Nutritional genomics: À la carte menu

When Hipprocrates said “let food be your medicine and medicine be your food” he knew that food influences our health. And it tells us that nutritional genomics, which I will discuss in this article; a new science appeared in the post genomic era as a result of the sequencing of human genome (all DNA sequences that characterize an individual) and the technological advances that allow the analysis of large amounts of complex information.   

WHAT IS NUTRITIONAL GENOMICS?

The aim of nutritional genomics is to study the interactions of genes with elements of the human diet, altering cellular metabolism and generating changes in the metabolic profiles that may be associated with susceptibility and risk of developing diseases.

This study wants to improve the health and to prevent diseases based on changes in nutrition. It is very important not understand nutritional genomics how that specific food or nutrients cause a particular answer to certain genes.

When we talk about diet we have to distinguish between what are nutrients and what are food. Nutrients are compounds that form part of our body, while foods are what we eat. Food can take many nutrients or only one (such as salt).

NUTRIGENOMICS vs. NUTRIGENETICS

Within nutritional genomics we find nutrigenomics and nutrigenetics, but although their names we may seem to mean the same is not the case (Figure 1).

Nutrigenomics is the study of how foods affect our genes, and nutrigenetics is the study of how individual genetic differences can affect the way we respond to nutrients in the foods we eat.

Figure 1. Schematic representation of the difference between nutrigenomics and nutrigenetics (Source: Mireia Ramos, All You Need is Biology)

NUTRIGENOMICS IN DETAIL

Nutrients can affect metabolic pathways and homeostasis (balance) of our body. If this balance is disturbed chronic diseases or cancer may appear, but it can also happen that a disease, which we have it, be more or less severe. It means that impaired balance can give the appearance, progression or severity of diseases.

The aim of nutrigenomics is that homeostasis is not broken and to discover the optimal diet within a range of nutritional alternatives.

Thus, it avoids alterations in genome, in epigenome and/or in expression of genes.

ALTERATIONS IN GENOME

Free radicals are subproducts that oxidise lipids, proteins or DNA. These can be generated in mitochondria, organelles that we have inside cells and produce energy; but we can also incorporate from external agents (tobacco, alcohol, food, chemicals, radiation).

In adequate amounts they provide us benefits, but too much free radicals are toxic (they can cause death of our cells).

Antioxidants neutralize free radicals. But where can we get these antioxidants? There are foods that contain them, as Table 1 shows.

Table 1. Example of antioxidants and some foods where we can find them (Source: ZonaDiet)

The way we cook food or cooking is important for avoid to generate free radicals. In barbecues, when we put the meat on high heat, fats and meat juices fall causing fire flames. This produces more flame and it generates PAHs (a type of free radicals). These adhere to the surface of the meat and when we eat it can damage our DNA.

ALTERATIONS IN EPIGENOME

Epigenome is the global epigenetic information of an organism, ie, changes in gene expression that are inheritable, but they are not due to a change in DNA sequence.

Epigenetic changes may depend on diet, aging or drugs. These changes would not have to exist lead to diseases as cancer, autoimmune diseases, diabetes…

For example, with hypomethylation, in general, cytosines would have to be methylated are not. What does it mean? Hypomethylation silenced genes and then, they cannot be expressed. Therefore, we need methylated DNA. A way of methylate DNA is eating food rich in folic acid.

ALTERATIONS IN GENE EXPRESSION

There are agents (UV rays) that activate pathways that affect gene expression. Occurring a cascade that activates genes related to cell proliferation, no differentiation of cells and that cells survive when they should die. All this will lead us cancer.

It has been found that there are foods which, by its components, can counteract activation of these pathways, preventing signal transduction is given. For example curcumin (curry), EGCG (green tea) or resveratrol (red wine).

 REFERENCES

• The NCMHD Center of Excellence for Nutritional Genomics
• Michael Müller’s Laboratory
• Documentos TV: La Alimentación del Futuro
• M. Müller, S. Kersten. Nutrigenomics: Goals ans Strategies. Nature Reviews Genetics 2003; 4, 315-322
• J. Kaput, R.L. Rodríguez. Nutritional Genomics: the Next Frontier in the Postgenomic Era. Physiol Genomics 2004; 16, 166-177
• J.M. Ordovas, D. Corella. Nutritional Genomics. Annu Rev Genomics Hum Genet 2004; 5, 71-118
• Portal Antioxidantes
• Main picture: The Pu·rée

Plants and animals can also live in marriage

When we think about the life of plants it is difficult to imagine without interaction with the animals, as they establish different symbiotic relationships day after day. These symbiotic relationships include all the herbivores, or in the contradictory way, all the carnivorous plants. But there are many other super important interactions between plants and animals, such as the relationships that allow them to help each other and to live together. So, this time I want to present mutualism between plants and animals.

And, what is mutualism? it is the relationship established between two organisms in which both benefit from living together, i.e., the two get a reward when they live with the other. This relationship increase their biological effectiveness (fitness), so there is a tendency to live always together.

According to this definition, both pollination and seed dispersal by animals are cases of mutualism. Let’s see.

POLLINATION BY ANIMALS

Many plants are visited by animals seeking to feed on nectar, pollen or other sugars they produce in their flowers and, during this process, the animals carry pollen from one flower to others, allowing it reaches the stigma in a very effective way. Thus, the plant gets the benefit of fertilization with a lower cost of pollen production, which would be higher if it was dispersed through the air. And the animals, in exchange, obtain food. Therefore, a true relationship of mutualism is stablished between the two organisms.

 “Video:The Beauty of Pollination” – Super Soul Sunday – Oprah Winfrey Network (www.youtube.com)

The extreme mutualism occurs when the species evolve depending on the other organism, i.e., when there is coevolution. We define the coevolution such as these evolutionary adaptations that allow two or more organisms to establish a deep relationship of symbiosis, due that the evolutionary adaptations of one specie influence the evolutionary adaptations of another organism. For example, this occurs between various orchids and their pollinators, as is the well- known case of Darwin’s orchid. But there are many other plants that also have co-evolved with their pollinators, as a fig tree or cassava.

In no way, this should be confused with the trickery produced by some plants to their pollinators, that is, when they do not obtain any direct benefit. For example, some orchids can attract their pollinators through odours (pheromones) and their curious forms that resemble female pollinator, stimulating them to visit their flowers. The pollinators will be impregnated with pollen, which will be transported to other flowers due to the same trickery.

Bee orchid (Ophrys apifera) (Autnor: Bernard DUPONT, flickr).

SEED DISPERSAL BY ANIMALS

The origin of seed dispersal by animals probably had occurred thanks to a co-evolutionary process between animals and mechanisms of seed dispersal in which both plants and animals obtain a profit. The most probably is that this process began in the Carboniferous (~ 300MA), as it is believed that some plants like cycads developed a false fleshy fruits that could be consumed by primitive reptiles that would act as seed dispersers. This process could have intensified the diversification of flowering plants (angiosperms), small mammals and birds during the Cretaceous (65-12MA).

The mutualism can occur in two ways within the seed dispersal by animals.

The first case is carried out by animals that eat seeds or fruits. These seeds or some parts of the fruits (diaspores) are expelled without being damaged, by defecation or regurgitation, allowing the seed germination. In this case, diaspores are carriers of rewards or lures that result very attractive to animals. That is the reason why fruits are usually fleshy, sweet and often have bright colours or emit scents to attract them.

For example, the red-eyed wattle (Acacia cyclops) produces seeds with elaiosomes (a very nutritive substance usually made of lipids) that are bigger than the own seed. This suppose an elevated energy cost to the plant, because it doesn’t only have to produce seeds, as it has to generate the award too. But in return, the rose-breasted or galah cockatoo (Eolophus roseicapillus) transports their seeds in long distances. Because when the galah cockatoo eats elaiosomes, it also ingest seeds which will be transported by its flight until they are expelled elsewhere.

On the left,  Galah  cockatoo (Eolophus roseicapillus) (Autnor: Richard Fisher, flickr) ; On the right, red-eyed wattle’s seeds (black) with the elaiosome (pink) ( Acacia cyclops) (Autnor: Sydney Oats, flickr).

And the other type of seed dispersal by animals that establishes a mutualistic relationship occurs when the seeds or fruits are collected by the animal in times of abundance and then are buried as a food storage to be used when needed. As long as not all seed will be eaten, some will be able to germinate.

A squirrel that is recollecting som nuts (Author: William Murphy, flickr)

But this has not finished yet, since there are other curious and less well-known examples that have somehow made that both animals and plants can live together in a perfect “marriage.” Let’s see examples:

Azteca and Cecropia

Plants of the genus Cecropia live in tropical rain forests of Central and South America and they are very big fighters. The strategy that allow them to grow quickly and capture sunlight, avoiding competition with other plants, resides in the strong relationship they have with Azteca ants. Plants provide nests to the ants, since their stems are normally hollow and with separations, allowing ants to inhabit inside. Furthermore, these plants also produce Müllerian bodies, which are small but very nutritive substances rich in glycogen that ants can eat. In return, the ants protect Cecropia from vines and lianas, allowing them to success as a pioneer plants.

Ant Plants: Cecropia – Azteca Symbiosis (www.youtube.com)

Marcgravia and Bats

Few years ago, an interesting plant has been discovered in Cuba. This plant is pollinated by bats, and it has evolved giving rise to modified leaves that act as satellite dish for echolocation performed by these animals. That is, their shape allow bats to locate them quickly, so they can collect nectar more efficiently. And at the same time, bats also pollinate plants more efficiently, as these animals move very quickly each night to visit hundreds of flowers to feed.

Marcgravia (Author: Alex Popovkin, Bahia, Brazil, Flickr)

In general, we see that the life of plants depends largely on the life of animals, since they are connected in one way or another. All the interactions we have presented are part of an even larger set that make life a more complex and peculiar one, in which one’s life cannot be explained without the other’s life. For this reason, we can say that life of some animals and some plants resembles a marriage.

REFERENCES

• Notes from the Environmental Biology degree (Universitat Autònoma de Barcelona) and the Master’s degree in Biodiversity (Universitat de Barcelona).
• Bascompte, J. & Jordano, P. (2013) Mutualistic Networks (Chapter 1. Biodiversity and Plant-Animal Coevolution). Princeton University Press, pp 224.
• Dansereau, P. (1957): Biogeography: an Ecological Perspective. The Ronald Press, New York., pp. 394.
• Fenner M. & Thompson K. (2005). The Ecology of seeds. Cambridge: Cambridge University Press, 2005. pp. 250.
• Font Quer, P. (1953): Diccionario de Botánica. Editorial Labor, Barcelona.
• Izco, J., Barreno, E., Brugués, M., Costa, M., Devesa, J. A., Fernández, F., Gallardo, T., Llimona, X., Parada, C., Talavera, S. & Valdés, B. (2004) Botánica ªEdición. McGraw-Hill, pp. 906.
• Murray D. R. (2012). Seed dispersal. Academy Press. 322 pp.
• Tiffney B. (2004). Vertebrate dispersal of seed plants through time. Annual Review of Ecology, Evolution and Systematics. 35:1-29.
• Willis, K.J. & McElwain, J.C. (2014) The Evolution of Plants (second edition). Oxford University Press, pp. 424.
• National Geographic (2011). Bats Drawn to Plant via “Echo Beacon”. http://news.nationalgeographic.com/news/2011/07/110728-plants-bats-sonar-pollination-animals-environment/

If the nymphs were plants, they would be water lilies

This week, I’m going to introduce water lilies, some flowers very nice and known for being important in the ornamentation.

INTRODUCTION

The Nymphaeaceae family has few species and most of them are freshwater aquatic plants in quiet places and commonly are known as water lilies. Because they are aquatic plants, the family’s name is derived from the Latin word nympha, as they have some similarity with nymphs, mythological beings with a predilection for the waters.

Water nymphs, water lilies can be seen around (Painting by Henrietta Rae, 1909).

The water lilies were originated in warm regions, but they are now subcosmopolitan and can be found in several parts of the world, living in ponds, lakes and freshwater streams.

MORPHOLOGICAL CHARACTERS

The water lilies are perennial aquatic plants, they live several years, and are rhizomatous, that is, they have a thickened stem below the soil at the bottom of the water. In some species, we see that some leaves are immersed and others are floating on the water surface, being sometimes even membranous (they have raised edges perpendicularly upward to avoid the ingress of too much water). When this morphological difference happens, we talk about heteromorphous leaves.

Water lily's membranous leaves (Victoria amazonica) (Photo taken by Dirk van der Made).

Their flowers grown out of water and are constituted by a variable number of sepals, petals and stamens, which are helically born. Therefore, flowers are acyclic, that is, are asymmetrical or irregular because they have no symmetric plane. These flowers are solitary, not born grouped, and hermaphrodites, that is, both male (stamens) and female (ovary) sex organs occur in the same flower.

Pygmy waterlily (Nymphaea tetragona)(Photo taken by Miguel303xm).

These perianth parts (petals and sepals) and stamens are free among them, therefore, they are not united or fused among them, and normally appear in large numbers. The stamens are different to several of other flowers, because they are laminar stamens, similar to the petals. Therefore, they are not filamentous, are thicker and wider.

DIVERSITY

Currently, the genera of water lilies which have more relevance are Nuphar, Nymphaea and Victoria, but there are also some others. Below I present some cases of very interesting species.

The tiger lotus or Egyptian white water-lily (Nymphaea lotus) is native of the Nile Valley and eastern Africa. It is prized as an ornamental and ancient Egyptians believed that the flower could give strength and power.

Egyptian white water-lily (Nymphaea lotus) (Photo taken by Meneerke bloem).

The yellow water-lily (Nuphar lutea) is typical of Europe, North Africa and the Middle East and, as the previous one, is also very ornamental. Furthermore, it has been long used in traditional medicine. Its roots were applied on the skin and seeds and roots were eaten to treat different diseases.

Yellow water-lily (Nuphar lutea) (Photo taken by Oksana Golovko).

Finally, I’d want to introduce the genus of Victoria, whose pollinitation is very curious. It has two American species: V. cruziana in Argentina and V. amazonica in the Amazon and Brazil. Plants of this genus are very big, with floating leaves reaching to 2 meters in diameter and with showy flowers which can reach up to 30 centimeters and are opened at evening.When these flowers are opened, strong scents and a little heat are released and with the whitish and beige colours of the petals, they result very attractive to the beetles (Coleoptera) that are feed of starch extensions on the flowers (starch bodies). The next morning, flowers are closed and the beetles are captured within, causing them to be permeated of pollen. At afternoon, flowers are reopened and allow beetles to escape. Then, as the flowers have been pollinated, their colour varies to pink and they also lose scent. Therefore, the beetles feel more attracted to white flowers that have not been pollinated yet. Finally, the pink flowers are dipped.

On the left, V. cruziana (Photo taken by Greenlamplady); On the right, V. amazonica (Photo taken by frank wouters).

IMPORTANCE

Currently, several species are used as ornamentals, decorative. Furthermore, the water lilies can also be used to get food; the seeds and rhizomes of the genera Nymphaea and Victoria are edible. On the other hand, a very curious thing is that the nerves of the leaves of some species have been used to extract a liquid, which has been applied to treat snake bites.

I hope you liked the way the water lilies behave and all their tales and uses that are associated to them, although only for its beauty are charming. If you enjoyed, do not forget to share in different social networks. Thanks for your interest.

REFERENCES

• Bolòs, J. Vigo, R. M. Masalles & J. M. Ninot. 2005. Flora manual dels Països catalans. 3ed. Pòrtic Natura, Barcelona: pp. 1310.
• Notes of Botany and Phanerogamae, Degree of Environmental Biology, UAB.
• http://www.biologia.edu.ar/diversidadv/fascIII/11.%20Nymphaeaceae.pdf
• http://www.thecompositaehut.com/www_tch/webcurso_spv/familias_pv/nymphaeaceae.html
• http://web.ing.puc.cl/~ing1004/Homeworks/SeresVivos_E3/g63_Sof%C3%ADaGjuranovic_VictoriaAmaz%C3%B3nica.pdf

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