New Research and Studies Show Genetic Diversity in Corn

    Research and studies showed newly assembled genomes of 26 different genetic lines of corn, showing the crop’s rich genetic diversity. Detailed in an article published in the journal Science, first author of the study and an associate professor of ecology, evolution and organismal biology at Iowa State University, Matthew Hufford, says that these genomes as references can better help plant scientists select genes that lead to better crop yields or stress tolerance. The first corn genome, mapped in 2009 at Iowa State by Patrick Schnable and Doreen Ware and team, was the genetic line known as B73. Since then, B73 has served as the primary reference genome for corn, and scientists have a limited understanding of genetic sequences in corn genomes that are not in B73. The 26 genomes mapped in the new study, however, encompass a wide range of genetic diversity, including popcorn to sweetcorn to field corn from different geographical and environmental conditions. This genome mapping provides more reference data in order for scientists to combine maize genetics for targets that could lead to better crop performance. The large genetic diversity present in corn, however, creates major hurdles for the creation of new genomes, since 85% of the corn genome is composed of transposable elements. Hufford, comparing these elements to a jigsaw puzzle because the majority of pieces are one color. This repetition makes it harder to determine how the parts fit together. Technological advancements allow tools for researchers to overcome these hurdles, and allows for longer sequence reads, which make the pieces of the puzzle larger and more likely to be arranged properly by scientists.

Link to Study: https://www.sciencedaily.com/releases/2021/08/210805141202.htm

Link to Article: https://phys.org/news/2021-08-corn-genetic-diversity-genome.html

How We Got Here: DNA Points to a Single Migration From Africa

The question of where humans came from has been one of the biggest in science for years. Three separate teams of geneticists from different places, all sampling different people, sequenced the genomes of 787 people from hundreds of different populations and found that all humans came from a single population from Africa between 50,000 and 80,000 years ago. The genomes were taken from a variety of people from every continent and were examined separately to finally come up with the same conclusion as to where people came from. Before now, there were very few sequenced genomes from people outside of population centers like China and Europe, but this new data with genomes from indigenous populations adds great value to our understanding of human DNA. 

The first team was Dr. Willerslev and a few colleagues who first sequenced the genome from a century-old lock of hair of an Aboriginal Australian. The results raised many questions, so the group joined David W. Lambert and the University of Oxford to obtain DNA from people from Papua New Guinea and from Aboriginal Australians to sequence. Mait Metspalu from the Estonian Biocentre sequenced genomes mostly from populations from Europe and Asia.  David Reich and his team from Harvard Medical School formed their database of genomes from people from all six inhabited continents. All coming up with the same results, the teams each established that there was an exodus from Africa 80,000 to 50,000 years ago, resulting in the populations we have today. There is also evidence of other groups migrating from Africa much earlier than 80,000 years ago, but these groups have since disappeared, having been wiped out by others who came after them who were stronger in number or in technology. 

Fundamental Differences Found Between Human Cancers, Genetically Engineered Mouse Models

Researchers at the Fred Hutchinson Cancer Research Center in Seattle, Washington have been comparing mouse models of cancer to human cancer samples. These genetically engineered mice that usually overexpress a cancer causing gene have been extensively been used to understand human cancer biology. Cancer involves a complex interplay between genetic and epigenetic alterations. the epigenetic alterations mediate changes in gene expression without altering the DNA sequences. One of these important was found to be significantly different in the mouse models of medulloblastoma and primary  medulloblastoma human samples.

In my opinion, this may be an issue that needs a closer look. If researchers have found one significantly different sequences how many more can their be and even more, how different are the other sequences. I hope they go into more research to get a better understanding of the differences.

http://www.sciencedaily.com/releases/2013/12/131205142220.htm

http://emice.nci.nih.gov/aam/mouse/how-and-why-mouse-cancer-models-are-used