Journal Article

Knockout of juvenile hormone receptor, Methoprene-tolerant, induces black larval phenotype in the yellow fever mosquito, Aedes aegypti

Noh, Mi Young, Zhu, Guan-Heng, Jiao, Yaoyu, Chereddy, Shankar C. R. R., Palli, Subba Reddy

2019

Overview

The yellow fever mosquito, Aedes aegypti, vectors human pathogens. Juvenile hormones (JH) control almost every aspect of an insect’s life, and JH analogs are currently used to control mosquito larvae. Since RNA interference does not work efficiently during the larval stages of this insect, JH regulation of larval development and mode of action of JH analogs are not well studied. To overcome this limitation, we used a multiple single guide RNA-based CRISPR/Cas9 genome-editing method to knockout the methoprene-tolerant (Met) gene coding for a JH receptor. The Met knockout larvae exhibited a black larval phenotype during the L3 (third instar larvae) and L4 (fourth instar larvae) stages and died before pupation. However, Met knockout did not affect embryonic development or the L1 and L2 stages. Microscopy studies revealed the precocious synthesis of a dark pupal cuticle during the L3 and L4 stages. Gene expression analysis showed that Krüppel homolog 1, a key transcription factor in JH action, was down-regulated, but genes coding for proteins involved in melanization, pupal and adult cuticle synthesis, and blood meal digestion in adults were up-regulated in L4 Met mutants. These data suggest that, during the L3 and L4 stages, Met mediates JH suppression of pupal/adult genes involved in the synthesis and melanization of the cuticle and blood meal digestion. These results help to advance our knowledge of JH regulation of larval development and the mode of action of JH analogs in Ae. aegypti.

• Publisher: National Academy of Sciences
• Subject: adults / Aedes - genetics / Aedes - growth & development / Aedes - metabolism / Aedes aegypti / Analogs / Animals / Aquatic insects / Biochemistry / Biological Sciences / Blood / blood meal / Carrier Proteins - genetics / Carrier Proteins - metabolism / Control / CRISPR / CRISPR-Cas systems / Digestion / Embryogenesis / Embryonic growth stage / Fever / gene editing / Gene expression / Gene Expression Regulation, Developmental / Gene Knockout Techniques / Genes / Genomes / Herbivores / Homology / Hormones / humans / Insect Proteins - genetics / Insect Proteins - metabolism / Insecticides / Insects / instars / juvenile hormone receptors / Juvenile hormones / Juvenile Hormones - metabolism / juveniles / Larva - genetics / Larva - growth & development / Larva - metabolism / Larvae / Larval development / mechanism of action / Melanization / Menopause / Methoprene / Methoprene - metabolism / microscopy / Mode of action / mosquito control / Mosquito Vectors - genetics / Mosquito Vectors - growth & development / Mosquito Vectors - metabolism / Mosquitoes / phenotype / Phenotypes / Pupa - genetics / Pupa - growth & development / Pupa - metabolism / pupae / Pupation / Ribonucleic acid / RNA / RNA interference / RNA-mediated interference / Synthesis / transcription factors / Transcription Factors - genetics / Transcription Factors - metabolism / Vector-borne diseases / Vectors / Yellow fever