Spatial connectedness imposes local‐ and metapopulation‐level selection on life history through feedbacks on demography

Dispersal evolution impacts the fluxes of individuals and hence, connectivity in metapopulations. Connectivity is therefore decoupled from the structural connectedness of the patches within the spatial network. Because of demographic feedbacks, local selection also drives the evolution of other life history traits. We investigated how different levels of connectedness affect trait evolution in experimental metapopulations of the two-spotted spider mite. We separated local- and metapopulation-level selection and linked trait divergence to population dynamics. With lower connectedness, an increased starvation resistance and delayed dispersal evolved. Reproductive performance evolved locally by transgenerational plasticity or epigenetic processes. Costs of dispersal, but also changes in local densities and temporal fluctuations herein are found to be putative drivers. In addition to dispersal, demographic traits are able to evolve in response to metapopulation connectedness at both the local and metapopulation level by genetic and/or non-genetic inheritance. These trait changes impact the persistence of spatially structured populations

Far-infrared spectra of lateral quantum dot molecules

We study effects of electron-electron interactions and confinement potential on the magneto-optical absorption spectrum in the far-infrared range of lateral quantum dot molecules. We calculate far-infrared (FIR) spectra for three different quantum dot molecule confinement potentials. We use accurate exact diagonalization technique for two interacting electrons and calculate dipole-transitions between two-body levels with perturbation theory. We conclude that the two-electron FIR spectra directly reflect the symmetry of the confinement potential and interactions cause only small shifts in the spectra. These predictions could be tested in experiments with nonparabolic quantum dots by changing the number of confined electrons. We also calculate FIR spectra for up to six noninteracting electrons and observe some additional features in the spectrum.Comment: For better quality Figs download manuscript from http://www.fyslab.hut.fi/~mma/FIR/Helle_qdmfir.ps.g

SUMO Modification: Wrestling with Protein Conformation

SUMO modification of human thymine-DNA glycosylase facilitates the processing of base excision repair substrates by an unusual mechanism: while leaving the catalytic center unaffected, it induces product release by eliciting a conformational change in the enzyme

Avid 18F-FDG Uptake in Idiopathic Tumoral Calcinosis Mimicking Lymph Node Metastasis

Tumoral calcinosis is a benign condition characterized by periarticular calcified lesions that is frequently observed in patients with chronic renal failure. Tumoral calcinosis often presents with subcutaneous masses and joint swelling. We present a case of tumoral calcinosis with dramatically increased 18F-fluoro-2-deoxy-d-glucose (18F-FDG) uptake on positron emission tomography/computed tomography (PET/CT) that mimicked lymphoma or lymph node metastases

18F-FDG PET/CT in a Case of Urothelial Carcinoma in the Urachus Presenting as Colon Cancer

Urachal cancer arises from an embryologic remnant of the urogenital sinus and allantois and accounts for approximately 1% of bladder malignancies. The most encountered histologic subtype is adenocarcinoma. We present a 76-year-old man suspected to have an advanced sigmoid cancer infiltrating nearby organs. A supplemental 18F-FDG PET/CT showed high tracer uptake in a tumorous process coherent with the dome of the bladder wall involving the sigmoid colon. Cystoscopy revealed a normal bladder wall, except for a small edematous area in the anterior bladder. Biopsies from the sigmoid colon and transurethral resection from the bladder confirmed a urothelial carcinoma originating from the urachus

Mechanistic analysis of PCNA poly-ubiquitylation by the ubiquitin protein ligases Rad18 and Rad5

Poly-ubiquitylation is a common post-translational modification that can impart various functions to a target protein. Several distinct mechanisms have been reported for the assembly of poly-ubiquitin chains, involving either stepwise transfer of ubiquitin monomers or attachment of a preformed poly-ubiquitin chain and requiring either a single pair of ubiquitin-conjugating enzyme (E2) and ubiquitin ligase (E3), or alternatively combinations of different E2s and E3s. We have analysed the mechanism of poly-ubiquitylation of the replication clamp PCNA by two cooperating E2–E3 pairs, Rad6–Rad18 and Ubc13–Mms2–Rad5. We find that the two complexes act sequentially and independently in chain initiation and stepwise elongation, respectively. While loading of PCNA onto DNA is essential for recognition by Rad6–Rad18, chain extension by Ubc13–Mms2–Rad5 is only slightly enhanced by loading. Moreover, in contrast to initiation, chain extension is tolerant to variations in the attachment site of the proximal ubiquitin moiety. Our results provide information about a unique conjugation mechanism that appears to be specialised for a regulatable pattern of dual modification