Comparison and Validation of Ichthyoplankton DNA Extraction Methods.

Diouri Lamia,Soukri Abdelaziz,Baibai Tarik,Malki Mohamed,Uwiringiyeyezu Théophile,Abdelouahab Hinde

doi:10.3390/mps4040087

Abstract

Ichthyoplankton is the cluster of planktonic organisms that consists of fish eggs and larvae. These planktonic stages belong to the temporary zooplankton, representing future exploitable stocks. The study of the early ontogenesis of fish plays a key role in the understanding and evaluation of these populations through the study of their abundance and their spatio-temporal distribution. To better understand and protect these fisheries resources, it is essential to identify the different stages of fish embryonic development. This identification is usually performed using the classical method, based on morphological criteria under a binocular magnifying glass; however, this methodology is not always sufficient and is time consuming and, therefore, it is necessary to rely increasingly on molecular tools. The major problem with these tools is the yield and quality of the nucleic acids extracted from ichthyoplankton, especially in the case of eggs, which are small. Several methods have been used for DNA extraction from ichthyoplankton, either automated or manual, but very often from larvae or adults. In the present work, five fish egg DNA extraction protocols were compared based on their DNA yield and extraction quality, verified by agarose gel electrophoresis and quantitative PCR amplification. The results showed that extraction by our heat-protocol for direct PCR (Hp-dPCR) presents the simplest and cheapest protocol of all the kits used in this study, providing a sufficient quantity and quality of nucleic acids to be used for PCR amplification, and being within the reach of third world laboratories that often do not have sufficiently large budgets to obtain automated kits.

Highlights

Fish eggs and larvae are part of the ichthyoplankton. These planktonic stages belong to the temporary zooplankton or meroplankton, representing future exploitable stocks [1]
To better understand and protect these fisheries resources, it is necessary to identify the different stages of fish embryonic development
The identification of ichthyoplankton is usually carried out based on morphological criteria under a binocular magnifying glass, according to such features as the size and shape of the eggs, the pigmentation of the embryo, the presence or absence of adipose drops, the yolk structure, and the size of the perivitelline space [2]

Summary

Introduction

Fish eggs and larvae are part of the ichthyoplankton. These planktonic stages belong to the temporary zooplankton or meroplankton, representing future exploitable stocks [1].The study of the early life stages of ichthyoplankton plays a major role in understanding the ecology and evolution of fish faunas and their constituent populations and is an important component in fisheries resource assessment models through the study of fish fauna abundance and spatio-temporal distribution [2]. The identification of ichthyoplankton is usually carried out based on morphological criteria under a binocular magnifying glass, according to such features as the size and shape of the eggs, the pigmentation of the embryo, the presence or absence of adipose drops, the yolk structure, and the size of the perivitelline space [2]. This method is not always sufficient and is time-consuming [3] and, it is necessary to make increasing use

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Discussion

Conclusion