HACD1, a regulator of membrane composition and fluidity, promotes myoblast fusion and skeletal muscle growth

The reduced diameter of skeletal myofibres is a hallmark of several congenital myopathies, yet the underlying cellular and molecular mechanisms remain elusive. In this study, we investigate the role of HACD1/PTPLA, which is involved in the elongation of the very long chain fatty acids, in muscle fibre formation. In humans and dogs, HACD1 deficiency leads to a congenital myopathy with fibre size disproportion associated with a generalized muscle weakness. Through analysis of HACD1-deficient Labradors, Hacd1-knockout mice, and Hacd1-deficient myoblasts, we provide evidence that HACD1 promotes myoblast fusion during muscle development and regeneration. We further demonstrate that in normal differentiating myoblasts, expression of the catalytically active HACD1 isoform, which is encoded by a muscle-enriched splice variant, yields decreased lysophosphatidylcholine content, a potent inhibitor of myoblast fusion, and increased concentrations of ≥C18 and monounsaturated fatty acids of phospholipids. These lipid modifications correlate with a reduction in plasma membrane rigidity. In conclusion, we propose that fusion impairment constitutes a novel, non-exclusive pathological mechanism operating in congenital myopathies and reveal that HACD1 is a key regulator of a lipid-dependent muscle fibre growth mechanism

Liquefaction hazard of the Groningen region of the Netherlands due to induced seismicity

The operator of the Groningen gas field is leading an effort to quantify the seismic hazard and riskof the region due to induced earthquakes, includingoverseeing one of the most comprehensive liquefaction hazard studies performedgloballyto date. Due tothe unique characteristics of the seismic hazard and the geologic deposits in Groningen, efforts first focused on developing relationships for a Groningen-specific liquefaction triggering model. The liquefaction hazard was then assessedusing a Monte Carlo method, wherein a range of credibleevent scenarios were considered in computingliquefaction damage-potentialhazard curves. Thiseffort entailed the use of a regional stochastic seismic source model,ground motion prediction equation,site response model,and geologic model that were developed as part of the broader regional seismic hazardassessment.“No-to-Minor Surficial Liquefaction Manifestations”arepredicted for mostsites across the study areafor a 75-year return period. The only sites where “Moderate Surficial Liquefaction Manifestations” are predicted are in the town of Zandeweer, with only some of the sites in the townbeing predicted to experience this severityof liquefactionfor thisreturn period

Calibration of the oxygen and clumped isotope thermometers for (proto-)dolomite based on synthetic and natural carbonates

Dolomite is a very common carbonate mineral in ancient sediments, but is rarely found in modern environments. Because of the difficulties in precipitating dolomite in the laboratory at low temperatures, the controls on its formation are still debated after more than two centuries of research. Two important parameters to constrain the environment of dolomitization are the temperature of formation and the oxygen isotope composition of the fluid from which it precipitated. Carbonate clumped isotopes (expressed with the parameter Δ47) are increasingly becoming the method of choice to obtain this information. However, whereas many clumped isotope studies treated dolomites the same way as calcite, some recent studies observed a different phosphoric acid fractionation for Δ47 during acid digestion of dolomite compared to calcite. This causes additional uncertainties in the Δ47 temperature estimates for dolomites analyzed in different laboratories using different acid digestion temperatures. To tackle this problem we present here a (proto-)dolomite-specific Δ47-temperature calibration from 25 to 1100 °C for an acid reaction temperature of 70 °C and anchored to widely available calcite standards. For the temperature range 25 to 220 °C we obtain a linear Δ47-T relationship based on 289 individual measurements with R2 of 0.864: [Formula presented] Tin Kelvin When including two isotopically scrambled dolomites at 1100 °C, the best fit is obtained with a third order polynomial temperature relationship (R2 = 0.924): [Formula presented]. Applying a calcite Δ47-T relationship produced under identical laboratory conditions results in 3 to 16 °C colder calculated formation temperatures for dolomites (with formation temperature from 0 to 100 °C) than using the (proto-)dolomite specific calibration presented here. For the synthetic samples formed between 70 and 220 °C we also determined the temperature dependence of the oxygen isotope fractionation relative to the water. Based on the similarity between our results and two other recent studies (Vasconcelos et al., 2005 and Horita, 2014) we propose that a combination of the three datasets represents the most robust calibration for (proto-)dolomite formed in a wide temperature range from 25 to 350 °C. 103αCaMg−carbonates−Water=2.9923±0.0557×[Formula presented]−2.3592±0.4116 Because of the uncertainties in the phosphoric acid oxygen and clumped isotope fractionation for (proto-)dolomite, we promote the use of three samples that are available in large amounts as possible inter-laboratory reference material for oxygen and clumped isotope measurements. A sample of the middle Triassic San Salvatore dolomite from southern Switzerland, the NIST SRM 88b dolomite standard already reported in other Δ47 studies and a lacustrine Pliocene dolomite from La Roda (Spain). This study demonstrates the necessity to apply (proto-)dolomite specific Δ47-T relationships for accurate temperature estimates of dolomite formation, ideally done at identical acid digestion temperatures to avoid additional uncertainties introduced by acid digestion temperature corrections. In addition, the simultaneous analyses of dolomite reference material will enable a much better comparison of published dolomite clumped and oxygen isotope data amongst different laboratories

New records of predation of Harpactorinae (Hemiptera: Reduviidae) over Euglossini and Xylocopini bees (Hymenoptera: Apidae) in Brazil.

Abstract. The predatory activities of Apiomerus duckei Costa Lima, Seabra & Hathaway, 1951, Apiomerus pilipes (Fabricius, 1787) and Apiomerus luctuosus Costa Lima, Seabra & Hathaway, 1951 (Hemiptera: Reduviidae: Harpactorinae: Apiomerini) on orchid bees (Hymenoptera: Apidae: Apinae: Euglossini) in odoriferous traps in the influence area of Santo Antônio Hydroelectric Power Plant, Rondônia State, Brazil, and of Cosmoclopius annulosus Stål, 1872 (Hemiptera: Reduviidae: Harpactorinae: Harpactorini) on the bee Ceratina rupestris Holmberg, 1884 (Hymenoptera: Apidae: Apinae: Xylocopini: Ceratinina), in an experimental area cultivated with canola in Passo Fundo, Rio Grande do Sul State, Brazil, are recorded by the first time. Resumen. Se registran por primera vez las actividades depredadoras de Apiomerus duckei Costa Lima, Seabra y Hathaway, 1951, Apiomerus pilipes (Fabricius, 1787) y Apiomerus luctuosus Costa Lima, Seabra y Hathaway, 1951 (Hemiptera: Reduviidae: Harpactorinae: Apiomerini) sobre abejas orquídeas (Hymenoptera: Apidae: Apinae: Euglossini) en trampas odoríferas ubicadas en el área de influencia de la Central Hidroeléctrica Santo Antônio (HEP), Estado de Rondônia, Brasil, y de Cosmoclopius annulosus Stål, 1872 (Hemiptera: Reduviidae: Harpactorinae: Harpactorini) sobre la abeja Ceratina rupestris Holmberg, 1884 (Hymenoptera: Apidae: Apinae: Xylocopini: Ceratinina), en un área experimental cultivada con canola en Passo Fundo, Rio Grande do Sul State, Brasil