Dale Fort Blog Number 9

2 07 2012

Seaweed Research at Dale Fort

Ascophyllum nodosum (egg wrack) and to a lesser extent, Laminaria digitata (oarweed), L. hyperborea  (tangle) and Fucus serratus (serrated wrack) are marine algal species used in the commercial production of seaweed extracts used in agriculture.

 

 

 

 

These extracts are known to protect crops species against drought, viral infections and attack by  nematodes (see Blog Number 1).  Their use could have profound consequences for humans.  Imagine manipulating food crops so that they could withstand dry conditions. The drier parts of the world currently of no use for agriculture might become fertile farmland.

Betaines are proteins that have been shown to be important constituents of these extracts.  The precise mechanisms of how they work in drought protection are not known but it might be like this:

When plants are water stressed one of the problems is that their enzymes change shape.  Enzymes are very large protein molecules and for them to function it’s vital that they retain the correct shape.  They have to be capable of fitting into the corresponding shape of the molecule they are to help modify; rather like a key fitting into a lock.

 

 

 

 

Large protein molecules are so big that the retention of their gross structure requires them to be supported and this is where water is so useful.

Water molecules have a small negative charge at the oxygen end and a small positive charge at the hydrogen ends.

 

 

 

 

 

The oppositely charged ends of the molecules have a tendency to stick together. The process is known as hydrogen bonding and it is the reason why water is the only liquid which expands when it freezes.  As it cools the molecules slow down and the electrical attractions cause them to line up and  form the more open crystalline structure of ice.

In a cell they form a similar sort of matrix which is able to surround big protein molecules and support them.

One of the problems of desiccation is that these watery support structures are lost.  The enzymes change shape and do not recognise their substrates.  This is not great for the plant and ultimately leads to death.

Betaines are also proteins and it is believed that in times of drought stress they are able to wrap themselves around other proteins (like enzymes) and help preserve the correct shape.

 

 

 

There had been no study made on whether there are variations in the betaine contents of seaweeds based on either the place or date of collection.  So we did one.

  Samples of each of the four species were collected from widely separated areas at different times of the year.

In the case of A. nodosum, Steve also made monthly collections over 18 months from Cliff Cottages Beach near Dale.

The betaines detected in the various collections of the same species showed little variation, although in the case of A. nodosum, glycinebetaine was found as a minor constituent in some samples, but was not detected in others. Trigonelline was found in all the tested samples of the two Laminaria species; this is, to our knowledge, the first record of this betaine in marine algae. With the exception of trigonelline in the Laminaria species, the betaine yields from the various samples of L. digitata, L. hyperborea and F. serratus showed little variation, regardless of either the place or date of collection. The trigonelline contents of the Laminaria species collected at one location (Finavarra, Ireland), in particular of L. hyperborea, appear to be substantially greater than those from the other places of collection.

In the case of A. nodosum, the betaine yields from samples collected at Dale were much higher than those from the other places of collection, which were very similar to each other.  We don’t know why Dale had higher yields.   There was no clear indication of seasonal variation in betaine yields from A. nodosum.

So, some obscure substances from some common seaweeds might have huge implications for food production.  It’s very difficult to tell where a piece of basic research might lead but there are enough examples of serendipitous discoveries* to remind us that the pursuit of knowledge and understanding is never wasted effort.  It’s what makes our species  worthwhile.

*Penicillin, microwaves ovens, Viagra, The Dead Sea Scrolls, LSD, America; you may not agree that all of these are  serendipitous but it’s mainly a matter of opinion anyway.

Anyone who wants to read the original paper can find it here:

Betaine Yields from Marine Algal Species Utilized in the Preparation of Seaweed Extracts Used in Agriculture

Gerald Blunden, Peter F. Morse, Imre Mathe, Judit Hohmann, Alan T. Critchley and

Stephen Morrell

Natural Product Communications

2010 Vol 5 No. 4  581  –  585

Look out for the next exciting blog.  Even I don’t know what it will be about because we live life close to the edge at Dale Fort.