Activation of SnRK2 by Raf-like kinase ARK represents a primary mechanism of ABA and abiotic stress responses

The Raf-like protein kinase abscisic acid (ABA) and abiotic stress-responsive Raf-like kinase (ARK) previously identified in the moss Physcomitrium (Physcomitrella) patens acts as an upstream regulator of subgroup III SNF1-related protein kinase2 (SnRK2), the key regulator of ABA and abiotic stress responses. However, the mechanisms underlying activation of ARK by ABA and abiotic stress for the regulation of SnRK2, including the role of ABA receptor-associated group A PP2C (PP2C-A), are not understood. We identified Ser1029 as the phosphorylation site in the activation loop of ARK, which provided a possible mechanism for regulation of its activity. Analysis of transgenic P. patens ark lines expressing ARK-GFP with Ser1029-to-Ala mutation indicated that this replacement causes reductions in ABA-induced gene expression, stress tolerance, and SnRK2 activity. Immunoblot analysis using an anti-phosphopeptide antibody indicated that ABA treatments rapidly stimulate Ser1029 phosphorylation in the wild type (WT). The phosphorylation profile of Ser1029 in ABA-hypersensitive ppabi1 lacking protein phosphatase 2C-A (PP2C-A) was similar to that in the WT, whereas little Ser1029 phosphorylation was observed in ABA-insensitive ark missense mutant lines. Furthermore, newly isolated ppabi1 ark lines showed ABA-insensitive phenotypes similar to those of ark lines. Therefore, ARK is a primary activator of SnRK2, preceding negative regulation by PP2C-A in bryophytes, which provides a prototype mechanism for ABA and abiotic stress responses in plants.

Phosphorylation in the activation loop of the Raf-like kinase ARK is critical for SNF1-related protein kinase2 regulation during abscisic acid responses in the moss Physcomitrium (Physcomitrella) patens.     

Primary role of NADH formed by glucose dehydrogenase in ATP provision at the early stage of spore germination in Bacillus megaterium QM B1551

Metabolic events involved in energy metabolism were studied in order to evaluate the ATP-forming ability of Bacillus megaterium QM B1551 spores at the very early stage of germination. When heat-activated spores were germinated on glucose as a sole substrate, its oxidation into gluconate (catalyzed by glucose dehydrogenase, EC 1.1.1.47), the accompanying NADH formation, oxygen uptake, and RNA synthesis were initiated immediately after germination, even when anaerobic breakdown of 3-phosphoglycerate (an ATP source for spores) and the subsequent glucose metabolism via the phosphorylating pathway were impaired by potassium fluoride (KF). In contrast, fructose metabolism and the accompanying metabolic events did not begin until a few minutes after triggering of germination, and those events were entirely abolished by KF, indicating that fructose metabolism is initiated exclusively via its phosphorylation by the ATP derived from endogenous 3-phosphoglycerate. Thus those results provided further evidence for our previous proposal (Otani et al (1987) Microbiol. Immunol. 31: 967-974; Sano et al (1988) Biochem. Biophys. Res. Commun. 151: 48-52) that the first molecules of ATP in germinating spores can be efficiently generated via aerobic oxidation of NADH, which is formed by glucose dehydrogenase. Fluorescence monitoring of NADH in germinating spores also supported this conclusion.     

A multicenter non-randomized,uncontrolled single arm trial for evaluation of the efficacy and the safety of the treatment with favipiravir for patients with severe fever with thrombocytopenia syndrome

Severe fever with thrombocytopenia syndrome (SFTS) is a bunyavirus infection with high mortality. Favipiravir has shown effectiveness in preventing and treating SFTS virus (SFTSV) infection in animal models. A multicenter non-randomized, uncontrolled single arm trial was conducted to collect data on the safety and the effectiveness of favipiravir in treatment of SFTS patients. All participants received favipiravir orally (first-day loading dose of 1800 mg twice a day followed by 800 mg twice a day for 7–14 days in total). SFTSV RT-PCR and biochemistry tests were performed at designated time points. Outcomes were 28-day mortality, clinical improvement, viral load evolution, and adverse events (AEs). Twenty-six patients were enrolled, of whom 23 were analyzed. Four of these 23 patients died of multi-organ failure within one week (28-day mortality rate: 17.3%). Oral favipiravir was well tolerated in the surviving patients. AEs (abnormal hepatic function and insomnia) occurred in about 20% of the patients. Clinical symptoms improved in all patients who survived from a median of day 2 to day10. SFTSV RNA levels in the patients who died were significantly higher than those in the survivors (p = 0.0029). No viral genomes were detectable in the surviving patients a median of 8 days after favipiravir administration. The 28-day mortality rate in this study was lower than those of the previous studies in Japan. The high frequency of hepatic dysfunction as an AE was observed. However, it was unclear whether this was merely a side effect of favipiravir, because liver disorders are commonly seen in SFTS patients. The results of this trial support the effectiveness of favipiravir for patients with SFTS.     

Membrane lipid remodeling is required for photosystem II function under low CO2

Membrane lipid remodeling in plants and microalgae has a crucial role in their survival under nutrient-deficient conditions. Aquatic microalgae have low access to CO₂, an essential carbon source for photosynthetic assimilates; however, 70–90 mol% of their membrane lipids are sugar-derived lipids (glycolipids) such as monogalactosyldiacylglycerol (MGDG). In this study, we discovered a new system of membrane lipid remodeling responding to CO₂ in Synechocystis sp. PCC 6803, a unicellular, freshwater cyanobacterium. As compared with higher CO₂ (HC; 1% CO₂), under ambient air (lower CO₂: LC), phosphatidylglycerol (PG) content was increased at the expense of MGDG content. To explore the biological significance of this alteration in content, we generated a transformant of Synechocystis sp. PCC 6803 overexpressing sll0545 gene encoding a putative phosphatidic acid phosphate (oxPAP), which produces diacylglycerol that is used for the synthesis of glycolipids, and examined the effect on membrane lipid remodeling and phototrophic growth responding to LC. Photosystem II (PSII) activity and growth rate were inhibited under LC in oxPAP cells. PG content was substantially reduced, and MGDG and sulfoquinovosyldiacylglycerol contents were increased in oxPAP cells as compared with control cells. These phenotypes in oxPAP cells were recovered under the HC condition or PG supplementation. Increased PG content may be required for proper functioning of PSII under LC conditions.     

Establishment of inbred rabbit strains

Two inbred rabbit strains, JWY-NIBS and NWY-NIBS, were established by full-sib mating in the Nippon Institute for Biological Science, Laboratory Animal Research Station. The origin, breeding history, and biological characteristics of the two inbred strains are as follows. 1. JWY-NIBS: Origin: Japanese white rabbits which had been originally kept at a farm near mount Takao, then transferred to another farm in Fuchu and maintained as a closed colony for a long time. Date of the first full-sib mating: April, 1964. Date of the 20th full-sib mating: June, 1981. Age of maturity: 7-month-old in females, 7.5-month-old in males. Body weight at maturity: 2.8-3.0 kg in females, 2.8-2.9 kg in males. Marker genes: Hemopexin; HxS. Esterase; Est-1s. alpha-Protein; F type. 2. NWY-NIBS: Origin: A strain III of New zealand white rabbits imported from the Jakson Laboratory in USA. Date of the first full-sib mating: November, 1967. Date of the 20th full-sib mating: July, 1982. Age of maturity: 7.5-month-old in females, 8-month-old in males. Body weight at maturity: 2.8-3.0 kg in females, 2.9-3.1 kg in males. Marker genes: Hemopexin; HxF. Esterase; Est-1S. Est-2f. alpha-Protein; S type.     

Glucose catabolism during germination of Bacillus megaterium spores.

When heat-activated spores of Bacillus megaterium germinated in glucose-containing medium, 10 to 30% of the glucose was found to be oxidized to gluconate.     

A new hexasaccharide chain isolated from bovine colostrum κ-casein taken at the time of parturition

The carbohydrate units linked to caseinoglycopeptide from colostrum taken 30 min after parturition were released as reduced oligosaccharides by alkaline borohydride treatment, and separated into four acidic oligosacchariditols (a hexa- (11.0%), penta- (38.5%), tetra- (35.5%) and a trisacchariditol (15.0%)). Structural studies showed that the hexasacchariditol was a new structure and had the chemical structure: NeuNAc-α-2-3-Gal-β-1-3-[NeuNAc-α-2-3-Gal-β-1-4-GlcNAc-β-1-6-]-N-acetylgalactosaminitol(GalNAcItol). The other three oligosacchariditols were shown to be NeuNAc-α-2-3-Gal-β-1-3-[Gal-β-1-4-GlcNac- β-1-6-]-GalNAcItol, NeuNAc-α-2-3-Gal-β-1-3-[NeuNAc-α-2-6-]-GalNAcItol and NeuNAc-α-2-3-Gal-β-1-3- GalNAcItol, which were identical with those found previously in colostrum κ-casein taken 6 h after parturition.