The achene mucilage hydrated in desert dew assists seed cells in maintaining DNA integrity: adaptive strategy of desert plant Artemisia sphaerocephala

Despite proposed ecological importance of mucilage in seed dispersal, germination and seedling establishment, little is known about the role of mucilage in seed pre-germination processes. Here we investigated the role of mucilage in assisting achene cells to repair DNA damage during dew deposition in the desert. Artemisia sphaerocephala achenes were first treated γ-irradiation to induce DNA damage, and then they were repaired in situ in the desert dew. Dew deposition duration can be as long as 421 min in early mornings. Intact achenes absorbed more water than demucilaged achenes during dew deposition and also carried water for longer time following sunrise. After 4-d dew treatment, DNA damage of irradiated intact and demucilaged achenes was reduced to 24.38% and 46.84%, respectively. The irradiated intact achenes exhibited much higher DNA repair ratio than irradiated demucilaged achenes. Irradiated intact achenes showed an improved germination and decreased nonviable achenes after dew treatment, and significant differences in viability between the two types of achenes were detected after 1020 min of dew treatment. Achene mucilage presumably plays an ecologically important role in the life cycle of A. sphaerocephala by aiding DNA repair of achene cells in genomic-stressful habitats.     

GM-CSF and IL-2 as adjuvant enhance the immune effect of protein vaccine against foot-and-mouth disease

Background

The West Nile virus (WNV) capsid (C) protein is one of the three viral structural proteins, encapsidates the viral RNA to form the nucleocapsid, and is necessary for nuclear and nucleolar localization. The antigenic sites on C protein that are targeted by humoral immune responses have not been studied thoroughly, and well-defined B-cell epitopes on the WNV C protein have not been reported.

Results

In this study, we generated a WNV C protein-specific monoclonal antibody (mAb) and defined the linear epitope recognized by the mAb by screening a 12-mer peptide library using phage-display technology. The mAb, designated as 6D3, recognized the phages displaying a consensus motif consisting of the amino acid sequence KKPGGPG, which is identical to an amino acid sequence present in WNV C protein. Further fine mapping was conducted using truncated peptides expressed as MBP-fusion proteins. We found that the KKPGGPG motif is the minimal determinant of the linear epitope recognized by the mAb 6D3. Western blot (WB) analysis demonstrated that the KKPGGPG epitope could be recognized by antibodies contained in WNV- and Japanese encephalitis virus (JEV)-positive equine serum, but was not recognized by Dengue virus 1-4 (DENV1-4)-positive mice serum. Furthermore, we found that the epitope recognized by 6D3 is highly conserved among the JEV serocomplex of the Family Flaviviridae.

Conclusion

The KKPGGPG epitope is a JEV serocomplex-specific linear B-cell epitope recognized by the 6D3 mAb generated in this study. The 6D3 mAb may serve as a novel reagent in development of diagnostic tests for JEV serocomplex infection. Further, the identification of the B-cell epitope that is highly conserved among the JEV serocomplex may support the rationale design of vaccines against viruses of the JEV serocomplex.     

Engineering microbes to sense and eradicate Pseudomonas aeruginosa,a human pathogen

Synthetic biology aims to systematically design and construct novel biological systems that address energy, environment, and health issues. Herein, we describe the development of a synthetic genetic system, which comprises quorum sensing, killing, and lysing devices, that enables Escherichia coli to sense and kill a pathogenic Pseudomonas aeruginosa strain through the production and release of pyocin. The sensing, killing, and lysing devices were characterized to elucidate their detection, antimicrobial and pyocin release functionalities, which subsequently aided in the construction of the final system and the verification of its designed behavior. We demonstrated that our engineered E. coli sensed and killed planktonic P. aeruginosa, evidenced by 99% reduction in the viable cells. Moreover, we showed that our engineered E. coli inhibited the formation of P. aeruginosa biofilm by close to 90%, leading to much sparser and thinner biofilm matrices. These results suggest that E. coli carrying our synthetic genetic system may provide a novel synthetic biology‐driven antimicrobial strategy that could potentially be applied to fighting P. aeruginosa and other infectious pathogens.     

Understanding lignin-degrading reactions of ligninolytic enzymes: binding affinity and interactional profile

Previous works have demonstrated that ligninolytic enzymes mediated effective degradation of lignin wastes. The degrading ability greatly relied on the interactions of ligninolytic enzymes with lignin. Ligninolytic enzymes mainly contain laccase (Lac), lignin peroxidase (LiP) and manganese peroxidase (MnP). In the present study, the binding modes of lignin to Lac, LiP and MnP were systematically determined, respectively. Robustness of these modes was further verified by molecular dynamics (MD) simulations. Residues GLU460, PRO346 and SER113 in Lac, residues ARG43, ALA180 and ASP183 in LiP and residues ARG42, HIS173 and ARG177 in MnP were most crucial in binding of lignin, respectively. Interactional analyses showed hydrophobic contacts were most abundant, playing an important role in the determination of substrate specificity. This information is an important contribution to the details of enzyme-catalyzed reactions in the process of lignin biodegradation, which can be used as references for designing enzyme mutants with a better lignin-degrading activity.     

Stage-specific expression of dynein light chain-1 and its interacting kinase, p21-activated kinase-1, in rodent testes: implications in spermiogenesis.

Mammalian spermatogenesis is a complex process involving regulatory interactions of many gene products. In this study, we found that dynein light chain-1 (DLC1), a component of the dynein motor complex, is highly expressed in mouse and rat testes. Immunohistochemically detectable levels of DLC1 are observed specifically in spermatids in steps 9-16 in distinct subcellular compartments: in steps 9-11, DLC1 is predominantly localized in the nucleus; in steps 12 and 13, it is found in both nucleus and cytoplasm; and in step 14-16, it is present exclusively in the cytoplasm. In addition, we found p21-activated kinase 1 (Pak1), a protein kinase that activates DLC1 by phosphorylating DLC1 at Serine 88, was also expressed during these stages of spermatogenesis. Pak1 was also expressed in Leydig cells, in preleptotene primary spermatocytes, and in round spermatids. The spermiogenic stage-specific expression of DLC1 suggests a role for DLC1 in chromatin condensation, spermatid shaping, and the final release of sperm from the spermatogenic epithelium. Further, Pak1 may also play a role in spermiogenesis by regulating DLC1 phosphorylation and, consequently, its function.     

Finding cancer biomarkers from mass spectrometry data by decision lists.

Finding accurate biomarkers is key to early diagnosis and successful treatment of many otherwise incurable diseases. In this work, we study the problem of finding biomarkers through mass spectrometry (SELDI-TOF) spectra from cancerous and normal tissues. In contrast to the common practice of using vague methods such as genetic algorithms, or uninterpretable methods such as Support Vector Machines, we look for a method that is simple, intuitive, interpretable, usable, and more accurate. We introduce decision lists to this domain. Our experiments on clinical cancer datasets demonstrate that decision lists can achieve more accurate results than other methods. More interestingly, the resulting decision lists are more interpretable for possible causal relationship between cancer and differentially expressed proteins, and directly usable in clinical biomarker design. In particular, our approach is capable of finding multiple biomarkers with high sensitivity and specificity. Such a feature will provide clues for medical experts to thoroughly investigate the roles of protein in cancer development and progression.     

Virulizin, a novel immunotherapy agent, activates NK cells through induction of IL-12 expression in macrophages

Virulizin, a novel biological response modifier, has demonstrated significant antitumor efficacy in a variety of human tumor xenograft models including melanoma, pancreatic cancer, breast cancer, ovarian cancer and prostate cancer. The significant role of macrophages and NK (Natural killer) cells was implicated in the antitumor mechanism of Virulizin where expansion as well as increased activity of macrophages and NK cells were observed in mice treated with Virulizin. Depletion of macrophages compromised Virulizin-induced NK1.1⁺ cell infiltration into xenografted tumors and was accompanied by reduced antitumor efficacy. In the present study, involvement of macrophages in NK cell activation was investigated further. We found that depletion of NK cells in CD-1 nude mice by anti-ASGM1 antibody significantly compromised the antitumor activity of Virulizin. Cytotoxicity of NK cells isolated from Virulizin-treated mice was enhanced against NK-sensitive YAC-1 cells and C8161 human melanoma cells, but not against NK-insensitive P815 cells. An increased level of IL-12 was observed in the serum of mice treated with Virulizin. IL-12 mRNA and protein levels were also increased in peritoneal macrophages isolated from Virulizin-treated mice. Moreover, Virulizin-induced cytotoxic activity of NK cells isolated from the spleen was abolished when an IL-12 neutralizing antibody was co-administered. In addition, depletion of macrophages in mice significantly impaired Virulizin-induced NK cell cytotoxicty. Taken together, the results suggest that Virulizin induces macrophage IL-12 production, which in turn stimulates NK cell-mediated antitumor activity.     

Genetic consequence of restricted habitat and population decline in endangered Isoetes sinensis (Isoetaceae)

BACKGROUND AND AIMS: Isoetes sinensis (Isoeteaceae) is a critically endangered aquatic quillwort in eastern China. Rapid decline of extant population size and local population extinction have occurred in recent years and have raised great concerns among conservationists. METHODS: Amplified fragment length polymorphisms (AFLPs) were used to investigate the genetic variation and population structure of seven extant populations of the species. KEY RESULTS: Eight primer combinations produced a total of 343 unambiguous bands of which 210 (61.2 %) were polymorphic. Isoetes sinensis exhibited a high level of intra-population genetic diversity (H(E) = 0.118; hs = 0.147; I = 0.192; P = 35.2 %). The genetic variation within each of the populations was not positively correlated with their size, suggesting recent population decline, which is well in accordance with field data of demographic surveys. Moreover, a high degree of genetic differentiation (F(ST) = 0.535; G(ST) = 0.608; theta(B) = 0.607) was detected among populations and no correlation was found between geographical and genetic distance, suggesting that populations were in disequilibrium of migration-drift. Genetic drift played a more important role than gene flow in the current population genetic structure of I. sinensis because migration of I. sinensis is predominantly water-mediated and habitat range was highly influenced by environment changes. CONCLUSIONS: Genetic information obtained in the present study provides useful baseline data for formulating conservation strategies. Conservation management, including both reinforcement for in situ populations and ex situ conservation programmes should be carefully designed to avoid the potential risk of outbreeding depression by admixture of individuals from different regions. However, translocation within the same regional population should be considered as a measure of genetic enhancement to rehabilitate local populations. An ex situ conservation strategy for conserving all extant populations to maximize genomic representation of the species is also recommended.     

Pentoxifylline attenuates cardiac dysfunction and reduces TNF-alpha level in ischemic-reperfused heart

Although pentoxifylline (PTXF), a phosphodiesterase inhibitor, has been reported to exert beneficial effects in cardiac bypass surgery, its effect and mechanisms against ischemia-reperfusion (I/R) injury in heart are poorly understood. Because I/R is known to increase the level of tumor necrosis factor (TNF)-alpha in myocardium and PTXF has been shown to depress the production of TNF-alpha in failing heart, this study examined the hypothesis that PTXF may attenuate cardiac dysfunction and reduce TNF-alpha content in I/R heart. For this purpose, isolated rat hearts were subjected to global ischemia for 30 min followed by reperfusion for 2-30 min. Although cardiac dysfunction due to ischemia was not affected, the recovery of heart function upon reperfusion was markedly improved by PTXF treatment. This cardioprotective effect of PTXF was dose dependent; maximal effect was seen at a concentration of 125 microM. TNF-alpha, nuclear factor-kappaB (NF-kappaB), and phosphorylated NF-kappaB contents were decreased in ischemic heart but were markedly increased within 2 min of starting reperfusion. The ratio of cytosolic-to-homogenate NF-kappaB was decreased, whereas the ratio of particulate-to-homogenate NF-kappaB was increased in I/R hearts. These changes in TNF-alpha and NF-kappaB protein contents as well as in NF-kappaB redistribution due to I/R were significantly attenuated by PTXF treatment. The results of this study indicate that the cardioprotective effects of PTXF against I/R injury may be due to reductions in the activation of NF-kappaB and the production of TNF-alpha content.