Chris G. Jones

The mineralized osteocyte: A living fossil

We report here on an enigmatic and biologically mysterious event in which a single cell, the osteocyte, mineralizes in vivo and in this process the cells organelles, cytoskeleton and membrane, are mineralized in a dying state. That the bony lacuna in which the lone osteocyte resides becomes infilled with mineral in vivo is not a new observation and was noted by early microscopists. This study has applied scanning and transmission electron microscopy to modern, archaeological, and fossil bone to investigate the mineral and organic structure and content of this cell. The results from this study revealed that within this mineral lies a visibly identifiable cell, which has an apoptotic-like morphology. The mechanisms by which this cell mineralizes are so intimate chemically that remnant cell organelles, membranes, cytoskeleton, and potentially nucleic bodies are morphologically identifiable. We have further identified mineralized osteocytes surviving in archaeological and fossil mammal bone up to 5 million years BP. The significance of our findings demonstrates that a single cell may itself mineralize in vivo via an unknown set of biochemical events. Importantly, the location and survival of extra cellular and cellular proteins, including nuclear and mitochondrial DNA in bone after death, has been an area of some speculation, and this unique fossil cell provides a preservation locus within human and mammalian bone, which might be fruitfully targeted in future biomolecular studies.

Scanning electron microscopy: preparation and imaging for SEM.

Scanning electron microscopy (SEM) has been almost universally applied for the surface examination and characterization of both natural and man-made objects. Although an invasive technique, developments in electron microscopy over the years has given the microscopist a much clearer choice in how invasive the technique will be. With the advent of low vacuum SEM in the 1970s (The environmental cold stage, 1970) and environmental SEM in the late 1980s (J Microsc 160(pt. 1):9-19, 1989), it is now possible in some circumstances to examine samples without preparation. However, for the examination of biological tissue and cells it is still advisable to chemically fix, dehydrate, and coat samples for SEM imaging and analysis. This chapter aims to provide an overview of SEM as an imaging tool, and a general introduction to some of the methods applied for the preparation of samples.

New genetic and morphological evidence suggests a single hoaxer created ‘Piltdown man’

In 1912, palaeontologist Arthur Smith Woodward and amateur antiquarian and solicitor Charles Dawson announced the discovery of a fossil that supposedly provided a link between apes and humans: Eoanthropus dawsoni (Dawsons dawn man). The publication generated huge interest from scientists and the general public. However, ‘Piltdown mans’ initial celebrity has long been overshadowed by its subsequent infamy as one of the most famous scientific frauds in history. Our re-evaluation of the Piltdown fossils using the latest scientific methods (DNA analyses, high-precision measurements, spectroscopy and virtual anthropology) shows that it is highly likely that a single orang-utan specimen and at least two human specimens were used to create the fake fossils. The modus operandi was found consistent throughout the assemblage (specimens are stained brown, loaded with gravel fragments and restored using filling materials), linking all specimens from the Piltdown I and Piltdown II sites to a single forger—Charles Dawson. Whether Dawson acted alone is uncertain, but his hunger for acclaim may have driven him to risk his reputation and misdirect the course of anthropology for decades. The Piltdown hoax stands as a cautionary tale to scientists not to be led by preconceived ideas, but to use scientific integrity and rigour in the face of novel discoveries.

Scanning electron microscopy techniques for imaging materials from paintings.

ABSTRACT This chapter reviews a range of techniques of scanning electron microscopy (SEM) and its application to the study of paintings and artists materials. The review focuses on imaging the materials (rather than chemical analysis), and its application to the materials used for and from easel paintings. Examples of published experimental studies of cleaning, paint surface defects, bio-deterioration of painting materials from the conservation and paint manufacturers literature are discussed, with reference to sample preparation and imaging conditions. Images of selected artists materials and materials from paintings examined using conventional high vacuum SEM, low vacuum (variable pressure) SEM and ESEM are given to illustrate comparative techniques.

Correction to ‘New genetic and morphological evidence suggests a single hoaxer created ‘Piltdown Man’’

[This corrects the article DOI: 10.1098/rsos.160328.].

Plastic embedding and polishing of bone for reflected light and electron microscopy.

The successful embedding of bone or any sample for reflected light or electron microscopy is crucial to the success of any analysis that might follow. Different materials present different embedding challenges, and here we discuss bone. Embedding is developed often as an adapted in-house protocol, and will vary from one institution to another, and is barely referenced in any detail in scientific papers. This chapter provides the protocol for bone that has proved successful at the Natural History Museum, both for reflected light and particularly for scanning electron microscopic examination.