Richard Woltereck first described the concept of Reaktionsnorm (norm of reaction) in his 1909 paper 'Weitere experimentelle Untersuchungen uber Art-veranderung, speziell uber das Wesen quantitativer Artunterschiede bei Daphniden' ('Further investigations of type variation, specifically concerning the nature of quantitative differences between varieties of Daphnia'). This concept refers to the ways in which the environment can alter the development of an organism, and its adult characteristics. Woltereck conceived of the Reaktionsnorm as the full range of potentialities latent in a single genotype, evocable by the environmental circumstances of a developing organism. Biologists used variants of Woltereck's concept of Reaktionsnorm, often called the reaction norm or norm of reaction, throughout the twentieth century in attempts to explain how developmental responses to the environment can evolve, and even alter the tempo and direction of evolutionary change.

The transcriptome of an organism is a collection of the various messenger RNAs that the genes of an organism produce. As the level of gene expression is different between different tissues of an organism, understanding the transcriptome serves as a way to better understand the differences between the functions and abilities of tissues and cells in an organism. This understanding of the transcriptome can aid further research in targeted disease treatments and indentifying new biomarkers. This study aims to gather the transcriptome from various tissues of the organism Daphnia pulex. This will be done by using a combination of single cell RNA sequencing (scRNA-seq), which involves the isolation and sequencing of single cells, and single nuclei RNA sequencing (snRNA-seq), which involves the isolation and sequencing of single nuclei. Here we show the viability of isolating single cells and single nuclei from various Daphnia pulex tissues using different techniques and enzymes including trypLE, trypsin EDTA, accutase, etc by using microscopy and automatic cell counting. The results show that each tissue is best isolated using different techniques.