The parasitic marine dinoflagellate Amoebophrya is the first known eukaryote with aerobic mitochondria without a genome.

Significance: Unicellular organisms form endless variability of complex skeletons that serve as archives of Earth’s history and play a crucial role in global geochemical cycles. A longstanding question is how single cells control morphogenesis and mineralization of skeletal structures. Although already addressed by Sir D’Arcy W. Thompson, this problem is still unsolved. Shell emerges from a controlled cascade of interactions at different levels of cellular organization. To gain insight into its morphogenesis, we apply live fluorescent imaging to observe cytoskeleton structures during shell formation in foraminifera. Our live experiments on calcifying foraminiferal chambers show that dynamic F-actin structures are involved in shaping and controlling mineralization.

In search for methods of anesthesia of crustaceans, an implanted electrode into lobster and crayfish CNS enabled us to monitor signal propagation in the nerve system of animals undergoing different protocols. Cooling (tap water 0°C, sea water -1,8°C) and anesthesia with MgCl₂ (10%) were both discarded as anesthetic procedures because responses to external stimuli were still detectable under treatment. Contrarily, bubbling the aquarium water with CO₂ can be considered a “partially successful” anesthesia, because signal propagation is inhibited but before that the animals show discomfort. The procedure of “electro-stunning” induces epileptic-form seizures in the crustacean CNS (lobster, crayfish), which overlay but do not mitigate the response to external stimuli. After several minutes the activity declines before the nervous system starts to recover. A feasible way to sacrifice lobsters is to slowly raise the water temperature (1°C min^-1), as all electrical activities in the CNS cease at temperatures above ~30°C, whereas below this temperature the animals do not show signs of stress or escape behavior (e.g. tail flips) in the warming water. CO₂ is efficient to anaesthetize lobster and crayfish but due to low pH in water is stressful to the animals previous to anesthesia. Electrical stunning induces epileptiform seizures but paralyses the animals and leads to a reversible decline of nerve system activity after seizure. Electric stunning or slowly warming just before preparation may meet ethical expectations regarding anaesthesia and to sacrifice crustaceans.