Ribeirão Preto, September 2011 - nº 21 Year 11
CTC EDUCATIONAL PROJECT MEDICAL SCHOOL OF RIBEIRÃO PRETO REGIONAL BLOOD CENTER OF RIBEIRÃO PRETO
DNA scrap
The flight of bees in life reproduction
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Raising laughs from the audience, Ádamo Siena and Daniele Viola showed how the sanitarist physician Carlos Chagas was the first scientist to completely describe an infectious disease. The play, written and performed by them, shows how the kissing bug – that is how is called the insect Triatoma infestans – transmits the Trypanossoma cruzi, flagellate protozoan, responsible for Chagas’ disease. The play premiere “Chagas and the kissing bug” took place in February 2010, when the House of Science received Carlos Chagas´ history
In 1897, Carlos Chagas (1878-1934) left the coffee farm where he was born in Minas Gerais, near a small town named Oliveira, and enrolled himself in the Faculdade de Medicina do Rio de Janeiro that back then was the capital of Brazil.
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students from the discontinued program “Me at USP Jr.” by the Dean for Cultural and Extramural Activities of the University that aimed to offer Elementary and High School students experience with the scientific and cultural atmosphere of USP. To write the play, Ádamo and Daniele former students of the House of Science and undergraduate in Biological Sciences (Unesp) and Physical Education (USP), respectively –adopted as reference the celebration edition of the 100 hundred years of the discovery of Chagas’ disease by Revista Radis, produced by Fundação Fiocruz (Fundação Oswaldo Cruz). The discovery of the disease was in 1909, when Carlos Chagas went to Minas Gerais to help in the campaign against malaria. The theatre production illustrates how the bug infects human beings: it is
His conclusion thesis was completely dedicated to study malaria. After he majored, Chagas was assigned by Oswaldo Cruz to fight the malaria epidemics that have jeopardized the modernization works in the country.
Life in the root of water hyacinth
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generally at night and in the face area where the kissing bug (that is the reason for its name), sometimes infected by T. cruzi, bites man to suck blood and then they fill up their digestive tube and defecate close to the bitten area. By scratching this area, man makes easier the entrance of the parasite in the organism, once the parasite might stay in the bug’s feces. The House of the Science – supported by the Regional Blood Center of Ribeirão Preto – produced a video based on the play which is available on the website www.hemocentro.fmrp.usp.br/casadaciencia
Men who worked in the expansion of the railroad Central do Brasil were getting sick, halting the construction. It was right there that Carlos Chagas, after 30 years, discovered what he is famous for.
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Ribeirão Preto, September 2011- nº 21 Year 11
The use of Trypanossoma cruzi in scientific research House of Science
Interview
The current research with Trypanossoma cruzi goes beyond Chagas’ disease and uses the parasite as a model to observe the response of the immune system. That is what reveals Professor Dr. João Santana da Silva of the Department of Biochemistry and Immunology of FMRP – USP.
Cartoon: André Perticarrari
Revista Radis
The infection by T. cruzi results in a series of diseases, for example, heart disease, megaesophagus, megacolon. A question that intrigues researchers is how this flagellate modulates the immune response. “If we were able to answer this question, we would also be able to answer how the immune system works. We are using T. cruzi as a weapon to answer this question and, by indirect means; we ended up answering how the infection triggers these diseases”, he reveals. This flagellate has the capacity to infect all nucleated cells and it has a series of surface molecules that interact with the cell molecules. “This interaction happens due to many parasites’ receptors which bind with the host cell and then the parasite effectively enters”, Prof. João explains. Read the interview: not infect. Trypanossoma cruzi (T. cruzi) is a JS - When is exactly T. cruzi flagellate protozoan that causes identified in exams? Chagas’ disease. This name was I do not look for the parasite; I look for given by Carlos Chagas in honor its consequences. I check if there is any of Osvaldo Cruz. Flagellates are antibody against T. cruzi in the individual’s unicellular microorganisms that serum, consisting in an indirect assay. I can do a direct assay though: I get the Prof. João Santana coordinates a laboratory at move using flagella, appendices FMRP that has conducted researches on T. cruzi individual’s blood and run a PCR to check in filament forms. Since the for more than 50 years. if T. cruzi is there. Years ago, we used to discovery by Chagas, who was conduct an assay known as Journal of Science: Does xenodiagnoses, we used indicated to Nobel Price, the Trypanossoma cruzi depend on man to place 40 kissing bugs studies have never stopped. The immune system is for its cycle? in the individual’s arm capable of fighting it, but When man is infected, T. João Santana: It needs any nucleated and engorged, and not of eliminating it, that cruzi is in the tripomastigote cell. In the host (man), it invades a cell and we waited for 40 days is the difference. Because stage, and then it turns to the there it changes its stage to metacyclic and then analyzed the the encysted parasite amastigote stage. T. cruzi trypomastigotes, if the parasite has bug’s feces to check if moves to determined remains longer in this encysted come from the kissing bug, for example. it was infected. It was places and stays within stage, which is the amastigote, Still within the cell, it changes to the an assay to identify the the cell, where the because it is “hiding” from the amastigote stage and by binary division it parasite. immune system is not immune response. multiplies. When the cell gets bigger, with JS - Why is not the able to find it. JS - What are the perspectives a high amount of parasite, it changes to immune system able to on the cure for the disease or trypomastigote stage, ruptures the cell and fight T. cruzi? even on the better understanding of releases a large amount of parasites there Actually the immune system which might infect some neighbor cells or can fight T. cruzi. We have in our lab at T. cruzi? There are lots of groups in Brazil and if these parasites reach the bloodstream, least 60 mice from different lines, each they might infect distant cells. Then it one of them has a deficiency in the also abroad that have been working to closes the cycle. If there is kissing bug, immune system in some specific points. control the disease. Some, like my group, the bug sucks blood with the metacyclic If I infect one animal that does not present in the past, wanted to know how the trypomastigote stage which, within the one of these cytokines – which is capable disease happens and why the individual bug, goes through a stage known as of helping in the infection control – the gets sick. Today we are quite sure about epimastigote. It does not multiply as animal dies in 10 or 12 days. There is a how the disease develops but not so sure epimastigote and when it goes to the series of molecules that are secreted by about the effective way to cure it though. digestive tube it changes to metacyclic the immune system which are involved There is a drug, benznidazole, which kills trypomastigote. Then in the bug’s feces in the infection control, if the animal does the parasite, but has a large number of we find metacyclic trypomastigote, not have it, the animal dies. The immune side effects. We described, two or three which would be the infector stage. If we system is capable of fighting it, but not years ago, that there are other drugs put a T. cruzi in a liquid, it will turn into of eliminating it, that is the difference. which are more effective and capable of epimatisgote. We have a lot of means to Because the encysted parasite moves controlling the parasite in an experimental culture the parasite as epimastigote, this to determined places and stays within model. We need an effort to take it from lower infecting stage. Sometimes it is the cell, where the immune system is not the lab benches to drugstores. It is a quite even used as a “vaccine” in some animals, able to find it. T. cruzi is capable of getting long way, it involves a lot of people, a lot once it is theoretically the stage that does way from the immune response; it has a of money, a lot of effort, because we have to do all the clinical assays and it takes a series of mechanisms to trick the immune while. Right now, here in Brazil, we do not 1µm system for a while. receive incentive to do that with T. cruzi. JS - Is there only one type of T. cruzi? Do have any doubts? Check more of There are more than six types of this interview with Prof. João Santana on different strains and even in a type there the House of Science’s website. are several lines. There are some that are www.hemocentro.fmrp.usp.br/casadaciencia extremely pathogenic; they are capable of killing a dog. Sometimes, if I infect a PCR (Polymerase Chain Reaction): is a mouse with two T. cruzi, it dies, but there molecular assay that amplifies DNA are some that are infected with a million sequences specific to the target-pathogen based on temperature variation and use of and they just do not die. Amastigote JS - In which stage does T. cruzi synthetic oligonucleotides - acid polymer Epimastigote nucleic short, normally with twenty or less Tripomastigote remain longer in man?
Editorial
This 21st edition has a special flavor: the House of Science is celebrating its 10th anniversary. With a long time on the road, the Journal of Sciences (JS) has already a clear editorial line, dedicated to science dissemination with objective texts that privilege the development of concepts, once subjects related to
bases (source: Fiocruz).
science are difficult. That is exactly what makes this challenge even better. All the JS editions are planned and previously structured. However, this edition has revealed how important are the registers done by the team. They are indispensable to write the history of the House of Science, because the production of material for diffusion (website, journal, and Leaflets) is always based on the
evaluation of the coordinated programs. The 21st JS was born from the effort of the House of Science team to show everybody a small part of the total activities we develop here. However, the menu varies from T. cruzi, DNA, trophic guilds to the root of the water hyacinth. Enjoy the reading!
The Journal of Sciences is a publication of the House of Science of the Regional Blood Center of Ribeirão Preto/USP distributed to schools. It is part of the Educational Project CTC/CEPID and INCTC – Fapesp and CNPq. Coordinators: Dimas Tadeu Covas, Marco Antonio Zago and Marisa Ramos Barbieri. Coordinator of the House of Science and MuLEC: Marisa Ramos Barbieri. Journalist: Gisele S. Oliveira – MTB 61.339. Layout: Gisele S. Oliveira. Articles: the House of Science team: Ádamo D. D. Siena, André Perticarrari, Fernando Trigo, Gisele S. Oliveira, Gustavo Leopoldo R. Daré, Maria José de Souza G. Vechia, Marisa Ramos Barbieri, Ricardo M. Couto and Rosimeire R. Tritola. Translation and Revision: Alessandra Almeida and Fernanda Udinal. Support: Blood Center of Ribeirão Preto Foundation, Fapesp, CNPq and USP. Address: Tenente Catão Roxo Street, 2501, CEP 14051-140. Telephone: +55 16 2101 9308. Website: www.hemocentro.fmrp.usp.br/casadaciencia. E-mail: casadaciencia@hemocentro.fmrp.usp.br. Circulation: 3.500 copies. Free distribution. The material reproduction is allowed unless the source is mentioned.
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Ribeirão Preto, September 2011 - nº 21 Year 11
Who would say that a construction of a DNA model could contribute to the discussion and the development of some concepts! Using materials that would be thrown away, three students from basic education, advised by researchers at the Regional Blood Center (Kátia Kaori Otaguri, Mariana Tomazini Pinto and Tathiane Maistro Malta Pereira) have built a “giant” DNA molecule. This 2m model allowed the students to learn and also explain
DNA scrap
the molecular structure of the DNA to friends who have also explored this subject. During the presentation, questions like “Why are the strands intertwined in a spiral shape of a helix?” And the students shared what they have learned: “The double helix, in fact, is not a stair! It is a helix because of the structure, the way they stick with the carbon towards the phosphate, it leans
The DNA is a molecule found within the nucleus of cells. It is formed by a sequence of nucleotides.
Gene is nothing more than a DNA fragment (…), it is a fundamental unit of heredity, it means, it goes from generation to generation. They are formed by specific sequences of nucleic acids.
For a carbon bond to happen it is necessary that carbon 1 is bound to the nitrogenous base, carbon 5 is bound to phosphate of the own nucleotide and the carbon 3 bonds to the phosphate of the next nucleotide. And if we pay attention to this molecule, it is in the direction 5’ by one side and by the other 3’, allowing then to form the bond of the nitrogenous bases.
At the Mural, 42 students discussed and explored more complex subjects like Okazaki’s mysterious fragments, which are synthetized in “small blocks” and then united to form one of the DNA strands; the PCR “thermal shocks” technique to amplify a DNA sample; the enzymes involved in the duplication of the genetic material (DNA polymerase and DNA ligase) and the circularity of bacterial DNA. It was a veritable learning test. The Mural represents an afternoon fulfilled with very important presentations, in which the students, who take part in
so the strand rolls up, and the other strand runs in the opposite direction”. By the register of the House of Science’s team (André Perticarrari, Fernando R. Trigo, Flávia F. do Prado, Maria José de Souza G. Vechia and Renata Aparecida P. Oliveira), the Mural was documented, analyzed, and written so readers, like you, could learn a bit more about this fascinating molecule of life. Check some of the students’ comments:
The nucleotide is composed by a pentose, a phosphate and four nitrogenous bases which are adenine, cytosine, guanine, and thymine.
There are purine and pyrimidine nitrogenous bases and one completes the other. A pyrimidine completes a purine (…), an adenine completes a thymine and the cytosine completes the guanine. When fecundation happens, you “get” a part of the DNA from the father and one from the mother and everyone here is different because of that. You put different things together and they form a new sequence. It won’t be like the father or the mother, it’ll be the combination of both. That’s why people have different characteristics.
the program “Adopt a Scientist”, have the opportunity to share the outcomes achieved with everybody. A moment of growing together. A total of nine theme groups showed their projects on subjects as Synapse and Neurons, Schizophrenia, Aphasia, Mental Health, DNA Structure, Computer
Biomolecular Science, Drosophila, Biodiversity, Biological Models, Natural Selection, Stem Cells, Cell Differentiation, Blood and Donation (in the play “For one drop”), the projects were evaluated by researchers and teachers. According to the House of Science’s coordinator, Marisa Ramos Barbieri “the Mural has not ended; it is always a preparation for the next. It has no end, just like the research”. Watching the other groups’ outcomes accelerates the process. The exchange is essential for the rhythm of the program. “It is an opportunity to talk and to listen to everybody”.
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Ribeirão Preto, September 2011 - nº 21 Year 11
Paul Hebert
From nature to the book or from the book to nature?
to the naked eye), which can be found coexisting in a 30cm plant. It aroused the curiosity and the will to separately recognize and identify the different beings in that microenvironment. House of Science
0,02mm
Daphnia sp.
In “Vacation with Science”, after exploring the water hyacinth, some students were invited to know a new set of organisms common in the lake of USP, but uncommon in books, the microcrustaceans. When asked about the structures found in the dorsum of the water flea (picture on the left), the students did not dare to say, ask, and recognize the eggs. But before that, they had the opportunity to participate in the analysis of the diversity of the beings that live in the root of the water hyacinth, to watch a flatworm, a mosquito larvae and a mollusk interacting with nature. It was a great surprise to check the amount of organisms and their sizes, from the microscopic ones to the largest ones (visible
Student observing the root of the water hyacinth during “Vacation with Science”.
Are the animals of the water hyacinth, as the water flea, the same as those in the books? And the doubt was raised.
Stem cells and asymmetric division mitosis” has been defined: the diseases, such as leukemia. asymmetric (the one the stem Are stem cells exclusive to cells perform), in which the cells humans? replicate and differentiate. By Stem cells are not only found in doing the asymmetric mitosis, humans, they can also be found the cell originates a copy of itself in plants and in all multicellular that keeps the original features, organisms, however the potency primary or stem (and then the of the adult stem cells varies name stem cells) and also depending on the organism. originates a differentiated cell. Despite different, the cells keep the same genetic material of the Written by the student Luciana first cell that has originated them. Souza da Silva, from the public The difference is in the activation school Professor Nestor Gomes and inhibition of specific groups de Araújo from Dumont – SP. of genes that will determine the function and the structure of every cell. What are the importance and the objective of the studies on stem cells? The study of these cells is extremely important, because scientists suspect that on these cells relies the key for the cure of many diseases, such as cardiovascular diseases, neurodegenerative, type 1 diabetes, strokes, blood disorders, spinal cord injuries, and kidney diseases. The main goal of the researches on stem cells is to use them to recover tissues damaged by these diseases or injuries. A good example is the bone marrow transplant, a therapy with adult stem cells, an extensively investigated Luciana during her presentation at the Mural in subject that can cure blood December 2010. House of Science
What are stem cells? They are special cells capable of originating other cells of the body and also of self-renewing. They are unique, because they can remain undifferentiated or originate specialized cells by cell differentiation. Stem cells can be embryonic or adult and can be classified according to the number of the different cell lines they are able to originate. Embryonic stem cells are found in embryos, the ones isolated, before the blastocyst stage, are totipotent and they can originate all embryonic and extraembryonic (placenta and annex) cells. The stem cells isolated at blastocyst stage though are pluripotent and able to originate all kind of embryo cells. The adults are found in diverse tissues such as bone marrow and liver. This type of stem cell has a more limited differentiation capacity; they are multipotent and able to generate cells from different lines. Why does cell differentiation happen in stem cells? This special feature of stem cells of generating a differentiated cell happens because of the asymmetric mitosis. For a long time mitosis has been defined as a cell division in two exactly the same. However with all advancements in cell biology, a “new type of
Ribeirão Preto, September 2011 - nº 21 Year 11
The flight of bees in the reproduction of life
How many organisms benefit from this flower (Tecoma stans)?
nectar which is composed by sugars, an important source of energy. Flying also allows bees to visit more than one thousand flowers a day. It is quite a nice life, isn’t it? They enjoy the lovely views, eat and then they just have to find the “perfect” match to reproduce. As incredible as it may seem, flowers also help on that happy history of life! Flowers produce the pollen grain, a food rich in proteins, which is extracted and transported, in the third pair of legs, up to the nest. Why do bees set down pollen in their nest? The female “just like our moms” take care of their children. This mother care starts when the larvae Tecoma breaks through the egg and starts being fed with the pollen brought by the females. Ricardo M. Couto
Flying is a wish of every human being. From angels to Superman, seeing the world from the top arouses curiosity and sparks our imagination. Who has never thought of flying? There is only a problem though: it requires energy. The animals worked this out by many different ways, by making their skeleton lighter, like the birds did, or specializing their food, like bees did. Bees are expert on the art of flying, but how and where they get energy for that? Of course flowers are gorgeous, with their forms and colors that delight those who can see. But those who see it from the top see it better, and they not only enjoy the Mangava view, they also search for the food hidden within the flowers. It is the
bee visiting inflorescence of stans
Trophic guilds
Organism is a common reference We would be naïve if we thought in the studies of extinct and that this flower fulfills the needs of living beings, however there is a only one species of bee. Actually, discussion about the limitations of Tecoma stans is a tree that can using it, which has made difficult reach 12 meters, native to Mexico the understanding of biodiversity, and brought to Brazil in 1871, it whose complexity is not fully explored. Studying the organism might be useful to 48 species is important, but is it enough to of bees, among understand the specific them the native and complex of the Xylocopa questions related gender, to population and popularly known community? as mangava or A concept not mamangava. fully explored, but 0,3 mm In the lack of this fundamental for plant, or when it is in understanding flowering, the bees Tongue or glossa of a bee (Apinae: the energy flow in attracted by the flowers Euglossini) adapted to collect nectar an ecosystem, is the concept of the of Tecoma explore other from flowers. species, like the passion fruit trophic guilds, which are formed (Passiflora sp) and the orange by species that explore, in a similar way, a common base of resources tree (Citrus sp). (food). We can have, for example, House of Science
Getting to school…
1 cm
Knowing the food specialization of bees was important for the students at the 8th grade of the school Sesi 259 in Ribeirão Preto, supervised by the teacher Ricardo Couto and the journalist Danielle Castro in an investigative work for the specialization course “Partners in Science Dissemination” (2010 – 2011), coordinated by the House of Science.
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Bee that emerged from a nest located in the trunk of Tecoma stans at the school Sesi.
the guild of nectar collectors or the guild of pollen collectors. There are many reasons for the bees to visit flowers and diverse ways by which flowers attract bees, forming different guilds and resulting in a diversity of interaction between both. Flowers provide food (pollen, nectar, and oil), produce substances used by bees in the construction of the nest or needed for the bees’ reproduction, hide floral resources, deceive the visitors or serve as a place for mating. For curious observers and bee researchers it is possible to notice that the behavior and the form are specialized for the collector resources difficult to access and for exploring specific floral resources. These pollinator guilds are formed mostly by species of lonesome bees, in which there is no contact among generations, because generally the female dies before the descendants emerge.
To analyze and investigate In a sugar cane monoculture, what happens to the guilds? It is expected a decrease of the biodiversity, with a reduction of the natural vegetation, getting rid of the native vegetation to plant a single species of plant reducing the number of ecologic guilds! Studying population and community goes beyond knowing a catalogue of species or describing ecological relationships. Has media, with its important role in scientific dissemination and in being opinion leader, found sources that might be the foundation for the complex network of knowledge that compose the subject of biodiversity?
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Ribeirão Preto, September 2011 - nº 21 Year 11
Life in the root of a water hyacinth
In July 2010, in one edition of “Vacation with Science”, a program by the House of Science for students from basic education, the subject was the biodiversity in the lake of USP. Once these programs are developed in the MuLEC – Museum and Laboratory for Science Teaching located at the campus of USP, they aim to articulate the relation between laboratory and nature observation, followed by theoretical discussions with specialists. For three days, the students’ participation in various activities such as experiments, lectures, and observation is documented and
A complex “ecosystem”
Water hyacinth and its fauna
Do you know the water hyacinth? House of Science
The water hyacinth is a plant common to aquatic environments, floating on the surface with the help of “natural floats”, it means, the base of the leaves is dilated and rich in a tissue that accumulates air (aerenchyma), it belongs to the group of the angiosperms, produces flowers and fruits. But what is the relation between diversity and this plant? Many living beings roots can be watched living in its roots where they find shelter from predators, find food resources, a place for reproduction, forming a microenvironment. Odonata
allow us to notice the enthusiasm in confirming the information read on books and textbooks. Focusing on zooplankton, in this activity, guided by André Perticarrari (expert on aquatic ecosystems), the students observed and analyzed a plant present in the lake, the water hyacinth that was collected the day before. With the idea of working with diversity of the beings that live in this plant, understanding a little more about the organisms found, the students were invited to explore it. They observed the animals and tried to recognize the different groups – their forms and behaviors, associating it with what they have learned at school.
Investigating the biodiversity: student observes root of water hyacinth for SNCT / CNPq - 2010.
nymphs (dragonflies) and other insects, gastropod mollusk, mosquito larvae, water mites, flatworms, microcrustaceans (cladocerans or water fleas and copepods, that compose zooplankton), notonectas (backswimmers) rotifera (microscopic animals), tadpoles and even fish can be found (see the scheme). These beings found can be microscopic (about 100 to 1000 times smaller than a millimeter) and some with many centimeters living together. Environmental factors such as water condition, light, food, temperature, etc., may vary over the years, influencing in the diversity.
Today’s special: periphyton!
As we have seen, many organisms adhere to the root of this plant. These living beings represent a true banquet to a lot of animals that form the trophic guild of the epiphytes or periphyton eaters. A guild is formed by groups of organisms that have similar ways of surviving, it means, they explore the same resources in a similar way. In our case, animals that eat periphyton. Plenty of insects, such as the ephemeroptera nymph and the mosquito larvae, various fish, little mollusks, and tadpoles belong to this guild, eating the microalgae, rotifer and protozoan from the roots, exploring this rich food resource. As we can see, a simple plant that floats on aquatic environments might be a place where many ecological relationships happen and a lot of animals find food to survive. If a plant gives shelter to huge
diversity, could you imagine a lake? This great diversity of living The outcomes of these activities have beings, belonging to many awakened interest and gave birth to an groups and found in the root exposition about diversity and stem cells of the water hyacinth, forms a in the lake of USP (in the National Week real community where a lot of of Science and Technology by CNPq interactions happen. There the – 2010). microorganisms find shelter Think and answer against predators, but they Can animals that also find food. Mites, which are eat plankton (phyto and zooplankton) form voracious predators, eat mosquito a guild? And the ones larvae which by their turn eat the that eat detritus (rests of small microcrustaceans. Small organisms, organic matter)? Would you know the relation fish eat the snails that eat the between guild and diversity? Could the microscopic algae that adhere guild be a diversity indicator? to the root. We can notice, by these few examples, different Learn more! food chains that form a complex Do you want to know more about flatworms, zooplankton, and ecosystems? food network only in this small Visit the House of Science website: environment. Another ecological www.hemocentro.fmrp.usp.br/casadaciencia relation we can find is the presence of microscopic algae, Check the size of animals in a scale bacteria, protozoan and rotifer that are adhered to the roots, forming what we call periphyton (a group of organisms that adhere to a substrate); this relationship Descending order is known as epiphytes.