Seascape Genomics of the Sugar Kelp Saccharina latissima along the North Eastern Atlantic Latitudinal Gradient.

Temperature is one of the most important range-limiting factors for many seaweeds. Driven by the recent climatic changes, rapid northward shifts of species' distribution ranges can potentially modify the phylogeographic signature of Last Glacial Maximum. We explored this question in detail in the cold-tolerant kelp species Saccharina latissima, using microsatellites and double digest restriction site-associated DNA sequencing ( ddRAD-seq) derived single nucleotide polymorphisms (SNPs) to analyze the genetic diversity and structure in 11 sites spanning the entire European Atlantic latitudinal range of this species. In addition, we checked for statistical correlation between genetic marker allele frequencies and three environmental proxies (sea surface temperature, salinity, and water turbidity). Our findings revealed that genetic diversity was significantly higher for the northernmost locality (Spitsbergen) compared to the southern ones (Northern Iberia), which we discuss in light of the current state of knowledge on phylogeography of S. latissima and the potential influence of the recent climatic changes on the population structure of this species. Seven SNPs and 12 microsatellite alleles were found to be significantly associated with at least one of the three environmental variables. We speculate on the putative adaptive functions of the genes associated with the outlier markers and the importance of these markers for successful conservation and aquaculture strategies for S. latissima in this age of rapid global change.

Transformation of the Drosophila Sex-Manipulative Endosymbiont Spiroplasma poulsonii and Persisting Hurdles for Functional Genetic Studies.

Insects are frequently infected by bacterial symbionts that greatly affect their physiology and ecology. Most of these endosymbionts are, however, barely tractable outside their native host, rendering functional genetics studies difficult or impossible. Spiroplasma poulsonii is a facultative bacterial endosymbiont of Drosophila melanogaster that manipulates the reproduction of its host by killing its male progeny at the embryonic stage. S. poulsonii, although a very fastidious bacterium, is closely related to pathogenic Spiroplasma species that are cultivable and genetically modifiable. In this work, we present the transformation of S. poulsonii with a plasmid bearing a fluorescence cassette, leveraging techniques adapted from those used to modify the pathogenic species Spiroplasma citri We demonstrate the feasibility of S. poulsonii transformation and discuss approaches for mutant selection and fly colonization, which are persisting hurdles that must be overcome to allow functional bacterial genetics studies of this endosymbiont in vivoIMPORTANCE Dozens of bacterial endosymbiont species have been described and estimated to infect about half of all insect species. However, only a few them are tractable in vitro, which hampers our understanding of the bacterial determinants of the host-symbiont interaction. Developing a transformation method for S. poulsonii is a major step toward genomic engineering of this symbiont, which will foster basic research on endosymbiosis. This could also open the way to practical uses of endosymbiont engineering through paratransgenesis of vector or pest insects.

Intestinal Parasitic Infections and Environmental Water Contamination in a Rural Village of Northern Lao PDR.

A field survey studying intestinal parasites in humans and microbial pathogen contamination at environment was performed in a Laotian rural village to identify potential risks for disease outbreaks. A parasitological investigation was conducted in Ban Lak Sip village, Luang Prabang, Lao PDR involving fecal samples from 305 inhabitants as well as water samples taken from 3 sites of the local stream. Water analysis indicated the presence of several enteric pathogens, i.e., Aeromonas spp., Vibrio spp., E. coli H7, E. coli O157: H7, verocytotoxin-producing E. coli (VTEC), Shigella spp., and enteric adenovirus. The level of microbial pathogens contamination was associated with human activity, with greater levels of contamination found at the downstream site compared to the site at the village and upstream, respectively. Regarding intestinal parasites, the prevalence of helminth and protozoan infections were 68.9% and 27.2%, respectively. Eight helminth taxa were identified in fecal samples, i.e., 2 tapeworm species (Taenia sp. and Hymenolepis diminuta), 1 trematode (Opisthorchis sp.), and 5 nematodes (Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis, trichostrongylids, and hookworms). Six species of intestinal protists were identified, i.e., Blastocystis hominis, Cyclospora spp., Endolimax nana, Entamoeba histolytica/E. dispar, Entamoeba coli, and Giardia lamblia. Questionnaires and interviews were also conducted to determine risk factors of infection. These analyses together with a prevailing infection level suggested that most of villagers were exposed to parasites in a similar degree due to limited socio-economic differences and sharing of similar practices. Limited access to effective public health facilities is also a significant contributing factor.