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Hemicellulose, as a primary component of plant cell walls, constitutes approximately one third of cell wall dry matter and ranks as the second abundant renewable biomass resource in the nature after cellulose. Hemicellulose is tightly cross-linked with cellulose, lignin and other components in the plant cell wall, leading to lignocellulose recalcitrance. However, precise genetic modifications of plant cell walls can significantly improve the saccharification efficiency of lignocellulose while ensuring normal plant growth and development. We comprehensively review the research progress in the structural distribution of hemicellulose in plant cell walls, the cross-linking between hemicellulose and other components of the cell wall, and the impact of hemicellulose modification on the saccharification efficiency of the cell wall, proving a reference for the genetic improvement of energy crops.

PhoPR is an important two-component regulatory system in Mycobacterium tuberculosis. PhoP is essential for virulence as a response regulator involved in cell wall lipid biosynthesis and regulation of gene expression. In this review, the structure, function and vaccine application of PhoP were summarized, as well as some questions that need to be solved.

Members of the genus Microlunatus exhibit many potential advantages in managing the environmental pollution caused by phosphorus. The genus was proposed by Nakamura and co-workers with the name Microlunatus phosphovorus as the type species in 1995. Up to date, the genus Microlunatus encompasses seven validly described species, which were isolated from various environments. Members of the genus Microlunatus share the following genus-specific characteristics, possessing LL-2, 6-diaminopimelic acid in the cell wall peptidoglycan, MK-9(H4) as the predominant menaquinone and diphosphatidylglycerol and phosphatidylglycerol as the phospholipid pattern. Based on the taxonomic results of two newly isolated strains of the genus Microlunatus and the related reference reports, this review summarizes the research advances of the genus Microlunatus, including the genus establishment, taxonomic characteristics, their distribution in the environments, as well as the application prospect in chemical and medical industry.

Objective: To study the role of Snf1/AMPK kinase in cell wall integrity in Saccharomyces cerevisiae JY102., Methods: SNF1 deletion mutant of S. cerevisiae was created by homologous recombination. Congo red and Calcofluor white were applied to evaluate the cell wall integrity for the mutant strain. qRT-PCR was used to analyze the transcription of cell wall-related genes., Results: The SNF1 disruption mutant was severely sensitive to Congo red and Calcofluor white, manifesting the impairment of cell wall integrity. The mutant exhibited apparently growth defect at high temperature. The results of qRT-PCR revealed down-regulated transcription of several genes involved in β-glucan biosynthesis., Conclusion: The deletion of Snf1 impairs the cell wall integrity by reducing the transcription of β-glucan-related genes, suggesting a new role of Snf1 in the activation of cell wall synthesis.

Bioactive gibberellins (GAs) are a type of important plant growth regulators, which play the key roles in multiple processes, such as seed germination, leaf expansion, flowering, fruit bearing, and stem development. Its biosynthesis is regulated by a variety of enzymes including gibberellin 3-oxidase that is a key rate-limiting enzyme. In Arabidopsis, gibberellin 3-oxidase consists of four members, of which AtGA3OX1 and AtGA3OX2 are highly expressed in stems, suggesting the potential roles in the stem development played by the two genes. To date, there are few studies on AtGA3OX1 and AtGA3OX2 regulating secondary wall thickening in stems. In this study, we used the atga3ox1atga3ox2 double mutant as the materials to study the effects of AtGA3OX1 and AtGA3OX2 genes on secondary wall thickening in stems. The results indicated that simulations repression of AtGA3OX1 and AtGA3OX2 genes resulted in significantly reduction of secondary wall thickening of fiber cells, but not that of vessel cells. Three main components (cellulose, hemicelluloses, and lignin) were also dramatically suppressed in the double mutants. qRT-PCR analysis demonstrated that the expressions of secondary wall biosynthetic genes and the associated transcription factors were obviously affected in AtGA3OX1 and AtGA3OX2 double mutant. Therefore, we presume that Arabidopsis AtGA3OX1 and AtGA3OX2 genes might activate the expression of these transcription factors, thus regulate secondary wall thickening in stems. Together, our results provide a theoretical basis for enhancing the lodging resistance of food crops and improving the biomass of energy plants by genetically engineering Arabidopsis AtGA3OX homologs.

Objective: AfMp1p is a glycosylphosphatidylinositol (GPI) anchored cell wall protein (GPI-CWP) identified in filamentous fungus Aspergillus fumigatus, which contains a specific C terminal signal for cell wall localization. Trichoderma reesei is known as a safe fungal species (GRAS) and widely used in the industry. Thus, developing of the cell-surface expression systems in T. reesei is of industrial interest., Methods: The GPI signal from the A. fumigatus AfMp1p was fused to the C-terminal of green fluorescent protein (GFP) and transformed into T. reesei. The optimization of T. reesei transformation and the expression profiles of the GFP were investigated in detail. The cellular location of the GFP fusion protein was detected., Results: Fluorescent image analysis and Western blot analysis indicate that the GFP fusion protein locates on the cell wall of T. reesei., Conclusion: According to these results, the GPI signal from A. fumigatus can be recognized in T. reesei and the expression system constructed in this study can be used to express heterogeneous protein in the cell wall of T. reesei.

Objective: To investigate the effects of the cell wall of Streptococcus mutans on the expression of Toll-like receptor 4 (TLR4), IL-6 and IL-8 in EAhy926 cells (The human endothelial hybridoma of human umbilical vein endothelial cells (HUVEC) and the human epithelial cell line A549, characterized by endothelial phenotype and biology)., Methods: EAhy926 cells were treated with different concentrations of the cell wall of Streptococcus mutans. The proliferation of EAhy926 cells was determined by MTT assay. The mRNA expression of TLR4, IL-6 and IL-8 in EAhy926 cells was detected by reverse transcription polymerase chain reaction (RT-PCR). TLR4 was analyzed by flow cytometry. The production of IL-6 and IL-8 in the cultured supernatants was measured by biochemical method and ELISA respectively. TLR4 blocking assay was used to investigate the relationship between IL-6, IL-8 and TLR4 mRNA expression., Results: The proliferation of EAhy926 cells was significantly enhanced by the cell wall of Streptococcus mutans at 6 h (P<0.05), and inhibited after 12 h (P<0.05), both time- and dose-dependent. The expression of mRNA and protein for TLR4 in EAhy926 cells was increased after stimulated by the cell wall of Streptococcus mutans, peaking at 16 h (P<0.05), and then decreased. The expression of IL-6 and IL-8 mRNA was significantly induced when exposed to the cell wall, reaching the maximal level at 16 h and 24 h, respectively (P<0.05). Meanwhile, the cell wall of Streptococcus mutans induced the production of IL-6 and IL-8 (P<0.05). The expression of IL-6 and IL-8 mRNA in EAhy926 cells was blocked by anti-human TLR4 antibodies significantly., Conclusion: The cell wall of Streptococcus mutans upregulated the expression of TLR4 and induced the production of inflammatory cytokines IL-6 and IL-8, indicating that the expression of TLR4 of EAhy926 cells may elicit a TLR4-mediated innate immune response and contribute to production of inflammatory cytokines IL-6 and IL-8.

Aim: To investigate the effects of rBCG vaccination containing foreign antigen Der p2 in the form of lipoprotein on murine immune response., Methods: 6 to 8 weeks old and newborn BALB/c mice were vaccined intraperitoneally with 10(6) CFU rBCG or BCG. At the same time, the control group was injected with saline. Six weeks later, all animals were injected with Der p2 (20 microg). After two weeks later, the concentrations of IL-4 and IFN-gamma in the serum and splenocyte culture supernatant (STLCS) were determined by ELISA, and Th subgroups were determined by double fluorescent staining and flow cytometry., Results: After vaccination, the serum and STLCS from both rBCG-immunized and BCG-immunized group of adult and newborn BALB/c mice had significantly higher level of IFN-gamma and lower level of IL-4 than those from control groups. Besides, there was the larger percentage of CD4 (+) IFN-gamma (+) cells in spleen from rBCG-vaccined and BCG-vaccined mice than that from control group. However, the percentage of CD4 (+) IL-4 (+) cells in spleen cells from rBCG-vaccined and BCG-vaccined group was lower than that from control group. Moreover, the level of IFN-gamma in STLCS from rBCG-immunized was significantly higher, compared with that from BCG-immunized mice. At the same time, the percentage of CD4 (+) IFN-gamma (+) cells in spleen from rBCG-vaccined mice was larger than that from BCG-vaccined group., Conclusion: Both rBCG and BCG could stimulate Th1 predominant immune response, when injected intraperitoneally into adult or newborn BALB/c mice, The Der p2 expressed on the cell wall of BCG can work as the component of BCG and be recognized by the immune system of mice, therefore stimulates Der p2-specific Th1 predominant immune response. These data indicate that recombinant BCG-expressing antigens can be used as the antigen-specific vaccines against allergic diseases by regulating the balance of Th1/Th2.