Project description:Background: Studying genomic variation in rapidly evolving pathogens potentially enables definition of genes supporting their “core biology” present, functional and expressed by all strains or “flexible biology”, varying between strains. Genes supporting flexible biology may be considered to be “accessory”, whilst the “core” gene set is likely to be important for common features of a pathogen species biology, including virulence on all host genotypes. The wheat-pathogenic fungus Zymoseptoria tritici represents one of the most rapidly evolving threats to global food security and was the focus of this study. Results:We constructed a pangenome of 18 European field isolates, with 12 also subjected to RNAseq transcription profiling during infection. Combining this data, we predicted a “core” gene set comprising 9807 sequences which were; (1) present in all isolates; (2) lacking inactivating polymorphisms ; and (3) expressed by all isolates. A large accessory genome, consisting of 45% of the total genes was also defined. We classified genetic and genomic polymorphism at both chromosomal and individual gene scales. Proteins required for essential functions including virulence, had lower-than average sequence variability amongst core genes. Both core and accessory genomes encoded many small, secreted candidate effector proteins that likely interact with plant immunity. Viral vector-mediated transient in planta overexpression of 88 candidates failed to identify any which induced leaf necrosis characteristic of disease. However, functional complementation of a non-pathogenic deletion mutant lacking five core genes, demonstrated that full virulence was restored by re-introduction of the single gene exhibiting least sequence polymorphism and highest expression. Conclusions:These data support the combined use of pangenomics and transcriptomics for defining genes which represent core, and potentially exploitable, weaknesses in rapidly evolving pathogens.

Project description:Female Aedes aegypti mosquitoes impose a severe global public health burden as primary vectors of multiple viral and parasitic pathogens. Under optimal environmental conditions, Aedes aegypti females have access to human hosts that provide blood proteins for egg development, conspecific males that provide sperm for fertilization, and freshwater that serves as an egg-laying substrate suitable for offspring survival. As global temperatures rise, Aedes aegypti females are faced with climate challenges, like intense droughts and intermittent precipitation, which create unpredictable and suboptimal conditions for the egg-laying step of their reproductive cycle. Aedes aegypti mosquitoes nonetheless show remarkable reproductive resilience, but how they achieve this is unknown. Here we show that under drought-like conditions simulated in the laboratory, mated, blood-fed Aedes aegypti females carrying mature eggs retain them in their ovaries for extended periods, while maintaining the viability of these eggs until they can be deposited in freshwater. Using transcriptomic and proteomic profiling of Aedes aegypti ovaries, we identify two previously uncharacterized genes – here named tweedledee and tweedledum – that show ovary-enriched, temporally-restricted expression during egg retention. These genes are mosquito-specific, linked within a syntenic locus, and rapidly evolving under positive selection, raising the possibility that they serve an adaptive function. Using loss-of-function mutagenesis to disrupt both genes, we show that, tweedledee and tweedledum, which encode secreted proteins, are specifically required for extended retention of viable eggs, such as during intermittent precipitation or drought. These results highlight an elegant example of taxon-restricted genes at the heart of an important adaptation that equips Aedes aegypti females with “insurance” to, when contextually appropriate, flexibly extend their reproductive sequence without losing reproductive capacity, thus allowing this species to exploit diverse and unpredictable/chaotic/changing habitats.

Project description:Female Aedes aegypti mosquitoes impose a severe global public health burden as primary vectors of multiple viral and parasitic pathogens. Under optimal environmental conditions, Aedes aegypti females have access to human hosts that provide blood proteins for egg development, conspecific males that provide sperm for fertilization, and freshwater that serves as an egg-laying substrate suitable for offspring survival. As global temperatures rise, Aedes aegypti females are faced with climate challenges, like intense droughts and intermittent precipitation, which create unpredictable and suboptimal conditions for the egg-laying step of their reproductive cycle. Aedes aegypti mosquitoes nonetheless show remarkable reproductive resilience, but how they achieve this is unknown. Here we show that under drought-like conditions simulated in the laboratory, mated, blood-fed Aedes aegypti females carrying mature eggs retain them in their ovaries for extended periods, while maintaining the viability of these eggs until they can be deposited in freshwater. Using transcriptomic and proteomic profiling of Aedes aegypti ovaries, we identify two previously uncharacterized genes – here named tweedledee and tweedledum – that show ovary-enriched, temporally-restricted expression during egg retention. These genes are mosquito-specific, linked within a syntenic locus, and rapidly evolving under positive selection, raising the possibility that they serve an adaptive function. Using loss-of-function mutagenesis to disrupt both genes, we show that, tweedledee and tweedledum, which encode secreted proteins, are specifically required for extended retention of viable eggs, such as during intermittent precipitation or drought. These results highlight an elegant example of taxon-restricted genes at the heart of an important adaptation that equips Aedes aegypti females with “insurance” to, when contextually appropriate, flexibly extend their reproductive sequence without losing reproductive capacity, thus allowing this species to exploit diverse and unpredictable habitats.

Project description:Following the removal of implanted mammary tumors, nude mice develop multiple-organ metastases at late stage. The metastases may originate from the primary tumors before the resection surgery, or alternatively, from some established metastases. By multiple approaches, we have proved that bone environment could invigorate cancer cells for further dissemination. this study aims to examine if metastatic dissemination from bone to other sites occurs in natural setting of metastatic spread. We herein apply the rapidly evolving barcode system using homing guide RNA/Cas9 to trace the metastases formation in mouse. hgRNA/Cas9 is a self-targeting Crispr system which allows the mutation occurs in the DNA sequence of guide RNA. Tumor cells wer labelled with doxycycline inducible evolving barcoding system. Upon doxycycline treatment the DNA sequence of hgRNA accumulate mutations with time. The diversity of barcodes in each lesion can infer the timeing of seeding while the mutation patterns of barcodes suggest the phylogenetic correlation of metastases. Several findings were made on this study. First, at the terminal stage, multi-organ metastases are not genetically grouped according to sites of metastases. Nonnegative Matrix Factorization (NMF) analysis of mutant barcodes suggested the early disseminated metastases, which have highest level of Shannon entropy, were featured with a common cluster of mutant barcodes irrespective of their locations. Second, most metastases are potentially multiclonal as indicated by multiple clusters of independent mutant barcodes. Third, when we use Shannon entropy as an index of metastasis age , putative parent-child relationship between metastases with unique mutant barcodes clearly exemplified secondary metastatic seeding from bone to other organs. Finally, we did not observe a clear correlation between tumor burden and Shannon entropy across different metastases, suggesting that putative parental metastases might remain small after seeding further metastases.

Dataset Information

Antiviral function and viral antagonism of the rapidly evolving dynein activating adapter NINL

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