mTORC1 regulates phagosome digestion of symbiotic bacteria for intracellular nutritional symbiosis in a deep-sea mussel

Phagocytosis is one of the methods used to acquire symbiotic bacteria to establish intracellular symbiosis. A deep-sea mussel, Bathymodiolus japonicus, acquires its symbiont from the environment by phagocytosis of gill epithelial cells and receives nutrients from them. However, the manner by which mussels retain the symbiont without phagosome digestion remains unknown. Here, we show that controlling the mechanistic target of rapamycin complex 1 (mTORC1) in mussels leads to retaining symbionts in gill cells. The symbiont is essential for the host mussel nutrition; however, depleting the symbiont's energy source triggers the phagosome digestion of symbionts. Meanwhile, the inhibition of mTORC1 by rapamycin prevented the digestion of the resident symbionts and of the engulfed exogenous dead symbionts in gill cells. This indicates that mTORC1 promotes phagosome digestion of symbionts under reduced nutrient supply from the symbiont. The regulation mechanism of phagosome digestion by mTORC1 through nutrient signaling with symbionts is key for maintaining animal-microbe intracellular nutritional symbiosis.

Evidence of global chlorophyll d

Although analyses of chlorophyll d (Chl d)-dominated oxygenic photosystems have been conducted since their discovery 12 years ago, Chl d distribution in the environment and quantitative importance for aquatic photosynthesis remain to be investigated. We analyzed the pigment compositions of surface sediments and detected Chl d and its derivatives from diverse aquatic environments. Our data show that the viable habitat for Chl d-producing phototrophs extends across salinities of 0 to 50 practical salinity units and temperatures of 1 degrees to 40 degrees C, suggesting that Chl d production can be ubiquitously observed in aquatic environments that receive near-infrared light. The relative abundances of Chl d derivatives over that of Chl a derivatives in the studied samples are up to 4%, further suggesting that Chl d-based photosynthesis plays a quantitatively important role in the aquatic photosynthesis.

Stability and degradation pattern of cefpirome (HR 810) in aqueous solution

The stability and degradation pathways of a new semi-synthetic cephalosporin, 1-[[(6R,7R)-7-[2-(2-amino-4-thiazolyl)glyoxylamido]-2-carboxy-8-ox o-5-thia-1-azabicyclo[4.2.0]oct-2-en-3-yl]methyl]-6,7-dihydro-5H-1- pyridinium hydroxide, inner salt, 7(2)-(Z)-(O-methyloxime) sulfate (cefpirome sulfate, HR 810), were studied. Cefpirome in various buffer solutions was allowed to stand at 40 degrees C and its degradation patterns were investigated by high performance liquid chromatography. Cefpirome was stable in the region of pH 4-7 and slightly unstable beyond this range. In aqueous solution from the neutral to alkaline regions, the produced degradation products were: 1- [[(6R,7S)-7-[2-(2-amino-4-thiazolyl)glyoxylamido]-2-carboxy-8-oxo -5-thia-1-azabicyclo[4.2.0]oct-2-en-3-yl]methyl]-6,7-dihydro-5 H-1- pyridinium hydroxide, inner salt, 7(2)-(Z)-(O-methyloxime) (epi-cefpirome); 1-[[(6R,7R)-7-[2-(2-amino-4-thiazolyl)glyoxylamido]-2-carboxy-8-ox o-5-thia-1-azabicyclo[4.2.0]oct-3-en-3-yl]methyl]-6,7-dihydro-5H-1- pyridinum hydroxide, inner salt, 7(2)-(Z)-(O-methyloxime) (delta 2-cefpirome); 2-[[(2-amino-4-thiazolyl)((Z)-methoxy-imino)acetyl]amino]acetaldehyde; and 6,7-dihydro-5H-1-pyrindine. On the other hand, 1-[[(6R,7R)-7-[2-(2- amino-4-thiazolyl)glyoxylamido]-2-carboxy-8-oxo-5-thia-1- azabicyclo[4.2.0]oct-2-en-3-yl]methyl]-6,7-dihydro-5H-1-pyridinium++ + hydroxide, inner salt, 7(2)-(E)-(O-methyloxime) (anti-cefpirome), 2-[[(2- amino-4-thiazolyl)-((Z)-methoxyimino)-acetyl]aminomethyl]-1,2,5,7- tetrahydro-7-oxo-4H-furo[3,4-D]-[1,3]thiazine, and 6,7-dihydro-5H-1- pyrindine were produced in strongly acidic solution or under irradiation by artificial sunlight.

Increased uptake of 5-fluorouracil by Ehrlich ascites tumor cells with some additives and metabolite analysis

We studied the uptake of radioactive 5-fluorouracil (FUra) by the intact cells of Ehrlich ascites tumor in the presence of various coreactants with FUra such as uridine (Urd), deoxyuridine (dUrd), ribose 1-phosphate (Rib1P), and deoxyribose 1-phosphate (dRib1P). Radioactivity uptake by the cells was increased when FUra-6-14C was incubated with Rib1P or dRib1P, while the uptake was not stimulated with Urd or dUrd. The increased formation of antineoplastic ribo- and deoxyribo-nucleotides of FUra in the acid-soluble fraction was also observed in the same incubation with Rib1P or dRib1P. Also, some detergents, ethylenediaminetetraacetic acid (EDTA), adenosine 5'-triphosphate (ATP), and polyamines were examined. EDTA stimulated the uptake of radioactivity from the FUra by the cells. However, the other compounds exhibited no effect on the uptake of FUra alone or FUra plus dRib1P, except of ATP showing somewhat increase of radioactivity uptake. The above results suggest that the coadministration of FUra together with Rib1P or/and dRib1P, which are stimulants for the formation of FUra-deoxynucleotides from FUra, may be able to potentiate the chemotherapeutic effect of FUra.