Stem cells build tissue structures in the human body

The intestinal flora and humans have a mutualistic relationship. The human body contains about 100 trillion microbes in the intestinal tract, a number 10 times greater than the total number of human cells in the body.

Beautiful life form from another planet. A species that resembles a microscopic octopus interacting with other smaller microorganisms

Life form from another planet. A fungus-like species, that also resembles a snail. A bit slimy but beautiful

Life form from another planet. A species that resembles a microscopic octopus interacting with fungus like structures

Sectional view of a human embryo in the advanced blastocyst stage. The outer layer (green), the trophoblast, the trophoblasts are almost indistinguishable. The inner mass of o cells is called embryoblast. Some cells are dividing in the foreground. The blastocyst is close to the endometrium (bottom right).

Illustration of a microscopic fungus fruiting body in the style of a macrophotograph

Illustration of a fungus fruiting body growing on a plant, in the style of a macrophotograph

Cluster of yellow forest mushrooms on a mossy forest ground

Stem cells are undifferentiated cells that can specialized through mitosis to many other cell types of multicellular organisms.

C. auris causes candidiasis, an infection of the bloodstream, the central nervous system and internal organs. It has acquired multiple drug resistance.

Illustration of a fungus fruiting bodies growing on a rotten plant, in the style of a macrophotograph

Cluster of red forest mushrooms growing on the wood soil

T cells are born from hematopoietic stem cells in the bone marrow. Maturing T cells then migrate to the thymus gland to develop

Mucor species are commonly found in soil, digestive systems, plant surfaces and some cheeses like Tomme de Savoie, and also in rotten vegetable matter

Cluster of yellow forest mushrooms on a tree trunk

Cluster of yellow forest mushrooms on a mossy tree trunk

Cluster of white forest mushrooms on a tree trunk

White mushrooms growing on the forest soil

Heparin is a medication and a naturally ocurring glycosaminoglycan that binds to and activates antithrombin and has an anticoagulant effect. Source: PDB entry 3irl

Heparin (yellow) binds to and activates antithrombin. Antithrombin inhibits thrombin (dark blue). The anticoagulant properties of heparin are mediated by its interaction with antithrombin. Source: PDB entry 1tb6

Heparin (yellow) binds to and activates antithrombin. Antithrombin is the most important inhibitor of coagulation proteases like thrombin. Activation of antithrombin has an anticoagulant effect. Source: PDB entry 3evj

Heparin (yellow) binds to and activates antithrombin. Antithrombin inhibits thrombin (dark blue). Thrombin cannot activate fibrinogen (light blue) to build fibrin clots. Source: PDB entry 1tb6

Natural killer cells provide rapid responses to virus infected cells and tumor cells. They act at around 3 days after infection.

G-protein-coupled receptors (GPCRs) have central roles in intercellular communication. From left to right, Rhodopsin activated by light, T-cell receptor activated by MHC and antigen (green), dopamine receptor activated by dopamine (red), GABA B receptor activated by the agonist baclofen. G alpha proteins (light blue) activate the phosphodiesterase 6 (left), which degrades cGMP, and adenylyl cyclase (right), which produces cAMP. cAMP activates the protein kinase C.

G-protein-coupled receptors (GPCRs) have central roles in intercellular communication. From left to right, Rhodopsin activated by light, T-cell receptor activated by MHC and antigen (green), dopamine receptor activated by dopamine (red), GABA B receptor activated by the agonist baclofen. G alpha proteins (light blue) activate the phosphodiesterase 6 (left), which degrades cGMP, and adenyly

GABA B receptors are G protein-coupled receptors, also called metabotropic receptors. Binding of an agonist (baclofen, red) leads to a G-protein coupled C-AMP signaling pathway. Source: PDB entries 7eb2, 6r3q ,.

GABA B receptors are G protein-coupled receptors, also called metabotropic receptors. Binding of an agonist (here baclofen, red) leads to a G-protein coupled C-AMP signaling pathway.

GABA B receptors are G protein-coupled receptors, also called metabotropic receptors. Binding of an agonist (here baclofen, red) leads to a G-protein coupled C-AMP signaling pathway. Source: PDB entries 7eb2, 6r3q ,.

Activation of rhodopsin by light leads to the hyperpolarization of photoreceptor cells. Rhodopsin is a light sensitive G-protein coupled receptor with retinal as cofactor. Source: PDB entry 6oy9

Activation of the melanocortin receptor. The melanocortin receptor 4 is crucial for appetite, energy homeostasis and body-weight control in the central nervous system. Source: PDB entries 7aue, 6r3q ,.

Molecules of the blood plasma 1: complement C1, 2: fibrinogen, 3: von Willebrand factor, 4: ferritin, 5: HDL, 6: immunoglobulin G, 7: immunoglobulin M, 8: albumin carrying fatty acids, 9: LDL.

Pentameric immunoglobulin M molecule. IgM is the first antibody that appears after exposure to an antigen. The dark blue subunit is the J chain.

Activation of the T-cell receptor (violet, lef) through the presentation of an antigen molecule (green) by MHC -2 (red). A G-alpha subunit of a G-protein (blue) gets then activated through GTP (yellow) binding and activates the adenylyl cylclase (violet, right), which produces c-AMP (red, highlighted) out of ATP. Source: PDB entries 1jl4, 1fyt, 6r3q .

Immune system cells: macrophages (left) segregate multiple cytokines, that activate other immune cells. Antigen presenting cells (bottom) activate T-cells and the adaptive immune response.

Long-term potention strengthening of synapses. NMDA receptor activates calmodulin through calcium ions. Calmodulin activates the CAMKII kinase, which regulates several proteins, eg the AMPA receptor.

From left to right: the NMDA and AMPA receptors transport calcium cations into neurons after being activated by the neurotransmitter glutamate and the GABA receptor (right) transport chloride anions after the activation by gamma aminobutyrate. PDB entries: 6wht, 3kg2, 6d6u

Ca2 + / calmodulin-dependent protein kinase II, key regulatory aminoacids. CAMKII is a key mediator of learning and memory. Misregulation of CAMKII seems to be linked to Alzheimer's disease.

CaMKII is regulated by the Ca2 + / calmodulin complex. CAMKII is a key mediator of learning and memory. Misregulation of CAMKII seems to be linked to Alzheimer's disease.

Cytokine storm: a cytokine storm is a physiological reaction in which the innate immune system causes an uncontrolled and excessive release of pro-inflammatory signaling molecules called cytokines.

The binding of the coronavirus spike protein (red) to an ACE2 receptor (blue) on a human cell leads to the penetration of the virus in the cell.

Dexamethasone, an anti-inflammatory drug with positive effects on serious COVID-19 patients

Monomeric tumor necrosis factor  receptors (light blue) get activated after binding TNF (dark blue) and build trimeric complexes. TNF receptors are primarily involved in apoptosis and inflammation. PDB entries: 2alq

Monomeric tumor necrosis factor  receptors (light blue) get activated after binding TNF (dark blue) and build trimeric complexes. The lighter bottom domains are the  death domains. TNF receptors are primarily involved in apoptosis and inflammation. PDB entries: 2alq, 1ich.

The angiotensin converting enzyme 2 (ACE2, blue) in complex with the amino acid transporter BOAT 1 (violet). ACE2 is involved in control of blood pressure and is the target for the SARS-CoV-2 virus to infect human cells..PDB; entry 6m17

TNF is a homotrimeric cytokine, a cell signaling protein, involved in inflammation processes. TNF main role is the regulation of immune cells. PDB entry 1tnf

The tumor necrosis factor receptor (light blue) with TNF (dark blue) bound. The lighter bottom domains are the  death domains. TNF receptors are primarily involved in apoptosis and inflammation. PDB entries: 2alq, 1ich.

A fibrin monomer (highlighted) is composed of 2? ?, 2? ?, 2? and 2? ? C domains. There are 4 flexible chains (light blue) in the center .. The 2 short .chains bind to two adjacent ? domains of the polymer. The ? ? C domains and the long flexible arms stabilize the polymer aditionally. PDB entries: 1m1j, 2baf.

Fibrinogen is composed of two trimers, and each trimer  oft three polypeptide chains.,. 2 flexible arms  at either sie. The four light blue chains are cut by  thrombin, turning into fibrin.  Hence fibrin polymerizes and builds blood clots with platelets. PDB entries: 1m1j, 2baf., 2a45

2 thrombin molecules (red)  activate fibrin by cutting some aminoacid residues (yellow glow) from the flexible arms in the middle of the fibrinogen molecule. Hence fibrin polymerizes and builds blood clots with platelets. PDB entries: 1m1j, 2baf., 2a45

Immune response to coronavirus infection: coronaviruses marked bei antibodies are engulfed and destroyed by a macrophage immune cell

2 thrombin molecules (red)  activate fibrin by cutting some aminoacid residues from the flexible arms in the middle of the fibrinogen molecule. Hence fibrin polymerizes and builds blood clots with platelets. PDB entries: 1m1j, 2baf., 2a45

Fibrinogen turns to fibrin by the catalysis of thrombin, that cleaves the short flexible arms in the middle of the molecule. Hence fibrin polymerizes and  builds with platelets a clot over blood vessel injuries. PDB entries: 1m1j, 2baf.

Erythrocytes (red blood cells) are trapped within a fibrin mesh.

Spike protein (violet), RNA polymerase (orange), main protease (red). This proteins are the main targets for .drugs against COVID-19.. PDB entries: 6vsb, 7btf, 6lu7.

Coronavirus breaking out of infected pneumocytes type II in a human lung. The darker cells are pneumocytes type I.

From left to right.: spike protein, RNA polymerase, main protease. This proteins are the main targets for .drugs against COVID-19.. PDB entries: 6vsb, 7btf, 6lu7.

Pyramidal neurons fluorescence-marked. They are found in the cerebral cortex, the hippocampus and the amygdala.

From upper left to right: spike protein, RNA polymerase, main protease with an inhibitor bound. This proteins are the main targets for drugs against COVID-19.. PDB entries: 6vsb, 7btf, 6lu7.

Protoplasmic astrocytes (violet) play an active role in neuronal communication through synapses and regulation of neural circuit functions, memory and learning.

Protoplasmic astrocytes (violet) play an active role in neuronal communication through synapses and regulation of neural circuit function.

The nucleotide analog remdesivir blocks the SARS-CoV-2 RNA dependent RNA polymerase and is a promising drug for the treatment of COVID-19. RdRp is an enzyme that catalyzes the replication of RNA from an RNA template. PDB entry 7BTF

The SARS-CoV-2 RNA dependent RNA polymerase is a promising target for the treatment of COVID-19. RdRp is an enzyme that catalyzes the replication of RNA from an RNA template. PDB entry 7BTF

Immune response to SARS-CoV-2: B-lymphocyte releases antibodies that bind to and mark coronaviruses. Hence, the viruses can't penetrate into their target cells and are engulfed and destroyed by a macrophage (cell in the background).

The SARS-CoV-2 RNA dependent RNA polymerase is a promising target for the treatment of COVID-19.

Coronaviruses coated with antibodies can't penetrate into their target cells and are engulfed and destroyed by a macrophage (cell in the background).

Antibodies binding to the spike protein (red) of the coronavirus prevent it's binding to ACE2 (light blue) on a human cell.

Binding of antibodies to the spike (S)-protein of the SARS-CoV-2 virus is an essential  step for  developing immunity to the coronavirus.

The antiretroviral protease inhibitor lopinavir is onsidered a potential drug against Sars-CoV-2 infections..

The SARS-CoV-2 viruis has 3 surface proteins. attached to a lipid bilayer. The biggest is the spike (S) protein. Source: PDB entries 6vsb, 5x29.

Binding of antibodies to the spike (S)-protein of the SARS-CoV-2 virus is an essential  step for  developing immunity to the coronavirus. PDB source 6VSB, 1IGT

4 potential drugs against the coronavirus SARS-CoV-2. Clockwise from upper left: remdesivir, lopinavir, camostat, chloroquine

Binding of antibodies to the spike (S)-protein of the SARS-CoV-2 virus is an essential  step for  developing immunity to the coronavirus. PDB source 6VSB, 1IGT, 5X29

Coronaviruses. The SARS-CoV-2 virus has 3 different surface proteins.

The antimalaria agent  chloroquine is considered a potential drug against Sars-CoV-2 infections..

The protease inhibitor camostat is a potential candidate for the treatment of Sars-CoV-2 infections.

Binding of the coronavirus spike protein(red)  to an ACE2 receptor (blue) on a human cell  leads to the penetration of the virus in the cell, as depicted in the background.

Structure of the coronavirus. The SARS-CoV-2 virion has four structural proteins: S (spike, dark blue), E (envelope, violet), M (membrane, light blue) attached to the lipid membrane (orange), and the N (nucleocapsid, light violet) protein holding the genome RNA (yellow). PDB entry 6vsb., 5x29, 2ca1.

Phages inject their RNA/DNA in specific bacteria strains, replicate and burst out of them. Phages are a possible therapy against multi-drug-resistant bacteria.

Bacteriophages from the families: myoviridae (left), siphoviridae and podoviridae (right). Phages inject their RNA / DNA in specific bacteria strains, replicate and burst out of them. Phages are a possible therapy against multi-drug-resistant bacteria.

The nucleotide analog remdesivir is considered a promising candidate for the treatment of Sars-CoV-2 infections .. It causes a decrease in viral RNA production.

Bacteriophages infecting a bacterium. Phages inject their genome in specific bacteria strains and replicate in them. Phages are a possible therapy against multi-drug-resistant bacteria.

Bacteriophages infecting and killing bacteria. Phages inject their genome in specific bacteria strains, replicate and burst out of them. Phages are a possible therapy against multi-drug-resistant bacteria.

Common antibiotics: 1 rifampicin, 2 ciprofloxaxin, 3 doxorubicin, 4 cephalosporin, 5 tetracycline, 6 penicillin, 7 fusidic acid, 8 nalidixic acid, 9 novobiocin, 10 chloramphenicol, 11 vancomycin. Color code: H light blue, c blue, O red, N dark blue, Cl & F green, S yellow.

Active site of the coronavirus main protease with an inhibitor bound. The coronavirus 3CL hydrolase enzyme is essential for the maturation of the virus. It can be a promising target for drugs that would inhibit cleavage of the viral polyprotein and prevent spread of the infection. Source: PDB entry 6LU7

The coronavirus causes the severe illness SARS (Severe Acute Respiratory Syndrome).

The spike protein (red) mediates the coronavirus entry into host cells. It binds to the angiotensin converting enzyme 2 (blue) through its S1 subunit and then fuses viral and host membranes through the S2 subunits.

Vancomycin, a tricyclic glycosylated peptide, binds to the peptide chains of a peptidoglycane. Thus, the D-alanyl-D-lactate ligase (blue) cannot build up the bacterial wall, leading to the death of the bacterium. Source: PDB entry 1e4e.

Penicillin is an antibiotic derived from Penicillium fungi. It is effective against many bacterial infections, although many bacteria have developed resistance.

D-alanyl-D-lactate ligase (blue) synthesizes cell-wall precursors in bacteria, that are resistant to the antibiotic vancomycin (yellow), so that it cannot bind to the cell-wall. Source: PDB entry 1e4e.

D-alanyl-D-lactate ligase (VanA) synthesizes cell-wall precursors in bacteria, that are resistant to the antibiotic vancomycin. The cofactor ADP is visible in the active site. Source: PDB entry 1e4e.

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Juan Gaertner

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