Dietary versatility of Early Pleistocene hominins.

New geochemical data from the Malawi Rift (Chiwondo Beds, Karonga Basin) fill a major spatial gap in our knowledge of hominin adaptations on a continental scale. Oxygen (δO), carbon (δC), and clumped (Δ) isotope data on paleosols, hominins, and selected fauna elucidate an unexpected diversity in the Pleistocene hominin diet in the various habitats of the East African Rift System (EARS). Food sources of early and thriving in relatively cool and wet wooded savanna ecosystems along the western shore of paleolake Malawi contained a large fraction of C plant material.

Slight pressure imbalances can affect accuracy and precision of dual inlet-based clumped isotope analysis.

It is well known that a subtle nonlinearity can occur during clumped isotope analysis of CO2 that - if remaining unaddressed - limits accuracy. The nonlinearity is induced by a negative background on the m/z 47 ion Faraday cup, whose magnitude is correlated with the intensity of the m/z 44 ion beam. The origin of the negative background remains unclear, but is possibly due to secondary electrons.

Clumped isotope analysis of carbonates: comparison of two different acid digestion techniques.

Rationale: The kinetic nature of the phosphoric acid digestion reaction enables clumped isotope analysis of carbonates using gas source isotope ratio mass spectrometry (IRMS). In most laboratories acid digestions are performed at 25°C in sealed vessels or at 90°C in a common acid bath. Here we show that different Δ47 results are obtained depending on the digestion technique employed.

Background effects on Faraday collectors in gas-source mass spectrometry and implications for clumped isotope measurements.

Rationale: The measurement of the abundances of minor isotopologues by mass spectrometry requires correction of subtle non-linearities in the mass spectrometer that cause deviations in the relationship between actual and measured isotope ratios. Here we show that negative backgrounds on the Faraday cups recording the minor ion beams are the cause of the observed non-linearities in the measurement of CO(2) isotopologues, and propose a new correction procedure for clumped isotope measurements.

Methods: We carefully investigated the cause of non-linearity effects in the measurement of the abundance of (13)C(18)O(16)O, a minor isotopologue of CO(2) with m/z 47, on two different mass spectrometers.

Concurrent protective and destructive signaling of JNK2 in neuroblastoma cells.

Investigation of the c-Jun N-terminal kinases (JNKs) has mainly focused on their response to stress and their pro-apoptotic effects. In this regard, JNKs are crucial mediators of chemotherapy-induced killing of tumor cells. Importantly, however, JNKs also have physiological functions in cancer involving cell cycle regulation or oncogenesis.