Mechanistic studies of perfluorooctane sulfonate, perfluorooctanoic acid uptake by maize (Zea mays L. cv. TY2)

Aims

There is a need to predict trace metal concentration in plant organs at given development stages. The aim of this work was to describe the Cd hyperaccumulation kinetics in the different plant organs, throughout the complete cultivation cycle, independently of a possible soil effect.

Methods

Plants of Noccaea caerulescens were exposed in aeroponics to three constantly low Cd concentrations and harvested at 6 to 11 dates, until siliquae formation.

Results

Dry matter allocation between roots and shoots was constant over time and exposure concentrations, as well as Cd allocation. However 86 % of the Cd taken up was allocated to the shoots. Senescent rosette leaves showed similar Cd concentrations to the living ones, suggesting no redistribution from old to young organs. The Cd root influx was proportional to the exposure concentration and constant over time, indicating that plant development had no effect on this. The bio-concentration factor (BCF), i.e. [Cd]_plant/[Cd²⁺]_solution for the whole plant, roots or shoots was independent of the exposure concentration and of the plant stage.

Conclusions

Cadmium uptake in a given plant part could therefore be predicted at any plant stage by multiplying the plant part dry matter by the corresponding BCF and the Cd²⁺ concentration in the exposure solution.     

Intermediate herbivory intensity of an aboveground pest promotes soil labile resources and microbial biomass via modifying rice growth

Background and Aims

The importance of aboveground herbivores for modifying belowground ecosystems has prompted numerous studies; however, studies can be biased by context dependent conditions which lead to extremely inconsistent results. So far, the impacts of herbivory intensity by important rice pests on rice paddy soil ecosystems are lacking. The aim of this study was to test the hypothesis that intermediate herbivory intensity of the brown planthopper (Nilaparvata lugens Stål) could promote soil labile resources and microbial biomass, while high intensity would show a reverse pattern, by mediating rice plant growth. This study will also help the development of integrative pest management.

Methods

Four hopper infestation density treatments (0, 4, 8 and 12 nymphs per rice plant) and two infestation duration treatments (9 and 15 days after N. lugens infestation, DAI 9 and DAI 15) were established in a glasshouse experiment. Soil and plant were sampled destructively from four replicates and analysed for soil labile resources availability, soil microbial biomass and plant performance, respectively.

Results

The infestation density significantly affected both shoot and root mass of rice (P?<?0.05), soil dissolved organic carbon (DOC) and nitrogen (DON), and microbial biomass carbon (MBC) and nitrogen (MBN), and the effects were further enhanced by prolonged infestation duration. Compared to the control (CK) without N. lugens, plant dry mass, DOC, DON, MBC and MBN increased under low (LD) and moderate hopper densities (MD) but decreased under high density (HD) on DAI 9. Moreover, the LD treatment exerted the most promotional effects on DAI 15. Rice root to shoot ratio generally increased in treatments subjected to herbivory. The labile resources and microbial biomass showed close relationships with both shoot and root mass across treatments, in particular with root mass on DAI 15. Such a trend indicated that the shift of photosynthate allocation to belowground contributed to changes of soil resource availability and microbial biomass.

Conclusions

Intermediate herbivory intensity showed positive effects on rice seedling performance and, further, promoted soil labile resource availability and microbial biomass. The importance of extrapolating temporal and spatial scale, i.e. from the short-term greenhouse experiment to an entire rice growing season in the field, was highlighted.     

Later Passages of Neural Progenitor Cells from Neonatal Brain Are More Permissive for Human Cytomegalovirus Infection

Congenital human cytomegalovirus (HCMV) infection is the most frequent infectious cause of birth defects, primarily neurological disorders. Neural progenitor/stem cells (NPCs) are the major cell type in the subventricular zone and are susceptible to HCMV infection. In culture, the differentiation status of NPCs may change with passage, which in turn may alter susceptibility to virus infection. Previously, only early-passage (i.e., prior to passage 9) NPCs were studied and shown to be permissive to HCMV infection. In this study, NPC cultures derived at different gestational ages were evaluated after short (passages 3 to 6) and extended (passages 11 to 20) in vitro passages for biological and virological parameters (i.e., cell morphology, expression of NPC markers and HCMV receptors, viral entry efficiency, viral gene expression, virus-induced cytopathic effect, and release of infectious progeny). These parameters were not significantly influenced by the gestational age of the source tissues. However, extended-passage cultures showed evidence of initiation of differentiation, increased viral entry, and more efficient production of infectious progeny. These results confirm that NPCs are fully permissive for HCMV infection and that extended-passage NPCs initiate differentiation and are more permissive for HCMV infection. Later-passage NPCs being differentiated and more permissive for HCMV infection suggest that HCMV infection in fetal brain may cause more neural cell loss and give rise to severe neurological disabilities with advancing brain development.     

An Inactivated Cell Culture Japanese Encephalitis Vaccine (JE-ADVAX) Formulated with Delta Inulin Adjuvant Provides Robust Heterologous Protection against West Nile Encephalitis via Cross-Protective Memory B Cells and Neutralizing Antibody

West Nile virus (WNV), currently the cause of a serious U.S. epidemic, is a mosquito-borne flavivirus and member of the Japanese encephalitis (JE) serocomplex. There is currently no approved human WNV vaccine, and treatment options remain limited, resulting in significant mortality and morbidity from human infection. Given the availability of approved human JE vaccines, this study asked whether the JE-ADVAX vaccine, which contains an inactivated cell culture JE virus antigen formulated with Advax delta inulin adjuvant, could provide heterologous protection against WNV infection in wild-type and β2-microglobulin-deficient (β2m^−/−) murine models. Mice immunized twice or even once with JE-ADVAX were protected against lethal WNV challenge even when mice had low or absent serum cross-neutralizing WNV titers prior to challenge. Similarly, β2m^−/− mice immunized with JE-ADVAX were protected against lethal WNV challenge in the absence of CD8⁺ T cells and prechallenge WNV antibody titers. Protection against WNV could be adoptively transferred to naive mice by memory B cells from JE-ADVAX-immunized animals. Hence, in addition to increasing serum cross-neutralizing antibody titers, JE-ADVAX induced a memory B-cell population able to provide heterologous protection against WNV challenge. Heterologous protection was reduced when JE vaccine antigen was administered alone without Advax, confirming the importance of the adjuvant to induction of cross-protective immunity. In the absence of an approved human WNV vaccine, JE-ADVAX could provide an alternative approach for control of a major human WNV epidemic.     

Macrophage migration inhibitory factor in mud crab Scylla paramamosain: Molecular cloning, expression profiles in various tissues and under Vibrio challenge

As one of the first found cytokines, macrophage migration inhibitory factor (MIF) plays an important role in several physiological processes in crabs. In this study, a full-length MIF cDNA (GenBank accession number: JX131610) from mud crab Scylla paramamosain (Sp) was cloned based on a sequence of S. paramamosain cDNA library. The full length of SpMIF was 734 bp consisting of a 363 bp open reading frame encoding the SpMIF, a 120 amino acid peptide chain. The molecular weight of SpMIF was 13.46 kDa with the pI of 6.82. The alignment analysis showed that SpMIF appeared to be closely related to the counterpart from Eriocheir sinensis (68%). Quantitative real-time PCR analysis revealed that SpMIF was highly expressed in hepatopancreas and hemocytes. In addition, the expression level of SpMIF was increased significantly after a 6-h challenge by Vibrio parahaemolyticus (4.00 × 10⁶ CFU/mL), peaked at 8 h, and then declined to the common level in 48 h. This data indicated that SpMIF was cloned successfully, and suggested that it participated in the immune system of mud crabs.     

The emission of floral scent from Lilium ‘siberia’ in response to light intensity and temperature

Floral scent is an important part of volatile compounds emitted from plants, and is influenced by many environmental factors. In this study, the floral scent emitted from Lilium ‘siberia’, a common breed of lily, was collected by dynamic headspace at different levels of light intensity (0, 100, 300, 600, 1,000, and 1,500 μmol m^?2 s^?1) and temperature (10, 20, 30, and 40 °C). Using the automated thermal desorption-gas chromatography/mass spectrometry (ATD-GC/MS) technique, the components and release amounts were subsequently identified to investigate the influence of light and temperature on the emission of floral scent. The results revealed that the numbers and release amounts of floral scent components were significantly influenced by light intensity and temperature, showing the similar pattern: first increasing and then decreasing. After light intensity treatment, the maximum numbers and release amounts mainly appeared at 600 and 1,000 μmol m^?2 s^?1. For temperature treatment, 30 °C resulted in the highest numbers and release amounts of the floral scent components. At different levels of light intensity and temperature, terpenoid compounds showed the highest numbers and release amounts among the component categories. α-Ocimene and linalool were the two terpenoid compounds with the highest release amounts, and accounted for the highest proportion. The results obtained provide evidence that both light intensity and temperature trigger the emission of floral scent. The particular response mechanisms must be investigated in future research.     

The comparison of immune-enhancing activity of sulfated polysaccharidses from Tremella and Condonpsis pilosula

Based on our previous research, four sulfated polysaccharide (sPSs) from Tremella and Condonpsis pilosula, sTPS_tp, sTPS_70c, sCPPS_tp and sCPPS_50c, were prepared and their effects on splenic lymphocytes proliferation in vitro and the immune response of ND vaccine in chicken were compared taking the unmodified polysaccharide (uPS) TPS_tp as control. The results showed that four sPSs could significantly or numerically stimulate splenic lymphocyte proliferation singly or synergistically with LPS in vitro, sTPS_70c and sCPPS_tp demonstrated better effect; promote peripheral lymphocytes proliferation and enhance serum HI antibody titer in chickens vaccinated with ND vaccine, the actions of sPSs were stronger than that of uPS, and sTPS_70c at medium dosage presented the best efficacy. These indicated that sulfation modification could improve the immune-enhancing activity of TPS and CPPS, sTPS_70c possessed the strongest activity and would be expected as a component of new-type immunopotentiator.     

Role of Pigment Epithelium-Derived Factor (PEDF) in Arsenic-Induced Cell Apoptosis of Liver and Brain in a Rat Model

Although studies have shown that arsenic exposure can induce apoptosis in a variety of cells, the exact molecular mechanism of chronic arsenicosis remains unclear. Based on our previous study on human serum, the present study was to determine whether pigment epithelium-derived factor (PEDF) plays a role in the damage induced by chronic arsenic exposure in a rat model and to explore the possible signaling pathway involved. Thirty male Wistar rats were randomly divided into three groups and the arsenite doses administered were 0, 10, and 50 mg/L, respectively. The experiment lasted for 6 months. Our results showed that level of arsenic increased significantly in serum, liver, brain, and kidney in arsenic-exposed groups. It was indicated that PEDF protein was widely distributed in the cytoplasm of various types of cells in liver, brain, and kidney. PEDF protein level was only changed when the arsenite dose reached 50 mg/L in liver and brain, whereas it was not changed in the kidney. In order to investigate the possible mechanism of PEDF-exerted damages upon arsenite exposure, apoptosis in liver and brain was assessed. The proportion of apoptotic cells gradually increased with increasing arsenic administration. The ratio of Bax/Bcl-2 in the high arsenic group (50 mg/L) was significantly higher than that in the control group. Therefore, we thought PEDF played a role in cell apoptosis of liver and brain which induced by sodium arsenite exposure, and the results also demonstrated that Bax and Bcl-2 might be two key targets in the action of PEDF.