Converting paddy fields to Lei bamboo (Phyllostachys praecox) stands affected soil nutrient concentrations, labile organic carbon pools, and organic carbon chemical compositions

Background and aims

Land-use change often markedly alters soil carbon (C) and nitrogen (N) pool sizes with implications for climate change and soil sustainability. The objective of this research was to study the effect of converting paddy fields to Lei bamboo (Phyllostachys praecox) stands on soil C and N and other nutrient pools as well as the chemical structure of soil organic C (SOC) in the soil profile.

Methods

Soils (Anthrosols) from four adjacent paddy field–bamboo forest pairs with a known land-use history were sampled from Lin’an County, Zhejiang Province. Soil water soluble organic C (WSOC), hot water soluble organic C (HWSOC), microbial biomass C (MBC), readily oxidizable C (ROC), water soluble organic N (WSON), and other soil chemical and physical properties were determined. Soil organic C functional group compositions were determined by ¹³C-nuclear magnetic resonance (NMR).

Results

Concentrations of soil available P, available K, and different N forms increased (P?<?0.05) by the land-use conversion. Higher concentrations of SOC and total N (TN) were observed in the subsoil (20–40 and 40–60 cm soil layers) but not in the topsoil (0–20 cm layer) in the bamboo stands than in the paddy fields. The storage of SOC and TN in the entire soil profile (0–60 cm) increased by 56.7 and 70.7 %, respectively, after the land-use change. The increases in the SOC stock of the three soil layers were 11.0, 14.3, and 9.5 Mg C ha^?1, respectively. The conversion decreased WSOC concentrations in the subsoil but increased the ROC concentration in the topsoil. Solid-state NMR spectroscopy of soil samples showed that the conversion increased (P?<?0.05) the O-alkyl C content while decreased the aromatic C content, alkyl C to O-alkyl C ratio (A/O-A), and aromaticity of SOC.

Conclusions

Conversion of paddy fields to bamboo stands increased soil nutrient availability, and SOC and TN stocks. Effects of land-use change on C pools and C chemistry of SOC varied among different soil layers in the profile. The impact of the land-use conversion on soil organic C pools was not restricted to the topsoil, but changes in the subsoil were equally large and should be accounted for.     

Protoplasts: a useful research system for plant cell biology, especially dedifferentiation

As protoplasts have the characteristics of no cell walls, rapid population growth, and synchronicity, they are useful tools for research in many fields, especially cellular biology (Table 1). This article is an overview that focuses on the application of protoplasts to investigate the mechanisms of dedifferentiation, including changes in hormone signals, epigenetic changes, and organelle distribution during the dedifferentiation process. The article also emphasizes the wide range of uses for protoplasts in studying protein positions and signaling during different stresses. The examples provided help to show that protoplast systems, for example the mesophyll protoplast system of Arabidopsis, represent promising tools for studying developmental biology. Meanwhile, specific analysis of protoplast, which comes from different tissue, has specific advantages and limitations (Table 2), and it can provide recommendations to use this system.     

Role of Cell-Type-Specific Endoplasmic Reticulum-Associated Degradation in Polyomavirus Trafficking

BK polyomavirus (BKPyV) is a widespread human pathogen that establishes a lifelong persistent infection and can cause severe disease in immunosuppressed patients. BKPyV is a nonenveloped DNA virus that must traffic through the endoplasmic reticulum (ER) for productive infection to occur; however, it is unknown how BKPyV exits the ER before nuclear entry. In this study, we elucidated the role of the ER-associated degradation (ERAD) pathway during BKPyV intracellular trafficking in renal proximal tubule epithelial (RPTE) cells, a natural host cell. Using proteasome and ERAD inhibitors, we showed that ERAD is required for productive entry. Altered trafficking and accumulation of uncoated viral intermediates were detected by fluorescence in situ hybridization and indirect immunofluorescence in the presence of an inhibitor. Additionally, we detected a change in localization of partially uncoated virus within the ER during proteasome inhibition, from a BiP-rich area to a calnexin-rich subregion, indicating that BKPyV accumulated in an ER subcompartment. Furthermore, inhibiting ERAD did not prevent entry of capsid protein VP1 into the cytosol from the ER. By comparing the cytosolic entry of the related polyomavirus simian virus 40 (SV40), we found that dependence on the ERAD pathway for cytosolic entry varied between the polyomaviruses and between different cell types, namely, immortalized CV-1 cells and primary RPTE cells.     

Polyomavirus Large T Antigen Binds Symmetrical Repeats at the Viral Origin in an Asymmetrical Manner

Polyomaviruses have repeating sequences at their origins of replication that bind the origin-binding domain of virus-encoded large T antigen. In murine polyomavirus, the central region of the origin contains four copies (P1 to P4) of the sequence G(A/G)GGC. They are arranged as a pair of inverted repeats with a 2-bp overlap between the repeats at the center. In contrast to simian virus 40 (SV40), where the repeats are nonoverlapping and all four repeats can be simultaneously occupied, the crystal structure of the four central murine polyomavirus sequence repeats in complex with the polyomavirus origin-binding domain reveals that only three of the four repeats (P1, P2, and P4) are occupied. Isothermal titration calorimetry confirms that the stoichiometry is the same in solution as in the crystal structure. Consistent with these results, mutation of the third repeat has little effect on DNA replication in vivo. Thus, the apparent 2-fold symmetry within the DNA repeats is not carried over to the protein-DNA complex. Flanking sequences, such as the AT-rich region, are known to be important for DNA replication. When the orientation of the central region was reversed with respect to these flanking regions, the origin was still able to replicate and the P3 sequence (now located at the P2 position with respect to the flanking regions) was again dispensable. This highlights the critical importance of the precise sequence of the region containing the pentamers in replication.     

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.     

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.     

Effects of cytokinin on photosynthetic gas exchange, chlorophyll fluorescence parameters, antioxidative system and carbohydrate accumulation in cucumber (Cucumis sativus L.) under low light

The effects of 6-benzylaminopurine (6-BA) on plant growth, net photosynthetic rate, relative chlorophyll content, soluble protein, carbohydrates contents and antioxidant systems of cucumber (Cucumis sativus L.) under low-light environment were investigated using two different cucumber cultivars. The results showed that the weak light resulted in the remarkable decrease in plant net photosynthetic rate, relative chlorophyll content, soluble protein and carbohydrates contents, but promoted the superoxide dismutase and guaiacol peroxidase activities. However, application of 6-BA alleviated the reduction of the correlative parameters and mediated the changes of antioxidant systems. The potential mechanisms may involve the following aspects: 6-BA clearly enhanced the plants’ tolerance to low light by increasing chlorophyll content, reducing the production of superoxide radical (O ₂ ^·? ), and enhancing the quenching of hydrogen peroxide (H₂O₂), consequently alleviating the injury of photosynthetic system, and further increasing the efficiency of CO₂ assimilation, producing more carbohydrates which can meet the growth need of cucumber. Meanwhile, the present study indicated that cucumber of Europe mini type (Chunqiuwang) was more tolerant to low light than HuaNan type (Huza No.3).