Correction: Self-assembled fibrillar networks comprised of a naturally-occurring cyclic peptide-LOB3.

[This corrects the article DOI: 10.1039/C6RA05154E.].

A novel formulation significantly increases the cytotoxicity of flaxseed orbitides (linusorbs) LOB3 and LOB2 towards human breast cancer MDA-MB-231 cells.

Flaxseed orbitides (linusorbs) are a family of N to C linked bioactive cyclic octa-, nona-, and decapeptides present in flaxseed oil. They are highly hydrophobic and thermally stable. Our previous studies showed that [1-9-NαC]-linusorb B3 (LOB3) and [1-9-NαC]-linusorb B2 (LOB2) exhibited cytotoxic effects towards human breast cancer HER2-subtype Sk-Br-3 cells at a concentration of ~400 µM. However, this high concentration significantly limits their potential clinical applications. In the current study, we developed a novel polyethylene glycol-based formulation for linusorbs and showed that both LOB3 and LOB2, especially LOB3, exhibited strong cytotoxicity towards human breast cancer triple-negative-subtype MDA-MB-231 cells at low nanomolar concentrations.

Cyclo-linopeptide A methanol solvate.

Crystals of the title compound, C(57)H(85)N(9)O(9)·CH(4)O, the methanol solvate of a nine peptide polypeptide, cyclo-(Pro-Pro-Phe-Phe-Leu-Ile-Ile-Leu-Val), were obtained after separation of the cyclic peptide from flax oil. The cyclo-linopeptide A (CLP-A) mol-ecules are linked in chains along the a axis by N-H⋯O hydrogen bonds. Each methanol O atom is hydrogen bonded to one O atom and two N-H groups in the same CLP-A mol-ecule. There are a total of eight hydrogen bonds in each CLP-A-MeOH unit.

Synthesis and characterization of vegetable oil derived esters: evaluation for their diesel additive properties.

Trans-esterification of four vegetable oils; canola oil, greenseed canola oil from heat-damaged seeds, processed waste fryer grease and unprocessed waste fryer grease, was carried out using methanol, and KOH as catalyst. The methyl esters of the corresponding oils were separated from the crude glycerol, purified, and characterized by various methods to evaluate their densities, viscosities, iodine values, acid numbers, cloud points, pour points and gross heat of combustion, fatty acid and lipid compositions, lubricity properties, and thermal properties. The fatty acid composition suggests that 80-85% of the ester was from unsaturated acids. Substantial decrease in density and viscosity of the methyl esters compared to their corresponding oils suggested that the oils were in their mono or di glyceride form. The lubricity of the methyl esters, when blended at 1 vol% treat rate with ISOPAR M reference fuel, showed that the canola methyl ester enhanced the fuel's lubricity number. From the analyses performed, it was determined that the ester with the most potential for being an additive or a substitute for diesel fuel is the canola methyl ester, whose physical and chemical characteristics are similar to diesel fuel.

Preparation and characterization of bio-diesels from various bio-oils.

Methyl, ethyl, 2-propyl and butyl esters were prepared from canola and linseed oils through transesterification using KOH and/ or sodium alkoxides as catalysts. In addition, methyl and ethyl esters were prepared from rapeseed and sunflower oils using the same catalysts. Chemical composition of the esters was determined by HPLC for the class of lipids and by GC for fatty acid compositions. The bio-diesel esters were characterized for their physical and fuel properties including density, viscosity, iodine value, acid value, cloud point, pure point, gross heat of combustion and volatility. Methyl and ethyl esters prepared from a particular vegetable oil had similar viscosities, cloud points and pour points, whereas methyl, ethyl, 2-propyl and butyl esters derived from a particular vegetable oil had similar gross heating values. However, their densities, which were 2 7% higher than those of diesel fuels, statistically decreased in the order of methyl approximately 2-propyl > ethyl > butyl esters. Butyl esters showed reduced cloud points (-6 degrees C to -10 degrees C) and pour points (-13 degrees C to -16 degrees C) similar to those of summer diesel fuel having cloud and pour points of -8 degrees C and -15 degrees C, respectively. The viscosities of bio-diesels (3.3-7.6 x 10(-4) Pa s at 40 degrees C) were much less than those of pure oils (22.4-45.1 x 10(-4) Pa s at 40 degrees C) and were twice those of summer and winter diesel fuels (3.50 and 1.72 x 10(-4) Pa s at 40 degrees C), and their gross heat contents of approximately 40 MJ/kg were 11% less than those of diesel fuels (approximately 45 MJ/kg). For different esters from the same vegetable oil, methyl esters were the most volatile, and the volatility decreased as the alkyl group grew bulkier. However, the bio-diesels were considerably less volatile than the conventional diesel fuels.

An example of intron junctional sliding in the gene families encoding squalene monooxygenase homologues in Arabidopsis thaliana and Brassica napus.

Sequences of three Arabidopsis thaliana and two Brassica napus cDNAs encoding squalene monooxygenase homologues (Sqp1 and Sqp2) are reported. Southern analysis confirmed that these cDNAs are derived from small gene families in both species. Expression analysis indicates that Sqp1 genes in B. napus are strongly expressed in leaves but not roots or developing seeds. Comparison of cDNA and genomic sequences indicate that the 3' splice site of an intron in these genes has undergone junctional sliding. The evolutionary significance of this phenomenon is discussed.

Structure-Activity Relationships of Abscisic Acid Analogs Based on the Induction of Freezing Tolerance in Bromegrass (Bromus inermis Leyss) Cell Cultures.

The induction of freezing tolerance in bromegrass (Bromus inermis Leyss) cell culture was used to investigate the activity of absisic acid (ABA) analogs. Analogs were either part of an array of 32 derived from systematic alterations to four regions of the ABA molecule or related, pure optical isomers. Alterations were made to the functional group at C-1 (acid replaced with methyl ester, aldehyde, or alcohol), the configuration at C-2, C-3 (cis double bond replaced with trans double bond), the bond order at C-4, C-5 (trans double bond replaced with a triple bond), and ring saturation (C-2', C-3' double bond replaced with a single bond so that the C-2' methyl and side chain were cis). All deviations in structure from ABA reduced activity. A cis C-2, C-3 double bond was the only substituent absolutely required for activity. Overall, acids and esters were more active than aldehydes and alcohols, cyclohexenones were more active than cyclohexanones, and dienoic and acetylenic analogs were equally active. The activity associated with any one substituent was, however, markedly influenced by the presence of other substituents. cis, trans analogs were more active than their corresponding acetylenic analogs unless the C-1 was an ester. Cyclohexenones were more active than cyclohexanones regardless of oxidation level at C-1. An acetylenic side chain decreased the activity of cyclohexenones but increased the activity of cyclohexanones relative to their cis, trans counterparts. Trends suggested that for activity the configuration at C-1' has to be the same as in (S)-ABA, in dihydro analogs the C-2'-methyl and the side chain must be cis, small positional changes of the 7'-methyl are tolerable, and the C-1 has to be at the acid oxidation level.

Water relation parameters of embryogenic cultures and seedlings of larch.

Changes in the water relations parameters of developing somatic embryogenic and xygotic European larch (Larix decidua) were studied. Water release curves were generated by suspending tissue samples over unsaturated NaCl solutions until they reached vapor equilibration with the surrounding air. Twenty solutions were used whose water potentials ranged from -0.05 to -10 MPa. Water release curves were obtained by plotting paired values of tissue relative water content (RWC) and solution potential. Curves were derived for embryonic larch at various stages of development and for hypocotyls and roots from germinated zygotic and somatic embryos. The ability to resist dehydration increased markedly with development. Stage 1 tissue, which consisted of clusters of loosely associated nonchlorophyllous cells, had extremely low bulk elastic modulus (epsilon) (1.91 MPa) and apoplastic water content (A) (0.023), relatively high osmotic potential (Psi(pi)) (-0.53 MPa), and lost turgor at 0.56 RWC. In contrast, mature embryoids with primary roots, hypocotyl, and cotyledons (stage 3) had an almost 4-fold increase in A (0.089), significantly higher epsilon (3.49 MPa), and lower Psi(pi) (-0.88 MPa) and lost turgor at 0.66 RWC. Hypocotyl tissue from germinated somatic embryos lost turgor at 0.74 RWC and had higher epsilon, A, and solute accumulation than pregerminated tissue. Hypocotyl tissue resisted dehydration more strongly than root tissue, and differences between root and hypocotyl water relation parameters were more pronounced in xygotic than in somatic seedlings. Highest dehydration resistance was in zygotic hypocotyls. The characterization of the water relations of tissue cultures should allow the development of more consistent and reliable desiccation protocols to induce maturation of embryos and produce synchronously germinating seed.

Monoclonal antibody recognition of abscisic Acid analogs.

Specificities of three monoclonal antibodies (15-I-C5, DBPA 1, and MAC 62) raised against the plant hormone (S)-(+)-abscisic acid (ABA) have been compared. Immunological cross-reactivities against fifteen biologically active analogs of ABA were measured. The ABA analogs were altered at one or more of four positions: the double bonds in the ring, at C-2 C-3 and at C-4 C-5, and in the oxidation level at C-1. Several analogs were optically active with chiral centers at C-1' and C-2'. For cross-reactivity, all three monoclonal antibodies required the carboxylic acid group, and the cis configuration of the double bond at C-2 C-3 of the ABA molecule. Monoclonals 15-I-C5 and DBPA 1 required the entire ABA sidechain from the C-1 to C-1', but these monoclonals did cross-react with analogs with the ring double bond reduced and the C-2' methyl cis to the sidechain. Only MAC 62 recognized analogs containing an acetylene at C-4 C-5. MAC 62 had more strict requirements for the ring double bond, but gave some cross-reactivity with acetylenic analogs having a saturated ring. All three monoclonals had higher specificity for analogs having the same absolute configuration at C-1' as (S)-(+)-ABA. This work provides new information about the spatial regions of the ABA molecule that elicit immunological recognition, and serves as a basis for future investigations of the ABA receptor using ABA analogs and anti-idiotypic antibodies.

Identification of Proteins Correlated with Increased Freezing Tolerance in Bromegrass (Bromus inermis Leyss. cv Manchar) Cell Cultures.

Cellular and extracellular protein profiles from Bromus inermis Leyss. cv Manchar cell suspension cultures cold hardened by low temperature and abscisic acid (ABA) treatment were analyzed by one- and two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis. Cellular proteins (25, 165, 190, and 200 kilodaltons) increased by low temperature growth and cellular proteins (20, 25, 28, 30, 32, 37, 40, 45, 200 kilodaltons) increased by exogenous ABA treatment were identified. Low temperature treatment inhibited the synthesis of a 22 kilodalton protein and ABA treatment resulted in the synthesis of two extracellular proteins (17 and 21 kilodaltons). Low temperature and ABA-induced hardening conditions increased or induced a 25 and a 200 kilodalton protein. The 25 and a 30 kilodalton protein previously shown to be enriched by ABA-induced hardening conditions at both 3 and 23 degrees C temperatures co-fractionated with the crude membrane fraction (30,000g sediment). The 200 kilodalton protein was detected in the 30,000g supernatant. Two-dimensional analysis of the crude membrane fraction resolved the 30 kilodalton protein band into a major polypeptide with an apparent isoelectric point of 6.85.

Protein Synthesis in Bromegrass (Bromus inermis Leyss) Cultured Cells during the Induction of Frost Tolerance by Abscisic Acid or Low Temperature.

Bromus inermis Leyss cell cultures treated with 75 micromolar abscisic acid (ABA) at both 23 and 3 degrees C developed more freezing resistance than cells cultured at 3 degrees C. Protein synthesis in cells induced to become freezing tolerant by ABA and low temperature was monitored by [(14)C]leucine incorporation. Protein synthesis continued at 3 degrees C, but net cell growth was stopped. Most of the major proteins detected at 23 degrees C were synthesized at 3 degrees C. However, some proteins were synthesized only at low temperatures, whereas others were inhibited. ABA showed similar effects on protein synthesis at both 23 and 3 degrees C. Comparative electrophoretic analysis of [(14)C]leucine labeled protein detected the synthesis of 19, 21 and 47 kilodalton proteins in less than 8 hours after exposure to exogenous ABA. Proteins in the 20 kilodalton range were also synthesized at 3 degrees C. In addition, a 31 kilodalton protein band showed increased expression in freezing resistant ABA treated cultures after 36 hours growth at both 3 and 23 degrees C. Quantitative analysis of [(14)C]leucine labeled polypeptides in two-dimensional gels confirmed the increased expression of the 31 kilodalton protein. Two-dimensional analysis also resolved a 72 kilodalton protein enriched in ABA treated cultures and identified three proteins (24.5, 47, and 48 kilodaltons) induced by low temperature growth.

Factors Influencing the Induction of Freezing Tolerance by Abscisic Acid in Cell Suspension Cultures of Bromus inermis Leyss and Medicago sativa L.

A 2-gram fresh weight inoculum of bromegrass (Bromus inermis Leyss. culture BG970) cell suspension culture treated with 7.5 x 10(-5) molar abscisic acid (ABA) for 7 days at 25 degrees C survived slow cooling to -60 degrees C. Over 80% of the cells in ABA treated cultures survived immersion in liquid N(2) after slow cooling to -40 or -60 degrees C. In contrast, a 6-gram fresh weight inoculum only attained a hardiness level of -28 degrees C after 5 days of ABA treatment. Ethanol (2 x 10(-2) molar) added to the culture medium at the time of ABA addition, inhibited the freezing tolerance of bromegrass cells by 25 degrees C. A 6-gram inoculum of both control and ABA treated bromegrass cells altered the pH of the medium more than a 2-gram inoculum. ABA inhibited the increase in fresh weight of bromegrass by 20% after 4 days. Both control and ABA (10(-4) molar) treated alfalfa cells (Medicago sativa L.) grown at 25 degrees C hardened from an initial LT(50) of -5 degrees C to an LT(50) of -23 degrees C by the third to fifth day after subculture. Thereafter, the cells dehardened but the ABA treated cells did not deharden to the same level as the control cells. ABA inhibited the increase in fresh weight of alfalfa by 50% after 5 days.