Evolution of the thaumastocheliform lobsters (Crustacea,Decapoda, Nephropidae)

Deep‐sea lobsters previously assigned to the family Thaumastochelidae Bate, 1888, the thaumastocheliforms, have very distinctive, greatly unequal first chelipeds, with the right side extremely elongate and pectinate, and in having short, quadrate pleonal pleura. Despite interesting morphology and a long taxonomic history, the phylogeny of the group has received little detailed analysis. Here, we conduct a species‐level phylogenetic analysis of the thaumastocheliforms based on morphological and molecular data (three mitochondrial genes: COI, 16S rDNA and 12S rDNA; two nuclear protein‐coding genes: H3 and NaK) to robustly reconstruct their evolutionary history and estimate divergence times. Separate and combined analyses of all data sources support thaumastocheliform monophyly, but as a clade deeply nested within the Nephropidae supporting recent synonymy of Thaumastochelidae with Nephropidae. Combined and molecular‐only analyses support generic monophyly of all three thaumastocheliform genera and Dinochelus as sister to Thaumastochelopsis, fully corroborating the current, morphology‐based taxonomy. In contrast, Thaumastocheles is recovered as paraphyletic in morphology‐only analyses owing to minimal character support. The Cretaceous–Paleogene Oncopareia was recovered as a stem‐lineage thaumastocheliform. The fossil record indicates that the thaumastocheliforms once lived in shallow, continental shelf depths, but moved into deeper water in the Cenozoic where they occur today. The thaumastocheliforms originated in northern Europe during the Mid‐Late Cretaceous and later dispersed westwards to the south‐eastern Pacific through the western Atlantic and eastwards to the western Pacific through the Indian Ocean. Thaumastochelopsis can be considered the most derived thaumastocheliform genus based on the degree of structural reduction relative to other thaumastocheliforms, its remote geographical occurrence (Australia) from the hypothesised place of origin (northern Europe) and its more recent estimated divergence than other genera (28 Mya for the MRCA of extant species of the genus).     

Priority effects and habitat complexity affect the strength of competition

Both habitat complexity and priority effects can influence the strength of competitive interactions; however, the independent and synergistic effects of these processes are not well understood. In Moorea, French Polynesia, we conducted a factorial field experiment to quantify the independent and combined effects of priority effects and habitat complexity on the strength of intraspecific competitive interactions among recently settled individuals of a coral reef fish (Thalassoma quinquevittatum: Labridae). Simultaneous arrival of focal individuals with competitors resulted in a 2.89-fold increase in survival relative to reefs where focal individuals arrived 5 days later than competitors (i.e., a priority effect). Increasing habitat complexity resulted in a 1.55-fold increase in survivorship when focal individuals arrived simultaneously with or before competitors. However, increasing habitat complexity did not affect the survivorship of focal individuals arriving 5 days later than competitors. Behavior observations showed that survivorship was negatively correlated with aggression. Aggression by prior residents towards focal individuals was significantly greater when focal individuals arrived 5 days later than competitors than when they arrived simultaneously. Increasing habitat complexity did not reduce aggression. Our results suggest that, when competitors arrive simultaneously, competitive interactions are weak and subordinates are not displaced from complex habitat; increasing habitat complexity increases survival by disrupting predation. Conversely, when competitors arrive at different times, aggression intensifies and increasing habitat complexity does not disrupt predation because competitive subordinates are excluded from habitat resources. This study demonstrates that the strength of competition can be context-dependent and may vary with the timing of competitive interactions and habitat complexity.     

Avoidance behavior in two sympatric planaria species: effects of conspecific and heterospecific chemical alarm cues

In many aquatic animals, predator avoidance can be stimulated by chemical cues, including those released by injured prey (alarm cues). Alarm cues of both conspecific and heterospecific origin have been identified within several fish taxa, where phylogenetic conservation of the cue-response complex is common. Turbellarian flatworms (planaria) are among the simplest animals known to respond to chemical cues released by injured conspecifics. We examined how two locally sympatric planaria species respond to conspecific and heterospecific chemical cues using macerated tissue suspensions. Brown (Girardia tigrina) and black (Dugesia dorotocephala) planaria both exhibited avoidance behavior when presented conspecific cues. Despite a significant twofold difference in body size (black > brown), stimulus prepared from a single (1×) individual of either species elicited avoidance. Increasing brown planaria cue concentration by macerating two individuals (2×) produced a significant increase in conspecific avoidance. Heterospecific stimuli produced asymmetric results. Black planaria avoided the brown planaria stimulus, but only in the higher concentration (2×) trials. Brown planaria did not consistently exhibit avoidance of the black planaria stimulus and some brown subjects approached and consumed black planarian tissues. Our results expand the demonstrated occurrence of alarm cues among planaria and suggest that avoidance behavior can be mediated by multiple environmental and intrinsic factors in freshwater Turbellaria.     

Magnetic core-shell nanoparticles for drug delivery by nebulization

Background

Aerosolized therapeutics hold great potential for effective treatment of various diseases including lung cancer. In this context, there is an urgent need to develop novel nanocarriers suitable for drug delivery by nebulization. To address this need, we synthesized and characterized a biocompatible drug delivery vehicle following surface coating of Fe₃O₄ magnetic nanoparticles (MNPs) with a polymer poly(lactic-co-glycolic acid) (PLGA). The polymeric shell of these engineered nanoparticles was loaded with a potential anti-cancer drug quercetin and their suitability for targeting lung cancer cells via nebulization was evaluated.

Results

Average particle size of the developed MNPs and PLGA-MNPs as measured by electron microscopy was 9.6 and 53.2 nm, whereas their hydrodynamic swelling as determined using dynamic light scattering was 54.3 nm and 293.4 nm respectively. Utilizing a series of standardized biological tests incorporating a cell-based automated image acquisition and analysis procedure in combination with real-time impedance sensing, we confirmed that the developed MNP-based nanocarrier system was biocompatible, as no cytotoxicity was observed when up to 100 μg/ml PLGA-MNP was applied to the cultured human lung epithelial cells. Moreover, the PLGA-MNP preparation was well-tolerated in vivo in mice when applied intranasally as measured by glutathione and IL-6 secretion assays after 1, 4, or 7 days post-treatment. To imitate aerosol formation for drug delivery to the lungs, we applied quercitin loaded PLGA-MNPs to the human lung carcinoma cell line A549 following a single round of nebulization. The drug-loaded PLGA-MNPs significantly reduced the number of viable A549 cells, which was comparable when applied either by nebulization or by direct pipetting.

Conclusion

We have developed a magnetic core-shell nanoparticle-based nanocarrier system and evaluated the feasibility of its drug delivery capability via aerosol administration. This study has implications for targeted delivery of therapeutics and poorly soluble medicinal compounds via inhalation route.