No hay productos en el carrito



Horizontal Gene Transfer in Microorganisms
Francino, M.
1ª Edición Septiembre 2012
Inglés
Tapa dura
202 pags
559 gr
16 x 24 x 2 cm
ISBN 9781908230102
Editorial CAISTER ACADEMIC PRESS
LIBRO IMPRESO
-5%
259,50 €246,53 €IVA incluido
249,52 €237,05 €IVA no incluido
Recíbelo en un plazo de
7 - 10 días
Description
There is a growing awareness that horizontal gene transfer (HGT) is a highly significant phenomenon amongst single-celled organisms. The evolution of bacteria and archaea most often results from the acquisition of new genes through horizontal transfer rather than by modification of vertically inherited genes. Horizontal or lateral gene transfer is a major factor in the spread of bacterial antibiotic resistance and other adaptive traits of microorganisms and is particularly significant in microbial communities. HGT may also play a substantial role in the emergence of novel infections and opportunistic pathogens.
Under the expert guidance of the editor, M. Pilar Francino, expert authors from around the world have contributed novel work and comprehensive, up-to-date reviews on the most topical aspects of horizontal gene transfer in microorganisms. Topics include: gene survival in emergent genomes, evolution of prokaryotic pangenomes, horizontal transfer of host-adaptability systems, barriers to horizontal gene transfer, evolution of horizontally transferred genes, lateral gene transfer in natural ecosystems, maintenance of plasmids among bacteria, mobile genetic elements in metagenomes, and the evolution of antibiotic resistance genes.
Aimed primarily at research scientists, graduate students and other experts, this book is a major resource for anyone interested in horizontal gene transfer, microbial evolution or antibiotic resistance in bacteria. A recommended book for all microbiology laboratories.
Contents
Chapter 1
Gene Survival in Emergent Genomes
M. Pilar Francino
As genome sequences have accumulated for closely related bacteria, our view
of bacterial genomes has radically changed. Genome comparisons have demonstrated
that little 16S sequence divergence can be accompanied by large differences
in total gene repertoire, and even populations of a single 16S rRNA species
are made up of vast numbers of genomic varieties. Much of the observed variation
among closely related genomes is attributable to gains and losses of genes that
are acquired horizontally, in addition to genomic rearrangements, including
gene duplications. The genomic flexibility that results from these mechanisms
certainly contributes to the ability of bacteria to survive and adapt in varying
environmental challenges. However, the duplicability and transferability of
individual genes imply that natural selection should operate, not only at the
organismal level, but also at the level of the gene. Therefore, it can be argued
that genes are semiautonomous entities capable of responding to natural selection
at different levels: selfishly, because they can "reproduce" by duplication
and "migrate" by Horizontal Gene Transfer (HGT), and cooperatively,
because their long-term survival depends on their ability to be replicated as
parts of integrated, emerging genomes. The extent of gene autonomy, or the tightness
of the association between gene and genome, can greatly vary, mostly depending
on the relative strengths of the selective processes acting at each of these
two different, but directly related, levels of organization.
Chapter 2
Evolution of Prokaryotic Pangenomes
Florent Lassalle and Vincent Daubin
Since the discovery of the two ancient "kingdoms" of Bacteria and
Archaea, molecular biologists have been constantly revising their perception
of the abundance and variety of microbial life, and the processes driving their
evolution. In the last years, genome sequences from closely related species
and strains of the same species have revealed a yet unforeseen diversity of
gene repertoires, much larger than could have been predicted by their morphologies
or biochemical capabilities. The origins and the functional significance of
these differences still need to be understood, and the techniques to address
these questions have yet by large to be invented. In this chapter, we will present
a review of the current knowledge on the mechanisms responsible for the diversity
of gene repertoires in prokaryotes.
Chapter 3
Horizontal Transfer of Host-adaptability Systems in Bacteria
Eva C. Berglund and A. Carolin Frank
Understanding the origin, evolution, maintenance, and breakdown of host-adaptation
is central to diverse areas such as human health and agriculture. Horizontal
gene transfer (HGT) is a recurrent theme in the evolution of host-adaptability
systems. Why are these genes often successfully transferred and what is the
consequence for the recipient genome? Drawing examples from the mammal-adapted
bacterium Bartonella, and from plant-adapted rhizobia, we discuss the role of
horizontal gene transfer in the evolution and ecology of host-adaptation.
Chapter 4
Barriers to Horizontal Gene Transfer: Fuzzy and Evolvable Boundaries
Fernando González-Candelas and M. Pilar Francino
The existence of numerous types of barriers to Horizontal Gene Transfer (HGT)
is well documented. Nevertheless, no barrier is impervious, and all kinds of
genes can occasionally find their way into organisms different from the ones
in which they evolved. This by no means implies a free flow of genes across
taxa, but, rather, the existence of complex networks of loopholes across barriers
that could potentially connect all kinds of organisms through gene transfer.
Loopholes may be provided by way of a small fraction of the individuals in an
otherwise inaccessible population and, if exogenous genes are incorporated into
the chromosome, homology-assisted recombination processes may further spread
them across wild type individuals. HGT networks should be very fluid, as they
depend heavily on fortuitous events and transient circumstances, such as the
presence of Mobile Genetic Elements (MGEs) in a potential donor that may extend
the transfer network in particular directions. Moreover, HGT networks should
be highly evolvable, as a result of 1) the multiplicity of processes with the
potential to modulate, modify or alleviate the different barriers to transfer,
2) the constantly changing selective pressures operating on them and 3) the
enormous plasticity of MGEs. Finally, HGT networks should be gene-specific,
as different genes should have an unequal likelihood of passing through or being
incorporated into new genomes.
Chapter 5
The Evolution of Horizontally Transferred Genes: a Model for Prokaryotes
Iñaki Comas and Fernando González-Candelas
Horizontal gene transfer is a pervasive evolutionary process which has developed
and is still developing an essential role in shaping biodiversity through providing
opportunities for innovation, moving determinants of functions among taxa, opening
opportunities for colonization of new niches, or acting as a catalyst for adaptation.
However, its importance in evolution has only recently begun to be recognized.
Reasons for this relatively late recognition of HGT and its relevance stem from
two main sources. One is the availability, or rather the lack thereof, of appropriate
information to infer the existence of HGT. This shortcoming has now been widely
overcome with the large, and still growing at a very fast rate, number of completely
sequenced genomes, which allow for precise phylogenetic reconstructions, along
with the deployment of theoretical models necessary for inferring evolutionary
events in deep-time. The second source is the appreciation that HGT does not
leave an indelible stamp on the transferred genes because these continue evolving
under a different genomic, and often ecological, environment which usually act
synergistically to erase the initially clear marks that go along with those
genes. In this chapter we provide an overview of these processes along with
a model proposal that will help to better understand the consequences of the
continuous evolution of laterally transferred genes at different evolutionary
time-scales.
Chapter 6
The Extent and Regulation of Lateral Gene Transfer in Natural Microbial Ecosystems
Rustam I. Aminov
The importance of horizontal gene transfer (HGT) in bacterial evolution is evident
from the retrospective analyses of bacterial genomes, which suggest that a substantial
part of bacterial genomes is of foreign origin. Another line of evidence that
supports the possibility of rapid adaptation of bacteria through lateral gene
exchange is the history of antibiotic use by humans. Within a very brief period
of the "antibiotic era" many bacterial pathogens were able to acquire
the mechanisms allowing them to withstand the selective pressure of antibiotics.
And finally, the field and microcosm studies allowed monitoring HGT events in
situ. In this chapter, a brief overview of the milestones of mobile genetic
elements (MGEs) research is given, followed by discussion of the conceptual
framework development. Then the occurrence and diversity of MGEs as well as
the frequencies of HGT in terrestrial, aquatic, intestinal and biofilm communities
are described. The role of environmental factors that may affect MGE-mediated
HGT in these ecosystems is also discussed.
Chapter 7
What Maintains Plasmids Among Bacteria?
Francisco Dionisio, Teresa Nogueira, Luís M. Carvalho, Helena Mendes-Soares,
Sílvia C. M. Mendonça, Iolanda Domingues, Bernardino Moreira and
Ana M. Reis
The ubiquity of plasmids in nature contrasts with our ability to understand
their maintenance. Despite the ability of plasmids to transfer across different
bacterial taxonomic groups and to carry useful genes to bacterial cells, it
is unclear which factors are responsible for plasmid maintenance among bacterial
populations. In this review, we present several hypotheses aiming at explaining
plasmid existence: efficiency of self-transfer, advantageous genes, transitory
derepression of conjugative pili synthesis, compensatory mutations, the existence
of amplifier strains, positive epistasis between chromosomal mutations and plasmids,
selective sweeps, frequent cross-species transfer, as well as three types of
social interactions (exploitation avoidance in the production of public goods,
pathogen- or parasite-mediated harmful behavior, biofilm formation). These hypotheses
imply that plasmids and their hosts are adaptable to variable conditions and
even that plasmids can be irreplaceable under particular circumstances.
Chapter 8
Identification of Mobile Genetic Elements in Metagenomes
Peter Mullany and Adam P. Roberts
Mobile genetic elements are discrete segments of nucleic acid that can translocate
from one part of the genome to another, and in the case of conjugative elements
between genomes in different cells. The vast majority of our knowledge of mobile
genetic elements is derived from experimentation on cultivable bacteria and
is therefore incomplete. In this chapter we will discuss the methods available
for identifying and isolating these elements from metagenomic samples.
Chapter 9
Horizontal Gene Transfer and Recombination in the Evolution of Antibiotic Resistance
Genes
Miriam Barlow, Jared Caywood, Serena Lai, Joshua Finley and Chad Swanlund
Recombination is a mechanism that leads to variation in antibiotic resistance
genes. We review its importance in the recently emerged nosocomial pathogen
Acinetobacter baumannii, where Horizontal Gene Transfer (HGT) and recombination
are major sources of variation for resistance phenotypes. We also present our
results focusing on the plasmid borne genes of blaCTX-M, ampC and qac. These
results show that random point mutations are not the only major source of variants
among the plasmid borne genes, but that homologous recombination is a major
contributor of gene variants that can likewise add and remove resistance phenotypes
from bacterial populations. Further studies of HGT and recombination are therefore
important to determine how their effects can be manipulated to control the occurrence
of resistance.
© 2025 Axón Librería S.L.
2.149.0