Travellers' malaria - 'one shoe does not fit all'

Travellers' malaria is an exciting topic. It is a field in flux with evolving options for chemoprophylaxis, self-diagnosis, self-treatment, risk/strategy analyses and surveillance. Ideologies vary and experts differ but debate is needed and can bring change. The launch of a new thematic series in the Malaria Journal -- " Travellers' malaria " -- creates an ideal forum to bring together research papers, reviews, opinion papers and commentaries, and will hopefully stimulate debate.     

Molecular Evidence for a Deep Clade of Dunnarts (Marsupialia: Dasyuridae: Sminthopsis)

Sminthopsis is the most speciose genus of living dasyurid marsupials and, along with its close relatives Antechinomys and Ningaui, constitutes the clade Sminthopsini. Phylogenetic relationships among the 23 species in this clade have been the subject of much morphological and molecular investigation, including a recent integration of penis morphology (in Sminthopsis) with molecular systematics. Several phylogenetic issues remain open, however, including the monophyly of Sminthopsis and branching order among early sminthopsin lineages. In this study, we revisit sminthopsin systematics with an expanded molecular data set, including new DNA sequences from mitochondrial (valine transfer-RNA and 16S ribosomal RNA) and nuclear (interphotoreceptor retinoid binding protein and beta-fibrinogen) loci, along with previously published sequences of cytochrome b, 12S ribosomal RNA, control region, and protamine P1. Our results again fail to establish the monophyly of Sminthopsis, but do provide a clearer resolution of early sminthopsin branching. Specifically, our phylogeny suggests three major groups of Sminthopsis species: S. longicaudata (perhaps the sister of Antechinomys); the Macroura species group of previous authors (S. crassicaudata, S. macroura, S. virginiae, S. douglasi, and S. bindi); and the remaining 13 species allied with the Murina species group. Our results depart from previous molecular findings by reuniting S. ooldea with the Murina group, while resolving S. psammophila as sister to the hairy-footed dunnarts (S. hirtipes and S. youngsoni). We suggest that this conflict traces to anomalous phylogenetic signal in previously published cytochrome b sequences. Penis morphology maps reasonably well onto our phylogeny, requiring parallel origination of only one of the ten morphotypes described for Sminthopsis.     

Transformation of pecan and regeneration of transgenic plants

A gene transfer system developed for walnut (Juglans regia L.) was successfully applied to pecan (Carya illinoensis [Wang] K. Koch). Repetitively embryogenic somatic embryos derived from open-pollinated seed of Elliott, Wichita, and Schley were co-cultivated with Agrobacterium strain EHA 101/pCGN 7001, which contains marker genes for beta-glucuronidase activity and resistance to kanamycin. Several modifications of the standard walnut transformation techniques were tested, including a lower concentration of kanamycin and a modified induction medium, but these treatments had no measurable effect on efficiency of transformation. Nineteen of the 764 viable inoculated embryos produced transgenic subclones; 13 of these were from the line Elliott6, 3 from Schley5/3, and 3 from Wichita9. Transgenic embryos of Wichita9 germinated most readily and three subclones were successfully micropropagated. Three transgenic plants of one of these subclones were obtained by grafting the tissue cultured shoots to seedling pecan rootstock in the greenhouse. Gene insertion, initially detected by GUS activity, was confirmed by detection of integrated T-DNA sequences using Southern analysis.     

Genome-inferred spatio-temporal resolution of an uncultivated Roizmanbacterium reveals its ecological preferences in groundwater

Subsurface ecosystems like groundwater harbour diverse microbial communities, including small-sized, putatively symbiotic organisms of the Candidate Phyla Radiation, yet little is known about their ecological preferences and potential microbial partners. Here, we investigated a member of the superphylum Microgenomates (Cand. Roizmanbacterium ADI133) from oligotrophic groundwater using mini-metagenomics and monitored its spatio-temporal distribution using 16S rRNA gene analyses. A Roizmanbacteria-specific quantitative PCR assay allowed us to track its abundance over the course of 1 year within eight groundwater wells along a 5.4 km hillslope transect, where Roizmanbacteria reached maximum relative abundances of 2.3%. In-depth genomic analyses suggested that Cand. Roizmanbacterium ADI133 is a lactic acid fermenter, potentially able to utilize a range of complex carbon substrates, including cellulose. We hypothesize that it attaches to host cells using a trimeric autotransporter adhesin and inhibits their cell wall biosynthesis using a toxin–antitoxin system. Network analyses based on correlating Cand. Roizmanbacterium ADI133 abundances with amplicon sequencing-derived microbial community profiles suggested one potential host organism, classified as a member of the class Thermodesulfovibrionia (Nitrospirae). By providing lactate as an electron donor Cand. Roizmanbacterium ADI133 potentially mediates the transfer of carbon to other microorganisms and thereby is an important connector in the microbial community.