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Patterns of transcriptome divergence in the male accessory gland of two closely related species of field crickets.

ABSTRACT: One of the central questions in evolutionary genetics is how much of the genome is involved in the early stages of divergence between populations, causing them to be reproductively isolated. In this article, we investigate genomic differentiation in a pair of closely related field crickets (Gryllus firmus and G. pennsylvanicus). These two species are the result of allopatric divergence and now interact along an extensive hybrid zone in eastern North America. Genes encoding seminal fluid proteins (SFPs) are often divergent between species, and it has been hypothesized that these proteins may play a key role in the origin and maintenance of reproductive isolation between diverging lineages. Hence, we chose to scan the accessory gland transcriptome to enable direct comparisons of differentiation for genes known to encode SFPs with differentiation in a much larger set of genes expressed in the same tissue. We have characterized differences in allele frequency between two populations for >6000 SNPs and >26,000 contigs. About 10% of all SNPs showed nearly fixed differences between the two species. Genes encoding SFPs did not have significantly elevated numbers of fixed SNPs per contig, nor did they seem to show larger differences than expected in their average allele frequencies. The distribution of allele frequency differences across the transcriptome is distinctly bimodal, but the relatively high proportion of fixed SNPs does not necessarily imply "ancient" divergence between these two lineages. Further studies of linkage disequilibrium and introgression across the hybrid zone are needed to direct our attention to those genome regions that are important for reproductive isolation.

SUBMITTER: Andres JA

PROVIDER: S-EPMC3567739 | biostudies-literature | 2013 Feb

REPOSITORIES: biostudies-literature

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Patterns of transcriptome divergence in the male accessory gland of two closely related species of field crickets.

Andrés Jose A JA Larson Erica L EL Bogdanowicz Steven M SM Harrison Richard G RG

Genetics 20121119 2

One of the central questions in evolutionary genetics is how much of the genome is involved in the early stages of divergence between populations, causing them to be reproductively isolated. In this article, we investigate genomic differentiation in a pair of closely related field crickets (Gryllus firmus and G. pennsylvanicus). These two species are the result of allopatric divergence and now interact along an extensive hybrid zone in eastern North America. Genes encoding seminal fluid proteins ...[more]

PMID: 23172857

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Project description:Ticks are important vectors of numerous human diseases and animal diseases. Feeding stimulates spermatogenesis, mating and insemination of male factors that trigger female reproduction. The physiology of male reproduction and its regulation of female development are essentially a black box. Several transcriptomes have catalogued expression of tick genes in the salivary glands, synganglion and midgut but no comprehensive investigation has addressed male reproduction and mating. Consequently, a new global approach using transcriptomics, proteomics, and quantitative gene expression is needed to understand male reproduction and stimulation of female reproduction.This first transcriptome to the reproductive biology of fed male ticks, Dermacentor variabilis, was obtained by 454 pyrosequencing (563,093 reads, 12,804 contigs). Gene Ontology (Biological Processes level III) recognized 3,866 transcripts in 73 different categories; spermiogenesis; spermatogenesis; peptidases, lipases and hydrolases; oxidative and environmental stress; immune defense; and protein binding. Reproduction-associated genes included serine/threonine kinase, metalloendoproteinases, ferritins, serine proteases, trypsin, cysteine proteases, serpins, a cystatin, GPCR and others. qRT-PCR showed significant upregulation from unfed versus fed adult male reproductive organs of zinc metalloprotease, astacin metalloprotease and serine protease, enzymes important in spermiogenesis and mating activity in insects, as well as a GPCR with the greatest similarity to a SIFamide receptor known to be important in regulating courtship behavior in Drosophila. Proteomics on these organs and the spermatophore by tryptic digestion/Liquid chromatography/Mass spectrometry/Mass spectrometry (LC/MS/MS) demonstrated expression of many of the same messages found by 454 sequencing, supporting their identification, and revealed differences in protein distribution in the reproductive system versus the spermatophore. We found Efα but no EF β in the transcriptome and neither of these proteins in the spermatophore. Thus, the previously described model for male regulation of female reproduction may not apply to other ticks. A new paradigm is needed to explain male stimulation of female tick reproduction.

Project description:BackgroundThe ultrasound (US) evaluation of the male sex accessory gland inflammation (MAGI) helps the clinicians to understand the severity of this condition, allowing them to distinguish the uncomplicated form (prostatitis) from the complicated ones (prostate-vesiculitis and prostate-vesiculitis-epididymitis), as well as the unilateral from the bilateral forms, the fibrosclerotic and the hypertrophic-congestive form.ObjectiveThis retrospective study aimed to evaluate the US features of MAGI patients with active symptoms compared to patients without sexual, voiding, and ejaculatory dysfunction.Materials/methodsTo achieve this aim, an analysis of the prevalence of MAGI US criteria was carried out on a very large series of over 500 patients diagnosed with MAGI classified according to the different symptom profile evaluated through a dedicated questionnaire (previously conceived and published by our group) arbitrarily named "structured interview about MAGI" (SI-MAGI) for sexual, voiding, and ejaculatory disorders reported by these patients.ResultsThe results of this study revealed that US criteria most frequently detected in patients with severe urinary symptoms were the presence of areas of high echogenicity (almost exclusively in the periurethral prostatic zone) together with the presence of single or multiple areas of acinar ectasia of the prostate. The presence of seminal vesicles with polycyclic areas within the glandular lumen separated by hyperechoic septa represented US criterion most frequently detected in patients with severe spontaneous or post-ejaculate pain. Finally, US criterion most frequently detected in patients with severe sexual dysfunction was the dilation of the periprostatic venous plexus, suggesting the hypothesis of a possible alternative therapeutic approach.ConclusionThe data of the present study suggest that symptoms may associate with US signs in patients with MAGI. Also, specific US signs may associate with specific symptoms. Further studies are needed to understand whether patients with specific US signs may in turn benefit from a personalized therapeutic choice.

Dataset Information

Patterns of transcriptome divergence in the male accessory gland of two closely related species of field crickets.

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Patterns of transcriptome divergence in the male accessory gland of two closely related species of field crickets.

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