Zaštićene vrste grada Zagreba i okolice

Pozdrav svima i dobro došli na moj blog. Ovo je zapravo prva objava koju pišem na hrvatskom jeziku, a razlog tomu je moj mali, studentski projekt koji je fokusiran na zaštićene vrste grada Zagreba i okolice. Iako su moji primarni interesi neuroznanost i molekularna biologija, smatram da je zaštita okoliša i bioraznolikosti iznimno važna, jednako kao i borba protiv klimatskih promjena, pravilno razvrstavanje otpada te prelazak na samo-obnovljive izvore energije.

Ni sama nisam sigurna kada je ideja za ovakav projekt niknula u mom umu, ali u ožujku 2020. godine, otvaranjem natječaja Studentskog Zbora Sveučilišta u Zagrebu, već sam imala konkretnu ideju kakav projekt bih htjela provesti i na koji način. Mali, studentski projekt koji bi educirao širu javnost, poglavito djecu osnovnoškolske uzrasti, o zaštićenim vrstama koje se nalaze u svijetu oko njih.

Na prvu, ovo se možda čini kao relativno dosadan projekt: malo letaka, malo otvorenih predavanja, o nekim nebitnim životinjama koje žive po šumama i rupama oko Zagreba.


Ipak, zaštićene vrste koje obitavaju u Zagrebu i okolici nisu samo životinje, već i biljke, gljive i lišajevi. I važnije, mnoge životinje koje se nalaze na listi zaštićenih životinja nisu opskurne, već bića koja srećemo toliko često, u prirodi i medijima, da možda ne bismo ni pomislili da su ugrožene i zaštićene. S nekoliko prijatelja sam raspravljala o ideji, i nakon njihovog ohrabrenja, prijavila projekt. Pandemija koronavirusa i bolesti COVID-19 me spriječila u izvođenju projekta kako sam ga inicijalno zamislila, s obzirom da se predavanja otvorenog tipa nisu mogla odvijati, pa sam taj dio projekta prebacila na snimanje edukativnog video uratka, koji je objavljen na stranicama Udruge BIUS, udruge koja je partner projekta.
Iva Čupić, poznatija na Instagramu pod imenom Samsa Critters, je ilustrirala projekt svojim sjajnim crtežima, koje možete vidjeti i u letku i videu, a umjetnica Ivana Geček je obradila grafičku pripremu za tisak.


U ovom video uratku, saznajte točnu definiciju strogo zaštićenih vrsta te ukratko u određenim vrstama životinja koje se često pojavljuju na području grada Zagreba i okolice, kao i načine na koje se možete dalje informirati o zaštićenim vrstama.

Ovaj projekt nije ni velik ni poseban, ali nadam se da će educirati barem nekoliko ljudi o posebnosti biljnog i životinjskog svijeta oko njih; ako samo jedno dijete, tijekom šetnje po Medvednici, Jarunu, Savici, Bundeku ili Maksimiru, samo jedno dijete vidi malenog crvendaća i shvati da je upravo ta vrsta zaštićena, ugrožena i posebna, i da je na nama da tu vrstu zaštitimo od izumiranja, smatrat ću da je moj projekt ispunio svoj cilj o edukaciji i proširenju kolektivne svijesti o prirodnom bogastvu kojim smo okruženi.

Short science posts | Eluding Ctenophora

Ctenophora, commonly known as comb jellies, are a rather perplexing phylum of beautiful pelagic creatures. Their evolutionary position has been debated for many years as is the origin of their nervous system (some scientists believe they are older than sponges and that sponges lost their nervous system, while others advocate the theory about the nervous system forming independently twice, once in cnidarians and once in ctenophores).
Ctenophora have two nerve nets: subepidermal and less organized subgastrodermal, which recent research identifies as a mesogleal nerve net. Nerve cells from this layer communicate with muscles by synapses and affect the locomotion of the body. The subepidermal net is denser around the mouth, the pharynx, and under the comb rows (comb rows are strips that run the length of the ctenophore body and contain cilia called “ctenes”). Ctenophore neurons can be iso- and multipolar.


They have sensory cells on the whole surface of the body and those correspond to vibrations and thermal and chemical stimuli: more receptors are located around the mouth and pharynx. Ctenophora also have an apical and aboral sensory organ. Such sensory organ consists of a statocyst, a sensor that contains a statolith that balances on four groups of long cilia connected to the comb rows. These organs help the orientation of the ctenophore body.
What’s extremely interesting is that ctenophores use different chemical signalling system than the ones described in the previous posts, mainly because these animals simply lack the neurotransmitters (and genes), such as serotonin, dopamine, noradrenaline, and acetylcholine; glutamate is the only neurotransmitter currently known to be present.


I gathered all this information from different resources, and some are sometimes contradictory or are generalizing conclusions about the whole phylum from the data of only one ctenophora species. This is the best overview I could manage, to show both the similarities and the differences of the ctenophora nervous system, when compared to the Cnidarian system. These lovely animals are not very well researched and I’m sure many wonderful breakthroughs about their anatomy, physiology, and their place in the evolutionary tree are to come.

Literature & more information:
Habdija et al: Protista-Protozoa, Metazoa-Invertebrata, Alfa, 2011, Zagreb
Norekian & Moroz Neural system and receptor diversity in the ctenophore Beroe abyssicola J Comp Neurol. 2019;1–23.
Ctenophores – quick guide
Did the ctenophore nervous system evolve independently?
Aliens in our midst

Dry lab – why I suck at it, but don’t regret taking the classes

Hi everyone, and welcome to my first post of 2021! I hope you had a nice time over the holidays and that your year started well, both personally and professionally. For my first post of the year, I decided to write about my personal experience; how it helped me, and what I learned from it.

If you follow me on social media, then you probably know most of my path in education, but for the new readers, I’m going to write a short recap: I have a Bachelor of Science in Biology and I’m currently finishing Master of Science in Molecular Biology. In my country, a Master’s degree is needed for almost any kind of employment and is a condition for applying for a Ph.D. However, only some classes are obligatory once you reach the Master’s, and in the second year, you only need to hit a certain number of ECTS; you can choose any of the classes as you please. You can choose classes that are completely unrelated to each other or a complete “module” or a couple of classes that are dedicated to a certain topic; I chose Computational Biology.

I was always interested in coding, and coding in Biology sounded like such a good idea at the time. I already took another course, titled “Bioinformatics”, where I initially fell in love with this type of work. It was a very different class, as there wasn’t that much factual studying, but rather we had a problem that we had to solve using various online tools. This class was something new and challenging. Choosing that module seemed like a normal continuation of my interests; another very important reason was also that classes weren’t held every day and also weren’t compulsory. Now, I naturally tried to attend as much as possible, but with my illness and doctor’s appointments, not worrying about doctor’s notes and attendance quotas was a bonus.

My violin plots bring all the people to the yard

There are five classes in the Computational Biology module and I chose four of them: Algorithms and Programming, Computational Genomics, Machine Learning and Statistics, and Mathematical Foundations of Computational Biology. Structural Computational Biophysics, the fifth one, honestly didn’t sound as appealing. Most of those classes were held in blocks (only Algorithms for a couple of weeks, then Statistics, then Genomics), with Mathematics being the only one we had every week for the duration of the whole semester.
Very quickly, I realised this may not be it for me; my colleagues got a hang of things quicker than me, and I felt that I’m lacking quite a lot of the prior knowledge, things I should have learned in high school, but my high school course back then didn’t focus on that. There were also memory issues, probably due to rapid changes in the medication I was taking, which was taking a priority above everything else.

The whole module is not perfect (for example, I learned quite a lot of Statistics, but not much about Machine Learning), however, I think it’s quite rewarding, especially since it’s the only opportunity we have to even check out a dry lab. It requires a lot of dedication and a lot of free time; at least now I have a reasonable (beginner’s) understanding of how to use R. What I also had, was the knowledge that sometimes, your first choices may not be the best for you and that it’s quite normal not to be exhilarated about the classes you’re taking. See, if I chose anything else, I would be plagued by the “what if-s” and now, after passing all the classes, I can confidently say I’m happy with the decision I made, but Computational Biology is just not right for me.

I’ve learned a lot and my professors were very understanding, although I honestly believe they also figured out this field isn’t my strength, but they helped me navigate all the tasks anyway. I gained a deeper understanding and appreciation of this type of research and re-discovered my love for the wet lab. I don’t know how much this knowledge will help me in the actual research, but even if I won’t do profound coding, statistical analysis is always an incredibly important skill to have.
If you had a similar experience, don’t be too hard on yourself – sometimes, we have to try out different things, even academically, to realize what kind of research interests us. Of course, at times that can be rather difficult and not everyone has the same options and opportunities. Academia can bring about a lot of stress and pressure, even without us doing the same to ourselves.

Short science posts | Hydrozoa

Hydrozoa are the last cnidarian class I’m going to write about. They can exist in two distinct shapes, as hydromedusa and hydropolyp (same as Scyphozoa and Cubozoa). Despite perhaps expecting hydrozoans to be the most advanced in both nervous and sensory systems, they don’t actually have any rophalium. Furthermore, some hydromedusae don’t even have nerve nets. However, they have two nerve rings (outer and inner) on the margins of their bells which are regarded as ganglia by some scientists.

These rings consist of neural pathways which process different sensory inputs (such as light and gravity). Aglantha digitale, a hydrozoan species, has been reported to have as much as 14 distinct neural pathways. A. digitale is also distinct from the other species in the class by having two swimming “modes” – slow (which is a characteristic for all hydrozoan) and escape mode. Transmission through giant ring neurons is responsible for both modes, but the escape mode requires a stronger contraction. The slow swim mode is activated by the input from the pacemaker, which triggers slow calcium spikes. Direct mechanical nerve ring stimulation by tentacles triggers fast sodium spikes. In short, giant ring neurons are capable of generating two different kinds of action potentials.

bsh

Gap junctions are also present in (and only in) Hydrozoa, and they transfer electrical signals through the musculature. Furthermore, I would like to emphasize that despite some hydromedusae not having a nerve net, some in fact do, and so do hydropolyps. In polyps, however, some groupings of the neurons could be found around their mouth.

Literature & more information:
Habdija et al: Protista-Protozoa, Metazoa-Invertebrata, Alfa, 2011, Zagreb
Do jellyfish have central nervous systems?
Jellyfish nervous systems

Short science posts | Cubozoa (most advanced cnidarian nerve system)

Cubozoa, or box jellyfish, are another cnidarian class. Their name stems from their distinct cube-like shape. Cubozoa are also distinct from other cnidarian because their venom can be fatal to humans. As with all cnidarians, box jellyfish have two nerve nets and, like Scyphozoa, rophalia. However, box jellyfish also have a distinct nerve ring, as well as more developed eyes that consist of a lens, cornea, pupil, and a layer of retinal cells. Altogether, Cubozoa have 24 eyes, which makes them the most advanced cnidarian class in the sensory aspect.

Rophalia are mutually connected via the mentioned nerve ring. This ring is believed to be an integration center for the swimming, visual, and tentacle systems; it is comprised of oversized neurons, as well as some smaller neurites.
The communication between the nerve net and jellyfish muscles is regulated by chemical synapses.

Most of the information relating to Cubozoa, I already mentioned in the previous post about Scyphozoa, so I only wanted to relay the main differences between the two. These two classes are so similar that, until recently, they were actually considered one class.

Literature & more information:
Habdija et al: Protista-Protozoa, Metazoa-Invertebrata, Alfa, 2011, Zagreb
The ring nerve of the box jellyfish Tripedalia cystophora
Do jellyfish have central nervous systems?
Jellyfish nervous systems


Short science posts | Scyphozoa – more advanced nervous system

Scyphozoa (true jellyfish) are much more interesting (in a neurobiological way) than previously described corals. One major difference is that Scyphozoa are pelagic animals, which means they are not fixed to the ground. They also have two diffuse nerve nets (subepidermal and subgastrodermal) that consist of bipolar and multipolar neurons – the impulse conduction has been measured at 0,15 m/s. Both nets coordinate the movements of an animal towards the food. Some scientists, however, differentiate one diffuse and one motor nerve net. The motor net is in charge of the activation of muscle contractions after receiving signals from the so-called pacemaker organs (which are in charge of the swimming rhythm). The diffuse net, in this case, is in charge of marginal tentacle contraction and it is also believed it communicates sensory information to jellyfish musculature. Neurons of the motor nerve net are connected by chemical synapses, while neurons of diffuse nerve net are connected by peptidergic synapses that were noted in Anthozoa as well.

Sycphozoa also have much more developed sensory organs than any of the animals previously mentioned. These sensory structures are called rhopalia and they are located on the edges of the jellyfish bell – there are usually four of them (or a number that’s a multiple of four). Rhopalia contain multiple sensory receptors – statocyst (balance receptor), ocelli (light sensitivity), a mechanoreceptor, a chemoreceptor, and aforementioned pacemaker neurons.

I would also like to note here that some authors (I’m referring here to the article “Do jellyfish have central nervous systems?” by R. A. Satterlie) believe this kind of nerve net explanation is rather simplified and that there exist some evidence suggesting that jellyfish have a centralized nervous system, mainly that rophalia are in fact rudimentary ganglia and could be regarded as integrative centers. However, any communications between rhopalia themselves exist only through the nerve nets.

Literature & more information:
Habdija et al: Protista-Protozoa, Metazoa-Invertebrata, Alfa, 2011, Zagreb
Do jellyfish have central nervous systems?
Jellyfish nervous systems

Studying | My favourite online courses

I don’t know about you, but I just love doing online courses, especially when they deal in subjects I don’t get to explore in my college courses. Over the years, I tried many different platforms, such as YouTube, Google Digital Garage, Khan Academy, Udemy, and, my favourite, Coursera. As a matter of fact, I discovered Coursera back when they started in 2012; most of the courses I took were on topics of Neuroscience and Molecular Biology. At first, courses and certificates were completely free, but with time, they started offering paid vs. free, as well as many specializations and even some college degree courses. However, many of the courses are still available to watch and do quizzes, just without the certification.

Disclaimer: this post is not sponsored by Coursera.

Synapses, Neurons and Brains – available here

This course, offered by Hebrew University of Jerusalem, is actually the very first course I took, and at the time was one of the rare Neuroscience courses. I have only good memories about this one – it is a good introductory course into the field and the professor explained the curriculum very well. Also, the course mentions real projects that deal with neural networks and brain reconstructions, such as Blue Brain Project. I didn’t mention this previously, but every course also comes with subtitles (in English at least) and transcripts, so you can follow along easier.

The Addicted Brain – available here

The Addicted Brain (by Emory University) is another course appropriate for beginners in this topic – I was initially interested not only because of the topic of addiction, but also because various mechanisms of how drugs interact with the brain were presented. The course also covers the topic of drugs in society, although this part mainly concerns United States of America. Also, I don’t know if this is something that’s important to you, but I followed professor’s narration easily – his voice is calming and he speaks very understandably.

Medical Neuroscience – available here

Medical Neuroscience (by Duke University) is not only the most advanced course of the ones mentioned here, but the most advanced course I ever took. Actually, I started it once or twice before, but dropped out because it required a lot of time and dedication that, at times, I just didn’t have due to my University obligations. This course is really extensive and requires some before-knowledge, but is also very satisfactory when you finish it. The only problem I had with this one is that sometimes I felt that questions in quizzes were asking for details that to me seemed almost overlooked in the videos. However, I felt like this course was quite important for my studies, since I have a strong interest in Neuroscience, but lacked the medicinal perspective.

All quizzes are multiple choice answers, with usually one correct answer (sometimes more correct answers). I vaguely remember some questions where you had to connect some phrases (like 1-d, 2-c, etc) as well, but haven’t came across those recently. Also, the quizzes I did were never timed and you can take one quiz 3 times every eight hours (they keep your highest score).

Coursera also offers financial aid – you can fill out an application where you explain why is the course you’re applying for important to you and why you can’t afford it. So far, I’ve heard of many positive experiences where they gave grants.

There are also two Neuroscience related courses I am planning to take – Human Neuroanatomy (to revise a bit) and Computational Neuroscience, which deals with using Python in Neuroscience research. I would very happily review those for you, in a greater detail, if this is something you’d like to read about!

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What is your opinion on online courses – do you think they’re useful or a waste of time? Did you perhaps take some of the ones I mentioned? If yes, I would love to hear from your!

Short science posts | What is a nerve net?

A nerve net is a type of nervous system that consists of many neurons but there is no brain or cephalization. Nerve nets are found in animals with radial symmetry (Cnidaria) and biradial symmetry (Ctenophora). Despite being called a net, there sometimes exist some groupings of neural cells in some Cnidaria classes, which I will write more about during the next couple of weeks.
Cnidaria are specific due to their specialized organelles, cnidocytes, which they utilize to hunt for food or use for securing itself to a surface. Some cnidocytes contain toxins that can paralyze their prey (the burning sensation you may have felt when touching a sea anemone 😉).
As a rule, Cnidaria have two diffuse nerve nets, one in the epidermal layer and a second one in the gastrodermal layer. In between these two layers is the mesoglea, a layer that functions as sort of a skeleton. The epidermal net consists of bipolar and multipolar nerve cells, while the gastrodermal net is made up of only multipolar cells.

Cerianthus membranaecus (known as cylinder anemone or coloured tube anemone)

Cnidarian nerve systems are fascinating but also quite unexplored. What is known is that nerve cells consist of two types of neurons, sensory neurons that respond to stimuli and motor neurons which ultimately trigger a response. Chemical synapses exist and provide the communication between the neurons. Hormones have also been reported in some cnidarians (steroids, neuropeptides) but it is still not known how exactly these signalling molecules work.

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In the next couple of weeks, I will write a post about every cnidarian class and also ctenophores, focusing on their nervous and sensory systems. If you have any questions or would like me to focus on something, please let me know!

Literature & more information:
Habdija et al: Protista-Protozoa, Metazoa-Invertebrata, Alfa, 2011, Zagreb
Endocrine-like Signaling in Cnidarians: Current Understanding and Implications for Ecophysiology
Evolution of sensory structures in basal metazoa

Reading | Blood Work by Holly Tucker

Blood Work: A Tale of Medicine and Murder in the Scientific Revolution by Holly Tucker is a book that I first read almost 10 years ago. I got it as a gift from a dear friend, for my birthday during the time I was a student at School of Medicine (as you can guess, I decided to start anew and switch to Biology). However, this book has always stayed with me, not only because it was the first book of this genre I’ve read – I loved it because I thought it was the perfect mix of history, medicine, and macabre.

Blood Work follows a fascinating tale of the history of human transfusion, something what in today’s world we almost take for granted. Back in high school, we learned all about Rh factor and blood types (and how there is a possibility of A and B parent having an O or AB child) and voluntary blood donations are common occurrence in my country. Despite all this, I never wondered when did the actual blood transfusion procedures start and how did physicians know whose blood to use.

In the book, we follow Jean-Baptiste Denis, a 17th century French physician who administrated first documented transfusion. Since this transfusion included using sheep’s blood, it was called a xenotransfusion, which is a term that describes blood transfusion from one species to another. This experiment was successful, probably due to small amount of transfused blood and, I dare say, luck, since at the time, blood groups and agglutination were not known facts.
Denis’ last transfusion experiment is, however, the one we learn about in a detail – after trying to treat an illness of psychiatric nature, and transferring a large amount of calf blood, his patient dies, and he is accused of murder. Denis was ultimately acquitted (with a true crime worthy twist in the case), but all further transfusions were banned, first by French government, then by English and even the Pope.

Blood Work doesn’t focus solely on this event – the writer masterfully describes political events of the time, both in France (rivalry with another physician, Henri-Martin de la Martinière, tensions in French Academy of Sciences founded by Louis XIV) and abroad (a competition between French and English Academies), as well as the religious ones (“playing God”, fear that this kind of transfusion could produce some sort of half-human half-animal creature). Furthermore, as Neil Blumberg wrote in his review for Journal of Clinical Investigations, these kinds of experiments were primary conducted due to the belief that transfusion could treat, or even cure,  mental illness, sometimes we now know is not possible.

Lastly, it doesn’t actually matter if you have health and/or science background to find this book interesting, as long as your’re interested in history and historical non-fiction. Blood Work offers a captivating look on the beginnings of one of the most important medical procedures in the world and does it so vividly you almost feel like you’re transported to Paris, in the middle of the scientific revolution.

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I would very much liked to hear your opinion – did you read this book, and if yes, did you like it as much as I did?
Do you have similar book recommendations?  Please let me know in the comments 🙂

Cave animals in Croatia

Hi everyone, and welcome to another caving post! Today, I would like to write a bit about animals that live almost exclusively in caves in Croatia and region. So, what is so special about this region?  Dinarides, or Dinaric Alps, is a mountain range on the western part of Balkan peninsula; it is about 650 km long and is made of limestone and dolomite (karst). The mountain is a home for many different species, both animal and plant alike, with some of them being endemic for the region.

A view from inside to outside of the cave; framed arch with the blackness of the cave forming an outside frame, and sky and forest being the picture in the centre.
The cave near the Big Natural Bridge; a view from the inside.


Animals in cave some specific features, such as slower metabolism, lost of sight and pigment, and lost of circadian rhythms. Also, we can roughly divide them as animals that live in water and the ones that live on rocks and/or the ground. Furthermore, we can divide them in the following categories: genuine inhabitants (they live their whole lives in caves), inhabitants which can have epigean populations (they can live both in and out), occasional inhabitants (examples include hibernation and seeking shelter), and accidental inhabitants. When looking in numbers, there are 455 described cave inhabitants in Croatia, with many species of beetles leading the board, followed by crustaceans and snails.


However, Dinaric karst is a home to many one of the kind species, such as the only  underground freshwater sponge in the world, Eunapius subterraneus (Ogulin cave sponge), and Congeria spp, the only underground freshwater bivalves. There are two species of Congeria, Congeria jalzici that is found in north Velebit and Congeria kusceri that lives in southern parts of Dalmatia and Dinara. And if you think this is the end of the “the only underground freshwater weird looking animal”, you would be wrong, because Croatia is also home to Marifugia cavatica, Dinaric cave-dwelling tubeworm. And to Velkovrhia enigmatica (also found in Slovenia and Bosnia and Herzegovina) which is the only cave hydrozoan (Cnidaria) in the world.

There are also two very interesting species found in deep caves on Velebit – Troglocladius hajdi (Diptera without eyes, and yes, it flies) and Croatobranchus mestrovi (pictured below, it’s basically a white leech). I already wrote about Proteus in another post, so I’m purposefully omitting them here.


Now, you might wonder, what’s the big deal? Well, most of these species are not very well researched and are still a big enigma to scientists. For many of these, their genomic DNA is not yet sequenced, and their evolutionary relations to species in the same taxa are not completely clear. There is also a question of how exactly these species survive, mainly what exactly they eat, since caves are not exactly blooming with life – there are no plants, but there is some bacteria.

Have you ever heard (or seen) of these species? Would you like to know more about them? Please let me know in the comments!

 

Literature & more information:

Cave fauna
Pijavica Croatobranchus mestrovi
Diptera