A study on identification of bacteria in environmental samples using single-cell Raman spectroscopy: feasibility and reference libraries

We report on our recent efforts towards identifying bacteria in environmental samples by means of Raman spectroscopy. We established a database of Raman spectra from bacteria submitted to various environmental conditions. This dataset was used to verify that Raman typing is possible from measurements performed in non-ideal conditions. Starting from the same dataset, we then varied the phenotype and matrix diversity content included in the reference library used to train the statistical model. The results show that it is possible to obtain models with an extended coverage of spectral variabilities, compared to environment-specific models trained on spectra from a restricted set of conditions. Broad coverage models are desirable for environmental samples since the exact conditions of the bacteria cannot be controlled.     

A novel “Integrated Biomarker Response” calculation based on reference deviation concept

Multi-biomarker approaches are used to assess ecosystem health and identify impacts of environmental stress on organisms. However, exploration of large datasets by environmental managers represents a major challenge for regulatory application of this tool. Several integrative tools were developed to summarize biomarker responses. The aim of the present paper is to update calculation of the “Integrated Biological Response” (IBR) described by Beliaeff and Burgeot (Environ Toxicol Chem 21:1316–1322, 2002) to avoid weaknesses of this integrative tool. In the present paper, a novel index named “Integrated Biological Responses version 2” based on the reference deviation concept is presented. It allows a clear discrimination of sampling sites as for the IBR, but several differences are observed for contaminated sites according to up- and downregulation of biomarker responses. This novel tool could be used to integrate multi-biomarker responses not only in large-scale monitoring but also in upstream/downstream investigations.     

Effect of positional isomerism on the abiotic degradation of pesticides: Case of m- and p-imazamethabenz-methyl

The effect of positional isomerism on chemical and photochemical degradations of the Imazamethabenz-methyl (IMBM), a pesticide of the imidazolinone family, has been studied. IMBM is proposed in the form of a mixture of the two positional isomers: meta and para. The development of an effective HPLC method (resolution factor R=1.3) allows us to follow either the abiotic disappearance of the meta and para IMBM and the formation of their breakdown products. The abiotic degradation studies include the chemical hydrolysis, as well as the direct and the indirect photodecomposition. We used TiO(2), a well-known initiator of hydroxyl radicals, to highlight the role of *OH in the indirect photodegradation. This work confirms the different behaviours of positional isomers in the environment. Indeed the chemical or direct photochemical degradation is faster for the meta isomer than for the para. Whereas, concerning IMBM, there is not any prevalent influence of this type of isomerism on the indirect photochemical degradation. The degradation products were tentatively identified by LC-MS, NMR and IR and a degradation pathway was proposed.     

McKusik-Kaufman syndrome: prenatal diagnosis,genetics and follow up

McKusick-Kaufman syndrome (MKKS) is a rare autosomal recessive genetic disease with classical hexadactyly and hydrocolpos in females and sometimes cardiac abnormality. We report such a case diagnosed just before birth with a favourable outcome. From this case we describe and discuss all the prenatal sonographic signs which are not always present. On the genetic side, the gene has recently been localized together with the mutation responsible for MKKS. The phenotypic relationship between MKKS which has a good prognosis and Bardet-Biedl syndrome (BBS) with a worse prognosis requires great caution before diagnosing MKKS and a long follow-up is necessary to recognize obesity, growth retardation and pigmentary retinitis. Copyright © 2002 John Wiley & Sons, Ltd.