Encyclopedia
Transmission electron microscopy (TEM) micrograph of carbon nanoscrolls[1] prepared by a mechanical technique, using graphite nanoplatelets as precursor.
04 Dec 2023
Chroococcus turgidus High resolution photo of Chroococcus turgidus using Planapo 63/1.4. Sample from sphagnum pond situated in the northern alpine region of Austria near Salzburg. Images were taken using Zeiss Universal with Olympus C7070 CCD camera.
Wolfgang Bettighofer, protisten.de
01 Aug 2024
Transmission electron microscopy (TEM) micrograph of graphite oxide (GO) prepared by applying the Hummers' method to graphite nanoplatelets (GNP).
04 Dec 2023
Nanomaterials are frequently characterized by an astonishing morphology that, owing to their very small size, requires an electron microscopy technique (SEM or TEM) to be visualized. Such phenomenon can be ascribed to the high uniformity of the nanomaterials morphology. For example, in this SEM-micrograph, all cristobalite crystals are shaped as equilateral triangles, which is a geometry characterized by several symmetry elements (4 planes and 4 axes). In addition, the crystals have approximately the same size (i.e., a monodispersed particle size distribution) and are oriented in the same direction (iso-orientation). Such very high uniformity of both morphology and topology of this nanostructured system could be the reason of the nice aspect. In general, beauty means capability to show a harmonious appearance, which tends towards the perfection, because harmony and perfection of the aspect lead to the aesthetic pleasure. A harmonious microstructure may correspond to a dimensionally uniform and geometrically regular shape, to a highly symmetrical or well proportioned shape, etc. In general, a microstructure can be considered as harmonious/perfect and therefore beautiful when a law, rule or criterion can be used for describing it. It is similar to the case of a musical melody, which is pleasant only if it is well paced, otherwise it is noise.
08 Jan 2024
Transmission electron microscopy (TEM) micrograph of thiol-derivatized gold nanoparticles.
04 Dec 2023
Laboratory mice play a pivotal role in advancing biomedical research by serving as invaluable models for studying human physiology, diseases, and potential treatments. Their genetic similarity to humans and the ease with which their genes can be modified make them indispensable. Researchers use mice to replicate human diseases, from cancer to Alzheimer's, enabling investigations into disease mechanisms and the development of therapeutic interventions. Additionally, mice are crucial for drug testing, helping identify promising candidates while reducing risks in clinical trials. Their contributions extend to genetics, immunology, neuroscience, toxicology, and reproductive biology, underpinning countless scientific discoveries that improve human health and medical treatments.
14 Sep 2023
Levels of regulation of the biosynthesis of secondary metabolites (SMs) in fungi [1]. (a) A particular gene from a biosynthetic gene cluster (BGC) is “silent” under normal physiological conditions, in the absence of a stimulating effect from the regulatory system. The absence of their transcription is associated both with the absence of the necessary transcription factors and with the functional state of these loci, which are in the form of heterochromatin. (b) The activation of a gene from the BGC as a result of coordinated regulation at the levels of (i) pathway-specific, (ii) cross-cluster, (iii) global cell, and (iv) global secondary metabolism (at the epigenetic level), (v) mediated by regulatory molecules. The antibiotic penicillin G is given as an example of a SM synthesized due to BGC activation. Pathway-specific regulators: ApdR—Zn(II)2Cys6 regulator for aspyridone A and B BGC (PKS/NRPS hybrid); FsqA—Zn(II)2Cys6 regulator for fumisoquin BGC (NRPS); FmpR—Zn(II)2Cys6 regulator for fumipyrrole BGC (NRPS); CicD—regulator with Myb-like DNA-binding domain for cichorine BGC (PKS); AntN—Zn(II)2Cys6 regulator for aspercryptin BGC (NRPS); XanC—bZIP transcription factor for xanthocillin BGC (isocyanide synthase); GliZ—Zn(II)2Cys6 regulator for gliotoxin BGC (NRPS); LaeA—Zn(II)2Cys6 regulator for lovastatin BGC (PKS). Cross-cluster regulators: PbcR—Zn(II)2Cys6 regulator for ent-pimara-8(14),15-diene BGC (terpenoid), which also downregulates penicillin cluster, two putative PKS clusters, and one putative NRPS cluster and upregulates one siderophore BGC; PexanC—bZIP transcription factor for upregulation of xanthocillin BGC, which also upregulates citrinin BGC; ScpR—transcription factor with C2H2-type zinc finger for upregulation of fellutamide B BGC (NRPS), which also upregulates asperfuranone BGC (PKS); RglT—Zn(II)2Cys6 transcription factor, whose gene is localized outside the gliotoxin BGC (NRPS), for which it is a positive regulator; CefR transcription factor with nuclear targeting signal that downregulates some genes from “early” beta-lactams BGC (NRPS) and upregulates some genes from “late” beta-lactams BGC. Global regulators: CreA (Cre1)—C2H2-type zinc finger transcription factor for glucose catabolite regulation; PacC—C2H2-type transcription factor with three zinc fingers for pH regulation; Nre (or AreA)—GATA transcription factor with single Cys4 zinc finger for nitrogen regulation; Ada1—C2H2-type transcription factor for control of asexual development; Yap1—bZIP-containing transcription factor for antioxidant response; HapB, HapC, and HapE—transcription factors from CCAAT-binding complex for regulation of redox status and iron starvation; CPCR1—RFX transcription factor for morphological development; AcFKH1—forkhead transcription factor for regulation of morphogenesis. Epigenetic regulators (including global regulators of secondary metabolism). Velvet complex: LaeA—S-adenosylmethionine-dependent histone methylase for chromatin remodeling; VelA (VeA), VelB, VelC, and VosA—components of so-called velvet complex with velvet domain for interacting with each other and with LaeA in the fungal nucleus. COMPASS complex—complex associated with Set1: Set1—histone-lysine N-methyltransferase (H3 lysine-4-specific). Mediators: sRNA—small non-coding RNA; PA—polyamine; SM—secondary metabolite.
19 Jul 2023
This model illustrates how defatted flaxseed leverages vitamin B6 antagonism to synergize glycolysis with one-carbon metabolism. The implication is that defatted flaxseed (or specifically, 1-amino D-proline) functions as a homologue for metformin, at least in avian species. This "one-carbon metabolism / glycolysis" synergy should attenuate type 2 diabetic complications and decelerate physiological aging [1].
28 Aug 2023
Here is the electron microscopic view of a red blood cell in stool with fecal bacteria. The image highlights the detailed surface texture of the red blood cell, surrounded by various fecal bacteria of different shapes and sizes.
05 Jul 2024
This image shows the position of an Infrared Gas Analyzer and Sonic Anemometer (IRGASON) at 137 ft. above the ground that measures carbon and water flux across the forest-atmosphere boundary layer at high temporal resolution of 10 Hz. This can help us better understand and manage carbon and water cycles in this system for informed management.
08 Mar 2024
Reovirus replication is initiated with the attachment of the virus particles to the cell surface via the sigma1-receptor interaction, followed by cell entry via beta-1 integrin mediated endocytosis. Reovirus capsid disassembly takes place in the acidified late endosomes by the proteolytic activities of cathepsins. The formed reovirus intermediate subviral particles (ISVPs) penetrate the endosomal membranes by the aid of Mu1 membrane fusion protein. In the cytoplasm, transcriptionally active core particles initiate viral transcription. The synthesized viral mRNAs are released from the core particles and translated into the viral proteins. Reovirus core assembly and minus strand synthesis takes place in the viral inclusions (viral factories) which are composed of viral proteins and RNAs, complete and nascent core particles, and certain elements of the cell cytoskeleton. In the newly formed core particles a secondary transcription may take place which amplifies the synthesis of viral mRNAs and proteins. Reovirus virions are formed with the outer capsid assembly and released from the infected cell. Reovirus ISVPs can also be generated from virions by extracellular proteolysis and then enter cells through direct penetration of cell membrane [1].
Wikimedia Commons, Ergin Sahin; Michael E. Egger; Kelly M. McMasters; Heshan Sam Zhou
01 Feb 2024
A picture of a herpes simplex on the knee.
Wikimedia Commons, Arenavittorio
28 Jun 2024
Several 2D materials have been discovered, the most important are the following substances: graphene, transition metal dichalcogenide (TMDs), layered double hydroxides (LDHs), hexagonal boron nitride (h-BN) and transition metal oxide (TMOs). Such compounds are made of ultra-thin sheet-like structures. Molybdenum disulphide (MoS2) is a layered-structure inorganic material from the TMDs series, it is the most widely-used 2D materials due to its low cost, robustness, high abundance, mechanical flexibility, photoluminescence, optical absorption, layer-dependent band gap transition, spin polarization, and many other useful physical properties. Owing to these properties, MoS2 finds numerous applications in various fields including electrode fabrication, energy storage, sensors, electronic and optoelectronic devices, supercapacitors, Li-ion batteries, memory devices, FETs, photodetectors, photovoltaics, solar cells, catalytic application, etc.
09 Jan 2024
Biosynthesis of secondary metabolites (SMs) in response to signal exposure. The arrival of a specific signal (from the external environment or the internal signal of the cell) leads to the production of corresponding SMs [1]. As an example, changes in the production of SMs in Penicillium chrysogenum are given: (a) Under normal physiological conditions (in the absence of specific environmental signals) and at an early stage of fungal cell development (trophophase stage), most SMs are not produced. (b) In response to a specific signal, the corresponding SM is synthesized. The green color shows known SMs of P. chrysogenum, which, in principle, can be synthesized by the cell (representing its biosynthetic capacity), but are not produced at a particular moment. The red color shows the currently produced SMs in response to the signal; the antibiotic penicillin G, synthesized in response to an external signal, is given as an example.
18 Jul 2023
Early ovarian clear cell carcinoma. Clear cell carcinoma of the right ovary, most probably originating from endometriosis. The macroscopic picture in the very early stage may be difficult to distinguish from a benign endometrioma or another benign ovarian tumor. The preoperative assessment including transvaginal sonography and tumor marker CA-125 is important in the risk assessment (e.g. according to the IOTA criteria) and crucial for the correct surgical therapy of the patient. Arrows: various peritoneal endometriotic lesions and old blood deposits.
07 Oct 2023
Escherichia coli grows on many commonly used cultivation media. Examples of these media are: Fig. A1 Brain heart infusion agar (BHIA), A2 Trypticase soy agar (TSA), A3 MacConkey agar (MCA), A4 Endo agar Fig. B shows growth of a common E. coli strain on these media. Note the different size of colonies as nutriet and selective properties of these media vary. Colonies on brain heart infusion agar (B1) are larger in comparison with colonies on trypticase soy agar (B2), MacConkey (B3) and Endo agar (B4). MacConkey (Fig. C1, C4) and Endo agar (Fig. C2, C3) represent diagnostic selective media. Both of them typically inhibit growth of Gram positive bacteria and enable differentiation between lactose positive and lactose negative bacteria (E. coli is typically lactose positive).Colonies are smallest on Endo agar as this medium has higher selectivity for Enterobacteriaceae in comparison with MacConkey agar. Size of colonies is also influenced by numbers of colonies growing on a defined surface of agar medium (higher numbers usually mean smaller colonies). (Competition for nutrients) Fig. C E. coli growing on MacConkey (C1) and Endo agar (C2) in comparison with Klebsiella pneumoniae (C3 MacConkey, C4 Endo). Both of them are lactose positive. Fig. D, G, H Colonies of lactose-negative and positive E. coli on MacConkey agar. E. coli strains are typically lactose positive. Colonies apperaing lactose-negative are usually delayed lactose fermentors giving positive ONPG test. Fig. E Staphylococcus aureus (yellow), Enterococcus faecalis (small) and E. coli on trypticase soy agar after 24 h at 37°C. Seen with reflected light. Fig. F E. coli and Pseudomonas aeruginosa (smaller greenish colonies) in mixed culture on brain heart infusion agar. 24 h, 37°C, seen with both reflected and transmitted light. Fig. I E. coli and Klebsiella pneumoniae (larger), yellow, lactose-positive colonies on CLED agar. Bluish lactose-negative colonies of Serratia marcescens. Fig. J Lactose-fermenting colonies of E.coli with a gold metallic sheen on Endo agar.
HansN, Wikimedia Commons
12 Aug 2024
Chinese osmanthus tree, also known as "Osmanthus osmanthus" because of its yellow color.
31 Aug 2023
0.1 ml of the sample was combined with 1 ml of reagent solution (0.6 M sulfuric acid, 28 mM sodium phosphate and 4 mM ammonium molybdate). The tubes were capped and incubated at 95 °C for 90 min. After cooling to room temperature for 15 min, the absorbance of the solutions was measured at 695 nm against a blank.
03 Sep 2023
E-polymers, also known as conducting polymers, are a class of materials that exhibit both electrical conductivity and the mechanical properties of polymers [1]. The use of e-polymer materials in daily life is becoming increasingly widespread, especially in the field of biology [2][3]. Since the manufacturing cost of e-polymer implants is relatively low and e-polymers also react, causing different chemical molecules to attach to the surface of the implant, they are more compatible with the surrounding environment of the body [4][5]. Some e-polymers are biodegradable in the body. If used for temporary implants, the advantage of these polymers is that they can gradually degrade in the body after performing their functions [6][7][8], thereby reducing the possibility of any long-term complications [9]. Polymers and their composite materials can be designed to have inherent tensile properties while maintaining their high performance, making them favorable candidates for the next generation of skin-inspired electronic materials [10][11]. In addition, combining self-healing polymers and biodegradable materials can improve the durability and biocompatibility of electronic skin [12][13].
24 Jan 2024
Schematic drawing of a virion of the genus Coltivirus, cross section and side view.
ViralZone, SIB Swiss Institute of Bioinformatics, Wikimedia Commons
08 Mar 2024
