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Topic: Bacterial conjugation

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	Bacterial Gene Swapping in Nature
		Conjugation was the first mechanism of gene transfer studied extensively as a way bacteria might disseminate genetic material in nonlaboratory arenas.
		Thus, even if they travel to a new bacterial host, they do not become a stable part of that host's genome; chromosomes are invariably copied and distributed to new generations of bacterial cells whenever a parent cell reproduces itself, but plasmids are not reproduced consistently when cells divide.
		Although conjugation was the first mechanism of bacterial gene transfer to be studied extensively in the environment, it was not the earliest to be identified.
	www.genethik.de /gene_swapping.htm (3153 words)

	Genetic Exchange Utilizing Microbial Donors or Vectors
		Most bacterial cells need to be at a particular stage in their growth cycle or under a particular growth regimen in order to be transformed.
		Conjugation begins with the extrusion of a sex pilus; the tip of the sex pilus adheres to the outer membrane of Gram-negative cell walls.
		A bacterial cell containing a F plasmid integrated into the bacterial DNA is termed a Hfr (high frequency of recombination) cell.
	www.kcom.edu /faculty/chamberlain/Website/Lects/Genexch.htm (2249 words)

	Conjugation - Wikipedia, the free encyclopedia
		A conjugate in algebra is similar to a complex conjugate, but is used to rationalize the denominator of a fraction.
		This includes bacterial conjugation, which takes place without fusion; conjugation in ciliates, which involves fusion of nuclei but not cells; and conjugation in certain algae and fungi, which involves fusion of cells but not filaments.
		Conjugate quantities, in quantum physics, are observables that are linked by the Heisenberg uncertainty principle, such as position and momentum.
	en.wikipedia.org /wiki/Conjugation (281 words)

	Bacterial Recombination (Site not responding. Last check: 2007-11-05)
		The contact between the cells is via a protein tube called an F or sex pilus, which is also the conduit for the transfer of the genetic material.
		Genetic transfer in conjugation is from an F+ cell to an F- cell, and the genetic material transferred is the F factor itself.
		This is because the F factor is not homologous to the DNA in the bacterial chromosome.
	www.emunix.emich.edu /~rwinning/genetics/bactrec2.htm (365 words)

	Rediscovering Biology - Online Textbook: Unit 5 Emerging Infectious Diseases
		Conjugation is another means of gene transfer in many species of bacteria (Fig.
		On rare occasions an F-plasmid may become integrated in the chromosome of its bacterial host, generating what is known as an Hfr (high frequency of recombination) cell.
		Lateral gene transfer is a potent evolutionary force that can create diversity within bacterial species (See the Microbial Diversity unit.) As genes for virulence factors and antibiotic resistance spread between and among bacterial populations, scientists are realizing how integral these mechanisms are to the emergence of novel pathogens.
	www.learner.org /channel/courses/biology/textbook/infect/infect_7.html (675 words)

	Charles T. Esmon, Ph.D.
		This mechanism of gene transfer, or conjugation, allows bacterial cells to transfer genes directly to other bacterial cells, and in some cases to plant, fungal, and animal cells as well.
		Conjugation among bacteria is responsible for the epidemic spread of antibiotic resistance and even plays a direct role in some forms of pathogenesis.
		Conjugative plasmids encode about 2-dozen proteins that assemble at the cell surface into a specific structure, or nanomachine, that mediates DNA transfer from a donor to a host or recipient cell.
	www.omrf.org /omrf/Research/06/SilvermanPLay.asp (481 words)

	BioInteractive's Animation Console
		Above the chromosome of one bacterium (bacterium A) is a plasmid, a portion of the bacterial genome that is separate from the chromosome.
		Plasmids are not connected to the main bacterial chromosomes and replicate independently.
		Conjugation is one of the mechanisms by which bacteria can aquire new genetic material and, as a result, new traits.
	www.hhmi.org /biointeractive/animations/conjugation/conj_print.htm (615 words)

	MCDB 2150 -- LECTURE 10
		Conjugation: Bacterial conjugation can be viewed as a primitive form of sex, in which a cell from a donor strain injects DNA into a recipient cell, where it can undergo recombination and become part of the recipient's genome (figures 7.13 and 7.14).
		Bacterial strains with integrated F factors are referred to as Hfr strains (for "high frequency of recombination").
		When single bacteriophage are plated on a lawn of bacterial cells on an agar plate, the first burst initiates a second round of infection, leading to more bursts and a growing circle of bacterial lysis, which is known as a plaque (figure 7.28).
	www.colorado.edu /MCDB/MCDB2150Fall/notes99/99L10.html (2542 words)

	Study Guide 5b
		Bacterial Transformation: Free DNA is transferred to a recipient strain of bacteria and brings about a genetic change.
		Conjugation between Hfr and F- strains involve transfer of part or all of the bacterial chromosome.
		b) During conjugation mediated by the integrated F factor, the flanking bacterial chromosomal sequence is replicated by rolling circle replication initiated from the F plasmid oriT, and the bacterial chromosome is transferred into the F- recipient with OriT leading.
	www.biology.duke.edu /bio103l/StudyGuides/SG5/study5b.html (1123 words)

	Viral and Bacterial Genetics [MT Dorak]
		In conjugation, a direct contact between a male (carrying a fertility factor, or F+) and a female (F-) bacteria results in a one-way genetic material transfer (from male-to-female).
		During conjugation in E.coli, the F factor (which is a conjugative plasmid) is not lost from the donor as it is only one of the strands of the plasmid that has been transferred.
		Conjugation is the exception to the rule that bacteria reproduce asexually.
	members.tripod.com /~dorakmt/genetics/notes10.html (1444 words)

	Bacteria - Crystalinks
		These limitations can be avoided by the use of a chemostat, which maintains a bacterial culture under steady-state conditions by the continuous addition of nutrients and the removal of waste products and cells.
		Conjugation increases the genetic variability of bacterial populations and facilitates the emergences of antibiotic resistance.
		The ability to transfer DNA is not ubiquitous in the bacterial kingdom, so all bacteria also rely on none transfer methods to diversify their DNA.
	www.crystalinks.com /bacteria.html (1563 words)

	Bacterial conjugation - Wikipedia, the free encyclopedia
		Bacterial conjugation is the transfer of genetic material between bacteria through cell-to-cell contact.
		Bacterial conjugation is often incorrectly regarded as the bacterial equivalent of sexual reproduction or mating.
		In order to perform conjugation, one of the bacteria, the donor, must play host to a conjugative or mobilizable genetic element, most often a conjugative plasmid.
	en.wikipedia.org /wiki/Bacterial_conjugation (464 words)

	Conjugation
		Conjugation is conservative -- donor retains a copy of the plasmid after transfer, indicating that plasmid replication occurs during conjugation.
		The host range for conjugation can be determined by the range of hosts that can serve as recipients for DNA transfer or the range of hosts that the plasmid can replicate within.
		The host range for conjugation is typically determined by the ability of the plasmid to replicate within a specific host.
	www.sci.sdsu.edu /~smaloy/MicrobialGenetics/topics/plasmids/conjugation.html (809 words)

	Bacterial conjugation (Site not responding. Last check: 2007-11-05)
		Divide large volumes of gravies, bacterial conjugation are the gastrointestinal tracts.
		You are bacterial conjugation the bacterial conjugation leading causes of bacterial conjugation bacterial and mycotic diseases home in ontario.
		bacterial conjugation monocytogenes is a number of bacterial and staphylococcus aureus produces a doctor immediately.
	bacterial.mooreasafari.com /bacterial-conjugation.html (759 words)

	biology - Bacterial conjugation (Site not responding. Last check: 2007-11-05)
		Bacterial conjugation is the often regarded as the bacterial equivalent of sexual reproduction or mating; however it is not actually sexual as it does not involve the fusing of gametes and the creation of a zygote, it is merely the exchange of genetic information.
		In order to perform conjugation, one of the bacteria has to carry an F-plasmid, the other one must not.
		The F-plasmid (also called F-factor) is an episome (a plasmid that can integrate itself into the bacterial chromosome by genetic recombination) of about 100 kb (kilo base pairs) length.
	www.biologydaily.com /biology/Bacterial_conjugation (388 words)

	CHAPTER #9: MICROBIAL EXCHANGE OF GENETIC MATERIAL (Site not responding. Last check: 2007-11-05)
		Transgenic plants containing "bacterial genes" that make a protein toxic to certain insect pathogens are currently growing around the world.
		The number of bacteriophage in a liquid can be easily counted by diluting the phage cultures through a series, mixing a standard amount of each dilution with a suspension of phage host and spreading the mixture on a plate of media.
		The ability of phage to carry bacterial DNA between bacteria was discovered in 1952.
	www.slic2.wsu.edu:82 /hurlbert/micro101/pages/Chap9.html (3173 words)

	Conjugation of Plasmid R1
		Bacterial conjugation is one of the major processes by which genetic material is transferred between bacteria.
		Plasmid R1 is a conjugative resistance plasmid belonging to the incompatibility class IncFII.
		Högenauer (1991) Repression and derepression of conjugation of plasmid R1 by wild-type and mutated finP antisense RNA.
	www.kfunigraz.ac.at /imkwww/CONJUG.HTML (865 words)

	Bacterial Recombination
		Bacteria, since they are usually haploid, cannot have their chromosomes mapped by the same techniques as eukaryotes (For a reminder of how this works, see the module on linkage and mapping).
		If this cell undergoes conjugation with an Hfr cell that is a+, b+ (in other words, wild type), the F- cell should undergo gene conversion to a+, b+ when both of those genes have been transferred by conjugation.
		These bacteria would then be tested for gene conversion (for example, if the mutations rendered the F- bacteria auxotrophic, the bacteria could be tested by growing them on minimal medium, or minimal medium supplemented with the necessary nutrient required because of one or the other mutation).
	www.emunix.emich.edu /~rwinning/genetics/bactrec3.htm (486 words)

	Bacterial Conjugation Protein MobA Mediates Integration of Complex DNA Structures into Plant Cells -- Bravo-Angel et ...
		Bacterial and plant media were prepared as previously described (24, 34).
		A 38 base-pair segment of DNA is required in cis for conjugative mobilization of broad host-range plasmid R1162.
		The conjugal intermediate of plasmid RSF1010 inhibits Agrobacterium tumefaciens virulence and VirB-dependent export of VirE2.
	jb.asm.org /cgi/content/full/181/18/5758 (5370 words)

	News in Science - Bacteria mate with animal cells - 19/11/2001
		The new research, however, shows that DNA can be passed on to mammalian cells via bacterial plasmids through a process known as conjugation, in which the two cells temporarily fuse.
		She suggests that bacterial conjugation may provide a future vector, or carrier, for gene therapy.
		Conjugation is one way bacterial genes may have entered the human genome in ancient times, said Dr Hall, although if this occurred, there would need to have been a further transfer of DNA from the plasmid into the chromosome.
	www.abc.net.au /science/news/stories/s418799.htm (565 words)

	Gene Transfer between Salmonella enterica Serovar Typhimurium inside Epithelial Cells -- Ferguson et al. 184 (8): 2235 ...
		Bacterial conjugation is probably the primary mechanism of antibiotic
		Transfer of conjugative plasmids and bacteriophage lambda occurs in the presence of antibiotics that prevent de novo gene expression.
		Bacterial secreted proteins are required for the internalisation of Campylobacter jejuni into cultured mammalian cells.
	jb.asm.org /cgi/content/full/184/8/2235 (4416 words)

	UT Scientists Pinpoint Channel in Bacterial DNA Transfer System
		This injection process, known as bacterial sex, or conjugation, is one of three ways that bacteria obtain new DNA.
		"Scientists have studied bacterial conjugation mechanisms for over 50 years and have a general understanding of how these machines function," Christie said, "but until our study there was no knowledge of the secretion channel, that is, the route through which DNA is delivered across the bacterial cell's surface."
		They obtain new DNA three ways: through bacterial sex; by taking up DNA molecules from their surroundings (transformation); or infection from viruses (transduction).
	publicaffairs.uth.tmc.edu /Media/newsreleases/nr2004/bacterial_dna.html (613 words)

	The Joshua Lederberg Papers: The Development of Bacterial Genetics
		The very low incidence of mating, together with his technique of studying the genetic products of bacterial conjugation (namely, inherited nutritional requirements and drug resistance) in culture medium, prevented Lederberg from examining the physiology and kinetics, the stages and dynamics, of the mating process in detail.
		When new ways of photographing the stages of the mating process with the electron microscope were developed in the 1950s, they revealed that during conjugation the two bacteria of the mating pair lay side by side and formed a connecting bridge through which DNA is passed.
		The complexities in Lederberg's linkage map could not be resolved until the Irish bacteriologist William Hayes reported in 1952 that during conjugation, one partner of the mating pair, the male, acted as a donor, and that the other, the female, acted as recipient.
	profiles.nlm.nih.gov /BB/Views/Exhibit/narrative/bacgen1.html (1908 words)

	MCDB 2150 -- LECTURE 9
		Transformation: Transformation refers to the ability of extracellular DNA to enter a bacterial cell and recombine with the bacterial genome, thereby giving the cell new genetic properties.
		The single strand left behind in the donor and the one that is transferred to the recipient are both converted into double strands, restoring the donor chromosome and generating double stranded donor DNA in the recipient.
		New bacteriophage particles are assembled inside the bacterial cell, and the products of late-acting genes lyse the host cell, giving rise to a "burst" of new bacteriophage particles (figure 7.27).
	www.colorado.edu /MCDB/MCDB2150Fall/notes00/L0009.html (2779 words)

	LAB MANUAL, EXERCISE #14: Conjugation, Bacterial Mating (Site not responding. Last check: 2007-11-05)
		The rare defective phage can however infect another bacterial host, the recipient, and inject the donor's DNA into the recipient cell.
		Conjugation is a major means of spreading resistant genes to sensitive bacterial populations.
		At the conclusion of the mating period, streak a loop-full of the conjugated culture onto the MATE plate; streaking for isolation.
	www.slic2.wsu.edu:82 /micro101/pages/101lab14.html (1080 words)

	Bacterial conjugation and Plasmid stabilisation (Site not responding. Last check: 2007-11-05)
		Conjugation is a unidirectional DNA transfer process involving cell-cell contact.
		This process is catalyzed by relaxases, enzymes that are encoded on conjugative plasmids and most mobilizable plasmids.
		Intergeneric transfer of the Enterococcus faecalis plasmid pIP501 to Escherichia coli and Streptomyces lividans and sequence analysis of its tra region.
	strubi.uni-graz.at /projects/cnj.htm (196 words)

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