Genetic evidence for the origin of Aedes aegypti,the yellow fever mosquito,in the southwestern Indian Ocean

Aedes aegypti is among the best‐studied mosquitoes due to its critical role as a vector of human pathogens and ease of laboratory rearing. Until now, this species was thought to have originated in continental Africa, and subsequently colonized much of the world following the establishment of global trade routes. However, populations of this mosquito on the islands in the southwestern Indian Ocean (SWIO), where the species occurs with its nearest relatives referred to as the Aegypti Group, have received little study. We re‐evaluated the evolutionary history of Ae. aegypti and these relatives, using three data sets: nucleotide sequence data, 18,489 SNPs and 12 microsatellites. We found that: (a) the Aegypti Group diverged 16 MYA (95% HPD: 7–28 MYA) from its nearest African/Asian ancestor; (b) SWIO populations of Ae. aegypti are basal to continental African populations; (c) after diverging 7 MYA (95% HPD: 4–15 MYA) from its nearest formally described relative (Ae. mascarensis), Ae. aegypti moved to continental Africa less than 85,000 years ago, where it recently (<1,000 years ago) split into two recognized subspecies Ae. aegypti formosus and a human commensal, Ae. aegypti aegypti; (d) the Madagascar samples form a clade more distant from all other Ae. aegypti than the named species Ae. mascarensis, implying that Madagascar may harbour a new cryptic species; and (e) there is evidence of introgression between Ae. mascarensis and Ae. aegypti on Réunion, and between the two subspecies elsewhere in the SWIO, a likely consequence of recent introductions of domestic Ae. aegypti aegypti from Asia.     

Detection of ornamental transgenic fish by real-time PCR and fluorescence microscopy

Transgenic Research - Numbers of ornamental transgenic fish are increasing, and some of them are illegally imported into Europe. The fish are modified to display different fluorescent colors under...     

Investigating the Impact of Storage Conditions on Microbial Community Composition in Soil Samples

Recent advances in DNA sequencing technologies have allowed scientists to probe increasingly complex biological systems, including the diversity of bacteria in the environment. However, despite a multitude of recent studies incorporating these methods, many questions regarding how environmental samples should be collected and stored still persist. Here, we assess the impact of different soil storage conditions on microbial community composition using Illumina-based 16S rRNA V4 amplicon sequencing. Both storage time and temperature affected bacterial community composition and structure. Frozen samples maintained the highest alpha diversity and differed least in beta diversity, suggesting the utility of cold storage for maintaining consistent communities. Samples stored for intermediate times (three and seven days) had both the highest alpha diversity and the largest differences in overall beta diversity, showing the degree of community change after sample collection. These divergences notwithstanding, differences in neither storage time nor storage temperature substantially altered overall communities relative to more than 500 previously examined soil samples. These results systematically support previous studies and stress the importance of methodological consistency for accurate characterization and comparison of soil microbiological assemblages.     

Biomass Production and Composition of Perennial Grasses Grown for Bioenergy in a Subtropical Climate Across Florida, USA

Carbohydrate and lignin composition of feedstock materials are major factors in determining their bioenergy potential. This study was conducted to quantify dry biomass yield and the carbohydrate and lignin composition of six potential biofuel grasses (elephantgrass, energycane, sweetcane, giant reed, giant miscanthus, and sugarcane) across three sites in Florida for plant (2009) and first ratoon (2010) crops. Dry biomass yields ranged from about 30 to 50 Mg ha^?1 and were generally greatest for elephantgrass, energycane, sweetcane, and sugarcane. Accordingly, total plant carbohydrate yields (20 to 25 Mg ha^?1) were comparable among sugarcane, energycane, sweetcane, and elephantgrass, but were generally less for giant reed and even less for giant miscanthus. However, the contribution of total extractable carbohydrates and total fiber carbohydrates to total plant carbohydrate yields differed among species. Sugarcane had the highest concentrations of extractable carbohydrates (219 to 356 mg g^?1), followed by energycane, then sweetcane, elephantgrass, and giant reed, with giant miscanthus having the lowest. Energycane and elephantgrass tended to have significantly more fiber glucose, and elephantgrass less xylose, than other species. Variability in total lignin concentrations on a fiber basis was relatively modest (250 to 285 mg g^?1) across species, but was generally highest in sweetcane and giant reed. Overall, elephantgrass and energycane were prime regional candidates for cellulosic conversion using fermentation processes due to high yields and favorable fiber characteristics, although energycane tended to have higher extractable carbohydrates.     

Ultrastructure of Calcareous Dinophytes (Thoracosphaeraceae,Peridiniales) with a Focus on Vacuolar Crystal-Like Particles

Biomineralization in calcareous dinophytes (Thoracosphaeracaea, Peridiniales) takes place in coccoid cells and is presently poorly understood. Vacuolar crystal-like particles as well as collection sites within the prospective calcareous shell may play a crucial role during this process at the ultrastructural level. Using transmission electron microscopy, we investigated the ultrastructure of coccoid cells at an early developmental stage in fourteen calcareous dinophyte strains (corresponding to at least ten species of Calciodinellum, Calcigonellum, Leonella, Pernambugia, Scrippsiella, and Thoracosphaera). The shell of the coccoid cells consisted either of one (Leonella, Thoracosphaera) or two matrices (Scrippsiella and its relatives) of unknown element composition, whereas calcite is deposited in the only or the outer layer, respectively. We observed crystal-like particles in cytoplasmic vacuoles in cells of nine of the strains investigated and assume that they are widespread among calcareous dinophytes. However, similar structures are also found outside the Thoracosphaeraceae, and we postulate an evolutionarily old physiological pathway (possibly involved in detoxification) that later was specialized for calcification. We aim to contribute to a deeper knowledge of the biomineralization process in calcareous dinophytes.     

Silencing of OsCV (chloroplast vesiculation) maintained photorespiration and N assimilation in rice plants grown under elevated CO2

High CO₂ concentrations stimulate net photosynthesis by increasing CO₂ substrate availability for Rubisco, simultaneously suppressing photorespiration. Previously, we reported that silencing the chloroplast vesiculation (cv) gene in rice increased source fitness, through the maintenance of chloroplast stability and the expression of photorespiration-associated genes. Because high atmospheric CO₂ conditions diminished photorespiration, we tested whether CV silencing might be a viable strategy to improve the effects of high CO₂ on grain yield and N assimilation in rice. Under elevated CO₂, OsCV expression was induced, and OsCV was targeted to peroxisomes where it facilitated the removal of OsPEX11-1 from the peroxisome and delivered it to the vacuole for degradation. This process correlated well with the reduction in the number of peroxisomes, the decreased catalase activity and the increased H₂O₂ content in wild-type plants under elevated CO₂. At elevated CO₂, CV-silenced rice plants maintained peroxisome proliferation and photorespiration and displayed higher N assimilation than wild-type plants. This was supported by higher activity of enzymes involved in NO₃⁻ and NH₄⁺ assimilation and higher total and seed protein contents. Co-immunoprecipitation of OsCV-interacting proteins suggested that, similar to its role in chloroplast protein turnover, OsCV acted as a scaffold, binding peroxisomal proteins.     

Antibiotic resistance of biofilms

Microbial biofilms are notably recalcitrant towards treatment with antibiotics, biocides or disinfectants that would adequately control the same organisms growing in planktonic mode. Much of this resistance has been attributed to an organisation of the biofilm cells within exopolymer matrices. Whilst such exopolymers are unlikely to hinder the diffusion and access of antimicrobial agents to the underlying cells, they will chemically quench reactive biocides such as chlorine and peroxygens, and bind highly charged antibiotics, such as tobramycin and gentamycin, thereby providing some protection to the more deep lying cells. Extracellular enzymes, bound within the glycocalyx and able to degrade the treatment agents, will further reduce the access of susceptible compounds. Diffusion limitation however, is unlikely to be the sole moderator of the resistance properties of microbial biofilms. In addition, gradients of oxygen and nutrients established across the biofilm community will cause growth rates to be much reduced at points remoted from the accessible nutrient. Slow growth rates, and the associated induction of stringent responses further contribute towards this resistance. Finally, there have been recent demonstrations that attachment of microorganisms to surfaces promotes the expression of genes that are not normally expressed in planktonic culture. Whether or not the expression of such genes alters the phenotype in a manner which alters the response of the cells to antimicrobial agents remains to be demonstrated.