IsoForensics

Carbon-14 measurements on 231 elephant ivory specimens from 14 large ivory seizures (≥0.5 ton) made between 2002 and 2014 show that most ivory (ca 90%) was derived from animals that had died less than 3 y before ivory was confiscated. This indicates that the assumption of recent elephant death for mortality estimates of African elephants is correct: Very little "old" ivory is included in large ivory shipments from Africa. We found only one specimen of the 231 analyzed to have a lag time longer than 6 y. Patterns of trade differ by regions: East African ivory, based on genetic assignments of geographic origin, has a much higher fraction of "rapid" transit than ivory originating in the Tridom region of Cameroon-Gabon-Congo. Carbon-14 is an important tool in understanding patterns of movement of illegal wildlife products.

Recent forensic applications of stable isotope analysis (SIA) have demonstrated its value as an investigative tool in the identification of unknown decedents. Stable isotope ratios measured in bones, teeth, hair, and nails provide a record of a person’s dietary preferences, travel history, and residence patterns. Stable carbon, nitrogen, and sulfur isotopes of human tissues provide information regarding a decedent’s dietary preferences, which in turn may reflect a person’s geographic region of origin. Additionally, stable oxygen and strontium isotopes in body tissues can be used to provenance human remains, because these isotopes reflect the source of drinking water and local geology, respectively. When combined, a multi-isotope approach provides a powerful geolocation tool for predicting a region of origin or recent travel history for unidentified human remains. In this study, we present on two forensic cases that used SIA to predict the travel history and region of origin of unknown decedents.

Analyses of stable isotope ratios of pollen present within complex matrices may be useful in sample provenance or climate change applications. We developed a method for separating pollen from honey and preparing pollen for hydrogen and oxygen stable isotope ratio analysis. The method combined several treatments: ethanol dilution to separate pollen; hexane washing to remove wax; and acetolysis to digest all but the external layer of pollen granules. There were large isotopic effects associated with treatments but effects were consistent between replicate applications of the method. We used the method to separate pollen from 45 honey samples from across the United States. Pollen δ2H and δ18O isotope values were significantly positively correlated (P < 0.05), but there was little variation in δ2H values explained by δ18O values (r2 = 0.17). Pollen δ2H values were significantly correlated with δ2H values of precipitation predicted for hive locations (P < 0.05, r2 = 0.24), but there was no significant correlation between pollen and precipitation δ18O values (P = 0.34, r2 = 0.03). These results suggest hydrogen and oxygen stable isotope analysis of pollen may not be as useful as analysis of liquid honey or beeswax in investigating provenance.

Understanding links between water consumers and climatological (precipitation) sources is essential for developing strategies to ensure the long‐term sustainability of water supplies. In pursing this understanding a need exists for tools to study and monitor complex human‐hydrological systems that involve high levels of spatial connectivity and supply problems that are regional, rather than local, in nature. Here we report the first national‐level survey of stable isotope ratios in tap water, including spatially and temporally explicit samples from a large number of cities and towns across the contiguous United States. We show that intra‐annual ranges of tap water isotope ratios are relatively small (e.g., &lt;10‰ for δ2H) at most sites. In contrast, spatial variation in tap water isotope ratios is very large, spanning ranges of 163‰ for δ2H and 23.6‰ for δ18O. The spatial distribution of tap water isotope ratios at the national level is similar to that of stable isotope ratios of precipitation. At the regional level, however, pervasive differences between tap water and precipitation isotope ratios can be attributed to hydrological factors in the water source to consumer chain. These patterns highlight the potential for monitoring of tap water isotope ratios to contribute to the study of regional water supply stability and provide warning signals for impending water resource changes. We present the first published maps of predicted tap water isotope ratios for the contiguous United States, which will be useful in guiding future research on human‐hydrological systems and as a tool for applied forensics and traceability studies.

Conantokins are small peptides (17-27 amino acids) found in the venoms of cone snails (Conus sp.) that inhibit the activity of N-methyl-D-aspartate (NMDA) receptors. Unlike most of the peptides characterized from cone snail venom that contain multiple disulfide bridges, conantokins are linear peptides that possess a high degree of alpha-helicity in the presence of divalent cations, and contain gamma-carboxyglutamic acid residues. Four naturally occurring conantokins have been identified and characterized to date, conantokin-G, conantokin-T, conantokin-R, and conantokin-L. The most extensively characterized, conantokin-G, is selective for subtypes of NMDA receptors containing the NR2B subunit. The conantokins have been synthesized and characterized in a number of animal models of human pathologies including pain, convulsive disorders, stroke, and Parkinson's disease. The potential pharmacological selectivity of the conantokins, coupled with their efficacy in preclinical models of disease and favorable safety profiles indicate that these peptides represent both novel probes for NMDA receptor function as well as an important class of compounds for continued investigation as human therapeutics.