Scale invariance of cell size fluctuations in starving bacteria

In stable environments, cell size fluctuations are thought to be governed by simple physical principles, as suggested by recent findings of scaling properties. Here, by developing a microfluidic device and using E. coli, we investigate the response of cell size fluctuations against starvation. By abruptly switching to non-nutritious medium, we find that the cell size distribution changes but satisfies scale invariance: the rescaled distribution is kept unchanged and determined by the growth condition before starvation. These findings are underpinned by a model based on cell growth and cell cycle. Further, we numerically determine the range of validity of the scale invariance over various characteristic times of the starvation process, and find the violation of the scale invariance for slow starvation. Our results, combined with theoretical arguments, suggest the relevance of the multifork replication, which helps retaining information of cell cycle states and may thus result in the scale invariance.Comment: 15+23 pages, 5+11 figures and 2 table

Color discrimination at the spatial resolution limit in a swallowtail butterfly, Papilio xuthus

Spatial resolution of insect compound eyes is much coarser than that of humans: a single pixel of the human visual system covers about 0.008° whereas that of diurnal insects is typically about 1.0°. Anatomically, the pixels correspond to single cone outer segments in humans and to single rhabdoms in insects. Although an outer segment and a rhabdom are equivalent organelles containing visual pigment molecules, they are strikingly different in spectral terms. The cone outer segment is the photoreceptor cell part that expresses a single type of visual pigment, and is therefore monochromatic. On the other hand, a rhabdom is composed of several photoreceptor cells with different spectral sensitivities and is therefore polychromatic. The polychromatic organization of the rhabdom suggests that insects can resolve wavelength information in a single pixel, which is an ability that humans do not have. We first trained the Japanese yellow swallowtail butterfly Papilio xuthus to feed on sucrose solution at a paper disk of certain color. We then let the trained butterflies discriminate disks of the training color and grey disks each presented in a Y-maze apparatus. Papilio correctly selected the colored disk when the visual angle was greater than 1.18° for blue, 1.53° for green or 0.96° for red: they appeared to see colors in single pixels to some extent. This ability may compensate their rather low spatial resolution

Percutaneous Endoscopic Gastrostomy, Duodenostomy and Jejunostomy

Although enteral feeding by nasal gastric tube is popular for the patients who have a swallowing disability and require long-term nutritional support, but have intact gut, this tube sometimes causes aspiration pneumonia or esophageal ulcer. For these patients, conventional techniques for performance of a feeding gastrostomy made by surgical laparotomy have been used so far. However, these patients are frequently poor anesthetic and operative risks. Percutaneous endoscopic gastrostomy (PEG) which can be accomplished with local anesthesia and without the necessity for laparotomy has become popular in the clinical treatment for these patients. PEG was performed in 31 cases, percutaneous endoscopic duodenostomy (PED) in 1 case, and percutaneous endoscopic jejunostomy (PEJ) in 2 cases. All patients were successfully placed, and no major complication and few minor complications (9%) were experienced in this procedure. After this procedure, some patients could discharge their sputa easily and their pneumonia subsided. PED and PEJ for the patients who had previously received gastrostomy could also be done successfully with great care. Our experience suggests that PEG, PED, and PEJ are rapid, safe, and useful procedures for the patients who have poor anesthetic or poor operative risks

(3,6-Dimeth­oxy­naphthalen-2-yl)(phen­yl)methanone

In the title compound, C19H16O3, the dihedral angle between the naphthalene ring system and the phenyl ring is 68.32 (5)°. The bridging carbonyl C—C(=O)—C plane makes a dihedral angle of 54.32 (5)° with the naphthalene ring system and 21.45 (6)° with the phenyl ring. An inter­molecular C—H⋯O hydrogen bond exists between the H atom of one meth­oxy group and the O atom of the second meth­oxy group in an adjacent mol­ecule. The crystal packing is additionally stabilized by a weak C—H⋯O inter­molecular inter­action between an H atom of the naphthalene ring and the O atom of the carbonyl group