Swimming patterns of the quadriflagellate Tetraflagellochloris mauritanica (Chlamydomonadales, Chlorophyceae).

Chlamydomonadales are elective subjects for the investigation of the problems related to locomotion and transport in biological fluid dynamics, whose resolution could enhance searching efficiency and assist in the avoidance of dangerous environments. In this paper, we elucidate the swimming behavior of Tetraflagellochloris mauritanica, a unicellular-multicellular alga belonging to the order Chlamydomonadales. This quadriflagellate alga has a complex swimming motion consisting of alternating swimming phases connected by in-place random reorientations and resting phases.

Water monitoring: automated and real time identification and classification of algae using digital microscopy.

Microalgae are unicellular photoautotrophs that grow in any habitat from fresh and saline water bodies, to hot springs and ice. Microalgae can be used as indicators to monitor water ecosystem conditions. These organisms react quickly and predictably to a broad range of environmental stressors, thus providing early signals of a changing environment.

A second rhodopsin-like protein in Cyanophora paradoxa: gene sequence and protein expression in a cell-free system.

Here we report the identification and expression of a second rhodopsin-like protein in the alga Cyanophora paradoxa (Glaucophyta), named Cyanophopsin_2. This new protein was identified due to a serendipity event, since the RACE reaction performed to complete the sequence of Cyanophopsin_1, (the first rhodopsin-like protein of C. paradoxa identified in 2009 by our group), amplified a 619 bp sequence corresponding to a portion of a new gene of the same protein family.

Automatic and real time recognition of microalgae by means of pigment signature and shape.

Microalgae are unicellular photoautotrophic organisms that grow in any habitat such as fresh and salt water bodies, hot springs, ice, air, and in or on other organisms and substrates. Massive growth of microalgae may produce harmful effects on the marine and freshwater ecological environment and fishery resources. Therefore, rapid and accurate recognition and classification of microalgae is one of the most important issues in water resource management.

Tetraflagellochloris mauritanica gen. et sp. nov. (Chlorophyceae), a New Flagellated Alga from the Mauritanian Desert: Morphology, Ultrastructure, and Phylogenetic Framing.

Morphological, ultrastructural, and molecular-sequence data were used to assess the phylogenetic position of a tetraflagellate green alga isolated from soil samples of a saline dry basin near F'derick, Mauritania. This alga can grow as individual cells or form non-coenobial colonies of up to 12 individuals. It has a parietal chloroplast with an embedded pyrenoid covered by a starch sheath and traversed by single parallel thylakoids, and an eyespot located in a parietal position opposite to the flagellar insertion.

Fundamental questions and concepts about photoreception and the case of Euglena gracilis.

The ability to sense light can be considered the most fundamental and presumably the most ancient property of visual systems. This ability is the basis of phototaxis, one of the most striking behavioral responses of motile photosynthetic microorganisms (i.e.

Chemistry, physico-chemistry and applications linked to biological activities of β-glucans.

β-Glucans is the common name given to a group of chemically heterogeneous polysaccharides. They are long- or short-chain polymers of (1-->3)-β-linked glucose moieties which may be branched, with the branching chains linked to the backbone by a (1-->6)-β linkage. β-(1-->3)-Glucans are widely distributed in bacteria, algae, fungi and plants, where they are involved in cell wall structure and other biological function.

A rhodopsin-like protein in Cyanophora paradoxa: gene sequence and protein immunolocalization.

Here, we report the DNA sequence of the rhodopsin gene in the alga Cyanophora paradoxa (Glaucophyta). The primers were designed according to the conserved regions of prokaryotic and eukaryotic rhodopsin-like proteins deposited in the GenBank. The sequence consists of 1,272 bp comprised of 5 introns.

MICROSPECTROPHOTOMETRY AS A METHOD TO IDENTIFY KLEPTOPLASTIDS IN THE NAKED FRESHWATER DINOFLAGELLATE GYMNODINIUM ACIDOTUM(1).

A relatively small number of freshwater dinoflagellates are involved in symbiotic association with cryptophytes. The chloroplasts of the cryptophytes are retained by the dinoflagellate and give it the characteristic phycobilin pigmentation, either phycoerythrin or phycocyanin. The pigment characterization of the retained chloroplasts can give precise and accurate information about the type of cryptophyte preyed upon by the dinoflagellate.

In vivo absorption spectra of the two stable states of the Euglena photoreceptor photocycle.

Euglena gracilis possesses a simple but sophisticated light detecting system, consisting of an eyespot formed by carotenoids globules and a photoreceptor. The photoreceptor of Euglena is characterized by optical bistability, with two stable states. In order to provide important and discriminating information on the series of structural changes that Euglena photoreceptive protein(s) undergoes inside the photoreceptor in response to light, we measured the in vivo absorption spectra of the two stable states A and B of photoreceptor photocycle.

Low-resolution characterization of the 3D structure of the Euglena gracilis photoreceptor.

This paper deals with the first characterization of the structure of the photoreceptive organelle of the unicellular alga Euglena gracilis (Euglenophyta). This organelle has a three-dimensional organization consisting of up to 50 closely stacked membrane lamellae. Ionically induced unstacking of the photoreceptor lamellae revealed ordered arrays well suited to structural analysis by electron microscopy and image analysis, which ultimately yielded a low-resolution picture of the structure.

Microspectroscopy of the photosynthetic compartment of algae.

We performed microspectroscopic evaluation of the pigment composition of the photosynthetic compartments of algae belonging to different taxonomic divisions and higher plants. The feasibility of microspectroscopy for discriminating among species and/or phylogenetic groups was tested on laboratory cultures. Gaussian bands decompositions and a fitting algorithm, together with fourth-derivative transformation of absorbance spectra, provided a reliable discrimination among chlorophylls a, b and c, phycobiliproteins and carotenoids.

Absorption microspectroscopy, theory and applications in the case of the photosynthetic compartment.

We performed microspectroscopic evaluation of the pigment composition of the photosynthetic compartments of both algae and higher plants. The feasibility of microspectroscopy for discriminating among species and/or phylogenetic groups was tested on laboratory cultures. Gaussian bands decompositions, and a fitting algorithm, together with fourth-derivative transformation of absorbance spectra, provided a reliable discrimination among chlorophylls, phycobiliproteins and carotenoids.

A short flagella mutant of Dunaliella sallina (Chlorophyta, Cholorophyceae).

Dunaliella salina (Chlorophyta, Chlorophyceae) is a unicellular wall-less biflagellate alga. In this paper we describe a spontaneous mutant of D. salina, isolated from wild type cultures, which is characterized by very short flagella.

Fluorescence behavior of Euglena photoreceptor.

To provide new information on the series of structural changes that Euglena photoreceptive proteins undergo inside the photoreceptor in response to light, we measured in vivo emission fluorescence spectra in the stable intermediates of its photocycle. Our emission spectra give a certain indication that fluorescent proteins are present in the Euglena photoreceptor and that they undergo a photocycle. On the basis of our data, we suggested that at least two stable intermediates, one of which is fluorescent, can be discriminated at room temperature and with our time resolution.