cDNA-AFLP analysis reveals differential gene expression in compatible interaction of wheat challenged with Puccinia striiformis f. sp. tritici

<p>Abstract</p> <p>Background</p> <p><it>Puccinia striiformis </it>f. sp. <it>tritici </it>is a fungal pathogen causing stripe rust, one of the most important wheat diseases worldwide. The fungus is strictly biotrophic and thus, completely dependent on living host cells for its reproduction, which makes it difficult to study genes of the pathogen. In spite of its economic importance, little is known about the molecular basis of compatible interaction between the pathogen and wheat host. In this study, we identified wheat and <it>P. striiformis </it>genes associated with the infection process by conducting a large-scale transcriptomic analysis using cDNA-AFLP.</p> <p>Results</p> <p>Of the total 54,912 transcript derived fragments (TDFs) obtained using cDNA-AFLP with 64 primer pairs, 2,306 (4.2%) displayed altered expression patterns after inoculation, of which 966 showed up-regulated and 1,340 down-regulated. 186 TDFs produced reliable sequences after sequencing of 208 TDFs selected, of which 74 (40%) had known functions through BLAST searching the GenBank database. Majority of the latter group had predicted gene products involved in energy (13%), signal transduction (5.4%), disease/defence (5.9%) and metabolism (5% of the sequenced TDFs). BLAST searching of the wheat stem rust fungus genome database identified 18 TDFs possibly from the stripe rust pathogen, of which 9 were validated of the pathogen origin using PCR-based assays followed by sequencing confirmation. Of the 186 reliable TDFs, 29 homologous to genes known to play a role in disease/defense, signal transduction or uncharacterized genes were further selected for validation of cDNA-AFLP expression patterns using qRT-PCR analyses. Results confirmed the altered expression patterns of 28 (96.5%) genes revealed by the cDNA-AFLP technique.</p> <p>Conclusion</p> <p>The results show that cDNA-AFLP is a reliable technique for studying expression patterns of genes involved in the wheat-stripe rust interactions. Genes involved in compatible interactions between wheat and the stripe rust pathogen were identified and their expression patterns were determined. The present study should be helpful in elucidating the molecular basis of the infection process, and identifying genes that can be targeted for inhibiting the growth and reproduction of the pathogen. Moreover, this study can also be used to elucidate the defence responses of the genes that were of plant origin.</p

The large area detector onboard the eXTP mission

The Large Area Detector (LAD) is the high-throughput, spectral-timing instrument onboard the eXTP mission, a flagship mission of the Chinese Academy of Sciences and the China National Space Administration, with a large European participation coordinated by Italy and Spain. The eXTP mission is currently performing its phase B study, with a target launch at the end-2027. The eXTP scientific payload includes four instruments (SFA, PFA, LAD and WFM) offering unprecedented simultaneous wide-band X-ray timing and polarimetry sensitivity. The LAD instrument is based on the design originally proposed for the LOFT mission. It envisages a deployed 3.2 m2 effective area in the 2-30 keV energy range, achieved through the technology of the large-area Silicon Drift Detectors - offering a spectral resolution of up to 200 eV FWHM at 6 keV - and of capillary plate collimators - limiting the field of view to about 1 degree. In this paper we will provide an overview of the LAD instrument design, its current status of development and anticipated performance

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Determination and Evaluation of Heavy Metal Content of Freshwater Economic Fish in Northeast Guangdong

Concentrations of lead (Pb), cadmium (Cd), chromium (Cr), copper (Cu), zinc (Zn) and manganese (Mn) were measured in various organs (such as in liver and muscle) from 9 species of freshwater economic fishes which were collected from northeast area of Guangdong Province. The concentration of metals was measured by inductively coupled plasma atomic emission spectrometry (ICP-AES). Results showed that the levels of metals in hepatopancreas of the fishes were found in order of Zn>Pb>Cu>Hg>Cd, while in muscles were Zn>Cr>Pb>Mn>Cu>Cd. In general, the metals concentrations were significantly higher in liver samples than that in muscle samples. Based on the “pollution index of single factor”, the fishes, to one degree or another, were polluted by Pb, Cd, Cr, Cu and Zn, and pollution levels were mostly followed by Pb>Cd>Cr>Cu>Zn. The indexes of Pb and Cd tested in hepatopancreas of the fishes were in a majority exceeded the national safety criteria for food in China. What’s more, it was found that the contents of the heavy metals in fishes did not vary with the trophic level which they belong to. In summary, the fishes were polluted by Pb, Cd, Cr, Cu and Zn to some extent, which indicated that hidden danger of heavy metals pollution was present in ecological environment or safety in fishery production in the area

Development of an allele-specific PCR assay for simultaneous sero-typing of avian pathogenic Escherichia coli predominant O1, O2, O18 and O78 strains.

Systemic infections by avian pathogenic Escherichia coli (APEC) are economically devastating to poultry industries worldwide. E. coli strains belonging to serotypes O1, O2, O18 and O78 are preferentially associated with avian colibacillosis. The rfb gene cluster controlling O antigen synthesis is usually various among different E. coli serotypes. In present study, the rfb gene clusters of E. coli serotypes O1, O2, O18 and O78 were characterized and compared. Based on the serotype-specific genes in rfb gene cluster, an allele-specific polymerase chain reaction (PCR) assay was developed. This PCR assay was highly specific and reliable for sero-typing of APEC O1, O2, O18 and O78 strains. The sensitivity of the assay was determined as 10 pg DNA or 10 colony forming units (CFUs) bacteria for serotypes O2 and O18 strains, and 500 pg DNA or 1,000 CFUs bacteria for serotypes O1 and O78 strains. Using this PCR system, APEC isolates and the infected tissue samples were categorized successfully. Furthermore, it was able to differentiate the serotypes for the samples with multi-agglutination in the traditional serum agglutination assay. Therefore, the allele-specific PCR is more simple, rapid and accurate assay for APEC diagnosis, epidemiologic study and vaccine development

Generation and analysis of expression sequence tags from haustoria of the wheat stripe rust fungus Puccinia striiformis f. sp. Tritici

BACKGROUND: Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases of wheat (Triticum aestivum L.) worldwide. In spite of its agricultural importance, the genomics and genetics of the pathogen are poorly characterized. Pst transcripts from urediniospores and germinated urediniospores have been examined previously, but little is known about genes expressed during host infection. Some genes involved in virulence in other rust fungi have been found to be specifically expressed in haustoria. Therefore, the objective of this study was to generate a cDNA library to characterize genes expressed in haustoria of Pst. RESULTS: A total of 5,126 EST sequences of high quality were generated from haustoria of Pst, from which 287 contigs and 847 singletons were derived. Approximately 10% and 26% of the 1,134 unique sequences were homologous to proteins with known functions and hypothetical proteins, respectively. The remaining 64% of the unique sequences had no significant similarities in GenBank. Fifteen genes were predicted to be proteins secreted from Pst haustoria. Analysis of ten genes, including six secreted protein genes, using quantitative RT-PCR revealed changes in transcript levels in different developmental and infection stages of the pathogen. CONCLUSIONS: The haustorial cDNA library was useful in identifying genes of the stripe rust fungus expressed during the infection process. From the library, we identified 15 genes encoding putative secreted proteins and six genes induced during the infection process. These genes are candidates for further studies to determine their functions in wheat-Pst interactions

A survey of potential acceptance of 9-valent HPV vaccine among Chinese male college students

ABSTRACTHuman papillomavirus (HPV) has a great impact on world health. Vaccination is among the most important methods of preventing HPV infection. This study investigated Chinese male college students’ knowledge of, attitude toward, and acceptance of the 9vHPV vaccine and the independent predictors. An online cross-sectional study was conducted among male college students at Chinese colleges and universities from March 12 to March 23, 2022. Based on a literature review of similar studies, a self-questionnaire was designed to investigate the students’ knowledge of, attitude toward, and acceptance of the 9vHPV vaccine. Multivariate logistic regression analysis was performed to identify factors influencing their willingness to be vaccinated. In addition, the structural equation model was constructed. A total of 1,547 male college students completed the survey. Of all the students, 54.95% were unwilling to receive a 9vHPV vaccination, while only 45.05% expressed willingness. Multivariate logistic regression analysis revealed that the male college students willing to receive the vaccine included medical students, those in a romantic relationship, those whose relatives and friends had cervical cancer, those whose relatives and friends had received the 9vHPV vaccine, those supportive of promoting the vaccine for men, and those who would recommend the vaccine to their relatives and friends. Male college students exhibited high hesitancy toward the 9vHPV vaccine. Acceptance of the 9vHPV vaccine by male college students can be improved by deepening their accurate understanding of the vaccine and enhancing their positive attitude toward it

Studies on the Infection, Colonization, and Movement of Pseudomonas syringae pv. actinidiae in Kiwifruit Tissues Using a GFPuv-Labeled Strain.

Kiwifruit bacterial canker, an economically important disease caused by Pseudomonas syringae pv. actinidiae (Psa), has caused severe losses in all major areas of kiwifruit cultivation. Using a GFPuv-labeled strain of Psa, we monitored the invasion, colonization, and movement of the pathogen in kiwifruit twigs, leaves and veins. The pathogen can invade twigs through both wounds and natural openings; the highest number of Psa is obtained in cut tissues. We determined that, following spray inoculation, Psa-GFPuv could infect leaves and cause lesions in the presence and absence of wounds. Light and transmission electron microscopic observations showed that bacterial cells colonize both phloem and xylem vessels. Bacterial infection resulted in marked alterations of host tissues including the disintegration of organelles and degeneration of protoplasts and cell walls. Furthermore, low temperature was conducive to colonization and movement of Psa-GFPuv in kiwifruit tissues. Indeed, the pathogen migrated faster at 4°C than at 16°C or 25°C in twigs. However, the optimum temperature for colonization and movement of Psa in leaf veins was 16°C. Our results, revealing a better understanding of the Psa infection process, might contribute to develop more efficacious disease management strategies

Virulence and Molecular Diversity of the Puccinia striiformis f. sp. tritici Population in Xinjiang in Relation to Other Regions of Western China

In recent years, wheat stripe rust caused severe yield losses in western China, especially the Xinjiang Autonomous Region. The population of the stripe rust fungus Puccinia striiformis f. sp. tritici in the vast region had not been well studied. To determine the population structure and compare it with the populations in the neighboring provinces or autonomous regions, P. striiformis f. sp. tritici isolates from Xinjiang, Qinghai, Gansu, Ningxia, and Tibet in western China were characterized by virulence tests with 19 wheat genotypes that are used to differentiate races of P. striiformis f. sp. tritici in China and by genotyping tests with 15 simple-sequence repeat (SSR) markers. In total, 56 races, including 39 previously known and 17 new races, were identified from 308 isolates obtained from the three epidemiological regions covering five provinces, of which 27 previously known and 8 unknown races were detected in Xinjiang, higher than the numbers in either of the other two regions. The races in Xinjiang consisted of those historically and recently predominant races in other regions of China. The P. striiformis f. sp. tritici population in Xinjiang had a higher genetic diversity than populations in other epidemiological regions. Molecular variation among subpopulations within Xinjiang was higher than in other regions. Both virulence and molecular data indicate that the P. striiformis f. sp. tritici population in Xinjiang is related to but more diverse than those in other epidemiological regions. The results show that Xinjiang is an important stripe rust epidemiological region in China, and the information should be useful for control of the disease in the region as well as in other regions