Multiplication cellulaire et production lipidique en culture in vitro chez Taphrina insititiae et Taphrina pruni, parasites de Prunus domestica

Cellular Multiplication and Lipid Synthesis during in vitro Culture of Taphrina insititiae and Taphrina pruni, Parasites of Prunus domestica. Two Taphrina species were grown on “yeast extract/glucose” and harvested at regular intervals. Their growth was estimated by dry mycelial weight and cell nitrogen. Lipids were recovered and measured by weighing. Phospholipids, which form the major portion of polar lipids, were measured by phosphorus assay. Lipidic and nitrogenous products were studied with regard to the evolution of the cultures during the phase of active growth. The cells accumulated fats, but during the phase of autolysis, fat content decreased. Production of nitrogenous components was maximal during the autolytic phase. Phospholipids varied as nitrogenous and inversely to neutral lipids. There was apparently an antagonism between nitrogen assimilation and synthesis of neutral lipids. Different functions of neutral and polar lipids may be involved, so that the former act as a reserve material and the latter represent an essential structural cell constituent. Fatty acids were analysed by gas liquid chromatography at various culture periods. Fatty acids from polar as well as those from neutral lipids exhibited great variations with regard to culture evolution. The ratio insaturated/saturated fatty acids is greater in polar lipids than in neutral lipids. These variations are discussed with regard to their consequences for the function of cell membranes.     

Les larves chétosphères de polychètes: position systematique et description de nouveaux types

A series of plankton net samples (200 μm mesh width) was collected in the New Caledonian lagoon. From observations by scanning electron microscopy, six larval forms of chaetosphaera are described for the first time. In spite of criticism concerning the use of morphology of setae, the features of transitional larval setae are the main criterion for distinguishing these forms. Nine criteria are used: (1) arrangement of fascicles with regard to the body—pen as a fan and transverse or tightened and parallel to the body; (2) arrangement of fascicles with regard to the dorsal side—entirely or partly sheltered; (3) number of morphological types of setae; (4) number of setae in the fascicles; (5) general morphology—capillary and straight or curved and spiny or as blade-shaped sword; (6) cross section of the setae; (7) arrangement of spines; (8) morphology of distal end; (9) colour. It appears likely that chaetosphaera larvae belong to species of the genera Scolelepis, Dispio or Australospio as defined by Blake & Kudenov and not to Laonice cirrata, as previously thought. In order to display this difference, the larvae of Laonice sp. are also illustrated. Diagnosis of chaetosphaera may be provisionally based on the following features: prostomium pointed; larvae curled to the ventral side; dorsal side without chromatophores; notopodial setal bundles open as a fan on each side and sheltering, at least in part, the dorsal side. Une série de prélèvements au filet à plancton (200 μm de vide de maille) est réalisée dans le lagon de Nouméa, Nouvelle Calédonie. Six formes de larves chetospheres d'Annélides Polychètes sont décrites par observation au microscope électronique à balayage. Les caractères diffèrentiels reposent principalernent sur la morphologie des soies provisoires. Neuf criteres sont utilisés: (1) disposition des faisceaux par rapport au corps—en éventail et transversale ou fermée et parallele au corps; (2) disposition des faisceaux sur la face dorsale—cette dernière peut être entièrement ou partiellement protégée; (3) nombre de types morphologiques de soies; (4) nombre de soies dans un faisceau; (5) morphologie générale—capillaire, droite, avec ou sans épines ou bien courbée et épineuse ou bien aplatie en forme de lame de sabre; (6) section transversale de la soie; (7) disposition des épines; (8) morphologie de la partie distale; (9) coloration. II resort de cette étude qu'il est maintenant nécessaire de rapporter les larves du type chéAtosphère—au moins certaines d'entre elles—à des espèces appartenant aux genres Scolelepis, Dispio ou Australospio tels qu'ils sont définis par Blake & Kudenov. Correlativement la correspondance entre les chétosphères et les larves de Laonice cirrata ne semble pas confirmée. La reconnaissance des larves chétosphères peut être provisoirement basée sur les caractères suivants: prostomium pointu, corps enroulé autour de la face ventrale, tégument dorsal sans chromatophores, faisceaux de soies notopodiales ouverts en éventail et protégeant au moins en partie la face dorsale.     

Consequences of an amphibian malformity for development and fitness in complex environments

1. Environmental stressors have both lethal and sublethal effects, such as altered developmental rates and the induction of malformations. Ecological interactions, including predation and competition, often amplify such effects, for instance by inducing behavioural changes that increase susceptibility to the stress. 2. Using experimental mesocosms, we asked whether the density of conspecific competitors and predation risk from larval water beetles (Dytiscus spp.) affect the development of malformations in tadpoles of the wood frog (Rana sylvatica). We also examined whether such malformities increase the susceptibility of tadpoles to predation. 3. The risk of predation decreased the frequency of malformities in both low‐ and high‐density treatments, although this effect was greater at low density. Behavioural observations suggested that reductions in activity by amphibian larvae induced by predators mediated these responses by decreasing cumulative exposure to ultraviolet‐B radiation, the putative stressor causing the observed malformity. These results suggest that predators can reduce negative impacts of stressors by inducing behavioural changes in prey organisms. 4. Malformed individuals were twice as vulnerable to predators as non‐malformed individuals, suggesting that sublethal effects can ultimately cause increased mortality.     

Observations on a Rare Ciliate, Discomorphella pectinata (Levander, 1894) Corliss, 1960

ABSTRACT. Specimens of the rare ciliate Discomorphella pectinata (Levander, 1894) Corliss, 1960 were impregnated with silver nitrate in 1963. The body is discoid, about 60 μ m long, laterally compressed and adorned with long spines. The somatic kineties on the right and left sides are sparse, sometimes disorganized, and locally without cilia. The oral zone has a complex infraciliature that lies above two series of ventral kineties and below a large, visor-like, epistomial fringe. The arrangement of this fringe is similar to that observed in some other heterotichous ciliates, notably members of the Metopidae and Caenomorphidae.