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.     

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.     

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.     

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.     

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.     

Cytotoxic diterpenoids from two lianas from the Suriname rainforest

Bioassay-guided fractionation of the MeOH and EtOAc fractions of extracts of two lianas collected in Suriname has led to the isolation of five new diterpenoids, humirianthone 1, 1-hydroxy-humirianthone 2, 15R-humirianthol 3, patagonol 4, and patagonal 5, and the five known diterpenoids, humirianthol 7, annonalide 8, acrenol 9, icacinol 10, and the oxidized annonalide 11. All 10 diterpenoids showed cytotoxic activity against the A2780 human ovarian cancer cell line, and compounds 1, 3, 8, and 9 also showed activity against phytopathogenic fungi.