Wikipedia:Reference desk/Archives/Science/2015 September 29

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September 29

Spider ID

Could someone help to identify this spider? Taken on a ceiling in living room in Warsaw, Poland. Even just genus or family would be appreciated, the spider's length is about 3,5 cm. Brandmeister^talk 08:46, 29 September 2015 (UTC)

It's an orb-web spider and possibly a male from the small abdomen, but there are many possibilities. Mikenorton (talk) 09:37, 29 September 2015 (UTC)

Yeah. Too many possibilities. It's way too blurry to identify reliably unfortunately. If there's a web nearby and it's the classic spiral in a disc, then it's an orb-weaver. If the web is "cobwebby", then it's not. If there's no web, it's probably a male, scurrying to find a female before winter (pedipalps don't seem to be evident in the photo, but it's thin enough to be a typical male of most spider species).

Judging from the leg stance, though, I'd also say it's an orb weaver. Or at least any of the web-building spiders. If it's an orb-weaver, my guess would be a missing sector spider (Zygiella x-notata) or a male gray cross spider (Larinioides sericatus note that our article of the latter species is outdated and under the wrong name). Both commonly build their webs in human structures and has ranges that include Poland. They have striped legs and are around the size you described (I'm assuming 3.5 cm describes the legspan, rather than the length of the body).

If it's not an orb-weaver, then it could be any of the other common web-building synanthropic spiders of Theridiidae or Nesticidae (cobweb spiders and scaffold web spiders, respectively), e.g. the triangulate cobweb spider (Steatoda triangulosa), though spiders from both families are typically smaller than the length you described. Note that all of these are just guesses and does not take into account spiders that don't actually live in houses. It may have just gotten in from somewhere else.-- OBSIDIAN†SOUL 11:57, 29 September 2015 (UTC)

Extraterrestrial life

With the recent discovery of water in Mars, a lot of media raises the discussion of the possibility of the existence of extraterrestrial life there. There are many reports around that describe the things that may be need for that, such as liquid water. There's of course the reminder that, if there is life in Mars, it may only be as unicellular organisms, and not as "little green men". But that raised a question, that goes one step beyond Mars: which would be the requirements (even if only speculated at this point) for the presence of multicellular organisms on a planet, and not just unicellular ones? Cambalachero (talk) 17:05, 29 September 2015 (UTC)

I'd think it comes down to a question of quantity and time. That is, the more (single-celled) organisms you have on a planet, for a longer period of time, the more likely multi-celled organisms are to evolve. Temperature may also play a role, as a planet that's always warm will have faster chemical reactions and subsequently faster reproduction rates of single-celled organisms and thus faster evolution. So, multi-cellular organisms might evolve on Mars, but take much longer because of conditions there. StuRat (talk) 18:07, 29 September 2015 (UTC)

It goes beyond that. We don't know that the concept of a "cell" would necessarily apply to all life - and whether the terms "multicellular" or "single-celled" would even have meaning for extraterrestrial life is impossible to know until we get some under the microscope to see. SteveBaker (talk) 19:32, 29 September 2015 (UTC)

It's life, Jim, but not as we know it, not as we know it, not as we know it, it's life, Jim, but not as we know it, not as we know it, Jim --Trovatore (talk) 19:38, 29 September 2015 (UTC)

"Not as we know it, Captain." WHAAOE. Tevildo (talk) 21:16, 29 September 2015 (UTC)

More twin questions

Seeing the question on twins above reminded me of a question I have. My best friend is a twin. Or at least she thought she was until earlier this year when her mother died, and the family secret came out. It seems that her father got her mother and her mother's sister pregnant at the same time and the two babies were born a day or so apart. Both babies were raised by her father and her biological mother's sister as twins. (Confused yet?) My question is, what is the heredity of these two babies? How much shared genetics do they have? It seems too glib to say "100%" as the mothers are different women, albeit sisters. --TammyMoet (talk) 17:27, 29 September 2015 (UTC)

To simplify "same father and two sisters for mothers", right ? Full siblings (including twins as long as they aren't identical twins) are 50% related on average, cousins are 25% related on average. So, I'd think 37.5% related, not counting mutations and other minor effects.

BTW, wouldn't their birth certificates have different mothers and birth dates listed ? StuRat (talk) 18:11, 29 September 2015 (UTC)

Beware, you lucked into the right answer for the wrong reasons! Normal first cousins don't have 25% coefficient of relationship, it takes a double first cousin to get that close. You get a double first cousin when siblings pair up with siblings. Double first cousins are related as closely as half siblings or uncles/nephews, all at 25%. Normal first cousins (whose four parents are all unrelated) have coefficient of relationship of only 12.5%. All this info is given quite clearly in the table at Coefficient_of_relationship#Human_relationships. SemanticMantis (talk) 18:55, 29 September 2015 (UTC)

"Normal first cousins (whose four parents are all unrelated)". How can they be cousins if none of their parents are related ? StuRat (talk) 19:59, 29 September 2015 (UTC)

Sorry, that was nonsensical, I've struck it out now. I was just trying to distinguish "normal" first cousins from the other cases where there are paths of relation in addition to the common way where two people each have one parent who are siblings with each other. SemanticMantis (talk) 21:42, 29 September 2015 (UTC)

Assuming the two mothers were not identical twins...that would dramatically change the picture since the two daughters would now be genetically similar to fraternal twins - which would better explain the entire confusion. SteveBaker (talk) 14:31, 30 September 2015 (UTC)

They are 3/4 siblings, and also first cousins, sometimes called sibling cousins. They can call themselves "horizontal 3/4 siblings" to distinguish from the case where the consanguinity of the non-shared parents comes from a parental relation rather than a sibling relation. Your friend and her 3/4 sister do indeed have a Coefficient_of_relationship that is 37.5%. Terminology and other info at Sibling#3.2F4_sibling. SemanticMantis (talk) 18:39, 29 September 2015 (UTC)

Thank you all for this, and StuRat - they do indeed. In the UK you can have a short form birth certificate or a long form birth certificate, and among the "mother"'s effects they found the long form certificate for both "twins" - which indeed gave the game away. This had been a really well-kept secret for 56 years (although I have to say my friend suspected for a long time she was actually the daughter of her aunt, based on family resemblance). Oh what a tangled web we weave. --TammyMoet (talk) 17:42, 30 September 2015 (UTC)

So how did she get through 56 years of her life without ever seeing her birth certificate ? Isn't that required for anything there, like job applications or weddings ? StuRat (talk) 18:14, 30 September 2015 (UTC)

• You know, "3/8" is more concise and more meaningful in this context than "37.5%". The latter may be false precision, as the ratio is only the expected share of genes in common. (Approximately 46% of my cats are on my desk right now. The other one is heavier.) —Tamfang (talk) 22:56, 1 October 2015 (UTC)

Synthesizing acetone from urine

Let's say you're out in the woods and for some reason you need acetone. Is it possible to synthesize it from your urine if you stop eating for over 24 hours and are in a state of ketosis? 18:16, 29 September 2015 (UTC)

If you're willing to settle for trace quantities of acetone mixed in with your breath, I suppose; but it's not a serious way to make it in meaningful amounts. A woods-expedient method would probably start with Acetone–butanol–ethanol fermentation, but I still think it will look like more lab than woods by the time you have it running properly. Wnt (talk) 18:38, 29 September 2015 (UTC)

Maybe worth mentioning that some uses of acetone are also uses of urine, e.g. both can be used as a light solvent and cleaner. Urine#Uses has some other cases, tanning might be a useful one for surviving in the wild. SemanticMantis (talk) 18:43, 29 September 2015 (UTC)

If the OP is a normal male, the only reason he would be going into the woods is to introduce his girlfriend the wood fairies. So if he suddenly needs (?) some acetone, all he needs to do is rifle through her hand-bag for her nail polish remover! On the other hand, if the OP is a female Goth, all she need to do is rifle through her boyfeind's hand-bag for his nail polish remover.--Aspro (talk) 20:13, 29 September 2015 (UTC)

...unless said significant-other has run out of nail polish remover and is unreasonably unwilling to experiment with using urine as a solution. SteveBaker (talk) 14:27, 30 September 2015 (UTC)

Amount of acetone from urine will be small. Your urine contains 3 ketone bodies in proportions 20% acetoacetic acid, 2% acetone and 78% beta-hydroxybutyric acid. When talking about acetone in urine, one usually means the equivalent amount of acetone for the three together. Most urine tests only measure acetoacetic acid and assume the other two present in normal proportions.

This book mentions an increase of acetoacetic acid from 0.05 mM/day to 11 mM/day after 8 days fasting. beta-hydroxybutyric acid goes up to 77mM/day.

Acetoacetic acid decomposes into CO₂ and acetone, heating speeds up the process. There's no simple way to turn the beta-hydroxybutyric acid into acetone. So you have 11 mM, and assuming normal proportions, there's already one tenth that amount acetone in the urine, or 12mM total. Molar mass of acetone is 58 g/mol and density 0.79 g/cm³, giving 0.012*58 = 0.7 gram or 0.7/0.79 = 0.89 ml per day, which can be separated by fractional distillation, since acetone and water don't form an azeotrope...

There are better acetone sources in the woods. For example, with distillation tools and calcium hydroxide you could dry distill wood to produce acetic acid, distill it into calcium hydroxide solution, yielding calcium acetate, which when heated produces acetone. Was the main production process used before the first world war. Ssscienccce (talk) 21:21, 30 September 2015 (UTC)

Discussing MyD88

Hello, I'm a third-party editor of research papers and an author has written "We performed immunohistochemical staining with a MyD88 antibody ..." and I don't know how MyD88 is expressed out loud, so I don't know whether to correct the indefinite article to 'an MyD88 antibody' or keep it as is. I've been reading it as "My-dee-eighty-eight" but maybe it's "em-why-dee-eighty-eight" in which case I will correct the article. Any help is appreciated. Wolfgangerl (talk) 20:56, 29 September 2015 (UTC)

We have an article at MYD88, suggesting that maybe the 'y' should be capitalized. The string name comes from the term myeloid, suggesting that your first reading is probably how some people pronounce it. But some people may also pronounce it according to your second reading. Here's [1] a video of a guy presenting a research conference talk involving MYD88 - at a skim I can't find him pronouncing it, but if you watch the whole 12 minutes he probably says it at some point (youtube is often a great resource for finding how expert scientists pronounce weird names!). You can ask your authors how they pronounce it or punt to the journal office, but I think the sentence as written is fine. SemanticMantis (talk) 21:30, 29 September 2015 (UTC)

Experts may expand the abbreviation to "Myeloid differentiation primary response gene 88". Google Books have both "a" and "an", so writers disagree. Lower case "y" is more common than Wikipedia's upper case. Dbfirs 21:42, 29 September 2015 (UTC)

Have to disagree with the choice of letter case: Myd88 . Think that maybe, we on WP have it wrong this time. MyD88 makes more sense. Should the article name be corrected?--Aspro (talk) 21:45, 29 September 2015 (UTC)

Yes, I think it should be corrected. Does that mean moving it over the redirect? I've left a question on the talk page. Dbfirs 22:22, 29 September 2015 (UTC)

See Gene nomenclature which AFAIK is correct and also deals with "expansion" issues somewhat. If you have some idea where this particular paper is going to be submitted, you may want to check, what, if any, nomenclature rules they have.

As our article says, standard nomenclature is for human gene symbols to be entirely uppercase, whether it's sonic hedgehog or cytotoxic T-lymphocyte-associated protein 4. Others have different conventions, mice genes have the first letter upper case for example. I'm not aware of any convention which follows the full name. That would be confusing for various reasons, including the fact as our article mentions the symbols are intended to be independent.

Protein symbols (our article appears to be about the protein rather then the gene, as does the OP) have sometimes differing rules, more commonly they're entirely in uppercase, but also not always again dependent on species. they also don't generally use italics. But again, I'm not aware of many cases where the follow the name for capitalisation however.

As for wikipedia articles, I'm not sure whether we follow the human symbol name or what. I'm sure this must be covered in some MOS, or if not a previous discussion. It may be all upper case is generally used, because quite a few including humans use all upper case for the protein names.

The earlier source does use MyD88 as do a number of others [2] [3] and some of the source titles in our articles (which I assume are correct).

It may be that at the time the protein was first described the conventions were not well established. Or it was described and researched by people who don't or didn't. Or in journals which don't or didn't follow such capitalisation conventions. I believe the protein name capitalisation conventions are perhaps somewhat less followed, possibly because they mostly arose after people began to consider how to deal with gene symbol conventions.

Notably this protein seems to be of interest to those involved in public health research, who I believe may be less likely to follow such conventions (our article mentions how they don't generally follow italic conventions) than most other molecular biologists. Particularly Drosophila researchers, who probably need them to avoid confusion over capitilisation given their tendency to come up with weird names.

It's possible a common name argument could be made for MyD88, but I would suggest checking the MOS or other conventions first.

Nil Einne (talk) 23:26, 29 September 2015 (UTC)

Good points; even our MYD88 article is inconsistent in typographical style, writing 'Myd88tm1a' for the corresponding mouse model when naming the corresponding International_Knockout_Mouse_Consortium lines. It seems to me that the OP has no uncontested right or wrong choices. This is presumably why s/he earns a paycheck for this type of work :) SemanticMantis (talk) 00:55, 30 September 2015 (UTC)

If this is professional work, I'd say there's no substitute for talking to someone who works in the field: perhaps one of the authors whose work is referenced in the paper you're editing. Alternatively, you could assume that the author of the paper you're editing knows how she pronounces the abbreviation and used the correct form of the article. --174.88.134.156 (talk) 22:58, 29 September 2015 (UTC)

• MyD88 is one of the proteins I work on, it's pronounced My D 88, not M Y D 88. Both the capitalisation and the use of 'a', rather than 'an' is correct. Fgf10 (talk) 11:14, 30 September 2015 (UTC)

Thanks User:Fgf10. Would you support the changing of our current article name to MyD88 and getting a redirect of MYD88 to it? The capitalization is great when doing a lot of data entry onto a data base, as it saves having to shift case on the keyboard all the time. Yet, for our article name the MyD88 formate seams more appropriate. Otherwise, we will just keep going round in circles as to how to pronounce these proteins correctly.--Aspro (talk) 15:09, 30 September 2015 (UTC)

The capitalization is tricky, because different species have different conventions and Wikipedia generally lumps them all together. Orthology is itself tricky because it is rarely absolute; there tend to be crucial little differences that evolve from one species to the next, and it is possible at times that there are actually two orthologues, one more diverged than the other, so that philosophically it is not even a 1-to-1 relationship, even though that is what BLAST shows (but I haven't checked that is the case here, and it usually is 1-to-1). Or the gene could have become duplicated, the two copies diverged in function, then later each species lost a different one... So if we wanted to be very precise we would have one article for the human protein, one for the mouse, maybe a couple more for the RNAs that produce each, then throw in some more species.... but we're not. I think most of our articles use all capitals as is the common human convention for proteins. In any case I generally would prefer to avoid such picayune adjustments to an article structure which is really not that well rooted. Wnt (talk) 16:48, 30 September 2015 (UTC)

You're right of course, I was probably too succinct in my awnser. I work in human tissue and that's what I've always heard it as in there. And don't even get me started on the human bias in the anatomical/biochemical/genetic articles on here! Most of the time non-humans aren't even mentioned! But that's a rant for a different time and place. Amusingly, MyD88 is a positive exception to this. Fgf10 (talk) 17:03, 30 September 2015 (UTC)

Does penicillin have sulfa

I need to know form a doctor as my doctor said it does not have sulfa but wikipedia says it has sulfur witch is sulfa — Preceding unsigned comment added by Rigsofrods (talk • contribs) 23:51, 29 September 2015 (UTC)

You should discuss your concerns with your physician. Penicillin contains sulfur, but it is not a Sulfa drug. A Sulfa drug contains a sulfonamide group. Not all drugs that contain sulfur are Sulfa drugs. Wikipedia does not call penicillin a Sulfa drug, because it isn't a Sulfa drug. - Nunh-huh 00:16, 30 September 2015 (UTC)