Lipids in plant tissue cultures IV. The characteristic patterns of lipid classes in callus cultures and suspension cultures

Lipids from callus cultures and suspension cultures of higher plants constitute 5 to 8% of the dry tissue's weight.The predominant lipid classes are the sterols, steryl esters, steryl glycosides and esterified steryl glycosides. Considerable amounts of a variety of sterylglycolipids, whose structures are not completely elucidated, are also present. Triglycerides and phospholipids occur in small proportions, whereas monogalactosyl diglycerides, digalactosyl diglycerides and sulfoquinovosyl diglycerides are present only in traces, if at all.β-Sitosterol is the predominant constituent sterol, stigmasterol and campesterol as well as a variety of as yet unidentified sterols occur in smaller proportions. The major constituent fatty acids are palmitic, oleic, linoleic and linolenic acids. Saturated very long-chain fatty acids are found in smaller proportions. Unusual fatty acids, such as epoxy acids, which occur in the seed lipids of certain plants, are not found in tissue cultures derived from these plants. Clucose and traces of galactose are the only sugars obtained by acid hydrolysis of the glycolipids occurring in plant tissue cultures.     

Lipids in plant tissue cultures. III. Very long-chain fatty acids in the lipids of callus cultures and suspension cultures

The lipids in plant tissue cultures contain in addition to the common saturated and unsaturated fatty acids even- and odd-numbered fatty acids having chain-lengths up to 26 carbon atoms.     

Ultrastructural study of Pneumocystis carinii in explant cultures of rabbit lung and in cultures with and without feeder cells

Pneumocystis carinii-parasitized lung explants were obtained from corticoid-treated rabbits and maintained in vitro. Twenty-one days after the beginning of explant cultures, the ultrastructural morphology of trophozoite, precyst and cyst forms was normal as compared to the in vivo ultrastructure of P. carinii from infected rabbit. However, after the 36th day, only altered forms of P. carinii were observed. Lung tissue showed only minor alterations. Intracytoplasmic lamellar inclusions were observed in type 2 alveolar cells from which they were released. While the total number of parasites increased approximately 4-fold from day 0 to day 41, trophozoite counts increased approximately 6 times. Pneumocystis cells from inocula and supernates of cultures with and without Vero cells showed important ultrastructural alterations.     

Cytological and ultrastructural changes induced in anther and isolated-microspore cultures in barley: Fe deposits in isolated-microspore cultures

To gain further insight into the role played by sporophytic anther tissues in the early stages of the androgenic process, we have compared the cytology and ultrastructure of barley embryogenic pollen grains obtained by anther culture with those obtained by isolated-microspore culture. The microspores behaved similarly in both culture systems but ultrastructural studies detected a significant difference: the presence of electron-dense deposits on the intine of embryogenic pollen grains generated by isolated-microspore culture compared to their absence in grains generated by anther culture. To discover the nature of these deposits, we applied proteinase K and EDTA treatments to ultrathin sections. We also subjected the deposits to X-ray microanalysis and found that they contained iron. Anthers and isolated microspores were cultured in media containing different concentrations of iron so as to evaluate the presence of these deposits on the intine. Deposits were not found in anther cultures at any iron concentration used or in microspore cultures when concentrations were lower than 40 mg/L. The Fe deposits on the intine appear to derive from an excess of Fe in the isolated-microspore culture medium which, if allowed to pass through the cell wall, could well be toxic to the embryogenic development of the microspores.     

Growth and respiration of Petunia hybrida cells in chemostat cultures: A comparison of glucose-limited and nitrate-limited cultures

Nitrate-limited and glucose-limited chemostat cultures of Petunia hybrida cells were compared at a specific biomass (+extracellular product) formation rate of 0.0042 C.mol/C.mol h. The composition of the biomass differed considerably in both culture types. The N/C (mol/mol) ratio in the biomass was almost four times lower in the nitrate-limited than in the glucose-limited cultures. On a dry weight basis (g/g DW) the biomass in the nitrate-limited cultures contained about 2.5 times less ions and protein N and about 2.5 times more carbohydrates than the biomass in the glucose-limited cultures. On a fresh weight basis (mmol/g FW) the biomass in nitrate-limited and glucose-limited cultures differed mainly in carbohydrate content. The yields of biomass on glucose and oxygen were generally higher in the nitrate-limited than in the glucose-limited cultures. Average values for these parameters were 0.27 C . mol biomass/C . mol glucose and 0.42 C . mol biomass/mol O(2) in the glucose-limited cultures and 0.34 C . mol biomass/C . mol glucose and 0.55 C . mol biomass/mol O(2) in the nitrate-limited cultures. On a C . mol basis the total respiration was about 25% and the maximally attainable cytochrome pathway activity (measured in the presence of hydroxamate) about 30% higher in the glucose-limited than in the nitrate-limited cultures. The maximally attainable activity of the alternative pathway (measured in the presence of KCN) was significantly lower in the glucose-limited cultures. On an organic N ( approximately protein) basis all respiratory parameters were significantly higher in the nitrate-limited cultures. In the presence of the respiratory uncoupler carbonyl cyanide p-trifluoromethoxy phenylhydrazone (FCCP) and excess glucose, cellular respiratory activity shows its maximal activity; under these conditions the total respiration increased more than 150% in the glucose-limited and only 30% in the nitrate-limited cultures. It is suggested that glucose-limited cultures are able to react more flexibly to changes in the environmental conditions than nitrate-limited cultures. (c) 1996 John Wiley & Sons, Inc.     

Lipids in plant tissue cultures. VII: Heterotrophic and mixotrophic cell cultures of Chenopodium rubrum

Mixotrophic cell cultures of Chenopodium rubrum were found to synthesize 5 to 33 times more monogalactosyldiacylglycerols and 5 to 16 times more digalactosyldiacylglycerols than heterotrophic ones. The monogalactosyldiacylglycerols and digalactosyldiacylglycerols from mixotrophic cultures contained higher levels of linolenic acid as compared to heterotrophic cultures. It is concluded that the active synthesis of these galactolipids with high levels of constituent linolenic acid is associated with the onset of photosynthesis in plant cell cultures, as is the case in intact plants.     

Callus cultures for phytometabolism studies: phytometabolites of 3-trifluoromethylphenol in Lemnaceae plants and callus cultures

Plant callus cultures have the potential to advance phytoremediation science by allowing study of cellular phytometabolism in absence of sorption, translocation, microbial degradation, and other phytoremediation processes; however, studies demonstrating the applicability of results from callus cultures to whole plants are limited. The aim of this study was to evaluate the feasability and applicability of using callus cultures to study phytometabolism. This aim was accomplished through evaluation of induction and growth of Lemnaceae callus cultures and comparison of phytometabolism in callus cultures and whole plants. Four out of eight published methods for callus culture of Lemnaceae successfully induced callus cultures that exhibited doubling times of 1.7 to 23 wks. Callus cultures and whole plants of Landoltia punctata and Lemna minor metabolized 3-trifluoromethylphenol (3-TFMP) through conjugation with glucopyranoside, malonyl-glucopyranoside, and glucopyranosyl-apiofuranoside. However, concentrations of metabolites were approximately 10 times less in callus cultures than in plants. While results demonstrated applicability of callus cultures results to whole plants, the low success rate of callus induction procedures, length of time required to produce substantial callus mass, and the low accumulation of metabolites in callus cultures may limit the feasibility of callus cultures for assessing phytometabolism.     

Organogenesis and tuberization in cultures of Dioscorea floribunda

Callus cultures were established from node and internode segments of Dioscorea floribunda Mart. & Gal. Both Murashige and Skoog's and modified White's medium supported callusing as well as organogenesis when supplemented with either 2,4-D or NAA in combination with BAP or Kn. On development of shoot primordia, calli were transferred to unsupplemented, half strength MS basal medium. This procedure led to the increase in formation of shoots. Several crops of shoots were obtained from single differentiating callus cultures by excising the shoots and subculturing the residual part. Seventy percent of plantlets survived rooting and transfer to soil.When they were maintained in half-strength MS basal medium and 0.5 mg1^-1 of NAA, 70% of plantlets formed aerial tubers at nodes. These tubers produced both roots and shoots and could be detached from the mother plant.     

Comparative study of human chromosome replication in primary cultures of embryonic fibroblasts and in cultures of peripheral blood leucocytes

By autoradiography with ³H-thymidine and ³H-deoxycytidine it is shown that chromosomes 1 and 16 in cultures of embryonic fibroblasts at the termination of the S period synthesise AT- and GC-rich DNA at different rats: in both chromosomes the labelling of AT-bases is more intensive. In leucocyte cultures both nucleotide pairs label equally in these chromosomes. Chromosomes 2, 3, 4–5 and 21–22 are labelled equally in both cultures with respect to AT-and GC-pairs. Fibroblasts and leucocytes differ in the relative intensity of DNA synthesis at the end of the S period: chromosomes 1,16 and 21–22 contain more label in the case of fibroblasts (chromosome 1 solely due to AT-pairs) and chromosome 4–5 in the case of leucocytes. Analysis of distribution of late label along chromosome 1 showed that in fibroblast cultures the pericentromeric regions of both arms are labelled more intensively in respect to both nucleotide pairs than in leucocyte cultures. Both in fibroblast and leucocyte cultures no significant distinctions in the distribution of AT-and GC-pairs along chromosome 2 were established. In fibroblast cultures the pericentromeric regions of both arms of chromosome 3 are labelled more intensively than other regions. In leucocyte cultures the pericentromeric region of the short arm of this chromosome is labelled with the same intensively as in fibroblasts, whereas in the pericentromeric region of the long arm the intensity of incorporation of labelled synthesis precursors decreases. — Analysis of results obtained in the present study together with data of previous studied (Slesinger et al., 1974; Lozovskaya et al., 1976; Lozovskaya et al., 1977) shows that differences between the two types of cells in the intensity of late ³H-thymidine labelling in the C-heterochromatin regions of chromosomes 1 and 16 may be explained both by variation of replication time in leucocytes as compared with fibroblasts and by variation of the content of AT- rich DNA. Differences observed in other chromosomes are probably due to different times of replication of these chromosomes in leucocytes and fibroblasts. — Thus, the process of cell system differentiation involves not only differential activity of the genome (the main mechanism) that is connected with differences in the replication time of chromosomes and of their regions but also variation of the quantity of genetic material.