VACCINES FOR HEALTHIER LIFE

Vaccine is a chemical substance, which is used to   stimulate an immune response in the body to resist disease.  Vaccines are the preparation of killed or living microorganisms which are produce immunity when administered into the body.

The first vaccine was produced by Edward Jenner in 1776 against small pox. Small pox was the first disease to be eliminated by vaccination.                                                                                                                                                                                         When pathogen enters into the human body, pathogen releases toxic chemical to destroy the human defense system. This toxic substance is called antigen. Similarly, human blood is also defends against and destroy that antigen by releasing a very specific chemical called antibody. Antigen is the foreign material that elicits antibody formation. Antibody is the molecule synthesized by human body in the response of foreign substance i.e. antigen.

There are five types of vaccines:

I)                           Killed vaccines

II)                       Toxoid

III)                   Attenuated living vaccines

IV)                  Antibodies as vaccines

V)                      Antigen like polysaccharides

        Immunity is the ability of the person to fight against diseases causing pathogen. They can be achieved by two by two ways

1)           Natural or in-born immunity

2)           Acquired immunity

      Most of us think that these vaccines are kind of medicines as like those medicine which are given by physician when suffering from some kind disease like common cold, typhoid etc. But actually, vaccines are the bacteria or viruses that cause the same diseases themselves. For e.g. Dadura Khop contains the same kind of bacteria that cause the same diseases. But these bacteria are made passive and having no capacity to cause disease .when these vaccines is given in the small age, our body builds the immune system against them and makes the boy safe from future infection.

 When the passive bacteria or virus are given in our body system, due their presence, B-cell, one kind of white blood cell, become active and produce the antibody.  These antibodies combat with the diseases causing bacteria and virus. That is why when the vaccine is given for on time that works for a whole life time. However, all the vaccines do not work for a whole life time. As for e.g. tetanus vaccines works for a certain time. In such situation, the vaccines should be given in the fixed interval of time.

        When the child is born, he or she has an immune system to fight against with a few numbers of diseases and which are obtained from mother and can keep the child safe for only one year. But lacks the antibody to fight against with many kinds of disease. That is why the vaccines are needed to give within a time so as to safe from possible infection in the future.

REPTILES IN NEPAL

                        Nepal is a country consists of variety of plants and animals. It is only due to geographic distribution and climatic condition.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       We can see Dolphin to schizothorax, bullfrog to spade footed toad, coral snake to Himalayan python, peacock to Spiny Bladder and Rhino to red panda in or country. Here are 6300 species of reptiles in the world among them 141 species are suspected to found in Nepal which is 2.2% of world. Hence, Nepal is rich in aspect of reptiles.

    Reptiles are cool-blooded, air breathing vertebrates which include snakes, lizards, turtles, tortoise, crocodile, and alligators. Most of reptiles hatch from eggs

   Fossil studies suggest that reptiles evolved from their amphibian ancestors in the early Carboniferous Period, about 340 million years ago.  Reptiles suppressed amphibians as the dominant vertebrates on the land.

By the late Carboniferous Period, about 300 million years ago, reptiles had splits into several distinct types, characterized by difference in skulls and skeletons. The Anapsida, of which the turtle may be only living members, retained some similarities to the earliest reptiles. The Synapsida are sometime called the mammal-like reptiles. The Diapsida splits into two distinct groups: the archosaurs, meaning "ruling reptiles,” which includes crocodilians, pterosaurs, dinosaurs, and birds; and lepidosaurs, which give rise to tuatara and its extinct relatives, as well as lizard, snakes and worm lizard.

The Mesozoic Era is often called as the age of reptiles because this era is dominantly ruled by the dinosaurs on the land, the pleisoasaurs and ichthyosaurs in the sea, and the pterosaurs, or flying reptiles in the sky. Fossils studies suggested that the dinosaurs  may be the direct ancestors of birds.

This animal was killed by a disaster bout 65 million years ago. The reasons of massive extinction are still studied, but some scientists have found evidence that a giant asteroid or comet hit the earth that causes the abrupt climate changes that the dinosaurs could not survive.

In Nepal many research has been done in the field of reptiles. But it is our misfortunate that researches paper, reports, collected specimens are dispersed and some of them become the valuable property in the foreigner’s museum and we are still unknown about them. So there is need of centralized collection with proper record and correct data. It is the time for networking of Zoologist for proper research and establishment of living museum of nation. If we do so it is our true respect towards reptiles.

 

DNA AS BASIS of HEREDITARY MATERIAL

DNA is deoxy-ribose- sugar which is mainly found in the nucleus of eukaryotic cell, a small amount in mitochondria and chloroplasts. This is long chain of macromolecules of nucleotides with high molecular weights. It is also found in the chloroplast of prokaryotic cell.

It is formed by the end to end polymerization of large number of repeated units called deoxyribonucleotides or simply nucleotides.

A DNA molecule is composed of;

i)                            pentose sugar-deoxyibose sugar

ii)                        N-Bases-  1) Purines –a)Adenine (A)

                                                  b) Guanine (G)

                              2) Pyrimidines-a) Cytosine (C)

                                                         b) Thymine (T)
           DNA is a double helix or double stranded structure. In 1953 Watson and Crick establish the double structure on the basis of X-ray diffraction. According to them DNA is composed of anti-parallel

Polynucleotide strands that form a double helix around the central axis.

   The strands are made up of alternate band of deoxyribose sugar and phosphate molecules. Each deoxyribose sugar in the strand has one N-base horizontally attached to it at carbon-1. The four N-bases can occur in any possible sequence along the length of a strand. The N-base + deoxyribose sugar + phosphate together form one unit or deoxyribonucletide in the strand. Such many deoxyribosenucleotides are linked with each other in a linear fashion; therefore the resulting strand is described as the polynucleotide strand and DNA molecules as polynucleotide molecule.

The two polynucleotide strands are held together by hydrogen bonds between specific pairs of purines and pyrimidines. Purine of onepolynucleotide chain pairs with pyrimidine of other i.e. adenine (A) with thymine (T) and Guanine (G) with Cytosine(C). A and T are held together by two hydrogen bonds and G and C by three bonds. The sequence of bases in one polynucleotide chain automatically determines the order of bases in the other i.e. the two chains are complementary to each other when adenine occurs in one strand, thymine is present in corresponding  position in the opposite strand and vice versa . Similarly, where guanine is present in one strand, the other strand has cytosine opposite to it and vice versa.

The two strands of helix are of opposite polarity. If one chain run in 3'        5' direction (sugar phosphate linkage), then the other in 5'           3’ direction (sugar phosphate linkage)

 The function of DNA

a)            It is a genetic material, hence it carries hereditary information from parents to offspring.

b)           DNA has unique property of carbon copies which is essential for transfer of genetic information.

c)            It give rise to RNA through transcription process

d)           It plays key role in protein synthesis.

e)           any changes in the sequence of nitrogen bases due to addition or deletion causes mutation

cell the fundamental basis of life

Cell is microscopic mass of protoplasm which is the structural and functional basis of living organism. It is unseparatable part of living creatures. Although it is very small in size it has a very important functional work in living organism. The entire living organism functions like respiration, oxidation etc.takes place in cell.          The cell was discovered by Robert hook (1635-1703).firstly he cut a thin slice of cork and observed it .He observed many small, hollow, honey-comb like compartments. For each compartment he gave the name cell. The cell is a Latin word derived from cellula meaning small apartment.

There are two types of cell.They are plant cell and animal cell.

      The cell found in plant is called plant cell. Cell wall is the outermost covering of the plant cell. Cell wall is compose of cellulose, hemicellulose and pectin .It act a protective layer in the plant cell. It is followed by cell wall. It is semi-permeable in nature i.e. It checks the entry of solute and ions .Cell wall is the outermost layer in animal cell.

   Cell is composed of protoplasm .actually protoplasm is the functional unit of cell and life. Protoplasm with non-living inclusions and excluding cell wall is called protoplast. Protoplasm excluding nucleus is called cytoplasm. cytoplasm helps in the intracellular distribution of nutrients, metabolities and enzymes. It is site of glycolysis and biosynthesis of fatty acids, nucleotides and many protein. Cytoplasm consists of endoplasmic reticulum, vacuoles, mitochondria, golgibody, ribosome etc. there are two types of endoplasmic reticulum ie. Rough endoplasmic reticulum and smooth endoplasmic reticulum .Rough endoplasmic reticulum consists of ribosome in its outermost surface. Hence rough endoplasmic reticulum helps ion protein synthesis. Smooth endoplasmic reticulum does not contain ribosome and helps in biosynthesis of Phospholipids. Actually ribose is the site of protein synthesis. Ribosome is found in all type of cells. Golgicomplex is found in almost all type of Eukaryotic cell. It forms secretory vessels which moves to the surface of the cell and discharge the secretory molecules outside the cell. It stores certain protein and lipids. It is found in endocrine gland as it helps in secretion. Endoplasmic reticulum and golgicomplex forms lysosome. Mitochondria contains homogeneous granular matrix and matrix contains lipid, protein, DNA, RNA, ribosomes, granules and enzymes. Kerb’s cycle takes place in mitochondria during which food material is completely oxidized into CO2 and H2O. So mitochondria I called powerhouse of the cell. Chloroplast is found in only plant cell ..as chloroplast consists of chlorophyll it helps in photosynthesis .Green color in chlorophyll is due to the nitrogen.

     Hence all the activities of living organism i.e. oxidation, respiration, production of ATP i.e. energy etc takes place in cell. In all living organism all the vital activities are due to the result of combined action of these cells. Therefore cell is the one of the most fundamental basis of life.

global warming

 Global warming refers to the rising global temperature. It causes climate change that is responsible for; flood; frequent and intense rain and snow; change in the normal occurrence of monsoon thereby affecting crop production; drought; landslide; vector born diseases; more frequent tropical stroms;  forest fire and extinction of species due o the loss of ecological niches.

   Scientist all over the world believe that global  warming is mainly  caused by two processes as given below:

1)Increase in the level of green house gases such as carbon dioxide(co2),chlorofluorocarbons(CFCS), methane and water vapour due burning of fossil fuel and deforestation.

2)  Milankovitch cycle

        According to milankovitch cycle, there is a periodic change in the Earth’s orbit and rotation around the sun that alter solar radiation reaching the Earth and cause global warming   as well as cooling.

Green house effect is the major cause of global warming. In the troposphere level of atmosphere  there are  gases like co2,CFCS, methane and water vapour that aloe visible light and infrared radiation from the sun to reach the earth but do not allow heat from earth to escape out thereby increasing the temperature of the earth.

      Earth faced global warming and cooling in the past , long before human evolved   in the Earth .However the global warming occurring at present is found to be very rapid due to excess production of co2 .This is harmful to the natural ecosystem as they cannot adopt the fast occurring environment change thereby increasing the chance of species extinction.

       Global warming directly  effects the life and life cycle of organism, glaciers on mountains, heats up sea, melts polar ice, increases chance of forest fire, cause drought and dries up river, ponds and lakes.

    The melting of glaciers and polar ice increases sea level. Studies  have shown that the sea level has raised by 4-8 inches during the last 100 years. The rise of sea level brings coastal flooding that is dangerous to the island.

     Global warming heats the sea water and interferes with the circulation. The important circulation in the sea are: Arctic circulation, El Nino and LA Nina. They effect climate in most parts of the earth. High temperature can slow down Arctic circulation and increases the frequency and intensity of El Nino .

South America where as LA Nina causes the upwelling of cold  water in the west coast of south America and accumulation of warm water in the east coast of Asia near Indonesia . LA Nina

 cause rain and monsoon in India, Africa and North America.

Global warming has brought the following consequences:

a)            Late monsoon affecting crop production.

b)           Insecure supply of water

c)            Rapid melting of glaciers has endangered the existence of temperature lakes in high altitudes

d)           High possibility of forest fire

e)            Man as well as animals are forced to live under stress due to warm climate.

f)              Decreases the volume of water in the high altitude rivers and streams has threatened the life of the coldwater fishes and other aquatic organism.

g)           Land slides in many parts.

h)           Out break of diseases due to insufficient supply of water in hills.

i)              Excessive melting of ice has caused flooding in terai region ,affecting the life style of thousands of people and destroying land and crop.

             Control Measures:

    We must act responsibly against the global warming before it’s  too late.the following activities act against global warming:

a)            reduction in the use of fossil fuel

b)           increase hydropower to generate electricity

c)            maximum use of biogas and solar energy

d)           protecting and increasing the forest as they  absorbs co2, the main cause of global warming.

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