The Hyper Suprime-Cam SSP survey: Overview and survey design

Hyper Suprime-Cam (HSC) is a wide-field imaging camera on the prime focus of the 8.2-m Subaru telescope on the summit of Mauna Kea in Hawaii. A team of scientists from Japan, Taiwan, and Princeton University is using HSC to carry out a 300-night multi-band imaging survey of the high-latitude sky. The survey includes three layers: the Wide layer will cover 1400 deg2 in five broad bands (grizy), with a 5 σ point-source depth of r ≈ 26. The Deep layer covers a total of 26 deg2 in four fields, going roughly a magnitude fainter, while the UltraDeep layer goes almost a magnitude fainter still in two pointings of HSC (a total of 3.5 deg2). Here we describe the instrument, the science goals of the survey, and the survey strategy and data processing. This paper serves as an introduction to a special issue of the Publications of the Astronomical Society of Japan, which includes a large number of technical and scientific papers describing results from the early phases of this survey

Stress Response of Mesosutterella multiformis Mediated by Nitrate Reduction

Bacterial stress responses are closely associated with the survival and colonization of anaerobes in the human gut. Mesosutterella multiformis JCM 32464T is a novel member of the family Sutterellaceae, an asaccharolytic bacterium. We previously demonstrated energy generation via heme biosynthesis, which is coupled with nitrate reductase. Here, physiological and morphological changes in M. multiformis induced by exposure to nitrate were investigated. The ability of M. multiformis to reduce nitrate was determined using a colorimetric assay. A unique morphology was observed during nitrate reduction under anaerobic conditions. The association between nitrate concentration and cell size or cellular fatty acid composition was evaluated. Nitrate-induced responses of M. multiformis were compared to those of related species. An increase in cellular filamentation and the ratio of saturated: unsaturated fatty acids was mediated specifically by nitrate. This indicates a decrease in cell fluidity and low leakage. Furthermore, a similar response was not observed in other related species cultured in the presence of nitrate. Hence, the nitrate-induced stress response in new anaerobes such as M. multiformis was demonstrated. The response could also be involved in the conservation of menaquinones and the maximization of nitrate reduction

Needle length control and the secretion substrate specificity switch are only loosely coupled in the type III secretion apparatus of Shigella

The type III secretion apparatus (T3SA), which is evolutionarily and structurally related to the bacterial flagellar hook basal body, is a key virulence factor used by many Gram-negative bacteria to inject effector proteins into host cells. A hollow extracellular needle forms the injection conduit of the T3SA. Its length is tightly controlled to match specific structures at the bacterial and host-cell surfaces but how this occurs remains incompletely understood. The needle is topped by a tip complex, which senses the host cell and inserts as a translocation pore in the host membrane when secretion is activated. The interaction of two conserved proteins, inner-membrane Spa40 and secreted Spa32, respectively, in Shigella, is proposed to regulate needle length and to flick a type III secretion substrate specificity switch from needle components/Spa32 to translocator/effector substrates. We found that, as in T3SAs from other species, substitution N257A within the conserved cytoplasmic NPTH region in Spa40 prevented its autocleavage and substrate specificity switching. Yet, the spa40(N257A) mutant made only slightly longer needles with a few needle tip complexes, although it could not form translocation pores. On the other hand, Δspa32, which makes extremely long needles and also formed only few tip complexes, could still form some translocation pores, indicating that it could switch substrate specificity to some extent. Therefore, loss of needle length control and defects in secretion specificity switching are not tightly coupled in either a Δspa32 mutant or a spa40(N257A) mutant