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The echurian worm Bonellia viridis has attracted the attention of both biologists and chemists over a long period of time. A drawing of the female organism is shown in Fig 1. The animal is a deep green all over its surface and is negatively phototactic. The trunk of the animal is generally housed in a burrow system and the proboscis is extended for feeding purposes. There are several points of interest regarding this organism. The first is the marked sexual dimorphism: the female is much larger than the male which is only 1 -3 nnn long.The males live parasitically inside the female after an initial period of settlement on the proboscis. There are usually several rnLes in each female. The eggs hatch into sexually undifferentiated larvae. It has been repeatedly observed that if the indifferent larvae settle on a female they differentiate into males, whilst if they settle away from the female they develop into females. Thus it is clear that an exogenous agent is influencing the determination of the sex of the larvae, rather than this being wholly determined genetically.The larvae seem to be specially attracted to the proboscis of the female on which they settle. When the larvae leave their site of attachment on the female, they leave behind a clear area from which all pigment has been removed,4 something we have been unable to achieve by chemical extraction. This removal of pigment suggests that it is being actively taken up by the larvae and raises the question of whether or not the pigment has anything to do with their masculinisation. Such a question is also raised by the observation that the degree of masculinisation depends on the length of contact between the adult and larvae, * Lecture delivered by Professor A. Pelter. 1847Bonellia viridis Rol. (female)

The structures of aspertetronin A (C16H2004) and aspertetronin 8 (C16H2,06), metabolites of a mutant strain of Aspergillus rugulosus, have been elucidated. The use of both high-resolution l H n.m.r. spectroscopy (220 Mc./ sec. and spin decoupling) and ' element-map ' mass spectrometry have proved determining in establishing that the metabolites are the novel acyltetronic acid derivatives (XXI I) and (XXI I I) respectively.

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The oxidation of low-density lipoprotein (LDL) is implicated in atherosclerosis. Lipids and oxidized lipids were analysed by gas chromatography and gas chromatography-mass spectrometry in human LDL incubated with mouse peritoneal macrophages (MPM) or copper (II) sulphate in Ham's F-10 medium or medium alone (control). MPM-modification and copper-catalysed oxidation of LDL resulted in the formation of oxysterols, mainly cholest-5-en-3 beta,7 beta-diol (7 beta-OH-CHOL); 7%-19% of the initial cholesterol was converted to 7 beta-OH-CHOL in 24 h. 7 beta-OH-CHOL levels in control LDL were very low. The increase in 7 beta-OH-CHOL in MPM and copper-oxidized LDL was accompanied by decreases in linoleate and arachidonate and increases in the electrophoretic mobility and degradation of LDL protein by 'target' macrophages. The concerted occurrence of these processes and their similarity in both MPM-modification and copper-catalysed oxidation of LDL were suggested by the highly significant cross-correlations. The fall in polyunsaturated fatty acid (PUFA) was accompanied by a directly proportional increase in electrophoretic mobility of the LDL. Production of 7 beta-OH-CHOL and protein degradation by macrophages showed modest elevations during the initial steep fall in PUFA, and showed their greatest increases as the levels of PUFA slowly approached zero. The levels of 7 beta-OH-CHOL and the degradation of LDL by macrophages were directly proportional. The degradation of LDL by macrophages increased rapidly as the electrophoretic mobility of LDL was slowly approaching its maximum level.