Oligonucleotide Insecticides for Green Agriculture: Regulatory Role of Contact DNA in Plant–Insect Interactions

Insects vastly outnumber us in terms of species and total biomass, and are among the most efficient and voracious consumers of plants on the planet. As a result, to preserve crops, one of the primary tasks in agriculture has always been the need to control and reduce the number of insect pests. The current use of chemical insecticides leads to the accumulation of xenobiotics in ecosystems and a decreased number of species in those ecosystems, including insects. Sustainable development of human society is impossible without useful insects, so the control of insect pests must be effective and selective at the same time. In this article, we show for the first time a natural way to regulate the number of insect pests based on the use of extracellular double-stranded DNA secreted by the plant Pittosporum tobira. Using a principle similar to one found in nature, we show that the topical application of artificially synthesized short antisense oligonucleotide insecticides (olinscides, DNA insecticides) is an effective and selective way to control the insect Coccus hesperidum. Using contact oligonucleotide insecticide Coccus-11 at a concentration of 100 ng/μL on C. hesperidum larvae resulted in a mortality of 95.59 ± 1.63% within 12 days. Green oligonucleotide insecticides, created by nature and later discovered by humans, demonstrate a new method to control insect pests that is beneficial and safe for macromolecular insect pest management.     

Benchmarking advanced architecture computers

Recently, a number of advanced architecture machines have become commercially available. These new machines promise better cost performance than traditional computers, and some of them have the potential of competing with current supercomputers, such as the CRAY X-MP, in terms of maximum performance. This paper describes the methodology and results of a pilot study of the performance of a broad range of advanced architecture computers using a number of complete scientific application programs. The computers evaluated include:

• 1 shared-memory bus architecture machines such as the Alliant FX/8, the Encore Multimax, and the Sequent Balance and Symmetry
• 2 shared-memory network-connected machines such as the Butterfly
• 3 distributed-memory machines such as the NCUBE, Intel and Jet Propulsion Laboratory (JPL)/Caltech hypercubes
• 4 very long instruction word machines such as the Cydrome Cydra-5
• 5 SIMD machines such as the Connection Machine
• 6 ‘traditional’ supercomputers such as the CRAY X-MP, CRAY-2 and SCS-40.

Seven application codes from a number of scientific disciplines have been used in the study, although not all the codes were run on every machine. The methodology and guidelines for establishing a standard set of benchmark programs for advanced architecture computers are discussed. The CRAYs offer the best performance on the benchmark suite; the shared memory multiprocessor machines generally permitted some parallelism, and when coupled with substantial floating point capabilities (as in the Alliant FX/8 and Sequent Symmetry), provided an order of magnitude less speed than the CRAYs. Likewise, the early generation hypercubes studied here generally ran slower than the CRAYs, but permitted substantial parallelism from each of the application codes.     

Preparation,Characterisation, and Rheological Behaviour of Starch-Sodium Trimetaphosphate Hydrogels

Ionic biopolymer hydrogels were prepared by the cross-linking of starches with sodium trimetaphosphate in alkaline medium at 40°C for 2 hours. The swelling capacity is relatively high — up to 310 g H₂0/g polymer. Salt solutions have a marked influence, and result in shrinkage but not in a total collapse. The effect of both the cross-linker and substrate concentrations on the swelling and rheological properties was investigated. The influence of temperature and NaOH concentration on the rheological behaviour suggests that they are both significant in determining the gel properties because of the readiness of the diester phosphate bonds to undergo hydrolysis. The molecular weight between two entanglement points (M_e) and the effectiveness of cross-linking [n_e(r)/n_e(t)] were estimated from the observed G_p′ values, and those calculated from complete conversion of the cross-linker. The effectiveness of cross-linking lay between 0.2 and 2.74% for 10% wlw gels, and reached a maximum of 48.1% at the higher substrate concentration of 20% wlw. ¹³C-NMR signals from the anhydroglucose units became broader and decreased in intensity with rising cross-linker concentration due to the restricted motion arising from the additional bonding.