“lectibody”, bispecific molecule of a lectin and an antibody scFv, for cancer therapy

A group from Faculty of Biology, University of Freiburg, Freiburg, Germany, etc. has reported about a lectibody recruiting cytotoxic T lymphocytes while simultaneously binding to tumor-associated antigen on cancer cells as a new modality for cancer therapy.

The lectibody was realized by conjugating an anti-CD3 single-chain antibody fragment to the B-subunit of Shiga toxin. The tumor-related glycosphingolipid globotriaosylceramide (Gb3) expressed on malignant cancer cells can be selectively recognized by the B-subunit of Shiga toxin (which is a kind of lectin), and the CD3 receptor on T cells can be targeted by the single chain variable fragment (scFv) OKT3 as the anti-CD3-binding molecule.

To show the proof of the concept, two human colon adenocarcinoma cell lines HT-29 and LS-174 which express different abundance of Gb3 antigen were targeted with the lectibody. The HT-29 cell line expresses a high amount of Gb3, in contrast, the LS-174 cell line expresses very low or no amounts of Gb3. As shown below, it was demonstrated that the killing activity strongly correlates to the abundance of the Gb3 antigen at the surface of the target cells.

Two diazotrophic beneficial bacteria isolated from the rhizosphere of a wild wheat ancestor (Pseudomonas and Enterobacter)

A group from UMR IPSiM, Université de Montpellier, Institut Agro, CNRS, Montpellier, France, etc. has reported about two diazotrophic PGPR strains, isolated from the rhizosphere of a wild wheat ancestor as beneficial bacteria.

Two bacterial strains, Pseudomonas BPMP-PU-28 and Enterobacter BPMP-EL-40, were isolated from the rhizosphere of a wild wheat ancestor. These strains have been shown to stimulate plant growth when the availability of nitrogen in the soil is limiting for the growth.

A striking effect of culture supernatant obtained from these beneficial bacteria was observed on root hair density and length in root apical regions as shown below (left-hand side is a control and right-hand side shows that of Pseudomonas).

The following features were seen in exudates from these bacteria.

The AHL N-tetradecenoyl-L-homoserine lactone (TDHL) has been found in BPMP-PU-28 and BPMP-EL-40 exudates. AHLs play a role in bacterial quorum sensing and in bacterial communication networks. They have positive effects on plant growth, and could be recognized by plant receptors and lead to modifications of plant gene expression.

It should also be noted that while no amino acids were detected in the bacterial exudates, some cyclopeptides were present. Together with AHLs, cyclic peptides have been shown to play a role in quorum sensing. In addition to playing a role in quorum sensing, cyclic peptides can act as mimetics of phytohormones which upregulate salicylic acid, ethylene and jasmonic acid signaling.

In addition to AHLs and cyclopeptides, many of the metabolites identified in exudates may play a role in plant growth promotion, for example by behaving as antibiotics (about 18% of the identified metabolites can be expected to have antibiotic effects), or by improving nutrient ion acquisition.

Changes in rhizospheric microbiota due to chitin addition into soybean soils

A group from Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, China, etch. has reported about changes in dominant bacterial and fungal taxa due to chitin addition into soybean soils.

Chitin addition is considered promising methods for alleviating soybean continuous cropping obstacles, however, the underlying mechanisms of soil sickness reduction remain unclear.

In this study, changes in dominant bacterial and fungal taxa due to chitin addition were evaluated.
At the bacterial OTU level, chitin distinctly increased the relative abundance of Streptomyces, Sphingomonas, Bacillus, Mesorhizobium and Nitrospira. At the fungal phylum level, chitin addition markedly increased the relative abundance of Zygomycota, and conversely drastically reduced the relative abundance of potential pathogens affiliated with Fusarium, Paraphoma, Cylindrocarpon and Septoria.

Dectin-1 is O-glycosylated and serves as a ligand for C-type lectin receptor CLEC-2

A group from Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan, etc. has reported that Human Dectin-1 is O-glycosylated and serves as a ligand for C-type lectin receptor CLEC-2.

Dectin-1 is known as the best-characterized C-type lectin receptors (CLRs) recognizing β-glucan on pathogens. Here, it was first found that Dectin-1 could be a ligand for CLEC-2, another CLR expressed on platelets. It was also known that CLEC-2 recognizes its endogenous ligand podoplanin in an O-glycosylation-dependent manner.

Dectin-1 is a mucin-like protein and its stalk region is highly O-glycosylated with sialylated core 1 (Galβ1-3GalNAc) and/or sialylated core 3 (GlcNAcβ1-3GalNAc) glycans. This finding will be the first example of an innate immune receptor also functioning as a physiological ligand to regulate ontogeny upon glycosylation.

Glycosylation engineering of the extracellular loop of CD63 on the surface of exosomes to improve the targeting performance of its DDS

A group from Biomolecular Medicine, Division of Biomolecular and Cellular Medicine, Department of Laboratory Medicine, Karolinska Institute, Huddinge Sweden, etc. has reported about cell‐specific targeting of extracellular vesicles (EVs) though engineering of glycan expression on EVs.

Extracellular vesicles are thought to be promising carriers for the delivery of a variety of chemical and biological drugs. In order to improve the targeting performance of EVs, EVs were engineered to display the glycan of interest.
EV producer cells were genetically engineered to co‐express a glycosylation domain (GD) inserted into the large extracellular loop of CD63 and fucosyltransferase VII (FUT7) or IX (FUT9). P19 (19‐mer, derived from PSGL‐1) and CTP (28‐mer, from beta‐chorionic gonadotropin) were selected as potential sLeX peptide carriers (i.e., as the glycosylation domain). The combination of FUT7 and PSGL-1 resulted in the highest expression of sLeX, and also the combination of FUT9 and PSGL‐1 resulted in the highest expression of Lewis X (LeX) but not sLeX.

Through this strategy, surface display of two types of glycan ligands, sLeX and LeX, on EVs was demonstrated, and achieved high specificity towards activated endothelial cells and dendritic cells, respectively.

Wheat rhizospheric microbiome: from Phylum level analysis and Genus level analysis

A group from ICAR-Indian Institute of Wheat and Barley Research, Karnal, Haryana, India, etc. has reported about wheat microbiome under varied agricultural field conditions.

This report presents wheat microbiome analysis under six different farm practices,
organic (Org),
timely sown (TS),
wheat after pulse crop (WAPC),
temperature-controlled phenotyping facility (TCPF),
maize-wheat cropping system (MW), and
residue burnt field (Bur).

The analysis based on phylum level revealed abundances of Proteobacteria, followed by Actinobacteria, Acidobacteria, Gemmatimonadetes, and Bacteroidetes, in all conditions, while the relative abundances varied at the genus level. The highest relative abundances of the genera Bacillus and Flavobacterium were observed in TCPF and Org, respectively, and the genus Nitrospira had the highest relative abundance in TS, MW, and WAPC.

Seed priming of entomopathogenic fungi to increase maize crop growth and tolerance against herbivores

A group from State Key Laboratory for Biology of Plant Diseases and Insect Pest, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China, etc. has reported seed priming of entomopathogenic fungi to increase crop growth and tolerance against herbivores.

Ostrinia furnacalis is the most destructive pest of maize causing an annual yield loss of about 6 to 9 million tons in East and Southeast Asia.

Seed priming is nowadays considered one the most promising techniques in enhancing abiotic and biotic stress tolerance, yield, and growth in crop plants. In this study, seed priming using Beauveria bassiana (BB) and Trichoderma asperellum (TA) were evaluated.

From the experimental results, the additional yield and gross return were calculated to estimate the increase in corn yield and economic return by the seed priming of entomopathogenic fungi. The highest additional yield of 6811.62 KG/ha and 8117.45 KG/ha in year 2018 and 2019 respectively was recorded in consortium treatment (BT), which is an increase of 82 – 96% over control. Treatment by BB and TA resulted in additional yield of 4518.06 (52.2%) and 2930.19 (35.4%) respectively in 2018 year and 4688.58 (55.8%) and 3982.40 (47.5%) in 2019 over control.

The effect of seed priming of entomopathogenic fungi was seen in O. furnacalis larval development, especially in consortium inoculated plants (BT). The growth speed was greatly reduced and larval survival rate was also reduced. It was seen that more then 50% larvae cannot even reached at 3rd instar stage and died. The lowest survival rate of 13% was recorded in consortium (BT) treated plants followed by 28% in B. bassiana (BB) and 36% in T. asperellum (TA) was recorded whereas the survival rate in control group was 94%.

Leaf samples of seed primed and non-primed maize under O. furnacalis stress were analyzed for antioxidants, proline, and chlorophyll content. Seed priming with fungal strains significantly increased the enzyme activities at 24-h by the consortium treatment (BT) compared to non-primed control (IC). The seed priming with BT significantly enhanced the SOD, POD, Protease, PPO, and Proline activities up to 80.29-, 336-, 302-, 141-, and 65.8-fold respectively. And further, O. furnacalis infestation significantly increased cis-OPDA, JA, and JA-Ile in all fungal inoculated treatments (BB, TA, BT) but the highest phytohormone content was observed in consortium treated plants (BT), suggesting that the entomopathogenic fungal inoculation., especially consortium (BT) induced the enhanced production of JA metabolites in maize.

Foliar pathogen infection recruits beneficial bacteria through root exudates

A group from State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, China, etc. has reported that foliar pathogen infection recruits beneficial bacteria through root exudates.

It was found that foliar infection of Panax notoginseng by Alternaria panax modified the rhizosphere soil microbial community and reversed the direction of the buildup of the soilborne pathogen Ilyonectria destructans and beneficial microbes, including Trichoderma, Bacillus, and Streptomyces, in rhizosphere soil. These beneficial microbes not only showed antagonistic ability against the pathogen I. destructans but also enhanced the resistance of plants to A. panax.

Foliar infection changes the metabolite profiles of root exudates determined by GC-MS analyses. Inoculated means foliar infection.

This is similar to the human immune response, in which cytokines and chemokines are secreted from the inflammatory site, and immune cells such as leukocytes are attracted to the inflammatory site. Changes in the secretion from the root correspond to the secretion of cytokines and chemokines, and beneficial bacteria are immune cells derived from bone marrow cells.

Lectin analysis of SARS-CoV-2-positive nasopharyngeal samples

A group from GLYcoDiag, 2 Rue du Cristal, Orléans, France, etc. has reported about lectin analysis of SARS-CoV-2-positive nasopharyngeal samples.

I have decided to stop blogging about SARS-CoV-2 related issues, but oh well!

GlycoDIAG’s GLYcoPROFILE® technology clearly indicated the glycan differences between SARS-CoV-2-positive and -negative samples.
BPA and PHA-E were able to discriminate the control group from SARS-CoV-2-positive samples, with values around or higher than 3000. The BPA recognizes GalNAc-containing glycans, while PHA-E binds to bi-antennary complex N-glycans. In addition, another group of lectins, including WFA (binds to LacdiNAc), GSL-II (binds to agalacto) and PHA-L (binds to tri/tetra antennary complex N-glycan), were also distinguishing for SARS-CoV-2-positive samples. The HHA lectin was confirmed as a negative reference lectin.

Interactions between thrombopoietin (TPO) receptor MPL and a marine sponge-derived lectin

A group from Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Japan, etc. has reported about interactions between thrombopoietin (TPO) receptor MPL and a marine sponge-derived lectin, thrombocorticin (ThC).

It has been reported that a marine sponge-derived 14-kDa protein, ThC, as a potent agonist of MPL.
In this study, the three-dimensional structure of ThC was elucidated as a fucose-binding lectin, and also it was shown that the MPL activation was induced by its binding to a fucosylated glycan on MPL.

Dimer structure of rThC in complex with Ca2+ (green ball) and fucose (ball-and-stick model, yellow: carbon, red: oxygen)