Japonicum Isolates Research Articles

Quality control of Bradyrhizobium inoculant strains: detection of nosZ and correlation of symbiotic efficiency with soybean leaf chlorophyll levels

Greenhouse gas emissions, such as N2O from excessive N-fertilizer use, are of concern. Symbiotic N2-fixation by pulses such as soybean might mitigate this issue, for which inoculants carrying locally adapted Bradyrhizobium strains are recommended. In the frame of this goal, enhancing the quality control of these inoculants is required on two key aspects: determining the presence of nosZ, for the strains being able to reduce N2O, and assessing N2-fixation potential. Previously it was demonstrated that, in soybean leaves, N-contents are well correlated with chlorophyll contents. However, no such correlations were made with either N obtained from N2-fixation or with nodules mass, which is an indicator of nodular activity. Here we aimed to leverage the correlation between N and chlorophyll levels to develop a simple and non-destructive laboratory method to be applied in quality control of inoculants, able to assess the N2-fixing capacity of rhizobial strains. To establish such correlations, we cultivated soybeans in vermiculite with N-free nutrient solution, and inoculated them with various Bradyrhizobium field isolates that displayed a range of symbiotic N2-fixing capacities. Subsequently, we measured chlorophyll with a portable chlorophyllometer, and correlated these measures with symbiotic parameters. Moreover, we tested for the presence of nosZ by PCR. We observed significant correlations between chlorophyll and shoot nitrogen obtained from N2-fixation and, in addition, we corroborated that chlorophyll contents were significantly correlated also with nodules mass. Two B. diazoefficiens strains stood out and possessed nosZ. In contrast, B. elkanii and B. japonicum isolates displayed lower chlorophyll and symbiotic performance, and lacked nosZ. Our findings highlight the potential of measuring chlorophyll contents and testing for the presence of nosZ as two straightforward techniques that may enhance laboratory tests for quality control, enabling selection of superior and safe locally isolated strains for soybean inoculants without increased production costs.

Comparison of pathogenicity and gene expression profiles between adult Schistosoma japonicum isolated from hilly and marshland and lake regions of Anhui Province

To compare the differences in pathogenicity and gene expression profiles between adult Schistosoma japonicum isolated from hilly and marshland and lake regions of Anhui Province, so as to provide the scientific evidence for formulating the precise schistosomiasis control strategy in different endemic foci. C57BL/6 mice were infected with cercariae of S. japonicum isolates from Shitai County (hilly regions) and Susong County (marshland and lake regions) of Anhui Province in 2021, and all mice were sacrificed 44 days post-infection and dissected. The worm burdens, number of S. japonicum eggs deposited in the liver, and the area of egg granulomas in the liver were measured to compare the difference in the pathogenicity between the two isolates. In addition, female and male adult S. japonicum worms were collected and subjected to transcriptome sequencing, and the gene expression profiles were compared between Shitai and Susong isolates of S. japonicum. The differentially expressed genes (DEGs) were subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. The total worm burdens [(14.50 ± 3.96) worms/mouse vs. (16.10 ± 3.78) worms/mouse; t = 0.877, P = 0.392], number of female and male paired worms [(4.50 ± 0.67) worms/mouse vs. (5.10 ± 1.45) worms/mouse; t = 1.129, P = 0.280], number of unpaired male worms [(5.50 ± 4.01) worms/mouse vs. (5.60 ± 1.69) worms/mouse; t = 0.069, P = 0.946], number of eggs deposited in per gram liver [(12 116.70 ± 6 508.83) eggs vs. (16 696.70 ± 4 571.56) eggs; t = 1.821, P = 0.085], and area of a single egg granuloma in the liver [(74 359.40 ± 11 766.34) µm2 vs. (74 836.90 ± 13 086.12) µm2; t = 0.081, P = 0.936] were comparable between Shitai and Susong isolates of S. japonicum. Transcriptome sequencing identified 584 DEGs between adult female worms and 1 598 DEGs between adult male worms of Shitai and Susong isolates of S. japonicum. GO enrichment analysis showed that the DEGs between female adults were predominantly enriched in biological processes of stimulus response, cytotoxicity, multiple cell biological processes, metabolic processes, cellular processes and signaling pathways, cellular components of cell, organelles and cell membranes and molecular functions of binding and catalytic ability, and KEGG enrichment analysis showed that these DEGs were significantly enriched in pathways of vascular endothelial growth factor signaling, glutathione metabolism, arginine and proline metabolism. In addition, the DEGs between male adults were predominantly enriched in biological processes of signaling transduction, multiple cell biological processes, regulation of biological processes, metabolic processes, development processes and stimulus responses, cellular components of extracellular matrix and cell junction and molecular functions of binding and catalytic ability, and these DEGs were significantly enriched in pathways of Wnt signaling, Ras signaling, natural killer cells-mediated cytotoxicity, extracellular matrix-receptor interactions and arginine biosynthesis. There is no significant difference in the pathogenicity between S. japonicum isolates from hilly and marshland and lake regions of Anhui Province; however, the gene expression profiles vary significantly between S. japonicum isolates.

A chromosome-level genome of the human blood fluke Schistosoma japonicum identifies the genomic basis of host-switching.

The evolution and adaptation of S.japonicum, a zoonotic parasite that causes human schistosomiasis, remain unclear because of the lack of whole-genome data. We construct a chromosome-level S.japonicum genome and analyze it together with 72 samples representing six populations of the entire endemic region. We observe a Taiwan zoophilic lineage splitting from zoonotic populations ∼45,000 years ago, consistent with the divergent history of their intermediate hosts. Interestingly, we detect a severe population bottleneck in S.japonicum, largely coinciding with human history in Asia during the last glacial maximum. We identify several genomic regions underlying natural selection, including GATAD2A and Lmln, both showing remarkable differentiation among different areas. RNAi knockdown suggests association of GATAD2A with parasite development and infection in definitive hosts, while Lmln relates to the specificity of the intermediate hosts. Our study provides insights into the evolution of S.japonicum and serves as a resource for further studies.

In vivo praziquantel efficacy of Schistosoma japonicum over time: A systematic review and meta-analysis

Praziquantel (PZQ), the only choice of chemotherapy for schistosomiasis recommended by World Health Organization (WHO), has been widely used over 40 years. The long-term, and rapid expansion of, PZQ use for disease control across a large populations continues to raise concern regarding the potential for emergence and establishment of drug resistance. Recent research has also proposed that the long survival and low sensitivity of unpaired worms, derived from either incomplete treatment cure rates or single-sex schistosome infections within final hosts, could exacerbate the risk of PZQ resistance (PZQ-R) emerging. With the aim of assessing whether PZQ efficacy amongst S. japonicum may have changed over time in China, we performed a unique systematic review and meta-analyses on datasets which evaluated the efficacy of PZQ via laboratory assays of field S. japonicum isolates on experimental mice over time. Relevant published literatures from four electronic bibliographic databases and lists of article references were searched. Two indexes, d, a measure used in meta-analyses for worm burden difference between two groups, and r, a traditional measure for worm reduction percentage after treatment but without considering sample size were calculated for each study. A total of 25 papers including 127 experimental studies with eligible data on 2230 mice were retrieved. The pooled d (D) was 3.91 (3.56–4.25) and pooled r (R) was 54.52% (52.55%–56.52%). D significantly increased over time, whereas R non-significantly decreased; both estimates were significantly associated with the total drug dose. Such findings suggested no evidence of PZQ-R emergence S. japonicum to date. However, we consider the potential role of parasite origins, PZQ dosage, and single versus mixed gender infections of the results published to date, and the avenues now needed for further research.

Studies on resistance of Schistosoma to praziquantel XVIII Sensitivity to praziquantel in filial generations of praziquantel-resistant and -sensitive Schistosoma japonicum mixed infections

To investigate the sensitivity of adult worms of filial generations from praziquantel-resistant and -sensitive Schistosoma japonicum mixed infections to praziquantel. Mice were infected with the cercariae of an experimentally generated praziquantel-resistant S. japonicum isolate [median effective dose (ED50) = 277.4 mg/kg] and a laboratory-maintained praziquantel-sensitive S. japonicum isolate (ED50 = 99.6 mg/kg) at a mixture ratio of 1:1 and 2:1, which was maintained in the laboratory via the mouse-snail cycle for 8 generations. Then, mice were infected with the cercariae of the 8th filial-generation parasite, and grouped 35 days post-infection. Mice in the 5 treatment groups were given praziquantel treatment by gavage at a single oral dose of 37.5, 75, 150, 300 mg/kg and 600 mg/kg, while animals in the control group was administered orally with 2.5% cremophor EL. All mice were sacrificed 14 days post-treatment and adult worms were collected by perfusion of the portal vein. The worm burden reductions and praziquantel ED50 values were calculated. The praziquantel-resistant S. japonicum isolate generated from experimental induction with 12 rounds of praziquantel treatment with sub-curative doses was maintained in the laboratory via the mouse-snail cycle, and mice were infected with the cercariae of the 8th filial-generation parasite. The praziquantel ED50 value against the 8th filial-generation adults was measured. After mice were infected with the mixture of cercariae of PZQ-resistant and -sensitive S. japonicum isolates at a ratio of 1:1, the praziquantel ED50 was 135.2 mg/kg against the adults of the 8th filial-generation parasite. After mice were infected with the mixture of cercariae of PZQ-resistant and -sensitive S. japonicum isolates at a ratio of 2:1, the praziquantel ED50 was 129.2 mg/kg against the adults of the 8th filial-generation parasite. In addition, the praziquantel ED50 was 208.4 mg/kg against the adults of the 8th filial-generation S. japonicum without the selection pressure of praziquantel. Compared with the experimentally induced praziquantel-resistant S. japonicum isolate, the adult worms of the filial-generation S. japonicum show a reduced sensitivity to praziquantel in the same host following infection with the mixture of cercariae of praziquantel-resistant and -sensitive S. japonicum isolates. The adult worms of the filial generation of the praziquantel-resistant S. japonicum isolate without the selection pressure of praziquantel may still maintain the resistance to praziquantel.

The efficacy of biofertilizer contains Bradyrhizobium japonicum isolates on soybean yields grown in Inceptisols, Bogor, West Java, Indonesia

The use of biofertilizers is growing rapidly and promising for food crops and horticulture. They are capable to improve soil fertility, increase crop growth and yield, and environment friendly. Soybean is a strategic commodity in Indonesia. Various ways of cultural practice to improve soybean yield have been reported. The biofertilizer containing six Bradyrhizobium japonicum isolates with husk charcoal powder carrier material has been tested on soybean in Cibungbulang Bogor. Our objective was to evaluate the efficacy of Bradyrhizobium japonicum biofertilizer on soybean growth and the yield on Inceptisols Cibungbulang Bogor. The experiment was a randomized block design consisted of seven treatments with four replications. The treatments were (1) Control, no fertilizer (2) 100% NPK (3) Biofertilizer, (4) Biofertilizer + 25%NPK, (5) Biofertilizer + 50% NPK, (6) Biofertilizer + 75% NPK and (7) Biofertilizer + 100% NPK. The results showed that the promising treatment to improve soybean yield was Biofertilizer + 50% NPK and Biofertilizer + 75% NPK as indicated by significantly increase of soybean yield from 18.56 to 25.77% compared to the treatments of 100% NPK, reduced NPK fertilizer 25 to 50%. The values of Relative Agronomic Effectiveness were 191% and 165%. This study implies that the application of biofertilizer gave a positive result both on the growth and yield of soybean.

DIVERSITY OF NODD GENE OF SOME RHIZOBIUM ISOLATES FROM DIFFERENT LEGUMES.

This study was conducted to 1) isolate and characterize some rhizobia from some legumes, 2) determine the phylogenetic relationships among them; and 3) investigate their potential biological control agent. 24 Rhizobial isolates were obtained from five legumes namely; faba bean, lentil, pea, clover, and soybean. Morphological characterization classified isolates into fast grower and slow grower. Also, their biochemical profiles using API 20E and API 20NE system showed large diversity which may reflect their adaptation in different environments. Moreover, molecular detection by 16S rDNA gene was able to characterize 19 of them to species level. Isolates from pea, faba bean, clover and lentil were Rhizobium leguminosarum and isolates from soybean were Bradyrhizobium japonicum. This data supported the idea that there is a narrow diversity of species of rhizobia in Egypt. Phylogenetic analysis of the 19 isolates confirmed that the Bradyrhizobium japonicum isolates were phylogenetically divergent from all other isolates. Also, the phylogram revealed that each group of isolates originated from root nodule of a certain legume formed a separate sub-cluster. Besides a narrow range of interspecies variations was found which is consistent with the idea of biovars presence among species. In addition, the 24 isolates showed strong inhibition of growth of Fusarium and Rhizoctonia phytopathogens. However, results indicated that 25% of isolates were not able to solubilize tricalcium phosphate. On the other hand, the IAA production by the 24 isolates varied greatly among isolates. Therefore, these results demonstrated that they may have the potential to act as biocontrol agents. Moreover, we characterize Nod D gene on the molecular level. Upon its isolation its size came to be 820 bp of nucleotides. This came to be true for all bacterial isolates except four isolates we did not succeed to isolate NodD gene. Moreover we used Quantitative Real Time PCR to study NodD gene expression. Seven nod D gene were down regulated and five were up regulated than 16S housekeeping gene.

Effect of photoperiod change on chronobiology of cercarial emergence of Schistosoma japonicum derived from hilly and marshy regions of China

The chronobiology of cercarial emergence appeared to be a genetically controlled behavior, adapted to definitive host species, for schistosome. However, a few physiological and ecological factors, for example the change of photoperiod, were reported to affect the rhythmic emergence of cercariae. Therefore, the effect of photoperiod change on cercarial emergence of two Schistosoma japonicum isolates, the hilly and the marshland, was investigated. Four shedding experiments each under a different photoperiod were conducted. Under a natural photoperiod, two distinct shedding modes, one from the hilly region and one from the marshland, were observed. Under a reversed photoperiod, the regular pattern (i.e. under a natural photoperiod) of S. japonicum cercarial emergence was reversed for the marshland isolate and disappeared for the hilly isolate. With an input of a 2 h darkness from 7am to 9am, the cercarial emergence peak were delayed for the two isolates; whereas with an input of a 2 h darkness from 5pm to 7pm, neither effect on the cercarial emergence rhythm was observed. The total cercariae emerged for both parasite isolates varied with a different photoperiod. The results indicate that the change of photoperiod could affect the chronobiology of S japonicum cercarial emergence.

Comparison of genetic diversity and population structure between two Schistosoma japonicum isolates--the field and the laboratory.

Schistosomiasis japonicum is one of the most important human parasitic diseases, and a number of studies have recently elucidated the difference in biological characteristics of S. japonicum among different parasite isolates, for example, between the field and the laboratory isolates. Therefore, the understanding of underlying genetic mechanism is of both theoretical and practical importance. In this study, we used six microsatellite markers to assess genetic diversity, population structure, and the bottleneck effect (a sharp reduction in population size) of two parasite populations, one field and one laboratory. A total of 136 S. japonicum cercariae from the field and 86 from the laboratory, which were genetically unique within single snails, were analyzed. The results showed bigger numbers of alleles and higher allelic richness in the field parasite population than in the laboratory indicating lower genetic diversity in the laboratory parasites. A bottleneck effect was detected in the laboratory population. When the field and laboratory isolates were combined, there was a clear distinction between two parasite populations using the software Structure. These genetic differences may partially explain the previously observed contrasted biological traits.

Genetic variability among Schistosoma japonicum isolates from the Philippines, Japan and China revealed by sequence analysis of three mitochondrial genes

The present study examined sequence variability in the mitochondrial (mt) protein–coding genes cytochrome b (cytb), NADH dehydrogenase subunits 2 and 6 (nad2 and nad6) among 24 isolates of Schistosoma japonicum from different endemic regions in the Philippines, Japan and China. The complete cytb, nad2 and nad6 genes were amplified and sequenced separately from individual schistosome. Sequence variations for isolates from the Philippines were 0–0.5% for cytb, 0–0.6% for nad2, and 0–0.9% for nad6. Variation was 0–0.5%, 0.1–0.8%, 0–0.7% for corresponding genes for schistosome samples from mainland China. For worms in Japan, genetic variations were 0–0.2%, 0.1–0.2% and 0 for the three genes, respectively. Sequence variations were 0–1.0%, 0–1.8% and 0–1.1% for cytb, nad2 and nad6, respectively, among schistosome isolates from different geographical strains in the Philippines, Japan and China. Of the three countries, lowest sequence variations were found between isolates from mainland China and the Philippines and highest were detected between Japan and the Philippines in three mtDNA genes. Phylogenetic analyses based on the combined sequences of cytb, nad2 and nad6 revealed that all isolates in the Philippines clustered together sistered to samples from Yunnan and Zhejiang provinces in China, while isolates from Yamanashi in Japan were in a solitary clade. These results demonstrated the usefulness of the combined three mtDNA sequences for studying genetic diversity and population structure among S. japonicum isolates from the Philippines, China and Japan.

Practical identification of eight medically importantTrichosporonspecies by reverse line blot hybridization (RLB) assay and rolling circle amplification (RCA)

We developed a reverse line blot (RLB) hybridization-, and rolling circle amplification (RCA)-based assays for the identification of Trichoporon species and evaluated them with 48 isolates that had been previously recognized as belonging to eight species (Trichosporon asahii, T. cutaneum, T. dermatis, T. domesticum, T. inkin, T. japonicum, T. jirovecii, and T. laibachii). Results were compared to those obtained with DNA sequencing of three rRNA gene loci, i.e., the internal transcribed spacer (ITS) region, D1/D2 domain of the 28S rRNA gene and intergenic spacer 1 (IGS1) region. Using species-specific, or group-specific probes targeted at the ITS region and the D1/D2 domain, the RLB assay permitted accurate species identification of all 48 isolates with 100% specificity. Species-specific RLB probes correctly assigned 45/48 (94%) of the isolates (six species) with the exception of T. dermatis and T. japonicum isolates which were not targeted by the assay. Identification of T. dermatis relied on a positive hybridization result with the group-specific probe hybridizing with T. dermatis and T. jirovecii and the absence of a signal with the T. jirovecii-specific probe. T. japonicum strains were first assigned to the T. asahii-T. japonicum group by hybridization with the two species group-specific probe and then as T. japonicum by the absence of signal with a T. asahii-specific probe. Twelve species-specific RCA probes targeting the eight species studied detected templates of all 48 Trichosporon isolates and an artificial template of T. asteroides, all with good specificity. Both RLB and RCA are potential alternatives to DNA sequencing for the identification of Trichosporon species. The RLB approach is suited for the batched simultaneous analysis of large numbers of isolates, while RCA is more appropriate for the immediate study of single isolates. Comparative costs are US$7 and US$2 per assay for the RLB and RCA methods, respectively.

Retrotransposon‐microsatellite amplified polymorphism, an electrophoretic approach for studying genetic variability among Schistosoma japonicum geographical isolates

In the present study, retrotransposon-microsatellite amplified polymorphism (REMAP) was used to examine genetic variability among Schistosoma japonicum isolates from different endemic provinces in mainland China, using S. japonicum from Japan and the Philippines for comparison. Of the 50 primer combinations screened, eight produced highly reproducible REMAP fragments. Using these primers, 190 distinct DNA fragments were generated in total, of which 147 (77.37%) were polymorphic, indicating considerable genetic variation among the 43 S. japonicum isolates examined. The percentage of polymorphic bands (PPB) among S. japonicum isolates from mainland China, Japan, and the Philippines was 77.37%; PPB values of 18.42% and 53.68% were found among isolates from southwestern (SW) China and the lower Yangtze/Zhejiang province in eastern (E) China, respectively. Based on REMAP profiles, unweighted pair-group method with arithmetic averages (UPGMA) dendrogram analysis revealed that all of the S. japonicum samples grouped into three distinct clusters: parasites from mainland China, Japan, and the Philippines were clustered in each individual clade. Within the mainland China cluster, SW China isolates (from Sichuan and Yunnan provinces) grouped together, whereas worms from E China (Zhejiang, Anhui, Jiangxi, Jiangsu, Hunan, and Hubei provinces) grouped together. These results demonstrated that the REMAP marker system provides a reliable electrophoretic technique for studying genetic diversity and population structures of S. japonicum isolates from mainland China, and could be applied to other pathogens of human and animal health significance.

The second transcribed spacer rDNA sequence: an effective genetic marker for inter-species phylogenetic analysis of trematodes in the order Strigeata

In the present study, the second nuclear internal transcribed spacer (ITS-2) rDNA of Schistosoma japonicum isolates in mainland China was amplified, sequenced, and assessed for inferring the intra- and inter-species phylogenetic relationships of trematodes in the order Strigeata. The fragment containing ITS-2 rDNA was obtained from 24 S. japonicum isolates from eight epidemic provinces in mainland China. The length polymorphisms were observed among these ITS-2 rDNA sequences, ranging from 343 to 346 bp, and the intra- and inter-population variations in ITS-2 sequence were 0.0-2.1% among S. japonicum isolates in China. Phylogenetic analyses using the maximum parsimony and maximum likelihood methods revealed that the ITS-2 rDNA sequence is not a suitable marker for studying inter- and intra-population variation in S. japonicum. However, phylogenetic analysis of trematodes in the order Strigeata indicated that the ITS-2 rDNA sequence provides an effective molecular marker for studying inter-species phylogenetic relationships among trematodes in this order.

A cleaved amplified polymorphic sequence (CAPS) method for the identification of geographical isolates of Schistosoma japonicum in China.

Schistosomiasis japonica, caused by the blood fluke Schistosoma japonicum, is a severe parasitic zoonosis, causing significant morbidity, mortality and considerable economic losses in south-east Asia, particularly in mainland China (Zhou et al., 2005; Bergquist et al., 2008; Zhou et al., 2008; Li et al., 2010). Although there have been significant efforts to control schistosomiasis in China, this disease appears to be re-emerging due to climate changes and human activities (Wang et al., 2009). Thus far, schistosomiasis is still endemic in seven provinces (Yunnan, Sichuan, Anhui, Hubei, Jiangxi, Jiangsu and Hunan provinces) of China (Ross et al., 2001), and the impact of this communicable disease in China is almost equal to that of HIV/AIDS and tuberculosis (Engels et al., 2005). In previous studies, genetic variation among S. japonicum populations from different endemic provinces in China has been detected using a variety of genetic markers (Bogh et al., 1999; Sorensen et al., 1999; Zhu et al., 1999; Shrivastava et al., 2005; Zhao et al., 2009a; Zhao et al., 2009b; Zhao et al., 2009c). However, these markers and the detected genetic variability have not been utilized for the practical identification and differentiation of S. japonicum geographical isolates in China. The economic reform and the deterioration of ecological environment, flash floods, landslides and the mobility of human population appear to be having an impact on the transmission of S. japonicum (Li et al., 2000; Seto et al., 2008). Consequently, it is important to be able to identify different genetic variants of S. japonicum in China. Various methods for the analysis of genetic variation have been developed, including single-strand conformation polymorphism (Simoes et al., 2007), denaturing high-performance liquid chromatography (Nickerson et al., 2000), gene chips (Schmalzing et al., 2000), TaqMan probe (Shi et al., 1999) and pyrosequencing technology (Ahmadian et al., 2000). However, such techniques can be time-consuming and/or require detection instruments or labelled oligonucleotides. In contrast, the cleaved amplified polymorphism sequence (CAPS) technique is a simple and effective method to allow the rapid detection of single nucleotide polymorphisms (SNPs) (Neff et al., 1998; Komori and Nitta, 2005). CAPS is based on the PCR-based amplification of targeted genes and subsequent digestion of amplicons using restriction enzymes. The digested PCR products are separated by agarose gel electrophoresis. CAPS generates the same type of data as traditional restriction fragment length polymorphism analysis, but significantly reduces the amount of purified DNA required for analysis and time-consuming steps. This method can detect both homozygous and heterozygous individuals (Weiland and Yu, 2003; Komori and Nitta, 2005). CAPS has been successfully used to study genetic diversity in plants, such as Arabidopsis thaliana (Hardtke et al., 1996; Barth et al., 2002), Cryptomeria japonica (Tsumura and Tomaru, 1999; Tsumura et al., 1999) and Pisum sativum L. (Konovalov et al., 2009), but has seldom been used to study variation in parasites (Gandhi et al., 2009). The aims of the present study were to identify SNP sites specific for geographical isolates of S. japonicum based on results of previous studies. Using these SNPs, the CAPS technique was developed and used to identify and differentiate S. japonicum isolates from Yunnan province and those from other endemic provinces.

IRAP: An efficient retrotransposon-based electrophoretic technique for studying genetic variability among geographical isolates of Schistosoma japonicum

In the present study, a inter-retrotransposon-amplified polymorphism (IRAP) technique, based on retrotransposons, was used to examine genetic variability among Schistosoma japonicum isolates from different provinces in mainland China. Of the 15 primers screened, 5 produced highly reproducible IRAP patterns. Using these primers, 54 discernible DNA fragments were generated with 40 (74.07%) being polymorphic, indicating considerable genetic variation among the examined S. japonicum isolates. The primer LTR-11 was found to be able to differentiate male and female parasites, producing one constant specific band for female S. japonicum isolates. The percentages of polymorphic bands (PPB) among all parasites, among isolates from mountainous provinces and among those from the lake/marshland areas were 74.07, 48.15, and 66.67%, respectively. UPGMA analysis revealed that the IRAP profiles could group S. japonicum isolates in mainland China into two clades (mountainous and lake/marshland types), and samples from the same geographical origins clustered together. These results demonstrated that the IRAP technique is suitable for studying genetic diversity and population structures, and also provides an effective technique for studying sex differentiation of S. japonicum.

Electrophoretic detection of genetic variability among Schistosoma japonicum isolates by sequence-related amplified polymorphism

In the present study, sequence-related amplification polymorphism (SRAP) was utilized to study the genetic variability among Schistosoma japonicum isolates from different provinces in China, using Schistosoma mansoni from Puerto Rico for comparison. Five out of ten tested SRAP primer combinations displayed significant polymorphisms among S. japonicum isolates from China, namely ME2/EM1, ME4/EM1, ME4/EM6, ME5/EM4 and ME5/EM5. Analysis of the 61 S. japonicum samples from China with five SRAP primer combinations identified a total of 83 reproducible polymorphic fragments. The number of fragments using each primer combination ranged from 14 to 19, with an average of 16 polymorphic bands per primer pair, and the size of fragment ranged approximately from 100 to 1000 bp. Representative-specific SRAP fragments were excised from the gels, and confirmed by PCR amplification of genomic DNA using primers designed and based on the sequences of these SRAP fragments. Based on SRAP profiles, unweighted pair-group method with arithmetic averages (UPGMA) dendrogram was constructed. UPGMA clustering algorithm categorized S. japonicum isolates from China into nine clades and two lineages (representing the mountainous and lake/marshland regions). These results indicate the usefulness of the SRAP technique for revealing genetic variability among S. japonicum isolates from China, and the SRAP technique should be applicable to other living organisms.

Variability in intron sequences of housekeeping and antigen-coding genes among Schistosoma japonicum isolates in mainland China

The accurate characterization of Schistosoma japonicum has important implications for analyzing genetic variation and would provide basic data for disease control. Previous studies using proteins, coding sequences, and especially antigen-coding genes showed lower genetic variation among S. japonicum isolates from mainland China. Therefore, the present study focused on variations in intron sequences of housekeeping and antigen-coding genes, which may be more informative for genetic analysis. We compared sequence variation between introns of two housekeeping genes and two antigen-coding genes. All 4 genes were polymorphic among all the S. japonicum isolates in mainland China, with 103, 158, 47, and 19 polymorphic (segregating) sites per kilobase in intron sequences of Actin, FBPA, 22.6 kDa antigen and GST-26, respectively. Introns of housekeeping genes were slightly more polymorphic than coding and non-coding regions of antigen-coding genes examined in the present study within or among lake/marshland and mountainous types. Phylogenetic analysis based on sequences of single gene or combined sequences of multiple genes showed no specific clustering comprising parasites from single geographical or endemic regions. These results demonstrated that introns of housekeeping and antigen-coding genes were polymorphic, but the intron sequences examined in the present study were not suitable markers for examining genetic relationship among different isolates from endemic regions in mainland China.

Symbiotic potential, competitiveness and compatibility of indigenous Bradyrhizobium japonicum isolates to three soybean genotypes of two distinct agro-climatic regions of Rajasthan, India

In the current study, we recovered sixteen bradyrhizobial isolates from root nodules of two soybean genotypes (JS 335 and PK 472) grown in two distinct agro-climatic conditions (Bundi and Udaipur) of Rajasthan, India. Symbiotic effectiveness of these isolates was evaluated under greenhouse conditions. On the basis of statistical analysis of data (ANOVA followed by LSD P ⩽ 0.05), four effective isolates namely BJ335-1, BPK-3, BPK-5 and UJ335-1 were screened out from the greenhouse experiment. The compatibility to three soybean genotypes, and the competitive ability with other field population of rhizobia, of these four isolates was further determined by conducting field trial. Results demonstrated significant variation in the symbiotic potential of tested isolates with respect to different soybean genotypes. Response of soybean genotype JS 335 towards inoculation was relatively better suggesting its suitability in the Haroti region of Rajasthan. Moreover, BJ 335-1 and BPK-3 isolates were found to be highly efficient as they significantly improved the nodulation, plant growth and seed yield. Possible factors responsible for variable response of bradyrhizobial isolates towards inoculation in three soybean genotypes are discussed. Further, the inoculants production of effective isolates at large scale and their multilocational trials are required to check their suitability for the other agro-climatic conditions.

Combined mitochondrial 16S and 12S rDNA sequences: an effective genetic marker for inter-species phylogenetic analysis of zoonotic trematodes

The present study studied the genetic variation among Schistosoma japonicum isolates from different endemic regions in mainland China and examined the phylogenetic relationships of zoonotic trematodes using the combined mitochondrial 16S and 12S ribosomal DNA sequences. The fragments of 16S and 12S rDNA were amplified from 22 S. japonicum isolates, and sequenced, and the relevant sequences of other nine trematode species belonging to six genera in four families were downloaded from GenBank, and their phylogenetic relationships were re-constructed by unweighted pair-group method with arithmetic averages analyses using the combined 16S and 12S rDNA sequences, with Trichinella spiralis as outgroup. The results showed that the partial sequences of mitochondrial 16S and 12S rDNA of S. japonicum were 757 and 797 bp, respectively, and they were quite conserved among the S. japonicum isolates. Phylogenetic analysis revealed that the combined 16S and 12S rDNA sequences were not able to distinguish S. japonicum isolates in mountainous areas from those in lake/marshland areas in mainland China. However, the combined sequences could distinguish different species of zoonotic trematodes. Therefore, the combined mitochondrial 16S and 12S rDNA sequences provide an effective molecular marker for the inter-species phylogenetic analysis and differential identification of zoonotic trematodes.

An effective sequence characterized amplified region‐PCR method derived from restriction site‐amplified polymorphism for the identification of femaleSchistosoma japonicumof zoonotic significance

In the present study, restriction site-amplified polymorphism (RSAP) markers were used to examine the genetic variability of Schistosoma japonicum isolates from different endemic provinces in mainland China. Of the 45 pairs of primers screened, 10 RSAP markers showed a clear banding pattern with good resolution; however, only six exhibited a polymorphism among different isolates. Among six RSAP markers, one pair of primers (R8+R10) was able to differentiate male and female parasites, and amplified one constant specific band for female S. japonicum isolates. The specific band was recovered, re-amplified and sequenced, and a sequence of 162 bp was obtained. Based on this sequence, a pair of specific primers was designed and used to develop sequence characterized amplified region (SCAR)-PCR assay for identification and differentiation of female S. japonicum isolates. The SCAR-PCR assay allowed the specific identification of female S. japonicum, with no amplicons being amplified from male S. japonicum, Fasciola hepatica, Clonorchis sinensis, S. mansoni (male and female parasite). DNA sequencing confirmed the identity of the amplified products. The minimum amount of DNA detectable using SCAR-PCR assay was 0.3 ng for female S. japonicum. The SCAR-PCR was able to differentiate effectively the male and female S. japonicum worms collected from 12 geographical origins in eight endemic provinces, the gender of which was known based on the morphological and biological features. These results showed that SCAR-PCR provides an effective tool for the sex differentiation studies of S. japonicum, identification of female S. japonicum, diagnosis and epidemiological survey of S. japonicum infections in animals and human.