A central aim of the original proposal was the concept of a circulating low flow regimen above the reconstituted streambed: “The park design would be centered about a small creek to be reestablished within the right of way by pumping Temescal Creek water to ground level. The reconstituted creek would harmonize with and accentuate the linear nature of the proposed park, providing a focus for lay out of trails, resting spots, and landscaping. The design of park trails would be integrated with the creek and the narrow right or way to achieve a corridor effect inviting the user to walk and experience what the park has to offer. The reconstituted small creek will also serve as a local storm drain by receiving runoff from adjoining properties which have historically drained to the creek”. The other project studied is located in northeastern Ventura County, near the Santa Susanna Pass. Regionally, White Oak Creek is tributary to the Arroyo Simi, which drains the Simi Valley over a distance of approximately 36 miles in a southeasterly direction towards the Oxnard flood plain and Ventura Harbor. The White Oak Creek restoration program was part of a coordinated restoration effort involving a number of developers who have participating in building out housing and other uses within the Douglas Ranch Specific Plan Area. The segment of White Oak Creek comparison study was implemented by Standard Pacific Homes under the regulatory authority of the Corps of Engineers, Department of Fish and Game, and the City of Simi Valley. The restoration program was designed to satisfy two purposes: first, to compensate for the major disruptions to White Oak Creek which resulted from the construction of access roads and flood control measures,indoor growers and to create a common area that functions as both a habitat amenity and as a density buffer and urban design feature within the neighborhoods situated on either side of the Creek.
The Standard Pacific Homes White Oak Creek restoration is immediately linked upstream to a major flood control facility that was built within the Creek’s active streambed boundary in the newly constructed Mount Sinai Memorial Park. To comply with the Clean Water Act, horticultural riparian restoration programs were required for both the Memorial Park and the Standard Pacific residential development. As in the case of the Temescal Creek project, the scope of these restoration projects was clearly flood control, not process driven. The Standard Pacific Homes restoration included a subdivision of land which set aside about three acres of riparian restoration which is served by conducting stored detention waters beneath a manufactured, at grade, “re-constructed” streambed alignment. This reconstructed streambed carries a perennial flow of up to 195 c.f.s. through a diversion from the immediately upstream detention structure . The upstream detention basin gathers both neighborhood street discharge, as well as potential irrigation run-off from the Memorial Park as well as storm water flows.The gradients between the cemetery and residential projects were carefully adjusted and matched. In contrast to the Temescal Creek program, this artificial streambed was designed, disclosed in detail, and is considered a success by both the regulatory agency and the lead agency . Although flood control issues were primary considerations, in this case riparian horticulture restoration and habitat planning were also considered to be of primary importance—unlike Temescal Creek. This is clearly expressed in both the planning efforts and the design. The adjacent development changed ‘Faux’ White Oak Creek from a natural ephemeral channel to a manufactured perennial flow channel. This is a common outcome in southern California restoration projects because most of the time, such projects are designed to incorporate increased continual flows from upstream residential developments.As an amenity, creating a protected common area with habitat functions in a contemporary subdivision is unusual. The reconstructed reach of White Oak Creek now has the character of a young riparian greenbelt. Based on my review of the monitoring records , over the period of monitoring, perennial flow has been provided without interruption into the Standard Pacific Homes restoration area. This site has been under regulatory monitoring for four years.
The monitoring period has been extended beyond the established five-year time frame because of a series of early failures which more frequent monitoring would have revealed. The relative success of each project is compared in Table 1 through a series of defined success criteria. Unlike the outcome at Temescal Creek, for this project, there is a close correlation between original concept and implementation. The low flow diversion has been carefully designed so that it is reliable and operates within the parameters of the source detention waters. The low flow device is calibrated not to rainfall data but to neighborhood runoff flow rates, the actual reliable source of water for the restoration. In this respect, “natural” hydrologic conditions were determined not to be the governing design requirement for long-term success—flow rates out of the upstream neighborhoods were the determinant. The establishment of a firm legal basis for the protection of the restored area, , and the creation of an enclosure around the restoration site have ensured that the surrounding community does not encroach upon the project.Two different strategies of Fe uptake have been described in plants. The so-called chelation strategy , which is mainly found in graminaceous plants, is based on the excretion of phytosideropores to the rhizosphere. Phytosideropores rapidly chelate Fe, to form Fe-PS chelates that are subsequently transported into the root cells through a specific transporter. The so called reduction strategy relies on the coordinated action of a membrane bound Fe reductase, that reduces Fe to Fe, an Fe uptake transporter and an H+ -ATPase that lowers the pH of the rhizosphere, is mainly used by non graminaceous plants, including Beta vulgaris. The reduction strategy includes root morphological, physiological and biochemical changes that lead to an increased capacity for Fe uptake. Morphological changes include root tip swelling, development of transfer cells and an increase in the number of lateral roots, leading to an increase in the root surface in contact with the medium. Some plants are able to accumulate and/or release both reducing and chelating substances, such as phenolics and flavins, which may have a role in Fe acquisition.
Iron has been shown to down-regulate riboflavin synthesis in flavinogenic yeast strains and some bacteria. In plants, Rbfl and derivatives are accumulated and/ or excreted in Fe-deficient roots and could act as a redox bridge for electron transport to the Fe reductase. Moreover, FRO2 belongs to a super family of flavocytochrome oxidoreductases, and a recent study confirmed that the FRO2 protein contains FAD sequence motifs on the inside of the membrane. Also, a connection between Fe deficiency perception and Rbfl excretion has been described to occur through basic helixloop-helix transcription factors in Arabidopsis thaliana. At the metabolic level, increases in the activity of phosphoenolpyruvate carboxylase and several enzymes of the glycolytic pathway and the tricarboxylic acid cycle have been found in different plant species grown under Fe deficiency. Transcriptomic and proteomic studies in Fe deficient plants have also reported increases in root transcript and protein abundances, respectively, of enzymes related to the glycolytic and TCA cycle pathways, among others. Iron deficiency also induces an accumulation of organic acids,danish trolley mainly malate and citrate, in roots. The induction of C metabolism in roots of Fe-deficient plants would not only provide a source of reducing power, protons and ATP for the Fe reductase and H+-ATPase enzymes, but also lead to an anaplerotic root C fixation. Carbon accumulated in roots is exported in the form of organic acids via xylem to leaves, which have otherwise drastically reduced photosynthetic rates when Fe-deficient. The higher energy requirements in Fedeficient root cells are tackled by increasing mitochondrial oxidative processes, and roots from Fe-deficient plants show enhanced respiratory activities and higher O2 consumption rates. On the other hand, the mitochondrial respiratory chain is strongly affected under Fe-deficient conditions, since some of its components are Fe-containing enzymes. Iron deficiency leads to an enhancement of different ROS detoxification strategies. Furthermore, an increase in anaerobic metabolism has also been described in Fe-deficient roots, probably as an strategy to oxidize all the reducing power generated by glycolysis and TCA cycle that can not be easily oxidized in the respiratory chain. When resupplied with Fe, Fe-deficient plants reorganize its metabolism by readjusting metabolic cycles and changing root morphology towards those typical of Fe-sufficient plants. The most common approach used to study Fe deficiency in roots is to analyze only a small number of genes, proteins and/or metabolites. A more comprehensive knowledge of the processes taking place in Fe-deficient roots has been recently provided by the application of modern techniques allowing for the simultaneous and untargeted analysis of multiple genes or proteins. The aim of this work was to characterize the changes induced in the root tip proteome and metabolome of sugar beet plants in response to Fe deficiency and resupply, in order to provide a holistic view of the metabolic processes occurring in plants under different Fe status.The polypeptide pattern of root tip extracts was obtained by 2-D IEF-SDS PAGE electrophoresis. Real scans of typical 2-D gels are shown in Figure 1; an average number of 141 and 148 polypeptides were detected in Fe-sufficient and Fe-deficient plants, respectively .Several causes may account for this discrepancy, including i) protein extraction method and amount of protein loaded in the gels, ii) gel size, iii) pI range and iv) sensitivity of the staining method.
Averaged 2-D polypeptide maps were obtained using gels of three independent preparations, each from a different batch of plants . To better describe polypeptide changes we built a composite averaged virtual map containing all spots present in both Fe-deficient and control root tip extracts . Iron deficiency caused 2-fold increases in 29 spots and 2-fold decreases in signal intensity in 13 spots . Furthermore, 6 spots were only detected in Fe-sufficient plant samples and 13 spots were only detected in Fe-deficient plants . All polypeptides in the composite averaged map are depicted again in Figure 1D, to permit annotation of those polypeptides where identification was achieved by matrix assisted laser desorption ionization – time of flight MS . These polypeptides were labeled from a to v as described in Figure 1D, and homologies found are described in detail in Table 1. From the 29 spots that showed increases in signal in root tip extracts of Fe-deficient as compared to Fe-sufficient controls, the 20 more abundant were excised and analyzed by MALDI-MS. Since the sugar beet genome has not been sequenced yet and few sequences are avail-able in the databases, identification was performed by homology searches with proteins from other plant species. From the 20 spots analyzed, 14 proteins were identified . These include proteins related to glycolysis such as fructose 1,6-bisphosphate aldolase , triose-phosphate isomerase , 3-phosphoglycerate kinase and enolase . Three spots gave significant matches to malate dehydrogenase , and two more polypeptides presented homology with α and β subunits from F1 ATP synthase . Other proteins increasing in root tip extracts from Fe-deficient sugar beet plants as compared to the controls were fructokinase and formate dehydrogenase . Also, one spot gave significant matches to a cytosolic peptidase At1g79210/YUP8H12R_1 . Spot n gave significant match to a glycine rich protein, which possibly has a role in RNA transcription or processing during stress conditions. From the 13 spots detected de novo in proteome maps from root tip extracts of Fe-deficient plants , the 6 more abundant were excised and analyzed by MALDI-MS, resulting in only 2 positive matches . These significant matches were found for glyceraldehyde 3-phosphate dehydrogenase and DMRL .Changes in the amount of DMRL as well as DMRL gene expression and flavin analysis were further studied using root tip extracts of Fe-sufficient, Fe-deficient and Fere supplied sugar beet plants . From the 13 spots showing a decrease in signal intensity in root tip extracts from Fe-deficient plants as compared to controls , 3 were identified by MALDI-MS. Spots q and rgave a significant match to nucleoside diphosphate kinase I and to oxalate oxidase-like germin, respectively.