The function of glucose metabolism in embryonic diapause of annual killifish.

Annual killifish could survive as diapaused embryos buried in soil during dry seasons. When the embryos in diapause III were incubated in water, the larvae could be hatched quickly. However, the mechanism of diapause and hatching of annual killifish was ambiguous. In the present study, Nothobranchius guentheri were used as the model to clarify the physiological mechanism of diapause and hatching of annual killifish. The results indicated that incubation with water could significantly enhance the heart rate and blood circulation of embryos. To clarify the molecular mechanism, the transcriptomic analysis was used to compare the embryos in diapause I, diapause III, and hatching period. The results showed that DNA replication-related genes, cell division cycle 45 and proliferating cell nuclear antigen were more highly expressed in diapause I compared to diapause III. In addition, the transcript levels of glucagon, glucokinase and phosphofructokinase were more abundantly detected in hatching period compared to diapause III, but insulin receptor and insulin-like growth factor-binding protein were lower. These results indicated glucose metabolism might play an important role in diapause and hatching of killifish. To further confirm this result, several reagents involved in glucose metabolism were used to incubate embryos in diapause III. The results displayed that glucose and glucagon could both shorten the hatching time of embryos. In contrast, 2-deoxy-d-glucose, metformin, and insulin could prolong the hatching time and reduce the hatching rate. The results further confirmed that glucose metabolism played an important role in the diapause and hatching of annual killifish.

Gao X ，Cai T ，Lin Y ，Zhu R ，Hao W ，Guo S ，Hu G ... -  《-》

The evolution of an annual life cycle in killifish: adaptation to ephemeral aquatic environments through embryonic diapause.

An annual life cycle is characterized by growth, maturity, and reproduction condensed into a single, short season favourable to development, with production of embryos (seeds, cysts, or eggs) capable of surviving harsh conditions which juveniles or adults cannot tolerate. More typically associated with plants in desert environments, or temperate-zone insects exposed to freezing winters, the evolution of an annual life cycle in vertebrates is fairly novel. Killifish, small sexually dimorphic fishes in the Order Cyprinodontiformes, have adapted to seasonally ephemeral water bodies across much of Africa and South America through the independent evolution of an annual life history. These annual killifish produce hardy desiccation-resistant eggs that undergo diapause (developmental arrest) and remain buried in the soil for long periods when fish have perished due to the drying of their habitat. Killifish are found in aquatic habitats that span a continuum from permanent and stable to seasonal and variable, thus providing a useful system in which to piece together the evolutionary history of this life cycle using natural comparative variation. I first review adaptations for life in ephemeral aquatic environments in killifish, with particular emphasis on the evolution of embryonic diapause. I then bring together available evidence from a variety of approaches and provide a scenario for how this annual life cycle evolved. There are a number of features within Aplocheiloidei killifish including their inhabitation of marginal or edge aquatic habitat, their small size and rapid attainment of maturity, and egg properties that make them particularly well suited to the colonization of ephemeral waters.

Furness AI 《-》

A rapid transcriptome response is associated with desiccation resistance in aerially-exposed killifish embryos.

Tingaud-Sequeira A ，Lozano JJ ，Zapater C ，Otero D ，Kube M ，Reinhardt R ，Cerdà J ... -  《PLoS One》

Embryonic developmental arrest in the annual killifish Austrolebias charrua: A proteomic approach to diapause III.

Chalar C ，Clivio G ，Montagne J ，Costábile A ，Lima A ，Papa NG ，Berois N ，Arezo MJ ... -  《PLoS One》

The role of energetic reserves during embryonic development of an annual killifish.

Females can significantly improve their fitness by utilizing a range of maternal effects. Embryos of annual killifish survive the dry season in ephemeral pools encased in dry substrate for several months. Here, we experimentally test the association between energetic provisioning and maternally controlled duration of embryonic development in the African annual killifish Nothobranchius furzeri (Cyprinodontiformes). We found that embryonic energetic reserves do not limit duration of development. However, differences in energetic reserves affect the size at which embryos hatched, with larger yolk size resulting in larger hatchling size. These findings suggest uncoupling of the two traits examined (i.e., embryonic energetic reserves and development duration) and emphasize the strong buffering role of diapause in the energetic balance of embryonic development in the annual killifish. Developmental Dynamics 246:838-847, 2017. © 2017 Wiley Periodicals, Inc.

Vrtílek M ，Polačik M ，Reichard M 《-》