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At least 37 records · Page 2Linked to original sources
PubMed1978

Properties and reaction mechanism of the bioluminescence system of the deep-sea shrimp Oplophorus gracilorostris.

The bioluminescent reaction of Oplophorus takes place when the oxidation of coelenterazine (the luciferin) with molecular oxygen is catalyzed by Oplophorus luciferase, resulting in light of maximum intensity at 462 nm and the products CO2 and coelenteramide. Oplophorus luciferase has now been obtained in a highly purified state. Optimum luminescence occurs at pH 9 in the presence of 0.05--0.1 M NaCl at 40 degrees C, and, due to the unusual resistance of this enzyme to heat, visible luminescence occurs at temperatures above 70 degrees C when partially purified enzyme is used. The specific activity of purest preparations is 1.75 X 10(15) photons s-1 mg-1 at 23 degrees C. At pH 8.7, native luciferase has a molecular weight of approximately 130 000, apparently comprising 4 monomers of 31 000; at lower pHs, the native luciferase tends to polymerize. The quantum yield of coelenterazine is 0.34 at 22 degrees C with this enzyme. After the luminescent reaction, the spent solution is nonfluorescent, and likewise solutions of luciferase alone. When the bioluminescent reaction was carried out in the presence of 18O2, the product CO2 contained more than 50% C18O16O, supporting the dioxetane mechanism, but without ruling out the linear peroxide mechanism.

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PubMed2025

Temperature and Pressure Shaped the Evolution of Antifreeze Proteins in Polar and Deep Sea Zoarcoid Fishes.

Antifreeze proteins (AFPs) have enabled teleost fishes to repeatedly colonize polar seas. Four AFP types have convergently evolved in several fish lineages. AFPs inhibit ice crystal growth and lower tissue freezing point. In lineages with AFPs, species inhabiting colder environments may possess more AFP copies. Elucidating how differences in AFP copy number evolve is challenging due to the genes' tandem array structure and consequently poor resolution of these repetitive regions. Here, we explore the evolution of type III AFPs (AFP III) in the globally distributed suborder Zoarcoidei, leveraging six new long-read genome assemblies. Zoarcoidei has fewer genomic resources relative to other polar fish clades while it is one of the few groups of fishes adapted to both the Arctic and Southern Oceans. Combining these new assemblies with additional long-read genomes available for Zoarcoidei, we conducted a comprehensive phylogenetic test of AFP III evolution and modeled the effects of thermal habitat and depth on AFP III gene family evolution. We confirm a single origin of AFP III via neofunctionalization of the enzyme sialic acid synthase B. We also show that AFP copy number increased under low temperature but decreased with depth, potentially because pressure lowers freezing point. Associations between the environment and AFP III copy number were driven by duplications of paralogs that were translocated out of the ancestral locus at which AFP III arose. Our results reveal novel environmental effects on AFP evolution and demonstrate the value of high-quality genomic resources for studying how structural genomic variation shapes convergent adaptation.

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PubMed1975

Abyssotrema pritchardae gen. et sp. n. (Digenea: Fellodistomidae) from the deep-sea fish, Alepocephalus agassizi Goode and Bean 1883.

Abyssotrema pritchardae gen. et sp. n. is described from the benthic teleost, Alepocephalus agassizi Goode and Bean 1883 (Alepocephalidae), taken from Hudson Canyon in the western North Atlantic. The new genus is placed in the subfamily Monascinae Dollfus 1947 and relationships among Abyssotrema, Elopsium Fischthal and Thomas 1972, and Monascus Looss 1907 are discussed.

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PubMed1975

The myrosperidan genus Davisia in two deep-sea fishes.

Two new species of Davisia were identified in the urinary bladders and kidney tubules of 2 species of marine fish. D. anoplopoma was found in Anoplopoma fimbria from southern and central California. D. pectoralis was recorded from Coryphaenoides pectoralis from northern California. We have distinguished between Davisia species whose lateral appendages are "solid" and those which contain a cavity in their lateral appendages. Our species belong to the latter category. We believe the lateral appendages of "hollow" species are extensions of the spore body and not, as sometimes pictured, independently attached.

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PubMed1975

[Cyclic reproductive activity in bathyal and abyssel deep-sea fishes].

A female of the rare Brotulid fish Cataetyx laticeps has been caught; it contained a great number of larvae all of the same size. Growth marks can be noticed on its otoliths as well as on those of various species caught to the depth of 4 700 m. They are indications of a cyclic activity in the abyssal depths.

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PubMedDate not supplied

[New species of Microsporidia from the gallbladder of deep-sea fishes].

Two new species of myxosporidians with gigantic spores are described from the gall bladder of Alepocephalus australis caught at 1500 m depth. Both species differ in gigantic sizes of spores that apparently is characteristic of myxosporidians of fishes inhabiting such great depths.

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PubMed1977

Two new zoogonid digenea from deep-sea fishes in the Gulf of Panama.

Panopula cavernossa gen. et. sp. n. from the intestine of the brotulid Enchelybrotula (?) paucidens differs from other members of the Steganodermatinae by having testes near the anterior of the acetabulum, a posttesticular ovary, and a postequatorial acetabulum. Two related species are transferred to the genus Brachyenteron as B. pycnorganum comb. n. and B. spinosum comb. n. Neosteganoderma gillissi sp. n. from the synaphobranchid eel Synaphobranchus bathybius differs from N. glandulosum and N. polymixiae, the most similar species, because conspicuous glandular cells envelop the esophagus and pharynx, others about the genital atrium occur in elongated sacs, epithelium is lacking at the cecal bifurcation, and the cirrus sac is straight. We establish N. infundibulum comb. n. and expand Steganodermatinae to include Brevicreadium congeri and Hudsonia agassizi.

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