Phytoalexins from Brassicaceae: News from the front

The chemical structures, syntheses, metabolism and biological activities of the cruciferous phytoalexins discovered to date, with particular focus on the latest results dealing with their biosynthesis and detoxification are reviewed.     

Structure of the O-polysaccharide from the lipopolysaccharide from Vibrio cholerae O6

The O-polysaccharide from Vibrio cholerae O6 was isolated from the LPS by mild-acid hydrolysis and has been investigated by sugar and methylation analysis and NMR spectroscopy. The polysaccharide was also depolymerized with aqueous hydrofluoric acid to give the repeating unit and multiples thereof. The O-polysaccharide had the following tetrasaccharide repeating unit. Two O-acetyl groups are present, one of them making the GlcNAc residue fully substituted and the steric crowding considerable at the branching residue.     

Items from the Literature

Hazards in fixing small pieces of tissue for electron microscopy include damage, drying, or loss. Over the years, microstrainer tissue carriers have been developed to minimize these problems. Construction materials have included glass tubing, copper grids for electron microscopy, stainless steel screen, and bolting silk (Padawer 1951, Friend 1963, Bronskill 1970). Carriers made from plastic embedding molds (e.g., BEEM capsules) with either TEM grids attached to the conical tip (Buchanan 1965) or Nitex screen cloth held to one end by a retaining ring have proven to be inexpensive and popular, though the former has a very small filtration area and in the latter small tissues may be lost or crushed between the screen cloth and the bottom rim of the carrier. This note describes a carrier in which Nitex is permanently sealed to the bottom edee of a BEEM capsule cylinder.     

Letter from the Editors

Two behavioural measures of activity at 5HT₁ receptors in mice: RU 24969-induced hyperactivity and 80H-DPAT hypothermia, were measured at 3-hr intervals throughout the 12-12 L-D cycle. Neither parameter showed significant circadian variation.     

Everything from the egg

In 1651, William Harvey opened a real debate when he postulated that the egg is the origin of all life. The central pillar of Harvey's theory sustains that all adults are already present in a smaller size in the egg. The frontispiece of his famous treatise attributed to Richard Gaywood shows Zeus holding an egg that releases small creatures as humans, others animals, and plants. The treatise concludes that no generation occurs without a primordial egg, representing the establishment of ex Ovo Omnia doctrine. Nowadays, evidence supports that both male and female gametes are essential for embryo development following sexual reproduction. Despite obvious differences in morphology and in scale, the oocytes carry out the same role in the development and still demonstrate the mystery of reproduction.     

Items from the Literature

LIPP, WALTHER. Histochemische Methoden. Twenty-four pages per issue; 3 issues (No. 12, 13 and 14) during 1957. R. Oldenbourg, Miinchen 1, Germany. DM 30-for 6 issues; DM 6—per single copy. (In German)

STACH, E. Auflicht-Mikroslcopie mit Immersions-Kappen. Mikroskopie, 12, 232-42. 1957.

JOHNSON, C. Time savers in the paraffin technique. Turtox News, 36, 126-7. 1958.

JONSSON, N., and LAGERSTEDT, S. Losses of nucleic acid derivatives from fixed tissues during flattening of paraffin sections on water. Experientia, 14, 157-9. 1958.

SCHAUMKELL, K. W., STANGE, H. H., and DÖRFFLER, P. Methodische Untersuchungen über die pH-abhängige Aufname saurer und basischer Hellfeld-Diachrome in der Nebennierenrinde. Mikroskopie, 12, 227-32. 1957.

SCHEFTHALER, MARIA, and MAYET, A. Eine Modification der Bielschowsky Methode für periphere Nervenfasern. Mikroskopie, 12, 298-801. 1958.

LANGENBUCH, R. Beitrag zur Färbung von Einschluszkörpern (Polyedern) in Blut- und Gewebeausstrichen viruskranker Insecten. Mikroskopie, 12, 267-8. 1957.

SHUGAR, D., and BARANOWSKA, J. Quantitative Gram staining with labelled iodine. Nature, 181, 357-8. 1958.

ARVY, L., and GABE, M. Comparison des activitiés aliestérasique mises en évidence par les techniques au tween et a l'acétate de naphthyle. Ann. d'Histochimie, 2, 141-8. 1957.

VERNE, J., and WEGMANN, R. Problèmes actuels de la cytochimie des estérases (carboxyl estérases and cholinestérases). Ann. d'Histochimie, 2, 75-107. 1957.

WEGMANN, R. Les carbonyles lipidiques. III. Les facteurs associés au prétraitement. Ann. d'Histochimie, 2, 197-214. 1957.     

Fatty acids from the sponge Halichondria panicea from the Sea of Japan

The fatty acid (FA) composition of total lipids isolated from the marine sponge Halichondria panicea inhabiting Peter the Great Bay of Sea of Japan was studied. GC and GC-MS techniques helped identify 63 FAs, with the main attention being paid to FAs with 14-22 carbon atoms. 4, 8, 12-Trimethyl-13:0 FA was for the first time identified as the main saturated FA along with the branched FAs br-25:1, br-27:1, and br-27:2. The contents of arachidonic, eicosapentaenoic, docosapentaenoic, and the major demospongic acids [26:3(5, 9, 19), 26:3(5, 9, 17), 27:3(5, 9, 20), and 28:3(5, 9, 21)] considerably differed from those previously found for H. panicea, which may be due to seasonal changes in the species composition of organisms consumed by the sponge.     

Antibacterial metabolites from Australian macrofungi from the genus Cortinarius

In this study, ethyl acetate and aqueous fractions from 117 collections of Australian macrofungi belonging to the mushroom genus Cortinarius were screened for antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa. Overall, the lipophilic fractions were more active than the aqueous fractions. The ethyl acetate fractions of most or all collections of 13 species, namely Cortinarius ardesiacus, C. archeri, C. austrosaginus, C. austrovenetus, C. austroviolaceus, C. coelopus, C. [Dermocybe canaria]², C. clelandii, C. [D. kula], C. memoria-annae, C. persplendidus, C. sinapicolor, C. vinosipes and forty seven collections of un-described Cortinarius species exhibited IC₅₀ values of ?0.09 mg/mL against S. aureus. In contrast, most or all collections of only four species, namely C. abnormis, C. austroalbidus, C. [D. kula], C. persplendidus, and eleven un-described Cortinarius collections exhibited similar effects against P. aeruginosa (IC₅₀ ? 0.09 mg/mL). Anthraquinonoid pigments isolated from C. basirubescens together with emodin physcion and erythrogluacin were assessed for their antimicrobial activity. The fungal octaketides austrocortilutein, austrocortirubin, torosachrysone, physcion and emodin were found to strongly inhibit the growth of S. aureus (IC₅₀ 0.7–12 μg/mL) whereas only physcion and emodin exhibited potency against P. aeruginosa (IC₅₀ 1.5 and 2.0 μg/mL, respectively).     

Announcement from the publisher

Announcement from the publisher