Development and validation of a model forecasting the phenology of European tarnished plant bug Lygus rugulipennis in the U.K

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Human‐facilitated metapopulation dynamics in an emerging pest species,Cimex lectularius

The number and demographic history of colonists can have dramatic consequences for the way in which genetic diversity is distributed and maintained in a metapopulation. The bed bug (Cimex lectularius) is a re‐emerging pest species whose close association with humans has led to frequent local extinction and colonization, that is, to metapopulation dynamics. Pest control limits the lifespan of subpopulations, causing frequent local extinctions, and human‐facilitated dispersal allows the colonization of empty patches. Founder events often result in drastic reductions in diversity and an increased influence of genetic drift. Coupled with restricted migration, this can lead to rapid population differentiation. We therefore predicted strong population structuring. Here, using 21 newly characterized microsatellite markers and approximate Bayesian computation (ABC), we investigate simplified versions of two classical models of metapopulation dynamics, in a coalescent framework, to estimate the number and genetic composition of founders in the common bed bug. We found very limited diversity within infestations but high degrees of structuring across the city of London, with extreme levels of genetic differentiation between infestations (F_ST = 0.59). ABC results suggest a common origin of all founders of a given subpopulation and that the numbers of colonists were low, implying that even a single mated female is enough to found a new infestation successfully. These patterns of colonization are close to the predictions of the propagule pool model, where all founders originate from the same parental infestation. These results show that aspects of metapopulation dynamics can be captured in simple models and provide insights that are valuable for the future targeted control of bed bug infestations.     

Phagosome resolution regenerates lysosomes and maintains the degradative capacity in phagocytes

Phagocytes engulf unwanted particles into phagosomes that then fuse with lysosomes to degrade the enclosed particles. Ultimately, phagosomes must be recycled to help recover membrane resources that were consumed during phagocytosis and phagosome maturation, a process referred to as “phagosome resolution.” Little is known about phagosome resolution, which may proceed through exocytosis or membrane fission. Here, we show that bacteria-containing phagolysosomes in macrophages undergo fragmentation through vesicle budding, tubulation, and constriction. Phagosome fragmentation requires cargo degradation, the actin and microtubule cytoskeletons, and clathrin. We provide evidence that lysosome reformation occurs during phagosome resolution since the majority of phagosome-derived vesicles displayed lysosomal properties. Importantly, we show that clathrin-dependent phagosome resolution is important to maintain the degradative capacity of macrophages challenged with two waves of phagocytosis. Overall, our work suggests that phagosome resolution contributes to lysosome recovery and to maintaining the degradative power of macrophages to handle multiple waves of phagocytosis.     

Neritic carbonate for six submerged coral reefs from northern Australia: Implications for Holocene global carbon dioxide

Total contribution of six recently discovered submerged coral reefs in northern Australia to Holocene neritic CaCO₃ and CO₂ is assessed to address a gap in global budgets. CaCO₃ production for the reef framework and inter-reefal deposits is 0.26–0.28 Mt. Holocene CO₂ production is 0.14–0.16 Mt. Coral and coralline algae are the dominant sources of Holocene CaCO₃ although foraminifers and molluscs are the dominant constituents of inter-reefal deposits. The total amount of Holocene neritic CaCO₃ produced by the six submerged coral reefs is several orders of magnitude smaller than that calculated using accepted CaCO₃ production values because of very low production, a ‘give-up’ growth history, and presumed significant dissolution and exports. The contribution of submerged coral reefs to global Holocene neritic CaCO₃ is estimated to be 0.26–0.62 Gt, which yields 0.15–0.37 Gt of CO₂. This amount of CO₂ is 0.02–0.05% of the 780 Gt added to the atmosphere since 18 kyr BP. Contributions from Australian submerged coral reefs are estimated to be 0.05 Gt CaCO₃ and 0.03 Gt CO₂ for an emergent reef area of 47.9 × 10³ km². Based on the growth history of the submerged coral reefs in the Gulf of Carpentaria, maximum global Holocene CaCO₃ fluxes could have attained 0.3 Gt yr^− 1 between 11 and 7 ka BP. This additional CaCO₃ would have culminated in a maximum CaCO₃ production from all (emergent and submerged) coral reefs of 1.2 Gt yr^− 1 and neritic CaCO₃ production of 2.75 Gt yr^− 1. The dilemma remains that the global area and CaCO₃ mass of submerged coral reefs are currently unknown. It is inevitable that many more submerged coral reefs will be found. Our findings imply that submerged coral reefs are a small but fundamental source of Holocene neritic CaCO₃ and CO₂.     

Modulation of the heteromeric Kir4.1-Kir5.1 channel by multiple neurotransmitters via Galphaq-coupled receptors

The heteromeric Kir4.1-Kir5.1 channel is a candidate sensing molecule for central CO(2) chemoreception. Since central CO(2) chemoreception is subject to neural modulations, we performed studies to test the hypothesis that the Kir4.1-Kir5.1 channel is modulated by the neurotransmitters critical for respiratory control, including serotonin (5-HT), substance-P (SP), and thyrotropin releasing hormone (TRH). The heteromeric Kir4.1-Kir5.1 channel was strongly inhibited by SP, TRH, and 5-HT when expressed in Xenopus oocytes, whereas these neurotransmitters had no effect on the homomeric Kir4.1 channel. Such an inhibition was dose-dependent and relied on specific G(alphaq)-protein-coupled receptors and protein kinase C (PKC). No direct interaction of the channel with G-proteins was found. Channel sensitivity to CO(2)/pH was not compromised with the inhibition by these neurotransmitters, as the channel remained to be inhibited by acidic pH following an exposure to the neurotransmitters. The firing rate of CO(2)-sensitive brainstem neurons cultured in microelectrode arrays was augmented by SP or a 5-HT2A receptor agonist, which was blocked by PKC inhibitors suggesting that PKC underscores the inhibitory effect of SP and 5-HT in cultured brainstem neurons as well. Immunostaining showed that both Kir4.1 and Kir5.1 proteins were co-localized in the cultured brainstem neurons. These results therefore indicate that the heteromeric Kir4.1-Kir5.1 channel is modulated by the neurotransmitters critical for respiratory control, suggesting a novel neuromodulatory mechanism for the chemosensitivity of brainstem neurons to elevated PCO(2) and acidic pH.     

Molecular shape, architecture, and size of P2X4 receptors determined using fluorescence resonance energy transfer and electron microscopy

P2X receptors are ATP-gated nonselective cation channels with important physiological roles. However, their structures are poorly understood. Here, we analyzed the architecture of P2X receptors using fluorescence resonance energy transfer (FRET) microscopy and direct structure determination using electron microscopy. FRET efficiency measurements indicated that the distance between the C-terminal tails of P2X(4) receptors was 5.6 nm. Single particle analysis of purified P2X(4) receptors was used to determine the three-dimensional structure at a resolution of 21A(;) the orientation of the particle with respect to the membrane was assigned by labeling the intracellular C termini with 1.8-nm gold particles and the carbohydrate-rich ectodomain with lectin. We found that human P2X(4) is a globular torpedo-like molecule with an approximate volume of 270 nm(3) and a compact propeller-shaped ectodomain. In this structure, the distance between the centers of the gold particles was 6.1 nm, which closely matches FRET data. Thus, our data provide the first views of the architecture, shape, and size of single P2X receptors, furthering our understanding of this important family of ligand-gated ion channels.     

Evading the 'Lotus Effect'

A micro-relief of wax encrustation or outgrowths of epidermal cells imparts a property to most leaf surfaces which makes them self-cleaning when rain drops pass over them. Fungi, lichens and algae may evade this self-cleaning mechanism and take up residence on the leaf surface.     

A validated LC/MS/MS method for the quantification of pyrrole-2,3,5-tricarboxylic acid (PTCA), a eumelanin specific biomarker, in human skin punch biopsies

A novel skin tissue extraction method coupled with liquid chromatography-tandem mass spectrometry (LC/MS/MS) detection was developed and validated for the analysis of endogenous pyrrole-2,3,5-tricarboxylic acid (PTCA), a eumelanin specific biomarker, in human skin punch biopsies. The analyte is extracted from the matrix (2 mm skin punch biopsies) using a simple oxidative degradation procedure. The extract supernatants are evaporated, reconstituted in mobile phase solvent, and injected into the LC/MS/MS system without further derivatization. The chromatographic separation is achieved on a reverse phase high performance liquid chromatography (HPLC) column. The accuracy and precision of the method was determined over the concentration range of 1-1000 ng/mL PTCA from human skin extracts in three validation batch runs. Inter-assay precision (%CV) and accuracy (%R.E.) of the quality control samples were 相似文献