scholarly journals Phenotypic Variation Through Ontogeny: Thyroid Axis Disruption During Larval Development in the Frog Pleurodema borellii

2021 ◽  
Vol 9 ◽  
Author(s):  
Marissa Fabrezi ◽  
Julio César Cruz
Keyword(s):  
Thyroid Gland ◽  
Larval Development ◽  
Growth Rates ◽  
Phenotypic Variation ◽  
Musculoskeletal Tissues ◽  
Mesocosm Experiments ◽  
Baseline Information ◽  
Developmental Rates ◽  
Thyroid Axis ◽  
Late Exposure

Studies of the effects of thyroid hormones on larval development in the frog Xenopus spp. have provided baseline information to identify developmental constraints and elucidate genetic and hormonal mechanisms driving development, growth, and life history transitions. However, this knowledge requires data based on other anurans to complete a comprehensive approach to the understanding of larval developmental diversity and phenotypic variation through ontogeny. Mesocosm experiments provide realistic data about environmental conditions and timing; this information is useful to describe anuran larval development and/or analyze endocrine disruption. In this study, mesocosm experiments of the larval development of the frog Pleurodema borellii were conducted to explore the consequences of thyroid axis disruption; the sensitivity of tadpoles to the methimazole (2.66 mg/l) and thyroxine (T4) (1.66 μg/l) was compared. These concentrations were selected based on previous studies in Pleurodema borellii. We test the effects of methimazole and thyroxine on development in early exposure (from beginning of larval development) and late exposure, 18 days after hatching, with doses administered every 48 h. Tadpoles were evaluated 31 days after hatching. Methimazole caused moderate hypertrophy of the thyroid gland, alteration in the growth rates, differentiation without inhibition of development, and an increase of developmental variability. Thyroxine produced slight atrophy of the thyroid gland, accelerated growth rates and differentiation, and minor developmental variability. In tadpoles at stages previous to metamorphose, skull development (differentiation of olfactory capsules, appearance of dermal bones, and cartilage remodeling) seemed to be unaltered by the disruptors. Moreover, similar abnormal morphogenesis converged in specimens under methimazole and thyroxine exposures. Abnormalities occurred in pelvic and pectoral girdles, and vent tube, and could have been originated at the time of differentiation of musculoskeletal tissues of girdles. Our results indicate that premetamorphic stages (Gosner Stages 25–35) are sensitive to minimal thyroid axis disruption, which produces changes in developmental rates; these stages would also be critical for appendicular musculoskeletal morphogenesis to achieve the optimal condition to start metamorphosis.

The missing links: larval and post-larval development of the ascoglossan opisthobranch Elysia viridis

2000 ◽  
Vol 80 (6) ◽  
pp. 1087-1094 ◽  
Author(s):  
Cynthia D. Trowbridge
Keyword(s):  
Larval Development ◽  
Growth Rates ◽  
Shell Length ◽  
Larval Growth ◽  
Model Organism ◽  
Larval Life ◽  
Codium Fragile ◽  
Planktotrophic Larvae ◽  
Algal Diet ◽  
Better Than

The stenophagous ascoglossan (=sacoglossan) opisthobranch Elysia viridis has long been a model organism for the study of endosymbiosis or kleptoplasty as well as one of the few herbivores to consume the introduced green macroalga Codium fragile on European shores. Larval and post-larval dynamics of the ascoglossan were investigated. Planktotrophic larvae of E. viridis grew at 5–10 μm d−1 (shell length) at 15°C on a unicellular algal diet (the cryptophyte Rhodomonas baltica); larvae became competent one month post-hatching. Effective feeding and chloroplast acquisition typically started within 2–3 d of metamorphosis. Slugs grew about 8 mm in the first month of post-larval life. During this period, juveniles held in the light did not grow faster or survive better than conspecifics held in the dark; thus, functional kleptoplasty did not occur during first three weeks of benthic life. While larval growth rates and the nature of metamorphic cues are consistent with those of many other opisthobranch species with planktotrophic larvae, measures of post-larval growth—particularly as it pertains to kleptoplasty—is a new contribution to opisthobranch biology.

scholarly journals OctylPhenol (OP) Alone and in Combination with NonylPhenol (NP) Alters the Structure and the Function of Thyroid Gland of the Lizard Podarcis siculus

2021 ◽  
Vol 80 (3) ◽  
pp. 567-578 ◽  
Author(s):  
Rosaria Sciarrillo ◽  
Mariana Di Lorenzo ◽  
Salvatore Valiante ◽  
Luigi Rosati ◽  
Maria De Falco
Keyword(s):  
Thyroid Gland ◽  
Endocrine Disrupting Chemicals ◽  
Thyroid Stimulating Hormone ◽  
Control Group ◽  
Type Ii ◽  
Endocrine Disrupting ◽  
Pituitary Thyroid Axis ◽  
Podarcis Siculus ◽  
Thyroid Axis ◽  
By Products

Abstract Different environmental contaminants disturb the thyroid system at many levels. AlkylPhenols (APs), by-products of microbial degradation of AlkylPhenol Polyethoxylates (APEOs), constitute an important class of Endocrine Disrupting Chemicals (EDCs), the two most often used environmental APs being 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP). The purpose of the present study was to investigate the effects on the thyroid gland of the bioindicator Podarcis siculus of OP alone and in combination with NP. We used radioimmunoassay to determine their effects on plasma 3,3′,5-triiodo-L-thyronine (T3), 3,3′,5,5′-L-thyroxine (T4), thyroid-stimulating hormone (TSH), and thyrotropin-releasing hormone (TRH) levels in adult male lizards. We also investigated the impacts of AP treatments on hepatic 5′ORD (type II) deiodinase and hepatic content of T3 and T4. After OP and OP + NP administration, TRH levels increased, whereas TSH, T3, and T4 levels decreased. Lizards treated with OP and OP + NP had a higher concentration of T3 in the liver and 5′ORD (type II) activity, whereas T4 concentrations were lower than that observed in the control group. Moreover, histological examination showed that the volume of the thyroid follicles became smaller in treated lizards suggesting that that thyroid follicular epithelial cells were not functionally active following treatment. This data collectively suggest a severe interference with hypothalamus–pituitary–thyroid axis and a systemic imbalance of thyroid hormones. Graphic Abstract

scholarly journals Alterations of the thyroid structure and function in experimental hypopinealism

2011 ◽  
Vol 57 (2) ◽  
pp. 32-35
Author(s):  
L A Bondarenko ◽  
L Iu Sergienko ◽  
N N Sotnik ◽  
A N Cherevko
Keyword(s):  
Thyroid Gland ◽  
Structural Changes ◽  
Structure And Function ◽  
Initial Increase ◽  
Histological Structure ◽  
Pituitary Thyroid Axis ◽  
Thyroid Axis ◽  
And Function ◽  
Sexually Mature

The pituitary-thyroid axis of young sexually mature rabbits kept under a 24-hour daylight photoperiod was shown to undergo phase-modulated variations of hormonal activity with its initial increase (during the first month) and subsequent progressive decrease (within 2-5 months after the onset of exposure to light). These changes correlated with the time-dependent fall in the blood T3, T4, and TSH levels. Simultaneously, the animals developed pathological changes in the histological structure of the thyroid gland similar to those in patients with secondary or tertiary hypothyroidism. It is concluded that hormonal and structural changes in the thyroid gland during long-term hypopinealism should be regarded as an experimental model of hypothyroidism of neuroendocrine origin.

PARTIAL FAILURE OF ANTERIOR PITUITARY AND THYROID PRESENTING AS MYXOEDEMA

1975 ◽  
Vol 79 (4) ◽  
pp. 688-690
Author(s):  
A. D. Toft ◽  
W. J. Irvine
Keyword(s):  
Thyroid Gland ◽  
Anterior Pituitary ◽  
Clinical Presentation ◽  
Present Report ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Partial Failure ◽  
Impaired Function ◽  
Precise Evaluation ◽  
Thyroid Axis

ABSTRACT The development of a sensitive radioimmunoassay of plasma thyrotrophin (TSH) and the isolation and synthesis of thyrotrophin-releasing hormone (TRH) allows a precise evaluation of the disordered brain-thyroid axis. The present report describes a patient who presented with myxoedema due to partial failure of both the anterior pituitary and the thyroid gland. The degree of impaired function of either gland alone would not have caused her clinical presentation.

scholarly journals Ovarian growth during larval development of queen and worker of Apis mellifera (Hymenoptera: Apidae): a morphometric and histological study

2003 ◽  
Vol 63 (1) ◽  
pp. 121-127 ◽  
Author(s):  
R. D. Reginato ◽  
C. Cruz-Landim
Keyword(s):  
Weight Gain ◽  
Apis Mellifera ◽  
Larval Development ◽  
Growth Rates ◽  
Histological Study ◽  
Larval Instars ◽  
Ovarian Growth

The present work reports the differences between the ovarian grow in queen and worker larvae of A. mellifera, from the start of differential feeding. The observations made of the growth rates in larvae of both castes showed that the queen and worker larvae have the same rates of cephalic capsule growth from one instar to another but the weight gain is greater in queens. In the same way, the draw areas of ovaries of queens increase more and continuously, while from the 5th instar on the ovaries of workers decrease in size. The decrease is due to a loss of ovariole numbers that starts early in the worker larvae and increases in the 4th-5th instar. The ovarian shape in queens and workers became different in the last larval instars.

Larval and Early Post-Larval Development of Arctica Islandica

1982 ◽  
Vol 62 (4) ◽  
pp. 745-769 ◽  
Author(s):  
R. A. Lutz ◽  
R. Mann ◽  
J. G. Goodsell ◽  
M. Castagna
Keyword(s):  
Larval Development ◽  
Growth Rates ◽  
Larval Growth ◽  
Ammonium Hydroxide ◽  
Culture Conditions ◽  
Dilute Solution ◽  
Arctica Islandica ◽  
Larval Stages ◽  
Experimental Laboratory ◽  
Rearing Techniques

Mature eggs were stripped from ripe adult specimens of Arctica islandica and exposed to a dilute solution of ammonium hydroxide for various lengths of time before addition of stripped sperm. Larval and early post-larval stages were cultured under experimental laboratory conditions using standard bivalve rearing techniques. Larval cultures were maintained at various controlled temperatures ranging from 8·5 to 14·5 °C. Minimum time to settlement was 32 days at a temperature of approximately 13 °C; at temperatures between 8·5 and 10·0 °C, settlement was not observed until approximately 55 days after fertilization. Larval growth rates were significantly faster at temperatures between 11·0 and 145 °C than at temperatures between 8°C. Morphometry of the larval shell and morphology of the larval hinge apparatus were independent of larval growth rates and experimental culture conditions.

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