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An evidence-based 3D reconstruction of Asteroxylon mackiei, the most complex plant preserved from the Rhynie chert.

ABSTRACT: The Early Devonian Rhynie chert preserves the earliest terrestrial ecosystem and informs our understanding of early life on land. However, our knowledge of the 3D structure, and development of these plants is still rudimentary. Here we used digital 3D reconstruction techniques to produce the first well-evidenced reconstruction of the structure and development of the rooting system of the lycopsid Asteroxylon mackiei, the most complex plant in the Rhynie chert. The reconstruction reveals the organisation of the three distinct axis types - leafy shoot axes, root-bearing axes, and rooting axes - in the body plan. Combining this reconstruction with developmental data from fossilised meristems, we demonstrate that the A. mackiei rooting axis - a transitional lycophyte organ between the rootless ancestral state and true roots - developed from root-bearing axes by anisotomous dichotomy. Our discovery demonstrates how this unique organ developed and highlights the value of evidence-based reconstructions for understanding the development and evolution of the first complex vascular plants on Earth.

SUBMITTER: Hetherington AJ

PROVIDER: S-EPMC8384418 | biostudies-literature | 2021 Aug

REPOSITORIES: biostudies-literature

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An evidence-based 3D reconstruction of <i>Asteroxylon mackiei</i>, the most complex plant preserved from the Rhynie chert.

Hetherington Alexander J AJ Bridson Siobhán L SL Lee Jones Anna A Hass Hagen H Kerp Hans H Dolan Liam L

eLife 20210824

The Early Devonian Rhynie chert preserves the earliest terrestrial ecosystem and informs our understanding of early life on land. However, our knowledge of the 3D structure, and development of these plants is still rudimentary. Here we used digital 3D reconstruction techniques to produce the first well-evidenced reconstruction of the structure and development of the rooting system of the lycopsid <i>Asteroxylon mackiei</i>, the most complex plant in the Rhynie chert. The reconstruction reveals t ...[more]

PMID: 34425940

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Project description:BackgroundPrognosis of stage IV colorectal cancer is related to control of liver metastasis. As of now, surgery provides survival advantage for patients affected by resectable colorectal liver metastases (CRLM), with parenchymal sparing strategies representing the most accepted strategy {[1]. In this setting, 3D reconstruction programs represent the newest available technological leap to improve anatomical accuracy [2]. Despite being quite expensive, 3D models have proved themselves as helpful adjunctive tools to enhance pre-operative strategy [3] in complex liver procedures, even in the eyes of expert hepatobiliary surgeons [4].MethodsWe present a video describing the practical use of a custom-made 3D model, acquired following specific quality criteria [2], for a case of bilateral CLRM after neoadjuvant chemotherapy.ResultsIn our reported case and as described in the video, pre-operative visualization of 3D reconstructions altered significantly the pre-operative surgical plan. First, following the principles of parenchymal sparing surgery, challenging atypical resections of metastatic lesions close to main vessels (right posterior branch of the portal vein, inferior vena cava) were preferred to anatomic resections/major hepatectomies, allowing the highest projected future liver remnant volume possible (up to 65%) amongst different available strategies. Secondly, the order of hepatic resections was planned to follow a decreasing degree of difficulty, in order minimize the effect of blood redistribution after previous resections during parenchymal dissection (thus starting from atypical resections close to main vessels, followed by anatomical resections and atypical resections of superficial resections). In addition, the availability of the 3D model in the operating room was crucial in the surgical field to guide safe surgical pathways, especially during atypical resections of lesions close to the main vessels: detection and navigation were further enhanced thanks to tools of augmented reality that allowed the surgeon to manipulate the 3D model through a touchless sensor in a dedicated screen in the operating room and to replicate a mirroring snapshot of the surgical field, without compromising sterility nor the surgical set-up. In the setting of these complex liver procedures, the application of 3D printed models has been described [4]; when available, 3D printed models, particularly useful in the pre-operative phase when explaining the procedure to patients and relatives, have been reported to have comparable significant impact, with feedback from expert hepatobiliary surgeons that is very similar to the one we are reporting in our experience [4].ConclusionRoutine use of 3D technology does not claim to revolutionize the world of traditional imaging but may be impactful in helping the surgeon visualize the anatomy of that specific individual in a dynamic and three-dimensional way that is similar to the surgical field, thus improving multidisciplinary preoperative planning and intraoperative navigation during complex liver surgery.

Project description:Background and aimsIntercropping systems contain two or more species simultaneously in close proximity. Due to contrasting features of the component crops, quantification of the light environment and photosynthetic productivity is extremely difficult. However it is an essential component of productivity. Here, a low-tech but high-resolution method is presented that can be applied to single- and multi-species cropping systems to facilitate characterization of the light environment. Different row layouts of an intercrop consisting of Bambara groundnut ( Vigna subterranea ) and proso millet ( Panicum miliaceum ) have been used as an example and the new opportunities presented by this approach have been analysed.MethodsThree-dimensional plant reconstruction, based on stereo cameras, combined with ray tracing was implemented to explore the light environment within the Bambara groundnut-proso millet intercropping system and associated monocrops. Gas exchange data were used to predict the total carbon gain of each component crop.Key resultsThe shading influence of the tall proso millet on the shorter Bambara groundnut results in a reduction in total canopy light interception and carbon gain. However, the increased leaf area index (LAI) of proso millet, higher photosynthetic potential due to the C4 pathway and sub-optimal photosynthetic acclimation of Bambara groundnut to shade means that increasing the number of rows of millet will lead to greater light interception and carbon gain per unit ground area, despite Bambara groundnut intercepting more light per unit leaf area.ConclusionsThree-dimensional reconstruction combined with ray tracing provides a novel, accurate method of exploring the light environment within an intercrop that does not require difficult measurements of light interception and data-intensive manual reconstruction, especially for such systems with inherently high spatial possibilities. It provides new opportunities for calculating potential productivity within multi-species cropping systems, enables the quantification of dynamic physiological differences between crops grown as monoculture and those within intercrops, and enables the prediction of new productive combinations of previously untested crops.

Dataset Information

An evidence-based 3D reconstruction of Asteroxylon mackiei, the most complex plant preserved from the Rhynie chert.

Publications

An evidence-based 3D reconstruction of <i>Asteroxylon mackiei</i>, the most complex plant preserved from the Rhynie chert.

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