The sterols of echinoderms

The pioneering work of Bergmann and his colleagues demonstrated that marine invertebrates in many cases contain complex sterol mixtures consisting of C 27 , C 28 and C 29 sterols of varying degrees of unsaturation (Bergmann 1949, 1962). The sterols found in the phylum Echinodermata have proved of particular interest not only from the point of view of their composition and biological origin but also from phylogenetic considerations. Dorée (1909) first recognized that the sterol of a starfish differed from cholesterol, the typical sterol of higher animals. Later Kossel & Edlbacher (1915) obtained the sterol from a starfish, Asteropecten aurantiacus , and named it stellasterol. Subsequently Bergmann & Stansbury (1944) concluded that starfish sterols are mixtures which include stellastenol (1) and stellasterol, the 22, 23-dihydro derative of stellastenol (Shoppee 1964) Extending their studies Bergmann and co-workers demonstrated that the echinoderms can be divided into two groups on the basis of the types of sterol which they contain. Crinoidea (sea lilies), Ophiuroidea (brittle stars) and Echinoidea (sea urchins) contain sterols with a ∆ 5 bond while the Asteroidea (starfish) and Holothuroidea (sea cucumbers) contain mixtures in which sterols with a ∆ 7 bond predominate (Bergmann 1962). This division of echinoderms according to sterol type has recently been confirmed by Gupta & Scheuer (1968) using more modern methods of sterol analysis. Bergmann (1962) concluded that the distribution of ∆ 5 and ∆ 7 sterols in the different classes of echinoderms is a reflexion of the phylogenetic relationships which exist in the phylum. From embryological evidence there is a close relationship between the asteroids and holothuroids on the one hand and the ophiuroids and echinoids on the other (Bergmann 1962; Hyman 1955). In addition to the data on sterols other comparative biochemical evidence on the occurrence and distribution of batyl alcohol, spinochromes and phosphagens in echinoderms is in accord with these phylogenetic relationships (Singh, Moore & Scheuer 1967; Bolker 1967 α ). The validity of the embryological and biochemical evidence, however, has been contested by Fell who regards the asteroids to be more closely related to the ophiuroids while the holothuroids have some affinities with the echinoids (Fell 1948, 1963, 1965; Fell & Pawson 1966; Bolker 1967 α ).

Response of type illa-j kodak spectroscopic plates to baking in various controlled atmospheres

A new emulsion with excellent signal-to-noise characteristics has been hypersensitized to speeds practicable for astronomical applications by baking in a controlled nitrogen atmosphere. Important gains are achieved in speed and fog suppression relative to the usual procedure of baking in air.

Land Clearance in the Irish Neolithic: New Evidence and Interpretation

Time scales are derived, from radiocarbon dating of pollen diagrams, for Neolithic land clearance at three Irish sites. Three stages are distinguished beginning in the 4th millennium B.C.: stage A, clearance and farming (possibly arable), 100 to 400 years; stage B, farming (possibly pastoral), 150 to 200 years; and stage C, forest regeneration, 50 to 100 years.

Decametric Radio Pulses from Jupiter: Characteristics

On occasion the decametric radio bursts from Jupiter contain pulses of millisecond duration. Study of data for 2 years shows that the distribution in Jovian longitude of these fast pulses is different from that of the more common pulses of longer duration. The two classes of pulses also appear to be differently affected by the position of the innermost Galilean satellite.

Jupiter's Decametric Emission Correlated with the Longitudes of the First Three Galilean Satellites

An analysis of data obtained at a variety of frequencies since 1957 has confirmed Bigg's observation that the satellite Io appears to control the emission of decametric radio energy by Jupiter. The correlation is stronger when intensity, rather than simple probability, is included in the analysis. There is also evidence of a similar influence by the satellites Europa and Ganymede.

Cytological observations on the sporulation process of Clostridium perfringens

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