Effect of X-ray irradiation on ancient DNA in sub-fossil bones – Guidelines for safe X-ray imaging

Immel, Alexander; Cabec, Adeline Le; Bonazzi, Marion; Herbig, Alexander; Temming, Heiko; Schuenemann, Verena J.; Bos, Kirsten I.; Langbein, Frauke; Harvati, Katerina; Bridault, Anne; Pion, Gilbert; Julien, Marie-Anne; Krotova, Oleksandra; Conard, Nicholas J.; Münzel, Susanne C.; Drucker, Dorothée G.; Viola, Bence; Hublin, Jean‐Jacques; Tafforeau, Paul; Krause, Johannes

doi:10.1038/srep32969

Cited by 85 publications

(49 citation statements)

References 44 publications

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“…The samples were restored to their original color by illumination with low energy UV light (black light neon tubes) for a few hours [ 60 ]. Recent refinements subsequent to the acquisition of these data have reduced the radiation dose to avoid this darkening effect [ 61 ]. Volumes were reconstructed using filtered-backprojection algorithm (PyHST software, ESRF) in edge detection mode.…”

Section: Methodsmentioning

confidence: 99%

Disentangling isolated dental remains of Asian Pleistocene hominins and pongines

et al. 2018

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Scholars have debated the taxonomic identity of isolated primate teeth from the Asian Pleistocene for over a century, which is complicated by morphological and metric convergence between orangutan (Pongo) and hominin (Homo) molariform teeth. Like Homo erectus, Pongo once showed considerable dental variation and a wide distribution throughout mainland and insular Asia. In order to clarify the utility of isolated dental remains to document the presence of hominins during Asian prehistory, we examined enamel thickness, enamel-dentine junction shape, and crown development in 33 molars from G. H. R. von Koenigswald's Chinese Apothecary collection (11 Sinanthropus officinalis [= Homo erectus], 21 “Hemanthropus peii,” and 1 “Hemanthropus peii” or Pongo) and 7 molars from Sangiran dome (either Homo erectus or Pongo). All fossil teeth were imaged with non-destructive conventional and/or synchrotron micro-computed tomography. These were compared to H. erectus teeth from Zhoukoudian, Sangiran and Trinil, and a large comparative sample of fossil Pongo, recent Pongo, and recent human teeth. We find that Homo and Pongo molars overlap substantially in relative enamel thickness; molar enamel-dentine junction shape is more distinctive, with Pongo showing relatively shorter dentine horns and wider crowns than Homo. Long-period line periodicity values are significantly greater in Pongo than in H. erectus, leading to longer crown formation times in the former. Most of the sample originally assigned to S. officinalis and H. erectus shows greater affinity to Pongo than to the hominin comparative sample. Moreover, enamel thickness, enamel-dentine junction shape, and a long-period line periodicity value in the “Hemanthropus peii” sample are indistinguishable from fossil Pongo. These results underscore the need for additional recovery and study of associated dentitions prior to erecting new taxa from isolated teeth.

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Section: Methodsmentioning

confidence: 99%

Disentangling isolated dental remains of Asian Pleistocene hominins and pongines

et al. 2018

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“…The dose increases at about the square power of the increase of resolution. 18 Thus, another reason to advocate the application of lower energy scanning over higher energy scanning for breccia triage is that the potential and ability to access ancient DNA from fossil specimens still needs research and elucidation.…”

Section: Discussionmentioning

confidence: 99%

“…17 Recent work has shown that radiation of fossils may have a detrimental effect on ancient DNA when the total surface dose exceeds 200 Gray, so these researchers recommended using as low a dose as possible when scanning fossils as well as using resolution no higher than necessary to achieve the desired outcome. 18 The value of 200 Gray is far higher than any dose from a XCT or µXCT scan (8000 times higher than the highest dose for a medical CT scan). 18 …”

Section: Research Articlementioning

confidence: 97%

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Finding fossils in Malapa breccia – medical CT scanning or micro-CT scanning?

Smilg¹

2017

S. Afr. J. Sci.

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Computed tomography (CT) imaging of fossils has revolutionised the field of palaeontology, allowing researchers to gain a better understanding of fossil anatomy, preservation and conservation. Micro focus X-ray computed tomography (μXCT) has been far more extensively used for these purposes than medical CT (XCT) – mostly because of the exquisite detail that the μXCT scanning modality, using slices of micron thicknesses, can produce. High energy X-rays can potentially penetrate breccia more effectively than lower energy beams. This study demonstrates that lower energy beams produce superior images for prioritising breccia for preparation. Additionally, XCT scanners are numerous, accessible, fast and relatively cost-effective when compared to μXCT scanners – the latter are not freely available, scanning times are much longer and there are significant limitations on the size and weight of scannable objects. Breccia blocks from Malapa were scanned at high and lower energy and images were analysed for image quality, artifact and certainty of diagnosis. Results show that lower energy images are deemed superior to higher energy images for this particular application. This finding, taken together with the limitations associated with the use of μXCT for the imaging of the large breccia from Malapa, shows that XCT is the better modality for this specific application. The ability to choose fossil-bearing breccia, ahead of manual mechanical preparation by laboratory technicians, would allow for the optimal use of limited resources, manual preparatory skills as well as the curtailment of costs.

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“…However, techniques are likely to become available in the future that will help to remove contrast agents from stained specimens (Schmidbaur et al 2015, Gignac et al 2016. Furthermore, in case of specimens intended for DNA extraction, alterations of the genetic code due to the X-ray dose a sample might receive during scanning cannot be ruled out (Paredes et al 2012, Hall et al 2015, Immel et al 2016, Wanek & Rühli 2016.…”

Section: Methodological Considerationsmentioning

confidence: 99%

<p class="HeadingRunIn"><strong>Combined visualization of echinoderm hard and soft parts using contrast-enhanced micro-computed tomography</strong></p>

Ziegler

2019

Zoosymposia

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Recent studies have shown that micro-computed tomography (µCT) must be considered one of the most suitable techniques for the non-invasive, three-dimensional (3D) visualization of metazoan hard parts. In addition, µCT can also be used to visualize soft part anatomy non-destructively and in 3D. In order to achieve soft tissue contrast using µCT based on X-ray attenuation, fixed specimens must be immersed in staining solutions that include heavy metals such as silver (Ag), molybdenum (Mo), osmium (Os), lead (Pb), or tungsten (W). However, while contrast-enhancement has been successfully applied to specimens pertaining to various higher metazoan taxa, echinoderms have thus far not been analyzed using this approach. In order to demonstrate that this group of marine invertebrates is suitable for contrast-enhanced µCT as well, the present study provides results from an application of this technique to representative species from all five extant higher echinoderm taxa. To achieve soft part contrast, freshly fixed and museum specimens were immersed in an ethanol solution containing phosphotungstic acid and then scanned using a high-resolution desktop µCT system. The acquired datasets show that the combined visualization of echinoderm soft and hard parts can be readily accomplished using contrast-enhanced µCT in all extant echinoderm taxa. The results are compared with µCT data obtained using unstained specimens, with conventional histological sections, and with data previously acquired using magnetic resonance imaging, a technique known to provide excellent soft tissue contrast despite certain limitations. The suitability for 3D visualization and modeling of datasets gathered using contrast-enhanced µCT is illustrated and applications of this novel approach in echinoderm research are discussed.

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Effect of X-ray irradiation on ancient DNA in sub-fossil bones – Guidelines for safe X-ray imaging

Cited by 85 publications

References 44 publications

Disentangling isolated dental remains of Asian Pleistocene hominins and pongines

Disentangling isolated dental remains of Asian Pleistocene hominins and pongines

Finding fossils in Malapa breccia – medical CT scanning or micro-CT scanning?

<p class="HeadingRunIn"><strong>Combined visualization of echinoderm hard and soft parts using contrast-enhanced micro-computed tomography</strong></p>

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