CD45 tyrosine phosphatase inhibitory components from Aspergillus niger.

Two inhibitors of CD45 tyrosine phosphatase, dihydrocarolic acid (1) and penitricin D (2), were isolated from a fermentation broth of the fungus Aspergillus niger and purified by HSCCC (high speed countercurrent chromatography) followed by HPLC. The structures were determined by NMR. The inhibitory activities of both compounds were specific to tyrosine phosphatases.

Identification of inhibitors of inducible nitric oxide synthase from microbial extracts.

A new member of the angucycline family, vineomycin C (3), together with four known metabolites saquayamycin A1 (1), A-7884 (2), rabelomycin (5) and xanthomegnin (6) were isolated from microbial extracts. The structures were determined by 1D and 2D NMR techniques and chemical degradation. Compounds 1-3 and 5 were isolated from a fermentation of Streptomyces sp., while 6 was isolated from a fungal fermentation extract. All five compounds have shown potent inhibitory activity in the inducible nitric oxide synthase (iNOS) assay.

A hierarchy of sexual harassment.

Undergraduate students (143 males, 100 females) and working women (n = 48) read 18 scenarios depicting a wide range of types of sexual harassment behaviors and indicated whether they personally perceived each type of behavior to be sexual harassment. A hierarchy of harassment was developed on the basis of the subjects' perceptions. Potential differences between the perceptions of working women and female students and between the perceptions of male and female students were also investigated. Although a general consensus emerged regarding the relative perceived severity of the different types of sexual harassment, the percentage of working women who considered the behaviors to be sexual harassment was greater than the percentage of female students who considered them so.

Psychological and demographic correlates of perceptions of sexual harassment.

This study examines the relationship of American students' attitudes toward women, sex, religiosity, self-esteem, and locus of control to variations in perceptions of sexual harassment. The set of two-way interactions of these variables accounted for a substantial portion of the variance in perceptions. A model of perceptions of sexual harassment is introduced suggesting potential theoretical and empirical linkages to be tested in future research.

Perceptions of sexual harassment: a re-examination of gender differences.

There is mixed evidence for gender differences in perceptions of sexual harassment. To help clarify the existence of gender differences, we examined the sexual-harassment perceptions of 409 state government employees in the western United States. Few gender differences were found. We also compared the workers' perceptions to findings from a previous study of students (Terpstra & Baker, 1987). The relative ordering of the incidents' perceived severity was very similar, but workers perceived a number of incidents to be more harassing than did students. Thus, the major differences found were between students and workers, not between genders. Potential theoretical and methodological causes of these findings are discussed.

Caffeine in floral nectar enhances a pollinator's memory of reward.

Plant defense compounds occur in floral nectar, but their ecological role is not well understood. We provide evidence that plant compounds pharmacologically alter pollinator behavior by enhancing their memory of reward. Honeybees rewarded with caffeine, which occurs naturally in nectar of Coffea and Citrus species, were three times as likely to remember a learned floral scent as were honeybees rewarded with sucrose alone. Caffeine potentiated responses of mushroom body neurons involved in olfactory learning and memory by acting as an adenosine receptor antagonist. Caffeine concentrations in nectar did not exceed the bees' bitter taste threshold, implying that pollinators impose selection for nectar that is pharmacologically active but not repellent. By using a drug to enhance memories of reward, plants secure pollinator fidelity and improve reproductive success.

Screening of symbiotic frankiae for host specificity by restriction fragment length polymorphism analysis.

Restriction fragment length polymorphism analysis of numerous Frankia strains, using a nifDH probe, separated the strains into three distinct groups based on hybridization patterns. The groups identified in this study were well correlated with host specificity groups identified in earlier cross-inoculation studies.