Quantification of Cre-mediated recombination by a novel strategy reveals a stable extra-chromosomal deletion-circle in mice

<p>Abstract</p> <p>Background</p> <p>Inducible conditional knockout animals are widely used to get insight in the function of genes and the pathogenesis of human diseases. These models frequently rely on Cre-mediated recombination of sequences flanked by Lox-P sites. To understand the consequences of gene disruption, it is essential to know the efficiency of the recombination process.</p> <p>Results</p> <p>Here, we describe a modification of the multiplex ligation-dependent probe amplification (MLPA), called extension-MLPA (eMLPA), which enables quantification of relatively small differences in DNA that are a consequence of Cre-mediated recombination. eMLPA, here applied on an inducible <it>Pkd1 </it>conditional deletion mouse model, simultaneously measures both the reduction of the floxed allele and the increase of the deletion allele in a single reaction thereby minimizing any type of experimental variation. Interestingly, with this method we were also able to observe the presence of the excised DNA fragment. This extra-chromosomal deletion-circle was detectable up to 5 months after activation of Cre.</p> <p>Conclusion</p> <p>eMLPA is a novel strategy which easily can be applied to measure the Cre-mediated recombination efficiency in each experimental case with high accuracy. In addition the fate of the deletion-circle can be followed simultaneously.</p

Field dependent anisotropy change in a supramolecular Mn(II)-[3x3] grid

The magnetic anisotropy of a novel Mn(II)-[3x3] grid complex was investigated by means of high-field torque magnetometry. Torque vs. field curves at low temperatures demonstrate a ground state with S > 0 and exhibit a torque step due to a field induced level-crossing at B* \approx 7.5 T, accompanied by an abrupt change of magnetic anisotropy from easy-axis to hard-axis type. These observations are discussed in terms of a spin Hamiltonian formalism.Comment: 4 pages, 4 figures, to be published in Phys. Rev. Let

The Listening Network and Cochlear Implant Benefits in Hearing-Impaired Adults

Older adults with mild or no hearing loss make more errors and expend more effort listening to speech. Cochlear implants (CI) restore hearing to deaf patients but with limited fidelity. We hypothesized that patient-reported hearing and health-related quality of life in CI patients may similarly vary according to age. Speech Spatial Qualities (SSQ) of hearing scale and Health Utilities Index Mark III (HUI) questionnaires were administered to 543 unilaterally implanted adults across Europe, South Africa, and South America. Data were acquired before surgery and at 1, 2, and 3 years post-surgery. Data were analyzed using linear mixed models with visit, age group (18–34, 35–44, 45–54, 55–64, and 65+), and side of implant as main factors and adjusted for other covariates. Tinnitus and dizziness prevalence did not vary with age, but older groups had more preoperative hearing. Preoperatively and postoperatively, SSQ scores were significantly higher (¿0.75–0.82) for those aged <45 compared with those 55+. However, gains in SSQ scores were equivalent across age groups, although postoperative SSQ scores were higher in right-ear implanted subjects. All age groups benefited equally in terms of HUI gain (0.18), with no decrease in scores with age. Overall, younger adults appeared to cope better with a degraded hearing before and after CI, leading to better subjective hearing performance.

New Tetromycin Derivatives with Anti-Trypanosomal and Protease Inhibitory Activities †

Four new tetromycin derivatives, tetromycins 1–4 and a previously known one, tetromycin B (5) were isolated from Streptomyces axinellae Pol001T cultivated from the Mediterranean sponge Axinella polypoides. Structures were assigned using extensive 1D and 2D NMR spectroscopy as well as HRESIMS analysis. The compounds were tested for antiparasitic activities against Leishmania major and Trypanosoma brucei, and for protease inhibition against several cysteine proteases such as falcipain, rhodesain, cathepsin L, cathepsin B, and viral proteases SARS-CoV Mpro, and PLpro. The compounds showed antiparasitic activities against T. brucei and time-dependent inhibition of cathepsin L-like proteases with Ki values in the low micromolar range

The Clinical Spectrum of Missense Mutations of the First Aspartic Acid of cbEGF-like Domains in Fibrillin-1 Including a Recessive Family

Marfan syndrome (MFS) is a dominant disorder with a recognizable phenotype. In most patients with the classical phenotype mutations are found in the fibrillin-1 gene (FBN1) on chromosome 15q21. It is thought that most mutations act in a dominant negative way or through haploinsufficiency. In 9 index cases referred for MFS we detected heterozygous missense mutations in FBN1 predicted to substitute the first aspartic acid of different calcium-binding Epidermal Growth Factor-like (cbEGF) fibrillin-1 domains. A similar mutation was found in homozygous state in 3 cases in a large consanguineous family. Heterozygous carriers of this mutation had no major skeletal, cardiovascular or ophthalmological features of MFS. In the literature 14 other heterozygous missense mutations are described leading to the substitution of the first aspartic acid of a cbEGF domain and resulting in a Marfan phenotype. Our data show that the phenotypic effect of aspartic acid substitutions in the first position of a cbEGF domain can range from asymptomatic to a severe neonatal phenotype. The recessive nature with reduced expression of FBN1 in one of the families suggests a threshold model combined with a mild functional defect of this specific mutation. © 2010 Wiley-Liss, Inc