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PubMed1998

Killer whale predation on sea otters linking oceanic and nearshore ecosystems

After nearly a century of recovery from overhunting, sea otter populations are in abrupt decline over large areas of western Alaska. Increased killer whale predation is the likely cause of these declines. Elevated sea urchin density and the consequent deforestation of kelp beds in the nearshore community demonstrate that the otter's keystone role has been reduced or eliminated. This chain of interactions was probably initiated by anthropogenic changes in the offshore oceanic ecosystem.

Journal Article↗

PubMed2004

From mouse to whale: a universal scaling relation for the PR Interval of the electrocardiogram of mammals.

BACKGROUND: On the ECG, the PR interval measures the time taken by an electrical impulse generated in the sinoatrial node to propagate from atria to ventricles. From mouse to whale, the PR interval increases approximately 10(1), whereas body mass (BM) augments approximately 10(6). Scaling of many biological processes (eg, metabolic rate, life span, aortic diameter) is described by the allometric equation Y=Y(0) x BM(b), where Y is the biological process and b is the scaling exponent that is an integer multiple of 1/4. Hierarchical branching networks have been proposed to be the underlying mechanism for the 1/4 power allometric law. METHODS AND RESULTS: We first derived analytically the allometric equation for the PR interval. We assumed that the heart behaves as a set of "fractal-like" networks that tend to minimize propagation time across the conducting system while ensuring a hemodynamically optimal atrioventricular activation sequence. Our derivation yielded the relationship PR proportional, variant BM1/4. We subsequently obtained previously published values of PR interval, heart rate, and BM of 541 mammals representing 33 species. Double-logarithmic analysis demonstrates that PR interval increases as heart rate decreases, and both variables relate to BM following the 1/4 power law. Most important, the best fit for PR versus BM is described by the equation PR=53 x BM0.24. Hence, the empirically determined exponent (0.24) is close to 1/4, as predicted. CONCLUSIONS: We have demonstrated that the PR interval of mammals scales as the 1/4 power of the BM, following the universal law for allometric scaling to ensure an optimal atrioventricular activation sequence.

Algorithms↗

PubMed2004

Echolocation clicks of two free-ranging, oceanic delphinids with different food preferences: false killer whales Pseudorca crassidens and Risso's dolphins Grampus griseus.

Toothed whales (Odontoceti, Cetacea) navigate and locate prey by means of active echolocation. Studies on captive animals have accumulated a large body of knowledge concerning the production, reception and processing of sound in odontocete biosonars, but there is little information about the properties and use of biosonar clicks of free-ranging animals in offshore habitats. This study presents the first source parameter estimates of biosonar clicks from two free-ranging oceanic delphinids, the opportunistically foraging Pseudorca crassidens and the cephalopod eating Grampus griseus. Pseudorca produces short duration (30 micro s), broadband (Q=2-3) signals with peak frequencies around 40 kHz, centroid frequencies of 30-70 kHz, and source levels between 201-225 dB re. 1 micro Pa (peak to peak, pp). Grampus also produces short (40 micro s), broadband (Q=2-3) signals with peak frequencies around 50 kHz, centroid frequencies of 60-90 kHz, and source levels between 202 and 222 dB re. 1 micro Pa (pp). On-axis clicks from both species had centroid frequencies in the frequency range of most sensitive hearing, and lower peak frequencies and higher source levels than reported from captive animals. It is demonstrated that sound production in these two free-ranging echolocators is dynamic, and that free-ranging animals may not always employ biosonar signals comparable to the extreme signal properties reported from captive animals in long-range detection tasks. Similarities in source parameters suggest that evolutionary factors other than prey type determine the properties of biosonar signals of the two species. Modelling shows that interspecific detection ranges of prey types differ from 80 to 300 m for Grampus and Pseudorca, respectively.

Animal Communication↗

PubMed2002

Stenurus globicephalae Baylis et Daubney, 1925 (Nematoda: Pseudaliidae) from a false killer whale, Pseudorca crassidens (Cetacea: Delphinidae), stranded on the coast of Uruguay.

Stenurus globicephalae Baylis et Daubney, 1925 (Nematoda: Pseudaliidae) was found in the cranial air sinuses of a false killer whale, Pseudorca crassidens (Owen), stranded on the coast of Uruguay in 1999. Although this species has been reported once in P. crassidens from the North Atlantic, this is the first record for South America. A total of 920 specimens were obtained, of which 663 were females (body length: 4.34 +/- 0.45 cm) and 257 were males (2.99 +/- 0.18 cm). Morphometric details are presented for S. globicephalae in this host, which do not show significant differences from those parasitizing Globicephala melas (Traill), but are distinct from those parasitizing Peponocephala electra (Gray). The host's skull revealed loss of osseous mass with the disappearance of the left zygomatic arch, and the left jaw had three osseous fenestrations in the region related to the organ of acoustic reception. These lesions support the hypothesis that this infection, known as stenurosis, was related to the stranding.

Animals↗

PubMed2002

Saksenaea vasiformis and Apophysomyces elegans zygomycotic infections in bottlenose dolphins (Tursiops truncatus), a killer whale (Orcinus orca), and pacific white-sided dolphins (Lagenorhynchus obliquidens).

During a 10-yr period, a killer whale (Orcinus orca), two Pacific white-sided dolphins (Lagenorhynchus obliquidens), and two bottlenose dolphins (Tursiops truncatus), all housed at SeaWorld of Texas from 1991 to 2001, were infected with fungi from the class Zygomycetes. In four out of five cases, the fungi were identified as either Saksenaea vasiformis or Apophysomyces elegans. All fungi in the class Zygomycetes aggressively invade the vascular system. Death occurred within 23 days after the initial clinical signs. The primary site of infection involved the s.c. tissue and skeletal musculature. In one case, infection originated in the placenta and uterus of a periparturient animal. All cases exhibited systemic spread of the organisms, including two to the central nervous system. The fifth and most recent case, a bottlenose dolphin, was treated with liposomal nystatin, an antifungal formulation with reduced nephrotoxicity. This animal initially responded to therapy; however, 14 days after cessation of therapy, fungal growth reoccurred. Thus, the animal was euthanatized 39 days after the initial clinical signs. This drug represents a promising treatment option if combined with early disease detection and aggressive tissue resection.

Animals↗

PubMed1977

Spondylosis in the whale--an anatomicoradiological study of an osteophyte.

This report describes a macroscopic and radiological study (on a dry specimen) of a whale vertebra having an osteophyte of spondylosis similar to those present in man and other mammalians. This osteophyte has a remodelled and dense structure different from that of the normal neighbouring bone of the vertebral body (which has the particular bone structure of a cetacean). The study of the osteophytes and the bridges of sponylosis in the marine mammalians offers particularly favourable conditions for a better dissociation of the pre-existing vertebral body and the extrinsic bone which was newly developed under the influence of mechanical factors.

Animals↗

PubMed2003

Autometallographic tracing of mercury in pilot whale tissues in the Faroe Islands.

OBJECTIVES: Autometallography (AMG) was applied for tracing mercury in long-finned pilot whales (Globicephala melas) harvested in the Faroe Islands. RESULTS: Ample mercury accumulation was found in kidney tubules, in contrast to the largely unstained glomeruli. Hepatocytes, as well as liver macrophages, exhibited high mercury uptake. The muscle tissue accumulated only scant amounts of mercury, primarily around the nuclei of the striated muscle cells. At the ultrastructural level, mercury was found to accumulate intracellularly in lysosomes, and extracellularly in the basement membranes of vessels. The results were verified by proton induced X-ray emission (PIXE) analysis, and it was established that the tissue contained no other AMG traceable metals. CONCLUSION: The use of AMG analysis on autopsies and biopsies is suggested as a tool for evaluating mercury pollution.

Animals↗

PubMed2002

A covalently cross-linked gel derived from the epidermis of the pilot whale Globicephala melas.

The rheological properties of the stratum corneum of the pilot whale (Globicephala melas) were investigated with emphasis on their significance to the self-cleaning abilities of the skin surface smoothed by a jelly material enriched with various hydrolytic enzymes. The gel formation of the collected fluid was monitored by applying periodic-harmonic oscillating loads using a stress-controlled rheometer. In the mechanical spectrum of the gel, the plateau region of the storage modulus G' (<1200 Pa) and the loss modulus G" (>120 Pa) were independent of frequency (omega = 43.98 to 0.13 rad x s(-1), tau = 15 Pa, T = 20 degrees C), indicating high elastic performance of a covalently cross-linked viscoelastic solid. In addition, multi-angle laser light scattering experiments (MALLS) were performed to analyse the potential time-dependent changes in the weight-average molar mass of the samples. The observed increase showed that the gel formation is based on the assembly of covalently cross-linked aggregates. The viscoelastic properties and the shear resistance of the gel assure that the enzyme-containing jelly material smoothing the skin surface is not removed from the stratum corneum by shear regimes during dolphin jumping. The even skin surface is considered to be most important for the self-cleaning abilities of the dolphin skin against biofouling.

Animals↗

PubMed1992

Limited T cell receptor beta-chain usage in the sperm whale myoglobin 110-121/E alpha dA beta d response by H-2d congenic mouse strains.

The specificity and TCR gene usage of a panel of sperm whale myoglobin (SpWMb)-reactive T cell clones from DBA/2 mice have previously been characterized, to study structure-function relationships between components of the ternary complex consisting of Ag, TCR, and MHC class II molecules, whose interaction leads to Th cell activation. These DBA/2 clones were specific for epitopes within the residue 110 to 121 region of SpWMb, in the context of the mixed isotype molecule E alpha dA beta d, and expressed the TCR V beta 8.2 gene element. SpWMb-specific T cell hybridomas from the H-2d-congenic B10.D2 mouse strain, which differs from the DBA/2 strain only in the non-MHC background, were generated and compared with the T cell hybridomas from DBA/2 mice, in order to investigate the influence of non-MHC genes on the specificity of the T cell response to the 110-121 epitope. V beta usage by these hybridomas was very homogeneous; three of three DBA/2 and eight of nine B10.D2 hybridomas specific for the 110-121 epitope, in the context of the mixed isotype molecule E alpha dA beta d, expressed the V beta 8.2 gene product. Nucleotide and amino acid sequences of D beta, J beta, and N regions were also similar. One 110-121/E alpha dA beta d-specific B10.D2 hybridoma used V beta 7, a V beta that is clonally deleted in DBA/2 mice. These experiments suggest that a similar set of TCR beta genes are used to respond to a given epitope, regardless of non-MHC background, and they support the hypothesis that, despite great variability between individuals in their non-MHC background genes, human HLA-associated diseases might result from the formation of a particular ternary complex consisting of a shared MHC molecule, a common "disease-associated" epitope, and a shared TCR.

Animals↗

PubMed1989

Chemical investigation of the internal secretion of the sperm blue whale.

Ambergris, which is an internal secretion of the sperm blue whale, was extracted with 96% ethanol. The saponified and unsapondied portions have been studied in detail. The number of fractions and components of the unsaponified matter as separated by column and thin layer Chromatography confirm the presence of ambrein (triterpenoid) as well as same other steroid. The saponified portion is reported to contain stearic, oleic, linoleic, archidic and betenic acids. More than one compound have been found in each fraction.

Journal Article↗

PubMed1973

Levels of DDT and PCB compounds in North Atlantic fin-back whales.

DDT and polychlorinated biphenyl (PCB) compounds were found in blubber tissue samples of 12 North American fin-back whales collected in 1970 and 1971. Concentrations of DDT and metabolites ranged up to 2.557 ppm, while the highest PCB concentration was 0.185 ppm Gas chromatographic results were confirmed by chemical derivatization.

Adipose Tissue↗

PubMed1951