Ionic stress is one of the most important components of salinity and is brought about by excess Na+ accumulation, especially in the aerial parts of plants. Since Na+ interferes with K+ homeostasis, and especially given its involvement in numerous metabolic processes, maintaining a balanced cytosolic Na+/K+ ratio has become a key salinity tolerance mechanism. Achieving this homeostatic balance requires the activity of Na+ and K+ transporters and/or channels. The mechanism of Na+ and K+ uptake and translocation in glycophytes and halophytes is essentially the same, but glycophytes are more susceptible to ionic stress than halophytes. The transport mechanisms involve Na+ and/or K+ transporters and channels as well as non-selective cation channels. Thus, the question arises of whether the difference in salt tolerance between glycophytes and halophytes could be the result of differences in the proteins or in the expression of genes coding the transporters. The aim of this review is to seek answers to this question by examining the role of major Na+ and K+ transporters and channels in Na+ and K+ uptake, translocation and intracellular homeostasis in glycophytes. It turns out that these transporters and channels are equally important for the adaptation of glycophytes as they are for halophytes, but differential gene expression, structural differences in the proteins (single nucleotide substitutions, impacting affinity) and post-translational modifications (phosphorylation) account for the differences in their activity and hence the differences in tolerance between the two groups. Furthermore, lack of the ability to maintain stable plasma membrane (PM) potentials following Na+-induced depolarization is also crucial for salt stress tolerance. This stable membrane potential is sustained by the activity of Na+/H+ antiporters such as SOS1 at the PM. Moreover, novel regulators of Na+ and K+ transport pathways including the Nax1 and Nax2 loci regulation of SOS1 expression and activity in the stele, and haem oxygenase involvement in stabilizing membrane potential by activating H+-ATPase activity, favorable for K+ uptake through HAK/AKT1, have been shown and are discussed.

With the opportunistic pathogen Pseudomonas aeruginosa, quorum sensing based on homoserine lactones was found to influence biofilm formation. Here we discern a mechanism by which quorum sensing controls biofilm formation by screening 5850 transposon mutants of P. aeruginosa PA14 for altered biofilm formation. This screen identified the PA3885 mutant, which had 147-fold more biofilm than the wild-type strain. Loss of PA3885 decreased swimming, abolished swarming, and increased attachment, although this did not affect production of rhamnolipids. The PA3885 mutant also had a wrinkly colony phenotype, formed pronounced pellicles, had substantially more aggregation, and had 28-fold more exopolysaccharide production. Expression of PA3885 in trans reduced biofilm formation and abolished aggregation. Whole transcriptome analysis showed that loss of PA3885 activated expression of the pel locus, an operon that encodes for the synthesis of extracellular matrix polysaccharide. Genetic screening identified that loss of PelABDEG and the PA1120 protein (which contains a GGDEF-motif) suppressed the phenotypes of the PA3885 mutant, suggesting that the function of the PA3885 protein is to regulate 3,5-cyclic diguanylic acid (c-di-GMP) concentrations as a phosphatase since c-di-GMP enhances biofilm formation by activating PelD, and c-di-GMP inhibits swarming. Loss of PA3885 protein increased cellular c-di-GMP concentrations; hence, PA3885 protein is a negative regulator of c-di-GMP production. Purified PA3885 protein has phosphatase activity against phosphotyrosine peptides and is translocated to the periplasm. Las-mediated quorum sensing positively regulates expression of the PA3885 gene. These results show that the PA3885 protein responds to AHL signals and likely dephosphorylates PA1120, which leads to reduced c-di-GMP production. This inhibits matrix exopolysaccharide formation, which leads to reduced biofilm formation; hence, we provide a mechanism for quorum sensing control of biofilm formation through the pel locus and suggest PA3885 should be named TpbA for tyrosine phosphatase related to biofilm formation and PA1120 should be TpbB.

Protein N -glycosylation in the endoplasmic reticulum (ER) and in the Golgi apparatus is an essential process in eukaryotic cells. Although the N -glycosylation pathway in the ER has been shown to regulate protein quality control, salt tolerance, and cellulose biosynthesis in plants, no biological roles have been linked functionally to N -glycan modifications that occur in the Golgi apparatus. Herein, we provide evidence that mutants defective in N -glycan maturation, such as complex glycan 1 ( cgl1 ), are more salt-sensitive than wild type. Salt stress caused growth inhibition, aberrant root-tip morphology, and callose accumulation in cgl1 , which were also observed in an ER oligosaccharyltransferase mutant, staurosporin and temperature sensitive 3a ( stt3a ). Unlike stt3a , cgl1 did not cause constitutive activation of the unfolded protein response. Instead, aberrant modification of the plasma membrane glycoprotein KORRIGAN 1/RADIALLY SWOLLEN 2 (KOR1/RSW2) that is necessary for cellulose biosynthesis occurred in cgl1 and stt3a . Genetic analyses identified specific interactions among rsw2 , stt3a , and cgl1 mutations, indicating that the function of KOR1/RSW2 protein depends on complex N -glycans. Furthermore, cellulose deficient rsw1-1 and rsw2-1 plants were also salt-sensitive. These results establish that plant protein N -glycosylation functions beyond protein folding in the ER and is necessary for sufficient cell-wall formation under salt stress.

The oxidation of nitrite by dissolved oxygen to form nitrate is known to be accelerated ca. 105 times by the freezing of the aqueous solution. Here we report a detailed study on the acceleration mechanism of the above-mentioned oxidation. The reaction was studied at pH values between 3.0 and 5.6 at various freezing rates, by different freezing methods, and with and without additional salts. The effect of freezing which induced concentration (freeze concentration) of reactants into the unfrozen bulk solution was too small to explain the acceleration factor of ca. 105. Nitrate formations were completely prevented by addition of salts, such as NaCl and KCl, which make the freezing potential of ice negative, while the reaction was not affected by addition of salts, such as Na2SO4 and NH4Cl, which make the freezing potential of ice positive. When a sample solution was frozen in such a way as to form a single crystal of ice, most nitrite was exclusively liberated from the ice to the gas phase. This observation suggests the importance of ice in the polycrystalline form to retain nitrite during freezing. When freezing begins, grains of crystalline ice begin to grow. The solutes are rejected from the ice and concentrated in the interfacial water layer by assistance of the electrostatic force generated by the freezing potential. At a certain stage of freezing, the water layer is completely confined by the walls of some ice grains. Protons move from the ice phase to the unfrozen solution surrounded by the ice walls to neutralize the electric potential generated, and thus the pH of the unfrozen solution decreases. As a result, the reactant species, HNO2, increased more in the unfrozen solution. After this stage, the concentrations of the reactants in the unfrozen solution abruptly increase resulting in the acceleration of the rate of formation of nitrate. On the basis of the above mechanism, the concentration factor for nitrite was calculated as 2.4 × 103. The validity of this mechanism is further discussed.

Transcription and mRNA processing are regulated by phosphorylation and dephosphorylation of the C-terminal domain (CTD) of RNA polymerase II, which consists of tandem repeats of a Y 1 S 2 P 3 T 4 S 5 P 6 S 7 heptapeptide. Previous studies showed that members of the plant CTD phosphatase-like (CPL) protein family differentially regulate osmotic stress-responsive and abscisic acidresponsive transcription in Arabidopsis thaliana. Here we report that AtCPL1 and AtCPL2 specifically dephosphorylate Ser-5 of the CTD heptad in Arabidopsis RNA polymerase II, but not Ser-2. An N-terminal catalytic domain of CPL1, which suffices for CTD Ser-5 phosphatase activity in vitro, includes a signature DXDXT acylphosphatase motif, but lacks a breast cancer 1 CTD, which is an essential component of the fungal and metazoan Fcp1 CTD phosphatase enzymes. The CTD of CPL1, which contains two putative doublestranded RNA binding motifs, is essential for the in vivo function of CPL1 and includes a C-terminal 23-aa signal responsible for its nuclear targeting. CPL2 has a similar domain structure but contains only one double-stranded RNA binding motif. Combining mutant alleles of CPL1 and CPL2 causes synthetic lethality of the male but not the female gametes. These results indicate that CPL1 and CPL2 exemplify a unique family of CTD Ser-5-specific phosphatases with an essential role in plant growth and development.T ranscriptional induction of genes that encode stress tolerance determinants is an integral part of the survival strategy of plants in adverse environments. The Arabidopsis thaliana responsive to dehydration (RD) genes are prototypal outputs of stress signal integration activated by low temperature, hyperosmolarity, and the plant hormone abscisic acid (ABA). The stress-inducible promoter of the RD29a gene contains dehydration͞cold-responsive elements and ABA-responsive elements that are the targets of distinct families of DNA binding transcription factors (1, 2). The plant stress response is also regulated by proteins that impact the core RNA polymerase II (Pol II) transcriptional machinery, the mRNA maturation process, and chromatin structure (3-9). Analysis of Arabidopsis mutants that display hyperinduction of RD29a expression under stress conditions have identified a family of C-terminal domain (CTD) phosphatase-like (CPL) genes that negatively regulate stressresponsive transcription (5, 6). The CPL1 and CPL3 genes discovered in the screen for hyperinduction are so named because they encode large polypeptides (967 and 1,241 aa, respectively) with local primary structure similarity to the Fcp1 family of fungal and metazoan protein serine phosphatases, which regulate transcription by dephosphorylating the CTD of the largest subunit of RNA Pol II (10).The Pol II CTD is composed of a tandemly repeated heptapeptide of consensus sequence Y . The number of CTD heptad repeats varies widely among species and correlates roughly with evolutionary complexity; e.g., mammals have 52 repeats, Drosophila has 42 repeats, fission yeast Schizosacc...

SummaryPseudomonas aeruginosa is an ubiquitous, opportunistic pathogen whose biofilms are notoriously difficult to control. Here we discover uracil influences all three known quorum‐sensing (QS) pathways of P. aeruginosa. By screening 5850 transposon mutants for altered biofilm formation, we identified seven uracil‐related mutations that abolished biofilm formation. Whole‐transcriptome studies showed the uracil mutations (e.g. pyrF that catalyses the last step in uridine monophosphate synthesis) alter the regulation of all three QS pathways [LasR‐, RhlR‐ and 2‐heptyl‐3‐hydroxy‐4‐quinolone (PQS)‐related regulons]; addition of extracellular uracil restored global wild‐type regulation. Phenotypic studies confirmed uracil influences the LasR (elastase), RhlR (pyocyanin, rhamnolipids), PQS and swarming regulons. Our results also demonstrate uracil influences virulence (the pyrF mutant was less virulent to barley). Additionally, we found an anticancer uracil analogue, 5‐fluorouracil, that repressed biofilm formation, abolished QS phenotypes and reduced virulence. Hence, we have identified a central regulator of an important pathogen and a potential novel class of efficacious drugs for controlling cellular behaviour (e.g. biofilm formation and virulence).

Objective Coronavirus disease 2019 (COVID-19) is spreading around the world. The aim of this study was to assess the degree of anxiety, depression, resilience, and other psychiatric symptoms among healthcare workers in Japan during the COVID-19 pandemic. Methods This survey involved medical healthcare workers at the Japanese Red Cross Medical Center (Tokyo, Japan) between April 22 and May 15, 2020. The degree of symptoms of anxiety, depression, and resilience was assessed using the Japanese versions of the 7-item Generalized Anxiety Disorder Scale (GAD-7), Center for Epidemiologic Studies Depression Scale (CES-D), and 10-item Connor-Davidson Resilience Scale. Furthermore, we added original questionnaires comprising three factors: (i) anxiety and fear of infection and death; (ii) isolation and unreasonable treatment; and (iii) motivation and escape behavior at work. Results In total, 848 healthcare workers participated in this survey: 104 doctors, 461 nurses, 184 other co-medical staff, and 99 office workers. Among all participants, 85 (10.0%) developed moderate-to-severe anxiety disorder, and 237 (27.9%) developed depression. Problems with anxiety and fear of infection and death, isolation and unreasonable treatment, and motivation and escape from work were higher in the depression group than in the non-depression group (total CES-D score ≥ 16 points). Being a nurse and high total GAD-7 scores were risk factors of depression. Older workers and those with higher resilience were less likely to develop depression than others. Conclusion During the COVID-19 epidemic, many healthcare workers suffered from psychiatric symptoms. Psychological support and interventions for protecting the mental health of them are needed.

Anti-laminin c1 pemphigoid is an autoimmune subepidermal bullous disease first described in 1996, and has been distinct from previously known subepidermal blistering diseases, such as bullous pemphigoid and epidermolysis bullosa acquisita. Circulating autoantibodies of the patients do not react to any known autoantigen of the skin, but react to a 200-kDa molecule (p200) from dermal extracts. The identity of p200 was unmasked as laminin c1, an extracellular matrix glycoprotein composing several forms of laminin heterotrimers. We renamed this disease from the previously used anti-p200 pemphigoid to anti-laminin c1 pemphigoid, a new entity of an autoimmune bullous disease. In this decade, we have experienced over 70 cases of this disease. Although the number of the cases of anti-laminin c1 pemphigoid is half as many as the number of definitely diagnosed cases of epidermolysis bullosa acquisita in the same duration, a considerable number of the cases could be clinically misdiagnosed as epidermolysis bullosa acquisita. Unveiling the pathogenicity and development of a useful diagnostic method is necessary for appropriate management of this new disease.