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Biomedical subjects

G Calhoun

Publications and source records attributed to G Calhoun.

15 recordsLinked to original sources
PubMed1999

An N-terminal truncation uncouples the sex-transforming and dosage compensation functions of sex-lethal.

In Drosophila melanogaster, Sex-lethal (Sxl) controls autoregulation and sexual differentiation by alternative splicing but regulates dosage compensation by translational repression. To elucidate how Sxl functions in splicing and translational regulation, we have ectopically expressed a full-length Sxl protein (Sx.FL) and a protein lacking the N-terminal 40 amino acids (Sx-N). The Sx.FL protein recapitulates the activity of Sxl gain-of-function mutations, as it is both sex transforming and lethal in males. In contrast, the Sx-N protein unlinks the sex-transforming and male-lethal effects of Sxl. The Sx-N proteins are compromised in splicing functions required for sexual differentiation, displaying only partial autoregulatory activity and almost no sex-transforming activity. On the other hand, the Sx-N protein does retain substantial dosage compensation function and kills males almost as effectively as the Sx.FL protein. In the course of our analysis of the Sx.FL and Sx-N transgenes, we have also uncovered a novel, negative autoregulatory activity, in which Sxl proteins bind to the 3' untranslated region of Sxl mRNAs and decrease Sxl protein expression. This negative autoregulatory activity may be a homeostasis mechanism.

3' Untranslated Regions↗
PubMed1996

Sex-specific control of Sex-lethal is a conserved mechanism for sex determination in the genus Drosophila.

In D. melanogaster the binary switch gene Sex-lethal (Sxl) plays a pivotal role in somatic sex determination -- when the Sxl gene is on the female pathway is followed, while the male pathway is followed when the gene is off. In the present study we have asked whether the Sxl gene is present in other species of the genus Drosophila and whether it is subject to a similar sex-specific on-off regulation. Sxl proteins were found in all of the drosophilids examined, and they display a sex-specific pattern of expression. Furthermore, characterization of the Sxl gene in the distant drosophilan relative, D. virilis, reveals that the structure and sequence organization of the gene has been well conserved and that, like melanogaster, alternative RNA processing is responsible for its sex-specific expression. Hence, this posttranscriptional on-off regulatory mechanism probably existed before the separation of the drosophilan and sophophoran subgenera and it seems likely that Sxl functions as a sex determination switch gene in most species in the Drosophila genus. Although alternative splicing appears to be responsible for the on-off regulation of the Sxl gene in D. virilis, this species is unusual in that Sxl proteins are present not only in females but also in males. The D. virilis female and male proteins appear to be identical over most of the length except for the amino-terminal approx. 25 aa which are encoded by the differentially spliced exons. In transcriptionally active polytene chromosomes, the male and female proteins bind to the same cytogenetic loci, including the sites corresponding to the D. virilis Sxl and tra genes. Hence, though the male proteins are able to interact with appropriate target pre-mRNAs, they are apparently incapable of altering the splicing pattern of these pre-mRNAs.

Alternative Splicing↗
PubMed1993

The neophyte female delinquent: a review of the literature.

During the 1950s, most of the attention on juvenile delinquency concentrated on males. Recently, however, the incidence of female delinquency has escalated. Female delinquency that did exist a generation ago centered primarily on sexual misconduct; today, much greater numbers of females are involved in armed robbery, gang activity, drug trafficking, burglary, weapons possession, aggravated assault, and prostitution. Research on the etiology of this behavior is inconclusive, with some of the theories centering around dysfunctional families, victimization, aggression, neglect, rejection, physical and sexual abuse, self-perception, gender role, and intellectual ability. This paper attempts to ascertain the status of female delinquency, with special focus on definition, etiology, and treatment.

Adolescent↗
PubMed1987

Enhancing self-perception through bibliotherapy.

Bibliotherapy has been used for generations by professionals in medicine, psychology, counseling, social work, and education. A selected review of the literature is provided to show how bibliotherapy was used in the past and how it is currently employed to implement and facilitate self-identification and to enhance self-perception. Researchers concur that the process of providing pupils with carefully monitored literature will result in positive or negative changes in their self-perception.

Adolescent↗
PubMed1986

Hypnotherapy: a possible alternative for treating pupils affected with attention deficit disorder.

The purpose of this study was to ascertain the effectiveness of hypnotherapy in treating attention-deficit-hyperactivity by certified psychologist and physicians. The 7 boys and 4 girls were enrolled in a Special Day classroom for hyperkinesis and behavior problems and were being given methylphenidate (Ritalin). Three attempts were made to hypnotize these subjects; however, the group had to be reduced from 11 to 3 and finally, from 3 to a single child to be successful. A significant improvement from pre- and post-hypnotic sessions was noted.

Attention Deficit Disorder with Hyperactivity↗
PubMed1984

Comparison of delinquents and nondelinquents in ethnicity, ordinal position, and self-perception.

Compared three groups of black, white, and Mexican-American delinquent and nondelinquent males, aged 11 to 18, on measures of self-concept, self-esteem, and ordinal position by groups (N = 135). Data were analyzed with analysis of variance and Chi-square test. Significant main effects were found with respect to delinquency, self-concept, and self-esteem. A significant interaction was present for delinquency and ethnicity for both self-concept and self-esteem. Chi-square results found birth-order and ethnicity to be related significantly.

Adolescent↗
PubMed1978

An ethnic comparison of self-esteem in Portuguese-, Mexican-, and Anglo-American pupils.

Three groups of Portuguese-, Mexican-, and Anglo-American boys and girls (N - 158) from 5th through 8th grade were compared in self-esteem. The results of the chi square test indicated that there were no significant differences between Mexican and Anglo Ss. However, significant differences were observed when the Portuguese Ss were compared to the other two groups. Here it was discovered that Portuguese boys--but not girls--had significantly higher self-esteem than all other Ss.

Child↗