Unit two

I. Pre-reading Activities.

A. Practise the pronunciation of the following words and memorize them.

• delineation /dɪlɪniˈeɪʃən/ • sequence /ˈsiːkwəns/

• species /ˈspiːʃiːz/ • poultry /ˈpəultri/

• lymphocyte /ˈlimfəsaɪt/ • vaccinology /ˌvæksɪˈnɔlədʒi/

• physiological /ˌfɪziəˈlɔdʒɪkəl/ • thorough /ˈθʌrə/

• lineage /ˈlɪniɪdʒ/ • cholera /ˈkɔlərə/

• fowl /faul/ • histocompatibility /ˈhistəkəmpætəˈbiliti/

• avian /ˈeɪviən/ • repertoire /ˈrepətwɑː/

B. Read and discuss the questions.

→ The text below is called “Chickens Are Not Mice with Feathers”. What do you think the text is about?

→ Have you ever heard about comparing mice with chickens? If yes, what exactly do you know about this comparison?

→ Why should we investigate avian immune system?

C. Match the following words with their definitions.

1. restrict A. to come into possession or control of often by unspecified means

2. contribute B.  to confine within bounds

3. species C. to help to bring about a result  

4. crucial D.  new and not resembling something formerly known or used

5. thorough E. to manage or deal

6. avian F. to develop gradually by a natural process

7. novel (adj.) G.  carried through to completion

8. evolve H. a group of living organisms consisting of related similar individuals capable of exchanging genes or interbreeding

9. key (adj.) I. to come into possession of

10. gain J.  of, relating to, or derived from birds 

11. counterpart K. essential, of vital importance

12. incentive (n.) L. important, fundamental

13. handle (v.) M. descent in a line from a common progenitor

14. acquire N.  a person or thing extremely like another

15. progeny O.  a motive or incitement, esp. to action

II. Reading Activities.

1. Read the text below using a dictionary. Chickens Are Not Mice with Feathers

Avian Immunology,

Jim Kaufman

Immunology is not just restricted to investigations on the immune systems of mice and humans. Historically, studies on other species have contributed greatly to the development of immunological understanding. Amongst these other species, birds have provided an invaluable model for investigating basic immunological mechanisms. Birds have also played a crucial role in the development of vaccinology, and they still do to this day. The first attenuated vaccine discovered by Pasteur was directed against fowl cholera, a poultry disease. Likewise the first widely used vaccine against a naturally occurring cancer, Marek's disease, was developed for the poultry industry. The current threat from avian influenza reminds us of the necessity for gaining a thorough understanding of the avian immune system in order to develop novel and effective

strategies for control.

Birds have many immunological mechanisms in common with mammals but have evolved a number of quite distinct strategies; they achieve the same goal through use of different mechanisms. Some of their different physiological characteristics such as their lung ventilation system, significantly different from the mammalian one, may partly explain the pressures for the evolution of different mechanisms.

One key feature of research on the avian immune system has been the seminal contributions it made on the key role of lymphocytes in adaptive immunity, graft-versus-host responses, delineation of the two major lymphocyte lineages - B cells and T cells - and gene conversion for developing the immunoglobulin repertoire. In addition the chicken major histocompatibility complex (MHC) - the first non-mammalian MHC to be sequenced - is compact, considerably smaller than its mammalian counterpart, and strongly associated with resistance to certain infectious diseases.

No doubt the availability of the entire chicken genome sequence will help provide us with a more precise picture and a better understanding of the avian immune system.

Birds have been described as living dinosaurs, as exemplified by the discovery of dinobirds, mainly in China. This discovery provides a major incentive to carefully study the avian immune system and gain a better understanding of the rules of evolution. At the same time, we should bear in mind that infections provide an important selection pressure and immunocompetence is a valuable trait for the survival of a species. I firmly believe that a full understanding of the immune system will be acquired only through comparative analysis of its structure, function and physiology in a multitude of different species.

Apart from all these fundamental aspects of avian immunology, practical aspects should not be neglected. As consumption of meat is expected to increase considerably during this century (Delgado's livestock revolution) it must be expected that poultry will have a key contribution.

Reproductive traits, a short productive lifespan, production of eggs, absence of dietary restrictions and worldwide distribution, all favour the use of poultry as a major source of animal protein. These same characteristics are also valuable for the avian research model. Well-defined inbred strains of chickens are already available. These can produce large numbers of progeny that are relatively easy to house and handle in laboratory research. From this point of view, chickens can be considered 'mice with feathers'.

B. Look through the text again and translate the following parts from English into Russian:

― Immunology is not just restricted to investigations on the immune systems of mice and humans.

― … studies on other species have contributed greatly to the development of immunological understanding

― birds have provided an invaluable model

― Likewise the first widely used vaccine against a naturally occurring cancer was developed

― The current threat from avian influenza reminds us of the necessity for gaining a thorough understanding of the avian immune system in order to develop novel and effective

strategies for control.

― No doubt the availability of the entire chicken genome sequence will help provide us with a more precise picture

― Birds have been described as living dinosaurs, as exemplified by the discovery of dinobirds, mainly in China.

― we should bear in mind

― infections provide an important selection pressure

― As consumption of meat is expected to increase considerably

― a short productive lifespan, production of eggs, absence of dietary restrictions and worldwide distribution, all favour the use of poultry as a major source of animal protein.

― Well-defined inbred strains of chickens are already available.

C. Read the text again and answer the following questions in your own words.

1. What was the disease against which the first attenuated vaccine was discovered? 2. Why does a careful study of avian immune system help us to understand better the rules of evolution? 3. What practical application will we get from these studies?

4. What are the differences between mammalian and avian immune systems?

5. What is in author’s opinion the only way for a full understanding of the immune system?

6. How can the studying of the avian immune system be useful for science and for people?

7. What qualities help poultry to be a major source of protein for humans? 

8. Why cannot chickens be called "mice with feathers"?

9. What particular qualities of the chicken MHC can you name?

10. Why does the discovery of “dinobirds " provide a major incentive to careful study of avian immune system?

D. The text below has been jumbled. Arrange the paragraphs in the correct order to make a full story.

Rats and Mice are the Most Common Chicken Predators.

(1) Eggs may also be removed from the nesting box and taken to the rats’ lair along with feathers and bedding that the rats use for nesting material. The feathers are collected from the floor or plucked from the chickens.

(2) Some birds survive but lose toes, feet and even legs to the rats’ incredibly sharp teeth. Any chickens showing signs of having been attacked by rats must be checked out by a vet immediately because of the risk of disease and infection resulting from the near-death encounter.

Eggs are easy targets often consumed on the spot, leaving telltale pieces of broken eggs behind that can lead a poultry-keeper to erroneously believe a member of the flock is responsible.

(3) Chickens are most in danger from the presence of rodents at night, when the birds are roosting in their coop. Rats commonly emerge in the darkness to kill chicks and even bantams (miniature chicken breeds), dragging prey back to their lair.

(4) Another form of poison is much slower-acting but will kill the rodents over time, causing death by dehydration that results in no attendant smell of decomposition. This type can sometimes be safe to use in the vicinity of humans and other animals.

(5) Poison generally comes in the form of lethally dosed corn or wheat. This is as dangerous for chickens to eat as it is for rats and mice, so it must be located underneath coops in places where the birds cannot reach no matter how hard they try. Unless dead bodies are found and removed, they will decompose in situ and smell.

(6) Both mice and rats will steal from poultry feeders, use drinkers and harvest corn and layers pellets from the floor of the run and coop. (7) Mice being smaller aren’t as big a problem as rats. They don’t steal chicks or bantams away, although they will steal feathers—often nibbling at tail feathers in particular - and their droppings can be consumed by the chickens, spreading disease in this way and by urinating on food and in drinking water.

(8) Rodents are kept under control by using either poison or traps, or both. Traps are generally safer for chickens but it is unacceptable to release the captured rats elsewhere. They must be killed, which is a job not everybody feels able to do and must be done quickly and humanely, the same as with any other animal.