Relationships between wild bee abundance and fruit set of Camellia oleifera Abel

Camellia oleifera Abel. is an economically important plant for edible oils. To investigate the importance of wild bee abundance at different canopy and spatial scale for fruit set of Camellia oleifera, we evaluated the relationship of bee abundance with fruit set using yellow pan trap, with additional focus on distance and wild bee abundance counts at a farm in China for 2 years. We found that yellow traps collected 95% more individual bees than the second-best (pink) trap colour. Looking across canopy positions, the number of wild bees (including Colletes gigas, Andrena camellia, Andrena striata, Andrena hunanensis and Andrena chekiangensis) varied significantly in each year. The fruit set also varied significantly based on canopy position. In 2018, there was with an average fruit set of 34.13% in the lower canopy, 54.30% in the middle canopy and 47.41% in the upper canopy. In 2019, fruit set was 29.67% in the lower canopy, 54.15% in the middle canopy and 47.36% in the upper canopy. Comparing inter-annual changes, only the fruit set and number of bees in the low canopy showed significant differences between 2018 and 2019. Fruit set and wild bee abundance were positively correlated in all canopy layers in each year, and there was an interactive effect between canopy and bee abundance on fruit set. Across 205 trees, growth indicators, crown size and tree height, increased significantly from 2018 to 2019, but the fruit set did not increase with the significant increase in the number of flowers. From the spatial perspective, wild bee abundance and fruit set were positively correlated, but fruit set was negatively correlated with distance from a large bee nesting aggregation nearby. Among the variables investigated, bee abundance seems to have the strongest influence on fruit set in C. oleifera.     

The Small Subunit Ribosomal RNA Gene Sequence of Pleistophora anguillarum and The Use of PCR Primers for Diagnostic Detection of the Parasite

Using the polymerase chain reaction (PCR) and two primers for conserved regions of the small subunit ribosomal RNA (SSU-rRNA.) of Microsporidia, a DNA segment about 1,195 base pairs long was amplified from a DNA template prepared from purified spores of the microsporidian species Pleistophora anguillarum. These spores had been isolated from adult eels ( Anguilla japonica ) with "Beko Disease." A comparison of sequence data from other microsporidian species showed P. anguillarum SSU-rRNA to be most similar to Vavraia oncoperae. When juvenile eels were artificially infected with P. anguillarum , enzyme-linked immunosorbent assay could detect a positive infection only 12 days post-infection. However, when suitable PCR primers were used, a DNA fragment of about 0.8 kb was detected from these juvenile eels after only 3 days post-infection. No PCR product was obtained with templates prepared from clinically healthy control animals.     

Biallelic β‐carotene oxygenase 2 knockout results in yellow fat in sheep via CRISPR/Cas9

The recently emerged CRISPR/Cas9 approach represents an efficient and versatile genome editing tool for producing genetically modified animals. Β‐carotene oxygenase 2 (BCO2) is a key enzyme in the progress of β‐carotene metabolism and is associated with yellow adipose tissue color in sheep. We have recently demonstrated targeted multiplex mutagenesis in sheep and have generated a group of BCO2‐disrupted sheep by zygote injection of the CRISPR/Cas9 components. Here, we show that biallelic modification of BCO2 resulted in yellow fat, compared with the fat color in monoallelic individuals and wild types (snow‐flower white). We subsequently characterized the effects of gene modifications at genetic levels employing sequencing and Western blotting, highlighting the importance of the BCO2 gene for the determination of fat color in sheep. These results indicate that genetic modification via CRISPR/Cas9 holds great potential for validating gene functions as well as for generating desirable phenotypes for economically important traits in livestock.     

Structural mechanism of cooperative activation of the human calcium-sensing receptor by Ca2+ ions and L-tryptophan

The human calcium-sensing receptor (CaSR) is a class C G protein-coupled receptor (GPCR) responsible for maintaining Ca²⁺ homeostasis in the blood. The general consensus is that extracellular Ca²⁺ is the principal agonist of CaSR. Aliphatic and aromatic L-amino acids, such as L-Phe and L-Trp, increase the sensitivity of CaSR towards Ca²⁺ and are considered allosteric activators. Crystal structures of the extracellular domain (ECD) of CaSR dimer have demonstrated Ca²⁺ and L-Trp binding sites and conformational changes of the ECD upon Ca²⁺/L-Trp binding. However, it remains to be understood at the structural level how Ca²⁺/L-Trp binding to the ECD leads to conformational changes in transmembrane domains (TMDs) and consequent CaSR activation. Here, we determined the structures of full-length human CaSR in the inactive state, Ca²⁺- or L-Trp-bound states, and Ca²⁺/L-Trp-bound active state using single-particle cryo-electron microscopy. Structural studies demonstrate that L-Trp binding induces the closure of the Venus flytrap (VFT) domain of CaSR, bringing the receptor into an intermediate active state. Ca²⁺ binding relays the conformational changes from the VFT domains to the TMDs, consequently inducing close contact between the two TMDs of dimeric CaSR, activating the receptor. Importantly, our structural and functional studies reveal that Ca²⁺ ions and L-Trp activate CaSR cooperatively. Amino acids are not able to activate CaSR alone, but can promote the receptor activation in the presence of Ca²⁺. Our data provide complementary insights into the activation of class C GPCRs and may aid in the development of novel drugs targeting CaSR.Subject terms: Cryoelectron microscopy, Calcium signalling     

LPS induces fibroblast-like synoviocytes RSC-364 cells to pyroptosis through NF-κB mediated dual signalling pathway

Journal of Molecular Histology - Rheumatoid arthritis (RA) is a chronic, progressive, and systemic inflammatory joint disease characterized by synovial inflammation and joint damage. Abnormal...     

Isolation,stereochemical study,and racemization of (±)-pratenone A,the first naturally occurring 3-(1-naphthyl)-2-benzofuran-1(3H)-one polyketide from a marine-derived actinobacterium

(±)-Pratenone A ( 1 ), the first representative of natural 3-(1-naphthyl)-2-benzofuran-1(3H)-one polyketides, was isolated from a marine-derived Streptomyces pratensis strain KCB-132 together with three other new analogues ( 2−4 ). Its structure was assigned by spectroscopic analysis, and the absolute configurations of the two enantiomers separated by high-performance liquid chromatography were determined by single-crystal X-ray diffraction and electronic circular dichroism calculations. The solvent-induced racemization of 1 and a proposed biogenetic pathway to 1−4 from the co-isolated angucyclinone precursor, as well as their biological activity, are also discussed.     

Structural analysis of the mouse T-cell receptor Tcra V2 subfamily

Cosmid clones containing T-cell receptor Tcra V2 subfamily gene segments have been isolated from a BALB/c cosmid library and subjected to DNA sequence analysis. The V gene segments in the Tcra V2 subfamily differ from each other by 3%–7% at the nucleotide level and 5%–16% at the amino acid level. T-cell receptor Tcra V2 gene segment polymorphisms have been identified in the B10.PL and PL/J mouse strains with a Tcra V2 subfamily-specific probe. These V gene segment polymorphisms may cause the differential Tcra V gene usage in induced experimental allergic encephalomyelitis between B10.PL and PL/J mice.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide database and have been assigned the accession numbers U04312 and U04622-U04626     

Time to update the sectional classification of Ilex (Aquifoliaceae): New insights from Ilex phylogeny,morphology, and distribution

Resolving the infrageneric classification of species-rich genera has been challenging in plant taxonomy. Ilex L. is a subcosmopolitan genus with over 600 species of dioecious trees and shrubs. Many classification systems based on morphological data have been proposed during the past 250 years. However, these systems (such as Loesener's and Galle's systems) may not truly reflect Ilex's evolutionary trajectories because most of those system's infrageneric hierarchies are not monophyletic. In this study, we reconstructed a phylogeny of Ilex L. comprising 15 moderately to highly supported clades using rigorously identified samples (202 species) and closely authenticated gene sequences of three nuclear genes [internal transcribed spacer (ITS), external transcribed spacer (ETS), and nepGS]. The newly generated phylogenetic tree resembles essentially that of the nuclear tree of Manen et al., but shows conspicuous topological differences with the phylogeny of Yao et al. Closely scrutinizing morphological variation and distributional patterns of 202 species, this study found that most lineages of Ilex identified herein are well defined by a particular trait or a combination of morphological and distributional traits, displaying phylogeny–morphology–distribution conformity that has seldom been uncovered in previous studies. Given the general phylogeny–morphology–distribution conformity revealed in this genus, we put forward an updated sectional classification system for Ilex that temporarily contains 14 sections. The new classification will provide a robust framework for studying the evolution and diversification of this ecologically and economically important genus.