Comparative evaluation of irrigation waters on microbiological safety of spinach in field.

AIMS: Effect of ground water (GW), secondary-treated wastewater (STWW) and roof-harvested rainwater (RHW) irrigation on microbiological quality of spinach in field was investigated. METHODS AND RESULTS: Spinach grown at the Fulton farm (Chambersburg, PA) was spray-irrigated with GW, STWW or RHW once a week for 2 weeks in summer and fall seasons. Four replicate spinach and soil samples collected from two plots for each group were analysed for indicator and pathogenic bacteria on 0, 1, 2 and 4 days postirrigation (dpi). While total coliforms remained unchanged on spinach regardless of the treatment waters and growing seasons, populations of faecal coliform significantly decreased on RHW- and STWW-irrigated spinach as compared to spinach irrigated with GW at 4 dpi of each week in fall. Irrigation with STWW that contained Escherichia coli population <1·0 log CFU per 100 ml resulted in the lowest E. coli recovery on spinach in fall. Bacterial pathogens were not detected in any sample. CONCLUSIONS: The transference of indicator micro-organisms from irrigation waters to plants was influenced by the type of water and growing season. SIGNIFICANCE AND IMPACT OF THE STUDY: Alternative water sources such as STWW and RHW containing low indicator bacterial populations may be suitable for spinach irrigation in the mid-Atlantic region. However, microbiological quality of these waters must be determined prior to their use for irrigation.

TRPV5 and TRPV6 are expressed in placenta and bone tissues during pregnancy in mice.

We investigated the dynamic expression of calcium transporters, TRPV5 and TRPV6, in placenta and bone to determine their role in maternal and fetal calcium balance during gestation. In placenta, TRPV5 was expressed predominantly in syncytiotrophoblasts of the labyrinthine zone, whereas TRPV6 was expressed in spongiotrophoblasts of the junction zone. In bone, the two transporters were found in osteoblasts, osteoclasts, cartilage and bone matrices. During the first half of gestation, TRPV5 and TRPV6 levels in bone were increased on pregnancy day (P) 0.5, then decreased on P3.5 followed by a slight increase on P6.5. During the second half of pregnancy, both the proteins and their mRNAs gradually increased from P9.5 to P15.5-P17.5 in both bone and placenta, followed at parturition by relatively high amounts in placenta, but markedly decreased amounts in bone. The expression pattern is likely related to the fetal and maternal calcium requirement during gestation, which may be regulated by estrogen and other hormones, because the fetal demand for calcium is greatest during the last few days of gestation for rats; maternal calcium metabolism is designed to meet the calcium needs of the fetus during this period. We found that TRPV5 and TRPV6 are involved in calcium transport in the placenta and bone, and therefore play a role in calcium homeostasis during embryonic and fetal development.

Microbiological quality of spinach irrigated with reclaimed wastewater and roof-harvest water.

AIMS: The effect of reclaimed wastewater (RCW) and roof-harvest rainwater (RHW) on the microbiological quality of irrigated spinach was investigated. METHODS AND RESULTS: Spinach grown in the controlled environment chamber was irrigated by RCW, RHW or creek water (CW; control water) for 4 weeks, and then six replicate spinach samples from each treatment were collected weekly at 0 h and 24 h postirrigation. Spinach samples were analysed for populations of faecal bacterial indicators and pathogens. Bacterial populations in alternative irrigation water samples were determined by the membrane filtration technique. The RCW samples contained the highest faecal bacterial indicator populations, followed by the CW and RHW throughout the entire study. Irrigation waters containing higher populations of total and faecal coliforms did not necessarily result in higher populations of these bacteria on the irrigated spinach. Higher numbers of E. coli-positive spinach samples were reported from RCW-irrigated spinach, especially with repeated irrigation. Pathogens were not detected from any water or spinach samples. CONCLUSIONS: Spinach irrigated with RHW did not significantly affect the populations of faecal indicator bacteria when compared with CW-irrigated spinach. Repeat irrigation with RCW is not recommended due to the increased contamination of E. coli on spinach leaves. SIGNIFICANCE AND IMPACT OF THE STUDY: RHW may potentially be used as alternative irrigation water without deleteriously affecting the microbiological safety of the spinach.

Inactivation of Salmonella enteritidis on shell eggs by coating with phytochemicals.

Salmonella enteritidis (SE) is a major foodborne pathogen that causes human infections largely by consumption of contaminated eggs. The external surface of eggs becomes contaminated with SE from multiple sources, highlighting the need for effective egg surface disinfection methods. This study investigated the efficacy of three GRAS-status, phytochemicals, namely carvacrol (CR), eugenol (EG), and ß-resorcylic acid (BR) applied as pectin or gum arabic based coating for reducing SE on shell eggs. White-shelled eggs, spot inoculated with a 5-strain mixture of nalidixic acid (NA) resistant SE (8.0 log CFU/mL) were coated with pectin or gum arabic solution containing each phytochemical (0.0, 0.25, 0.5, or 0.75%), and stored at 4°C for 7 days. SE on eggs was enumerated on days 0, 1, 3, and 7 of storage. Approximately 4.0 log CFU/egg of SE was recovered from inoculated and pectin or gum arabic coated eggs on day 0. All coating treatments containing CR and EG, and BR at 0.75% reduced SE to undetectable levels on day 3 (P < 0.05). Results suggest that the aforementioned phytochemicals could effectively be used as a coating to reduce SE on shell eggs, but detailed studies on the sensory and quality attributes of coated eggs need to be conducted before recommending their use.

Polyelectrolyte multilayers generated in a microfluidic device with pH gradients direct adhesion and movement of cells.

In this study, multilayers from polyethylene imine, heparin and chitosan are prepared at three different pH values of 5, 7 and 9. Water contact angle and quartz microbalance measurements show that resulting multilayers differ in terms of wetting behaviour, layer mass and mechanical properties. The multilayer is then formed within a gradient generation microfluidic (µFL) device. Polyethylene imine or heparin solutions of pH 5 are introduced into one inlet and the same solutions but at pH 9 into another inlet of the µFL device. The pH gradient established during the multilayer formation can be visualized inside the microchamber by pH sensitive fluorophores and confocal laser scanning microscopy. From this setup it is expected that properties of multilayers displayed at distinct pH values can be realised in a gradient manner inside the µFL device. Behaviour of the osteoblast cell line MG-63 seeded and cultured on top of multilayers created inside the µFL device support this hypothesis. It is observed that more cells adhere and spread on multilayers build-up at the basic side of the µFL channel, while those cells on top of multilayers built at pH 5 are fewer and smaller. These results are consistent with the behaviour of MG-63 cells seeded on multilayers formed at discrete pH values. It is particularly interesting to see that cells start to migrate from multilayers built at pH 5 to those built at pH 9 during 6 h of culture. Overall, the presented multilayer formation setup applying pH gradients leads to surfaces that promote migration of cells.

Acid volatile sulfides and simultaneously extracted metals in a metal-polluted area of Taihu Lake, China.

There were similar distribution characteristics for acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) in surface sediments, and the concentrations of AVS and SEM decreased from the deposition area to the center of the bay (lake). The ratio of AVS to SEM was <1 in the surface sediments, indicating that heavy metals in surface sediments may be bioavailable. The concentration of AVS increased with sediment depth, followed by a decrease with large variation, while the concentration of SEM remained constant. By comparing the concentration of SEM with total metals, it was shown that extracted Cu and Ni decreased with sediment depth, indicating increasing association of Cu and Ni with sulfides in deeper sediment layers. The lower extracted ratios for Pb and Zn compared with sulfidic sediment illustrated that AVS should not have strong control on sediment Pb and Zn. The molar ratio of AVS and reactive iron showed that heavy metals were dynamic and active in sediments in this lake.

Submicron patterning of DNA oligonucleotides on silicon.

The covalent attachment of DNA oligonucleotides onto crystalline silicon (100) surfaces, in patterns with submicron features, in a straightforward, two-step process is presented. UV light exposure of a hydrogen-terminated silicon (100) surface coated with alkenes functionalized with N-hydroxysuccinimide ester groups resulted in the covalent attachment of the alkene as a monolayer on the surface. Submicron-scale patterning of surfaces was achieved by illumination with an interference pattern obtained by the transmission of 248 nm excimer laser light through a phase mask. The N-hydroxysuccinimide ester surface acted as a template for the subsequent covalent attachment of aminohexyl-modified DNA oligonucleotides. Oligonucleotide patterns, with feature sizes of 500 nm, were reliably produced over large areas. The patterned surfaces were characterized with atomic force microscopy, scanning electron microscopy, epifluorescence microscopy and ellipsometry. Complementary oligonucleotides were hybridized to the surface-attached oligonucleotides with a density of 7 x 10(12) DNA oligonucleotides per square centimetre. The method will offer much potential for the creation of nano- and micro-scale DNA biosensor devices in silicon.

Cartorimine, a new cycloheptenone oxide derivative from Carthamus tinctorius.

Cartorimine (1), a new cycloheptenone oxide derivative, was isolated from Carthamus tinctorius, and its structure was established from spectral data interpretation and single-crystal X-ray analysis.