The function of small RNAs in plant biotic stress response

Small RNAs(s RNAs) play essential roles in plants upon biotic stress. Plants utilize RNA silencing machinery to facilitate pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity to defend against pathogen attack or to facilitate defense against insect herbivores. Pathogens, on the other hand, are also able to generate effectors and s RNAs to counter the host immune response. The arms race between plants and pathogens/insect herbivores has triggered the evolution of s RNAs,RNA silencing machinery and pathogen effectors. A great number of studies have been performed to investigate the roles of s RNAs in plant defense, bringing in the opportunity to utilize s RNAs in plant protection. Transgenic plants with pathogen-derived resistance ability or transgenerational defense have been generated, which show promising potential as solutions for pathogen/insect herbivore problems in the field. Here we summarize the recent progress on the function of s RNAs in response to biotic stress, mainly in plant-pathogen/insect herbivore interaction,and the application of s RNAs in disease and insect herbivore control.     

Psychosine-induced alterations in peroxisomes of twitcher mouse liver

Krabbe disease is a neuroinflammatory disorder in which galactosylsphingosine (psychosine) accumulates in nervous tissue. To gain insight into whether the psychosine-induced effects in nervous tissue extend to peripheral organs, we investigated the expression of cytokines and their effects on peroxisomal structure/functions in twitcher mouse liver (animal model of Krabbe disease). Immunofluorescence analysis demonstrated TNF-α and IL-6 expression, which was confirmed by mRNAs quantitation. Despite the presence of TNF-α, lipidomic analysis did not indicate a significant decrease in sphingomyelin or an increase in ceramide fractions. Ultrastructural analysis of catalase-dependent staining of liver sections showed reduced reactivity without significant changes in peroxisomal contents. This observation was confirmed by assaying catalase activity and quantitation of its mRNA, both of which were found significantly decreased in twitcher mouse liver. Western blot analysis demonstrated a generalized reduction of peroxisomal matrix and membrane proteins. These observations indicate that twitcher mouse pathobiology extends to the liver, where psychosine-induced TNF-α and IL-6 compromise peroxisomal structure and functions.     

Application of antimicrobial polypeptide host defenses to aquaculture: Exploitation of downregulation and upregulation responses

Antimicrobial polypeptides (AMPPs), consisting of peptides and small proteins with antimicrobial activity, are an integral component of innate immunity. Their often potent properties and widespread prevalence in fish suggests that designing means of manipulating their levels has considerable potential for maintaining or improving fish health. There is evidence that a number of chronic stresses lead to significant downregulation of AMPPs and thus their monitoring could be a highly sensitive measure of health status and risk of an infectious disease outbreak. Conversely, upregulation of AMPP expression could be used to enhance disease resistance in stressful environments, as well as improve the efficacy of traditional antimicrobial drugs. However, further work is required in linking levels of a number of AMPPs to physiological function since, while a number of studies have documented the down- or upregulation of AMPPs via gene expression, relatively few studies have quantitatively examined changes in protein expression. In addition, not all AMPPs appear to be expressed at microbicidal levels in vivo, suggesting that at least some may have functions other than being directly protective. Nonetheless, in fish, there is evidence that some constitutively expressed AMPPs, such as piscidins and histone-like proteins, are expressed at microbicidal levels and that they decline with stress. Furthermore, certain AMPPs derived from hemoglobin-β are upregulated to microbicidal levels after experimental challenge. The likely widespread distribution of these three AMPP groups in fish provides the opportunity to design strategies to greatly improve the health of cultured fish populations.     

Profile of rhythmic gene expression in the livers of obese diabetic KK-A(y) mice

Although a number of genes expressed in most tissues, including the liver, exhibit circadian regulation, gene expression profiles are usually examined only at one scheduled time each day. In this study, we investigated the effects of obese diabetes on the hepatic mRNA levels of various genes at 6-h intervals over a single 24-h period. Microarray analysis revealed that many genes are expressed rhythmically, not only in control KK mice but also in obese diabetic KK-A(y) mice. Real-time quantitative PCR verified that 19 of 23 putative circadianly expressed genes showed significant 24-h rhythmicity in both strains. However, obese diabetes attenuated these expression rhythms in 10 of 19 genes. More importantly, the effects of obese diabetes were observed throughout the day in only two genes. These results suggest that observation time influences the results of gene expression analyses of genes expressed circadianly.     

A novel approach for multi-domain and multi-gene family identification provides insights into evolutionary dynamics of disease resistance genes in core eudicot plants

Background

Recent advances in DNA sequencing techniques resulted in more than forty sequenced plant genomes representing a diverse set of taxa of agricultural, energy, medicinal and ecological importance. However, gene family curation is often only inferred from DNA sequence homology and lacks insights into evolutionary processes contributing to gene family dynamics. In a comparative genomics framework, we integrated multiple lines of evidence provided by gene synteny, sequence homology and protein-based Hidden Markov Modelling to extract homologous super-clusters composed of multi-domain resistance (R)-proteins of the NB-LRR type (for NUCLEOTIDE BINDING/LEUCINE-RICH REPEATS), that are involved in plant innate immunity.

Results

To assess the diversity of R-proteins within and between species, we screened twelve eudicot plant genomes including six major crops and found a total of 2,363 NB-LRR genes. Our curated R-proteins set shows a 50% average for tandem duplicates and a 22% fraction of gene copies retained from ancient polyploidy events (ohnologs). We provide evidence for strong positive selection and show significant differences in molecular evolution rates (Ka/Ks-ratio) among tandem- (mean = 1.59), ohnolog (mean = 1.36) and singleton (mean = 1.22) R-gene duplicates. To foster the process of gene-edited plant breeding, we report species-specific presence/absence of all 140 NB-LRR genes present in the model plant Arabidopsis and describe four distinct clusters of NB-LRR “gatekeeper” loci sharing syntenic orthologs across all analyzed genomes.

Conclusion

By curating a near-complete set of multi-domain R-protein clusters in an eudicot-wide scale, our analysis offers significant insight into evolutionary dynamics underlying diversification of the plant innate immune system. Furthermore, our methods provide a blueprint for future efforts to identify and more rapidly clone functional NB-LRR genes from any plant species.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-966) contains supplementary material, which is available to authorized users.     

肝源性肝细胞再生刺激因子(HSS)的制备及鉴定

本文采用新鲜乳牛肝脏作为原料。经酸处理、超滤、分离得到肝源性肝细胞再生刺激因子（ＨＳＳ）。ＳＤＳ－ＰＡＧＥ测得ＨＳＳ的蛋白质分子量为１２,０００～１５,０００Ｄａ。经动物试验和生物学活性鉴定,表明本法制备的ＨＳＳ符合《中国生物制品规程》（１９９５版）的有关要求,且工艺简便、有效     

Active specific immunotherapy with Newcastle-diseasevirus-modified autologous tumor cells following resection of liver metastases in colorectal cancer

Summary A group of 23 colorectal cancer patients were treated by a new type of active specific immunotherapy (ASI) following complete surgical resection of liver metastases (R0 resection). For ASI treatment we used a vaccine consisting of 1 × 10⁷ autologous, irradiated (200 Gy) metastases-derived tumor cells incubated with 32 hemagglutination units (HU) of Newcastle disease virus (NDV). The adjuvant vaccine therapy was started 2 weeks after surgery and was repeated five times at 14-days intervals followed by one boost 3 months later. The delayed-type hypersensitivity (DTH) skin reactions to the vaccine were measured as well as the DTH reactions to a challenge test of 1 × 10⁷ non-virus-modified autologous tumor cells from liver metastases or 1 × 10⁷ autologous normal liver cells. In addition 32 HU NDV alone and a standard antigen test (Merieux test) were applied pre- and post-vaccination. The vaccination was well tolerated. In 13 of 23 patients an increasing reactivity against the vaccine was observed during the vaccination procedure. Nine patients (40%) experienced an increased DTH reactivity against autologous tumor cells following vaccination, while 17% or fewer showed an increased reactivity to Merieux test antigens, NDV, or normal liver cells. The increased antitumor response was not correlated to responsiveness to NDV alone, autologous liver cells, enzymes and culture medium used for vaccine preparation or standard antigens (Merieux test). After a follow-up of at least 18 months 61% of the vaccinated patients developed tumor recurrence in comparison to 87% of a matched control groups from the same institution that had been only surgically treated. The results of this phase II trial are encouraging and should stimulate further prospective randomized studies.     

A 31P-NMR study of the intact liver fluke Fasciola hepatica

³¹P-NMR techniques offer a useful method of studying changes in the metabolism of intact parasitic worms. The liver flukes, Fasciola hepatica, provide good quality ³¹P high resolution NMR spectra for at least 6 h under anaerobic conditions. The levels of ATP remain constant throughout this period. There is no signal for phosphocreatine or phosphoarginine. In contrast to the findings in mammalian tissues, there is a distinct peak for the terminal phosphate of ADP. A number of signals are observed in the phosphodiester region of the spectrum the largest of which is identified as l-α-glycerophosphoryl choline. Serotonin (5-hydroxytryptamine) causes an appreciable increase in the levels of sugar phosphates when the flukes are incubated in the absence of glucose. The addition of glucose also causes a marked increase in the signals for the hexose phosphate.     

天然保肝药研究进展

本文综述了天然保肝药的筛选方法,活性成分的化学结构,以及临床应用.