A Trip Which Sparked Curiosity (Part 1)

The King of Saxony’s Crown

 Very recently I visited the Natural History Museum in London for the first time in six years. I was immediately transported back to the last time I was there, completely filled with awe and wonder.

Investigating many of the exhibits sparked my curiosity and so I thought I would share with you, in a series of posts, what I found interesting and the further information I have discovered as a result of my curiosity.

The King of Saxony Bird of Paradise

I am going to start with one of the most peculiar of my discoveries; Pteridophora alberti, or more commonly known as the King of Saxony Bird of Paradise. What caught my eye about this tiny bird was the huge pair of head wires attached above its eyes which are, in most cases, double the length of the bird itself.[1]head-wires

These head wires consist of a shaft with fused barbs down one side, which have been greatly modified for their purpose; to attract a mate. As many of you may already know, in the animal kingdom, success is measured by the number of genes an individual passes down to the next generation, via the offspring, and the male King of Saxony Bird of Paradise has a very unusual way of increasing his chances of success.

The Dance of Love

A mating dance is not uncommonly associated with particular species of birds, however the mating dance of the King of Saxony Bird of Paradise is second only to that of the Magnificent Riflebird (which, let’s face it, isn’t a surprise based on its name). While many birds, like the Magnificent Riflebird and the Superb Bird of Paradise (again, another case of an appropriately named bird) show off their genetic prowess by puffing up their feathers and startling the poor female with bright flashes of colour[2], the King of Saxony Bird of Paradise takes a different approach.

A lonely male sits on a branch high in the canopy and waits for a female to pass by. 2ndWhen one catches his eye, he flies down to his chosen courtship branch and prepares for the performance.[1] He gets excited. His first display is a bit of a warm up, he bops up and down on his branch rhythmically, trying to attract the much sought after attention of the female, competing with other males in proximity. Increasing in emotion, the male King of Saxony then begins his call. Starting with a low buzz, his mating call not only rises in volume but also in pitch, eventually building to an incredibly ear-piercing screech, which, combined with several clicking sounds, will hopefully win over the female.

However, the female has not yet been wooed, and the spectacle is only just beginning. As the now fully enthused male King of Saxony reaches the climax of his dance, he puffs up his feathers and his head wires begin to rise. The sound of buzzing heightens, the magnificent head wires are now extended above the top of his head. Screeching begins, the feathers on his head puff up, and he brings his head wires perpendicular to the sides of his head. With a screech that gives the rainforests of Papua New Guinea its characteristic sound, the male King of Saxony waves his head wires in a well rehearsed manner, as to make the female fall instantly in love with him.

The Evolutionary Success

This routine has been practised and perfected and, subsequently, passed down through the generations, but it has not always been like this.

In the forests of Papua New Guinea, the climate is warm, food is abundant (at least for the King of Saxony Bird of Paradise) and predation is at a relatively low level. Therefore, the evolution of the King of Saxony has not been guided by the need to thermoregulate, or hunt, or even blend into surroundings [3], but by its ability to attract a mate. The female King of Saxony Bird of Paradise finds the male’s outrageous head wires and ear-piercing screeches hugely attractive (whatever floats your boat I guess), so that is what has steered evolution to produce this incredibly interesting looking bird. For a male King of Saxony Bird of Paradise, the longer your head wires and louder your call, the more likely you are to succeed in passing your genes to the next generation, and the lack of parental help the males give the females, means the males can continue to give their genes to several females in a year, further increasing their success.

Furthermore, it is also as a result of sexual selection that the female counterparts of3rd brightly coloured male birds are always so dull in comparison (sexual dichromatism). Females are picky when choosing a mate; they want the best genetic package for their offspring, so when it comes down to it, what the females look like doesn’t matter to male birds, as long as they get to pass down their genes. Females want the brightest, best looking and sounding male to hopefully pass strength, resilience and attractiveness down to their offspring, so the chances of survival are much greater. It has also been scientifically proven that, in birds, there is a positive correlation between brighter colours and better health.[4] Females also need to be able to camouflage themselves when sitting on their eggs, which could be another explanation for sexual dichromatism.

Conclusion

In conclusion, what I first thought was just a small bird with a big hair issue, is actually an incredibly interesting example of sexual selection, and just goes to show how far evolution will go to ensure the highest chance of success in the animal kingdom.

[1] BIRDS OF PARADISE PROJECT. (2016) King Of Saxony Giant Head Wires. [Online] Available from: http://www.birdsofparadiseproject.org/content.php?page=77 [Accessed: 24th October 2016]

[2] ARKIVE. (2012) Superb bird-of-paradise. [Online] Availabe from: http://www.arkive.org/superb-bird-of-paradise/lophorina-superba/image-G129246.html [Accessed: 24th October 2016]

[3] LARSON, S. (2016) The King of Saxony Bird-of-Paradise’s Courtship Freakout. [Online] Available from: https://www.junglesinparis.com/stories/the-king-of-saxony-bird-of-paradise-s-courtship-freakout [Accessed: 26th October 2016]

[4] SCIENTIFIC AMERICAN. (2016) Why are male birds more colorful than female birds? [Online] Available from: https://www.scientificamerican.com/article/why-are-male-birds-more-c/ [Accessed: 26th October 2016]

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The Misconception of Unset Jelly

As an experimental cook, the conventional fruit which are set in jelly on top of a cake are not good enough. So, fuelled by the desire to find the most original combination of fruit that could adorn a cake creation whilst smothered in jelly, I managed to find a few unusual possibilities, until I met my nemesis: fruit, which no matter how long the jelly sat in the fridge, prevented it from setting.

This post looks at why, and the slight misconception which surrounds the idea that some fruit prevent jelly from setting.

An Introduction to Gelatine

What is gelatine?

Gelatine is a mild tasting protein that is derived from collagen in animal tissue, which in turn is a hard, insoluble, fibrous protein [1]. Collagen is the connective tissue protein that provides strength to muscles and tendons and resiliency to an animal’s skin and bones, meaning that in humans it makes up one third of the total protein content [1]. Furthermore, since it is a structural protein, collagen is found in many parts of an animal’s body as it helps to maintain the structure and shape.

Where does gelatine come from?

Most gelatine is manufactured from pig skin because around 30% of its weight is collagen [2]. Firstly, the pig skin is soaked in dilute hydrochloric acid for roughly 24 hours. This step leads to the unravelling of the crosslinking protein bonds in collagen, resulting in the free protein chains then being extracted. These are filtered, purified and dried into sheets or granules (powder) that contain around 90% gelatine, 8% water and the remaining 2% is salts and glucose [2].

How does gelatine work?

Gelatine has claimed the prize of being different to all other proteins typically used in a kitchen setting, partially because it is the only protein that has the power to thicken liquids. This is why gelatine thickened sauces are ‘crystal clear and syrupy’ rather than opaque and creamy like sauces which use starch or flour as the thickening agent [2]. Gelatine’s unique properties arise from that fact its response to heat is not one that is usually demonstrated by proteins. Normally, food proteins respond to heat by unravelling (meaning they lose their tertiary and potentially secondary structures), and then bonding to one another to coagulate into a firm, solid mass. This is demonstrated by an egg frying since the albumin (liquid protein of the white) firms up into a solid mass of egg white as it is heated. However, gelatine proteins do not readily form bonds with one another, meaning that although heat initially causes them to unravel and disperse like any other protein, the gelatine proteins never form new bonds. This results in the liquid that they are dispersed in remaining as a fluid. Furthermore, because gelatine proteins are also long and stringy, they tend to become interwoven and this leads to the hot liquid in which they are suspended to thicken, although not completely solidify when warm. As the gelatine gradually cools down, the protein strands line up next to each other and twist into long ‘ropes’ and turn the liquid into a firm gel [2].

Plot Twist from an Innocent Addition

Learning from my past experiences, the following fruit should not be added if you wish for your jelly to achieve its intended state:

  • Pineapple
  • Kiwi
  • Figs
  • Papaya
  • Pawpaw
  • Mango
  • Guava
  • Ginger root

There are, as always, some exceptions to this rule, however I will come onto this later.

An unexpected culprit

You may have noticed that some of the aforementioned fruit are quite acidic, such as kiwi, and for me, initially, this was why the jelly did not set. However, it was as I did more research that I realised this was not the case.

As far as I am aware, when we study enzymes at school, whether at GCSE or A Level, enzymes seem to take on the role of the keys to existence, the Gods of all things bright and biological, or words to that effect. Or an effect slightly less exaggerated.

And yes, I do not dare disagree with the importance of their function as biological catalysts, whether it be in the baby food industry, slimming food industry or even saving the world by being a part of biological washing powders which require a lower temperature.

However, enzymes are the reason behind your cake masterpiece having a ‘soggy top’ as a result of the jelly not setting, which would lead to a piercing ice-blue stare from Paul Hollywood himself, an ‘It’s a little informal’ comment from the Queen of baking, Mary Berry, and may even provoke Shakespeare’s ‘God has given you one face, and you make yourself another’ exclamation.

Why are enzymes the downfall of jelly?

The listed fruit contain enzymes, in particular, proteases. Pineapple, kiwi, papaya, pawpaw and mango all contain actinidin, papaya and pawpaw also contain papain, pineapple also has bromelain, figs contain ficain and ginger contains zingibain.

The reason that jelly sets is because the collagen proteins in the gelatine form a tangled mesh as a result of being interwoven, meaning that water molecules are trapped, as well as other components of the liquid, and this provides the gelatine its semisolid state when it cools [3].

gelatine-structure

Fig 1. The long gelatine molecules as seen in set jelly [4].

The proteases in the fruit act on gelatine protein, and this can be thought of as the proteases acting as scissors and ‘cutting up’ the long strands of gelatine protein into smaller pieces, so that they can no longer interweave and create a network to trap water and other liquid molecules, meaning the jelly does not set [4]. This is shown in figure 2 and figure 3.

enzymes-acting-on-gelatine

Fig 2. Scissors representing enzymes (proteases) acting on gelatine [4].

shorter-gelatine-molecules

Fig 3. Shorter gelatine molecules after protease action [4].

In addition, it is important to note that pineapple and kiwi contain far more proteases than the other listed fruit. The reason for this difference is unknown, however it may be linked to the idea of repelling pests. As a basic concept, animals and bacteria are made up of proteins meaning that essentially the high levels of proteases in the fruit will digest any of the pests trying to feed on the fruit [4].

Moreover, I should address the exception that I mentioned earlier in the post. The fruit has to be fresh in order for it to ‘rain unset jelly on your cake parade’. For example, canned pineapple will not ruin your showstopper. This is because during the canning process, the pineapple is heated to kill bacteria so that the pineapple can be in the can for a long period of time and not decay [4]. This process also denatures the enzymes which means that they no longer act on the gelatine protein and prevent the jelly form setting. The high heat causes the bonds in the protein of the enzyme to vibrate meaning the bonds break (hydrogen bonds break first). Since hydrogen bonds are an essential part of the tertiary structure of the protein (which create a fibrous chain or globular chain) and the secondary (which is responsible for the protein either being an alpha helix or beta pleated sheet), the two structures of the enzyme are lost. This results in the active site of the enzyme no longer being complementary to the substrate (the gelatine protein molecule), so that no enzyme-substrate complexes form, meaning the gelatine is not catabolised. As a result, the jelly sets in its normal fashion.

Overall, for me the misconception lies in the fact that the fruit which should not be added fresh are rather acidic, especially kiwi. This always seemed to mean that it is the acidic conditions that the prevent the jelly from setting rather than the presence of certain enzymes.

References

[1]   http://www.medicalnewstoday.com/articles/262881.php

[2] http://www.finecooking.com/item/63379/the-science-of-gelatin

[3] https://www.scientificamerican.com/article/bring-science-home-fruit-gelatin/

[4] http://www.thenakedscientists.com/HTML/experiments/exp/science-of-fruit-jellies/

Other websites used

http://chemistry.about.com/od/foodcookingchemistry/a/foods-that-ruin-jell-o.htm

https://en.wikipedia.org/wiki/Actinidain

 

 

Oxytocin: Liquid Trust

keep-calm-and-release-oxytocin-21

I was listening to a Bryson Tiller song this morning and being the cynic of love that I am, I cringed at the lines ‘Love holds me together’. As much as I hate clichés like these however, those lyrics may hold some truth in them. Patty Van Cappellen, associate director of the Interdisciplinary and Behavioral Research Center at Duke University in Durham, NC, and colleagues found that men given oxytocin nasal spray reported a greater sense of ‘being whole’. Afterwards, those who received the oxytocin were more likely to say spirituality was important in their lives, and that they felt connected to other living things, agreeing with statements like “All life is interconnected”.

a-man-meditating-by-the-sea

Oxytocin is also known for its role in maternal bonding, and there is strong evidence that the hormone is important for social bonding, empathy
, trust, and sexual pleasure, hence why it is often dubbed the love hormone.


 

So looks like all those soppy love songs were on to something that science has only recently begun to explore. So what does this mean for us? Is oxytocin the real life version of Amortentia and therefore the love potion to solve all our relationship woes? Not so fast says Dr Radulovic (well actually I’m saying it, but you get what I mean).

 

Jelena Radulovic, senior author on the study and a professor at Northwestern University’s medical school claims that:

 

“The love drug also plays an important role in intensifying negative emotional memories and increasing feelings of fear in future stressful situations.”

 

This is because the hormone actually strengthens social memories, whether it be positive or nightmarish. The scientists discovered that oxytocin strengthens negative social memory and future anxiety by triggering an important signalling molecule – ERK (extracellular signal regulated kinases) – that becomes activated for six hours after a negative social experience. Although the experiment was conducted on mice, it’s safe to assume that oxytocin might have played a role in those cringe-bombs every time you remember that moment when you were depants in front of your crush.

 

“Love is essentially a biochemical cocktail, and a poorly understood one at that”

 

~Jessica Hullinger

 

Research also links oxytocin to increased trust, social bonding and even a predisposition to donate to charity, thus earning its nickname ‘Liquid Trust’.

Speaking from personal, one of the most common ways to incite an oxytocin release is by hugging for more than 5 seconds. It’s these positive influences that make researchers hopeful that it could help treat mental health disorders, including autism, social anxiety disorder and schizophrenia.

Despite oxytocin’s dark side, it is undeniably an important hormone especially with its many roles in building trusting relationships, increasing one’s sense of interconnectedness and an overall kumbaya feeling, and could potentially even be used to treat schizophrenia.

 

My verdict? Go ahead and hug somebody today.