Overexpressing CrePAPS Polyadenylate Activity Enhances Protein Translation and Accumulation in Chlamydomonas reinhardtii.

The alga Chlamydomonas reinhardtii is a potential platform for recombinant protein expression in the future due to various advantages. Dozens of C. reinhardtii strains producing genetically engineered recombinant therapeutic protein have been reported. However, owing to extremely low protein expression efficiency, none have been applied for industrial purposes. Improving protein expression efficiency at the molecular level is, therefore, a priority. The 3'-end poly(A) tail of mRNAs is strongly correlated with mRNA transcription and protein translation efficiency. In this study, we identified a canonical C. reinhardtii poly(A) polymerase (CrePAPS), verified its polyadenylate activity, generated a series of overexpressing transformants, and performed proteomic analysis. Proteomic results demonstrated that overexpressing CrePAPS promoted ribosomal assembly and enhanced protein accumulation. The accelerated translation was further verified by increased crude and dissolved protein content detected by Kjeldahl and bicinchoninic acid (BCA) assay approaches. The findings provide a novel direction in which to exploit photosynthetic green algae as a recombinant protein expression platform.

The Dissolution Mechanism of Low-Molecular-Weight Organic Acids on the Sillimanite.

The interaction between low-molecular-weight organic acids (LMWOAs) and minerals in nature has been widely studied; however, limited research has been conducted on the dissolution mechanism of sillimanite in the presence of different organic acids. In this study, the interaction between the sillimanite sample and LMWOAs (citric acid, oxalic acid, and citric/oxalic mixture) at the same pH was investigated. The dissolution rate of Si and Al was high during the initial reaction time, then slowed down in the presence of LMWOAs. The dissolution data for Si and Al from sillimanite in the LMWOAs fit well with the first-order equation (Ct = a(1 - exp(-kt))) (R2 > 0.991). The dissolution process of sillimanite in the organic acids was controlled by the surface chemical reaction step. The dissolution concentration of Si in aqueous citric acid was higher than that in oxalic acid. In contrast, the dissolution concentration of Al in oxalic acid was more than that in citric acid. The maximum concentrations of Si and Al in the presence of composite organic acids were 1754 µmol/L and 3904 µmol/L. The sillimanite before and after treatment with LMWOAs were studied using X-ray diffraction (XRD) and scan electron microscopy (SEM). These results are explained by the characterization of the sillimanite. Under the single acid solution, the (210) crystal plane with a high areal density of Al in sillimanite was easily dissolved by the oxalic acid, while the (120) in sillimanite with a high areal density of Si was more easily dissolved by citric acid. In the composite organic acids, the Si-O bond and Al-O bond in sillimanite were attacked alternately, leading to the formation of some deeper corrosion pits on the surface of sillimanite. The results are of interest in the dissolution mechanisms of sillimanite in the low-molecular-weight organic acids and the environmentally friendly activation of sillimanite.

Chemical synthesis of left arm of Chlamydomonas reinhardtii mitochondrial genome and in vivo functional analysis.

Chlamydomonas reinhardtii is a photosynthetic eukaryote showing great industrial potential. The synthesis and in vivo function of the artificial C. reinhardtii genome not only promotes the development of synthetic biology technology but also supports industries that utilize this algae. Mitochondrial genome (MtG) is the smallest and simplest genome of C. reinhardtii that suits synthetic exploration. In this article, we designed and assembled a synthetic mitochondria left arm (syn-LA) genome sharing >92% similarity to the original mitochondria genome (OMtG) left arm, transferred it into the respiratory defect strain cc-2654, screened syn-LA containing transformants from recovered dark-growth defects using PCR amplification, verified internal function of syn-LA via western blot, detected heteroplasmic ratio of syn-LA, tried promoting syn-LA into homoplasmic status with paromomycin stress, and discussed the main limitations and potential solutions for this area of research. This research supports the functionalization of a synthetic mitochondrial genome in living cells. Although further research is needed, this article nevertheless provides valuable guidance for the synthesis of eukaryotic organelle genomes and opens possible directions for future research.

The Functionally Characterization of Putative Genes Involved in the Formation of Mannose in the Aplanospore Cell Wall of Haematococcus pluvialis (Volvocales, Chlorophyta).

Unicellular volvocalean green algal Haematococcus pluvialis, known as astaxanthin rich microalgae, transforms into aplanospore stage from the flagellate stage when exposed to the stress environments. However, the mechanism of the formation of aplanospore cell wall, which hinders the extraction of astaxanthin and the genetic manipulation is still unclear. In this study, the cell wall components under salicylic acid and high light stresses were explored, and cellulose was considered the main component in the flagellates, which changed gradually into mannose in the aplanospore stages. During the period, the genes related to the cellulose and mannose metabolisms were identified based on the RNA-seq data, which presented a similar expression pattern. The positive correlations were observed among these studied genes by Pearson Correlation (PC) analysis, indicating the coordination between pathways of cellulose and mannose metabolism. The study firstly explored the formation mechanism of aplanospore cell wall, which might be of scientific significance in the study of H. pluvialis.

A new species and new record of Polycystididae (Rhabdocoela: Kalyptorhynchia) from China.

One new species and one newly recorded species of Polycystididae from China, Paulodora sinensis n. sp. and Polycystis ali Schockaert, 1982, were described based on comprehensive morphological and molecular analyses. In Paulodora sinensis n. sp., the stylet is double-walled and is composed of a funnel-shaped proximal part and a spiral distal part, while the outer stylet forms a minor fold proximally. In Polycystis ali Schockaert, 1982, the stylet is also double-walled with a funnel-shaped proximal part. However, the collar-shaped distal part is partially concave and forms a jagged edge. The concatenated 18S rDNA and 28S rDNA phylogenetic analysis supports the establishment of the new species. Besides, based on the morphology of stylet, we have made detailed categorization among the recorded species within these two genera.

Two new species of Kalyptorhynchia (Koinocystididae and Gnathorhynchidae) from China.

Two new species of Kalyptorhynchia (Rhabdocoela), namely Itaipusa sinensis n. sp. (Koinocystididae) and Prognathorhynchus sinensis n. sp. (Gnathorhynchidae) were described from brackish water near Shenzhen Bay, representing the first records of Koinocystididae and Gnathorhynchidae in China. For I. sinensis n. sp., the U-shaped cirrus contains 50 triangular lamellar spines, with two cuticular (pseudocuticular) hooks situated at both sides of its anterior part. The hook I (right side) is funnel-shaped, while the hook II (left side) is triangular lamellar in shape. For P. sinensis n. sp., the proboscis hook has two hooks situated in an anterior to posterior sequence. The semicircular tubular stylet has a hollow spherical dead end posteriorly to the distal opening. Both the morphological and phylogenetic (18S rDNA and 28S rDNA) analyses support the establishment of these two new species.

A new species of the genus Bothrioplana (Platyhelminthes: Bothrioplanida: Bothrioplanidae) and a new species of the genus Pentacoelum (Tricladida: Bdellouridae) from southern China.

Two new species of turbellarians, Bothrioplana sinensis n. sp., and Pentacoelum sinensis n. sp., were described based on their reproductive behavior, ontogenic development, morphology in whole-mounted and sectioned specimens, and 18S rDNA phylogenetic classification. Bothrioplana sinensis n. sp. represents a newly recorded order in China and the second identified species in the genus Bothrioplana. It is characterized by a pair of spherical-shaped well-developed testes located dorsally behind the pharynx, and the common vas deference located ventrally to the gonopore. Phylogenetic analysis showed that this new species is closely related to parasitic flatworms. Pentacoelum sinensis n. sp. is characterized by two uteri instead of lateral bursae located laterally near the tail end and a lack of connection between the posterior intestinal branches. Each uterus has a ventral receptaculum seminalis (also functioning as bursa copulatrix) which has a muscular vagina externa opening obliquely to the ventral side at the tail end.