Pollinator Shortage Affects the Global Health

Pollinators play a central role in the reproductive propagation of flowering plants. Tiny insects or animals which act as pollinators include honey bees, butterflies, hummingbirds, bats, and ants. Plants yielding nutritionally rich fruits and vegetables are dependent to a large extent on pollinators.

Since past 50 years production of staple crops like rice, potato, wheat, yam etc has almost doubled. These crops mainly supply energy to our body and they are mostly wind-pollinated, self-pollinated, or vegetatively propagated. However our diet is incomplete without certain vital nutrients like vitamins and minerals and they are supplied by animal or insect pollinated plants.

According to the recent research conducted by Eilers et al. (2011) majority of oil produced from the plant sources comes from the plants which are animal pollinated. Vital nutrients like vitamin A, C and E come from animal pollinated fruits and vegetables. It has been estimated that approximately 70% of vitamin A and 98% of key nutrients like

Carotenoids, lycopene and ß-cryptoxanthin are obtained from plants which yield red, orange and yellow vegetables and fruits. These nutrients help us to fight cardiovascular diseases and cancer and are a source of antioxidants to the body. Plants like beans and dark green leafy vegetables are rich in folic acid which is very essential during pregnancy.

Eilers and his team have noticed a direct correlation between the increases in the yield of these plants with the increase in the number of pollinators. Apart from this the supply of certain vital minerals like calcium and fluorine and iron, increases with an increase in pollination of plants like beans, almonds and nuts.

Human intervention has reduced the number of pollinators to a very large extent. Deforestation over a vast area destroys the habitat and depletes the source of food for pollinators. This automatically reduces their number. Monoculture-based agricultural production that is planting similar crop year after year with a support of chemicals in the form of fertilizers and pesticides not only depletes the soil of its natural fertility but also reduces the number of pollinators. Some other factors which effect the pollinator population include, pesticides, insect and animal diseases and parasites.

A large number of nutrient supplements are available in market. But are they affordable to a common man belonging to the developing country? Moreover the synthesis of these supplements involves huge expenditure. Should we go ahead with the rampant use of chemicals to increase the food production or revert back to traditional eco-friendly farming practices? The choice is left to us.

References

Eilers EJ, Kremen C et al. Contribution of pollinator-mediated crops to nutrients in the human food supply. PLoS One. 2011;6(6):e21363

Manipulation of Plant’s Defense by Herbivores Poses Challenge to Entomologists

Plants have inherent defensive mechanism which protects them from their predators and phytopathogens. Their inability to move is largely complemented by the defensive adaptations which help the plants to survive and reproduce successfully. One of the most important defensive mechanisms is production of secondary metabolites. These metabolites are the chemical substances which are not involved in the normal photosynthetic process of the plants. They are alternatively known as allelochemicals and they can influence the behavior, growth, or survival of herbivores. Allelochemicals act as toxins to herbivores and in some cases also reduce the digestibility of plant cell wall.

Some external structural features on the stem and the leaves (prickles, spines, thorns etc) discourage herbivory to a very large extent. These mechanical defensive mechanisms deter, injure, or kill the grazer. Some defensive substances like wax, resins, lignins, etc. are released on the plants’ epidermis and prevent the herbivores from feeding on them. Apart from these, sensitivity to touch shown by Mimosa pudica is another example of defense mechanism in plants.

Herbivores form a primary link in the food chain, as they are the source of energy for organisms ranking higher in the food chain. Plants are the only source of food for herbivores and this led to the co-evolution of adaptations, which help them to acquire their food, irrespective of the defense mechanisms in plants. Some of these adaptations are:

·        synthesis of enzymes which can reduce the effect of secondary metabolites

·        existence of internal symbiotic bacteria, fungi, or protozoa which help to break down the plant cellulose so that it can be digested by the herbivore

·        mechanical adaptations like incisors in moths which helps them to eat soft leaves.

Amongst these adaptations, host manipulation is the most important mechanism by which herbivores feed on the plants in a better way. According to the recent research conducted by Renato Almeida Sarmento and his team, invasive spider mite Tetranychus evansi, manipulates its host (tomato), by interfering with signalling pathways involved in its defense mechanism [1].

Primary hosts for T. evansi are solanaceous crops like tomato, potato, tobacco etc. These mites puncture the leaves while feeding, leading to yellowing or whitening of leaves. Subsequently the leaves fall down and in case of severe attack the plant dies. The study conducted by Sarmento, suggests that T. evansi, manipulates the host defense mechanism by suppressing the induction of the salicylic acid and jasmonic acid signalling routes which are involved in plant defenses in tomato plant [1]. Salicylic acid and jasmonic acid play a vital role in plants immunity. Spider mites reduce the levels of inducible defense compounds and volatiles (example, proteinase inhibitors) which play a crucial role in plants defense.

Crops like tomato and potato find a widespread use across the world. Control of pathogens affecting these crops is a vital area of research. The result of the research by Sarmento, provides a better understanding of the plant–herbivore interactions. It opens the gateway for further research in two directions:

·        Biological control of Tetranychus evansi at an affordable cost to the farmer.

·        Developing crop varieties which are able to combat the manipulations by herbivores.

Reference:

Sarmento R, Lemos F et al. A herbivore that manipulates plant defense. Ecol Lett. 2011 March 14(3): 229–236.

Organ Donation – Saves another Life

During organ donation, solid organs like kidney, heart, pancreas, liver, bone marrow, eyes and limbs, are removed from the body of the donor and transplanted into the body of the recipient. Some of these organs can be preserved and utilized for future transplant. Vital organ like heart cannot be removed from a living person. Hence such organs are acquired from cadaver donors, who have died recently. Organs are separated from live donors in two cases

1)     When the organs are present in pairs. Example kidney

2)     When the removal of a portion of an organ does not effect the functioning of organ. Example liver, bone-marrow, pancreas

Legalization of transplantation of human organs has given rise to the concept of brain dead. Brain death is state of legal death. In this state the heart continues to beat and all the vital organs are kept alive and functional with the help of mechanical ventilation. This is a state during which the brain is dead and in an unrecoverable state – meaning – cannot be brought back to life. This condition is optimum to remove the organs for transplantation.

Consent of the Donors

Organ donation should happen only with the consent of the donor, if alive.  In most cases, the donor registers himself or herself as a donor where he agrees to donate specific organs on his death.  This is very common in the case of eye-donation and there are multiple organizations catering to this. After getting registered, the donors are issued a card which certifies their wish to donate organs. It is the donor’s responsibility to keep his family informed of his decision so that in case of death, the family can notify the organization that registered him.  The organizations try to reach the person in the earliest possible time to retrieve the organs after death. In some cases, the family of a victim of an accident may decide to donate the organs of the brain-dead victim. 

National Marrow Donor Program maintains a list of people willing to donate bone marrow to a stranger and here are some links given below where we can register ourselves as organ donors

http://www.medicareaustralia.gov.au/public/services/aodr/register.jsp

http://www.sgrh.com/subcat.aspx?id=51

http://www.organdonation.nhs.uk/ukt/roadshow.jsp

http://www.iaod.org/donor-registration-card-organ-donation.htm

Regulation of Organ Donation

Organ donation and transplant has always had a lot of regulation surrounding it. 

The reasons behind intense regulation are many, primary reason being exploitation and corruption. Seeing the high demand of organs, doctors and organ vendors try to exploit a common man by taking out his organs without his consent. Organ selling is legally banned in India but there are many areas where poor people are encouraged to sell their organs in return of money. On the ethical side, questions like - can a person who is mentally retarded be allowed to donate, can infants be donors, and so on have necessitated the stringent regulation of organ donation.

Does organ transplantation bring an end to the treatment procedure?

Once an organ is implanted into the body a long journey of recovery with intense medication begins. The body recognizes an implanted organ as a foreign body and the immune system wakes up. It tries to produce antibodies against the implanted organ and hence rejecting it. The patient is kept on strong immunosuppressant drugs for a long duration to allow the implanted organ to work properly.

Milestones Covered on the Road of Organ Transplant

• Transplantation of kidney was only feasible in the beginning but now transplantation of heart, liver, pancreas, skin, bone marrow, limbs intestines etc is also feasible.
• Now we have a wider choice as we can collect organs from both living and dead people.
• Discovery of strong immunosuppressant drugs has increased the success rate of organ transplants.
• Xenotransplantation or use of animal organs for human transplantation has takes us a step ahead. Example Chimpanzee kidneys were transplanted into patients with renal failure. A baboon heart was transplanted into a newborn infant.
• Syntheses of artificial organs for transplantation – Examples in this line are bionic eyes and ears, artificial heart.
• Organ from a single donor is being used for more than one patient by splitting it. Example split liver transplant where liver from a single donor was used for implantation into multiple recipients.
• Pioneering research – Stem cells have an enormous capacity to develop into any kind of tissue within the body including organs. Scientists aim to synthesize organs using the stem cells.

A large number of deaths have been reported to be due to the lack of organs ready for transplantation. Many patients live years together on expensive dialysis as they do not get a kidney donor. Lack of public awareness and inclination towards organ donation are main hurdles in this line. Galore of controversies and ethical issues surrounding organ donation accompanied by unawareness have made this procedure difficult. A voluntary organ donation saves another life.

Preservation of Suji or Semolina

Suji is vital ingredient in many Indian foods like upma, halwa, vada, laddoos, rava dosas etc. A porridge made of suji is a good weaning food for toddlers. Suji rava is prepared from wheat. The wheat grains are fed into rollers to remove the bran and germ. The remaining starchy part or the endosperm is broken down into pieces. A sieve made of net or mesh is used to separate the lighter part which is bran. The semolina pieces are further crushed to obtain fine flour.

Suji is a high calorie diet which provides energy for long period after consumption. It provides complex carbohydrates to our body. It is a processed food and vital components of grains like bran (fiber rich part) and germ (rich source of vitamin B complex, vitamin E, and minerals like Iron and calcium and magnesium) are lost during processing.

However nutritional value of any food item depends a lot on the method of preparation also. Many dishes like suji roti, rava-ragi rotis, rava idlis, rava dosas etc can be prepared using very less amount of oil. This will reduce the fat intake and also reduce the cholesterol levels. We can also add some grated vegetables in these dishes to supplement other nutritional requirements. We can prepare a wide variety of yummy dishes by slightly changing the formula of cooking. Isn’t that great about suji!

Porridge of suji with milk and sugar is cherished by infants. This gets easily digested and can be supplemented with smashed vegetables and fruits for a wholesome diet. Suji is generally stored in containers on the shelf and does not require refrigeration. Rava can be considered to be good until the rava granules are separate like that of sugar. However upon infestation, it starts forming threads. We can increase the shelf life of suji. All we need to do is fry siji for a few minutes over a low flame. After frying for few minutes the colour of rava turns out to be light brown accompanied with nice aroma. This should be cooled properly and then packed in air tight containers. This technique extends the shelf life of suji. Even after this if we find any signs of infestation it should be sun dried and used as soon as possible.