Functional dissection of a gene expression oscillator in C. elegans

Gene expression oscillations control diverse biological processes. One such example of gene expression oscillations, are those found for thousands of genes during C. elegans larval development. However, it remains unclear whether and how gene expression oscillations regulate development processes in C. elegans. In this work, I aimed to study the molecular architecture and the system properties of the C. elegans oscillator to provide insight into potential developmental functions and reveal features that are unique, as well as those that are shared among oscillators. Here, performing temporally highly resolved mRNA-sequencing across all larval stages (L1-L4) of C. elegans development, we identified 3,739 genes, whose transcripts revealed high-amplitude oscillations (>2-fold from peak to trough), peaking once every larval stage with stable amplitudes, but variable periods. Oscillations appeared tightly coupled to the molts, but were absent from freshly hatched larvae, developmentally arrested dauer larvae and adults. Quantitative characterization of transitions between oscillatory and stable states of the oscillator showed that the stable states are similar to a particular phase of the oscillator, which coincided with molt exit. Given that these transitions are sensitive to food, we postulate that feeding might impact the state of the oscillator. These features appear rather unique, and hence a better understanding may help to reveal general principles of gene expression oscillators. Our RNAPII ChIP-seq revealed rhythmic occupancy of RNAPII at the promoters of oscillating genes, suggesting that mRNA transcript oscillations arise from rhythmic transcription. Given that oscillations are coupled to the repetitive molts and that the molecular mechanisms that regulate molting are unknown, we aimed to find transcription factors important for molting and oscillations. Hence, we screened 92 transcription factors that oscillate on the mRNA level for their role in molting and identified grh-1, myrf1, blmp-1, bed-3, nhr-23, nhr-25 and ztf-6. We showed that oscillatory activity of GRH-1 is required for timely completion of the molt, to prevent cuticle rupturing, and for oscillatory expression of structural components of the cuticle and ‘ECM regulators’, among others, including grh-1 itself. Hence, we propose GRH-1 as a putative component of the (sub-)oscillator that regulates molting. We showed that loss of BLMP-1 increased the duration of molts, affected cuticle integrity, and changed the oscillatory dynamics of a subset of genes in diverse ways. We postulate that BLMP-1 acts as factor that couples gene expression oscillations, and potentially sub-oscillators or repetitive developmental processes. In conclusion, this work provides insight into the function of the oscillator, and its system properties. Moreover, we identified relevant factors, which we propose as a starting point to unravel the molecular wiring of the C. elegans oscillator and its functional relevance

Sursum Corda

Masterthesis Systematische Theologi

Acute Effects of Decaffeinated Coffee and the Major Coffee Components Chlorogenic Acid and Trigonelline on Glucose Tolerance

OBJECTIVE: Coffee consumption has been associated with lower risk of type 2 diabetes. We evaluated the acute effects of decaffeinated coffee and the major coffee components chlorogenic acid and trigonelline on glucose tolerance. RESEARCH DESIGN AND METHODS: We conducted a randomized crossover trial of the effects of 12 g decaffeinated coffee, 1 g chlorogenic acid, 500 mg trigonelline, and placebo (1 g mannitol) on glucose and insulin concentrations during a 2-h oral glucose tolerance test (OGTT) in 15 overweight men. RESULTS Chlorogenic acid and trigonelline ingestion significantly reduced glucose (−0.7 mmol/l, P = 0.007, and −0.5 mmol/l, P = 0.024, respectively) and insulin (−73 pmol/l, P = 0.038, and −117 pmol/l, P = 0.007) concentrations 15 min following an OGTT compared with placebo. None of the treatments affected insulin or glucose area under the curve values during the OGTT compared with placebo. CONCLUSIONS: Chlorogenic acid and trigonelline reduced early glucose and insulin responses during an OGTT

Rhodococcus equi Infection after Alemtuzumab Therapy for T-cell Prolymphocytic Leukemia

Rhodococcus equi, mainly known from veterinary medicine as a pathogen in domestic animals, can also cause infections in immunocompromised humans, especially in those with defects in cellular immunity. Alemtuzumab, an anti-CD52 monoclonal antibody, causes lymphocytopenia by eliminating CD52-positive cells. We report a patient in whom Rhodococcus equi infection developed after alemtuzumab therapy

Different molecular bases underlie the mitochondrial respiratory activity in the homoeothermic spadices of Symplocarpus renifolius and the transiently thermogenic appendices of Arum maculatum

Symplocarpus renifolius and Arum maculatum are known to produce significant heat during the course of their floral development, but they use different regulatory mechanisms, i.e. homoeothermic compared with transient thermogenesis. To further clarify the molecular basis of species-specific thermogenesis in plants, in the present study we have analysed the native structures and expression patterns of the mitochondrial respiratory components in S. renifolius and A. maculatum. Our comparative analysis using Blue native PAGE combined with nano LC (liquid chromatography)-MS/MS (tandem MS) has revealed that the constituents of the respiratory complexes in both plants were basically similar, but that several mitochondrial components appeared to be differently expressed in their thermogenic organs. Namely, complex II in S. renifolius was detected as a 340 kDa product, suggesting an oligomeric or supramolecular structure in vivo. Moreover, the expression of an external NAD(P)H dehydrogenase was found to be higher in A. maculatum than in S. renifolius, whereas an internal NAD(P)H dehydrogenase was expressed at a similar level in both species. Alternative oxidase was detected as smear-like signals that were elongated on the first dimension with a peak at around 200 kDa in both species. The significance and implication of these data are discussed in terms of thermoregulation in plants

Synchronicity of thermogenic activity, alternative pathway respiratory flux, AOX protein content, and carbohydrates in receptacle tissues of sacred lotus during floral development

The relationships between heat production, alternative oxidase (AOX) pathway flux, AOX protein, and carbohydrates during floral development in Nelumbo nucifera (Gaertn.) were investigated. Three distinct physiological phases were identified: pre-thermogenic, thermogenic, and post-thermogenic. The shift to thermogenic activity was associated with a rapid, 10-fold increase in AOX protein. Similarly, a rapid decrease in AOX protein occurred post-thermogenesis. This synchronicity between AOX protein and thermogenic activity contrasts with other thermogenic plants where AOX protein increases some days prior to heating. AOX protein in thermogenic receptacles was significantly higher than in post-thermogenic and leaf tissues. Stable oxygen isotope measurements confirmed that the increased respiratory flux supporting thermogenesis was largely via the AOX, with little or no contribution from the cytochrome oxidase pathway. During the thermogenic phase, no significant relationship was found between AOX protein content and either heating or AOX flux, suggesting that regulation is likely to be post-translational. Further, no evidence of substrate limitation was found; starch accumulated during the early stages of floral development, peaking in thermogenic receptacles, before declining by 89% in post-thermogenic receptacles. Whilst coarse regulation of AOX flux occurs via protein synthesis, the ability to thermoregulate probably involves precise regulation of AOX protein, most probably by effectors such as α-keto acids.Nicole M. Grant, Rebecca E. Miller, Jennifer R. Watling and Sharon A. Robinso