Cation-π Interactions and their Functional Roles in Membrane Proteins

Cation-π interactions arise as a result of strong attractive forces between positively charged entities and the π-electron cloud of aromatic groups. The physicochemical characteristics of cation-π interactions are particularly well-suited to the dual hydrophobic/hydrophilic environment of membrane proteins. As high-resolution structural data of membrane proteins bring molecular features into increasingly sharper view, cation-π interactions are gaining traction as essential contributors to membrane protein chemistry, function, and pharmacology. Here we review the physicochemical properties of cation-π interactions and present several prominent examples which demonstrate significant roles for this specialized biological chemistry.     

Heterogeneous signals in plant–biotic interactions and their applications

<正>Plants have to overcome different types of environment stress including various insect and pathogen attacks during their life cycle. With long-term evolution, plants have developed sophisticated systems to recognize different biotic attacks and initiate an integrated defense network for survival. On the other hand, pathogens and insects have devised multiple strategies to adapt to their host plants. In the past     

Biosynthesis of geraniol and nerol and their β-d-glucosides in Perlargonium graveolens and Rosa dilecta

1. 3R-[2-(14)C]Mevalonate was incorporated into geranyl and neryl beta-d-glucosides in petals of Rosa dilecta in up to 10.6% yield, and the terpenoid part was specifically and equivalently labelled in the moieties derived from isopentenyl pyrophosphate and 3,3-dimethylallyl pyrophosphate. A similar labelling pattern, with incorporations of 0.06-0.1% was found for geraniol or nerol formed in leaves of Pelargonium graveolens The former results provide the best available evidence for the mevalonoid route to regular monoterpenes in higher plants. 2. Incorporation studies with 3RS-[2-(14)C,(4R)-4-(3)H(1)]-mevalonate and its (4S)-isomer showed that the pro-4R hydrogen atom of the precursor was retained and the pro-4S hydrogen atom was eliminated in both alcohols and both glucosides. These results suggest that the correlation of retention of the pro-4S hydrogen atom of mevalonate with formation of a cis-substituted double bond, such as has been found in certain higher terpenoids, does not apply to the biosynthesis of monoterpenes. It is proposed that either nerol is derived from isomerization of geraniol or the two alcohols are directly formed by different prenyltransferases. Possible mechanisms for these processes are discussed. 3. The experiments with [(14)C,(3)H]mevalonate also show that in these higher plants, as has been previously found in animal tissue and yeast, the pro-4S hydrogen atom of mevalonate was lost in the conversion of isopentenyl pyrophosphate into 3,3-dimethylallyl pyrophosphate.     

Do plants adjust their sex allocation and secondary sexual morphology in response to their neighbours?

Background and aims

Changes in the sex allocation (i.e. in pollen versus seed production) of hermaphroditic plants often occur in response to the environment. In some homosporous ferns, gametophytes choose their gender in response to chemical cues sent by neighbours, such that spores develop as male gametophytes if they perceive a female or hermaphrodite nearby. Here it is considered whether a similar process might occur in the androdioecious angiosperm species Mercurialis annua, in which males co-occur with hermaphrodites; previous work on a Spanish population of M. annua found that individuals were more likely to develop as males at high density.

Methods

Using a novel approach to treat plants with leachate from pots containing males or hermaphrodites of M. annua, the hypothesis that individuals assess their mating opportunities, and adjust their sex expression accordingly, was tested through an exchange of chemical cues through the soil.

Key Results

For the population under study, from Morocco, no evidence was found for soil-signal-dependent sex expression: neither sex ratios nor sex allocation differed among experimental treatments.

Conclusions

The results imply either that the Moroccan population under study behaves differently from that previously studied in Spain (pointing to potential geographical variation in plasticity for sex expression), or that our method failed to capture the signals used by M. annua for adjustment of sex expression.     

Exoglucanases fromZea mays L. seedlings: their role inβ-D-glucan hydrolysis and their potential role in extension growth

Exoglucanases of corn seedlings were examined and evaluated in terms of their participation in the hydrolysis of cell-wall β-D-glucan and their possible role in extension growth. An exo-β-1,3-glucanase (EC 3.2.1.58), a component of the protein dissociated from isolated wall by use of high salt solutions, was purified using gel-filtration and ion-exchange chromatography. The purified enzyme hydrolyzed a number of polymeric and oligosaccharide substrates, including those of mixedlinkage, and their direct conversion to monosaccharide was evidence that the enzyme was capable of hydrolyzing both β1–4 and β1–3 linkages. The enzyme was considerably more active toward glucan that had been previously hydrolyzed by a cell-wall endo-β-D-glucanase. Similarly, the capacity of the purified exo-β-D-glucanase to degrade isolated wall was enhanced by more than 60% when the wall had been previously treated with the endoenzyme. The exo-β-D-glucanase did not exhibit growth-promoting properties nor was its activity, measured in vivo, enhanced by auxin. Another glucanase was obtained from the soluble fraction of seedling homogenates. It functioned strictly as a β-glucosidase and did not appear to participate in the hydrolysis of wall β-D-glucan.     

Ecosystem carbon stocks and their changes in China’s grasslands

The knowledge of carbon (C) stock and its dynamics is crucial for understanding the role of grassland ecosystems in China’s terrestrial C cycle. To date, a comprehensive assessment on C balance in China’s grasslands is still lacking. By reviewing published literature, this study aims to evaluate ecosystem C stocks (both vegetation biomass and soil organic C) and their changes in China’s grasslands. Our results are summarized as follows: (1) biomass C density (C stock per area) of China’s grasslands differed greatly among previous studies, ranging from 215.8 to 348.1 g C m⁻² with an average of 300.2 g C m⁻². Likewise, soil C density also varied greatly between 8.5 and 15.1 kg C m⁻². In total, ecosystem C stock in China’s grasslands was estimated at 29.1 Pg C. (2) Both the magnitude and direction of ecosystem C changes in China’s grasslands differed greatly among previous studies. According to recent reports, neither biomass nor soil C stock in China’s grasslands showed a significant change during the past 20 years, indicating that grassland ecosystems are C neutral. (3) Spatial patterns and temporal dynamics of grassland biomass were closely correlated with precipitation, while changes in soil C stocks exhibited close associations with soil moisture and soil texture. Human activities, such as livestock grazing and fencing could also affect ecosystem C dynamics in China’s grasslands.     

What counts? Volunteers and their organisations in the recording and monitoring of biodiversity

There is a pressing need for volunteer amateur naturalists to participate in data collection for biodiversity monitoring programmes in Europe. It is being addressed in some countries, but less so in others. This paper discusses the results from qualitative research using semi-structured interviews, focus groups and participant observation within nine Participatory Monitoring Network (PMN) organisations in six European countries. The paper examines the features that facilitate recruitment, retention and motivations of volunteers to participate in biodiversity monitoring, including the social and cultural milieus in which they operate. The paper concludes that volunteers place a high degree of significance on their social experience within PMNs. Successful creation and management of PMNs thus requires that similar levels of attention be paid to social aspects of the organisation as are paid to the generation and management of data.     

Vacuolar membrane structures and their roles in plant–pathogen interactions

Plant Molecular Biology - Short review focussing on the role and targeting of vacuolar substructure in plant immunity and pathogenesis. Plants lack specialized immune cells, therefore each plant...     

Cl? and K+ channels and their role in primary brain tumour biology

Profound cell volume changes occur in primary brain tumours as they proliferate, invade surrounding tissue or undergo apoptosis. These volume changes are regulated by the flux of Cl⁻ and K⁺ ions and concomitant movement of water across the membrane, making ion channels pivotal to tumour biology. We discuss which specific Cl⁻ and K⁺ channels are involved in defined aspects of glioma biology and how these channels are regulated. Cl⁻ is accumulated to unusually high concentrations in gliomas by the activity of the NKCC1 transporter and serves as an osmolyte and energetic driving force for volume changes. Cell volume condensation is required as cells enter M phase of the cell cycle and this pre-mitotic condensation is caused by channel-mediated ion efflux. Similarly, Cl⁻ and K⁺ channels dynamically regulate volume in invading glioma cells allowing them to adjust to small extracellular brain spaces. Finally, cell condensation is a hallmark of apoptosis and requires the concerted activation of Cl⁻ and Ca²⁺-activated K⁺ channels. Given the frequency of mutation and high importance of ion channels in tumour biology, the opportunity exists to target them for treatment.     

Bioactive chemicals and biological—biochemical activities and their functions in rhizospheres of wetland plants

Wetland soils provide anoxia-tolerant plants with access to ample light, water, and nutrients. Intense competition, involving chemical strategies, ensues among the plants. The roots of wetland plants are prime targets for root-eating pests, and the wetland rhizosphere is an ideal environment for many other organisms and communities because it provides water, oxygen, organic food, and physical protection. Consequently, the rhizosphere of wetland plants is densely populated by many specialized organisms, which considerably influence its biogeochemical functioning. The roots protect themselves against pests and control their rhizosphere organisms by bioactive chemicals, which often also have medicinal properties. Anaerobic metabolites, alkaloids, phenolics, terpenoids, and steroids are bioactive chemicals abundant in roots and rhizospheres in wetlands. Bioactivities include allelopathy, growth regulation, extraorganismal enzymatic activities, metal manipulation by phytosiderophores and phytochelatines, various pest-control effects, and poisoning. Complex biological-biochemical interactions among roots, rhizosphere organisms, and the rhizosphere solution determine the overall biogeochemical processes in the wetland rhizosphere and in the vegetated wetlands. To comprehend how wetlands really function, it is necessary to understand these interactions. Such understanding requires further research.     

Advances in proteomic technologies and their scope of application in understanding plant–pathogen interactions

Proteomics, one of the major tools of ‘omics’ is evolving phenomenally since the development and application of two-dimensional gel electrophoresis coupled with mass spectrometry at the end of twentieth century. However, the adoption and application of advanced proteomic technologies in understanding plant–pathogen interactions are far less, when compared to their application in other related fields of systems biology. Hence, this review is diligently focused on the advances in various proteomic approaches and their gamut of applications in different facets of phyto-pathoproteomics. Especially, the scope and application of proteomics in understanding fundamental concepts of plant–pathogen interactions such as identification of pathogenicity determinants (effector proteins), disease resistance proteins (resistance and pathogenesis-related proteins) and their regulation by post-translational modifications have been portrayed. This review, for the first time, presents a critical appraisal of various proteomic applications by assessing all phyto-pathoproteomics-related research publications that were published in peer-reviewed journals, during the period 2000–2016. This assessment has revealed the present status and contribution of proteomic applications in different categories of phyto-pathoproteomics, namely, cellular components, host–pathogen interactions, model and non-model plants, and utilization of different proteomic approaches. Comprehensively, the analysis highlights the burgeoning application of global proteome approaches in various crop diseases, and demand for acceleration in deploying advanced proteomic technologies to thoroughly comprehend the intricacies of complex and rapidly evolving plant–pathogen interactions.     

Transglutaminases and their substrates in biology and human diseases: 50 years of growing

Transglutaminase is an enzyme able to play more than one enzymatic action, acting on a variety of different substrates. The growth of knowledge about the members of the enzyme transglutaminase’s family and its substrates since the last 50 years indicates a large interest and curiosity about this protein, whose function and structure was, but still is, an important object of research. On the other hand, the involvement in a number of human diseases together with the lack of knowledge about the biological functions played by some of the most studied members of this family, make this enzyme a fascinating field of study. The history of this enzyme and its substrates, whose cross-linking action was reported for the first time 50 years ago, suggests that an effort to increase knowledge and communication among researchers is required. To achieve this important result, 10 years ago an internet web page called worldwide happening around transglutaminase (WHAT) was created. Driven by these experiences, novel points-of-view to look at Transglutaminase and its substrates may be identified.     

Farmers’ perception of termites in agriculture production and their indigenous utilization in Northwest Benin

Background

Although termites are considered as agricultural pests, they play an important role in maintaining the ecosystem. Therefore, it matters to investigate the farmers’ perception of the impacts of the termites on the agriculture and their indigenous utilization.

Methods

A semi-structured questionnaire was used to interview 94 farmers through 10 villages of Atacora department, in the northwestern region of Benin, to obtain information for the development of successful strategies of termite management and conservation. Their perceptions on the importance and management of termites along with the indigenous nomenclature and utilization of termite mounds were assessed. Termite species identified by farmers were collected and preserved in 80% alcohol for identification.

Results

Eight crops were identified by farmers as susceptible to termites with maize, sorghum, and yam as being the most susceptible. According to farmers, the susceptibility to termites of these crops is due to their high-water content and sweet taste. A total of 27 vernacular names of termites were recorded corresponding to 10 species, Amitermes evuncifer, Macrotermes subhyalinus, and Trinervitermes oeconomus being the most damaging termite species. All the names given to termite species had a meaning. The drought was identified by farmers as the main factor favouring termite attacks. Demolition of termite mounds in the fields was the most commonly reported control method. Salt and other pesticides were commonly used by farmers to protect stored farm products. The lack of effective control methods is the main constraint for termite management. In northwestern Benin, farmers reported different purpose utilizations of termite mounds and termites.

Conclusions

The study has shown that farmers perceived termites as pests of several agricultural crops and apply various indigenous control practices whose efficiency need to be verified. Utilization of termites and termite mound soil as food and medicinal resources underlines the need for a more focused approach to termite control for the conservation of non-pest termite species. The sensitization of farmers on the importance of termites as well as the development of an integrated control method to combat termite pests proved necessary.

     

Expression of TNF-α and IL-1β in splenic dendritic cells and their serum levels in mouse sparganosis

Sparganosis is a tissue invading helminthiasis infecting intermediate hosts, including humans. Strong immune responses are expected to occur in early phases of infection. Thus, we investigated cytokine expressions in splenic dendritic cells and in sera after experimental infection of mice. In splenic dendritic cells, TNF-α and IL-1β expression peaked at week 1 and week 3 post-infection (PI), respectively, and also early phase (week 2 PI) depressed cytokine expression was noticed. Serum IL-1β concentration increased significantly at week 2 PI and peaked at week 6 PI, and that of TNF-α peaked at week 6 PI. These results showed that pro-inflammatory cytokines, TNF-α and IL-1β, are chronologically regulated in mouse sparganosis.     

African trypanosomes in the 21st century: what is their future in science and in health?

The African trypanosomes remain well recognised for their role as an interesting model eukaryote for basic science, but are loosing ground in their ability to contribute to understanding common cellular mechanisms. At the same time, the diseases they cause remain as prevalent as ever, but appear increasingly irrelevant in their wider medical, social, economic and political context. What can be done to keep trypanosome biology relevant and vigorous in the 21st century?     

Harmful cyanobacteria and their cyanotoxins in Egyptian fresh waters – state of knowledge and research needs

Cyanobacterial blooms have increased in freshwater ecosystems worldwide in the last century, mostly resulting from eutrophication and climate change. These blooms represent serious threats to environmental and human health because of the production of harmful metabolites, called cyanotoxins. Like many countries, Egypt has been plagued with cyanobacterial blooms in most water sources, including the Nile River, irrigation canals, lakes and fishponds. However, the data about cyanotoxins produced in these blooms are limited. Only two types of cyanotoxins, microcystins and cylindrospermopsin, have been identified and characterised, mainly from Microcystis and Cylindrospermopsis blooms. The data revealed the presence of microcystins in raw and treated drinking waters at concentrations (0.05–3.8 µg l^?1), exceeding the WHO limit (1 µg l^?1) in some drinking water treatment plants. In addition, Nile tilapia Oreochromis niloticus caught from ponds containing heavy cyanobacterial blooms have accumulated considerable amounts of cyanotoxins in their edible tissues. The data presented here could be the catalyst for the establishment of a monitoring and management programme for harmful cyanobacteria and their cyanotoxins in Egyptian fresh waters. This review also elucidates the important research gaps and possible avenues for future research on cyanobacterial blooms and cyanotoxins in Egypt.