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Author Topic: Missing word?: forma  (Read 338 times)
mkenuk
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« on: August 24, 2017, 10:35:09 PM »

re the malefactor 10-letter game

COD has forma which it defines as 'a taxonomic category that ranks below 'variety'

One for Calilasseia perhaps?

I played it, thinking it meant something else, but obviously it was rejected.
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Alan W
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« Reply #1 on: September 13, 2017, 04:19:34 PM »

Definitely a rare word - absent from many dictionaries. Still, it is in a few of the Oxford dictionaries and the online Merriam-Webster, so I'll add it to our word list. The Shorter Oxford identifies it as an alternative to form, in the sense:

Quote
Botany. A taxonomic grouping ranking below a variety, which contains organisms differing from a given variety, subspecies, etc, in some trivial, freq. impermanent, character, e.g. a colour variant.

The M-W definition is a little vaguer: "a distinguishable group of organisms".

Its plural can be either formae or formas, so formae will also be allowed in future.
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Alan Walker
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« Reply #2 on: September 24, 2017, 10:44:33 PM »

re the malefactor 10-letter game

COD has forma which it defines as 'a taxonomic category that ranks below 'variety'

One for Calilasseia perhaps?

I played it, thinking it meant something else, but obviously it was rejected.

Looks like my reputation is now preceding me. Smiley

Indeed, this is one of those lesser used taxonomic designations, at least in the world of vertebrate taxonomy. Move into Lepidoptera, however, and its usage positively abounds. It's practically impossible to see any in-depth discussion of, say, Heliconius butterflies, without seeing something like "f. eucherioides" appearing in the literature, because Heliconius species are hyper-variable, with several species existing in multiple colour forms. For example, Heliconius erato has at least 20 documented colour forms alone, some of which are geographical variants, some of which are variants that are part of intricate mimicry rings, and several of which overlap with other Heliconius species such as Heliconius melpomene, which itself is a hyper-variable species with another 20 or so colour variants.

Whether any attempt has been made to place "f." on a formal foundation, in terms of being connected to genetics, for example, I am not currently aware of, but in the literature, "f." is frequently associated with well-defined genetic variants. The canonical example is Papilio dardanus from sub-Saharan Africa, a butterfly whose females are Batesian mimics of other butterflies. Depending upon where in Africa you venture, you will see females of P. dardanus mimicking Danaine butterflies, Acraeine butterflies, frequently with astonishing fidelity, and indeed, a former luminary of my own Entomology Society was instrumental in elucidating the genetics underpinning this phenomenon. Consequently, designations of this butterfly such as f. cenea, f. hippocoon and f. trophonissa, are associated with well-defined combinations of certain genes. Indeed, the luminary in question, Cyril Clarke, earned his claim to fame through this work, via an unusual piece of serendipity, which I shall now expound upon.

At the same time as Cyril Clarke was working on the genetics of these butterflies in his spare time, his day job was that of a doctor in a Liverpool hospital. He was given the task of researching, along with the later-to-be Professor Ronald Finn, a condition known as Perinatal Rhesus Haemolytic Disease. This condition arises as follows: a Rh- mother conceives her first child by an Rh+ father, and the child is Rh+. If at any time during the pregnancy, including during the fairly traumatic business of birth, blood from the baby comes into contact with blood from the mother, this triggers an immune reaction in the mother. The mother then has Rh antibodies in her bloodstream from that point on. If she conceives a second child, and that child is also Rh+, the mother's RH antibodies will attack the baby's blood, possibly resulting in stillbirth.

It was while looking into this matter, that Clarke, a geneticist by training, began analysing the data from his patients. In one of those special serendipitous moments, he realised that the data bore an uncanny match to the data from his controlled butterfly matings. It transpires that the RhD gene in humans (which is implicated in the condition) is what is known as a polygene, with a multiplicity of alleles (specific forms of the gene). The manner in which this abundance of alleles is inherited, happens to mimic very closely the manner in which the alleles of the polygene controlling wing pattern in Papilio dardanus are inherited in that species.

As a consequence of this finding, his elucidation of the genetics of the condition, allowed him to direct research in such a manner as to make the treatment alighted upon by his colleagues much more effective. As a consequence of this finding, Cyril Clarke was awarded the Lasker Prize for Services to Basic Medicine in 1980, and was knighted for his efforts. It's been estimated that his work has, to date, saved several million lives in the developed world alone. A legacy many of us would be proud to leave.

The fun part starts, however, when one moves into research on Papilio dardanus butterflies conducted after Cyril Clarke's death, in which the butterfly has been demonstrated  not only to provide a canonical example of a polygene in action, but also, to provide a canonical example of what is known as a Turing reaction-diffusion system. Alan Turing (yes, the same Turing responsible for deciphering the Enigma code) wrote a paper on biological morphopgenesis in 1952, centred upon what is known as a reaction-diffusion system of differential equations, and his paper provided numerous examples of how that system could explain a wide range of morphological developments in biology. Fast forward to 2000 and beyond, and now, there are no less than eleven scientific papers describing the operation of this mechanism, in detail, in Papilio dardanus, and more recently still, several genes governed by reaction-diffusion behaviour, influencing butterfly wing patterns, have been identified and tracked. Some of those genes act as 'canvas definers', specifying regions into which various pattern elements are introduced, and other genes act as 'paintbrush' genes, inserting the requisite colours or pattern elements into those canvas areas.

Indeed, as recently as the beginning of September 2017, I was directed to two papers, covering two such genes - WntA, a canvas defining gene, and optix, a paintbrush gene, which have been investigated using a novel knockout technique using what is known as the CRISPR-Cas9 gene editing system (which itself was borrowed, wait for it, from the immune systems of bacteria). By modifying the CRISPR bacterial gene system, scientists have produced a technique which effectively allows them to edit genes at will in any organism, and researchers into butterfly wing patterns used this technique to find out what happens when you knock our or modify certain genes expressed in butterfly wings. The results are pretty remarkable, and open up the prospect of, wait for it, experimentally probing the evolution of butterfly wing patterns over time.

As a corollary of this research, we could finally see the day when "f.", instead of merely referring to variations that were distinctive to taxonomists, refers to a solid genetic foundation.

And yes, in case you're asking, this is what I treat as light bedtime reading. Cheesy
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pat
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« Reply #3 on: September 25, 2017, 05:41:45 AM »

Someone obviously enjoys typing!
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yelnats
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« Reply #4 on: September 25, 2017, 09:36:38 AM »

Calilasseia,
Thank you for the translated version of scientific papers.

There was a period in my history as a blood donor (early/mid 70s) when I was given an injection to build up Rh antibodies, and then my plasma was taken to make a vaccine? for women who had given birth to a baby of the opposite Rh factor. I believe this allowed them to have another baby without the negative effects common otherwise. The injection effect diminished after a few years and I went back into the regular program.

On the first couple of donations, the plasma group shared the centrifuge that separated the plasma from the blood cells with the general program and it was refrigerated, which meant the cells going back into my arm were much cooler than when they came out. A tingling rather than chilling effect.
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