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Marine sterols. III--The sterol compositions of oceanic jellyfish. The use of gas chromatographic mass spectrometric techniques to identify unresolved components.

The sterol compositions of three oceanic jellyfish have been determined using gas chromatographic mass spectrometric techniques involving the use of two separate gas chromatographic column systems. The components in overlapping peaks have been identified by comparison of the mass spectra of peaks in the two column systems using subtractive techniques. A mid-water animal, Periphylla periphylla, was found to contain a very complex and unusual sterol profile including rare 5alpha-stanols, whereas two other oceanic jellyfish Pelagia noctiluca and Atolla wyvillei contained similar mixtures of delta5 sterols to those previously isolated from coastal species.

Chromatography, Gas

Occurrence of fatty acid chlorohydrins in jellyfish lipids.

Fatty acid chlorohydrins are characterized as lipid components of an edible jellyfish. The four isomers 9-chloro-10-hydroxypalmitic acid, 10-chloro-9-hydroxypalmitic acid, 9-chloro-10-hydroxystearic acid, and 10-chloro-9-hydroxystearic acid were identified by gas chromatography-mass spectrometry comparison of the methyl esters and their trimethylsilyl derivatives with known synthetic samples. Two additional isomers, 11-chloro-12-hydroxystearic acid and 12-chloro-11-hydroxystearic acid, were also found in the lipid by the identification of the expected mass spectral fragments of the trimethylsilyl (Me3Si) derivative of their methyl esters. These six isomeric compounds represented approximately 1.4% of the total extractable jellyfish lipid and were released from the lipid as methyl esters by boron trifluoride-methanol treatment. These isomers account for only about 30% of the organic chlorine in the lipid. Evidence is given that the remaining organic chlorine is also present as fatty acid chlorohydrins containing more than one hydroxyl group.

Animals

The genome sequence of a coronate scyphozoan jellyfish, Nausithoe racemosa (Komai, 1936) (Coronatae: Nausithoidae), and a metagenome-assembled genome of the associated cyanobacterium Moorena producens.

We present a genome assembly from a specimen of Nausithoe racemosa (coronate scyphozoan jellyfish; Cnidaria; Scyphozoa; Coronatae; Nausithoidae). The assembly contains two haplotypes with total lengths of 4 784.66 megabases and 4 868.20 megabases. Most of haplotype 1 (97.34%) is scaffolded into 20 chromosomal pseudomolecules. Haplotype 2 was assembled to scaffold level. The mitochondrial genome has also been assembled, with a length of 13.97 kilobases. From the metagenome data, we recovered one high-quality metagenome-assembled genome.

Coronatae

Sea nettle jellyfish venom targets proteoglycans to cause cell death and pain.

Sea nettle jellyfish cause millions of painful stings annually with little known about how their venom works and no rational treatments available. Here, we perform a systematic analysis of sea nettle venom/host interactions. The venom shows dose-dependent cytotoxic activity in human cells, and this can be blocked by dual inhibition of apoptosis and necroptosis. Using whole-genome CRISPR screening, we identified human genes and pathways that modify venom action. The top gene cluster identified regulates proteoglycan biosynthesis. We show that exogenous heparin, a drug used clinically as an anticoagulant, blocks venom cytotoxicity at a physiologically relevant dose. This effect was therapeutic, inhibiting venom even 1 hour after exposure. In vivo, heparin protected against acute spontaneous pain, thermal hyperalgesia, and mechanical allodynia induced by venom. This provides the exciting possibility of repurposing heparin, a safe, commercially available drug, as a prophylactic or therapeutic to reduce the impact of sea nettle stings.

Animals

Electrically coupled, photosensitive neurons control swimming in a jellyfish.

Central neurons in Polyorchis (Hydromedusae) were impaled with microelectrodes, and conventional resting potentials were obtained. The waveform of action potentials recorded concurrently with swimming events shows evidence of electrotonic coupling between these neurons, which are also directly photosensitive and receive excitatory synaptic input from other conduction systems.

Action Potentials