Nepenthes Pitcher Research Articles

Super Slippery Surface for Small Volume of Liquid on Superhydrophilic Nanoscale Texture

In order to realize the excellent functional antifouling coating, the anti-adhesive property is requiring for the material surface. The photocatalyst material such as TiO2 are conventionally used for degrading pollution [1,2]. The superhydrophobic bumps such as lotus leaf structure [3,4], or super slippery surface such as Nepenthes pitcher plant are also conventionally used for self-cleaning function [5,6]. These functional surfaces, however, have been applied in limited practical use due to their difficulties in processability, wearability, permeability and resupplying the lubricant. This paper reports the first example of super slippery surface using superhydrophilic material, which is opposite approach to generally using superhydrophobic material as mentioned above. The newly discovered superhydrophilic slippery surface has been realized by nanotextured photocatalyst with surface reforming process. Without hydrophobicity or lubricant, it has been succeeded in sliding waterdrops smaller than 5 μL with sliding angle lower than 5° (Fig. 1). The GaN substrate has been selected as photocatalyst in this study, and 100 nm in diameter SiO2 nanoballs have been dip coated on the substrate in the shape of single layered colloidal crystal following surface modification of the substrate. The nanotexture has been formed by dry etching process with hexagonal closed packed structure SiO2 nanoball etching mask [7–9]. Finally, the nanotextured GaN surface has been modified again to superhydrophilic then the super slippery surface has been finished up [10]. The obtained new phenomenon, i.e. super slips on superhydrophilic surface, is supposed to be affected by the fractal curve at the 3-phase (water, GaN and air) contact line, and by the super low friction coefficient between waterdrop and nanotexture that likes commonly used Cassie-Baxter model. [1] A. Fujishima & K. Honda, Nature 238, 37–38 (1972). [2] R. Wang, K. Hashimoto, A. Fujishima, M. Chikuni, E. Kojima, A. Kitamura, M. Shimohigoshi & T. Watanabe, Nature 388, 431–432 (1997). [3] T. Y. Liu & C. Kim, Science 346, 1096–1100 (2014). [4] A. Tuteja, W. Choi, M. Ma, J. M. Mabry, S. A. Mazzella, G. C. Rutledge, G. H. McKinley & R. E. Cohen, Science 318, 1618–1622 (2007). [5] T. S. Wong, S. H. Kang, S. K. Tang, E. J. Smythe, B. D. Hatton, A. Grinthal & J. Aizenberg, Nature 477, 443–447 (2011). [6] A. R. Parker, C. R. Lawrence, Nature 414, 33–34 (2001). [7] M. Fujikane, A. Inoue & T. Yokogawa, US patent 8852965 (2014). [8] M. Fujikane, A. Inoue & T. Yokogawa, US patent 8841220 (2014). [9] M. Fujikane, A. Inoue & T. Yokogawa, US patent 9209254 (2015). [10] M. Fujikane, EU patent 17167854.3 (2017). Figure 1 | Relation between the water volume and the sliding angle for different types of surfaces. The values in parentheses at the end of graph legends indicate static contact angle with 2 μL water probe. Figure 1

Bioinspired Slippery Zinc Phosphate Coating for Sustainable Corrosion Protection

In this work, a slippery zinc phosphate coating composed with homogeneous pores was successfully fabricated by a facile method which was inspired by nepenthes pitcher plants. The as-prepared coating exhibited superhydrophobicity with a large water contact angle (WCA) of 156.6° after modification with fluoroalkylsilane (FAS) ethanol solution. A slippery surface with highly water-repellency was achieved by completely filling the Krytox 100 lubricant into the pores. Generally, based on the stable and low-volatile lubricant, a slippery surface can provide a better corrosion resistance than that of superhydrophobic surface for metals. Herein, this novel slippery coating also displayed an efficient and sustainable anticorrosion performance. The corrosion resistance was enhanced by 7 orders of magnitude compared with that of bare mild steel substrate. More importantly, the corrosion inhibition efficiency of this coating is still higher than 99.99% even after immersion in NaCl solution for 6 weeks, demonstrating ...

Evidence for pitcher trait-mediated coexistence between sympatric Nepenthes pitcher plant species across geographical scales

ABSTRACTBackground: According to modern coexistence theory, ecologically similar species can coexist if fitness differences between them are small, or niche differences between them are large. However, these predictions have not been tested extensively in real systems and are difficult to examine in traits-based studies.Aims: The aim of our study was, by using the carnivorous pitcher plant genus Nepenthes as a model system, to examine (1) species growth ranks as a proxy for fitness; (2) modern coexistence theory at a geographical scale; (3) evidence for pitcher trait-mediated resource partitioning between sympatric Nepenthes species.Methods: We used growth ranks, obtained from a survey of experienced Nepenthes nursery owners, as a proxy for fitness. Multivariate pitcher-, vegetative- or combined-trait distances, computed from morphometric-trait data from the literature were used as proxies for niche differences. Data on global Nepenthes species-pair sympatry was modelled against these fitness and niche differences.Results: Niche and growth rate differences were positively and negatively correlated with sympatry, respectively, as expected from theory.Conclusion: Our results agree with theory and suggest that fitness differences can be approximated from average species growth. Prey- and microhabitat-resource partitioning, operating through divergent pitcher and vegetative traits respectively, are likely mechanisms that stabilise the coexistence of sympatric Nepenthes species.

Porous Network Microstructures: Femtosecond Laser Direct Writing of Porous Network Microstructures for Fabricating Super‐Slippery Surfaces with Excellent Liquid Repellence and Anti‐Cell Proliferation (Adv. Mater. Interfaces 7/2018)

Porous network microstructures can be directly generated on various polymer surfaces by one-step femtosecond laser writing. Inspired by Nepenthes pitcher plant, a super-slippery surface was fabricated based on the porous PET substrate whose surface was fully covered by interconnected nanopores. The resultant slippery surface can repel various liquids. In addition, such a surface can completely inhibit the cells growth. This is reported by Feng Chen, Xiaoyun Lu and co-workers in article number 1701479.

Predatory dipteran larva contributes to nutrient sequestration in a carnivorous pitcher plant.

The fluids of Nepenthes pitcher plants are habitats to many specialized animals known as inquilines, which facilitate the conversion of prey protein into pitcher-absorbable nitrogen forms such as ammonium. Xenoplatyura beaveri (Diptera: Mycetophilidae) is a predatory dipteran inquiline that inhabits the pitchers of Nepenthes ampullaria Larvae of X. beaveri construct sticky webs over the fluid surface of N. ampullaria to ensnare emerging adult dipteran inquilines. However, the interaction between X. beaveri and its host has never been examined before, and it is not known if X. beaveri can contribute to nutrient sequestration in N. ampullaria. Xenoplatyura beaveri individuals were reared in artificial pitchers in the laboratory on a diet of emergent Tripteroides tenax mosquitoes, and the ammonium concentration of the pitcher fluids was measured over time. Fluid ammonium concentration in tubes containing X. beaveri was significantly greater than those of the controls. Furthermore, fluid ammonium concentrations increased greatly after X. beaveri larvae metamorphosed, although the cause of this increase could not be identified. Our results show that a terrestrial, inquiline predator can contribute significantly to nutrient sequestration in the phytotelma it inhabits, and suggest that this interaction has a net mutualistic outcome for both species.

Fauna Diversity in Pitcher Plants at Setiam Hill, Bintulu, Sarawak, Malaysia

A study was carried out to determine the diversity and enumerate the fauna species related to five pitcher plant species at a selected area in Bukit Setiam Forest, Tatau, Bintulu, Sarawak, Malaysia. At the end of the study, six insect orders together with nematodes and Araneae were detected with different existence abundances and diversity. From the 901 total fauna trapped, 58.82% belonged to the order Hymenoptera, mainly of the ant species, followed by nematodes (21.64%), Diptera (15.87%), Coleoptera (1.66%), Hemiptera (0.89%), Blattaria (0.44%) and finally, Lepidoptera (0.33%) and Araneae (0.33%). Significant differences (p<0.05) in the composition of insect trapped in pitcher plants were observed for the order Hymenoptera, Diptera, Lepidoptera, Hemiptera and even nematodes. Meanwhile, no significant difference was observed for Coleoptera, Blattaria and Araneae. There is a strong relationship between fauna and Nepenthes pitcher either as a prey, predator, a mutualistic relationship or parasites or also for a habitat to live or to reproduce.

A Lubricant-Sandwiched Coating with Long-Term Stable Anticorrosion Performance.

Lubricant-infused surface(s) (LIS) bioinspired by the Nepenthes pitcher plant are receiving enormous attention owing to their excellent hydrophobicity as well as their self-healing ability. Thus, they have been applied as anticorrosion coatings. However, the loss of lubricant mediated by vapor or other liquids deteriorates their functions. Herein, we introduce a lubricant-inserted (sandwiched) microporous triple-layered surface (LIMITS) that prevents the sudden loss of lubricant. The sandwiched lubricant gradually self-secretes toward the surface, resulting in long-term stability even under water. The LIMITS prevented the corrosion of the Fe plate for at least 45 days, which is much superior to a conventional LIS coating. This work opens an avenue for the application of slippery coating materials that are stable under water and will also promote the development of anticorrosion coating in various industries.

Coprophagous features in carnivorous Nepenthes plants: a task for ureases

Most terrestrial carnivorous plants are specialized on insect prey digestion to obtain additional nutrients. Few species of the genus Nepenthes developed mutualistic relationships with mammals for nitrogen supplementation. Whether dietary changes require certain enzymatic composition to utilize new sources of nutrients has rarely been tested. Here, we investigated the role of urease for Nepenthes hemsleyana that gains nitrogen from the bat Kerivoula hardwickii while it roosts inside the pitchers. We hypothesized that N. hemsleyana is able to use urea from the bats’ excrements. In fact, we demonstrate that 15N-enriched urea provided to Nepenthes pitchers is metabolized and its nitrogen is distributed within the plant. As ureases are necessary to degrade urea, these hydrolytic enzymes should be involved. We proved the presence and enzymatic activity of a urease for Nepenthes plant tissues. The corresponding urease cDNA from N. hemsleyana was isolated and functionally expressed. A comprehensive phylogenetic analysis for eukaryotic ureases, including Nepenthes and five other carnivorous plants’ taxa, identified them as canonical ureases and reflects the plant phylogeny. Hence, this study reveals ureases as an emblematic example for an efficient, low-cost but high adaptive plasticity in plants while developing a further specialized lifestyle from carnivory to coprophagy.

Nepenthes pitchers are CO2-enriched cavities, emit CO2 to attract preys

Carnivorous plants of the genus Nepenthes supplement their nutrient deficiency by capturing arthropods or by mutualistic interactions, through their leaf-evolved biological traps (pitchers). Though there are numerous studies on these traps, mostly on their prey capture mechanisms, the gas composition inside them remains unknown. Here we show that, Nepenthes unopened pitchers are CO2-enriched ‘cavities’, when open they emit CO2, and the CO2 gradient around open pitchers acts as a cue attracting preys towards them. CO2 contents in near mature, unopened Nepenthes pitchers were in the range 2500–5000 ppm. Gas collected from inside open N. khasiana pitchers showed CO2 at 476.75 ± 59.83 ppm. CO2-enriched air-streaming through N. khasiana pitchers (at 619.83 ± 4.53 ppm) attracted (captured) substantially higher number of aerial preys compared to air-streamed pitchers (CO2 at 412.76 ± 4.51 ppm). High levels of CO2 dissolved in acidic Nepenthes pitcher fluids were also detected. We demonstrate respiration as the source of elevated CO2 within Nepenthes pitchers. Most unique features of Nepenthes pitchers, viz., high growth rate, enhanced carbohydrate levels, declined protein levels, low photosynthetic capacity, high respiration rate and evolved stomata, are influenced by the CO2-enriched environment within them.

Potential effects of climate change on members of the Palaeotropical pitcher plant family Nepenthaceae.

Anthropogenic climate change is predicted to have profound effects on species distributions over the coming decades. In this paper, we used maximum entropy modelling (Maxent) to estimate the effects of projected changes in climate on extent of climatically-suitable habitat for two Nepenthes pitcher plant species in Borneo. The model results predicted an increase in area of climatically-suitable habitat for the lowland species Nepenthes rafflesiana by 2100; in contrast, the highland species Nepenthes tentaculata was predicted to undergo significant loss of climatically-suitable habitat over the same period. Based on the results of the models, we recommend that research be undertaken into practical mitigation strategies, as approximately two-thirds of Nepenthes are restricted to montane habitats. Highland species with narrow elevational ranges will be at particularly high risk, and investigation into possible mitigation strategies should be focused on them.

Liquid-infused surfaces as a passive method of turbulent drag reduction

Liquid-infused surfaces present a novel, passive method of turbulent drag reduction. Inspired by the Nepenthes Pitcher Plant, liquid-infused surfaces utilize a lubricating fluid trapped within structured roughness to facilitate a slip at the effective surface. The conceptual idea is similar to that of superhydrophobic surfaces, which rely on a lubricating air layer, whereas liquid-infused surfaces use a preferentially wetting liquid lubricant to create localized fluid–fluid interfaces. Maintaining the presence of these slipping interfaces has been shown to be an effective method of passively reducing skin friction drag in turbulent flows. Given that liquid-infused surfaces have only recently been considered for drag reduction applications, there is no available framework to relate surface and lubricant characteristics to any resulting drag reduction. Here we use results from direct numerical simulations of turbulent channel flow over idealized, liquid-infused grooves to demonstrate that the drag reduction achieved using liquid-infused surfaces can be described using the framework established for superhydrophobic surfaces. These insights can be used to explain drag reduction results observed in experimental studies of lubricant-infused surfaces. We also demonstrate how a liquid-infused surface can reduce drag even when the viscosity of the lubricant exceeds that of the external fluid flow, which at first glance can seem counter-intuitive.

Widespread paleopolyploidy, gene tree conflict, and recalcitrant relationships among the carnivorous Caryophyllales.

The carnivorous members of the large, hyperdiverse Caryophyllales (e.g., Venus flytrap, sundews, and Nepenthes pitcher plants) represent perhaps the oldest and most diverse lineage of carnivorous plants. However, despite numerous studies seeking to elucidate their evolutionary relationships, the early-diverging relationships remain unresolved. To explore the utility of phylogenomic data sets for resolving relationships among the carnivorous Caryophyllales, we sequenced 10 transcriptomes, including all the carnivorous genera except those in the rare West African liana family Dioncophyllaceae. We used a variety of methods to infer the species tree, examine gene tree conflict, and infer paleopolyploidy events. Phylogenomic analyses supported the monophyly of the carnivorous Caryophyllales, with a crown age of 68-83 million years. In contrast to previous analyses, we recovered the remaining noncore Caryophyllales as nonmonophyletic, although the node supporting this relationship contained a significant amount of gene tree discordance. We present evidence that the clade contains at least seven independent paleopolyploidy events, previously unresolved nodes from the literature have high levels of gene tree conflict, and taxon sampling influences topology even in a phylogenomic data set, regardless of the use of coalescent or supermatrix methods. Our data demonstrate the importance of carefully considering gene tree conflict and taxon sampling in phylogenomic analyses. Moreover, they provide a remarkable example of the propensity for paleopolyploidy in angiosperms, with at least seven such events in a clade of less than 2500 species.

Dipteran larvae and microbes facilitate nutrient sequestration in the Nepenthes gracilis pitcher plant host.

The fluid-containing traps of Nepenthes carnivorous pitcher plants (Nepenthaceae) are often inhabited by organisms known as inquilines. Dipteran larvae are key components of such communities and are thought to facilitate pitcher nitrogen sequestration by converting prey protein into inorganic nitrogen, although this has never been demonstrated in Nepenthes Pitcher fluids are also inhabited by microbes, although the relationship(s) between these and the plant is still unclear. In this study, we examined the hypothesis of digestive mutualism between N. gracilis pitchers and both dipteran larvae and fluid microbes. Using dipteran larvae, prey and fluid volumes mimicking in situ pitcher conditions, we conducted in vitro experiments and measured changes in available fluid nitrogen in response to dipteran larvae and microbe presence. We showed that the presence of dipteran larvae resulted in significantly higher and faster releases of ammonium and soluble protein into fluids in artificial pitchers, and that the presence of fluid microbes did likewise for ammonium. We showed also that niche segregation occurs between phorid and culicid larvae, with the former fragmenting prey carcasses and the latter suppressing fluid microbe levels. These results clarify the relationships between several key pitcher-dwelling organisms, and show that pitcher communities facilitate nutrient sequestration in their host.

Shrew poo and deranged hamsters

Pitcher plant potties for tree shrews on the go Carnivorous plants derive key nutrients by beckoning, trapping, and digesting insects. One class of these plants, pitcher plants, typically ensnares its prey in a slippery, inescapable, pitcher-shaped leaf full of sticky digestive fluid. But for at least three species of Nepenthes pitcher plants found in northern Borneo, the pitcher acts more like a bowl—specifically, a toilet bowl. In the fog-enshrouded mountain forests where these plants grow, insects are relatively scarce compared with other pitcher plant habitats such as lowland swamps. So the mountain-dwelling plants have repurposed their pitchers as potties, luring mouselike tree shrews, Tupaia montana, with tasty secretions. While licking the plants’ upper rims, the shrews perch with their derrieres hung over the bowl. Some of the shrews then defecate into the pitcher, giving the plants a source of needed nitrogen. Botanist Charles M. Clarke of Monash University first reported

Carnivorous Nutrition in Pitcher Plants (Nepenthes spp.) via an Unusual Complement of Endogenous Enzymes.

Plants belonging to the genus Nepenthes are carnivorous, using specialized pitfall traps called "pitchers" that attract, capture, and digest insects as a primary source of nutrients. We have used RNA sequencing to generate a cDNA library from the Nepenthes pitchers and applied it to mass spectrometry-based identification of the enzymes secreted into the pitcher fluid using a nonspecific digestion strategy superior to trypsin in this application. This first complete catalog of the pitcher fluid subproteome includes enzymes across a variety of functional classes. The most abundant proteins present in the secreted fluid are proteases, nucleases, peroxidases, chitinases, a phosphatase, and a glucanase. Nitrogen recovery involves a particularly rich complement of proteases. In addition to the two expected aspartic proteases, we discovered three novel nepenthensins, two prolyl endopeptidases that we name neprosins, and a putative serine carboxypeptidase. Additional proteins identified are relevant to pathogen-defense and secretion mechanisms. The full complement of acid-stable enzymes discovered in this study suggests that carnivory in the genus Nepenthes can be sustained by plant-based mechanisms alone and does not absolutely require bacterial symbiosis.

Comparative Study of Bacterial Communities in Nepenthes Pitchers and Their Correlation to Species and Fluid Acidity

Pitchers are specialized digestive organs of carnivorous plants which evolved for trapping prey and represent a unique environment harboring hidden diversity of unexplored microbes forming transient hydrolytic microcosms. In this study, the diversity of bacterial communities in the pitcher fluids of seven local Nepenthes found in Thailand was assessed by tagged 16S ribosomal RNA (rRNA) gene amplicon sequencing on an Ion PGM™ platform. A total of 1,101,000 filtered sequences were obtained which were taxonomically classified into 20 phyla, 48 classes, 72 orders, 153 families, and 442 genera while the remainder (1.43%) could not be assigned to any existing taxa. Proteobacteria represented the predominant members in closed pitchers and more diversified bacterial taxa particularly Bacteriodetes and Actinobacteria, showed increasing abundance in open pitchers containing insect bodies. Principal coordinate analysis revealed that distribution of bacterial taxa was not significantly related to the Nepenthes species but strongly correlated to the pH of the pitcher fluids (pH 1.7-6.7). Acidicella was a highly dominant bacterial genus in acidic pitcher fluids while Dyella and Mycobacterium were also common genera in most pitchers. A unique microbial community structure was found in Nepenthes ampullaria which could reflect their adaptation to digest leaf litter, in addition to insect prey. The work revealed the highly unexplored nature of bacterial microcosms in Nepenthes pitcher fluids and provides insights into their community structure in this unique ecological system.

Mechanically Tunable Slippery Behavior on Soft Poly(dimethylsiloxane)-Based Anisotropic Wrinkles Infused with Lubricating Fluid.

We demonstrate a novel technique to fabricate mechanically tunable slippery surfaces using one-dimensional (anisotropic) elastic wrinkles. Such wrinkles show tunable topography (amplitude) on the application of mechanical strain. Following Nepenthes pitcher plants, lubricating fluid infused solid surfaces show excellent slippery behavior for test liquid drops. Therefore, combining the above two, that is, infusing suitable lubricating fluid on elastic wrinkles, would enable us to fabricate mechanically tunable slippery surfaces. Completely stretched (flat) wrinkles have uniform coating of lubricating fluid, whereas completely relaxed (full amplitude) wrinkles have most of the lubricating oil in the wrinkle grooves. Therefore, water drops on completely stretched surface show excellent slippery behavior, whereas on completely relaxed surface they show reduced slippery behavior. Therefore, continuous variation of wrinkle stretching provides reversibly tunable slippery behavior on such a system. Because the wrinkles are one-dimensional, they show anisotropic tunability of slippery behavior depending upon whether test liquid drops slip parallel or perpendicular to the wrinkles.

Bioinspired Omniphobic Coatings with a Thermal Self-Repair Function on Industrial Materials.

Inspired by the wax regeneration ability of plant leaves and the slippery surfaces of the Nepenthes pitcher plants, we have developed a new form of cross-species bioinspired slippery liquid-infused porous surfaces (X-SLIPS) that can self-repair under thermal stimulation even under large-area physical and chemical damage. The performance and underlying mechanism of the thermal-healing property has been studied and characterized in detail. These thermally self-healing omniphobic coatings can be applied to a broad range of metals, plastics, glass, and ceramics of various shapes and show excellent repellency toward aqueous and organic liquids.

Designing Bioinspired Anti-Biofouling Surfaces based on a Superwettability Strategy.

Anti-biofouling surfaces are of high importance owing to their crucial roles in biosensors, biomedical devices, food processing, the marine industry, etc. However, traditional anti-biofouling surfaces based on either the release of biocidal compounds or surface chemical/physical design cannot satisfy the practical demands when meeting real-world complex conditions. The outstanding performances of natural anti-biofouling surfaces motivate the development of new bioinspired anti-biofouling surfaces. Herein, a novel strategy is proposed for rationally designing bioinspired anti-biofouling surfaces based on superwettability. By utilizing the trapped air cushions or liquid layers, Lotus leaf inspired superhydrophobic surfaces, fish scales inspired underwater superoleophobic surfaces, and Nepenthes pitcher plants inspired omniphobic slippery surfaces have been successfully designed as anti-biofouling surfaces to effectively resist proteins, bacteria, cells, and marine organisms. It is believed that these novel superwettability-based anti-biofouling surfaces will bring a new era to both biomedical technology and the marine industry, and will greatly benefit human health and daily life in the near future.

Different pitcher shapes and trapping syndromes explain resource partitioning in Nepenthes species.

Nepenthes pitcher plants display interspecific diversity in pitcher form and diets. This species-rich genus might be a conspicuous candidate for an adaptive radiation. However, the pitcher traits of different species have never been quantified in a comparative study, nor have their possible adaptations to the resources they exploit been tested. In this study, we compare the pitcher features and prey composition of the seven Nepenthes taxa that grow in the heath forest of Brunei (Borneo) and investigate whether these species display different trapping syndromes that target different prey. The Nepenthes species are shown to display species-specific combinations of pitcher shapes, volumes, rewards, attraction and capture traits, and different degrees of ontogenetic pitcher dimorphism. The prey spectra also differ among plant species and between ontogenetic morphotypes in their combinations of ants, flying insects, termites, and noninsect guilds. According to a discriminant analysis, the Nepenthes species collected at the same site differ significantly in prey abundance and composition at the level of order, showing niche segregation but with varying degrees of niche overlap according to pairwise species comparisons. Weakly carnivorous species are first characterized by an absence of attractive traits. Generalist carnivorous species have a sweet odor, a wide pitcher aperture, and an acidic pitcher fluid. Guild specializations are explained by different combinations of morpho-functional traits. Ant captures increase with extrafloral nectar, fluid acidity, and slippery waxy walls. Termite captures increase with narrowness of pitchers, presence of a rim of edible trichomes, and symbiotic association with ants. The abundance of flying insects is primarily correlated with pitcher conicity, pitcher aperture diameter, and odor presence. Such species-specific syndromes favoring resource partitioning may result from local character displacement by competition and/or previous adaptations to geographically distinct environments.