Mapping quantitative trait loci for root development under hypoxia conditions in soybean (<Emphasis Type="Italic">Glycine max</Emphasis> L. Merr.)

Key message

Greatest potential, QTLs for hypoxia and waterlogging tolerance in soybean roots were detected using a new phenotypic evaluation method.

Abstract

Waterlogging is a major environmental stress limiting soybean yield in wet parts of the world. Root development is an important indicator of hypoxia tolerance in soybean. However, little is known about the genetic control of root development under hypoxia. This study was conducted to identify quantitative trait loci (QTLs) responsible for root development under hypoxia. Recombinant inbred lines (RILs) developed from a cross between a hypoxia-sensitive cultivar, Tachinagaha, and a tolerant landrace, Iyodaizu, were used. Seedlings were subjected to hypoxia, and root development was evaluated with the value change in root traits between after and before treatments. We found 230 polymorphic markers spanning 2519.2 cM distributed on all 20 chromosomes (Chrs.). Using these, we found 11 QTLs for root length (RL), root length development (RLD), root surface area (RSA), root surface area development (RSAD), root diameter (RD), and change in average root diameter (CARD) on Chrs. 11, 12, 13 and 14, and 7 QTLs for hypoxia tolerance of these root traits. These included QTLs for RLD and RSAD between markers Satt052 and Satt302 on Chr. 12, which are important markers of hypoxia tolerance in soybean; those QTLs were stable between 2 years. To validate the QTLs, we developed a near-isogenic line with the QTL region derived from Iyodaizu. The line performed well under both hypoxia and waterlogging, suggesting that the region contains one or more genes with large effects on root development. These findings may be useful for fine mapping and positional cloning of gene responsible for root development under hypoxia.

     

Radiological workers sensitivity to 50 Hz pulsed magnetic fields: preliminary results

In the present study the effect of extremely low frequency pulsed magnetic fields (PMF) was evaluated in lymphocyte cultures from 12 subjects occupationally exposed to low doses of ionising radiations. The PMF signal characteristics were repetition frequency 50 Hz, triangular shape, rise time about 1.2 ms and peak intensity 2.5 mT. The cytokinesis-block technique was employed to evaluate genotoxicity and cytotoxicity in terms of micronucleus frequency and cell proliferation, respectively. When PMF-exposed cultures were compared with their respective controls, a slight but statistically significant increase was detected in both the biological parameters investigated ( p<0.05). The results obtained suggest a possible role of specific employments involving exposure to ionising radiation, in the risk associated with electromagnetic field exposure.     

Cell fusions in mammals

Cell fusions are important to fertilization, placentation, development of skeletal muscle and bone, calcium homeostasis and the immune defense system. Additionally, cell fusions participate in tissue repair and may be important to cancer development and progression. A large number of factors appear to regulate cell fusions, including receptors and ligands, membrane domain organizing proteins, proteases, signaling molecules and fusogenic proteins forming alpha-helical bundles that bring membranes close together. The syncytin family of proteins represent true fusogens and the founding member, syncytin-1, has been documented to be involved in fusions between placental trophoblasts, between cancer cells and between cancer cells and host cells. We review the literature with emphasis on the syncytin family and propose that syncytins may represent universal fusogens in primates and rodents, which work together with a number of other proteins to regulate the cell fusion machinery.     

Biological role of MicroRNA-103 based on expression profile and target genes analysis in pigs

MicroRNAs (miRNAs) are endogenously expressed RNAs consisting of 20–24 nucleotides. These molecules are thought to repress protein translation by binding to target mRNAs. However, biological functions have not been assigned to most of the 175 porcine miRNAs registered in miRBase (release 15.0). In an effort to uncover miR-103 important in pigs, we examined the integrative tissue expression profile and gene ontology (GO) term enrichment of predicted target genes to determine the global biological functions of miR-103. Our results demonstrated that miR-103 is involved in various biological processes including brain development, lipid metabolism, adipocyte differentiation, hematopoiesis, and immunity. Moreover, we also experimentally verified effects of miR-103 in porcine preadipocytes. miR-103 levels increased in differentiating adipocytes, and inhibition of miR-103 effectively inhibited preadipocyte differentiation. In addition, mRNA levels of the putative miR-103 target RAI14 were higher in miR-103 inhibitor-treated adipocytes. These results demonstrate that miR-103 is involved in porcine preadipocyte differentiation and may act through the putative target gene RAI14. In a word, our data provide new insights into the global biological role of miR-103.     

Multiple strategies to improve sensitivity,speed and robustness of isothermal nucleic acid amplification for rapid pathogen detection

Background  

In the past decades the rapid growth of molecular diagnostics (based on either traditional PCR or isothermal amplification technologies) meet the demand for fast and accurate testing. Although isothermal amplification technologies have the advantages of low cost requirements for instruments, the further improvement on sensitivity, speed and robustness is a prerequisite for the applications in rapid pathogen detection, especially at point-of-care diagnostics. Here, we describe and explore several strategies to improve one of the isothermal technologies, helicase-dependent amplification (HDA).     

Possible role of ionic gradients in the apical growth of <Emphasis Type="Italic">Neurospora crassa</Emphasis>

The effects of the Ca²⁺/H⁺ exchanger A23187 and the K⁺/H⁺ exchanger nigericin on the growth of Neurospora crassa were analyzed. Both ionophores had the same effects on the fungus. They both inhibited growth in liquid media, apical extension being more affected than protein synthesis. A sudden challenge to either ionophore on solid media rapidly stopped hyphal extension. Additionally, both ionophores induced profuse mycelium branching and upward hyphal growth. Hyphae growing on nigericin-containing media also burst at the apex. Both ionophores caused a rapid inhibition in the apically-occurring synthesis of structural wall polysaccharides, but they did not affect mitochondrial energy conservation. With the use of DiBAC, a membrane-potential sensitive fluorophore, it was excluded that their effects were due to depletion of the plasma membrane potential. Considering that both ionophores exchange H⁺ for different metallic ions, we concluded that their effect was due to dissipation of a proton gradient, which is directly or indirectly involved in the apical growth of the fungus. This revised version was published online in June 2006 with corrections to the Cover Date.     

DNA indels in coding regions reveal selective constraints on protein evolution in the human lineage

Background  

Insertions and deletions of DNA segments (indels) are together with substitutions the major mutational processes that generate genetic variation. Here we focus on recent DNA insertions and deletions in protein coding regions of the human genome to investigate selective constraints on indels in protein evolution.     

Preparation of cross-linked carboxymethyl chitosan for repairing sciatic nerve injury in rats

A successful nerve regeneration process was achieved with nerve repair tubes made up of 1-ethyl-3(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) cross-linked carboxymethyl chitosan (CM-chitosan) with improved biodegradability. Chitosan has a very slow degradation rate, while the EDC cross-linked CM-chitosan tubes degraded to 30% of original weight during 8 weeks of incubation in lysozyme solution. In vitro cell culture indicated that the CM-chitosan films presented no cytotoxicity to Schwann cells. From in vivo studies using a 10 mm rat sciatic nerve defect model investigated by histomorphometry analysis, the average diameter of the fibers and the average thickness of myelin sheath in the CM-chitosan tubes were 3.7 ± 0.33 and 0.33 ± 0.04 μm, respectively, which demonstrated equivalence to nerve autografts (the current “gold” standard); furthermore, the average fiber density in the CM-chitosan tubes was 20.5 × 10³/mm², which was similar to that of autografts (21 × 10³/mm²) and significantly higher than that of common chitosan tubes (15.3 × 10³/mm²).     

Anti-Osteoporotic Drug Release from Ordered Mesoporous Bioceramics: Experiments and Modeling

The release of a potent bone-resorption inhibitor such as zoledronate from a versatile drug delivery system such as SBA 15 has been modeled. The initial and boundary conditions have been defined, together with the system parameters, including the determination of equilibrium and transport parameters. Additionally, the experimental model of the same system has been observed to validate the prediction here developed. This approach represents a powerful tool for the designing of mesoporous implantable drug delivery systems because their release kinetics can be predicted in advance, and this leads to a considerable time and resources saving.     

Selenite and ebselen supplementation attenuates <Emphasis Type="SmallCaps">d</Emphasis>-galactose-induced oxidative stress and increases expression of SELR and SEP15 in rat lens

Selenite and ebselen supplementation has been shown to possess anti-cataract potential in some experimental animal models of cataract, however, the underlying mechanisms remain unclear. The present study was designed to evaluate the anti-cataract effects and the underlying mechanisms of selenite and ebselen supplementation on galactose induced cataract in rats, a common animal model of sugar cataract. Transmission electron microscopy images of lens fiber cells (LFC) and lens epithelial cells (LEC) were observed in d-galactose-induced experimental cataractous rats treated with or without selenite and ebselen, also redox homeostasis and expression of proteins such as selenoprotein R (SELR), 15kD selenoprotein (SEP15), superoxide dismutase 1 (SOD1), catalase (CAT), β-crystallin protein, aldose reductase (AR) and glucose-regulated protein 78 (GRP78) were estimated in the lenses. The results showed that d-galactose injection injured rat lens and resulted in cataract formation; however, selenite and ebselen supplementation markedly alleviated ultrastructural injury of LFC and LEC. Moreover, selenite and ebselen supplementation could mitigate the oxidative damage in rat lens and increase the protein expressions of SELR, SEP15, SOD1, CAT and β-crystallin, as well as decrease the protein expressions of AR and GRP78. Taken together, these findings for the first time reveal the anti-cataract potential of selenite and ebselen in galactosemic cataract, and provide important new insights into the anti-cataract mechanisms of selenite and ebselen in sugar cataract.