Identification of an estrogenic hormone receptor in Caenorhabditis elegans

Changes in both behavior and gene expression occur in Caenorhabditis elegans following exposure to sex hormones such as estrogen and progesterone, and to bisphenol A (BPA), an estrogenic endocrine-disrupting compound. However, only one steroid hormone receptor has been identified. Of the 284 known nuclear hormone receptors (NHRs) in C. elegans, we selected nhr-14, nhr-69, and nhr-121 for analysis as potential estrogenic hormone receptors, because they share sequence similarity with the human estrogen receptor. First, the genes were cloned and expressed in Escherichia coli, and then the affinity of each protein for estrogen was determined using a surface plasmon resonance (SPR) biosensor. All three NHRs bound estrogen in a dose-dependent fashion. To evaluate the specificity of the binding, we performed a solution competition assay using an SPR biosensor. According to our results, only NHR-14 was able to interact with estrogen. Therefore, we next examined whether nhr-14 regulates estrogen signaling in vivo. To investigate whether these interactions actually control the response of C. elegans to hormones, we investigated the expression of vitellogenin, an estrogen responsive gene, in an nhr-14 mutant. Semi-quantitative RT-PCR showed that vitellogenin expression was significantly reduced in the mutant. This suggests that NHR-14 is a C. elegans estrogenic hormone receptor and that it controls gene expression in response to estrogen.     

Bld10p constitutes the cartwheel-spoke tip and stabilizes the 9-fold symmetry of the centriole

Centrioles/basal bodies have a characteristic cylindrical structure consisting of nine triplet microtubules arranged in a rotational symmetry. How this elaborate structure is formed is a major unanswered question in cell biology [1, 2]. We previously identified a 170 kDa coiled-coil protein essential for the centriole formation in Chlamydomonas. This protein, Bld10p, is the first protein shown to localize to the cartwheel, a 9-fold symmetrical structure possibly functioning as the scaffold for the centriole-microtubule assembly [3]. Here, we report results by using a series of truncated Bld10p constructs introduced into a bld10 null mutant. Remarkably, a transformant (DeltaC2) in which 35% of Bld10p at the C terminus was deleted assembled centrioles with eight symmetrically arranged triplets, in addition to others with the normal nine triplets. The cartwheels in these eight-membered centrioles had spokes approximately 24% shorter than those in the wild-type, suggesting that the eight-triplet centrioles were formed because the cartwheel's smaller diameter. From the morphology of the cartwheel spoke in the DeltaC2 centriole and immunoelectron-microscope localization, we conclude that Bld10p is a major spoke-tip component that extends the cartwheel diameter and attaches triplet microtubules. These results provide the first experimental evidence for the crucial function of the cartwheel in centriolar assembly.     

Seasonal changes in taxon richness and abundance of mobile invertebrates inhabiting holdfast of annual kelp Ecklonia radicosa (Phaeophyceae,Lessoniaceae) at the central Pacific coast of Japan

To investigate seasonal changes in the taxon richness and abundance of mobile invertebrates inhabiting holdfasts of the warm temperate annual kelp Ecklonia radicosa, five holdfasts were collected monthly at the central Pacific coast of Japan from April to November 2014. During the study period, there was little variation in holdfast height and diameter, which ranged from 5.9 to 8.5 cm and from 7.1 to 10.8 cm, respectively. In total 7087 animals were collected from 40 holdfasts (177.2 individuals inds./holdfast, on average). The number of mobile invertebrates gradually increased from May (15 ± 9.9 inds./holdfast) to August (346 ± 152.5 inds./holdfast), with over 300 inds./holdfast until October before rapidly decreasing in November (110 ± 85.6 inds./holdfast). Similarly, taxon richness increased gradually from April (4.3 ± 1.0 taxa/holdfast) to August (11.0 ± 3.7 taxa/holdfast), and decreased in November (8.6 ± 2.3 taxa/holdfast). Interestingly, hundreds of mobile invertebrates inhabited holdfasts of kelp plants that had shed their blade in October and November. Taxon composition from August to October and the number of invertebrates from July to November were comparable to data previously reported for perennial kelps. In this study, the importance of annual Ecklonian species as biogenic habitats was demonstrated for the first time.     

Axon Diameter and Intra-Axonal Volume Fraction of the Corticospinal Tract in Idiopathic Normal Pressure Hydrocephalus Measured by Q-Space Imaging

Purpose

Previous studies suggest that compression and stretching of the corticospinal tract (CST) potentially cause treatable gait disturbance in patients with idiopathic normal pressure hydrocephalus (iNPH). Measurement of axon diameter with diffusion MRI has recently been used to investigate microstructural alterations in neurological diseases. In this study, we investigated alterations in the axon diameter and intra-axonal fraction of the CST in iNPH by q-space imaging (QSI) analysis.

Methods

Nineteen patients with iNPH and 10 age-matched controls were recruited. QSI data were obtained with a 3-T system by using a single-shot echo planar imaging sequence with the diffusion gradient applied parallel to the antero-posterior axis. By using a two-component low-q fit model, the root mean square displacements of intra-axonal space ( =  axon diameter) and intra-axonal volume fraction of the CST were calculated at the levels of the internal capsule and body of the lateral ventricle, respectively.

Results

Wilcoxon''s rank-sum test revealed a significant increase in CST intra-axonal volume fraction at the paraventricular level in patients (p<0.001), whereas no significant difference was observed in the axon diameter. At the level of the internal capsule, neither axon diameter nor intra-axonal volume fraction differed significantly between the two groups.

Conclusion

Our results suggest that in patients with iNPH, the CST does not undergo irreversible axonal damage but is rather compressed and/or stretched owing to pressure from the enlarged ventricle. These analyses of axon diameter and intra-axonal fraction yield insights into microstructural alterations of the CST in iNPH.     

Isolation of a protein lethal to the endoparasitoid Cotesia kariyai from entomopoxvirus-infected larvae of Mythimna separata

Virion-free plasma from entomopoxvirus (MyseEPV)-infected larvae of the armyworm, Mythimna separata, contains a factor that adversely affects the survival of the gregarious braconid endoparasitoid, Cotesia kariyai. Heating or proteinase K treatment eliminates the toxic effect of virion-free plasma on the parasitoid, suggesting that the lethal factor is a protein. We purified the Protein Lethal to C. kariyai larvae (PLCK) from the virion-free plasma of MyseEPV-infected M. separata larvae by a three-step procedure using gel filtration and cation-exchange chromatography. Toxic activity was measured using an in vitro-cultured parasitoid bioassay. Parasitoid larvae cultured in IPL-41 medium (Weiss et al., In vitro 17 (1981), 495) containing 4.7 microg/ml purified PLCK shrank and died within 3days. The molecular weight of PLCK was estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be about 28,000, under both reducing and non-reducing conditions, indicating that in its native form the protein is a single 28-kDa polypeptide. Western blot analysis indicated that the lethal protein is not present in the hemolymph of uninfected host larvae, but is induced in the hemolymph by infection with MyseEPV. Western blot analysis also indicated that the proteins of virions and occlusion bodies of MyseEPV are not serologically related to PLCK.     

Microscopic heat pulses induce contraction of cardiomyocytes without calcium transients

It was recently demonstrated that laser irradiation can control the beating of cardiomyocytes and hearts, however, the precise mechanism remains to be clarified. Among the effects induced by laser irradiation on biological tissues, temperature change is one possible effect which can alter physiological functions. Therefore, we investigated the mechanism by which heat pulses, produced by infra-red laser light under an optical microscope, induce contractions of cardiomyocytes. Here we show that microscopic heat pulses induce contraction of rat adult cardiomyocytes. The temperature increase, ΔT, required for inducing contraction of cardiomyocytes was dependent upon the ambient temperature; that is, ΔT at physiological temperature was lower than that at room temperature. Ca(2+) transients, which are usually coupled to contraction, were not detected. We confirmed that the contractions of skinned cardiomyocytes were induced by the heat pulses even in free Ca(2+) solution. This heat pulse-induced Ca(2+)-decoupled contraction technique has the potential to stimulate heart and skeletal muscles in a manner different from the conventional electrical stimulations.     

High calorie diet augments age-associated sleep impairment in Drosophila

The fruit fly, Drosophila melanogaster is an established model used for aging and longevity studies and more recently for sleep studies. Mammals and Drosophila share various physiological, pathological, pharmacological and genetic similarities in these processes. In particular, sleep is essential for survival in both species and both have age-associated sleep quality alterations. Here we report that a high calorie diet, which accelerates the aging process and reduces lifespan across species, also accelerates age-associated sleep changes in Drosophila. These changes are more evident in the dopamine transporter mutant, fumin, that displays a short sleep phenotype due to enhanced dopaminergic signaling. With normal food, fumin mutants sleep for only one third of the time that the control flies do, but still show equivalent longevity. However, when on a mildly high calorie diet, their sleep length shows a marked decrease and they have a reduced longevity. These data indicate that the age-associated change in sleep in Drosophila is a physiologically regulated aging process that is tightly linked to calorie intake and that the dopamine level plays an important role. In addition, this provides another evidence that sleep is essential for the longevity of Drosophila.     

Conserved protein TTHA1554 from Thermus thermophilus HB8 binds to glutamine synthetase and cystathionine β-lyase

TTHA1554 was found as a hypothetical protein composed of 95 amino acids in the genome of the extremely thermophilic bacterium, Thermus thermophilus HB8. Proteins homologous to TTHA1554 are conserved in several bacteria and archaea, although their functions are unknown. To investigate the function of TTHA1554, we identified interacting proteins by using a pull-down assay and mass spectrometry. TTHA1329, which is glutamine synthetase, and TTHA1620, a putative aminotransferase, were identified as TTHA1554 binding proteins. The interactions with TTHA1329 and TTHA1620 were validated using in vitro pull-down assays and surface plasmon resonance biosensor assays with recombinant proteins. Since sequence homology analyses suggested that TTHA1620 was a pyridoxal 5′-phosphate-dependent enzyme, such as an aminotransferase, a cystathionine β-lyase or a cystalysin, putative substrates were investigated. When cystathionine, cystine and S-methylcysteine were used as substrates, pyruvate was produced by TTHA1620. The data revealed that TTHA1620 has cystathionine β-lyase enzymatic activity. When TTHA1554 was added to the reaction mixtures, the glutamine synthetase and cystathionine β-lyase enzymatic activities both increased by approximately two-fold. These results indicated that TTHA1554 is a novel protein (we named it GCBP: glutamine synthetase and cystathionine β-lyase binding protein) that binds to glutamine synthetase and cystathionine β-lyase.     

Crystal structure and mutational study of a unique SpoU family archaeal methylase that forms 2'-O-methylcytidine at position 56 of tRNA

The conserved cytidine residue at position 56 of tRNA contributes to the maintenance of the L-shaped tertiary structure. aTrm56 catalyzes the 2′-O-methylation of the cytidine residue in archaeal tRNA, using S-adenosyl-L-methionine. Based on the amino acid sequence, aTrm56 is the most distant member of the SpoU family. Here, we determined the crystal structure of Pyrococcus horikoshii aTrm56 complexed with S-adenosyl-L-methionine at 2.48 Å resolution. aTrm56 consists of the SPOUT domain, which contains the characteristic deep trefoil knot, and a unique C-terminal β-hairpin. aTrm56 forms a dimer. The S-adenosyl-L-methionine binding and dimerization of aTrm56 were similar to those of the other SpoU members. A structure-based sequence alignment revealed that aTrm56 conserves only motif II, among the four signature motifs. However, an essential Arg16 residue is located at a novel position within motif I. Biochemical assays showed that aTrm56 prefers the L-shaped tRNA to the λ form as its substrate.