A contribution to the moss flora of Ecuador

An annotated list of new records or otherwise interesting species from Ecuador is presented. The occurrence of rhizoidal tubers is reported for the first time in Anoectangium aestivum, Brachymenium chilense and Bryoerythrophyllum campylocarpum

Gymnostomiella tuberculosa (Renauld & Paris) Arts & P.Sollm. comb. nov.

Gymnostomiella tuberculosa (Renauld & Paris) Arts & P.Sollm. comb. nov. replaces Gymnostomiella burmensis E.B. Bartram

Occurrence of the neotropical moss Dicranella hilariana (Mont.) Mitt. in the Antarctic

Dicranella hilariana (Mont.) Mitt., a pan-neotropical moss species, is reported for the first time from the Antarctic botanical zone. It was found on geothermally heated ground near fumaroles on Visokoi, Candlemas and Bellingshausen Islands in the volcanic archipelago of the South Sandwich Islands. Dicranella recurvata Ochyra, Arts & Lewis-Smith, nom. nud., is reduced to synonymy with D. hilariana. The Antarctic plants of D. hilariana are briefly described and illustrated, including the rhizoidal tubers which have not previously been reported in this species. The global distribution of D. hilariana is briefly reviewed and mapped. It is suggested that the species reached the Antarctic via long-distance dispersal from South America by the prevailing strong westerly winds

Advances in semantic representation for multiscale biosimulation: a case study in merging models

As a case-study of biosimulation model integration, we describe our experiences applying the SemSim methodology to integrate independently-developed, multiscale models of cardiac circulation. In particular, we have integrated the CircAdapt model (written by T. Arts for MATLAB) of an adapting vascular segment with a cardiovascular system model (written by M. Neal for JSim). We report on three results from the model integration experience. First, models should be explicit about simulations that occur on different time scales. Second, data structures and naming conventions used to represent model variables may not translate across simulation languages. Finally, identifying the dependencies among model variables is a non-trivial task. We claim that these challenges will appear whenever researchers attempt to integrate models from others, especially when those models are written in a procedural style (using MATLAB, Fortran, etc.) rather than a declarative format (as supported by languages like SBML, CellML or JSim’s MML)

Control of Whole Heart Geometry by Intramyocardial Mechano-Feedback: A Model Study

Geometry of the heart adapts to mechanical load, imposed by pressures and volumes of the cavities. We regarded preservation of cardiac geometry as a homeostatic control system. The control loop was simulated by a chain of models, starting with geometry of the cardiac walls, sequentially simulating circulation hemodynamics, myofiber stress and strain in the walls, transfer of mechano-sensed signals to structural changes of the myocardium, and finalized by calculation of resulting changes in cardiac wall geometry. Instead of modeling detailed mechano-transductive pathways and their interconnections, we used principles of control theory to find optimal transfer functions, representing the overall biological responses to mechanical signals. As biological responses we regarded tissue mass, extent of contractile myocyte structure and extent of the extra-cellular matrix. Mechano-structural stimulus-response characteristics were considered to be the same for atrial and ventricular tissue. Simulation of adaptation to self-generated hemodynamic load rendered physiologic geometry of all cardiac cavities automatically. Adaptation of geometry to chronic hypertension and volume load appeared also physiologic. Different combinations of mechano-sensors satisfied the condition that control of geometry is stable. Thus, we expect that for various species, evolution may have selected different solutions for mechano-adaptation

Disruption of the basal body protein POC1B results in autosomal-recessive cone-rod dystrophy

Exome sequencing revealed a homozygous missense mutation (c.317C>G [p.Arg106Pro]) in POC1B, encoding POC1 centriolar protein B, in three siblings with autosomal-recessive cone dystrophy or cone-rod dystrophy and compound-heterozygous POC1B mutations (c.199_201del [p.G1n67del] and c.810+1G>T) in an unrelated person with cone-rod dystrophy. Upon overexpression of POC1B in human TERT-immortalized retinal pigment epithelium 1 cells, the encoded wild-type protein localized to the basal body of the primary cilium, whereas this localization was lost for p.Arg106Pro and p.G1n67del variant forms of POC1B. Morpholino-oligonucleotide-induced knockdown of poc1b translation in zebrafish resulted in a dose-dependent small-eye phenotype, impaired optokinetic responses, and decreased length of photoreceptor outer segments. These ocular phenotypes could partially be rescued by wild-type human POC1B mRNA, but not by c.199_201del and c.317C>G mutant human POC1B mRNAs. Yeast two-hybrid screening of a human retinal cDNA library revealed FAM161A as a binary interaction partner of POC1B. This was confirmed in coimmunoprecipitation and colocalization assays, which both showed loss of FAM161A interaction with p.Arg106Pro and p.G1n67del variant forms of POC1B. FAM161A was previously implicated in autosomal-recessive retinitis pigmentosa and shown to be located at the base of the photoreceptor connecting cilium, where it interacts with several other ciliopathy-associated proteins. Altogether, this study demonstrates that POC1B mutations result in a defect of the photoreceptor sensory cilium and thus affect cone and rod photoreceptors