Distinct Functional Groups Research Articles

Understanding scales of movement: animals ride waves and ripples of environmental change

Animal movements are the primary behavioural adaptation to spatiotemporal heterogeneity in resource availability. Depending on their spatiotemporal scale, movements have been categorized into distinct functional groups (e.g. foraging movements, dispersal, migration), and have been studied using different methodologies. We suggest striving towards the development of a coherent framework based on the ultimate function of all movement types, which is to increase individual fitness through an optimal exploitation of resources varying in space and time. We developed a novel approach to simultaneously study movements at different spatiotemporal scales based on the following proposed theory: the length and frequency of animal movements are determined by the interaction between temporal autocorrelation in resource availability and spatial autocorrelation in changes in resource availability. We hypothesized that for each time interval the spatiotemporal scales of moose Alces alces movements correspond to the spatiotemporal scales of variation in the gains derived from resource exploitation when taking into account the costs of movements (represented by their proxies, forage availability NDVI and snow depth respectively). The scales of change in NDVI and snow were quantified using wave theory, and were related to the scale of moose movement using linear mixed models. In support of the proposed theory we found that frequent, smaller scale movements were triggered by fast, small-scale ripples of changes, whereas infrequent, larger scale movements matched slow, large-scale waves of change in resource availability. Similarly, moose inhabiting ranges characterized by larger scale waves of change in the onset of spring migrated longer distances. We showed that the scales of movements are driven by the scales of changes in the net profitability of trophic resources. Our approach can be extended to include drivers of movements other than trophic resources (e.g. population density, density of related individuals, predation risk) and may facilitate the assessment of the impact of environmental changes on community dynamics and conservation.

Understory plant communities and the functional distinction between savanna trees, forest trees, and pines

Although savanna trees and forest trees are thought to represent distinct functional groups with different effects on ecosystem processes, few empirical studies have examined these effects. In particular, it remains unclear if savanna and forest trees differ in their ability to coexist with understory plants, which comprise the majority of plant diversity in most savannas. We used structural equation modeling (SEM) and data from 157 sites across three locations in the southeastern United States to understand the effects of broadleaf savanna trees, broadleaf forest trees, and pine trees on savanna understory plant communities. After accounting for underlying gradients in fire frequency and soil moisture, abundances (i.e., basal area and stem density) of forest trees and pines, but not savanna trees, were negatively correlated with the cover and density (i.e., local-scale species richness) of C4 graminoid species, a defining savanna understory functional group that is linked to ecosystem flammability. In analyses of the full understory community, abundances of trees from all functional groups were negatively correlated with species density and cover. For both the C4 and full communities, fire frequency promoted understory plants directly, and indirectly by limiting forest tree abundance. There was little indirect influence of fire on the understory mediated through savanna trees and pines, which are morefire tolerant than forest trees. We conclude that tree functional identity is an important factor that influences overstory tree relationships with savanna understory plant communities. In particular, distinct relationships between trees and C4 graminoids have implications for grass-tree coexistence and vegetation-fire feedbacks that maintain savanna environments and their associated understory plant diversity.

Hybrid Janus particles based on polymer-modified kaolinite

Janus particles are superior to ordinary Pickering emulsifiers. Widespread industrial usage is however hampered by the restricted accessibility of these polar colloids. Whereas established synthesis protocols that allow for breaking the symmetry of colloid surfaces are laborious and expensive, here we use Janus particles that are based on the ubiquitous layered silicate kaolinite. As a consequence of its crystal structure, the two opposing basal planes, the tetrahedral (TS) and the octahedral (OS) surface, are capped by distinct functional groups. We show that these chemically different basal surfaces allow for facile selective modification making them compatible with e.g. polystyrene (PS) and poly(methyl methacrylate) (PMMA), respectively. The TS was selectively modified by simple cation exchange with poly(2-(dimethylamino)ethyl methacrylate) polycations attached to a polystyrene block while on the OS PMMA chains were covalently anchored via statistically distributed catechol groups. Solid-state NMR proved successful modification, while TGA was provided the amount of polymer bound to both external basal surfaces of kaolinite. Moreover, the selective nature of the modification was proven indirectly by qualitatively comparing the sedimentation stability of suspensions of differently modified samples. These Janus particles with fine-tuned surface tension of the opposing hemispheres were tested on their interfacial activity in solvent-cast films of PS–PMMA blends. The assembly of the Janus particles at the interfaces of the blend was proven by transmission electron microscopy.

Cage the firefly luciferin! – a strategy for developing bioluminescent probes

Bioluminescent imaging (BLI) has been widely applicable in the imaging of process envisioned in life sciences. As the most conventional technique for BLI, the firefly luciferin-luciferase system is exceptionally functional in vitro and in vivo. The state-of-the-art strategy in such a system is to cage the luciferin, in which free luciferin is conjugated with distinctive functional groups, thus accommodating an impressive toolkit for exploring various biological processes, such as monitoring enzymes activity, detecting bioactive small molecules, evaluating the properties of molecular transporters, etc. This review article summarizes the rational design of caged luciferins towards diverse biotargets, as well as their applications in bioluminescent imaging. It should be emphasized that these caged luciferins can stretch out the applications of bioluminescence imaging and shed light upon understanding the pathogenesis of various diseases.

Multicolor electrochromic performance of electroactive poly(amic acid) containing pendant oligoaniline, azobenzene and sulfonic acid groups

A novel electroactive poly(amic acid) (EDA-CON-EPAA) containing oligoaniline pendants, azobenzene and sulfonic acid groups was synthesized by copolymerization. The synergistic interplay of these three distinct functional groups results in a number of interesting and novel properties. The polymer showed photoisomerization induce by irradiation with ultraviolet light and visible light by virtue of azobenzene groups, and also revealed excellent electroactivity in acid, neutral and even in alkaline solutions (pH=12) due to self-doping between oligoaniline and sulfonic acid (and/or carboxylic acid) groups. Moreover, EDA-CON-EPAA displayed acceptable electrochromic performance even in alkaline solutions and multiple colors attributed to the complementary effects of the two chromophores, which greatly enlarged the range of the electrochromic application. The coloration efficiency could still reach 93.8cm2/C (at 700nm) even at pH=10.

Heterosegmented Perturbed-Chain Statistical Associating Fluid Theory as a Robust and Accurate Tool for Modeling of Various Alkanes. 1. Pure Fluids

Heterosegmented molecular models based on statistical associating fluid theory (SAFT) seem to be very promising and robust tools for modeling thermodynamic properties of fluid mixtures. They differ from conventional SAFT-based methodologies as they take into account varying sizes and interactions of segments constituting chain molecules. Those different types of segments can be assigned to functional groups, and hence, the group contribution (GC) method is incorporated in a straightforward manner into the SAFT approach. In this contribution, we applied a heterosegmented version of perturbed-chain SAFT (hs-PC-SAFT) for modeling thermodynamic behavior of a great variety of pure saturated hydrocarbons, including n-alkanes, branched alkanes, and alkyl-monosubstituted cyclohexanes and cyclopentanes. All the investigated compounds were assumed to be composed of 11 distinct functional groups defined within the GC model. The properties under consideration were saturated liquid and vapor density, vapor pressure, e...

Effects of heuweltjies and utilization on vegetation patterns in the Succulent Karoo, South Africa

Heuweltjies are large circular earth mounds created by termites and are important features of the landscape in the Succulent Karoo biome in South Africa. This study demonstrates that heuweltjies and livestock grazing act together to shape vegetation patterns in the region. Using a multifactorial approach, we investigated the combined effects of heuweltjie-induced habitat conditions, grazing pressure and physical disturbance by livestock and native animals as well as the interactions among two distinct plant functional groups, on the composition and cover of vascular plant vegetation. Heuweltjie soils had significantly higher pH-values, finer texture, and higher concentrations of carbon, nitrogen, and phosphorus than those of the surroundings. Neither perennial nor ephemeral cover was different on- and off-mounds. However, species richness, cover of highly palatable plants and livestock grazing pressure were significantly higher between mounds. Grazing pressure generally resulted in a loss of perennial species and a shift to more ephemeral species, probably through the competitive release of annuals and geophytes from perennial plants. We propose that the apparent contradiction between superior nutrient conditions and inferior plant food quality on heuweltjies is caused by a combination of otherwise unfavourable soil properties and historic overgrazing of heuweltjies resulting in local degradation of the vegetation.

Plant litter and soil type drive abundance, activity and community structure of alkB harbouring microbes in different soil compartments.

Alkanes are major constituents of plant-derived waxy materials. In this study, we investigated the abundance, community structure and activity of bacteria harbouring the alkane monooxygenase gene alkB, which catalyses a major step in the pathway of aerobic alkane degradation in the litter layer, the litter-soil interface and in bulk soil at three time points during the degradation of maize and pea plant litter (2, 8 and 30 weeks) to improve our understanding about drivers for microbial performance in different soil compartments. Soil cores of different soil textures (sandy and silty) were taken from an agricultural field and incubated at constant laboratory conditions. The abundance of alkB genes and transcripts (by qPCR) as well as the community structure (by terminal restriction fragment polymorphism fingerprinting) were measured in combination with the concentrations and composition of alkanes. The results obtained indicate a clear response pattern of all investigated biotic and abiotic parameters depending on the applied litter material, the type of soil used, the time point of sampling and the soil compartment studied. As expected the distribution of alkanes of different chain length formed a steep gradient from the litter layer to the bulk soil. Mainly in the two upper soil compartments community structure and abundance patterns of alkB were driven by the applied litter type and its degradation. Surprisingly, the differences between the compartments in one soil were more pronounced than the differences between similar compartments in the two soils studied. This indicates the necessity for analysing processes in different soil compartments to improve our mechanistic understanding of the dynamics of distinct functional groups of microbes.

Evolutionary genomics of dog domestication

We review the underlying principles and tools used in genomic studies of domestic dogs aimed at understanding the genetic changes that have occurred during domestication. We show that there are two principle modes of evolution within dogs. One primary mode that accounts for much of the remarkable diversity of dog breeds is the fixation of discrete mutations of large effect in individual lineages that are then crossed to various breed groupings. This transfer of mutations across the dog evolutionary tree leads to the appearance of high phenotypic diversity that in actuality reflects a small number of major genes. A second mechanism causing diversification involves the selective breeding of dogs within distinct phenotypic or functional groups, which enhances specific group attributes such as heading or tracking. Such progressive selection leads to a distinct genetic structure in evolutionary trees such that functional and phenotypic groups cluster genetically. We trace the origin of the nuclear genome in dogs based on haplotype-sharing analyses between dogs and gray wolves and show that contrary to previous mtDNA analyses, the nuclear genome of dogs derives primarily from Middle Eastern or European wolves, a result more consistent with the archeological record. Sequencing analysis of the IGF1 gene, which has been the target of size selection in small breeds, further supports this conclusion. Finally, we discuss how a black coat color mutation that evolved in dogs has transformed North American gray wolf populations, providing a first example of a mutation that appeared under domestication and selectively swept through a wild relative.

Are sugarcane leaf-detritus well colonized by aquatic macroinvertebrates?

AIM: The aim was to compare the kinetics of decomposition and the colonization of leaf litter of two plant species, the native Talauma ovata (pinha-do-brejo) and the exotic Saccharum officinarum (sugarcane), by aquatic macroinvertebrates; METHODS: From each substrate, three recipients of colonization were taken from a stream, and the specimens identified to the lowest taxonomic level on days 7, 15, 34, 44, 61 and 75. The debris was weighed at the beginning and end of the experiment and determined their cell wall fractions; RESULTS: The coefficients of mineralization indicated higher velocity decay of organic matter refractory in T. ovata. There was no difference in taxonomic structure of macroinvertebrates, between the two substrates, but the community exhibited distinct functional feeding groups in the peak of colonization, with a greater number of shredders in T. ovata. The successive states of decomposition of the two plant detritus showed distinct macroinvertebrate densities; CONCLUSIONS: The amount and state of the plant biomass were important factors influencing the density and diversity of the macroinvertebrate fauna throughout the process of organic decomposition.

Switched recognition and release ability of temperature responsive molecularly imprinted polymers based on magnetic halloysite nanotubes

CoFe2O4/halloysite nanotube magnetic composites (MHNTs) were firstly achieved via a wet impregnation technique, and then a thermal polymerization under (NH4)2S2O8 chain initiation in water was employed to obtain methacrylic acid-functionalized MHNTs (MAA-MHNTs). By decorating the MAA-MHNTs with the temperature responsive monomer N-isopropylacrylamide (NIPAM), a novel temperature responsive molecularly imprinted material based on the obtained NIPAM-MHNTs (TMMIPs) was synthesized by a surface imprinting technique. The results of characterization indicated that the TMMIPs exhibited magnetic sensitivity (Ms = 1.758 emu g−1), magnetic stability (in the pH range of 2.0–8.0), thermal stability (especially below 200 °C) and contained a temperature responsive imprinted layer (the lower critical solution temperature was 33.96 °C). Then the TMMIPs were applied to switched recognition and release of 2,4,5-trichlorophenol molecules (5-TCP) by changing the medium temperature. TMMIPs showed outstanding recognition ability towards the imprinted species under high temperature conditions (such as 60 °C), due to the loss of hydration and a collapsed state of inter-poly(N-isopropylacrylamide), which resulted in the formation of a specific structure between 5-TCP and the polymer network. In contrast, at relatively low temperatures (such as 20 °C), the captured 5-TCP was released from the swelled TMMIPs, which resulted from increasing the distance between 5-TCP and the polymer network. The selective analysis demonstrated the high affinity and selectivity of TMMIPs towards 5-TCP over competitive phenolic compounds, and the specific recognition of binding sites may be based on the distinct size, structure and functional groups of the template molecules.

Temperature responsive polymer brushes with clicked rhodamine B: synthesis, characterization and swelling dynamics studied by spectroscopic ellipsometry

Here, we report on a new temperature responsive polymer brush system with a terminal “click” functionality. Bifunctionalized poly(N-isopropylacrylamide) (PNiPAAm) with distinct functional end groups was synthesized by atom transfer radical polymerization (ATRP) and grafted to a modified silicon substrate. The presence of the active terminal alkyne functionality is validated using an azide-modified rhodamine B (N3-RhB) via copper(I) catalyzed alkyne–azide cycloaddition (CuAAC). The optical properties and swelling dynamics of an N3-RhB modified PNiPAAm brush are analyzed in dry state and in situ by VIS-spectroscopic ellipsometry (SE). The best-fit results are obtained using a Gaussian oscillator model and are confirmed by UV/VIS-spectroscopy. We observed evidence of interactions between the aromatic residues of the dye and the PNiPAAm amide groups, which significantly affect the swelling behavior of the modified polymer brush.

Selective recognition of 2,4,5-trichlorophenol by temperature responsive and magnetic molecularly imprinted polymers based on halloysite nanotubes

Fe3O4/Halloysite nanotube magnetic composites (MHNTs) were firstly prepared via an effective polyol-medium solvothermal method, and then the surface of the MHNTs was endowed with reactive vinyl groups through modification with 3-(methacryloyloxy)propyl trimethoxysilane (MPS). Based on the MHNTs-MPS, temperature responsive and magnetic molecularly imprinted polymers (t-MMIPs) were further synthesized by adopting methacrylic acid (MAA) and N-isopropylacrylamide (NIPAM) as the functional monomer and temperature responsive monomer, respectively. The as-prepared t-MMIPs were characterized by FT-IR, TEM, TGA and VSM, which indicated that the t-MMIPs exhibit magnetic sensitivity (Ms = 2.026 emu g−1), magnetic stability (especially in the pH range of 4.0–8.0) and thermal stability and are composed of an imprinted layer. The molecular interaction between 2,4,5-trichlorophenol (TCP) and MAA was investigated by 1H-NMR spectroscopy and ultraviolet absorption spectroscopy, which suggest that hydrogen bonding may be largely responsible for the recognition mechanism. The t-MMIPs were then applied to selectively recognise and release TCP molecules at 60 °C and 20 °C, respectively. The maximum amount of binding at 60 °C was 197.8 mg g−1 and 122.6 mg g−1 for t-MMIPs and temperature responsive and magnetic non-imprinted polymers (t-MNIPs), respectively. At 20 °C, about 32.3%–42.7% of TCP adsorbed by t-MMIPs was released, whereas 25.3%–39.9% of TCP was released by t-MNIPs. The selective recognition experiments demonstrated the high affinity and selectivity of t-MMIPs towards TCP over competitive phenolic compounds, and the specific recognition of binding sites may be based on the distinct size, structure and functional group to the template molecules.

An expression map for Anopheles gambiae

BackgroundQuantitative transcriptome data for the malaria-transmitting mosquito Anopheles gambiae covers a broad range of biological and experimental conditions, including development, blood feeding and infection. Web-based summaries of differential expression for individual genes with respect to these conditions are a useful tool for the biologist, but they lack the context that a visualisation of all genes with respect to all conditions would give. For most organisms, including A. gambiae, such a systems-level view of gene expression is not yet available.ResultsWe have clustered microarray-based gene-averaged expression values, available from VectorBase, for 10194 genes over 93 experimental conditions using a self-organizing map. Map regions corresponding to known biological events, such as egg production, are revealed. Many individual gene clusters (nodes) on the map are highly enriched in biological and molecular functions, such as protein synthesis, protein degradation and DNA replication. Gene families, such as odorant binding proteins, can be classified into distinct functional groups based on their expression and evolutionary history. Immunity-related genes are non-randomly distributed in several distinct regions on the map, and are generally distant from genes with house-keeping roles. Each immunity-rich region appears to represent a distinct biological context for pathogen recognition and clearance (e.g. the humoral and gut epithelial responses). Several immunity gene families, such as peptidoglycan recognition proteins (PGRPs) and defensins, appear to be specialised for these distinct roles, while three genes with physically interacting protein products (LRIM1/APL1C/TEP1) are found in close proximity.ConclusionsThe map provides the first genome-scale, multi-experiment overview of gene expression in A. gambiae and should also be useful at the gene-level for investigating potential interactions. A web interface is available through the VectorBase website http://www.vectorbase.org/. It is regularly updated as new experimental data becomes available.

Expression pattern of two paralogs of the PI/GLO-like locus during Orchis italica (Orchidaceae, Orchidinae) flower development

The class B MADS-box genes belong to two distinct functional groups: the AP3/DEF-like and the PI/GLO-like sub-families. In orchids, AP3/DEF-like genes are present in four copies, each with a different role in floral organ formation, which is described in the "orchid code" model. Interestingly, the orchid PI/GLO-like genes are present in two copies in Orchidinae, whereas they are described as single copy in the other orchid lineages. The two PI/GLO-like paralogs have site-specific different selective constraints; in addition, they show relaxation of purifying selection when compared to the single-copy lineages. In this study, we present a comparative analysis of the expression patterns of the two PI/GLO-like paralogs, OrcPI and OrcPI2, in floral tissues of Orchis italica in different developmental stages using real-time PCR. The two genes show similar expression profiles in the tissue examined, with differences detectable between immature and mature inflorescence. In all cases, OrcPI2 is expressed at a higher level than OrcPI. Real-time PCR results reveal that the co-expression of the two duplicated loci could have a fully or partially redundant function. The possible evolutionary fate of OrcPI and OrcPI2 is discussed as well as their involvement in ovary development.

All Together Now

Neuroscience Information processing in the brain occurs by the selective recruitment of nerve cells into transient assemblies, whose coordinated patterns of activity underlie different cognitive or behavioral functions. Such assemblies comprise groups of pyramidal neurons that fire together, in determined temporal order. Little is known, however, about how individual neurons are bound into such functional groups. Bahner et al. combined electrophysiological recordings in brain slices with computer modeling to describe a cellular mechanism that may underlie assembly formation in hippocampal networks. By focusing on complexes involved in memory consolidation, they found that pyramidal cells formed two clearly distinct functional groups with respect to their participation in such complexes. Participating pyramidal cells had peculiar properties: They generated antidromic axonal action potentials that were facilitated by axonal GABAA receptors. Classical perisomatic GABAergic inhibition, in contrast, suppressed background activity and ensured that nonparticipating neurons were silenced during these periods. These results provide a mechanism of assembly formation in oscillating networks. Proc. Natl. Acad. Sci. U.S.A. 108 , 10.1073/pnas.1103546108 (2011).

α‐Sulfonyl Succinimides: Versatile Sulfinate Donors in Fe‐Catalyzed, Salt‐Free, Neutral Allylic Substitution

Allyl sulfones are versatile intermediates in organic chemistry. The presence of two distinct functional groups sets the stage for a plethora of subsequent transformations. However, despite these advantages the preparation of regioisomerically enriched sulfones is not easy. The use of sulfinate salts as nucleophiles in substitutions is frequently accompanied by side reactions such as π-bond migration, β-elimination, and so on. Herein we present a preparatively simple way to synthesize a variety of different aryl or alkyl allyl sulfones starting from readily accessible allylic carbonates. By employing aryl or alkyl α-sulfonyl succinimides as sulfinate synthons, mild and regioselective ipso substitution of diverse allylic carbonates was realized.

Patterns of nitrate reductase activity vary according to the plant functional group in a Mediterranean maquis

Since little is known about how the Mediterranean Basin ecosystems are affected by nitrogen deposition, we aimed to understand the use of nitrogen by distinct plant functional groups (PFG: summer semi-deciduous and evergreen sclerophylls) present in the Mediterranean maquis in order to assess which may be more affected by changes in nitrogen availability. The availability of soil inorganic nitrogen, leaf nitrate concentrations and nitrate reductase activity (in vivo and in vitro) were measured during the year in three plant species from each PFG. The patterns of in vitro NRA along the shoot and through the day were also determined. Although summer semi deciduous species occupied soil patches richer in nitrate, their leaf NRA were significantly lower than that of evergreen sclerophylls species. The pattern of nitrate and ammonium availabilities along the year also distinguished the PFG. Results show that each PFG is composed of a number of physiologically similar species. Patterns of NRA varied according to the PFG, which may represent distinct specializations of co-occurring species to access nitrogen. Therefore, the NRA can be used as an indicator of the nitrate availability taking into consideration the time of the year, the plant species and its PFG.

Competitive dynamics in two species of marine phytoplankton under non-equilibrium conditions

Although mathematical models suggest that competition between primary producers in response to dynamical changes in the availability of a limiting nutrient is non-linear, experimental data supporting this basic hypothesis are sparse. Using continuous culture systems with nitrate as a single limiting nutrient, we present results of competition experiments between 2 species of marine phytoplankton, a diatom Thalassiosira pseudonana and a coccolithophore Coccolithus braarudii. These 2 organisms of similar size represent biogeochemically and ecologically distinct functional groups. Consistent with classical resource competition theory, under steady-state nitrate limitation (i.e. continuous flow chemostats), the diatom was outcompeted by the coccolithophore. However, when pulses of nitrate were provided to the chemostats (i.e. non-equilibrium, dynamical conditions) the diatom outcompeted the coccolithophore. The rate of exclusion was a linear function of the fre- quency of nitrate pulses. These results experimentally demonstrate that dynamical nutrient supply allows co-existence of 2 primary producers competing for a single limiting nutrient and may help us to understand phytoplankton succession in the ocean.

Collembola species composition and diversity effects on ecosystem functioning vary with plant functional group identity

The relationship between decomposer diversity and ecosystem functioning is little understood although soils accommodate a significant proportion of worldwide biodiversity. Collembola are among the most abundant and diverse decomposers and are known to modify plant growth. We examined the effects of Collembola species diversity (one, two and three species belonging to different life history groups) and composition on litter decomposition and the performance of plant communities (above- and belowground productivity) of different functional groups (grasses, forbs and legumes). Collembola densities did not increase with diversity indicating niche overlap. Generally, Collembola species composition was a better predictor for ecosystem functioning than Collembola species number with the impacts of Collembola diversity and composition on ecosystem functioning strongly depending on plant functional group identity. Non-linear effects of Collembola diversity on litter decomposition and plant productivity suggest pronounced and context dependent species interactions and feeding habits. Net surface litter decomposition was decreased by Collembola, whereas root litter decomposition was at maximum in the highest Collembola diversity treatment. Forbs benefitted most from the presence of three Collembola species. Similarly, Collembola diversity influenced root depth distribution in a plant functional group specific way: while grass root biomass decreased with increasing Collembola diversity in the upper and lower soil layer, legume root biomass increased particularly in the lower soil layer. Idiosyncratic and context dependent effects of Collembola diversity and composition even in rather simple assemblages of one to three species suggest that changes in Collembola diversity may have unpredictable consequences for ecosystem functioning. The finding that changes in Collembola performance did not directly translate to alterations in ecosystem functioning indicates that response traits do not necessarily conform to effect traits. Distinct plant functional group specific impacts of Collembola diversity on root depth distribution are likely to modify plant competition in complex plant communities and add a novel mechanism how decomposers may affect plant community assembly.