Molecular Dynamics Simulations of Ibuprofen Binding to Aβ Peptides

Using replica exchange molecular dynamics simulations and the implicit solvent model we probed binding of ibuprofen to Aβ_10-40 monomers and amyloid fibrils. We found that the concave (CV) fibril edge has significantly higher binding affinity for ibuprofen than the convex edge. Furthermore, binding of ibuprofen to Aβ monomers, as compared to fibrils, results in a smaller free energy gain. The difference in binding free energies is likely to be related to the presence of the groove on the CV fibril edge, in which ibuprofen tends to accumulate. The confinement effect of the groove promotes the formation of large low-energy ibuprofen clusters, which rarely occur on the surface of Aβ monomers. These observations led us to suggest that the ibuprofen binding mechanism for Aβ fibrils is different from that for monomers. In general, ibuprofen shows a preference to bind to those regions of Aβ monomers (amino terminal) and fibrils (the CV edge) that are also the primary aggregation interfaces. Based on our findings and on available experimental data, we propose a rationale for the ibuprofen antiaggregation effect.     

Unique multiple sex chromosomes of the tree mouse Vandeleuria o. oleracea: identification of X1 and X2.

The tree mouse Vandeleuria o. oleracea has an odd diploid chromosome complement (2n = 29 female/male) accompanied by a unique multiple sex-chromosome mechanism (X1X2Ymale/X1X1X2female). In the present paper the sex chromosomes have been identified unequivocally with the help of G-banding and DNA replication patterns which confirm our earlier suggestion that the X1 is smaller in size than the simple mammalian X, and also that the combined sizes of the X1 and X2 (3-8 and 1-7 per cent respectively) approximate to the size of the conservative mammalian X (5 per cent). It is proposed that the mammalian X has attained a minimum functional size so that further reduction is not tolerated.     

Mortality among Canadian military personnel exposed to low-dose radiation.

We carried out a cohort study of mortality among 954 Canadian military personnel exposed to low-dose ionizing radiation during nuclear reactor clean-up operations at Chalk River Nuclear Laboratories, Chalk River, Ont., and during observation of atomic test blasts in the United States and Australia in the 1950s. Two controls matched for age, service, rank and trade were selected for each exposed subject. Mortality among the exposed and control groups was ascertained by means of record linkage with the Canadian Mortality Data Base. Survival analysis with life-table techniques did not reveal any difference in overall mortality between the exposed and control groups. Analysis of cause-specific mortality showed similar mortality patterns in the two groups; there was no elevation in the exposed group in the frequency of death from leukemia or thyroid cancer, the causes of death most often associated with radiation exposure. Analysis of survival by recorded gamma radiation dose also did not show any effect of radiation dose on mortality. The findings are in agreement with the current scientific literature on the risk of death from exposure to low-dose radiation.     

Strength is in engagement: The rise of an online scientific community during the COVID‐19 pandemic

Many scientists, confined to home office by COVID‐19, have been gathering in online communities, which could become viable alternatives to physical meetings and conferences. Subject Categories: S&S: Careers & Training, Methods & Resources, S&S: Ethics

As COVID‐19 has brought work and travel to a grinding halt, scientists explored new ways to connect with each other. For the gene regulation community, this started with a Tweet that quickly expanded into the “Fragile Nucleosome” online forum, a popular seminar series, and many intimate discussions connecting scientists all over the world. More than 2,500 people from over 45 countries have attended our seminars so far and our forum currently has ~ 1,000 members who have kick‐started discussion groups and mentorship opportunities. Here we discuss our experience with setting up the Fragile Nucleosome seminars and online discussion forum, and present the tools to enable others to do the same.Too often, we forget the importance of social interactions in science. Indeed, many creative ideas originated from impromptu and fortuitous encounters with peers, in passing, over lunch, or during a conference coffee break. Now, the ongoing COVID‐19 crisis means prolonged isolation, odd working hours, and less social interactions for most scientists confined to home. This motivated us to create the “Fragile Nucleosome” virtual community for our colleagues in the chromatin and gene regulation field.

… the ongoing COVID‐19 crisis means prolonged isolation, odd working hours and less social interactions for most scientists confined to home.

While the need to address the void created by the COVID‐19 pandemic triggered our actions, a large part of the international community already has had limited access to research networks in our field. Our initiative offered new opportunities though, in particular for those who have not benefited from extensive networks, showing how virtual communities can address disparities in accessibility. This should not be a stop‐gap measure during the pandemic: Once we come out from our isolation, we still need to address the drawbacks of in‐person scientific conferences/seminars, such as economic disparities, travel inaccessibility, and overlapping family responsibilities (Sarabipour, 2020). Our virtual community offers some solutions to the standing challenges (Levine & Rathmell, 2020), and we hope our commentary can help start conversations about the advantages of virtual communities in a post‐pandemic world.

… once we come out from our isolation we still need to address the drawbacks of in‐person scientific conferences/seminars, such as economic disparities, travel inaccessibility and overlapping family responsibilities…

     

Changes in Proline Content Accompanying the Uptake of Zinc and Copper by Lemna minor

Lemna minor L. grown in Hoagland solution containing zinc (10ppm) or copper (5 ppm) for 4 d accumulated high levels of thesemetals. Zinc and Cu accumulation in the test plants was accompaniedby a specific pattern of change in proline content. The lattershowed a steep rise during early stages (peak at 12-24 h) followedby a gradual decline until 96 h of treatment. In a dose-responsestudy, lower metal concentrations induced a sharp rise in prolinelevel with a maximum value at 5 ppm, which declined when theconcentration was further enhanced. There was a correspondencebetween the level of proline and total free amino acids in metaltreated plants. The possibility of proline involvement in tolerancemechanisms to heavy metals has been discussed.Copyright 1993,1999 Academic Press Heavy metals, zinc, copper, proline, total free amino acids, Lemna minor     

Effect of morphine on <Emphasis Type="Italic">Mycobacterium smegmatis</Emphasis> infection in mice and macrophages

The immunomodulatory effects of opioids are known in various infections. However, little is known about the effects of opioids in tuberculosis (TB). In the present study, we report the effects of morphine in Mycobacterium smegmatis infection in mice and macrophages. Morphine exerted a dose-dependent suppression of infection in vivo: 50 and 100 mg/kg morphine exerted significant (P<0.05) suppression whereas 5 mg/kg morphine showed no effect. Analogous to the in vivo effects, incubation of M. smegmatis-infected mouse peritoneal macrophages with morphine (100 μM) showed significant reduction in intramacrophage CFU counts. However, morphine did not show any direct antimycobacterial activity in broth dilution assay upto 100 μM concentration. Further, morphine-induced intramacrophage killing of M. smegmatis was abrogated by naloxone and aminoguanidine indicating the involvement of opioid-receptor activation and nitric oxide production in protective effects of morphine. In conclusion, morphine suppressed the progression of experimental TB in both mice and macrophage models.