Greenhouse effect

What is the greenhouse effect..? This is a common word used by the environmentalists, scientists and many others who are interested in protecting the earth for the next generation and for many more generations to come.

                   The greenhouse effect is nothing strange. It is natural process that occurs and helps to heat the earth’s surface and the atmosphere. If not for the greenhouse effect the temperature on this earth world be minus eighteen degrees centigrade rather than the present fifteen degrees centigrade. We would have frozen to death if not for the greenhouse effect.
        If that is the situation why is everyone talking about the greenhouse effect, global warming and climatic changes? It is because of the increase of greenhouse gases in the atmosphere. Let us see what has actually happened.
                                    51% of the energy from the sun’s rays that reaches the surface of the earth is used for many processes including heating of the earth’s surface, melting ice, evaporation of water and photosynthesis. The balance energy is expected to be reflected into space. But this does not happen due to the presence of greenhouse gases like Carbon dioxide. Methane, Nitrous Oxide etc. These gases trap the excess, out going heat energy and additional heat is added to the earth’s atmosphere.
             How have humans contributed to this phenomenon? The industrial revolution, development and also human interference with nature have caused a great amount of greenhouse gases to be emitted into the earth’s atmosphere.

                   Scientists have predicted that the greenhouse effect will be enhanced. It is not yet confirmed but there are doubts as to whether Global Warming and the climatic changes are due to the greenhouse effect. There is a lot of research being done and many countries have started working on reducing the amount of carbon emission into the atmosphere. Even in Sri Lanka if you go to a petrol station you can see a board on every petrol pump which reads 90 octane petrol lead free which is environment friendly.

              Carbon dioxide levels are expected to rise further due to the ongoing burning of fossil fuels. The rate of rite will depend on the usage and the availability of fossil fuels.

               The increase in global temperature can in turn cause other changes like rising sea levels, creating extreme weather conditions, changes in agricultural fields. glazier retreat, species extinctions and the increase in breeding of disease carrying insects like mosquitoes.

    

                       

Books

We have brought some pictures of books too. Books, are the most important sources of knowledge. We have learnt many things from books. As little children, we loved to read fairy tales and other story books.
                 Now we have read stories, poems, histories, repots, biographies, adventures, everything in books. We have learnt about our country, and other countries from books. We have read about things we have never seen or heard before.
                                                           Books give us not only knowledge; they give us entertainment too. The Tales of the Arabian Nights, tell us of strange adventures. They keep us awake with curiosity. Aesop’s fables tell us of folk tales of many lands. The fairy tales delighted us in our childhood. Now we have the Harry Potter Series. Some time back we had the Enid Blyton stories.
                                                    Each religion has its own books too. The Christians have the Bible, the Muslims have the Quran, the Hindus have the Vedas, the Buddhists have the Dhammapadaya. The Mahavamsa, is considered the oldest record of history of Sri Lanka.
                                                  When we are free, we spend our time with books in the library. When we are ill, and in bed how would we spend our time if we didn’t have a story book? Books and knowledge are inseparable are inseparable in our life.

VIRUS AND CANCERS...?

                 Cancer is a class of diseases in which a group of cells display uncontrolled growth, invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis (spread to other locations in the body via lymph or blood).Cancer may affect people at all ages, even fetuses. Cancer causes nearly 13% of all death around the world.

                                          There are many causes for cancer for cancer including chemical carcinogens, ionizing radiations, viral or bacterial infections, hormonal imbalances, immune system dysfunction and heredity.

Some cancers can be caused by infection with pathogens. There are many cancers that originate from a viral infection, and these viruses are responsible for 15% of human cancers worldwide. Many viral oncogenes have been discovered and identified to cause cancer. (An oncogene is an agent associated with cancer).Oncoviruses come in tow different forms: viruses with a DNA genome, and viruses with a RNA genome.

                                           There are many examples of DNA viruses in the world. Homan Papilloma Virus (HPV), is a DNA virus, which causes transformation in cells through interfering with tumor suppressor proteins such as p53. It cancers in cervix, skin, anus mouth, and may be lung cancer. Human herpes virus 8 is associated with Kaposi’s sarcoma, a type of skin cancer. Epstein Barr Virus (EBV) is associated with four types of cancers and they are Burkitt’s lymphoma, Hodgkin’s lymphoma, B lymph proliferative disease and nasopharyngeal carcinoma.

                                            There are RNA viruses too which can cause cancer. Hepatitis Virus causes Hepatocellular carcinoma (liver cancer).Human T cell leukaemia virus1 (HTLV1) cause adult T cell leukemia.
                             Mainly the DNA viruses insert their information directly into the cells of their hosts, although the Epstein Barr virus instead appears to exist in multiple copies as nucleic material known as a plasmid in the host cell’s nucleus, separate from the host DNA. The RNA viruses such as the HTLV 1 virus require first that their genetic information be transcribed into DNA by using the enzyme reverse transcriptase, supplied by the virus.
                              The oncogenic mechanism is ether to insert additional oncogenic genes in the host DNA, or to enhance already existing oncognic genes in the genome. These oncogenic  are best characterized in the genomes of oncogenic RNA viruses.
            Some oncogenic retroviruses (RNA viruses causing cancers) insert their genomic material into the host cell and use reverse transcriptase enzyme to make new DNA. This DNA is then incorporated into the cell DNA along with Powerful Promoter Sequences (LTRs) that Promote transcription Of the Viral DNA to reproduce more Viruses. Sometimes the Viral DNA incorporates a section of the host DNA which contains genes for growth promotion. These types of genes are called proto oncogenes in their normal state, which become oncogenic once incorporated into the viral DNA because of the increased transcription caused by the viral LTRs. This is the causes for the increased growth of the infected cell, leading to cellular proliferation and the tumor formation. A large number of oncogenes have been discovered in the genomes of transforming retroviruses. 

                  Other oncogenic retroviruses transform cells by integrating into the host gene near a proto oncogene. If the viral LTRs are close enough to that oncogene, they will up regulate transcription not only of the viral DNA but of the proto oncogene nearby, causing growth, cell proliferation and by consequence tumor formation.

RAINFORESTS

The importance of Rainforests

Tropical rainforests are located around the equator. The temperature around the equator is high. Hence the rate of water evaporation is high. As a result there is frequent rain in rainforests. They are found in South and Central America, Africa, in the islands around Australia and Asia. The rainforests are important to human existence and the surroundings. Rainforests are rich source of medicinal plants, food and useful forest products. They maintain about 50% of the plant, animal, bird, reptile and insect species of the world. These forests help to maintain a regular rainfall. They also stand as a buffer against floods, droughts and erosion. These forests produce a significant amount of the world’s oxygen. 

“Sinharaja” Rainforest in Sri Lanka.

The sinharaja forest is the only undisturbed rainforest left in Sri Lanka. It is about 9000 hectares in extent. Many of the plants are rave. Over 60% of the tree species are found only in the lowland wet zone of Sri Lanka. If these species of tree are allowed to get destroyed, the world would lose them altogether. So it is important that much effort is made to conserve this rich, valuable and fragile habitat.

             The sinharaja rainforest is the largest rainforest reserve in Sri Lanka. In 1840 Sinharaja became a crown property. In 1988 the Sinharaja was made National Wilderness area. In1989 UNESCO included the Sinharaja Forest in the World Heritage list, as the fist National Heritage of Sri Lanka.

                                The sinharaja forest is home to many rare animal, birds, butterflies, insects, reptiles and trees. Ferns and mosses grow well as the climate is humid because of heavy rainfall.

          

The vegetation

Vegetation means trees, shrubs and woody climbers. The average height of tree in the Sinharaja varies between 35 to 40metres. Some trees are above 50 metres.

The animals and the birds

Sinharaja provides a habitat for animals. The plants provide them with food. There are large mammals as well ones living there. The purple faced monkeys can be observed easily. They move about in groups. There are herbivores, carnivores as well as mixed feeders. The wild pig, the sambur, the mouse-deer and the barking-deer are some that you find in the Sinharaja. There is also evidence of the presence of the leopard. Among others are the rusty spotted cat and the fishing cat. There are many other varieties of small mammals.

                            Studies have recorded 147 species of birds. Some threatened species of birds are found in the Sinharaja. Among them are the blue magpie, the white-headed starling and the ash-headed babbler.

Reptiles

Studies have recorded 45 varieties of reptiles. These include snakes, lizards and tortoises. The viper and the cobra are among the venomous species. Conservation of sinharaja is of vital necessity. It ensures the maintenance of water resources. It also controls floods, which is a constant threat due to heavy rainfall in the area.