Cellular response of Parachlorella kessleri to a solid surface culture environment.

Attached culture allows high biomass productivity and is a promising biomass cultivating system because neither a huge facility area nor a large volume of culture medium are needed. This study investigates photosynthetic and transcriptomic behaviors in Parachlorella kessleri cells on a solid surface after their transfer from liquid culture to elucidate the physiological and gene-expression regulatory mechanisms that underlie their vigorous proliferation. The chlorophyll content shows a decrease at 12 h after the transfer; however, it has fully recovered at 24 h, suggesting temporary decreases in the amounts of light harvesting complexes. On PAM analysis, it is demonstrated that the effective quantum yield of PSII decreases at 0 h right after the transfer, followed by its recovery in the next 24 h. A similar changing pattern is observed for the photochemical quenching, with the PSII maximum quantum yield remaining at an almost unaltered level. Non-photochemical quenching was increased at both 0 h and 12 h after the transfer. These observations suggest that electron transfer downstream of PSII but not PSII itself is only temporarily damaged in solid-surface cells just after the transfer, with light energy in excess being dissipated as heat for PSII protection. It thus seems that the photosynthetic machinery acclimates to high-light and/or dehydration stresses through its temporal size-down and functional regulation that start right after the transfer. Meanwhile, transcriptomic analysis by RNA-Seq demonstrates temporary upregulation at 12 h after the transfer as to the expression levels of many genes for photosynthesis, amino acid synthesis, general stress response, and ribosomal subunit proteins. These findings suggest that cells transferred to a solid surface become stressed immediately after transfer but can recover their high photosynthetic activity through adaptation of photosynthetic machinery and metabolic flow as well as induction of general stress response mechanisms within 24 h.

One of the isoamylase isoforms, CMI294C, is required for semi-amylopectin synthesis in the rhodophyte Cyanidioschyzon merolae.

Most rhodophytes synthesize semi-amylopectin as a storage polysaccharide, whereas some species in the most primitive class (Cyanidiophyceae) make glycogen. To know the roles of isoamylases in semi-amylopectin synthesis, we investigated the effects of isoamylase gene (CMI294C and CMS197C)-deficiencies on semi-amylopectin molecular structure and starch granule morphology in Cyanidioschyzon merolae (Cyanidiophyceae). Semi-amylopectin content in a CMS197C-disruption mutant (ΔCMS197C) was not significantly different from that in the control strain, while that in a CMI294C-disruption mutant (ΔCMI294C) was much lower than those in the control strain, suggesting that CMI294C is essential for semi-amylopectin synthesis. Scanning electron microscopy showed that the ΔCMI294C strain contained smaller starch granules, while the ΔCMS197C strain had normal size, but donut-shaped granules, unlike those of the control strain. Although the chain length distribution of starch from the control strain displayed a semi-amylopectin pattern with a peak around degree of polymerization (DP) 11-13, differences in chain length profiles revealed that the ΔCMS197C strain has more short chains (DP of 3 and 4) than the control strain, while the ΔCMI294C strain has more long chains (DP ≥12). These findings suggest that CMI294C-type isoamylase, which can debranch a wide range of chains, probably plays an important role in semi-amylopectin synthesis unique in the Rhodophyta.

Acute respiratory distress syndrome relapsing in 10 months with an initial manifestation of polymyositis.

Autoimmune disorders are an important cause of acute respiratory distress syndrome (ARDS). We report a case of a patient with steroid-responsive ARDS that relapsed in 10 months with an initial manifestation of seronegative polymyositis. ARDS associated with polymyositis may develop earlier than myopathy and may relapse later.

Physiological Properties of Photoautotrophic Microalgae and Cyanobacteria Relevant to Industrial Biomass Production.

Photoautotrophic mass culture of microalgae is currently under investigation for social implementation, since such organisms are anticipated to be resources of alternative fuels and materials for reducing global warming. Production scale-up of culture systems and economy balance are great barriers for practical usage. In order to develop new culture systems such as attachment on solid surfaces or biofilms, we investigated various characteristics of photosynthesis in Chlorella, not only in liquid but also on filter membranes. In aquatic cultures, the photosynthetic rate was almost the same as the specific exponential growth rate at over 32 °C, suggesting that highly efficient cell growth was achieved at that temperature. The algal cells could fix about 50 mmol carbons per mole photons, at cloudy-day-level light intensities, which result to produce 1.2 g dry cell weight in calculation. Moreover, Chlorella could grow on a membrane surface at almost the same rate as in liquid. Similar tolerance to water deficiency was observed in a cyanobacterium, Synechocystis, in which gene expression responded in 30 min after the stress. Such a tolerance was also observed in other species of microalgae and cyanobacteria in photosynthesis.