Population dynamics of ticks infesting sheep in the arid steppes of Tunisia

This study aimed to determine tick population dynamics infesting sheep in Gafsa region (Central Tunisia). Ticks were collected monthly over a year, from October 2013 to September 2014, from 57‒64 randomly-included Barbarine-breed sheep. In total, 560 ticks were collected and identified. They belonged to two species: Rhipicephalus sanguineus sensu lato (98.6%) and Hyalomma excavatum (1.4%). Sheep were only infested from April to October with a maximum infestation prevalence (number of infested animals / number of examined animals) in August for R. sanguineus s.l. (83%), and in May for H. excavatum (7%). The highest infestation intensity (number of ticks / number of infested sheep) was 3.7 ticks per animal in August. These results should help sheep owners and veterinarians to implement efficient control programs against ticks and the pathogens they transmit

Closed-loop cycles of experiment design, execution, and learning accelerate systems biology model development in yeast

This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1900548116/-/DCSupplemental.Copyright © 2019 The Author(s). One of the most challenging tasks in modern science is the development of systems biology models: Existing models are often very complex but generally have low predictive performance. The construction of high-fidelity models will require hundreds/thousands of cycles of model improvement, yet few current systems biology research studies complete even a single cycle. We combined multiple software tools with integrated laboratory robotics to execute three cycles of model improvement of the prototypical eukaryotic cellular transformation, the yeast (Saccharomyces cerevisiae) diauxic shift. In the first cycle, a model outperforming the best previous diauxic shift model was developed using bioinformatic and systems biology tools. In the second cycle, the model was further improved using automatically planned experiments. In the third cycle, hypothesis-led experiments improved the model to a greater extent than achieved using high-throughput experiments. All of the experiments were formalized and communicated to a cloud laboratory automation system (Eve) for automatic execution, and the results stored on the semantic web for reuse. The final model adds a substantial amount of knowledge about the yeast diauxic shift: 92 genes (+45%), and 1,048 interactions (+147%). This knowledge is also relevant to understanding cancer, the immune system, and aging. We conclude that systems biology software tools can be combined and integrated with laboratory robots in closed-loop cycles.HIST-ERA AdaLab project: The Engineering and Physical Sciences Research Council (EPSRC), UK(EP/M015661/1) ANR-14-CHR2-0001-01

Seasonal variation of lungworm infestation of ewes at Sidi Bouzid slaughterhouse (Central Tunisia)

Respiratory strongyloses are among the most important diseases affecting sheep reared in various farming systems in many countries. In Tunisia, farmers without any scientific background carry out the control of these parasites. A survey was performed in a slaughterhouse in Sidi Bouzid District (Central Tunisia) to assess the prevalence of sheep infestation by lungworms. The study lasted 12 months and involved 720 of the slaughtered ewes. Fecal samples from each ewe were collected and examined by Baermann’s technique. Sixty-eight samples were infested with pulmonary nematode larvae (9.4 ± 2.1%). The population was dominated by Protostrongylus rufescens (4.4 ± 1.5%), followed by Dictyocaulus filaria (2.6 ± 1.2%), Cystocaulus ocreatus and Neostrongylus linearis (1.3 ± 0.8%), and finally Muellerius capillaris (0.3 ± 0.4%), whereas mixed infestations concerned 0.4 ± 0.5% of samples. Lungworm infestation was observed in all age groups with no significant difference (p = 0.64). In addition there was no significant difference in infestation between fat-tailed Barbarine (10.8 ± 3.6%) and Queue fine de l’Ouest (Western Thin Tail) (8.5 ± 2.6%; p = 0.31) sheep breeds. The lowest prevalence was recorded in spring (6.7 ± 3.6%) and the highest in winter (11.7 ± 4.8%), but the difference between seasons was not significant (p = 0.32). This study concerning the activity dynamics of lungworms should be completed by a monitoring project to determine the economic importance of these infestations and provide a solid basis for the establishment of specific control programs against these parasites in Tunisia

Integrating transcriptional activity in genome-scale models of metabolism

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