Earthworm-produced calcite granules: a new terrestrial palaeothermometer?

In this paper we show for the first time that calcite granules, produced by the earthworm Lumbricus terrestris, and commonly recorded at sites of archaeological interest, accurately reflect temperature and soil water δ18O values. Earthworms were cultivated in an orthogonal combination of two different (granule-free) soils moistened by three types of mineral water and kept at three temperatures (10, 16 and 20 ºC) for an acclimatisation period of three weeks followed by transfer to identical treatments and cultivation for a further four weeks. Earthworm-secreted calcite granules were collected from the second set of soils. δ18O values were determined on individual calcite granules (δ18Oc) and the soil solution (δ18Ow). The δ18Oc values reflect soil solution δ18Ow values and temperature, but are consistently enriched by 1.51 (±0.12) ‰ in comparison to equilibrium in synthetic carbonates. The data fit the equation 1000 ln α = [20.21 ± 0.92] (103 T-1) - [38.58 ± 3.18] (R2 = 0.95; n = 96; p < 0.0005). As the granules are abundant in modern soils, buried soils and archaeological contexts, and can be dated using U-Th disequilibria, the developed palaeotemperature relationship has enormous potential for application to Holocene and Pleistocene time intervals

Micromorphology of Cave Sediments in the Humid Tropics: Niah Cave, Sarawak

This is the first detailed study of the micromorphology of archaeologically important cave sediments in the Great Cave of Niah, in the humid tropics of Sarawak, Borneo. Micromorphology is used to describe the sediments and post-depositional alteration, reconstruct the palaeoenvironments, and refine the environmental history of late Pleistocene deposits associated with the human remains (the so-called Deep Skull dated to ca. 43,000-42,000 B.P.). Micromorphology provides details of the shape, roundedness, arrangement, and chemistry of grains, aggregates, precipitates, and sedimentary structures that make up the cave sediments. The dominant processes in the West Mouth of the Great Cave of Niah are guano sedimentation, fluvial and shallow pond deposition interrupted by desiccation, mass movement, and chemical weathering. Also important is post-depositional alteration by bioturbation, mineral translocation and reprecipitation, and diagenesis. Micromorphology also provides evidence for short periods of soil development, burnt surfaces, and deposition of small fragments of bone within the sediment. Together this information indicates the fine details of the environment occupied by humans, the scale and effects of the mass movement processes that deformed the beds in which the human remains are preserved, and the taphonomic processes that reworked and redistributed archaeological material within this part of the cave. KEYWORDS: micromorphology, cave sediments, human remains, Niah Cave, Borneo, humid tropics

Morphology and dynamics of calcium carbonate granules produced by different earthworm species.

Granules of calcium carbonate produced by earthworms are regularly found in soil profiles, but little is known of their origins and dynamics. Pure cultures of a range of species were therefore set up, using artificial soils, and the granules recovered for examination. Species of Lumbricus, Aporrectodea, Octolasion and Allolobophora all produced granules larger than 0.125mm, but Eisenia hortensis did not. For comparison, two compost-dwelling Eisenia species were also cultured. These yielded no granules at all, suggesting that the genus as a whole does not produce granules, consistent with its lack of calciferous sacs. Granules recovered from the other 7 species have a variety of sizes and morphologies, ranging from single calcite crystals to aggregations up to 2.5mm in diameter. SEM photographs of the granules and data on granule concentrations in relation to depth are presente

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field