Gudgeon fish with and without genetically determined countershading coexist in heterogeneous littoral environments of an ancient lake

Countershading, characterized by a darker dorsal surface and lighter ventral surface, is common among many animals. This dorsoventral pigment polarity is often thought to be adaptive coloration for camouflage. By contrast, noncountershaded (melanistic) morphs often occur within a species due to genetic color polymorphism in terrestrial animals. However, the polymorphism with either countershaded or melanistic morphs is poorly known in wild aquatic animals. This study explored the genetic nature of diverged color morphs of a lineage of gudgeon fish (genus Sarcocheilichthys) in the ancient Lake Biwa and propose this system as a novel model for testing hypotheses of functional aspects of countershading and its loss in aquatic environments. This system harbors two color morphs that have been treated taxonomically as separate species; Sarcocheilichthys variegatus microoculus which occurs throughout the littoral zone and Sarcocheilichthys biwaensis which occurs in and around rocky areas. First, we confirmed that the divergence of dorsoventral color patterns between the two morphs is under strict genetic control at the levels of chromatophore distribution and melanin‐related gene expression under common garden rearing. The former morph displayed sharp countershading coloration, whereas the latter morph exhibited a strong tendency toward its loss. The crossing results indicated that this divergence was likely controlled by a single locus in a two‐allele Mendelian inheritance pattern. Furthermore, our population genomic and genome‐wide association study analyses detected no genome‐wide divergence between the two morphs, except for one region near a locus that may be associated with the color divergence. Thus, these morphs are either in a state of intraspecific color polymorphism or two incipient species. Evolutionary forces underlying this polymorphism appear to be associated with heterogeneous littoral environments in this lake. Future ecological genomic research will provide insight into adaptive functions of this widespread coloration, including the eco‐evolutionary drivers of its loss, in the aquatic world.     

Endomorphin-1, an endogenous mu-opioid receptor-selective agonist, stimulates oxygen consumption in mice.

This study was undertaken to investigate the effect of endogenous mu-receptor-selective peptide endomorphin 1, administered intracerebroventricularly, on oxygen consumption in mice. The intracerebroventricular injection of endomorphin 1 (3-30 nmol) significantly increased oxygen consumption in unrestrained mice. The effect of endomorphin 1 (30 nmol) was significantly antagonized by the simultaneous intraperitoneal administration of naloxone (100 nmol). These results suggest that endomorphin 1 stimulates oxygen consumption, and that the mu-opioid receptor influences energy balance in mice.     

Climatic gradients of arms race coevolution

In nature, spatiotemporally dynamic coevolutionary processes play major roles in the foundation and maintenance of biodiversity. Here, we examined the arms race coevolution involving a seed-eating weevil with a long snout and its camellia plant host with a thick fruit coat (pericarp) throughout the marked climatic gradient observed across the Japanese islands. Results demonstrated that female weevils, which bored holes through camellia pericarps to lay eggs into seeds, had evolved much longer snouts than males, especially in areas in which Japanese camellia pericarps were very thick. The thickness of the plant pericarp was heritable, and the camellia plant evolved a significantly thicker pericarp on islands with the weevil than on islands without it. Across populations with weevils, resource allocation to plant defense increased with increasing annual mean temperature or annual precipitation, thereby geographically differentiating the evolutionary and ecological interactions between the two species. Given that the coevolutionary relationship exhibited appreciable variation across a relatively small range of annual mean temperatures, ongoing global climatic change can dramatically alter the coevolutionary process, thereby changing the ecological interaction between these species.     

Inhibition of Achromobacter protease I by lysinal derivatives.

Z-Val-, Z-Pro-, Z-Leu-Leu-, and Z-Leu-Pro-lysinals and BZ-DL-lysinal were chemically synthesized and tested as novel inhibitors for Achromobacter protease I (API), a lysine-specific serine protease. Among the lysinal derivatives tested, Z-Val-lysinal was the most potent competitive inhibitor, its Ki being estimated as 6.5 nM in an esterolytic assay with Tos-Lys-OMe. In an amidolytic assay, Z-Leu-Leu-lysinal was the most potent inhibitor and the apparent mode of inhibition was non-competitive. The Kis of the other lysinal derivatives in both esterolytic and amidolytic assays were more than 10(3) times lower than that of leupeptin. Z-Val-lysinol, lacking the aldehyde group, was a poor competitive inhibitor. These results suggest that acyl-, acylaminoacyl-, and acylpeptidyllysinals function as a transition-state inhibitor for Achromobacter protease I.     

Meristem-specific gene expression directed by the promoter of the S-phase-specific gene,cyc07, in transgenic Arabidopsis

A genomic clone for the cyc07 gene, which is expressed specifically at the S phase during the cell cycle in synchronous cultures of periwinkle (Catharanthus roseus) cells, was isolated. Determination of the nucleotide sequence of the clone revealed that the cyc07 gene consists of seven exons separated by six introns. Genomic Southern analysis indicated that the cyc07 gene is present as a single copy per haploid genome in periwinkle. Expression of related genes was detected in a wide range of other plants. Transgenic Arabidopsis plants were generated that expressed the gene for -glucuronidase (GUS) under the control of the promoter of the cyc07 gene. The tissue-specific pattern of expression directed by the promoter was investigated by analysis of GUS activity. Histochemical tests demonstrated that 589 bp of the 5-upstream sequence of the cyc07 gene could direct specifical expression of the GUS reporter gene in meristematic tissues in transgenic plants. The spatial pattern of expression directed by the promoter was closely correlated with meristematic activity and cell proliferation, suggesting an association between the function of the cyc07 gene and cell proliferation.     

Constitutively active parathyroid hormone receptor signaling in cells in osteoblastic lineage suppresses mechanical unloading-induced bone resorption

Multiple signaling pathways participate in the regulation of bone remodeling, and pathological negative balance in the regulation results in osteoporosis. However, interactions of signaling pathways that act comprehensively in concert to maintain bone mass are not fully understood. We investigated roles of parathyroid hormone receptor (PTH/PTHrP receptor) signaling in osteoblasts in unloading-induced bone loss using transgenic mice. Hind limb unloading by tail suspension reduced bone mass in wild-type mice. In contrast, signaling by constitutively active PTH/PTHrP receptor (caPPR), whose expression was regulated by the osteoblast-specific Col1a1 promoter (Col1a1-caPPR), suppressed unloading-induced reduction in bone mass in these transgenic mice. In Col1a1-caPPR transgenic (Tg) mice, hind limb unloading suppressed bone formation parameters in vivo and mineralized nodule formation in vitro similarly to those observed in wild-type mice. In addition, serum osteocalcin levels and mRNA expression levels of type I collagen, Runx2 and Osterix in bone were suppressed by unloading in both wild-type mice and Tg mice. However, in contrast to unloading-induced enhancement of bone resorption parameters in wild-type mice, Col1a1-caPPR signaling suppressed, rather than enhanced, osteoclast number and osteoclast surface as well as urinary deoxypyridinoline excretion upon unloading. Col1a1-caPPR signaling also suppressed mRNA expression levels of RANK and c-fms in bone upon unloading. Although the M-CSF and monocyte chemoattractant protein 1 (MCP-1) mRNA levels were enhanced in control Tg mice, these levels were suppressed in unloaded Tg mice. These results indicated that constitutive activation of PTH/PTHrP receptor signaling in osteoblastic cells suppresses unloading-induced bone loss specifically through the regulation of osteoclastic activity.     

Expansion of GAA trinucleotide repeats in mammals

We have previously shown that GAA trinucleotide repeats have undergone significant expansion in the human genome. Here we present the analysis of the length distribution of all 10 nonredundant trinucleotide repeat motifs in 20 complete eukaryotic genomes (6 mammalian, 2 nonmammalian vertebrates, 4 arthropods, 4 fungi, and 1 each of nematode, amoebozoa, alveolate, and plant), which showed that the abundance of large expansions of GAA trinucleotide repeats is specific to mammals. Analysis of human-chimpanzee-gorilla orthologs revealed that loci with large expansions are species-specific and have occurred after divergence from the common ancestor. PCR analysis of human controls revealed large expansions at multiple human (GAA)(30+) loci; nine loci showed expanded alleles containing >65 triplets, analogous to disease-causing expansions in Friedreich ataxia, including two that are in introns of genes of unknown function. The abundance of long GAA trinucleotide repeat tracts in mammalian genomes represents a significant mutation potential and source of interindividual variability.     

A novel mutant (transthyretin Ile-50) related to amyloid polyneuropathy. Single-strand conformation polymorphism as a new genetic marker.

DNA sequence polymorphisms in transthyretin (TTR) genes were investigated by single-strand conformation polymorphism (SSCP) analysis of polymerase chain reaction products. The amplified DNA fragments that encode each exon of the normal TTR gene showed two bands, representing the two complementary single strands of DNA. In one patient with amyloid polyneuropathy, the exon 3 DNA showed a unique, aberrant migration pattern. Direct sequencing analysis of the amplified exon 3 revealed a single base change (G-to-T), resulting in a novel amino acid substitution (Ser-50----Ile). We also present the SSCP patterns for five known Japanese TTR variants.     

Identification of the endostyle as a stem cell niche in a colonial chordate

Stem cell populations exist in "niches" that hold them and regulate their fate decisions. Identification and characterization of these niches is essential for understanding stem cell maintenance and tissue regeneration. Here we report on the identification of a novel stem cell niche in Botryllus schlosseri, a colonial urochordate with high stem cell-mediated developmental activities. Using in vivo cell labeling, engraftment, confocal microscopy, and time-lapse imaging, we have identified cells with stemness capabilities in the anterior ventral region of the Botryllus' endostyle. These cells proliferate and migrate to regenerating organs in developing buds and buds of chimeric partners but do not contribute to the germ line. When cells are transplanted from the endostyle region, they contribute to tissue development and induce long-term chimerism in allogeneic tissues. In contrast, cells from other Botryllus' regions do not show comparable stemness capabilities. Cumulatively, these results define the Botryllus' endostyle region as an adult somatic stem cell niche.     

Design and synthesis of novel pyrimido[4,5-b]azepine derivatives as HER2/EGFR dual inhibitors

A novel 7,6 fused bicyclic scaffold, pyrimido[4,5-b]azepine was designed to fit into the ATP binding site of the HER2/EGFR proteins. The synthesis of this scaffold was accomplished by an intramolecular Claisen-type condensation. As the results of optimization lead us to 4-anilino and 6-functional groups, we discovered 6-substituted amide derivative 19b, which has a 1-benzothiophen-4-yloxy group attached to the 4-anilino group. An X-ray co-crystal structure of 19b with EGFR demonstrated that the N-1 and N-3 nitrogens of the pyrimido[4,5-b]azepine scaffold make hydrogen-bonding interactions with the main chain NH of Met793 and the side chain of Thr854 via a water-mediated hydrogen bond network, respectively. In addition, the NH proton at the 9-position makes an additional hydrogen bond with the carbonyl group of Met793, as we expected. Compound 19b revealed potent HER2/EGFR kinase (IC₅₀: 24/36 nM) and BT474 cell growth (GI₅₀: 18 nM) inhibitory activities based on its pseudo-irreversible (PI) profile.