Aminotransferase and the Production of Alanine During Hyperosmotic Stress in Paramecium calkinsi

When Paramecium calkinsi encounter hyperosmotic stress, intracellular free alanine increases. In vivo assays indicate that the reaction catalyzed by alanine aminotransferase contributes to the build up of alanine in response to hyperosmotic shock. ¹⁴C-pyruvate is converted to ¹⁴C-alanine in cells grown axenically at 200 mosm. When shifted to 600 mosm, the rate of conversion of pyruvate to alanine increases, and conversion at either 200 or 600 mosm is blocked by 1 mM aminooxyacetic acid (AOA), an inhibitor of aminotransferase. Intracellular free alanine increase is partially inhibited by AOA, and AOA prevents cells living in fresh water from acclimating to higher salinities, an indication that the increase in intracellular alanine is physiologically significant.     

A METHOD FOR THE INVESTIGATION OF THE SHELL STRUCTURE OF NEWLY SETTLED LIMPETS

A method for the preparation and examination of fragile andparticularly small (sub-millimetre) shells is presented, basedupon the geologist's method for the viewing of fine sectionedrock. (Received 19 February 1985;     

Functional innovation through vestigialization in a modular marine invertebrate

Few studies show how morphological vestigialization may facilitate functional innovation. Fewer still describe the co‐occurrence of the derived and more ancestral structures in the same genetic individual. In the present study, we explore that rare instance in a modular (colonial) marine invertebrate. Using laser scanning confocal microscopy with fluorescent staining and behavioural observations, we describe homologous structures in polymorphic modules (zooids) in the bryozoan Bugula flabellata and document the occurrence of previously unreported retractor and circular muscles in the more derived module, the bird's‐head avicularium. In the evolution of a sessile feeding zooid to a moveable nonfeeding zooid with sensory and grasping functions, transformations were effected in the food‐capture apparatus, orificial structures, musculature, and sensory structures. We expand on and clarify previous reports of homologies between ancestral and derived modules in bryozoans and argue that vestigialization and augmentation of homologous structures were coincident with functional innovations in the avicularium. The present study offers rare evidence for the evolution of functional innovation through vestigialization. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 63–74.     

The Translocation of Antibiotics in Higher Plants: I. ISOLATION OF GRISEOFULVIN AND CHLORAMPHENICOL FROM PLANT TISSUE

Griseofulvin and chloramphenicol have been recovered from thetissues of broad-bean plants grown in solutions containing theseantibiotics. Partial separation of the compounds from other constituentsof solvent extracts of plant tissue was effected by counter-currentdistribution in a carbon tetra chloride methanol : water system.Pure griseofulvin and chloramphenicol were then obtained byrecovery of the solute in appropriate tubes followed by chromatographyon an activated alumina column; they were identified by mixedmelting point determinations and comparison of their infra-redspectra. A method for estimating griseofulvin in plant tissue extractsbased on counter current distribution and examination of thefractions spectrophotometrically has been developed, and usedto strike a balance between the gnseofulvin entering the plantand that present in the tissues after treatment. Estimates of chloramphenicol in the tissues by bioassay agreewell with the chemical determinations.