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R S Wells

Publications and source records attributed to R S Wells.

At least 37 records · Page 2Linked to original sources
PubMed1996

Nucleotide variation at the Gpdh locus in the genus Drosophila.

The Gpdh locus was sequenced in a broad range of Drosophila species. In contrast to the extreme evolutionary constraint seen at the amino acid level, the synonymous sites evolve at rates comparable to those of other genes. Gpdh nucleotide sequences were used to infer a phylogenetic tree, and the relationships among the species of the obscura group were examined in detail. A survey of nucleotide polymorphism within D. pseudoobscura revealed no amino acid variation in this species. Applying a modified McDonald-Kreitman test, the amino acid divergence between species in the obscura group does not appear to be excessive, implying that drift is adequate to explain the patterns of amino acid change at this locus. In addition, the level of polymorphism at the Gpdh locus in D. pseudoobscura is comparable to that found at other loci, as determined by a Hudson-Kreitman-Aguadé test. Thus, the pattern of nucleotide variation within and between species at the Gpdh locus is consistent with a neutral model.

Algorithms↗
PubMed1996

Peptides bound endogenously by HLA-Cw*0304 expressed in LCL 721.221 cells include a peptide derived from HLA-E.

The peptide-binding specificity of HLA-Cw*0304 was determined. Sequence analysis of endogenously-bound peptides isolated from Cw*0304 expressed by LCL 721.221 (221 for short) cells transfected with Cw*0304 cDNA revealed this class I allotype preferentially binds peptides possessing alanine at position 2 and leucine or methionine at the C-terminus. One peptide isolated from Cw*0304 expressed by 221 cells has sequence identity to residues 116-126 of HLA-E. Expression of HLA-E by 221 cells was confirmed by isolation of mRNA transcripts for HLA-E*0101 and detection of beta 2-microglobulin (beta 2-m)-associated HLA-E protein.

Cell Line, Transformed↗
PubMed1996

A novel recombinant HLA-B*39 allele (B*3910) in a South African Zulu.

The sequence of a new B*39 allele has been identified in a South African Zulu individual. This allele designated B*3910, differs at two nucleotide positions (246 and 272) from B*39011. The difference at position 246 is silent, while that at position 272 results in an amino acid change from cysteine (B*39011) to tyrosine (B*3910). As these same differences are found in other HLA-B alleles, they were probably introduced into the B*3910 sequence by a short gene conversion event with another allele. This finding provides further evidence for the diversification of HLA-B allelic sequences via recombination.

Alleles↗
PubMed1995

Sequence and evolution of the Drosophila pseudoobscura glycerol-3-phosphate dehydrogenase locus.

The Gpdh genomic region has been cloned and sequenced in Drosophila pseudoobscura. A total of 6.8 kb of sequence was obtained, encompassing all eight exons of the gene. The exons have been aligned with the sequence from D. melanogaster, and the rates of synonymous and nonsynonymous substitution have been compared to those of other genes sequenced in these two species. Gpdh has the lowest rate of nonsynonymous substitution yet seen in genes sequenced in both D. pseudoobscura and D. melanogaster. No insertion/deletion events were observed, and the overall architecture of the gene (i.e., intron sites, etc.) is conserved. An interesting amino acid reversal was noted between the D. melanogaster Fast allele and the D. pseudoobscura gene.

Amino Acid Sequence↗
PubMed1995

Decreased lymphocyte responses in free-ranging bottlenose dolphins (Tursiops truncatus) are associated with increased concentrations of PCBs and DDT in peripheral blood.

Since 1987, large-scale mortalities of dolphins have been reported along the Atlantic coast of North America, in the Gulf of Mexico, and in the Mediterranean Sea. Autopsied bottlenose dolphins, Tursiops truncatus, which were collected from the large-scale mortality along the Atlantic coast in 1987 to 1988, exhibited opportunistic infections indicative of immune dysfunction. Further, these animals had high levels of chlorinated hydrocarbons, such as PCBs and DDT, that can suppress immune functions. The purpose of this study was to determine whether there is a relationship between chemical contaminant exposure and immune response in free-ranging dolphins. In June of 1991, peripheral blood was obtained from members of a bottlenose dolphin population that resides along the west coast of Florida. Peripheral blood lymphocyte responses to Concanavalin A (Con A) and phytohemagglutinin (PHA) were determined in vitro and compared by regression analysis with contaminant concentrations in whole blood from a small subset of these animals (n = 5). These data indicate that a reduced immune response in these bottlenose dolphins was correlated with increasing whole blood concentrations of several contaminants. Specifically, inverse correlations were found between Con A-induced lymphocyte proliferation and tetrachlorinated to octachlorinated biphenyls (r2 values ranged from 0.70 to 0.87). Con A-induced lymphocyte responses also correlated inversely with p,p'DDT (r2 values of 0.73 and 0.79); o.p'-DDE (r2 values of 0.93 and 0.96); and p,p'-DDE (r2 values of 0.73 and 0.81).

Animals↗
PubMed1995

Development of an interleukin-2 receptor expression assay and its use in evaluation of cellular immune responses in bottlenose dolphin (Tursiops truncatus).

We describe optimization of a peripheral blood mononuclear leukocyte proliferation assay and development of an interleukin-2 receptor (IL-2R) expression assay for bottlenose dolphins (Tursiops truncatus). Peripheral blood mononuclear leukocytes obtained from both Sea World (February 1993) and the Naval Command Control and Ocean Surveillance Center (March 1993) (San Diego, California, USA) were stimulated with the mitogens concanavalin A (ConA) and phytohemagglutinin (PHA) and evaluated for optimum proliferation and IL-2R expression. Based on these optimization assays, standard conditions were established and used to assess immune function in a population of apparently healthy, free-ranging bottlenose dolphins from Sarasota Bay, Florida (USA) in June 1993. A positive correlation was observed between proliferation assays using ConA and PHA as the stimulants. However, IL-2R expression induced by both mitogens differed significantly.

Animals↗
PubMed1990

Assignment of six enzyme loci to multipoint linkage groups in fishes of the genus Poeciliopsis (Poeciliidae): designation of linkage groups III-V.

Three new linkage groups of enzyme loci are described using Poeciliopsis monacha x P. viriosa-derived interspecific backcross hybrids. Comparison to known linkage groups of the confamilial genus Xiphophorus shows homology between Xiphophorus linkage group I and Poeciliopsis linkage group III, Xiphophorus linkage group II and Poeciliopsis linkage group I, and Xiphophorus linkage group IV and Poeciliopsis linkage group IV. Comparison of the gene content of other fish, amphibians, and mammal syntenic groups suggests retention of plesiomorphic vertebrate gene arrangements in at least two poeciliid linkage groups. Expansion of the Poeciliopsis gene map should be of utility in the identification of tumor regulatory genes through demonstration of linkage to biochemical markers.

Animals↗
PubMed1989

Familial keratoses of actinic distribution associated with internal malignancy and cellular hypersensitivity to UVA.

In members of a family there appeared to be an association between the development of cutaneous pigmented keratoses in sun-exposed sites, and the later evolution of internal malignancies, particularly carcinoma of the uterus. Affected individuals were not clinically photosensitive, but their fibroblasts demonstrated gross cytopathic changes, low survival indices and an increased frequency of DNA single strand breaks following exposure to long-wave ultraviolet radiation (UVA). These clinical and cellular features appear to identify an unrecognized syndrome that may not be uncommon. Recognition of this syndrome in a family may prevent certain malignancies developing in those affected.

Adult↗
PubMed1989

Inferring emotions from multiple cues: revealing age-related differences in "how" without differences in "can".

This study examined differences in children's use of social cues to make emotional inferences. Children ages 4, 5, and 8 years were presented with stimuli that depicted another child in affectively congruous and affectively incongruous expression/situation combinations. The intensity of positive and negative facial expressions was varied across situations. Subjects judged the target's feelings and selected among the alternative facial expressions or situations the one they had just seen. No significant age-related differences were found in the extent to which children registered and used both the expressive and situational information when making emotional inferences. The main experimental measure asked children to explain their judgments. In explaining their judgments, subjects' rationales indicated that they: (a) used both the situational and expressive cues; and (b) were sensitive to congruous versus incongruous cues, and even to mild versus strong incongruous cues. Children's rationales also reflected a sensitivity to expressive and situational negativity. For each age group, the rationales were more elaborate when the cues were problematic. Characteristic strategies, however, were also found for each age group. These distinct strategies may reflect social-life changes in children's social "theories" of emotion.

Age Factors↗
PubMed1988

Differentiation of ICM cells into trophectoderm.

It has been established previously that when inserted in the blastocyst E Ca 247 preferentially differentiates into trophectoderm in vitro. If the concept that tumors are caricatures of the process of tissue renewal is correct, then some cells from the inner cell mass (ICM), the normal counterpart of embryonal carcinoma, should be able to differentiate into trophectoderm. This has been a controversial issue. Four experiments are now reported that support the idea that ICM can differentiate into trophectoderm: 1) ICM from early blastocysts after classical immunosurgery made blastocysts in vitro; 2) ICM obtained from early blastocysts by immunosurgery using antigens other than histocompatibility ones made blastocysts in vitro; 3) ICM from early blastocysts, in which the trophectodermal cells had been labeled, contained no labeled cells following immunosurgery; and 4) In reconstruction experiments, polar and mural trophectodermal cells attached to ICM from late blastocysts failed to multiply and make blastocysts when cultured. It is concluded that like the embryonal carcinoma some ICM cells of early blastocysts have the potential to make trophectoderm. This fact is consistent with the concept that tumors are caricatures of the process of tissue renewal; and establishes E Ca 247 as a good model for study of trophectodermal differentiation.

Animals↗
PubMed1987

Pachyonychia congenita with cutaneous amyloidosis and hyperpigmentation--a distinct variant.

Two kindreds manifesting an unusual form of pachyonychia congenita are described. Clinical involvement consists of nail dystrophy, which tends to improve with age, and moderate palmoplantar hyperkeratosis. In addition, all affected members show a characteristic pattern of cutaneous hyperpigmentation, which resembles macular amyloidosis around the neck and waist, but which confers a dappled appearance to the axillae, popliteal fossae, thighs, buttocks, and lower aspect of the abdomen. With advancing age the pigmentation fades. Histologic and ultrastructural examination of the hyperpigmented skin has revealed pigmentary incontinence and deposition of amyloid within the papillary dermis. These features appear to constitute a distinct variant of pachyonychia congenita.

Adolescent↗
PubMed1987

The fate of embryonal-carcinoma cells in mouse blastocysts.

Double-labeled embryonal-carcinoma (ECa) cells were injected into blastocysts or incorporated into blastocysts by aggregation, and their fate after various periods of time in culture was investigated. ECa-247 cells labeled with fluorescent microscopheres were easily identified in whole blastocysts. These blastocysts were embedded in plastic, serially sectioned, and prepared for autoradiography. The 3H-thymidine label on the embryonal-carcinoma cells allowed precise localization of the cancer-derived cells. ECa-247 cells preferentially localized in the mural trophectoderm, with a few being seen in primitive endoderm and, even more rarely, in the inner cell mass. Selected autoradiograms were re-embedded and thin sectioned for transmission electron microscopy. The cancer-derived cells were found to have differentiated in accordance with their localization.

Animals↗
PubMed1986

Regulation of melanoma by the embryonic skin.

This report focuses on the regulation of murine melanoma by the embryonic skin. A surgical technique was developed to allow injection of B16 melanoma cells into the embryo in utero. A significant decrease in incidence of tumors was noted, which correlated with the time of arrival of normally migrating premelanocytes into the skin. Media were conditioned from skin explanted at the time premelanocytes arrive in it; these media inhibited the growth of melanoma cells in vitro. Under optimal conditions the growth of melanoma cells ceased; the cells had altered morphology and failed to proliferate when placed in fresh growth media.

Animals↗