The synthesis of diapause-specific molecular chaperones in embryos of Artemia franciscana is determined by the quantity and location of heat shock factor 1 (Hsf1)

Abstract

The crustacean, Artemia franciscana, displays a complex life history in which embryos either arrest development and undertake diapause as cysts or they develop into swimming nauplii. Diapause entry is preceded during embryogenesis by the synthesis of specific molecular chaperones, namely the small heat shock proteins p26, ArHsp21, and ArHsp22, and the ferritin homolog, artemin. Maximal synthesis of diapause-specific molecular chaperones is dependent on the transcription factor, heat shock factor 1 (Hsf1), found in similar amounts in cysts and nauplii newly released from females. This investigation was performed to determine why, if cysts and nauplii contain comparable amounts of Hsf1, only cyst-destined embryos synthesize diapausespecific molecular chaperones. Quantification by qPCR and immunoprobing of Western blots, respectively, demonstrated that hsf1 mRNA and Hsf1 peaked by day 2 post-fertilization in embryos that were developing into cysts and then declined. hsf1 mRNA and Hsf1 were present in nauplii-destined embryos on day 2 post-fertilization, but in much smaller amounts than in cystdestined embryos, and they increased in quantity until release of nauplii from females. Immunofluorescent staining revealed that the amount of Hsf1 in nuclei was greatest on day 4 post-fertilization in cyst-destined embryos but could not be detected in nuclei of nauplius-destined embryos at this time. The differences in quantity and location of Hsf1 explain why embryos fated to become cysts and eventually enter diapause synthesize p26, ArHsp21, ArHsp22, and artemin, whereas nauplius-destined embryos do not produce these molecular chaperones.

Bioresilience to Mercury Chloride of the Brine Shrimp Artemia Salina after Treatment with Homeopathic Mercurius Corrosivus

“…17,18,38 Cysts are forms of resistance of the species and their permanence as such reveals a well-known resilience mechanism, involving the production of chaperone (p26, ArHsp21, ArHsp22, and artemin) and other proteins by the embryo. [65][66][67] Similarly, the treatment with Ethilicum 1cH (succussed 0.7% alcoholic solution) was also related to a first level of cyst protection. According to Sandri et al, potentized alcohol cannot be considered as an inert vehicle, but a specific homeopathic medicine, thus a comparative substance.…”

Transcriptomic analysis elucidates the molecular processes associated with hydrogen peroxide-induced diapause termination in Artemia-encysted embryos

“…In previous studies, most of them on genes related to the regulation of diapause termination in Artemia cysts focused on genes related to adversity resistance [ 9 , 21 – 24 ]. For examples, these reported genes or proteins are involved in the regulation of diapause termination have been elucidated including HSP70 [ 25 ], HSP p26 [ 26 , 27 ], ArHSPs [ 28 – 32 ] and heat shock factor 1 (Hsf1) [ 33 , 34 ]. In addition, There are also many recent studies on late embryogenesis abundant (LEA) proteins in their roles on Artemia [ 35 – 42 ].…”