Structural and functional spatial dynamics of microbial communities in aerated and non-aerated horizontal flow treatment wetlands.

A multiphasic study using structural and functional analyses was employed to investigate the spatial dynamics of the microbial community within five horizontal subsurface flow treatment wetlands (TWs) of differing designs in Germany. The TWs differed in terms of the depth of media saturation, presence of plants (Phragmites australis), and aeration. In addition to influent and effluent water samples, internal samples were taken at different locations (12.5 %, 25 %, 50 %, and 75 % of the fractional distance along the flow path) within each system. 16S rRNA sequencing was used for the investigation of microbial community structure and was compared to microbial community function and enumeration data. The microbial community structure in the unaerated systems was similar, but different from the aerated TW profiles. Spatial positioning along the flow path explained the majority of microbial community dynamics/differences within this study. This was mainly attributed to the availability of nutrients closer to the inlet which also regulated the fixed biofilm/biomass densities. As the amount of fixed biofilm decreased from the inlet to the TW outlets, structural diversity increased, suggesting different microbial communities were present to handle the more easily utilized/degraded pollutants near the inlet vs. the more difficult to degrade and recalcitrant pollutants closer to the outlets. This study also confirmed that effluent water samples do not accurately describe the microbial communities responsible for water treatment inside a TW, highlighting the importance of using internal samples for investigating microbial communities in TWs. The results of this study reinforce an existing knowledge gap regarding the potential for TW design modifications which incorporate microbial community spatial dynamics (heterogeneity). It is suggested that utilizing step-feeding could allow for improved water treatment within the same areal footprint, and modifications enhancing co-metabolic processes could assist in improving the treatment of more difficult to degrade or recalcitrant compounds such as micropollutants.

A phylogenetic test of sympatric speciation in the Hydrobatinae (Aves: Procellariiformes).

Phylogenetic relationships among species can provide insight into how new species arise. For example, careful consideration of both the phylogenetic and geographic distributions of species in a group can reveal the geographic models of speciation within the group. One such model, sympatric speciation, may be more common than previously thought. The Hydrobatinae (Aves: Procellariformes) is a diverse subfamily of Northern Hemisphere storm-petrels for which the taxonomy is unclear. Previous studies showed that Hydrobates (formally Oceanodroma) castro breeding in the Azores during the cool season is sister species to H. monteiroi, a hot season breeder at the same locations, which suggests sympatric speciation by allochrony. To test whether other species within the subfamily arose via sympatric speciation by allochrony, we sequenced the cytochrome b gene and five nuclear introns to estimate a phylogenetic tree using multispecies coalescent methods, and to test whether species breeding in the same geographic area are monophyletic. We found that speciation within the Hydrobatinae appears to have followed several geographic modes of divergence. Sympatric seasonal species in Japan likely did not arise through sympatric speciation, but allochrony may have played a role in the divergence of H. matsudairae, a cool season breeder, and H. monorhis, a hot season breeder. No other potential cases of sympatric speciation were discovered within the subfamily. Despite breeding in the same geographic area, hydrobatine storm-petrels breeding in Baja California (H. microsoma and H. melania) are each sister to a species breeding off the coast of Peru (H. tethys and H. markhami, respectively). In fact, antitropical sister species appear to have diverged at multiple times, suggesting allochronic divergence might be common. In addition, allopatry has likely played a role in divergence of H. furcata, a north Pacific breeder, and H. pelagius, a north Atlantic breeder. This study demonstrates that a variety of mechanisms of divergence have played a role in generating the diversity of the Hydrobatinae and supports the current taxonomy of the subfamily.

Lamotrigine for the treatment of epilepsy in childhood.

OBJECTIVE: In this multicenter study, the efficacy and tolerability of lamotrigine were assessed in 285 children less than 13 years of age, recruited from 37 centers in 11 countries. METHODS: Pooled data from five open add-on studies have been analyzed. All the children had treatment-resistant epilepsy and most had two or more seizure types. Seizure frequency and global evaluation were assessed at the end of four successive 12-week periods of therapy. RESULTS: Seizure frequency was reduced by 50% or more in one third of the patients. Lamotrigine was effective in all seizure types examined, particularly for typical and atypical absence seizures. Atonic seizures also responded well. Improvement was well maintained during the treatment period. The maintenance dose had to be adjusted according to concomitant medication; dose ranges were 1 to 5 mg/kg per day for children taking valproate and 5 to 15 mg/kg per day for those not taking valproate. The commonest reported adverse experiences were somnolence, rash, vomiting, and seizure exacerbations. Adverse experiences led to withdrawal of treatment from 36 patients (12.6%). CONCLUSIONS: These results indicate that lamotrigine is well tolerated and is effective for a broad range of seizure types, especially absence seizures and atonic seizures.