jack@citcom.UUCP (Jack Waugh) (08/14/87)
Which species have mitochondria? Do mitochondria always have their own DNA and hence genetic line independent of nuclear DNA? In sexually reproducing species, do the mitochondrial genes always come from the mother (I understand that this is the case for humans).
pell@boulder.Colorado.EDU (Anthony Pelletier) (08/15/87)
In article <52@citcom.UUCP> jack@citcom.UUCP (Jack Waugh) writes: >Which species have mitochondria? > >Do mitochondria always have their own DNA and hence >genetic line independent of nuclear DNA? > >In sexually reproducing species, do the mitochondrial >genes always come from the mother (I understand that >this is the case for humans). I might start by suggesting you check a decent biology text for the details (such as Mol. Bio. Of The Cell: Alberts, Bray, Lewis, Raff, Roberts et. al.). But the simple answers: All eukariotes have mitochondria. This includes any multicellular organism and alot of unicellular ones such as yeast and cilliates. Loosely speaking, those organisms that do not have mito's are bacteria. All mitochondria thus studied have their own DNA. All gene-products of the mitochondrial genome are used in the mito. But far from all the proteins used in the mito come from there. Most are encoded in the nucleus, made in the cytoplasm and transported to the mitochondria. I believe that in all cases known, sexually-produced offspring get their mitochondria from one parent or the other. This is true of chloroplast DNA as well. The phrase "from their mother" might not apply. It would be hard to come up with a good reason to call one yeast "male" and the other "female." In many metazoans, the female gamete is usually much larger than the male gamete. This may explain why the "mother's" mitochondia are inhereted. But it does not explain the cases where two cells of more-or-less identical size fuse to form a zygote and the offspring inheret mito DNA from only one of them (as is the case for Chlamydomonas--an algae). there are models to explain this. Happy reading. Tony Pelletier Molecular etc. Biology Boulder, Co. 80309-0347
dd@beta.UUCP (08/16/87)
In article <52@citcom.UUCP>, jack@citcom.UUCP (Jack Waugh) writes: > Which species have mitochondria? Anything with a nucleus that wants to live off of oxygen. > Do mitochondria always have their own DNA and hence > genetic line independent of nuclear DNA? It varies by kingdom. Plants have relatively large >150KB mito genomes; mammaliam mitochondria have 16 KB or so genomes. The difference is that more of the proteins required for the mitochrondria are encoded in the mammalian case. There was an interesting article in Science in 1984 by Lewin that discussed gene migration from the mitochondrial genome to the host. The proteins that remain encoded in the mammalian mt genome are very hydro- phobic and do not cross membranes well. Also remember that mt are descended from procaryotes, and there are at least two separate lines of descent (plants vs. everything else). > In sexually reproducing species, do the mitochondrial > genes always come from the mother (I understand that > this is the case for humans). In some fungi the mt genomes fuse when the zygote is formed and the mt inherited by the daughter cells is therefore recombinant. In mammals the mt come from the egg, and only very, very rarely does the mt from the sperm make it into the zygote. dan davison/theoretical biology/t-10 ms K710/los alamos national lab/NM 87545
werner@aecom.YU.EDU (Craig Werner) (08/17/87)
In article <1910@sigi.Colorado.EDU>, (Anthony Pelletier) writes: > > But the simple answers: All eukaryotes have mitochondria. This includes > any multicellular organism and alot of unicellular ones such as yeast and > cilliates. I, too, used to believe that all Eukaryotes have mitochondria. In fact, Entamoeba species, including Entamoeba histolytica (which infects 10-20% of the world's human population) and Entamoeba coli (whose presence means that all first references to everyone's favorite bacteria must be spelled out Escherichia coli to distinguish it from this E. coli) lack mitochondria. That's right Entamoeba are Eukaryotes that lack mitochondria. Their nucleus qualifies them as bona fide Eukaryotes, and as soon as he gets his act together, Neil Rothstein will be sequencing E. histolytica ribosomal RNA in order to place it in proper perspective. There are also several strains of yeast that seem to do without mitochondria very nicely. Yes, the above is a nit-pick, but it's nature's fault, not mine. -- Craig Werner (future MD/PhD, 3 years down, 4 to go) werner@aecom.YU.EDU -- Albert Einstein College of Medicine (1935-14E Eastchester Rd., Bronx NY 10461, 212-931-2517) "Versatility is no crime, but it is a source of adrenaline."
gagen@bgsuvax.UUCP (kathleen gagen) (08/17/87)
In article <52@citcom.UUCP>, jack@citcom.UUCP (Jack Waugh) writes: > Which species have mitochondria? So far as is known, all cellular organisms have mitochondria. Virus lack them. > > Do mitochondria always have their own DNA and hence > genetic line independent of nuclear DNA? Yes. > > In sexually reproducing species, do the mitochondrial > genes always come from the mother (I understand that > this is the case for humans). To the best of my knowledge, this is always the case for organisms for which one parent can be called the "mother". There are, however, organisms in which the gametes that fuse are of similar size (some of the blue-green algae, for example) and unicellular organisms, such as yeast, that fuse. I am not familiar with blue-green algae. However, in yeast two haploid cells (cells with one set of chromosomes), an "a" and an "alpha" cell fuse to form a diploid cell (with two sets of chromosomes) referred to as an "a-alpha" cell. This a-alpha cell contains mitochondria from both parent cells. This cell or its genetically identical progeny can then sporulate to produce four daughter cells: two "a" cells and two "alpha" cells. To the best of my knowledge, the mitochondria of these cells can be a mixture of that from the original "a" and "alpha" cell that fused to form their parent. -- Kathleen Pausic Gagen ...!cbosgd!osu-eddie!bgsuvax!gagen Dept. of Biological Sciences gagen@research!.bgsu.edu Bowling Green State University gagen%bgsu.csnet@csnet-relay.arpa Bowling Green Ohio 43403 gagen%andy.bgsu.edu@csnet-relay.csnet
dd@beta.UUCP (Dan Davison) (08/19/87)
In article <1273@aecom.YU.EDU>, werner@aecom.YU.EDU (Craig Werner) writes: > In article <1910@sigi.Colorado.EDU>, (Anthony Pelletier) writes: > > > > But the simple answers: All eukaryotes have mitochondria. This includes > > I, too, used to believe that all Eukaryotes have mitochondria. In > fact, Entamoeba species, including Entamoeba histolytica (which infects There was also a report in Nature earlier this year (senior author was the Godfather of rRNA, Carl Woese) about the microsporidia Vairimorpha necatrix, which not only doesn't have mt, its rRNA looks more like a eubacteria's than a eucaryote's. Also see the section on eucaryotic phylogeny in the June Microbiological Reviews article "Bacterial Evolution", also by The Godfather. It's excellent. dan davison/theoretical biology/t-10 msk710/LANL/Los Alamos, NM 87545 dd@lanl.gov (arpa) uucp: still don't know...sorry...check the header...
lonetto@phri.UUCP (Michael Lonetto) (08/20/87)
In article <9059@beta.UUCP> dd@beta.UUCP (Dan Davison) writes: > >eubacteria's than a eucaryote's. Also see the section on eucaryotic >phylogeny in the June Microbiological Reviews article "Bacterial >Evolution", also by The Godfather. It's excellent. > >dan davison/theoretical biology/t-10 msk710/LANL/Los Alamos, NM 87545 >dd@lanl.gov (arpa) uucp: still don't know...sorry...check the header... I just wanted to put in a further plug for the Microbilogical Reviews article. Anyone at all interested in evolution, phylogeny, origin of life or bacterial physiology should read it. The article is very broad in scope, very conceptual in tone and very long on explanation. It is by no means necessary to be an expert in the field, or even a biologist, to understand it. All that is needed is a knowlege of basic molecular biology (DNA, RNA, protein synthesis) and genetics (simple heredity) which could have been obtained in a basic undergraduate biology course, or even an advanced high school course. The author carefully and clearly explains all methodology used and how the data was obtained to generate the phylogenetic trees proposed (uncertainties and abiguities are also pointed). In addition the writing is very clear and forthright and the organization is excellent. Overall this is one of the best written scientific papers I have seen in years. It is also a very useful reference for those of us who must occassionally wander the maze of bacterial physiology, as it is presently the most complete reference of what is related to what. -- Michael Lonetto UUCP:(allegra!phri!lonetto) Dept of Applied Genetics Public Health Research Institute, 455 1st Ave, NY, NY 10016