Expression of snowdrop lectin (GNA) in transgenic rice plants confers resistance to rice brown planthopper

Snowdrop lectin ( Galanthus nivalis agglutinin; GNA) has been shown previously to be toxic towards rice brown planthopper ( Nilaparvata lugens ; BPH) when administered in artificial diet. BPH feeds by phloem abstraction, and causes ‘hopper burn’, as well as being an important virus vector. To evaluate the potential of the gna gene to confer resistance towards BPH, transgenic rice ( Oryza sativa L.) plants were produced, containing the gna gene in constructs where its expression was driven by a phloem-specific promoter (from the rice sucrose synthase RSs1 gene) and by a constitutive promoter (from the maize ubiquitin ubi1 gene). PCR and Southern analyses on DNA from these plants confirmed their transgenic status, and that the transgenes were transmitted to progeny after self-fertilization. Western blot analyses revealed expression of GNA at levels of up to 2.0% of total protein in some of the transgenic plants. GNA expression driven by the RSs1 promoter was tissue-specific, as shown by immunohistochemical localization of the protein in the non-lignified vascular tissue of transgenic plants. Insect bioassays and feeding studies showed that GNA expressed in the transgenic rice plants decreased survival and overall fecundity (production of offspring) of the insects, retarded insect development, and had a deterrent effect on BPH feeding. gna is the first transgene to exhibit insecticidal activity towards sap-sucking insects in an important cereal crop plant.     

BMRP is a Bcl-2 binding protein that induces apoptosis

Members of the Bcl-2 family of proteins play important roles in the regulation of cell death by apoptosis. The yeast Two-Hybrid system was utilized to identify a protein that interacts with the anti-apoptotic protein Bcl-2, designated BMRP. This protein corresponds to a previously known mitochondrial ribosomal protein (MRPL41). Binding experiments confirmed the interaction of BMRP to Bcl-2 in mammalian cells. Subcellular fractionation by differential centrifugation studies showed that both Bcl-2 and BMRP are localized to the same fractions (fractions that are rich in mitochondria). Northern blot analysis revealed a major bmrp mRNA band of approximately 0.8 kb in several human tissues. Additionally, a larger 2.2 kb mRNA species was also observed in some tissues. Western blot analysis showed that endogenous BMRP runs as a band of 16-17 kDa in SDS-PAGE. Overexpression of BMRP induced cell death in primary embryonic fibroblasts and NIH/3T3 cells. Transfection of BMRP showed similar effects to those observed by overexpression of the pro-apoptotic proteins Bax or Bad. BMRP-stimulated cell death was counteracted by co-expression of Bcl-2. The baculoviral caspase inhibitor p35 also protected cells from BMRP-induced cell death. These findings suggest that BMRP is a mitochondrial ribosomal protein involved in the regulation of cell death by apoptosis, probably affecting pathways mediated by Bcl-2 and caspases.     

<Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated genetic transformation and development of herbicide-resistant sugarcane (<Emphasis Type="Italic">Saccharum</Emphasis> species hybrids) using axillary buds

Direct regeneration from explants without an intervening callus phase has several advantages, including production of true type progenies. Axillary bud explants from 6-month-old sugarcane cultivars Co92061 and Co671 were co-cultivated with Agrobacterium strains LBA4404 and EHA105 that harboured a binary vector pGA492 carrying neomycin phosphotransferase II, phosphinothricin acetyltransferase (bar) and an intron containing -glucuronidase (gus-intron) genes in the T-DNA region. A comparison of kanamycin, geneticin and phosphinothricin (PPT) selection showed that PPT (5.0 mg l^–1) was the most effective selection agent for axillary bud transformation. Repeated proliferation of shoots in the selection medium eliminated chimeric transformants. Transgenic plants were generated in three different steps: (1) production of putative primary transgenic shoots in Murashige-Skoog (MS) liquid medium with 3.0 mg l^–1 6-benzyladenine (BA) and 5.0 mg l^–1 PPT, (2) production of secondary transgenic shoots from the primary transgenic shoots by growing them in MS liquid medium with 2.0 mg l^–1 BA, 1.0 mg l^–1 kinetin (Kin), 0.5 mg l^–1 -napthaleneacetic acid (NAA) and 5.0 mg l^–1 PPT for 3 weeks, followed by five more cycles of shoot proliferation and selection under same conditions, and (3) rooting of transgenic shoots on half-strength MS liquid medium with 0.5 mg l^–1 NAA and 5.0 mg l^–1 PPT. About 90% of the regenerated shoots rooted and 80% of them survived during acclimatisation in greenhouse. Transformation was confirmed by a histochemical -glucuronidase (GUS) assay and PCR amplification of the bar gene. Southern blot analysis indicated integration of the bar gene in two genomic locations in the majority of transformants. Transformation efficiency was influenced by the co-cultivation period, addition of the phenolic compound acetosyringone and the Agrobacterium strain. A 3-day co-cultivation with 50 M acetosyringone considerably increased the transformation efficiency. Agrobacterium strain EHA105 was more effective, producing twice the number of transgenic shoots than strain LBA4404 in both Co92061 and Co671 cultivars. Depending on the variety, 50–60% of the transgenic plants sprayed with BASTA (60 g l^–1 glufosinate) grew without any herbicide damage under greenhouse conditions. These results show that, with this protocol, generation and multiplication of transgenic shoots can be achieved in about 5 months with transformation efficiencies as high as 50%.Abbreviations BA 6-Benzyladenine - CaMV Cauliflower mosaic virus - GUS -Glucuronidase - Kin Kinetin - NAA -Naphthaleneacetic acid - Nos Nopaline synthase - nptII Neomycin phosphotransferase II - PCR Polymerase chain reaction - PPT Phosphinothricin - YEP Yeast extract and peptone     

Extracellular small heat shock proteins: exosomal biogenesis and function

Small heat shock proteins (sHsps) belong to the family of heat shock proteins (Hsps): some are induced in response to multiple stressful events to protect the cells while others are constitutively expressed. Until now, it was believed that Hsps, including sHsps, are present inside the cells and perform intracellular functions. Interestingly, several groups recently reported the extracellular presence of Hsps, and sHsps have also been detected in sera/cerebrospinal fluids in various pathological conditions. Secretion into the extracellular milieu during many pathological conditions suggests additional or novel functions of sHsps in addition to their intracellular properties. Extracellular sHsps are implicated in cell-cell communication, activation of immune cells, and promoting anti-inflammatory and anti-platelet responses. Interestingly, exogenous administration of sHsps showed therapeutic effects in multiple disease models implying that extracellular sHsps are beneficial in pathological conditions. sHsps do not possess signal sequence and, hence, are not exported through the classical Endoplasmic reticulum-Golgi complex (ER-Golgi) secretory pathway. Further, export of sHsps is not inhibited by ER-Golgi secretory pathway inhibitors implying the involvement of a nonclassical secretory pathway in sHsp export. In lieu, lysoendosomal and exosomal pathways have been proposed for the export of sHsps. Heat shock protein 27 (Hsp27), αB-crystallin (αBC), and Hsp20 are shown to be exported by exosomes. Exosomes packaged with sHsps have beneficial effects in in vivo disease models. However, secretion mechanisms and therapeutic use of sHsps have not been elucidated in detail. Therefore, this review aimed at highlighting the current understanding of sHsps (Hsp27, αBC, and Hsp20) in the extracellular medium.     

Anomalous Charge‐Extraction Behavior for Graphene‐Oxide (GO) and Reduced Graphene‐Oxide (rGO) Films as Efficient p‐Contact Layers for High‐Performance Perovskite Solar Cells

Reduced graphene oxides (rGO) are synthesized via reduction of GO with reducing agents as a hole‐extraction layer for high‐performance inverted planar heterojunction perovskite solar cells. The best efficiencies of power conversion (PCE) of these rGO cells exceed 16%, much greater than those made of GO and poly(3,4‐ethenedioxythiophene):poly(styrenesulfonate) films. A flexible rGO device shows PCE 13.8% and maintains 70% of its initial performance over 150 bending cycles. It is found that the hole‐extraction period is much smaller for the GO/methylammonium lead‐iodide perovskite (PSK) film than for the other rGO/PSK films, which contradicts their device performances. Photoluminescence and transient photoelectric decays are measured and control experiments are performed to prove that the reduction of the oxygen‐containing groups in GO significantly decreases the ability of hole extraction from PSK to rGO and also retards the charge recombination at the rGO/PSK interface. When the hole injection from PSK to GO occurs rapidly, hole propagation from GO to the indium‐doped tin oxide (ITO) substrate becomes a bottleneck to overcome, which leads to a rapid charge recombination that decreases the performance of the GO device relative to the rGO device.