Biology subjects

Zeng, Q.

Publications and source records attributed to Zeng, Q..

5 recordsLinked to original sources

bioRxiv2018

Transcriptomic responses of the marine cyanobacterium Prochlorococcus to viral lysis products

Marine phytoplankton contributes to about one half of global primary production, and a significant proportion of their photosynthetically fixed organic carbon is released after viral infection as dissolved organic matter (DOM). This DOM pool is known to be consumed by heterotrophic microorganisms; however, its impact on the uninfected co-occurring phytoplankton remains largely unknown. Here, we conducted transcriptomic analyses to study the effects of viral lysis products on the unicellular cyanobacterium Prochlorococcus, which is the most abundant photosynthetic organism on Earth. While Prochlorococcus growth was not affected by viral lysis products, many tRNAs increased in abundance, which was also seen after amino acid addition, suggesting that amino acids are one of the compounds in viral lysis products that affected the expression of tRNA genes. The decreased transcript abundances of N metabolism genes also suggested that Prochlorococcus responded to organic N compounds, consistent with abundant amino acids in viral lysis products. The addition of viral lysis products to Prochlorococcus reduced the maximum photochemical efficiency of photosystem II and CO2 fixation while increased its respiration rate, consistent with differentially expressed genes related to photosynthesis and respiration. One of the highest positive fold-changes was observed for the 6S RNA, a non-coding RNA functioning as a global transcriptional regulator in bacteria. The high level of 6S RNA might be responsible for some of the observed transcriptional responses. Taken together, our results revealed the transcriptional regulation of Prochlorococcus in response to viral lysis products and suggested its metabolic potential to utilize organic N compounds.\n\nImportancePhotosynthetic microorganisms called phytoplankton are abundant in the oceans and contribute to about one half of global CO2 fixation. Phytoplankton are frequently infected by viruses and after infection their organic carbon is released into the ocean as dissolved organic matter (DOM). Marine DOM is important for the marine food web because it supports the growth of heterotrophic microorganisms. However, the impact of viral DOM on the uninfected phytoplankton is largely unknown. In this study, we conducted transcriptomic analyses and identified many differentially expressed genes when viral DOM was added to the marine cyanobacterium Prochlorococcus. One effect of viral DOM is that the carbon fixation of Prochlorococcus was reduced by ~16%, which might affect carbon cycling in the worlds oceans since Prochlorococcus is the most abundant photosynthetic organism on Earth.

microbiology↗

bioRxiv2018

WDR45 contributes to neurodegeneration through regulation of ER homeostasis and neuronal death

Mutations in the autophagy gene WDR45 cause {beta}-propeller protein-associated neurodegeneration (BPAN); however the molecular and cellular mechanism of the disease process is largely unknown. Here we generated constitutive Wdr45 knockout (KO) mice that displayed cognitive impairments, abnormal synaptic transmission and lesions in hippocampus and basal ganglia. Immunohistochemistry analysis shows loss of neurons in prefrontal cortex and basal ganglion in aged mice, and increased apoptosis in these regions, recapitulating a hallmark of neurodegeneration. Quantitative proteomic analysis shows accumulation of endoplasmic reticulum (ER) proteins in KO mouse. Furthermore, we show that a defect in autophagy results in impaired ER turnover and ER stress. The unfolded protein response (UPR) is elevated through IRE1 and possibly other kinase signaling pathways, and eventually leads to neuronal apoptosis. Suppression of ER stress, or activation of autophagy through inhibition of mTOR pathway rescues neuronal death. Thus, our study not only provides mechanistic insights for BPAN, but also suggests that a defect in macroautophagy machinery leads to impairment in selective organelle autophagy.

cell biology↗

bioRxiv2018

Whole genome analysis illustrates global clonal population structure of the ubiquitous dermatophyte pathogen Trichophyton rubrum

Dermatophytes include fungal species that infect humans, as well as those which also infect other animals or only grow in the environment. The dermatophyte species Trichophyton rubrum is a frequent cause of skin infection in immunocompetent individuals. While members of the T. rubrum species complex have been further categorized based on various morphologies, the population structure and ability to undergo sexual reproduction are not well understood. In this study, we analyze a large set of T. rubrum and Trichophyton interdigitale isolates to examine mating types, evidence of mating, and genetic variation. We find that nearly all isolates of T. rubrum are of a single mating type, and that incubation with T. rubrum morphotype megninii isolates of the other mating type failed to induce sexual development. While the region around the mating type locus is characterized by a higher frequency of SNPs compared to other genomic regions, we find that the population is remarkably clonal, with highly conserved gene content, low levels of variation, and little evidence of recombination These results support a model of recent transition to asexual growth when this species specialized to growth on human hosts.\n\nData access: Genome sequence data is available in NCBI under the Umbrella BioProject PRJNA186851.

genetics↗

bioRxiv2017

Cyanophages exhibit rhythmic infection patterns under light-dark cycles

Most living organisms exhibit diurnal rhythms as an adaptation to the daily light-dark (diel) cycle. However, diurnal rhythms have not been found in viruses. Here, we studied the diel infection patterns of bacteriophages infecting the unicellular cyanobacteria Prochlorococcus and Synechococcus, which are the most abundant photosynthetic organisms in the oceans. With lab cultures, we found that cyanophages used three infection strategies in the dark: no adsorption, adsorption but no replication, and replication. Interestingly, the former two exhibited rhythmic infection patterns under light-dark cycles. We further showed in the South China Sea and the Western Pacific Ocean that cyanophage abundances varied rhythmically, with a peak at night. Moreover, diel transcriptional rhythms of many cyanophage genes were found in the North Pacific Subtropical Gyre, which also peaked at night. Our results suggested that cyanophage infection of Prochlorococcus is synchronized to the light-dark cycle, which may result in a synchronized release of dissolved organic matter to the marine food web.

microbiology↗

bioRxiv2017

Artemisinin mimics nitric oxide to reduce adipose weight by targeting mitochondrial complexes

It remains obscure how to medically manage visceral obesity that predisposes metabolic disorders. Here, we show for the first time that a trace amount of artemisinin (0.25 mg/kg) reduces adipose weight in an inflammatory obese mouse model induced by a high-fat diet with lipopolysaccharide (HFD+LPS). HFD+LPS trigger pro-inflammatory responses, upregulate NOS2 expression, elicit potent nitric oxide (NO) burst, and reinforce adipose mitochondrial dysfunctions that facilitate adipogenesis for visceral weight gain. By targeting mitochondrial complexes, artemisinin resembles the NO donor nitroglycerin to exert anti-inflammatory effects, downregulate NOS2 expression, maintain stable NO release, and augment adipose mitochondrial functions that necessitate adipolysis for visceral weight loss. Taken together, artemisinin plays adipose weight-reducing roles by rectifying inflammation-driven mitochondrial dysfunctions.

pharmacology and toxicology↗