From owner-cellbiol@net.bio.net Wed Feb 19 22:00:00 1997 Path: biosci!ihnp4.ucsd.edu!news1.ucsd.edu!usenet From: Kevin Shreder Newsgroups: bionet.cellbiol Subject: responses to the largest cell on Earth question Date: Thu, 20 Feb 1997 09:11:59 -0700 Organization: Antibody Resource Page Lines: 132 Message-ID: <330C77CF.410C@znet.com> NNTP-Posting-Host: chegood10.ucsd.edu Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 2.02 (Macintosh; I; PPC) I recently posted a question inquiring about what the largest cell on Earth was and I got several interesting responses. I suppose there was such variety because I was vague - what exactly does "large" mean? The heaviest, the longest, the most voluminous? In any sense, here are just some of the many responses I got: The largest cell on earth would be an egg of one of the larger birds eg emu, ostrich, casuari (sp?), no other type of cell has the needs of storage that an egg does, and only a large animal can produce eggs the size of an emu egg. Perhaps a news group on birds would be more informative? Plantwise it would probably be a giant algae, the name escapes me for the moment, but there is an algae used in experiments on plant physiology becaue of it's large size, principly for rates of cytoplasmic streaming. Now I have it - there are two algae "Chara" and "Nitella" The longest cell would be a nerve cell of the giant squid. The largest surfaces area would, I guess, belong to a 'skin' cell, but I have no idea which species has it. I hope this is of some use to you. WT Depends what you are after - the largest cell in a multicellular organism or the largest cell of any type! For the latter, the alga Valonia would be somewhere near the mark but I'm sure there are bigger - memory is a bit deficient after 7 years of retirement but have a look in a good Plant Physiology text since early ion and nutrient exchange work used them for hypodermic extraction of internal fluids in the sorts of quantities required in early days! The 1969(??!!) edition of Salisbury & Ross "Plant Physiology" gives Chara, Halicystis and Nitella spp as also being large celled but the Nitellas I used to handle were not as large as Valonia (cm rather than mm!!). Later editions were more process orientated and fascinating byways such as this on size seemed to have been lost. Best success but I hope you can authenticate a few measurements!!! I may be able to give one example of larger cells than those you listed: A marine diatom which is unicellular plant leaving in ocean, its name is Ethmodiscus rex. It length is about 0.9 mm, and width about 0.5 mm. SL Further to my earlier response - having been a botanist and your query being in a plant Newsgroup I never gave a thought to animal cells!! However, one of my old books I did a bit of subsequent searching in was a BIOLOGY text and mentioned the yolk cell (not cells) of an ostrich egg as an example of 'large', and human nerve cells several feet long (+ the speculation of elephant cells being larger!). I think the ostrich egg yolk, if the facts bear up, might well be in the running!!! JB I believe that the largest cell on Earth is "plasmodium of true slime mold", for example, Physarum polycephalum. This multi nucleated web like cell may spread over one square meter. YK If you *want* to call a seed a single cell (I'm not sure if they qualify), there one species of cocoanut that weighs something like 40 pounds. Otherwise, it might be an ostrich egg, or, if semi-fossil eggs count, there's some kind of preserved egg from Aussie-land that is rather larger than ostriches. Every now and again, one turns up in decent condition. AJH The answer to this may well be Caulerpa, a green alga, that has essentially one body cavity in its 6 or more foot body, although multitudinous nuclei. It has morphological definition of organs, so it is remarkable whether it fits the requirements of your definition or not. The answer to this may well be Caulerpa, a green alga, that has essentially one body cavity in its 6 or more foot body, although multitudinous nuclei. It has morphological definition of organs, so it is remarkable whether it fits the requirements of your definition or not. SDH Several years ago, there was a news article in Science (maybe Nature) about a certain type of cell -- some sort of fungus, I think -- which lives underground in the root system of certain trees in north-central North America (I think). This cell, according to the article, spreads over a very large area, I mean like several hundred feet! Sorry I can't remember more, and I couldn't find it in Medline (not surprising). Maybe someone else recalls hearing about this. JA If I am not mistaken, it is a ciliate and close relative of Euglena. I believe it was a new species discovered in Australia several years ago. It is almost discernible with the naked eye. LAF I think that your suggestion of a nerve cell could be correct. I remember reading that individual neurons of large mammals like an elephant or giraffe can grow to 3 meters in length. You might want to check an encyclopedia on that. Good luck. MC I'm not sure, but check into acellular slime molds (myxomycota). These are multinucleate, monostromatic, and can get quite large. J This is an interesting question. An ovum is definitely 'large' but not that large. If a multinucleated coenocyte may be considered as a single cell, then a fungal hypha may be larger than an ovum. However, the fibrous cells that make up the supporting matrix of the vuscular bundles of certain plants ( eg. Gossypum sp. and certain types of hemp) are known to be several cm's long. But, these cells would eventually lose their nuclei and so be essentially dead. H I may be mistaken, but I think the largest cell in volumn is the alga called acetabulum. I seem to remember a reference to it some few years ago. The longest is probably a nerve cell of one of the larger mammals, perhaps cetaceans. KBJ .