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Muturi, M.

Publications and source records attributed to Muturi, M..

5 recordsLinked to original sources

Molecular mechanisms of seasonal brain shrinkage and regrowth inSorex araneus

To meet the challenge of wintering in place many high-latitude small mammals reduce energy demands through hibernation. In contrast, short-lived Eurasian common shrews, Sorex araneus, remain active and shrink, including energy-intensive organs in winter, regrowing in spring in an evolved strategy called Dehnels phenomenon. How this size change is linked to metabolic and regulatory changes to sustain their high metabolism is unknown. We analyzed metabolic, proteomic, and gene expression profiles spanning the entirety of Dehnels seasonal cycle in wild shrews. We show regulatory changes to oxidative phosphorylation and increased fatty acid metabolism during autumn-to-winter shrinkage, as previously found in hibernating species. But in shrews we also found upregulated winter expression of genes involved in gluconeogenesis: the biosynthesis of glucose from non-carbohydrate substrates. Co-expression models revealed changes in size and metabolic gene expression interconnect via FOXO signaling, whose overexpression reduces size and extends lifespan in many model organisms. We propose that while shifts in gluconeogenesis meet the challenge posed by high metabolic rate and active winter lifestyle, FOXO signaling is central to Dehnels phenomenon, with spring downregulation limiting lifespan in these shrews.

genetics↗

Large captivity effect based on gene expression comparisons between captive and wild shrew brains

Compared to their free-ranging counterparts, wild animals in captivity experience different conditions with lasting physiological and behavioral effects. Although shifts in gene expression are expected to occur upstream of these phenotypes, we found no previous gene expression comparisons of captive vs. free-ranging mammals. We assessed gene expression profiles of three brain regions (cortex, olfactory bulb, and hippocampus) of wild shrews (Sorex araneus) compared to shrews kept in captivity for two months and undertook sample drop-out to examine robustness given limited sample sizes. Consistent with captivity effects, we found hundreds of differentially expressed genes in all three brain regions, 104 overlapping across all three, that enriched pathways associated with neurodegenerative disease, oxidative phosphorylation, and genes encoding ribosomal proteins. In the shrew, transcriptomic changes detected under captivity resemble responses in several human pathologies, including major depressive disorder and neurodegeneration. While interpretations of individual genes are tempered by small sample sizes, we propose captivity influences brain gene expression and function and can confound analyses of natural processes in wild individuals under captive conditions.

genetics↗

Zoonotic Tick Borne Pathogens in Ticks at Human-Wildlife-Livestock interfaces in Kwale County, Kenya

BackgroundTicks are vectors that can harbor pathogens like viruses, protozoa and bacteria that can cause zoonotic diseases in human. Human gets infected through tick bites where the pathogens are passed to the human blood. One tick bite can lead to transmission of more than one disease. Ticks are obligate hematophagous, infest most vertebrates globally. Lack of surveillance information about the tick-borne pathogens and diseases has made it impossible to assess its impact to the community. Materials and MethodsWe morphologically identified ticks collected from two game reserves in Kenya, locations near the Shimba Hills National Reserve (SHNR) and Tsavo National Reserve (TNR). We identified tick-borne pathogens by HRM analysis and sequencing of specific RT-PCR products of Anaplasma, Ehrlichia, and Rickettsia. ResultsA total of 317 (281 adult ticks and 36 nymphs) was collected at near Tsavo National Reserve in Taita Taveta County, which includes seven species. Amblyomma was the most sampled genus with Amblyomma gemma being the most sampled species (n=135, 42.6%). Other Amblyomma species sampled was Amblyomma Variegatum (n= 40, 12.62%). Greatest species diversity was identified in Rhipicephalus genus with four species identified that includes; Rhipicephalus appendiculatus (n=44, 13.9%), Rhipicephalus Averts (n=1, 0.31%), Rhipicephalus Decoloratus (n=5, 1.6%), Rhipicephalus Pulchellus (n= 91, 28.7%). A single species of Hyalomma sp. was sampled. From near Shimba Hill game reserve (SHNR), a total of 240 adults ticks were sampled that comprises of eight species. Amblyomma was the most sampled genus and again Amblyomma gemma being the most sampled species (n=156, 65 %). Other Amblyomma species sampled includes; Amblyomma Lepidum (n= 5, 2.1 %), Amblyomma Variegatum (n= 15, 6.3 %). Greatest species diversity was also identified in Rhipicephalus genus with four species identified that includes; Rhipicephalus appendiculatus (n=18, 7.5 %), Rhipicephalus Averts (n=6, 2.5 %), Rhipicephalus Decoloratus (n=4, 1.7 %), Rhipicephalus Pulchellus (n= 34, 14.2 %). The least sampled species was a single species of Hyalomma Scupense (n=2, 0.83 %). At near Tsavo National Reserve (TNR) in Taita Taveta County, a total of three pools of Rhipicephaline appendiculatus were positive for Theileria parva, two pools of Rhipicephaline evertsi for Anaplasma platys and one pool of Amblyomma variegatum nymphs for Rickettsia africae. From near Shimba Hill game reserve (SHNR), Kwale County, Rickettsia africae pathogen was detected in two pools of Am. variegatum and one pool of Am. Gemma. Rickettsia sp. and Anaplasma sp. were detected in Am. Gemma and Rh. evertsi respective. R. aeschlimannii was detected in a pool of Am. Gemma. These findings highlight the risk of transmission of zoonotic R. africae and unclassified Rickettsia spp. to humans causing African tick-bite fever and other spotted-fever group rickettsioses.

molecular biology↗

High Real-time Reporting of Domestic and Wild Animal Diseases Following Rollout of Mobile Phone Reporting System in Kenya

BackgroundTo improve early detection of emerging infectious diseases in sub-Saharan Africa (SSA), many of them zoonotic, numerous electronic animal disease-reporting systems have been piloted but not implemented because of cost, lack of user friendliness, and data insecurity. In Kenya, we developed and rolled out an open-source mobile phone-based domestic and wild animal disease reporting system and collected data over two years to demonstrate its robustness and ability to track disease trends. MethodsThe Kenya Animal Biosurveillance System (KABS) application was built on the Java(R) platform, freely downloadable for android compatible mobile phones, and supported by web-based account management, form editing and data monitoring. The application was integrated into the surveillance systems of Kenyas domestic and wild animal sectors by adopting their existing data collection tools, and targeting disease syndromes prioritized by national, regional and international animal and human health agencies. Smartphone-owning government and private domestic and wild animal health officers were recruited and trained on the application, and reports received and analyzed by Kenya Directorate of Veterinary Services. The KABS application performed automatic basic analyses (frequencies, spatial distribution), which were immediately relayed to reporting officers as feedback. ResultsOver 95% of trained domestic animal officers downloaded the application, and >72% of them started reporting using the application within three months. Introduction of the application resulted in 2- to 10-fold increase in number of disease reports when compared the previous year (p<0.05), and reports were more spatially distributed. Among domestic animals, food animals (cattle, sheep, goats, camels, and chicken) accounted for >90% of the reports, with respiratory, gastrointestinal and skin diseases constituting >85% of the reports. Herbivore wildlife (zebra, buffalo, elephant, giraffe, antelopes) accounted for >60% of the wildlife disease reports, followed by carnivores (lions, cheetah, hyenas, jackals, and wild dogs). Deaths, traumatic injuries, and skin diseases were most reported in wildlife. ConclusionsThis open-source system was user friendly and secure, ideal for rolling out in other countries in SSA to improve disease reporting and enhance preparedness for epidemics of zoonotic diseases. Authors SummaryTaking advantage of a recently developed freely downloadable disease reporting application in the United States, we customized it for android smartphones to collect and submit domestic and wild animal disease data in real-time in Kenya. To enhance user friendliness, the Kenya Animal Biosurveillance System (KABS) was installed with disease reporting tools currently used by the animal sector and tailored to collected data on transboundary animal disease important for detecting zoonotic endemic and emerging diseases. The KABS database was housed by the government of Kenya, providing important assurance on its security. The application had a feedback module that performed basics analysis to provide feedback to the end-user in real-time. Rolling out of KABS resulted in >70% of domestic and wildlife disease surveillance officers using it to report, resulting in exponential increase in frequency and spatial distributions of reports regions. Utility of the system was demonstrated by successful detected a Rift Valley fever outbreak in livestock in 2018, resulting in early response and prevention of widespread human infections. For the wildlife sector in Eastern Africa, the application provided the first disease surveillance system developed. This open-source system is ideal for rolling out in other countries in sub-Saharan Africa to improve disease reporting and enhance preparedness for epidemics of zoonotic diseases.

microbiology↗

Evaluation of near infrared spectroscopy for sporozoite detection in mosquitoes infected with wild-strain parasites from asymptomatic gametocyte carriers in Kilifi Kenya

BackgroundScreening for Plasmodium spp. sporozoite infection in mosquitoes is routinely done using ELISA (enzyme-linked immunosorbent assay). Near infrared spectroscopy (NIRS), a fast and non-destructive method, has recently been shown to distinguish, with 95% accuracy, between uninfected and sporozoite-infected mosquitoes using laboratory strains of Plasmodium falciparum (PfN54). The aim of this present study was to further investigate the reproducibility of NIRS to identify sporozoite infection in mosquitoes infected using field isolates of P. falciparum gametocytes from asymptomatic carriers. MethodsHealthy individuals (aged 5 years and above) were screened for gametocytaemia by thick-smear microscopy in an area of moderate transmission along the Coast of Kenya between May and September 2018. Asymptomatic gametocyte carriers were recruited for mosquito feeding assays, direct membrane feeding (DMFA) and direct skin feeding (DFA), using insectary-reared Anopheles gambiae s.s (Kilifi strain). Mosquitoes were kept for 14-days post feeding after which they were scanned using NIRS and subsequently analysed for sporozoite infection using circumsporozoite-ELISA. Predictive models were explored using partial least square regressions (PLS). ResultsTwo hundred and ninety-nine (299) individuals were screened for malaria parasites, 74 (24.8%) were found with circulating asexual parasites, and 16 (5.4%) with P. falciparum gametocyte stages. Fourteen (14) asymptomatic gametocyte carriers were recruited to the study for mosquito feeding assays. A total of 134 (7%, 134/1881) sporozoite-infected mosquitoes were obtained from 9 successful experiments. Three different training datasets composed of infected and uninfected mosquitoes were analysed. The PLS models were unable to distinguish between sporozoite-infected and uninfected mosquitoes. A predictive model could not be generated. ConclusionsThe results of this study were not consistent with previous published research on NIRS for detection of sporozoite infection in the same mosquito species and may reflect differences between laboratory and field conditions. The current findings indicate that methods for sporozoite detection should be tested on field isolates at an early stage in their development and are informative for future research seeking novel high-throughput methods for parasite detection in mosquitoes.

zoology↗