Distribution of glycan motifs at the surface of midgut cells in the cotton leafworm (Spodoptera littoralis) demonstrated by lectin binding

Glycans are involved in many biological phenomena, including signal transduction, cell adhesion, immune response or differentiation. Although a few papers have reported on the role of glycans in the development and proper functioning of the insect midgut, no data are available regarding the localization of the glycan structures on the surface of the cells in the gut of insects. In this paper, we analyzed the spatial distribution of glycans present on the surface of the midgut cells in larvae of the cotton leafworm Spodoptera littoralis, an important agricultural pest insect worldwide. For this purpose, we established primary midgut cell cultures, probed these individual cells that are freely suspended in liquid medium with a selection of seven fluorescently labeled lectins covering a range of different carbohydrate binding specificities [mannose oligomers (GNA and HHA), GalNAc/Gal (RSA and SSA), GlcNAc (WGA and Nictaba) and Neu5Ac(alpha-2,6)Gal/GalNAc (SNA-I)], and visualized the interaction of these lectins with the different zones of the midgut cells using confocal microscopy. Our analysis focused on the typical differentiated columnar cells with a microvillar brush border at their apical side, which are dominantly present in the Lepidopteran midgut and function in food digestion and absorption, and as well as on the undifferentiated stem cells that are important for midgut development and repair. Confocal microscopy analyses showed that the GalNAc/Gal-binding lectins SSA and RSA and the terminal GlcNAc-recognizing WGA bound preferentially to the apical microvillar zone of the differentiated columnar cells as compared to the basolateral pole. The reverse result was observed for the mannose-binding lectins GNA and HHA, as well as Nictaba that binds preferentially to GlcNAc oligomers. Furthermore, differences in lectin binding to the basal and lateral zones of the cell membranes of the columnar cells were apparent. In the midgut stem cells. GNA and Nictaba bound more strongly to the membrane of these undifferentiated cells compared to the microvillar pole of the columnar cells, while SSA, HHA, WGA, and SNA-I showed stronger binding to the microvilli. Our results indicated that polarization of the midgut cells is also reflected by a specific distribution of glycans, especially between the basal and microvillar pole. The data are discussed in relation to the functioning and development of the insect midgut

Glycosylation in Tribolium castaneum : composition, physiological significance and exploitation for pest control

The majority of all the proteins undergoes glycosylation. This post-translational modification of proteins is involved in numerous biological processes and an erroneous glycosylation is often lethal. Following this logic interference with insect glycosylation is likely to be an effective way to control insect pests. Unfortunately, most of the knowledge on insect glycobiology comes from the research on Drosophila which lacks relevance in the context of pest insect control. This work focused on the discovery of the physiological importance of N-glycosylation in the red flour beetle, Tribolium castaneum, which is a pest and a model insect. Additionally, this PhD thesis investigates the use of glycan-binding proteins (lectins) and the disruption of N-glycosylation as control strategies against pest beetles. Lectins have high insecticidal activity against insect cells but when fed to the red flour beetle their efficiency was greatly impaired by susceptibility to proteolysis, low efficiency of passing through the peritrophic matrix and inefficient transport to the hemolymph. These factors restricting the insecticidal properties of lectins could be generalized to virtually all insecticidal proteins. Therefore these data can be used for a more rational selection of novel insecticidal toxins and enhancement of the activity of the currently used ones. By studying glycan composition, gene expression analysis and functional genomics it was determined that N-glycosylation is involved in insect metamorphosis. Regulated production of N-glycans was crucial for larval growth, progression of the life stages and development of adult appendages. Finally, disruption of the early stages of the N-glycosylation pathway appears to be promising strategy for future control of insect pests

Overcoming Hurdles In Real Time Modeling

Real time modeling and control sounds easy. Get data from the SCADA system, run the appropriate model and push the results back to the controls. What could be difficult about that? Plenty. Anyone attempting to do this work probably has run into some of the institutional, technical and personal hurdles in actually making this sort of system work. This paper will discuss the hurdles and ways to deal with them. The most daunting hurdle is that of security. Most modeling happens on computers connected to the internet. Water utility managers are justifiably terrified of all the bad things that lurk on the internet and want to protect their systems from them. At a minimum, SCADA systems are protected by fire walls, but more aggressive protection is provided by air gaps (sneaker nets) and some have even removed USB ports from computers in control rooms. This leaves modelers struggling to get current data, relying on old massaged data or moving modeling over to the control room side of the air gap. Next is the language barrier. To make real time control work, there groups of people need to communicate: operators, modelers and SCADA managers. But each speaks a unique language and meetings can bog down with each side trying to communicate. There are very few individuals who speak all three languages. Then it becomes necessary to sell modeling to control room operators who see models as an attempt to replace their jobs with a button tied to a computer. Operators need to be sold on the idea that they will do their jobs better but their positions will be safe, while upper management may be actively trying to reduce operator “head count”. This paper will give real world examples of dealing with each of these issues

Comparison Of Various Phased Approaches For The Constrained Minimum-Cost Design Of Water Distribution Networks

This work is aimed at analyzing and comparing three different phased approaches for constrained minimum-cost design of water distribution networks: the single-step design with demand feedback, the multi-step design without demand feedback and the multi-step design with demand feedback. The difference between the single-step design and the multi-step design lies in the fact that whereas the former entails optimizing a single construction step at a time, i.e. the current construction phase, the latter is based on the phasing of construction and then is aimed at optimizing the current construction phase and all the subsequent phases, included inside a certain temporal horizon, simultaneously. The demand feedback is here used as a pragmatic tool for updating the forecast at some specific time instant of the future demand growth: such an update is performed by setting the future demand growth equal to that really observed in the previous time step. Alternatively, the predicted demand growth rate at the generic time instant can be kept equal to the value assumed at the time instant when the generic node appears, without taking account of the demand variation really observed in time in the node (absence of demand feedback). Applications to a real case study show that the multi-step design with the demand feedback is the most reliable because it makes it possible to reduce the overall construction costs while attenuating the occurrence of pressure deficits in the various construction steps of the network

Some explicit formulations of Colebrook-White friction factor considering accuracy vs. computational speed

The Colebrook–White formulation of the friction factor is implicit and requires some iterations to be solved given a correct initial search value and a target accuracy. Some new explicit formulations to efficiently calculate the Colebrook–White friction factor are presented herein. The aim of this investigation is twofold: (i) to preserve the accuracy of estimates while (ii) reducing the computational burden (i.e. speed). On the one hand, the computational effectiveness is important when the intensive calculation of the friction factor (e.g. large-size water distribution networks (WDN) in optimization problems, flooding software, etc.) is required together with its derivative. On the other hand, the accuracy of the developing formula should be realistically chosen considering the remaining uncertainties surrounding the model where the friction factor is used. In the following, three strategies for friction factor mapping are proposed which were achieved by using the Evolutionary Polynomial Regression (EPR). The result is the encapsulation of some pieces of the friction factor implicit formulae within pseudo-polynomial structures

Technical Report EL-88-18: Reliability of the Federally Owned Water Main System

The reliability of the Federally Owned Water Main (FOWM) system was examined, and recommendations to improve system reliability are made. The existing FOWM system is very dependent upon three different pipe links. The first and most important link is the Francis Scott Key Bridge river crossing. This link carries the entire FOWM supply, and if taken out of service, an alternate means of supply must be used. At present, the only alternate source of supply is through interconnections with the adjacent Arlington County, Virginia, system. The second vital link is the 30-in. steel main which extends from the Key Bridge river crossing to the Pentagon. This line carries approximately 83 percent of the total delivery to the FOWM system. If taken out of service, all flow in the FOWM system would have to be routed through the 16-in. main along George Washington Parkway and Eisenhower Drive. During periods of high water use, flow in this 16-in. line would cause excessive friction losses. As a result, adequate system pressures cannot be maintained, and system demands cannot be fully met. The final critical pipe link is the feed to National Airport. This link consists of a 24-in. pipe and a 16-in. pipe connected in series. At present, this is the only source of water for National Airport. If this line were taken out of service, an alternate source of supply must be found. Furthermore, the available fire flow to the airport through this line during maximum daily demands falls below Insurance Services Office requirements. Several system improvements were evaluated to determine their contribution to the overall reliability of the FOWM system. System improvements consisted of operating existing and new interconnections, constructing new river crossings, installing a new storage tank, new line construction, and combinations of the above. System improvements were evaluated and ranked based on hydraulic performance, engineering impact, and total cost

Failure impact analysis of isolation valves in a water distribution

This is the author accepted manuscript. The final version is available from American Society of Civil Engineers via the DOI in this record.Isolation valves are crucial components of water distribution systems for separating pipe segments from the network for repair or maintenance purpose. This paper looks at the impacts of isolation valves failure on the three indictors including number of valves that are needed to isolate a distribution system segment, the size of distribution system segments and the shortfall in meeting demands during failure. A network with various isolation valve configurations in terms of the density of valves is used as a case study. The results obtained from the case study show that the failure of an isolation valve has substantially varying impacts on system performance during a shutdown. The density of valves in the network determines impacts of inoperable valves on a shutdown. Generally speaking, a higher density of isolation valves leads to the less impact of valve failure. Finally, several conclusions drawn from the critical valve analysis in this study could be applied to guide the isolation valve maintenance and management.Bentley Systems provided the software to conduct the hydraulic simulation and valve segmentation. This study is financially supported by the National Natural Science Foundation of China (51320105010, 51579027), the National Science and Technology Major Project (2014ZX03005001), and Ministry of Water Resource of China (Grant No.201401014-2), which are greatly acknowledged