Identification and Characterization of the Larval Settlement Pheromone Protein Components in Adult Shells of Crassostrea gigas: A Novel Function of Shell Matrix Proteins

The global decline of natural oyster populations emphasizes the need to improve our understanding of their biology. Understanding the role of chemical cues from conspecifics on how oysters occupy appropriate substrata is crucial to learning about their evolution, population dynamics, and chemical communication. Here, a novel role of a macromolecular assembly of shell matrix proteins which act as Crassostrea gigas Settlement Pheromone Protein Components in adult shells is demonstrated as the biological cue responsible for gregarious settlement on conspecifics. A bioassay-guided fractionation approach aided by biochemical and molecular analyses reveals that Gigasin-6 isoform X1 and/or X2 isolated from adult shells is the major inducing cue for larval settlement and may also play a role in postlarva–larva settlement interactions. Other isolated Stainsall-stainable acidic proteins may function as a co-factor and a scaffold/structural framework for other matrix proteins to anchor within this assembly and provide protection. Notably, conspecific cue-mediated larval settlement induction in C. gigas presents a complex system that requires an interplay of different glycans, disulfide bonds, amino acid groups, and phosphorylation crosstalk for recognition. These results may find application in the development of oyster aquacultures which could help recover declining marine species and as targets of anti-fouling agents

Uptake of Iodine and Bromine by Ion-Exchange Resins in Aqueous Solution

The uptakes of molecular iodine and bromine by both strong acid cation (Dowex 50W-X4 and X8) and strong base anion (Dowex 1-X4 and X8) exchange resins have been studied in aqueous solutions at 25°C. An empirical formula for the amount of solute taken up by the resin in mmol per gram of dry resin, Q, as a function of the solute concentration in M (mol dm-3), C, was derived. Direct proportional relationships between Q and C have been found, except for the　bromine-anion exchanger system. In contrast to the cation-exchange resin, the anion exchanger exhibits extremely high affinity for I2 and Br2

Hormonal regulation of temperature-induced growth in Arabidopsis

[EN] Successful plant survival depends upon the proper integration of information from the environment with endogenous cues to regulate growth and development. We have investigated the interplay between ambient temperature and hormone action during the regulation of hypocotyl elongation, and we have found that gibberellins (GAs) and auxin are quickly and independently recruited by temperature to modulate growth rate, whereas activity of brassinosteroids (BRs) seems to be required later on. Impairment of GA biosynthesis blocked the increased elongation caused at higher temperatures, but hypocotyls of pentuple DELLA knockout mutants still reduced their response to higher temperatures when BR synthesis or auxin polar transport were blocked. The expression of several key genes involved in the biosynthesis of GAs and auxin was regulated by temperature, which indirectly resulted in coherent variations in the levels of accumulation of nuclear GFP-RGA (repressor of GA1) and in the activity of the DR5 reporter. DNA microarray and genetic analyses allowed the identification of the transcription factor PIF4 (phytochrome-interacting factor 4) as a major target in the promotion of growth at higher temperature. These results suggest that temperature regulates hypocotyl growth by individually impinging on several elements of a pre-existing network of signaling pathways involving auxin, BRs, GAs, and PIF4.We thank G. Choi (KAIST, Daejeon, South Korea), C. Fankhauser (University of Lausanne, Lausanne, Switzerland), T. Guilfoyle (Department of Biochemistry, University of Missouri, MO, USA), N. P. Harberd (Department of Plant Sciences, University of Oxford, Oxford, UK), E. Huq (University of Texas, Austin, TX, USA), T-p Sun (Department of Biology, Duke University, Durham, USA), S. G. Thomas (Rothamsted Research, Hertfordshire, UK), G. Vert (Institut de Biologie Integrative des Plantes, Montpellier, France), Z. Y. Wang (Department of Plant Biology, Carnegie Institution, Stanford, USA), Y. Yin (Plant Science Institute, Iowa State University, Ames, IA, USA), and the Arabidopsis Biological Resource Center for seeds; and X. W. Deng (Yale University, New Haven, CT, USA) for antibodies against RPT5. We also thank Dr Jorge Casal (Universidad de Buenos Aires, Buenos Aires, Argentina) for helpful suggestions on this work. Work in the authors' laboratories is funded by grant BIO2007-60923 from the Spanish Ministry of Science and Innovation and by grant 167890/110 from the Norwegian Research Council. JG-B was supported by a JAE pre-doctoral fellowship from CSIC.Stavang, JA.; Gallego-Bartolomé, J.; Gómez Jiménez, MD.; Yoshida, S.; Asami, T.; Olsen, JE.; García-Martínez, JL.... (2009). Hormonal regulation of temperature-induced growth in Arabidopsis. The Plant Journal. 60(4):589-601. https://doi.org/10.1111/j.1365-313X.2009.03983.x58960160

Transcriptome Dynamics of an Oyster Larval Response to a Conspecific Cue-Mediated Settlement Induction in the Pacific Oyster Crassostrea gigas

The molecular mechanisms underlying the conspecific cue-mediated larval settlement in Crassostrea gigas is not yet fully understood. In this study, we described and compared the transcriptomes of competent pediveligers (Pedi) and conspecific cue-induced postlarvae (PL). A total of 2383 candidate transcripts were identified: 740 upregulated and 1643 downregulated transcripts, after settlement. Gene Ontology analysis revealed active chitin binding, calcium ion binding, and extracellular region processes in both stages. Results showed that the differential expression trend of six candidate transcripts were consistent between the quantitative real-time PCR and transcriptome data. The differential transcript expression related to shell formation showed closely linked dynamics with a gene regulatory network that may involve the interplay of various hormone receptors, neurotransmitters, and neuropeptide receptors working together in a concerted way in the Pedi and PL stages. Our results highlight the transcriptome dynamics underlying the settlement of oysters on conspecific adult shells and demonstrate the potential use of this cue as an attractant for wild and hatchery-grown oyster larval attachment on artificial substrates. It also suggests the possible involvement of an ecdysone signal pathway that may be linked to a neuroendocrine-biomineralization crosstalk in C. gigas settlement

DNA methylation dynamics in mouse preimplantation embryos revealed by mass spectrometry

Following fertilization in mammals, paternal genomic 5-methyl-2′-deoxycytidine (5 mC) content is thought to decrease via oxidation to 5-hydroxymethyl-2′-deoxycytidine (5 hmC). This reciprocal model of demethylation and hydroxymethylation is inferred from indirect, non-quantitative methods. We here report direct quantification of genomic 5 mC and 5 hmC in mouse embryos by small scale liquid chromatographic tandem mass spectrometry (SMM). Profiles of absolute 5 mC levels in embryos produced by in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) were almost identical. By 10 h after fertilization, 5 mC levels had declined by ∼40%, consistent with active genomic DNA demethylation. Levels of 5 mC in androgenotes (containing only a paternal genome) and parthenogenotes (containing only a maternal genome) underwent active 5 mC loss in the first 6 h, showing that both parental genomes can undergo demethylation independently. We found no evidence for net loss of 5 mC 10-48 h after fertilization, implying that any passive â€'demethylation' following DNA replication was balanced by active 5 mC maintenance methylation. However, levels of 5 mC declined during development after 48 h, to 1% (measured as a fraction of G-residues) in blastocysts (∼96 h). 5 hmC levels were consistently low (<0. 2% of G-residues) throughout development in normal diploid embryos. This work directly quantifies the dynamics of global genomic DNA modification in mouse preimplantation embryos, suggesting that SMM will be applicable to other biomedical situations with limiting sample sizes

Photometry and Polarimetry of 2010 XC15_{15}: Observational Confirmation of E-type Near-Earth Asteroid Pair

Asteroid systems such as binaries and pairs are indicative of physical properties and dynamical histories of the Small Solar System Bodies. Although numerous observational and theoretical studies have been carried out, the formation mechanism of asteroid pairs is still unclear, especially for near-Earth asteroid (NEA) pairs. We conducted a series of optical photometric and polarimetric observations of a small NEA 2010 XC$_{15}$ in 2022 December to investigate its surface properties. The rotation period of 2010 XC$_{15}$ is possibly a few to several dozen hours and color indices of 2010 XC$_{15}$ are derived as $g-r=0.435\pm0.008$, $r-i=0.158\pm0.017$, and $r-z=0.186\pm0.009$ in the Pan-STARRS system. The linear polarization degrees of 2010 XC$_{15}$ are a few percent at the phase angle range of 58$^{\circ}$ to 114$^{\circ}$. We found that 2010 XC$_{15}$ is a rare E-type NEA on the basis of its photometric and polarimetric properties. Taking the similarity of not only physical properties but also dynamical integrals and the rarity of E-type NEAs into account, we suppose that 2010 XC$_{15}$ and 1998 WT$_{24}$ are of common origin (i.e., asteroid pair). These two NEAs are the sixth NEA pair and first E-type NEA pair ever confirmed, possibly formed by rotational fission. We conjecture that the parent body of 2010 XC$_{15}$ and 1998 WT$_{24}$ was transported from the main-belt through the $\nu_6$ resonance or Hungaria region.Comment: Resubmitted to AAS Journals. Any comments are welcom

Novel method for detection of pancreatic beta cell death using cell-free DNA

In people with type１ diabetes（T１D）, biomarkers that can sensitively and quantitatively evaluate injury of pancreatic beta cell are required in order to predict the onset of the disease at an early stage and to provide interventions to prevent the progression of the disease. We developed a new method for quantifying pancreatic beta cell-derived insulin DNA in circulation that combines bisulfite conversion and Amplification Refractory Mutation System（ARMS）PCR, which can be performed using a conventional real-time PCR system. We applied this method to T１D patients and healthy adults, both could be detected in about ３０％ of cases. The results in healthy adults indicate that this method may have sensitivity to detect the turnover of pancreatic beta cells at physiological conditions. In post-onset T１D patients, there were many negatives because the amount of residual pancreatic beta cells was extremely small. However, in some cases with a short duration of the disease, pancreatic beta cell-derived insulin DNA was detected in negative correlation between the duration of the disease, that suggested the residual pancreatic beta cells continue to be slowly destroyed. It was demonstrated that the time course of pathophysiology in T１D could be understood using this method