Appearance of ossification centers of the lower arm,wrist, lower leg,and ankle in immature orangutans and chimpanzees with an assessment of the relationship of ossification to dental development

This study examines the appearance of the secondary ossification centers in the lower arms, wrists, lower legs, and ankles of a cross-sectional sample of 20 infant orangutans and chimpanzees (15 of known age). The number of tarsal and carpal centers is analyzed relative to the degree of M₁ development and the weight of individual animals. Variation in the appearance of these ossification centers is discussed relative to these variables and others. In addition, a sequence of appearance is established for the carpal and tarsal ossification centers in the orangutan and data is presented on the status of these centers in a fetal and newborn gorilla. Study results indicate that 1) there is variation in the number of secondary epiphyses present in animals of similar ages; 2) tarsal ossification is completed prior to carpal ossification in the orangutan; 3) there are indications of a relationship between weight and the number of ossification centers present in animals of similar age; and 4) there appears to be no evidence of specific relationships between carpal and tarsal development and M₁ development. © 1996 Wiley-Liss, Inc.     

Relative dental development of Upper Pleistocene hominids compared to human population variation

The relative development of permanent teeth in samples of Neandertal/archaic Homo and Early Modern/Upper Paleolithic hominids is compared to the range of variability found in three recent human samples. Both fossil hominid samples are advanced in relative M2 and M3 development compared to white French-Canadians, but only the Neandertal/archaic Homo M3 sample is advanced when compared to black southern Africans. Both fossil hominid samples are delayed in relative I1 and P3 development compared to the recent human samples. Two hypotheses concerning the significance of the advanced M3 and M2 development found in both hominid groups and southern Africans compared to French-Canadians are discussed. The first postulates that the differences in relative molar development are due simply to variation in tooth/jaw size relationships. The second postulates that the relatively advanced M3 and M2 development found in the fossil hominids and southern Africans is a correlate of their potential for advanced skeletal maturation compared to French-Canadians and other European-derived populations. It appears that dental development patterns have continued to evolve from the Upper Pleistocene to present times, and that Neandertals and Early Moderns shared similar patterns of relative dental development. © 1996 Wiley-Liss, Inc.     

Menarche age,fatness, and fat distribution in Hawaiian adolescents

Menarche age was assessed in 93 adolescent females in a sample of public schools in East Hawaii. Native Hawaiian girls had significantly lower reported age at menarche than non-Hawaiian classmates. Age at menarche was significantly correlated with total fatness as measured by the sum of six skinfolds in girls who had reached menarche at least 2 years previous to measurement. When fatness was controlled in comparisons, the ethnic differences were not significant. Fat distribution, independent of fatness, was also significantly related to age at menarche. Socioeconomic, cultural, and admixture variables were not significantly related to age at menarche. Adiposity appears to be both a cause and a consequence of early age at menarche, with the relationship dependent on the elapsed time between menarche and measurement. This suggests that studies relating body composition to age at menarche must carefully control for the time interval between measurement and the date of menarche. © 1996 Wiley-Liss, Inc.     

Stereoselective metabolism of two keto-pyrrol analogues of 8-hydroxy-2-dipropyl-aminotetralin by freshly isolated rat hepatocytes

In vitro metabolism models have been used to determine the relative metabolic stability of novel 2-aminotetralin analogues for the treatment of CNS diseases. Few of these new compounds had been produced as stereochemically pure materials and the achiral analytical techniques, used initially, measured the average metabolic clearance of the two enantiomers of the racemic mixtures. A chiral HPLC assay, using a Chiral AGP column, was developed for two of these racemic analogues and was used to measure the clearance of the enantiomers from suspensions of freshly isolated rat hepatocytes. Robust separations were obtained for both compounds and a number of metabolic products. The enantiomers of only one analogue were subject to different rates of metabolism. The extent of the difference was dependent upon the initial starting concentration of the incubation. The identity of certain metabolites was investigated using LC/MS. The enantioselectivity appears to have arisen from the restricted hydroxylation of one analogue compared to that of the other. © 1996 Wiley-Liss, Inc.     

Genetic analysis of mutations that alter cell fates in maize leaves: Dominant Liguleless mutations

The three major components of the maize leaf are the blade, the sheath, and at their junction, the ligular region. Each exhibits specific cell types and organization. Four dominant Liguleless (Lg) mutations (Lg3-O, Lg4-O, Lg*347, and Lg*9167) in at least three different genes cause a similar morphological phenotype in leaves, although each mutation affects a distinct domain of the blade. Mutant leaves display regions of altered cell fate in the blade, occompanied by elimination of ligule and auricle at their wild-type positions and development of ligule and auricle in the blade at the borders of the altered regions. The affected blade cells are transformed into sheath-like cells, as determined by morphological and genetic tests. Lg4-O expressivity is highly dependent on genetic background. For example, two different backgrounds may specify converse patterns of phenotypic expression. Lg4-O expressivity is also affected by the heterochronic mutation Teopod2 (Tp2). Gene dosage experiments indicate that Lg4-O is a neomorph. Interactions between recessive lg mutations (which eliminate ligular structures) and the dominant Lg mutations suggest that the lg⁺ genes act after the Lg mutations. Lg3-O and Lg4-O act semidominantly, and interact with each other and with other mutations in the Knotted1 (Kn1)-like family (a family in which dominant mutant alleles cause blade to sheath transformation phenotypes). These interactions suggest that the above Kn1-like mutations may function similarly in the leaf. We discuss the similarities between the Lg mutations and the other mutations of the Kn1-like family, which led us to postulate that lg3 and lg4 are members of a growing family of kn1-like (knox) homeobox genes that are identified by dominant mutant alleles causing leaf transformation phenotypes. We also propose that certain key characteristics of this family of dominant neomorphic mutations are important for generating meaningful morphological changes during evolution. © 1996 Wiley-Liss, Inc.     

A molecular marker confirms that the rate of adult maturation is largely independent of the rate of pre-adult development in Drosophila melanogaster

The separation of adult from pre-adult life seen with animals such as Drosophila melanogaster, which are holometabolous and undergo complete metamorphosis, provides the opportunity to examine the contribution of pre-adult rate of development on the rate of maturation and aging of the adult. Recent work has shown that when ambient temperature is used to alter the rate of development there is little effect on adult life span. From this work it has been concluded that the rate of aging is largely independent of the rate of pre-adult development. However, the techniques used to examine life span did not allow for the examination of the earliest events of adult life. Our experimental design used a molecular marker linked to life span as a sensitive measure of determining physiological age. In this way, we were able to evaluate the effect of pre-adult rate of development on the earliest events of adult life. Using ambient temperature to alter both the rate of development in the pre-adult and the rate of aging in the adult independently, we were able to show that it is the ambient temperature at which the adults are living that is the principle determinant of the rate of maturation and aging of the adult. Little effect was seen on the rate of adult maturation in response to an acceleration or a slowing down of the rate of pre-adult development as measured by our molecular marker. These data support the conclusions drawn by others who examined the effect of the rate of development on adult life expectancy. The timing mechanisms at work during pre-adult and adult life appear to be largely regulated separately. If there is such a thing as a physiological clock, it appears to be reset upon eclosion. © 1996 Wiley-Liss, Inc.     

Polydactyly in the Strong's luxoid mouse is suppressed by limb deformity alleles

The study of limb development has provided insight into pattern formation during vertebrate embryogenesis. Genetic approaches offer powerful ways to identify the critical molecules and their pathways of action required to execute a complex morphogenetic program. We have applied genetic analysis to the process of limb development by studying two mouse mutants, limb deformity (Id) and Strong's luxoid (Ist). These mutations confer contrasting phenotypic alterations to the anteroposterior limb pattern. The six mutant Id alleles are fully recessive and result in oligosyndactyly of all four limbs. By contrast, the two mutant Ist alleles result in a mirror-image polydactylous limb phenotype inherited in a semidominant fashion. Morphological and molecular analysis of embryonic limbs has shown that the Id and Ist alleles affect the extent and distribution of two key signaling centers differentially: the apical ectodermal ridge and the zone of polarizing activity. Molecular characterization of the Id gene has defined a new family of evolutionarily conserved proteins termed the formins. The underlying molecular defect in the Ist mutation has not been identified; however, both loci are tightly linked on mouse chromosome 2, suggesting the possibility that they may be allelic. In this study, we have used genetic analysis to examine the epistatic and allelic relationships of Id and Ist. We observed that in + Id/Ist + double heterozygotes, a single mutant Id allele is able to suppress the semi-dominant polydactylous Ist limb phenotype. By segregating the Ist and Id loci in a backcross, we observed that these loci recombine and are separated by a genetic distance of approximately 6 cM. Therefore, while our observations demonstrate a genetic interaction between Id and Ist, it is probable that Id and Ist are not allelic. Instead, Ist and Id may be operating either in a linear or in a parallel (bypass) genetic pathway to affect the limb signaling centers. © 1996 Wiley-Liss, Inc.