Estimation of Cochlodinium polykrikoides growth potential using a dialysis membrane.

We developed a test to measure the growth potential of C. polykrikoides using a dialysis membrane and artificial seawater. Nitrite nitrogen and inorganic phosphorus in the medium were almost completely removed when the medium was dialyzed against artificial seawater for five or more 6-hour cycles using a dialysis membrane (Spectrum's Spectra/Por 7 Membrane) with a molecular-weight cut-off of 50,000, regardless of the presence of C. polykrikoides. The phytoplankton grew well even after dialysis. To estimate the growth potential of C. polykrikoides, a minimum initial concentration of > 100 cells/ml is required. Methods using short-term starvation culturing of C. polykrikoides to measure growth potential were determined to be ineffective; instead, controlled tests using artificial seawater are recommended. The dialysis membrane used in this study can also be employed to measure the algal growth potential of other phytoplankton species.

Morphology and ecology of the planktonic diatom Palmerina hardmaniana (Greville) Hasle in southern Brazil / Morfologia e ecologia de diatomácea planctônica Palmerina hardmaniana (Greville) Hasle no Sul do Brasil

The diatom Palmerina hardmaniana (Greville) Hasle presents a wide geographical distribution in neritic tropical and subtropical regions. In the present work we analyzed plankton samples collected monthly between 1995 and 2007 at the surf zone of Cassino Beach, RS (32º 12' S and 52º 10' W), and in winter 2005 and summer 2007 at the continental shelf and slope in southern Brazil, Santa Marta Grande Cape, SC and Albardão-Chuí, RS regions (28º 23'-33º 07' S and 48º 41'-52º 26' W). We present the detailed morphological description of P. hardmaniana, and the first study including electron scanning microscope observations for material from the southwestern Atlantic Ocean. The morphometric data confirm the identity of the species in all its ultra-structural details. Palmerina hardmaniana was only observed in summer-autumn months with low cell density (< 500 cells.L-1) at both Cassino Beach surf zone and coastal shelf stations. The warm water temperature (18-29 ºC) indicates the most probable origin of its inoculum are tropical/subtropical regions. Salinities of 23-36 and the relatively high silicate content indicate the importance of the terrestrial discharge during occasions when P. hardmaniana was observed, probably with influence on the nutrient availability. We emphasize that the species was not cited previously for Argentinean and Uruguayan waters and suggest that the southern Brazilian region is close to the southern geographical distribution limit of Palmerina hardmaniana in the southwestern Atlantic Ocean.

A diatomácea Palmerina hardmaniana (Greville) Hasle apresenta ampla distribuição geográfica em águas neríticas tropicais e subtropicais. No presente trabalho foram analisadas amostras de plâncton, coletadas mensalmente entre 1995 e 2007 na zona de rebentação da Praia do Cassino, RS (32º 12' S e 52º 10' W), e no inverno de 2005 e verão de 2007 na plataforma continental e talude do sul do Brasil, na região de Cabo de Santa Marta Grande, SC e Albardão-Chuí, RS (28º 23'-33º 07' S e 48º 41'-52º 26' W). Apresentamos a descrição detalhada de P. hardmaniana, como primeiro estudo com observações de microscopia eletrônica de varredura para material coletado em águas do Oceano Atlântico Sul Ocidental. Os dados morfológicos analisados confirmam a identificação da espécie em todos os seus detalhes estruturais. Palmerina hardmaniana somente foi observada nos meses de verão/outono, em baixa densidade (< 500 células.L-1) na zona de arrebentação da Praia do Cassino bem como em estações costeiras da plataforma continental. A temperatura quente da água (18-29 ºC), indica as águas tropicais/subtropicais como possível origem do inóculo de P. hardmaniana no verão-outono. A salinidade entre 23 e 36 e o teor relativamente alto de sílica também indicam a importância da descarga terrestre nas ocasiões de presença de P. hardmaniana, exercendo importante papel no suprimento de nutrientes. Salienta-se que a espécie não é citada em águas argentinas e uruguaias e assim, sugerimos que o extremo sul do Brasil representa aproximadamente o limite sul da distribuição geográfica de Palmerina hardmaniana no Oceano Atlântico Sul Ocidental.

Improvement of silver impregnation technique (Protargol) to obtain morphological features of protists ciliates, flagellates and opalinates

The research on ciliates, flagelates and opalinates have been widespread by the utilization of techniques employing silver impregnation (Protargol), modified by several authors. However, these are time consuming and its results are variable. The present work is a variant of the technique described by Tuffrau (1964, 1967) showing some adaptations made in our laboratory. The organisms can be preserved by different fixatives (alcoholic Bouin, Stieve's fluid, 2.5 percent glutaraldehyde and others) and then rinsed in destilled water followed by a fast clarification by 3 percent sodium hypochloride. If the organism is very sensitive to hypochloride, 4 percent sodium lauryl sulfate may be used and then washed 3 times in distilled water. The protista can be adhered to the glass slides with Mayer's glycerinated-albumin (1 glycerin vol. to 1 or 2 albumin vol.), diluted in water at a proportion of 1:10 Cv/v., or with 1 percent polylysine followed by fast washes with distilled water. After the slide preparation, they were covered with a layer of 0,8 percent Silver proteinate. Right after that, the slide has to be placed in a glass tray lined with moist tissue and covered to prevent the proteinate to dry. The tray was placed in a incubator at 40º-50ºC for 30 minutes. The slides are rinsed for 1 minute. with warm (35ºC) distilled water. The development of the material should be done with 0.4 percent hydroquinone with a maximum incubation time of 1 minute. It should be developed gradually, controlling the silver impregnation intensity by observation under optical microscope. Next, rinse in distilled water for 1 minute, and then, fix in 2,5 percent Sodium thiosulfate. Rinse the slide for two minutes before dehydrating it in an alcoholic serial 50-100º. Finally rinse the slides in xylene. Mount the slides with Entellan MerckTM or Canada balsam

Cytological findings suggesting sexuality in Phytomonas davidi (Protozoa: Kinetoplastida)

On few occasions, Phytomonas davidi (McGhee & Postell isolate) cultures in LIT (liver infusion-tryptose) medium around 27ºC presented, as seen in Giemsa-stained smears, a set of pecular morphological features, among them being noticeable the pairs of apposed cells attached by their posterior ends, where occured a stained line and/or a dilatation, usually bulb-like in shape; sometimes this dilatation could occupy one of the cells or hold both together. In some pairs, the nucleous of each parasite seemed migrating towards the other, entering into such dilatation; in others, both nuclei were inside it, sometimes in close proximity or seeming fused; peculiar chromatin arrangements involving both nuclei were occasionally observed. Several mono or binucleate round forms bearing one or two flagella, as well as flagellate slender cells without nucleous were concomitantly seen there. In some instances, an intriguing small stained body, occurred beside a single large nucleous, either in pairs presenting the bulb-like structure or in round cells. There cytological findings seemed steps of a dynamic process suggesting sexuality, since in several of them nuclear interactions following fusion of two parasites appeared to occur.