Urbanization and Identity Dissonance: A Guajiro Case

The results of this study indicate that urbanization has the effect of significantly altering the Guajiro's sense of ideal and feared identity. It was hypothesized that an attempt would be made to minimize dissonance between the ideal and the real or "true" self which the individual privately acknowledges. However, there is found to be considerable dissonance between ideal and real identities, with the latter actually including many components of feared identity. Defective socialization in the city is suggested as a possible reason for failure to achieve ideal standards.     

The Effect of 17 β-Estradiol and Estrone on Intermediary Metabolism of the Pyloric Caeca of the Asteroid Luidia clathrata (Say) Maintained under Different Nutritional Regimes

Luidia clathrata were fed either a high or low level of food and injected with estradiol, estrone, or seawater for 16 days. In individuals maintained at a low level of food, the weight of the pyloric caeca decreased in all individuals, regardless of hormone injections. Activities of all enzymes in these individuals were lower than in individuals maintained at a high level of food. In the individuals maintained at a low level of food, the activity of GPDH was higher in the pyloric caeca of individuals injected with estradiol and estrone than in those receiving seawater injections; the activity of 6-PGDH decreased in those injected with estrone. In individuals maintained at a high level of food, the activities of glucose-6-phosphate dehydrogenase (G–6–PDH) and 6-phosphogluconate dehydrogenase (6–PGDH) were higher in individuals injected with estradiol than in those receiving seawater injections. Activities of glycerol phosphate dehydrogenase (GPDH) and pyruvate kinase (PK) were not affected. A slight decrease (P<0.1) in the activity of 6–PGDH was seen with injection of estrone. These results suggest that steroids have a role in regulating cellular metabolism in the pyloric caeca, and that nutritional condition influences the response of the pyloric caeca to steroids. In addition, these results indicate that the nutritional condition of the individual directly influences enzyme activities.     

Genetic Characterization and Use of a Restriction Fragment Length Variant in the Hypotrichous Ciliate Euplotes crassus1

Two forms of a macronuclear DNA molecule differing in the presence or absence of a restriction endonuclease recognition site have been detected in the hypotrichous ciliate Euplotes crassus. Through a series of genetic crosses the two forms were shown to be allelic, being derived from a single micronuclear genetic locus. This restriction fragment length variant (RFLV) was used as a genetic marker to determine that the migratory and stationary pronuclei generated during mating can be genetically non-identical. In addition, the RFLV was used to investigate the efficiency of processing of the alternate alleles during macronuclear development and their subsequent transmission during vegetative growth. Little or no bias in the processing and/or amplification of the two alleles was observed during macronuclear development. During vegetative growth, however, changes in the relative amounts of the two alleles were observed.     

A comparative description of mitochondrial DNA differentiation in selected avian and other vertebrate genera

Levels of mitochondrial DNA (mtDNA) sequence divergence between species within each of several avian (Anas, Aythya, Dendroica, Melospiza, and Zonotrichia) and nonavian (Lepomis and Hyla) vertebrate genera were compared. An analysis of digestion profiles generated by 13-18 restriction endonucleases indicates little overlap in magnitude of mtDNA divergence for the avian versus nonavian taxa examined. In 55 interspecific comparisons among the avian congeners, the fraction of identical fragment lengths (F) ranged from 0.26 to 0.96 (F = 0.46), and, given certain assumptions, these translate into estimates of nucleotide sequence divergence (p) ranging from 0.007 to 0.088; in 46 comparisons among the fish and amphibian congeners, F values ranged from 0.00 to 0.36 (F = 0.09), yielding estimates of P greater than 0.070. The small mtDNA distances among avian congeners are associated with protein-electrophoretic distances (D values) less than approximately 0.2, while the mtDNA distances among assayed fish and amphibian congeners are associated with D values usually greater than 0.4. Since the conservative pattern of protein differentiation previously reported for many avian versus nonavian taxa now appears to be paralleled by a conservative pattern of mtDNA divergence, it seems increasingly likely that many avian species have shared more recent common ancestors than have their nonavian taxonomic counterparts. However, estimates of avian divergence times derived from mtDNA- and protein-calibrated clocks cannot readily be reconciled with some published dates based on limited fossil remains. If the earlier paleontological interpretations are valid, then protein and mtDNA evolution must be somewhat decelerated in birds. The empirical and conceptual issues raised by these findings are highly analogous to those in the long-standing debate about rates of molecular evolution and times of separation of ancestral hominids from African apes.      

Methods for computing the standard errors of branching points in an evolutionary tree and their application to molecular data from humans and apes

Statistical methods for computing the standard errors of the branching points of an evolutionary tree are developed. These methods are for the unweighted pair-group method-determined (UPGMA) trees reconstructed from molecular data such as amino acid sequences, nucleotide sequences, restriction-sites data, and electrophoretic distances. They were applied to data for the human, chimpanzee, gorilla, orangutan, and gibbon species. Among the four different sets of data used, DNA sequences for an 895-nucleotide segment of mitochondrial DNA (Brown et al. 1982) gave the most reliable tree, whereas electrophoretic data (Bruce and Ayala 1979) gave the least reliable one. The DNA sequence data suggested that the chimpanzee is the closest and that the gorilla is the next closest to the human species. The orangutan and gibbon are more distantly related to man than is the gorilla. This topology of the tree is in agreement with that for the tree obtained from chromosomal studies and DNA-hybridization experiments. However, the difference between the branching point for the human and the chimpanzee species and that for the gorilla species and the human-chimpanzee group is not statistically significant. In addition to this analysis, various factors that affect the accuracy of an estimated tree are discussed.      

Anonymous nuclear DNA markers in the American oyster and their implications for the heterozygote deficiency phenomenon in marine bivalves

A puzzling population-genetic phenomenon widely reported in allozyme surveys of marine bivalves is the occurrence of heterozygote deficits relative to Hardy-Weinberg expectations. Possible explanations for this pattern are categorized with respect to whether the effects should be confined to protein-level assays or are genomically pervasive and expected to be registered in both protein- and DNA-level assays. Anonymous nuclear DNA markers from the American oyster were employed to reexamine the phenomenon. In assays based on the polymerase chain reaction (PCR), two DNA-level processes were encountered that can lead to artifactual genotypic scorings: (a) differential amplification of alleles at a target locus and (b) amplification from multiple paralogous loci. We describe symptoms of these complications and prescribe methods that should generally help to ameliorate them. When artifactual scorings at two anonymous DNA loci in the American oyster were corrected, Hardy-Weinberg deviations registered in preliminary population assays decreased to nonsignificant values. Implications of these findings for the heterozygote-deficit phenomenon in marine bivalves, and for the general development and use of PCR-based assays, are discussed.