Here numerous HIV-1 particles leave a cultured HeLa cell. These viruses lack their vpu gene and thus can’t detach from the cell’s tethering factor, BST2. Each viron particle is ~120nm in diameter. The image was captured with a Zeiss Merlin ultra high-resolution scanning electron microscope. The cells were fixed, dehydrated, critical-point dried, and lightly sputter-coated with gold/palladium.
The seminiferous tubules (pseudocolored blue in the image to the left) are part of the male reproductive system and are the site of sperm production and development. The majority of the volume of the testis comprises tightly compacted seminiferous tubules, and the total collective length of these tubules in humans can range from 300 to 700 meters.
Image: Spermatids (pink) in seminiferous tubules of mouse testis. Digitally pseudocolored scanning electron microscopy.
For the first time, and to the astonishment of many of their colleagues, researchers created what they call Alzheimer’s in a Dish — a petri dish with human brain cells that develop the telltale structures of Alzheimer’s disease. In doing so, they resolved a longstanding problem of how to study Alzheimer’s and search for drugs to treat it; the best they had until now were mice that developed an imperfect form of the disease.
Killer T-Cell Attacking Cancer
A major advance in cancer research is harnessing the capacity of the immune system to track down and destroy tumor cells. Here, Cytotoxic T lymphocytes (green) kill virally infected and tumor cells (red) by secreting cytolytic proteins. The centrosome (red dots) determines where secretion occurs by contacting the plasma membrane at the point where the T cell recognizes the tumor cell.
Movie: The attacking CTL is visualized with an intensity spectrum that lights up actin. In both videos the CTLs express Cherry and GFP fusion proteins, which mark the centrosome and actin, respectively. Target cells express a blue plasma membrane fusion protein; nuclei are labeled in blue. Movie editing and narration by Cambridge University.
Approximately 80% of malignant tumors in the CNS are gliomas, which include morphologically distinct cancers that resemble astrocytes, oligodendrocytes and ependymal cells. Such heterogeneity suggests that glioma originates from multiple cell types. Another possibility, however, is that gliomas arise from mutated neural stem cells (NSCs), which could give rise to a variety of tumors.
Recently, Hui Zong and colleagues address this debate by engineering a “mosaic” mouse with three types of NSCs: mutations in the tumor suppressors p53 and Nf1 (green); wild-type p53 and Nf1 (red); and, heterozygous for both mutations (yellow). All three NSCs give rise to the normal repertoire of neuronal cell types, but only mutant NSCs give rise to oligodendrocyte precursor cells (crescent-shaped cells) that develop into malignant gliomas.
Image: The brain of a “mosaic” glioma model mouse imaged by confocal microscopy at the pre-transforming stage (inset; postnatal day 60) and the early stage (three months) when the tumor started to emerge (white box). Mutant, wild type, and heterozygous cells are labeled as green, red, and yellow, respectively. The green cells with small “crescent” cell bodies are mutant oligodendrocyte precursor cells, the cell of origin for the glioma at the later stage. Scale, 2 cm.
Medicine, as we are practising it, is a luxury trade. We are selling bread at the price of jewels… Let us take the profit, the private economic profit, out of medicine, and purify our profession of rapacious individualism… Let us say to the people not ‘How much have you got?’ but ‘How best can we serve you?