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Men in nursing: issues of gender segregation and hidden advantage.

The small but growing number of men in the nursing profession does not herald a progressive integration of masculine and feminine sex roles. The evidence presented in this paper suggests that even in female-dominated occupations such as nursing, patriarchal gender relations which reflect a high valuation of all that is male and masculine, play a significant role in situating a disproportionate number of men in administrative and elite specialty positions. At the heart of this gender dynamic is the need to separate the masculine from the lesser valued feminine. Male nurses do this by employing strategies that allow them to distance themselves from female colleagues and the quintessential feminine image of nursing itself, as a prerequisite to elevating their own prestige and power. They are aided in this task by patriarchal cultural institutions that create and perpetuate male advantage, as well as by women nurses themselves who, consciously or unconsciously, nurture the careers of men colleagues.

Career Mobility↗

The ovary retains male potential after the thermosensitive period for sex determination in the turtle Emys orbicularis.

Emys orbicularis is a turtle with temperature-dependent sex determination. The thermosensitive period (TSP) lies between embryonic stages 16 and 22. Gonadal differentiation begins during this period involving oestrogens. Treatment with oestrogens during TSP results in the differentiation of ovaries at a male-producing temperature (25 degrees C), whereas treatment with an antioestrogen (tamoxifen) or with nonsteroidal aromatase inhibitors results in gonadal masculinization at a female-producing temperature (30 degrees C). The present study examines the effects on the ovary of inhibiting aromatase activity after TSP. Eggs of E. orbicularis incubated at 30 degrees C were given five or seven applications of 10 micrograms aromatase inhibitor Letrozole (CGS 20267) in ethanol, between stages 22+ and 24-25 when ovarian aromatase activity strongly increases. Individuals which received five applications were sacrificed at stages 24(+)-25. Those which received seven applications were sacrificed either at stage 25+ (close to hatching), or 34-36 days after hatching. Gonadal aromatase activity and related gonadal structure were studied in each individual. In the three series, the gonadal aromatase activity in individuals treated with Letrozole varied from similar or close to that in controls to much lower, and the gonadal structure varied from ovary-like to ovotestis. Ovotestes had the lowest levels of aromatase activity, under 4 fmoles/h/gonad, close to testis levels. They were found in 7 out of 26 individuals given Letrozole. Besides ovotestes, gonads presenting various degrees of masculinization, with enlarged epithelial cords and lacunae in the medulla, were found. Therefore, by inhibiting aromatase activity and thus estrogen synthesis, we were able to obtain the differentiation of testis-like cords or tubes in ovaries of E. orbicularis, after the period of temperature sensitivity. These results show that the ovary retains male potential after this period. Thus, besides their implication during the critical embryonic period for gonadal sex differentiation, oestrogens play a role in maintaining the ovarian structure after this period. A decrease in oestrogen levels could explain some other cases of ovarian masculinization known in vertebrates.

Analysis of Variance↗

The role of a clinical score in the assessment of ambiguous genitalia.

OBJECTIVE: To improve the initial assessment of ambiguous genitalia in infants. SUBJECTS AND METHODS: Using a specially devised scoring system, the external genitalia (external masculinization score, EMS, range 0-12) and internal reproductive structures (internal masculinization score, IMS, range 0-10) were assessed in 426 male newborns and 291 cases of ambiguous genitalia. RESULTS: In normal male newborns, the median (10th centile) EMS was 11 (10). In the affected infants, the sex of rearing was male in 202 and female in 89 cases, respectively. The median (10-90th centile) EMS in those cases reared male, at 3.5 (2-8), was significantly higher than in cases reared as females, at 2 (1-6) (P < 0.001). The median IMS in cases reared as males and females was the same, at 10, but the scatter of values was higher for males (10-90th centile, 4-10) than for females (0-10) (P = 0.01). Infants reared as females were more likely to have a micropenis, a uterus and/or a urogenital sinus, but there were 12 cases where the sex of rearing was male despite the presence of a uterus; five infants without micropenis were reared as female and 23 with a urogenital sinus were reared as male. CONCLUSION: The masculinization score provides a standardized format to summarize clinical features in newborn infants with ambiguous genitalia. Gender assignment does not solely depend on the appearance of the external genitalia and the nature of internal sexual organs.

Disorders of Sex Development↗

The relationship of maternal personality characteristics to birth outcomes and infant development.

BACKGROUND: Previous studies reported an association between maternal psychological factors and adverse pregnancy outcomes. The objective of this study was to evaluate the relationships between maternal personality characteristics, as determined by the Minnesota Multiphasic Personality Inventory (MMPI), and infant birth outcomes and development. METHOD: The inventory was administered during pregnancy to 638 pregnant women enrolled in a staff model health maintenance organization. MMPI validity as well as clinical and research scales were evaluated in relationship to infant birth outcomes (low birthweight, preterm birth) and 15-month-old infant development as assessed by the Bayley Scales of Infant Development. RESULTS: Mothers of low birthweight infants scored significantly lower on the hypochondriasis scale, a relationship which was no longer significant after controlling for ethnicity. No other relationships were observed between infant birth outcomes and maternal MMPI scale scores. A higher infant Mental Developmental Index (MDI) was related to higher maternal masculinity-femininity and ego-strength scale scores and lower lie and hypochondriasis scale scores. Only the relationship between infant MDI and maternal masculinity-femininity scale score remained significant after controlling for ethnicity and socioeconomic index (beta = 0.104, p = 0.036). CONCLUSIONS: Maternal personality characteristics, as determined by the MMPI, did not appear to be significantly related to the occurrence of preterm birth or low birthweight in this healthy, general population. Maternal personality characteristics reflected in the MMPI masculinity-femininity scale appeared to be related to infant mental development, above and beyond the effects of socioeconomic status and ethnicity.

Adaptation, Psychological↗

The Caenorhabditis elegans F-box protein SEL-10 promotes female development and may target FEM-1 and FEM-3 for degradation by the proteasome.

The Caenorhabditis elegans F-box protein SEL-10 and its human homolog have been proposed to regulate LIN-12 Notch signaling by targeting for ubiquitin-mediated proteasomal degradation LIN-12 Notch proteins and SEL-12 PS1 presenilins, the latter of which have been implicated in Alzheimer's disease. We found that sel-10 is the same gene as egl-41, which previously had been defined by gain-of-function mutations that semidominantly cause masculinization of the hermaphrodite soma. Our results demonstrate that mutations causing loss-of-function of sel-10 also have masculinizing activity, indicating that sel-10 functions to promote female development. Genetically, sel-10 acts upstream of the genes fem-1, fem-2, and fem-3 and downstream of her-1 and probably tra-2. When expressed in mammalian cells, SEL-10 protein coimmunoprecipitates with FEM-1, FEM-2, and FEM-3, which are required for masculinization, and FEM-1 and FEM-3 are targeted by SEL-10 for proteasomal degradation. We propose that SEL-10-mediated proteolysis of FEM-1 and FEM-3 is required for normal hermaphrodite development.

Animals↗

Sexually dimorphic expression of trkB, a Z-linked gene, in early posthatch zebra finch brain.

Sexual differentiation of the zebra finch (Taeniopygia guttata) neural song circuit is thought to be initiated by sex differences in sex chromosome gene expression in brain cells. One theory is that Z-linked genes, present in the male's ZZ genome at double the dose of females' (ZW), are expressed at higher levels and trigger masculine patterns of development. We report here that trkB (tyrosine kinase receptor B) is Z-linked in zebra finches. trkB is the receptor for neurotrophic factors BDNF and neurotrophin 4, and mediates their influence on neuronal survival, migration, and specification. trkB mRNA is expressed at a higher level in the male telencephalon or whole brain than in corresponding regions of the female in adulthood, and at posthatch day (P) 6, when the song circuit is undergoing sexual differentiation. Moreover, this expression is higher in the song nucleus high vocal center (HVC) than in the surrounding telencephalon at P6, and in males relative to females. In addition, trkB protein is expressed more highly in male than female whole brain at P6. These results establish trkB as a candidate factor that contributes to masculine differentiation of HVC because of its Z-linkage, which leads to sex differences in expression. BDNF is known to be stimulated by estrogen and to be expressed at higher levels in males than females at later ages in HVC. Thus, the trkB-BDNF system may be a focal point for convergent masculinizing influences of Z-linked factors and hormones.

Animals↗

Neural, not gonadal, origin of brain sex differences in a gynandromorphic finch.

In mammals and birds, sex differences in brain function and disease are thought to derive exclusively from sex differences in gonadal hormone secretions. For example, testosterone in male mammals acts during fetal and neonatal life to cause masculine neural development. However, male and female brain cells also differ in genetic sex; thus, sex chromosome genes acting within cells could contribute to sex differences in cell function. We analyzed the sexual phenotype of the brain of a rare gynandromorphic finch in which the right half of the brain was genetically male and the left half genetically female. The neural song circuit on the right had a more masculine phenotype than that on the left. Because both halves of the brain were exposed to a common gonadal hormone environment, the lateral differences indicate that the genetic sex of brain cells contributes to the process of sexual differentiation. Because both sides of the song circuit were more masculine than that of females, diffusible factors such as hormones of gonadal or neural origin also likely played a role in sexual differentiation.

Animals↗

Interpulse growth hormone secretion in the episodic plasma profile causes the sex reversal of cytochrome P450s in senescent male rats.

Humans as well as other mammals experience an aging-related decline in drug metabolism as well as a diminution in growth hormone secretion. In the case of rats, these events are more pronounced in senescent males, whose expression of male-specific isoforms of cytochrome P450, the major drug-metabolizing enzymes and constituting approximately 60-70% of the total cytochrome P450 in male rat liver, is completely suppressed, whereas female-dependent isoforms are remarkably induced to female-like levels. Overlooked in these independently reported studies is the fact that "signals" inherent in the masculine episodic and female continuous growth hormone profiles regulate expression and/or suppression of the dozen or so sex-dependent cytochrome P450 isoforms in rat liver. Whereas previous studies identified profound reductions in the pulse amplitudes of the masculine growth hormone profile as the cause for the diminished hormone secretion during aging, pulse heights are not recognized by the cytochromes as regulatory signals. Instead, we have shown that just a nominal secretion of growth hormone during the usual growth hormone-devoid interpulse period in the masculine episodic profile can explain the complete repression of male-specific CYP2C11, CYP3A2, and CYP2A2 and induction of female-dependent CYP2C12, CYP2C6, and CYP2A1 observed in senescent male rats.

Aging↗

Gender schema and gender role discrepancy as correlates of body image.

Past studies of gender role and body image have focused on women's self-reported levels of femininity and masculinity as correlates of body dissatisfaction and eating disorders. This study explored how college-aged women's and men's self-reported discrepancies in actual and ideal femininity and masculinity are linked to three measures of body image. For this group of women, physical size, but not gender role discrepancy, was predictive of body image. For the men, in addition to physical size, falling short of their masculine ideal was predictive of more negative body image. Results are discussed in relation to gender schema theory and cultural ideals of female thinness and male muscularity.

Adolescent↗

The influence of sex, gender, self-discrepancies, and self-awareness on anger and verbal aggressiveness among U.S. college students.

Among a sample of 445 U.S. college students, the authors examined the extent to which individual differences (e.g., sex, gender, self-discrepancies, self-awareness) explained anger tendencies and verbal aggressiveness. Regression analyses showed that (a) the tendency to repress anger (anger-in) was explained by masculinity, desire to be masculine, and public self-awareness, R2 = .19, F(11, 433) = 8.44, p < .001; (b) the tendency to express anger (anger-out) was explained by sex, masculinity, and public self-awareness, R2 = .17, F(11, 433) = 7.38, p < .001; and (c) willingness to be verbally aggressive was explained by sex, femininity, and private self-awareness, R2 = .32, F(11, 433) = 16.94, p < .001. In addition, different types of individual difference variables accounted for anger tendencies and verbal aggressiveness across sex and gender categories, suggesting that anger and verbal aggressiveness may be driven by different psychological processes across types of participants.

Adolescent↗

Social perceptions of male and female extreme mesomorphs.

In this study, male and female university students in the United States were exposed to mesomorphic or nonmesomorphic stimuli as reflected by photographs of either male body builders and non-body builders or female body builders and non-body builders. Then they were asked to attribute various personality traits and sex-role behaviors to them. Subjects, irrespective of their sex, perceived male and female body builders as possessing more traditionally masculine and less traditionally feminine personality characteristics than male and female non-body builders. Also, male and female body builders were seen as possessing less socially desirable traits than non-body builders. As predicted, female body builders were perceived generally as being more likely to engage in traditionally masculine sex-role behaviors in their dating and marriage relationships than female non-body builders. Contrary to expectation, however, male body builders were not perceived as more likely to engage in higher levels of masculine sex-role behaviors than male non-body builders.

Adult↗

Gender and self-disclosure revisited: personal and contextual variations in self-disclosure to same-sex acquaintances.

Male and female American students who differed in masculinity and in femininity self-disclosed to a same-sex stranger in contexts that made either social/expressive motives or instrumental motives salient. The results were consistent with the primary assertion that measures of sex role identity are better predictors of contextual variations in self-disclosure than is sex per se. Sex consistently failed to predict subjects' willingness to self-disclose, both within and across contexts, whereas femininity promoted self-disclosure in the context that was clearly social and expressive in character. Although masculinity failed to exert the expected facilitative impact on self-disclosure within the instrumental context, it nonetheless influenced the results; androgynous subjects, who scored high in both masculinity and femininity, were more self-revealing across contexts than was any other group.

Adult↗

Sex differences in cardiovascular reactivity as a function of the appraised gender relevance of the stressor.

Previous research suggests that sex differences in cardiovascular reactivity are a function of the gender relevance of the stressor. The authors examined the role of a stressor's gender relevance as a mediator of sex differences in cardiovascular reactivity. The cardiovascular reactivity of 121 male and female college students to the cold-pressor test was compared under feminine- and masculine-relevant stressor instructions. The women were expected to show greater cardiovascular reactivity than the men were to the test relevant to women, whereas the men were expected to show greater cardiovascular reactivity than the women were to the masculine cold-pressor test. Results supported these predictions for systolic blood pressure reactivity, but not heart rate reactivity. Diastolic blood pressure results were mixed. The women showed greater diastolic reactivity than the men did to the feminine-relevant test, but the men did not show greater diastolic reactivity than the women did to the masculine test. The influence of sex differences in cognitive appraisal of situations on cardiovascular reactivity and coronary heart disease is discussed.

Adolescent↗

Sexual mimicry in hyenas.

Genital masculinization in female spotted hyenas has been widely explained as an incidental consequence of high androgen levels. High androgen levels, in turn, were supposed to be favored because they led to adaptive aggressive behavior. Incidental androgenization is no longer a tenable hypothesis, however, because genital masculinization has been shown to proceed in the absence of androgenic steroids. Thus, an alternative hypothesis is required. The genitals of spotted hyena females are not simply masculinized, but exhibit a detailed physical resemblance to the male genitalia. In the absence of satisfactory alternative explanations, we propose that selection may have favored sexual mimicry in females because they are more likely than males to be targets of aggression from other females. Male-like camouflage could theoretically be protective in three contexts: neonate sibling aggression, infanticide by conspecific females, and interclan territoriality. Current data suggest that if sexual mimicry is important, its effects are strongest among infants.

Aggression↗

How do we decide that a species is sex-role reversed?

Defining sex roles has been driven by differences in mating systems at the extreme: polygyny and polyandry. Roles may reverse depending on which sex limits the reproductive rate of the other, and it is generally the female that limits the male. Males therefore compete for female mates. But in species in which the male limits the reproductive rate of the female, the female competes for male mates and assumes the masculine role. Complications arise, however, in species with typical roles when males are temporarily limiting, and females then briefly compete for and display to males. Problems also occur among tightly monogamous species with biparental care, where the mates have equal reproductive rates; both males and females compete intrasexually for mates. Despite this, monogamous species have masculine and feminine roles, typically manifested as the male dominating the female. Some monogamous species are nevertheless sex-role reversed. The pervasive behavioral mechanism characterizing the masculine role is dominance through aggression, size, or both. Attending more to behavioral mechanisms will enrich our understanding of sex-role reversal.

Aggression↗

Sex determination in the nematode C. elegans: analysis of tra-3 suppressors and characterization of fem genes.

Mutations of the gene tra-3 result in partial masculinization of XX animals of C. elegans, which are normally hermaphrodites (males are XO). A total of 43 tra-3 revertants (one intragenic, 42 extragenic) have been isolated and analyzed, in the hope of identifying new sex-determination loci. Most (38) of the extra-genic suppressors cause partial or complete feminization of XX and XO animals; the remaining four are weak suppressors. The feminizing suppressors are mostly alleles of known sex-determining genes: tra-1 (11 dominant alleles), tra-2 (one dominant allele), fem-1 (four alleles) and fem-2 (four alleles), but 18 are alleles of a new gene, fem-3. Additional alleles have been isolated for the fem-2 and fem-3 genes, as well as fem-3 deficiencies. Mutations in fem-3 resemble alleles of fem-1 (previously characterized): putative null alleles result in complete feminization of XX and XO animals, transforming them into fertile females. Severe alleles of fem-2 also cause complete feminization of XX animals at all temperatures, but feminization of fem-2 XO animals is temperature-sensitive: complete at 25 degrees, incomplete at 20 degrees. As with fem-1, severe mutations of fem-2 and fem-3 are wholly epistatic to masculinizing alleles of tra-2 and tra-3, and epistatic to tra-1 masculinizing alleles in the germline, but not in the soma. All three fem genes are essential for male development and appear to have a dual role in promoting spermatogenesis and repressing tra-1 activity. All three fem genes exhibit strong maternal effects; the maternal contribution of fem gene products may be inactivated in XX animals by a posttranscriptional mechanism. Maternal contributions of wild-type fem-3 product are necessary for normal XO male development and XX hermaphrodite (as opposed to female) development.

Alleles↗

Sequenced alleles of the Caenorhabditis elegans sex-determining gene her-1 include a novel class of conditional promoter mutations.

In the control of Caenorhabditis elegans sex determination, the her-1 gene must normally be activated to allow male development of XO animals and deactivated to allow hermaphrodite development of XX animals. The gene is regulated at the transcriptional level and has two nested male-specific transcripts. The larger of these encodes a small, novel, cysteine-rich protein responsible for masculinizing activity. Of the 32 extant mutant alleles, 30 cause partial or complete loss of masculinizing function (lf), while 2 are gain-of-function (gf) alleles resulting in abnormal masculinization of XX animals. We have identified the DNA sequence changes in each of these 32 alleles. Most affect the protein coding functions of the gene, but six are in the promoter region, including the two gf mutations. These two mutations may define a binding site for negative regulators of her-1. Three of the four remaining promoter mutations are single base changes that cause, surprisingly, temperature-sensitive loss of her-1 function. Such conditional promoter mutations have previously not been found among either prokaryotic or eukaryotic mutants analyzed at the molecular level.

Alleles↗

Evidence for multiple promoter elements orchestrating male-specific regulation of the her-1 gene in Caenorhabditis elegans.

The sex-determining gene her-1 is required for male development in Caenorhabditis elegans. In XO males, two her-1 mRNAs, her-1a and her-1b, are transcribed from two separate promoters: P1, located in the 5'-flanking region, and P2, located in the large second intron. In XX hermaphrodites, accumulation of both her-1 transcripts is repressed by the sdc genes, which in turn are negatively regulated by the xol-1 gene. When introduced into a xol-1(y9) background, transgenic arrays, including 3.4 kb of her-1 intron 2 sequence (P2), result in phenotypes that mimic those of sdc(lf) mutants, including suppression of XO lethality and masculinization of both XX and XO animals. The masculinization, but not the suppression of XO lethality, is dependent on endogenous her-1 activity. These effects could therefore result from sequestration (titration) of sdc gene products by sequences in the arrays, causing derepression of her-1 (masculinizing effect) and disruption of the dosage compensation machinery (allowing survival of XO animals). We used these effects as an assay in a deletion analysis of the two her-1 promoter regions to define potential cis-regulatory sites required for the putative titration. Several regions in P2 contributed to these effects. P1 was effective only in combination with certain P2 sequences and only if a particular P1 site previously implicated in her-1 repression was intact. These results suggest that normal repression of transcription from P1 in XX animals may involve cooperative interaction with sequences in the P2 region. In experiments to test for a possible role of the her-1b transcript in regulation of sdc genes, no significant effects could be demonstrated.

Animals↗