Dysfunction of epithelial sodium transport: from human to mouse.

The highly amiloride-sensitive epithelial sodium channel (ENaC) is an apical membrane constituent of cells of many salt-absorbing epithelia. In the kidney, the functional relevance of ENaC expression has been well established. ENaC mediates the aldosterone-dependent sodium reabsorption in the distal nephron and is involved in the regulation of blood pressure. Mutations in genes encoding ENaC subunits are causative for two human inherited diseases: Liddle's syndrome, a severe form of hypertension associated with ENaC hyperfunction, and pseudohypoaldosteronism (PHA-1), a salt-wasting syndrome caused by decreased ENaC function. Transgenic mouse technologies provide a useful tool to study the role of ENaC in vivo. Different mouse lines have been established in which each of the ENaC subunits was affected. The phenotypes observed in these mice demonstrated that each subunit is essential for survival and for regulation of sodium transport in kidney and colon. Moreover, the alpha subunit plays a specific role in the control of fluid absorption in the airways at birth. Such mice can now be used to study the role of ENaC in various organs and can serve as models to understand the pathophysiology of these human diseases.

[Transport des pylônes dédiés à la bataille de la Somme, allégorie de la victoire, vers l'avenue des Champs-Elysées, autour du 13 juillet 1919] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54838

Animal Industry News, February 2004, Vol. 5, No. 1

Newsletter produced by Iowa Department of Agriculture and Land Stewardship.

Localization in sucrose gradients of the pyrophosphate-dependent proton transport of maize root membranes.

A maize (Zea mays L. cv LG 11) root homogenate was prepared and centrifuged to sediment the mitochondria. The pellet (6 KP) and the supernatant (6 KS) were collected and fractionated on linear sucrose density gradients. Marker enzymes were used to study the distribution of the different cell membranes in the gradients. The distribution of the ATP- and pyrophosphate-dependent proton pumping activities was similar after 3 hours of centrifugation of the 6 KS or the 6 KP fraction. The pumps were clearly separated from the mitochondrial marker cytochrome c oxidase and the plasmalemma marker UDP-glucose-sterolglucosyl-transferase. The pyrophosphate-dependent proton pump might be associated with the tonoplast, as the ATP-dependent pump, despite the lack of a specific marker for this membrane. However, under all the conditions tested, the two pumps overlapped the Golgi markers latent UDPase and glucan synthase I and the ER marker NADH-cytochrome c reductase. It is therefore not possible to exclude the presence of proton pumping activities on the Golgi or the ER of maize root cells. The two pumps (but especially the pyrophosphate-dependent one) were more active (or more abundant) in the tip than in the basal part of maize roots, indicating that these activities might be important in growth processes.

Acoustic transport of charge and spins in GaAs-based heterostructures

Report for the scientific sojourn carried out at the Paul Drude Institut für Festkörperelektronik of the Stanford University, USA, from 2010 to 2012. The objective of this project is the transport and control of electronic charge and spin along GaAs-based semiconductor heterostructures. The electronic transport has been achieved by taking advantage of the piezolectric field induced by surface acoustic waves in non-centrosymmetric materials like GaAs. This piezolectric field separates photogenerated electrons and holes at different positions along the acoustic wave, where they acummulate and are transported at the same velocity as the wave. Two different kinds of structures have been studied: quantum wells grown along the (110) direction, both intrinsic and n-doped, as well as GaAs nanowires. The analysis of the charge acoustic transport was performed by micro-photoluminescence, whereas the detection of the spin transport was done either by analyzing the polarization state of the emitted photoluminescence or by Kerr reflectometry. Our results in GaAs quantum wells show that charge and spin transport is clearly observed at the non-doped structures,obtaining spin lifetimes of the order of several nanoseconds, whereas no acoutically induced spin transport was detected for the n-doped quantum wells. In the GaAs nanowires, we were able of transporting successfully both electrons and holes along the nanowire axis, but no conservation of the spin polarization has been observed until now. The photoluminescence emitted by these structures after acoustic transport, however, shows anti-bunching characteristics, making this system a very good candidate for its use as single photon emitters.

Food security, food safety and small farmers

Some of the elements that characterize the globalization of food and agriculture are industrialization and intensification of agriculture and liberalization of agricultural markets, that favours elongation of the food chain and homogenization of food habits (nutrition transition), among other impacts. As a result, the probability of food contamination has increased with the distance and the number of “hands" that may contact the food (critical points); the nutritional quality of food has been reduced because of increased transport and longer periods of time from collection to consumption; and the number of food-related diseases due to changes in eating patterns has increased. In this context, there exist different agencies and regulations intended to ensure food safety at different levels, e.g. at the international level, Codex Alimentarius develops standards and regulations for the marketing of food in a global market. Although governments determine the legal framework, the food industry manages the safety of their products, and thus, develops its own standards for their marketing, such as the Good Agricultural Practices (GAP) programs. The participation of the private sector in the creation of regulatory standards strengthens the free trade of food products, favouring mostly large agribusiness companies. These standards are in most cases unattainable for small producers and food safety regulations are favouring removal of the peasantry and increase concentration and control in the food system by industrial actors. Particularly women, who traditionally have been in charge of the artisanal transformation process, can be more affected by these norms than men. In this project I am analysing the impcact of food safety norms over small farms, based on the case of artisanal production made by women in Spain.

Health effects of occupational exposure in a dairy food industry, with a specific assessment of exposure to airborne lactic acid bacteria

OBJECTIVE:: Lactic acid bacteria (LAB) are used in food industries as probiotic agents. The aim of this study is to assess the potential health effects of airborne exposure to a mix of preblend (LAB and carbohydrate) and milk powder in workers. METHODS:: A medical questionnaire, lung function tests, and immunologic tests were carried out on 50 workers. Occupational exposure to inhalable dust and airborne LAB was measured. RESULTS:: Workers not using respiratory masks reported more symptoms of irritation than workers using protection. Workers from areas with higher levels of airborne LAB reported the most health symptoms and the immune responses of workers to LAB was higher than the immune responses of a control population. CONCLUSIONS:: Measures to reduce exposure to airborne LAB and milk powder in food industries are recommended.

Industry Projections 2002 - 2012 Iowa Workforce Development Regions, 2002

Statewide and Regional projected industry employment 2002 - 2012

Vasopressin-dependent coupling between sodium transport and water flow in a mouse cortical collecting duct cell line.

Water balance is achieved through the ability of the kidney to control water reabsorption in the connecting tubule and the collecting duct. In a mouse cortical collecting duct cell line (mCCD(c11)), physiological concentrations of arginine vasopressin increased both electrogenic, amiloride-sensitive, epithelial sodium channel (ENaC)-mediated sodium transport measured by the short-circuit current (Isc) method and water flow (Jv apical to basal) measured by gravimetry with similar activation coefficient K(1/2) (6 and 12 pM, respectively). Jv increased linearly according to the osmotic gradient across the monolayer. A small but highly significant Jv was also measured under isoosmotic conditions. To test the coupling between sodium reabsorption and water flow, mCCD(c11) cells were treated for 24 h under isoosmotic condition with either diluent, amiloride, vasopressin or vasopressin and amiloride. Isc, Jv, and net chemical sodium fluxes were measured across the same monolayers. Around 30% of baseline and 50% of vasopressin-induced water flow is coupled to an amiloride-sensitive, ENaC-mediated, electrogenic sodium transport, whereas the remaining flow is coupled to an amiloride-insensitive, nonelectrogenic sodium transport mediated by an unknown electroneutral transporter. The mCCD(c11) cell line is a first example of a mammalian tight epithelium allowing quantitative study of the coupling between sodium and water transport. Our data are consistent with the 'near isoosmotic' fluid transport model.

Radio Frequency Identification Tagging as a Mechanism of Creating a Viable Producer’s Brand in the Cattle Industry, May 2005

This manuscript reports on a project to examine the feasibility of extensive radio frequency identification (RFID) tagging to determine product provenance in the meat production industry. The investigators examined existing technologies and meat production processes as well as emerging technologies in RFID tagging to assess the potential of RFID technologies for provenance assurance. While RFID technologies hold tremendous promise for traceability, the current state of the technology and production process creates challenges for effectively creating full traceability. However, RFID holds tremendous potential for improving processing throughput, which will help make RFIDbased traceability more attractive for adoption by meat processors.

Viral transport of DNA damage that mimics a stalled replication fork.

Adeno-associated virus type 2 (AAV2) infection incites cells to arrest with 4N DNA content or die if the p53 pathway is defective. This arrest depends on AAV2 DNA, which is single stranded with inverted terminal repeats that serve as primers during viral DNA replication. Here, we show that AAV2 DNA triggers damage signaling that resembles the response to an aberrant cellular DNA replication fork. UV treatment of AAV2 enhances the G2 arrest by generating intrastrand DNA cross-links which persist in infected cells, disrupting viral DNA replication and maintaining the viral DNA in the single-stranded form. In cells, such DNA accumulates into nuclear foci with a signaling apparatus that involves DNA polymerase delta, ATR, TopBP1, RPA, and the Rad9/Rad1/Hus1 complex but not ATM or NBS1. Focus formation and damage signaling strictly depend on ATR and Chk1 functions. Activation of the Chk1 effector kinase leads to the virus-induced G2 arrest. AAV2 provides a novel way to study the cellular response to abnormal DNA replication without damaging cellular DNA. By using the AAV2 system, we show that in human cells activation of phosphorylation of Chk1 depends on TopBP1 and that it is a prerequisite for the appearance of DNA damage foci.

Phosphate and zinc transport and signalling in plants: toward a better understanding of their homeostasis interaction.

Inorganic phosphate (Pi) and zinc (Zn) are two essential nutrients for plant growth. In soils, these two minerals are either present in low amounts or are poorly available to plants. Consequently, worldwide agriculture has become dependent on external sources of Pi and Zn fertilizers to increase crop yields. However, this strategy is neither economically nor ecologically sustainable in the long term, particularly for Pi, which is a non-renewable resource. To date, research has emphasized the analysis of mineral nutrition considering each nutrient individually, and showed that Pi and Zn homeostasis is highly regulated in a complex process. Interestingly, numerous observations point to an unexpected interconnection between the homeostasis of the two nutrients. Nevertheless, despite their fundamental importance, the molecular bases and biological significance of these interactions remain largely unknown. Such interconnections can account for shortcomings of current agronomic models that typically focus on improving the assimilation of individual elements. Here, current knowledge on the regulation of the transport and signalling of Pi and Zn individually is reviewed, and then insights are provided on the recent progress made towards a better understanding of the Zn-Pi homeostasis interaction in plants.

Transfer of MPEG-2 Transport Stream over MPLS

This study examines how MPEG-2 Transport Stream, used in DVB-T video transmission, can be reliably and efficiently transferred to remote locations over an MPLS network. All the relevant technologies used in this scenario are also discussed in the study. This study was done for Digita Oy, which is a major radio and television content distributor in Finland. The theoretical part of the study begins with the introduction to MPLS technology and continues with explanation of IP Multicast and its components. The fourth section discusses MPEG-2 and the formation and content of MPEG-2 Transport Stream. These technologies were studied in relevant literature and RFC documentation. After the theoretical part of the study, the test setup and the test cases are presented. The results of the test cases, and the conclusions that can be drawn based on them, are discussed in the last section of the study. The tests showed that it is possible to transfer digital video quite reliably over an MPLS network using IP Multicast. By configuring the equipment correctly, the recovery time of the network in case of a failure can be shortened remarkably. Also, the unwanted effect of other traffic on the critical video traffic can be eliminated by defining the Quality of Service parameters correctly. There are, however, some issues that need to be tested further before this setup can be used in broadcast networks. Reliable operation of IP Multicast and proper error correction are the main subjects for future testing.