Talk:Trypanosoma brucei

this

this is awesome --Anonymous

This statement is very odd and needs revision: "The C terminal domain forms a structural bundle of 4 alpha helices, while the N teminal domain forms a 'halo' around the helices. The tertiary structure of this halo is well conserved between different VSGs ..." The C-terminal domain is much more poorly defined structurally, and the N-terminal domain is much more complex than described. I will return to this if I have time sometime this summer. --RobertSmithies (talk) 19:25, 25 June 2009 (UTC)

Text for inclusion

I have performed a big tidy of the trypanosomatid and trypanosoma pages and there is a lot of information from those pages which would be more appropriate here: - Zephyris _Talk 19:03, 30 June 2010 (UTC)

Research and Disease Control

Trypanosome is transmitted by tsetse fly. T. brucei locates in the posterior section of the midgut of the insect, where it multiplies the trypomastigote form. They then migrate farther forward into the esophagus, pharynx, and hypopharynx and enter the salivary glands. Once in the salivary glands they transform into epimastigotes and attach to host cells or lie free in the lumen. After, several asexual generations they transform into metacycylic trypomastigoes, which are small and stumpy and lack a free flagellum. Only metacyclic trypomastigotes are infective to a vertebrae host.

Trypanosoma brucei parasites experience differentiation in their life cycles in response to changes in temperature, availability of nutrients, and immune system defense. These changes occur so the parasites can readily adapt to different host environments. In previous studies, researchers discovered that cycling between the mammalian host and the insect vector, T. brucei expresses different types of stage specific surface coat proteins including variable surface glycoproteins (VSG) and procyclic acidic repetitive proteins (PARP) (explained here), that allow them to evade the immune systems of both species . Researchers also determined that stumpy-form trypanosomes can be induced to differentiate by cis-aconitate or citrate (CCA)--intermediates in the Krebs cycle--into procyclic forms (shedding the VSG coat for a PARP coat) , and that temperature reduction from 37 °C to 20 °C induced hypersensitivity of stumpy forms to CCA .

The primary mechanism by which T. brucei can change forms in response to the CCA signal and to temperature drops is a group of surface proteins known as proteins associated with differentiation (PAD). These transmembrane proteins convey the extracellular CCA signal to differentiate into the procyclic form. T. brucei slender forms do not have PAD proteins (except those which are in transition to the stumpy form) so the CCA signal is relatively ineffective on them while the stumpy forms show the PAD1 protein. A second protein, the PAD2 protein, is also found in stumpy forms, but is not diagnostic of stumpy forms (i.e., not all of them have it). PAD2, while also allowing the transmission of the CCA signal, is thermoregulated so that it upregulates dramatically at the lower 20 °C temperature than the 37 °C temperature . This would make sense since the job of the PAD proteins is to allow the trypanosome to switch to the procyclic form upon entering the fly and the 20 °C temperature would be indicative of the shift from the larger human body to the smaller fly body.

Trypanosoma brucei morphologies

Trypanosoma brucei sub-species have two forms in the bloodstream of a vertebrate host, the rapidly dividing long-slender form and the non-dividing short stumpy form. The short stumpy parasites are adapted for uptake into the tsetse fly vector, and are non-proliferative in comparison with the slender forms.

In a typical bloodstream a simple mitochondrion with or without tubular cristae runs anteriorly from the kinetoplast. In the insect stage, the mitochondrion is much larger and more complex, with lamellar cristae.

As the trypanosomes usually live in blood they are called hemoflagellates.

Trypanosoma brucei cell surface

Unique to the African trypanosome Trypansoma brucei is the expression of a variable surface glycoprotein (VSG) coat on the cell surface, which undergoes constant variation in order to evade the humoral immune system (antibody response). It is thought that recombination via double-stranded DNA breaks from a repertoire of about 100 complete VSG genes, and a large number of VSG-related sequences, is responsible for the vast diversity of the parasite. This recombination would retain effectiveness in immune evasion by maintaining diversity.

VSG coat

Trypanosoma have evolved a strategy for avoiding a host’s immune response by implementing antigen variation. Antigen variation is the process of a parasite changing its surface protein. Particularly, trypanosomes use the antigen variation of variant surface glycoprotein (VSGs). The parasite produces and covers its own plasma membrane with host VSGs. As the parasite attacks the host’s antibodies, it changes its expression to the new VSGs and masks itself from the body's natural defense mechanisms against foreign particles. This strategy allows the parasite to regularly switch to different VSGs and continue to thrive in its host. This contributes to trypanosome parthogenesis because as soon as the host's immune system responds to current VSGs, the parasite quickly switches to another type of glycoprotein.

There has been research done to study the mechanism of antibody clearance from the parasite. It was found that Ig-VSG immune complexes are arranged to the posterior end where these complexes undergo endocytosis. The researchers found the hydrodynamic flow that acts on swimming trypanosomes cause directional movement of the Ig-VSG immune complex in the plane of plasma membrane shifts to the end. The Ig-VSG complex shifts aided by hydrodynamic forces help to protect the trypanosomes against the host’s immune system.

In addition, two life cycle forms of Trypanosoma brucei are easy to culture and are genetically pliable.

Life cycle

Trypanosoma undergo a complex life cycle which includes several different morphological forms. For example, Trypanosoma brucei is transmitted between mammalian hosts through a tsetse fly vector and undergoes a series of morphological and metabolic changes to adapt to these very different environments. The most significant change is the developmental changes of its mitochondrial function from. Through each of the following stages, the single mitochondria in a trypanosome is precisely duplicated to ensure replication of the parasite and survival inside its host. These mitochondrial changes are critical to the survival of the protist inside the tsetse fly midgut and the human bloodstream. The life cycle of Trypanosoma rhodesiense begins when trypomastigotes are ingested by flies from an infected mammal or arthropod source. The trypomastigotes then undergo asexual reproduction in the fly's midgut. Once reproduced in the midgut, they migrate into bodily fluids, including saliva. In the salivary glands, the they are transformed into metacylic trypomastigotes. The metacylic trypomastigotes are then transferred into the host's bloodstream when the fly feeds, and then are transformed into trypomastigotes. Once they are transformed, the trypomastigotes reproduce asexually inside of the host.

References

Red links

Wikipedia encourages red links for good reason, they eventually lead to articles. Tb is carried by different species, but there are primary species for different parasite subspecies that infect humans versus animals. It is not necessary to say, well, there are different fly species, so don't mention any. This is an encyclopedia seeking to cover everything. Correct is to introduce some fly species, then later develop which ones carry which species and infect which hosts and create articles about the well-stocked ones. There is literature on this, and Wikipedia has no policy against Tsetse fly species. — Preceding unsigned comment added by 2601:648:8503:4467:ECFF:D4F0:B5F2:11E6 (talk) 18:32, 12 February 2017 (UTC)

Yes. Some of us are well aware of the Wikipedia policy on red link. Although "Good red links help Wikipedia", it does not encourage that every possible terminology/name/phrase be red linked ("Articles should not have red links to topics that do not warrant an article... Do not create red links to articles that are not likely to be created and retained in Wikipedia"). In your case Glossina palpalis does not exist as a page but is already included in the main page Glossina. In fact no species of Glossina has a separate page so far. There are dozens of species and there is no reason to favour a particular species. And you are (most probably) the same StupidUserName whose account has been blocked from editing. Chhandama (talk) 10:11, 13 February 2017 (UTC)

I have been blocked from editing under that user name, is this a discussion of the topic or a personal issue? "Your account has been blocked from editing Wikipedia with this username."

There is a reason to include an extensively studied species with geonomic studies and that has major research literature available for writing an article. All species of tsetse fly are not the same.

So, yes there is a reason to favor a particular species. Biology. That is what species are.

Wikipedia also favors articles on all species even without sufficient literature, but in this case, due to it being a major vector for the human disease, it is an excellent choice for a mention and an article written from its extensive body of literature.

2601:648:8503:4467:ECFF:D4F0:B5F2:11E6 (talk) 22:55, 13 February 2017 (UTC)

Look at the section Infection and pathogenicity, and see how it should be discussed, with proper citation. Even if you know something, always support with citation. Anyway this is a page for T. brucei and not about a particular species of Glossina, and there is absolutely no need to mention that in the lead. Chhandama (talk) 02:49, 14 February 2017 (UTC)

I am trying to go by Wikipedia's guidelines on what should be in a lead. A lead should be a broad overview of the topic: [1] "The lead should stand on its own as a concise overview of the article's topic. It should identify the topic, establish context, explain why the topic is notable, and summarize the most important points, including any prominent controversies." This article's lead is nothing of the sort. It should mention the organism, its clade of subspecies, its general ecology, including distribution and diseases, the tsetse vector, the three major economic issues and hosts, humans, game animals, and farm animals, its discovery and general ecology, and the state of science today, including a sentence about the genomics issues. That would give a concise lead that a reader accessing the article on a mobile device, for example, would come away with a solid idea of the organism. Instead it contains, for example, this cryptic sentence, "Whilst not historically regarded as T. brucei subspecies due to their different means of transmission, clinical presentation, and loss of kinetoplast DNA, genetic analyses reveal that T. equiperdum and T. evansi are evolved from parasites very similar to T. b. brucei, and are thought to be members of the brucei clade.[4]" But I add a human species vector and it requires insults ("you're blocked"), lectures ("red links"), and quite an ordeal. The organism is known and studied for being a human pathogen, and this and the connected articles contain a lot of plagiarized information that I was considering rewriting. So, I would like to edit it. The AAT needs expanded greatly. This article is out of date in addition to being plagiarized. But, I think that every edit I make will be reverted, even if it is sound, and argued, because, simply, there are ownership or new editor issues. Two words = five hours. No wonder all the plagiarized information is still in the articles years later. 2601:648:8503:4467:9C40:6138:A33B:2DB7 (talk) 02:28, 15 February 2017 (UTC)

You don't have to take it like that. Make edits as you wish (provided that your contributions are based on cited reliable sources). Create a less embarrassing/arrogant user name, and try to me more genial and understanding. Remember Wikipedia is a public collaboration, no one owns any of it, but editors and admins do work to prevent useless (vandals) and less useful edits, and to utter annoyance, there are a lot of them. Chhandama (talk) 03:41, 15 February 2017 (UTC)

Back to the user name. It is not arrogant or embarrassing. I spent twenty minutes trying to pick a stupid user name. How juvenile that everyone freaked out at the word "stupid," and became hostile towards someone making real edits and now it seems I will be attacked, even on article talk pages, for light heartedly picking what I though was a bit of a silly name. You can't let it go.

You might have fewer vandals, at least percentage wise, if you weren't so jumpy and hostile towards new editors, which I think this is what this is about. Geniality is a two way street, and there is not much more offensive than being attacked from square one, then being told that if you had graciously accepted the attacks all would be okay. If you don't want people to take it like that, don't dish it out. This is an article talk page. You don't like my user name. It is blocked. Time to move on. It would be nice if the direction were improving the article, but it doesn't seem editing is primary on Wikipedia. 2600:387:6:805:0:0:0:65 (talk) 23:22, 15 February 2017 (UTC)

Recent changes

Hello @Chhandama: I prefer to talk here over reverting again. So:

• [2] is a secondary source. There are phytochemical effects that are real.
• On Koyfman [3] An exhaustive search doesn't find any reviews that cite Koyfman for the parallel structure claim. Koyfman is widely cited but (as far as I can find) not for that particular detail. I can only find Koyfman cited for technique or for other parts of their diagrams. (Note that even this self cite ISBN 978-1-4557-3146-6 doesn't mention that specifically.) That does suggest Koyfman is credible but to cite that particular piece of text it would be better to have a review to go with it – it may be that that part of Koyfman is regarded as incorrect, or that is just unverified, or even that no one else in the world is able to understand that part of the analysis, or that others validly discovered this. I don't know.
• On Cachon & Bastin (same edit) if I remember correctly those taxa have been revised heavily since 1988 & 1996; there has been much improvement in our equipment and understanding at small scales; therefore I don't think those are sufficient by themselves. I am not suggesting removing Cachon or Bastin.
• Can you provide exact quotes from Langousis & Hill and Halliday supporting flagellar anchoring in the tsetse fly? I've added {{request quotation}}s so you can find which I mean.
• If you're going to cover the history of research on Tb from decades past (we should, this is the page) then it is also appropriate to cover research covered by Juan & Fürthauer 2018 and Büscher et al. 2017.

Invasive Spices (talk) 9 March 2022 (UTC)

It is good of you to check on my edits. My points are:

1. Statement like "Aderbauer et al 2008 and Umar et al 2010 find Khaya senegalensis is effective in vitro and Ibrahim et al 2013 and 2008 in vivo (in rats). Ibrahim et al ..." is utterly out of place and seems to not be encyclopaedic. Information on medicinal plant activity cannot possible come under the species section, nor is important to the topic. This article is about a parasite, and not preliminary tests on the effectiveness of certain plants against it. Anyway, the writing is poor, and listing citations (like Aderbauer et al 2008) is not proper writing (at least, it is "et al.").
2. On Koyfman et al. (2011) [see how I write], let's trust journal like PNAS unless there is a retraction note or rebuttal finding.
3. You are right; it can also be euglenids or euglenophytes, but "Kinetoplastida" would be wrong and should be "kinetoplastids" since we are mentioning the common names, and not the taxons.
4. Flagellar function is quite a general statement and will not be in exact quote. We can get the inference from reading the sources; look for the para "In procyclic cells, this is mediated by the flagellar connector (FC), a mobile molecular machine that tethers the tip of the new flagellum to the side of the existing flagellum and translocates with the new flagellum tip as it assembles alongside the old flagellum... [next para] In addition to orchestrating cell division in proliferating forms, dramatic changes in flagellum length and position are associated with specific developmental transformations during development in the tsetse fly ... Midgut procyclics then embark on an epic migration (panel B) that takes them through the peritrophic matrix, along the foregut to the proventriculus and from there, onward through the mouthparts, salivary ducts and ultimately into the salivary gland." By any means, feel free to copyedit if you can come up with a more coherent sentence, I did not write this part in the first place.
5. I am not describing the broad research history, but only milestone developments in the discovery. I feel an encyclopaedia needs that. If you have other landmark historical information, add them boldly. Chhandama (talk) 05:58, 10 March 2022 (UTC)

1. I think Ibrahim establishes credibility, relevance, and notability. If it was preliminary I would agree but Ibrahim is a review. On style, I am not attached to my phrasing or style choices. Do you have a suggestion? (I have seen et al abbreviated that way on Wikipedia and so I did not want to elaborate or take more space. However, it may be appropriate to do so ''et al.''. I don't care either way.)
2. On Koyfman, PNAS has a wide range of quality. I am uncertain about this detail of Koyfman's structure without a review's endorsement. Out of 16 reviews none mention the PFR⇔axoneme parallelism part.
3. I think that part should be removed because "unique to" and "taxonomic revision" don't mix.
4. I don't think flagellar attachment to the host gut is correct. I have moved [4] Langousis & Hill and Halliday forward so they don't cite the wrong part. I see the author of that text was Zephyris in 2006 [5]. Since Zephyris is still rarely active maybe a source will be forthcoming.
5. I think milestones are for the intro and section titles. We have (and should have) flagellar biophysics, antigen expression, diameter, research in 1894, trypanolytic factors, etc – you've been adding sources. We should take our signals as to level of detail from secondaries, such as the reviews I've been adding. Invasive Spices (talk) 11 March 2022 (UTC)

I admire how you pointed out the descriptive flaws in some statements; let's try to improve them, and it would be more useful if you can correct them yourselves. As to Ibrahim's works, it not about reliability or notability, it is just that medicinal plants are inappropriate where they were mentioned. To most of the points, I think you give undue reliance on secondary sources. But note that secondary sources are not always the best, as Wikipedia policy states: "Primary sources can be reliable, and they can be used. Sometimes, a primary source is even the best possible source..." And I believe it is better to edit the article than discuss every detail. Chhandama (talk) 06:11, 12 March 2022 (UTC)