Mice with humanized livers reveal the role of hepatocyte clocks in rhythmic behavior.

The synchronization of circadian clock depends on a central pacemaker located in the suprachiasmatic nuclei. However, the potential feedback of peripheral signals on the central clock remains poorly characterized. To explore whether peripheral organ circadian clocks may affect the central pacemaker, we used a chimeric model in which mouse hepatocytes were replaced by human hepatocytes. Liver humanization led to reprogrammed diurnal gene expression and advanced the phase of the liver circadian clock that extended to muscle and the entire rhythmic physiology. Similar to clock-deficient mice, liver-humanized mice shifted their rhythmic physiology more rapidly to the light phase under day feeding. Our results indicate that hepatocyte clocks can affect the central pacemaker and offer potential perspectives to apprehend pathologies associated with altered circadian physiology.

Functional characterization of a three-component regulatory system involved in quorum sensing-based regulation of peptide antibiotic production in Carnobacterium maltaromaticum.

BACKGROUND: Quorum sensing is a form of cell-to-cell communication that allows bacteria to control a wide range of physiological processes in a population density-dependent manner. Production of peptide antibiotics is one of the processes regulated by quorum sensing in several species of Gram-positive bacteria, including strains of Carnobacterium maltaromaticum. This bacterium and its peptide antibiotics are of interest due to their potential applications in food preservation. The molecular bases of the quorum sensing phenomenon controlling peptide antibiotic production in C. maltaromaticum remain poorly understood. The present study was aimed at gaining a deeper insight into the molecular mechanism involved in quorum sensing-mediated regulation of peptide antibiotic (bacteriocin) production by C. maltaromaticum. We report the functional analyses of the CS (autoinducer)-CbnK (histidine protein kinase)-CbnR (response regulator) three-component regulatory system and the three regulated promoters involved in peptide antibiotic production in C. maltaromaticum LV17B. RESULTS: CS-CbnK-CbnR system-dependent activation of carnobacterial promoters was demonstrated in both homologous and heterologous hosts using a two-plasmid system with a beta-glucuronidase (GusA) reporter read-out. The results of our analyses support a model in which the CbnK-CbnR two-component signal transduction system is necessary and sufficient to transduce the signal of the peptide autoinducer CS into the activation of the promoters that drive the expression of the genes required for production of the carnobacterial peptide antibiotics and the immunity proteins that protect the producer bacterium. CONCLUSIONS: The CS-CbnK-CbnR triad forms a three-component regulatory system by which production of peptide antibiotics by C. maltaromaticum LV17B is controlled in a population density-dependent (or cell proximity-dependent) manner. This regulatory mechanism would permit the bacterial population to synchronize the production of peptide antibiotics and immunity proteins. Such a population-wide action would afford a substantial peptide antibiotic production burst that could increase the ability of the bacterium to inhibit susceptible bacterial competitors. Finally, our CS-CbnK-CbnR-based two-plasmid expression system represents a suitable genetic tool for undertaking structure-function relationship analyses to map the amino acid residues in the components of the CS-CbnK-CbnR system that are required for biological activity. This plasmid system also has potential as a starting point for developing alternative vectors for controlled gene expression in C. maltaromaticum, Lactococcus lactis, and related lactic acid bacteria.

Evaluation of BRCA1/2 mutational status among German and Austrian women with triple-negative breast cancer.

PURPOSE: Testing for BRCA1 and BRCA2 mutations in breast cancer patients is used to identify the risk of second primary cancers and the risk of cancer in the patients' family. Women with triple-negative breast cancer (TNBC) are thought to be more likely to be BRCA1/2 mutation carriers, but most national guidelines for genetic testing, including those used in Germany and Austria, do not consider receptor triple negativity. METHODS: We determined the prevalence of BRCA1 and BRCA2 mutations within a cohort of 100 unselected TNBC cases, including patients from Germany and Austria to identify those BRCA-positive patients with a masked family history and who would have been missed due to respective current national guidelines. Double-stranded Sanger sequencing of all exons of BRCA1 and BRCA2, respectively, was performed. RESULTS: We identified a total of 13 deleterious mutations in BRCA1 and a total of four deleterious mutations in BRCA2. The total rate of deleterious BRCA1/2 mutation carriers was 21 % in our cohort. Six novel mutations, including two deleterious mutations, have been identified, which have not been described in public mutation databases so far. According to current German and Austrian national guidelines for genetic testing, 38.1 and 52.4 %, respectively, of BRCA1/2 mutation carriers would have been overlooked. CONCLUSIONS: We conclude that the prevalence of BRCA1 and BRCA2 mutations is high in TNBC patients and that BRCA1/2 mutations are not restricted to young women or patients with a positive family history. Receptor triple negativity should therefore be considered in BRCA1/2 genetic testing guidelines.

The tale of a resting gland: transcriptome of a replete venom gland from the scorpion Hottentotta judaicus.

cDNA libraries are increasingly being used for high-throughput interrogation of animal venomes. Most previous studies have focused on discovery of new venom toxins, whereas the dynamics of toxin transcription and associated cellular processes have received much less attention. Here we provide, for the first time, an analysis of a transcriptome from the venom gland of a scorpion (Hottentotta judaicus) that is not actively engaged in regenerating its venom. We demonstrate a low abundance of toxin-encoding transcripts coupled with a previously unobserved proliferation of protease sequences. Additionally, we identified several low abundance, toxin-like sequences that may represent decommissioned toxins that are unlikely to be translated. These sequences are not evenly distributed across all toxin families, but rather appear more frequently in transcripts related to α-toxins and ß-toxins that are known to target voltage-gated sodium channels. The transcriptomic profile of the replete venom gland is very different to that obtained previously from scorpion venom glands actively engaged in venom regeneration, and it highlights our lack of knowledge as to how the dynamics of transcription changes as the gland progresses from venom regeneration to a "resting" state. This study therefore provides an important foundation for future studies into the dynamics of transcription in the venom glands of scorpions and other venomous animals.