Tissue,cell culture and micropropagation of Mandevilla velutina,a natural source of a bradykinin antagonist

Leaf, stem and root explants of Mandevilla velutina were cultured in vitro and produced vigorous callus in LS basal medium containing one auxin (2,4-D or NAA) plus BAP. Calli can be subcultured indefinitely with vigorous growth. Subculture of calli to NAA (1.0 mg/l) plus BAP (5.0 mg/l) caused profuse regeneration of shoots. Isolated shoots were rooted in basal medium plus NAA (5.0 mg/l) or IBA (8.0 mg/l). Rapidly growing cell suspensions can be easily obtained from friable callus cultured in liquid medium.Abbreviations LS Linsmaier & Skoog - 2,4-D 2,4 dichlorophenoxi-acetic acid - NAA -naphthalene-acetic acid - GA₃ gibberellic acid - IAA indole-3-acetic acid - BAP 6-benzylaminopurine - IBA indole-3-butyric acid     

Somaclonal variation rate evolution in plant tissue culture: Contribution to understanding through a statistical approach

Summary In order to better understand somaclonal variant rate evolution in plant tissue culture, a statistical approach has been adopted. According to this approach, the variant percentage could be calculated by: %V=[1−(1−p) ⁿ ]×100, where %V is the percentage of variant, p the probability of variation and n the number of multiplication cycles. A numerical estimation was performed to characterize the variance of this function. It has been demonstrated that a wide scale of variance is associated with ‘%V’, due to the occurrence of variations after a variable number of multiplication cycles in the different lines of culture. Two main conclusions can be drawn from this model: (1) a variant rate increase can be expected as an exponential function of the number of multiplication cycles; (2) after a given number of multiplication cycles, variable off-types percentages can be expected. Due to the complexity of biological systems, this statistical approach could obviously not be applied directly for the calculation and forecasting of variant rates in tissue culture. However, this approach results in a better understanding of two apparently confusing experimental features often reported in tissue culture: the increase of the variant rate as a function of the length of the culture period on the one hand, and, on the other hand, the observations of different variant rates among lines cultured for the same lengths of time under strietly identical culture conditions. This approach also underlined that the comparison of somaclonal variant percentage between batches of plants from different in vitro treatments could be, in some cases, insufficient for ascertaining a difference of variability generated by tissue culture.     

The role of acyl carrier protein isoforms from Cuphea lanceolata seeds in the de-novo biosynthesis of medium-chain fatty acids

To investigate the role of acyl carrier protein (ACP) in determining the fate of the acyl moieties linked to it in the course of de-novo fatty acid biosynthesis in higher plants, we carried out in vitro experiments to reconstitute the fatty acid synthase (FAS) reaction in extracts of spinach (Spinaciaoleracea L.) leaves, rape (Brassicanapus L.) seeds and Cuphea lanceolata Ait. seeds. The action of two major C. lanceolata ACP isoforms (ACP 1 and ACP 2) compared to ACP from Escherichia coli was monitored by saponification of the corresponding FAS products with subsequent analysis of the liberated fatty acids by high-performance liquid chromatography. In a second approach the preference of the medium-chain acyl-ACP-specific thioesterase (EC 3.1.2.14) of C. lanceolata seeds for the hydrolysis of acyl-ACPs prepared from the three ACP types was investigated. Both ACP isoforms from C. lanceolata seeds supported the synthesis of medium-chain fatty acids in a reconstituted FAS reaction of spinach leaf extracts. Compared to the isoform ACP 1, ACP 2 was more effective in supporting the synthesis of such fatty acids in the FAS reaction of rape seed extracts and caused a higher accumulation of FAS products in all experiments. No preference of the medium-chain thioesterase for one specific ACP isoform was observed. The results indicate that the presence of ACP 2 is essential for the synthesis of decanoic acid in C. lanceolata seeds, and its expression in the phase of accumulation of high levels of this fatty acid provides an additional and highly efficient cofactor for stimulating the FAS reaction. Received: 23 June 1997 / Accepted: 23 October 1997     

蝴蝶兰的组织培养和快速繁殖

通过诱导残败花梗上的休眠芽萌发,以萌发的幼叶和去茎尖的茎段为外植体进行组织培养,建立了蝴蝶兰(Phalaenopsis amabilis Bl.)的无菌繁殖体系,并筛选出最佳培养基组成.诱导休眠芽萌发的最佳培养基为不加任何激素的MS0培养基;原球茎诱导的适宜培养基为MS 3.0 mg·L-1 6-BA 0.5 mg·L-1 ZT 30 mg·L-1柠檬酸和MS 5.0 mg·L-1 6-BA 30 mg·L-1柠檬酸 30%椰乳(CM),其中茎段的诱导效果明显优于叶片,诱导率达95%;诱导无菌苗生根的最适培养基为1/4 MS 1.0 mg·L-1 6-BA 0.1 mg·L-1 NAA,生根率可达79%.     

Beta-ketoacyl-acyl carrier protein synthase IV: a key enzyme for regulation of medium-chain fatty acid synthesis in Cuphea lanceolata seeds

With the aim of elucidating the mechanisms involved in the biosynthesis of medium-chain fatty acids in Cuphea lanceolata Ait., a crop accumulating up to 90% decanoic acid in seed triacylglycerols, cDNA clones of a beta-ketoacyl-acyl carrier protein (ACP) synthase IV (clKAS IV, EC 2.3.1.41) were isolated from C. lanceolata seed embryos. The amino acid sequence deduced from clKAS IV cDNA showed 80% identity to other plant KAS II-type enzymes, 55% identity towards plant KAS I and over 90% towards other Cuphea KAS IV-type sequences. Recombinant clKAS IV was functionally overexpressed in Escherichia coli, and substrate specificity of purified enzyme showed strong preference for elongation of short-chain and medium-chain acyl-ACPs (C4- to C10-ACP) with nearly equal activity. Further elongation steps were catalysed with distinctly less activity. Moreover, short- and medium-chain acyl-ACPs exerted a chain-length-specific and concentration-dependent substrate inhibition of clKAS IV. Based on these findings a regulatory mechanism for medium-chain fatty acid synthesis in C. lanceolata is presented.     

Inflorescence culture of wheat-Agropyron hybrids: Callus induction,plant regeneration,and potential in overcoming sterility barriers

Segments of young inflorescences of Triticum aestivum cv. Chinese Spring (CS), its F₁ hybrids with Agropyron trachycaulum and A. scirpeum and backcross derivatives with A. yezoense, A. intermedium and A. junceum, and of a A. yezoense x T. aestivum cv. Wichita hybrid were cultured. Different parts of young spikelets of A. trachycaulum x CS F₁ and A. yezoense x Wichita F₁ 's were also cultured. Percent callus induction was lower in wheat than in the wheat-Agropyron hybrids or backcross derivatives. Percent callus induction from different organs in both hybrids was in the descending order of whole spikelet, spikelet without glumes, rachis, and glumes. No plants could be regenerated from calli of wheat and backcross derivatives except those of CS x A. intermedium combination. Callus induction in hybrids varied from 54 to 84% and plant regeneration from 14 to 31%. The regenerants required no vernalization. Variants including one with top-dense spikes and another with elongated spikelets were recovered. Out of eight A. trachycaulm x CS hybrid regenerants, one had anthers and stigma as opposed to neutral flowers of the original hybrid.     

Effect of exercise and medium-chain fatty acids on postprandial lipemia.

The purpose of this study was to evaluate the effect of medium-chain triglycerides (MCT) with and without exercise on postprandial lipemia (PPL). Subjects were 25 young men and women. Each subject performed three trials: 1) control (fat meal only, 1.5 g fat/kg) 2) MCT (substitution of MCT oil, 30% of fat calories), and 3) MCT + Ex (exercise 12 h before the MCT meal). Before each trial, the subject underwent consistent dietary preparation. Blood was collected on 2 separate days for baseline measurements of postheparin lipases and, in each trial, at 0 h (premeal), at 2, 4, 6, and 8 h after the fat meal for triglycerides and cholesterol ester transfer protein (CETP), and at 8 h for postheparin lipoprotein lipase (LPL) and hepatic lipase activities (HL). ANOVA indicated that the partial substitution of MCT oil to the fat meal did not affect the PPL response. However, the PPL was significantly lower after the MCT + Ex trial vs. the other trials. LPL activity was significantly elevated after all trials compared with baseline, whereas HL was lower in the MCT + Ex trial only. CETP mass was significantly lower at 4 and 8 h than 0 h during all trials but relatively higher in the MCT + Ex trial vs. the nonexercise trials. These results suggest that MCT does not affect the TG response to a fat meal. LPL and CETP are affected by a fat meal with or without exercise, but HL is affected only when exercise is included.     

Pigment and isozyme variation in aspen shoots regenerated from callus culture

Pigment as well as isozyme variations were observed among aspen (Populus tremuloides Michx.) plants regenerated from callus cultures. Out of more than 600 plantlets, two chimeric plants (one with green base and two albino shoots and the other with an albino shoot) were produced. Callus derived from albino shoots produced albino as well as chimeric plants when transferred to shoot inducing medium. Isozyme patterns of 119 plants were examined by starch gel electrophoresis. Thirty plants showed variation in shikimic dehydrogenase isozyme and 41 in isocitric dehydrogenase. Variation was also observed in malate dehydrogenase and phosphoglucose isomerase. No variation was seen in 6-phosphogluconate dehydrogenase. Pigment variation was not associated with any isozyme changes.Abbreviations BA 6-benzyladenine - IBA indole-3-butyric acid - GD Gresshoff & Doy medium - WPM woody plant medium - SKD shikimic dehydrogenase - IDH isocitric dehydrogenase - MDH malate dehydrogenase - PGI phosphoglucose isomerase - 6-PGD 6-phosphogluconate dehydrogenase     

圆柏组织培养繁殖研究

用5年生圆柏幼嫩茎段为外植体,研究植物生长调节剂对试管苗的调控作用及增殖效果,结果表明:在1/2MS+BA0.5mg/L+NAA0.5mg/L+IBA0.2mg/L的培养基上,试管苗分化率为95.0%,生长发育良好,在MS+BAI.omg/L+NAA0.cling/L的培养基上,增殖效果较好。     

食用仙人掌的组织培养

在优良蔬莱品种——米邦塔的推广过程中，采用组织培养的方法，即使在种源较少的情况下在有限的时间内可以获得大量的优质种苗。     

One-step quantitative extraction of medium-chain and long-chain fatty acids from aqueous samples

Medium-chain (C(6) and longer) fatty acids, as well as 12-hydroxystearic and long-chain fatty acids, can be quantitatively extracted into toluene and titrated in the toluene phase with tetrabutylammonium hydroxide. The method may be useful in determinations of fecal and serum fatty acids and of the products of lipolysis.     

红掌组织培养与快速繁殖

红掌叶片在新代培养基上的分化能力与品种和叶片部位有关。组织培养试验表明,最佳诱导培养基为改良Nitsch (NH₄NO₃ 200mg/L)+6-BA 1.0mg/L+2,4-D 0.1mg/L;芽增殖培养基Nitsch (NH₄NO₃720mg/L)+6-BA 0.5mg/L;生根培养基为Nitsch (NH₄NO₃720mg/L)。     

Clonal micropropagation of six selected half-sibling families of Pinus pinea and somaclonal variation analysis

Organogenesis response of six selected half-sibling families of stone pine (Pinus pinea L.) has been evaluated, showing genotype-dependent behaviour. The caulogenic phase was characterized by high values of Survival and Organogenesis, while the rooting phase (the bottleneck of many coniferous species) showed great variability among families. Provenance influence was also studied, and the rhizogenesis protocol was optimized for the selected families. The highest values were obtained with family 36, with 100% of Organogenesis, a Bud Formation Capacity (BFC) Index of 6.54 and 38.44% of Rooted Shoots; on the other hand, family 61 presented the worst results, with 83.64% Organogenesis, a BFC Index of 3.01 and a 29.69% Rooting Rate. According to these results, both families will be used in further experiments looking for the underlying bases of the different organogenic behaviour between both families under the same culture conditions. In addition to this, and for the first time in this species, random amplified polymorphism DNA (RAPD) analysis has been carried out to determine whether somaclonal variation had occurred. The results suggested an absence of variation during the whole in vitro process, although more thorough studies would be required for a conclusive answer.     

Consistent and Heritable Alterations of DNA Methylation Are Induced by Tissue Culture in Maize

Plants regenerated from tissue culture and their progenies are expected to be identical clones, but often display heritable molecular and phenotypic variation. We characterized DNA methylation patterns in callus, primary regenerants, and regenerant-derived progenies of maize using immunoprecipitation of methylated DNA (meDIP) to assess the genome-wide frequency, pattern, and heritability of DNA methylation changes. Although genome-wide DNA methylation levels remained similar following tissue culture, numerous regions exhibited altered DNA methylation levels. Hypomethylation events were observed more frequently than hypermethylation following tissue culture. Many of the hypomethylation events occur at the same genomic sites across independent regenerants and cell lines. The DNA methylation changes were often heritable in progenies produced from self-pollination of primary regenerants. Methylation changes were enriched in regions upstream of genes and loss of DNA methylation at promoters was associated with altered expression at a subset of loci. Differentially methylated regions (DMRs) found in tissue culture regenerants overlap with the position of naturally occurring DMRs more often than expected by chance with 8% of tissue culture hypomethylated DMRs overlapping with DMRs identified by profiling natural variation, consistent with the hypotheses that genomic stresses similar to those causing somaclonal variation may also occur in nature, and that certain loci are particularly susceptible to epigenetic change in response to these stresses. The consistency of methylation changes across regenerants from independent cultures suggests a mechanistic response to the culture environment as opposed to an overall loss of fidelity in the maintenance of epigenetic states.     

小叶锦鸡儿的组织培养和快速繁殖

选用小叶锦鸡儿茎段为材料进行组织培养和快速繁殖,结果表明,芽诱导的最适培养基是MS基本培养基附加6-BA0．5mg／L和IAA0.01mg／L,最适生根培养基是1／2MS基本培养基附加IAA0．5mg／L,诱导生根率达86％．再生植株移人大田,15d后成活率在98%以上。     

Determinants of intestinal mucosal uptake of short- and medium-chain fatty acids and alcohols

Uptake rates across the jejunal brush border have been measured for water-soluble fatty acids and alcohols and analyzed to determine the relative roles of the unstirred water layer and the lipid cell membrane as determinants of the intestinal absorptive process. Initial studies involving measurement of time courses of electrical transients developed across the intestine exposed to poorly permeant solute molecules showed no anomalous discrimination of probe molecules of different size or charge. This finding suggests that the diffusion barrier in the intestine can be considered as an unstirred water layer. Next, uptake rates of fatty acid were found to be linear with respect to concentration of the test solute, demonstrated no competitive inhibition or contralateral stimulation, had low temperature dependency, and were insensitive to metabolic inhibition, indicating that uptake proceeds by passive diffusion. Passive permeability coefficients, *P, varied from 22 +/- 1.4 to 395 +/- 9.2 nmoles.min(-1).100 mg(-1).mm(-1) for the saturated fatty acids 2:0 through 12:0 and from 119 +/- 3.3 to 581 +/- 45.2 for the saturated alcohols 6:0 through 10:0. Vigorous stirring of the bulk buffer solution enhanced *P values in direct proportion to chain length while the presence of bile acid micelles depressed apparent permeability coefficients in proportion to fatty acid chain length. These results demonstrate that uptake of short-chain fatty acid monomers is rate limited by the lipid cell membrane but diffusion through the unstirred water layer becomes increasingly rate limiting as the chain length increases. It is also possible to conclude from these data that diffusion through the unstirred water layer becomes totally rate limiting for uptake of long-chain fatty acid monomers of physiological importance.     

魔芋属植物组织培养与遗传转化研究进展

本文对近20年来魔芋生物技术研究取得的进展进行了系统的回顾分析。组织培养是当前魔芋生物技术研究的主要内容,魔芋离体植株再生以器官发生途径为主,包括不定芽和拟球茎两种途径,后者是当前研究的热点。利用组织培养进行有用突变体的筛选和种质资源的保存也取得了一些有价值的结果。以抗病和品质改良为目的的转基因技术取得了较快发展,如抗病基因和抗除草剂基因等已实现成功转化。此外,本文还分析了魔芋生物技术研究中存在的主要问题并提出了相应的对策。     

桂黔吊石苣苔的组织培养与快速繁殖

以桂黔吊石苣苔的茎段和叶片为外植体材料,对桂黔吊石苣苔进行离体培养与快速繁殖技术研究.结果表明：桂黔吊石苣苔茎段腋芽可直接诱导萌发,在 MS＋6-BA 1．0 mg·L-1＋IBA 0．1 mg·L-1培养基上萌发率最高,达75％;适宜的继代增殖及壮苗培养基为1/2MS＋NAA0．2 mg·L-1,繁殖系数为6．0/60 d,继代培养中茎段外植体可以诱导出愈伤组织,但诱导率较低,未能进一步分化成苗;最佳生根培养基为1/2MS＋6-BA 0．2 mg·L-1＋NAA 0．8 mg·L-1＋AC 0．1％＋香蕉5％,生根率达100％;在大棚中模拟桂黔吊石苣苔自然生境对生根苗进行移栽,成活率在95％以上.