Short communication: Effect of water activity on cell growth and phenol oxidase production by Streptomyces cyaneus var. viridochromogenes in surface culture

In surface cultures of Streptomyces cyaneus var. viridochromogenes, NaCl depressed water activity (a _w) without supporting growth. Reducing a _w from 0.987 to 0.951 led to 3- and 4-fold increases in intracellular and extracellular phenol oxidase activities, respectively.     

Elicitation with methyl-jasmonate stimulates peruvoside production in cell suspension cultures of <Emphasis Type="Italic">Thevetia peruviana</Emphasis>

Thevetia peruviana is a small tree that produces several compounds with pharmaceutical application, among which peruvoside could be highlighted. However, these compounds are produced in low concentration in the plant, making it important to develop strategies such as plant cell culture and elicitation to obtain higher quantities of the desired product. In this work, cell suspension cultures of T. peruviana were established in four different culture media: Murashige–Skoog (MS), half Murashige–Skoog (half MS), Schenk–Hildebrandt (SH), and Gamborg (B5) to study their effect on cell growth. Cell growth kinetics were studied in SH medium, and the extracellular peruvoside production during the culture time was determined. The best culture medium for the establishment of cell suspension cultures was MS with a growth index of 3.17 ± 0.2 g g⁻¹ inoculum. The cell growth kinetics showed the four characteristic growth phases of a cell culture (lag, exponential, stationary, and death), and during none of these phases was it possible to observe peruvoside production. The elicitor effect of methyl-jasmonate (MeJ) was studied in cell suspension cultures established in SH medium. The effect of MeJ concentration and the time in which it should be applied were determined. The best results were obtained at a concentration of 100 mg l⁻¹ of MeJ applied at the beginning of the culture, which induced a peruvoside production of 8.93 mg l⁻¹ medium. The current results are the first report of an in vitro peruvoside production system.     

Structural and functional interaction of (±)-2-(N-tert-butylamino)-3′-iodo-4′-azidopropiophenone,a photoreactive bupropion derivative,with nicotinic acetylcholine receptors

The pharmacological properties of (±)-2-(N-tert-butylamino)-3′-iodo-4′-azidopropiophenone [(±)-SADU-3-72], a photoreactive analog of bupropion (BP), were characterized at different muscle nicotinic acetylcholine receptors (AChRs) by functional and structural approaches. Ca²⁺ influx results indicate that (±)-SADU-3-72 is 17- and 6-fold more potent than BP in inhibiting human (h) embryonic (hα1β1γδ) and adult (hα1β1εδ) muscle AChRs, respectively. (±)-SADU-3-72 binds with high affinity to the [³H]TCP site within the resting or desensitized Torpedo AChR ion channel, whereas BP has higher affinity for desensitized AChRs. Molecular docking results indicate that both SADU-3-72 enantiomers interact with the valine (position 13′) and serine (position 6′) rings. However, an additional domain, between the outer (position 20′) and valine rings, is observed in Torpedo AChR ion channels. Our results indicate that the azido group of (±)-SADU-3-72 may enhance its interaction with polar groups and the formation of hydrogen bonds at AChRs, thus supporting the observed higher potency and affinity of (±)-SADU-3-72 compared to BP. Collectively our results are consistent with a model where BP/SADU-3-72 and TCP bind to overlapping sites within the lumen of muscle AChR ion channels. Based on these results, we believe that (±)-SADU-3-72 is a promising photoprobe for mapping the BP binding site, especially within the resting AChR ion channel.     

Copper-mediated DNA photocleavage by a tetrapyridoacridine (tpac) ligand

We have focused our interest on the tetrapyridoacridine ligand tetrapyrido[3,2-a:2',3'-c:3',2'-h: 2',3'-j]acridine (tpac), as a model system for the preparation of novel copper-based artificial nucleases. The complex of copper(II)-tpac cleaves supercoiled pUC18 plasmid DNA in an oxidative manner by photoactivation with visible light, exhibiting maximum cleaving efficiency at 1:2 metal-ligand stoichiometric ratio. We propose an interaction of the copper-tpac complex with DNA through both major and minor grooves and a photocleavage mechanism via the formation of hydroxyl radicals and singlet oxygen or singlet oxygen-like species.     

Genetic ancestry of participants in the National Children’s Study

Background

The National Children’s Study (NCS) is a prospective epidemiological study in the USA tasked with identifying a nationally representative sample of 100,000 children, and following them from their gestation until they are 21 years of age. The objective of the study is to measure environmental and genetic influences on growth, development, and health. Determination of the ancestry of these NCS participants is important for assessing the diversity of study participants and for examining the effect of ancestry on various health outcomes.

Results

We estimated the genetic ancestry of a convenience sample of 641 parents enrolled at the 7 original NCS Vanguard sites, by analyzing 30,000 markers on exome arrays, using the 1000 Genomes Project superpopulations as reference populations, and compared this with the measures of self-reported ethnicity and race. For 99% of the individuals, self-reported ethnicity and race agreed with the predicted superpopulation. NCS individuals self-reporting as Asian had genetic ancestry of either South Asian or East Asian groups, while those reporting as either Hispanic White or Hispanic Other had similar genetic ancestry. Of the 33 individuals who self-reported as Multiracial or Non-Hispanic Other, 33% matched the South Asian or East Asian groups, while these groups represented only 4.4% of the other reported categories.

Conclusions

Our data suggest that self-reported ethnicity and race have some limitations in accurately capturing Hispanic and South Asian populations. Overall, however, our data indicate that despite the complexity of the US population, individuals know their ancestral origins, and that self-reported ethnicity and race is a reliable indicator of genetic ancestry.