Horizontal

1
Horizontal gene transfer
?
The transfer of genetic information from one
genome to another.
2
Conjugation transfer of DNA from one organism
to another by means of a plasmid.
3
Transformation uptake of free DNA from the
environment.
4
Transduction transfer of DNA from one organism
to another by a bacteriophage.
5
Retrotransduction?
6
An organism into which genetic information from a
different organism has been incorporated as a
stable part of its genome is a transgenic
organism.
green fluorescent protein (GFP)
Aeqorea victoria
ANDi
7
Orthology Paralogy Xenology
8
Horizontal gene transfer is suspected when there
is a discrepancy between gene phylogeny and
species phylogeny, in particular when the tree
reflects geographical proximity rather than
phylogenetic affinity.
9
Patchy phylogenetic distribution
Aedes aegypti
10
cyanobacteria chloroplast (Fe-SOD)
nucleus
cytoplasm (CuZn-SOD)
bacteria mitochondria (Mn-SOD)
SOD superoxide dismutase
11
Leiognathus daura
Photobacterium leiognathi (CuZnSOD)
12
(No Transcript)
13
Crown Gall Disease
14
Agrobacterium tumefaciens
15
(No Transcript)
16
(No Transcript)
17
P
M
P elements hybrid dysgenesis
Margaret Kidwell
18
P elements were not found in any D. melanogaster
strains collected before 1950, and collections
made subsequently showed increasing frequencies
of P with decreasing age.
North and South America
Europe, Africa, Middle East
Australia, Far East
19
Two hypotheses 1. Most D. melanogaster strains
in nature carry P elements, but they tend to lose
them in the laboratory. 2. P elements were
recently introduced into D. melanogaster
populations in nature.
20
The recent acquisition hypothesis is supported
by 1. P strains that have been monitored in the
lab for 15 y were never observed to lose P. 2.
There is a geographical cline in the temporal
appearance of P in nature. 3. There is evidence
for horizontal gene transfer.
21
(No Transcript)
22
Species tree
P-element tree
23
P element
Drosophila melanogaster
Drosophila willistoni
24
(No Transcript)
25
Proctolaelaps regalis
26

• Conditions for horizontal P-element transfer
• two Drosophila females from the donor and the
  recipient species must lay eggs in proximity to
  one another
• (2) the recipient egg must be less than 3 hours
  old (lt 512 cells)
• (3) the germline of the recipient embryo must
  incorporate a complete copy of P
• (4) the receiving embryo must survive the biting
  injuries

Marilyn A. Houck
27
type-C virogene
28
(No Transcript)
29
(No Transcript)
30
Informational genes Genes involved in
replication, transcription, reverse
transcription, and translation. Operational
genes All others.
31
The complexity hypothesis
informational
operational
32
Genes move within the genome and between
genomes. Genetic Mutatis mutandis.
33
Promiscuous DNA
34
Einat Hazkani-Covo et al.
Mitochondrial-sequence invasions into the nuclear
genome
35
Numts (nuclear mitochondrial DNA sequences) are
a type of promiscuous DNA, i.e., nuclear
sequences of mitochondrial origin.
pronounced new mights
36
The transfer of functional genes from the
mitochondria to the nucleus is thought to have
has stopped in evolution after the emergence of
animals (1,000 MYA).
37
The reason is thought to be the differences
between the nuclear and mitochondrial genetic
codes.
38
The transfer of nonfunctional pieces of
mitochondrial genetic information continues to
this day.
Numts have been found so far in 83 eukaryote
species.
39
Most species whose genomes have been completely
sequenced contain very few numts. Saccharomyces
cerevisiae 17 numts Caenorhabditis elegans 3
numts Drosophila melanogaster 3
numts Plasmodium falciparum 3 numts
40
In the human genome we find 1,000 numts total
length 831 Kb 0.02 of the nuclear genome
41
Numts Evolutions misplaced witnesses
42
(No Transcript)
43
Junk DNA
Domestic
Imported