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Updated: Jan 26, 2026

Resurrection of Dormant Daphnia magna: Protocol and Applications
Published on: January 19, 2018
Changes in ultrastructure of gonads and external morphology during aging in the parthenogenetic cladoceran Daphnia
Mingqi Cai1, Zhiquan Liu1, Minghai Chen1
1School of Life Science, East China Normal University, Shanghai 200241, China.
Abstract:
The water flea Daphnia pulex, a small crustacean that lives in freshwater ponds, undergoes parthenogenesis and gamogenesis according to environmental conditions. In D. pulex, different morphological characteristics can be observed using a microscope during aging. In this study, we recorded the growth, reproduction, and survival indicators of parthenogenetic D. pulex females to analyze the morphological changes that occur during senescence. We observed the growth and development of the parthenogenetic females on the 7th, 14th, 21st, and 28th days by using scanning electron microscopy and ultrastructure of the gonads on the 7th, 14th and 21st days with transmission electron microscopy. We found that body length and reproductive capacity in the parthenogenetic individuals first increased and then decreased with aging, and the survival rate decreased gradually. The depression of the brood pouch on the back of the parthenogenetic females implied a decline in gonadal function and gradual aging. During senescence, the number of lipid droplets in the gonads of the parthenogenetic females decreased, and the integrity of the mitochondria and peroxisome was destroyed. The results of our study revealed the morphological characteristics of senescence in D. pulex.
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