Comparative genomics of first available bovine Anaplasma phagocytophilum genome obtained with targeted sequence capture

Background

Anaplasma phagocytophilum is a zoonotic and obligate intracellular bacterium transmitted by ticks. In domestic ruminants, it is the causative agent of tick-borne fever, which causes significant economic losses in Europe. As A. phagocytophilum is difficult to isolate and cultivate, only nine genome sequences have been published to date, none of which originate from a bovine strain.Our goals were to; 1/ develop a sequencing methodology which efficiently circumvents the difficulties associated with A. phagocytophilum isolation and culture; 2/ describe the first genome of a bovine strain; and 3/ compare it with available genomes, in order to both explore key genomic features at the species level, and to identify candidate genes that could be specific to bovine strains.

Results

DNA was extracted from a bovine blood sample infected by A. phagocytophilum. Following a whole genome capture approach, A. phagocytophilum DNA was enriched 197-fold in the sample and then sequenced using Illumina technology. In total, 58.9% of obtained reads corresponded to the A. phagocytophilum genome, covering 85.3% of the HZ genome. Then by performing comparisons with nine previously-sequenced A. phagocytophilum genomes, we determined the core genome of these ten strains. Following analysis, 1281 coding DNA sequences, including 1001 complete sequences, were detected in the A. phagocytophilum bovine genome, of which four appeared to be unique to the bovine isolate. These four coding DNA sequences coded for "hypothetical proteins of unknown function” and require further analysis. We also identified nine proteins common to both European domestic ruminants tested.

Conclusion

Using a whole genome capture approach, we have sequenced the first A. phagocytophilum genome isolated from a cow. To the best of our knowledge, this is the first time that this method has been used to selectively enrich pathogenic bacterial DNA from samples also containing host DNA. The four proteins unique to the A. phagocytophilum bovine genome could be involved in host tropism, therefore their functions need to be explored.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-973) contains supplementary material, which is available to authorized users.     

First Evidence of Inclusive Sexual Selection in the Ant Cataglyphis cursor: Worker Aggressions Differentially Affect Male Access to Virgin Queens

Sexual selection typically shapes the traits of individuals capable of reproduction. However, in social species, it may also affect the behaviour of non‐reproductive individuals if this increases their inclusive fitness. We examined the potential role of workers during mating in the polyandrous ant Cataglyphis cursor. In this species, mating takes place on the ground near the nest entrance, and workers chase away foreign males trying to mate with young queens (gynes). We investigated the effects of worker aggression on male mating attempts by placing three or four males in the presence of one foreign gyne and 20 of her nestmate workers and contrasted this with a second group of 3–4 males in the presence of another gyne without nestmate workers (n = 8 paired replicates). Workers strongly attacked males (more than 20 aggressions per minute), although this did not affect the total number of mating attempts by the 3–4 males or the skew in the number of mating attempts among these males. However, there was an interaction between worker aggression and relative male weight, as relatively heavy males attempted to mate more often than lighter males in the absence of worker whereas the reverse occurred in the presence of workers. Our study is the first to experimentally test the potential role of non‐reproductive individuals in sexual selection. It shows that workers could potentially change male mating success by disfavouring heavier males.     

Inhibition of plant and animal cytochrome oxidases by nitrous oxide as a function of cytochrome c concentration.

Cytochrome oxidase from both pea leaves and bovine heart shows lower activity under a mixture of 79% N2O/21% O2 than under ambient air. This inhibition is not detectable below 5 microM cytochrome c but appears with increasing concentrations of cytochrome c. These results suggest that the N2O-induced inhibition of cytochrome c oxidase is modulated by cytochrome c concentration. This seems to concern only the lowest affinity site of the oxidase. Apparently, N2O and cytochrome c do not share the same site of fixation on the oxidase.     

Magnesium ions promote assembly of channel‐like structures from beticolin 0, a non‐peptide fungal toxin purified from Cercospora beticola

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