1 The DNAs which are to be used as passenger DNA and the vehicle DNA are extracted out of their cells by lysing the cells with the suitable enzyme.
2 The extracted DNAs are isolated from other cell contents by ultra centrifugation and purified.
3 Both the passenger and vehicle DNAs are then, cleaved by using the same restriction endonuclease so that they have complementary sticky ends.
4 The complementary sticky ends of the passenger and vehicle DNAs are joined with ligase enzyme. This gives rise to a recombinant DNA.
5 The recombinant DNA is now inserted into a host cell such as E. coli.The bacteria to be used as hosts should be without plasmids.
6 The host cells are treated with calcium chloride or lysozyme. It creates transiet pores in their wall and makes the latter permeable to recombinant DNA.
7 The recombinant DNA is added to be the culture in which such as bacteria are growing. The recombinant DNA is taken up by the bacteria. It replicates when the host bacteria divide and give rise to multiple copies of recombinant DNA.

1. A new system of medicine gene therapy, may develop to treat some hereditary disease such as SCID, haemophilia etc.
2. It is the technique for curing genetic disease through replacing a “Faculty Gene” by a normal healthy functional gene.
3. The first gene therapy used in severe combined immune deficiency (SCID) Pateint.
4. Infact with SCID disorder lack the enzyme adenosine deaminase (ADA)
5. ADA enzyme involved in purine metabolism.
6. These patients have no functioning T & B lymphocytes.
7. The affected child of SCID develops recurrent infection early in life because they have no immune response against invading pathogen.
8. The ideal approach would be to give the patient a functioning ADA by gene therapy.
9. Thus, genetic disorder can be over come by introducing specific gene.

 Transfer of desired genes from one organism into another is an important aspect of genetic engineering.
 Gene transfer is achieved by two kinds of transfer methods:
(i) Indirect method through vectors or carriers and
(ii) Direct or vector less transfer method
 Vectorless Gene Transfer : Foreign genes can also be transferred directly by the following methods:
(a) Electroporation : It creates transients ( temporary pores) in the plasma membrane to facilitate entry of foreign DNA.
(b) Chemical mediated genetic transformation: It involves certain chemicals such as polyethylene glycol (PEG), that help in the uptake of foreign DNA into host cells.
(c) Microinjection : It is the introduction of foreign genes into plant or animal cells using microinjection or glass needles.
(d) Particle gun/ Biolistic method: It is a technique in which tungsten or gold particle coated with foreign DNA are bombarded into target cells to facilitate entry of the foreign genes.

(e) Liposome mediated gene transfer : In this method DNA encloses within lipid begs. These lipid begs fused with protoplast.

Aestivation or æstivation (from Latin: aestas, summer, additionally spelled estivation in American English) is a condition of creature lethargy, like hibernation, described by inertia and a brought down metabolic rate, that is entered because of high temperatures and dry conditions.[1] It happens amid times of warmth and dryness, the hot dry season, which are regularly the mid year months.
Invertebrate and vertebrate creatures are known not this state to maintain a strategic distance from harm from high temperatures and the danger of parching. Both physical and amphibian creatures experience aestivation.
Living beings who aestivate give off an impression of being in a genuinely “light” condition of lethargy, as their physiological state can be quickly turned around, and the life form can rapidly come back to an ordinary state. A study done on Otala lactea, a snail local to parts of Europe and Northern Africa, demonstrates that they can wake from their torpid state inside ten minutes of being acquainted with a wetter domain. Fossil records demonstrate that the demonstration of aestivating might be a few hundred million years of age.
Invertebrate and vertebrate creatures are known not this state to maintain a strategic distance from harm from high temperatures and the danger of parching. Both physical and amphibian creatures experience aestivation.
Living beings who aestivate give off an impression of being in a genuinely “light” condition of lethargy, as their physiological state can be quickly turned around, and the life form can rapidly come back to an ordinary state. A study done on Otala lactea, a snail local to parts of Europe and Northern Africa, demonstrates that they can wake from their torpid state inside ten minutes of being acquainted with a wetter domain. Fossil records demonstrate that the demonstration of aestivating might be a few hundred million years of age.
Finally, aestivation is summer rest and amid aestivation, creatures normally tend to rest in a shady and cool spot. They take rest amid the hot hours of daytime. Among numerous creatures that perform aestivation are, frogs, night crawlers, snails, crocodiles, reptiles, tortoise and some more. In aestivation, typically unfeeling creatures like reptiles keep up their body temperature by diminishing their metabolic exercises and shielding themselves from high temperature. That is the motivation behind why aestivation is likewise called summer rest. Normally in summer the body temperature rises, particularly that of creatures of land and water and reptiles can continue expanding so it gets to be fundamental for them to discover a shay and damp spot to shield themselves from temperature dis-regulation in their bodies.For occurrence, frogs have a tendency to go in the most profound piece of lakes to secure themselves.

Hibernation is a condition of idleness and metabolic gloom in endotherms. Hibernation alludes to a season of heterothermy that is described by low body temperature, moderate breathing and heart rate, and low metabolic rate. Albeit customarily held for “profound” hibernators, for example, rodents, the term has been re-imagined to incorporate creatures, for example, bears and is presently connected taking into account dynamic metabolic concealment as opposed to in view of total body temperature decrease. Numerous specialists trust that the procedures of every day torpor and hibernation shape a continuum and use comparable mechanisms. Hibernation amid the mid year months is known as aestivation. Some reptile species (ectotherms) are said to brumate, or experience brumation, yet any conceivable similitudes in the middle of brumation and hibernation are not immovably settled. A few creepy crawlies, for example, the wasp Polistes exclamans, sleep by collecting together in gatherings in secured places called hibernacula.
Frequently connected with low temperatures, the capacity of hibernation is to save vitality amid a period when adequate nourishment is occupied. To accomplish this vitality sparing, an endotherm will first diminishing its metabolic rate, which then results in a diminished body temperature. Hibernation may most recent a few days, weeks, or months relying upon the species, encompassing temperature, time of year, and individual’s body condition.
Before entering hibernation, creatures need to store enough vitality to last through the whole winter. Bigger species get to be hyperphagic and eat a lot of nourishment and store the vitality in fat stores. In numerous little species, nourishment reserving replaces eating and getting to be fat. Some types of warm blooded creatures sleep while gestating youthful, which are either conceived while the mother rests or presently a short time later.
For instance, the female polar bear goes into hibernation amid the frosty winter months to bring forth her posterity. She loses 15-27% of her pre-hibernation weight and uses put away fats for vitality amid times of nourishment shortage, or hibernation. It is obvious that pregnant female polar bears altogether build body mass before hibernation, and this increment is further reflected in the heaviness of their posterity. The fat amassing before hibernation in female polar bears empowers them to give an adequate and warm, sustaining environment for their babies