Lucky rugose corals on crinoid stems: unusual examples of subepidermal epizoans from the Devonian of Morocco

Berkowski, B & Klug, C. 2011: Lucky rugose corals on crinoid stems: unusual examples of subepidermal epizoans from the Devonian of Morocco. Lethaia, Vol. 45, pp. 24–33. In the fossil record, evidence for true epizoans, i.e. living animals inhabiting other living host‐animals, is rather rare. A host reaction is usually needed to proof the syn vivo‐settling of the epizoan. Herein, we provide a first report of such an epizoan biocoenosis from various strata of the Early Devonian of Hamar Laghdad, the world‐renowned Moroccan mud‐mound locality. In this case, solitary rugose corals settled as larvae on crinoid stems, perhaps at a spot where the epidermis was missing for some reason (injury, disease). Both the crinoid and the coral began to grow around each other. By doing so, the affected crinoid columnals formed a swelling, where ultimately only an opening slightly larger than the coral orifice remained. We discuss both macroecological and small‐scale synecological aspects of this biocoenosis. The coral profited from its elevated home because it reached into more rapid currents providing the polyp with more food than at the densely populated seafloor, which was probably covered by a coral‐meadow around the mounds and hydrothermal vents. □Corals, crinoids, Early Devonian, epizoans, Morocco, Rugosa.     

The Oxidation of Malate by Isolated Turnip (Brassica napus L.) Mitochondria: II. THE MALATE-OXIDIZING ENZYMES, NUMBER AND LOCATION

The enzymes of malate oxidation in turnip mitochondria havebeen partially purified and some of their properties studied.Turnips contain a cytoplasmic malate dehydrogenase and two mito-chondrialmalate dehydrogenases. These are all distinct isoenzymes withdifferent immunblogical properties but similar molecular weights.The K_m for malate is relatively high (8.3 mM) in the mito-chondrialenzymes. One of the mitochondrial enzymes is located in thematrix while the other is membrane-bound but within the matrixcompartment. This latter enzyme, which retains its NAD and activitywhen submitochondrial particles are prepared, is responsiblefor the first phase of malate oxidation in submitochondrialparticles. Two malic enzymes were isolated: one, an NADP enzyme, is a minorcomponent and was not studied further; the other, immunologicallydistinct from the malate dehydrogenases, is probably locatedin the matrix compartment. The K_m for malate oxidation (1.4mM) is relatively low. This malic enzyme which apparently lacksOAA decarboxylase activity is NAD-specific but is unstable.The possibility of multiple malic enzymes is discussed. Themalic enzymes are responsible for the second NAD-requiring phaseof malate oxidation in submitochondrial particles.     

Studies on the Glasshouse Carnation: Effects of Light and Temperature on the Growth and Development of the Flower

Experiments were concerned with the growth and development offlowers of carnation (Dianthus) var. White Sim from the timethe flower buds became visible up to anthesis. Rates of growthin size of the flower were decreased by either low temperaturesor low light intensities but only low temperatures caused anappreciable delay in anthesis. Effects of low light intensitycould be simulated by partial defoliation and appeared to bemediated through effects on photosynthesis. Temperature, however,acted directly on processes occurring in the flower bud. The rate of development of the flower, in the sense of progresstowards anthesis, appeared to be independent of levels of assimilatesavailable for growth. It is suggested that processes controllingdevelopment in the flower regulate the partition of assimilatesbetween the flower and the remainder of the shoot system. Seasonal variations in rates of flower development under glasshouseconditions are considered to be largely attributable to variationsin the temperature of the flower buds.