BACKGROUND: The parasitic protozoan Giardia duodenalis is an important cause of diarrheal disease in humans and animals that can be spread by fecal-oral transmission through water and the environment, posing a challenge to public health and animal husbandry. Little is known about its impact on large-scale sheep farms in China. In this study we investigated G. duodenalis infection of sheep and contamination of the environment in large-scale sheep farms in two regions of China, Henan and Ningxia.
METHODS: A total of 528 fecal samples, 402 environmental samples and 30 water samples were collected from seven large-scale sheep farms, and 88 fecal samples and 13 environmental samples were collected from 12 backyard farms. The presence of G. duodenalis was detected by targeting the β-giardin (bg) gene, and the assemblage and multilocus genotype of G. duodenalis were investigated by analyzing three genes: bg, glutamate dehydrogenase (gdh) and triphosphate isomerase (tpi).
RESULTS: The overall G. duodenalis detection rate was 7.8%, 1.4% and 23.3% in fecal, environmental and water samples, respectively. On the large-scale sheep farms tested, the infection rate of sheep in Henan (13.8%) was found to be significantly higher than that of sheep in Ningxia (4.2%) (P < 0.05). However, the difference between the rates of environmental pollution in Henan (1.9%) and Ningxia (1.0%) was not significant (P > 0.05). Investigations of sheep at different physiological stages revealed that late pregnancy ewes showed the lowest infection rate (1.7%) and that young lambs exhibited the highest (18.8%). Genetic analysis identified G. duodenalis belonging to two assemblages, A and E, with assemblage E being dominant. A total of 27 multilocus genotypes were identified for members of assemblage E.
CONCLUSIONS: The results suggest that G. duodenalis is prevalent on large-scale sheep farms in Henan and Ningxia, China, and that there is a risk of environmental contamination. This study is the first comprehensive examination of the presence of G. duodenalis on large-scale sheep farms in China. Challenges posed by G. duodenalis to sheep farms need to be addressed proactively to ensure public health safety.

Giardia duodenalis is one of the most common causes of waterborne disease worldwide, and is often associated with outbreaks of diarrhea in areas with poor sanitation and hygiene. This study aimed to assess the prevalence and genetic diversity of G. duodenalis assemblages in individuals attending major public hospitals in Shiraz, southwestern Iran. From August 2022 to May 2023, a total of 614 stool samples from individuals were collected and initially examined for G. duodenalis cysts using parasitological techniques, sucrose flotation, and microscopy. Microscopy-positive samples were validated by SSU-PCR amplification of the parasite DNA. A multilocus genotyping (MLG) scheme, which focused on the triose phosphate isomerase (tpi) and the glutamate dehydrogenase (gdh) genes, was employed for genotyping purposes. G. duodenalis cysts were found in 7.5% (46/614) and 8.5% (52/614) of samples through microscopy and SSU-PCR, respectively. Successful amplification and sequencing results were obtained for 77.3% (17/22) and 45.5% (10/22) of the infected samples at the tpi and gdh loci, respectively. MLG data for the two loci were available for only five samples. Out of the 22 samples genotyped at any loci, 54.5% (12/22) were identified as assemblage A, while 45.5% (10/22) were identified as assemblage B. AII was the most predominant sub-assemblage identified [54.5% (12/22)], followed by BIII [27% (6/22)], discordant BIII/BIV [13.6% (3/22)], and BIV [4.5% (1/22)]. In the present study, no assemblages suited for non-human animal hosts (e.g., C-F) were detected. This suggests that the transmission of human giardiasis in Shiraz is primarily anthroponotic. Further molecular-based analyses are necessary to confirm and expand upon these findings. These analyses will also help determine the presence and public health importance of the parasite in environmental samples, such as drinking water.

The glucan content of rice is a key factor defining its nutritional and economic value. Starch and its derivatives have many industrial applications such as in fuel and material production. Non-starch glucans such as (1,3;1,4)-β-D-glucan (mixed-linkage β-glucan, MLG) have many benefits in human health, including lowering cholesterol, boosting the immune system, and modulating the gut microbiome. In this study, the genetic variability of MLG and starch contents were analyzed in rice (Oryza sativa L.) whole grain, by performing a new quantitative analysis of the polysaccharide content of rice grains. The 197 rice accessions investigated had an average MLG content of 252 μg/mg, which was negatively correlated with the grain starch content. A new genome-wide association study revealed seven significant quantitative trait loci (QTLs) associated with the MLG content and two QTLs associated with the starch content in rice whole grain. Novel genes associated with the MLG content were a hexose transporter and anthocyanidin 5,3-O-glucosyltransferase. Also, the novel gene associated with the starch content was a nodulin-like domain. The data pave the way for a better understanding of the genes involved in determining both MLG and starch contents in rice grains and should facilitate future plant breeding programs.

Plant cell walls (PCWs) form the outer barrier of cells that give the plant strength and directly interact with the environment and other cells in the plant. PCWs are composed of several polysaccharides, of which cellulose forms the main fibrillar network. Enmeshed between these fibrils of cellulose are non-cellulosic polysaccharides (NCPs), pectins, and proteins. This study investigates the sequence, timing, patterning, and architecture of cell wall polysaccharide regeneration in suspension culture cells (SCC) of the grass species Lolium multiflorum (Lolium). Confocal, superresolution, and electron microscopies were used in combination with cytochemical labeling to investigate polysaccharide deposition in SCC after protoplasting. Cellulose was the first polysaccharide observed, followed shortly thereafter by (1,3;1,4)-β-glucan, which is also known as mixed-linkage glucan (MLG), arabinoxylan (AX), and callose. Cellulose formed fibrils with AX and produced a filamentous-like network, whereas MLG formed punctate patches. Using colocalization analysis, cellulose and AX were shown to interact during early stages of wall generation, but this interaction reduced over time as the wall matured. AX and MLG interactions increased slightly over time, but cellulose and MLG were not seen to interact. Callose initially formed patches that were randomly positioned on the protoplast surface. There was no consistency in size or location over time. The architecture observed via superresolution microscopy showed similarities to the biophysical maps produced using atomic force microscopy and can give insight into the role of polysaccharides in PCWs.

Cell walls of marine macroalgae are composed of diverse polysaccharides that provide abundant carbon sources for marine heterotrophic bacteria. Among them, Zobellia galactanivorans is considered as a model for studying algae-bacteria interactions. The degradation of typical algal polysaccharides, such as agars or alginate, has been intensively studied in this model bacterium, but the catabolism of plant-like polysaccharides is essentially uncharacterized. Here, we identify a polysaccharide utilization locus in the genome of Z. galactanivorans, induced by laminarin (β-1,3-glucans), and containing a putative GH5 subfamily 4 (GH5_4) enzyme, currently annotated as a endoglucanase (ZgEngAGH5_4). A phylogenetic analysis indicates that ZgEngAGH5_4 was laterally acquired from an ancestral Actinobacteria We performed the biochemical and structural characterization of ZgEngAGH5_4 and demonstrated that this GH5 is, in fact, an endo-β-glucanase, most active on mixed-linked glucan (MLG). Although ZgEngAGH5_4 and GH16 lichenases both hydrolyze MLG, these two types of enzymes release different series of oligosaccharides. Structural analyses of ZgEngAGH5_4 reveal that all the amino acid residues involved in the catalytic triad and in the negative glucose-binding subsites are conserved, when compared with the closest relative, the cellulase EngD from Clostridium cellulovorans, and some other GH5s. In contrast, the positive glucose-binding subsites of ZgEngAGH5_4 are different and this could explain the preference for MLG, with respect to cellulose or laminarin. Molecular dynamics computer simulations using different hexaoses reveal that the specificity for MLG occurs through the +1 and +2 subsites of the binding pocket that display the most important differences when compared with the structures of other GH5_4 enzymes.

BACKGROUND: Giardiasis, caused by Giardia duodenalis (syn. Giardia intestinalis, Giardia lamblia), is a significant zoonotic parasitic disease of animals and humans worldwide. Accurate genotyping of G. duodenalis is essential for efficient control and management of giardiasis. The objectives of the present study were to investigate the prevalence and assemblages of giardiasis in pigs in Shaanxi Province, northwestern China, and for the first time study multilocus genotypes (MLGs) in pigs using multilocus genotyping technology in this region.
RESULTS: Of 560 faecal samples collected from five farms in Shaanxi Province, 45 were positive for G. duodenalis and significant differences in prevalence were observed among different locations. Differences in prevalence were also detected in pigs of different age groups, with the highest prevalence in sows and the lowest in boars. Two assemblages, A and E, were identified, and a mixed infection of both A and E was identified in one faecal sample. Assemblage E was predominant and widely distributed in all investigated areas and age groups. Genetic viability was detected for both assemblages, and four different multi-locus genotypes (MLGs) within assemblage E were found, MLGE1-MLGE4.
CONCLUSIONS: Giardia duodenalis was detected in pigs from Shaanxi Province, northwestern China, and genetic diversity was observed in these infections. Both assemblages A and E were detected, and four distinct MLGs within assemblage E were identified. These findings provide new data for controlling G. duodenalis infection in pigs.

Mixed-linkage (1→3),(1→4)-β-d-glucan (MLG) is a biologically and technologically important hemicellulose, known to occur in three widely separated lineages: the Poales (including grasses and cereals), Equisetum (fern-allies), and some lichens e.g. Iceland moss (Cetraria islandica). Lichenase (E.C. 3.2.1.73) is widely assumed to hydrolyse all (1→4) bonds that immediately follow (1→3) bonds in MLG, generating predominantly the tetrasaccharide β-d-Glcp-(1→4)-β-d-Glcp-(1→4)-β-d-Glcp-(1→3)-d-Glc (G4G4G3G; MLG4), the corresponding trisaccharide (G4G3G; MLG3), and sometimes also laminaribiose (G3G; MLG2). The ratio of the oligosaccharides produced characterises each polysaccharide. We report here that digestion of MLG from barley (Hordeum vulgare), Equisetum arvense and C. islandica by Bacillus subtilis lichenase also yields the unexpectedly stable hexasaccharide, β-d-Glcp-(1→3)-β-d-Glcp-(1→4)-β-d-Glcp-(1→4)-β-d-Glcp-(1→4)-β-d-Glcp-(1→3)-d-Glc (G3G4G4G4G3G, i.e. MLG2-MLG4), identified by thin-layer chromatography, gel-permeation chromatography, HPLC (HPAEC), β-glucosidase digestion, (1)H/(13)C-NMR spectroscopy and mass spectrometry. On HPLC, G3G4G4G4G3G is the major constituent of a peak previously ascribed solely to the nonasaccharide G4G4G4G4G4G4G4G3G. Because it was widely presumed that lichenase would cleave G3G4G4G4G3G to MLG2+MLG4, our data both redefine the substrate specificity of Bacillus lichenase and show previous attempts to characterise MLGs by HPLC of lichenase-digests to be flawed. MLG2 subunits are particularly underestimated; often reported as negligible, they are here shown to be an appreciable constituent of MLGs from all three lineages. We also show that there is no appreciable yield of water-soluble lichenase products with DP>9; potential identities of products previously labelled DP>9 are suggested. Finally, this discovery also provides a opportunity to investigate the spatial distribution of subunits along the MLG chain. We show that MLG2 subunits in barley and Cetraria MLG are not randomly distributed, but predominantly found at the non-reducing end of MLG4 subunits.