Our RNA World @ MHC

You may know the role of RNA in the central dogma: DNA makes RNA makes proteins. But RNA is an amazing molecule that is capable of so much more. There are so many types of RNAs besides the most commonly known RNAs involved in translation: mRNA and tRNA. For instance, microRNAs (miRNAs) are one such fascinating yet lesser known type of RNA.  These small RNA molecules are “non-coding” RNAs. This just means they are not translated into proteins. Instead, miRNAs regulate gene expression at the post-transcriptional level , after the DNA has been transcribed into mRNA. This means that less of the protein encoded for by that gene will be produced. This regulatory process is known as post-transcriptional “gene silencing”. Many miRNAs play important roles in development and can be expressed in a tissue specific manner. For example, miRNAs are important in in morphogenesis, the process by which a developing organism begins to take shape through spatial distribution and organization of cell...

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...