Our RNA World @ MHC

Summary of main points Retrotransposons are a type of mobile genetic element (MGE) that can copy and paste themselves multiple times throughout the genome using an RNA intermediate. Retrotransposons are widely considered to be harmful and bad for cells. They resemble retroviruses and our cells have developed mechanisms to protect against retrotransposition.  The prevalence of retrotransposons throughout the tree of life suggests they are evolutionary important. This contrasts the negative effects that can cause in cells.  Retrotransposons are suggested to generate more genetic diversity locally and globally in a genome, which is consistent with their prevalence in humans among other species. The glossary at the end of the post may have some helpful information should you need it :)  Figure 1: The mechanism of DNA transposition. In the past ten years alone, the study of mobile genetic elements (MGEs), or DNA sequences that can move around within a genom...

Since 2006, an unknown plague upon western honey bee communities has caused populations to plummet, putting the species in danger of extinction. Beekeepers and agricultural scientists named this mysterious illness Colony Collapse Disorder, as it causes large portions of worker bees to leave the hive and isolate themselves before dying. While there are a whole host of pathogens and illnesses known to be harmful to honeybees--including the modern problem of acute pesticide poisoning--no single pathogen has been identified as a probable cause of the startling phenomenon. Consequently, researchers from the Agricultural Research Service and University of Illinois conducted a study exploring possible genetic explanations. In the study, scientists collected tissue samples from the guts of honey bees either affected or unaffected by CCD, then performed experimental analysis of gene expression across the whole genome. Here, researchers saw that there were no irregularities in the exp...

Figure 1. Tomato plant infected with PSTVd. Have you ever encountered a funny looking plant that makes you think, “I shouldn’t eat this” by instinct? Maybe it was an OK crop that just looks weird, but it is possible for plants to catch ‘diseases’ as well, just like humans. Viruses can infect many hosts, from humans to small microorganisms. These viruses take advantage of living organisms, using the host to replicate themselves and eventually end up ‘killing’ the host if left unattended. Figure 2. Comparison of potatoes with or without PSTVd. PSTVd is one of these viruses that makes most of plants (aka your food) sick. PSTVd is short for Potato Spindle Tuber Viroid; it obtained that name by being found in potatoes for the first time. Symptoms of viroid infection in plants include stunting of growth, deformation of leaves and fruit, stem necrosis, and death. In the case of PSTVd affected potato, the plants show stunting of the plant and malformation and cracking of tuber...

Posted by Oliver Stockert            Today I am going to tell you about one of my favorite classes of RNAs. They are called small nucleolar RNAs (or snoRNAs). SnoRNAs are short, noncoding, and abundant in the nucleoli of eukaryotic organisms.  They have important roles within cells by associating with proteins, finding a specific mRNA, and modifying the mRNA with the help of the associated protein. There are two main types of snoRNAs that each have their own structure, function, and purpose. The two types are H/ACA box and C/D box snoRNAs. You may have heard of  sequence “boxes” in regards to proteins or RNA before; it just means a section of the sequence is genetically conserved to make snoRNAs function and bind with a high level of specificity. Figure 1 outlines the H/ACA boxes and the C/D boxes on each type of snoRNA. The boxes represent an important parts of the sequences that all C/D box or H/ACA box snoRNAs contain that helps them...

Ana was 22 years old when she found out she had it… Hepatitis C! Unlike others her age, she hadn’t yet had a boyfriend, gotten tattoos in non sterile conditions, damaged her liver by excessive drinking in college, or shared needles to inject drugs, all of which are ways one can get the disease (1). All she had done was receive a kidney (a solid organ) from her uncle who was born in 1962 in Japan, one of the few industrialized countries with high Hepatitis C rates (2). She first noticed the massive bruises on her arms and legs 6 months ago followed by the yellowing of her eyes (jaundice). Her doctor thought it was her body rejecting the kidney and causing her to have reduced platelets but after getting a biopsy, it turned out her liver had become cirrhotic and was failing. Cirrhosis is a chronic disease that leads to inflammation which, over time, replaces healthy liver cells with scar tissue. It takes about 20 to 30 years for this to happen (or faster if alcohol is drunk or if someon...