ALBERT

Notes: . When a streptomycin-bleached mutant of Euglena gracilis strain Z was cultured in the dark at 33, 26, or 15°C, the content of paramylon was higher at lower growing temperature while that of wax esters was higher at higher temperature. Transfer of the cells grown at 33°C–15°C decreased the wax ester content while increasing the paramylon content; transfer in the reverse direction caused reverse changes. On incubation with labeled acetate, the cells grown at 33°C showed more distribution of radioactivity in wax esters than the cells grown at lower temperatures. Apparently the two energy-reserve substances have different physiological functions.

Notes: The sessiline peritrich Ellobiophrya conviva n. sp. is described from marine ectoprocts of the genus Bugula, the first report of an ellobiophryid on bryozoan hosts. The new species is distinguished from others of its genus by its different body proportions, size, host, and structure of the clasping holdfast (for which the new name cinctum is chosen). Ellobiophrya conviva has been found only on B. neritina and B. turrita and shows a marked seasonal cycle of abundance. The family Ellobiophryidae Chatton & Lwoff is revised on the basis of new information provided by E. conviva, with the single species of the genus Clausophrya removed to Ellobiophrya as E. oblida Naidenova & Zaika n. comb. The genus Caliperia Laird remains unchanged. The two genera of the revised family are distinguished from one another by differences in the structure of the cinctum. Hypotheses are advanced to explain the morphogenesis of the cinctum and the evolution of ellobiophryids from other peritrichs.

Notes: The spatial and seasonal distribution of Paramecium bursaria in two small Indiana ponds was studied using a sampling grid. Very small (5.0 ml) samples were taken so that the individual microhabitats could be studied. The results were evaluated in comparison to the data collected for the P. aurelia complex collected in the same manner and at the same sites. It was found that P. bursaria exist in a clumped distribution, but that the distribution was not very different from random. Paramecium bursaria also exist at the surface and at the mud-water interface. Temperature does not seem to play a statistically significant role in determining population size. The breeding system of P. bursaria is optimized for an outbreeding population of low density. In comparison, the species of the P. aurelia complex exist in a very clumped distribution, are found only at the mud-water interface, and are inbreeders. The evolutionary strategies of the two types of paramecia are discussed.

Notes: L'étude du caractère planctonique de différentes spores d'Actinomyxidies montre une complexité croissante dans leur adaptation au milieu aquatique. Au contact de l'eau, les trois cellules épéisporales de chaque spore se transforment en flotteurs de forme différente suivant les espèces. Ces flotteurs peuvent s'unir entre eux en un style équivelent à un quatrième flotteur ou associer diversement les huit spores issues d'un měme pansporocyste. C'est le cas dans le genre Synactinomyxon dont la diagnose est modifiée pour inclure une deuxième espèce S. Iongicauda n. sp. Un type nouveau est décrit chez lequel la preéence d'ancres à l'extrémité des cellules épisporales permet de maintenir efficacement réunies plusieurs dizaines de spores émises simultanément. Nous avons observé dans les genres Aurantiactinomyxon, Synactinomyxon, Echinactinomyxon l'emission du sporoplasme. II est libére en entier et capable de se déplacer dans l'eau pendant plus d'une heure grǎce à des mouvements amoeboïdes. Chez Aurantiactinomyxon eiseniellae les études ultrastructurales montrent que l'enveloppe du pansporocyste, d'une part, les épispores et les capsules polaires d'autre part sont réalisées à partir de cellules distinctes et profondément modifiées. Quant au sporoplasme, autrefois décrit comme un plasmode avec de nombreuses paires de noyaux, il contient, en fait, des ensembles identiques dont chacun est constitué de l'union d'un noyau satellite et d'une cellule uninucléée.〈section xml:id="abs1-2"〉〈title type="main"〉ABSTRACTThe study of the planktonic character of different Actinomyxidia spores reveals increasingly complex adaptations to an aquatic environment. On contact with water, the three episporal cells of each spore transform into floats, the forms of which differ according to species. These floats can join together so that a fourth type of float is formed, or they can unite in various ways the eight spores originating from the same pansporocyst. This is the case in the genus Synactinomyxon whose diagnosis is modified to include a second species S. Iongicauda n. sp. A new type is described in which the presence of anchors at the extremities of the episporal cells permits several dozen spores that have been emitted simultaneously to be kept together. We have observed the emission of the sporoplasm in the genera Aurantiactinomyxon, Synactinomyxon, and Echinactinomyxon. It is freed completely and for more than an hour is capable of changing its position in the water by amoeboid movements. In the case of Aurantiactinomyxon eiseniellae, ultrastructural studies show that the pansporocyst envelope on the one hand, and the epispores and polar capsules on the other hand, are formed from separate but profoundly modified cells. The sporoplasm, however, sometimes described as a plasmodium with numerous pairs of nuclei, contains, in fact, identical complexes, each consisting of a uninucleate cell united with a satellite nucleus.

Notes: Paramecia detect and accumulate in or disperse from some chemicals. Cells do this by changing frequency of turning and speed of swimming. There are at least two mechanisms by which cells respond: one dependent on ability to turn, one dependent on speed modulation. There are also two classes of chemicals: those that require the cells' ability to turn in order to cause accumulation and dispersal (type I), and those that apparently require only speed modulation (type II). Attractants of type I cause qualitatively similar changes in behavior to repellents of type II and the converse; therefore, assays are needed to distinguish between these two classes of chemicals, despite qualitatively similar behavior of some attractants and repellents. We examined two assays of paramecium chemoresponse, T-maze assay and well test, to understand how the T-maze distinguishes between attractants of type I and repellents of type II and why the well test does not.

Notes: The morphology of spore germination in Didymium nigripes was studied using scanning electron microscopy and Nomarski phase optics. First, the outer spore wall splits, revealing a fibrillar inner wall. Remnants of the inner wall continue to cover the newly emerged amoeba. A single nucleus and a prominent vacuole are visible throughout germination. Germination is more rapid in glucose-peptone-yeast extract than in phosphate buffer. Germination is completely inhibited at 4°C, and is very slow at 18°C. Germination is most rapid at 26°C; at 21°C or 32°C it is slightly slower. Germination is reversibly inhibited by 20 μ/ml cycloheximide, but not by 200 μ/ml 5-fluoro uracil or 200 μ/ml proflavin. It is completely inhibited by 10-3 M Na azide.

Notes: Crithidia fasciculata (Anopheles, Culex, and Nöller strains), C. hutneri, C. luciliae thermophila, and Herpetomonas samuelpessoai were grown in a defined medium with different values of osmolarity at different temperatures. C. fasciculata (all strains) grew best between 300 to 500 mOsm; H. samuelpessoai, 400–500 mOsm; and C. hutneri and C. luciliae thermophila, 500–800 mOsm. At higher temperatures better growth was obtained at the upper osmolarities.

Notes: Crypthecodinium cohnii, a small marine heterotrophic homothallic dinoflagellate, has diversified into a complex of morphologically very similar breeding groups (biological species or sibling species), some of which have become widely dispersed. Membership of two clones in the same sibling species is shown by their sexual compatibility as determined by genetic complementation in zygotes formed from motility mutants derived from the two stocks. Membership in different sibling species may be inferrec when motility mutants of one strain do not complement those of another. Fifty-six clones representing seaweed enrichments from *** geographic sites have been found to belong to 28 sibling species; 35 clones are members of seven wide-ranging biological species, and 21 are single representatives of 21 other breeding groups within the ranges of the others. Of 174 clonal isolates in our possession, 168 conform in size and shape to C. cohnii. Six others which have smaller cells and only one-fifth the standard DNA and chromosome number belong, we believe, to another species. The C. cohnii complex provides a unique opportunity for the study of evolutionary divergence and geographical dispersion of a dinoflagellate.