Colonic dendritic cells (red) in crypts (SC)
In addition to their role as executioners, caspases also participate in a variety of non-apoptotic processes, such as cellular remodeling. For instance, during the production of Drosophila sperm, cytoplasmic content must be removed to complete differentiation. To prevent excessive activation and unwanted death of the sperm precursors, caspases (red) are not activated uniformly but rather in a gradient descending from the cell’s nucleus to the end of its tail. This unique activation pattern is determined by an inverse gradient of Soti (green), an inhibitor of a ubiquitin ligase complex required for caspase activation.
By Yosef Kaplan and Eli Arama, Weizmann Institute of Science (Cell Picture Show)
DNA Microarray wonders
Until recently, geneticists have been limited to studying the genome of an organism “one gene at a time” through mutational analysis. But with the accumulation of vast amounts of DNA sequence information in the last ten years, molecular geneticists have expanded their studies of gene function to the cell-wide level. This global approach to studying gene expression and gene interaction is called functional genomics.
One technological advance that has allowed the mining of the DNA database is the invention of DNA microarrays. These arrays, or chips, are samples of DNA laid out as a series of microscopic spots bound to a small glass slide. One slide can contain thousands of individual spots of DNA segments, each corresponding to a different section of the genome. These microarrays present an opportunity to examine the expression of every gene under a given set of environmental or developmental conditions. (Carleton College)
I feel like I’m in the middle of this biological phenomena and more and more data is coming out fast than humans can come together to analyze it. I defiantly need to learn how to read microarrays.
What we really need is top-notch bioinformatics geniuses able to create computers and programs that actually can handle all this data. Hey, to the people spending all your time on facebook, yeah, the fake “geeks”, do you want to become bioinformatics engineers ?
I thought so.
Fig. 3. Forced expression of desmin mutants in human cultured cells. Indirect immunofluorescence microscopy of human desmin- and vimentin-free SW13 cells cDNA-transfected with WT desmin (A), DesE245D (B), DesA360P (C), DesL385P (D), DesA357P (E), and DesL345P (F). Green, immunostaining; blue, DAPI staining. Note that DesE245D and DesA360P form an apparently normal IF network in the transfected cells shown, whereas all other mutations, which exhibit a compromised in vitro filament assembly, only show intracytoplasmic aggregates. (Scale bar: 10 μm.)
There’s something that has been bothering me for a while now. Mouths : how do they work ? Have you ever noticed that our mouths seem to heal way faster than the rest of our body ? And even as we’ve burnt and cut our tongues, palates and gums way more than we can count, we can’t see or feel any major scars. WHY ? How is that not a thing ?
Well apparently it is a thing. Prof. Sandu Pitaru and his graduate students have studied the oral mucosa, a source for fetal-like stem cells. They successfully harvested these cells from the oral mucosa to turn them into stem cells capable of generating bone, cartilage, muscle or even neurons. These cells behave like fetal cells and don’t seem to produce any aggressive tumors. Being able to implant them could imply new therapies for neurodegenerative, heart, or autoimmune diseases. (Gafni et al. 2011)
And it all started with a simple question : Why ?
Lamellipodia are not the only way for cells to get about— plasma membrane blebs can also drive cell migration. Once thought to be restricted to dying cells, these spherical membrane protrusions are now thought to be particularly important in tumor cells, which have been shown to switch between the lamellipodia- and bleb-based motility.
Image: Cells from culture were imaged with a JEOL 6700 Field Emission Scanning Electron Microscope, and then false colored with Adobe Photoshop. By Anne Weston, Cancer Research UK. (Cell.com)
Colorized transmission electron micrograph of goblet cells packed full of mucous globules (blue). The cells release the globules to provide lubrication and protection to the inner surfaces of the intestine and the respiratory system among others. The mucous globules are condensed inside the goblet cell but expand hugely once they are released, absorbing water within 20 milliseconds. This rapid release occurs in response to lots of different stimuli and allows the mucous to work instantly. The horizontal field width of the sample is 17.3 micrometers. (Cell Image Library)
A C. elegans adult and a polarized embryo express the polarity proteins PAR-2 (green) and PAR-6 (red). Goehring et al. analyze the dynamics of these two proteins as they diffuse between opposing membrane domains and exchange with cytoplasmic pools.
Image courtesy of Nathan Goehring.
Reference: Goehring et al. (2011) J. Cell Biol. 193, 583-594.
Why does a volcanic eruption sometimes create lightning? Pictured above, the Sakurajima volcano in southern Japan was caught erupting in early January. Magma bubbles so hot they glow shoot away as liquid rock bursts through the Earth’s surface from below. The above image is particularly notable, however, for the lightning bolts caught near the volcano’s summit. Why lightning occurs even in common thunderstorms remains a topic of research, and the cause of volcanic lightning is even less clear. Surely, lightning bolts help quench areas of opposite but separated electric charges. One hypothesis holds that catapulting magma bubbles or volcanic ash are themselves electrically charged, and by their motion create these separated areas. Other volcanic lightning episodes may be facilitated by charge-inducing collisions in volcanic dust. Lightning is usually occurring somewhere on Earth, typically over 40 times each second. (Astronomy Picture of the Day)
Image Credit & Copyright: Martin Rietze
The Illusion of Reality
In 1999, a movie came out which blew everyone’s mind, and still twists our brains today : the Matrix. It described a future where reality is an illusion, a computer-simulated universe in which we thrive. Solipsism with guns in a post-apocalyptic world. But what if I told you… they’re right ? In fact that’s not true, they’re probably completely mistaken. Reality is not a computer-generated dream. Reality is empty. Well… 99,99% empty.
Science basics, matter is made of atoms. Atoms are themselves made of a cloud of electrons orbiting a dense nucleus of protons and neutrons. Separating electrons and the nucleus is just air. Not even air, since air is composed of molecules. This is why I can say that atoms are mostly empty, and therefore matter is mostly empty. We’ve known this for a very long time. Most of us would just give up and say “matter is nothing, so why bother ?”. Most of us, but not scientists. Scientists have twisted and mangled these teensy balls of nothing. They stripped these minuscule objects apart and threw the remains into a 27 kilometers collider to blow them up. They’ve invented machines and probes to witness matter in its very extreme intimacy. In 1951 they invented the Field Ion Microscope and they’ve taken pictures… of individual atoms. Repelled ions looking like clusters of stars or ripples into the nothingness.
So, why bother ? That’s why. Matter is almost empty. But we were here, and we took pictures to prove it.
Picture : Examples of field ion micrographs of (a) iridium, (b) a Pd40Ni40P20 bulk metallic glass, (c) a decorated grain boundary in a neutron-irradiated pressure vessel steel, and (d) 5nm-diameter secondary precipitates in the nickel-based superalloy Alloy 718
M.K. Miller (2000) The Development of Atom Probe Field-Ion Microscopy, Materials Characterization (44):1-2 11-27
Using techniques that took 4 years to design, a team of developmental biologists has shown that certain proteins can direct the subdivision of fruit fly and chicken nervous system tissue into the regions depicted here in blue, green, and red. Molecules called bone morphogenetic proteins (BMPs) helped form this fruit fly embryo. While scientists knew that BMPs play a major role earlier in embryonic development, they didn’t know how the proteins help organize nervous tissue. The findings suggest that BMPs are part of an evolutionarily conserved mechanism for organizing the nervous system. Courtesy of Mieko Mizutani and Ethan Bier of the University of California, San Diego, and Henk Roelink of the University of Washington.
Article abstract (from the September 2006 issue of PLoS Biology)
Featured in the October 17, 2006, issue of Biomedical Beat.
Fig. 4. Immunofluorescence confocal micrographs showing subcellular dUNC-45 localization in the body-wall muscle of third instar wild-type larvae. (A) α-Actinin staining highlights the location of the Z-discs. (B) dUNC-45 is discretely localized in the sarcomere. (C) Actin staining with phalloidin shows the location of I bands in the sarcomeres. (D) dUNC-45 colocalizes with α-actinin (bright pink in the overlay panel) and bisects the actin-containing I bands, which supports dUNC-45 location in the Z-discs of the sarcomeres.
Drosophila UNC-45 accumulates in embryonic blastoderm and in muscles, and is essential for muscle myosin stability (2011) Journal of Cell Science (124):5, 699-705
Chlorhexidine (CHX), widely used as antiseptic and therapeutic agent in medicine and dentistry, has a toxic effect both in vivo and in vitro. The intrinsic mechanism underlying CHX-induced cytotoxicity in eukaryotic cells is, however, still unknown.
Fig. 1. Representative images by scanning electron microscopy of the effect of CHX L929 fibroblasts. (A) Control cultured L929 fibroblasts. (B) Fibroblasts submitted to CHX at a concentration of 0.0005% are enlarged, showing decreased number of filopodia. (C) At a concentration of 0.001%, the fibroblasts are in small number, with an oval appearance and disrupted filopodia. (D) At a concentration of 0.002% the fibroblasts have an oval appearance and no filopodia. Bar = 15 μm.
Chlorhexidine-induced apoptosis or necrosis in L929 fibroblasts: A role for endoplasmic reticulum stress (2009) Toxicology and Applied Pharmacology (234):2, 256–265