7 captures

13 Jun 2010 - 12 Oct 2017

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2010	2016	2017

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About this capture

COLLECTED BY

Collection: Wikipedia Outlinks March 2016

Crawl of outlinks from wikipedia.org started March, 2016. These files are currently not publicly accessible. Properties of this collection. It has been several years since the last time we did this. For this collection, several things were done: 1. Turned off duplicate detection. This collection will be complete, as there is a good chance we will share the data, and sharing data with pointers to random other collections, is a complex problem. 2. For the first time, did all the different wikis. The original runs were just against the enwiki. This one, the seed list was built from all 865 collections.

TIMESTAMPS

Molecular Genetics

Facts

The plant symbiont Bradyrhizobium japonicum has two glutamine synthetase genes, one similar to those found in other bacteria, the other 50% identical to the enzymes from higher plants. When protein sequences encoded by archaeal genomes are used to search protein sequence databases for similar sequences, some sequences have their best match with sequences from eubacteria. The opposite is also true (ref1, ref2, ref3). There are even a few cases where one sequence segment of a protein with an origin in one kingdom is attached to a segment with an origin in another kingdom (ref).

Kanamycin, streptomycin and tetracycline resistance genes found in gram negative and gram positive bacteria are essentially identical in nucleotide sequence.

A plasmid, RSF1010, can successfully be conjugated from E.coli to cyanobacteria, actinomycetes, Agrobacterium and other bacteria.

Interpretations

• Sequence comparisons suggest recent horizontal transfer of many genes among diverse species including across the boundaries of phylogenetic "domains". Thus determining the phylogenetic history of a species can not be done conclusively by determining evolutionary trees for single genes.
• Genes can move across species barriers by conjugation.
• Symbiotic relationships may play a role in cross kingdom transfers of genes.
• The wide transfer of genes that must have occurred naturally weakens the argument that human intervention through genetic engineering is placing genes where they have never been before.

Further Information

• Bacteria of the genus Agrobacterium have developed a special mechanism that allows transfer of genes from the bacterium to higher plant chromosomes.
• Phylogenetic analyses indicate that Drosophila P elements have been transferred horizontally (Ref).
• Horizontal transfer is also called lateral gene transfer and may account for 10 to 50% of all the genes in a bacterial or archaeal genome.

This is page 334 of Molecular Genetics by Ulrich Melcher, © 1997, 1998, 2001