Genomic DNA extraction from<Emphasis Type="Italic">Victoria amazonica</Emphasis>

DNA extraction is difficult in many plants because of metabolites that interfere with DNA isolation procedures and subsequent applications such as DNA restriction, amplification, and cloning. We developed the first reliable and efficient method for isolatingVictoria amazonica genomic DNA that is free from polysaccharides and polyphenols. This protocol uses 1.5 M NaCl, 2% polyvinylpyrrolidone (PVP) (Mr 1000), 5% mercaptoethanol, 0.12% sodium sulfite, and an incubation at 65°C for 4 h. The purity of isolated genomic DNA was confirmed by means of high-performance liquid chromatography (HPLC) profile and spectrophotometric analyses (A_260/230 ratio of 1.836, A_260/280 of 1.842). DNA was obtained in the amount of 387 μg per gram of leaf material, and it proved amenable to restriction digestion.     

Efficient isolation of high quality nucleic acids from different tissues of <Emphasis Type="Italic">Taxus baccata</Emphasis> L.

Improved and efficient methods were developed for isolating high quality DNA and RNA from different sources of Iranian Yew (Taxus baccata L.). The methods were based on CTAB extraction buffer added with high levels of polyvinylpyrrolidone (PVP) and β-mercaptoethanol to properly remove polysaccharides and prevent oxidation of phenolics. The pellets obtained by ethanol precipitation were washed only with Chloroform: isoamyl alcohol (24:1). So, we could successfully eliminate the dangerous phenol/chloroform extraction steps from the isolation procedure. Both spectrophotometric (A₂₆₀/A₂₈₀ and A₂₆₀/A₂₃₀ ratios) and agarose electrophoresis analysis of isolated nucleic acids (DNA and RNA) indicated good results. DNA with the average yield of 100–300 μg/g leaf and stem tissue and total RNA with an average yield of 20–30 μg/g cell culture and 80–100 μg/g leaf and stem tissue of Iranian yew could be obtained. Successful amplification of pam and pds by PCR and RT-PCR, showed the integrity of isolated DNA and RNA, respectively.     

Leaf phosphorus influences the photosynthesis–nitrogen relation: a cross-biome analysis of 314 species

The ecophysiological linkage of leaf phosphorus (P) to photosynthetic capacity (A _max) and to the A _max–nitrogen relation remains poorly understood. To address this issue we compiled published and unpublished field data for mass-based A _max, nitrogen (N) and P (n = 517 observations) from 314 species at 42 sites in 14 countries. Data were from four biomes: arctic, cold temperate, subtropical (including Mediterranean), and tropical. We asked whether plants with low P levels have low A _max, a shallower slope of the A _max–N relationship, and whether these patterns have a geographic signature. On average, leaf P was substantially lower in the two warmer than in the two colder biomes, with the reverse true for N:P ratios. The evidence indicates that the response of A _max to leaf N is constrained by low leaf P. Using a full factorial model for all data, A _max was related to leaf N, but not to leaf P on its own, with a significant leaf N ×  leaf P interaction indicating that the response of A _max to N increased with increasing leaf P. This was also found in analyses using one value per species per site, or by comparing only angiosperms or only woody plants. Additionally, the slope of the A _max–N relationship was higher in the colder arctic and temperate than warmer tropical and subtropical biomes. Sorting data into low, medium, and high leaf P groupings also showed that the A _max–N slope increases with leaf P. These analyses support claims that in P-limited ecosystems the A _max–N relationship may be constrained by low P, and are consistent with laboratory studies that show P-deficient plants have limited ribulose-1,5-bisphosphate regeneration, a likely mechanism for the P influence upon the A _max–N relation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Modulation of DNA intercalation by resveratrol and genistein

Time correlated Single Photon Counting study (TCSPC) was performed for the first time to evaluate the effect of resveratrol (RES) and genistein (GEN) at 10–100 μM and 10–150 μM respectively, in modulating the DNA conformation and the variation induced due to intercalation by the dyes, ethidium bromide (EtBr) and acridine orange (AO). It is demonstrated using UV-absorption and fluorescence spectroscopy that RES and GEN, at 50 μM and 100 μM respectively can bind to DNA resulting in significant de-intercalation of the dyes, preventing their further intercalation within DNA. Hyperchromicity with red/blue shifts in DNA when bound to dyes was reduced upon addition of RES and GEN. DNA-dependent fluorescence of EtBr and AO was quenched in the presence of RES by 87.97% and 79.13% respectively, while similar quenching effect was observed for these when interacted with GEN (85.52% and 83.85%). It is found from TCSPC analysis that the higher lifetime component or constituent of intercalated dyes (τ₂, A ₂) decreased with the subsequent increase in smaller component or constituent of free dye (τ₁, A ₁) after the interaction of drugs with the intercalated DNA. Thus these findings signify that RES and GEN can play an important role in modulating DNA intercalation, leading to the reduction in DNA-directed toxicity.     

Spatial and Temporal Genetic Variation of Green Mussel, Perna viridis in the Gulf of Thailand and Implication for Aquaculture

The culture of green mussel (Perna viridis) in the Gulf of Thailand depends on natural spat which are believed to come from spawning grounds adjacent to major river mouths. In the present paper, genetic diversity of spatial and temporal populations of green mussel in the Gulf of Thailand was investigated using five microsatellite loci. The results showed moderate genetic variation of all 11 populations (averaged number of alleles per locus, A = 10.4–12.2; effective number of alleles per locus, A _e = 5.36–6.59; mean allelic richness, A _r = 10.23–12.06; observed heterozygosity, H _o = 0.52–0.63, and expected heterozygosity, H _e = 0.66–0.73) without significant differences among populations. No sign of bottleneck or genetic disequilibrium was observed. Genetic differentiation among spatial populations was low (F _ST = 0.0046, CI_0.95 = 0.0020–0.0083 for the samples collected in January, 2007, and F _ST = 0.0088, CI_0.95 = 0.0010–0.0162 for the samples collected in July, 2007) while temporal variation was significant as revealed by the analysis of molecular variance. Multidimensional scaling separated temporal population groups with minor exception. The assignment test revealed that most of the recruits were from other populations.     

Size distribution analysis of recombinant adenovirus using disc centrifugation

Recombinant adenovirus is one of the primary vectors for human gene therapy. However, the aggregation of unstable virus has been a recurring problem during the production of purified virus for human therapeutics. To facilitate the development of a robust manufacturing process for recombinant adenovirus vectors, a convenient and reliable size distribution analytical assay is necessary and we demonstrate here that disc centrifuge sedimentation is applicable to this purpose. Using the disc centrifuge system and the line start method, the assay can provide particle size distribution of adenovirus samples within 30 min. The assay can detect virus concentrations down to 0.01% (w/v) or 3 × 10¹¹ particles per ml. The apparent hydrodynamic diameter of recombinant adenovirus was determined to be about 0.063 μm. Furthermore, the disc centrifuge analysis was able to detect adenovirus dimers, trimers, and tetramers, consistent with a rigid sphere approximation for adenovirus, as well as a large aggregate of 0.35 μm. The appearance of viral aggregates is confirmed by increased light scattering based on A₃₂₀/A₂₆₀ ratios. The technique could be useful for monitoring the kinetics of aggregation for adenovirus and other DNA and RNA viruses in the submicron region. Therefore, this novel assay provides a critical tool for purification development of viral vectors for meeting therapeutic and research needs. Received 18 September 1997/ Accepted in revised form 15 May 1998     

An in vitro model of acetaldehyde metabolism by rodent conceptuses

Summary A culture model is described for the study of acetaldehyde (A_cH) metabolism by explanted postimplantation rat and mouse conceptuses. The ability of 12-d rat and 10-d mouse embryos to metabolise A_cH was demonstrated. The elimination rate for the 12-d rat conceptus using an initial A_cH concentration of 1 mM in the medium was found to be 1.8 nmol/mg per minute. When the conceptus was divided into embryonic and extraembryonic tissue, the rates were 1.6 and 2.2 nmol/mg per minute, respectively. When the A_cH concentration was reduced to 50 μM the rate was 0.095 nmol/mg per minute. The results provide further evidence for a functional barrier that prevents A_cH entry to the embryo. A comparative experiment using CBA/beige mouse conceptuses showed that A_cH elimination characteristics may be qualitatively similar to those in rat embryos, but that the estimated elimination rate of 0.8 nmol/mg per minute was less than half that of the rat. Thus the “metabolic barrier” may be less efficient in the mouse. This may be important in view of the greater sensitivity of the mouse to ethanol embryotoxicity. The work was supported by the King Edward Memorial Hospital Research Foundation and the Raine Research Foundation.     

A simple extraction method suitable for PCR-based analysis of plant,fungal, and bacterial DNA

A simple and easy protocol for extracting high-quality DNA from microorganisms and plants is presented. The method involves inactivating proteins by using SDS/proteinase K and precipitating polysaccharides in the presence of high salt. Further purification is based on differential solubility of DNA and high-molecular-weight polysaccharides in aqueous media. The procedure does not use the toxic and potentially hazardous phenol and chloroform, and as many as 100 samples can be processed per day. Absorbency ratios (A₂₆₀/A₂₈₀) of 1.6–2.0 indicated a minimal presence of contaminating metabolites. The DNA was completely digested with 5 restriction enzymes:EcoR I,RsaI,TaqI,EcoR V, andHind III. PCR analysis using enterobacterial repetitive intergenic consensus (ERIC) sequence, sequence-characterized amplified region (SCAR), and random amplified microsatellite (RAMS) primers showed the DNA's compatibility with downstream applications. This procedure is applicable to a range of pathogens and plants and thus may find wide application in quarantine services and marker-assisted selection (MAS) breeding.     

Cloning and characterization of a DNA repair gene inHaemophilus influenzae

Using a high-efficiency DNA cloning vector pJ1–8, a DNA repair geneuvr1 has been self-cloned in bacteriumHaemophilus influenzae. Chimeric plasmid pKuvrl, carrying wild type allele ofuvr1 gene and flanking DNA sequences, specifically complements auvr1 gene mutation in the bacterial chromosome. Auvr1_} mutation could be transferred from chromosome byin vivo recombination to pKuvr1 and isolated and designated as plasmid pKuvrl₋. Plasmid pKuvrl carries a 11.3 kb chromosomal DNA insert which was scanned for the presence of any other DNA repair genes by a novel method of directed mutagenesis. Preliminary analysis of the 3 new mutants isolated by this method supports the notion that the insert contains more than one gene concerned with ultraviolet radiation-sensitivity.     

Improved procedure for separation and purification of <Emphasis Type="Italic">Arthronema africanum</Emphasis> phycobiliproteins

A rapid, inexpensive and reliable procedure for separation and purification of C-phycocyanin (C-PC) and allophycocyanin (APC) from Arthronema africanum based on a previously described rivanol-sulfate method for C-PC purification was developed. Exclusion of NaCl from the extraction buffer resulted in complete separation of APC and C-PC, two-fold reduction of rivanol treatments, and a higher yield and purity of C-PC. Pure C-PC (A₆₂₀/A₂₈₀ of 4.52) and APC (A₆₅₂/A₂₈₀ of 2.41) were obtained. The estimated molecular masses of the α and β subunits were 17 and 19 kDа for С-phycocyanin and 16 and 18 kDа for APC, respectively. The overall C-PC recovery of 55% (w/w) from its content (100 mg) in the crude extract was 10–20% higher than so far reported. The procedure appears promising for scaling up and broader applications.     

Probing the ground state of the purple mixed valence CuA center in nitrous oxide reductase: a CW ENDOR (X-band) study of the 65Cu, 15N-histidine labeled enzyme and interpretation of hyperfine couplings by molecular orbital calculations

 CW ENDOR (X-band) spectra for the purple mixed-valence [Cu(1.5+)...Cu(1.5+)], S = 1/2, Cu_A site in nitrous oxide reductase were obtained after insertion of ⁶⁵Cu or both ⁶⁵Cu and ¹⁵N-histidine. The ¹⁴N/¹⁵N isotopic substitution allowed for an unambiguous deconvolution of proton and nitrogen hyperfine couplings in the spectra. A single nitrogen coupling with a value of 12.9 ± 0.4 MHz for ¹⁴N was detected. Its anisotropy was characteristic for imidazole bound to copper. A spin density of 3–5% was estimated for the nitrogen donors to Cu_A, indicating that the ground state is ²B_3u. Proton hyperfine structure was detected from four C_β protons of coordinating cysteine residues. Their isotropic and anisotropic parts were deconvoluted by spectral simulation. From the anisotropic couplings a spin density of 16–24% was estimated for each of the cysteine thiolate donors of Cu_A. The [N_HisCu(RS)₂CuN_His]⁺ core structure of Cu_A in nitrous oxide reductase from Pseudomonas stutzeri is predicted to be similar to the crystallographically determined Cu_A* structure (Wilmanns M, Lappalainen P, Kelly M, Sauer-Eriksson E, Saraste M (1995) Proc Natl Acad Sci USA 92 : 11955–11959), but distinct from the Cu_A structure of Paracoccus denitrificans cytochrome c oxidase (Iwata S, Ostermeier C, Ludwig B, Michel H (1995) Nature 376 : 660–669). The angular dependence of the isotropic couplings as a function of the electronic ground state was calculated by the INDO/S method. The Mulliken atomic-spin populations calculated by a gradient-corrected density functional method and the semiempirical INDO/S method were compared with experimentally derived spin populations, and good agreement between theory and experiment was found for both calculations. The ground state of Cu_A is best represented by the resonance structures of the form [Cu^IS^–S^–Cu^II↔ Cu^IS^•S^–Cu^I↔ Cu^IS^–S^•Cu^I↔ Cu^IIS^–S^–Cu^I]. It is proposed that the Cu 4s,p as well as sulfur 3d orbitals play a role in the stabilization of this novel type of cluster. Received: 17 September 1997 / Accepted: 28 October 1997     

A simple and efficient protocol for isolation of functional RNA from plant tissues rich in secondary metabolites

A protocol is described for rapid RNA isolation from various plant species and tissues rich in polyphenolics and polysaccharides. The method is based on the Nucleon PhytoPure^™ system without the use of phenol. The procedure can be completed within 1 h and many samples can be processed at the same time. The yield ranged from 240 μg up to 3 mg per gram of tissue with an average purity measured as A_260/280 of 1.85. The RNA was of sufficient quality for use in RT-PCR reactions. Quantitation of single-stranded cDNA was carried out with the RiboGreen^™ reagent and of PCR products with the PicoGreen^™ reagent.     

Reconciling the apparent difference between mass- and area-based expressions of the photosynthesis-nitrogen relationship

The relationship between photosynthetic carbon assimilation (A _max) and leaf nitrogen content (N _leaf) can be expressed on either a leaf area basis (A _area vs N _area) or a leaf mass basis (A _mass vs N _mass). Dimensional analysis shows that the units for the slope of this relationship are the same for both expressions (μmol [CO₂] g⁻¹ [N] s⁻¹). Thus the slope measures the change in CO₂ assimilation per gram of nitrogen, independent of leaf mass or leaf area. Although they have the same units, large differences between the area and mass-based slopes have been observed over a broad range of taxonomically diverse species. Some authors have claimed that regardless of these differences, the fundamental nature of the A _max-N _leaf relationship is independent of the units of expression. In contrast, other authors have claimed that the area-based A _max-N _leaf relationship is fundamentally different from the mass-based relationship because of interactions between A _max, N _leaf, and leaf mass per area (LMA, g [leaf] m⁻² [leaf]). In this study we consider the mathematical relationships involved in the transformation from mass- to area-based expressions (and vice versa), and the implications this transformation has for the slope of the A _max-N _leaf relationship. We then show that the slope of the relationship is independent of the units of expression when the effect of LMA is controlled statistically using a multiple regression. The validity of this hypothesis is demonstrated using 13 taxonomically and functionally diverse C₃ species. This analysis shows that the slope of the A _max-N _leaf relationship is similar for the mass- and area-based expressions and that significant errors in the estimate of the slope can arise when the effect of LMA is not controlled. Received: 7 May 1998 / Accepted: 19 October 1998     

A fast, simple, and reliable high-yielding method for DNA extraction from different plant species

Genetic studies and pathogen detection in plants using molecular methods require the isolation of DNA from a large number of samples in a short time span. A rapid and versatile protocol for extracting high-quality DNA from different plant species is described. This method yields from 1 to 2 mg of DNA per gram of tissue. The absorbance ratios (A₂₆₀/A₂₈₀) obtained ranged from 1.6 to 2.0. A minimal presence of contaminating metabolites (as polymerase chain reaction [PCR] inhibitors) in samples and a considerable savings in reagents are characteristics of this protocol, as well as the low cost of the analysis per sample. The quality of the DNA was suitable for PCR amplification.     

A measure of bending in nucleic acids structures applied to A-tract DNA

A method is proposed to measure global bending in DNA and RNA structures. It relies on a properly defined averaging of base-fixed coordinate frames, computes mean frames of suitably chosen groups of bases and uses these mean frames to evaluate bending. The method is applied to DNA A-tracts, known to induce considerable bend to the double helix. We performed atomistic molecular dynamics simulations of sequences containing the A₄T₄ and T₄A₄ tracts, in a single copy and in two copies phased with the helical repeat. Various temperature and salt conditions were investigated. Our simulations indicate bending by roughly 10° per A₄T₄ tract into the minor groove, and an essentially straight structure containing T₄A₄, in agreement with electrophoretic mobility data. In contrast, we show that the published NMR structures of analogous sequences containing A₄T₄ and T₄A₄ tracts are significantly bent into the minor groove for both sequences, although bending is less pronounced for the T₄A₄ containing sequence. The bending magnitudes obtained by frame averaging are confirmed by the analysis of superhelices composed of repeated tract monomers.     

Growth-active gibberellins overcome the very slow shoot growth of Hancornia speciosa, an important fruit tree from the Brazilian “Cerrado”

Shoot elongation of Hancornia speciosa, an endangered tree from the Brazilian savannah “Cerrado”, is very slow, thus limiting nursery production of plants. Gibberellins (GAs) A₁, A₃, and A₅, and two inhibitors of GA biosynthesis, trinexapac-ethyl and ancymidol were applied to shoots of Hancornia seedlings. GA₁ and GA₃ significantly stimulated shoot elongation, while GA₅ had no significant effect. Trinexapac-ethyl and ancymidol, both at 100 μg per seedling, inhibited shoot elongation up to 45 days after treatment, though the effect was statistically significant only for ancymidol. Somewhat surprisingly, exogenous GA₃ more effectively stimulated shoot elongation in SD-grown plants, than in LD-grown plants. The results from exogenous application of GAs and inhibitors of GA biosynthesis imply that Hancornia shoot growth is controlled by GAs, and that level of endogenous growth-active GAs is likely to be the limiting factor for shoot elongation in Hancornia. Application of GAs thus offer a practical method for nursery production of Hancornia seedlings for outplanting into the field.     

Efficient separation and purification of allophycocyanin from <Emphasis Type="Italic">Spirulina</Emphasis> (<Emphasis Type="Italic">Arthrospira</Emphasis>) <Emphasis Type="Italic">platensis</Emphasis>

Allophycocyanin (APC) is a minor component of phycobiliproteins in cyanobacteria and red algae. This paper describes a simple and inexpensive extracting method for isolating APC from Spirulina (Arthrospira) platensis with high efficiency. The crude phycobiliprotein extract was pretreated by ammonium sulfate fractionation. Then, by adding hydroxylapatite into crude phycobiliprotein extract dissolved in 20 mM phosphate buffer (pH 7.0), APC was selectively adsorbed by hydroxylapatite but C-phycocyanin (C-PC) was not. The hydroxylapatite was collected and APC was extracted from the crude phycobiliprotein extract. Then, the enriched APC was washed off from the hydroxylapatite using 100 mM phosphate buffer (pH 7.0). In this simple extracting method it was easy to remove C-PC and isolate APC in large amounts. The absorbance ratio A ₆₅₀/A ₂₈₀ of extracted APC reached 2.0. The recovery yield was 70%, representing 4.61 mg · g⁻¹ wet weight. The extracted APC could be further purified by a simple anion-exchange chromatography with a pH gradient from 5.6 to 4.0. The absorbance ratio A ₆₅₀/A ₂₈₀ of the purified APC reached 5.0, and the overall recovery yield was 43%, representing 2.83 mg · g⁻¹ wet weight. Its purity was confirmed by native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate-PAGE.     

Estimating photosynthetic electron transport via chlorophyll fluorometry without Photosystem II light saturation

Estimates of thylakoid electron transport rates (J_e) from chlorophyll fluorometry are often used in combination with leaf gas exchange measurements to provide detailed information about photosynthetic activity of leaves in situ. Estimating J_e requires accurate determination of the quantum efficiency of Photosystem II (Φ_P), which in turn requires momentary light saturation of the Photosystem II light harvesting complex to induce the maximum fluorescence signal (F_M′). In practice, full saturation is often difficult to achieve, especially when incident photosynthetic photon flux density (Q) is high and energy is effectively dissipated by non-photochemical quenching. In the present work, a method for estimating the true F_M′ under high Q was developed, using multiple light pulses of varying intensity (Q′). The form of the expected relationship between the apparent F_M′ and Q′ was derived from theoretical considerations. This allowed the true F_M′ at infinite Q′ to be estimated from linear regression. Using a commercially available leaf gas exchange/ chlorophyll fluorescence measurement system, J_e was compared to gross photosynthetic CO₂ assimilation (A_G) under conditions where the relationship between J_e and A_G was expected to be linear. Both in C₄ leaves (Zea mays) in ambient air and also in C₃ leaves (Gossypium hirsutum) under non-photorespiratory conditions the apparent ratio between J_e and A_G declined at high Q when Φ_P was calculated from F_M′ measured simply using the highest available saturating pulse intensity. When F_M′ was determined using the multiple pulse / linear regression technique, the expected relationship between J_e and A_G at high Q was restored, indicating that the Φ_P estimate was improved. This method of determining F_M′ should prove useful for verifying when saturating pulse intensities are sufficient, and for accurately determining Φ_P when they are not. This revised version was published online in June 2006 with corrections to the Cover Date.     

Photosynthetic characteristics of dipterocarp seedlings in three tropical rain forest light environments: a basis for niche partitioning?

In three tropical rain forest light environments in Sabah, Malaysia, we compared photosynthesis in seedlings of ten climax tree species with putatively differing shade tolerances. The objectives of the study were (a) to characterise the range of photosynthetic responses in ten species of the Dipterocarpaceae and (b) to elucidate those photosynthetic characteristics that might provide a basis for niche partitioning. Seedlings were acclimated (c. 7 months) in three light environments; understorey, partial shade and a gap (140 m²). The light environments represented a gradation in median diurnal (0630–1830 hours) photon flux density (PFD) ranging from understorey (4.7 μmol m⁻² s⁻¹), through partial shade (21.2 μmol m⁻² s⁻¹) to gap (113.7 μmol m⁻² s⁻¹). Integrated diurnal PFD were in the sequence gap > partial shade > understorey (15.2, 4.7, 1.3 mol m⁻² day⁻¹, respectively). In gap-acclimated plants, species differed in the photosynthetic light-response variables apparent quantum yield, dark respiration rate, light compensation point, net saturated leaf assimilation rate (A _sat), and in stomatal conductance (g _s sat) when assimilation rate (A) was saturated. A light-demanding pioneer species (Macaranga hypoleuca) and a shade-demanding understorey species (Begonia sp.) had, respectively, higher and lower A _sat and g _s sat than the dipterocarp species. In high-light conditions A _sat and g _s sat were strongly positively correlated in dipterocarp species. Differing photosynthetic characteristics of gap-acclimated plants suggest that, in these dipterocarp species, different rates of carbon fixation may be an important factor contributing towards niche partitioning. Mean integrated diurnal A (A _diurnal) in the gap, partial shade and understory were, respectively, 122.9, 52.7, 20.5 mmol m⁻² day⁻¹. Differences occurred in A _diurnal of dipterocarp species between light environments. When Macaranga was included, differences in A _diurnal were evident in the gap and partial shade, and in both cases were attributed to the pioneer. For the variable A _diurnal, there was of a shift in the rank position of Macaranga among light environments, but a shift did not occur among the dipterocarp species. Results from this study are consistent with the idea that rates of carbon fixation per unit leaf area may contribute towards niche differentiation between the climax and single pioneer species, but not within the group of climax species. Other physiological and/or carbon allocation factors may be involved in any niche partitioning; dipterocarp species often have inherently different growth rates and susceptibility to herbivory. As an alternative to niche partitioning, dipterocarp species may co-exist in natural light environments as a result of habitat disequilibrium or purely stochastic processes. Received: 2 April 1997 / Accepted: 13 July 1997     

Toxicity of prostaglandins A1 and A2 for cells in culture

Summary Prostaglandins A₁ and A₂, in concentrations near 3×10⁻⁵ M, produced striking toxicity to muscle, skin and liver cells in culture. Prostaglandins E and F_2α were much less active in this regard. Toxicity could be measured by reduction in viable cell number, protein and DNA synthesis in the cultures. The sensitivity of cultured cells was related to their age and population density. Dense cultures were sensitive early, in the first 2 days, and resistant after they manifested confluent growth. Sparse cultures remained sensitive later while they continued DNA synthesis and active cell division. It is hypothesized that the prostaglandin A effect is related to active cell division and DNA synthesis. Supported by USPHS NIAMDD 1RO1 AM 14650 and the Muscular Dystrophy Associations of America, Inc.