Follicle Lumen Research Articles

Reduction in reproductive activity from degeneration of testicular follicles in Megapitaria squalida (Mollusca: Bivalvia) exposed to metal pollution in the Gulf of California

Over a reproductive cycle, the prevalence and intensity of degeneration of testicular follicles in Megapitaria squalida collected from the mining port of Santa Rosalia (a highly metal-polluted area), and San Lucas (a less polluted site), Gulf of California, Mexico, were evaluated. At San Lucas, most individuals had a typical testicular structure, and degeneration of testicular follicles was present in 9.5 % of spawning organisms. In contrast, at Santa Rosalia, 68 % of males, mainly in the ripe stage, had testicular degeneration (72 % severe intensity, mostly in medium and large-sized). Degeneration was characterized by intense hemocyte infiltration, identified as dense masses with numerous melanized cells in the follicle lumen. In both sites, males with testicular follicles degeneration had a lower condition index compared to males without degeneration. Degeneration of testicular follicles before spawning compromises and decreases the reproductive activity of M. squalida males at Santa Rosalia, which may ultimately affect the population sustainability.

OR14-01 Contact Between Thyroglobulin Opposite Domains Assists Its Upstream Regions In Intracellular Trafficking For Thyroid Hormonogenesis

Abstract Disclosure: C.E. Citterio: None. K. Kim: None. B. Rajesh: None. K. Pena: None. O.B. Clarke: None. P. Arvan: None. Thyroglobulin (Tg), must be released into the lumen of thyroid follicles to facilitate thyroid hormone synthesis. The Tg primary sequence (∼2,760 amino acids) includes regions I, II, III, as well as ∼570 residues of cholinesterase-like (ChEL) domain (which bears 47% similarity to acetylcholinesterase), folded as a globular protein with multiple contacts between different Tg regions. The ChEL domain is reported to function as an intramolecular chaperone assisting Tg region I. This function cannot be replaced by acetylcholinesterase or neuroligins, indicating a unique function of Tg ChEL. However, the specific amino acids of ChEL neighboring upstream Tg regions have only recently been identified, and the key functional residues for Tg folding remain unknown. Here, we’ve combined structural analyses with functional characterization of recombinant Tg expressed in cell culture. We’ve identified hTg-ChEL K2223 and W2222 as amino acids that exhibit the closest physical proximity with Tg region I. By cryo-EM of Tg (both human and bovine), Tg-K2223 and Tg-W2222 reside only ∼4.5Å from Tg-W1089 and Tg-P1098, respectively, both of which are located in the Tg 1-9 repeat within region I. We’ve employed site-directed mutagenesis to determine the impact of these contacts by studying both full length Tg as well as Tg expressed in a two-component system in cultured cells. We find that secretory ChEL-K2223E and ChEL-W2222A behave much like WT secretory ChEL; both mutants are reasonably well expressed and secreted efficiently. However, when secretory ChEL was co-expressed with Tg region I-II-III lacking its own ChEL domain, region I-II-III secretion could be rescued in the presence of WT secretory ChEL, but not by co-expression of either ChEL-K2223E or ChEL-W2222A. In context of a single contiguous full length Tg, both expression and secretion of Tg-K2223E and Tg-W2222A were significantly diminished. These results highlight two residues (K2223 and W2222) that are not needed for the independent folding (or endoplasmic reticulum export) of the Tg ChEL domain, but are key residues for contacting Tg region I, thereby offering the overall Tg structure a great increase in conformational stability, which is needed to satisfy endoplasmic reticulum quality control requirements for intracellular protein trafficking. These findings point to the possibility that mutations altering regional contacts within the Tg structure could contribute to the molecular pathogenesis of congenital hypothyroidism. Presentation: Friday, June 16, 2023

Investigations on Primary Cilia of Nthy-ori 3-1 Cells upon Cysteine Cathepsin Inhibition or Thyrotropin Stimulation.

In the thyroid gland, cysteine cathepsins are secreted upon thyrotropin stimulation for thyroglobulin processing, and they are present at the primary cilia of thyroid epithelial cells. Treatment with protease inhibitors resulted in the loss of cilia from rodent thyrocytes and caused redistribution of the thyroid co-regulating G protein-coupled receptor Taar1 to the endoplasmic reticulum. These findings suggest that ciliary cysteine cathepsins are important to maintain sensory and signaling properties for the proper regulation and homeostasis of thyroid follicles. Therefore, it is important to better understand how cilia structure and frequencies are maintained in human thyroid epithelial cells. Hence, we aimed to investigate the potential role of cysteine cathepsins for the maintenance of primary cilia in the normal human Nthy-ori 3-1 thyroid cell line. This was approached by determining cilia lengths and frequencies in cysteine peptidase inhibition conditions in Nthy-ori 3-1 cell cultures. Cilia lengths were shortened upon 5 h of cysteine peptidase inhibition with cell-impermeable E64. Likewise, cilia lengths and frequencies were decreased upon additional overnight treatment with the cysteine peptidase-targeting, activity-based probe DCG-04. The results suggest that cysteine cathepsin activity is required for the maintenance of the cellular protrusions not only in rodents, but also in human thyrocytes. Hence, thyrotropin stimulation was used to simulate physiological conditions that eventually lead to cathepsin-mediated thyroglobulin proteolysis, which is initiated in the thyroid follicle lumen. Immunoblotting revealed that thyrotropin stimulation conditions result in the secretion of little procathepsin L and some pro- and mature cathepsin S but no cathepsin B from the human Nthy-ori 3-1 cells. Unexpectedly, however, 24 h incubation periods with thyrotropin shortened the cilia although higher amounts of cysteine cathepsins were present in the conditioned media. These data point to the necessity of further studies to delineate which of the cysteine cathepsins plays the most prominent role in cilia shortening and/or elongation. Collectively, the results of our study provide corroboration for the hypothesis of thyroid autoregulation by local mechanisms that our group previously proposed.

Selenium, Iodine and Iron–Essential Trace Elements for Thyroid Hormone Synthesis and Metabolism

The adequate availability and metabolism of three essential trace elements, iodine, selenium and iron, provide the basic requirements for the function and action of the thyroid hormone system in humans, vertebrate animals and their evolutionary precursors. Selenocysteine-containing proteins convey both cellular protection along with H2O2-dependent biosynthesis and the deiodinase-mediated (in-)activation of thyroid hormones, which is critical for their receptor-mediated mechanism of cellular action. Disbalances between the thyroidal content of these elements challenge the negative feedback regulation of the hypothalamus-pituitary-thyroid periphery axis, causing or facilitating common diseases related to disturbed thyroid hormone status such as autoimmune thyroid disease and metabolic disorders. Iodide is accumulated by the sodium-iodide-symporter NIS, and oxidized and incorporated into thyroglobulin by the hemoprotein thyroperoxidase, which requires local H2O2 as cofactor. The latter is generated by the dual oxidase system organized as 'thyroxisome' at the surface of the apical membrane facing the colloidal lumen of the thyroid follicles. Various selenoproteins expressed in thyrocytes defend the follicular structure and function against life-long exposure to H2O2 and reactive oxygen species derived therefrom. The pituitary hormone thyrotropin (TSH) stimulates all processes required for thyroid hormone synthesis and secretion and regulates thyrocyte growth, differentiation and function. Worldwide deficiencies of nutritional iodine, selenium and iron supply and the resulting endemic diseases are preventable with educational, societal and political measures.

Biochemical Changes of Mancozeb-Induced Alternations in Testes and Thyroid gland of Male Albino Rats

Mancozeb manganese ethylenebis dithiocarbamate polymeric complex – with zinc salts is a very important protective non-systemicfungicide, classified as an ethylenebisdithiocarbamate fungicide. It is used to control fungal diseases for a wide variety of crops because its broad-spectrum fungicidal effects and high compatibility with agrochemicals. The objective of this study was to investigate the effects of the fungicide mancozeb at different doses on some biochemical parameters, reproductive performance and histological changes in testes and thyroid gland. The low dose equal 1/7 of LD50 manc-d1 and high dose equal 1/3.5 of LD50 manc-d1. Doses of mancozeb (manc-d1 and manc-d2) adjusted according to rat's body weights. The results showed that mancozeb significantly (P<0.05) decreased plasma testosterone level, sperm count, viability, motility, and significantly (P<0.05) increased abnormal sperms, altered acrosome and abnormal DNA. Treatment of rats with manc-d1 and manc-d2 significantly (P<0.05) decreased T3. Also, T4 significantly (P<0.05) decreased in the group treated with manc-d2. Treatment of rats with manc-d1 and manc-d2 significantly (P<0.05) increased TSH. Furthermore, the histological investigation revealed that exposure to mancozeb reduced number of mature spermatozoa, necrosis and basal vacuoles observed in some tubules. On the other hand, mancozeb reduce colloid in most follicles resulting in desquamation of the follicular epithelium into the lumen of the thyroid follicles. In conclusion, despite mancozeb exhibit low acute toxicity, it has been shown to cause detrimental effects on reproduction, thyroid gland and its secretion. For this reason, it should be necessary to be careful when using mancozeb in agricultural areas and should take precautions.

Defective Thyroglobulin: Cell Biology of Disease.

The primary functional units of the thyroid gland are follicles of various sizes comprised of a monolayer of epithelial cells (thyrocytes) surrounding an apical extracellular cavity known as the follicle lumen. In the normal thyroid gland, the follicle lumen is filled with secreted protein (referred to as colloid), comprised nearly exclusively of thyroglobulin with a half-life ranging from days to weeks. At the cellular boundary of the follicle lumen, secreted thyroglobulin becomes iodinated, resulting from the coordinated activities of enzymes localized to the thyrocyte apical plasma membrane. Thyroglobulin appearance in evolution is essentially synchronous with the appearance of the follicular architecture of the vertebrate thyroid gland. Thyroglobulin is the most highly expressed thyroid gene and represents the most abundantly expressed thyroid protein. Wildtype thyroglobulin protein is a large and complex glycoprotein that folds in the endoplasmic reticulum, leading to homodimerization and export via the classical secretory pathway to the follicle lumen. However, of the hundreds of human thyroglobulin genetic variants, most exhibit increased susceptibility to misfolding with defective export from the endoplasmic reticulum, triggering hypothyroidism as well as thyroidal endoplasmic reticulum stress. The human disease of hypothyroidism with defective thyroglobulin (either homozygous, or compound heterozygous) can be experimentally modeled in thyrocyte cell culture, or in whole animals, such as mice that are readily amenable to genetic manipulation. From a combination of approaches, it can be demonstrated that in the setting of thyroglobulin misfolding, thyrocytes under chronic continuous ER stress exhibit increased susceptibility to cell death, with interesting cell biological and pathophysiological consequences.

OR11-1 Thyroglobulin Structural Requirements in Protein Trafficking for Thyroid Hormonogenesis

Abstract In vertebrates, thyroglobulin (Tg) is secreted into the lumen of thyroid follicles to enable its iodination for the synthesis of thyroid hormone — defective Tg secretion causes hypothyroidism. A defining step in Tg secretion is export from the endoplasmic reticulum (ER), but Tg structural features needed to meet ER quality control requirements remain poorly defined. Tg primary structure is composed of Regions I, II, III, and ChEL, each engaged in intradomain disuflide bonding. Two major surprises that have recently emerged from the visualization of bovine Tg 3D-structure by cryoEM include the first identified long-range disulfide bond (C408-C608), which appears to tether a boundary separating two halves of region I, as well as the apparent absence of an evolutionarily conserved disulfide bond between C2444 and C2455 in the ChEL domain, which is known to support folding stability of region I. To understand the cell biological importance of these findings, we employed site-directed mutagenesis to determine the impact of these structural features in protein export of recombinant Tg expressed in cultured cells. To our surprise, we found that mutation of either a single Cys residue or both cysteines that contribute to the C408-C608 disulfide bridge had no discernible impact on the efficiency of Tg export. These data strongly suggest that the proximity of the two-halves of region I in the final Tg structure may be achieved by protein folding of individual repeating units of region I that must take place independently of (and thus presumably prior to) the formation of this interesting long-range disulfide bond. As ChEL supports Tg region I folding stability, we turned attention to the apparent absence of the C-2444-C2455 disulfide, which is one of the three disulfide bonds that had been thought to exist in every member of the large Cholinesterase-Like gene superfamily. Reported detection of this disulfide within human Tg, but lack of detection in bovine Tg, means either that this bond is 'structurally optional', or that this surface disulfide bond might have been broken by radiolysis under the X-ray beam used for cryoEM. Unequivocally, we found that mutagenesis of either C2444, C2455, or both, blocks Tg secretion and causes a pattern of intracellular misfolding consistent with incomplete Tg compaction indicative of lack of maturation of region I. Moreover, we found that disruption of these same residues causes misfolding and blocks secretion of an expressed isolated secretory ChEL domain, or acetylcholinesterase itself. Loss of the C2444-C2455 disulfide bridge behaves similarly to the defective folding observed in the mutant Tg encoded within cog/cog mice and rdw/rdw rats, whereas no pathogenic mutations have been reported affecting the long-range disulfide in Tg region I. Together, these results highlight the importance of ChEL domain structure in the maturation and secretion of Tg. Presentation: Sunday, June 12, 2022 11:00 a.m. - 11:15 a.m.

Comparison of Thyroglobulin Levels among Different Ages, Gender, and Grades of Goiter in Patients with Simple Diffuse Goiter

Background: Simple diffuse goiter (SDG) which is also known as endemic goiter usually occurs in a large number of certain populations. Serum thyroglobulin (TG) is a thyroid-specific glycoprotein, that serves as the source for thyroxine (T4) as well as triiodothyronine (T3) production within the lumen of thyroid follicles. Serum thyroglobulin and urinary iodine concentration are considered the most potent indicators of iodine status and thyroid functions as thyroid volume, thyroid nodularity, or iodine excretion have close associations to serum TG. Aim of the study: The aim of the study was to observe the association of serum thyroglobulin with different ages, gender, and grades of goiter in patients with simple diffuse goiter. Methods: This single-center observational study was conducted at the Department of Endocrinology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka Bangladesh during the period from May 2014 to March 2016. The targeted sample size of this study was between 39 and 90 and the final sample size was determined as 87. A purposive sampling technique was used to select 87 patients with simple diffuse goiter attending the outpatient department of the study hospital. All data were processed, analyzed, and disseminated by using MS Office and SPSS programs as per necessity. Results: The lowest level of serum thyroglobulin (ng/mL) was found in the age group of 12-16 years (6.0±4.5 ng/mL) where the mean (±SD) age was 23.97±6.83 years. The mean (±SD) S. TG (ng/mL) levels in the male and female patients were 5.76 ± 5.72 and 11.60 ± 13.50 respectively. The mean (±SD) S. TG (ng/mL) levels among the grade I and II patients were 6.79±4.33 and 11.67±13.69 respectively. Overall, S. TG had no significant correlations with various factors like age gender, and goiter grades. According to the Pearson’s or Spearman analysis in assessing the correlations, with serum thyroglobulin levels, the P values were found 0.813, 0.294, and 0.319 against age, gender, and goiter grades. Conclusion: Serum thyroglobulin has not any statistically significant correlation with age, gender, or grades of goiter in patients with simple diffuse goiter.

Pelodera strongyloides in the critically endangered Apennine brown bear (Ursus arctos marsicanus)

Skin biopsies from 20 Apennine brown bears (Ursus arctos marsicanus), 17 of which displaying skin lesions, were investigated by histopathology.Different degrees of dermatitis characterized by folliculitis and furunculosis accompanied by epidermal hyperplasia and epidermal and follicular hyperkeratosis were detected. In the most severe lesions, the superimposition of traumatic wounds, probably self-induced by scratching, was observed. In 8 out of 17 (47.0%) affected bears, cross- and longitudinally-sectioned nematode larvae were present within the lumen of hair follicles, whose localization and morphological characteristics were consistent with Pelodera strongyloides.P. strongyloides is a free-living saprophytic nematode whose third-stage larvae can invade the skin causing pruritic dermatitis in several mammalian species. This is the first report of Pelodera infection in the brown bear. Although capable of causing primary dermatitis, the finding of Pelodera is not sufficient to conclude that it is the cause of the lesions observed in bears. Nevertheless, the high prevalence of the infection is indicative of a diffuse phenomenon that requires further specific investigations given the interest and conservational relevance of this relict bear population.

XB130 Plays an Essential Role in Folliculogenesis Through Mediating Interactions Between Microfilament and Microtubule Systems in Thyrocytes.

Background: XB130 (actin filament-associated protein 1-like 2, AFAP1L2) is a thyroid-abundant adaptor/scaffold protein. Xb130-/- mice exhibit transient growth retardation postnatally due to congenital hypothyroidism with diminished thyroglobulin iodination and release at both embryonic and early postnatal stages due to disorganized thyroid apical membrane structure and function. We hypothesized that XB130 is crucial for polarity and folliculogenesis by mediating proper cytoskeletal structure and function in thyrocytes. Methods: Primary thyrocytes isolated from thyroid glands of Xb130-/- mice and their wild-type littermates at postnatal week 2 were cultured in 10% Matrigel for different time periods. Folliculogenesis was studied with immunofluorescence staining, followed by confocal microscopy. Cells were also transfected to express human XB130 fused Green Fluorescent Protein (XB130-GFP) or Green Fluorescent Protein (GFP) only before morphological analysis. Cytoskeletal structures from embryo and postnatal thyroid glands were also studied. Results: In three-dimensional cultures of thyrocytes, XB130, aligned with actin filaments, participated in defining the site of apical membrane formation and coalescence to form a thyroid follicle lumen. Xb130-/- thyrocytes displayed delayed folliculogenesis, reduced recruitment of a microtubule (MT)-associated proteins, and disorganized acetylated tubulin under the apical membrane, resulting in delayed folliculogenesis with reduced efficiency in formation of the thyroid follicle lumen. Conclusions: XB130 critically regulates thyrocyte polarization by functioning as a link between the actin filament cortex and MT network at the apical membrane of thyrocytes. Defects of adaptor scaffold proteins may affect cellular polarity and cytoskeletal structure and function and result in disorders of epithelial function, such as congenital hypothyroidism.

The structure of natively iodinated bovine thyroglobulin.

Thyroglobulin is a homodimeric glycoprotein that is essential for the generation of thyroid hormones in vertebrates. Upon secretion into the lumen of follicles in the thyroid gland, tyrosine residues within the protein become iodinated to produce monoiodotyrosine (MIT) and diiodotyrosine (DIT). A subset of evolutionarily conserved pairs of DIT (and MIT) residues can then engage in oxidative coupling reactions that yield either thyroxine (T4; produced from coupling of a DIT `acceptor' with a DIT `donor') or triiodothyronine (T3; produced from coupling of a DIT acceptor with an MIT donor). Although multiple iodotyrosine residues have been identified as potential donors and acceptors, the specificity and structural context of the pairings (i.e. which donor is paired with which acceptor) have remained unclear. Here, single-particle cryogenic electron microscopy (cryoEM) was used to generate a high-resolution reconstruction of bovine thyroglobulin (2.3 Å resolution in the core region and 2.6 Å overall), allowing the structural characterization of two post-reaction acceptor-donor pairs as well as tyrosine residues modified as MIT and DIT. A substantial spatial separation between donor Tyr149 and acceptor Tyr24 was observed, suggesting that for thyroxine synthesis significant peptide motion is required for coupling at the evolutionarily conserved thyroglobulin amino-terminus.

Trace Amine-Associated Receptor 1 Trafficking to Cilia of Thyroid Epithelial Cells.

Trace amine-associated receptor 1 (rodent Taar1/human TAAR1) is a G protein-coupled receptor that is mainly recognized for its functions in neuromodulation. Previous in vitro studies suggested that Taar1 may signal from intracellular compartments. However, we have shown Taar1 to localize apically and on ciliary extensions in rodent thyrocytes, suggesting that at least in the thyroid, Taar1 may signal from the cilia at the apical plasma membrane domain of thyrocytes in situ, where it is exposed to the content of the follicle lumen containing putative Taar1 ligands. This study was designed to explore mouse Taar1 (mTaar1) trafficking, heterologously expressed in human and rat thyroid cell lines in order to establish an in vitro system in which Taar1 signaling from the cell surface can be studied in future. The results showed that chimeric mTaar1-EGFP traffics to the apical cell surface and localizes particularly to spherical structures of polarized thyroid cells, procilia, and primary cilia upon serum-starvation. Moreover, mTaar1-EGFP appears to form high molecular mass forms, possibly homodimers and tetramers, in stably expressing human thyroid cell lines. However, only monomeric mTaar1-EGFP was cell surface biotinylated in polarized human thyrocytes. In polarized rat thyrocytes, mTaar1-EGFP is retained in the endoplasmic reticulum, while cilia were reached by mTaar1-EGFP transiently co-expressed in combination with an HA-tagged construct of the related mTaar5. We conclude that Taar1 trafficking to cilia depends on their integrity. The results further suggest that an in vitro cell model was established that recapitulates Taar1 trafficking in thyrocytes in situ, in principle, and will enable studying Taar1 signaling in future, thus extending our general understanding of its potential significance for thyroid autoregulation.

Thyroid hormone synthesis continues despite biallelic thyroglobulin mutation with cell death.

Complete absence of thyroid hormone is incompatible with life in vertebrates. Thyroxine is synthesized within thyroid follicles upon iodination of thyroglobulin conveyed from the endoplasmic reticulum (ER), via the Golgi complex, to the extracellular follicular lumen. In congenital hypothyroidism from biallelic thyroglobulin mutation, thyroglobulin is misfolded and cannot advance from the ER, eliminating its secretion and triggering ER stress. Nevertheless, untreated patients somehow continue to synthesize sufficient thyroxine to yield measurable serum levels that sustain life. Here, we demonstrate that TGW2346R/W2346R humans, TGcog/cog mice, and TGrdw/rdw rats exhibited no detectable ER export of thyroglobulin, accompanied by severe thyroidal ER stress and thyroid cell death. Nevertheless, thyroxine was synthesized, and brief treatment of TGrdw/rdw rats with antithyroid drug was lethal to the animals. When untreated, remarkably, thyroxine was synthesized on the mutant thyroglobulin protein, delivered via dead thyrocytes that decompose within the follicle lumen, where they were iodinated and cannibalized by surrounding live thyrocytes. As the animals continued to grow goiters, circulating thyroxine increased. However, when TGrdw/rdw rats age, they cannot sustain goiter growth that provided the dying cells needed for ongoing thyroxine synthesis, resulting in profound hypothyroidism. These results establish a disease mechanism wherein dead thyrocytes support organismal survival.

Procathepsin V Is Secreted in a TSH Regulated Manner from Human Thyroid Epithelial Cells and Is Accessible to an Activity-Based Probe.

The significance of cysteine cathepsins for the liberation of thyroid hormones from the precursor thyroglobulin was previously shown by in vivo and in vitro studies. Cathepsin L is most important for thyroglobulin processing in mice. The present study aims at specifying the possible contribution of its closest relative, cysteine cathepsin L2/V, to thyroid function. Immunofluorescence analysis on normal human thyroid tissue revealed its predominant localization at the apical plasma membrane of thyrocytes and within the follicle lumen, indicating the secretion of cathepsin V and extracellular tasks rather than its acting within endo-lysosomes. To explore the trafficking pathways of cathepsin V in more detail, a chimeric protein consisting of human cathepsin V tagged with green fluorescent protein (GFP) was stably expressed in the Nthy-ori 3-1 thyroid epithelial cell line. Colocalization studies with compartment-specific markers and analyses of post-translational modifications revealed that the chimeric protein was sorted into the lumen of the endoplasmic reticulum and subsequently transported to the Golgi apparatus, while being N-glycosylated. Immunoblotting showed that the chimeric protein reached endo-lysosomes and it became secreted from the transduced cells. Astonishingly, thyroid stimulating hormone (TSH)-induced secretion of GFP-tagged cathepsin V occurred as the proform, suggesting that TSH upregulates its transport to the plasma membrane before it reaches endo-lysosomes for maturation. The proform of cathepsin V was found to be reactive with the activity-based probe DCG-04, suggesting that it possesses catalytic activity. We propose that TSH-stimulated secretion of procathepsin V is the default pathway in the thyroid to enable its contribution to thyroglobulin processing by extracellular means.

Auto-Regulation of the Thyroid Gland Beyond Classical Pathways.

This mini-review asks how self-regulation of the thyroid gland is realized at the cellular and molecular levels by canonical and non-canonical means. Canonical pathways of thyroid regulation comprise thyroid stimulating hormone-triggered receptor signaling. As part of non-canonical regulation, we hypothesized an interplay between protease-mediated thyroglobulin processing and thyroid hormone release into the circulation by means of thyroid hormone transporters like Mct8. We proposed a sensing mechanism by different thyroid hormone transporters, present in specific subcellular locations of thyroid epithelial cells, selectively monitoring individual steps of thyroglobulin processing, and thus, the cellular thyroid hormone status. Indeed, we found that proteases and thyroid hormone transporters are functionally inter-connected, however, in a counter-intuitive manner fostering self-thyrotoxicity in particular in Mct8- and/or Mct10-deficient mice. Furthermore, the possible role of the G protein-coupled receptor Taar1 is discussed, because we detected Taar1 at cilia of the apical plasma membrane of thyrocytes in vitro and in situ. Eventually, through pheno-typing Taar1-deficient mice, we identified a co-regulatory role of Taar1 and the thyroid stimulating hormone receptors. Recently, we showed that inhibition of thyroglobulin-processing enzymes results in disappearance of cilia from the apical pole of thyrocytes, while Taar1 is re-located to the endoplasmic reticulum. This pathway features a connection between thyrotropin-stimulated secretion of proteases into the thyroid follicle lumen and substrate-mediated self-assisted control of initially peri-cellular thyroglobulin processing, before its reinternalization by endocytosis, followed by extensive endo-lysosomal liberation of thyroid hormones, which are then released from thyroid follicles by means of thyroid hormone transporters.

Pixelar index: a new quantitative approach for the assessment of reproductive condition in the purple sea urchin, Paracentrotus lividus, by image analysis

The assessment of the gametogenic cycle and gonadal stage in commercial species relevant for shellfisheries and aquaculture is essential for the optimal management of the resource. However, currently this assessment frequently relies on the subjective classification of the specimens into discrete stages of development, with a strong dependence on the observer. The present study developed a quantitative, continuous, and observer-independent method for the analysis of the gonadal stage of the edible sea urchin, Paracentrotus lividus. This new approach takes advantage of image analysis to assess in histological preparations of the gonads the cellular growth of germ cells and calculate a Pixelar index (PI). The PI can be calculated taking into account just the proportion of the area covered by germinal vs somatic cells in the gonad follicle (PI1) or computing also the empty space created in the follicle lumen after spawning (PI2), which reduces the variability of the index. In both cases, PI showed a bell-shaped dependence on the traditional gametogenic stage that could be fitted to a Gaussian model, providing a tool that can be used for the quantitative evaluation of effects on sea urchin gonads of any kind of environmental factors, from aquaculture rearing conditions to ecotoxicological effects of pollutants on wild stocks. Further assessment of intraindividual—both among gonads and within gonads—variability in this index will be necessary for refinement of this quantitative tool.

Pinopsin and photoreception in the pineal organ of the domestic turkey during post-hatching development

The avian pineal organ is photosensitive because of the presence of photopigments, of which pinopsin seems to be one of the most important. This organ is subject to far-reaching changes during post-hatching development, but evidence regarding pinopsin presence and direct photoreception during this time is lacking. This study was carried out to demonstrate the following: 1) the structures showing immunoreactivity to pinopsin in the turkey pineal organ, 2) the changes of these structures during development, 3) the pinopsin localization in pinealocytes in monolayer cultures, and 4) the role of direct photoreception in the regulation of melatonin secretion in pineal organs in adult turkeys. Pinopsin immunoreactivity was localized in the apical extensions of columnar cells limiting the follicular lumen, in fiber-like structures located between columnar cells in the inner part of follicle wall, in string-shapes or small spherical structures distributed in the outer part of follicle wall and in amorphous material inside the follicle lumen. In young birds, immunoreactivity was also sporadically noted in cell bodies of rudimentary receptor pinealocytes. The distribution of pinopsin showed prominent age-dependent changes, including a subsequent increase in pinopsin-positive structures in the outer part of the follicle wall and a prominent reduction in the number and size of positive apical extensions in 40- and 56-week-old turkeys. These data demonstrate that the role of secretory pinealocytes in pineal photoreception increases with age. In monolayer cultures, all pinealocytes showed strong reactions in club- or bulbous-shaped prolongations. The pineal organs of adult birds were less sensitive to light exposition at night than those of young turkeys, which points to differences in light sensitivity between rudimentary receptor and secretory pinealocytes. However, direct photoreception could play an important role in the regulation of melatonin secretion in adult turkeys.

Histopathological Study of Well Differentiated Papillary Thyroid Carcinoma Case Study

The present study conducted on a fifty year old women affected with well differentiated papillary carcinoma, the histological changes of the thyroid left lobe was revealed, irregular shapes of thyroid follicles and degenerative alteration in the most follicles, Some thyroid follicles were enlarged and fill with colloid which contain on the large vacuoles, From another hand metaplastic changes was occur in the thyroid tissue of old women patient, So the epithelial linings of some thyroid follicles was projected as papillae which extended into the lumen of follicles, as well as the multifocal tumors of thyroid tissue was encapsculated by thick fibrous connective tissue, dilation and congestion of thyroid arteries and veins in parenchyma of thyroid left lobe.

Histological Alterations in Pacific Oysters Crassostrea gigas that Survived a Summer Mortality Event in Baja California, Mexico.

A mortality episode (>90%) of triploid and diploid Pacific oysters Crassostrea gigas cultured in Baja California Sur occurred during summer 2012, coinciding with a thermal anomaly, an algal bloom, and low oxygen values. To help explain the cause of the mortalities, histological analyses and molecular tests for specific pathogens (ostreid herpesvirus 1 [OsHV-1] and Perkinsus marinus) were performed on oysters surviving at the end of the episode. Triploid oysters showed a high percentage of males (43%) and hermaphrodites (30%); 93% of these oysters were in the gonadic reabsorption stage, and in some cases, hemocytes completely filled the lumen of the gonadic follicles. Oysters presented large areas with severe hemocyte infiltration that extended toward the digestive gland. Diploid oysters showed similar gonad alterations. None of samples showed histological or molecular evidence of OsHV-1 or P. marinus. Histological alterations can be related to physiological disorders caused by the mechanism driving summer mortality. This is the first case history of a summer mortality episode among Pacific oysters in Mexico.

HISTOARCHITECTURE OF THE THYROID GLAND IN PIGLETS WITH HYPOTROPHY AND AFTER THE COURSE OF MEDICAL CORRECTION

Antenatal malnutrition is a condition characterized by both a weight loss in animals and a change in the morphofunctional characteristics of the internal organs, particularly the incompleteness of the thyroid gland structure that will have a direct impact on the further growth and development of animals. Therefore, the aim of the research was to establish the patterns of histostructure of the thyroid gland inhypotrophic piglets and piglets after prenatal correction of hypotrophy considering their age. The study was performed on piglets of the large white breed. The study material was the thyroid gland of hypotrophic piglets and piglets after prenatal correction with Sedimin at 1, 5, 15 and 30 days of age. The main methods of study: histological, morphometric and statistical data processing. According to the research results, a thickening of the connective tissue capsule of the thyroid gland in newborns and five-day-old hypotrophic piglets was established in relation to fifteen and thirty-day-old ones. The average diameter of the follicle is at a relatively equal level during all periods of the study, the colloid acquired a “foamy” appearance on the fifth and fifteenth day. The form of thyrocytes and their nuclei changed with age from flattened to cubic. Cell-tissue composition of the thyroid gland of piglets after prenatal correction of malnutrition is functionally active. On the first and fifth days the capsule of the organ was thinned, by the end of the study its thickness increased markedly. The diameter of the follicles of the thyroid gland decreased from the neonatal period to the thirtieth day. Throughout the experiment, the structure of the colloid changed in the follicle lumen from homogeneous consistency to “frothy” by the end of the experiment. At the beginning of the experiment, both flattened and cubic-shape epithelial cells were observed in the parenchyma of the thyroid gland, by the thirtieth day it was stably cubic. The nuclei of thyrocytes are mostly spherical and hypochromic. In conclusion, it is worth noting that in hypotrophic piglets in the neonatal period and in the five-day age, the incompleteness of the structure of the thyroid gland was observed, the further morphological reorganization reached by the thirtieth day. The medication “Sedimin” had a positive effect on the body of pigs, reducing the degree of development of malnutrition and contributing to the adequate organoand histogenesis, including the thyroid gland.