biology

Hamiltosporidium

Hamiltosporidium is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Hamiltosporidium rather than just read about it. In short: Hamiltosporidium is a genus of Microsporidia, which are intracellular and unicellular parasites. The genus, proposed by Haag et al. in 2010, contains two species; Hamiltosporidium tvaerminnensis, and Hamiltosporidium magnivora.

Key takeaways

Hamiltosporidium belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Hamiltosporidium to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Hamiltosporidium from memory before moving on to harder problems.

Reference excerpt

Hamiltosporidium is a genus of Microsporidia, which are intracellular and unicellular parasites. The genus, proposed by Haag et al. in 2010, contains two species; Hamiltosporidium tvaerminnensis, and Hamiltosporidium magnivora. Both species infect only the crustacean Daphnia magna (Waterflea). D. magna and H. tvaerminnensis are a frequently used model organism to study coevolution and local adaptation.

Classification In 2010 these two species were moved to the new genus Hamiltosporidium. Previously H. tvaerminnensis was wrongly identified as Octosporea bayeri Jírovec, 1936, a parasite of D. magna described in Czech Republic which was never found again. H. magnivora was formerly named Flabelliforma magnivora Larsson, 1998 and belonged to the Flabelliforma genus, before its close phylogenetic relation to H. tvaerminnensis was discovered.

Distribution Infection of Daphnia populations by Hamiltosporidium have been recorded in the United Kingdom, Russia, Belgium and Israel (H. magnivora), as well as Sweden, Finland and Israel (H. tvaerminnensis). While its host D. magna is found all over the northern hemisphere, the two Hamiltosporidium species seem to have a limited geographic distribution. Genetic differences in host susceptibility have been suggested to contribute to the geographic distribution of H. tvaerminnensis.

Morphology and life cycle

H. magnivora reproduces sexually, while H. tvaerminnensis has an obligatory asexual status. All stages of vegetative reproduction (merogony) are enclosed by a thick plasma membrane, which is in direct contact with the cytoplasma of the host cell. In all stages the nuclei is isolated and clearly visible. The onset of the sporogony is the production of a sporophorous vesicle that is connected to the plasma membrane by tubules. Then fabelliform budding of mostly eight sporoblasts into the vesicle is initiated. Initially the wall of the encysted spore (sporont) has two layers. During the maturating of the sporont two generations of tubules are present in the episporontal space, being reduced at maturity. Mature spores of the genus Hamiltosporidium are polymorph, though pyriform and elongated rod-like spores dominate in H. tvaerminnensis while H. magnivora has lightly pyriform spores only. Pyriform spores measure 4·9–5·6 x 2·2–2·3 μm while elongated spores measure 6·8–12·0 x 1·6–2·1 μm in H. tvaerminnensis. Lightly pyriform spores in H. magnivora measure 2.34-3.03 x 4.07-4.93 μm. The polar filaments in the mature spore are more or less isofilar and the polaroplast has 2 – 3 distinct lamellar regions.

Infection The unicellular parasites infect the crustacean Daphnia magna. Both species H. magnivora and H. tvaerminnensis infect the fat body, the hypodermis and the ovaries of the crustacean. Infection can be detected by examining crushed animals under a phase contrast microscope (400x). In advanced stages of the infection spores are found in the whole body cavity of host animals, which leads to a clearly visible whitish coloration. The infection leads to reduction in the host fitness by reducing life expectancy, fecundity and competitive ability for resources among D. magna.

Transmission In H. tvaerminnensis horizontal transmission occurs after the host's death, when spores from decaying cadaver suspend in the water. Spores can persist in the environment, being able to infect new hosts after extended periods of time. Horizontal transmission could not be observed in the lab for H. magnivora but it is suggested to happen in nature as witnessed in H. tvaerminnensis. Both parasite species are vertically transmitted to asexual host offspring with a transmission rate of up to 100% and a somewhat lower transmission rate to sexual offspring (transmission rates have only been reported for H. tvaerminnensis). This means that the parasite is hardly lost in a clone lineage and also survives inside the resting eggs of its host. Thereby it can be kept in a population even though the host is resting while the habitat is dried up or frozen. Because of its combined vertical and horizontal transmission strategies, H. tvaerminnensis can reach prevalence of up to 100% in asexual populations in nature as well as in the laboratory.

Genome In 2009 a first draft of H. tvaerminnensis genome was sequenced (under the name of Octosporea bayeri). The whole genome has approximately the size of 24.2 Mega-bases (Mb). This stands in contrast to other sequenced microsporidia genomes (for example the compact 2.9 Mb genome of the obligate parasite Encephalitozoon cuniculi) which are reduced in size. It is suggested that H. tvaerminnensis genome is the largest known microsporidian genome. Almost half of the genome sequence was found to be unique for H. tvaerminnensis. Compared to smaller microsporidian genome, Gene density is rather low in H. tvaerminnensis but variable. The H. tvaerminnensis population in the Baltic Sea is genetically very homogeneous. So far there were only two main haplotype found in the whole population. Comparison of the genetic diversity to its sister species H. magnivora revealed H. tvaerminnensis asexuality.

References

Further reading Ebert, D. (2005). Ecology, epidemiology and evolution of parasitism in Daphnia. Bethesda (MD): National Library of Medicine (US), National Center for Biotechnology Information.

Illustrations

Worked examples

Example 1 — a first encounter with Hamiltosporidium

Start with the simplest possible case. Write down what Hamiltosporidium claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Hamiltosporidium before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Hamiltosporidium ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Hamiltosporidium

In research: Hamiltosporidium appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Hamiltosporidium in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Hamiltosporidium is common in secondary-school and first-year university syllabi. It links to neighbouring topics Microsporidia genera, Parasites of crustaceans, so understanding it makes those chapters shorter.
In everyday life: Look for Hamiltosporidium outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Hamiltosporidium in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Hamiltosporidium means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Hamiltosporidium out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Hamiltosporidium in simple terms?

Why does Hamiltosporidium matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Hamiltosporidium?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Hamiltosporidium.