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©2001 Timothy G. Standish John 1:12 12But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:

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Presentation on theme: "©2001 Timothy G. Standish John 1:12 12But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:"— Presentation transcript:

1 ©2001 Timothy G. Standish John 1:12 12But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:

2 ©2001 Timothy G. Standish Endosymbiosis and the Origin of Eukaryotes: Are mitochondria really just bacterial symbionts? Timothy G. Standish, Ph. D.

3 ©2001 Timothy G. Standish Outline Mitochondria - A very brief overview Endosymbiosis - Theory and evidence Archaezoa - Eukaryotes lacking mitochondria Gene expression - Mitochondrial proteins coded in the nucleus Mitochondrial genetic codes Gene transport - Mitochondria to nucleus Conclusions

4 ©2001 Timothy G. StandishMitochondria Mitochondria are organelles found in most eukaryotic organisms. The site of Krebs cycle and electron transport energy producing processes during aerobic respiration Are inherited only from the mother during sexual reproduction in mammals and probably all other vertebrates. Because of their mode of inheritance genetic material found in mitochondria appears to be useful in determining the maternal lineage of organisms.

5 ©2001 Timothy G. Standish Mitochondria Mitochondria Matrix Inter membrane space Inner membrane Outer membrane mtDNA

6 ©2001 Timothy G. Standish Extranuclear DNA Mitochondria and chloroplasts have their own DNA This extranuclear DNA exhibits non-Mendelian inheritance Recombination is known between some mt and ctDNAs Extranuclear DNA may also be called cytoplasmic DNA Generally mtDNA and ctDNA is circular and contains genes for multimeric proteins, some portion of which are also coded for in the nucleus Extranuclear DNA has a rate of mutation that is independent of nuclear DNA Generally, but not always, all the RNAs needed for transcription and translation are found in mtDNA and ctDNA, but only some of the protein genes

7 ©2001 Timothy G. StandishmtDNA Mitochondrial DNA is generally small in animal cells, about 16.5 kb In other organisms sizes can be more than an order of magnitude larger Plant mtDNA is highly variable in size and content with the large Arabidopsis mtDNA being 200 kb. The largest known number of mtDNA protein genes is 97 in the protozoan Riclinomonas mtDNA of 69 kb. “Most of the genetic information for mitochondrial biogenesis and function resides in the nuclear genome, with import into the organelle of nuclear DNA-specified proteins and in some cases small RNAs.” (Gray et al.,1999)

8 ©2001 Timothy G. Standish Endosymbiosis

9 Origin of Eukaryotes Two popular theories presupposing naturalism seek to explain the origin of membrane bound organelles: 1Endosymbiosis to explain the origin of mitochondria and chloroplasts (popularized by Lynn Margulis in 1981) 2Invagination of the plasma membrane to form the endomembrane system

10 ©2001 Timothy G. Standish Origin of Eukaryotes Two popular theories presupposing naturalism seek to explain the origin of membrane bound organelles: 1Endosymbiosis to explain the origin of mitochondria and chloroplasts (popularized by Lynn Margulis in 1981) 2Invagination of the plasma membrane to form the endomembrane system Mitochondria

11 ©2001 Timothy G. Standish Origin of Eukaryotes Two popular theories presupposing naturalism seek to explain the origin of membrane bound organelles: 1Endosymbiosis to explain the origin of mitochondria and chloroplasts (popularized by Lynn Margulis in 1981) 2Invagination of the plasma membrane to form the endomembrane system Nucleus Endoplasmic Reticulum Golgi Body Mitochondria Chloroplast

12 ©2001 Timothy G. Standish Origin of Eukaryotes Two popular theories presupposing naturalism seek to explain the origin of membrane bound organelles: 1Endosymbiosis to explain the origin of mitochondria and chloroplasts (popularized by Lynn Margulis in 1981) 2Invagination of the plasma membrane to form the endomembrane system Chloroplast Endoplasmic Reticulum Nucleus Golgi Body Mitochondria

13 ©2001 Timothy G. Standish How Mitochondria Resemble Bacteria Most general biology texts list ways in which mitochondria resemble bacteria. Campbell et al. (1999) list the following: Mitochondria resemble bacteria in size and morphology. They are bounded by a double membrane: the outer thought to be derived from the engulfing vesicle and the inner from bacterial plasma membrane. Some enzymes and inner membrane transport systems resemble prokaryotic plasma membrane systems. Mitochondrial division resembles bacterial binary fission They contain a small circular loop of genetic material (DNA). Bacterial DNA is also a circular loop. They produce a small number of proteins using their own ribosomes which look like bacterial ribosomes. Their ribosomeal RNA resembles eubacterial rRNA.

14 ©2001 Timothy G. Standish How Mitochondria Don’t Resemble Bacteria Mitochondria are not always the size or morphology of bacteria: –In some Trypanosomes (i.e., Trypanosoma brucei) mitochondria undergo spectacular changes in morphology that do not resemble bacteria during different lifecycle stages (Vickermann, 1971) –Variation in morphology is common in protistans, “Considerable variation in shape and size of the organelle can occur.” (Lloyd, 1974, p 1) Mitochondrial division and distribution of mitochondria to daughter cells is tightly controlled by even the simplest eukaryotic cells

15 ©2001 Timothy G. Standish How Mitochondria Don’t Resemble Bacteria Circular mtDNA replication via D loops is different from replication of bacterial DNA (Lewin, 1997, p 441). mtDNA is much smaller than bacterial chromosomes. Mitochondrial DNA may be linear, examples include: Plasmodium, C. reinhardtii, Ochromonas, Tetrahymena, Jakoba (Gray et al., 1999). Mitochondrial genes may have introns which eubacterial genes typically lack (these introns are different from nuclear introns so they cannot have come from that source) (Lewin, 1997 p 721, 888). The genetic code in many mitochondria is slightly different from bacteria (Lewin, 1997).

16 ©2001 Timothy G. Standish Archaezoa

17 Giardia - A “Missing Link”? The eukaryotic parasite Giardia has been suggested as a “missing link” between eukaryotes and prokaryotes because it lacks mitochondria (Friend, 1966; Adam, 1991) thus serving as an example of membrane invagination but not endosymbiosis Giardia also appears to lack smooth endoplasmic reticulum, peroxisomes and nucleoli (Adam, 1991) so these must have either been lost or never evolved

18 ©2001 Timothy G. Standish A Poor “Missing Link” As a “missing link” Giardia is not a strong argument due to its parasitic life cycle which lacks an independent replicating stage outside of its vertebrate host –Transmission is via cysts excreted in feces followed by ingestion –As an obligate parasite, to reproduce, Giardia needs other more derived (advanced?) eukaryotes Some other free-living Archaezoan may be a better candidate

19 ©2001 Timothy G. Standish Origin of Giardia Giardia and other eukaryotes lacking mitochondria and plastids (Metamonada, Microsporidia, and Parabasalia ) have been grouped by some as “Archaezoa” (Cavalier- Smith, 1983; Campbell et al., 1999 p 524-6) This name reflects the belief that these protozoa split from the group which gained mitochondria prior to that event. The discovery of a mitochondrial heat shock protein (HSP60) in Giardia lamblia (Soltys and Gupta, 1994) has called this interpretation into question. Other proteins thought to be unique to mitochondria, HSP70 (Germot et al., 1996), chaperonin 60 (HSP60) (Roger et al., 1996; Horner et al., 1996) and HSP10 (Bui et al., 1996) have shown up in Giardia’s fellow Archaezoans

20 ©2001 Timothy G. Standish Origin of Archaezoa The authors who reported the presence of mitochondrial genes in amitochondrial eukaryotes all reinterpreted prevailing theory in saying that mitochondria must have been present then lost after they had transferred some of their genetic information to the nucleus. The hydrogenosome, a structure involved in carbohydrate metabolism found in some Archaezoans (Muller, 1992), is now thought to represent a mitochondria that has lost its genetic information completely and along with that loss, the ability to do the Krebs cycle (Palmer, 1997). Alternative explanations include transfer of genetic material from other eukaryotes and the denovo production of hydrogenosomes by primitive eukaryotes.

21 ©2001 Timothy G. Standish Origin of Archaezoa: Mitochondrial Acquisition

22 ©2001 Timothy G. Standish Origin of Archaezoa: Gene Transfer and Loss mtGenes Lost genetic material

23 ©2001 Timothy G. Standish Origin of Archaezoa: Option 1 - Mitochondrial Eukaryote Production

24 ©2001 Timothy G. Standish Origin of Archaezoa: Option 2 - Mitochondrial DNA Loss/ Hydrogenosome production Hydrogenosome

25 ©2001 Timothy G. Standish Origin of Archaezoa: Option 2A - Mitochondria/Hydrogenosome Loss

26 ©2001 Timothy G. Standish Gene Transport

27 ©2001 Timothy G. Standish “All in all then, the host nucleus seems to be a tremendous magnet, both for organellar genes and for endosymbiotic nuclear genes.” Palmer, 1997

28 ©2001 Timothy G. Standish Steps in Mitochondrial Acquisition: The Serial Endosymbiosis Theory Fusion of Rickettsia with either a nucleus containing Archaezoan or an archaebacterium Rickettsia DNA reduction/transfer to nucleus Ancestral eukaryote (assuming a nucleus) Primitive eukaryote Host Cell

29 ©2001 Timothy G. Standish Steps in Mitochondrial Acquisition: The Hydrogen Hypothesis Fusion of proteobacterium with an archaebacterium Hydrogen producing proteobacterium DNA reduction/transfer nucleus production Hydrogen requiring archaebacterium Ancestral eukaryote With nucleus containing both archaebacterium and proteobacterium genes

30 ©2001 Timothy G. Standish Metamonada Hydrogenosome/ mitochondria loss Hydrogenosome/ mitochondria loss Microsporidia, and Parabasalia mtDNA loss mtDNA loss mtDNA loss mtDNA lossPhylogeny EukaryotaBacteria Origin of Life Gene transfer Cell fusion

31 ©2001 Timothy G. Standish Timing of Gene Transfer Because gene transfer occurred in eukaryotes lacking mitochondria, and these are the lowest branching eukaryotes known: Gene transfer must have happened very early in the history of eukaryotes. The length of time for at least some gene transfer following acquisition of mitochondria is greatly shortened. No plausible mechanism for movement of genes from the mitochondria to the nucleus exists although intraspecies transfer of genes is sometimes invoked to explain the origin of other individual nuclear genes.

32 ©2001 Timothy G. Standish Gene Expression

33 ©2001 Timothy G. Standish Cytoplasmic Production of Mitochondrial Proteins Mitochondria produce only a small subset of the proteins used in the Krebs cycle and electron transport. The balance come from the nucleus As mitochondrial genomes vary spectacularly between different groups of organisms, some of which may be fairly closely related, if all came from a common ancestor, different genes coding for mitochondrial proteins must have been passed between the nucleus and mitochondria multiple times

34 ©2001 Timothy G. Standish The Unlikely Movement of Genes Between Mitochondria and the Nucleus Movement of genes between the mitochondria and nucleus seems unlikely for at least two reasons: 1 Mitochondria do not always share the same genetic code with the cell they are in 2 Mechanisms for transportation of proteins coded in the nucleus into mitochondria seem to preclude easy movement of genes from mitochondria to the nucleus

35 ©2001 Timothy G. Standish Cytoplasm Nucleus Protein Production Mitochondria and Chloroplasts G AAAAAA Export Chloroplast Mitochondrion

36 ©2001 Timothy G. Standish Cytoplasm Nucleus ChloroplastMitochondrion Protein Production Mitochondria and Chloroplasts

37 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inter membrane space Inner membrane Outer membrane

38 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inter membrane space Inner membrane Outer membrane Leader sequence binding receptor MLSLRQSIRFFKPATRTLCSSRYLL P +ADP ATP P +ADP ATP

39 ©2001 Timothy G. Standish Matrix Inner membrane Outer membrane MLSLRQSIRFFKPATRTLCSSRYLL Inter membrane space Leader sequence binding receptor Protein Production Mitochondria Peptidease cleaves off the leader

40 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inner membrane Outer membrane MLSLRQSIRFFKPATRTLCSSRYLL Inter membrane space Leader sequence binding receptor

41 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inner membrane Outer membrane Inter membrane space Leader sequence binding receptor

42 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inner membrane Outer membrane Inter membrane space Leader sequence binding receptor Hsp60 Chaperones

43 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inner membrane Outer membrane Inter membrane space Leader sequence binding receptor Mature protein

44 ©2001 Timothy G. Standish Yeast Cytochrome C Oxidase Subunit IV Leader MLSLRQSIRFFKPATRTLCSSRYLL Polar Polar Non-polar R Y P L T C S R L S T I K P R F A F M R Q L L S S This leader does not resemble other eukaryotic leader sequences, or other mtProtein leader sequences. Probably forms an  helix This would localize specific classes of amino acids in specific parts of the helix There are about 3.6 amino acids per turn of the helix with a rise of 0.54 nm per turn First 12 residues are sufficient for transport to the mitochondria Neutral Non-polar Polar Basic Acidic Recognized by peptidase?

45 ©2001 Timothy G. Standish Yeast Cytochrome C1 Leader MFSNLSKRWAQRTLSKTLKGSKSAAGTATSYFE- KLVTAGVAAAGITASTLLYANSLTAGA-------------- Cytochrome c functions in electron transport and is thus associated with the inner membrane on the intermembrane space side Cytochrome c1 holds an iron containing heme group and is part of the B-C1 (III) complex C1 accepts electrons from the Reiske protein and passes them to cytochrome c Neutral Non-polar Polar Basic Acidic Second cut First cut Uncharged second leader sequence signals for transport across inner membrane into the intermembrane space Charged leader sequence signals for transport to mitochondria

46 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inter membrane space Inner membrane Outer membrane

47 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inter membrane space Inner membrane Outer membrane Leader sequence binding receptor P +ADP ATP P +ADP ATP Peptidease cleaves off the leader

48 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inter membrane space Inner membrane Outer membrane Leader sequence binding receptor

49 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inter membrane space Inner membrane Outer membrane Leader sequence binding receptor

50 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inter membrane space Inner membrane Outer membrane Leader sequence binding receptor

51 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inter membrane space Inner membrane Outer membrane Leader sequence binding receptor

52 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inter membrane space Inner membrane Outer membrane Leader sequence binding receptor Peptidease cleaves off the second leader

53 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inter membrane space Inner membrane Outer membrane Leader sequence binding receptor

54 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inter membrane space Inner membrane Outer membrane Leader sequence binding receptor

55 ©2001 Timothy G. Standish Protein Production Mitochondria Matrix Inter membrane space Inner membrane Outer membrane Leader sequence binding receptor Mature protein Note that chaperones are not involved in folding of proteins in the inter membrane space and that they exist in a low pH environment

56 ©2001 Timothy G. Standish Alternative Mechanism There are actually two theories about how the leader operates to localize mtproteins in the inter membrane space: 1. The first, as shown in the previous slides, involves the whole protein moving into and then out of the matrix 2. The alternative theory suggests that once the first leader, which targets to the mitochondria is removed, the second leader prevents the protein from ever entering the matrix so it is transported only into the inter membrane space.

57 ©2001 Timothy G. Standish Nuclear DNA Building a Minimally Functional Nuclear Mitochondrial Gene Given that a fragment of DNA travels from the mitochondria to the nucleus and is inserted into the nuclear DNA Additional hurdles may include: Resolution of problems resulting from differences between mitochondrial and nuclear introns Resolution of problems resulting from differences between mitochondrial and nuclear genetic codes Mitochondrial Gene Signal Sequence Control Sequence Mitochondrial GeneSignal SequenceControl Sequence

58 ©2001 Timothy G. Standish Additional Requirements In addition to addition of appropriate control and leader sequences to mitochondrial genes, the following would be needed: Recognition and transport mechanisms in the cytoplasm Leader sequence binding receptors Peptidases that recognize leader sequences and remove them

59 ©2001 Timothy G. Standish No Plausible Mechanism Exists If genes were to move from the mitochondria to the nucleus they would have to somehow pick up the leader sequences necessary to signal for transport before they could be functional While leader sequences seem to have meaningful portions on them, according to Lewin (1997, p 251) sequence homology between different sequences is not evident, thus there could be no standard sequence that was tacked on as genes were moved from mitochondria to nucleus Alternatively, if genes for mitochondrial proteins existed in the nucleus prior to loss of genes in the mitochondria, the problem remains, where did the signal sequences come from? And where did the mechanism to move proteins with signal sequences on them come from?

60 ©2001 Timothy G. Standish Mitochondrial Genetic Codes

61 ©2001 Timothy G. Standish Variation In Codon Meaning Lack of variation in codon meanings across almost all phyla is taken as an indicator that initial assignment must have occurred early during evolution and all organisms must have descended from just one individual with the current codon assignments Exceptions to the universal code are known in a few single-celled eukaryotes, mitochondria and at least one prokaryote Most exceptions are modifications of the stop codons UAA, UAG and UGA serine Stop Common Meaning Stop Candida A yeast Euplotes octacarinatus A ciliate Paramecium A ciliate Organism Tetrahymena thermophila A ciliate leucine cysteine glutamine Modified Meaning CUG UGA UAA UAG Codon/s UAA UAG glutamine Stop Mycoplasma capricolum A bacteria tryptophanUGA Neutral Non-polar, Polar

62 ©2001 Timothy G. Standish Variation in Mitochondrial Codon Assignment UGA/G=Stop Universal Code Cytoplasm/ Nucleus Plants Yeast/ Molds Platyhelmiths Echinoderms Molluscs Insects Vertebrates UGA=Trp AGA/G=Ser AUA=Met CUN=Thr AUA=Ile AAA=Asn Nematodes NOTE - This would mean AUA changed from Ile to Met, then changed back to Ile in the Echinoderms UGA must have changed to Trp then back to stop Differences in mtDNA lower the number of tRNAs needed AAA must have changed from Lys to Asn twice

63 ©2001 Timothy G. Standish Problems Resulting From Differences in Genetic Codes Changing the genetic code, even of the most simple genome is very difficult. Because differences exist in the mitochondrial genomes of groups following changes in the mitochondrial genetic code, mitochondrial genes coding differently must have been transported to the nucleus. These mitochondrial genes must have been edited to remove any problems caused by differences in the respective genetic codes.

64 ©2001 Timothy G. Standish Behe Goes Beyond Moustraps In an essay entitled “Intelligent Design theory as a Tool for Analyzing Biochemical Systems,” Michael Behe encourages researchers to go beyond “simple” biochemical systems and to apply Intelligent Design theory to more complex sub-cellular systems. He specifically poses the question: “Given that some biochemical systems were designed by an intelligent agent, and given the tools by which we came to that conclusion, how do we analyze other biochemical systems that may be more complicated and less discrete than the ones we have so far discussed?” (Behe, 1998 p 184)

65 ©2001 Timothy G. Standish No Modern Examples Unfortunately for Margulis and S.E.T. [the serial endosymbiotic theory], no modern examples of prokaryotic endocytosis or endosymbioses exist... She discusses any number of prokaryotes endosymbiotic in eukaryotes and uses Bdellovibrio as a model for prokaryotic endocytosis. Bdellovibrios are predatory (or parasitoid) bacteria that feed on E. coli by penetrating the cell wall of the latter and then removing nutrient molecules from E. coli while attached to the outer surface of its plasma membrane. Although it is perfectly obvious that this is not an example of one prokaryote being engulfed by another Margulis continually implies that it is. P.J. Whitfield, review of “Symbiosis in Cell Evolution,” Biological Journal of the Linnean Society 18 [1982]:77-78; p 78)

66 ©2001 Timothy G. StandishConclusions Presence of mitochondrial genes in nuclear DNA reduces the window of time available for mitochondrial acquisition in eukaryotes. Understanding the structure of mitochondrial genes in the nucleus and how they are expressed makes the transfer of genes from protomitochondria to the nucleus appear complex. Differences between mitochondrial genetic codes and nuclear genetic codes adds to the complexity of gene transfer between mitochondria and nucleus. As molecular data accumulates, the endosymbiotic origin of mitochondria appears less probable.

67 ©2001 Timothy G. Standish Laboratory

68 M PCR of Human mtDNA Single 460 bp mtDNA control region fragment which is polymorphic in sequence, but not size Single nucleotide polymorphisms are common in the mtDNA control region. These can be used to identify remains and determine maternal linage due to the maternal inheritance of mitochondria

69 ©2001 Timothy G. Standish 16,569 bp Human mtDNA 15,971 Left primer 16,411 Right primer 0 1,260 Control region, D-Loop, Or hypervariable region 0 tRNA Pro 440 bp fragment

70 ©2001 Timothy G. Standish The Amplified Segment gaaaaagtct ttaactccac cattagcacc caaagctaag Attctaattt aaactattct ctgttctttc atggggaagc agatttgggt accacccaag tattgactca cccatcaaca accgctatgt atttcgtaca ttactgccag ccaccatgaa tattgtacgg taccataaat acttgaccac ctgtagtaca taaaaaccca atccacatca aaaccccctc cccatgctta caagcaagta cagcaatcaa ccctcaacta tcacacatca actgcaactc caaagccacc cctcacccac taggatacc Acaaacctac ccacccttaa cagtacatag Tacataaagc catttaccgt acatagcaca ttacagtcaa atcccttctc Gtccccatgg atgacccccc tcagataggg gtcccttgac caccatcctc cgtga

71 ©2001 Timothy G. Standish The Amplified Segment 5’ ctttaactccaccattagcacccaaagctaag… 5’ ttaactccaccattagca 3’ 3’ …tcagataggggtcccttgaccaccatcctccgt 3’ ggaactggtggtaggagg 5’ Following are what I suspect the primers to be: –Right Primer 5’ ggaggatggtggtcaagg 3’ TM 58.80 –Left Primer 5’ ttaactccaccattagca 3’ TM 49.71

72 ©2001 Timothy G. Standish The Amplified Segment Following are what I suspect the primers to be: –Right Primer 5’ ggaggatggtggtcaagg 3’ TM 58.80 –Left Primer 5’ ttaactccaccattagca 3’ TM 49.71 5’ ttaactccaccattagca 3’ 3’ ggaactggtggtaggagg 5’ cc 3’ GC clamp at 3’ end? This would up TM and stabilize 3’ end of the primer 5’ ctttaactccaccattagcacccaaagctaag… …tcagataggggtcccttgaccaccatcctccgt 3’

73 ©2001 Timothy G. Standish Human mtDNA Genes Genes in human (for which numbers are given) and other mammalian mitochondria can be divided into three groups: tRNA genes - 22 rRNA genes - 2 Protein coding genes - 13 Total genes = 37 All protein coding genes are involved in respiration Aside from the coding portion of genes there is very little additional DNA except in the approximately 1,200 bp control region

74 ©2001 Timothy G. Standish Location Strand LengthGeneProduct 3307..4263+ 318ND1NADH dehydrogenase subunit 1 4470..5513+ 347ND2NADH dehydrogenase subunit 2 5904..7445+ 513COX1cytochrome c oxidase subunit I 7586..8269+ 227COX2cytochrome c oxidase subunit II 8366..8572+ 68 ATP8ATP synthase F0 subunit 8 8527..9207+ 226ATP6ATP synthase F0 subunit 6 9207..9989+ 260 COX3cytochrome c oxidase subunit III 10059..10406+ 115ND3NADH dehydrogenase subunit 3 10470..10766+ 98ND4LNADH dehydrogenase subun 4L 10760..12139+ 459ND4 NADH dehydrogenase subunit 4 12337..14148+ 603ND5NADH dehydrogenase subunit 5 14149..14673- 174ND6NADH dehydrogenase subunit 6 14747..15883+ 378CYTBcytochrome b

75 ©2001 Timothy G. Standish


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