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At least 649 records · Page 36Linked to original sources
PubMed1998

Rostrum of a toothed whale: ultrastructural study of a very dense bone.

The rostral bones of the toothed whale, Mesoplodon densirostris, consist mainly of hypermineralized secondary osteons and have yielded among the highest values for density (2.6 g/cm3) and mineral content (86.7%) yet reported for any bone. Scanning and transmission electron microscopy show parallel rods of mineral oriented along the length of the rostrum. These consist of platey crystals of carbonated hydroxyapatite, which, judging from electron diffraction, are extremely well and coherently aligned. The collagen component of the rostral bone consists largely of very thin fibrils aligned in longitudinal register to form tubular networks. The collagen fibrils are also aligned with the lengths of the mineral rods, which are apparently accommodated in the tubular spaces of the collagenous network. This peculiar ultrastructure clearly differs from the densely packed mineralized fibrils commonly observed in vertebrate lamellar osseous tissues, although histological examination has indicated some vestiges of "normal" primary bone surrounding the secondary osteons. Thus, the bone tissue in the rostrum is characterized by a remarkably sparse collagenous component. This ultrastructure can explain the high density, stiffness, and brittleness of the rostrum that have been observed. It also raises interesting questions about possible modes of crystal growth during ongoing mineralization in normal bone, and may have some relevance in the mechanical behavior of dense bones in pathological conditions.

Animals↗
PubMedDate not supplied

A comparative morphometric analysis of the optic nerve in two cetacean species, the striped dolphin (Stenella coeruleoalba) and fin whale (Balaenoptera physalus).

A comparative study was made on one Mysticete (the fin whale, Balaenoptera physalus) and one Odontocete species (the striped dolphin, Stenella coeruleoalba) by measuring several morphological characteristics seen in cross sections of the optic nerve. We found that the two cetacean nerves share a number of specializations that distinguish them from the optic nerve of terrestrial mammals. Fiber density is approximately two-fold lower than in land mammals. A corresponding increase in the cross-sectional area occupied by astrocytes is observed. A population of "giant" (up to 15 microm in diameter) optic axons is present in both the B. physalus and the S. coeruleoalba nerve. It is argued that these features probably reflect common adaptations to the constraints imposed by the aquatic environment. "Giant" optic axons might ensure short-latency detection of preys and other targets during navigation while the increased astroglial content might be related to the maintenance of neuronal function during periods of anaerobic metabolism under water.

Animals↗
PubMed2004

Relationship between the appearance of preantral follicles in the fetal ovary of Antarctic minke whales (Balaenoptera bonaerensis) and hormone concentrations in the fetal heart, umbilical cord and maternal blood.

The present study aimed to determine the relationship among changes in the number of preantral follicles and concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), progesterone (P4), androstenedione (A) and estradiol-17beta (E2) in the fetal heart, umbilical cord and maternal blood. Primordial follicles had already appeared in a 20 cm fetus and primary follicles were observed in a 50 cm fetus. In a 70 cm fetus, the number of primordial and primary follicles increased rapidly and secondary follicles were present. The concentrations of LH and FSH did not change between 20 cm and 160 cm in fetal length. When the fetal length became > 70 cm, serum levels in the fetus, umbilical cord and mothers, and E2 levels in umbilical cord increased synchronously (p < 0.05). These results showed increases in the number of preantral follicles in the Antarctic minke whale fetal ovary along with fetal growth during the early gestation period. These findings suggest that the change in preantral follicles was associated with changes in the concentration of steroids in early gestation periods. The changes in steroid concentrations in the fetal and umbilical cord blood and the increased number of preantral follicles were coincident at around 70 cm in fetal length, whereas the growth and differentiation of primordial and primary follicles appeared to be independent of FSH and LH.

Androstenedione↗
PubMed2005

A complete phylogeny of the whales, dolphins and even-toed hoofed mammals (Cetartiodactyla).

Despite the biological and economic importance of the Cetartiodactyla, the phylogeny of this clade remains controversial. Using the supertree approach of matrix representation with parsimony, we present the first phylogeny to include all 290 extant species of the Cetacea (whales and dolphins) and Artiodactyla (even-toed hoofed mammals). At the family-level, the supertree is fully resolved. For example, the relationships among the Ruminantia appear as (((Cervidae, Moschidae) Bovidae) (Giraffidae, Antilocapridae) Tragulidae). However, due to either lack of phylogenetic study or contradictory information, polytomies occur within the clades Sus, Muntiacus, Cervus, Delphinidae, Ziphiidae and Bovidae. Complete species-level phylogenies are necessary for both illustrating and analysing biological, geographical and ecological patterns in an evolutionary framework. The present species-level tree of the Cetartiodactyla provides the first opportunity to examine comparative hypotheses across entirely aquatic and terrestrial species within a single mammalian order.

Animals↗
PubMed1995

Certification of polychlorinated biphenyl congeners and chlorinated pesticides in a whale blubber standard Reference Material.

A Standard Reference Material (SRM) made from whale blubber has been developed for the validation of methods used for the determination of polychlorinated biphenyl (PCB) congeners and chlorinated pesticides. This material, which is a frozen blubber tissue homogenate, was analyzed using three different analytical techniques. These techniques were based on gas chromatography with electron capture detection on two stationary phases with different selectivity for the separation of PCB congeners and gas chromatography with mass spectrometric detection. The results from these three techniques were in good agreement and were combined to provide certified concentrations for 27 PCB congeners and 15 chlorinated pesticides.

Animals↗
PubMed1994

Replacement of the proximal ligand of sperm whale myoglobin with free imidazole in the mutant His-93-->Gly.

The proximal bond between the iron atom of the heme group and the N epsilon of histidine F8 in myoglobin (Mb) and hemoglobin (Hb) is presumed to be an important determinant of heme binding, protein structure, and oxygen binding. Here a system is described in which the proximal ligand is provided intermolecularly by the histidine side chain mimic imidazole. The proximal ligand of sperm whale Mb is replaced with glycine (H93G) using site-directed mutagenesis. The addition of imidazole to Escherichia coli expressing this gene reconstitutes myoglobin function. H93G Mb purified in the presence of imidazole is spectroscopically similar to wild-type Mb in combination with a wide variety of distal ligands. The crystal structure of H93G Mb, determined in the presence of imidazole, reveals that an imidazole molecule is bonded to the heme iron on the proximal side, substituting in trans for the side-chain function of the proximal histidine of wild-type Mb. Although H93G Mb is similar in spectroscopic and gross structural detail to wild-type Mb, subtle differences exist in the orientation of imidazole with respect to the heme group. trans-Complementation of proximal ligand function will allow the proximal bond in hemoproteins to be chemically substituted beyond the limits of the genetic code.

Animals↗
PubMed1994

The heme iron coordination complex in His64(E7)Tyr recombinant sperm whale myoglobin.

By using site-directed mutagenesis of recombinant sperm whale (SW) myoglobin, the native distal histidine residue, at position 64 (the helical position E7), has been replaced with a tyrosine. The mutation of His64Tyr SW myoglobin has an analogous heme iron electronic structure as that of native hemoglobins M Boston and M Saskatoon. Optical spectroscopy showed that the distal tyrosine bound to the heme iron had a pK value of 5.6. In the pH range of 4.7-11.0, electron spin resonance spectroscopy suggested the presence of two heme iron ligation schemes: the heme iron bound to a distal water molecule or to a distal tyrosine residue. The heme iron coordination in the wild-type myoglobin and in the His64Tyr SW Mb mutant was studied by X-ray absorption near-edge structure (XANES) spectroscopy. Indeed, the heme iron K-edge reflects the electronic organization of the metal inside the six-coordinated complex. Comparative analysis of X-ray absorption heme iron K-edge shapes showed that the heme iron of His64Tyr SW myoglobin is bound to the oxygen atom from the phenol group of the distal tyrosine residue (Fe-OH phi). When the pH value decreased from pH 7 to 5.6, the Fe-OH phi bond strength decreased, resulting in an increase of the heme iron high-spin population of His64Tyr SW myoglobin. At low pH values, the Fe-OH phi bond can be disrupted with the possibility of heme iron binding of another ligand having a higher affinity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Nuclear magnetic resonance studies of amino acids and proteins. Side-chain mobility of methionine in the crystalline amino acid and in crystalline sperm whale (Physeter catodon) myoglobin.

We have obtained deuterium (2H) nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation times (T1) of L-[epsilon-2H3]methionine, L-[epsilon-2H3]methionine in a D,L lattice, and [S-methyl-2H3]methionine in the crystalline solid state, as a function of temperature, in addition to obtaining 2H T1 and line-width results as a function of temperature on [epsilon-2H3]methionine-labeled sperm whale (Physeter catodon) myoglobins by using the method of magnetic ordering [Rothgeb, T. M., & Oldfield, E. (1981) J. Biol. Chem. 256, 1432-1446]. The results indicate that in the L-amino acid, methyl rotation having an activation energy (delta E) of 8.3 +/- 1 kJ dominates T1 at low temperatures (less than or equal to 10 degrees C), while at higher temperatures an additional large-amplitude side-chain motion occurs which causes changes in the 2H NMR line shape and T1. This motion is inhibited in the D,L lattice, indicating that lattice effects may have a strong effect on the mobility of anhydrous amino acids in the solid state. Further substitution at S delta to form the sulfonium salt [S-methyl-2H3]-methionine causes a large increase in delta E, to 15.9 +/- 2 kJ, a value comparable to the 14-16 kJ found in valine and leucine, which contain the structurally similar isopropyl moiety. These results suggest that the very low barriers to methyl rotation in the methionine side chain are due to long C-S bond lengths and the presence of only two substituents on sulfur, while the anomalous high-temperature behavior is due to a lattice-packing effect. 2H T1 results with methionine-labeled myoglobin are complex, reflecting the presence of fast large-amplitude side-chain motions, in addition to rapid methyl rotation. Our data indicate that Met-55 and Met-131 are motionally inequivalent in crystalline cyanoferrimyoglobin, in contrast to solution NMR results. We have also recorded 13C cross-polarization "magic-angle" sample-spinning NMR spectra of [epsilon-13C]methionine-labeled crystalline cyanoferrimyoglobin (at 37.7 MHz, corresponding to a magnetic field strength of 3.52 T) and of the same protein in aqueous solution. Cross-polarization transfer rates and proton rotating-frame relaxation time results again indicate that Met-55 and Met-131 are motionally inequivalent in the solid state, and the TCH data indicate that Met-55 is more solidlike. However, we find that 13C chemical shifts in solution and those in the crystalline solid state are in very close agreement, suggesting that the average solution and crystal conformations are the same, in the area of Met-55 and Met-131.

Animals↗
PubMed1987

A time-resolved photoacoustic calorimetry study of the dynamics of enthalpy and volume changes produced in the photodissociation of carbon monoxide from sperm whale carboxymyoglobin.

The dynamics of the enthalpy and volume changes produced in the photodissociation of carbon monoxide from sperm whale myoglobin is investigated by time-resolved photoacoustic calorimetry. The enthalpy and volume changes for the formation of the geminate pair, which occurs within 50 ns of photolysis, are delta H = -2.2 +/- 2.8 kcal/mol and delta V = -10.0 +/- 1.0 mL/mol relative to carboxymyoglobin. The enthalpy and volume changes associated with formation of deoxymyoglobin and solvated carbon monoxide, formed with a half-life of 702 +/- 31 ns at 20 degrees C, are delta H = 14.6 +/- 3.4 kcal/mol and delta V = 5.8 +/- 1.0 mL/mol relative to carboxymyoglobin.

Animals↗
PubMed1988

A structure of sperm whale myoglobin at a nitrogen gas pressure of 145 atmospheres.

A structure of sperm whale metmyoglobin under a nitrogen gas pressure of 145 atm (2200 psi) has been solved by X-ray diffraction using data to 2.0-A resolution. The perturbation of the gas pressure on the overall structure of the protein is minimal with a root mean square deviation of backbone atoms between the pressurized and unpressurized structures of 0.22 A. Additional electron density is observed, however, in two cavities of the protein molecule. The density is interpreted as a nitrogen molecule bound in the proximal cavity and as a water molecule hydrogen bonded in a separate cavity (cavity 3). In addition, alternate conformations are observed for three internal residues (Leu-135, Phe-138, and Ile-142) that border these cavities. These alternate conformations are not observed in atmospheric pressure structures and are presumed due to the effects of pressure and/or gas binding. The appearance of these alternate conformations implies a repacking of the protein interior and produces a new distribution of cavity spaces. The profile of the Debye-Waller factors for the pressurized structure is similar to that for the room pressure except for a small increase in the distal region (residues 61-69) of the protein.

Animals↗
PubMed1990

Role of the arginine-45 salt bridge in ligand dissociation from sperm whale carboxymyoglobin as probed by photoacoustic calorimetry.

The dynamics of the enthalpy and volume changes found in the photodissociation of CO from sperm whale carboxymyoglobin and two site-directed mutants in which arginine-45 is replaced by glycine and asparagine are examined by photoacoustic calorimetry. An intermediate is observed whose lifetime at 20 degrees C is 700 ns. The enthalpy of the intermediate increases by approximately 7 kcal/mol upon replacing arginine-45 with either asparagine or glycine. These observations support recent proposals that an arginine-45 salt bridge is broken upon ligand dissociation.

Acoustics↗
PubMed1981

Differences in iron-fluoride bonding between the isolated subunits of human methemoglobin fluoride and sperm whale metmyoglobin fluoride as measured by resonance Raman spectroscopy.

The heme geometries of the isolated alpha and beta subunits of human methemoglobin fluoride (HbIIIF) and sperm whale metmyoglobin fluoride (MbIIIF) have been examined by exciting their Raman spectra within their ca. 6000-A charge-transfer absorption bands. The Fe-F stretching vibration at 471 cm-1 in the beta subunits shifts to 466 cm-1 in the alpha subunits and to 461 cm-1 in MbIIIF. The Fe-F bond is estimated to elongate by 0.02 A in the alpha subunits and 0.03 AZ in MbIIIF compared with that in the beta subunits. This bond elongation is interpreted to result from an increased iron displacement toward the proximal histidine side of the heme in the series MbIIIF greater than alpha greater than beta. A comparison of the isolated subunit spectra with that of tetrameric HbIIIF indicates little change occurs in isolated subunit heme geometry upon association into tetrameric HbIIIF. A correlation is found between the gamma max of the 600-A charge-transfer absorption band and the Fe-F bond length. Elongation of the Fe-F bond is associated with a shift of the absorption spectral maximum to a longer wavelength. However, the absorption spectral shift induced by the inositsol hexaphosphate induced R leads to T conversion does not result from a change in the Fe-F stretching frequency (+/- 0.5 cm-1). In contrast, frequency shifts are observed for heme macrocyclic vibrational modes. The data are interpreted to indicate that the effect of the R leads to T conversion in HbIIIF is to perturb heme macrocycle conformation without altering the heme out-of-plane iron distance or the Fe-F bond length.

Animals↗
PubMed1981

Resonance Raman and absorption spectroscopic detection of distal histidine--fluoride interactions in human methemoglobin fluoride and sperm whale metmyoglobin fluoride: measurements of distal histidine ionization constants.

The pH dependence of the resonance Raman and absorption spectra of human methemoglobin fluoride (HbIIIF) and sperm whale metmyoglobin fluoride (MbIIIF) has been examined. Both the Raman and absorption spectra of HbIIIF and MbIIIF indicate the existence at alkaline pH of an equilibrium between the hydroxide and fluoride complexes. The absorption maxima of HbIIIF and MbIIIF solutions shift to longer wavelengths as the pH is decreased from neutrality. The Raman data show a corresponding shift of the 461- and 468-cm-1 Fe-F vibrational stretching peaks at pH 7.0 [Asher, S. A., & Schuster, T. M. (1979) Biochemistry 18, 5377] to 399 and 407 cm-1 at acid pH in MbIIIF and HbIIIF, respectively. These shifts are interpreted to result from protonation of the distal histidine and the formation of a hydrogen bond to the fluoride ligand. Measurements of the pH dependence of the absorption and resonance Raman spectra give distal histidine ionization constants (apparent) corresponding to pK = 5.1 (+/- 0.1) for HbIIIF and pK = 5.5 (+/- 0.1) for MbIIIF. An examination of the distal histidine pK values and the frequency of the hydrogen-bonded Fe--F stretching vibration at pH 5.0 of HbIIIF with and without inositol hexaphosphate indicates little difference in the distal histidine--heme distance between the so-called R and T quaternary forms of HbIIIF. These results indicate that the changes in the electronic spectrum of HbIIIF that occur upon switching from the R to the T form do not result from alterations in (1) the iron--fluoride bond distance, (2) the iron out-of-heme plane distance, or (3) the distal histidine--fluoride distance.

Animals↗
PubMed2003

Levels and temporal trends of toxaphene congeners in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary, Canada.

Environmentally relevant toxaphene congeners were determined in blubber samples of stranded beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary (SLE), Canada. The purpose of this study was to evaluate the levels and the temporal trends (1988-1999) of a suite of six chlorobornanes (P26, P40/41, P44, P50, and P62) in the SLE belugas. P26 and P50 mean concentrations were in the same range as those reported for animals living in the Arctic environment suggesting that the atmospheric transport represents the main input of toxaphene to the SLE. A general exponential decline of chlorobornane concentrations in belugas was observed, except for P26 and P50 in males. On average, concentrations decreased by a factor of two in 8.5 years during the 1988-1999 time period. This rate of decline is similar to the reduction of toxaphene emission from agricultural soils in the southern United States reported over the same time period. Some differences in decline rates were observed among the studied CHB congeners. For instance, P62 decreased more rapidly than P26 and P50 in both male and female belugas. Several hypotheses were advanced to explain these differences such as selective metabolism of specific chlorobornanes by SLE belugas or their prey. However, a most likely explanation is the selective degradation of the technical product in soils and atmosphere in the source region.

Adipose Tissue↗
PubMed2001

Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls.

Modern members of the mammalian order Cetacea (whales, dolphins and porpoises) are obligate aquatic swimmers that are highly distinctive in morphology, lacking hair and hind limbs, and having flippers, flukes, and a streamlined body. Eocene fossils document much of cetaceans' land-to-water transition, but, until now, the most primitive representative for which a skeleton was known was clearly amphibious and lived in coastal environments. Here we report on the skeletons of two early Eocene pakicetid cetaceans, the fox-sized Ichthyolestes pinfoldi, and the wolf-sized Pakicetus attocki. Their skeletons also elucidate the relationships of cetaceans to other mammals. Morphological cladistic analyses have shown cetaceans to be most closely related to one or more mesonychians, a group of extinct, archaic ungulates, but molecular analyses have indicated that they are the sister group to hippopotamids. Our cladistic analysis indicates that cetaceans are more closely related to artiodactyls than to any mesonychian. Cetaceans are not the sister group to (any) mesonychians, nor to hippopotamids. Our analysis stops short of identifying any particular artiodactyl family as the cetacean sister group and supports monophyly of artiodactyls.

Animals↗
PubMed1997

Genetic tagging of humpback whales.

The ability to recognize individual animals has substantially increased our knowledge of the biology and behaviour of many taxa. However, not all species lend themselves to this approach, either because of insufficient phenotypic variation or because tag attachment is not feasible. The use of genetic markers ('tags') represents a viable alternative to traditional methods of individual recognition, as they are permanent and exist in all individuals. We tested the use of genetic markers as the primary means of identifying individuals in a study of humpback whales in the North Atlantic Ocean. Analysis of six microsatellite loci among 3,060 skin samples collected throughout this ocean allowed the unequivocal identification of individuals. Analysis of 692 'recaptures', identified by their genotype, revealed individual local and migratory movements of up to 10,000 km, limited exchange among summer feeding grounds, and mixing in winter breeding areas, and also allowed the first estimates of animal abundance based solely on genotypic data. Our study demonstrates that genetic tagging is not only feasible, but generates data (for example, on sex) that can be valuable when interpreting the results of tagging experiments.

Animals↗
PubMed2004

Non-destructive analysis of the two subspecies of African elephants, mammoth, hippopotamus, and sperm whale ivories by visible and short-wave near infrared spectroscopy and chemometrics.

Visible (VIS) and short-wave near infrared (SW-NIR) spectroscopy was used for non-destructive analysis of ivories. VIS-SW-NIR (500-1000 nm) spectra were measured in situ for five kinds of ivories, that is two subspecies of African elephants, mammoth, hippopotamus, and sperm whale. Chemometrics analyses were carried out for the spectral data from 500 to 1000 nm region. The five kinds of ivories were clearly discriminated from each other on the scores plot of two principal components (PCs) obtained by principal component analysis (PCA). It was noteworthy that the ivories of the two subspecies of African elephants were discriminated by the scores of PC 1. The loadings plot for PC 1 showed that the discrimination relies on the intensity changes in bands due to collagenous proteins and water interacting with proteins. It was found that the scores plot of PC 2 is useful to distinguish between the ivories of the two subspecies of African elephants and the other ivories. We also developed a calibration model that predicted the specific gravity of five kinds of ivories from their VIS-SW-NIR spectral data using partial least squares (PLS)-1 regression. The correlation coefficient and root mean square error of cross validation (RMSECV) of this model were 0.960 and 0.037, respectively.

Animals↗