Regulation of tight junction assembly and epithelial morphogenesis by the heat shock protein Apg-2

Background: Tight junctions are required for epithelial barrier formation and participate in the regulation of signalling mechanisms that control proliferation and differentiation. ZO-1 is a tight junction-associated adaptor protein that regulates gene expression, junction assembly and epithelial morphogenesis. We have previously demonstrated that the heat shock protein Apg-2 binds ZO-1 and thereby regulates its role in cell proliferation. Here, we addressed the question whether Apg-2 is also important for junction formation and epithelial morphogenesis.Results: We demonstrate that depletion of Apg-2 by RNAi in MDCK cells did not prevent formation of functional tight junctions. Similar to ZO-1, however, reduced expression of Apg-2 retarded de novo junction assembly if analysed in a Ca-switch model. Formation of functional junctions, as monitored by measuring transepithelial electrical resistance, and recruitment of tight and adherens junction markers were retarded. If cultured in three dimensional extracellular matrix gels, Apg-2 depleted cells, as previously shown for ZO-1 depleted cells, did not form hollow polarised cysts but poorly organised, irregular structures.Conclusion: Our data indicate that Apg-2 regulates junction assembly and is required for normal epithelial morphogenesis in a three-dimensional culture system, suggesting that Apg-2 is an important regulator of epithelial differentiation. As the observed phenotypes are similar to those previously described for ZO-1 depleted cells and depletion of Apg-2 retards junctional recruitment of ZO-1, regulation of ZO-1 is likely to be an important functional role for Apg-2 during epithelial differentiation

Effects of Cu and Zn Coated Urea on Eh, pH and Solubility of Cu and Zn in Rice Soils

The concentration of Cu (Copper) and Zn (Zinc) decreases upon flooded conditions of rice soil. To assess the effects of flooding and application of Cu and Zn coated urea on changes in Eh, pH and solubility of Cu and Zn, a glasshouse experiment was conducted at Universiti Putra Malaysia. Rice plants (30 days old seedlings of type MR-219) on two soils (riverine and alluvium and marine alluvium) were transplanted. Nine treatments with variable rates and combinations of Cu and Zn coated urea were applied. The sources of fertilizers were copper sulfate and zinc sulfate. Eh values decreased with flooding time in both soils. The changes of Eh values were more negative in control treatments and stabilized after 3 weeks of submergence. The Eh variation was not observed affectively in the treated soils however, soil pH increased with flooding time. During the 3rd week of submergence, pH was neutral (pH 7.0). In both soils, Cu and Zn treated soil showed lower Eh and higher pH values as compared to untreated soil. Concentration of Cu and Zn in soil solution decreased with flooding. The higher Cu and Zn contents in soil were recorded in treated soils. Reduced solubility of Cu and Zn in control soils was related to larger changes in Eh and pH values. Mean comparison with Tukey’s HSD (Honest Significant Difference) test showed that Cu and Zn solubility decreased with decreased Eh and increased pH in the soil solution (p < 0.05%)

Developmental expression profile of the optic atrophy gene product: OPA1 is not localized exclusively in the mammalian retinal ganglion cell layer

PURPOSE: Autosomal dominant optic atrophy (ADOA) is characterized by primary degeneration of retinal ganglion cells and atrophy of the optic nerve. The OPA1 gene encodes a 960-amino-acid protein. In the current study the temporal and spatial localization of OPA1 were examined in developing and adult murine ocular tissues and the adult human eye. Because the Bst/+ mouse has been postulated as a model of ADOA, the mOPA1 expression in the Bst/+ retina was also examined. METHODS: A polyclonal antibody generated against a C-terminal peptide of OPA1 was used to assess by immunohistochemistry the expression of mOPA1 in the wild-type embryonic and postnatal mouse ocular tissues and the Bst/+ retina. Western blot analyses of total proteins from a panel of adult human tissues were used to examine the expression of human OPA1, and spatial localization was assessed by immunohistochemistry. RESULTS: The ocular expression of mOPA1 begins at E15 in the inner retina in a location corresponding to that of the subsequently developing ganglion cell layer (GCL) and peaks between postnatal day (P)0 and P1 in the retina and the optic nerve. There is a sharp decline in mOPA1 expression after P2, but it is expressed at a basal level until at least P12 in the GCL, inner plexiform layer (IPL), and inner nuclear layer (INL) of the retina as well as in the optic nerve. In the adult Bst/+ retina, mOPA1 is strongly expressed in the GCL and IPL and weakly in the INL. In the adult human eye, OPA1 is expressed in the GCL, IPL, INL, and outer plexiform layer (OPL) of the retina and in the optic nerve, where it is observed only in the myelinated region. CONCLUSIONS: OPA1 is not restricted to the GCL of the mammalian retina, and its expression extends into the IPL, INL, and OPL. OPA1 is distinctly expressed in the myelinated region beyond the lamina cribrosa in the human optic nerve, whereas its expression is weaker in the mouse optic nerve. In the Bst/+ mouse retina, despite the structural defects, mOPA1 expression is comparable to that observed in the wild-type adult mouse retina. These observations suggest a wider role for OPA1 than previously anticipated

Consequences of Cu and Zn coated urea to minimize ammonia volatilization

Nitrogen (N) losses from agricultural fields are commonly observed particularly from urea. The rate of urea hydrolysis is accelerated as it remains in conventional form and about 70% of applied urea losses in different forms to atmosphere. Ammonia volatilization is persuasive loss among all the losses from urea. Therefore to minimize ammonia (NH3) volatilization the micronutrient coated urea is applied to enhance N-efficiency and its uptake. This study is an application of micronutrient coated urea with zinc (Zn) and copper (Cu) for two soil series of Malaysia. A laboratory experiment was designed according to the force draft technique for trapping the NH3 loss. The results have manifested that the rate of ammonia volatilization was 16% from uncoated urea and 8% from coated urea with micronutrients during the first two weeks of observations. After the six weeks of observations it was perceived that the ammonia losses for both soil series were gradually decreased with time. The mean comparison by using Tukey’s range test has shown the positive effect of micronutrient coated urea in comparison with the conventional urea. However the urea coated with the combination of both micronutrients Cu and Zn has shown significant difference in contrast to the coating urea with single micronutrient. The overall results revealed the efficacy of micronutrient coated urea on both of the soil series to maximize N-uptake and reduce NH3 volatilization

Enteropathogenic E. coli: breaking the intestinal tight junction barrier [version 2; referees: 2 approved]

Enteropathogenic E. coli (EPEC) causes acute intestinal infections in infants in the developing world. Infection typically spreads through contaminated food and water and leads to severe, watery diarrhea. EPEC attaches to the intestinal epithelial cells and directly injects virulence factors which modulate multiple signaling pathways leading to host cell dysfunction. However, the molecular mechanisms that regulate the onset of diarrhea are poorly defined. A major target of EPEC is the host cell tight junction complex which acts as a barrier and regulates the passage of water and solutes through the paracellular space. In this review, we focus on the EPEC effectors that target the epithelial barrier, alter its functions and contribute to leakage through the tight junctions

Hydrodynamics of Port Phillip Heads

The Port of Melbourne Corporation is examining a proposal to deepen the shipping channels into the Port of Melbourne. This includes some deepening in Port Phillip Heads, the area known as The Rip. As part of the investigations for this project, measurements and modelling of the hydrodynamics of the heads has been undertaken. The Heads includes shallow banks with water depths of about 20 m intersected by a canyon with depths close to 100 m and near vertical walls. The result is an area of currents in excess of 3.5 m s-1, with complex flow patterns. It is shown to be the major control for water movements in and out of the bay. Measurements indicate strong and persistent eddies and large gradients in the sea-surface elevation as well as very strong vertical variations in the currents. The eddies are believed to play an important role in the exchange of water from Bass Strait with that in the bay. The major features are well reproduced by models with both two and three-dimensional modelling being used

Prediction of plume generation and movement from dredging operations in Port Phillip Bay, Melbourne

This paper describes the calibration, validation and application of numerical models to assess the spreading, dispersion and settling of the material put into suspension by dredging operations in Port Phillip Bay. The models were set-up and validated using the field data collected during a trial dredging program specifically undertaken as part of investigations for the Supplementary Environment Effects Statement. A brief discussion of the trial and some of the data collected is included. A range of dredging scenarios consisting of varying wind and tide conditions and different dredging configurations were simulated. The full dredging program, spanning about two years, was modelled and, in addition, more than one operational scenario was considered so that a very large modelling effort was undertaken. The results show that the plumes in the south of Port Phillip Bay are driven primarily by the strong tidal-currents and can travel relatively large distances with varying levels of turbidity. In the north of the Bay, the tidal flows are much less and the turbid plumes do not travel large distances from the area of dredging operations. The time-series of turbidity at ecologically sensitive locations in combination with statistical patterns derived for the entire model area provide an estimation of both spatial and temporal variation of turbidity

Coastal hazard assessment and adaptation to climate change at Portland, Victoria

This paper describes an engineering evaluation of risks and costs of current and future climate change impacts as a result of on-going and future erosion along the Portland coast. Numerical modelling has been employed to determine the wave climate, sediment transport, erosion and inundation due to extreme storm events. A reliable set of wave parameters that accurately describe the inshore wave conditions at Portland have been prepared for input into the wave and morphological models. The modelling results have been used to determine the coastal hazard lines for the current climate and due to sea level rise in the future for 2030, 2070 and 2100. These will assist the Glenelg Shire in the implementation of their local planning scheme. A broad range of adaptation options (structural and non-structural) have been developed to enable management or minimisation of threats to the coastal assets and infrastructure

Wave modulation by tidal currents near Cook Strait

Wave-current interactions are studied through the WAve and current MOnitoring System (WAMOS II) based on an HR Radar, installed at Makara, near Cook Strait (NZ). At Makara, the tidal regime generates currents up to 2.5 m/s parallel to the coastal line. Waves propagate through the strait mainly from the S quadrant. We observed that the waves are strongly modulated by the tidal currents and undertake a clear refraction pattern. The refraction is further explained and discussed exclusively through the geometrical optics. The modulation is also seen for significant wave height, absolute peak period and peak wavelength. When waves approach shallow regions they become steeper and eventually break. In these circumstances the currents are in turn modulated by the waves and WAMOS reveals a localised strong current jet. A wave model which fully represents the wave action balance equation (SWAN model) was also implemented. The mean WAMOS wave spectrum was applied as a constant boundary condition and propagated over the varying current field. The wave parameter modulations are well represented by the model. It is concluded that the current field is effectively inhomogeneous, and because of this generates wave height and wavelength modulations, and unsteady, which fact is responsible for absolute peak period oscillations. Therefore currents are an important factor to be considered when modelling waves near Cook Strait

Opening and closure of a marginal southern California lagoon inlet

Over the past 50 yr, direct observations of the inlet status (open or closed) of San Diegulto Lagoon, a typical southern California lagoon located in Del Mar, California, have shown that river flooding is the major natural determinant of inlet conditions on time scales longer than a few years. River flooding is strongly dependent on rainfall in the San Diegulto River watershed and on the influences of two water storage reservoirs in the area. Rainfall fluctuates on yearly and longer time scales and undergoes cycles of wet and dry periods. Over short time periods, ranging from a few months to several years, inlet status is primarily determined by the available tidal prism and littoral sand transport. Recognition of these factors is crucial in order to correctly evaluate the probability that a small lagoon will remain open naturally. A probability approach is essential because the variables controlling inlet conditions are random in nature. The results of our study show that the inlet will remain open naturally 34% of the time. The tendency to remain open is vastly smaller during years of dry weather (12%) versus times of above-average rainfall (66%)