Structural basis for cytokinin receptor signaling: an evolutionary approach

Cytokinins are ubiquitous plant hormones; their signal is perceived by sensor histidine kinases—cytokinin receptors. This review focuses on recent advances on cytokinin receptor structure, in particular sensing module and adjacent domains which play an important role in hormone recognition, signal transduction and receptor subcellular localization. Principles of cytokinin binding site organization and point mutations affecting signaling are discussed. To date, more than 100 putative cytokinin receptor genes from different plant species were revealed due to the total genome sequencing. This allowed us to employ an evolutionary and bioinformatics approaches to clarify some new aspects of receptor structure and function. Non-transmembrane areas adjacent to the ligand-binding CHASE domain were characterized in detail and new conserved protein motifs were recovered. Putative mechanisms for cytokinin-triggered receptor activation were suggested.     

Lipid peroxidation depends on the clock 3111T/C gene polymorphism in menopausal women with Insomnia

ABSTRACT

A comparative analysis of lipid peroxidation processes and antioxidant defense system in Caucasian menopausal women with/without insomnia depending on the genotype of Clock 3111T/C gene polymorphism was performed. Two hundred and fourteen Caucasian menopausal women divided into control (without insomnia) and main group (with insomnia) were examined. Lipid peroxidation (conjugated dienes, thiobarbituric acid reactants) and antioxidant defense system parameters (?-tocopherol, retinol, reduced and oxidized glutathione, glutathione S-transferase, glutathione peroxidase, glutathione reductase, superoxide dismutase) were determined by spectrofluorophotometer and immunoenzymometric methods. Patients with insomnia carriers of the TT-genotype had a significantly higher thiobarbituric acid reactants level and glutathione peroxidase activity as compared to group with insomnia carriers of the minor 3111C-allele (p < .05). A comparative analysis of the parameters in the women of the main and control groups showed higher conjugated dienes, thiobarbituric acid reactants levels and lower retinol, reduced glutathione levels, glutathione reductase activity in women with insomnia carriers of the TT-genotype (p < .05). The carriers of the minor allele with insomnia had a higher conjugated dienes levels and lower glutathione peroxidase activity as compared to control (p < .05). Thus, lipid peroxidation and antioxidant system parameters in Caucasian menopausal women with insomnia depend on the Clock 3111T/C gene polymorphism.     

Elastic properties of the growth-controlling outer cell walls of maize coleoptile epidermis

The effects of tensile stress and temperature on cell wall elasticity have been investigated in the outer cell walls of coleoptile epidermis of 4- and 6-day-old Zea mays L. seedlings. The change in tensile stress from 6 to 40 MPa caused the increase in cell wall elastic modulus from 0.4 to 3 GPa. Lowering the temperature from 30 to 4 °C resulted in instantaneous and reversible cell wall elongation of 0.3–0.5 ‰. At a given temperature and stress level, the wall elastic modulus of 6-day-old seedlings tended to be 30 % higher than that of 4-day-old plants. The relationship between cell wall elasticity and mechanical stress indicated that the stress distribution within the cell wall is highly uneven. The analysis of the effect of temperature on cell wall elastic strain showed that structural differences between crystalline and amorphous load-bearing polymers were not the only cause of the uneven stress distribution. Based on the results obtained by Hejnowicz and Borowska-Wykr?t (Planta 220:465–473, 2005), we suggested that the uneven stress distribution is partially related to the stress gradient between inner and outer layers of the cell wall.     

Prejudice in the former Soviet Union

Research in the United States and Europe has focused on the prejudice of majority groups towards minority groups, the implication somehow being that majority groups were more prejudiced than minority groups. In the former Soviet Union, ethnic environments were more complex; the same ethnic group could be a majority in one region but a minority in others. Using a sample of 1,459 first‐ and fourth‐year university students from eight regions of the former USSR, this study focuses on Russian, Tatar and Ukrainian respondents (n = 821) to test the hypothesis that the status of an ethnic group (majority/minority) or in‐group bias explains members’ prejudice. According to in‐group bias, all ethnic groups are equally prejudiced, minority and majority alike, whereas group status posits that groups in a majority position are more prejudiced. Findings show that group status has greater impact on prejudice than does in‐group bias. This applies, however, only to Russians. Interpretations of the findings rest on Soviet history and the rise of nationalism during the breakup of the Soviet Union.     

AMP-activated protein kinase and ATP-citrate lyase are two distinct molecular targets for ETC-1002, a novel small molecule regulator of lipid and carbohydrate metabolism

ETC-1002 (8-hydroxy-2,2,14,14-tetramethylpentadecanedioic acid) is a novel investigational drug being developed for the treatment of dyslipidemia and other cardio-metabolic risk factors. The hypolipidemic, anti-atherosclerotic, anti-obesity, and glucose-lowering properties of ETC-1002, characterized in preclinical disease models, are believed to be due to dual inhibition of sterol and fatty acid synthesis and enhanced mitochondrial long-chain fatty acid β-oxidation. However, the molecular mechanism(s) mediating these activities remained undefined. Studies described here show that ETC-1002 free acid activates AMP-activated protein kinase in a Ca²⁺/calmodulin-dependent kinase β-independent and liver kinase β 1-dependent manner, without detectable changes in adenylate energy charge. Furthermore, ETC-1002 is shown to rapidly form a CoA thioester in liver, which directly inhibits ATP-citrate lyase. These distinct molecular mechanisms are complementary in their beneficial effects on lipid and carbohydrate metabolism in vitro and in vivo. Consistent with these mechanisms, ETC-1002 treatment reduced circulating proatherogenic lipoproteins, hepatic lipids, and body weight in a hamster model of hyperlipidemia, and it reduced body weight and improved glycemic control in a mouse model of diet-induced obesity. ETC-1002 offers promise as a novel therapeutic approach to improve multiple risk factors associated with metabolic syndrome and benefit patients with cardiovascular disease.     

Fused in Sarcoma (FUS) Protein Lacking Nuclear Localization Signal (NLS) and Major RNA Binding Motifs Triggers Proteinopathy and Severe Motor Phenotype in Transgenic Mice

Dysfunction of two structurally and functionally related proteins, FUS and TAR DNA-binding protein of 43 kDa (TDP-43), implicated in crucial steps of cellular RNA metabolism can cause amyotrophic lateral sclerosis (ALS) and certain other neurodegenerative diseases. The proteins are intrinsically aggregate-prone and form non-amyloid inclusions in the affected nervous tissues, but the role of these proteinaceous aggregates in disease onset and progression is still uncertain. To address this question, we designed a variant of FUS, FUS 1–359, which is predominantly cytoplasmic, highly aggregate-prone, and lacks a region responsible for RNA recognition and binding. Expression of FUS 1–359 in neurons of transgenic mice, at a level lower than that of endogenous FUS, triggers FUSopathy associated with severe damage of motor neurons and their axons, neuroinflammatory reaction, and eventual loss of selective motor neuron populations. These pathological changes cause abrupt development of a severe motor phenotype at the age of 2.5–4.5 months and death of affected animals within several days of onset. The pattern of pathology in transgenic FUS 1–359 mice recapitulates several key features of human ALS with the dynamics of the disease progression compressed in line with shorter mouse lifespan. Our data indicate that neuronal FUS aggregation is sufficient to cause ALS-like phenotype in transgenic mice.     

Kauriphanes n. gen., a new genus of braconid parasitoid wasp (Hymenoptera: Braconidae: Doryctinae) from New Zealand

A new genus belonging to the braconid wasp subfamily Doryctinae, Kauriphanes n. gen. (type species K. khalaimi n. sp.), is described from New Zealand. This genus is placed within the doryctine subtribe Caenophanina. The extent of this subtribe is discussed and the phylogenetic relationships of three of its genera were investigated using one mitochondrial and one nuclear DNA sequence markers. Similar to previous studies, the Bayesian analyses performed significantly support a clade with the included members of Caenophanina as a sister group of a clade with the examined species of Spathiini sensu stricto. The placement of the Caenophanini within Doryctini, however, is left pendant to further exhaustive phylogenetic studies. A key to genera and subgenera belonging to Caenophanina is given.     

l-Leucine 5-hydroxylase of Nostoc punctiforme is a novel type of Fe(II)/α-ketoglutarate-dependent dioxygenase that is useful as a biocatalyst

l-Leucine 5-hydroxylase (LdoA) previously found in Nostoc punctiforme PCC 73102 is a novel type of Fe(II)/α-ketoglutarate-dependent dioxygenase. LdoA catalyzed regio- and stereoselective hydroxylation of l-leucine and l-norleucine into (2S,4S)-5-hydroxyleucine and (2S)-5-hydroxynorleucine, respectively. Moreover, LdoA catalyzed sulfoxidation of l-methionine and l-ethionine in the same manner as previously described l-isoleucine 4-hydroxylase. Therefore LdoA should be a promising biocatalyst for effective production of industrially useful amino acids.     

Genotypic difference in salinity tolerance in quinoa is determined by differential control of xylem Na loading and stomatal density

Quinoa is regarded as a highly salt tolerant halophyte crop, of great potential for cultivation on saline areas around the world. Fourteen quinoa genotypes of different geographical origin, differing in salinity tolerance, were grown under greenhouse conditions. Salinity treatment started on 10 day old seedlings. Six weeks after the treatment commenced, leaf sap Na and K content and osmolality, stomatal density, chlorophyll fluorescence characteristics, and xylem sap Na and K composition were measured. Responses to salinity differed greatly among the varieties. All cultivars had substantially increased K⁺ concentrations in the leaf sap, but the most tolerant cultivars had lower xylem Na⁺ content at the time of sampling. Most tolerant cultivars had lowest leaf sap osmolality. All varieties reduced stomata density when grown under saline conditions. All varieties clustered into two groups (includers and excluders) depending on their strategy of handling Na⁺ under saline conditions. Under control (non-saline) conditions, a strong positive correlation was observed between salinity tolerance and plants ability to accumulate Na⁺ in the shoot. Increased leaf sap K⁺, controlled Na⁺ loading to the xylem, and reduced stomata density are important physiological traits contributing to genotypic differences in salinity tolerance in quinoa, a halophyte species from Chenopodium family.