Experimental genetic crosses in tsetse flies of the livestock pathogen Trypanosoma congolense savannah
Abstract Background In tropical Africa animal trypanosomiasis is a disease that has severe impacts on the health and productivity of livestock in tsetse fly-infested regions. Trypanosoma congolense savannah (TCS) is one of the main causative agents and is widely distributed across the sub-Saharan ts...
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| Format: | Article |
| Language: | English |
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BMC
2024-01-01
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| Series: | Parasites & Vectors |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s13071-023-06105-4 |
| _version_ | 1827388710994313216 |
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| author | Lori Peacock Chris Kay Mick Bailey Wendy Gibson |
| author_facet | Lori Peacock Chris Kay Mick Bailey Wendy Gibson |
| author_sort | Lori Peacock |
| collection | DOAJ |
| description | Abstract Background In tropical Africa animal trypanosomiasis is a disease that has severe impacts on the health and productivity of livestock in tsetse fly-infested regions. Trypanosoma congolense savannah (TCS) is one of the main causative agents and is widely distributed across the sub-Saharan tsetse belt. Population genetics analysis has shown that TCS is genetically heterogeneous and there is evidence for genetic exchange, but to date Trypanosoma brucei is the only tsetse-transmitted trypanosome with experimentally proven capability to undergo sexual reproduction, with meiosis and production of haploid gametes. In T. brucei sex occurs in the fly salivary glands, so by analogy, sex in TCS should occur in the proboscis, where the corresponding portion of the developmental cycle takes place. Here we test this prediction using genetically modified red and green fluorescent clones of TCS. Methods Three fly-transmissible strains of TCS were transfected with genes for red or green fluorescent protein, linked to a gene for resistance to the antibiotic hygromycin, and experimental crosses were set up by co-transmitting red and green fluorescent lines in different combinations via tsetse flies, Glossina pallidipes. To test whether sex occurred in vitro, co-cultures of attached epimastigotes of one red and one green fluorescent TCS strain were set up and sampled at intervals for 28 days. Results All interclonal crosses of genetically modified trypanosomes produced hybrids containing both red and green fluorescent proteins, but yellow fluorescent hybrids were only present among trypanosomes from the fly proboscis, not from the midgut or proventriculus. It was not possible to identify the precise life cycle stage that undergoes mating, but it is probably attached epimastigotes in the food canal of the proboscis. Yellow hybrids were seen as early as 14 days post-infection. One intraclonal cross in tsetse and in vitro co-cultures of epimastigotes also produced yellow hybrids in small numbers. The hybrid nature of the yellow fluorescent trypanosomes observed was not confirmed by genetic analysis. Conclusions Despite absence of genetic characterisation of hybrid trypanosomes, the fact that these were produced only in the proboscis and in several independent crosses suggests that they are products of mating rather than cell fusion. The three-way strain compatibility observed is similar to that demonstrated previously for T. brucei, indicating that a simple two mating type system does not apply for either trypanosome species. Graphical Abstract |
| first_indexed | 2024-03-08T16:23:51Z |
| format | Article |
| id | doaj.art-ed26634ae2224e9e8abb5eae7bd8961b |
| institution | Directory Open Access Journal |
| issn | 1756-3305 |
| language | English |
| last_indexed | 2024-03-08T16:23:51Z |
| publishDate | 2024-01-01 |
| publisher | BMC |
| record_format | Article |
| series | Parasites & Vectors |
| spelling | doaj.art-ed26634ae2224e9e8abb5eae7bd8961b2024-01-07T12:13:59ZengBMCParasites & Vectors1756-33052024-01-0117111310.1186/s13071-023-06105-4Experimental genetic crosses in tsetse flies of the livestock pathogen Trypanosoma congolense savannahLori Peacock0Chris Kay1Mick Bailey2Wendy Gibson3School of Biological Sciences, University of BristolSchool of Biological Sciences, University of BristolBristol Veterinary School, University of BristolSchool of Biological Sciences, University of BristolAbstract Background In tropical Africa animal trypanosomiasis is a disease that has severe impacts on the health and productivity of livestock in tsetse fly-infested regions. Trypanosoma congolense savannah (TCS) is one of the main causative agents and is widely distributed across the sub-Saharan tsetse belt. Population genetics analysis has shown that TCS is genetically heterogeneous and there is evidence for genetic exchange, but to date Trypanosoma brucei is the only tsetse-transmitted trypanosome with experimentally proven capability to undergo sexual reproduction, with meiosis and production of haploid gametes. In T. brucei sex occurs in the fly salivary glands, so by analogy, sex in TCS should occur in the proboscis, where the corresponding portion of the developmental cycle takes place. Here we test this prediction using genetically modified red and green fluorescent clones of TCS. Methods Three fly-transmissible strains of TCS were transfected with genes for red or green fluorescent protein, linked to a gene for resistance to the antibiotic hygromycin, and experimental crosses were set up by co-transmitting red and green fluorescent lines in different combinations via tsetse flies, Glossina pallidipes. To test whether sex occurred in vitro, co-cultures of attached epimastigotes of one red and one green fluorescent TCS strain were set up and sampled at intervals for 28 days. Results All interclonal crosses of genetically modified trypanosomes produced hybrids containing both red and green fluorescent proteins, but yellow fluorescent hybrids were only present among trypanosomes from the fly proboscis, not from the midgut or proventriculus. It was not possible to identify the precise life cycle stage that undergoes mating, but it is probably attached epimastigotes in the food canal of the proboscis. Yellow hybrids were seen as early as 14 days post-infection. One intraclonal cross in tsetse and in vitro co-cultures of epimastigotes also produced yellow hybrids in small numbers. The hybrid nature of the yellow fluorescent trypanosomes observed was not confirmed by genetic analysis. Conclusions Despite absence of genetic characterisation of hybrid trypanosomes, the fact that these were produced only in the proboscis and in several independent crosses suggests that they are products of mating rather than cell fusion. The three-way strain compatibility observed is similar to that demonstrated previously for T. brucei, indicating that a simple two mating type system does not apply for either trypanosome species. Graphical Abstracthttps://doi.org/10.1186/s13071-023-06105-4Trypanosoma congolenseSexual reproductionTsetse flyMatingGreen fluorescent proteinRed fluorescent protein |
| spellingShingle | Lori Peacock Chris Kay Mick Bailey Wendy Gibson Experimental genetic crosses in tsetse flies of the livestock pathogen Trypanosoma congolense savannah Parasites & Vectors Trypanosoma congolense Sexual reproduction Tsetse fly Mating Green fluorescent protein Red fluorescent protein |
| title | Experimental genetic crosses in tsetse flies of the livestock pathogen Trypanosoma congolense savannah |
| title_full | Experimental genetic crosses in tsetse flies of the livestock pathogen Trypanosoma congolense savannah |
| title_fullStr | Experimental genetic crosses in tsetse flies of the livestock pathogen Trypanosoma congolense savannah |
| title_full_unstemmed | Experimental genetic crosses in tsetse flies of the livestock pathogen Trypanosoma congolense savannah |
| title_short | Experimental genetic crosses in tsetse flies of the livestock pathogen Trypanosoma congolense savannah |
| title_sort | experimental genetic crosses in tsetse flies of the livestock pathogen trypanosoma congolense savannah |
| topic | Trypanosoma congolense Sexual reproduction Tsetse fly Mating Green fluorescent protein Red fluorescent protein |
| url | https://doi.org/10.1186/s13071-023-06105-4 |
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