196,801 research outputs found
Pre-mRNA introns as a model for cryptographic algorithm: theory and experiment
No full textThe RNA-Crypto System (shortly RCS) is a symmetric key algorithm to cipher data. This algorithm, as
shown below, has the peculiarity to expand the message to be encrypted hiding the ciphered message itself
within a set of garbage and control information.
The idea for this new algorithm starts from the observation of nature. In particular from the observation
of RNA behavior and some of its properties.
In particular the RNA sequences has some sections called Introns. Introns, derived from the term
"intragenic regions", are non-coding sections of precursor mRNA (pre{mRNA) or other RNAs, that are
removed (spliced out of the RNA) before the mature RNA is formed. Once the introns have been spliced out
of a pre-mRNA, the resulting mRNA sequence is ready to be translated into a protein. The corresponding
parts of a gene are known as introns as well.
The nature and the role of Introns in the pre-mRNA is not clear and it is under ponderous researches
by Biologists but, in our case, we will use the presence of Introns, in the RNA-Crypto System output, as a
strong method to add only apparently chaotic and non coding information with an unnecessary behavior in
the access to the secret key to code the messages.
In the RNA-Crypto System algorithm the introns are sections of the ciphered message with non{coding
information as well as in the precursor mRNA. But the term "non{coding" does not necessarily mean "junk
data".
In this text a new cryptographic algorithm is described starting from a mathematical point of view
Use of Cryptographic Ideas to Interpret Biological Phenomena (and Vice Versa)
No full textThe RNA-Crypto System (shortly RCS) is a symmetric key algorithm to cipher data. This algorithm, as
shown below, has the peculiarity to expand the message to be encrypted hiding the ciphered message itself
within a set of garbage and control information.
The idea for this new algorithm starts from the observation of nature. In particular from the observation
of RNA behavior and some of its properties.
In particular the RNA sequences has some sections called Introns. Introns, derived from the term
"intragenic regions", are non-coding sections of precursor mRNA (pre-mRNA) or other RNAs, that are
removed (spliced out of the RNA) before the mature RNA is formed. Once the introns have been spliced out
of a pre-mRNA, the resulting mRNA sequence is ready to be translated into a protein. The corresponding
parts of a gene are known as introns as well.
The nature and the role of Introns in the pre-mRNA is not clear and it is under ponderous researches
by Biologists but, in our case, we will use the presence of Introns, in the RNA-Crypto System output, as a
strong method to add only apparently chaotic and non coding information with an unnecessary behavior in
the access to the secret key to code the messages.
In the RNA-Crypto System algorithm the introns are sections of the ciphered message with non{coding
information as well as in the precursor mRNA. But the term "non-coding" does not necessarily mean "junk
data".
In this text a new cryptographic algorithm is described starting from a mathematical point of view
M cell: the main entrance of the mucosal immune system
No full textM cells are higly specialized cells within the follicle-associated epithelium (FAE) of the respiratory and intestinal tracts. They play a central role in the induction of the mucosal immune response by transporting antigens to the lymphoid tissue. In this way the immune system may encounter the limitless variety of antigens that enter the body through the gut and airways. Here we describe the structure and the function of intestinal M cells. In addition, controversial issues relating to the M cell biology, such as APC function and the origin of M cells within the FAE, are discussed
Uptake of a Gram-positive bacterium (Streptococcus pneumoniae R36a) by the M cells of rabbit Peyer's patches
No full textThe epithelium associated with the lymphoid follicles of Peyer's patches differs from the villi epithelium by the presence of M cells. The main function of these cells is to take up antigens (inert material, viruses and bacteria) from the intestinal lumen. The M cells are able to internalize various different gram-negative bacteria. In order to show the M cells ability to interact and take up a gram-positive bacterium, we exposed rabbit Peyer's patches to Streptococcus pneumoniae R36a. Using the isolated ileal loop technique, Peyer's patches were incubated with a bacterial suspension for varying periods (15, 30, 60, 100 minutes). The bacteria were found outside and inside the M cells. The internalized streptococci could be found in the M cell cytoplasm, in the cytoplasmic "pockets" and inside the intraepithelial lymphoid cells. The finding of internalized bacteria with their damaged walls suggests the possibility that M cells are able to modify internalized antigens in the same way as the antigen presenting cells
Dendritic cells in the gut: to sample and to exclude?
No full textOver the past few years one of the most important concepts that emerged in the area of gut immunology derived from the observation by Rescigno et al.1 on the ability of intestinal dendritic cells (DCs) to extend cellular extensions between epithelial cells into the intestinal lumen, to internalize bacteria and shuttle them across the epithelial barrier. This sophisticated mechanism for antigen-sampling complements the well-studied M-cell-mediated transport of particulate antigen and bacteria.2 We have recently reported that DC-mediated sampling is not the only event taking place at the host–pathogen interface in the small intestine during the early stage of bacterial infection. Indeed, a proportion of DCs that rapidly migrate to the lamina propria following challenge with non-invasive Salmonella lacking the Salmonella Pathogenicity Island 1 (SPI1) did not act as an antigen-sampling cell but crossed the epithelium and moved into the gut lumen (Figure 1) before or following internalization of Salmonella.3 The migration of CD11c+CX3CR1+MHCII+CD11b-CD8-DCs was found to be flagellin- and MyD88-dependent, it was restricted to the small intestine and it was not observed in MyD88 mice. Interestingly, intraluminal DCs internalized Salmonella but did not cross the epithelium to return into the tissue. The finding that DCs migrate into the gut lumen following a challenge with a pathogen suggests a few observations. First, it appears that the same antigenic stimulus (e.g., non-invasive Salmonella) can induce DCs to either sample or to migrate into the gut lumen thus showing the complexity of the signaling network operating at the host–pathogen interface; second it tells us that many of the intraepithelial DC extensions previously considered to be "sampling" devices are a feature of DCs undergoing transepithelial migration. At this time the role of the intraluminal "bacteria-capturing" DCs remains to be determined. The migration of phagocytes into the gut lumen was described in the past and it was interpreted as a mechanism of cellular control of the gut pathogens;4, 5 thus, it is possible to hypothesize that DCs are also part of a similar defence mechanism. Sending phagocytes, including DCs, into the lumen of the small intestine would possibly help to limit the number of pathogens that can cross the epithelial barrier and infect the host; a strategy that would complement the immune exclusion mediated by mucous and sIgA antibod
From cyptography to biology and vice versa
No full textWe introduce a new symmetric cryptographic algorithm, based on the biological principle of redundancy. This algorithm has very good security and statistical properties. In addition, it suggests a nontrivial information-theoretical interpretation of the redundancy mechanism in DNA sequences which does not seem to be present in biological literature: according to this interpretation the introns do not directly code information, but play an essential role in the decoding procedure
Rabbit tonsil-associated M-cells express cytokeratin 20 and take up particulate antigen
No full textM-cells are believed to play a pivotal role in initiation of the immune response. These cells, located in the epithelia that overlie mucosal lymphoid follicles, are responsible for the active uptake of particulate antigens and for their translocation to the underlying lymphoid tissue. The identification of reliable markers for M-cells is therefore extremely important for the study of the initial steps that lead to the immune response. For this purpose, we studied cytokeratin 20 (CK20) expression in the epithelium of rabbit palatine tonsils by immunofluorescence, confocal microscopy, and Western blotting. CK20+ cells were observed in all rabbit palatine tonsils examined. By Western blotting, one CK20-immunoreactive band was identified at 46 kD on samples of proteins from the intermediate filament-enriched cytoskeletal fraction of tonsil epithelium. Double labeling of CK20+ cells with cell-specific markers confirmed that such cells were actually M-cells. Moreover, CK20+ M-cells displayed a mature phenotype (they formed pockets harboring lymphoid cells) and were functionally competent because they could take up particulate antigens from the pharyngeal lumen. We conclude that CK20 is an M-cell marker for rabbit palatine tonsils. Moreover, we can hypothesize the use of M-cells as a possible site for antigen delivery of particle-based vaccines
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