Mucin-Type O-Glycosylation in Invertebrates

Navigating the maze of mass spectra: a machine-learning guide to identifying diagnostic ions in O-glycan analysis

Structural details of oligosaccharides, or glycans, often carry biological relevance, which is why they are typically elucidated using tandem mass spectrometry. Common approaches to distinguish isomers rely on diagnostic glycan fragments for annotating topologies or linkages. Diagnostic fragments are often only known informally among practitioners or stem from individual studies, with unclear validity or generalizability, causing annotation heterogeneity and hampering new analysts. Drawing on a curated set of 237,000 O-glycomics spectra, we here present a rule-based machine learning workflow to uncover quantifiably valid and generalizable diagnostic fragments. This results in fragmentation rules to robustly distinguish common O-glycan isomers for reduced glycans in negative ion mode. We envision this resource to improve glycan annotation accuracy and concomitantly make annotations more transparent and homogeneous across analysts.

A high heterozygosity genome assembly of Aedes albopictus enables the discovery of the association of PGANT3 with blood-feeding behavior

The Asian tiger mosquito, Aedes albopictus, is a global invasive species, notorious for its role in transmitting dangerous human arboviruses such as dengue and Chikungunya. Although hematophagous behavior is repulsive, it is an effective strategy for mosquitoes like Aedes albopictus to transmit viruses, posing a significant risk to human health. However, the fragmented nature of the Ae. albopictus genome assembly has been a significant challenge, hindering in-depth biological and genetic studies of this mosquito. In this research, we have harnessed a variety of technologies and implemented a novel strategy to create a significantly improved genome assembly for Ae. albopictus, designated as AealbF3. This assembly boasts a completeness rate of up to 98.1%, and the duplication rate has been minimized to 1.2%. Furthermore, the fragmented contigs or scaffolds of AealbF3 have been organized into three distinct chromosomes, an arrangement corroborated through syntenic plot analysis, which compared the genetic structure of Ae. albopictus with that of Ae. aegypti. Additionally, the study has revealed a phylogenetic relationship suggesting that the PGANT3 gene is implicated in the hematophagous behavior of Ae. albopictus. This involvement was preliminarily substantiated through RNA interference (RNAi) techniques and behavioral experiment. In summary, the AealbF3 genome assembly will facilitate new biological insights and intervention strategies for combating this formidable vector of disease. The innovative assembly process employed in this study could also serve as a valuable template for the assembly of genomes in other insects characterized by high levels of heterozygosity.

Expression and Characterization of a β-Galactosidase from the Pacific Oyster, Crassostrea gigas, and Evaluation of Strategies for Testing Substrate Specificity

β-Galactosidases (EC 3.2.1.23) are exoglycosidases that catalyze the cleavage of glycoconjugates with terminal β-D-galactose residues in β1,3-, β1,4- or β1,6-linkage. Although this family of exoglycosidases has been extensively studied in vertebrates, plants, yeast, and bacteria, little information is available for mollusks. Mollusks are a diverse and highly successful group of animals that play many different roles in their ecosystems, including filter feeders and detritivores. Here, the first β-galactosidase from the Pacific oyster, Crassostrea gigas was discovered, biochemically characterized, and compared to our previously characterized slug enzyme from Arion vulgaris (UniProt Ref. Nr.: A0A0B7AQJ9). Overall, the mussel enzyme showed similar biochemical parameters to the snail enzyme. The enzyme from C. gigas was most active in an acidic environment (pH 3.5) and at a reaction temperature of 50 °C. Optimal storage conditions were up to 37 °C. In contrast to the enzyme from A. vulgaris, the supplementation of cations (Ni2+, Co2+, Mn2+, Mg2+, Ca2+, Cu2+, Ba2+) increased the activity of the enzyme from C. gigas. Substrate specificity studies of the β-galactosidases from the mussel, C. gigas, and the slug, A. vulgaris, revealed activity towards terminal β1,3- and β1,4-linked galactose residues for both enzymes. Using the same substrates in labeled and unlabeled form, we were able to detect the effect of labeling on the β-galactosidase activity using MALDI-TOF MS, HPTLC, and HPLC. While lactose was cleaved by the enzymes in an unlabeled or labeled state, galacto-N-biose was not cleaved as soon as a 2-amino benzoic acid label was added. In this study we present the biochemical characterization of the first recombinantly expressed β-galactosidase from the Pacific oyster, C. gigas, and we compare different analytical methods for the determination of β-galactosidase activity using the enzyme from C. gigas and A. vulgaris.

Comparative mucomic analysis of three functionally distinct Cornu aspersum Secretions

Every animal secretes mucus, placing them among the most diverse biological materials. Mucus hydrogels are complex mixtures of water, ions, carbohydrates, and proteins. Uncertainty surrounding their composition and how interactions between components contribute to mucus function complicates efforts to exploit their properties. There is substantial interest in commercializing mucus from the garden snail, Cornu aspersum, for skincare, drug delivery, tissue engineering, and composite materials. C. aspersum secretes three mucus-one shielding the animal from environmental threats, one adhesive mucus from the pedal surface of the foot, and another pedal mucus that is lubricating. It remains a mystery how compositional differences account for their substantially different properties. Here, we characterize mucus proteins, glycosylation, ion content, and mechanical properties that could be used to provide insight into structure-function relationships through an integrative "mucomics" approach. We identify macromolecular components of these hydrogels, including a previously unreported protein class termed Conserved Anterior Mollusk Proteins (CAMPs). Revealing differences between C. aspersum mucus shows how considering structure at all levels can inform the design of mucus-inspired materials.

Advances in protein glycosylation and its role in tissue repair and regeneration

After tissue damage, a series of molecular and cellular events are initiated to promote tissue repair and regeneration to restore its original structure and function. These events include inter-cell communication, cell proliferation, cell migration, extracellular matrix differentiation, and other critical biological processes. Glycosylation is the crucial conservative and universal post-translational modification in all eukaryotic cells [1], with influential roles in intercellular recognition, regulation, signaling, immune response, cellular transformation, and disease development. Studies have shown that abnormally glycosylation of proteins is a well-recognized feature of cancer cells, and specific glycan structures are considered markers of tumor development. There are many studies on gene expression and regulation during tissue repair and regeneration. Still, there needs to be more knowledge of complex carbohydrates' effects on tissue repair and regeneration, such as glycosylation. Here, we present a review of studies investigating protein glycosylation in the tissue repair and regeneration process.

Recombinant mucin biotechnology and engineering

Mucins represent a largely untapped class of polymeric building block for biomaterials, therapeutics, and other biotechnology. Because the mucin polymer backbone is genetically encoded, sequence-specific mucins with defined physical and biochemical properties can be fabricated using recombinant technologies. The pendent O-glycans of mucins are increasingly implicated in immunomodulation, suppression of pathogen virulence, and other biochemical activities. Recent advances in engineered cell production systems are enabling the scalable synthesis of recombinant mucins with precisely tuned glycan side chains, offering exciting possibilities to tune the biological functionality of mucin-based products. New metabolic and chemoenzymatic strategies enable further tuning and functionalization of mucin O-glycans, opening new possibilities to expand the chemical diversity and functionality of mucin building blocks. In this review, we discuss these advances, and the opportunities for engineered mucins in biomedical applications ranging from in vitro models to therapeutics.

Identification, Characterization, and Expression of a β-Galactosidase from Arion Species (Mollusca)

β-Galactosidases (β-Gal, EC 3.2.1.23) catalyze the cleavage of terminal non-reducing β-D-galactose residues or transglycosylation reactions yielding galacto-oligosaccharides. In this study, we present the isolation and characterization of a β-galactosidase from Arion lusitanicus, and based on this, the cloning and expression of a putative β-galactosidase from Arion vulgaris (A0A0B7AQJ9) in Sf9 cells. The entire gene codes for a protein consisting of 661 amino acids, comprising a putative signal peptide and an active domain. Specificity studies show exo- and endo-cleavage activity for galactose β1,4-linkages. Both enzymes, the recombinant from A. vulgaris and the native from A. lusitanicus, display similar biochemical parameters. Both β-galactosidases are most active in acidic environments ranging from pH 3.5 to 4.5, and do not depend on metal ions. The ideal reaction temperature is 50 °C. Long-term storage is possible up to +4 °C for the A. vulgaris enzyme, and up to +20 °C for the A. lusitanicus enzyme. This is the first report of the expression and characterization of a mollusk exoglycosidase.

Marine invertebrate sialyltransferase of the sea squirt Ciona savignyi sialylated core 1 O-linked glycans

An invertebrate sialyltransferase, cST3Gal-I, identified from the sea squirt Ciona savignyi, was functionally characterized in vitro using recombinant enzyme expressed in yeast strains. cST3Gal-I was localized to the Golgi membrane when expressed in Saccharomyces cerevisiae. Enzymatic characterization for substrate specificity and kinetic property indicate that cST3Gal-I prefers O-glycans, rather than N-glycan, of asialoglycoproteins as substrates. Interestingly, C. savignyi sialyltransferase exhibited effectively Neu5Ac transfer to core 1 O-glycan, Gal β(1,3)GalNAc, compared to orthologous human glycosyltransferase. Further, it is shown that cST3Gal-I catalyzes the formation of α(2,3)-linkage, through lectin blot analysis with Maackia amurensis lectin and by linkage-specific sialidase treatments. The putative active sites of cST3Gal-I for putative acid/base catalysts and sialic acid acceptor/donor substrate bindings were also identical to the counterpart residues of a mammalian enzyme, porcine ST3Gal-I, as predicted through homologous structure modeling. These results could imply that an ancestral tunicate ST3Gal-I in C. savignyi would prefer O-glycan onto glycoproteins as its sialic acid acceptor than vertebrate enzymes.

The Role of Fucose-Containing Glycan Motifs Across Taxonomic Kingdoms

The extraordinary diversity of glycans leads to large differences in the glycomes of different kingdoms of life. Yet, while most monosaccharides are solely found in certain taxonomic groups, there is a small set of monosaccharides with widespread distribution across nearly all domains of life. These general monosaccharides are particularly relevant for glycan motifs, as they can readily be used by commensals and pathogens to mimic host glycans or hijack existing glycan recognition systems. Among these, the monosaccharide fucose is especially interesting, as it frequently presents itself as a terminal monosaccharide, primed for interaction with proteins. Here, we analyze fucose-containing glycan motifs across all taxonomic kingdoms. Using a hereby presented large species-specific glycan dataset and a plethora of methods for glycan-focused bioinformatics and machine learning, we identify characteristic as well as shared fucose-containing glycan motifs for various taxonomic groups, demonstrating clear differences in fucose usage. Even within domains, fucose is used differentially based on an organism’s physiology and habitat. We particularly highlight differences in fucose-containing motifs between vertebrates and invertebrates. With the example of pathogenic and non-pathogenic Escherichia coli strains, we also demonstrate the importance of fucose-containing motifs in molecular mimicry and thereby pathogenic potential. We envision that this study will shed light on an important class of glycan motifs, with potential new insights into the role of fucosylated glycans in symbiosis, pathogenicity, and immunity.

The Vibrio parahaemolyticus subunit toxin PirBvp recognizes glycoproteins on the epithelium of the Penaeus vannamei hepatopancreas

Vibrio parahaemolyticus toxin PirAB^vp is the major virulence factor exotoxin that contributes to the disruption of the hepatopancreatic epithelium in acute hepatopancreatic necrosis disease in shrimp. The PirB^vp subunit is a lectin that recognizes amino sugars; however, its potential role in recognition of the hepatopancreas has not been identified. In the present work, we identified the cellular receptor for PirB^vp in the shrimp hepatopancreas. A ligand blot assay of hepatopancreas lysate showed that the PirB^vp subunit recognizes two glycoprotein bands of 60 and 70 kDa (Gc60 and Gc70). The hepatopancreas lysate was fractionated by anion-exchange chromatography, and the three main fractions obtained contained the recognized Gc60 and Gc70 protein bands. LC-MS/MS indicated that beta-hexosaminidases subunit beta and mucin-like 5 AC corresponded to the 60 and 70 kDa bands, respectively, which seem to be expressed in the epithelial cells of the hepatopancreas. Endoglycosidase treatment of hepatopancreas lysate with the O-glycosidase from Enterococcus faecalis, inhibits the binding of PirB^vp. Altogether, these results suggest the relevance of the interaction of PirB^vp with the hepatopancreas in the pathogenesis of acute hepatopancreatic necrosis disease in shrimp.

Medicinal chemistry of pyrophosphate mimics: A mini review

The pyrophosphate mimicking groups offer rational modification of the pyrophosphate-bearing natural substrates of the overexpressed enzymes that cause the onset of disease progression. Mainly, the modified substrate interacts differently with the enzyme active site eventually causing its deactivation, or provides the therapeutically active products at the completion of the catalytic cycle that contribute toward the inhibition of the target enzyme. Many of the pyrophosphate mimic-containing molecules serve as competitive or allosteric inhibitors of the target enzyme to achieve the desirable properties for the mitigation of the target enzyme's pathophysiology. This review presents an epigrammatic overview of the pyrophosphate mimics in medicinal chemistry.

A bi-specific lectin from the mushroom Boletopsis grisea and its application in glycoanalytical workflows

The BLL lectin from the edible Japanese "Kurokawa" mushroom (Boletopsis leucomelaena) was previously reported to bind to N-glycans harboring terminal N-acetylglucosamine (GlcNAc) and to induce apoptosis in a leukemia cell line. However, its gene has not been reported. In this study, we used a transcriptomics-based workflow to identify a full-length transcript of a BLL functional ortholog (termed BGL) from Boletopsis grisea, a close North American relative of B. leucomelaena. The deduced amino acid sequence of BGL was an obvious member of fungal fruit body lectin family (Pfam PF07367), a highly conserved group of mushroom lectins with a preference for binding O-glycans harboring the Thomsen-Friedenreich antigen (TF-antigen; Galβ1,3GalNAc-α-) and having two ligand binding sites. Functional characterization of recombinant BGL using glycan microarray analysis and surface plasmon resonance confirmed its ability to bind both the TF-antigen and β-GlcNAc-terminated N-glycans. Structure-guided mutagenesis of BGL's two ligand binding clefts showed that one site is responsible for binding TF-antigen structures associated with O-glycans, whereas the second site specifically recognizes N-glycans with terminal β-GlcNAc. Additionally, the two sites show no evidence of allosteric communication. Finally, mutant BGL proteins having single functional bindings site were used to enrich GlcNAc-capped N-glycans or mucin type O-glycopeptides from complex samples in glycomics and glycoproteomics analytical workflows.

Analysis of microRNA expression in cerebral ischemia/reperfusion after mild therapeutic hypothermia treatment in rats

Background

This study aimed to explore the molecular mechanism of mild hypothermia in in the treatment of cerebral ischemia, microRNA (miRNA) microarrays and bioinformatics analysis were employed to examine the miRNA expression profiles of rats with mild therapeutic hypothermia after middle cerebral artery occlusion (MCAO).

Methods

MCAO was induced in Male Sprague–Dawley rats. Mild hypothermia treatment began from the onset of ischemia and maintained for 3 hours. miRNA expressions following focal cerebral ischemia and mild hypothermia treatment were profiled using microarray technology. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to analyze the functions of the target genes in mild therapeutic hypothermia after MCAO. 60 min before MCAO, mimics and inhibitor of miR-291b were injected into the right lateral ventricle respectively, then the infarct volume and neuronal apoptosis were analyzed.

Results

Six upregulated miRNAs and 6 downregulated miRNAs were detected 4 hours after mild therapeutic hypothermia, and after 24 hours, 41 and 10 miRNAs were upregulated and downregulated, respectively. The target genes of the differentially expressed genes were mainly related with multicellular organism development and the mucin type O-glycan biosynthesis pathway was the most enriched KEGG pathway. Among the differentially expressed miRNAs, miR-291b was selected to assess the effects of mild therapeutic hypothermia in MCAO rats. At 24 hours after mild therapeutic hypothermia, miR-291b overexpression was proved to exhibit neuroprotective effects.

Conclusions

The results showed that miRNAs might play a pivotal role in mild therapeutic hypothermia in cerebral ischemia/reperfusion injury. Further understanding of the mechanism and function of miRNAs would help to illuminate the mechanism of mild therapeutic hypothermia in cerebral ischemia/reperfusion injury.

Chemo-Enzymatic Synthesis of S. mansoni O-Glycans and Their Evaluation as Ligands for C-Type Lectin Receptors MGL, DC-SIGN, and DC-SIGNR

Due to their interactions with C-type lectin receptors (CLRs), glycans from the helminth Schistosoma mansoni represent promising leads for treatment of autoimmune diseases, allergies or cancer. We chemo-enzymatically synthesized nine O-glycans based on the two predominant O-glycan cores observed in the infectious stages of schistosomiasis, the mucin core 2 and the S. mansoni core. The O-glycans were fucosylated next to a selection of N-glycans directly on a microarray slide using a recombinant fucosyltransferase and GDP-fucose or GDP-6-azidofucose as donor. Binding assays with fluorescently labelled human CLRs DC-SIGN, DC-SIGNR and MGL revealed the novel O-glycan O8 as the best ligand for MGL from our panel. Significant binding to DC-SIGN was also found for azido-fucosylated glycans. Contrasting binding specificities were observed between the monovalent carbohydrate recognition domain (CRD) and the tetravalent extracellular domain (ECD) of DC-SIGNR.

Macrobrachium rosenbergii nodavirus virus-like particles attach to fucosylated glycans in the gills of the giant freshwater prawn

The Macrobrachium rosenbergii nodavirus (MrNV), the causative agent of white-tail disease (WTD) in many species of shrimp and prawn, has been shown to infect hemocytes and tissues such as the gills and muscles. However, little is known about the host surface molecules to which MrNV attach to initiate infection. Therefore, the present study investigated the role of glycans as binding molecules for virus attachment in susceptible tissues such as the gills. We established that MrNV in their virus-like particle (MrNV-VLP) form exhibited strong binding to gill tissues and lysates, which was highly reduced by the glycan-reducing periodate and PNGase F. The broad, fucose-binding Aleuria Aurantia lectin (AAL) highly reduced MrNV-VLPs binding to gill tissue sections and lysates, and efficiently disrupted the specific interactions between the VLPs and gill glycoproteins. Furthermore, mass spectroscopy revealed the existence of unique fucosylated LacdiNAc-extended N-linked and O-linked glycans in the gill tissues, whereas beta-elimination experiments showed that MrNV-VLPs demonstrated a binding preference for N-glycans. Therefore, the results from this study highly suggested that MrNV-VLPs preferentially attach to fucosylated N-glycans in the susceptible gill tissues, and these findings could lead to the development of strategies that target virus-host surface glycan interactions to reduce MrNV infections.

Insights into the salivary N-glycome of Lutzomyia longipalpis, vector of visceral leishmaniasis

During Leishmania transmission sand flies inoculate parasites and saliva into the skin of vertebrates. Saliva has anti-haemostatic and anti-inflammatory activities that evolved to facilitate bloodfeeding, but also modulate the host's immune responses. Sand fly salivary proteins have been extensively studied, but the nature and biological roles of protein-linked glycans remain overlooked. Here, we characterised the profile of N-glycans from the salivary glycoproteins of Lutzomyia longipalpis, vector of visceral leishmaniasis in the Americas. In silico predictions suggest half of Lu. longipalpis salivary proteins may be N-glycosylated. SDS-PAGE coupled to LC-MS analysis of sand fly saliva, before and after enzymatic deglycosylation, revealed several candidate glycoproteins. To determine the diversity of N-glycan structures in sand fly saliva, enzymatically released sugars were fluorescently tagged and analysed by HPLC, combined with highly sensitive LC-MS/MS, MALDI-TOF-MS, and exoglycosidase treatments. We found that the N-glycan composition of Lu. longipalpis saliva mostly consists of oligomannose sugars, with Man5GlcNAc2 being the most abundant, and a few hybrid-type species. Interestingly, some glycans appear modified with a group of 144 Da, whose identity has yet to be confirmed. Our work presents the first detailed structural analysis of sand fly salivary glycans.

Toxocara "omics" and the promises it holds for medicine and veterinary medicine

Toxocariasis is one of the most neglected worldwide zoonoses that is caused by larval nematode parasites of the genus Toxocara, Toxocara canis, and to a lesser extent, Toxocara cati, whose migration mechanism is still largely unknown. Fortunately, some advanced tools have been employed, such as genomics, transcriptomics, and proteomics, to better understand the molecular biology and regulatory mechanisms of Toxocara. Using genomics and transcriptomics, we can identify a large number of genes that participate in the development of Toxocara and the interaction of parasites and their hosts and can predict the functions of unknown genes by comparing them with other relevant species. Using proteomics, we can identify somatic proteins and excretory and secretory (ES) proteins that perform specific biological functions in tissue degradation, pathogen invasion, immune evasion or modulation. These "omics" techniques also can contribute enormously to the development of new drugs, vaccines and diagnostic tools for toxocariasis. In a word, by utilizing "omics", we can better understand the Toxocara and toxocariasis. In this review, we summarized the representative achievements in Toxocara and the interaction between Toxocara spp. and their hosts based on expressed sequence tags (ESTs), microarray gene expression, next-generation sequencing (NGS) technologies and liquid chromatography-tandem mass spectrometry (LC-MS/MS), hoping to better understand the molecular biology of Toxocara, and contribute to new progress in the application areas of new drugs, vaccines and diagnostic tool for toxocariasis in the future.

N-glycosylation Site Analysis Reveals Sex-related Differences in Protein N-glycosylation in the Rice Brown Planthopper (Nilaparvata lugens)

Glycosylation is a common modification of proteins and critical for a wide range of biological processes. Differences in protein glycosylation between sexes have already been observed in humans, nematodes and trematodes, and have recently also been reported in the rice pest insect Nilaparvata lugens Although protein N-glycosylation in insects is nowadays of high interest because of its potential for exploitation in pest control strategies, the functionality of differential N-glycosylation between sexes is yet unknown. In this study, therefore, the occurrence and role of sex-related protein N-glycosylation in insects were examined. A comprehensive investigation of the N-glycosylation sites from the adult stages of N. lugens was conducted, allowing a qualitative and quantitative comparison between sexes at the glycopeptide level. N-glycopeptide enrichment via lectin capturing using the high mannose/paucimannose-binding lectin Concanavalin A, or the Rhizoctonia solani agglutinin which interacts with complex N-glycans, resulted in the identification of over 1300 N-glycosylation sites derived from over 600 glycoproteins. Comparison of these N-glycopeptides revealed striking differences in protein N-glycosylation between sexes. Male- and female-specific N-glycosylation sites were identified, and some of these sex-specific N-glycosylation sites were shown to be derived from proteins with a putative role in insect reproduction. In addition, differential glycan composition between males and females was observed for proteins shared across sexes. Both lectin blotting experiments as well as transcript expression analyses with complete insects and insect tissues confirmed the observed differences in N-glycosylation of proteins between sexes. In conclusion, this study provides further evidence for protein N-glycosylation to be sex-related in insects. Furthermore, original data on N-glycosylation sites of N. lugens adults are presented, providing novel insights into planthopper's biology and information for future biological pest control strategies.

Lectin PLL3, a Novel Monomeric Member of the Seven-Bladed β-Propeller Lectin Family

The Photorhabdus species is a Gram-negative bacteria of the family Morganellaceae that is known for its mutualistic relationship with Heterorhabditis nematodes and pathogenicity toward insects. This study is focused on the characterization of the recombinant lectin PLL3 with an origin in P. laumondii subsp. laumondii. PLL3 belongs to the PLL family of lectins with a seven-bladed β-propeller fold. The binding properties of PLL3 were tested by hemagglutination assay, glycan array, isothermal titration calorimetry, and surface plasmon resonance, and its structure was determined by X-ray crystallography. Obtained data revealed that PLL3 binds similar carbohydrates to those that the other PLL family members bind, with some differences in the binding properties. PLL3 exhibited the highest affinity toward l-fucose and its derivatives but was also able to interact with O-methylated glycans and other ligands. Unlike the other members of this family, PLL3 was discovered to be a monomer, which might correspond to a weaker avidity effect compared to homologous lectins. Based on the similarity to the related lectins and their proposed biological function, PLL3 might accompany them during the interaction of P. laumondii with both the nematode partner and the insect host.

Position of human blood group O(H) and phenotype-determining enzymes in growth and infectious disease

The human ABO(H) blood group phenotypes arise from the evolutionarily oldest genetic system found in primate populations. While the blood group antigen A is considered the ancestral primordial structure, under the selective pressure of life‐threatening diseases blood group O(H) came to dominate as the most frequently occurring blood group worldwide. Non‐O(H) phenotypes demonstrate impaired formation of adaptive and innate immunoglobulin specificities due to clonal selection and phenotype formation in plasma proteins. Compared with individuals with blood group O(H), blood group A individuals not only have a significantly higher risk of developing certain types of cancer but also exhibit high susceptibility to malaria tropica or infection by Plasmodium falciparum. The phenotype‐determining blood group A glycotransferase(s), which affect the levels of anti‐A/Tn cross‐reactive immunoglobulins in phenotypic glycosidic accommodation, might also mediate adhesion and entry of the parasite to host cells via trans‐species O‐GalNAc glycosylation of abundantly expressed serine residues that arise throughout the parasite's life cycle, while excluding the possibility of antibody formation against the resulting hybrid Tn antigen. In contrast, human blood group O(H), lacking this enzyme, is indicated to confer a survival advantage regarding the overall risk of developing cancer, and individuals with this blood group rarely develop life‐threatening infections involving evolutionarily selective malaria strains.

Early ovariectomy reveals the germline encoding of natural anti-A- and Tn-cross-reactive immunoglobulin M (IgM) arising from developmental O-GalNAc glycosylations. (Germline-encoded natural anti-A/Tn cross-reactive IgM)

While native blood group A-like glycans have not been demonstrated in prokaryotic microorganisms as a source of human "natural" anti-A isoagglutinin production, and metazoan eukaryotic N-acetylgalactosamine O-glycosylation of serine or threonine residues (O-GalNAc-Ser/Thr-R) does not occur in bacteria, the O-GalNAc glycan-bearing ovarian glycolipids, discovered in C57BL/10 mice, are complementary to the syngeneic anti-A-reactive immunoglobulin M (IgM), which is not present in animals that have undergone ovariectomy prior to the onset of puberty. These mammalian ovarian glycolipids are complementary also to the anti-A/Tn cross-reactive Helix pomatia agglutinin (HPA), a molluscan defense protein, emerging from the coat proteins of fertilized eggs and reflecting the snail-intrinsic, reversible O-GalNAc glycosylations. The hexameric structure of this primitive invertebrate defense protein gives rise to speculation regarding an evolutionary relationship to the mammalian nonimmune, anti-A-reactive immunoglobulin M (IgM) molecule. Hypothetically, this molecule obtains its complementarity from the first step of protein glycosylations, initiated by GalNAc via reversible O-linkages to peptides displaying Ser/Thr motifs, whereas the subsequent transferase depletion completes germ cell maturation and cell renewal, associated with loss of glycosidic bonds and release of O-glycan-depleted proteins, such as complementary IgM revealing the structure of the volatilely expressed "lost" glycan carrier through germline Ser residues. Consequently, the evolutionary/developmental first glycosylations of proteins appear metabolically related or identical to that of the mucin-type, potentially "aberrant" monosaccharide GalNAcα1-O-Ser/Thr-R, also referred to as the Tn (T "nouvelle") antigen, and explain the anti-Tn cross-reactivity of human innate or "natural" anti-A-specific isoagglutinin and the pronounced occurrence of cross-reactive anti-Tn antibody in plasma from humans with histo-blood group O. In fact, A-allelic, phenotype-specific GalNAc glycosylation of plasma proteins does not occur in human blood group O, affecting anti-Tn antibody levels, which may function as a growth regulator that contributes to a potential survival advantage of this group in the overall risk of developing cancer when compared with non-O blood groups.

Characterization and expression analysis of Galnts in developing Strongylocentrotus purpuratus embryos

Mucin-type O-glycosylation is a ubiquitous posttranslational modification in which N-Acetylgalactosamine (GalNAc) is added to the hydroxyl group of select serine or threonine residues of a protein by the family of UDP-GalNAc:Polypeptide N-Acetylgalactosaminyltransferases (GalNAc-Ts; EC 2.4.1.41). Previous studies demonstrate that O-glycosylation plays essential roles in protein function, cell-cell interactions, cell polarity and differentiation in developing mouse and Drosophila embryos. Although this type of protein modification is highly conserved among higher eukaryotes, little is known about this family of enzymes in echinoderms, basal deuterostome relatives of the chordates. To investigate the potential role of GalNAc-Ts in echinoderms, we have begun the characterization of this enzyme family in the purple sea urchin, S. purpuratus. We have fully or partially cloned a total of 13 genes (SpGalnts) encoding putative sea urchin SpGalNAc-Ts, and have confirmed enzymatic activity of five recombinant proteins. Amino acid alignments revealed high sequence similarity among sea urchin and mammalian glycosyltransferases, suggesting the presence of putative orthologues. Structural models underscored these similarities and helped reconcile some of the substrate preferences observed. Temporal and spatial expression of SpGalnt transcripts, was studied by whole-mount in situ hybridization. We found that many of these genes are transcribed early in developing embryos, often with restricted expression to the endomesodermal region. Multicolor fluorescent in situ hybridization (FISH) demonstrated that transcripts encoding SpGalnt7-2 co-localized with both Endo16 (a gene expressed in the endoderm), and Gcm (a gene expressed in secondary mesenchyme cells) at the early blastula stage, 20 hours post fertilization (hpf). At late blastula stage (28 hpf), SpGalnt7-2 message co-expresses with Gcm, suggesting that it may play a role in secondary mesenchyme development. We also discovered that morpholino-mediated knockdown of SpGalnt13 transcripts, results in a deficiency of embryonic skeleton and neurons, suggesting that mucin-type O-glycans play essential roles during embryonic development in S. purpuratus.

Diversity and functions of protein glycosylation in insects

The majority of proteins is modified with carbohydrate structures. This modification, called glycosylation, was shown to be crucial for protein folding, stability and subcellular location, as well as protein-protein interactions, recognition and signaling. Protein glycosylation is involved in multiple physiological processes, including embryonic development, growth, circadian rhythms, cell attachment as well as maintenance of organ structure, immunity and fertility. Although the general principles of glycosylation are similar among eukaryotic organisms, insects synthesize a distinct repertoire of glycan structures compared to plants and vertebrates. Consequently, a number of unique insect glycans mediate functions specific to this class of invertebrates. For instance, the core α1,3-fucosylation of N-glycans is absent in vertebrates, while in insects this modification is crucial for the development of wings and the nervous system. At present, most of the data on insect glycobiology comes from research in Drosophila. Yet, progressively more information on the glycan structures and the importance of glycosylation in other insects like beetles, caterpillars, aphids and bees is becoming available. This review gives a summary of the current knowledge and recent progress related to glycan diversity and function(s) of protein glycosylation in insects. We focus on N- and O-glycosylation, their synthesis, physiological role(s), as well as the molecular and biochemical basis of these processes.

Draft Genome of Toxocara canis, a Pathogen Responsible for Visceral Larva Migrans

This study aimed at constructing a draft genome of the adult female worm Toxocara canis using next-generation sequencing (NGS) and de novo assembly, as well as to find new genes after annotation using functional genomics tools. Using an NGS machine, we produced DNA read data of T. canis. The de novo assembly of the read data was performed using SOAPdenovo. RNA read data were assembled using Trinity. Structural annotation, homology search, functional annotation, classification of protein domains, and KEGG pathway analysis were carried out. Besides them, recently developed tools such as MAKER, PASA, Evidence Modeler, and Blast2GO were used. The scaffold DNA was obtained, the N50 was 108,950 bp, and the overall length was 341,776,187 bp. The N50 of the transcriptome was 940 bp, and its length was 53,046,952 bp. The GC content of the entire genome was 39.3%. The total number of genes was 20,178, and the total number of protein sequences was 22,358. Of the 22,358 protein sequences, 4,992 were newly observed in T. canis. Following proteins previously unknown were found: E3 ubiquitin-protein ligase cbl-b and antigen T-cell receptor, zeta chain for T-cell and B-cell regulation; endoprotease bli-4 for cuticle metabolism; mucin 12Ea and polymorphic mucin variant C6/1/40r2.1 for mucin production; tropomodulin-family protein and ryanodine receptor calcium release channels for muscle movement. We were able to find new hypothetical polypeptides sequences unique to T. canis, and the findings of this study are capable of serving as a basis for extending our biological understanding of T. canis.