scholarly journals Presence of three mycorrhizal genes in the common ancestor of land plants suggests a key role of mycorrhizas in the colonization of land by plants

2010 ◽  
Vol 186 (2) ◽  
pp. 514-525 ◽  
Author(s):  
Bin Wang ◽  
Li Huey Yeun ◽  
Jia-Yu Xue ◽  
Yang Liu ◽  
Jean-Michel Ané ◽  
...  
Keyword(s):  
Common Ancestor ◽  
Land Plants ◽  
The Common ◽  
Colonization Of Land

scholarly journals Role of the Digestive Gland in Ink Production in Four Species of Sea Hares: An Ultrastructural Comparison

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Jeffrey S. Prince ◽  
Paul Micah Johnson
Keyword(s):  
Digestive Gland ◽  
Common Ancestor ◽  
Aplysia Californica ◽  
Digestive Cell ◽  
Digestive Cells ◽  
Sea Hare ◽  
Red Algal ◽  
The Common ◽  
Algal Chloroplast

The ultrastructure of the digestive gland of several sea hare species that produce different colored ink (Aplysia californicaproduces purple ink,A. julianawhite ink,A. parvulaboth white and purple ink, whileDolabrifera dolabriferaproduces no ink at all) was compared to determine the digestive gland’s role in the diet-derived ink production process. Rhodoplast digestive cells and their digestive vacuoles, the site of digestion of red algal chloroplast (i.e., rhodoplast) inA. californica, were present and had a similar ultrastructure in all four species. Rhodoplast digestive cell vacuoles either contained a whole rhodoplast or fragments of one or were empty. These results suggest that the inability to produce colored ink in some sea hare species is not due to either an absence of appropriate digestive machinery, that is, rhodoplast digestive cells, or an apparent failure of rhodoplast digestive cells to function. These results also propose that the digestive gland structure described herein occurred early in sea hare evolution, at least in the common ancestor to the generaAplysiaandDolabrifera. Our data, however, do not support the hypothesis that the loss of purple inking is a synapomorphy of the white-ink-producing subgenusAplysia.

scholarly journals β-Catenin–dependent mechanotransduction dates back to the common ancestor of Cnidaria and Bilateria

2018 ◽  
Vol 115 (24) ◽  
pp. 6231-6236 ◽  
Author(s):  
Ekaterina Pukhlyakova ◽  
Andrew J. Aman ◽  
Kareem Elsayad ◽  
Ulrich Technau
Keyword(s):  
Gene Expression ◽  
Common Ancestor ◽  
Marker Gene ◽  
Genetic Regulation ◽  
Regulation Of Gene Expression ◽  
Model Organism ◽  
The Common ◽  
Gene Regulatory ◽  
Ancient Gene

Although the genetic regulation of cellular differentiation processes is well established, recent studies have revealed the role of mechanotransduction on a variety of biological processes, including regulation of gene expression. However, it remains unclear how universal and widespread mechanotransduction is in embryonic development of animals. Here, we investigate mechanosensitive gene expression during gastrulation of the starlet sea anemone Nematostella vectensis, a cnidarian model organism. We show that the blastoporal marker gene brachyury is down-regulated by blocking myosin II-dependent gastrulation movements. Brachyury expression can be restored by applying external mechanical force. Using CRISPR/Cas9 and morpholino antisense technology, we also show that mechanotransduction leading to brachyury expression is β-catenin dependent, similar to recent findings in fish and Drosophila [Brunet T, et al. (2013) Nat Commun 4:1–15]. Finally, we demonstrate that prolonged application of mechanical stress on the embryo leads to ectopic brachyury expression. Thus, our data indicate that β-catenin–dependent mechanotransduction is an ancient gene regulatory mechanism, which was present in the common ancestor of cnidarians and bilaterians, at least 600 million years ago.

scholarly journals The role of invasive trophoblast in implantation and placentation of primates

2015 ◽  
Vol 370 (1663) ◽  
pp. 20140070 ◽  
Author(s):  
Anthony M. Carter ◽  
Allen C. Enders ◽  
Robert Pijnenborg
Keyword(s):  
Basal Lamina ◽  
Common Ancestor ◽  
Great Apes ◽  
Blastocyst Stage ◽  
Trophoblast Invasion ◽  
Deep Penetration ◽  
Old World Monkeys ◽  
Non Invasive ◽  
The Common

We here review the evolution of invasive placentation in primates towards the deep penetration of the endometrium and its arteries in hominoids. The strepsirrhine primates (lemurs and lorises) have non-invasive, epitheliochorial placentation, although this is thought to be derived from a more invasive type. In haplorhine primates, there is differentiation of trophoblast at the blastocyst stage into syncytial and cellular trophoblast. Implantation involves syncytiotrophoblast that first removes the uterine epithelium then consolidates at the basal lamina before continuing into the stroma. In later stages of pregnancy, especially in Old World monkeys and apes, cytotrophoblast plays a greater role in the invasive process. Columns of trophoblast cells advance to the base of the implantation site where they spread out to form a cytotrophoblastic shell. In addition, cytotrophoblasts advance into the lumen of the spiral arteries. They are responsible for remodelling these vessels to form wide, low-resistance conduits. In human and great apes, there is additional invasion of the endometrium and its vessels by trophoblasts originating from the base of the anchoring villi. Deep trophoblast invasion that extends remodelling of the spiral arteries to segments in the inner myometrium evolved in the common ancestor of gorilla, chimp and human.

scholarly journals Divergent evolutionary trajectories of bryophytes and tracheophytes from a complex common ancestor of land plants

2021 ◽  
Author(s):  
Brogan J Harris ◽  
James W Clark ◽  
Dominik Schrempf ◽  
Gergely J Szöllősi ◽  
Philip Donoghue ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Vascular Plants ◽  
Common Ancestor ◽  
Land Plants ◽  
Terrestrial Environment ◽  
Stomatal Complex ◽  
Evolutionary Trajectories ◽  
Mapping Gene ◽  
Colonization Of Land

The origin of plants and their colonization of land resulted in the transformation of the terrestrial environment. Here we investigate the evolution of the land plants (embryophytes) and their two main lineages, the tracheophytes (vascular plants) and bryophytes (non vascular plants). We used new fossil calibrations, relative lineage dating implied by horizontal gene transfer, and new phylogenomic methods for mapping gene family origins. Distinct rooting strategies resolve tracheophytes and bryophytes as monophyletic sister groups that diverged in the Cambrian, 515-494 Ma. The embryophyte stem is characterised by a burst of gene innovation, while bryophytes subsequently experienced a no less dramatic episode of reductive genome evolution in which they lost genes associated with the elaboration of vasculature and the stomatal complex. Overall, our analyses confirm that extant tracheophytes and bryophytes are both highly derived; as a result, understanding the origin of land plants requires tracing character evolution across the diversity of modern lineages.

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 The evolution of land plants: a perspective from horizontal gene transfer

2014 ◽  
Vol 83 (4) ◽  
pp. 363-368 ◽  
Author(s):  
Qia Wang ◽  
Hang Sun ◽  
Jinling Huang
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Land Plant ◽  
Plant Evolution ◽  
Land Plants ◽  
Plant Colonization ◽  
Mitochondrial Genome Evolution ◽  
Land Plant Evolution ◽  
Colonization Of Land

Recent studies suggest that horizontal gene transfer (HGT) played a significant role in the evolution of eukaryotic lineages. We here review the mechanisms of HGT in plants and the importance of HGT in land plant evolution. In particular, we discuss the role of HGT in plant colonization of land, phototropic response, C<sub>4</sub> photosynthesis, and mitochondrial genome evolution.

scholarly journals RSL Class I Genes Controlled the Development of Epidermal Structures in the Common Ancestor of Land Plants

2016 ◽  
Vol 26 (1) ◽  
pp. 93-99 ◽  
Author(s):  
Hélène Proust ◽  
Suvi Honkanen ◽  
Victor A.S. Jones ◽  
Giulia Morieri ◽  
Helen Prescott ◽  
...  
Keyword(s):  
Common Ancestor ◽  
Land Plants ◽  
Class I ◽  
The Common

On everyday academic research

2017 ◽  
pp. 98-134 ◽  
Author(s):  
J. Tirole
Keyword(s):  
Common Good ◽  
Academic Research ◽  
Research Quality ◽  
Economic Research ◽  
Relevant Research ◽  
The Common ◽  
Verification Of Models ◽  
Science And Research

In the fourth chapter of the book “The economy of the common good”, the nature of economics as a science and research practices in their theoretical and empirical aspects are discussed. The author considers the processes of modeling, empirical verification of models and evaluation of research quality. In addition, the features of economic cognition and the role of mathematics in economic research are analyzed, including the example of relevant research in game theory and information theory.

Contemplative Principles of a Non-dual Praxis: the Unmediated Practices of the Tibetan ‘Heart Essence’ (sNying thig) Tradition

2015 ◽  
Vol 31 (2) ◽  
pp. 215-240
Author(s):  
Eran Laish
Keyword(s):  
Contemplative Practice ◽  
Tibetan Buddhist ◽  
Buddhist Tradition ◽  
The Common

This article focuses on the main contemplative principles of the ‘Heart Essence’ (sNying thig), a Tibetan Buddhist tradition that is characterized by a vision of non-duality and primordial wholeness. Due to this vision, which asserts an original reality that is not divided into perceiving subject and perceived object, the ‘Heart Essence’ advocates a contemplative practice that undermines the usual intuitions of temporality and enclosed selfhood. Hence, unlike the common principles of intentional praxis, such as deliberate concentration and gradual purification, the ‘Heart Essence’ affirms four contemplative principles of non-objectiveness, openness, spontaneity and singleness. As these principles transcend intentionality, temporality, and multiplicity, they are seen to directly disclose the nature of primordial awareness, in which the meanings of knowing and being are radically transformed. Therefore, the article will also consider the role of these non-dual contemplative principles in deeply changing our understanding of being and knowing alike.

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