Biomedical subjects

Fabrizio Erra

Publications and source records attributed to Fabrizio Erra.

4 recordsLinked to original sources

PubMed2004

Cell cycle and behaviour in Euplotes crassus: an attempt at describing the biological relationship between its cellular and organismic natures.

The two-faced nature of protozoa allowed us to study the relationship between cell cycle and behaviour in Euplotes crassus; the former represents one of the most typical cellular traits, the latter is one of the most significant characteristics of an organism. Dividing cells of E. crassus were isolated on a slide and recorded for 11 h: the classic ethographic parameters were calculated every 60 min. The percentage of mobile cells went from 0-100% in the first 2.5 h. This value was maintained for 6.5 h, but from 9 h the value began to drop, reaching 0% at 11 h. The relative frequency of leftward arcs was very high in the first hour, the radius and length of the arcs increased from 1-7 h; velocity showed a similar trend, peaking at 7 h. All our results showed that the behaviour of this ciliate is heavily affected by its cell-division cycle.

Animals↗

PubMedDate not supplied

Not-adaptive behavior of isotropically heated, inert populations of Oxytricha bifaria (Ciliophora, Stichotrichia).

The physiological effects on isotropically heated populations of Oxytricha bifaria cultured at 24 degrees C were investigated. At 34.6 degrees C ciliates became inert, and did not adaptively react to either cold or warm microgradients; they neither moved towards the favorable cold thermal source nor escaped from the unfavorable warm one. The inert oxytrichas were only able to perform the Side-Stepping Reaction (SSR) on the same spot. However, mobile ciliates at 31.6 degrees C reacted to the cold microgradient by immediately orienting themselves towards its source, without accelerating but reducing their SSR frequency. Moreover, in a warm microgradient such ciliates immediately increased their SSR frequency, then moved away from the thermal source. At 34.6 degrees C the behavior of ciliates was not-adaptive--not acting to guide the organisms to more favorable conditions--whereas at 31.6 degrees C it was still clearly adaptive. Therefore, the locomotory inertness of the oxytrichas at 34.6 degrees C was the result of thermal stress rather than their behavioral response to the environmental isotropy, in contrast to populations of the same species made inert at 9 degrees C.

Adaptation, Physiological↗

PubMedDate not supplied

The behaviour of unicellular eukaryotes.

The field of ciliated protozoa behaviour is reconsidered. The simple-complexity of their behaviour is seen in its basic nature and adaptive meaning. The Laboratory Conditions (LABCON) are discussed in comparison with those occurring in nature (NATCON). The nature of the arc, the behavioural element commonly performed by a ciliate, is discussed in detail. Several indexes and rates can perfectly describe the tracks of the ciliates. The behaviour can be considered as a kind of adaptive interface between the environment and the organism.

Adaptation, Physiological↗

PubMedDate not supplied

The locomotion of living organisms. Some hints for an evolutionistic reconsideration of biology's "foregone" topics.

From the analysis of the behaviour it is evidenced that the biological peculiarities of the Hypotrichs depend on the close linking between the adaptive strategies they have found to environmental problems. The loss of the envelope surface of the other ciliates was followed, in the Ciliates evolution, by the acquisition of the "cirrus and membranelle" propulsive logic. Furthermore they acquire a strong-and-easy-to-release adhesion system to creep on the substrate. The eco-ethological approach showed that they are capable of adapting to an environment characterised by new dimensional scales, new micro-environments and also new stimuli.

Animals↗