Biological UV dosimetry using the DLR-biofilm.

Changes of environmental UV radiation as part of global atmospheric changes will influence the biosphere substantially. The determination of the biological effects of these changes requires accurate and reliable UV monitoring systems that weight the spectral irradiance according to the biological responses under consideration. Biological UV dosimeters, which directly weight the incident UV components of sunlight in relation to the effectiveness of the different wavelengths and the potential interactions between them, can complement weighted physical UV measurements. Up to now several UV-dependent endpoints in biomolecules (e.g. uracil, DNA, provitamin D3), bacteriophages (e.g. T7), bacteria (e.g.E. coli, B. subtilis) and cultured eukaryotic cells have been suggested as sensing elements in biological UV dosimeters. One example is the DLR-biofilm consisting of immobilised spores of the bacterium B. subtilis as a UV sensor. It weights per se the incident UV radiation according to its DNA-damaging effectiveness. In several examples the applicability of the DLR-biofilm technique for personal UV dosimetry as well as for the measurement of the biologically weighted irradiance of the sun and of artificial UV sources is demonstrated.     

Visualizing the invisible: class excursions to ignite children’s enthusiasm for microbes

We have recently argued that, because microbes have pervasive – often vital – influences on our lives, and that therefore their roles must be taken into account in many of the decisions we face, society must become microbiology-literate, through the introduction of relevant microbiology topics in school curricula (Timmis et al. 2019. Environ Microbiol 21: 1513-1528). The current coronavirus pandemic is a stark example of why microbiology literacy is such a crucial enabler of informed policy decisions, particularly those involving preparedness of public-health systems for disease outbreaks and pandemics. However, a significant barrier to attaining widespread appreciation of microbial contributions to our well-being and that of the planet is the fact that microbes are seldom visible: most people are only peripherally aware of them, except when they fall ill with an infection. And it is disease, rather than all of the positive activities mediated by microbes, that colours public perception of ‘germs’ and endows them with their poor image. It is imperative to render microbes visible, to give them life and form for children (and adults), and to counter prevalent misconceptions, through exposure to imagination-capturing images of microbes and examples of their beneficial outputs, accompanied by a balanced narrative. This will engender automatic mental associations between everyday information inputs, as well as visual, olfactory and tactile experiences, on the one hand, and the responsible microbes/microbial communities, on the other hand. Such associations, in turn, will promote awareness of microbes and of the many positive and vital consequences of their actions, and facilitate and encourage incorporation of such consequences into relevant decision-making processes. While teaching microbiology topics in primary and secondary school is key to this objective, a strategic programme to expose children directly and personally to natural and managed microbial processes, and the results of their actions, through carefully planned class excursions to local venues, can be instrumental in bringing microbes to life for children and, collaterally, their families. In order to encourage the embedding of microbiology-centric class excursions in current curricula, we suggest and illustrate here some possibilities relating to the topics of food (a favourite pre-occupation of most children), agriculture (together with horticulture and aquaculture), health and medicine, the environment and biotechnology. And, although not all of the microbially relevant infrastructure will be within reach of schools, there is usually access to a market, local food store, wastewater treatment plant, farm, surface water body, etc., all of which can provide opportunities to explore microbiology in action. If children sometimes consider the present to be mundane, even boring, they are usually excited with both the past and the future so, where possible, visits to local museums (the past) and research institutions advancing knowledge frontiers (the future) are strongly recommended, as is a tapping into the natural enthusiasm of local researchers to leverage the educational value of excursions and virtual excursions. Children are also fascinated by the unknown, so, paradoxically, the invisibility of microbes makes them especially fascinating objects for visualization and exploration. In outlining some of the options for microbiology excursions, providing suggestions for discussion topics and considering their educational value, we strive to extend the vistas of current class excursions and to: (i) inspire teachers and school managers to incorporate more microbiology excursions into curricula; (ii) encourage microbiologists to support school excursions and generally get involved in bringing microbes to life for children; (iii) urge leaders of organizations (biopharma, food industries, universities, etc.) to give school outreach activities a more prominent place in their mission portfolios, and (iv) convey to policymakers the benefits of providing schools with funds, materials and flexibility for educational endeavours beyond the classroom.     

Ultraviolet Radiation and the Photobiology of Earth's Early Oceans

During the Archean era (3.9–2.5 Ga ago) the earth was dominatedby an oceanic lithosphere. Thus, understanding how life aroseand persisted in the Archean oceans constitutes a majorchallenge in understanding early life on earth. Using aradiative transfer model of the late Archean oceans, thephotobiological environment of the photic zone and the surfacemicrolayer is explored at the time before the formation of a significant ozonecolumn. DNA damage rates might have been approximately threeorders of magnitude higher in the surface layer of the Archeanoceans than on the present-day oceans, but at 30 m depth,damage may have been similar to the surface of the present-dayoceans. However at this depth the risk of being transported to surface waters in the mixed layer was high. The mixed layer mayhave been inhabited by a low diversity UV-resistant biota. Butit could have been numerically abundant. Repair capabilitiessimilar to Deinococcus radiodurans would be sufficient tosurvive in the mixed layer. Diversity may have beengreater in the region below the mixed layer and above the lightcompensation point corresponding to today's `deep chlorophyllmaximum'. During much of the Archean the air-water interface wasprobably an uninhabitable extreme environment for neuston. Thehabitability of some regions of the photic zone is consistentwith the evidence embodied in the geologic record, whichsuggests an oxygenated upper layer in the Archean oceans. Duringthe early Proterozoic, as ozone concentrations increased to acolumn abundance above 1 × 10¹⁷ cm^-2, UV stresswould have been reduced and possibly a greater diversity oforganisms could have inhabited the mixed layer. However,nutrient upwelling from newly emergent continental crusts mayhave been more significant in increasing total planktonic abundance inthe open oceans and coastal regions than photobiologicalfactors. The phohobiological environment of the Archean oceanshas implications for the potential cross-transfer of life betweenother water bodies of the early Solar System, possibly on earlyMars or the water bodies of a wet, early Venus.     

Slow clearance of Plasmodium vivax with chloroquine amongst children younger than six months of age in the Brazilian Amazon

Plasmodium vivax is the most widespread parasite causing malaria, being especially prevalent in the Americas and Southeast Asia. Children are one of the most affected populations, especially in highly endemic areas. However, there are few studies evaluating the therapeutic response of infants with vivax malaria. This study retrospectively evaluated the parasitaemia clearance in children diagnosed with vivax malaria during the first five days of exclusive treatment with chloroquine (CQ). Infants aged less than six months old had a significantly slower parasitaemia clearance time compared to the group of infants and children between six months and 12 years old (Kaplan-Meier survival analysis; Wilcoxon test; p = 0.004). The impaired clearance of parasitaemia in younger children with vivax malaria is shown for the first time in Latin America. It is speculated that CQ pharmacokinetics in young children with vivax malaria is distinct, but this specific population may also allow the detection of CQ-resistant parasites during follow-up, due to the lack of previous immunity.     

Preparative chromatography for obtaining pure samples of rosaniline,magenta II,and new fuchsine

A simple low pressure liquid chromatographic method is reported that can separate the basic fuchsine homologues, rosaniline, magenta II and new fuchsine from an impure commercial dye. The chromatographic purity of the separated dyes is > 90%. All homologues were obtained in multi-milligram amounts per chromatographic run; precise yields depend on the composition of the starting material and potentially may be greater. This is a useful preparative procedure for generating chromatographically pure samples of basic fuchsine homologues, especially those that cannot be obtained in pure form by direct synthesis.     

Description of <Emphasis Type="Italic">Tessaracoccus profundi</Emphasis> sp.nov., a deep-subsurface actinobacterium isolated from a Chesapeake impact crater drill core (940 m depth)

A novel actinobacterium, designated CB31^T, was isolated from a 940 m depth sample of a drilling core obtained from the Chesapeake meteor impact crater. The strain was isolated aerobically on R2A medium agar plates supplemented with NaCl (20 g l⁻¹) and MgCl₂·6H₂O (3 g l⁻¹). The colonies were circular, convex, smooth and orange. Cells were slightly curved, rod-shaped in young cultures and often appeared in pairs. In older cultures cells were coccoid. Cells stained Gram-positive, were non-motile and did not form endospores. The diagnostic diamino acid of the peptidoglycan was ll-diaminopimelic acid. The polar lipids included phosphatidylglycerol, diphosphatidglycerol, four different glycolipids, two further phospholipids and one unidentified lipid. The dominant menaquinone was MK-9(H₄) (70%). The major cellular fatty acid was anteiso C15:0 (83%). The DNA G + C content was 68 mol%. The strain grew anaerobically by reducing nitrate to nitrite or by fermenting glucose. It was catalase positive and oxidase negative. It grew between 10 and 45°C, with an optimum between 35 and 40°C. The pH range for growth was 5.7–9.3, with an optimum at pH 7.5. The closest phylogenetic neighbors based on 16S rRNA gene sequence identity were members of the genus Tessaracoccus (95–96% identity). On the basis of phenotypic and phylogenetic distinctiveness, strain CB31^T is considered to represent a novel species of the genus Tessaracoccus, for which we propose the name Tessaracoccus profundi sp. nov.. It is the first member of this genus that has been isolated from a deep subsurface environment. The type strain is CB31^T (=NCIMB 14440^T = DSM 21240^T).     

A meta-analysis of the activity,stability, and mutational characteristics of temperature-adapted enzymes

Understanding the characteristics that define temperature-adapted enzymes has been a major goal of extremophile enzymology in recent decades. In the present study, we explore these characteristics by comparing psychrophilic, mesophilic, and thermophilic enzymes. Through a meta-analysis of existing data, we show that psychrophilic enzymes exhibit a significantly larger gap (T_g) between their optimum and melting temperatures compared with mesophilic and thermophilic enzymes. These results suggest that T_g may be a useful indicator as to whether an enzyme is psychrophilic or not and that models of psychrophilic enzyme catalysis need to account for this gap. Additionally, by using predictive protein stability software, HoTMuSiC and PoPMuSiC, we show that the deleterious nature of amino acid substitutions to protein stability increases from psychrophiles to thermophiles. How this ultimately affects the mutational tolerance and evolutionary rate of temperature adapted organisms is currently unknown.     

Carbohydrate metabolism in erythrocytes of copper deficient rats

Dietary copper deficiency is known to adversely affect the circulatory system of fructose-fed rats. Part of the problem may lie in the effect of copper deficiency on intermediary metabolism. To test this, weanling male Long-Evans rats were fed for 4 or 8 weeks on sucrose-based diets containing low or adequate copper content. Copper deficient rats had significantly lower plasma and tissue copper as well as lower plasma copper, zinc-superoxide dismutase activity. Copper deficient rats also had a significantly higher heart:body weight ratio when compared to pair-fed controls. Direct measurement of glycolysis and pentose phosphate pathway flux in erythrocytes using (13)C NMR showed no differences in carbon flux from glucose or fructose to pyruvate but a significantly higher flux through the lactate dehydrogenase locus in copper deficient rats (approximately 1.3 times, average of glucose and glucose + fructose measurements). Copper-deficient animals had significantly higher erythrocyte concentrations of glucose, fructose, glyceraldehyde 3-phosphate and NAD(+). Liver metabolite levels were also affected by copper deficiency being elevated in glycogen and fructose 1-phosphate content. The results show small changes in carbohydrate metabolism of copper deficient rats.