In vitro Study of the Survival, Reproduction and Morphology of Daphnia pulicaria irradiated with a Low Energy Laser

F Zaldivar ,M Paulin,Saucedo González ,Jorge Mulia-Rodríguez ,Lourdes Romero ,J.a Monreal Montoya ,José Fernando Méndez-Sánchez ,L.a Mandujano ,D Osorio-González

doi:10.15415/jnp.2018.61019

Abstract

Daphnia is a genus of crustaceans that is representative of freshwater communities. The species exhibit a high sensitivity to a wide range of toxic compounds so that they have been used internationally as biomonitors in toxicity tests to evaluate ecosystem conditions such as water quality. It is also a model genus in genetics, epigenetics and reproductive ecology. In this work, we used Daphnia pulicaria as a model to measure the effects of low-energy laser irradiation on survival, reproduction, and morphology variables of parental organisms and their offspring. We used (1) a single clone line of organisms to eliminate interindividual genetic variability; (2) individuals from more than 50 generations after the clone line was established, and offspring from the third brood onwards to dissipate maternal and epigenetic effects, and (3) neonates, those individuals of the species that have less than 48 hours of life, because they are the most sensitive stage to optical stimuli. We analyzed number of deaths, longevity, age at first reproduction, number of offspring per week, number of total offspring during all their life cycle, body size, size of the antennules, and length of the apical spine of the 4th and 5th brood of the irradiated individuals, who were exposed to a blue laser stimulus of 405 nm for 25 minutes with a power of 40 mW at a distance of 50 cm, compared to those of the control (non-irradiated) group.

Highlights

Daphnia is worldwide considered a model organism in genetics, epigenetics and reproductive ecology experiments aside from being an excellent toxicity bioindicator in aquatic environments since they are the main representatives of the freshwater communities
If the environmental conditions are ideal, Daphnia will carry out its reproduction through a parthenogenetic or asexual cycle, whereas when the environmental conditions are disturbed, its reproductive cycle will change to a sexual one
Daphnia exilis, Daphnia pulex, Ceriodaphnia dubia and Moina macrocopa are used as toxicological models to measure the median lethal concentration (LC50), of agricultural and industrial chemical products [2]

Summary

Introduction

Daphnia is worldwide considered a model organism in genetics, epigenetics and reproductive ecology experiments aside from being an excellent toxicity bioindicator in aquatic environments since they are the main representatives of the freshwater communities. By exhibiting high sensitivity to a wide range of toxic compounds, they have been internationally used in toxicity tests to measure and evaluate the conditions of an ecosystem. The toxins tend to accumulate in the flea body, and their subsequent effect is reflected as oxidative stress or damage. This property can be quantified through specific biomarkers, including antioxidant enzymatic defenses such as superoxide dismutase and catalase activity which are considered the first and second line of defense against reactive oxygen species. In aquatic species, there is a close relationship between the increase in lipid peroxidation and oxidative deterioration [3]

Methods

Results

Conclusion