A novel ABCC8 mutation illustrates the variability of the diabetes phenotypes associated with a single mutation.

AIM: ATP-sensitive potassium channels are important regulators of insulin secretion. They consist of four sulphonylurea receptor (encoded by ABCC8) and four inwardly rectifying protein (encoded by KCNJ11) subunits. Activating ABCC8 mutations lead to decreased insulin secretion and to diabetes. Wide phenotype variability is associated with single ABCC8 mutations, ranging from transient or permanent neonatal diabetes (ND) with or without developmental delay (DEND syndrome) to very mild phenotypes. This report describes the case of a Caucasian infant diagnosed with ND at the age of 2 months due to a novel ABCC8 missense mutation. METHODS: ABCC8 was analyzed by sequence analysis. The mutation was present in the patient and her family and was found to be associated with phenotypes ranging from ND to asymptomatic impaired fasting glucose (IFG). RESULTS: A novel His863Tyr ABCC8 mutation was identified in a 2-month-old girl diagnosed with ND. After an initial insulin treatment, treatment with glibenclamide was initiated and the treatment with insulin discontinued. The same mutation was found in her father, who had been fortuitously diagnosed with diabetes and had an HbA(1c) level of 9% (74.8 mmol/mol). The patient's brother and mother both had normal fasting glucose, and were not found to be carriers of the mutation. However, the same mutation was found in her grandmother, who had been asymptomatic and discovered IFG (6.9 mmol/L) with an HbA(1c) of 6.8% (50.8 mmol/mol). CONCLUSION: This case describes a novel ABCC8 mutation and offers a further illustration of the highly variable phenotypes associated with an identical mutation present across three generations.

Quantification of bacterial subgroups in soil: comparison of DNA extracted directly from soil or from cells previously released by density gradient centrifugation.

All molecular analyses of soil bacterial diversity are based on the extraction of a representative fraction of cellular DNA. Methods of DNA extraction for this purpose are divided into two categories: those in which cells are lysed within the soil (direct extraction) and those in which cells are first removed from soil (cell extraction) and then lysed. The purpose of this study was to compare a method of direct extraction with a method in which cells were first separated from the soil matrix by Nycodenz gradient centrifugation in order to evaluate the effect of these different approaches on the analysis of the spectrum of diversity in a microbial community. We used a method based on polymerase chain reaction (PCR) amplification of a 16S rRNA gene fragment, followed by hybridization of the amplified fragments to a set of specific probes to assess the phylogenetic diversity of our samples. Control parameters, such as the relationship between amount of DNA template and amount of PCR product and the influence of competing DNA on PCR amplification, were first examined. Comparison between extraction methods showed that less DNA was extracted when cells were first separated from the soil matrix (0.4 microg g(-1) dry weight soil versus 38-93 microg g(-1) obtained by in situ lysis methods). However, with the exception of the gamma-subclass of Proteobacteria, there was no significant difference in the spectrum of diversity resulting from the two extraction strategies.

The cold shock response of the psychrotrophic bacterium Pseudomonas fragi involves four low-molecular-mass nucleic acid-binding proteins.

The psychrotrophic bacterium Pseudomonas fragi was subjected to cold shocks from 30 or 20 to 5 degrees C. The downshifts were followed by a lag phase before growth resumed at a characteristic 5 degrees C growth rate. The analysis of protein patterns by two-dimentional gel electrophoresis revealed overexpression of 25 or 17 proteins and underexpression of 12 proteins following the 30- or 20-to-5 degrees C shift, respectively. The two downshifts shared similar variations of synthesis of 20 proteins. The kinetic analysis distinguished the induced proteins into cold shock proteins (Csps), which were rapidly but transiently overexpressed, and cold acclimation proteins (Caps), which were more or less rapidly induced but still overexpressed several hours after the downshifts. Among the cold-induced proteins, four low-molecular-mass proteins, two of them previously characterized as Caps (CapA and CapB), and heat acclimation proteins (Haps) as well as heat shock proteins (Hsps) for the two others (TapA and TapB) displayed higher levels of induction. Partial amino acid sequences, obtained by microsequencing, were used to design primers to amplify by PCR the four genes and then determine their nucleotide sequences. A BamHI-EcoRI restriction fragment of 1.9 kb, containing the complete coding sequence for capB, was cloned and sequenced. The four peptides belong to the family of small nucleic acid-binding proteins as CspA, the major Escherichia coli Csp. They are likely to play a major role in the adaptative response of P. fragi to environmental temperature changes.