The mechanism of host-induced germination in root parasitic plants

Chemical signals known as strigolactones (SLs) were discovered more than 50 years ago as host-derived germination stimulants of parasitic plants in the Orobanchaceae. Strigolactone-responsive germination is an essential adaptation of obligate parasites in this family, which depend upon a host for survival. Several species of obligate parasites, including witchweeds (Striga, Alectra spp.) and broomrapes (Orobanche, Phelipanche spp.), are highly destructive agricultural weeds that pose a significant threat to global food security. Understanding how parasites sense SLs and other host-derived stimulants will catalyze the development of innovative chemical and biological control methods. This review synthesizes the recent discoveries of strigolactone receptors in parasitic Orobanchaceae, their signaling mechanism, and key steps in their evolution.

A family of receptors that evolved in the Orobanchaceae family enable seeds of parasitic plants to sense strigolactones from a nearby host root and germinate.

Advances

• Strigolactone perception by parasite seed is mediated by a clade of neofunctionalized KAI2d proteins that evolved from a receptor that mediates karrikin responses in other plants.
• KAI2d proteins use a similar mechanism to perceive SLs as D14, which mediates growth responses to SLs in nonparasites, but activate different signaling pathways.
• Crystal structure analyses and chemical probes reveal features of KAI2d ligand-binding pockets that contribute to their specificity.

     

Adaptation of the parasitic plant lifecycle: germination is controlled by essential host signaling molecules

Parasitic plants are plants that connect with a haustorium to the vasculature of another, host, plant from which they absorb water, assimilates, and nutrients. Because of this parasitic lifestyle, parasitic plants need to coordinate their lifecycle with that of their host. Parasitic plants have evolved a number of host detection/host response mechanisms of which the germination in response to chemical host signals in one of the major families of parasitic plants, the Orobanchaceae, is a striking example. In this update review, we discuss these germination stimulants. We review the different compound classes that function as germination stimulants, how they are produced, and in which host plants. We discuss why they are reliable signals, how parasitic plants have evolved mechanisms that detect and respond to them, and whether they play a role in host specificity. The advances in the knowledge underlying this signaling relationship between host and parasitic plant have greatly improved our understanding of the evolution of plant parasitism and are facilitating the development of more effective control measures in cases where these parasitic plants have developed into weeds.

Root parasitic plants grow on the roots of other plants and germinate only in the presence of that host, on which they completely depend, through the perception of host presence signaling molecules called germination stimulants.

Outstanding questions

• Have we overlooked the role of germination stimulants in facultative parasites?
• What is the biological relevance of the observation that many plant species produce and secrete a range of different strigolactones?
• Have parasitic plants evolved mechanisms to compensate for low phosphorus availability, a condition that stimulates their germination?
• What is the contribution of the HTL strigolactone receptors to host specificity in parasitic plants or does downstream signaling play a role?
• What other, nonstrigolactone, germination stimulants can parasitic plants respond to and does this require adaptation in the HTL receptors?
• What is the role of germination and underlying mechanism in the rapid adaptation of (orobanchaceous) parasitic plants to a new host?

     

Elucidating cryptic dynamics of Theileria communities in African buffalo using a high‐throughput sequencing informatics approach

1. Increasing access to next‐generation sequencing (NGS) technologies is revolutionizing the life sciences. In disease ecology, NGS‐based methods have the potential to provide higher‐resolution data on communities of parasites found in individual hosts as well as host populations.
2. Here, we demonstrate how a novel analytical method, utilizing high‐throughput sequencing of PCR amplicons, can be used to explore variation in blood‐borne parasite (Theileria—Apicomplexa: Piroplasmida) communities of African buffalo at higher resolutions than has been obtained with conventional molecular tools.
3. Results reveal temporal patterns of synchronized and opposite fluctuations of prevalence and relative abundance of Theileria spp. within the host population, suggesting heterogeneous transmission across taxa. Furthermore, we show that the community composition of Theileria spp. and their subtypes varies considerably between buffalo, with differences in composition reflected in mean and variance of overall parasitemia, thereby showing potential to elucidate previously unexplained contrasts in infection outcomes for host individuals.
4. Importantly, our methods are generalizable as they can be utilized to describe blood‐borne parasite communities in any host species. Furthermore, our methodological framework can be adapted to any parasite system given the appropriate genetic marker.
5. The findings of this study demonstrate how a novel NGS‐based analytical approach can provide fine‐scale, quantitative data, unlocking opportunities for discovery in disease ecology.

     

Optimal transportation theory for species interaction networks

1. Observed biotic interactions between species, such as in pollination, predation, and competition, are determined by combinations of population densities, matching in functional traits and phenology among the organisms, and stochastic events (neutral effects).
2. We propose optimal transportation theory as a unified view for modeling species interaction networks with different intensities of interactions. We pose the coupling of two distributions as a constrained optimization problem, maximizing both the system''s average utility and its global entropy, that is, randomness. Our model follows naturally from applying the MaxEnt principle to this problem setting.
3. This approach allows for simulating changes in species relative densities as well as to disentangle the impact of trait matching and neutral forces.
4. We provide a framework for estimating the pairwise species utilities from data. Experimentally, we show how to use this framework to perform trait matching and predict the coupling in pollination and host–parasite networks.

The coupling between species in a species interaction network can be modeled using optimal transportation. As an application of the MaxEnt principle, it jointly maximizes interaction utility and entropy. This allows for anticipating how the interaction coupling can change when species abundances change.     

Brain organoids: an ensemble of bioassays to investigate human neurodevelopment and disease

AbstractUnderstanding etiology of human neurological and psychiatric diseases is challenging. Genomic changes, protracted development, and histological features unique to human brain development limit the disease aspects that can be investigated using model organisms. Hence, in order to study phenotypes associated with human brain development, function, and disease, it is necessary to use alternative experimental systems that are accessible, ethically justified, and replicate human context. Human pluripotent stem cell (hPSC)-derived brain organoids offer such a system, which recapitulates features of early human neurodevelopment in vitro, including the generation, proliferation, and differentiation of neural progenitors into neurons and glial cells and the complex interactions among the diverse, emergent cell types of the developing brain in three-dimensions (3-D). In recent years, numerous brain organoid protocols and related techniques have been developed to recapitulate aspects of embryonic and fetal brain development in a reproducible and predictable manner. Altogether, these different organoid technologies provide distinct bioassays to unravel novel, disease-associated phenotypes and mechanisms. In this review, we summarize how the diverse brain organoid methods can be utilized to enhance our understanding of brain disorders.Facts

• Brain organoids offer an in vitro approach to study aspects of human brain development and disease.
• Diverse brain organoid techniques offer bioassays to investigate new phenotypes associated with human brain disorders that are difficult to study in monolayer cultures.
• Brain organoids have been particularly useful to study phenomena and diseases associated with neural progenitor morphology, survival, proliferation, and differentiation.

Open question

• Future brain organoid research needs to aim at later stages of neurodevelopment, linked with neuronal activity and connections, to unravel further disease-associated phenotypes.
• Continued improvement of existing organoid protocols is required to generate standardized methods that recapitulate in vivo-like spatial diversity and complexity.

Subject terms: Neuroscience, Neurological disorders

     

Contemporary proteomic strategies for cysteine redoxome profiling

Protein cysteine residues are susceptible to oxidative modifications that can affect protein functions. Proteomic techniques that comprehensively profile the cysteine redoxome, the repertoire of oxidized cysteine residues, are pivotal towards a better understanding of the protein redox signaling. Recent technical advances in chemical tools and redox proteomic strategies have greatly improved selectivity, in vivo applicability, and quantification of the cysteine redoxome. Despite this substantial progress, still many challenges remain. Here, we provide an update on the recent advances in proteomic strategies for cysteine redoxome profiling, compare the advantages and disadvantages of current methods and discuss the outstanding challenges and future perspectives for plant redoxome research.

Current cysteine redoxome profiling can characterize systematically diverse oxidative posttranslational modifications

Advances

• The chemical toolbox for Cys redoxome profiling has extensively expanded.
• Advanced chemoproteomic platforms have been applied to target specific Cys oxidative posttranslational modifications (OxiPTMs).
• Various reductomic workflows have been widely implemented for reversible Cys OxiPTMs quantification.
• Workflows have been integrated to measure the occupancy of multiple OxiPTMs simultaneously.
• Disulfide-based traps enable the in situ profiling for –SOH sites.

     

Structural requirements of strigolactones for germination induction and inhibition of Striga gesnerioides seeds

Key message

Structure–activity relationship studies of strigolactones and Striga gesnerioides seed germination revealed strict structural requirements for germination induction and a new function of the plant hormones as germination inhibitors.

Abstract

Stereoisomers of the naturally occurring strigolactones, strigol, sorgolactone, orobanchol, sorgomol and 5-deoxystrigol, 36 in total, were prepared and screened for the ability to induce and/or inhibit the germination of Striga hermonthica and Striga gesnerioides seeds collected from mature plants that parasitized on sorghum and cowpea, respectively. All of the compounds induced S. hermonthica seed germination, albeit displayed differential activities. On the other hand, only a limited number of the compounds induced significant germination in S. gesnerioides, thus indicating strict structural requirements. Strigolactones inducing high germination in S. gesnerioides induced low germination in S. hermonthica. Strigolactones with the same configuration at C3a, C8b and C2′ as that in 5-deoxystrigol (9a) induced high germination of S. hermonthica seeds, but most of them inhibited the germination of S. gesnerioides. The differential response of S. gesnerioides to strigolactones may play an important role in the survival of the species. However, the compounds could be used as means of control if mixed cropping of cowpea and sorghum is adopted.     

Enhancement of solubilization and biodegradation of petroleum by biosurfactant from Rhodococcus erythropolis HX-2

Abstract

The demand to repair areas contaminated with hydrocarbon products has led to the development of new technologies for the treatment of contaminants in an unconventional method, that is, no physical or chemical methods are used. Biosurfactants are amphiphilic biomolecules produced by microorganisms that can be used in environments contaminated by petroleum products due to their unexceptionable tensile properties. Petroleum degrading strain Rhodococcus erythropolis HX-2 was found to be an effective producer of biosurfactants. The resulting biosurfactant (named NK) exhibits high physicochemical properties in terms of surface activity. It is capable of reducing surface tension from 54.99 to 28.89?mN/m and critical micelle concentration (CMC) is 100?mg/L. NK was found to be a substitute for chemically synthesized surfactants because of its higher solubilization efficiency for petroleum and polycyclic aromatic hydrocarbons, superior to SDS, Tween 80, Triton X-100 and Rhamnolipid (a wide used biosurfactant). In addition, it exhibits favorable emulsion stability over a wide range of pH (3–10), temperature (20–100?°C) and salinity ranges (5–20?g/L). It was found that the addition of biosurfactant can improve the efficiency of petroleum degradation, therefore it has potential applications in bioremediation.

• Highlights

• Rhodococcus erythropolis HX-2 is an effective petroleum degrading strain.

• HX-2 is a potential source of biosurfactant production.

• The biosurfactant NK reduces surface tension and exhibits high emulsification activity.

• The biosurfactant NK is effective over a wide range of temperatures, pH and salinity.

• The biosurfactant NK shows high solubilization efficiency for petroleum as well as polycyclic aromatic hydrocarbons.

     

Functional Characterization and Comparison of Plasmodium falciparum Proteins as Targets of Transmission-blocking Antibodies

1. Download : Download high-res image (68KB)
2. Download : Download full-size image

Highlights

• •Characterization of 12 proteins from across the P. falciparum sexual-stages as possible TBV targets.
• •Heterologously expressed recombinant proteins recapitulate native parasite epitopes.
• •Some recombinant proteins exhibit immunoreactivity when tested against sera from individuals from malaria-endemic Burkina Faso and Mali.
• •Purified IgG against the antigen enolase moderately inhibits parasite development in the mosquito midgut.

     

Multi-omic Characterization of the Mode of Action of a Potent New Antimalarial Compound,JPC-3210, Against Plasmodium falciparum

1. Download : Download high-res image (134KB)
2. Download : Download full-size image

Highlights

• •Multi-omics analysis on mode of action of novel antimalarial, JPC-3210
• •JPC-3210 has rapid parasite killing kinetics.
• •Metabolomics and peptidomics demonstrated JPC-3210 inhibits hemoglobin digestion.
• •Proteomics demonstrated JPC-3210 enriches for translation regulation proteins.

     

Immune Signature Against Plasmodium falciparum Antigens Predicts Clinical Immunity in Distinct Malaria Endemic Communities

1. Download : Download high-res image (146KB)
2. Download : Download full-size image

Highlights

• •A predictive modelling framework has been established to analyze IgG antibody responses against a large panel of P. falciparum-specific antigens to identify a specific antigen signature of NAI.
• •An individual's immune status can be accurately predicted by measuring IgG responses against a small set of 15 defined parasite antigens.
• •Proteins identified in the 15-antigen signature represent potential candidates for next-generation malaria vaccines or biomarkers for monitoring the impact of malaria interventions.
• •The developed predictive framework can be adapted for developing novel surveillance and intervention tools for other infectious diseases.

     

Sex differences in progression of diabetic nephropathy in OVE26 type 1 diabetic mice

AimsOVE26 mice (FVB background), genetically overexpressing calmodulin in pancreatic beta cells, develop early onset type 1 diabetes, leading to progressive diabetic nephropathy (DN), with features of established human DN. The role of gender in characteristics of renal lesions has remained unexplored.MethodsMale and female OVE26 mice were compared to age and sex matched wild-type, nondiabetic FVB mice at ages of 4, 12, 24 and 36 weeks. Nephropathy was examined by measuring urine albumin-to-creatinine ratio, histopathology, expression of pathological markers and immunochemistry in the same cohort of mice.ResultsProgression of diabetic kidney disease was evident first in the OVE26 glomerulus, initially as mesangial matrix expansion at 4 weeks followed by loss of podocytes, glomerular volume expansion and severe albuminuria at 12 weeks. Tubule dilation and initiation of interstitial fibrosis did not become significant until 24 weeks. T-lymphocyte infiltration into the renal parenchyma appeared at 36 weeks. OVE26 female mice developed more advanced DN than male OVE26 mice, such as more severe albuminuria, greater podocyte loss, additional fibrosis and significantly more inflammatory cell infiltration. The female OVE26 mice had lowest level of plasma estradiol in all 36 weeks old mice, as well as renal estrogen receptors.ConclusionsThis demonstration of the role of gender, combined with the detailed characterization of DN progression illustrates the value of OVE26 mice for understanding gender effects on DN and provides the basis for researchers to better select the age and sex of OVE26 mice in future studies of type 1 DN.Research in contextWhat is already known about this subject?

• •OVE26 mice, genetically overexpressing calmodulin in pancreatic beta cells, develop early onset type 1 diabetes.
• •OVE26 mice are a widely used and valuable rodent model which develop severe, progressive diabetic nephropathy, with features of established human diabetic nephropathy.

What is the key question?

• •Does gender play a role in determining characteristics of renal lesions and severity of nephropathy?

What are the new findings?

• •Female OVE26 mice had more severe albuminuria, greater podocyte loss.
• •Female OVE26 mice had additional fibrosis and significantly more inflammatory cell infiltration.
• •Diabetes induced reductions in estradiol levels and renal estrogen receptors may be responsible for the female sensitization to DN in OVE26 mice.

How might this impact on clinical practice in the foreseeable future?

• •Our findings provide the basis for researchers to better select the age and sex of OVE26 mice in future studies of type 1 DN.

     

Mechanisms of resistance and virulence in parasitic plant–host interactions

Parasitic plants pose a major biotic threat to plant growth and development and lead to losses in crop productivity of billions of USD annually. By comparison with “normal” autotrophic plants, parasitic plants live a heterotrophic lifestyle and rely on water, solutes and to a greater (holoparasitic plants) or lesser extent (hemiparasitic plants) on sugars from other host plants. Most hosts are unable to detect an infestation by plant parasites or unable to fend off these parasitic invaders. However, a few hosts have evolved defense strategies to avoid infestation or protect themselves actively post-attack often leading to full or partial resistance. Here, we review the current state of our understanding of the defense strategies to plant parasitism used by host plants with emphasis on the active molecular resistance mechanisms. Furthermore, we outline the perspectives and the potential of future studies that will be indispensable to develop and breed resistant crops.

Some plants are able to recognize parasitic plants as attacking pathogens and can fend them off by inducing defense responses.

Advances

• Receptor proteins have been discovered in host plants (i.e. sunflower, tomato, or cowpea) that detect parasitic plants as an invading pathogen and further induce plant immunity and resistance responses in hosts leading to a parasite rejection.
• Molecular patterns exist in parasitic plants that can be specifically detected by host plant receptors.
• The host plant receptors require co-receptors and signaling components (i.e. BAK1, SOBIR1, etc.) also known from plant immunity against microbes.
• Parasitic plants evolved strategies to circumvent and to suppress host plant immunity, i.e. by manipulating host cells with siRNAs or proteins that act as effectors.
• Similar to the interaction of plants with microbial pathogens, elements of PTI and ETI can be both observed in plant–parasitic plant interactions.

     

High-dimensional Cytometry (ExCYT) and Mass Spectrometry of Myeloid Infiltrate in Clinically Localized Clear Cell Renal Cell Carcinoma Identifies Novel Potential Myeloid Targets for Immunotherapy

1. Download : Download high-res image (236KB)
2. Download : Download full-size image

Highlights

• •Using ExCYT, genomics, and Mass Spectrometry, we were able to uncover immune cell marker alterations that provide new insight into the biology of early stage ccRCC.
• •Among the CD45⁺ population, we observed a high level of myeloid cell infiltration in treatment-naïve ccRCC tissues.

     

Indole-derived water-soluble N,O bi-dentate ligand-based mononuclear transition metal complexes: in silico and in vitro biological screening,molecular docking and macromolecule interaction studies

Abstract

A novel tryptophan-derived Schiff base ligand (potassium (E)-2-((4-chloro-3-nitrobenzylidene)amino)-3-(1H-indol-3-yl)propanoate) and a series of its transition metal complexes of the types [ML₂] and [ML(1,10-phen)₂]Cl where M?=?Cu(II), Co(II), Ni(II) and Zn(II) were prepared. They were analyzed by various spectral and physicochemical studies. The XRD data were also used to determine the average lattice parameters and crystalline size of the compounds. All the synthesized compounds were tested against a series of five bacterial and fungal strains. The obtained results showed that the biological activity of free ligand was increased on complexation. PASS online software predicts the various biological activities of ligand such as enzyme inhibitor, antiviral, analgesic and antituberculosis. The in silico theoretical prediction of synthesized compounds is also deliberated by Swiss ADME predictor which gives the properties of molecular hydrophobicity (log P), topological polar surface area (TPSA) and oral bioavailability score. The binding energy of the docked molecule with macromolecules 1BNA and 3EQM is also determined by using Hex 8.0 software. The ligand has the least binding energy score which signifies that the potential of binding is greater in the receptor. Moreover, the interactions of complexes with DNA have been explored by electronic absorption titration, fluorescence emission titration, viscosity measurements and gel electrophoresis.

• Highlights

• Synthesis and characterization of novel indole-derived compounds.

• X-ray diffraction studies demonstrate average crystalline size of the compounds.

• Metal complexes act as good metallointercalators.

• Metal complexes show higher antimicrobial activity compared to ligand.

• Prediction of biological activities of the ligand by PASS online software.

• Drug-like nature and bioavailability of synthesized compounds predicted by Swiss ADME predictor

• Docking of the synthesized compounds with 1BNA and 3EQM using HEX 8.0 software.

Communicated by Ramaswamy H. Sarma     

Profiling Cell Signaling Networks at Single-cell Resolution

1. Download : Download high-res image (204KB)
2. Download : Download full-size image

Highlights

• •Signaling networks can be highly heterogeneous across cells in a tissue.
• •Various technologies allow analyzing signaling networks at single-cell resolution.
• •The advantages and limitations of each single-cell approach are summarized.
• •Confounding factors in single-cell signaling network analysis are discussed.

     

Global patterns in seed germination after ingestion by mammals

1. Mammals play an important role in seed germination through the ingestion of fruits and seeds. Since seed germination is a basic step in seedling recruitment, understanding how mammals affect germination improves our understanding of the effect of loss of mammal populations on the dynamics of plant communities.
2. We used meta-analytical methods to describe global patterns in the effect of seed ingestion by mammals on seed germination success and rate. We collected data from 154 studies that included 115 mammal species and 448 plant species.
3. Our results showed a positive cumulative effect of mammals on seed germination. However, this effect differed between mammalian orders; thus, some groups such as elephants, primates, and new world marsupials emerged as important enhancers of seed germination. Also, the effect varied depending on the plant family and the bioregion. Increased seed germination after ingestion was positively related to fast germination.
4. This meta-analysis, the first to synthesise and compare most of the information presently available on how mammals affect seed germination after ingestion, shows a global positive effect of mammals as enhancers of seed germination. However, behind that positive effect lies a diversity of neutral, negative, and positive effects of different magnitudes, which may have multifactorial explanations. We hope that the patterns presented here open up new questions and help guide future research efforts.

     

Live monitoring of plant redox and energy physiology with genetically encoded biosensors

Genetically encoded biosensors pave the way for understanding plant redox dynamics and energy metabolism on cellular and subcellular levels.

ADVANCES

• Methodological advances in fluorescent protein-based in vivo biosensing have been instrumental for several paradigm shifts in our understanding of cell physiology, metabolism and signaling.
• An increasing number of genetically encoded biosensors has been used to dissect the dynamics of several distinct redox couples and energy physiology in plants.
• In vivo monitoring using biosensors has pioneered the simultaneous read-out of different physiological parameters in different subcellular locations by parallelized plate reader-based, multiwell fluorimetry, or expression strategies for multiple sensors in parallel.
• Sensing dynamic changes in hydrogen peroxide levels is possible with sensors of the HyPer family, or roGFP fusion variants with a thiol peroxidase.
• Peredox and SoNar family sensors enable direct visualization of NADH/NAD⁺, while iNAP family sensors respond to NADPH concentration in plants.
• Sensor variants with different sensitivity ranges enable use of the most appropriate variant for the specific in vivo environment or experimental scope.

     

Extraction of watermelon seed proteins with enhanced functional properties using ultrasound

Abstract

Watermelon seed is the potential source of value-added proteins, oils, and carbohydrates. The present study evaluates the extraction, and functional properties of watermelon seed protein (WMSP) obtained by ultrasound-assisted extraction (UAE) method from watermelon seed (WMS). The optimization of various operating parameters, such as pH (9), WMS powder to solvent ratio (1:50 w/v), temperature (30?±?2?°C), ultrasound power (90?W), frequency (25?kHz), and duty cycle (75%) has been carried out. The extraction yield obtained was 87% and the extraction time was lowered down to 9?min from 120?min of conventional batch extraction. It contains all essential amino acids in an adequate amount required for adults as per FAO/WHO guidelines while for 2–5?years old children, the content of valine and isoleucine are above the required range. Methionine and lysine contents are adequate for both children and adults. Functional properties of ultrasonic extracted proteins were found superior to conventionally extracted proteins.

• highlights

• The UAE method is more efficient for watermelon seed protein extraction.

• Impact of extraction parameters on the extraction yield was studied.

• Protein isolate with enhanced functional properties was obtained.

• Essential amino acid content was determined.