Chromosomal localization of a tandemly repeated DNA sequence in Trifolium repens L

INTRoDUCTIoNlYho1iumrePensL,whiteclover,isaneconomicallyimportantplantspeciesintemperatepastures.Asbrieflyreportedby[1],ithas16pairsofchromosomes(2n=32).Asyet,nodetailedcytologicalexaminationofthisspecies,suchasC-banding,hasbeenrep0rted.Inthelastdecade,thetechnique0fC-bandinghasbeenusedt0examinehighlyrepeatedsequencesinplantchrom0s0mesandhasprovidedausefultoolf0rtheanalysis0fcyt0geneticstructureincr0pplants[2-71.Inplants,thechr0m0s0mall0calizationofhighlyrepeatedDNAsequencesbyinsituhybr…     

Masculinized otoacoustic emissions in female spotted hyenas (Crocuta crocuta)

In humans and rhesus monkeys, click-evoked otoacoustic emissions (CEOAEs) are stronger in females than in males, and there is considerable circumstantial evidence that this sex difference is attributable to the greater exposure to androgens prenatally in males. Because female spotted hyenas are highly androgenized beginning early in prenatal development, we expected an absence of sexual dimorphism in the CEOAEs of this species. The CEOAEs obtained from 9 male and 7 female spotted hyenas confirmed that expectation. The implication is that the marked androgenization to which female spotted hyenas are exposed masculinizes the cochlear mechanism responsible for CEOAEs. The CEOAEs measured in 3 male and 3 female hyenas that had been treated with anti-androgenic agents during prenatal development were stronger than the CEOAEs of the untreated animals, in accord with the implied inverse relationship between prenatal androgen exposure and the strength of the cochlear mechanisms producing CEOAEs. The CEOAEs of three ovariectomized females and two castrated males were essentially the same as those for the untreated females and males, suggesting that there is little or no activational effect of hormones on CEOAE strength in spotted hyenas. Distortion product OAEs (DPOAEs) also were measured. Those sex differences also were generally small (as they are in humans), and the effects of the anti-androgen agents were inconsistent. Thus, prenatal androgen exposure apparently does affect OAEs, but the effects appear to be greater for the reflection-based cochlear mechanism that underlies CEOAEs than for the nonlinear cochlear mechanism underlying DPOAEs.     

Retinal pigment epithelium pigment granules stimulate the photo-oxidation of unsaturated fatty acids

The cellular pigments of the retinal pigment epithelium (RPE) have been shown to catalyze free radical activity, especially when illuminated with visible or ultraviolet light. This activity is sufficient to cause photooxidation of several major cellular components. The present investigation determined the relative ability of melanin, lipofuscin, and melanolipofuscin granules isolated from human and bovine eyes to oxidize polyunsaturated fatty acids, specifically linoleic and docosahexaenoic acids. The dark reactivity as well as the light-stimulated reactions were determined. The production of hydroperoxide derivatives of the linoleic and docosahexaenoic acids were determined by NADPH oxidation coupled to the activity of glutathione peroxidase, and also by production of thiobarbituric acid reactive substances. All RPE pigment granules stimulated fatty acid oxidation when irradiated with short wavelength (< 550 nm) visible light, with the melanosomes exhibiting the greatest light-induced activity. Only lipofuscin granules, however, caused peroxidation of fatty acids in the dark. These findings provide additional support for the role of RPE pigments in "blue light toxicity" as well as indicating that accumulation of lipofuscin may contribute to increased photooxidation in the aging RPE.     

A comparison of ALPHAScreen, TR-FRET, and TRF as assay methods for FXR nuclear receptors

New developments in detection technologies are providing a variety of biomolecular screening strategies from which to choose. Consequently, we performed a detailed analysis of both separation-based and non-separation-based formats for screening nuclear receptor ligands. In this study, time-resolved fluorescence resonance energy transfer (TR-FRET), ALPHAScreen, and time-resolved fluorescence (TRF) assays were optimized and compared with respect to sensitivity, reproducibility, and miniaturization capability. The results showed that the ALPHAScreen system had the best sensitivity and dynamic range. The TRF assay was more time consuming because of the number of wash steps necessary. The TR-FRET assay had less interwell variation, most likely because of ratiometric measurement. Both the ALPHAScreen and the TR-FRET assays were miniaturized to 8-microl volumes. Of the photomultiplier tube-based readers, the ALPHAScreen reader (ALPHAQuest) presented the advantage of faster reading times through simultaneous reading with four photomultiplier tubes.     

Determination of voriconazole in aqueous humor by liquid chromatography-electrospray ionization-mass spectrometry

A novel method based on liquid chromatography-mass spectrometry with electrospray ionization (LC-MS) has been developed for analysis of voriconazole in aqueous humor. The separation was achieved on a reversed-phase C(18) column eluted by 70% acetonitrile-30% water-0.01% TFA. The correlation between the concentration of voriconazole to peak area was linear (r(2)=0.9990) between 0.04 and 60 ng, with a coefficient of variance of less than 3%. Limit of quantitation (LOQ) was estimated to be 5 ng/ml voriconazole with an injection volume of 2 microl of aqueous humor. Both intra-day and inter-day imprecision were less than 3% over the whole analytical range. Parallel analyses of voriconazole samples by LC-MS and by high-performance liquid chromatography (HPLC)-UV showed that the two methods were highly correlated (r(2)=0.9985). LC-MS was used to the determine voriconazole levels achieved in the aqueous humor of the rabbit eye, following topical application of 5 or 10 microg voriconazole in the form of eyedrops for 11 days b.i.d. The lower dosage produced an aqueous humor concentration of 7.29+/-5.84 microg/ml, while the higher dosage produced a concentration of 14.56+/-12.90 microg/ml.     

Induced mutagenesis in dam- mutants of Escherichia coli: a role for 6-methyladenine residues in mutation avoidance.

Summary E. coli strains carrying the dam-3 and dam-4 mutations resulting in reduced levels of 6-methyladenine in the DNA have been found to be more sensitive to base analogue mutagenesis than dam ⁺ strains. Mutagenesis by EMS was also found to be enhanced in dam ^– strains. Dam ^– mutants however were not found to be hypermutable by UV light. It is concluded that the dam ^– strains are deficient in the correct repair of mispairing lesions. The data are consistent with the hypothesis that 6-methyladenine residues in the DNA are involved in strand discrimination during mismatch correction.     

The surgical management of Melkersson-Rosenthal syndrome.

A triad of facial palsy, orofacial edema, and furrowed tongue constitutes an uncommon condition known as Melkersson-Rosenthal syndrome (MRS). We report on 14 patients with Melkersson-Rosenthal syndrome. Two patients had facial palsy, 12 had orofacial edema, and 1 patient had a furrowed tongue. Nine patients were treated medically. Intralesional steroid therapy had a 75 percent recurrence rate. Systemic steroid therapy resulted in remission in two of three patients. Surgical excision and reconstruction were carried out in five patients with chronic lip or eyelid edema. This provided relief in all cases. The etiology, clinical presentation, and histologic features are discussed. Three illustrative cases are presented. An algorithm is provided that guides the surgeon with regard to both the medical and surgical treatment of the patient with Melkersson-Rosenthal syndrome.