Multi-element analysis of soils and sediments by wavelength-dispersive X-ray fluorescence spectrometry

Soil and sediment reference materials were used to calibrate and evaluate an analytical method for the determination of major (Si, Al, Fe, Mg, Ca, Na, K, Mn, P, Ti) and trace elements (As, Ba, Cd, Co, Cr, Cu, Ga, Mo, Mb, Ni, Pb, Rb, S, Sb, Sn, Sr, Th, U, V, Y, Zn, Zr) by sequential wavelength X-ray fluorescence spectrometry. Samples were prepared as pressed pellets and analysis was done with a total measuring time of thirty minutes per sample. Special attention was given to the selection of the thirty reference materials used for calibration of the spectrometer. Another set of eleven RM (reference materials) was analyzed for the evaluation of accuracy. Detection limits for trace elements (1-2 mg kg^-1) are adequate both for geochemical and environmental purposes, except for Cd and Sb. Accuracy for trace elements falls within the expected interval of certified or recommended values in most cases, but for some major elements, like SiO₂, some results showed discrepancies, evidencing difficulties associated with the determination of light elements in complex matrices. But when quality criteria proposed by mapping programs are applied to the results, their requirements are fulfilled. Both instrumental precision, obtained by twelve sample replicate analyses, and analytical precision, considering also sub-sampling and pellet preparation, lie between the limits of the Horwitz expression, except at concentrations close to the detection limits.     

Hierarchical classification by rank and kinship in baboons

Humans routinely classify others according to both their individual attributes, such as social status or wealth, and membership in higher order groups, such as families or castes. They also recognize that people's individual attributes may be influenced and regulated by their group affiliations. It is not known whether such rule-governed, hierarchical classifications are specific to humans or might also occur in nonlinguistic species. Here we show that baboons recognize that a dominance hierarchy can be subdivided into family groups. In playback experiments, baboons respond more strongly to call sequences mimicking dominance rank reversals between families than within families, indicating that they classify others simultaneously according to both individual rank and kinship. The selective pressures imposed by complex societies may therefore have favored cognitive skills that constitute an evolutionary precursor to some components of human cognition.     

Geochemistry of Mercury Along a Soil Profile Compared to Other Elements and to the Parental Rock: Evidence of External Input

The vertical distribution of mercury along a weathering profile derived from a diabase was compared to the main geochemical and mineralogical characteristics of the soil and its parental rock. The sampling site was in a metropolitan area, nearby to an active quarry and relatively close to an industrial park. The samples of a 6-m-deep fresh exposure of the soil profile and also of fresh rock were collected during the dry season. Kaolinite, goethite, hematite, and residual primary minerals were identified in the soil samples. Typically, the concentrations of Hg in the soil are low. Whole samples contained between 1 (rock) and 37 ??g kg^?1 Hg, while the?<?63-??m soil fraction had up to 52 ??g kg^?1 Hg. The higher values of Hg corresponded to the upper layers of A (0?C10 cm) and B (200?C220 cm) soil horizons. Elemental gains and losses calculated against Zr resulted in the following order: Hg>>Pb?>?Zr?>?LREE?>?Nb?>?HREE?>?Al?>?Ti?>?Fe?>?Cr. Total organic carbon in soil samples varied between 0.2 and 5.1 g dm^?3, and correlation with Hg concentrations was moderate. The acid pH (4.2?C5.5) of the soil samples favors the sorption Hg species by predominant secondary phases like goethite and kaolinite. The Hg concentration of the rock is insufficient to explain the large enrichment of Hg along the soil profile, indicating that exogenic Hg, via atmospheric deposition, contributed to the measured Hg concentrations of the soil.     

Transgenic mice with a reduced core body temperature have an increased life span

Reduction of core body temperature has been proposed to contribute to the increased life span and the antiaging effects conferred by calorie restriction (CR). Validation of this hypothesis has been difficult in homeotherms, primarily due to a lack of experimental models. We report that transgenic mice engineered to overexpress the uncoupling protein 2 in hypocretin neurons (Hcrt-UCP2) have elevated hypothalamic temperature. The effects of local temperature elevation on the central thermostat resulted in a 0.3 degrees to 0.5 degrees C reduction of the core body temperature. Fed ad libitum, Hcrt-UCP2 transgenic mice had the same caloric intake as their wild-type littermates but had increased energy efficiency and a greater median life span (12% increase in males; 20% increase in females). Thus, modest, sustained reduction of core body temperature prolonged life span independent of altered diet or CR.     

Ketamine-induced loss of phenotype of fast-spiking interneurons is mediated by NADPH-oxidase

Abuse of the dissociative anesthetic ketamine can lead to a syndrome indistinguishable from schizophrenia. In animals, repetitive exposure to this N-methyl-d-aspartate-receptor antagonist induces the dysfunction of a subset of cortical fast-spiking inhibitory interneurons, with loss of expression of parvalbumin and the gamma-aminobutyric acid-producing enzyme GAD67. We show here that exposure of mice to ketamine induced a persistent increase in brain superoxide due to activation in neurons of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Decreasing superoxide production prevented the effects of ketamine on inhibitory interneurons in the prefrontal cortex. These results suggest that NADPH oxidase may represent a novel target for the treatment of ketamine-induced psychosis.     

Subchronic Exposure to Fenthion Induces Hematological Changes in Liver Tissue of African Catfish Clarias gariepinus

In this study, African Catfish (also known as Sharptooth Catfish) Clarias gariepinus were exposed to sublethal concentrations of fenthion of 2.0, 4.0, and 8.0 mg/L for 21 d and allowed to recover for 7 d to investigate the potential for hematological changes. Whole blood was sampled on days 1, 7, 14, and 21 postexposure and after a 7-d recovery period. During exposure, fenthion caused a reduction in red blood cell counts, hemoglobin concentration, and packed cell volume. There was an increase in white blood cell counts but no significant difference in mean corpuscular hemoglobin concentration, mean corpuscular volume, and mean corpuscular hemoglobin. Both increases and decreases were observed in white blood cell differentials. After the 7-d recovery period, both increases and decreases were observed in the hematological parameters. These results reveal that sublethal concentrations of fenthion can cause hematological alterations in African Catfish and that the substance should be used with caution.

Received October 20, 2015; accepted May 4, 2016 Published online October 20, 2016     

The potential of using 15N natural abundance in changing ammonium-N and nitrate-N pools for studying in situ soil N transformations

Purpose

This study examined the usefulness of ¹⁵N natural abundance (δ¹⁵N) with in situ core incubation to quantify the predominant N transformation processes in a natural suburban forest of subtropical Australia, which was subjected to prescribed burning.

Materials and methods

In situ core incubation for 3 days with 20 ml water, or 160.79 ml of 60 mg L^?1 NO₃^?-N surface application, and in situ core with 160.79 ml water but without incubation were set up in Toohey forest for sampling three times as before (once) and after (twice) a prescribed burning. The δ¹⁵N of NH₄⁺-N and NO₃^?-N in the top 5 cm soil before and after the incubation, and δ¹⁵N of NO₃^?-N in the 5–10 cm soil before incubation were compared with each other to examine the soil N mineralisation, nitrification, denitrification, and nitrate leaching processes.

Results and discussion

The significant decrease in δ¹⁵N of NH₄⁺-N after incubation under 20 ml water treatment was ascribed to soil N mineralisation, and the significant decrease in δ¹⁵N of NH₄⁺-N and significant increase in δ¹⁵N of NO₃^?-N after incubation with elevated water and nitrate inputs were associated with N mineralisation and nitrification, respectively, 2 months after the burning. The 160.79 ml water treatment also triggered nitrification in the baseline soil cores in both samplings after the burning. Water was crucial to stimulate soil N mineralisation and nitrification, but excessive water depleted labile N pools and reduced N mineralisation and nitrification. Burning effects were hard to separate from the seasonal impacts on soil N cycling processes.

Conclusions

The δ¹⁵N in soil mineral N pools was sensitive to indicate soil N mineralisation and nitrification processes. Soil water and labile N were determining factors for N transformations in the soil. It is suggested that δ¹⁵N combined with soil inorganic N concentrations and net N transformation rates could be used to identify primary N transformation processes. More frequent samplings would be needed to differentiate burning impacts from the seasonal impacts on soil N cycling processes.

     

A Bruce effect in wild geladas

Female rodents are known to terminate pregnancies after exposure to unfamiliar males ("Bruce effect"). Although laboratory support abounds, direct evidence for a Bruce effect under natural conditions is lacking. Here, we report a strong Bruce effect in a wild primate, the gelada (Theropithecus gelada). Female geladas terminate 80% of pregnancies in the weeks after a dominant male is replaced. Further, data on interbirth intervals suggest that pregnancy termination offers fitness benefits for females whose offspring would otherwise be susceptible to infanticide. Taken together, data support the hypothesis that the Bruce effect can be an adaptive strategy for females.     

Pyogenic bacterial infections in humans with IRAK-4 deficiency

Members of the Toll-like receptor (TLR) and interleukin-1 receptor (IL-1R) superfamily share an intracytoplasmic Toll-IL-1 receptor (TIR) domain, which mediates recruitment of the interleukin-1 receptor-associated kinase (IRAK) complex via TIR-containing adapter molecules. We describe three unrelated children with inherited IRAK-4 deficiency. Their blood and fibroblast cells did not activate nuclear factor kappaB and mitogen-activated protein kinase (MAPK) and failed to induce downstream cytokines in response to any of the known ligands of TIR-bearing receptors. The otherwise healthy children developed infections caused by pyogenic bacteria. These findings suggest that, in humans, the TIR-IRAK signaling pathway is crucial for protective immunity against specific bacteria but is redundant against most other microorganisms.