Limits...
Appraisal of microbial evolution to commensalism and pathogenicity in humans.

Ghosh AR - Clin Med Insights Gastroenterol (2013)

Bottom Line: The human body is host to a number of microbes occurring in various forms of host-microbe associations, such as commensals, mutualists, pathogens and opportunistic symbionts.While this association with microbes in certain cases is beneficial to the host, in many other cases it seems to offer no evident benefit or motive.The present discussion examines this interaction while tracing the origins of this association, and attempts to hypothesize a possible framework of selective pressures that could have lead microbes to inhabit mammalian host systems.

View Article: PubMed Central - PubMed

Affiliation: Centre for Infectious Diseases and Control, Division of Medical Biotechnology, School of Biosciences and Technology, VIT University, India.

ABSTRACT
The human body is host to a number of microbes occurring in various forms of host-microbe associations, such as commensals, mutualists, pathogens and opportunistic symbionts. While this association with microbes in certain cases is beneficial to the host, in many other cases it seems to offer no evident benefit or motive. The emergence and re-emergence of newer varieties of infectious diseases with causative agents being strains that were once living in the human system makes it necessary to study the environment and the dynamics under which this host microbe relationship thrives. The present discussion examines this interaction while tracing the origins of this association, and attempts to hypothesize a possible framework of selective pressures that could have lead microbes to inhabit mammalian host systems.

No MeSH data available.


Related in: MedlinePlus

Possible changes in the human genome due to residential microflora. Human genome underwent possible rearrangement and reassortment with the intervention of retrotransposon from commensals leading to the variability in immunoglobulin (Ig) and hence in variable receptors on T and B cells.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4020404&req=5

f3-cgast-6-2013-001: Possible changes in the human genome due to residential microflora. Human genome underwent possible rearrangement and reassortment with the intervention of retrotransposon from commensals leading to the variability in immunoglobulin (Ig) and hence in variable receptors on T and B cells.

Mentions: The Recombination Activating Genes (RAG 1 and 2) are both critical in rearranging the immunoglobulin gene segments in T and B cells.28,32 Again, a homology detected in these DNA processing enzyme genes and the site-specific recombinases in prokaryotes suggests a relation between the vertebrate immune system and the rearrangement and recombination mechanisms of prokaryotes. Furthermore, the RAG 1 homology domain resembles the integrase (INT) family of microbial site-specific recombinases, in particular the E. coli site specific fim recombinases appeared to be the most related to the RAG 1 protein,28 suggesting that the recombination and rearrangement capacity of the human immunoglobulin system is possibly derived from an association with microbes during the evolutionary stages (Fig. 3). Similarly RAG 2 resembles the bacterial integration host factor (IHF) proteins, a fact that further bolsters the argument that an exchange of genes took place to allow colonization of microbes in the hosts.28,42–44


Appraisal of microbial evolution to commensalism and pathogenicity in humans.

Ghosh AR - Clin Med Insights Gastroenterol (2013)

Possible changes in the human genome due to residential microflora. Human genome underwent possible rearrangement and reassortment with the intervention of retrotransposon from commensals leading to the variability in immunoglobulin (Ig) and hence in variable receptors on T and B cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4020404&req=5

f3-cgast-6-2013-001: Possible changes in the human genome due to residential microflora. Human genome underwent possible rearrangement and reassortment with the intervention of retrotransposon from commensals leading to the variability in immunoglobulin (Ig) and hence in variable receptors on T and B cells.
Mentions: The Recombination Activating Genes (RAG 1 and 2) are both critical in rearranging the immunoglobulin gene segments in T and B cells.28,32 Again, a homology detected in these DNA processing enzyme genes and the site-specific recombinases in prokaryotes suggests a relation between the vertebrate immune system and the rearrangement and recombination mechanisms of prokaryotes. Furthermore, the RAG 1 homology domain resembles the integrase (INT) family of microbial site-specific recombinases, in particular the E. coli site specific fim recombinases appeared to be the most related to the RAG 1 protein,28 suggesting that the recombination and rearrangement capacity of the human immunoglobulin system is possibly derived from an association with microbes during the evolutionary stages (Fig. 3). Similarly RAG 2 resembles the bacterial integration host factor (IHF) proteins, a fact that further bolsters the argument that an exchange of genes took place to allow colonization of microbes in the hosts.28,42–44

Bottom Line: The human body is host to a number of microbes occurring in various forms of host-microbe associations, such as commensals, mutualists, pathogens and opportunistic symbionts.While this association with microbes in certain cases is beneficial to the host, in many other cases it seems to offer no evident benefit or motive.The present discussion examines this interaction while tracing the origins of this association, and attempts to hypothesize a possible framework of selective pressures that could have lead microbes to inhabit mammalian host systems.

View Article: PubMed Central - PubMed

Affiliation: Centre for Infectious Diseases and Control, Division of Medical Biotechnology, School of Biosciences and Technology, VIT University, India.

ABSTRACT
The human body is host to a number of microbes occurring in various forms of host-microbe associations, such as commensals, mutualists, pathogens and opportunistic symbionts. While this association with microbes in certain cases is beneficial to the host, in many other cases it seems to offer no evident benefit or motive. The emergence and re-emergence of newer varieties of infectious diseases with causative agents being strains that were once living in the human system makes it necessary to study the environment and the dynamics under which this host microbe relationship thrives. The present discussion examines this interaction while tracing the origins of this association, and attempts to hypothesize a possible framework of selective pressures that could have lead microbes to inhabit mammalian host systems.

No MeSH data available.


Related in: MedlinePlus