Phenotypic profiling of antibiotic response signatures in Escherichia coli using Raman spectroscopy.

Identifying the mechanism of action of new potential antibiotics is a necessary but time-consuming and costly process. Phenotypic profiling has been utilized effectively to facilitate the discovery of the mechanism of action and molecular targets of uncharacterized drugs. In this research, Raman spectroscopy was used to profile the phenotypic response of Escherichia coli to applied antibiotics. The use of Raman spectroscopy is advantageous because it is noninvasive, label free, and prone to automation, and its results can be obtained in real time. In this research, E. coli cultures were subjected to three times the MICs of 15 different antibiotics (representing five functional antibiotic classes) with known mechanisms of action for 30 min before being analyzed by Raman spectroscopy (using a 532-nm excitation wavelength). The resulting Raman spectra contained sufficient biochemical information to distinguish between profiles induced by individual antibiotics belonging to the same class. The collected spectral data were used to build a discriminant analysis model that identified the effects of unknown antibiotic compounds on the phenotype of E. coli cultures. Chemometric analysis showed the ability of Raman spectroscopy to predict the functional class of an unknown antibiotic and to identify individual antibiotics that elicit similar phenotypic responses. Results of this research demonstrate the power of Raman spectroscopy as a cellular phenotypic profiling methodology and its potential impact on antibiotic drug development research.

An intron loss in the chloroplast gene rpoC1 supports a monophyletic origin for the subfamily Cactoideae of the Cactaceae.

The deletion of an approximately 700-bp intron in the chloroplast-encoded gene rpoC1 was shown in 21 representative species of the subfamily Cactoideae of the angiosperm family Cactaceae. Members of the subfamilies Pereskioideae and Opuntioideae were found to possess the intron, as did members of the related families Aizoaceae, Basellaceae, Didiereaceae, Phytolaccaceae, and Portulacaceae. These results support a monophyletic origin for the most-speciose subfamily of the cactus family, and represent a first report of the loss of this intron in dicots.

Renal medullary amyloidosis in Dorcas gazelles.

Between January 1976 and September 1987 renal medullary amyloidosis (RMA) was diagnosed in 17 Dorcas gazelles; the necropsy prevalence rate was 17/32 (53%). The most severe amyloid deposits were in the renal medulla; glomeruli were spared. Renal cortical lesions of interstitial fibrosis and tubular atrophy and dilatation significantly correlated with RMA (P less than 0.01) and were considered to be secondary changes. There were varying degrees of lymphoplasmacytic inflammation and tubular cast formation which did not significantly correlate with RMA. Amyloid was confirmed histochemically and by electron microscopy and was identified as AA type by the permanganate method. Progressive renal failure was the cause of death or necessitated euthanasia in 7/17 (41%) gazelles. RMA in Dorcas gazelles does not appear to be familial. A high prevalence of chronic or recurring Actinomyces (Corynebacterium) pyogenes infections may be an important factor.

Deaths from exertional myopathy at the National Zoological Park from 1975 to 1985.

A retrospective study was conducted to determine the incidence of deaths from exertional myopathy (EM) in the hoofstock collection at the National Zoological Park (NZP) from 1975 to 1985. The diagnosis of EM was based on history, clinical signs, clinicopathological findings, gross and microscopic lesions. Only bovids, cervids, and equids were included in the study. Data were derived from the medical and pathological records of the NZP. There were 10 cases of EM during this period, but only seven deaths were directly attributable to EM. Five deaths occurred after immobilization. Two deaths occurred after improper transport, but the anesthetic history was not known in these cases. Pathologic changes consistent with EM were incidental findings in an animal killed by dogs, and in two animals euthanized because of suspected infection with Parelaphostrongylus tenuis. Only cervids and bovids were affected. There was no age or sex predilection for developing EM and deaths occurred throughout the year. Deaths associated with immobilization occurred most often after anesthesia with xylazine and etorphine. These are the drugs used most frequently in bovid and cervid anesthesia at the NZP. The overall incidence of deaths from EM after immobilization was 0.25% for the 10-yr period.

Dental fluorosis in cattle.

Five expressions of dental fluorosis are described in cattle exposed to industrial fluoride pollution: 1. Hypercementosis with tooth ankylosis, cementum necrosis and cyst formation; 2. Delayed eruption of permanent incisor teeth; 3 Necrosis of alveolar bone with recession of bone and gingiva; 4. Oblique eruption of permanent teeth, hypoplasia of teeth with diastemata; and 5. Rapid progression of dental lesions. The five entities are not recognized in the "standard for the classification of dental fluorosis" by the National Academy of Sciences. Since this classification it too limited and superficial, adherence to this standard has left severe cases of fluoride intoxication in cattle undetected in field surveys.