Publications

4719

Background: Tick-borne diseases are frequent in the Southeastern section of Brazil. The most prevalent canine parasites diagnosed are Ehrlichia canis, Babesia gibsoni, Babesia canis and Anaplasma platys, although Mycoplasma haemocanis and candidatus Mycoplasma haematoparvum have been registered in the country. Methods: When two clinically healthy dogs from a suburban area of the state of Rio de Janeiro, Brazil with history of being heavily infested with ticks were examined at Idexx Reference Laboratories, California for tick panel check. Results: One dog harbored DNA of candidatus Mycoplasma haematoparvum and the other DNA of Mycoplasma haemocanis. Conclusions: These results suggest that monitoring for tick infestations and tick-borne parasites must be permanent in southeastern Brazil, especially due to global climate changes which may contribute to spread and increase the number of infections in the Country.

A little help from a friend The Hawaiian sea slug Elysia rufescens grazes on an alga called Bryopsis sp. The alga defends itself from predators using peptide toxins decorated with fatty acids, called kahalalides. Zan et al. wondered if a third party was involved in toxin production (see the Perspective by Mascuch and Kubanek). Within the alga, a species of bacterium with a very reduced genome was discovered to be a factory for the nonribosomal assembly of a family of kahalalides. The authors elucidated the pathways for generating this chemical diversity. It seems that the sea slug not only tolerates the toxins but, to protect itself from being eaten by fish, grazes on the alga to accumulate kahalalide. Science , this issue p. eaaw6732 ; see also p. 1034

AbstractPlacozoa is an enigmatic phylum of simple, microscopic, marine metazoans1,2. Although intracellular bacteria have been found in all members of this phylum, almost nothing is known about their identity, location and interactions with their host3–6. We used metagenomic and metatranscriptomic sequencing of single host individuals, plus metaproteomic and imaging analyses, to show that the placozoan Trichoplax sp. H2 lives in symbiosis with two intracellular bacteria. One symbiont forms an undescribed genus in the Midichloriaceae (Rickettsiales)7,8 and has a genomic repertoire similar to that of rickettsial parasites9,10, but does not seem to express key genes for energy parasitism. Correlative image analyses and three-dimensional electron tomography revealed that this symbiont resides in the rough endoplasmic reticulum of its host’s internal fibre cells. The second symbiont belongs to the Margulisbacteria, a phylum without cultured representatives and not known to form intracellular associations11–13. This symbiont lives in the ventral epithelial cells of Trichoplax, probably metabolizes algal lipids digested by its host and has the capacity to supplement the placozoan’s nutrition. Our study shows that one of the simplest animals has evolved highly specific and intimate associations with symbiotic, intracellular bacteria and highlights that symbioses can provide access to otherwise elusive microbial dark matter.

AbstractHuanglongbing (HLB; yellow shoot disease) is a severe worldwide infectious disease for citrus family plants. The pathogenCandidatus Liberibacter asiaticus(CLas) is an alphapro-teobacterium of theRhizobiaceaefamily that has been identified as the cause. The virulence of CLas has been attributed, in part, to prophage encoded genes. Prophage and prophage like elements have been identified in 12 of the 15 CLas available genomes, and are classified into three prophage types. Here, we re-examined all 15 CLas genomes using ade novoprediction approach and expanded the number of prophage like elements from 16 to 33. Further, we find that all CLas contain at least one prophage-like sequence. Comparative analysis reveals a prevalent, albeit previously unknown, prophage-like sequence type that is a remnant of an integrated prophage. Notably, this remnant prophage is found in the Ishi-1 CLas strain that had previously been reported as lacking prophages. Our findings provide both a resource and new insights into the evolutionary relationship between phage and CLas pathogenicity.