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At least 343 records · Page 19Linked to original sources
PubMed1990

Analysis of the C4 genes in baleen whales using a human cDNA probe.

We have used a human C4 cDNA probe to investigate the complement component C4 gene in four members of the family Balaenopteridae: fin whale (Balaenoptera physalus), sei whale (B. borealis), minke whale (B. acutorostrata), and bryde's whale (B. edeni). Restriction mapping of genomic DNA from the first three species suggests the presence of only one locus in these species, and also shows that the C4 genes in the three species are very similar. We have used 14 restriction endonucleases to investigate the restriction fragment length polymorphism (RFLP) of fin whales, 13 enzymes for sei whales, and 8 enzymes for the minke whale. No polymorphism was seen in DNA from the five minke whale samples, but Rsa I and Taq I restriction enzymes gave polymorphism in fin and sei whales whereas Hind III and Msp I restriction enzymes showed polymorphism in sei whales only. Only one bryde's whale sample was available for investigation. The study of DNA available from mother-fetus pairs from the two polymorphic species demonstrated a simple, two-allele transmission of RFLP alleles.

Animals↗
PubMed1980

Irido-corneal angle of mammalian eyes: comparative morphology of encapsulated corpuscles in odontocete cetaceans.

A study of the structure and distribution of encapsulated corpuscles (corpuscles of Rochon-Duvigneaud) in the irido-corneal (anterior chamber) angle in 42 adult eyes from nine species of odontocete cetaceans representing each of the five families in this group indicates a diversity of form and function. The corpuscles occur as signle features or multiple groupings with each species having a distinct pattern. No definite phylogenic or environmental patterns were seen although sometimes there were similarities among related genera. The neural structure of the angle suggests that these receptors probably respond to a variety of stimuli including intraocular pressure, vitreous displacements, external muscular force applied to the sclera and cornea, and changes in the volume of the massive iris/choroid vascular system.

Animals↗
PubMed1975

Cell number and cell density in the cerebellar cortex of man and some other mammals.

The number of cells per unit volume was determined in the cerebellar cortex of man and 19 other mammals. The cell density (i.e. the number of cells per unit volume) decreases from mammals with a low brain weight to those with a higher brain weight. This decrease in the number of cells is found to be proportional for all three layers of the cerebellar cortex. In addition, the ratio of Purkinje cells to granule cells was determined. In contrast to the decrease of all cell types with increasing brain weight, this ratio varies remarkably among the mammals and is not correlated with brain weight. In man, this ratio is 1:2991, while it is lower in all other mammals investigated. These differences in the ratio of Purkinje cells to granule cells and the decrease in cell density with increasing brain weight are discussed in relation to brain evolution.

Animals↗
PubMed1989

Composition and chromosomal localization of cetacean highly repetitive DNA with special reference to the blue whale, Balaenoptera musculus.

Three highly repetitive DNA components--the common cetacean component, the heavy (GC-rich) satellite and the light (AT-rich) satellite--were were studied in the blue whale. Consensus sequences of the common component and the heavy satellite were determined on the basis of three repeats of the common component and eight repeats of the heavy satellite. The tandemly organized common cetacean component, which comprises a large portion of all cetacean--both odontocete (toothed whale) and mysticete (whalebone whale)--genomes has a repeat length of 1,760 bp and the three clones analysed showed a high degree of conformity. The repeat contains a 72 bp sequence with dyad symmetry and striking intrastrand complementarity. The rest of the repeat comprises a unique sequence. The repeat unit of the heavy satellite of the blue whale is 422 bp. Also this component is tandemly organized. About half the length of the repeat constitutes a unique sequence and the other half is made up of subrepeats with TTAGGG as a frequent motif. The light satellite has not been sequenced and its basic repeat unit has not yet been identified. The chromosomal localization of the three components was determined by in situ hybridization using 3H-labelled cloned fragments as probes. The common cetacean component was located in most interstitial and terminal C-bands. The heavy satellite occurred primarily in terminal C-bands. When the two components hybridized to the same terminal C-bands, the localization of the heavy satellite was distal to that of the common cetacean component. Neither component shared localization with the light satellite which is located in centromeric C-bands in just a few chromosome pairs.

Animals↗
PubMed1984

Conservation of highly repetitive DNA in cetaceans.

It is controversial whether odontocetes (toothed whales) and mysticetes (whalebone whales) have a common ancestry. Cetacean karyological uniformity, which is unique among mammalian orders, suggests a monophyletic origin; however, several anatomical authorities have maintained that odontocetes and mysticetes are diphyletic. We investigated the issue using Southern blot hybridization. Two labelled restriction fragment probes from the DNA of the sei whale (a mysticete) were hybridized to restricted DNA of cetacean species representing all extant families except the Eschrichtiidae, the gray whales. The probes hybridized to specific restriction fragments in all odontocete and mysticete materials. Hybridization showed preservation of hybridization homologies and a striking conservation of the length of highly repeated DNA sequences. The results are compatible with a common ancestry of odontocetes and mysticetes.

Animals↗
PubMed1978

Conservation and chromosomal localization of DNA satellites in balenopterid whales.

DNA satellites were isolated from three balenopterid species, viz. the minke, sei, and fine whales. In each of them at least two DNA satellites were recognizable with buoyant densities in neutral CsCl of rho = 1.702/1.703 and rho = 1.710/1;711, respectively. cRNAs from each satellite group were used for filter and in situ hybridisations. Homo-and heterologous DNA-cRNA hybrids within each satellite group yielded virtually identical melting curve profiles showing conservation of at least a considerable part of the DNA satellite sequences. There was no evident sequence homology between the rho = 1.702/1.703 and the rho = 1.710/1;711 satellites by filter hybridisation.--The in situ hybridisation showed that in each species the rho = 1.702/1.703 satellite was located in centromeric-paracentromeric C-bands in a few pairs, whereas the rho = 1.710/1.711 satellite was located in terminal C-bands throughout the karyotypes.--The data on the whale DNA satellites indicate that the quantitative evolution of the sateliite DNA sequences preceded species divergence of the balenopterids and that the satellite sequences have remained relatively unaltered since the divergence took place. The function of satellite DNA is considered to imply the introduction of both chromosomal and genic polymorphisms and thus being of great importance in speciation, Based upon these concepts a model is postulated for the function of satellite DNA. According to this model at meiotic pairing euchromatinheterochromatin overlapping between homologous chromosomes is considered to be of a general occurrence. This overlapping is presumed to be accentuated by the size heteromorphism frequently observed between homologous heterochromatic segments (C-bands). In the region of such euchromatinheterochromatin overlapping, cross-over would be excluded. The overlapping is suggested to be rectified progresssively in the chromosome arms, leaving unaffected crossing-over distant to the euchromatin-heterochromatin junctions. The consequence of this will be that genes in the proximity of the junctions are collectively inherited and selected, whereas genes distant to the the heterochromatin will be independently assorted and selected.

Animals↗
PubMed1986

Ontogenetic development of the nervus terminalis in toothed whales. Evidence for its non-olfactory nature.

For the first time in cetaceans, the development of the terminalis system and its continuity between the olfactory placode and the telencephalon has been demonstrated by light microscopy. In the early development of toothed whales (Odontoceti) this system is partially incorporated within the fila olfactoria which grow out from the olfactory placode. As the peripheral olfactory system is reduced in later stages, a strongly developed ganglionlike structure (terminalis ganglion) remains within the primitive meninx. Peripherally it is connected via the cribriform plate with ganglionic cell clusters near the septal mucosa. Centrally it is attached to the telencephalon (olfactory tubercle, septal region) by several nerve fibre bundles. In contrast to all other mammalian groups, toothed whales and dolphins are anosmatic while being totally adapted to aquatic life. Therefore the remaining ganglion and plexus must have non-olfactory properties. They may be responsible for the autonomic innervation of intracranial arteries and of the large mucous epithelia in the accessory nasal air sacs. The morphology, evolution and functional implications of the terminalis system in odontocetes and other mammals are discussed.

Animals↗
PubMed1989

Spinal hyperostosis in comparative pathology. A useful approach to the concept.

Spinal hyperostosis, an anatomical and radiological concept primarily described in man, is characterized by enthesopathic bony overgrowth on vertebral bodies in the form of spurs or intervertebral bridges. It can also be part of a more diffuse enthesopathic condition, including the appendicular skeleton. These changes are distinct from those of osteoarthrosis. Similar changes can be observed in all kinds of mammals, independent of their type of locomotion (bipodic, quadrumanous, quadrupedic, or aquatic). An anatomical and radiological study is presented of six cases (with histological examination of two dogs and one horse, and observation of macerated specimens of one horse, one equida, and one whale). Comparative pathology allows for a better understanding of the concept of hyperostosis and, even more clearly than in man, this can be distinguished from that of discovertebral pathology although both conditions could be associated in older subjects. The knowledge of spinal hyperostosis in veterinary medicine could--as in man--be of interest to differentiate between this process and other features of vertebral pathology.

Animals↗
PubMed1984

Molecular charge and electrophoretic mobility in cetacean myoglobins of known sequence.

Fourteen myoglobins of known sequence were examined by polyacrylamide gel electrophoresis at five pH values. Gels at each pH divided the sequences into six to eight distinct classes, while the combination of the results of three gels at different pH levels distinguished 13 of 14, or 93%, of the sequences. The relative mobility of the myoglobins in the gels is significantly correlated with the charges of the proteins calculated from the pK values of the ionized groups. Major differences in mobility corresponded to expected differences in charge due to the amino acid substitutions between sequences. In addition to sequences differing in the total number of acidic and basic residues, those differing from each other in the total number of histidines were distinguished on low-pH gels. One pair of sequences differing by the exchange of lysine for arginine was separated on high-pH gels, as predicted from the differences in ionization of these two amino acids. On gels at pH 10.4, there was greater deviation of electrophoretic mobility from charge than on other gels, possibly due to the influence of amino acid substitutions in the neighborhood of lysine residues. Manipulation of the concentration and composition of the gels did not change the separation of the sequences from each other. Examination of myoglobins by gel electrophoresis at a wide range of pH values allows discrimination of nearly all amino acid substitutions and demonstrates the close relationship between titration and relative electrophoretic mobility.

Amino Acid Sequence↗
PubMed1986

The sensitivity of isoelectric focusing and electrophoresis in the detection of sequence differences in proteins.

Fourteen myoglobins of known sequence were examined by isoelectric focusing with and without urea. The 14 sequences formed six distinct mobility classes on gels without urea and three classes on those with urea. For these proteins, isoelectric focusing provides no advantage over single, nonequilibrium, nondenaturing gels in the total number of distinguishable mobility classes. Only major charge differences, resulting from the changes in the total numbers of acidic and basic amino acids, can be detected on gels with urea, indicating that denaturation by urea alters proteins so that small differences in ionization are eliminated.

Amino Acid Sequence↗
PubMed1986

Trace element content in two species of whale tapeworms, Diphyllobothrium macroovatum and Diplogonoporus balaenopterae.

Trace elements in two species of whale tapeworms, Diphyllobothrium macroovatum and Diplogonoporus balaenopterae, were analysed by atomic absorption spectroscopy. Six elements (Fe, Cu, Zn, Mn, Cd, Ca) were assayed from different regions of two tapeworms: scolex, neck, immature, mature and gravid proglottids. Whole strobilae at different stages of maturity were also examined. The relationship between the trace element content and the physiological significance is discussed.

Animals↗
PubMed1989

Critical evaluation of polychlorinated biphenyl toxicity in terrestrial and marine mammals: increasing impact of non-ortho and mono-ortho coplanar polychlorinated biphenyls from land to ocean.

Residues of potentially toxic non-ortho chlorine substituted coplanar 3,3',4,4'-tetra-,3,3',4,4',5-penta-, 3,3',4,4',5,5'-hexachlorobiphenyl and their mono- and di-ortho analogs 2,3',4,4',5-penta, 2,3,3',4,4'-penta-, 2,3,3',4,4',5-hexa- and 2,2',3,3',4,4'-hexa-, 2,2',3,4,4',5-hexachlorobiphenyl) were determined in humans, dogs, cats (terrestrial), a finless porpoise (Neophocoena phocoenoides--coastal), Dall's porpoises (Phocoenoides dalli, dalli), Baird's beaked whales (Berardius bairdii) and killer whales (Orcinus orca--open ocean). Among the coplanar polychlorinated biphenyl (PCB) congeners, the concentration of the di-ortho congeners was the highest and the non-ortho congeners was the lowest. However, all three coplanar PCBs occurred at significantly higher levels than toxic polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The relative bioconcentration and metabolic capacity of terrestrial and marine mammals to these chemicals, suggest that the toxic threat of coplanar PCBs increases from land to ocean, but the reverse is true for PCDDs and PCDFs. The toxic threat of coplanar PCBs to higher aquatic predators such as cetaceans was principally assessed by 2,3,7,8-T4CDD Toxic Equivalent Analysis which is based on the induction of arylhydrocarbon hydroxylase (AHH) and ethoxyresorufin O-deethylase (EROD). Analysis indicates, in particular, that the bioaccumulation of toxic 3,3',4,4',5-penta- and 2,3,3',4,4'-pentachlorobiphenyls in carnivorous marine mammals is a cause for considerable concern.

Animals↗