成分,探讨了食松（PinusedulisEngelm）幼苗生长过程中淀粉合酶与淀粉成分间的关系。结果表明,在胚根出现以后,淀粉含量迅速增加,伴随着淀粉颗粒数目和质量的增加,两类淀粉合酶活性的增加以及淀粉合酶免疫印迹图谱的变化。支链淀粉是食松淀粉的主要成分,占总淀粉的84％。可溶性淀粉合酶峰值比淀粉粒结合的淀粉合酶活性峰值高1．3倍,与支链淀粉和直链淀粉的比例相对应。结果支持食松可溶性淀粉合酶是负责支链淀粉合成的主要酶的假说,同时表明淀粉粒结合的淀粉合酶在支链淀粉的合成中也有作用。     

Changes in the Biochemical Composition, Structure, and Function of Pea Leaf Chloroplasts in Iron Deficiency and Root Anoxia

A combined effect of iron deficiency and root anoxia on the biochemical composition, function, and structure of pea leaf chloroplasts was studied. It was found that the chlorosis of apical leaves in response to iron deficiency was determined by the reduction of light-harvesting complexes I and II. Under root anoxia, complexes of the reaction centers of photosystems I and II degraded first. Weak activity was preserved even in yellow and white leaves under the effect of both factors. The ultrastructure of leaf chloroplasts gradually degraded. Initially, intergranal thylakoid sites were reduced, and the longitudinal orientation of grana was disturbed. However, yellow and white leaves still retained small thylakoids and grana. It is concluded that the degrading effects of iron deficiency and root anoxia on the complex composition and leaf chloroplast structure and function are additive because of their autonomous mechanisms.     

Changes in the Epilimnetic Bacterial Community Composition,Production, and Protist-Induced Mortality along the Longitudinal Axis of a Highly Eutrophic Reservoir

We studied changes in the epilimnetic bacterial community composition (BCC), bacterial biomass and production, and protistan succession and bacterivory along the longitudinal axis of the canyon-shaped, highly eutrophic Sau Reservoir (NE Spain) during two sampling campaigns, in April and July 1997. Longitudinal changes in BCC from the river inflow to the dam area of the reservoir were detected by using oligonucleotide probes targeted to the kingdom Bacteria, to the alpha, beta, and gamma subclasses (ALFA, BETA, and GAMA) of the class Proteobacteria, and to the Cytophaga/Flavobacterium (CF) cluster. In general, the inflow of the organically loaded Ter river, with highly abundant allochthonous bacterial populations, induced a clearly distinguishable longitudinal succession of the structure of the microbial food web. The most dynamic changes in microbial parameters occurred at the plunge point, the mixing area of river water and the reservoir epilimnion. Changes within members of BETA and CF were the most important in determining changes in BCC, bacterial abundance and biomass. Much less relevant changes occurred within the less abundant ALFA and GAMA bacteria. From the plunge point downstream, we described a significant shift in BCC in the form of decreased proportions of BETA and CF. This shift spatially coincided with the highest values of heterotrophic nanoflagellate bacterivory (roughly doubled the bacterial production). CF numerically dominated throughout the reservoir without any marked longitudinal changes in their mean cell volume. In contrast, very large cells affiliated to BETA clearly dominated in the allochthonous bacterial biomass brought by the river. BETA showed a marked downstream trend of decreasing mean cell volume. We conclude that the observed BCC shift and the longitudinal shift in food web structure (bacteria-heterotrophic nanoflagellates-ciliates) resulted from highly complex interactions brought about by several major factors: varying hydrology, the high localized allochthonous input of organic matter brought by the river, downstream changing substrate availability, and selective protistan bacterivory.     

Changes in the Content of Phytyl and Geranylgeranyl Esters of Germinating Polytrichum commune Spores

Polytrichum commune spores contained esterified phytol and geranylgeraniol, 706 and 114 μg, respectively, per 100 mg dry weight of freshly collected spores. After storage for 9 months the level of esterified phytol of the spores was decreased by c. 600 μg, whereas the level of esterified geranylgeraniol was more or less unchanged. The changes in the level of esterified prenols during germination follow the same pattern in freshly collected and in 9 month-old spore material. An immediate steep decrease between 0 and 3 h was followed by an increase in the level of esterified phytol between 3 and 12 h and by a constant value for esterified geranylgeraniol during the same period. Between 12 and 48 h the level of both types of esterified prenols decreased. In the freshly collected spores the amount of esterified prenols increased after 48 h of germination, in the older spores after 72 h. Free phytol was found in trace amounts in dry and germinating spores and in the protonema.