Real-time imaging of bHLH transcription factors reveals their dynamic control in the multipotency and fate choice of neural stem cells

The basic-helix-loop-helix (bHLH) transcription factors Ascl1/Mash1, Hes1, and Olig2 regulate the fate choice of neurons, astrocytes, and oligodendrocytes, respectively; however, these factors are coexpressed in self-renewing multipotent neural stem cells (NSCs) even before cell fate determination. This fact raises the possibility that these fate determination factors are differentially expressed between self-renewing and differentiating NSCs with unique expression dynamics. Real-time imaging analysis utilizing fluorescent proteins is a powerful strategy for monitoring expression dynamics. Fusion with fluorescent reporters makes it possible to analyze the dynamic behavior of specific proteins in living cells. However, it is technically challenging to conduct long-term imaging of proteins, particularly those with low expression levels, because a high-sensitivity and low-noise imaging system is required, and very often bleaching of fluorescent proteins and cell toxicity by prolonged laser exposure are problematic. Furthermore, to analyze the functional roles of the dynamic expression of cellular proteins, it is essential to image reporter fusion proteins that are expressed at comparable levels to their endogenous expression. In this review, we introduce our recent reports about the dynamic control of bHLH transcription factors in multipotency and fate choice of NSCs, focusing on real-time imaging of fluorescent reporters fused with bHLH transcription factors. Our imaging results indicate that bHLH transcription factors are expressed in an oscillatory manner by NSCs, and that one of them becomes dominant during fate choice. We propose that the multipotent state of NSCs correlates with the oscillatory expression of several bHLH transcription factors, whereas the differentiated state correlates with the sustained expression of a single bHLH transcription factor

Scientific Opinion on the safety and efficacy of disodium 5?-ribonucleotides, disodium 5?-guanylate, disodium 5?-inosinate for all animal species and categories

The flavours included in this assessment are widely present in nature as the building blocks of DNA and RNA. In the absence of any information on the microbial strains or substrates used for the production of the additives, and with little information on the manufacturing process, the FEEDAP Panel is unable to ascertain whether the manufacturing process introduces any safety concerns. Disodium 5′-guanylate and disodium 5′-inosinate and their mixture are considered to be safe for the target animals and the consumer. However, considering the lack of information on the production process, these conclusions apply only to the compounds ‘per se’ and their extrapolation to any feed additive containing these compounds is not possible. In the absence of any data related to hazard to the user, it would be prudent to regard disodium 5′-guanylate and disodium 5′-inosinate and their mixture as potentially hazardous to workers by skin or inhalation exposure. The compounds under assessment are naturally present in feed materials; therefore, no risk to the safety for the environment is foreseen. Since these compounds are used in food as flavourings, and their function in feed is essentially the same as that in food, no further demonstration of efficacy is necessary

HPV-18 transformed cells fail to arrest in G1 in response to quercetin treatment

Previous work with primary human keratinocytes demonstrated that quercetin, a potent mutagen found in high levels in bracken fern (Pteridium aquilinum), arrested cells in G1 with concomitant elevation of the cyclin-dependent kinase inhibitor (cdki) p27Kip1. Expression of the human papillomavirus type 16 (HPV-16) E6 and E7 oncoproteins, under transcriptional control of a heterologous promoter, in transformed keratinocytes failed to abrogate this arrest [Beniston, R., Campo, M.S., 2003. Quercetin elevates p27(Kip1) and arrests both primary and HPV-16 E6/E7 transformed human keratinocytes in G1. Oncogene 22, 5504–5514]. Given the link between papillomavirus infection, bracken fern in the diet and cancer of the oesophagus in humans, we wished to investigate further whether cells transformed by the whole genome of HPV-16 or HPV-18, with E6 and E7 under the transcriptional control of their respective homologous promoters, would be similarly arrested in G1 by quercetin. In agreement with earlier work, quercetin arrested HPV-16 transformed cells in G1 with an increase in the cyclin-dependent kinase inhibitor p27Kip1. However, HPV-18 transformed cells did not arrest after quercetin treatment. The failure of HPV-18 transformed cells to arrest in G1 was linked to the up-regulation of the HPV-18 long control region (LCR) by quercetin, maintaining high expression of the viral transforming proteins. Transcriptional up-regulation of the HPV-18 LCR was mediated by a “quercetin responsive element” homologous to the one identified previously in the bovine papillomavirus type 4 (BPV-4) LCR

The Lipopolysaccharide Export Pathway in Escherichia coli: Structure, Organization and Regulated Assembly of the Lpt Machinery

The bacterial outer membrane (OM) is a peculiar biological structure with a unique composition that contributes significantly to the fitness of Gram-negative bacteria in hostile environments. OM components are all synthesized in the cytosol and must, then, be transported efficiently across three compartments to the cell surface. Lipopolysaccharide (LPS) is a unique glycolipid that paves the outer leaflet of the OM. Transport of this complex molecule poses several problems to the cells due to its amphipatic nature. In this review, the multiprotein machinery devoted to LPS transport to the OM is discussed together with the challenges associated with this process and the solutions that cells have evolved to address the problem of LPS biogenesis

EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Ai ds (CEF); Scientific Opinion on Flavouring Group Evaluation 208 (FGE.208): Consideration of genotoxicity data on representatives for 10 alicyclic aldehydes with the α , β - unsaturation in ring / side - chain and precursors from chemical subgroup 2.2 of FGE.19 b y EFSA

The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the European Food Safety Authority was requested to evaluate the genotoxic potential of one flavouring substance from subgroup 2.2 of FGE.19 in the Flavouring Group Evaluation 208. The Flavour Industry has provided additional genotoxicity studies for p-mentha-1,8-dien-7-al [FL-no: 05.117]. p-Mentha-1,8-dien-7-al will represent the other nine flavouring substances in FGE.208. Based on the presently available data the Panel concluded that some concern for the genotoxic potential of p-mentha-1,8-dien-7-al remains. In order to clarify the genotoxic potential of this substance, the Panel considered that further in vivo testing should be performed. To address this, an in vivo Comet assay, considering the first site of contact (e.g. stomach or duodenum) and liver, should be carried out according to the Scientific Report of EFSA on Minimum Criteria for the acceptance of in vivo alkaline Comet Assay Reports

Re‐evaluation of propane‐1,2‐diol alginate (E 405) as a food additive

The present opinion deals with the re‐evaluation of propane‐1,2‐diol alginate (E 405) when used as a food additive. The Panel noted that absorption, distribution, metabolism and excretion (ADME) data on propane‐1,2‐diol alginate gave evidence for the hydrolysis of this additive into propane‐1,2‐diol and alginic acid. These two compounds have been recently re‐evaluated for their safety of use as food additives (EFSA ANS Panel, 2017, 2018). Consequently, the Panel considered in this opinion the major toxicokinetic and toxicological data of these two hydrolytic derivatives. No adverse effects were reported in subacute and subchronic dietary studies with propane‐1,2‐diol alginate. The available data did not indicate a genotoxic concern for propane‐1,2‐diol alginate (E 405) when used as a food additive. Propane‐1,2‐diol alginate, alginic acid and propane‐1,2‐diol were not of concern with respect to carcinogenicity. The Panel considered that any adverse effect of propane‐1,2‐diol alginate would be due to propane‐1,2‐diol. Therefore, the acceptable daily intake (ADI) of the food additive E 405 is determined by the amount of free propane‐1,2‐diol and the propane‐1,2‐diol released from the food additive after hydrolysis. According to the EU specification, the concentration of free and bound propane‐1,2‐diol amounts to a maximum of 45% on a weight basis. On the worst‐case assumption that 100% of propane‐1,2‐diol would be systemically available and considering the ADI for propane‐1,2‐diol of 25 mg/kg body weight (bw) per day, the Panel allocated an ADI of 55 mg/kg bw per day for propane‐1,2‐diol alginate. The Panel concluded that exposure estimates did not exceed the ADI in any of the population groups from the use of propane‐1,2‐diol alginate (E 405) as a food additive. Therefore, the Panel concluded that there is no safety concern at the authorised use levels

Effectiveness of onomatopoeias on coping behaviors of Japanese preschool children undergoing medical procedures.

神奈川大