Embryonic diapause in two species of brine shrimp: Artemia monica and Artemia franciscana
The brine shrimp, Artemia, has the capacity to produce encysted embryos which are resistant to severe environmental conditions. Upon release from the ovisac, these embryos, or cysts, do not hatch, but remain in a state of developmental arrest imposed by some unknown endogenous mechanism. However, once the proper abiotic signal is received, the embryo is free to resume development. Regulation of this embryonic diapause in two related species of brine shrimp, Artemia franciscana and Artemia monica, is studied. The abiotic cues which terminate diapause and the possibility of a regulatory mechanism involving depressed intracellular pH (pH/sub i/) are investigated. /sup 31/P-NMR studies show that pH/sub i/ of diapause cysts of both species is alkaline, greater than or equal to 7.9, essentially the same as that of activated cysts. A franciscana, which inhabits an unpredictable environment, is activated by several cues: low temperature, dehydration, and elevated levels of CO/sub 2/. A. monica, found in a fairly stable body of water with regular seasonal changes in temperature, breaks diapause only upon exposure to low temperature. Induction of anoxybiosis in diapause and activated cysts is studied using /sup 31/P-NMR to reveal that diapause cysts acidify rapidly in response to anoxia; pH/sub i/ falls to about 7.2 in 30 minutes, much like activated cysts, indicating the presence of a fairly active metabolism. The effects of salinity on cyst activation, hatching, water content, and carbohydrate metabolism are examined.
- Research Organization:
- California Univ., Davis (USA)
- OSTI ID:
- 6401667
- Resource Relation:
- Other Information: Thesis (Ph. D)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANOXIA
BIOLOGICAL EFFECTS
ARTEMIA
LIFE CYCLE
PHOSPHORUS
TEMPERATURE EFFECTS
CARBON DIOXIDE
EMBRYOS
SENSITIVITY
BIOLOGICAL STRESS
METABOLISM
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
PH VALUE
SALINITY
SEASONAL VARIATIONS
WATER POLLUTION
ANIMALS
AQUATIC ORGANISMS
ARTHROPODS
BRANCHIOPODS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CRUSTACEANS
ELEMENTS
INVERTEBRATES
MAGNETIC RESONANCE
NONMETALS
OXIDES
OXYGEN COMPOUNDS
POLLUTION
RESONANCE
SPECTRA
VARIATIONS
560200* - Thermal Effects
560300 - Chemicals Metabolism & Toxicology