3 �2-Microglobulin, Histocompatibility and H-Y Antigen Homologues in Invertebrates and Early Vertebrates

2015 ◽  
pp. 49-78
Author(s):  
Abraham Shalev ◽  
Lennart L�gdberg ◽  
Lars Bj�rck
Keyword(s):  
Early Vertebrates

Early vertebrates

Endeavour ◽  
1997 ◽  
Vol 21 (1) ◽  
pp. 45 ◽  
Author(s):  
Douglas Palmer
Keyword(s):  
Early Vertebrates

scholarly journals On the Expansion of “Dangerous” Gene Repertoires by Whole-Genome Duplications in Early Vertebrates

Cell Reports ◽  
2012 ◽  
Vol 2 (5) ◽  
pp. 1387-1398 ◽  
Author(s):  
Param Priya Singh ◽  
Séverine Affeldt ◽  
Ilaria Cascone ◽  
Rasim Selimoglu ◽  
Jacques Camonis ◽  
...  
Keyword(s):  
Whole Genome ◽  
Whole Genome Duplications ◽  
Genome Duplications ◽  
Early Vertebrates

The recovery of early vertebrates and reef ecosystems following the late Silurian carbon isotope excursion: the Burgen outlier, Gotland, Sweden

2021 ◽  
Author(s):  
Emilia Jarochowska ◽  
Oskar Bremer ◽  
Alexandra Yiu ◽  
Tiiu Märss ◽  
Henning Blom ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Carbonate Platform ◽  
Fish Diversity ◽  
Global Environmental ◽  
Carbon Isotope Excursion ◽  
Low Diversity ◽  
Early Vertebrates ◽  
Carbonate Factory ◽  
Faunal Distribution ◽  
Rapid Regression

<p>The Ludfordian Carbon Isotope Excursion (LCIE) reached the highest known δ<sup>13</sup>C values in the Phanerozoic. It was a global environmental perturbation manifested in a rapid regression attributed to glacial eustasy. Previous studies suggested that it has also heavily affected the diversity of conodonts, early vertebrates and reef ecosystems, but the timing of the crisis and recovery remained complicated owing to the lateral variability of δ<sup>13</sup>C values in epeiric platforms and rapid facies shifts, which drove faunal distribution. One of the best records of this interval is available in the Swedish island of Gotland, which preserves tectonically undisturbed strata deposited in a Silurian tropical carbonate platform. We revisited the world-renowned collection of the late Lennart Jeppsson, hosted at the Swedish Museum of Natural History, Stockholm, which holds the key to reconstruct the dynamics of faunal immigration and diversification following the LCIE. Here we focus on the Burgen erosional outlier, which remained a mystery, as it had been correlated with the excursion strata, but preserved a high diversity of conodonts and reefal ecosystems. We re-examined key outcrops and characterized macro- and microfacies, as well as chemostratigraphy and unpublished fauna in the collection. Strata in the Burgen outlier represent back-shoal facies of the Burgsvik Oolite Member and correspond to the Ozarkodina snajdri Conodont Biozone. The shallow-marine position compared to the more continental setting of coeval strata in southern Gotland, is reflected in the higher δ<sup>13</sup>C<sub>carb</sub> values, reaching +9.2‰. The back-shoal succession in this outcrop includes reefs, which contain a large proportion of microbial carbonates and have therefore been previously compared with low-diversity buildups developed in a stressed ecosystem. However, the framework of these reefs is built by a diverse coral-stromatoporoid-bryozoan fauna, indicating that a high microbial contribution might be a characteristic of the local carbonate factory rather than a reflection of restricted conditions. In the case of conodonts, impoverishment following the LCIE might be a product of facies preferences, as the diverse environments in the outlier yielded at least 20 of the 21 species known from the Burgsvik Formation in Gotland. Fish diversity also returned to normal levels following the LCIE with an estimated minimum of 9 species. Thelodont scales appear to dominate samples from the Burgen outlier, which is in line with previous reports. Our observations highlight how palaeoenvironmental reconstructions inform fossil niche and diversity analyses, but also how fossil museum collections continuously contribute new data on past biodiversity.</p>

Diversity and Evolution of Mineralized Skeletal Tissues in Chondrichthyans

2021 ◽  
Vol 9 ◽  
Author(s):  
Fidji Berio ◽  
Morgane Broyon ◽  
Sébastien Enault ◽  
Nelly Pirot ◽  
Faviel A. López-Romero ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Phylogenetic Relationships ◽  
Current Knowledge ◽  
Neural Arch ◽  
Fossil Species ◽  
Fibrous Matrix ◽  
Cartilaginous Matrix ◽  
Mineralized Tissues ◽  
Early Vertebrates ◽  
Cartilaginous Fishes

The diversity of skeletal tissues in extant vertebrates includes mineralized and unmineralized structures made of bone, cartilage, or tissues of intermediate nature. This variability, together with the diverse nature of skeletal tissues in fossil species question the origin of skeletonization in early vertebrates. In particular, the study of skeletal tissues in cartilaginous fishes is currently mostly restrained to tessellated cartilage, a derived form of mineralized cartilage that evolved at the origin of this group. In this work, we describe the architectural and histological diversity of neural arch mineralization in cartilaginous fishes. The observed variations in the architecture include tessellated cartilage, with or without more massive sites of mineralization, and continuously mineralized neural arches devoid of tesserae. The histology of these various architectures always includes globular mineralization that takes place in the cartilaginous matrix. In many instances, the mineralized structures also include a fibrous component that seems to emerge from the perichondrium and they may display intermediate features, ranging from partly cartilaginous to mostly fibrous matrix, similar to fibrocartilage. Among these perichondrial mineralized tissues is also found, in few species, a lamellar arrangement of the mineralized extracellular matrix. The evolution of the mineralized tissues in cartilaginous fishes is discussed in light of current knowledge of their phylogenetic relationships.

scholarly journals Zebrafish Thrombocytes: Functions and Origins

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Gauri Khandekar ◽  
Seongcheol Kim ◽  
Pudur Jagadeeswaran
Keyword(s):  
Platelet Function ◽  
Genetic Model ◽  
Cost Effective ◽  
Transgenic Zebrafish ◽  
Functional Genomic ◽  
Zebrafish Model ◽  
Functional Roles ◽  
Functional Assays ◽  
Genomic Studies ◽  
Early Vertebrates

Platelets play an important role in mammalian hemostasis. Thrombocytes of early vertebrates are functionally equivalent to mammalian platelets. A substantial amount of research has been done to study platelet function in humans as well as in animal models. However, to date only limited functional genomic studies of platelets have been performed but are low throughput and are not cost-effective. Keeping this in mind we introduced zebrafish, a vertebrate genetic model to study platelet function. We characterized zebrafish thrombocytes and established functional assays study not only their hemostatic function but to also their production. We identified a few genes which play a role in their function and production. Since we introduced the zebrafish model for the study of hemostasis and thrombosis, other groups have adapted this model to study genes that are associated with thrombocyte function and a few novel genes have also been identified. Furthermore, transgenic zebrafish with GFP-tagged thrombocytes have been developed which helped to study the production of thrombocytes and their precursors as well as their functional roles not only in hemostasis but also hematopoiesis. This paper integrates the information available on zebrafish thrombocyte function and its formation.

TERMINOLOGY OF PALEOZOIC PLACODERM FISHES (ANTIARCHI) EXOSKELETAL ELEMENTS

2021 ◽  
Vol 43 (2) ◽  
pp. 195-201
Author(s):  
Sergey Moloshnikov ◽  
Keyword(s):  
Anterior Part ◽  
Posterior Part ◽  
Shoulder Girdle ◽  
Russian Language ◽  
Postcranial Skeleton ◽  
Incorrect Conclusion ◽  
Similar Term ◽  
Early Vertebrates ◽  
Language Literature ◽  
Dorsal Scute

The terminology and morphology of plates of the posterior part of the antiarch head shield (Placodermi, Antiarchi) are discussed. The terms «zatilochnaya» and «bokovaya (kraevaya) zatilochnaya» was previously accepted in antiarch skulls and are suggested for use in Russian-language literature. These terms are more correct and clearly define a position and development of these plates in the head shield of antiarchs. The titles «zagrivkovaya (nuchalnaya)» and «bokovaya zagrivkovaya (paranuchalnaya)», recently applied to them in Russian-language literature may indicate a connection in development with an anterior part of a trunk. A similar term is used for acipenserid exoskeleton. The acipenserid «nuchalnaya kost’» is located posterior to the «verchnezatilochnaya» (after Gurtovoi), and embryonically developed in an anterior part of the trunk over basidorsals and bones of the shoulder girdle. The name «pervaya spinnaya plastinka» (first dorsal scute: after Hilton and others) is also use for this bone. The term «zagrivkovaya plastinka» is used in other vertebrate skeletons, for example, in turtles; this name denotes the unpaired element of a carapace (postcranial skeleton). Using the terms «zagrivkovaya (nuchalnaya)» and «bokovaya zagrivkovaya (paranuchalnaya)» in the morphology of antiarchs and other placoderms may lead confusion in the terminology of skeletal elements at early vertebrates, incorrect conclusion of their homology, structure and development of the head shield of these unusual fishes.

Vertebrate voyages

2019 ◽  
pp. 54-71
Author(s):  
Elisabeth A. Murray ◽  
Steven P. Wise ◽  
Mary K. L. Baldwin ◽  
Kim S. Graham
Keyword(s):  
Brain Area ◽  
Spatial Layouts ◽  
Early Vertebrates ◽  
The Brain

In this chapter, a rat charts a safe route to cheese; a woman misplaces her car; and one of your ancestors swims for its dinner. But mainly we consider the kinds of memories that evolved in early vertebrates. The brain of these ancestors included the hippocampus, a brain area crucial for memory. The hippocampus evolved to guide navigation, which came with a bonus: support for other memories, such as the sequence and timing of smells and sights. By combining these memories in various ways, vertebrates can construct a map of their world, including spatial layouts and the proximity of items; the order of items in a sequence; and the appearance of landscapes as viewed from various angles. The memories of events and contexts arise from the same source.

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