Photo cross-post

Mar. 20th, 2026 02:30 am
andrewducker: (Default)
[personal profile] andrewducker


Nice mist on Arthur's Seat this morning.
Original is here on Pixelfed.scot.

Dreamwidth and Icons

Mar. 20th, 2026 06:47 am
soc_puppet: A crude pencil drawing on lined paper of what's supposed to be a dog; the dog's mouth and eyes are on one side of its face, while its snout is on the other. (Gud at Drawings)
[personal profile] soc_puppet posting in [community profile] the_great_tumblr_purge
Buckle in, everyone, this is going to be a long one!

One of the things that has made Tumblr wildly popular with fandom is its unlimited image hosting capacity. Content, Tumblr eventually put limits on, but number of total images (rather than images per post) and size of images? Not so much.

Unfortunately, that's one of the big reasons why Tumblr is basically hemorrhaging money: Because data is expensive, and image data is much more so than text data, mainly because it's a lot more data. That number just goes up with gifs and videos, the former especially being a favorite on Tumblr.

The ways to get money to run a social media site on the internet are basically venture capitol (the investors will want their money back someday, somehow), selling user data (doesn't everyone love ads and hate privacy?), and users directly paying for services (in this economy?).

Dreamwidth started from a foundation of prioritizing privacy and user freedom, and that meant that they compromised on image hosting in order for their users to truly be the main focus of this site. A dedicated user base pays to keep Dreamwidth running, and while there's a price rise on the horizon, we've managed to keep Dreamwidth's doors open with just our own money for sixteen years now.

So what does this have to do with icons? Well, with the limited image hosting options in Dreamwidth's budget, they're one of the main ways we use images at all—and Dreamwidth users make the most of them!

Hold up; what exactly IS an icon? And what do you mean by 'make the most of them'? )

How do I get and upload icons? )

Is that it?

Well, it's everything I can think of, at any rate! But you might have questions that I haven't covered. This is a great place to ask them! I may not have the answers, but odds are decent that someone here will be able to point you in the right direction.

One last favor before I go...

Dreamwidth users, if you've got favorite icons, show them off in the comments! I think it would be great to be able to share examples of just how fun and creative we can get with this medium, and this seems like the perfect opportunity 😉 Reply to your own comment if you have more than one, or to other people if the icon fits, so it's not just a mass of top-level comments.

As for any newcomers, if this post gets enough comments, you may get a chance to try out another one of Dreamwidth's features; at 50 comments, comment threads will collapse to keep loading time down and limit data transfer costs. Towards the topmost comment, at the bottom of the comment below which everything gets folded up, there's a clickable option to Expand the thread. This will open up and display all of the comments below that for you! The thread will collapse back down if you click away, though.

If this post doesn't get that many comments but you still want to try it out, I'd recommend checking the latest post at [site community profile] dw_news. (Incidentally, if you have a Paid account, there's an option to expand all the comment threads at once at the top of the comment section. Pretty neat, yeah?)

Thanks, everyone, and I hope this post was helpful! I'm going to go collapse for a while now 😅

Book Spine Poetry

Mar. 19th, 2026 10:31 pm
lb_lee: Rogan drawing/writing in a spiral. (art)
[personal profile] lb_lee
We keep a little stack of books we're reading on the kitchen table and our roommates noticed that the spines lined up in amusing ways. This was accidental, but then we thought, "what if we did that... ON PURPOSE?"

And today, we trashed our room stacking books to make poems. We hope they amuse you!


Orchard Bees

Mar. 19th, 2026 04:02 pm
bookscorpion: This is Chelifer cancroides, a book scorpion. Not a real scorpion, but an arachnid called a pseudoscorpion for obvious reasons. (Default)
[personal profile] bookscorpion posting in [community profile] common_nature
This morning I went to check out the big insect hotel near the canal and I was just in time to catch a whole bunch of male European orchard bees who I am fairly sure had just hatched (the females will hatch a little later in the year).



Read more... )



Ask LLOG: "(The) OCCUPATION NAME"?

Mar. 19th, 2026 02:25 pm
[syndicated profile] languagelog_feed

Posted by Mark Liberman

From Coby L:

I wonder if you can refer me to a discussion of the appropriateness of the very common omission of "the" when a person's name is preceded by their position or occupation and is not a title or rank (like Professor, Colonel or President). For example, linguist Mark Liberman, writer Stephen King and the like. (In The New Yorker it would almost certainly be "the linguist" etc.)

As regards titles, specifically relating to political positions and used as forms of address, the I have also wondered why some are usually preceded by Mr. or Madam (President, Speaker…) and others are not (Governor, Senator, Prime Minister…). Any insights?

I've got some thoughts and references, but I'll leave this for readers to answer first…

 

TIL: "Sealioning"

Mar. 19th, 2026 12:20 pm
[syndicated profile] languagelog_feed

Posted by Mark Liberman

As Wikipedia explains,

Sealioning […] is a type of trolling or harassment that consists of pursuing people with relentless requests for evidence, often tangential or previously addressed, while maintaining a pretense of civility and sincerity ("I'm just trying to have a debate"), and feigning ignorance of the subject matter. It may take the form of "incessant, bad-faith invitations to engage in debate",[9] and has been likened to a denial-of-service attack targeted at human beings.[10] The term originated with a 2014 strip of the webcomic Wondermark by David Malki, which The Independent called "the most apt description of Twitter you'll ever see".

Although I'm a regular reader of David Malki's Wondermark, and interested in the taxonomy of trolling, I've somehow managed to miss this word. Here's the 9/19/2014 comic:

Wiktionary has an entry for sealioning. There's as yet no entry in Merriam-Webster's (though they list it among the Words We're Watching) or the OED.

There are more historical details in the Know Your Meme entry.

And the most recent Wondermark — "Limit Your Scream Time" — is again relevant to scrolling social media…

home and energy thoughts

Mar. 19th, 2026 07:49 pm
tielan: (AVG - maria 3)
[personal profile] tielan
What if I don't want to run the electricity in my household like a standard Australian household?
 
thinky thoughts )
[syndicated profile] languagelog_feed

Posted by Victor Mair

In part 1 of this post, "The (ir)reality of the MingKwai typewriter" (10/17/25) and many preceding, related posts (see "Selected readings" and the links to which they lead), we saw what a boondoggle and fiasco the Chinese typewriter (especially Lin Yutang's MingKwai) was.  Yet people are still glorifying and extolling the clumsy, clunky, cumbersome Chinese typewriter as though it were leading the IT revolution (when the reality is quite the contrary).  So much hype and sensationalism about the retrograde Chinese typewriter!

The following bilibili video, although in Chinese, will show how complicated and expensive to replicate such a device is:

Remarks by Xinyi Ye:

I just saw this behind-the-scenes video of HTX Studio's Chinese typewriter production. In another interview video, HTX said their studio was experiencing a financial deficit last year [when they made the video attempting to replicate Lin Yutang's MingKwai]. Probably not as bad as what happened to Lin Yutang [who went bankrupt building the MingKwai], but again shows how much investment goes into doing something like this!

It behooves all those who preach the gospel of the MingKwai and related Chinese typewriters to read and take to heart the scholarly critiques in the bibliography below.

 

Selected readings

soc_puppet: A gray masked dumbo rat wearing a Dreamwidth cheerleading outfit and waving red color-matched pompoms (Cheering you on)
[personal profile] soc_puppet posting in [community profile] the_great_tumblr_purge
This is a reproduction of a post I already made on Tumblr, but with that platform's future once again uncertain, I figured it'd be good to copy over here, as well.

Together with figuring out what to even post, one of the things that sucks about moving social media and/or blogging platforms is not knowing if there will be enough activity for you at the new place. Be it from old friends, new friends, or interactive communities, there’s a lot of ways you could find activity at a new place, but finding at least two of those categories can be tricky in itself.

Luckily, Dreamwidth has a few shortcuts for you already!


Adding new people to your reading page and finding new friends:

[community profile] addme: Straight up a place to find new “mutuals” on Dreamwidth, with no particular focus; a good place to start!

[community profile] addme_fandom: Same as above, but with a specific fandom focus! Interested in a particular fandom right now and want more people to talk about it with? Here’s a good place to find fellow fans!

[community profile] findingfriends: Similar to the addme communities but with a more in-depth approach, including things like posting style and what sort of interactions you’re looking for. Takes more brain power than the addme comms, but I imagine that the connections result in a higher level of compatibility.

Newcomers' Introduction and Friending Meme: A very in-depth adding meme, hosted by [community profile] newcomers! Includes a spot near the top for other platforms you're on, so it might be useful for finding Tumblr mutuals.

[community profile] fandomcalendar: This is a community dedicated to announcing fandom events, which can include fandom-specific friending memes. (I’ll be linking this one again later, as well.)


Getting started on Dreamwidth:

[community profile] newcomers: A community dedicated specifically to helping Dreamwdth newcomers find their way around on a new site! I believe it was launched around the time Cohost was being shut down, so a lot of the people there now are Cohost “refugees”, but it’s still a good place to start.

[community profile] the_great_tumblr_purge: A community dedicated specifically to Tumblr refugees, started around the time of the new content restrictions in 2018. If you've got questions specific to being former Tumblr user, this might be a good place to ask them, though Newcomers is also happy to help.

[site community profile] dw_news: The official Dreamwidth news community. I highly recommend following this one and the next one, which will help you keep up with what’s going on around Dreamwidth. DW News typically only posts a few times a year, but maybe that’ll change if a bunch of new users come by...

[site community profile] dw_maintenance: Keep up with the mechanical goings-on at Dreamwidth! If there’s a planned site outage or if DW is updating code, you can find out more here; if there’s something funky going on at Dreamwidth but the site is generally still usable, it’s also a good place to check.

[site community profile] dw_advocacy: Want to know more about how Dreamwidth is fighting for our rights? Follow this community to keep tabs on what bad bills Dreamwidth and NetChoice are battling, and if there's anything you can do to help!


Things to do on Dreamwidth:

[site community profile] dw_community_promo: The official Dreamwidth community for promoting Dreamwidth communities! People will promote new communities here, as well as events going on in established communities. A good place to find out about new things in general.

[community profile] followfriday: A place to share links to check out once a week. Did you find a cool community that you want more people to know about? Link it in the comments here! The host, [personal profile] ysabetwordsmith, shares a themed post every week with posts, events, and communities related to said theme.

[community profile] justcreate: A place where you can talk about things you’re working on. There’s a weekly check-in/reporting post, but sometimes people also organize body doubling sessions and other productivity-boosting things.

[community profile] queerly_beloved: An anti-exclusionist queer space to get together and talk about all things queer, including intersectional matters. Hosts a weekly recommendations thread, but more and other content is very welcome!

[community profile] allbingo: Do you like filling out bingo cards for just about anything? This community is for all things bingo cards, fandom related and otherwise! Put together a bingo card for making mood themes, post topics, or even bird watching (featuring your local feathered friends), and share your results!


Fandom things to do on Dreamwidth:

[community profile] fandomcalendar: I linked this above, and I’m linking it again: Want to know about fandom events that are going on at Dreamwidth? This is a good place to do it! It’ll also fill up your reading page in a hurry; you might be surprised at how many events are going on at Dreamwidth, or are at least connected there!

[community profile] fictional_fans: A community for all fans and fandoms. If you’ve got a post you want to make about fandom in general, or a specific fandom that doesn’t have its own community, this might be a good place to check out.

[community profile] fandom_on_dw: Pretty much the same as above, honestly, but it’s good that there’s more than one place that hosts this kind of thing!


Anything else?

Search Interests: Individuals and communities can have lists of things they’re “interested in”. If more than one person has that thing listed, it may turn into a hyperlink that you can click to find other accounts with! You can also use the Search Interests function pretty much the same way. Simply type “cats” into the search bar, hit enter, and a bunch of accounts that have “cats” listed as an interest will pop up! Click through the various tabs at the top to separate accounts out into individual users, communities, and more.

The Latest Things Page: Literally the latest things posted publicly anywhere on Dreamwidth. There’s a list of commonly used tags at the top, if you want to narrow things down at all, but in the mean time, it can be pretty neat to see what J. Random Dreamwidth User just posted about! This is about the closest Dreamwidth gets to surfing random tags on Tumblr.

The Explore Tab: Useful links for Dreamwidth in general. In addition to linking to the Latest Things Page, it can take you to a random account, the FAQ page, and more! Worth checking out if you’re feeling lost.

Most Useful Communities list, as curated by [personal profile] ysabetwordsmith; this has a lot of other options that I either didn't know about, or didn't feel like I had room to include; this post is already longer than I like to go without a cut tag or two 😅

The comments on the Newcomers' mirror of this post: People in both of these communities are pretty helpful, and that includes sharing their own suggestions in the comments! If you have something specific you're looking for, you might even ask for help here; who knows, we might just have a good lead for you! (Feel free to ask here as well!)


And that’s all I can think of at the moment! This should help you get started at least, and help fill out your reading page a bit.
lb_lee: Rogan drawing/writing in a spiral. (art)
[personal profile] lb_lee
  • Finally finishing the Reverend Alpert book, which has been stalled at around 80% completion for YEARS now
  • Expanding Quick'n'Dirty Plural History into a proper paperback, because the zine sells shockingly well for such a niche subject, we have a lot more info now (though not on the newest slapfights, ha, no, we're talking older, cross-cultural stuff, and spirit marriage/headmate relationship stuff) (if you want us to wade into the hottest new plural communities on Discord or Bsky or what the fuck ever, you're going to have to pay us real money, and in ADVANCE)
  • Finally kicking Rogan's ass into inking Loyal Forever, a comic that involves the muscle car beloved from Crazy Boys Get Money)
  • Expanding Xenogals into a book-length thing, the Mori and Rawlin version of Alter Boys In Love (Xenogals in Love?)
Oh no, all but Loyal Forever are big beefy books. But well, the Xenogals and Plural History ones would replace their floppies, and Reverend Alpert would probably end up a short run anyway.

Uploading Images to Dreamwidth

Mar. 19th, 2026 01:55 am
soc_puppet: A brown hooded rat seen from behind as it is surfing the web at a desktop computer; barely visible on the computer's screen is the Dreamwidth logo (Computer time)
[personal profile] soc_puppet posting in [community profile] the_great_tumblr_purge
Hello again! With Tumblr's latest brush with implosion, it seems the tutorial writing bug has bitten me again. Today, I'm finally going to talk about uploading and sharing images on Dreamwidth!

Dreamwidth has given all users a certain amount of image storage to use: Free users get 500 MB, Paid users get 1.5 GB, and Premium Paid users get 3 GB.

There's two ways to upload images directly to Dreamwidth.

The first option has a fair number of steps, but it's the one I know the most about and the one I'm best able to help with.

Option One )

The second option is to post an image by email, which I have to admit I haven't tried myself yet.

For Option Two, the first thing you need to know here is that it's possible to post to Dreamwidth by email; IIRC, it was [personal profile] silvercat17 who made the tutorial I used to get that set up, but I can't seem to locate it at the moment 😩 I'll edit this post to add in a link if that changes, though! In the mean time, you can check out Dreamwidth's official FAQ entries about how to get it set up over here. If you post an entry by email, you can attach an image as a file to the email, and it will automatically be uploaded to Dreamwidth and included in the post! It won't necessarily have any particular title or description included, though, so you may want to visit Manage Images to edit that.


And those are the basics of uploading images to Dreamwidth! Culturally, Dreamwidth users tend to either share larger images as a thumbnail, or to put them under a cut (Dreamwidth's "Read More"), but otherwise this should cover what you need to know.

But maybe I'm wrong about that! Feel free to ask any questions in the comments of this post, and I'll do my best to clear things up (and then edit the post to include the information). You can also check Dreamwidth's official Media FAQ and see if your question is answered there.

RIP (Read In Progress) Wednesday

Mar. 18th, 2026 03:56 pm
silversea: A dragon reading a book (Reading Dragon)
[personal profile] silversea posting in [community profile] booknook
Happy Wednesday! Are you keeping up with your books?

Books and Bytes

Mar. 18th, 2026 10:02 am
lb_lee: Rogan drawing/writing in a spiral. (art)
[personal profile] lb_lee
Mori: nobody jumps out of bed going, “Good morning world, today I do my TAXES!” with a big smile on their face, but man alive, is it neat to see what sold and what didn’t, when and where.

Read more... )

quick hello-I'm-alive post

Mar. 17th, 2026 10:41 pm
asakiyume: (feathers on the line)
[personal profile] asakiyume
It's been more than a week since I posted! Part of that's just life being busy; part is that [personal profile] osprey_archer is here!

Today we went to Bright Water Bog, swung on a swing, ate some cranberries, and saw ice forming. It was sunny, but a cold wind was blowing, and a few flurries of snow came down.



(We also went to the Smith College Botanical Gardens, but this is a drive-by post! So there's only the one photo.)

(no subject)

Mar. 19th, 2026 12:29 pm
conuly: (Default)
[personal profile] conuly
Them: Go look at any official communication from a company. Have you ever received a ConEd bill that says, “Ya should of paid ya bill on time, now we gonna haveta cut off ya powa”? Of course not. Why? Because that is not standard English, and it would reflect poorly on the company.

Me: I take it you've never called ConEd on the phone in NYC? Because, whew, that'd disabuse you of this fiction pretty quick. Them and National Grid, wow. And I'm not even talking about their representatives, I'm talking about their recordings! Never heard such a thick NYC accent in my life, and I grew up here!
[syndicated profile] languagelog_feed

Posted by Victor Mair

[N.B.:  The archeologically recovered objects, such as those described in this post, are still referred to as "Roman dodecahedron", but that is partly to distinguish them from the scientific study of such figures in chemistry, crystallography, geometry, mathematics, and so forth.  Considering the most recent archeological discoveries and studies, we will have to stop calling them "Roman dodecahedron" and may well have to begin styling them "Gallo dodecahedron" or at least "Gallo-Roman dodecahedron" (see below for the reasoning).

In geometry, a dodecahedron or duodecahedron is any polyhedron with twelve flat faces. The most familiar dodecahedron is the regular dodecahedron with regular pentagons as faces, which is a Platonic solid.

As if we hadn't spoken enough about dodecahedrons in the last few years!  Problem is, most of what we said was speculation, albeit interesting and ingenious, based on little other than the objects themselves — their odd shape, the locations where they were found, etc. — but there were no contemporary texts or associated artifacts / materials that would help us understand the purpose / use of these extraordinary, uniquely shaped objects.

But now we have a truly unprecedented discovery of a dodecahedron from a secure, sealed context.

"The Norton Disney Dodecahedron" (NDD) — with close-up photographs of the object.  The large, opening photograph, makes the front of the dodecahedron look like a face, with two holes for eyes on top, a knob for the nose in the middle, and one hole for the mouth at the bottom, though I'm not asserting that the makers of the NDD had that as one of their intentions.

The Norton Disney Dodecahedron - Norton ...

The Norton Disney Dodecahedron

From the Norton Disney History and Archaeology Group:

We found a fantastic example of a “Gallo Roman Dodecahedron” in June 2023  One of archaeology’s great enigmas. It was found in trench 4 on our 2023 “dig” by one of our volunteers. Trench 4 had only been opened in the last few days of the excavation. No metal detector was used when it was found. As we had to close the trench shortly afterwards we needed to return in 2024 to better understand the context of this find.

There are about 32 known examples, either whole or in parts in Roman Britain. The Norton Disney example now makes 33. There are roughly 130 known examples across the Roman world. All of which are found in north west Roman provinces. The Norton Disney dodecahedron is the only example found in the Midlands and is a particularly fine example. It is well cast, complete with no damage and in an excellent condition. It is an example of very fine craftsmanship, finished to a high standard.

After it’s [recte its] discovery the dodecahedron subsequently underwent XRF analysis by leading archaeo-mettallurgist [recte metallurgist] Gerry McDonnell which revealed it is a copper alloy object. 75% copper, 7% tin and 18% lead. 

It is also an important find in that it was found “in situ”, where it was deliberately placed some 1700 years before with 4th century Roman pottery in some sort of excavated hole or quarry pit. The context of which will need more archaeological excavation to clarify in 2025.

There are no known descriptions of dodecahedra in Roman literature and therefore their purpose remains extremely unclear. They are not of a standard size, so will not be measuring devices. They don’t show signs of wear, so they are not a tool. Nor are they devices for knitting. A huge amount of time, energy and skill was taken to create our dodecahedron, so it was not used for mundane purposes, especially when alternative materials are available that would achieve the same purpose. The most likely use we think is for ritual and religious purposes.

According to the Lincolnshire County Council, the Norton Disney dodecahedron, a 1,700-year-old Roman* artifact discovered in 2023, measures approximately 8 cm (3 inches) in height and is about 8.6 cm wide. It is considered one of the largest examples found, roughly the size of a grapefruit, and weighs 245–254 grams. 

*VHM:  The Norton Disney dodecahedron may be said to be a Roman-era artifact, but technically it is not a Roman artifact, nor are any of the known 130 +/- archeologically recovered dodecahedra Roman artifacts because such objects are not described in Roman texts and have not been found in Roman territory proper (i.e., senatorial provinces), only in the outlying provinces / colonies to the north:  Austria, Belgium, France, Germany, Hungary, Luxembourg, the Netherlands, Switzerland and the United Kingdom, but not in the Roman heartland in Italy.  They were mostly made in Gaul between the second and fourth centuries AD.  

Considering all the above, it would seem that the dodecahedra were a token of Celtic culture (religion / ritual) in northwest Europe during the Late Iron Age.

At their peak in the 3rd c. BC, the Celts expanded as far east as central Anatolia (modern-day Turkey), where they settled and established the region of Galatia (the Galatians of the New Testament).  They also reached the Carpathian Basin, the Danube region, Greece, the Balkans, and the Black Sea.

After its discovery in 2023, word of the NDD's discovery leaked to the public, and it was put on exhibition in a succession of local and regional museums during 2024 and up till today.  Of course, the news was quite sensational, and a flood of videos (dozens that I have seen) began to emerge.  Most of them were of poor quality.  They would get one or two experts to say a few words about how important the NDD was, but usually nothing substantial or reliable.  They were full of speculation, including the earlier claims that dodecahedra were for surveying and knitting gloves, etc., which they would splice together with stock footage of archeologists digging at the site and lots of imaginative drawings and historical illustrations that cannot realistically be linked to Gallo-Roman dodecahedra, NDD or otherwise. attendees at conferences, curators in storerooms, etc.), a few shots of reputable scientists discussing the results of their research, but mostly they had nothing directly to do with the NDD and shamelessly cribbed from each other.  They were pastiches of speculation and imagination.

Here's the best of this recent spate of videos inspired by the NDD that I have seen by now (probably at least two dozen):  

"Scientists Finally Solved the Roman Dodecahedron Mystery… And It Defies Human Origin" (beginning of February, 2026).  

Among others, it features Marcus Webb, lead archeometallurgist at Oxford University (7:10).  The narrator summarizes what Webb says (e.g., that the NDD is not Roman, but more importantly that chemical analysis points to the presence of cremated human bones in the context of calcium phosphate, amber, and rendered animal fat [a combination characteristic of funerary practices and necromantic rites in Iron Age Europe]), but we don't hear Webb himself speaking.

Yet even this relatively good documentary commits some howlers.  For instance, at 10:26, Isabelle Moreau, a paleographer specializing in medieval Latin, is said to have been examining a forgotten Latin ms in a Swiss monastic archives, Codex 134 Mistair Delore (supposedly dating to the 12th century), which has a description that eerily resembles the construction and possible use of a bronze object with twelve perforated sides….  Before you jump to any conclusions, be aware that the "Latin ms" Codex 134 Mistair Delore is actually an Old Armenian Bible translation Codex Etschmiadzin held in the Cambridge University Library.  I doubt that Dr. Isabelle Moreau is saying all those things about the bronze object with twelve perforated sides, and so forth, but rather that the videographer and narrator are attributing these words to her.

——–

This one is relatively decent too.

It's not worth my time or yours to mention the dozens of other videos on the dodecahedron that have popped up like mushrooms in recent months.  Sooner or later, someone or some responsible group of scholars are going to have to carry out a comprehensive study of the art, archeology, history, metallurgy, and other aspects of these enchanting objects.  

Meanwhile, I myself am not finished with dodecahedrons (including especially the NDD) — e.g., miniature dodecadrons strung on a necklace in Han period Southeast Asia and South China, and I will delve deeper into their association with Celtic expansion to the east in future posts.

Also, I will explore their relationship to the zodiac and the calendar (12 astronomical signs and 12 months); agriculture — when to plant; the cycle of 60 (called to my attention by Brian Pellar).  A Gallo-Roman dodecahedron found in London with 3 balls per vertex means that there were 60 of them (20 x 3).

I eagerly await a proper, full, scientific, scholarly report on the WDD.

 

Selected readings

———–

I have included the following article to show just how productive the idea of a dodecahedron is, how far it reaches.

"Acetylcholine-binding protein in the hemolymph of the planorbid snail Biomphalaria glabrata is a pentagonal dodecahedron (60 subunits)"
Michael Saur  1 , Vanessa Moeller, Katharina Kapetanopoulos, Sandra Braukmann, Wolfgang Gebauer, Stefan Tenzer, Jürgen Markl

     PMID: 22916297 PMCID: PMC3423370 DOI: 10.1371/journal.pone.0043685 

PubMed
PLoS One

National Library of Medicine

. 2012;7(8):e43685.
doi: 10.1371/journal.pone.0043685. Epub 2012 Aug 20. 

Abstract

Nicotinic acetylcholine receptors (nAChR) play important neurophysiological roles and are of considerable medical relevance. They have been studied extensively, greatly facilitated by the gastropod acetylcholine-binding proteins (AChBP) which represent soluble structural and functional homologues of the ligand-binding domain of nAChR. All these proteins are ring-like pentamers. Here we report that AChBP exists in the hemolymph of the planorbid snail Biomphalaria glabrata (vector of the schistosomiasis parasite) as a regular pentagonal dodecahedron, 22 nm in diameter (12 pentamers, 60 active sites). We sequenced and recombinantly expressed two ∼25 kDa polypeptides (BgAChBP1 and BgAChBP2) with a specific active site, N-glycan site and disulfide bridge variation. We also provide the exon/intron structures. Recombinant BgAChBP1 formed pentamers and dodecahedra, recombinant BgAChBP2 formed pentamers and probably disulfide-bridged di-pentamers, but not dodecahedra. Three-dimensional electron cryo-microscopy (3D-EM) yielded a 3D reconstruction of the dodecahedron with a resolution of 6 Å. Homology models of the pentamers docked to the 6 Å structure revealed opportunities for chemical bonding at the inter-pentamer interfaces. Definition of the ligand-binding pocket and the gating C-loop in the 6 Å structure suggests that 3D-EM might lead to the identification of functional states in the BgAChBP dodecahedron.

[Thanks to JP Mallory, Timothy Glover, and Lucas Christopoulos]

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