Oral ontogeny of the Ayu, Plecoglossus altivelis and comparisons with the jaws of other salmoniform fishes

The Japanese Ayu, Plecoglossus altivelis Temminck & Schlegel is the sole representative of the salmoniform family Plecoglossidae. The Ayu is remarkable for its dentition which in adults comprises groups of diagonally arranged comb-like teeth in the outer tissue of the jaws. In juveniles (below 63 mm SL) the teeth are attached normally to the jaws. The transition of tooth form is correlated with a switch from zooplanktivory to algal or aufwuchs grazing. The present study follows the development of the teeth, jaws, oral cavity ethmoid and suspensorial elements in specimens ranging in size from 41–70 mm SL. The possible mode of function of the adult dentition is discussed. Comparisons are made with the jaws of other salmoniform fishes and a suite of supposed apomorphic characters are identified which are also shared with certain genera of the family Osmeridae, thus supporting the ideas of others that the Osmeridae is a paraphyletic assemblage.     

A guinea-pig hereditary cataract contains a splice-site deletion in a crystallin gene

A congenital cataract present in guinea pigs provided a unique opportunity to study a hereditary lens diseases at the molecular level. ζ-crystallin, one of the most abundant guinea pig lens proteins, was found to be altered in the lens of cataractous animals. Several ζ-crystallin cDNA clones were isolated from a cataractous lens library and found to contain a 102-bp deletion towards the 3′ end of the coding region. The deletion does not interfere with the reading frame but results in a protein 34 amino acids shorter. Sequence analysis of a normal genomic ζ-crystallin clone revealed that the missing 102-bp fragment corresponds to an entire exon (exon 7). PCR analysis of the genomic DNA isolated from cataractous animals showed that exon 7, though missing from the mRNA, is intact in the cataractous genome. Further sequence analysis of the α-crystallin gene disclosed a dinucleotide delection of the universal AG at the acceptor splice-site of intron 6 of the mutant gene. The presence of this mutation results in the skipping of exon 7 during the mRNA processing which in turn results in the altered ζ-crystallin protein. This if the first time a genomic mutation in an enzyme/crytallin gene has been directly linked to a congenital cataract.     

Issues related to mineralized tissue biology in human evolutionary research

This comunication has two primary aims concerned with mineralized tissue biology (e.g. hard tissue biology of bone and tooth) research in human evolutionary studies: First, to introduce the literature and the methods (at the time of this symposium) so that one has an idea of the nature of this research and where one can go for details of the methodologies, etc; Second — and of primary concern here — to discuss issues that have come to light as a result of these studies mainly because of its recent beginnings as a subfield within paleoanthropology. Issues related to skeletal studies include; 1) whether different cortical surface pattens and bone tissue types influence the appearance and interpretation of bone growth activity states; 2) if SEM analyses of cortical surfaces in fossil hominids allow one to construct meaningful representations of remodeling patterns; 3) whether these representations can be used in phylogenetic arguments; and 4) how intraspecific variability would affect these issues. Issues related to dental studies include: 1) the relationship between the rate and pattern of eraly hominid dental development; 2) experimental support for the calibration of eraly hominid dental developmental rates; and 3) whether replica techniques are suitable for microanatomical studies of these sorts.     

Sperm aging in the male after sexual rest: Contribution to chromosome anomalies

The chromosome complement was studied in first-cleavage metaphases of mouse zygotes resulting from sperm aged in the male physiologically, after sexual rest. Females were inseminated by control males mating at 3-day intervals while experimentals mated to males that had had a sexual rest of 14 or more days. A total of 1954 eggs were collected 33–35 h post-HCG from 101 superovulated females mated to 42 controls and 43 experimental males. The fertilization rate was similar in both groups, being 84% and 85%, respectively. G-banded or Q-banded chromosomes were analyzed in 301 (68.3%) controls and 392 (49%) experimental first-cleavage metaphases. The overall rate of chromosome anomalies in controls was 4.45% as compared to 10.94% in experimentals, a highly significant difference. In the experimental group compared to controls, the frequency of trisomy, triploidy, structural rearrangements, and tetraploidy increased from 3.9% to 6.9%, 0% to 1.6%, 0.8% to 2.8%, and 0% to 1.3%, respectively. The genomic source of origin of the abnormalities was determined on the basis of differential condensation of the genomes. In the experimentals, grossly unbalanced sperm (diploids, disomics, double disomics, and those with large fragments) fertilized significantly more oocytes compared to controls. Our results implicate an advantage either in numbers or fertilizing capability for chromosomally abnormal sperm in a physiologically aged population.     

Hormone-responsive cells derived from human dental papilla: Characterization in vitro and in vivo in diffusion chambers

Summary Cells of the dental papilla are capable of odontoblastic, fibroblastic, and endothelial differentiation and formation of dentin and the dental pulp. In the present study dental papilla cells, obtained from human tooth buds (HDP cells), were cultured in vitro through 3 to 7 passages. After exposure to prostaglandin E₂ there was a marked decrease in intracellular cyclic AMP (cAMP) levels as compared to hormone-free controls. Parathyroid hormone and calcitonin had stimulatory effects with 1 and 2 log increases in cAMP, respectively. The HDP cells showed moderate activity of alkaline phosphatase, 1 log higher than that of hamster kidney fibroblasts (BHK 13) and 1 log lower than that of osteoblastic osteosarcoma cells (ROS 17/2). When cultured for 4 or 8 wk in diffusion chambers (DC) implanted in athymic mice, many of the HDP cells underwent odontoblastic morphodifferentiation with very long, single processes extending into the matrix. This matrix contained banded and unbanded collagen fibers. Neither light nor electron microscopy of the DC content revealed mineral deposits. These results suggest that HDP cells have an intrinsic potential for partial odontoblastic differentiation; inductive signals like those originating from odontogenic epithelium are probably essential for the completion of hard tissue formation.     

Atrial Septal Defect in a Bonnet Macaque (Macaca radiata)

Atrial Septal Defect was detected at autopsy in a subadult bonnet macaque (Macaca radiata). Case history and autopsy findings were described.     

Study of physiopathological phenomena in dental enamel by neutron activation analysis

An epithermal neutron activation method is used to determine the concentration of mineral elements in human dental enamel. A large number (252) of samples from ancient and modern origins are analyzed. The analytical results are mathematically processed using a statistical multivariant method. This allows to differentiate deciduous from permanent teeth and decayed from sound enamel. It is also possible to distinguish the teeth coming from two different necropoles. The origin and the localization of determined elements in the mineralized part, or in the aqueous-organic part, of enamel is suggested. Their role, as witnessed in the physiopathological phenomena of dental enamel, is discussed.     

Comparison of a Bone Criterion and a dental Criterion for estimation of age at death in the study of an Ancient Cemetery

Two methods, a visual method based on the appearance of the auricular surface of the ilium and a metric method based on two dental criteria, were used in conjunction for estimation of skeletal age at death in paleodemographic study of an ancient cemetery, and were found to be coherent. However, the paleodemographic profiles differed according to sex, indicating a sexual difference in the evolution of the sacroiliac joint.     

A tooth crown morphology framework for interpreting the diversity of primate dentitions

Variation in tooth crown morphology plays a crucial role in species diagnoses, phylogenetic inference, and the reconstruction of the evolutionary history of the primate clade. While a growing number of studies have identified developmental mechanisms linked to tooth size and cusp patterning in mammalian crown morphology, it is unclear (1) to what degree these are applicable across primates and (2) which additional developmental mechanisms should be recognized as playing important roles in odontogenesis. From detailed observations of lower molar enamel–dentine junction morphology from taxa representing the major primate clades, we outline multiple phylogenetic and developmental components responsible for crown patterning, and formulate a tooth crown morphology framework for the holistic interpretation of primate crown morphology. We suggest that adopting this framework is crucial for the characterization of tooth morphology in studies of dental development, discrete trait analysis, and systematics.     

Histological Techniques to Improve Testing of Pulpal Response of Teeth to Filling Material

Two fixation fluids, two fixation techniques and two embedding methods were investigated for their effects on the quality of sections of teeth for pulpal response to filling materials to improve evaluation of pulpal responses. Sections from 32 baboon teeth were prepared, half with experimental cavities and half without, using either 10% formaldehyde or 4% glutaraldehyde, longitudinal tooth splitting or removal of the tooth apex, and paraffin or K plast resin embedding; decalcification in a formic acid mixture was a constant throughout. Histometric analysis showed that paraffin embedding produced less shrinkage than the K Plast resin embedding although the difference was not statistically significant. Six parameters of separation at the pu1p:dentine interface were studied: embedding, fixative, presence or absence of a cavity, cutting technique and individual animal tooth type. Statistical investigation revealed that fixative, cutting technique, and fixative and cutting technique combined had significant influences on the separation artifact. Of the combinations tested the choice of embedding method depends on which of the two artifacts, shrinkage or separation, is more adverse in the opinion of the investigator. Four percent glutaraldehyde together with the longitudinal split technique of fixation. processed by either K Plast resin embedding or paraffin embedding produced satisfactory pulpal sections.