The role of rock-phosphate-solubilizing fungi and vesicular–arbusular-mycorrhiza (VAM) in growth of wheat plants fertilized with rock phosphate

A total of 36 fungal species isolated from soil were tested for their ability to solubilize rock phosphate (RP) in agar plates. Most of these fungi were non-rock phosphate solubilizers, but two isolates, Aspergillus niger and Penicillium citrinum, had high activity. Liquid culture experiments revealed that both fungi caused a remarkable drop in pH of culture media and solubilized considerable amounts of phosphate. The effects on wheat of inoculation with vesicular–arbuscular mycorrhizal fungi and rock-phosphate-solubilizing fungi and fertilization with rock phosphate were studied in sterilized pot soils, nonsterilized pot trials and in field plot soils. Rock phosphate fertilization and inoculation with Glomus constrictum and rock-phosphate-solubilizing fungi (A. niger and P. citrinum) significantly increased dry matter yield of wheat plants under all experimental conditions. However, the effect was more evident in non- sterilized pot soils and in the field than in sterilized pots. Rock phosphate had no significant effect on the total phosphorus content of plants grown under pot conditions but it was significantly increased in field plots; the effect of inoculation with fungi (G. constrictum, A. niger and P. citrinum) on plant phosphorus was closely related to this in dry matter production. The greatest positive effect on growth and phosphorus contents of wheat plants was recorded in the treatments that received rock phosphate and were inoculated with a mixed inoculum of the three microorganisms used, followed by dual inoculation treatments of G. constrictum plus either A. niger or P. citrinum.     

The role of ACE2, angiotensin-(1–7) and Mas1 receptor axis in glucocorticoid-induced intrauterine growth restriction

Background

Plasma and urine levels of the potent vasodilator Ang-(1–7) are elevated in mid and late pregnancy and are correlated with elevated placental angiogenesis, fetal blood flow, and rapid fetal growth. We hypothesized that Ang-(1–7), its receptor (Mas1) and the enzymes involved in Ang-(1–7) production (ACE2 and Membrane metallo-endopeptidase; MME) are down regulated in response to glucocorticoid administration contributing to IUGR.

Methods

Pregnant female Sprague–Dawley rats were injected with dexamethasone (DEX; 0.4 mg/kg/day) starting from 14 day gestation (dg) till sacrifice at 19 or 21 dg while control groups were injected with saline (n?=?6/group). The gene and protein expression of ACE2, MME, Ang-(1–7) and Mas1 receptor in the placental labyrinth (LZ) and basal zones (BZ) were studied.

Results

DEX administration caused a reduction in LZ weight at 19 and 21 dg (p?<?0.001). IUGR, as shown by decreased fetal weights, was evident in DEX treated rats at 21 dg (p?<?0.01). ACE2 gene expression was elevated in the LZ of control placentas at 21 dg (p?<?0.01) compared to 19 dg and DEX prevented this rise at both gene (p?<?0.01) and protein levels (p?<?0.05). In addition, Ang-(1–7) protein expression in LZ was significantly reduced in DEX treated rats at 21 dg (p?<?0.05). On the other hand, Mas1 and MME were upregulated in LZ at 21 dg in both groups (p?<?0.05 and p?<?0.001, respectively).

Conclusion

The results of this study indicate that a reduced expression of ACE2 and Ang-(1–7) in the placenta by DEX treatment may be responsible for IUGR and consequent disease programming later in life.

     

Effect of manganese spatial distribution in the soil profile on wheat growth in rice–wheat rotation

Manganese (Mn) deficiency in wheat under rice (Oryza sativa L.) and wheat (Triticum aestivum L.) rotation is an important problem in most rice-growing areas in China. A field survey, field trials and a soil column experiment were conducted to determine the relationship between Mn leaching and distribution in soil profiles and paddy rice cultivation and the effects of Mn distribution in soil profiles on wheat growth and its response to Mn fertilization. At five field sites surveyed, total Mn and active Mn concentrations in the topsoil layers under rice–wheat rotations were only 42% and 11%, respectively, of those under systems without paddy rice. Both total and available Mn increased with soil depth in soils with rice–wheat rotations, showing significant spatial variability of Mn in the soil profile. Manganese leaching was the main pathway for Mn loss in coarse-textured soil with high pH, while excessive Mn uptake was the main pathway for Mn loss in clay-textured and acid soil. When Mn was deficient in the topsoil, sufficient Mn in the subsoil contributed to better growth and Mn nutrition of wheat but insufficient Mn in the subsoil resulted in Mn deficiency in wheat.     

The role of transforming growth factor (TGF)-β in modulating the immune response and fibrogenesis in the gut

Transforming growth factor (TGF)-β, a pleiotropic cytokine released by both immune and non-immune cells in the gut, exerts an important tolerogenic action by promoting regulatory T cell differentiation. TGF-β also enhances enterocyte migration and regulates extracellular matrix turnover, thereby playing a crucial role in tissue remodeling in the gut. In this review we describe the mechanisms by which abnormal TGF-β signaling impairs intestinal immune tolerance and tissue repair, thus predisposing to the onset of immune-mediated bowel disorders, such as inflammatory bowel disease and celiac disease. Additionally, we will discuss potential therapeutic strategies aiming at restoring physiologic TGF-β signaling in chronic intestinal diseases.     

Properties and regulation of leaf nicotinamide–adenine dinucleotide phosphate–malate dehydrogenase and `malic'' enzyme in plants with the C4-dicarboxylic acid pathway of photosynthesis

1. NADP-malate dehydrogenase and ;malic' enzyme in maize leaf extracts were separated from NAD-malate dehydrogenase and their properties were examined. 2. The NADP-malate dehydrogenase was nicotinamide nucleotide-specific but otherwise catalysed a reaction comparable with that with the NAD-specific enzyme. By contrast with the latter enzyme, a thiol was absolutely essential for maintaining the activity of the NADP-malate dehydrogenase, and the initial velocity in the direction of malate formation, relative to the reverse direction, was faster. 3. For the ;malic' enzyme reaction the K(m) for malate was dependent on pH and the pH optimum varied with the malate concentration. At their respective optimum concentrations the maximum velocity for this enzyme was higher with Mg(2+) than with Mn(2+). 4. The NADP-malate dehydrogenase in green leaves was rapidly inactivated in the dark and was reactivated when plants were illuminated. Reactivation of the enzyme extracted from darkened leaves was achieved simply by adding a thiol compound. 5. The activity of both enzymes was low in etiolated leaves of maize plants grown in the dark but increased 10-20-fold, together with chlorophyll, when leaves were illuminated. 6. The activity of these enzymes in different species with the C(4)-dicarboxylic acid pathway was compared and their possible role in photosynthesis was considered.     

The role of ‘Norin 10’ dwarfing genes in photosynthetic and respiratory activity of wheat leaves

Summary A comparative analysis of eight cultivars of spring wheat (Triticum aestivum) classified by height as tall (T), semi-dwarf (D₁), dwarf (D₂) and very dwarf (D₃) was conducted to study their efficiency of oxygen exchange during photosynthesis and dark respiration. Two cultivars were included in each height group.Cultivars carrying Norin 10 dwarfing genes (D₁, D₂ and D₃) were found to have a significantly higher photosynthetic rate per unit leaf area than talls (T) that lack these genes. Among the Norin gene carriers, dwarf group (D₂) was most efficient, followed by very dwarf (D₃) and semi-dwarf (D₁).Photosynthetic rate and respiratory rate were found to have a positive relationship.     

The role of soil-borne fungi in driving the coexistence of Pinus massoniana and Lithocarpus glaber in a subtropical forest via plant–soil feedback

亚热带森林土壤真菌类群对马尾松和石栎物种共存的驱动机制 植物-土壤反馈(plant–soil feedback, PSF)是促进森林生态系统物种共存和多样性维持的关键机制之一。大量证据表明大树周围具有物种特异性的土壤病原菌对其同种幼苗的存活和生长具有明显的抑制作用,而对于异种幼苗更新的影响则相对较弱。然而,时至今日我们仍然未能全面解读PSF这一影响 的内在生物学机制。本研究通过对我国亚热带常绿落叶阔叶林常见树种——马尾松(Pinus massoniana)和石栎(Lithocarpus glaber)开展交叉接种盆栽试验,探讨PSF过程对目标树种共存的作用机制。盆栽实验所用接种土壤取自天然林地两种目标树种林冠下的表层土壤,分别检测来源于同种大树和异种大树的接种土壤对马尾松和石栎幼苗存活和生长的影响。同时,通过杀菌处理评估不同土壤真菌功能类群,尤其是土壤病原真菌类群在PSF过程中的相对重要性。研究结果表明,石栎幼苗在接种异种大树土壤的情况下生长更好,而马尾松幼苗并未受到接种土壤来源的影响。然而,进行杀菌处理之后,在接种同种大树土壤的盆栽中石栎幼苗的长势更优于接种异种土壤的幼苗,说明土壤真菌类群是调控其PSF过程的关键环节。该研究验证了土壤病原真菌和菌根真菌类群是PSF过程重要的驱动因素,而PSF过程通过调控石栎幼苗的存活和生长,从而促进石栎树种与马尾松树种在群落中的共存。     

The expanding role of miR-302–367 in pluripotency and reprogramming

MicroRNA (miRNA) has been shown to be essential for regulating cell fate and pluripotency; however, our knowledge of miRNA function in stem cells is incomplete due to experimental limitations and difficulties in identifying their physiological targets. Recent studies implicated hESC-expressed miRNAs (miR?302–367 and miR?371–373 clusters) in regulating BMP signaling and promoting pluripotency, suggesting that low levels of BMP signaling may promote pluripotency by preventing neural induction. A comprehensive list of miR?302–367 targets recently identified by genome-wide approaches suggests a number of additional cellular processes and signaling pathways whose regulation by miR?302–367 may promote pluripotency and reprogramming, such as cell cycle, epigenetic changes, metabolism and vesicular transfer.     

The role of noise in a predator–prey model with Allee effect

The existence and implications of alternative stable states in ecological systems have been investigated extensively within deterministic models. However, it is known that natural systems are undeniably subject to random fluctuations, arising from either environmental variability or internal effects. Thus, in this paper, we study the role of noise on the pattern formation of a spatial predator–prey model with Allee effect. The obtained results show that the spatially extended system exhibits rich dynamic behavior. More specifically, the stationary pattern can be induced to be a stable target wave when the noise intensity is small. As the noise intensity is increased, patchy invasion emerges. These results indicate that the dynamic behavior of predator–prey models may be partly due to stochastic factors instead of deterministic factors, which may also help us to understand the effects arising from the undeniable susceptibility to random fluctuations of real ecosystems.     

The molecular composition of lignin in spruce decayed by white-rot fungi (Phanerochaete chrysosporium and Trametes versicolor) using pyrolysis-GC–MS and thermochemolysis with tetramethylammonium hydroxide

Pyrolysis-gas chromatography-mass spectrometry (Py-GC–MS) and off-line thermochemolysis with tetramethylammonium hydroxide followed by GC–MS were used in the molecular characterisation of lignin in spruce wood decayed by Phanerochaete chrysosporium and Trametes versicolor. Mono-methoxyphenols were the main pyrolysis products from the undegraded lignin. Py-GC–MS provided qualitative evidence that 2-methoxy-4-(prop-2-enal)phenol and trans-2-methoxy-4-(1-hydroxy-prop-2-enyl)phenol content decreased whereas 1,2-dihydroxybenzene increased in intensity relative to other products upon fungal decay. Comparison of methylated phenols from thermochemolysis revealed that ratio of methyl 3,4-dimethoxybenzoate to 3,4-dimethoxybenzaldehyde increased from 0.69 in control spruce to 2.3 after decay by P. chrysosporium and 3.7 following growth of T. versicolor. The results indicate that white-rot fungi cleave alkyl side chains of β-O-4 linked mono-methoxyphenylpropane structures between the α–β carbon atoms to give lignin residues enriched in carboxylic acids as well as demethylating methoxy groups attached to aromatic nuclei to give dihydroxybenzene products. Py-GC–MS and thermochemolysis are complementary methods for tracking demethylation of aromatic nuclei and oxidation of alkyl side chains caused by white-rot fungi.     

The proton-translocating nicotinamide–dinucleotide (phosphate) transhydrogenase of rat liver mitochondria

1. The NAD(P) transhydrogenase activity of the soluble fraction of sonicated rat liver mitochondrial preparations was greater than the NAD-linked isocitrate dehydrogenase activity, and the NAD-linked and NADP-linked isocitrate dehydrogenase activities were not additive. The NAD-linked isocitrate dehydrogenase activity was destroyed by an endogenous autolytic system or by added nucleotide pyrophosphatase, and was restored by a catalytic amount of NADP. 2. We concluded that the isocitrate dehydrogenase of rat liver mitochondria was exclusively NADP-specific, and that the oxoglutarate/isocitrate couple could therefore be used unequivocally as redox reactant for NADP in experiments designed to operate only the NAD(P) transhydrogenase (or loop 0) segment of the respiratory chain in intact mitochondria. 3. During oxidation of isocitrate by acetoacetate in intact, anaerobic, mitochondria via the rhein-sensitive, but rotenone- and arsenite-insensitive, NAD(P) transhydrogenase, measurements of the rates of carbonyl cyanide p-trifluoromethoxyphenylhydrazone-sensitive and carbonyl cyanide p-trifluoromethoxyphenylhydrazone-insensitive pH change in the presence of various oxoglutarate/isocitrate concentration ratios gave an -->H(+)/2e(-) quotient of 1.94+/-0.12 for outward proton translocation by the NAD(P) transhydrogenase. 4. Measurements with a K(+)-sensitive electrode confirmed that the electrogenicity of the NAD(P) transhydrogenase reaction corresponded to the translocation of one positive charge per acid equivalent. 5. Sluggish reversal of the NAD(P) transhydrogenase reaction resulted in a significant inward proton translocation. 6. The possibility that isocitrate might normally be oxidized via loop 0 at a redox potential of -450mV, or even more negative, is discussed, and implies that a P/O quotient of 4 for isocitrate oxidation might be expected.     

The role of stratifin in fibroblast–keratinocyte interaction

Stratifin is a member of 14-3-3 protein family, a highly conserved group of proteins constituted by seven isoforms. They are involved in numerous crucial intracellular functions such as cell cycle and apoptosis, regulation of signal transduction pathways, cellular trafficking, cell proliferation and differentiation, cell survival, and protein folding and processing, among others. At epidermal level, stratifin (also called 14-3-3 sigma) has been described as molecule with relevant functions. For instance, this isoform is a marker associated with keratinocyte differentiation. In this maturation process, the presence of dominant negative molecules of p53 induces a “stemness condition” of keratinocyte precursor cells and suppression of stratifin expression. In addition, the recently described keratinocyte-releasable form of stratifin is involved in dermal fibroblast MMP-1 over-expression through c-Fos and c-Jun activity. This effect is mediated, at least in part, by p38 mitogen-activated protein kinase (MAPK). Other MMP family members such as stromelysin-1 (MMP-3), stromelysin-2 (MMP-10), neutrophil collagenase (MMP-8), and membrane-type MMP-24 (MT5-MMP) are also up-regulated by stratifin. Within fibroproliferative disorder of skin, hypertrophic scar and keloids exhibit a high content of collagen, proteoglycans, and fibronectin. Thus, the MMP profile induced by stratifin is an interesting starting point to establish new therapeutic tools to control the process of wound healing. In this review, we will focus on site of synthesis and mode of action of stratifin in skin and wound healing.     

Azospirillum brasilense colonisation of wheat roots and the role of lectin–carbohydrate interactions in bacterial adsorption and root-hair deformation

The dynamics of adsorption of the nitrogen-fixing soil bacteria Azospirillum brasilense 75 and 80 (isolated from soil samples collected in Saratov Oblast, southern Russia) and A. brasilense Sp245 to the roots of seedlings of common spring wheat was studied in relation to inoculum size, period of incubation with the roots and bacterial-growth phase. The number of root-attached cells increased with increasing size of inoculum and time of contact. The saturation of root-surface adsorption was observed by 24 h of co-incubation for A. brasilense 75, by 6 h for A. brasilense 80, and by 3 h for A. brasilense Sp245. The firmness of bacterial–root attachment increased after extended co-incubation. Differences in the adsorption kinetics of the azospirilla were found that were associated with bacterial-growth phases. Azospirilla attached to the roots of their host cultivar more actively than they did to the roots of a non-host cultivar. Adsorption was partially inhibited when the roots were treated with N-acetyl-D-glucosamine. Maximal inhibition occurred after a 3-h exposure of the roots to the bacteria. Root-hair deformation induced with polysaccharide-containing complexes from the Azospirillum capsular material was inhibited by N-acetyl-D-glucosamine and chitotriose, specific haptens of wheat germ agglutinin. A possible mechanism of the mutual influence of bacteria and plants may involve key roles of wheat germ agglutinin, present on the roots, and the polysaccharide-containing components of the Azospirillum capsule.     

Selection of cold‐tolerant plants for growth in soils contaminated with organics

A mixture of organic chemicals (MOC) containing equal molar amounts of benzoic acid, hexadecane, 2,2‐dimethyl 4,n‐propyl‐benzene, phenanthrene, pyrene, and either cycloheptane or cis‐decahydronaphthalene (cis‐decalin) was applied to soil at rates of 0 to 8000 mg/kg. In a plant‐screening experiment, growth responses of four legume and five nonlegume species were determined at 10 and 25°C. The MOC applied at 2000 mg/kg reduced the growth of several species without resulting in significant seedling death. At 10°C, the growth of alpine bluegrass (Poa alpina L.) in the 1000 and 2000 mg/kg treatments of soil increased by more than 185%. In a plant growth response experiment, alpine bluegrass and alfalfa (Medicago sativa L.) were grown in soil that had been contaminated at rates of 0 and 2000 mg/kg. At 14 weeks, the shoot and root dry weights of alfalfa were 97% lower in the contaminated soil, while the shoot dry weight, root dry weight, and root length of alpine bluegrass were 135,235 and 268% higher, respectively. Except for pyrene, <23% of the compounds comprising the MOC remained in the soil after 4 weeks and <5% after 14 weeks. The disappearance of the MOC was not significantly influenced by the presence of alfalfa or alpine bluegrass.     

Ubiquitous presence of β-glucuronidase (GUS) in plants and its regulation in some model plants

The enzyme β-glucuronidase (GUS) is well characterized in animals and microbes. However, this enzyme is not well studied in plants and is widely assumed to be absent in them. In this study we document the ubiquitous presence of GUS in the model plants Arabidopsis thaliana, Oryza sativa, Nicotiana tabacum and Zea mays and record its expression pattern. The pH of the assay buffer was found to be critical with pH 4.0 being optimum for detection in all the species. GUS in plants appears to be associated with growth. In general, younger regions of the organs showed more GUS activity than the older and more mature tissues. In Brassica juncea roots stained for GUS, intense blue color could be seen in the trichoblast cells and the growing root hair cells as compared to the non-root hair forming epidermal cells or the fully elongated root hairs. Cotton fibers showed high GUS activity during the initial phase of elongation while the seed coat, from which the fibers formed, did not stain for GUS activity. The activity in the fibers disappeared after they were fully elongated. The level of GUS activity increased 2.58 folds in leaf tissues of N. tabacum when cultured in MS medium supplemented with 6-benzylaminopurine, while gibberellic acid enhanced GUS activity 2.9 folds in the inter-nodal regions of rice in 12-h treatment. In addition, elongation of stem, root and root hairs in tobacco seedlings was strongly inhibited by the specific inhibitor of GUS, saccharo-1-4-lactone in a reversible manner. Taken together, these evidences suggest a probable association of plant GUS in cell growth.Charu Sudan and Shiva Prakash, the first two authors, have contributed equally.     

The role of temperament in the relationship between morningness–eveningness and mood

Apart from differences in circadian phase position, individuals with different morningness–eveningness levels vary in many more characteristics. Particularly consistent relationships have been observed between morningness–eveningness and mood. Eveningness has been associated with disadvantageous mood, e.g. depressiveness in healthy individuals, and mood disorders. A concept of social jetlag suggests that evening subjects function in less advantageous environments due to discrepancies between internal and social time (societies promote morning-oriented functioning), which results in their lowered mood. Individual temperament, as defined by the Regulative Theory of Temperament (RTT), refers to the capacity of the human organism to meet environmental requirements – the greater the capacity, the less negative impact of external conditions. Thus, the aim of this study is to determine which RTT traits are linked to both morningness–eveningness and mood dimensions and to test whether they account for the relationship between morningness–eveningness and mood. A sample of 386 university students (267 female) aged between 19 and 47 (M?=?21.15, SD?=?4.23) years completed the University of Wales Institute of Science and Technology (UWIST) Mood Adjective Check List, Morningness–Eveningness Questionnaire and Formal Characteristics of Behaviour – Temperament Inventory. Analyses revealed lower endurance (EN) and higher emotional reactivity (ER) related to eveningness as well as to lower hedonic tone (HT), energetic arousal (EA) and to higher tense arousal (TA). Moreover, eveningness was associated with lower HT, EA and higher TA. Among RTT traits, EN was most strongly related to eveningness, and mediation analyses revealed that this temperamental trait fully mediated the relationship between eveningness and the three mood dimensions. The remaining RTT traits did not provide more explanation of the association between morningness–eveningness and mood than EN itself. If subjects did not differ in EN, the association between morningness–eveningness and mood was absent. EN is discussed as a protective factor against negative consequences of social jetlag and particularly lowered mood in evening individuals.     

Interactions of two species of the genusChenopodium with two production plants—Sugar beet and spring wheat

TwoChenopodium species (C. album L.,C. suecicum J. Murr) were grown under field conditions with sugar beet to assess the weed-caused crop loss, and with spring wheat in a replacement series experiment. The weeds strongly reduced the growth of sugar beet. Dew's competition indexes for the regressions of sugar beet yield on weed density were 6.81 and 3.78 forC. suecicum andC. album respectively. On the other hand, the yield of spring wheat was not affected by the twoChenopodium species owing to early shading of the weeds by the faster growing crop stand.