Embryonic diapause and its regulation

Abstract

Embryonic diapause, a condition of temporary suspension of development of the mammalian embryo, occurs due to suppression of cell proliferation at the blastocyst stage. It is an evolutionary strategy to ensure the survival of neonates. Obligate diapause occurs in every gestation of some species, while facultative diapause ensues in others, associated with metabolic stress, usually lactation. The onset, maintenance and escape from diapause are regulated by cascades of environmental, hypophyseal, ovarian and uterine mechanisms that vary among species and between the obligate and facultative condition. In the bestknown models, the rodents, the uterine environment maintains the embryo in diapause, while estrogens, in combination with growth factors, reinitiate development. Mitotic arrest in the mammalian embryo occurs at the G0 or G1 phase of the cell cycle, and may be due to expression of a specific cell cycle inhibitor. Regulation of proliferation in non-mammalian models of diapause provide clues to orthologous genes whose expression may regulate the reprise of proliferation in the mammalian context.

The African turquoise killifish: A research organism to study vertebrate aging and diapause

“…As a consequence, it helps the species survive extreme forms of stress (e.g., drought) and it also “times” the birth of offspring to a more favorable environment (e.g., rainy season). In nature, diapause phenomena are widespread throughout the animal kingdom, from simple organisms such as brine shrimps and silkworms, to mammals such as the roe deer, bats, and mice (Bleier, 1975; Emerson, Bradshaw & Holzapfel, 2009; Hand, Denlinger, Podrabsky & Roy, 2016; Lambert et al., 2001; Lopes, Desmarais & Murphy, 2004; Meenakumari & Krishna, 2005; Ptak et al., 2012; Sato et al., 2014; Schiesari & O'Connor, 2013; Sim & Denlinger, 2013). Our current knowledge of diapause has benefited greatly from the studies in invertebrates.…”

“…Diapause can occur at different developmental stages in diverse species (Hand et al., 2016; Lopes et al., 2004; Mead, 1993; Ptak et al., 2012). In killifishes, diapause can occur during early, intermediate, and late developmental stages (diapause I, II, and III, respectively; Wourms, 1972).…”

Mouse pluripotent stem cells at a glance

“…Indeed, LIF is systematically required when mESCs are grown in combination with two small-molecule inhibitors (referred to as '2i') that block glycogen synthase kinase 3 (GSK3) and mitogen-activated protein kinase kinases (MAP2Ks, also known as MEKs) or when grown in the presence of bone morphogenetic protein (BMP) (Ying et al, 2003;Ying et al, 2008). Importantly, although the role of the LIF signalling pathway is well established in pluripotent cells in vitro, genetic studies have shown that the absence of glycoprotein 130 (gp130) or signal transducer and activator of transcription 3 (STAT3) (Nichols et al, 2001; Takeda et al, 1997) -both of which are necessary for LIF signalling -has no consequence on early mouse development but are required for the diapause stage (reviewed in Lopes et al, 2004). These studies indicate that LIF-dependent mESCs are representative of pluripotent cells of the diapause embryo just before implantation.…”

Genetic and phenotypic parameters of age at first mating, litter size and animal size in Finnish mink

“…Ovulation is induced by the presence of males or attempted or successful copulation, and a maturation age is about 8 to 12 months -E-mail: minna.koivula@mtt.fi (Lariviè re, 1999;Ferguson and Lariviè re, 2002). Minks have also delayed implantation, which is an evolutionary strategy to ensure that postnatal development can be completed under more favorable environmental conditions (Lopes et al, 2004). Because minks are photosensitive breeders with induced ovulation, it is possible to manipulate the timing of reproductive cycles by altering photoperiod (Fredberg et al, 2006) and also by date of first exposure to males.…”