The parasitic nematodes Ascaris lumbricoides and A. suum are of great public health and economic significance, and the two taxa were proposed to represent a single species. miRNAs are known with functions of gene regulations at post-transcriptional level. We herein compared the miRNA profiles of A. lumbricoides and A. suum female adults by Solexa deep sequencing combined with bioinformatics analysis and stem-loop real-time PCR. Using the A. suum genome as the reference genome, we obtained 171 and 494 miRNA candidates from A. lumbricoides and A. suum, respectively. Among which, 74 miRNAs were shared between the two taxa, 97 and 420 miRNAs were A. lumbricoides and A. suum specific. Target and function prediction revealed a significant set of targets which are related to ovarian message protein, vitellogenin and chondroitin proteoglycan of the two nematodes. Enrichment analysis revealed that the percentages of most predicted functions of the miRNA targets were similar, with some taxon specific or taxon enhanced functions, such as different target numbers, specific functions (NADH dehydrogenase and electron carrier functions), etc. This study characterized comparatively the miRNAs of adult A. lumbricoides and A. suum, and the findings provide additional evidence that A. lumbricoides and A. suum represent a single species. Due to the fast evolution nature of miRNAs and the different parasitic living conditions of humans and pigs, the phenomenon above might indicate a fast evolution of miRNAs of Ascaris in humans and pigs.

Background: Gametocyte proteins ofEimeria(E.) spp. are important components of the oocyst wall and some have been used to develop transmission-blocking vaccines against avian coccidiosis.Methods: Total RNA isolated fromE. necatrixgametocytes was utilized as templates for RT-PCR amplification and sequencing of cDNA encoding a gametocyte protein using gene-specific primers. The cDNA was cloned into the bacterial expression vector pET28a(+) and expressed inE. coliBL21 cells. The antigenicity of the recombinant gametocyte protein and its localization in differentE. necatrixlife-cycle stages were determined by western blot and indirect immunofluorescence analyses, respectively.Results: A 731-nucleotide sequence of cDNA [GenBank: KF649255] ofE. necatrixhad 97.7% identity to that of Etgam22ofE. tenella. The cDNA ORF encoded a 186-amino acid protein containing a histidine-proline-rich region. The recombinant gametocyte protein (rEnGAM22) was predominately expressed in the insoluble inclusion body and recognized by antiserum from chickens immunized with oocysts ofE. necatrix,E. maximaandE. tenella. A specific antibody to the rEnGAM22 protein recognized the wall-forming bodies in macrogametocytes and the walls of oocysts and sporocysts.Conclusions: The gene cloned fromE. necatrixgametocytes is an ortholog to Etgam22ofE. tenellaand presents a potential target for future recombinant subunit vaccines against coccidiosis.

Eimeria is a common genus of apicomplexan parasites that infect diverse vertebrates, most notably poultry, causing serious disease and economic losses. Eimeria species have complex life-cycles consisting of three developmental stages. However, the molecular basis of the Eimeria reproductive mode switch remains an enigma. Total RNA extracted from second- (MZ-2) and third-generation merozoites (MZ-3) of Eimeria necatrix was subjected to transcriptome analysis using RNA sequencing (RNA-seq) followed by qRT-PCR validation. A total of 6977 and 6901 unigenes were obtained from MZ-2 and MZ-3, respectively. Approximately 2053 genes were differentially expressed genes (DEGs) between MZ-2 and MZ-3. Compared with MZ-2, 837 genes were upregulated and 1216 genes were downregulated in MZ-3. Approximately 95 genes in MZ-2 and 48 genes in MZ-3 were further identified to have stage-specific expression. Gene ontology category and KEGG analysis suggested that 216 upregulated genes in MZ-2 were annotated by 70 GO assignments, 242 upregulated genes were associated with 188 signal pathways, while 321 upregulated genes in MZ-3 were annotated by 56 GO assignments, 322 upregulated genes were associated with 168 signal pathways. The molecular functions of upregulated genes in MZ-2 were mainly enriched for protein degradation and amino acid metabolism. The molecular functions of upregulated genes in MZ-3 were mainly enriched for transcriptional activity, cell proliferation and cell differentiation. To the best of our knowledge, this is the first RNA-seq data study of the MZ-2 and MZ-3 stages of E. necatrix; it demonstrates a high number of differentially expressed genes between the MZ-2 and MZ-3 of E. necatrix. This study forms a basis for deciphering the molecular mechanisms underlying the shift from the second to third generation schizogony in Eimeria. It also provides valuable resources for future studies on Eimeria, and provides insight into the understanding of reproductive mode plasticity in different Eimeria species.