scholarly journals Early metazoan life: divergence, environment and ecology

2015 ◽  
Vol 370 (1684) ◽  
pp. 20150036 ◽  
Author(s):  
Douglas H. Erwin
Keyword(s):  
Nervous System ◽  
Molecular Clock ◽  
Fossil Record ◽  
Environmental Changes ◽  
Cell Type ◽  
Geochemical Proxies ◽  
Model Complex ◽  
Type Specification ◽  
Early Metazoan ◽  
Atmospheric Level

Recent molecular clock studies date the origin of Metazoa to 750–800 million years ago (Ma), roughly coinciding with evidence from geochemical proxies that oxygen levels rose from less than 0.1% present atmospheric level (PAL) to perhaps 1–3% PAL O 2 . A younger origin of Metazoa would require greatly increased substitution rates across many clades and many genes; while not impossible, this is less parsimonious. Yet the first fossil evidence for metazoans (the Doushantuo embryos) about 600 Ma is followed by the Ediacaran fossils after 580 Ma, the earliest undisputed bilaterians at 555 Ma, and an increase in the size and morphologic complexity of bilaterians around 542 Ma. This temporal framework suggests a missing 150–200 Myr of early metazoan history that encompasses many apparent novelties in the early evolution of the nervous system. This span includes two major glaciations, and complex marine geochemical changes including major changes in redox and other environmental changes. One possible resolution is that animals of these still unknown Cryogenian and early Ediacaran ecosystems were relatively simple, with highly conserved developmental genes involved in cell-type specification and simple patterning. In this model, complex nervous systems are a convergent phenomenon in bilaterian clades which occurred close to the time that larger metazoans appeared in the fossil record.

scholarly journals Awareness and integrated information theory identify plant meristems as sites of conscious activity

PROTOPLASMA ◽  
2021 ◽  
Author(s):  
Anthony Trewavas
Keyword(s):  
Information Theory ◽  
Nervous System ◽  
Complex Networks ◽  
Environmental Changes ◽  
Biological Function ◽  
Human Consciousness ◽  
Extrinsic Information ◽  
Integrated Information Theory ◽  
Conscious Activity ◽  
Integrated Information

AbstractLacking an anatomical brain/nervous system, it is assumed plants are not conscious. The biological function of consciousness is an input to behaviour; it is adaptive (subject to selection) and based on information. Complex language makes human consciousness unique. Consciousness is equated to awareness. All organisms are aware of their surroundings, modifying their behaviour to improve survival. Awareness requires assessment too. The mechanisms of animal assessment are neural while molecular and electrical in plants. Awareness of plants being also consciousness may resolve controversy. The integrated information theory (IIT), a leading theory of consciousness, is also blind to brains, nerves and synapses. The integrated information theory indicates plant awareness involves information of two kinds: (1) communicative, extrinsic information as a result of the perception of environmental changes and (2) integrated intrinsic information located in the shoot and root meristems and possibly cambium. The combination of information constructs an information nexus in the meristems leading to assessment and behaviour. The interpretation of integrated information in meristems probably involves the complex networks built around [Ca2+]i that also enable plant learning, memory and intelligent activities. A mature plant contains a large number of conjoined, conscious or aware, meristems possibly unique in the living kingdom.

The fossil record of Phasmida (Insecta: Neoptera)

2000 ◽  
Vol 31 (4) ◽  
pp. 473-480 ◽  
Author(s):  
Erich Tilgner
Keyword(s):  
Dominican Republic ◽  
Molecular Clock ◽  
Fossil Record ◽  
Sister Group ◽  
Baltic Amber ◽  
Molecular Clock Dating

AbstractA review of the Phasmida fossil record is provided. No fossils of Timema Scudder are known. Euphasmida fossils include: Agathemera reclusa Scudder, Electrobaculum gracilis Sharov, Eophasma oregonense Sellick, Eophasma minor Sellick, Eophasmina manchesteri Sellick, Pseudoperla gracilipes Pictet, Pseudoperla lineata Pictet and various unclassified species from Grube Messel, Baltic amber, and Dominican Republic amber. The oldest documented Euphasmida fossils are 44-49 million years old; molecular clock dating underestimates the origin of the sister group Timema by at least 24 million years.

scholarly journals Adiponectin Controls Nutrient Availability in Hypothalamic Astrocytes

2021 ◽  
Vol 22 (4) ◽  
pp. 1587
Author(s):  
Nuri Song ◽  
Da Yeon Jeong ◽  
Thai Hien Tu ◽  
Byong Seo Park ◽  
Hye Rim Yang ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Adipose Tissue ◽  
Nutrient Availability ◽  
Acid Oxidation ◽  
Cell Type ◽  
Metabolic Processes ◽  
Nutrient Metabolism ◽  
Peripheral Tissues ◽  
The Central Nervous System

Adiponectin, an adipose tissue-derived hormone, plays integral roles in lipid and glucose metabolism in peripheral tissues, such as the skeletal muscle, adipose tissue, and liver. Moreover, it has also been shown to have an impact on metabolic processes in the central nervous system. Astrocytes comprise the most abundant cell type in the central nervous system and actively participate in metabolic processes between blood vessels and neurons. However, the ability of adiponectin to control nutrient metabolism in astrocytes has not yet been fully elucidated. In this study, we investigated the effects of adiponectin on multiple metabolic processes in hypothalamic astrocytes. Adiponectin enhanced glucose uptake, glycolytic processes and fatty acid oxidation in cultured primary hypothalamic astrocytes. In line with these findings, we also found that adiponectin treatment effectively enhanced synthesis and release of monocarboxylates. Overall, these data suggested that adiponectin triggers catabolic processes in astrocytes, thereby enhancing nutrient availability in the hypothalamus.

Anatomical, morphometric, and stratigraphic analyses of theropod biodiversity in the Upper Cretaceous (Campanian) Dinosaur Park Formation

2021 ◽  
pp. 1-15
Author(s):  
Thomas M. Cullen ◽  
Lindsay Zanno ◽  
Derek W. Larson ◽  
Erinn Todd ◽  
Philip J. Currie ◽  
...  
Keyword(s):  
High Resolution ◽  
North America ◽  
Fossil Record ◽  
Upper Cretaceous ◽  
Environmental Changes ◽  
Morphometric Analyses ◽  
Variable Distribution ◽  
Taxic Diversity ◽  
Dinosaur Park Formation ◽  
Broad Scale

The Dinosaur Park Formation (DPF) of Alberta, Canada, has produced one of the most diverse dinosaur faunas, with the record favouring large-bodied taxa, in terms of number and completeness of skeletons. Although small theropods are well documented in the assemblage, taxonomic assessments are frequently based on isolated, fragmentary skeletal elements. Here we reassess DPF theropod biodiversity using morphological comparisons, high-resolution biostratigraphy, and morphometric analyses, with a focus on specimens/taxa originally described from isolated material. In addition to clarifying taxic diversity, we test whether DPF theropods preserve faunal zonation/turnover patterns similar to those previously documented for megaherbivores. Frontal bones referred to a therizinosaur (cf. Erlikosaurus), representing among the only skeletal record of the group from the Campanian–Maastrichtian (83–66 Ma) fossil record of North America, plot most closely to troodontids in morphospace, distinct from non-DPF therizinosaurs, a placement supported by a suite of troodontid anatomical frontal characters. Postcranial material referred to cf. Erlikosaurus in North America is also reviewed and found most similar in morphology to caenagnathids, rather than therizinosaurs. Among troodontids, we document considerable morphospace and biostratigraphic overlap between Stenonychosaurus and the recently described Latenivenatrix, as well as a variable distribution of putatively autapomorphic characters, calling the validity of the latter taxon into question. Biostratigraphically, there are no broad-scale patterns of faunal zonation similar to those previously documented in ornithischians from the DPF, with many theropods ranging throughout much of the formation and overlapping extensively, possibly reflecting a lack of sensitivity to environmental changes, or other cryptic ecological or evolutionary factors.

scholarly journals Structural Basis for Partial Redundancy in a Class of Transcription Factors, the LIM Homeodomain Proteins, in Neural Cell Type Specification

2011 ◽  
Vol 286 (50) ◽  
pp. 42971-42980 ◽  
Author(s):  
Morgan S. Gadd ◽  
Mugdha Bhati ◽  
Cy M. Jeffries ◽  
David B. Langley ◽  
Jill Trewhella ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Neural Cell ◽  
Structural Basis ◽  
Cell Type ◽  
Homeodomain Proteins ◽  
Partial Redundancy ◽  
Type Specification ◽  
Lim Homeodomain

scholarly journals STAG2 promotes the myelination transcriptional program in oligodendrocytes

2021 ◽  
Author(s):  
Ningyan Cheng ◽  
Mohammed Kanchwala ◽  
Bret M. Evers ◽  
Chao Xing ◽  
Hongtao Yu
Keyword(s):  
Nervous System ◽  
Growth Retardation ◽  
Premature Death ◽  
Nerve Fibers ◽  
Conditional Knockout ◽  
Cell Type ◽  
Transcriptional Program ◽  
Dna Loop ◽  
Delayed Maturation ◽  
Relevant Cell Type

SUMMARYCohesin folds chromosomes via DNA loop extrusion. Cohesin-mediated chromosome loops regulate transcription by shaping long-range enhancer-promoter interactions, among other mechanisms. Mutations of cohesin subunits and regulators cause human developmental diseases termed cohesinopathy. Vertebrate cohesin consists of SMC1, SMC3, RAD21, and either STAG1 or STAG2. To probe the physiological functions of cohesin, we created conditional knockout (cKO) mice with Stag2 deleted in the nervous system. Stag2 cKO mice exhibit growth retardation, neurological defects, and premature death, in part due to insufficient myelination of nerve fibers. Stag2 cKO oligodendrocytes exhibit delayed maturation and downregulation of myelination-related genes. Stag2 loss reduces promoter-anchored loops at downregulated genes in oligodendrocytes. Thus, STAG2-cohesin generates promoter-anchored loops at myelination-promoting genes to facilitate their transcription. Our study implicates defective myelination as a contributing factor to cohesinopathy and establishes oligodendrocytes as a relevant cell type to explore the mechanisms by which cohesin regulates transcription.

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