Edenspace Systems (United States)

Abstract The worldwide interest in the production of biofuels from maize and other energy crops has prompted us to write this article. Maize is one the most important commercial crops in the world and is valued for its food, fiber, oil, and other by‐products. In this chapter, the advances in maize tissue culture and transformation, in gene discovery and expression optimization, and maize ethanol processing are reviewed. The position affirmed here is that technical advances in maize biotechnology make it today's model plant for ethanol recovery.

In feeding, aphids inject saliva into plant tissues, gaining access to phloem sap and eliciting (and sometimes overcoming) plant responses. We are examining the involvement, in this aphid-plant interaction, of individual aphid proteins and enzymes, as identified in a salivary gland cDNA library. Here, we focus on a salivary protein we have arbitrarily designated Protein C002. We have shown, by using RNAi-based transcript knockdown, that this protein is important in the survival of the pea aphid (Acyrthosiphon pisum) on fava bean, a host plant. Here, we further characterize the protein, its transcript, and its gene, and we study the feeding process of knockdown aphids. The encoded protein fails to match any protein outside of the family Aphididae. By using in situ hybridization and immunohistochemistry, the transcript and the protein were localized to a subset of secretory cells in principal salivary glands. Protein C002, whose sequence contains an N-terminal secretion signal, is injected into the host plant during aphid feeding. By using the electrical penetration graph method on c002-knockdown aphids, we find that the knockdown affects several aspects of foraging and feeding, with the result that the c002-knockdown aphids spend very little time in contact with phloem sap in sieve elements. Thus, we infer that Protein C002 is crucial in the feeding of the pea aphid on fava bean.

Transformation of maize (Zea mays L.) split‐seed explants from inbred line R23 was performed following particle bombardment with a construct carrying the Arabidopsis transcriptional factor CBF3 under the control of the inducible promoter rd29A and the selectable marker hygromycin phosphotransferase. Overexpressing CBF3 has been shown to enhance cold, drought, and salt tolerance in Arabidopsis, tobacco (Nicotiana tabacum L.), and wheat (Triticum aestivum L.). The CBF3 gene was detected in 18 lines by polymerase chain reaction (PCR), and stable integration of multiple copies of CBF3 was confirmed by Southern blot analysis in three selected lines. Reverse transcription PCR detected expression of CBF3 in the transgenic lines under unstressed conditions despite the use of the stress‐inducible rd29A promoter. This constitutive expression was associated with growth retardation and sterility in most of the transgenic lines. Transmission of the gene in a Mendelian fashion to T1 and T2 generations was confirmed in one line by Southern blot analysis. Plants of this line showed stress‐inducible expression of the CBF3 gene and hardly detectable expression under unstressed conditions along with significant tolerance to cold, drought, and salinity compared with wild‐type plants. These results demonstrate that stress‐inducible overexpression of CBF3 has the potential to enhance abiotic stress tolerance in corn.

A genetic screen was performed to isolate mutants showing increased arsenic tolerance using an Arabidopsis thaliana population of activation tagged lines. The most arsenic-resistant mutant shows increased arsenate and arsenite tolerance. Genetic analyses of the mutant indicate that the mutant contains two loci that contribute to arsenic tolerance, designated ars4 and ars5. The ars4ars5 double mutant contains a single T-DNA insertion, ars4, which co-segregates with arsenic tolerance and is inserted in the Phytochrome A (PHYA) gene, strongly reducing the expression of PHYA. When grown under far-red light conditions ars4ars5 shows the same elongated hypocotyl phenotype as the previously described strong phyA-211 allele. Three independent phyA alleles, ars4, phyA-211 and a new T-DNA insertion allele (phyA-t) show increased tolerance to arsenate, although to a lesser degree than the ars4ars5 double mutant. Analyses of the ars5 single mutant show that ars5 exhibits stronger arsenic tolerance than ars4, and that ars5 is not linked to ars4. Arsenic tolerance assays with phyB-9 and phot1/phot2 mutants show that these photoreceptor mutants do not exhibit phyA-like arsenic tolerance. Fluorescence HPLC analyses show that elevated levels of phytochelatins were not detected in ars4, ars5 or ars4ars5, however increases in the thiols cysteine, gamma-glutamylcysteine and glutathione were observed. Compared with wild type, the total thiol levels in ars4, ars5 and ars4ars5 mutants were increased up to 80% with combined buthionine sulfoximine and arsenic treatments, suggesting the enhancement of mechanisms that mediate thiol synthesis in the mutants. The presented findings show that PHYA negatively regulates a pathway conferring arsenic tolerance, and that an enhanced thiol synthesis mechanism contributes to the arsenic tolerance of ars4ars5.

Arsenic contamination of drinking water poses serious health risks to millions of people worldwide. Current technologies used to clean arsenic-contaminated water have significant drawbacks, such as high cost and generation of large volumes of toxic waste. In this study, we investigated the potential of using recently identified arsenic-hyperaccumulating ferns to remove arsenic from drinking water. Hydroponically cultivated, two arsenic-hyperaccumulating fern species (Pteris vittata and Pteris cretica cv. Mayii) and a nonaccumulating fern species (Nephrolepis exaltata) were suspended in water containing 73As-labeled arsenic with initial arsenic concentrations ranging from 20 to 500 microg L(-1). The efficiency of arsenic phytofiltration by these fern species was determined by continuously monitoring the depletion of 73As-labeled arsenic concentration in the water. With an initial water arsenic concentration of 200 microg L(-1), P. vittata reduced the arsenic concentration by 98.6% to 2.8 microg L(-1) in 24 h. When the initial water arsenic was 20 microg L(-1), P. vittata reduced the arsenic concentration to 7.2 microg L(-1) in 6 h and to 0.4 microg L(-1) in 24 h. At similar plant ages, both P. vittata and P. cretica had similar arsenic phytofiltration efficiency and were able to rapidly remove arsenic from water to achieve arsenic levels below the new drinking water limit of 10 microg L(-1). However, N. exaltata failed to reduce water arsenic to achieve the limit under the same experimental conditions. The significantly higher efficiency of arsenic phytofiltration by arsenic-hyperaccumulating fern species is associated with their ability to rapidly translocate absorbed arsenic from roots to shoots. The nonaccumulating fern N. exaltata was unable to translocate the absorbed arsenic to the shoots. Our results demonstrate that the arsenic-phytofiltration technique may provide the basis for a solar-powered hydroponic technique that enables small-scale cleanup of arsenic-contaminated drinking water.

This chapter describes the geochemical behavior of several radionuclides that are commonly found in contaminated soils and their association with soil minerals. The major concern of radionuclide-contaminated soils is that they represent a potential human health risk due to the emission of ionizing radiation. The chapter introduces the reader specifically to the concept of radioactivity and the problems and solutions involved in the remediation of soils contaminated by radionuclides. The importance of mineralogical information for optimizing proven and innovative soil remedial approaches is assessed and illustrated. The chapter provides a flowchart that uses physicochemical and mineralogical data of each soil and demonstrates how the information gleaned from such a characterization can be used to direct the selection of the appropriate remedial technology. It concludes with case study on uranium-contaminated soils at Fernald, Ohio.

Many types of gravity surveys have been conducted or proposed to support very accurate inertial navigation. For example, gravimetry and satellite altimetry data now exist over many areas of the world and new techniques are being developed such as satellite-to-satellite tracking and airborne gravity gradiometry. This paper presents a universal approach for analyzing the navigation system improvements afforded by these surveys. Comparisons are shown of the navigation RMS errors for five survey methods. These comparisons reveal the tradeoff between gravity survey resolution and inertial navigation system accuracy.