The action of cyclic-AMP on GA3 controlled responses II. Similarities in the induction of barley endosperm ATPase activity by gibberellic acid and cyclic 3',5'-adenosine monophosphate

The effect of cyclic-AMP and GA3 on ATPase production in embryolessbarley half-seeds was examined. Similarities in the responseinduced by 5 mM cyclic-AMP and GA₃ were observed in (1) thetotal amount of ATPase produced, (2) the time course for therelease of ATPase, and (3) the effect of abscisic acid on ATPaseinduction by these compounds. Of a variety of adenine nucleotidesexamined only cyclic-AMP was found to promote high levels ofATPase activity. Some of the implications of these results arediscussed. (Received May 11, 1971; )     

Sampling communities of ground-foraging ants: Pitfall catches compared with quadrat counts in an Australian tropical savanna

The relative abundances of ant species captured in pitfall traps was compared with those obtained by direct counts in quadrats at a savanna site in Kakadu National Park, Northern Territory. Two measures of abundance in traps were used, one based on total numbers of ants, the other on species frequency of occurrence. All species commonly recorded in quadrats were collected in traps, and their relative abundances were highly correlated on all occasions. Of the 20 most common species in quadrats, five occurred with a significantly different (in all cases lower) frequency in pitfall traps, but these species represented only 1.8–3.1% of total quadrat counts. Results from quadrats and pitfall traps were particularly similar (r > 0.8) when species-were classified into functional groups. Frequency data from traps may sometimes overestimate the abundance of widespread, solitary foraging species (e.g. ‘Chelaner’ and Tetramorium spp.) and underestimate species with large colony sizes (e.g. Iridomyrmex spp.). Data based on total numbers of ants in traps may be more prone to distortion arising from species differences in locomotor behaviour. Species counts in traps could be scaled to reduce these distortions. The finding that pitfall traps gave results comparable with those from quadrat counts provides support for the use of pitfall traps in studies of Australian ant communities in open habitats.     

On the manual morphology of Compsognathus longipes and its bearing on the diagnosis of Compsognathidae

Compsognathus longipes sits at an important point in theropod evolution at the base of Coelurosauria . Despite its relative completeness and oft-cited morphology, however, the manual morphology has been unclear. This work provides the first detailed study of the morphology of the manus of Compsognathus longipes . It shows that Compsognathus longipes had two fully formed functional digits as well as a reduced, perhaps even non-functional, third digit. That conclusion runs counter to the usual interpretation that Compsognathus longipes had only two phalanges, rather than the expected complement of three, in digit II. This work also identifies a unique suite of metacarpal I morphologies that are used to diagnose a subclade among species often referred to as 'Compsognathidae'. These features are used to construct an apomorphy-based definition of a new clade name: Compsognathidae.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 149 , 569–581.     

Colloidal crystal-like structure of sporopollenin in the megaspore walls of Recent Selaginella and similar fossil spores

HEMSLEY, A. R., COLLINSON, M. E. & BRAIN, A. P. R., 1992. Colloidal crystal-like structure of sporopollenin in the megaspore walls of Recent Selaginella and similar fossil spores. TEM and SEM studies of iridescent fossil Erlansonisporites and Recent Selaginella spores reveal a wall composed of three regions. The central region consists of close-packed particles in a semi-crystalline arrangement. This organization is compared with that of aggregated Iridoviridae, prolamellar bodies, lipid micelles and precious opal. Our observations suggest that the structure of this wall region (and that of the remaining regions) can be explained by derivation from colloidal mixtures. It is concluded that colloids and their precursors may play a far more significant part in spore and pollen wall structure than was previously believed.     

Development, structure and function of rhinoceros enamel

Vertical enamel prism decussation in the inner-layer enamel of rhinoceroses occurs as the result of vertical translation, in opposite senses, of zones of ameloblasts, which begins very shortly after amelogenesis commences at the enamel-dentine junction. Prisms in the centre of the decussating zones are stacked in the Pattern 3 arrangement. Zone boundary prisms adopt intermediate orientations, are locally nearly perpendicular to the enamel surface, and have a cylindrical, Pattern 1 cross-section. Decussation also continues in the outer-layer enamel, but the prisms all have occlusal-going courses: the occlusal-going zones of the inner enamel continue as the more occlusally oriented zones of the outer layer. Abrasion resistance to diamond polishing and soft abrasive projectile erosion (air-polishing with NaHCOs) and resistance to ion beam erosion is greater with distance from the nearest prism boundary discontinuity. Polished surface areas containing longitudinally sectioned prisms are more prone to 'air-polishing' and 'airbrading' erosion than areas with transversely sectioned prisms. These observed relationships fully explain the relief developed at natural wear surfaces.