Nannochloropsis

Key takeaways

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

Reference excerpt

Nannochloropsis is a genus of algae comprising six known species. The genus in the current taxonomic classification was first termed by Hibberd (1981). The species have mostly been known from the marine environment but also occur in fresh and brackish water. All of the species are small, nonmotile spheres which do not express any distinct morphological features that can be distinguished by either light or electron microscopy. The characterisation is mostly done by rbcL gene and 18S rRNA sequence analysis. The algae of the genus Nannochloropsis differ from other related microalgae in that they have chlorophyll a and completely lack chlorophyll b and chlorophyll c. In addition they are able to build up a high concentrations of a range of pigments such as astaxanthin, zeaxanthin and canthaxanthin. They have a diameter of about 2 to 3 micrometers and a very simple ultrastructure with reduced structural elements compared to neighbouring taxa. Nannochloropsis is considered a promising alga for industrial applications because of its ability to accumulate high levels of polyunsaturated fatty acids. Moreover, it shows promising features that can allow genetic manipulation aimed at the genetic improvement of the current oleaginous strains. Various species of Nannochloropsis indeed are transfectable and there has been evidence that some strains are able to perform homologous recombination. At the moment it is mainly used as an energy-rich food source for fish larvae and rotifers. Nevertheless, it has raised growing interest also for the investigation of biofuel production from photosynthetic organisms. (see Nannochloropsis and biofuels). Nannochloropsis is actually in use as food additive for human nutrition and it is also served at Restaurant "A Poniente" of El Puerto de Santa María (Cádiz, Spain) close to the natural environment where Nannochloropsis gaditana was first isolated and still grows. A 2020 study suggests it could be used for a highly performant, sustainable fish-free feed for farmed fish.

Species The species currently recognised are:

Nannochloropsis australis Fawley, Jameson & Fawley 2015 Nannochloropsis granulata Karlson & Potter 1996 Nannochloropsis limnetica Krienitz et al. 2000 Nannochloropsis oceanica Suda & Miyashita 2002 Nannochloropsis oculata (Droop 1955) Hibberd 1981 The species Nannochloropsis gaditana and Nannochloropsis salina were reclassified as Microchloropsis gaditana and Microchloropsis salina, respectively, in 2015.

Sequenced genomes The scientific community has obtained the genomic sequence of different strains of Nannochloropsis belonging to two species: N. gaditana and N. oceanica. A genome portal based on the N. gaditana B-31 genome allows accessing much of the genomic information that concerns this micro-organism, moreover dedicated web pages are also available for the genomes of N. gaditana CCMP526 Archived 2013-10-29 at the Wayback Machine and N. oceanica CCMP1779. The genomes of the sequenced Nannochloropsis strains were between 28.5 and 29 Mega bases long, they had high density of genes, reduced intron content, short intergenic regions and very limited presence of repetitive sequences. The genes of the two species share extended similarity. The analysis of the genomes revealed that these microalgae have set of genes for the synthesis and incorporation in the cell wall of cellulose and sulfated fucans and that they are able to store carbon in polymers of β-1,3- and β-1,6-linked glucose called chrysolaminarin. An NMR analysis of whole algal cells which were cultivated in autotrophic growth reports evidence of the presence of cellulose in the cell wall and of mobile chrysolaminarin, probably accumulated in solution in vacuoles inside the cell. Comparison between the lipid metabolic genes of N. gaditana and of red/green/brown algae and diatoms provided some insights into the exemplary lipid production of Nannochloropsis cultures. The comparisons indeed highlighted the presence of an expanded repertoire of some of the genes involved in TAG assembly in Nannochloropsis. Numerous TAG lipases, which can affect TAG metabolism through either TAG degradation or lipid remodeling, were identified in Nannochloropsis, many of them belonging to a gene family which seems to be exclusive of Nannochloropsis. Analysis of the genomic data suggested the presence in both the two species of Nannochloropsis of regulatory RNA and in particular miRNA. Various orthologs of known blue light sensing proteins were found in the genomes of Nannochloropsis suggesting possible circadian regulation. A research community from Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT [1]), Chinese Academy of Sciences, sequenced and compared six Nannochloropsis genomes that include two N. oceanica strains (IMET1 and CCMP531) and one strain from each of four other recognized species: N. salina (CCMP537), N. gaditana (CCMP526, which was previously reported), N. oculata (CCMP525) and N. granulata (CCMP529). They found that the six genomes share key oleaginous traits, such as the gene dose expansion of selected lipid biosynthesis genes compared to green algae Chlamydomonas. The most prominent example of gene dose expansion is Diacylglycerol acyltransferase (DGAT), which catalyzes the last step of triacylglycerol (TAG) synthesis. There are 13 DGAT genes in Nannochloropsis, representing the highest gene dose in known genomes. Through a comprehensive phylogenetic analysis, researchers proposed that among the 11 DGAT-2s, one gene might originate from the red algae related secondary endosymbiont, four from green algae related endosymbiont, and the other six from the eukaryotic host genome. In addition, a large proportion (15.3%) of TAG biosynthesis related genes were acquired by Nannochloropsis via horizontal gene transfer (HGT) from bacteria. Therefore, multiple genome pooling and horizontal genetic exchange, together with selective inheritance of lipid synthesis genes and species-specific gene loss, have led to the enormous genetic apparatus for oleaginousness and the wide genomic divergence among present-day Nannochloropsis spp.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Nannochloropsis

Start with the simplest possible case. Write down what Nannochloropsis 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 Nannochloropsis 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 Nannochloropsis 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 Nannochloropsis

In research: Nannochloropsis 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 Nannochloropsis 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: Nannochloropsis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Ochrophyta, Ochrophyte genera, so understanding it makes those chapters shorter.
In everyday life: Look for Nannochloropsis 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.

How to study Nannochloropsis in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Nannochloropsis 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 Nannochloropsis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Nannochloropsis in simple terms?

Nannochloropsis is a genus of algae comprising six known species. The genus in the current taxonomic classification was first termed by Hibberd (1981).

Why does Nannochloropsis 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 Nannochloropsis?

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 Nannochloropsis.