The sulfotransferase XB5850668.L is required to apportion embryonic ectodermal domains.

BACKGROUND: Members of the sulfotransferase superfamily (SULT) influence the activity of a wide range of hormones, neurotransmitters, metabolites and xenobiotics. However, their roles in developmental processes are not well characterized even though they are expressed during embryogenesis. We previously found in a microarray screen that Six1 up-regulates LOC100037047, which encodes XB5850668.L, an uncharacterized sulfotransferase. RESULTS: Since Six1 is required for patterning the embryonic ectoderm into its neural plate, neural crest, preplacodal and epidermal domains, we used loss- and gain-of function assays to characterize the role of XB5850668.L during this process. Knockdown of endogenous XB5850668.L resulted in the reduction of epidermal, neural crest, cranial placode and otic vesicle gene expression domains, concomitant with neural plate expansion. Increased levels had minimal effects, but infrequently expanded neural plate and neural crest gene domains, and infrequently reduced cranial placode and otic vesicle gene domains. Mutation of two key amino acids in the sulfotransferase catalytic domain required for PAPS binding and enzymatic activity tended to reduce the effects of overexpressing the wild-type protein. CONCLUSIONS: Our analyses indicates that XB5850668.L is a member of the SULT2 family that plays important roles in patterning the embryonic ectoderm. Some aspects of its influence likely depend on sulfotransferase activity.

Analysis of evolutionary and functional features of the bullfrog SULT1 family.

We identified the bullfrog Rana catesbeiana sulfotransferase 1 (SULT1) family from the BLAST search tool of the public databases based on the SULT1 families of Nanorana parkeri, Xenopus laevis, and Xenopus tropicalis as queries, revealing the characteristics of the anuran SULT1 family. The results showed that the anuran SULT1 family comprises six subfamilies, four of which were related to the mammalian SULT1 subfamily. Additionally, the bullfrog has two SULT1Cc subfamily members that are consistent with the characteristics of the expanded Xenopus SULT1C subfamily. Several members of the bullfrog SULT1 family were suggested to play important roles in sulfation during metamorphosis. Among these, cDNAs encoding SULT1Cc1 and SULT1Y1 were cloned, and the sulfation activity was analyzed using recombinant proteins. The affinity for 2-naphthol and 3'-phosphoadenosine 5'-phosphosulfate (PAPS) and the enzymatic reaction rate were higher in SULT1Cc1 than in SULT1Y1. Both the enzymes showed inhibitory effect of many thyroid hormones (THs) analogs on the sulfation of 2-naphthol. The potency of sulfation activities of SULT1Cc1 and SULT1Y1 against T4 indicated their possible role in the intracellular T4 clearance during metamorphosis.

The interaction of zinc with the multi-functional plasma thyroid hormone distributor protein, transthyretin: evolutionary and cross-species comparative aspects.

A considerable body of evidence has been accumulated showing the interrelationship between zinc and the plasma thyroid hormone (TH) distributor protein, transthyretin (TTR). TTR is a multi-functional protein, which emerged from 5-hydroxyisourate hydrolase (HIUHase) by neo-functionalization after gene duplication during early chordate evolution. HIUHase is also a zinc-binding protein. Most biochemical and molecular biological findings have been obtained from mammalian studies. However, in the past two decades, it has become clear that fish TTR displays zinc-dependent TH binding. After a brief introduction on plasma zinc, THs and their binding proteins, this review will focus on the role of zinc in TTR functions of various vertebrates. In particular primitive fish TTR has an extremely high zinc content, with an increased number of histidine residues which are involved in TH binding. However, zinc-dependent TH binding may have been gradually lost from TTRs during higher vertebrate evolution. Although human TTR has a low zinc content, zinc plays an essential role in TTR functions other than TH binding: the stability of TTR-holo retinol binding protein 4 (holoRBP4) complex, TTR amyloidogenesis, the sequestration of amyloid ß (Aß) fibrils and cryptic proteolytic activity. The interaction of TTR with metallothioneins may be a critical step in the exertion of some of these functions. Evolutionary and physiological insights on zinc-dependent functions of TTRs are also discussed.

Evolution of thyroid hormone distributor proteins in fish.

In plasma, thyroid hormone (TH) is bound to several TH distributor proteins (THDPs), constituting a TH delivery/distribution network. Extensive studies of THDPs from tetrapods has proposed an evolutionary scenario concerning structural and functional changes in THDPs, especially for transthyretin (TTR). When assessing, in an evolutionary context, the roles of THDPs as a component constituting part of the vertebrate thyroid system, the data from fish THDPs are critical. In this review the phylogenetic distributions, spatiotemporal expression patterns and binding properties of THDPs in fish are described, and the question of whether the evolutionary hypotheses proposed in tetrapod THDPs can be applied to fish THDPs is assessed. The phylogenetic distributions of THDPs are highly variable among fish groups. Analysis in this review reveals that the evolutionary hypotheses proposed in tetrapod THDPs cannot be applied to fish THDPs, and that the role of plasma lipoproteins as THDPs grows in importance in fish groups. In primitive fish, zinc is an import factor in TH binding to TTR, and high zinc content may facilitate the acquisition of high TH binding activity during the early evolution of TTR. Finally, the possible roles of THDPs in the vertebrate thyroid system are discussed.

Modulation of plasma protein expression in bullfrog (Rana catesbeiana) tadpoles during seasonal acclimatization and thermal acclimation.

Biological activities in ectothermic vertebrates depend to a great extent on ambient temperature. Adapting their biological systems to annual or short-term alterations in temperature may play an important role in thermal resistance or overwintering survival. Using SDS-PAGE and western blot, we examined plasma proteins in bullfrog (Rana catesbeiana) tadpoles that were seasonally acclimatized (winter vs. summer) or thermally acclimated (4 °C vs. 21 °C) and identified two season-responsive proteins. The first, transthyretin (TTR), is a plasma thyroid hormone distributor protein that was abundant in summer, and the second is a protein containing C-type lectin-like domain (CTLD) that was abundant in winter and cold acclimation of 4 weeks. Sequence analysis revealed that the C-terminal carbohydrate recognition domain of this CTLD protein (termed collectin X) was highly similar to those of the collectin family members, which participate in complement activation of the innate immune system; however, it lacked most of collagen-like domain. Among the hepatic genes involved in the thyroid system, ttr and dio3 were up-regulated, whereas thra and thrb were down-regulated, in summer acclimatization or warm acclimation. In contrast, the collectin X gene (colectx), as well as colect10 and colect11 in the collectin family involved in the innate immune system, were down-regulated during warm acclimation, although fcn2 in the ficolin family was up-regulated during summer acclimatization and warm acclimation. These findings indicate that seasonal acclimatization and thermal acclimation differentially affect some components of the thyroid and innate immune systems at protein and transcript levels.

Seasonal acclimatization and thermal acclimation induce global histone epigenetic changes in liver of bullfrog (Lithobates catesbeianus) tadpole.

The American bullfrog (Lithobates catesbeianus) is a eurythermal amphibian that is naturally distributed from subarctic to subtropical areas. The tadpoles of this species overwinter, in water, in cold environments. Therefore, they may have adapted to a wide range of temperatures in an active state. To understand the adaptation mechanisms to cope with low or high temperatures, we investigated global epigenetic modifications, histone variants, transcript levels of related genes, and the cellular acetyl coenzyme A (acetyl-CoA) and free CoA (CoA-SH) levels, in the livers of tadpoles collected in summer and winter and of those acclimated to 4 °C and 21 °C. Among epigenetic marks tested, the levels of acetylated histones and the histone variant H2A.Z were influenced by different temperature conditions. Histone acetylation levels were higher in summer than in winter and increased within 3 days of warm acclimation, whereas histone H2A.Z levels were higher in winter than in summer and decreased within 2 weeks of warm acclimation. Transcript analysis revealed that decreased expression of histone H2A.Z in warm acclimation was regulated at the transcriptional level. Acetyl-CoA levels were not correlated with those of the acetylated histones, indicating that cellular acetyl-CoA levels may not directly influence the state of histone acetylation in the tadpole liver. Such epigenetic and metabolic changes in the tadpole liver may contribute to the maintenance of energy balance during seasonal acclimatization and thermal acclimation.

Analysis of global and gene-specific acetylation of histones in the liver of American bullfrog (Rana catesbeiana) tadpoles acclimated to low temperature.

Severe environmental stressors such as low temperatures can affect gene expression by changing epigenetic states. American bullfrog (Rana catesbeiana) can overwinter as tadpoles, which can be active even in winter. However, the molecular mechanisms of epigenetic controls by which the tadpoles acclimate to low temperature are still unclear. In this study, we aimed to clarify the molecular mechanisms of global and gene-specific epigenetic regulations of low-temperature acclimation. We found that the global acetylation was decreased in the liver of bullfrog tadpoles acclimated to low temperature. The amounts of transcripts for two histone acetyltransferases were higher in the liver of tadpoles acclimated to low temperature than in those acclimated to warm temperature, while we observed no significant differences in the amounts of transcripts for histone deacetylases. We also found that the amounts of transcripts and acetylated histones on the specific temperature-responsive genes scd and cyp7a1 whose transcripts were increased and decreased, respectively, in response to low temperature were positively correlated. Cellular acetyl-CoA levels were higher in the liver of tadpoles acclimated to low temperature than in those acclimated to warm temperature. These results contradicted the states of histone acetylation, suggesting that bullfrog tadpoles have different epigenetic mechanisms to modify the histones when compared with those of other organisms such as reptiles and mammals, even though the relationship between the transcript amount and the states of histone acetylation on temperature-responsive genes was similar to that of mammals.

Sequential Molecular Events of Functional Trade-Offs in 5-Hydroxyisourate Hydrolase Before and After Gene Duplication Led to the Evolution of Transthyretin During Chordate Diversification.

Transthyretin (TTR), a plasma thyroid hormone distributor protein (THDP), emerged from 5-hydroxyisourate hydrolase (HIUHase), an enzyme involved in urate metabolism, by gene duplication at a stage of chordate evolution. Comparison of amino acid sequences revealed the presence of two His-rich segments in the primitive TTRs. Using several HIUHase and TTR mutants, we investigated 5-hydroxyisourate (HIU) hydrolysis activity and thyroid hormone (TH) binding activity to elucidate how a novel function as a THDP arose. Lancelet HIUHase was found to have higher enzyme activity than trout HIUHase. Two amino acid substitutions, R54E/Y119T, at the active sites of HIUHase, exerted weak [125I]-3,3',5-triiodo-L-thyronine ([125I]T3) binding activity with a concomitant loss of HIU hydrolysis activity. Addition of 3×His (3×H) to the N-terminal end weakened HIU hydrolysis activity of both lancelet and trout HIUHases, whereas it enhanced T3-binding activity of HIUHase R54E/Y119T. Trout HIUHase 3×H R54E/Y119T had higher [125I]T3-binding activity than that of lancelet HIUHase 3×H R54E/Y119T, with a Kd of 143 nM, and displayed metal dependency and no TH binding specificity. Deletion of the N-terminal His-rich segment from lamprey TTR decreased T3-binding activity, while addition of 3×H to trout TTR increased T3-binding activity, while maintaining TH binding specificity. Our results suggest that functional trade-offs of HIU hydrolysis activity with TH binding activity might have sequentially occurred before and after gene duplication, and that TH binding specificity and high-affinity sites may have been acquired later in the course of TTR evolution.

New Aspects of the Structure of Human Scalp Hair-II: Tubular Structure and Material Flow Property of the Medulla.

Asian scalp hair fibers were made thin by treatment with papain or sliced along the longitudinal axis or randomly cut by mechanical means. Optical microscopic observations of the resulting specimens indicated that (i) the medulla (M) consisted of two types of the M-surrounding cells which were linearly linked one another to form a tubular structure running through the fiber and (ii) the drum-shaped vesicles containing small proteinous granules were neatly or sparsely stored within the tube. On the other hand, H+ and OH- ions were able to move spontaneously from one end to another through the M tube. Large molecules such as an anthocyanin dye (from purple sweet potato) were also capable of flowing through the M tube, especially rapidly when DC voltage was applied between the two ends of the hair fiber. The possible function of the M is briefly discussed in conjunction with the tubular structure and the material flow property.

Characteristics of the brown hagfish Paramyxine atami transthyretin: Metal ion-dependent thyroid hormone binding.

Transthyretin (TTR) is a vertebrate-specific protein involved in thyroid hormone distribution in plasma, and its gene is thought to have emerged by gene duplication from the gene for the ancient TTR-related protein, 5-hydroxyisourate hydrolase, at some early stage of chordate evolution. We investigated the molecular and hormone-binding properties of the brown hagfish Paramyxine atami TTR. The amino acid sequence deduced from the cloned hagfish TTR cDNA shared 33-50% identities with those of other vertebrate TTRs but less than 24% identities with those of vertebrate and deuterostome invertebrate 5-hydroxyisourate hydrolases. Hagfish TTR, as well as lamprey and little skate TTRs, had an N-terminal histidine-rich segment, allowing purification by metal-affinity chromatography. The affinity of hagfish TTR for 3,3',5-triiodo-L-thyronine (T3) was 190 times higher than that for L-thyroxine, with a dissociation constant of 1.5-3.9nM at 4°C. The high-affinity binding sites were strongly sensitive to metal ions. Zn2+ and Cu2+ decreased the dissociation constant to one-order of magnitude, whereas a chelator, o-phenanthroline, increased it four times. The number of metal ions (mainly Zn2+ and Cu2+) was approximately 12/TTR (mol/mol). TTR was also a major T3-binding protein in adult hagfish sera and its serum concentration was approximately 8µM. These results suggest that metal ions and the acquisition of N-terminal histidine-rich segment may cooperatively contribute to the evolution toward an ancient TTR with high T3 binding activity from either 5-hydroxyisourate hydrolase after gene duplication.

Long-Term Survey of Cadmium and Lead Contamination in Japanese Black Bears Captured in Iwate Prefecture, Japan.

Cadmium and lead were measured in liver and kidney samples of 242 Japanese black bears (Ursus thibetanus japonicus) captured from 1999 to 2014 from two local populations in Japan. The median concentration of cadmium was 0.54 (mean: 0.80) mg/kg-w.w. in liver and 7.7 (mean: 11.8) mg/kg-w.w. in kidney. The median concentration of lead was 0.24 (mean: 0.40) and 0.21 (mean: 0.32) mg/kg-w.w. in liver and kidney, respectively. Bears in the Kita-ou local population had higher concentrations of cadmium and lead than those in the Kitakami Highlands local population. No chronological change was observed in cadmium levels in tissues, but the percentage of bears whose lead levels exceeded 0.5 mg/kg-w.w. has been decreasing in recent years. Countermeasures against lead poisoning in wildlife, which were instituted in 2002, may have contributed to the decrease in lead contamination of the Japanese black bear.

Exposure to 3,3',5-triiodothyronine affects histone and RNA polymerase II modifications, but not DNA methylation status, in the regulatory region of the Xenopus laevis thyroid hormone receptor ßΑ gene.

Thyroid hormones (THs) play a critical role in amphibian metamorphosis, during which the TH receptor (TR) gene, thrb, is upregulated in a tissue-specific manner. The Xenopus laevis thrb gene has 3 TH response elements (TREs) in the 5' flanking regulatory region and 1 TRE in the exon b region, around which CpG sites are highly distributed. To clarify whether exposure to 3,3',5-triiodothyronine (T3) affects histone and RNA polymerase II (RNAPII) modifications and the level of DNA methylation in the 5' regulatory region, we conducted reverse transcription-quantitative polymerase chain reaction, bisulfite sequencing and chromatin immunoprecipitation assay using X. laevis cultured cells and premetamorphic tadpoles treated with or without 2 nM T3. Exposure to T3 increased the amount of the thrb transcript, in parallel with enhanced histone H4 acetylation and RNAPII recruitment, and probably phosphorylation of RNAPII at serine 5, in the 5' regulatory and exon b regions. However, the 5' regulatory region remained hypermethylated even with exposure to T3, and there was no significant difference in the methylation status between DNAs from T3-untreated and -treated cultured cells or tadpole tissues. Our results demonstrate that exposure to T3 induced euchromatin-associated epigenetic marks by enhancing histone acetylation and RNAPII recruitment, but not by decreasing the level of DNA methylation, in the 5' regulatory region of the X. laevis thrb gene.

Histochemical Analyses of Biliary Development During Metamorphosis of Xenopus laevis Tadpoles.

In mammalian liver development, intrahepatic biliary morphogenesis takes place in periportal, but not in pericentral, regions. Liver progenitor cells transiently form epithelial plate structures and then intrahepatic bile ducts around the portal veins under the influence of the mesenchyme. The present study was undertaken to histochemically examine normal biliary development and its dependence on the action of the thyroid hormone triiodothyronine (T3) in Xenopus laevis tadpoles. In these tadpoles, the development of hepatic ducts and intrahepatic biliary ducts commenced along the portal veins at NF stages 48-50 and stages 50-52, respectively, when the blood concentration of thyroid hormone may be still low. Some periportal hepatocytes expressed carbamoylphosphate synthase I and SOX9, which are hepatocyte and biliary cell markers, respectively, suggesting that periportal hepatocytes give rise to biliary epithelial cells. Periportal biliary cells did not form ductal plates, nor was the periportal mesenchyme well developed as seen in fetal mouse livers. jag1 mRNA was moderately expressed in cells of portal veins and biliary epithelial cells, and notch1 and notch2 mRNAs were weakly detectable in biliary epithelial cells during metamorphosis as seen in developing mammalian livers. These results suggest that Notch signaling plays a decisive role in biliary cell differentiation and morphogenesis of Xenopus tadpoles. Anti-thyroid agent treatment of the tadpoles resulted in delayed biliary morphogenesis, suggesting that biliary development may depend on T3. However, T3 treatment of the tadpoles did not enhance biliary development. Thus, T3 may act positively on biliary development at a very low concentration.

Characterization of little skate (Leucoraja erinacea) recombinant transthyretin: Zinc-dependent 3,3',5-triiodo-l-thyronine binding.

Transthyretin (TTR) diverged from an ancestral 5-hydroxyisourate hydrolase (HIUHase) by gene duplication at some early stage of chordate evolution. To clarify how TTR had participated in the thyroid system as an extracellular thyroid hormone (TH) binding protein, TH binding properties of recombinant little skate Leucoraja erinacea TTR was investigated. At the amino acid level, skate TTR showed 37-46% identities with the other vertebrate TTRs. Because the skate TTR had a unique histidine-rich segment in the N-terminal region, it could be purified by Ni-affinity chromatography. The skate TTR was a 46-kDa homotetramer of 14.5kDa subunits, and had one order of magnitude higher affinity for 3,3',5-triiodo-l-thyronine (T3) and some halogenated phenols than for l-thyroxine. However, the skate TTR had no HIUHase activity. Ethylenediaminetetraacetic acid (EDTA) treatment inhibited [(125)I]T3 binding activity whereas the addition of Zn(2+) to the EDTA-treated TTR recovered [(125)I]T3 binding activity in a Zn(2+) concentration-dependent manner. Scatchard analysis revealed the presence of two classes of binding site for T3, with dissociation constants of 0.24 and 17nM. However, the high-affinity sites were completely abolished with 1mM EDTA, whereas the remaining low-affinity sites decreased binding capacity. The number of zinc per TTR was quantified to be 4.5-6.3. Our results suggest that skate TTR has tight Zn(2+)-binding sites, which are essential for T3 binding to at least the high-affinity sites. Zn(2+) binding to the N-terminal histidine-rich segment may play an important role in acquisition or reinforcement of TH binding ability during early evolution of TTR.

New aspects of the structure of human hair on the basis of optical microscopic observations of disassembled hair parts.

Infant' and adult' scalp hair fibers were disassembled to various cellular components and blocks by chemical and enzymatic treatments, followed by random scission with rapidly rotating cutters. The hair fibers were also fractured by the use of a vise. The optical microscopic inspection of these specimens led to the discovery of many previously unknown structures in the hair shaft. In particular, a cuticular cell (Cu) was found to take a trowel-like shape consisting of a part with a blade-like shape (CuB) and a part with a handle-like shape (CuH), where CuB overlapped one another and fused partially to build the honeycomb-like structure on a large cuticular thin plate (CuP). Whereas CuH was closely similar to the cortical cell in dimensions and richness of macrofibrils (Mf). It was considered that human hair is stabilized structurally and physicochemically by the presence of the honeycomb-like structure, the CuP and the Mf.

Far-East Asian Toxoplasma isolates share ancestry with North and South/Central American recombinant lineages.

Toxoplasma gondii is a global protozoan pathogen. Clonal lineages predominate in Europe, North America, Africa, and China, whereas highly recombinant parasites are endemic in South/Central America. Far East Asian T. gondii isolates are not included in current global population genetic structure analyses at WGS resolution. Here we report a genome-wide population study that compared eight Japanese and two Chinese isolates against representative worldwide T. gondii genomes using POPSICLE, a novel population structure analyzing software. Also included were 7 genomes resurrected from non-viable isolates by target enrichment sequencing. Visualization of the genome structure by POPSICLE shows a mixture of Chinese haplogroup (HG) 13 haploblocks introgressed within the genomes of Japanese HG2 and North American HG12. Furthermore, two ancestral lineages were identified in the Japanese strains; one lineage shares a common ancestor with HG11 found in both Japanese strains and North American HG12. The other ancestral lineage, found in T. gondii isolates from a small island in Japan, is admixed with genetically diversified South/Central American strains. Taken together, this study suggests multiple ancestral links between Far East Asian and American T. gondii strains and provides insight into the transmission history of this cosmopolitan organism.

Adult male Xenopus laevis can tolerate months of fasting by catabolizing carbohydrates and lipids.

The African clawed frog, Xenopus laevis, has been reported to tolerate long-term fasting without dormancy. However, the strategies for energy acquisition during fasting are unclear in this species. We performed 3- and 7-month fasting experiments to investigate how the metabolism of male X. laevis changes during long-term fasting. We found that the levels of several serum biochemical parameters, such as glucose, triglycerides, and free fatty acids, as well as liver glycogen were reduced after 3 months of fasting, whereas after 7 months of fasting, triglyceride levels were reduced, and fat body wet weight was lower than that of fed group indicating the onset of lipid catabolism. In addition, transcript levels of gluconeogenic genes, such as pck1, pck2, g6pc1.1, and g6pc1.2, were increased in the livers of animals fasted for 3 months, suggesting upregulation of gluconeogenesis. Our results raise the possibility that male X. laevis can tolerate much longer fasting than previously reported by utilizing several energy storage molecules. Further investigation of the effects of prolonged fasting on the metabolic switches from carbohydrates to lipids or amino acids in X. laevis is required.

RNA polymerase II phosphorylation at serine 2 and histone H3 tri-methylation at lysine 36 are key steps for thyroid hormone receptor ß gene activation by thyroid hormone in Rana catesbeiana tadpole liver.

Thyroid hormone (TH) is essential for amphibian metamorphosis, during which the expression of many genes is controlled directly or indirectly through TH receptors (TRs). Thyroid hormone binding to TRs induces coregulator switching on regulatory regions of TH-inducible genes: corepressors complexed with unliganded TRs are replaced by coactivators complexed with liganded TR resulting in transcriptionally active states. The coregulator switching is linked to histone acetylation. In our study, we have investigated the acetylation and methylation states of histones H3 and H4 using chromatin immunoprecipitation (ChIP) assays on the 5' coding region of the TRß gene, a primary TH-response gene, in the liver from Rana catesbeiana tadpoles either treated with or not treated with 3,3',5-triiodothyronine (T3). 3,3',5-Triiodothyronine treatment for 3 days increased the amount of TRß transcript by 19-fold. This increase was associated with increases in the acetylation of histone H4 and lysine 9 in histone H3 (H3-K9), and tri-methylation of lysine 36 in histone H3 (H3-K36). In addition, the amounts of RNA polymerase II (PolII) and serine 2 phosphorylation in PolII (PolII-S2) increased. These results suggest that T3 treatment enhances the elongation activity of PolII on the TRß gene in the liver by increasing histone H3-K36 tri-methylation through PolII-S2 phosphorylation.

Gene expression profile in the liver of Rana catesbeiana tadpoles exposed to low temperature in the presence of thyroid hormone.

Amphibian metamorphosis, which is controlled by thyroid hormone (TH), is highly temperature-sensitive. Using real-time PCR, we investigated the gene expression profile in the liver of Rana catesbeiana tadpoles kept at 28 and 4 °C and treated with 5 nM 3,3',5-triiodothyronine (T3). Out of the 48 genes tested, 12 were up-regulated at 4 °C in T3-treated or untreated tadpoles. These included genes involved in energy metabolism, transcription, and translation. Four TH-response genes, including TH receptor ß (TRß) gene, showed no response to T3 at 4 °C. Deiodinase III was the only gene down-regulated at 4 °C. Chromatin immunoprecipitation assays showed that CCAAT/enhancer-binding protein 2 gene activation by cold exposure was associated with an increase in the acetylation of histone H3 at lysine 9, whereas TRß gene activation by T3 at 28 °C was associated with an increase in the methylation of histone H3 at lysine 36 with no T3-dependent changes in methylation states on cold exposure. Our results suggest that the transfer of TH signal to chromatin modifications on a primary early TH response gene was specifically blocked by exposure to cold.

Genetic variation and population structure of the Japanese sika deer (Cervus nippon) in the Tohoku District based on mitochondrial D-loop sequences.

The sika deer (Cervus nippon) once inhabited the entire Tohoku District, the northeastern part of the main island of Japan. Currently, they are isolated as three discontinuous populations on Mt. Goyo, the Oshika Peninsula, and Kinkazan Island. To assess the genetic diversity and relationships among the sika deer populations in the Tohoku District, we analyzed the mitochondrial DNA D-loop sequences from 177 individuals. We detected a total of five haplotypes. Three haplotypes were present in the population from Mt. Goyo at a haplotype diversity of 0.235 ± 0.061, two haplotypes in the population from the Oshika Peninsula at 0.171 ± 0.064, and only one haplotype was detected in the population from the Kinkazan Island. A significant genetic differentiation was observed among all population pairs. Collectively, our data supports the observed population bottlenecks in the past. Four of the five haplotypes were specific to one of the three populations, whereas only one haplotype was shared between the Mt. Goyo and the Oshika Peninsula populations. This common haplotype may indicate a common ancestral population in the Tohoku District. Conversely, the D-loop haplotypes were completely different among the Kinkazan Island and Oshika Peninsula populations. The lack of a shared haplotype indicates that female gene flow between the two populations is very limited and that the 0.6 km strait acts as a strong barrier.