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PubMed2006

A whale's tale.

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Animals↗
PubMed1999

Anatomy of the laryngeal apparatus of the pygmy right whale, Caperea marginata (Gray 1846).

The laryngeal apparatus of Caperea marginata is described for the first time and proves to be significantly different from that of any mysticete previously described. This difference is especially noticeable in the position of the laryngeal sac, which is separate from the tracheal rings and lies to the right of the animal. Massive ontogenetic development of the sac in adult males is demonstrated, far greater than that seen in most other mysticetes. Histological analysis of the laryngeal sac shows the walls to be very muscular, abundantly innervated, and vascularized, indicating an active organ. Coiled blood vessels and nerves support the hypothesis that the sac undergoes extensive expansion and contraction. A possible association with the unique thoracic development of the species is suggested. The roles of the laryngeal sac and arytenoid cartilages in mysticete sound production are also discussed.

Animals↗
PubMed1986

Comparative morphology and evolution of the otic region in toothed whales (Cetacea, Mammalia).

The otic region in the skull of archeocetes and odontocetes is compared and interpreted with special emphasis on the morphology and suspension of the ear bones. In archeocetes, the periotic was obviously separate from the mastoid but still integrated within the skull via a long anterior and posterior process. The rotation of the cochlear part of the periotic was already obvious. The tympanic bone was attached to a decreasing number of neighboring elements, with the periotic becoming more and more important in the later archeocetes. The accessory air sacs of the tympanic cavity had invaded some of the adjacent skeletal elements and attained a moderate-to-remarkable extension. In the evolution of the odontocetes, the periotic and tympanic were successively uncoupled from the skull and combined to a new morphological and functional unit (tympanoperiotic complex). This uncoupling was mainly achieved by shortening the periotical processes and simultaneously extending the tympanic air sacs. For functional reasons, however, the periotic (posterior process) stayed in immediate contact with the mastoid, the latter remaining in the lateral wall of skull. In advanced marine dolphins, the bony sheaths of the accessory air sacs are largely reduced, presumably because of volume fluctuations in the tympanic cavity during diving. The perfect uncoupling of the ear bones from the skull obviously was an essential prerequisite for directional hearing, for effective ultrasound orientation and communication, and finally, for the striking development of the dolphin brain.

Animals↗
PubMed1981

Prenatal and postnatal development of the cervical portion of the spine in the short-finned pilot whale Globicephala macrorhyncha.

Fusion of the cervical spine in Globicephala macrorhyncha is a prenatal rather than a postnatal phenomenon which encompasses all cervical vertebra. This results in a relatively short, nonarticulated, composite cervical spine in this particular species. Cervicothoracic spine segments removed from fetuses demonstrated complete fusion of all cervical vertebra commencing during early prenatal development. C1 and C2 initially developed as a composite central cartilaginous unit, although laterally there was some separation through rudimentary interzone formation. However, C3 through C7 formed individual cartilaginous centra which were divided from each other by thin, well-demarcated concomitantly evident dividing the thoracic, lumbar, and caudal vertebra, although this was a very rudimentary intervertebral region). The first primary ossification center appeared in C2. Subsequently, primary ossification occurred in C7, and finally in C2 through C6, with ossification centers then progressively coalesced in the midline, from C2 to C7, in a craniocaudal sequence. This entire chondroosseous fusion process was completed during early gestation (probably less than 2 to 3 months of prenatal development), so that a composite "single" cervical vertebra developed that characterizes this species at birth and throughout postnatal development. Postnatally, ossification spreads laterally within each centrum, and also progressively removes the vestiges of the intervertebral material. The cranial end of C7 and the remainder of the cervical vertebra do not form secondary centers. An extensive fibrocartilaginous/hyaline cartilage bridge remains between C1 and C2, even after closure of the vertebral physes. Undoubtedly, this allows continued growth in C1 and C2, which become the dominant portion of the cervical unitary vertebra. Eventually, even this synchondrosis will disappear to form a completely osseous cervical mass.

Animals↗
PubMed1999

Immune functions in the Fisher rat fed beluga whale (Delphinapterus leucas) blubber from the contaminated St. Lawrence estuary.

In order to assess the immunotoxic potential of food naturally contaminated with PCBs and other organohalogens, Fisher rats were fed a diet in which the lipids originated from the blubber of either a highly polluted St. Lawrence beluga or a relatively uncontaminated Arctic beluga. After a period of 2 months, different immune functions were evaluated, including lymphoblastic transformation, natural killer cell activity, plaque-forming cells, phagocytosis, oxidative burst, and immunophenotyping. For all assays, rats fed a St. Lawrence beluga blubber diet or a mixture of Arctic and St. Lawrence beluga blubber diet were not different from control rats fed a diet containing Arctic beluga blubber. These results are inconsistent with the well-known immunosuppressive effects of organochlorines in numerous species and with the lesions suggestive of organochlorine-related immunosuppression that are observed in St. Lawrence belugas. The lack of observable immunotoxic effects in rats fed contaminated beluga blubber might be explained by antagonistic effects in the organohalogen mixture, by a response specific to the rat, by a strain-related lack of sensitivity to organochlorines, or by insufficient dose due to the shortness of the exposure period or the route of exposure.

Adipose Tissue↗
PubMed1998

Trifluoroethanol stabilizes the pH 4 folding intermediate of sperm whale apomyoglobin.

2,2,2-Trifluoroethanol (TFE) is known to stabilize peptide helices by strengthening hydrogen bonds. On the other hand, TFE destabilizes native proteins, as we confirm here, presumably by weakening the hydrophobic interaction. The stability of the pH 4 folding intermediate of apomyoglobin is known to depend both on the strength of the individual A, G, and H helices and on hydrophobic interactions between helices. We ask which effect of TFE dominates in this case: strengthening helices or weakening hydrophobic interactions between helices? Protein stability is measured by denaturant-induced unfolding curves, and two-state unfolding is tested by monitoring both far-UV CD and tryptophan fluorescence emission. Low concentrations of TFE strongly stabilize the pH 4 folding intermediate. Moreover, low concentrations of TFE compensate for helix-destabilizing mutations in the A and G helices. Consequently, enhancing helix propensity, rather than weakening the hydrophobic interaction, is the dominant effect of TFE on the folding intermediate. This result agrees with earlier mutational evidence that helix propensities are very important in determining the stability of the pH 4 intermediate. Although TFE destabilizes native holomyoglobin, as well as native lysozyme and ribonuclease A, nevertheless, TFE stabilizes native apomyoglobin.

Animals↗
PubMed2000

Molecular phylogenetic examination of the delphinoidea trichotomy: congruent evidence from three nuclear loci indicates that porpoises (Phocoenidae) share a more recent common ancestry with white whales (Monodontidae) than they do with true dolphins (Delphinidae).

Porpoises (Phocoenidae), dolphins (Delphinidae), and the two species of Monodontidae (beluga and narwhal) together constitute the superfamily Delphinoidea. Although there is extensive evidence supporting the monophyly of this superfamily, previous studies involving morphology, as well as sequence analysis of mitochondrial genes, have failed to yield a clear picture of the relative relationships within the group. Here we present the first examination of this issue from the perspective of single-copy nuclear genes at the DNA sequence level. The data involve three such loci: von Willebrand factor (vWF), interphotoreceptor retinoid binding protein (IRBP), and lactalbumin. The vWF and IRBP data sets consist of protein-coding fragments, whereas the sequenced lactalbumin fragment is predominately intronic. All phylogenetic analyses involving at least one representative from each of the three Delphinoidea families congruently support a beluga/porpoise clade. The levels of sequence divergence for most of these data appear to roughly concur with a paleontological date for the radiation of the Delphinoidea at 11-15 MYA but, in agreement with mitochondrial DNA sequence analyses, suggest that the extant major groups of cetaceans radiated approximately 25 MYA, 10 million years later than inferred from paleontological data.

Animals↗