OsSQD1 at the crossroads of phosphate and sulfur metabolism affects plant morphology and lipid composition in response to phosphate deprivation

In phosphate (Pi)-deprived Arabidopsis (Arabidopsis thaliana), phosphatidylglycerol (PG) is substituted by sulfolipid for maintaining Pi homeostasis. Sulfoquinovosyl diacylglycerol1 (AtSQD1) encodes a protein, which catalyzes uridine diphosphate glucose (UDPG) and sulfite (SO₃²⁻) to UDP-sulfoquinovose, which is a key component in the sulfolipid biosynthetic pathway. In this study, a reverse genetics approach was employed to decipher the function of the AtSQD1 homolog OsSQD1 in rice. Differential expressions of OsSQD1 in different tissue and response to −P and −S also detected, respectively. The in vitro protein assay and analysis suggests that OsSQD1 is a UDP-sulfoquinovose synthase. Transient expression analysis showed that OsSQD1 is located in the chloroplast. The analyses of the knockout (ossqd1) and knockdown (Ri1 and Ri2) mutants demonstrated reductions in Pi and total P concentrations, ³²Pi uptake rate, expression levels of Pi transporters and altered developmental responses of root traits, which were accentuated during Pi deficiency. The inhibitory effects of the OsSQD1 mutation were also evident in the development of reproductive tissue. Furthermore, OsSQD1 differently affects lipid composition under different Pi regime affects sulfur (S) homeostasis. Together, the study revealed that OsSQD1 affects Pi and S homeostasis, and lipid composition in response to Pi deprivation.     

Variability of light-induced circular dichroism spectra of photosystem I complexes of cyanobacteria

Circular dichroism (CD) spectra of photosystem I (PSI) complexes of the cyanobacteria Thermosynechococcus elongatus, Arthrospira platensis and Synechocystis sp. PCC 6803 were studied. CD spectra of dark-adapted PSI trimers and monomers, measured at 77 K, show common bands at 669–670(+), 673(+), 680(−), 683–685(−), 696–697(−), 702(−) and 711(−) nm. The intensities of these bands are species specific. In addition, bands at 683–685(−) and 673(+) nm differ in intensity for trimeric and monomeric PSI complexes. CD difference spectra (P700⁺–P700) of PSI complexes at 283 K exhibit conservative bands at 701(−) and 691(+) nm due to changes in resonance interaction of chlorophylls in the reaction center upon oxidation of P700. Additional bands are observed at 671(−), 678(+), 685(−), 693(−) nm and in the region 720–725 nm those intensities correlate with intensities of analogous bands of antenna chlorophylls in dark-adapted CD spectra. It is suggested that the variability of CD difference spectra of PSI complexes is determined by changes in resonance interaction of reaction center chlorophylls with closely located antenna chlorophylls.     

Genetic diversity of NBS–LRR class disease-resistance gene analogs in cultivated and wild eggplants

The genes encoding the nucleotide-binding site (NBS) and leucine-rich repeat (LRR) motifs constitute a large gene family in plants and have attracted much interest, because most of the plant disease-resistance genes that have been cloned are from this gene family. In this study, degenerate oligonucleotide primers, designed on the basis of conserved regions of the NBS domains from known plant resistance genes, were used to isolate resistance gene analogs (RGAs) from cultivated and wild eggplants, i.e., S. melongena, S. aethiopicum gr. Gilo, S. linnaeanum, S. integrifolium, S. sisymbriifolium, and S. khasianum. Sequence analysis indicated that the cloned eggplant RGAs belong to the non-TIR–NBS–LRR type, which are very similar to the R genes or the RGAs identified in other plant species, especially Solanaceae plants, suggesting the existence of common ancestors. Wide genetic diversity of eggplant RGAs was observed both in interspecific and intraspecific sequences, and eight distinct families of eggplant RGAs were identified. Further studies revealed a high average ratio of synonymous to non-synonymous substitution and a low level of recombination. These results suggest that NBS-encoding sequences of RGAs in cultivated and wild eggplants are subject to gradual accumulation of mutations leading to purifying selection. This is the first report of NBS–LRR class RGAs in eggplants.     

An active factor from tomato root exudates plays an important role in efficient establishment of mycorrhizal symbiosis

Root exudates play an important role in the early signal exchange between host plants and arbuscular mycorrhizal fungi. M161, a pre-mycorrhizal infection (pmi) mutant of the tomoto (Solanum lycopersicum) cultivar Micro-Tom, fails to establish normal arbuscular mycorrhizal symbioses, and produces exudates that are unable to stimulate hyphal growth and branching of Glomus intraradices. Here, we report the identification of a purified active factor (AF) that is present in the root exudates of wild-type tomato, but absent in those of M161. A complementation assay using the dual root organ culture system showed that the AF could induce fungal growth and branching at the pre-infection stage and, subsequently, the formation of viable new spores in the M161 background. Since the AF-mediated stimulation of hyphal growth and branching requires the presence of the M161 root, our data suggest that the AF is essential but not sufficient for hyphal growth and branching. We propose that the AF, which remains to be chemically determined, represents a plant signal molecule that plays an important role in the efficient establishment of mycorrhizal symbioses.     

IL22 Regulates Human Urothelial Cell Sensory and Innate Functions through Modulation of the Acetylcholine Response,Immunoregulatory Cytokines and Antimicrobial Peptides: Assessment of an In Vitro Model

Human urinary disorders are generally studied in rodent models due to limitations of functional in vitro culture models of primary human urothelial cells (HUCs). Current HUC culture models are often derived from immortalized cancer cell lines, which likely have functional characteristics differ from healthy human urothelium. Here, we described a simple explant culture technique to generate HUCs and assessed their in vitro functions. Using transmission electron microscopy, we assessed morphology and heterogeneity of the generated HUCs and characterized their intercellular membrane structural proteins relative to ex vivo urothelium tissue. We demonstrated that our cultured HUCs are free of fibroblasts. They are also heterogeneous, containing cells characteristic of both immature basal cells and mature superficial urothelial cells. The cultured HUCs expressed muscarinic receptors (MR1 and MR2), carnitine acetyltransferase (CarAT), immunoregulatory cytokines IL7, IL15, and IL23, as well as the chemokine CCL20. HUCs also expressed epithelial cell-specific molecules essential for forming intercellular structures that maintain the functional capacity to form the physiological barrier of the human bladder urothelium. A subset of HUCs, identified by the high expression of CD44, expressed the Toll-like receptor 4 (TLR4) along with its co-receptor CD14. We demonstrated that HUCs express, at the mRNA level, both forms of the IL22 receptor, the membrane-associated (IL22RA1) and the secreted soluble (IL22RA2) forms; in turn, IL22 inhibited expression of MR1 and induced expression of CarAT and two antimicrobial peptides (S100A9 and lipocalin-2). While the cellular sources of IL22 have yet to be identified, the HUC cytokine and chemokine profiles support the concept that IL22-producing cells are present in the human bladder mucosa tissue and that IL22 plays a regulatory role in HUC functions. Thus, the described explant technique is clearly capable of generating functional HUCs suitable for the study of human urinary tract disorders, including interactions between urothelium and IL22-producing cells.     

Origin of juvenile chum salmon <Emphasis Type="Italic">Oncorhynchus keta</Emphasis> (Salmonidae) in the Sea of Okhotsk coastal waters off South Sakhalin

Based on the data of the analysis of distribution of juvenile chum salmon Oncorhynchus keta that were marked at salmon hatcheries in the southern part of the Sakhalin Island and Japan it has been established that their stocks in the Sea of Okhotsk coastal waters off South Sakhalin and Japan are of mixed origin. One part of the stock is composed of juveniles from hatcheries located in the southern part of Sakhalin, and the other part is composed of migrants from the waters adjacent to Japan. The first part is formed by juveniles both from hatcheries on the Sea of Okhotsk and Sea of Japan coasts of South Sakhalin. The second part is formed by juveniles reared at hatcheries in all regions of Japan: the Pacific and Sea of Okhotsk coasts of Honshu and Hokkaido, and from the Sea of Okhotsk coast of Hokkaido and Izmena (Nemuro) Strait. In July, in the Sea of Okhotsk coastal waters off South Sakhalin, the length and weight of most juvenile chum salmon of Japanese origin exceed 10 cm and 10 g, and juveniles of Sakhalin origin are always smaller than 10 cm and 10 g, which makes it possible to differentiate juveniles in trawl catches.     

Precursors and propeptides of neurotrophic factors as modulators of the biological activity of mature forms

Problems of the maturation of neurotrophic factors, the role of their precursors (proneurotrophins), and the contribution of elements that are removed in the course of maturation (propeptides) to the biological functions of these growth factors, are reviewed.