Month: September 2022

PARALLEL EVOLUTION OR MYTH? “The record shows that it was there that Jenner heard a dairymaid say, “I shall never have smallpox for I have had cowpox. I shall never have an ugly pockmarked face.” It fact, it was a common belief that dairymaids were in some way protected from smallpox.” https://lnkd.in/eQfnZZv View in LinkedIn

SO ENDS this first of two weekend Fragments on a snippet of the history of the smallpox vaccine, the first to be successfully developed in the west. The attribution of the discovery to Jenner was clearly only a tiny part of a much bigger chain of observations and experiments worldwide, including its practice in the 10th century. What is very interesting is how, without the germ theory of diseases, or experimental methodology, various cultures came up with the same solution. And, without controlled preparations, there was clear immunity induced. View in LinkedIn

ON VIRIONS AND VIRUSES. “According to Bandea’s hypothesis, the infected cell is the virus, while the virus particles are ‘spores’ or reproductive forms. His theory was largely ignored until the discovery of the giant mimivirus, which replicates its DNA genome and produces new virions in the cytoplasm within complex viral ‘factories’. Claverie suggested that the viral factory corresponds to the organism, whereas the virion is used to spread from cell to cell. He wrote that “to confuse the virion with the virus would be the same as to confuse a sperm cell with a human being”. https://lnkd.in/eDXduUb View in LinkedIn

EYE OF THE BEHOLDER. “Those who consider the virus to be the infected cell also believe that viruses are alive.” https://lnkd.in/eDXduUb View in LinkedIn

RECLASSIFICATION. “This argument leads to the assumption that viruses are living, according to the classical definition of living organisms as cellular organisms. Raoult and Forterre have therefore proposed that the living world should be divided into two major groups of organisms, those that encode ribosomes (archaea, bacteria and eukarya), and capsid-encoding organisms (the viruses).” https://lnkd.in/eDXduUb View in LinkedIn

“TRANSPOSABLE ELEMENTS, also known as "jumping genes," are DNA sequences that move from one location on the genome to another...roughly half of the human genome is made up of transposons...most of the transposon sequences in the human genome are silent...transposons can drive the evolution of genomes by facilitating the translocation of genomic sequences, the shuffling of exons, and the repair of double-stranded breaks. Insertions and transposition can also alter gene regulatory regions and phenotypes.” https://lnkd.in/e_F3_XW View in LinkedIn

TRANSPOSON VIRIONS. “Unexpectedly, we have recently found that the majority of the Polintons encode two proteins homologous to the typical capsid proteins of other viruses, strongly suggesting that, at least under some conditions, these transposons actually produce virions that could infect new hosts.” http://onlinelibrary.wiley.com/doi/10.1111/nyas.12728/full View in LinkedIn

TWO LIFESTYLES. “Thus, Polintons, which we believe should be more properly denoted polintoviruses, appear to lead a dual lifestyle combining features of viruses and transposons.” http://onlinelibrary.wiley.com/doi/10.1111/nyas.12728/full View in LinkedIn

ANCIENT ANCESTORS: polintoviruses as the first group of eukaryotic dsDNA viruses that evolved from prokaryotic viral ancestors and played a central role in the evolution of eukaryotic viruses and selfish elements.” http://onlinelibrary.wiley.com/doi/10.1111/nyas.12728/full View in LinkedIn

LARGE DIVERSE GENOMES. “The genomes of Polintons are large by transposon standards, 15–20 kb, and encode arrays of diverse proteins. However, several proteins are shared by all Polintons, including protein-primed type B DNA polymerase (pPolB), RVE family integrase, FtsK-like DNA-packaging ATPase, and an adenovirus-type cysteine protease implicated in the maturation of capsid proteins.” http://onlinelibrary.wiley.com/doi/10.1111/nyas.12728/full View in LinkedIn