The Heart of the Killer Whale: Description of a Plastinated Specimen and Review of the Available Literature

The killer whale (Orcinus orca, Linnaeus, 1958) is the largest extant delphinid. Despite its worldwide distribution in the wild and in dolphinariums, its anatomy remains relatively poorly described. In the present study, we describe the detailed morphology of a plastinated killer whale heart. The gross description of the arteries and veins reaching the organ and its coronary vessels are reported. Additional endoscopy and CT (computed tomography) scanning were performed to provide extensive measurements of its parts. In many aspects, the killer whale heart conformed to other delphinid heart descriptions, including position, relative size and shape and specific features such as extensive papillary muscles, trabecular endocardium and trabecula septomarginalis. These characteristics are representative of the delphinid family, suggesting that its functions and capacities are similar to that of other, smaller, dolphins and help understand the conditions in which these predators exert their remarkable physical performance necessary for their survival

CHANGES IN CYTOCHROME C OXIDASE (CCO) AND LACTATE DEHYDROGENASE (LDH) ENZYME ACTIVITY OF THE WHITE EPAXIAL MUSCLE TISUE OF SEA BAS (DICENTRARCHUS LABRAX L.) AS SHELF-LIFE PREDICTIVE INDICES DURING ICE-STORAGE

Fish freshness can be evaluated by sensory, physical and biochemical parameters. The purpose of the present work was to evaluate the potential utilisation of enzyme activity changes as indicators of shelf life in ice-stored sea bass. Changes in the enzyme content and organoleptic score of ungutted ice-stored sea bass were monitored over a two-week period. Organoleptic score and activity of CCO and LDH decreased gradually with a 50% reduction after 10 days of storage in ice. The results show that monitoring the activity of the mitochondrial and cytoplasmic enzymes of fish muscle can be used as an indicator of fish freshness

Generality of vertebrate developmental patterns: evidence for a dermomyotome in fish

The somitic compartment that gives rise to trunk muscle and dermis in amniotes is an epithelial sheet on the external surface of the somite, and is known as the dermomyotome. However, despite its central role in the development of the trunk and limbs, the evolutionary history of the dermomyotome and its role in non-amniotes is poorly understood. We have tested whether a tissue with the morphological and molecular characteristics of a dermomyotome exists in non-amniotes. We show that representatives of the agnathans and of all major clades of gnathostomes each have a layer of cells on the surface of the somite, external to the embryonic myotome. These external cells do not show any signs of terminal myogenic or dermogenic differentiation. Moreover, in the embryos of bony fishes as diverse as sturgeons (Chondrostei) and zebrafish (Teleostei) this layer of cells expresses the pax 3 and 7 genes that mark myogenic precursors. Some of the pax7-expressing cells also express the differentiation-promoting myogenic regulatory factor Myogenin and appear to enter into the myotome. We therefore suggest that the dermomyotome is an ancient and conserved structure that evolved prior to the last common ancestor of all vertebrates. The identification of a dermomyotome in fish makes it possible to apply the powerful cellular and genetic approaches available in zebrafish to the understanding of this key developmental structure