Microbial Changes in Sweet Sorghum (Sorghum bicolor) Juices

Juice freshly expressed from Sorghum bicolor for making sweet sorghum syrup contained 10⁸ microorganisms per ml. The dominant bacterium was Leuconostoc mesenteroides, followed by gram-negative rods. Lactobacilli, yeasts, and nonfecal coliform bacteria each comprised about 1% of the microbial population. Spoilage of juice, manifested by a sour odor, discoloration, and foaming, occurred between 5 and 12 h at ambient temperatures. Spoilage was correlated with a drop in pH from 4.9 to 4.5 L. mesenteroides was the dominant spoiling agent at 20°C, and Lactobacillus plantarum was the dominant spoiling agent at 32°C, as determined by pure culture studies. Juice may be stored for 14 days at 4°C if promptly refrigerated.     

Structural Basis of pH Dependence of Neoculin,a Sweet Taste-Modifying Protein

Among proteins utilized as sweeteners, neoculin and miraculin are taste-modifying proteins that exhibit pH-dependent sweetness. Several experiments on neoculin have shown that His11 of neoculin is responsible for pH dependence. We investigated the molecular mechanism of the pH dependence of neoculin by molecular dynamics (MD) calculations. The MD calculations for the dimeric structures of neoculin and His11 mutants showed no significant structural changes for each monomer at neutral and acidic pH levels. The dimeric structure of neoculin dissociated to form isolated monomers under acidic conditions but was maintained at neutral pH. The dimeric structure of the His11Ala mutant, which is sweet at both neutral and acidic pH, showed dissociation at both pH 3 and 7. The His11 residue is located at the interface of the dimer in close proximity to the Asp91 residue of the other monomer. The MD calculations for His11Phe and His11Tyr mutants demonstrated the stability of the dimeric structures at neutral pH and the dissociation of the dimers to isolated monomers. The dissociation of the dimer caused a flexible backbone at the surface that was different from the dimeric interface at the point where the other monomer interacts to form an oligomeric structure. Further MD calculations on the tetrameric structure of neoculin suggested that the flexible backbone contributed to further dissociation of other monomers under acidic conditions. These results suggest that His11 plays a role in the formation of oligomeric structures at pH 7 and that the isolated monomer of neoculin at acidic pH is responsible for sweetness.     

甜高梁离体再生体系的建立和组织结构变化的观察

以甜高粱成熟种子为外植体,调节不同生长调节物质配比建立甜高梁离体再生体系。结果表明在MS＋2．5mg．L^-12,4．D＋0．3mg·L^-1KT培养基上愈伤组织的诱导率可达77．26％;比较不同浓度6-BA或TDZ与NAA配合诱导愈伤组织分化和苗形成的情况,TDZ的作用优于6-BA。观察培养组织的结构变化发现,甜高粱离体再生过程中除了体细胞胚发生途径之外,还伴随有器官发生途径。     

甜高梁种子人工老化过程中活性氧清除酶活性的变化

研究甜高粱品种'意达利'种子人工老化过程中种子活力与活性氧清除酶活性之间关系的结果表明:随着老化处理(100%RH,43℃)的时间进程,种子的萌发率、活力指数以及由存活种子形成的幼苗鲜重下降,相对渗漏率增加,丙二醛含量下降.超氧物歧化酶、抗坏血酸过氧化物酶、过氧化氢酶、谷胱甘肽还原酶和脱氢抗坏血酸还原酶的活性在人工老化初期增加,而后下降.据此认为活性氧清除酶活性下降可能是甜高粱种子活力丧失的原因之一.     

甜高粱种质资源在新疆的多样性表现及聚类分析

采用多样性指数、变异系数和聚类分析等方法,对国内外72份甜高粱种质资源24个性状进行遗传多样性研究。结果表明,14个质量性状中粒色的遗传多样性指数最高为1.6333,幼苗色和结实形式的遗传多样性指数最低为0,平均为0.7460;10个数量性状中穗长、茎粗、锤度、单穗粒重、单株秆重、出汁率、千粒重、株高、穗重、生育期都存在较大的变异,变异系数幅度为7.85%～53.01%,各性状多样性指数均较大,平均2.0061;穗长的多样性指数最大,为2.1383,生育期多样性指数最小,为1.7331,表明新疆现有甜高粱资源拥有丰富的遗传多样性。聚类分析将72份资源划分为四大类。     

Temperature-Induced Protein Conformational Changes in Barley Root Plasma Membrane-Enriched Microsomes: II. Intrinsic Protein Fluorescence

The membrane-bound proteins of barley (Hordeum vulgare L. cv Conquest) root plasma membrane-enriched microsomes displayed fluorescence typical of protein-associated trytophan residues. The protein fluorescence intensity was sensitive to variations in sample temperature. The temperature-induced decline in protein fluorescence intensity was nonlinear with slope discontinuities at about 12 and 32°C. Detergents at levels above their critical micelle concentration enhanced protein fluorescence. Glutaraldehyde reduced protein fluorescence. Protein fluorescence polarization increased at temperatures above 30°C. Both the rate of tryptophan photoionization and the fluorescence intensity of the photoionization products suggested alterations in membrane protein conformation between 12 and 32°C. The quenching of the intrinsic protein fluorescence by acrylamide and potassium iodide indicated changes in accessibility of the extrinsic agents to the protein tryptophan residues beginning at about 14°C. The results indicate thermally induced changes in the dynamics of the membrane proteins over the temperature range of 12 to 32°C which could account for the complex temperature dependence of the barley root plasma membrane ATPase.     

Catabolism of Fructose and Mannitol in Clostridium thermocellum: Presence of Phosphoenolpyruvate: Fructose Phosphotransferase, Fructose l-Phosphate Kinase, Phosphoenolpyruvate: Mannitol Phosphotransferase, and Mannitol l-Phosphate Dehydrogenase in Cell Extracts

Fructose and mannitol are fermented by Clostridium thermocellum in a medium containing salts and 0.5% yeast extract. The initial reaction in the catabolism of fructose was found to be the formation of fructose l-phosphate by phosphoenolpyruvate (PEP):fructose phosphotransferase which resembles the Kundig-Roseman phosphotransferase system. The phosphorylation of fructose l-phosphate to form fructose-1, 6-diphosphate is catalyzed by fructose l-phosphate kinase. Fructose-1, 6-diphosphate can be further metabolized by the Embden-Meyerhof pathway. The formation of both PEP:fructose phosphotransferase and fructose l-phosphate kinase is induced by growth in fructose medium. Mannitol catabolism was found to proceed by the phosphorylation of mannitol by PEP:mannitol phosphotransferase to form mannitol l-phosphate. Mannitol l-phosphate is converted to fructose 6-phosphate by a nicotinamide adenine dinucleotide-specific mannitol l-phosphate dehydrogenase. The fructose 6-phosphate formed in the reaction can enter the glycolytic scheme. The formation of both PEP:mannitol phosphotransferase and mannitol l-phosphate dehydrogenase is induced by growth in mannitol medium. Evidence is presented for the induction by mannitol of PEP:mannitol phosphotransferase and mannitol l-phosphate dehydrogenase in suspensions of fructose-grown cells.     

Physiological Changes in Cultured Sorghum Cells in Response to Induced Water Stress : II. Soluble Carbohydrates and Organic Acids

Eight cultivars Sorghum bicolor (L.) Moench were grown as callus cultures under induced, prolonged water stress (8 weeks), with polyethylene glycol in the medium. Concentrations of soluble carbohydrates and organic acids in callus were measured at the end of the growth period to determine differences in response to prolonged water stress. Sucrose, glucose, fructose, and malate were the predominant solutes detected in all callus at all water potentials. All cultivars had high levels of solutes in the absence of water stress and low levels in the presence of prolonged water stress. However, at low water potentials, low levels of solutes were observed in drought-tolerant cultivar callus and high solute levels were observed in drought-susceptible cultivar callus. Estimated sucrose concentrations were significantly higher in water-stressed, susceptible cultivar callus. Large solute concentrations in susceptible cultivar callus were attributed to osmotic adjustment and/or reduced growth during water stress.     

Phytochrome and Calcium Regulated Protein Phosphorylation in Sorghum bicolor

Irradiation with red light of Sorghum bicolor seedlings stimulated in vitro phosphorylation of 55 kD and several other soluble polypeptides in a development-dependent manner. The red light stimulated phosphorylation of 55 kD polypeptide was more in 6-day-old etiolated plants as compared to 5-day-old plants. The in vitro phosphorylation of 55 kD polypeptide was enhanced further when calcium was added to the extracts obtained from red light irradiated tissues of 6-day-old seedlings. This effect was inhibited in the presence of calmodulin inhibitors. There was no significant stimulation in the phosphorylation of this polypeptide by calcium in 5-day-old and 7-day-old etiolated plants. Besides 55 kD, the phosphorylation of several other polypeptides was either stimulated or inhibited by light, calcium and calmodulin inhibitors suggesting involvement of both kinases and phosphatases in light-mediated phosphorylation.     

Effects of spermine on transferrin and iron uptake by reticulocytes: II. Changes in intravesicular pH

An increase in extracellular spermine concentration brought about a progressive rise in intralysosomal pH in rabbit reticulocytes. Since intracellular release of iron from transferrin is believed to involve the protonation of the iron-transferrin complex, the rise in intralysomal pH could account for the inhibitory effect of spermine on iron uptake. The inhibition could be reversed if spermine was removed by washing. As a result of spermine treatment, more acid-labile N-terminal monoferric transferrin and less apotransferrin were released from the cell. These results are consistant with the protonation theory of iron release.     

施肥方式对甜高粱秸秆产量和糖分含量以及酶活性的影响

采用田间试验方法,研究了4种施肥方式(CK、A1、A2、A3)对2个甜高粱品种‘新高粱3号’(XT-2)和‘新高粱9号’(T601)秸秆生物产量、糖分含量和蔗糖代谢相关酶活性的影响。结果表明:(1)施肥方式对2个品种的生育天数没有影响;品种XT-2以氮、磷、钾后移改进作追肥施入处理(A3)的生物产量最高(54 916.96kg/hm2),而T601以生育前期施入磷、钾肥全部作基肥一次施入处理(A1)的生物产量最高(64 136.60kg/hm2),两者分别比CK(不施肥)增产14.96%和10.48%。(2)甜高粱秸秆总糖含量与蔗糖含量随生育期变化趋势基本一致,秸秆总糖含量在拔节期很低,其基本从挑旗期开始积累,并于成熟期达到最高值,且以XT-2品种在A3处理下的总糖含量最高(达到鲜基重12.7%)。(3)施肥方式对甜高粱秸秆蔗糖磷酸合成酶合成酶(SPS)和蔗糖合成酶(SS)活性的影响很明显,并以品种T601在A3处理下的SS活性最高(266.74mg.g-1.h-1)、品种XT-2在A1处理下的SPS活性最高(431.21mg.g-1.h-1),且二者均与其他处理差异极显著。研究发现,适宜施肥方式能显著提高甜高粱秸秆的生物产量、糖分含量和蔗糖代谢相关酶(SS、SPS)活性,从而有效改善甜高粱品质,增加其产量。     

Roller Compaction, Granulation and Capsule Product Dissolution of Drug Formulations Containing a Lactose or Mannitol Filler, Starch, and Talc

This study investigated the influence of excipient composition to the roller compaction and granulation characteristics of pharmaceutical formulations that were comprised of a spray-dried filler (lactose monohydrate or mannitol), pregelatinized starch, talc, magnesium stearate (1% w/w) and a ductile active pharmaceutical ingredient (25% w/w) using a mixed-level factorial design. The main and interaction effects of formulation variables (i.e., filler type, starch content, and talc content) to the response factors (i.e., solid fraction and tensile strength of ribbons, particle size, compressibility and flow of granules) were analyzed using multi-linear stepwise regression analysis. Experimental results indicated that roller compacted ribbons of both lactose and mannitol formulations had similar tensile strength. However, resulting lactose-based granules were finer than the mannitol-based granules because of the brittleness of lactose compared to mannitol. Due to the poor compressiblility of starch, increasing starch content in the formulation from 0% to 20% w/w led to reduction in ribbon solid fraction by 10%, ribbon tensile strength by 60%, and granule size by 30%. Granules containing lactose or more starch showed less cohesive flow than granules containing mannitol and less starch. Increasing talc content from 0% to 5% w/w had little effect to most physical properties of ribbons and granules while the flow of mannitol-based granules was found improved. Finally, it was observed that stored at 40 °C/75% RH over 12 weeks, gelatin capsules containing lactose-based granules had reduced dissolution rates due to pellicle formation inside capsule shells, while capsules containing mannitol-based granules remained immediate dissolution without noticeable pellicle formation.     

A Comprehensive Analysis of Chromoplast Differentiation Reveals Complex Protein Changes Associated with Plastoglobule Biogenesis and Remodeling of Protein Systems in Sweet Orange Flesh

Globular and crystalloid chromoplasts were observed to be region specifically formed in sweet orange (Citrus sinensis) flesh and converted from amyloplasts during fruit maturation, which was associated with the composition of specific carotenoids and the expression of carotenogenic genes. Subsequent isobaric tag for relative and absolute quantitation (iTRAQ)-based quantitative proteomic analyses of purified plastids from the flesh during chromoplast differentiation and senescence identified 1,386 putative plastid-localized proteins, 1,016 of which were quantified by spectral counting. The iTRAQ values reflecting the expression abundance of three identified proteins were validated by immunoblotting. Based on iTRAQ data, chromoplastogenesis appeared to be associated with three major protein expression patterns: (1) marked decrease in abundance of the proteins participating in the translation machinery through ribosome assembly; (2) increase in abundance of the proteins involved in terpenoid biosynthesis (including carotenoids), stress responses (redox, ascorbate, and glutathione), and development; and (3) maintenance of the proteins for signaling and DNA and RNA. Interestingly, a strong increase in abundance of several plastoglobule-localized proteins coincided with the formation of plastoglobules in the chromoplast. The proteomic data also showed that stable functioning of protein import, suppression of ribosome assembly, and accumulation of chromoplast proteases are correlated with the amyloplast-to-chromoplast transition; thus, these processes may play a collective role in chromoplast biogenesis and differentiation. By contrast, the chromoplast senescence process was inferred to be associated with significant increases in stress response and energy supply. In conclusion, this comprehensive proteomic study identified many potentially new plastid-localized proteins and provides insights into the potential developmental and molecular mechanisms underlying chromoplast biogenesis, differentiation, and senescence in sweet orange flesh.Chromoplasts are special organelles with superior ability to synthesize and store massive amounts of carotenoids, bringing vivid red, orange, and yellow colors to many flowers, fruits, and vegetables (Li and Yuan, 2013). Chromoplasts exhibit various morphologies, such as crystalline, globular, tubular, and membranous structures (Egea et al., 2010). The relationship between the architecture and carotenoid composition has been well stated in diverse pepper (Capsicum annuum) and tomato (Solanum lycopersicum) fruits (Kilcrease et al., 2013; Nogueira et al., 2013). Crystalline bodies have been observed in carrot (Daucus carota; Frey-Wyssling and Schwegler, 1965) and tomato (Harris and Spurr, 1969), which predominantly consist of β-carotene and lycopene, respectively. Globular and/or tubular-globular chromoplasts, in which numerous lipid droplets (also named plastoglobules), which act as passive storage compartments for triglycerides, sterol ester, and some pigments, are accumulated, were described for yellow fruits from kiwi (Actinidia deliciosa), papaya (Carica papaya), and mango (Mangifera indica), which contain lutein, β-cryptoxanthin, and β-carotene as the major pigments, respectively (Vasquez-Caicedo et al., 2006; Montefiori et al., 2009; Schweiggert et al., 2011). Carotenoid composition has been reported to be regulated by the expression of carotenogenic genes in the flesh of various citrus fruits differing in their internal colors (Fanciullino et al., 2006, 2008). Chromoplasts are frequently derived from fully developed chloroplasts, as seen during fruit ripening from green to red or yellow fruits in tomato and pepper (Egea et al., 2010). In some cases, chromoplasts also arise from nonphotosynthetic plastids, such as colorless proplastids, leucoplasts, or amyloplasts (Knoth et al., 1986; Schweiggert et al., 2011). To date, most studies on chromoplast differentiation have been focused on the synthesis of carotenoids by combining biochemical and molecular analyses (Cazzonelli and Pogson, 2010; Egea et al., 2010; Bian et al., 2011; Li and Yuan, 2013), and little is known about the molecular mechanisms underlying chromoplast biogenesis (Li and Yuan, 2013).Recently, proteomics has become an efficient tool to study the protein composition of subcellular organelles such as chromoplasts and their dynamic changes during the development of a particular plant organ/tissue. The majority of chromoplast-related studies are concerned with the functions of these organelles in various crops, such as pepper, tomato, watermelon (Citrulis lanatus), carrot, cauliflower (Brassica oleracea), and papaya (Siddique et al., 2006; Wang et al., 2013). However, only a few of such studies addressed the mechanisms underlying plastid differentiation, such as the transition from proplastid to chloroplast in maize (Zea mays; Majeran et al., 2010), from etioplast to chloroplast in pea (Pisum sativum; Kanervo et al., 2008) and rice (Oryza sativa; Kleffmann et al., 2007), and from chloroplast to chromoplast in tomato (Barsan et al., 2012). In tomato, chromoplastogenesis appears to be associated with major metabolic shifts, including a strong decrease in abundance of the proteins involved in light reaction and an increase in terpenoid biosynthesis and stress-response proteins (Barsan et al., 2012). These changes in proteins are in agreement with the structural changes occurring in tomato during fruit ripening, which is characterized by the loss of chlorophyll and the synthesis of colored compounds. Chromoplast differentiation from nonphotosynthetic plastids occurs frequently in a number of plant tissues, such as watermelon flesh and carrot root (Kim et al., 2010; Wang et al., 2013). However, to the best of our knowledge, no large-scale proteomic study for understanding this developmental process has been reported.Citrus is one of the most economically important fruit crops in the world. Different from the model fruit tomato, which represents climacteric fruits, citrus shows nonclimacteric characteristics during fruit maturation. Additionally, citrus fruits exhibit a unique anatomical fruit structure consisting of two major sections, the pericarp and the edible flesh. Considerable progress has been made in the understanding of chromoplast differentiation in the pericarp of citrus fruits (Eilati et al., 1969; Iglesias et al., 2007), which is a process similar to that of tomato and pepper (Egea et al., 2010). However, little is known about the molecular basis of chromoplast differentiation in the edible flesh, even though there is increasing evidence suggesting an essential role of carotenoid synthesis in inducing chromoplast differentiation (Egea et al., 2010; Bian et al., 2011; Li and Yuan, 2013). Recently, we successfully isolated and purified intact chromoplasts containing a large number of plastoglobules from the flesh of sweet orange (Citrus sinensis) fruits at the maturation stage (Zeng et al., 2011). The same method has also been used successfully to isolate plastids from sweet orange flesh in earlier maturation stages (Zeng et al., 2014), thus making comparative and quantitative proteomic analyses of plastid differentiation possible. In this study, we investigated how ultrastructural changes of plastids/chromoplasts during sweet orange fruit maturation might be associated with changes in the composition of carotenoids and the expression of carotenogenic genes in red and yellow flesh of the fruits. Furthermore, we employed the isobaric tag for relative and absolute quantitation (iTRAQ)-based technology to investigate how protein compositional changes might be correlated with metabolic and structural changes in the plastids of sweet orange flesh during their transformation from amyloplasts to chromoplasts.     

Water Relations, Diurnal Acidity Changes, and Productivity of a Cultivated Cactus, Opuntia ficus-indica

Physiological responses of the Crassulacean acid metabolism (CAM) plant Opuntia ficus-indica (Cactaceae) were studied on a commercial plantation in central Chile. Young cladodes (flattened stems) and flower buds exhibited daytime stomatal opening, whereas mature cladodes and fruit exhibited the nocturnal stomatal opening characteristic of CAM plants. Severe water stress suppressed the nocturnal stomatal opening by mature cladodes, but their high water vapor conductance occurring near dawn was not affected. Nocturnal acidity increases were not as sensitive to water stress as was the nocturnal stomatal opening. The magnitude of the nocturnal acidity increases depended on the total daily photosynthetically active radiation (PAR), being 90% PAR-saturated at 27 moles per square meter per day for a mean nighttime air temperature of 5°C and at 20 moles per square meter per day for 18°C. Inasmuch as the PAR received on unshaded vertical surfaces averaged about 21 moles per square meter per day, nocturnal acidity increases by the cladodes were on the verge of being PAR-limited in the field. The net assimilation rate, which was positive throughout the year, annually averaged 3.4 grams per square meter per day for 1.0- and 2.0-year-old plants. Plants that were 5.4 years old had 7.2 square meters of cladode surface area (both sides) and an annual dry weight productivity of 13 megagrams (metric tons) per hectare per year when their ground cover was 32%. This substantial productivity for a CAM plant was accompanied by the highest nocturnal acidity increase so far observed in the field, 0.78 mole H⁺ per square meter.     

Protein unfolding in detergents: effect of micelle structure,ionic strength,pH, and temperature

The 101-residue monomeric protein S6 unfolds in the anionic detergent sodium dodecyl sulfate (SDS) above the critical micelle concentration, with unfolding rates varying according to two different modes. Our group has proposed that spherical micelles lead to saturation kinetics in unfolding (mode 1), while cylindrical micelles prevalent at higher SDS concentrations induce a power-law dependent increase in the unfolding rate (mode 2). Here I investigate in more detail how micellar properties affect protein unfolding. High NaCl concentrations, which induce cylindrical micelles, favor mode 2. This is consistent with our model, though other effects such as electrostatic screening cannot be discounted. Furthermore, unfolding does not occur in mode 2 in the cationic detergent LTAB, which is unable to form cylindrical micelles. A strong retardation of unfolding occurs at higher LTAB concentrations, possibly due to the formation of dead-end protein-detergent complexes. A similar, albeit much weaker, effect is seen in SDS in the absence of salt. Chymotrypsin inhibitor 2 exhibits the same modes of unfolding in SDS as S6, indicating that this type of protein unfolding is not specific for S6. The unfolding process in mode 1 has an activation barrier similar in magnitude to that in water, while the activation barrier in mode 2 is strongly concentration-dependent. The strong pH-dependence of unfolding in SDS and LTAB suggests that the rate of unfolding in anionic detergent is modulated by repulsion between detergent headgroups and anionic side chains, while cationic side chains modulate unfolding rates in cationic detergents.     

Post-harvest Changes in the Respiratory Activity of and Ethanol Accumulation in Fresh Rice Grains

Fresh rice grains stored under anaerobic conditions at 4°C showed a strong activity of anaerobic respiration at 30°C. When stored at 30°C, the rates of both oxygen consumption and carbon dioxide evolution declined rapidly. The ethanol content in paddy at the post-harvest stage was increased at 4°C, whereas no significant accumulation of ethanol was observed at 30°C. The accumulated ethanol in paddy was depleted as the storage temperature was raised from 4 to 30°C. In contrast, a temperature-dependent accumulation was observed with a lowering from 30 to 4°C. On the other hand, ethanol content in brown rice changed little with storage temperature. On the basis of these results, it is assumed that ethanol is more easily accumulated in the rice grains against diffusion to the atmosphere at the lower temperature.     

H Uptake and Release during Circadian Rhythmic Movements of Excised Samanea Motor Organs : Effects of Mannitol, Sorbitol, and External pH

We investigated H⁺ fluxes during circadian rhythmic movements of Samanea saman leaflets by monitoring the pH of a weakly buffered medium bathing extensor or flexor motor tissue excised at different times during 51 hours of darkness. Experiments were made in media of two different osmotic potentials: −0.3 megapascal (control medium) and −1.2 megapascals (control medium supplemented with 0.4 molar mannitol or sorbitol). Both extensor and flexor tissue took up H⁺ from the control medium at all times when the initial pH was 5.5. Rates of uptake by the extensor varied rhythmically in phase with the leaflet movement rhythm, whereas rates for the flexor were similar at all times. Addition of 0.4`molar mannitol (or sorbitol) to the medium magnified the amplitude of the rhythm in H⁺ uptake and release by extensor tissue and revealed a rhythm with flexor tissue. In the flexor, mannitol promoted H⁺ release (or reduced H⁺ uptake) at all times. We propose that mannitol reduces flexor cell turgor, and that low turgor activates the H⁺ pump. The magnitude and/or direction of pH changes varied with the initial pH of the medium. The pH values after 60 minutes converged to a narrow range, suggesting that cell wall pH might be regulated.     

非洲紫罗兰叶片脱分化过程中核酸蛋白质和滨粉含量动态的研究

本文测定了非洲紫罗兰（Ｓａｉｎｔｐａｕｌｔａｉｏｎａｎｔｈａ）叶片脱分化过程中核酸、蛋白质和波粉的含量。结果表明：发生脱分化的叶片中的蛋白质和淀粉含量均低于对照,而ＲＮＡ含量则高于对照,ＤＮＡ含量无明显差异。叶片培养的第一天内,发生脱分化的叶片中的蛋白质含量明显下降,对照中的蛋白质含量上升。脱分化过程中,淀粉含量有一个上升、下降、再上升的变化过程,对照中淀粉含量一直上升。     

Starch Synthesis Studies in Zea mays: II. Molecular Distribution of Radioactivity in Starch

The amylose and amylopectin fractions from kernel starch synthesized shortly after exposure of intact Zea mays L. plants to ¹⁴CO₂ had similar specific radioactivities (counts per min per mg of carbohydrate). In both fractions the radioactivity was distributed throughout the molecules. These data are consistent with a model in which the polysaccharides are synthesized in the matrix of the amyloplast followed by crystallization of the completed molecules onto the starch granule.