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.     

Organogenesis in pepper tissue cultures

Knowledge concerning in vitro growth and developmental responses of bell and chile peppers (Capsicum annuum L.) has been limited. Shoot and root organogenesis in cultures of seedling explants was restricted to primary cultures or those less than three months old under 12-and 16-h photoperiod at 25°C. Shoot organogenesis was extended to 5 months under continuous light at 25°C, and to 8 months under continuous light at 28.5°C. Murashige and Skoog basal media containing 0.05mg/l each of IAA and BA promoted shoot elongation and rooting of some explant sources, while 0.05-4 mg/l IAA with 10–50 mg/l BA promoted adventitious shoot bud formation. Glucose was superior to sucrose as the carbon source. Leaf discs collected from greenhouse-grown plants regenerated shoots for at least 2 months. Incubation environment, carbon source, explant source, growth regulator treatment and passage number were not independent variables as demonstrated by statistical analysis. The plant regeneration techniques described here have useful but limited applications, not extending to unorganized callus or cell suspension cultures.Journal article no. 1151 of the New Mexico Agricultural Experiment Station.     

Synchronous cultures in cytodifferentiation studies

Summary This paper summarizes work done on the induction of the cytodifferentiation of a soil amoeba. The differentiation involves the synthesis of two cyst walls and results in a dormant cell called a cyst. This cytodifferentiation is called encystment. The following observations result from work on synchronously differentiating cultures. The differentiation is under genetic control, is induced by starvation, and occurs only after an induction period. Massive erosion of intracellular components occurs prior to and during the differentiation and provides the materials for the induction and for the syntheses of the differentiation products. The effects of various inhibitors on this induction are also presented. From results obtained, mainly with FUdR and mitomycin C, the following tentative conclusions are drawn: encystment is normally induced when cells are stalled in the terminal portion of the deoxyribonucleic acid (DNA) synthetic period. Induction of dormancy probably involves two steps, the unwrapping or loosening of material surrounding the differentiation genes, followed by a specific activation. Much of the work on inhibitors was performed during the tenure of PHS-NIH Special Fellowship 1-F3-GM-28567 to the author. Experiments were performed at the Carlsberg Foundation Biological Institute in Copenhagen, Denmark, and will be reported in detail in the Comptes Rendus des Travaux du Laboratorie Carlsberg.     

Indole derivatives in Azotobacter cultures

В культурах азотобактера и его почвениых препатах содержатся ?изиологически активные вещества, частькоторых термостабильна. Количество ?изиологически активных веществ зависит от штамма азотобактера и от возраста культур. Особое внимание посRящалось гетероауксину. С помощью разделительной хроматогра?ии на бумаге и биологического теста было доказано присутствие β-индолуксусной кислоты и еще однго, пока не иденти?ицированног о, ?акгора роста. β-индолуксусная кислота в старых культурах превращается в индол-З-карбоновую кислоту. Полученные результаты обсуждаются с точки зрения влияния культур азотобактера на рост растений.     

Cell-mass maximization in fed-batch cultures

Complete solutions are provided for cell-mass maximization for free and fixed final times and constant and variable yields. The optimal feed rate profile is a concatenation of maximum, minimum and singular feed rates. The exact sequence and duration of each feed rate depends primarily on the initial substrate concentration, and degenerate cases arise due to the magnitude constraint on the feed rate and the length of final time t _f. When the final time is free and not in the performance index, it is infinite for constant yield so that any form of feed rate leads to the same amount of cells, while for variable yield the singular feed rate is exponential and maximizes the yield. For fixed final time the singular feed rate for constant yield is exponential and maximizes the specific growth rate by maintaining the substrate concentration constant, while for variable yield, it is semi-exponential and the substrate concentration starts near the maximum specific growth rate and moves toward the maximum yield. A simple sufficient condition for existence of singular feed rate requires an existence of a region bounded by the maxima of specific growth and cellular yield. Otherwise, the optimal feed rate profile is a bang-bang type and the bioreactor operates in batch mode.     

Dialysis cultures

Dialysis techniques are discussed as a means for effective removal of low-molecular-mass components from fermentation broth to reach high cell density. Reactor systems and process strategies, the relevant properties of membranes and examples for high-density fermentation with dialysis, and problems related to scale-up are addressed. The dialysis technique has turned out to be very efficient and reliable for obtaining high cell densities. As in dialysis processes the membranes are not perfused, membrane clogging is not a problem as it is for micro- and ultrafiltration. By applying a “nutrient-split” feeding strategy, the loss of nutrients can be avoided and the medium is used very efficiently. The potential of dialysis cultures is demonstrated on the laboratory scale in a membrane dialysis reactor with an integrated membrane and in reactor systems with an external dialysis loop. In dialysis cultures with different microorganisms (Staphylococci, Escherichia coli, extremophilic microorganisms, Lactobacilli) the cell densities achieved were up to 30 times higher than those of other fermentation methods. The technique enables high cell densities to be attained without time-consuming medium optimization. For animal cell cultures the concept of a fixed bed coupled with dialysis proved to be very effective. Received: 24 March 1998 / Received revision: 18 June 1998 / Accepted: 19 June 1998