Cross-species microbial genome transfer: a Review

Synthetic biology combines the disciplines of biology, chemistry, information science, and engineering, and has multiple applications in biomedicine, bioenergy, environmental studies, and other fields. Synthetic genomics is an important area of synthetic biology, and mainly includes genome design, synthesis, assembly, and transfer. Genome transfer technology has played an enormous role in the development of synthetic genomics, allowing the transfer of natural or synthetic genomes into cellular environments where the genome can be easily modified. A more comprehensive understanding of genome transfer technology can help to extend its applications to other microorganisms. Here, we summarize the three host platforms for microbial genome transfer, review the recent advances that have been made in genome transfer technology, and discuss the obstacles and prospects for the development of genome transfer.

The cAMP-PKA signalling pathway regulates hyphal growth, conidiation, trap morphogenesis, stress tolerance, and autophagy in Arthrobotrys oligospora

The cyclic adenosine monophosphate-protein kinase A (cAMP-PKA) signalling pathway is evolutionarily conserved in eukaryotes and plays a crucial role in defending against external environmental challenges, which can modulate the cellular response to external stimuli. Arthrobotrys oligospora is a typical nematode-trapping fungus that specializes in adhesive networks to kill nematodes. To elucidate the biological roles of the cAMP-PKA signalling pathway, we characterized the orthologous adenylate cyclase AoAcy, a regulatory subunit (AoPkaR), and two catalytic subunits (AoPkaC1 and AoPkaC2) of PKA in A. oligospora by gene disruption, transcriptome, and metabolome analyses. Deletion of Aoacy significantly reduced the levels of cAMP and arthrobotrisins. Results revealed that Aoacy, AopkaR, and AopkaC1 were involved in hyphal growth, trap morphogenesis, sporulation, stress resistance, and autophagy. In addition, Aoacy and AopkaC1 were involved in the regulation of mitochondrial morphology, thereby affecting energy metabolism, whereas AopkaC2 affected sporulation, nuclei, and autophagy. Multi-omics results showed that the cAMP-PKA signalling pathway regulated multiple metabolic and cellular processes. Collectively, these data highlight the indispensable role of cAMP-PKA signalling pathway in the growth, development, and pathogenicity of A. oligospora, and provide insights into the regulatory mechanisms of signalling pathways in sporulation, trap formation, and lifestyle transition.

Regulatory Mechanism of Trap Formation in the Nematode-Trapping Fungi

Nematode-trapping (NT) fungi play a significant role in the biological control of plant- parasitic nematodes. NT fungi, as a predator, can differentiate into specialized structures called “traps” to capture, kill, and consume nematodes at a nutrient-deprived condition. Therefore, trap formation is also an important indicator that NT fungi transition from a saprophytic to a predacious lifestyle. With the development of gene knockout and multiple omics such as genomics, transcriptomics, and metabolomics, increasing studies have tried to investigate the regulation mechanism of trap formation in NT fungi. This review summarizes the potential regulatory mechanism of trap formation in NT fungi based on the latest findings in this field. Signaling pathways have been confirmed to play an especially vital role in trap formation based on phenotypes of various mutants and multi-omics analysis, and the involvement of small molecule compounds, woronin body, peroxisome, autophagy, and pH-sensing receptors in the formation of traps are also discussed. In addition, we also highlight the research focus for elucidating the mechanism underlying trap formation of NT fungi in the future.

AoSsk1, a Response Regulator Required for Mycelial Growth and Development, Stress Responses, Trap Formation, and the Secondary Metabolism in Arthrobotrys oligospora

Ssk1, a response regulator of the two-component signaling system, plays an important role in the cellular response to hyperosmotic stress in fungi. Herein, an ortholog of ssk1 (Aossk1) was characterized in the nematode-trapping fungus Arthrobotrys oligospora using gene disruption and multi-phenotypic comparison. The deletion of Aossk1 resulted in defective growth, deformed and swollen hyphal cells, an increased hyphal septum, and a shrunken nucleus. Compared to the wild-type (WT) strain, the number of autophagosomes and lipid droplets in the hyphal cells of the ΔAossk1 mutant decreased, whereas their volumes considerably increased. Aossk1 disruption caused a 95% reduction in conidial yield and remarkable defects in tolerance to osmotic and oxidative stress. Meanwhile, the transcript levels of several sporulation-related genes were significantly decreased in the ΔAossk1 mutant compared to the WT strain, including abaA, brlA, flbC, fluG, and rodA. Moreover, the loss of Aossk1 resulted in a remarkable increase in trap formation and predation efficiency. In addition, many metabolites were markedly downregulated in the ΔAossk1 mutant compared to the WT strain. Our results highlight that AoSsk1 is a crucial regulator of asexual development, stress responses, the secondary metabolism, and pathogenicity, and can be useful in probing the regulatory mechanism underlying the trap formation and lifestyle switching of nematode-trapping fungi.

Identification and Characterization of Major Constituents in Different-Colored Rapeseed Petals by UPLC-HESI-MS/MS

Oilseed rape (Brassica napus L.) is the second highest yielding oil crop worldwide. In addition to being used as an edible oil and a feed for livestock, rapeseed has high ornamental value. In this study, we identified and characterized the main floral major constituents, including phenolic acids and flavonoids components, in rapeseed accessions with different-colored petals. A total of 144 constituents were identified using ultrahigh-performance liquid chromatography-HESI-mass spectrometry (UPLC-HESI-MS/MS), 57 of which were confirmed and quantified using known standards and mainly contained phenolic acids, flavonoids, and glucosinolates compounds. Most of the epicatechin, quercetin, and isorhamnetin derivates were found in red and pink petals of B. napus, while kaempferol derivates were in yellow and pale white petals. Moreover, petal-specific compounds, including a putative hydroxycinnamic acid derivative, sinapoyl malate, 1-O-sinapoyl-β-d-glucose, feruloyl glucose, naringenin-7-O-glucoside, cyanidin-3-glucoside, cyanidin-3,5-di-O-glucoside, petunidin-3-O-β-glucopyranoside, isorhamnetin-3-O-glucoside, kaempferol-3-O-glucoside-7-O-glucoside, quercetin-3,4'-O-di-β-glucopyranoside, quercetin-3-O-glucoside, and delphinidin-3-O-glucoside, might contribute to a variety of petal colors in B. napus. In addition, bound phenolics were tentatively identified and contained three abundant compounds (p-coumaric acid, ferulic acid, and 8-O-4'-diferulic acid). These results provide insight into the molecular mechanisms underlying petal color and suggest strategies for breeding rapeseed with a specific petal color in the future.

[Clinical analysis of idiopathic sudden sensorineural hearing loss with vertigo and without vertigo]

Objective:To explore the clinical characteristics and treatments of patients with idiopathic sudden sensorineural hearing loss（ISSHL） with or without vertigo. Method:One hundred and twenty ISSHL cases were divided into vertigo group (n=36) , without vertigo group (n=84) , and with benign paroxysmal positional vertigo group (n=15). All patients were in regular treatment. Besides, according to the types of BPPV, patients do the Epley maneuver or Barbecue roll maneuver. We summarized the result and treatment of the patients. Result:The audiometric curve of ISSHL with vertigo were mainly at flat type. After treatment of the ISSHL patients were better than the patients with vertigo in the degrees of hearing loss . Furthermore, the rate of the patients of marked efficiency, efficiency and total efficiency of ISSHL was lower than the ones without.The patients with BPPV, including 12 cases of posterior semicircular canal and the 3 cases of lateral semicircular canal, were all ipsilateral. Conclusion:ISSHL with vertigo group lost hearing is severer than ISSHL without vertigo. Thus the hearing and the treatment effect were worse.The symptoms without vertigo in ISSHL were better than the patients with vertigo.

[Experimental studies of the protective effects of basic fibroblast growth factor and Radix Salviae Miltiorrhizae on brain injury in rats caused by repeated exposures to +Gz]

Objective. To investigate the preventive and theralseutive (therapeutic) effects of basic fibroblast growth factor (bFGF) and Radix Salviae Miltiorrhizae (RSM) on brain injury caused by repeated +Gz exposures. Method. bFGF and RSM were injected intraperitoneally into SD rats before and after repeated +Gz exposures. The contents of excitatory amino acids (EAAs), nitric oxide (NO) and the number of cell apoptosis in the brain were measured, and were compared to those of the control group and normal saline (NS) group. Result. The contents of EAAs, NO and the number of cell apoptosis were significantly higher in repeated +Gz exposures group than those in control group. The values were markedly lower in bFGF and RSM group than those in repeated +Gz exposures group and NS group. Conclusion. bFGF and RSM showed distinct preventive and therapeutic effect on the brain injury induced by repeated +Gz exposures.

[Changes of mRNA expression of IL-1beta and TNF-alpha in rat brains after repeated exposures to +Gz]

Objective. To study changes of mRNA expression of IL-1beta and TNF-alpha in rat brains after repeated exposures to +Gz. Method. Twenty conscious SD rats served as the subjects. They were randomly divided into 5 groups. Using an animal centrifuge, control rats (n = 4) were exposed to +1 Gz and experimental rats (n = 16) were exposed to +14 Gz three times, each for 45 s with 30 min interval in between. The rat brains were taken 30 min, 6 h, 24 h and 48 h after the last centrifuge run and total RNA was isolated. mRNA expression levels of IL-1beta and TNF-alpha in rat brain were measured by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). Result. mRNA expression levels of IL-1beta and TNF-alpha in rat brains taken 30 min, 6 h and 24 h after repeated +Gz exposures were significantly higher than those in control rats, but returned to normal after 48 h. Conclusion. It suggested that mRNA expressions of IL-1beta and TNF-alpha in rat brains can be stimulated by repeated +Gz exposures and the increased expression of IL-1beta and TNF-alpha may play a role in the pathologic course of brain damage induced by +Gz exposures, but the damage is reversible.

[A study of apoptosis and related gene bcl-2 and p53 expression in hippocampus of rats exposed to repeated +Gz]

Objective. To investigate the role of apoptosis in mechanisms of brain damage induced by +Gz exposures. Method. Twenty conscious SD rats were randomly divided into 5 groups. Rats in the control group (n=4) were exposed to +1 Gz and rats in the 4 experimental groups (n=16) were exposed to +14 Gz for three times, each for 45 seconds with 30 min interval in between. All the +Gz exposured were on an animal centrifuge. The rat brains were taken 30 min, 6 h, 24 h and 48 h after the last centrifuge run and fixed and embedded. The apoptosis and expression changes of related gene bcl-2 and p53 were detected by terminal deoxynucleotide (correction of deoxynuleotide) transferase-mediated dUTP nick end labeling (TUNEL) technique and immunohistochemical method, respectively. Result. Apoptotic cells and expression changes of bcl-2 and p53 were observed in CA1 subregion of rat hippocampus taken 6 h after repeated +Gz exposures, but returned to normal after 24-48 h. Conclusion. It suggests that apoptosis and expression changes of bcl-2 and p53 in rats hippocampus can be induced by repeated +Gz exposures and the apoptosis is one of the molecular mechanisms of brain damage induced by repeated +Gz exposures.

Purification and properties of acetylcholinesterase from human brain

Acetylcholinesterase from human caudate nucleus and partial thalamus was purified by using Con A-Sepharose, short-arm and long-arm ligand Sepharose affinity chromatographies. SDS-PAGE of the purified AChE under the reduced condition showed one main band, corresponding to a molecular weight of 66 kD. The purified AChE with a specific activity of 3384 U/mg protein represented 20% activity of the homogenate supernatant. Analysis of purified AChE by gradient slab PAGE and DISC-PAGE with activity staining revealed the existence of monomer, dimer, tetramer, hexamer and octomer of the enzyme. The isoelectric point of AChE ranged between pH 5.6 and 6.0. Con A-Sepharose affinity chromatography retained most of the applied AChE activity implying that the enzyme is a kind of glycoprotein. The isolated human brain AChE had no cross-immunoreactivity with 3F3 and weak cross-immunoreactivity with 2G8 and 1H11 anti-Torpedo AChE antibodies. Balb/c mice were immunized with human cerebellum AChE purified with Con A and short-arm ligand affinity chromatographies. The antiserum produced showed strong cross-immunoreactivity with Torpedo AChE but weak cross-immunoreactivity with human RBC membrane AChE. The purified human brain striatum AChE was reduced and alkylated, and then hydrolyzed by immobilized TPCK-treated trypsin. Trypsin peptides in the hydrolysate was separated by RP-HPLC. Several large peptide peaks and numbers of small peaks were observed. The large peaks showed obvious immunoreactivity with the mouse anti human cerebellum AChE antiserum.