Huoming Zhang

Rapid transcriptome and proteome profiling of a non‐model marine invertebrate, Bugula neritina

Non‐model organisms represent the majority of life forms in our planet. However, the lack of genetic information hinders us to understand the unique biological phenomena in non‐model organisms at the molecular level. In this study, we applied a tandem transcriptome and proteome profiling on a non‐model marine fouling organism, Bugula neritina. Using a 454 pyrosequencing platform with the updated titanium reagents, we generated a total of 48Mu2009bp transcriptome data consisting of 131u2009450 high‐quality reads. Of these, 122u2009650 reads (93%) were assembled to produce 6392 contigs with an average length of 538 bases and the remaining 8800 reads were singletons. Of the total 15u2009192 unigenes, 13u2009863 ORFs were predicated, of which 6917 were functionally annotated based on gene ontology and eukaryotic orthologous groups. Subsequent proteome analysis identified and quantified 882 proteins from B. neritina. These results would provide fundamental and important information for the subsequent studies of molecular mechanism in larval biology, development, antifouling research. Furthermore, we demonstrated, for the first time, the combined use of two high‐throughput technologies as a powerful approach for accelerating the studies of non‐model but otherwise important species.

Identification of redox-sensitive cysteines in the arabidopsis proteome using OxiTRAQ, a quantitative redox proteomics method

Cellular redox status plays a key role in mediating various physiological and developmental processes often through modulating activities of redox‐sensitive proteins. Various stresses trigger over‐production of reactive oxygen/nitrogen species which lead to oxidative modifications of redox‐sensitive proteins. Identification and characterization of redox‐sensitive proteins are important steps toward understanding molecular mechanisms of stress responses. Here, we report a high‐throughput quantitative proteomic approach termed OxiTRAQ for identifying proteins whose thiols undergo reversible oxidative modifications in Arabidopsis cells subjected to oxidative stress. In this approach, a biotinylated thiol‐reactive reagent is used for differential labeling of reduced and oxidized thiols. The biotin‐tagged peptides are affinity purified, labeled with iTRAQ reagents, and analyzed using a paralleled HCD‐CID fragmentation mode in an LTQ‐Orbitrap. With this approach, we identified 195 cysteine‐containing peptides from 179 proteins whose thiols underwent oxidative modifications in Arabidopsis cells following the treatment with hydrogen peroxide. A majority of those redox‐sensitive proteins, including several transcription factors, were not identified by previous redox proteomics studies. This approach allows identification of the specific redox‐regulated cysteine residues, and offers an effective tool for elucidation of redox proteomes.

Quantitative analysis of oyster larval proteome provides new insights into the effects of multiple climate change stressors

The metamorphosis of planktonic larvae of the Pacific oyster (Crassostrea gigas) underpins their complex life-history strategy by switching on the molecular machinery required for sessile life and building calcite shells. Metamorphosis becomes a survival bottleneck, which will be pressured by different anthropogenically induced climate change-related variables. Therefore, it is important to understand how metamorphosing larvae interact with emerging climate change stressors. To predict how larvae might be affected in a future ocean, we examined changes in the proteome of metamorphosing larvae under multiple stressors: decreased pH (pH 7.4), increased temperature (30xa0°C), and reduced salinity (15xa0psu). Quantitative protein expression profiling using iTRAQ-LC-MS/MS identified more than 1300 proteins. Decreased pH had a negative effect on metamorphosis by down-regulating several proteins involved in energy production, metabolism, and protein synthesis. However, warming switched on these down-regulated pathways at pH 7.4. Under multiple stressors, cell signaling, energy production, growth, and developmental pathways were up-regulated, although metamorphosis was still reduced. Despite the lack of lethal effects, significant physiological responses to both individual and interacting climate change related stressors were observed at proteome level. The metamorphosing larvae of the C.xa0gigas population in the Yellow Sea appear to have adequate phenotypic plasticity at the proteome level to survive in future coastal oceans, but with developmental and physiological costs.

Quantitative proteomics study of larval settlement in the barnacle Balanus amphitrite

Barnacles are major sessile components of the intertidal areas worldwide, and also one of the most dominant fouling organisms in fouling communities. Larval settlement has a crucial ecological effect not only on the distribution of the barnacle population but also intertidal community structures. However, the molecular mechanisms involved in the transition process from the larval to the juvenile stage remain largely unclear. In this study, we carried out comparative proteomic profiles of stage II nauplii, stage VI nauplii, cyprids, and juveniles of the barnacle Balanus amphitrite using label-free quantitative proteomics, followed by the measurement of the gene expression levels of candidate proteins. More than 700 proteins were identified at each stage; 80 were significantly up-regulated in cyprids and 95 in juveniles vs other stages. Specifically, proteins involved in energy and metabolism, the nervous system and signal transduction were significantly up-regulated in cyprids, whereas proteins involved in cytoskeletal remodeling, transcription and translation, cell proliferation and differentiation, and biomineralization were up-regulated in juveniles, consistent with changes associated with larval metamorphosis and tissue remodeling in juveniles. These findings provided molecular evidence for the morphological, physiological and biological changes that occur during the transition process from the larval to the juvenile stages in B. amphitrite.

The Putative E3 Ubiquitin Ligase ECERIFERUM9 Regulates Abscisic Acid Biosynthesis and Response during Seed Germination and Postgermination Growth in Arabidopsis

A wax locus negatively regulates ABA response within a small time window during seed germination and also affects ABA levels in seeds. The ECERIFERUM9 (CER9) gene encodes a putative E3 ubiquitin ligase that functions in cuticle biosynthesis and the maintenance of plant water status. Here, we found that CER9 is also involved in abscisic acid (ABA) signaling in seeds and young seedlings of Arabidopsis (Arabidopsis thaliana). The germinated embryos of the mutants exhibited enhanced sensitivity to ABA during the transition from reversible dormancy to determinate seedling growth. Expression of the CER9 gene is closely related to ABA levels and displays a similar pattern to that of ABSCISIC ACID-INSENSITIVE5 (ABI5), which encodes a positive regulator of ABA responses in seeds. cer9 mutant seeds exhibited delayed germination that is independent of seed coat permeability. Quantitative proteomic analyses showed that cer9 seeds had a protein profile similar to that of the wild type treated with ABA. Transcriptomics analyses revealed that genes involved in ABA biosynthesis or signaling pathways were differentially regulated in cer9 seeds. Consistent with this, high levels of ABA were detected in dry seeds of cer9. Blocking ABA biosynthesis by fluridone treatment or by combining an ABA-deficient mutation with cer9 attenuated the phenotypes of cer9. Whereas introduction of the abi1-1, abi3-1, or abi4-103 mutation could completely eliminate the ABA hypersensitivity of cer9, introduction of abi5 resulted only in partial suppression. These results indicate that CER9 is a novel negative regulator of ABA biosynthesis and the ABA signaling pathway during seed germination.

Dependency on de novo protein synthesis and proteomic changes during metamorphosis of the marine bryozoan Bugula neritina

BackgroundMetamorphosis in the bryozoan Bugula neritina (Linne) includes an initial phase of rapid morphological rearrangement followed by a gradual phase of morphogenesis. We hypothesized that the first phase may be independent of de novo synthesis of proteins and, instead, involves post-translational modifications of existing proteins, providing a simple mechanism to quickly initiate metamorphosis. To test our hypothesis, we challenged B. neritina larvae with transcription and translation inhibitors. Furthermore, we employed 2D gel electrophoresis to characterize changes in the phosphoproteome and proteome during early metamorphosis. Differentially expressed proteins were identified by liquid chromatography tandem mass spectrometry and their gene expression patterns were profiled using semi-quantitative real time PCR.ResultsWhen larvae were incubated with transcription and translation inhibitors, metamorphosis initiated through the first phase but did not complete. We found a significant down-regulation of 60 protein spots and the percentage of phosphoprotein spots decreased from 15% in the larval stage to12% during early metamorphosis. Two proteins--the mitochondrial processing peptidase beta subunit and severin--were abundantly expressed and phosphorylated in the larval stage, but down-regulated during metamorphosis. MPPbeta and severin were also down-regulated on the gene expression level.ConclusionsThe initial morphogenetic changes that led to attachment of B. neritina did not depend on de novo protein synthesis, but the subsequent gradual morphogenesis did. This is the first time that the mitochondrial processing peptidase beta subunit or severin have been shown to be down-regulated on both gene and protein expression levels during the metamorphosis of B. neritina. Future studies employing immunohistochemistry to reveal the expression locality of these two proteins during metamorphosis should provide further evidence of the involvement of these two proteins in the morphogenetic rearrangement of B. neritina.

Proteomic Changes in Brain Tissues of Marine Medaka (Oryzias melastigma) After Chronic Exposure to Two Antifouling Compounds: Butenolide and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT)

SeaNine 211 with active ingredient of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) has been used as a green antifouling agent worldwide but has raised serious biosafety concerns in coastal environments. DCOIT has the potential to disrupt the neurotransmission in nervous system, but the underlying mechanism has not been clarified. In the present study, we used TMT six-plex labeling coupled with two-dimensional LC-MS/MS analysis to investigate the protein expression profiles in brain tissues of the marine medaka (Oryzias melastigma) after a 28-day exposure to environmentally-realistic concentration of DCOIT at 2.55 μg/L (0.009 μM) or butenolide, one promising antifouling compound, at 2.31 μg/L (0.012 μM). DCOIT and butenolide induced differential expression of 26 and 18 proteins in male brains and of 27 and 23 proteins in female brains, respectively. Distinct mechanisms of toxicity were initiated by DCOIT and butenolide in males, whereas the protein expression profiles were largely similar in females treated by these two compounds. In males, DCOIT exposure mainly led to disruption of mitogen-activated protein kinase (MAPK) signaling pathway, while butenolide affected proteins related to the cytoskeletal disorganization that is considered as a general response to toxicant stress. Furthermore, a sex-dependent protein expression profile was also noted between male and female fish, as evident by the inverse changes in the expressions of common proteins (5 proteins for butenolide- and 2 proteins for DCOIT-exposed fish). Overall, this study provided insight into the molecular mechanisms underlying the toxicity of DCOIT and butenolide. The extremely low concentrations used in this study highlighted the ecological relevance, arguing for thorough assessments of their ecological risks before the commercialization of any new antifouling compound.

Proteomic identification of early salicylate- and flg22-responsive redox-sensitive proteins in Arabidopsis

Accumulation of reactive oxygen species (ROS) is one of the early defense responses against pathogen infection in plants. The mechanism about the initial and direct regulation of the defense signaling pathway by ROS remains elusive. Perturbation of cellular redox homeostasis by ROS is believed to alter functions of redox-sensitive proteins through their oxidative modifications. Here we report an OxiTRAQ-based proteomic study in identifying proteins whose cysteines underwent oxidative modifications in Arabidopsis cells during the early response to salicylate or flg22, two defense pathway elicitors that are known to disturb cellular redox homeostasis. Among the salicylate- and/or flg22-responsive redox-sensitive proteins are those involved in transcriptional regulation, chromatin remodeling, RNA processing, post-translational modifications, and nucleocytoplasmic shuttling. The identification of the salicylate-/flg22-responsive redox-sensitive proteins provides a foundation from which further study can be conducted toward understanding biological significance of their oxidative modifications during the plant defense response.

Quantitative proteomics reveals differential biological processes in healthy neonatal cord neutrophils and adult neutrophils.

Neonatal neutrophils are characterized by the immaturity of bactericidal mechanisms that contributes largely to neonatal mortality. However, underlying molecular mechanism associated with the immaturity remains incompletely understood. In this study, we performed comparative proteomic analysis on neonatal neutrophils derived from human cord blood and adult peripheral neutrophils. A total of 1332 proteins were identified and quantified, and 127 proteins were characterized as differentially expressed between adult and cord neutrophils. The differentially expressed proteins are mapped in KEGG pathways into five clusters and indicated impaired functions of neonatal neutrophils in proteasome, lysosome, phagosome, and leukocyte transendothelial migration. In particular, many proteins associated with NETosis, a critical mechanism for antimicrobial process and auto‐clearance, were also found to be downregulated in cord neutrophils. This study represents a first comparative proteome profiling of neonatal and adult neutrophils, and provides a global view of differentially expressed proteome for enhancing our understanding of their various functional difference.

The Arabidopsis gene DIG6 encodes a large 60S subunit nuclear export GTPase 1 that is involved in ribosome biogenesis and affects multiple auxin-regulated development processes

Highlight DIG6 encodes a large 60S subunit GTPase 1 and affects ribosome biogenesis, and auxin response and homeostasis.