Spikes with short inter-spike intervals in frog retinal ganglion cells are more correlated with their adjacent neurons’ activities

Correlated firings among neurons have been extensively investigated; however, previous studies on retinal ganglion cell (RGC) population activities were mainly based on analyzing the correlated activities between the entire spike trains. In the present study, the correlation properties were explored based on burst-like activities and solitary spikes separately. The results indicate that: (1) burst-like activities were more correlated with other neurons’ activities; (2) burst-like spikes correlated with their neighboring neurons represented a smaller receptive field than that of correlated solitary spikes. These results suggest that correlated burst-like spikes should be more efficient in signal transmission, and could encode more detailed spatial information.     

Extracellular vesicles package dsDNA to aggravate Crohn’s disease by activating the STING pathway

Crohn’s disease (CD) is an intestinal immune-dysfunctional disease. Extracellular vesicles (EVs) are membrane-enclosed particles full of functional molecules, e.g., nuclear acids. Recently, EVs have been shown to participate in the development of CD by realizing intercellular communication among intestinal cells. However, the role of EVs carrying double-strand DNA (dsDNA) shed from sites of intestinal inflammation in CD has not been investigated. Here we isolated EVs from the plasma or colon lavage of murine colitis and CD patients. The level of exosomal dsDNA, including mtDNA and nDNA, significantly increased in murine colitis and active human CD, and was positively correlated with the disease activity. Moreover, the activation of the STING pathway was verified in CD. EVs from the plasma of active human CD triggered STING activation in macrophages in vitro. EVs from LPS-damaged colon epithelial cells were also shown to raise inflammation in macrophages via activating the STING pathway, but the effect disappeared after the removal of exosomal dsDNA. These findings were further confirmed in STING-deficient mice and macrophages. STING deficiency significantly ameliorated colitis. Besides, potential therapeutic effects of GW4869, an inhibitor of EVs release were assessed. The application of GW4869 successfully ameliorated murine colitis by inhibiting STING activation. In conclusion, exosomal dsDNA was found to promote intestinal inflammation via activating the STING pathway in macrophages and act as a potential mechanistic biomarker and therapeutic target of CD.Subject terms: Acute inflammation, Monocytes and macrophages, Signal transduction     

Detection of sequence variation and genotyping of polymorphic genes using polymerase chain reaction stem–loop conformational polymorphism analysis

Here we describe a technique we have named polymerase chain reaction stem–loop conformational polymorphism (PCR–SLCP) analysis for screening DNA sequence variation. This technique uses PCR primers with adapters at the 5′ ends to generate amplicons containing inverted terminal repeat sequences. These enable the formation of specific conformers for single-stranded molecules on denaturation, and sequence variation in the loop region may affect the structure of these and their mobilities during electrophoresis. The technique has the ability to resolve sequence variation in amplicons that cannot be resolved using PCR single-strand conformational polymorphism (PCR–SSCP). PCR–SLCP is simple and sensitive, and the results are highly repeatable.     

A fine balance between CCNL1 and TIMP1 contributes to the development of breast cancer cells

Cyclin L1 (CCNL1) and tissue inhibitor of matrix metalloproteinase-1 (TIMP1) are candidate genes involved in several types of cancer. However, the expression of CCNL1 and the relationship between CCNL1 and TIMP1 in breast cancer cells is unknown. Using patients’ breast cancer tissues, the expression of CCNL1 and TIMP1 was measured by cDNA microarray and further confirmed by real-time RT-PCR and western blotting. Overexpression or repression of CCNL1 and TIMP1, individually or together, was performed in breast cancer MDA-MB-231 cells by transient transformation methods to investigate their role in breast cancer cell growth. Simultaneously, mRNA and protein expression levels of CCNL1 and TIMP1 were also measured. CCNL1 and TIMP1 expression was significantly elevated in breast cancer tissues compared with that in peri-breast cancer tissues of patients by cDNA microarray and these results were further confirmed by real-time RT-PCR and western blotting. Interestingly, in vitro experiments showed a stimulatory effect of TIMP1 and an inhibitory effect of CCNL1 on growth of MDA-MB-231 cells. Co-expression or co-repression of these two genes did not affect cell growth. Overexpression of CCNL1 and TIMP1 individually induced overexpression of each other. These data demonstrate that there is a fine balance between CCNL1 and TIMP1, which may contribute to breast cancer development.     

Engineering tocopherol biosynthetic pathway in lettuce

In order to increase tocopherol content, genes encoding Arabidopsis homogentisate phytyltransferase (HPT) and γ-tocopherol methyltransferase (γ-TMT) were constitutively over-expressed in lettuce (Lactuca sativa L. var. logifolia), alone or in combination. Over-expression of hpt could increase total tocopherol content, while over-expression of γ-tmt could shift tocopherol composition in favor of α-tocopherol. Transgenic lettuce lines expressing both hpt and γ-tmt produced significantly higher amount of tocopherol and elevated α-/γ-tocopherol ratio compared with non-transgenic control and transgenic lines harboring a single gene (hpt or γ-tmt). The best line produced eight times more tocopherol than the non-transgenic control and more than twice than hpt single-gene transgenic line.