Adverse effects polystyrene microplastics exert on zebrafish heart - Molecular to individual level.

In the present study the effects of sublethal concentrations of polystyrene microplastics (PS-MPs) on zebrafish were evaluated at multiple levels, related to fish activity and oxidative stress, metabolic changes and contraction parameters in the heart tissue. Zebrafish were fed for 21 days food enriched with PS-MPs (particle sizes 3-12 µm) and a battery of stress indices like DNA damage, lipid peroxidation, autophagy, ubiquitin levels, caspases activation, metabolite adjustments, frequency and force of ventricular contraction were measured in fish heart, parallel to fish swimming velocity. In particular, exposure to PS-MPs caused significant decrease in heart function and swimming competence, while enhanced levels of oxidative stress indices and metabolic adjustments were observed in the heart of challenged species.

Biphasic responses of the honeybee heart to nanomolar concentrations of amitraz.

Amitraz is a pesticide targeting the octopaminergic receptors. In a previous study, octopamine, a biogenic amine, was found to induce a biphasic effect on the honeybee heart, inhibition at low concentrations and excitation at high concentrations. Furthermore, the honeybee heart was found to be far more sensitive to octopamine compared to other insect hearts.

The force of the spontaneously contracting zebrafish heart, in the assessment of cardiovascular toxicity: application on adriamycin.

The heart of the zebrafish has been used extensively to assess the cardiotoxic effect of compounds, using the frequency of heart contractions as the main index of cardiac response to drugs. In this study, the force and the frequency generated by the spontaneously contracting zebrafish heart, isolated in saline, were found to be 0.87 ± 0.

The bite of the honeybee: 2-heptanone secreted from honeybee mandibles during a bite acts as a local anaesthetic in insects and mammals.

Honeybees secrete 2-heptanone (2-H) from their mandibular glands when they bite. Researchers have identified several possible functions: 2-H could act as an alarm pheromone to recruit guards and soldiers, it could act as a chemical marker, or it could have some other function. The actual role of 2-H in honeybee behaviour remains unresolved.

Octopamine--a single modulator with double action on the heart of two insect species (Apis mellifera macedonica and Bactrocera oleae): Acceleration vs. inhibition.

The effects of octopamine, the main cardioacceleratory transmitter in insects, were investigated, in the isolated hearts of the honeybee, Apis mellifera macedonica, and the olive fruit fly, Bactrocera oleae. Octopamine induced a biphasic effect on the frequency and force of cardiac contractions acting as an agonist, with a strong acceleratory effect, at concentrations higher than 10(-12)M for the honeybee and higher than 50×10(-9)M for the olive fruit fly. The heart of the honeybee is far more sensitive than the heart of olive fruit fly.