Mapping of QTLs Controlling Na+, K+ and CI− Ion Concentrations in Salt Tolerant Indica Rice Variety CSR27

Soil salinity and sodicity are major constraints to rice production in about twenty per cent of the irrigated crop land. Inbuilt genetic tolerance to salinity is the most economical and environmentally sustainable way to solve this problem. A mapping population of 200 F₂ plants and their corresponding F₃ families, derived from a cross between a salt tolerant indica rice variety CSR27 and a salt sensitive variety MI48 were used to map OTLs for salt tolerance. Seventeen different parameters, including seedling salt injury score, Na⁺, K⁺, CI^? concentrations and Na⁺/K⁺ ratio in leaf and stem tissues at vegetative and reproductive stages were mapped. A framework linkage map was constructed using 79 SSR and EST markers distributed over the twelve rice chromosomes at an average interval of 20.7cM and total map distance of 1634.5 cM. Twenty five major OTLs, each explaining more than ten per cent of the trait phenotypic variance, were mapped on chromosomes 1, 2, 3 and 8. These included one OTL for seedling salt injury score, nine for Na⁺ concentration, three for K⁺ concentration and four for Cl^? concentration in leaf and stem tissues at vegetative and reproductive stages. The Na⁺/K⁺ ratio, an important ion balancing parameter for the salt tolerance, was controlled by eight OTLs explaining phenotypic variance in the range of 42.88–52.63%. Four OTL intervals were robust with major effect and having OTLs for multiple salt tolerance parameters that might be governed by common or tightly linked genes. One major OTL for multiple salt tolerance parameters on chromosome 8 and three major OTLs for CI^? ion concentration are novel for this study. The OTLs identified here will serve as a base for fine mapping, gene tagging and marker assisted selection for salt tolerance in rice.     

Investigation of the synthetic route to pepstatin analogues by SPPS using O‐protected and O‐unprotected statine as building blocks

The synthetic route to pepstatin derivatives by a solid phase peptide synthesis using either O‐protected or O‐unprotected statine as a building block has been investigated. Statine was prepared according to a modified literature procedure, whereas protection of its 3‐hydroxyl moiety using tert‐butyldimethylsilylchloride (TBSCl) provided the novel O‐TBS‐protected statine building block. The O‐tert‐butyldimethylsilyl (TBS)‐protected statine approach provides an improved synthetic strategy for the preparation of statine‐containing peptides as demonstrated by the synthesis of the pepstatin analogue iva‐Val‐Leu‐Sta‐Ala‐Sta. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.     

Inula viscosa (L.) Aiton Ethanolic Extract Inhibits the Growth of Human AGS and A549 Cancer Cell Lines

The present study shows the chemical profile and cytotoxic properties of the ethanolic extracts of Inula viscosa from Northeast Algeria. The extract was obtained by maceration using ethanol. Its phenolic profile was determined using ultra-high-performance liquid chromatography coupled with a diode array detector and an electrospray mass spectrometer (UHPLC-DAD-ESI/MS), which allowed the identification and quantification of 17 compounds, 1,5-O-caffeoylquinic acid being the most abundant. The cytotoxic activity was assessed against human gastric cancer (AGS) and human non-small-cell lung cancer (A549) cell lines, whereas ethanolic extract elicited nearly 60 % and 40 % viability loss toward AGS and A549 cancer cells, respectively. Results also showed that cell death is caspase-independent and confirmed the involvement of RIPK1 and the necroptosis pathway in the toxicity induced by the I. viscosa extract. In addition, the ethanolic extract would not provoke morphological traits in the cancer cells. These findings suggest that I. viscosa can be a source of new antiproliferative drugs or used in preparation plant-derived pharmaceuticals.     

Transcriptome profile reveals AMPA receptor dysfunction in the hippocampus of the <Emphasis Type="Italic">Rsk2</Emphasis>-knockout mice,an animal model of Coffin–Lowry syndrome

Coffin–Lowry syndrome (CLS) is a syndromic form of mental retardation caused by loss of function mutations in the X-linked RPS6KA3 gene, which encodes RSK2, a serine/threonine kinase acting in the MAPK/ERK pathway. The mouse invalidated for the Rps6ka3 (Rsk2-KO) gene displays learning and long-term spatial memory deficits. In the current study, we compared hippocampal gene expression profiles from Rsk2-KO and normal littermate mice to identify changes in molecular pathways. Differential expression was observed for 100 genes encoding proteins acting in various biological pathways, including cell growth and proliferation, cell death and higher brain function. The twofold up-regulated gene (Gria2) was of particular interest because it encodes the subunit GLUR2 of the AMPA glutamate receptor. AMPA receptors mediate most fast excitatory synaptic transmission in the central nervous system. We provide evidence that in the hippocampus of Rsk2-KO mice, expression of GLUR2 at the mRNA and at the protein levels is significantly increased, whereas basal AMPA receptor-mediated transmission in the hippocampus of Rsk2-KO mice is significantly decreased. This is the first time that such deregulations have been demonstrated in the mouse model of the Coffin–Lowry syndrome. Our findings suggest that a defect in AMPA neurotransmission and plasticity contribute to mental retardation in CLS patients.     

Spiroplasma-like organisms closely associated with the gut in five leafhopper species (Hemiptera: Cicadellidae)

Spiroplasmas are bacteria in the Class Mollicutes that are frequently associated with insects and/or plants. Here, we describe the ultrastructure, localization, and occurrence of apparent commensal/symbiotic spiroplasma-like organisms (SLOs) in the midgut and hindgut of five leafhopper species from laboratory-reared colonies. Those found in Dalbulus elimatus, Endria inimica, and Macrosteles quadrilineatus were long and tubular shaped, whereas those in Dalbulus maidis and Graminella nigrifrons were shorter and mostly rod-shaped in their host organisms. These SLOs were found in great numbers in the gut lumen frequently associated with the gut microvilli, but unlike the plant-pathogenic mollicutes, they did not seem to invade the gut epithelium or other tissues in any of these five leafhopper species. Large accumulations of these gut-associated organisms were more commonly found by confocal laser scanning microscopy in males than in females and in crowded than in singly reared leafhoppers. Ultrastructural evidence suggests that these SLOs may be horizontally transmitted between leafhoppers by contamination of the mouth parts with leafhopper excretions.     

Salinity tolerance of hydroponically grown <Emphasis Type="Italic">Pinus pinea</Emphasis> L. seedlings

The salinity tolerance and ion transport of 2-month-old seedlings of stone pine (Pinus pinea L.) grown in hydroponic solution containing various concentrations of NaCl (0–100 mM) were studied. The presence of salt of up to 100 mM did not significantly reduce growth. Seedling hydration was insensitive to salinity. High salt concentrations reduced K⁺ and Ca²⁺ uptake, root accumulation, and export to shoots. Na⁺ and Cl⁻ ions, representing the major part of the ionic uptake, were effectively compartmentalized in vacuoles. We concluded that seedlings of stone pine cultivated hydroponically were highly tolerant to salt concentrations of up to 100 mM for a culture period of 38 days. This tolerance was associated with the accumulation of Na⁺ and Cl⁻ ions in the shoots.     

Cadmium stress induces changes in the lipid composition and biosynthesis in tomato (<Emphasis Type="Italic">Lycopersicon esculentum</Emphasis> Mill.) leaves

The effects of cadmium (Cd) stress on lipid composition and biosynthesis were investigated in young leaves of ten-day-old tomato seedlings (Lycopersicon esculentum Mill. cv. Ibiza F1). Cd was found to be mainly accumulated in roots, but a severe inhibition of biomass production occurred in leaves, even at its low concentration (1.0 μM). Seven days after Cd treatment, the membrane lipids were extracted and separated on silica-gel thin layer chromatography (TLC). Fatty acid methyl esters were analyzed by FID-GC on a capillary column. Our results showed that Cd stress decreased the quantities of all lipids classes (phospholipids, galactolipids and neutral lipids). Likewise, there was also a decline in the levels of tri-unsaturated fatty acids, such as linolenic (C18:3) and hexadecatrienoic (C16:3) acids. The linolenic acid (C18:3) decreased in monogalactosyldiacylglycerol (MGDG) and all phospholipids, while hexadecatrienoinic acid (C16:3) declined mainly in MGDG. Moreover, Cd at high concentrations (25.0 and 50.0 μM) significantly enhanced the levels of lipid peroxides. Radiolabelling experiments were carried out by laying down microdroplets of [1-¹⁴C]acetate–a major precursor of lipid biosynthesis–on attached leaves of the control and Cd-treated plants. After incubation for 1, 2, 12 and 24 h, the leaves were harvested and lipids extracted and analysed. Cd stress was found to decrease the incorporation of [1-¹⁴C]acetate in total lipids. The biosynthesis of total lipids was altered with 25.0 and 50.0 μM Cd. The decline in the incorporation of [1-¹⁴C]acetate due to Cd stress was observed in all lipid classes. There was also a substantial decline in the incorporation of [1-¹⁴C]acetate in tri-unsaturated fatty acids. The results indicate that Cd treatment induces an oxidative stress by inhibiting the chloroplastic and extrachloroplastic lipid-biosynthesis pathways as well as lipid peroxidation.