Dramatic Dietary Shift Maintains Sequestered Toxins in Chemically Defended Snakes

Unlike other snakes, most species of Rhabdophis possess glands in their dorsal skin, sometimes limited to the neck, known as nucho-dorsal and nuchal glands, respectively. Those glands contain powerful cardiotonic steroids known as bufadienolides, which can be deployed as a defense against predators. Bufadienolides otherwise occur only in toads (Bufonidae) and some fireflies (Lampyrinae), which are known or believed to synthesize the toxins. The ancestral diet of Rhabdophis consists of anuran amphibians, and we have shown previously that the bufadienolide toxins of frog-eating species are sequestered from toads consumed as prey. However, one derived clade, the Rhabdophis nuchalis Group, has shifted its primary diet from frogs to earthworms. Here we confirm that the worm-eating snakes possess bufadienolides in their nucho-dorsal glands, although the worms themselves lack such toxins. In addition, we show that the bufadienolides of R. nuchalis Group species are obtained primarily from fireflies. Although few snakes feed on insects, we document through feeding experiments, chemosensory preference tests, and gut contents that lampyrine firefly larvae are regularly consumed by these snakes. Furthermore, members of the R. nuchalis Group contain compounds that resemble the distinctive bufadienolides of fireflies, but not those of toads, in stereochemistry, glycosylation, acetylation, and molecular weight. Thus, the evolutionary shift in primary prey among members of the R. nuchalis Group has been accompanied by a dramatic shift in the source of the species’ sequestered defensive toxins

Discovery of Small-Scale Spiral Structures in the Disk of SAO 206462 (HD 135344B): Implications for the Physical State of the Disk from Spiral Density Wave Theory

We present high-resolution, H-band, imaging observations, collected with Subaru/HiCIAO, of the scattered light from the transitional disk around SAO 206462 (HD 135344B). Although previous sub-mm imagery suggested the existence of the dust-depleted cavity at r~46AU, our observations reveal the presence of scattered light components as close as 0.2" (~28AU) from the star. Moreover, we have discovered two small-scale spiral structures lying within 0.5" (~70AU). We present models for the spiral structures using the spiral density wave theory, and derive a disk aspect ratio of h~0.1, which is consistent with previous sub-mm observations. This model can potentially give estimates of the temperature and rotation profiles of the disk based on dynamical processes, independently from sub-mm observations. It also predicts the evolution of the spiral structures, which can be observable on timescales of 10-20 years, providing conclusive tests of the model. While we cannot uniquely identify the origin of these spirals, planets embedded in the disk may be capable of exciting the observed morphology. Assuming that this is the case, we can make predictions on the locations and, possibly, the masses of the unseen planets. Such planets may be detected by future multi-wavelengths observations.Comment: 8 pages, 5 figures, ApJL in press, typo correcte

High-Resolution Near-Infrared Polarimetry of a Circumstellar Disk around UX Tau A

We present H-band polarimetric imagery of UX Tau A taken with HiCIAO/AO188 on the Subaru Telescope. UX Tau A has been classified as a pre-transitional disk object, with a gap structure separating its inner and outer disks. Our imagery taken with the 0.15 (21 AU) radius coronagraphic mask has revealed a strongly polarized circumstellar disk surrounding UX Tau A which extends to 120 AU, at a spatial resolution of 0.1 (14 AU). It is inclined by 46 \pm 2 degree as the west side is nearest. Although SED modeling and sub-millimeter imagery suggested the presence of a gap in the disk, with the inner edge of the outer disk estimated to be located at 25 - 30 AU, we detect no evidence of a gap at the limit of our inner working angle (23 AU) at the near-infrared wavelength. We attribute the observed strong polarization (up to 66 %) to light scattering by dust grains in the disk. However, neither polarization models of the circumstellar disk based on Rayleigh scattering nor Mie scattering approximations were consistent with the observed azimuthal profile of the polarization degrees of the disk. Instead, a geometric optics model of the disk with nonspherical grains with the radii of 30 micron meter is consistent with the observed profile. We suggest that the dust grains have experienced frequent collisional coagulations and have grown in the circumstellar disk of UX Tau A.Comment: 20 pages, 8 figures, and 1 table. accepted to PAS

Thermally altered subsurface material of asteroid (162173) Ryugu

International audienc

Differential diagnosis of neonatal cholestasis by genetic testing: A case report

Introduction: Alagille syndrome (ALGS) is a cholestasis disorder with multiple organ dysfunction, including heart and kidney. The causative genes of ALGS are JAG1 and NOTCH2. Dysregulation of Notch signaling leads to defects in the developmental mechanisms of the bile ducts. Sometimes extrahepatic bile duct hypoplasia makes it difficult to differentiate ALGS from biliary atresia. The Kasai procedure for ALGS is associated with poor liver and patient outcomes. Therefore, it is important to differentiate ALGS from biliary atresia correctly. Case presentation: A 2-day-old female neonate was admitted to the neonatal intensive care unit due to poor feeding; blood tests on day 7 showed elevated direct bilirubin and total bile acids. Right hydronephrosis, peripheral pulmonary artery stenosis, butterfly vertebra, and posterior embryotoxon were observed, and ALGS was suspected from these findings. Duodenal fluid tests and biliary scintigraphy showed no bile excretion from the liver into the intestinal tract. These findings suggested biliary atresia, and to distinguish ALGS from biliary atresia, rapid JAG1 and NOTCH2 sequencing was performed preoperatively. We found a heterozygous de novo single nucleotide insertion mutation c.192dupC p.(Lys65GlnfsX8). Operative cholangiography showed that the common bile duct was patent, but the common hepatic duct was barely open, a finding consistent with type III-a-o biliary atresia. Because of the preoperative diagnosis of ALGS, Kasai procedure was omitted. Conclusion: Neonates and early infants with cholestasis with extrahepatic symptoms should be carefully examined, with genetic syndromes and biliary atresia considered differential diagnoses. Advances in genetic analysis methods are expected to facilitate early diagnosis of ALGS