Aeroponics for the culture of organisms, tissues and cells

Characteristics of aeroponics are discussed. Contrast is made, where appropriate, with hydroponics and aero-hydroponics as applies to research and commercial applications of nutrient mist technology. Topics include whole plants, plant tissue cultures, cell and microbial cultures, and animal tissue cultures with regard to operational considerations (moisture, temperature, minerals, gaseous atmosphere) and design of apparati.     

Possible evidence for novel metabolism of nitrogen gas by a green alga

We report the isolation of a cukaryotic green alga ( Chlorella , strain WPI-2) which accumulates large stores of nitrogen (N) during growth in N-free medium and seems to incorporate¹⁴N₂, yet does not reduce acetylene to ethylene. Total N accumulation during growth on N-free medium and in gases free of combined N was measured by three methods: Kjeldahl, oxidative pyrolysis via chemiluminescence (Antek N analyzer), and Dumas (Coleman N analyzer). Increases in N ranging from 22–64%± 1% were observed. Isotope dilution studies using cells labelled with ¹⁵NO ₃- and then shifted to ¹⁴N₂ in N-free medium showed dilution of the ¹⁵N isotope by ¹⁴N from 5.67 to 5.32%± 0.05%. Using a variety of conditions, we were unable to demonstrate the reduction of acctylene to ethylene by WPI-2, although diazotrophic cyanobacteria gave positive results. Although the data on WPI-2 are not conclusive in establishing this alga as a diazotroph, the data do suggest that within the Chlorophyceae there may exist a novel form of nitrogen gas metabolism.     

Nitrous oxide production by cyanobacteria

Evidence is presented here that axenic cultures of Nostoc spp., Aphanocapsa (PCC 6308), and Aphanocapsa (PCC 6714) but not Anacystis nidulans R-2 (PCC 7942) produce N₂O and ammonia when grown on nitrite. The data suggest that the cyanobacteria produce N₂O by nitrite reduction to ammonia.Nonstandard abbreviations DCMU 3-(3,4-dichlorophenyl)-1,1-dimethyl urea - NIR nitrite reductase     

Multiple fruiting of the edible mushroomCoprinus cinereus from explants of the stipe

Summary Carpophores were developed on defined medium from explants of stipes produced in the dark using an expansionless mutant (no. 190) ofCoprinus cinereus. Explants taken from stipes within 24 h of formation developed multiple fruit within 3–12 days without formation of mycelia. Fruiting levels were affected by stipe age (24 h), medium composition, explant size, and polarity of the explant on fruiting medium. This method offers a new tool for developmental studies and may also be of use to commercial mushroom growers.     

Non-lethal secondary product release from transformed root cultures of Beta vulgaris

Transformed root tissue of Beta vulgaris (Detroit Dark Red) was permeabilized to stimulate the release of intracellularly stored betanin without adverse affects on tissue viability as measured by biomass accumulation. Product release of up to 15% (w/w) was achieved by heat treatment at 42°C for 45 min with minimal effect on viability. Higher levels of product release were obtained with increasing temperature and exposure, but at the expense of viability. Viability was measured by comparing dry weight increases of permeabilized tissue 3 days after treatment vs non-permeabilized tissue over the same time interval. Recovery of heat-treated tissue was improved by addition of CaCl₂ (20 mm for 10 min) post-heat treatment. Betanin release up to 15% was also obtained at ambient temperature (25°C) by addition of up to 20 mm (NH₄)₂SO₄ in the presence of 1 mm ethylenediaminetetraacetic acid (EDTA). Correspondence to: A. A. DiIorio     

Variation in heat shock proteins within tropical and desert species of poeciliid fishes

The 70-kilodalton heat shock protein (hsp70) family of molecular chaperones, which contains both stress-inducible and normally abundant constitutive members, is highly conserved across distantly related taxa. Analysis of this protein family in individuals from an outbred population of tropical topminnows, Poeciliopsis gracilis, showed that while constitutive hsp70 family members showed no variation in protein isoforms, inducibly synthesized hsp70 was polymorphic. Several species of Poeciliopsis adapted to desert environments exhibited lower levels of inducible hsp70 polymorphism than the tropical species, but constitutive forms were identical to those in P. gracilis, as they were in the confamilial species Gambusia affinis. These differences suggest that inducible and constitutive members of this family are under different evolutionary constraints and may indicate differences in their function within the cell. Also, northern desert species of Poeciliopsis synthesize a subset of the inducible hsp70 isoforms seen in tropical species. This distribution supports the theory that ancestral tropical fish migrated northward and colonized desert streams; the subsequent decrease in variation of inducible hsp70 may have been due to genetic drift or a consequence of adaptation to the desert environment. Higher levels of variability were found when the 30- kilodalton heat shock protein (hsp30) family was analyzed within different strains of two desert species of Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In both cases the distribution of hsp30 isoform diversity was similar to that seen previously with allozyme polymorphisms.      

N2O Evolution by Green Algae

Evidence is presented here that axenic cultures of Chlorella, Scenedesmus, Coelastrum, and Chlorococcum spp. evolve N₂O when grown on NO₂⁻, showing that the Chlorophyceae are a source of N₂O in aquatic systems.     

Variations in short term products of inorganic carbon fixation in exponential and stationary phase cultures of Aphanocapsa 6308

Aphanocapsa 6308 metabolizes both NaHCO₃ and Na₂CO₃. The short term incorporation (5-s) metabolic pattern and the patterns of incorporation of bicarbonate for exponential versus stationary phase cultures differ, however. Cells were equilibrated for 10 min in air and distilled water prior to injection of either NaH¹⁴CO₃ at pH 8.0, or Na₂ ¹⁴CO₃ at pH 11.0. Hot ethanol extracts were analyzed via paper chromatography and autoradiography for products of CO₂ fixation. At 5 s, malate (51.5%) predominates slightly as a primary bicarbonate fixation product over 3-phosphoglycerate (40.3%); 3-phosphoglycerate is the primary product of carbonate fixation. At 60 s, the carbonate and bicarbonate labelling patterns are similar. Cells in stationary phase fix in 5 s a greater proportion of bicarbonate into malate (36% vs. 14% for 3-phosphoglycerate) than do cells in exponential growth. Likewise, 60 s incorporations show a large amount of bicarbonate fixed into aspartate (30.9%) in stationary phase cells over that of exponential phase (11.6%). These data suggest an operative C₄ pathway for purposes not related to carbohydrate synthesis but rather as compensation for the incomplete tricarboxylic acid cycle in cyanobacteria. The enhancement of both aspartate fixation and CO₂ fixation into citrulline in stationary phase correlates with an increase in cyanophycin granule production which requires both aspartate and arginine.Nonstandard Abbreviations 3-PGA 3-phosphoglyceric acid - TCA tricarboxylic acid     

The gas vacuole membrane of Microcystis aeruginosa. A partial amino acid sequence.

The primary structure and hydrophobicity of the gas vacuole membrane were investigated in order to determine if this simple membrane, containing only one protein and no lipid, typifies integral membrane proteins. Peptides obtained by trypsin digestion and N-bromosuccinimide treatment of the gas vacuole protein were sequenced. Two aspects of the sequence analysis are of interest: a long stretch of 15 aliphatic residues (in peptide NPT), and a thrice repeating octapeptide. The location of the aliphatic portion of peptide NPT between the amino and carboxyl termini of the gas vacuole protein sequence means that the protein is amphipathic i.e., the protein has stretches of primarily either nonpolar residues or polar residues in its sequence. Based on this and a comparison of the relative polarities of gas vacuole protein with other integral membrane proteins, the gas vacuole protein is an integral membrane protein. The presence of the repeating octapeptide in the sequence suggests that it may serve as a structural building block for the membrane. Based on the presence of the aliphatic sequence in peptide NPT, a functional model for the gas vacuole membrane was proposed. To allow gas to pass through the membrane without a conformational change in the protein, it is speculated that either the gas must pass through the intermolecular space in the protein or through hydrophobic pores.