Lanthanide probes in biological systems: characterization of luminescence excitation spectra of terbium complexes with proteins

Upon irradiation in the ultraviolet region aromatic chromophores may transfer energy to a nearby Tb³⁺, which in turn emits a green phosphorescence. This paper reports the characterization of the ultraviolet excitation spectra of aromatic chromophores capable of transferring energy to Tb³⁺ by monitoring of the green Tb³⁺ emission in the 540-550 nm region. Results are included for complexes containing phenyl, hydroxyphenyl, indole. and catechol chromophores. Characteristic excitation spectra are presented for the aromatic chromophores occurring as side chains in proteins. Though it is preferable to compare entire excitation spectra, the ratio of intensities at 292 to 276 nm, R, is suggested as a useful diagnostic criterion. Numerical R values are indicative of the following aromatic side chains as the energy donor to Tb³⁺: R <0.2, unionized tyrosine; R = 0.5 to 1.0, tryptophan; and R > 1.8. ionized tyrosine. Tlie phenylalanyl chromophore displays a definitive excitation spectrum at shorter wavelengths. For ovotransferrin R = 0.9 and comparison of the full excitation spectra suggests that it contains comparable contributions from both ionized tyrosine and tryptophan side chains. Some difficulties in obtaining reliable excitation spectra are described. An analysis of inner-filtering of incident light reveals that for an absorbance less than 0.8 the excitation spectrum is broadened and flattened compared to the absorption spectrum. At maximum absorbances greater than 0.8 false maxima may appear to both sides of a real maximum. Two spurious maxima in an excitation spectrum were generated in a Tb³⁺ complex and compared to the correct excitation spectrum of the same complex obtained at lower absorbance.     

Gender differences in anaerobic power tests

The purpose of this study was to determine if the differences in anaerobic power between males and females could be accounted for by differences in body composition, strength, and neuromuscular function. A total of 82 untrained men and 99 women took part in the study. Body composition, somatotype, isometric strength, neuromuscular function were measured, and four anaerobic power tests performed. The men were significantly different from the women on all strength, power, and neuromuscular measurements except reaction time and on all anthropometric and somatotype dimensions except ectomorphy. Strength and anthropometric dimensions were similarly related to anaerobic power values within each sex. Relative fat (%fat) exerted different degrees of influence on sprint and jump performances in each sex. Removing the influence of anthropometric, strength, and neuromuscular differences by analysis of covariance reduced, but did not remove, the significant differences between the sexes. Therefore, factors other than lean body mass, leg strength, and neuromuscular function may be operating in short-term, explosive power performances to account for the differences between the sexes. The task-specific nature of anaerobic power tests and the relatively large influence of anthropometric factors on power production were confirmed.     

An amino-acid-grown maize cell line for use in investigating nitrate assimilation

Summary Studies on uptake and assimilation of nitrate in plants are confounded by differences in cell function associated with anatomical features of roots as well as by problems inherent with growing plants without nitrate. To circumvent these problems, a Zea mays L. embryo cell line was grown in suspension culture using an amino-acid-based medium consisting of a Murashige and Skoog medium in which ammonium and nitrate were replaced by aspartic acid (100 mg/l), glycine (100 mg/l), arginine (150 mg/l), and glutamine (1 g/l). The growth, cellular characteristics, and physical appearance of the amino-acid-grown cells were similar to cells grown in the presence of nitrate. The amino-acid-grown cells exhibited the expected induction pattern and inhibitor sensitivity of nitrate uptake. This cell line should facilitate research on the induction of nitrate uptake and the regulation of nitrate assimilation into proteins.     

The Flora of the Perivaginal Area: The Normal Flora and the Effect of a Deodorant Spray

S ummary . The microbial flora of the thigh adjacent to the vaginal labia and of the mucosal surface of the labia has been examined quantitatively and qualitatively in students from Colleges of Education and a University, and in persons attending a Consultant Gynaecologist for non-suppurative conditions. In the 2 student populations, members of the Micrococcaceae and diphtheroids were the most common organisms but all populations yielded many organisms of gut origin. Differences between the populations may relate to social and hygienic conditions and should make us wary of direct comparisons with other, different populations. The effect of intimate hygiene deodorants containing 0.01% or 0.02% of chlorhexidine was compared with a base spray containing no antibacterial agent. No significant effect of these sprays on the microbial flora could be demonstrated.