Comparative development and ocular histology between epigean and subterranean salamanders (Eurycea) from central Texas

The salamander clade Eurycea from the karst regions of central Texas provides an ideal platform for comparing divergent nervous and sensory systems since some species exhibit extreme phenotypes thought to be associated with inhabiting a subterranean environment, including highly reduced eyes, while others retain an ancestral ocular phenotype appropriate for life above ground. We describe ocular morphology, comparing three salamander species representing two phenotypes—the surface-dwelling Barton Springs salamander (E. sosorum) and San Marcos salamander (E. nana) and the obligate subterranean Texas blind salamander (E. rathbuni) - in terms of structure and size of their eyes. Eyes were examined using confocal microscopy and measurements were made using ImageJ. Statistical analysis of data was carried out using R. We also provide a developmental series and track eye development and immunolocalization of Pax6 in E. sosorum and E. rathbuni. Adult histology of the surface-dwelling San Marcos salamander (E. nana) shows similarities to E. sosorum. The eyes of adults of the epigean species E. nana and E. sosorum appear fully developed with all the histological features of a fully functional eye. In contrast, the eyes of E. rathbuni adults have fewer layers, lack lenses and other features associated with vision as has been reported previously. However, in early developmental stages eye morphology did not differ significantly between E. rathbuni and E. sosorum. Parallel development is observed between the two phenotypes in terms of morphology; however, Pax6 labeling seems to decrease in the latter stages of development in E.rathbuni. We test for immunolabeling of the visual pigment proteins opsin and rhodopsin and observe immunolocalization around photoreceptor disks in E. nana and E. sosorum, but not in the subterranean E. rathbuni. Our results from examining developing salamanders suggest a combination of underdevelopment and degeneration contribute to the reduced eyes of adult E. rathbuni.

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Divergent patterns of ocular development and gene expression in the evolution of a subterranean salamander

10.7287/peerj.preprints.27301 ◽

2018 ◽

Author(s):

Ruben U. Tovar ◽

Valentin Cantu ◽

Brian P. Fremaux ◽

Pedro Gonzalez ◽

Dana M. García

Keyword(s):

Developmental Stages ◽

Ocular Tissue ◽

Ocular Development ◽

Evolution And Development ◽

Extreme Phenotypes ◽

San Marcos ◽

Central Texas ◽

Lens Vesicle ◽

Surface Dwelling ◽

Salamander Species

Relatively few studies have focused on the evolution and development of divergent nervous systems. The salamander clade (Eurycea) from the karst regions of central Texas provide an ideal platform for comparing divergent nervous and sensory systems, since some species exhibit extreme phenotypes thought to be associated with inhabiting a subterranean environment, including highly reduced eyes. We describe ocular development and examine early ocular protein expression (Pax6 and Shh), comparing between two salamander species representing two phenotypes: the surface dwelling Barton Springs salamander (E. sosorum) and the obligate subterranean Texas blind salamander (E. rathbuni). Between the two species, similarities during the development of ocular tissue (e.g. optic cup and lens vesicle) were observed during embryogenesis. However, during late stage embryogenesis the two species display markedly different patterns of Pax6 localization, which parallel patterns previously reported in a cavefish. A lens vesicle was observed in E. rathbuniembryos at stage 40, yet the lens is absent in adults, suggesting the regression of the lens during ontogeny. We also include adult histology of the surface dwelling San Marcos salamander (E. nana) and note similarities to E. sosorum. Adult E. rathbunilack major histological features associated with vision; however, eye morphology did not differ significantly between E. rathbuniand E. sosorumin early developmental stages, suggesting a combination of underdevelopment and degeneration contribute to the reduced eyes of adult E. rathbuni.

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Divergent patterns of ocular development and gene expression in the evolution of a subterranean salamander

10.7287/peerj.preprints.27301v1 ◽

2018 ◽

Author(s):

Ruben U. Tovar ◽

Valentin Cantu ◽

Brian P. Fremaux ◽

Pedro Gonzalez ◽

Dana M. García

Keyword(s):

Developmental Stages ◽

Ocular Tissue ◽

Ocular Development ◽

Evolution And Development ◽

Extreme Phenotypes ◽

San Marcos ◽

Central Texas ◽

Lens Vesicle ◽

Surface Dwelling ◽

Salamander Species

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Reduced Oxygen as an Environmental Pressure in the Evolution of the Blind Mexican Cavefish

Diversity ◽

10.3390/d13010026 ◽

2021 ◽

Vol 13 (1) ◽

pp. 26

Author(s):

Tyler Boggs ◽

Joshua Gross

Keyword(s):

Potential Role ◽

Environmental Changes ◽

Environmental Stressors ◽

Environmental Features ◽

Extreme Phenotypes ◽

Lower Oxygen ◽

Surface Dwelling ◽

Subterranean Environment ◽

Limited Oxygen

Extreme environmental features can drive the evolution of extreme phenotypes. Over the course of evolution, certain environmental changes may be so drastic that they lead to extinction. Conversely, if an organism adapts to harsh environmental changes, the adaptations may permit expansion of a novel niche. The interaction between environmental stressors and adaptive changes is well-illustrated by the blind Mexican cavefish, Astyanaxmexicanus, which has recurrently adapted to the stark subterranean environment. The transition from terrestrial rivers and streams (occupied by extant surface morphs of the same species) to the cave has been accompanied by the resorption of eyes, diminished pigmentation and reduced metabolism in cave-dwelling morphs. The principal features of caves most often associated with evolution of these common cave features are the absence of light and limited nutrition. However, a putatively essential cave feature that has received less attention is the frequently low concentration of oxygen within natural karst environments. Here, we review the potential role of limited oxygen as a critical environmental feature of caves in the Sierra de El Abra. Additionally, we review evidence that Astyanax cavefish may have evolved adaptive features enabling them to thrive in lower oxygen compared to their surface-dwelling counterparts.

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Correlated Studies of Cellular Interactions Using TEM, Freeze Etching, and SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010005161x ◽

1974 ◽

Vol 32 ◽

pp. 320-321

Author(s):

J. P. Revel

Keyword(s):

Developmental Stages ◽

Three Dimensional ◽

Cell Movement ◽

Cellular Interactions ◽

Serial Sections ◽

Cell Sheets ◽

Freeze Etching ◽

Early Developmental

Movement of individual cells or of cell sheets and complex patterns of folding play a prominent role in the early developmental stages of the embryo. Our understanding of these processes is based on three- dimensional reconstructions laboriously prepared from serial sections, and from autoradiographic and other studies. Many concepts have also evolved from extrapolation of investigations of cell movement carried out in vitro. The scanning electron microscope now allows us to examine some of these events in situ. It is possible to prepare dissections of embryos and even of tissues of adult animals which reveal existing relationships between various structures more readily than used to be possible vithout an SEM.

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Review of early developmental stages of trilobites and agnostids from the Barrandian area (Czech Republic)

Journal of the National Museum (Prague), Natural History Series ◽

10.2478/jzh-2018-0006 ◽

2017 ◽

Vol 186 (1) ◽

pp. 103-112

Author(s):

Lukáš Laibl ◽

Oldřich Fatka

Keyword(s):

Czech Republic ◽

Developmental Stages ◽

History Of Research ◽

Early Developmental Stages ◽

History Of ◽

Barrandian Area ◽

Early Developmental

This contribution briefly summarizes the history of research, modes of preservation and stratigraphic distribution of 51 trilobite and five agnostid taxa from the Barrandian area, for which the early developmental stages have been described.

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The Effect of an Anthropogenic Magnetic Field on the Early Developmental Stages of Fishes—A Review

International Journal of Molecular Sciences ◽

10.3390/ijms22031210 ◽

2021 ◽

Vol 22 (3) ◽

pp. 1210

Author(s):

Krzysztof Formicki ◽

Agata Korzelecka-Orkisz ◽

Adam Tański

Keyword(s):

Magnetic Fields ◽

Developmental Stages ◽

Negative Influence ◽

Pigment Cells ◽

Egg Activation ◽

Industrial Equipment ◽

Positive Effects ◽

Early Developmental Stages ◽

Species Specific ◽

Early Developmental

The number of sources of anthropogenic magnetic and electromagnetic fields generated by various underwater facilities, industrial equipment, and transferring devices in aquatic environment is increasing. These have an effect on an array of fish life processes, but especially the early developmental stages. The magnitude of these effects depends on field strength and time of exposure and is species-specific. We review studies on the effect of magnetic fields on the course of embryogenesis, with special reference to survival, the size of the embryos, embryonic motor function, changes in pigment cells, respiration hatching, and directional reactions. We also describe the effect of magnetic fields on sperm motility and egg activation. Magnetic fields can exert positive effects, as in the case of the considerable extension of sperm capability of activation, or have a negative influence in the form of a disturbance in heart rate or developmental instability in inner ear organs.

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Wnt/β-catenin Pathway-Mediated PPARδ Expression during Embryonic Development Differentiation and Disease

International Journal of Molecular Sciences ◽

10.3390/ijms22041854 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1854

Author(s):

Tabinda Sidrat ◽

Zia-Ur Rehman ◽

Myeong-Don Joo ◽

Kyeong-Lim Lee ◽

Il-Keun Kong

Keyword(s):

Embryonic Development ◽

Transcriptional Activation ◽

Target Gene ◽

Developmental Stages ◽

Embryonic Stem ◽

Hereditary Diseases ◽

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor ◽

Stem Cell Regulation ◽

Early Developmental

The Wnt/β-catenin signaling pathway plays a crucial role in early embryonic development. Wnt/β-catenin signaling is a major regulator of cell proliferation and keeps embryonic stem cells (ESCs) in the pluripotent state. Dysregulation of Wnt signaling in the early developmental stages causes several hereditary diseases that lead to embryonic abnormalities. Several other signaling molecules are directly or indirectly activated in response to Wnt/β-catenin stimulation. The crosstalk of these signaling factors either synergizes or opposes the transcriptional activation of β-catenin/Tcf4-mediated target gene expression. Recently, the crosstalk between the peroxisome proliferator-activated receptor delta (PPARδ), which belongs to the steroid superfamily, and Wnt/β-catenin signaling has been reported to take place during several aspects of embryonic development. However, numerous questions need to be answered regarding the function and regulation of PPARδ in coordination with the Wnt/β-catenin pathway. Here, we have summarized the functional activation of the PPARδ in co-ordination with the Wnt/β-catenin pathway during the regulation of several aspects of embryonic development, stem cell regulation and maintenance, as well as during the progression of several metabolic disorders.

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Mitochondrial Processes during Early Development of Dictyostelium discoideum: From Bioenergetic to Proteomic Studies

Genes ◽

10.3390/genes12050638 ◽

2021 ◽

Vol 12 (5) ◽

pp. 638

Author(s):

Monika Mazur ◽

Daria Wojciechowska ◽

Ewa Sitkiewicz ◽

Agata Malinowska ◽

Bianka Świderska ◽

...

Keyword(s):

Life Cycle ◽

Developmental Stages ◽

Coupling Efficiency ◽

Slime Mold ◽

Intact Cells ◽

Life Cycle Stages ◽

Early Developmental Stages ◽

Proteomic Study ◽

And Function ◽

Early Developmental

The slime mold Dictyostelium discoideum’s life cycle includes different unicellular and multicellular stages that provide a convenient model for research concerning intracellular and intercellular mechanisms influencing mitochondria’s structure and function. We aim to determine the differences between the mitochondria isolated from the slime mold regarding its early developmental stages induced by starvation, namely the unicellular (U), aggregation (A) and streams (S) stages, at the bioenergetic and proteome levels. We measured the oxygen consumption of intact cells using the Clarke electrode and observed a distinct decrease in mitochondrial coupling capacity for stage S cells and a decrease in mitochondrial coupling efficiency for stage A and S cells. We also found changes in spare respiratory capacity. We performed a wide comparative proteomic study. During the transition from the unicellular stage to the multicellular stage, important proteomic differences occurred in stages A and S relating to the proteins of the main mitochondrial functional groups, showing characteristic tendencies that could be associated with their ongoing adaptation to starvation following cell reprogramming during the switch to gluconeogenesis. We suggest that the main mitochondrial processes are downregulated during the early developmental stages, although this needs to be verified by extending analogous studies to the next slime mold life cycle stages.

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