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

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Alexander J Hetherington ◽  
Siobhán L Bridson ◽  
Anna Lee Jones ◽  
Hagen Hass ◽  
Hans Kerp ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Vascular Plants ◽  
3D Structure ◽  
Terrestrial Ecosystem ◽  
The Body ◽  
Evidence Based ◽  
Ancestral State ◽  
Early Devonian ◽  
Rhynie Chert ◽  
Development And Evolution

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.

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

2021 ◽  
Author(s):  
Alexander J Hetherington ◽  
Siobhán L Bridson ◽  
Anna Lee Jones ◽  
Hagen Hass ◽  
Hans Kerp ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Early Life ◽  
3D Structure ◽  
Terrestrial Ecosystem ◽  
The Body ◽  
Evidence Based ◽  
Ancestral State ◽  
Leafy Shoot ◽  
Rhynie Chert ◽  
Development And Evolution

The 407-million-year-old 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 complete reconstruction of the lycopsid Asteroxylon mackiei, the most complex plant in the Rhynie chert. The reconstruction reveals the organisation of the three distinct axes 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 plants on Earth.

A new crustacean from the Early Devonian Rhynie chert, Aberdeenshire, Scotland

2002 ◽  
Vol 93 (4) ◽  
pp. 355-382 ◽  
Author(s):  
Stephen R. Fayers ◽  
Nigel H. Trewin
Keyword(s):  
Hydrothermal Activity ◽  
The Body ◽  
Early Devonian ◽  
Rhynie Chert

ABSTRACTA new crustacean, Castracollis wilsonae is described from a loose block of the Early Devonian Rhynie chert, found in the vicinity of Rhynie, Aberdeenshire, Scotland. It differs markedly from Lepidocaris rhyniensis, Scourfield 1926, the only other crustacean found in the Rhynie chert.The material comprises complete individuals up to 8 mm long and fragmentary remains. The head is normally damaged and detached from the body, and damage to the anterior of the trunk suggests the specimens are exuviae. The head appears domed with a labrum, robust mandibles, and long biramous antennae. A few specimens exhibit a probable detached cephalo-thoracicshield. The trunk is multi-segmented, comprising similar ring-like somites. The thorax variably comprises up to 26 segments. The anterior 11 segments possess similar long, phyllopodous appendages, the remainder variably possess 10 to 15 phyllopodous appendages with a disposition of one per somite. The abdomen comprises up to 28 apodous segments. The posterior of the body comprises a telson with two furcal rami.The crustacean is most probably a calmanostracan branchiopod. It occurs associated with Lepidocaris, charophytes, cyanobacteria and coprolites within a ‘clotted’ chert texture, indicating subaqueous deposition, most probably in a temporary freshwater pool in an area of surficial hydrothermal activity.

scholarly journals Terrestrial invertebrates in the Rhynie chert ecosystem

2017 ◽  
Vol 373 (1739) ◽  
pp. 20160493 ◽  
Author(s):  
Jason A. Dunlop ◽  
Russell J. Garwood
Keyword(s):  
Early Life ◽  
Hot Springs ◽  
Terrestrial Ecosystem ◽  
Early Devonian ◽  
Male And Female ◽  
Terrestrial Invertebrates ◽  
Plant Parasitism ◽  
Liquid Feeding ◽  
Rhynie Chert ◽  
Nematode Worm

The Early Devonian Rhynie and Windyfield cherts remain a key locality for understanding early life and ecology on land. They host the oldest unequivocal nematode worm (Nematoda), which may also offer the earliest evidence for herbivory via plant parasitism. The trigonotarbids (Arachnida: Trigonotarbida) preserve the oldest book lungs and were probably predators that practiced liquid feeding. The oldest mites (Arachnida: Acariformes) are represented by taxa which include mycophages and predators on nematodes today. The earliest harvestman (Arachnida: Opiliones) includes the first preserved tracheae, and male and female genitalia. Myriapods are represented by a scutigeromorph centipede (Chilopoda: Scutigeromorpha), probably a cursorial predator on the substrate, and a putative millipede (Diplopoda). The oldest springtails (Hexapoda: Collembola) were probably mycophages, and another hexapod of uncertain affinities preserves a gut infill of phytodebris. The first true insects (Hexapoda: Insecta) are represented by a species known from chewing (non-carnivorous?) mandibles. Coprolites also provide insights into diet, and we challenge previous assumptions that several taxa were spore-feeders. Rhynie appears to preserve a largely intact community of terrestrial animals, although some expected groups are absent. The known fossils are (ecologically) consistent with at least part of the fauna found around modern Icelandic hot springs. This article is part of a discussion meeting issue ‘The Rhynie cherts: our earliest terrestrial ecosystem revisited’.

scholarly journals Bilaterally symmetric axes with rhizoids composed the rooting structure of the common ancestor of vascular plants

2017 ◽  
Vol 373 (1739) ◽  
pp. 20170042 ◽  
Author(s):  
Alexander J. Hetherington ◽  
Liam Dolan
Keyword(s):  
Vascular Plants ◽  
Common Ancestor ◽  
Terrestrial Ecosystem ◽  
Bilateral Symmetry ◽  
Land Plant ◽  
Land Plants ◽  
Free Living ◽  
Rhynie Chert ◽  
The Common ◽  
Almost All

There are two general types of rooting systems in extant land plants: gametophyte rhizoids and sporophyte root axes. These structures carry out the rooting function in the free-living stage of almost all land plant gametophytes and sporophytes, respectively. Extant vascular plants develop a dominant, free-living sporophyte on which roots form, with the exception of a small number of taxa that have secondarily lost roots. However, fossil evidence indicates that early vascular plants did not develop sporophyte roots. We propose that the common ancestor of vascular plants developed a unique rooting system—rhizoidal sporophyte axes. Here we present a synthesis and reinterpretation of the rootless sporophytes of Horneophyton lignieri , Aglaophyton majus , Rhynia gwynne-vaughanii and Nothia aphylla preserved in the Rhynie chert. We show that the sporophyte rooting structures of all four plants comprised regions of plagiotropic (horizontal) axes that developed unicellular rhizoids on their underside. These regions of axes with rhizoids developed bilateral symmetry making them distinct from the other regions which were radially symmetrical. We hypothesize that rhizoidal sporophyte axes constituted the rooting structures in the common ancestor of vascular plants because the phylogenetic positions of these plants span the origin of the vascular lineage. This article is part of a discussion meeting issue ‘The Rhynie cherts: our earliest terrestrial ecosystem revisited’.

scholarly journals Organs and tissues of Rhynie chert plants

2017 ◽  
Vol 373 (1739) ◽  
pp. 20160495 ◽  
Author(s):  
Hans Kerp
Keyword(s):  
Secondary Wall ◽  
Major Part ◽  
Terrestrial Ecosystem ◽  
Regular Pattern ◽  
Intercellular Spaces ◽  
Early Devonian ◽  
Short Stalk ◽  
Rhynie Chert ◽  
Thin Walled

The Early Devonian Rhynie chert and the nearby Windyfield chert contain the oldest in situ preserved terrestrial ecosystem. Two of the seven species of anatomically preserved land plants had naked axes, one an axis with a more or less regular pattern of short-longitudinal ribs, two species had spiny axes and one species had small leaf-like appendages. All plants mainly consist of parenchymatous tissues. In some species, conducting elements comprise uniformly thickened thick-walled cells resembling hydroids of larger bryophytes, whereas others have real tracheids with annular and/or spiral secondary wall thickenings. True phloem has never been demonstrated but in all species the thick-walled water-conducting cells are encircled by a zone of thin-walled cells without intercellular spaces. The cortex is differentiated into two or three zones and forms the major part of the axes; in one species the cells of the middle cortex are sclerified. Some species have a hypodermis. In all species the epidermis is covered by a well-developed cuticle. Sporangia are known from all species. Sporangia are spindle-shaped, lobed or kidney-shaped and attached terminally or laterally with a short stalk. Gametophytes of four species have been described. Gametophytes are unisexual, isomorphic but much smaller than the sporophytes. This article is part of a discussion meeting issue ‘The Rhynie cherts: our earliest terrestrial ecosystem revisited’.

Detection, Averaging, and 3D Reconstruction of Biological Specimens on Hypercubes (Transputer-based) Computers

1990 ◽  
Vol 48 (1) ◽  
pp. 454-455
Author(s):  
Jose-Maria Carazo ◽  
I. Benavides ◽  
S. Marco ◽  
J.L. Carrascosa ◽  
E.L. Zapata
Keyword(s):  
3D Reconstruction ◽  
3D Structure ◽  
Three Dimensional ◽  
Software Tools ◽  
Mapping Method ◽  
Computer Architectures ◽  
Parallel Computer ◽  
Reconstruction Process ◽  
Computing Power ◽  
Order Of Magnitude

Obtaining the three-dimensional (3D) structure of negatively stained biological specimens at a resolution of, typically, 2 - 4 nm is becoming a relatively common practice in an increasing number of laboratories. A combination of new conceptual approaches, new software tools, and faster computers have made this situation possible. However, all these 3D reconstruction processes are quite computer intensive, and the middle term future is full of suggestions entailing an even greater need of computing power. Up to now all published 3D reconstructions in this field have been performed on conventional (sequential) computers, but it is a fact that new parallel computer architectures represent the potential of order-of-magnitude increases in computing power and should, therefore, be considered for their possible application in the most computing intensive tasks.We have studied both shared-memory-based computer architectures, like the BBN Butterfly, and local-memory-based architectures, mainly hypercubes implemented on transputers, where we have used the algorithmic mapping method proposed by Zapata el at. In this work we have developed the basic software tools needed to obtain a 3D reconstruction from non-crystalline specimens (“single particles”) using the so-called Random Conical Tilt Series Method. We start from a pair of images presenting the same field, first tilted (by ≃55°) and then untilted. It is then assumed that we can supply the system with the image of the particle we are looking for (ideally, a 2D average from a previous study) and with a matrix describing the geometrical relationships between the tilted and untilted fields (this step is now accomplished by interactively marking a few pairs of corresponding features in the two fields). From here on the 3D reconstruction process may be run automatically.

Doctor of Nursing Practice: Integrating Theory, Research, and Evidence-Based Practice

2013 ◽  
Vol 6 (1) ◽  
pp. 4-8 ◽  
Author(s):  
Bridget R. Roberts
Keyword(s):  
Nursing Practice ◽  
Evidence Based Practice ◽  
Strong Relationship ◽  
The Body ◽  
Evidence Based ◽  
Advanced Practice ◽  
Nursing Knowledge ◽  
Doctor Of Nursing Practice ◽  
Practice Nurses ◽  
Theory Research

A strong relationship exists between theory, research, and evidence-based practice; and these three entities are necessary to guide practice and contribute to the body of nursing knowledge. Doctor of nursing practice graduates can serve as leaders as they enter into their respective clinical practice areas. Through education of peers, along with translation and evaluation of current theoretical literature and empirical data, these advanced practice nurses can positively influence nursing practice and patient care.

Abstract WP282: Protecting Stroke Patients from Aspiration and Mortality through a Bedside Aspiration Screen

Stroke ◽  
2013 ◽  
Vol 44 (suppl_1) ◽  
Author(s):  
Edith Matesic
Keyword(s):  
Organizational Learning ◽  
Aspiration Pneumonia ◽  
The Body ◽  
Kappa Statistics ◽  
Evidence Based ◽  
Stroke Patients ◽  
Rater Reliability ◽  
Stroke Treatment ◽  
Risk Of Death ◽  
The Impact

Background: Stroke patients initially experience dysphagia approximately 42-76% of the time, putting them at high risk for developing aspiration pneumonia and increasing the risk of death threefold in the first 30 days following onset of the condition. Interventions to identify risk for aspiration pneumonia are key to reducing mortality in hospitalized patients. However, no generally recognized bedside aspiration screen exists, and few have been rigorously tested. The Edith-Huhn-Matesic Bedside Aspiration Screen (EHMBAS) TM was developed as an evidence-based RN bedside aspiration screening protocol. Purpose: This study analyzed the sensitivity and inter-rater reliability of EHMBAS TM , assessed the efficacy of training methods, evaluated patient feedback, and looked at the impact of organizational learning. Methods: RNs were trained to apply the EHMBAS TM . An evaluation study assessed the sensitivity, specificity and predictability of the screen to detect aspiration in the stroke population study group. Cohen’s Kappa statistics was applied to test inter-rater reliability. Pre- and post-implementation Likert surveys examined patient and staff satisfaction on the education plan and screening process, respectively. Lastly, an analysis of organizational learning examined whether changes enhanced adherence to screening requirements. Results: Results showed that the EHMBAS TM demonstrated strong validity (94% sensitivity) and high inter-rater reliability (Kappa = .92, p<.001). Pre- and post- staff training survey results demonstrated a significant positive change in knowledge gained, feelings of preparedness, and satisfaction with teaching methods. Further, 92.3% of patients surveyed had positive screening experiences. The hospital received Silver recognition from The American Heart Association for following stroke treatment guidelines 85% of the time for at least 12 months, demonstrating the positive impact of the protocol on organizational change. Conclusions: This study contributes to the body of work aimed at establishing a reliable evidence-based, bedside aspiration screen. Patient safety is enhanced, because screen results help determine when patients can safely receive medication and nutrition by mouth.

The physical basis of mollusk shell chiral coiling

2021 ◽  
Vol 118 (48) ◽  
pp. e2109210118
Author(s):  
Régis Chirat ◽  
Alain Goriely ◽  
Derek E. Moulton
Keyword(s):  
Mathematical Model ◽  
The Body ◽  
Symmetric Body ◽  
Model Organisms ◽  
Physical Interaction ◽  
Mechanical Forces ◽  
Hard Shell ◽  
Left Right Asymmetry ◽  
Development And Evolution ◽  
Mollusk Shell

Snails are model organisms for studying the genetic, molecular, and developmental bases of left–right asymmetry in Bilateria. However, the development of their typical helicospiral shell, present for the last 540 million years in environments as different as the abyss or our gardens, remains poorly understood. Conversely, ammonites typically have a bilaterally symmetric, planispiraly coiled shell, with only 1% of 3,000 genera displaying either a helicospiral or a meandering asymmetric shell. A comparative analysis suggests that the development of chiral shells in these mollusks is different and that, unlike snails, ammonites with asymmetric shells probably had a bilaterally symmetric body diagnostic of cephalopods. We propose a mathematical model for the growth of shells, taking into account the physical interaction during development between the soft mollusk body and its hard shell. Our model shows that a growth mismatch between the secreted shell tube and a bilaterally symmetric body in ammonites can generate mechanical forces that are balanced by a twist of the body, breaking shell symmetry. In gastropods, where a twist is intrinsic to the body, the same model predicts that helicospiral shells are the most likely shell forms. Our model explains a large diversity of forms and shows that, although molluscan shells are incrementally secreted at their opening, the path followed by the shell edge and the resulting form are partly governed by the mechanics of the body inside the shell, a perspective that explains many aspects of their development and evolution.

Evolution and environment in the late Silurian-early Devonian: the rise of the pteridophytes

1985 ◽  
Vol 309 (1138) ◽  
pp. 147-165 ◽  
Keyword(s):  
Vascular Plants ◽  
Preliminary Report ◽  
Life Histories ◽  
Early History ◽  
Flora Of Australia ◽  
Early Devonian ◽  
The World ◽  
History Of

A brief review of the major advances since 1979 in Silurian and Devonian palaeobotany is followed by a preliminary report on a Gedinnian assemblage from the Welsh Borderland. This is dominated by rhyniopsids and includes several species of Cooksonia and Salopella . Spores have been isolated from a number of taxa. The assemblage is used to illustrate the problems of recognition and classification of early vascular plants. Parallel sedimentological and palaeogeographical studies permit speculation on the ecology and life histories of the plants that colonized the Old Red Continent. It is concluded that the lack of well preserved and independently dated assemblages from elsewhere in the world (an exception being the Baragwanathia flora of Australia) prevents the detection of any provincialism in the late Silurian and early Devonian and makes generalizations on the early history of vascular plants premature.

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