The dinoflagellates They are organisms of the Protista Kingdom whose main characteristic is that they present a pair of flagella that help them to move in the middle. They were first described in 1885 by the German naturalist Johann Adam Otto Buetschli. They are a fairly large group, including photosynthetic, heterotrophic, free-living organisms, parasites, and symbionts..
From the ecological point of view they are very important, since together with other microalgae, such as diatoms, they constitute phytoplankton, which in turn is the food of many marine animals such as fish, mollusks, crustaceans and mammals.
Likewise, when they proliferate exaggeratedly and uncontrollably, they give rise to a phenomenon called "Red Tide", in which the seas are stained in various colors. This constitutes a serious environmental problem, since it greatly affects the balance of ecosystems and the organisms that inhabit them..
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The taxonomic classification of dinoflagellates is as follows:
Domain: Eukarya.
Kingdom: Protista.
Super sharp: Alveolata.
Edge: Miozoa.
Subphylum: Myzozoa.
Dinozoa
Superclass: Dinoflagellata
Dinoflagellates are single-celled organisms, that is, they are made up of a single cell. They vary in size, some are so small that they cannot be seen with the naked eye (50 microns), while others are slightly larger (2mm)..
In dinoflagellates two forms can be found: the so-called armored or tecados and the naked ones. In the first case, the cell is surrounded by a resistant structure, like an armor, made up of the biopolymer cellulose.
This layer is known as "teak". In naked dinoflagellates there is no presence of the protective layer. Therefore, they are very fragile and susceptible to harsh environmental conditions..
The distinctive feature of these organisms is the presence of flagella. These are cell appendages or projections that are used primarily to provide mobility to the cell..
In the case of dinoflagellates, they present two flagella: transverse and longitudinal. The transverse flagellum surrounds the cell and gives it a rotating movement, while the longitudinal flagellum is responsible for the vertical movement of the dinoflagellate..
Some species have bioluminescence genes in their DNA. This implies that they are capable of emitting a certain glow (like some jellyfish or fireflies).
Likewise, like any eukaryotic organism, the genetic material (DNA and RNA) is packaged within a structure known as the cell nucleus, which is delimited by a membrane, the nuclear membrane..
Now, the organisms belonging to this superclass have very particular characteristics that make them unique within eukaryotes. In the first place, DNA is found perennially making up the chromosomes, which remain condensed at all times (including all stages of the cell cycle)..
In addition, it does not have histones and the nuclear membrane does not disintegrate during the process of cell division, as it does in the case of other eukaryotic organisms..
In a view with the electron microscope, the presence of various cytoplasmic organelles, typical in any eukaryote, can be observed within the dinoflagellate cells..
These include: Golgi apparatus, endoplasmic reticulum (smooth and rough), mitochondria, storage vacuoles, as well as chloroplasts (in the case of autotrophic dinoflagellates).
The Dinoflagellata superclass is broad and encompasses a large number of species, some very different from others. However, they agree on certain characteristics:
The group of dinoflagellates is so broad that it does not have a specific pattern of nutrition. There are species that are autotrophic. This means that they are able to synthesize their nutrients through the process of photosynthesis. This occurs because between their cytoplasmic organelles they have chloroplasts, within which there are chlorophyll molecules..
On the other hand, there are a few that are heterotrophs, that is, they feed on other living beings or on substances produced by them. In this case, there are species that feed on other protists belonging to the portozoans, the diatoms or even the dinoflagellates themselves..
Likewise, there are some species that are parasites, such as those belonging to the Ellobiopsea class, which are ectoparasites of some crustaceans..
This aspect is quite diverse. There are species that are free-living, while there are others that form colonies.
Similarly, there are species that establish endosymbiotic relationships with members of the Anthozoa class of the phylum cnidarians, such as anemones and corals. In these partnerships, both members mutually benefit and need each other to survive..
An example of this is the species Gymnodinium microoadriaticum, which abounds in coral reefs, contributing to their formation.
In most dinoflagellates, reproduction is asexual, while in a few others, sexual reproduction can occur..
Asexual reproduction occurs through a process known as binary fission. In this, each cell divides into two cells exactly the same as the parent..
Dinoflagellates have a type of binary fission known as longitudinal. In this type, the axis of division is longitudinal.
This division is varied. For example, there are species like those of the genus Ceratium, in which a process called desmochisis occurs. In this, each originating daughter cell maintains half of the parental cell wall.
There are other species in which something called eleutherochisis occurs. Here the division occurs within the mother cell and after division each daughter cell generates a new wall or a new theca, in the case of thecae species..
Now, sexual reproduction occurs by fusion of gametes. In this type of reproduction, the union and exchange of genetic material between two gametes occurs..
Dinoflagellates have various types of pigments in their cytoplasm. Most contain chlorophyll (types a and c). There is also the presence of other pigments, among which the xanthophylls peridinin, diadinoxanthin, diatoxanthin and fucoxanthin stand out. There is also the presence of beta-carotene.
A large number of species produce toxins that can be of three types: cytolytic, neurotoxic or hepatotoxic. These are highly toxic and harmful to mammals, birds, and fish..
The toxins can be consumed by some shellfish such as mussels and oysters, and accumulate in them at high and dangerous levels. When other organisms, including man, ingest shellfish contaminated with the toxin, they can present a poisoning syndrome that, if not treated in time and properly, can have a fatal outcome..
All dinoflagellates are aquatic. Most species are found in marine habitats, while a small percentage of species can be found in fresh water. They have a predilection for areas where sunlight reaches. However, specimens have been found at great depths.
Temperature does not seem to be a limiting element for the location of these organisms, since they have been located both in warm waters and in extremely cold waters such as those of polar ecosystems..
The life cycle of dinoflagellates is mediated by environmental conditions, since depending on whether they are favorable or not, various events will occur.
Likewise, it has a haploid and a diploid phase..
In the haploid phase, what happens is that a cell undergoes meiosis, generating two haploid cells (with half the genetic load of the species). Some scholars refer to these cells as gametes (+ -).
When environmental conditions are no longer ideal, two dinoflagellates unite, forming a zygote known as a planozygote, which is diploid (complete genetic load of the species).
Later, the planozygote loses its flagella and evolves to another phase that is called the hypnozygote. It is covered by a much harder and more resistant teak and is also full of reserve substances.
This will allow the hypnozygote to stay safe from any predator and protected from adverse environmental conditions for a long time..
The hypnozygote is deposited on the seabed waiting for environmental conditions to become ideal again. When this happens, the teak that surrounds it breaks and this becomes an intermediate stage known as planomeiocito.
This is a short-lived phase, as the cell quickly returns to its characteristic dinoflagellate shape..
Dinoflagellates include five classes:
The so-called "Red Tide" is a phenomenon that occurs in bodies of water in which certain microalgae that are part of phytoplankton proliferate, especially those of the group of dinoflagellates..
When the number of organisms increases considerably and they proliferate uncontrollably, the water is usually stained in a range of colors, among which may be: red, brown, yellow or ocher.
Red tide turns negative or harmful when proliferating microalgae species synthesize toxins that are harmful to other living things. When some animals such as mollusks or crustaceans feed on these algae, they incorporate the toxins into their body. When some other animal feeds on these, they will suffer the consequences of ingesting the toxin.
There is no preventive or remedial measure that will completely eliminate red tide. Among the measures that have been tried are:
Organisms belonging to the group of dinoflagellates are not pathogens in themselves, but, as mentioned above, produce toxins that greatly affect humans and other animals..
When there is an increase in the amount of dinoflagellates in some region of the sea, so does the production of toxins, such as saxitoxins and goniautoxin.
Dinoflagellates, which are an important and predominant part of phytoplankton, are part of the diet of crustaceans, mollusks and fish, in which toxins accumulate dangerously. These pass to humans when they feed on an infected animal.
When this occurs, what is known as shellfish poisoning syndrome is generated..
It occurs when mollusks infected with the various toxins synthesized by dinoflagellates are consumed. Now, there are several types of toxins and the characteristics of the syndrome to be generated depend on these..
Causes paralyzing seafood poisoning. It is produced mainly by the species Gymnodinium catenatum and several of the genus Alexandrium.
Death usually comes as a result of respiratory arrest.
Causes neurotoxic poisoning. It is synthesized by species belonging to the genus Karenia.
It is the cause of diarrheal poisoning from shellfish consumption. It is produced by the species of the genus Dinophysis.
Causes ciguatera poisoning by eating fish. It is synthesized by the species Gambierdiscus toxicus, Ostreopsis spp Y Coolia spp.
Symptoms begin to appear between 30 minutes and 3 hours after the contaminated food is ingested. This is because the toxin is rapidly absorbed through the oral mucosa..
Depending on the amount of toxin ingested, the symptoms may be more or less severe.
The elimination half-life of the toxin is approximately 90 minutes. The reduction of toxin levels in the blood to safe levels can last a period of 9 hours.
Unfortunately there is no antidote for any of the toxins. Treatment is indicated to relieve symptoms, especially respiratory symptoms, as well as to eliminate the toxin.
One of the usual measures is to induce vomiting, to eliminate the source of the poisoning. Activated charcoal is also usually administered, since it is capable of absorbing toxins, which are resistant to the action of gastric pH..
Likewise, abundant fluids are administered, which seeks to correct the possible acidosis, as well as accelerate the excretion of the toxin through the kidneys..
Poisoning by any of these toxins is considered a hospital emergency, and as such should be treated, providing the affected person with specialized medical attention immediately..
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