Respecting the colors

I watched the new documentary of David Attenborough “Life in Color”, available on Netflix. I will recommend anything starred by Attenborough, but this one is special for me, so I will leave here the trailer for you:

So, humans have good vision for colors when compared to other mammals. But our color vision is far behind birds’ vision, and a lot of other groups, including some insects. As you know, we can see the rainbow specter, from red to violet. Other organisms may see other colors, including infrared and ultraviolet wavelengths. In this link, you can see some ultraviolet pictures, taken with special cameras, that show a little bit of how much more information than us a bee can get when seeing a flower.

I was 21 years old when I took my first Ishihara test in a neurophysiology class. Ishihara test is a series of numbered plates written in colored dotted patterns and is used to detect color blindness. Funny thing is: I am colorblind, and I discovered it only at that moment. Specifically, I have deuteranomaly. That means that my green cones (special cells that detect green light) do not work properly. I never noticed it before, as well as most of the 6% of XY people. I see green, but not the same way that most of you see. I am also afraid that I cannot really show you any simulation of how I see the world. You may find them on the internet, but they always seem different from the original image for me. So just believe: I see things in a different way. Less shades of green, and some shades of orange-brown-red may be confusing.

I probably can count in a single hand the number of problems that I had with that before. The worst when I was collecting algae and I could not distinguish the brown ones from red ones (a task I was responsible for as an assistant teacher).

I decided to study structural evolution of plants. And well, I use a lot of Plant Anatomy and microscopy. That means that I slice dead plants in very thin sections, so I can see the organization of tissue and cells in the microscope. We can observe this “fresh” slices, but usually we use some dyes on them. Lot of them are available to detect several compounds: starch, cellulose, lignin (the main component of wood).  A lot of colors, a lot of different staining techniques, with beautiful results. One of the most used dyes is Sudan IV, used to detect lipids, and its positive reaction will give you an orange-red color. That is remarkably like brown and green natural colors often found in plant tissues. It means that, when I need to test plant for lipids, I need to borrow my colleague’s eyes. The colors are there, and I trust on them. I respect them, even if I cannot see them. I will leave at the end some good references for several staining techniques in plants 1–5.

Positive Sudan IV test in a Lamiaceae hair, in a very saturated picture.

When making graphs, schemes, and maps, avoid mixing red/orange and green colors. If you cannot present your pictures in shades of grey or different shapes for dots, try to avoid this specific mix of colors. Doing that, you will make your information accessible to 6% of XY people that see your work. Other types and complete colorblindness are rarer, and these people probably have friends to “borrow” their eyes. If your colorful graph is beautiful, try to upload a “colorblind friendly” supplementary version, if it does not take you much time.

And be aware that sometimes your screen quality does not allow you to see the “true colors”. Have you already been disappointed with printing quality? Sometimes, the problem is not your printer! Monitors with higher values of sRGB are the best and show more trustful colors. Also, the format of images RGB is best for digital images, but CMYK gives better color information for your printer, specifically how much pigment of the four available (cyan, magenta, yellow and black) it should mix. These are different forms of organizing color information in computers. You can easily do this conversion in Photoshop and other image editors, but I can explain better preparation of images for publishing in another post.

Finally, colors are the symbol of LGBTQI+ movements, and this is pride month. I left the closet during the college in the same month that I did that Ishihara test. This is far hard than deal with a deficient color vision, and you need to get over a lot of high school trauma and learn how to trust in people in a (mostly) safer environment. But well, it gets better. And I have my six-colors flag, while I wonder how unique is the way that I see it.

References for staining techniques:

1. Sass, J. E. Botanical Microtechnique. (The Iowa State College Press, 1951).

2. Johansen, D. Plant microtechnique. (McGraw-Hill Book Company Inc., 1940).

3. Ruzin, S. E. Plant Microtechnique and Microscopy. (Oxford University Press, 1999).

4.  Kraus, J. E. & Arduin, M. Manual Básico de Métodos em Morfologia Vegetal. Manual Básico de Métodos em Morfologia Vegetal (Editora Universidade Rural (EDUR), 1997).

5. Demarco, D. Histochemistry Analysis of Plant Secretory Structures. in Histochemistry of Single Molecules (eds. Pellicciari, C. & Biggiogera, M.) 313–330 (Springer New York, 2017). doi:10.1007/978-1-4939-6788-9.

Teaching life cycles of land plants

Clique aqui para Versão em Português.

Life cycles are frightening, that’s a fact. Not only for high school and college students, but also the botanical professional who does not work with reproductive structures.

Personally, I have achieved good results with my students using the following steps.

1. Do not use plants.

Okay, it is a piece of weird advice! But it is important to start slow. All students are familiar with the conventional life cycle of most vertebrate animals, with gametic meiosis. A diplobiont cycle without meiosis to produce gametes sounds like an alien process!

I use the diagram below, making it very clear that meiosis is sporic, and by doing this it is very easy to understand.

2. When introducing the plants, start with the ferns.

No mosses! And certainly no angiosperms! Ferns are the perfect group to explain the diplobiont cycle. Gametophytes and sporophytes are independent and free phases, making their cycle much easier to understand than reduced and ephemeral phases.

Fern life cycle
Image from Wada 2007. Journal of Plant Research 120.

3. Let them work!

The evaluation consisted of launching different terms related to the life history of angiosperms. Students had one week to make a mind map with the terms.

Binucleated central cell – Egg Cell – Embryo – Embryo sac – Endocarp – Endosperm – Epicarp or Exocarp – Flower – Fruit – Gametogenesis – Megagametophyte – Megaspore – Megaspore mother cell – Meiosis – Mesocarp – Microgametophyte – Microspore – Microspore mother cell – Mitosis – Ovary – Ovule – Pericarp – Pollen Grain – Pollen tube – Seed – Sperm cells – Sporogenesis – Tegument

For some cool results that I had (in Portuguese):

Ensinando ciclos de vida de plantas terrestres

Ciclos de vida assustam, isso é fato. Não só aos alunos de Ensino Médio e universitários, mas também o profissional botânico que não trabalha com estruturas reprodutivas.

Pessoalmente eu obtive bons resultados com meus alunos usando os seguintes passos.

1. Não use plantas.

Ok, parece um conselho estranho! Mas é importante começar de forma teórica. Todos os alunos conhecem muito bem um ciclo de vida convencional da maioria dos animais vertebrados, com meiose gamética. Um ciclo diplobionte e sem meiose para produzir gametas parece algo de outro mundo!

Eu utilizo o diagrama a seguir, deixando bem claro que a meiose é espórica e desta forma fica bem fácil entender.

2. Quando introduzir as plantas, comece pelas samambaias.

Nada de musgos! Muito menos angiospermas! As samambaias são o grupo perfeito para explicar o ciclo diplobionte. Os gametófitos e esporófitos são fases independentes e livres, tornando o ciclo muito mais palpável do que fases reduzidas e efêmeras.

Adaptado de Wada 2007. Journal of Plant Research 120.

3. Deixe-os trabalhar!

A avaliação consistiu em lançar diferentes termos relacionados ao histórico de vida das angiospermas. Os alunos deveriam fazer um mapa mental com os termos.

Célula central binucleada – Célula mãe de megásporo – Célula mãe de micrósporo – Células espermáticas – Embrião – Endocarpo – Endosperma – Epicarpo ou Exocarpo – Esporogênese – Flor – Fruto – Gametogênese – Grão de Pólen – Megagametófito – Megásporo – Meiose – Mesocarpo –Microgametófito – Micrósporo – Mitose – Oosfera – Ovário – Óvulo – Pericarpo – Saco embrionário –Semente – Tegumento – Tubo polínico

Alguns resultados legais:

Digital teaching tools for Plant Anatomy

Clique aqui para Versão em Português.

The unfortunate pandemic scenery brought new challenges to teachers from around the world. For example, Plant Anatomy, an integrative part of any field in plant sciences, requires practice and microscopy classes to be taught. These tools can also be useful to those that, even after the COVID-19 pandemic, do not have access to microscopes or slides in their classes. To make this list, I counted with the help of Dr. Fernanda Cordeiro (Federal University of Santa Catarina) and Dr. Luiza Costa (Harvard University). If you have any addition to the list, please let me know in the commentaries, and I can include it here, thanking you.

Most of these databases are in English. But you can always ask the most used browsers to translate it into your native language.

Edit 1: I can’t thank enough Dr. Priscila Cortez, a colleague from the University of São Paulo/the Federal University of São Paulo for these additions below. It took me an entire afternoon to check them all:

Ferramentas de ensino digital para anatomia vegetal

O infortuno cenário pandêmico trouxe novos desafios para professores de todo o mundo. Por exemplo, a Anatomia vegetal, uma parte integrativa de qualquer campo da Biologia Vegetal, requer prática e microscopia para serem ensinadas. Essas ferramentas também podem ser úteis para aqueles que, mesmo após a pandemia COVID-19, não terão acesso a microscópios ou lâminas para suas aulas. Para fazer essa lista, contei com a ajuda da Dra Fernanda Cordeiro (Universidade Federal de Santa Catarina) e da Dra Luiza Costa (Harvard University). Se você tiver alguma adição à lista, por favor, conte-me nos comentários, para que eu possa incluí-la aqui, agradecendo-o devidamente.

A maioria desses bancos de dados estão em Inglês. Mas você sempre pode pedir aos navegadores mais usados para traduzi-los para sua língua nativa.

 

Edit 1: Mal posso agradecer a Dra. Priscila Cortez, uma querida colega da Universidade de São Paulo (também da Federal de SP), pelas adições abaixo. Levei uma tarde inteira para checá-las:

Tive a honra de conviver com a estudante Ana Vitória enquanto ela trabalhava para fazer o Atlas de Anatomia Vegetal da UFSC. // I had the honor to know Ana Fernandes, the student that made the Atlas de Anatomia Vegetal – LAVeg, Universidade Federal de Santa Catarina