Antimicrobial and antiviral activities of an actinomycete (Streptomyces sp.) isolated from a Brazilian tropical forest soil

A promising producer of bioactive compounds isolated from a Brazilian tropical soil was tested for its range of antimicrobial activities. Strain 606, classified as Streptomyces sp., could not be identified up to species level, suggesting a possible new taxon. The supernatant and 10 extracts and fractions, obtained by extraction and chromatographic techniques, presented antimicrobial activity using antibiograms. The methanolic fraction was highly active against pathogenic bacteria, phytopathogenic fungi and the human pathogenic yeast Candida albicans. It also possessed high antiviral activity inhibiting the propagation of an acyclovir-resistant herpes simplex virus type 1 strain on HEp-2 cells at non-cytotoxic concentration. The strong cytotoxic effect suggests an antitumour action. This revised version was published online in August 2006 with corrections to the Cover Date.     

The promoters of Arabidopsis thaliana genes AtCOX17-1 and -2, encoding a copper chaperone involved in cytochrome c oxidase biogenesis, are preferentially active in roots and anthers and induced by biotic and abiotic stress

AtCOX17 genes encode Arabidopsis thaliana homologs of the yeast metallochaperone Cox17p, involved in the delivery of copper for cytochrome c oxidase (COX) assembly. Two different AtCOX17 genes, located in chromosomes 1 and 3, are present in the Arabidopsis genome. Sequences available in data banks indicate that the presence of two genes is a common feature in monocots, but not in dicots, suggesting that Arabidopsis genes may be the result of a recent duplication. Sequences upstream from the translation start sites of AtCOX17 genes, which include an intron located in the 5' leader region, were introduced into plants in front of the gus gene. For both genes, expression was localized preferentially in young roots and anthers, but almost 10-fold higher β-glucuronidase activity levels were observed in plants transformed with AtCOX17-1 upstream regions. Both promoters were induced to different extents by wounding, treatment of leaves with the bacterial pathogen Pseudomonas syringae and incubation with agents that produce oxidative stress and metals. AtCOX17-2 showed similar responses to these factors, while AtCOX17-1 was more strongly induced by relatively low (10–100 μ M ) copper. The results indicate that both AtCOX17 genes have similar, though not identical, expression characteristics and suggest the existence in their promoters of elements involved in tissue-specific expression and in responses to factors that may produce mitochondrial or cell damage. It can be speculated that Arabidopsis COX17 accumulates under stress conditions to actively replace damaged or inactive cytochrome c oxidase to sustain cyanide-sensitive respiration in plant cells.     

Resolving Power: A Quantitative Measure of Electrophoretic Resolution

Resolving power is a quantitative measure of the ability of an electrophoretic system to separate DNA (and other) molecules of similar size. It is a dimensionless quantity, and hence facilitates comparison of the performance of electrophoretic systems that operate very differently. Resolving power can be determined as a function of molecular length from experimental data consisting of a series of completely resolved bands on a gel or blot; closely spaced bands are not required. We discuss factors such as the mass of DNA in a particular band and the spatial resolution of the system used to image the distribution of DNA on a gel or blot that, while not an intrinsic part of the electrophoretic system, may influence the observed resolving power. We derive an empirical global dispersion function that applies both to images of gels obtained after a fixed time of electrophoresis of all the samples and to images obtained as each species reaches a detector located at a fixed distance from the starting well. We use this dispersion function to show that the improvement in resolving power produced by extending the time or distance of electrophoresis in a static, uniform electric field asymptotically approaches a limiting value that is a function of the length of the DNA. When plotted as a function of molecular length, this limiting value defines an envelope that characterizes the intrinsic limits of performance of a particular electrophoretic system (e.g., electric field strength, gel type and concentration, buffer, temperature). Comparing the resolving power of static field agarose gel electrophoresis as routinely practiced for separating DNA molecules from 10³ to 10⁵ bp long with other electrophoretic schemes suggests that significant improvements should be achievable.     

COVID-19 plasma proteome reveals novel temporal and cell-specific signatures for disease severity and high-precision disease management

Coronavirus disease 2019 (COVID-19) is a systemic inflammatory condition with high mortality that may benefit from personalized medicine and high-precision approaches. COVID-19 patient plasma was analysed with targeted proteomics of 1161 proteins. Patients were monitored from Days 1 to 10 of their intensive care unit (ICU) stay. Age- and gender-matched COVID-19-negative sepsis ICU patients and healthy subjects were examined as controls. Proteomic data were resolved using both cell-specific annotation and deep-analysis for functional enrichment. COVID-19 caused extensive remodelling of the plasma microenvironment associated with a relative immunosuppressive milieu between ICU Days 3–7, and characterized by extensive organ damage. COVID-19 resulted in (1) reduced antigen presentation and B/T-cell function, (2) increased repurposed neutrophils and M1-type macrophages, (3) relatively immature or disrupted endothelia and fibroblasts with a defined secretome, and (4) reactive myeloid lines. Extracellular matrix changes identified in COVID-19 plasma could represent impaired immune cell homing and programmed cell death. The major functional modules disrupted in COVID-19 were exaggerated in patients with fatal outcome. Taken together, these findings provide systems-level insight into the mechanisms of COVID-19 inflammation and identify potential prognostic biomarkers. Therapeutic strategies could be tailored to the immune response of severely ill patients.     

Catecholamine and MHPG plasma levels,platelet MAO activity,and3H-imipramine binding in heroin and cocaine addicts

This work evaluated in a population of heroin and heroin plus cocaine human addicts:

1. Norepinephrine (NE), epinephrine (Epi), and 3-methoxy-4-hydroxyphenylglycol (MHPG) (the principal metabolite of brain NE) plasma levels;
2. Monoamine oxidase (MAO) activity; and
3. ³H-imipramine specific binding to the amine carrier in platelets.

NE plasma levels were significantly lower in the short-term heroin user groups (1–3 and 4–6 yr), a finding not observed in both the long-term heroin user (>6 yr) and heroin plus cocaine user (>6 yr) groups. Epi levels changed in a similar manner, except that a significant increase was noted in heroin plus cocaine abusers. Conversely, dopamine and MHPG plasma levels increased with the duration of heroin use, and even more with cocaine abuse. Platelet MAO activity increased in all groups. Specific³H-imipramine binding sites showed an increase after 3 yr of heroin abuse and in all heroin plus cocaine addicts. In conclusion, short-term use of heroin decreases NE or Epi release, but with prolonged use, a slow adpatation occurs. In contrast, cocaine inhibits the neuronal Epi uptake, even in a situation of long duration of abuse. Probably the amine levels additionally regulate the amine carrier, resulting in changes that show a different pattern from major depression. These drugs of abuse may also influence directly or indirectly related enzymatic systems.     

Amblyomma americanum: characterization of salivary prostaglandins E2 and F2 alpha by RP-HPLC/bioassay and gas chromatography-mass spectrometry.

Secretagogue-induced saliva of the tick, Amblyomma americanum (L.) was fractionated by reversed-phase-high-performance liquid chromatography (RP-HPLC) and bioassayed in smooth muscle preparations. Material with retention times of authentic prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha) were found to cause contraction of preparations of rat colon and rat stomach strips. Gas chromatography-mass spectra of selected ions of both HPLC-purified fractions confirmed the existence of PGE2 and PGF2 alpha. Bioassay of individual samples obtained from ticks stimulated to salivate with pilocarpine, dopamine + theophiline, or dopamine + theophiline + GABA indicated that all these secretagogues induced similar amounts of prostaglandin secretion, averaging 469 ng PGE2/ml. These pharmacological doses of prostaglandin are hypothesized to assist in tick feeding by inducing vasodilation and/or other pharmacological events in their hosts.     

Genome size distributions in bacteria and archaea are strongly linked to evolutionary history at broad phylogenetic scales

The evolutionary forces that determine genome size in bacteria and archaea have been the subject of intense debate over the last few decades. Although the preferential loss of genes observed in prokaryotes is explained through the deletional bias, factors promoting and preventing the fixation of such gene losses often remain unclear. Importantly, statistical analyses on this topic typically do not consider the potential bias introduced by the shared ancestry of many lineages, which is critical when using species as data points because of the potential dependence on residuals. In this study, we investigated the genome size distributions across a broad diversity of bacteria and archaea to evaluate if this trait is phylogenetically conserved at broad phylogenetic scales. After model fit, Pagel’s lambda indicated a strong phylogenetic signal in genome size data, suggesting that the diversification of this trait is influenced by shared evolutionary histories. We used a phylogenetic generalized least-squares analysis (PGLS) to test whether phylogeny influences the predictability of genome size from dN/dS ratios and 16S copy number, two variables that have been previously linked to genome size. These results confirm that failure to account for evolutionary history can lead to biased interpretations of genome size predictors. Overall, our results indicate that although bacteria and archaea can rapidly gain and lose genetic material through gene transfers and deletions, respectively, phylogenetic signal for genome size distributions can still be recovered at broad phylogenetic scales that should be taken into account when inferring the drivers of genome size evolution.     

A New Species of Thraulodes (Ephemeroptera: Leptophlebiidae) from Mexico

A new species of Thraulodes from Mexico is described from male and female imagines. The male imagines of this species have very characteristic genitalia that allow its easy separation from the other known species of the genus.