Biology-Today.com

Å= angstrom= 0.1 m?

ACTH= adreno cortico tropic hormone

ADH= anti diuretic hormome

ADP= adenosine diphosphate

AHF= anti hemophilic factor

AHG= anti hemophilic glubulin

AIDS= acquired immune deficiency syndrome

AMP= adenosine monophosphate

ANS= autonomic nervous system

ATP= adenosine triphosphate

AVN= atrio ventricular node

BGC= Bacillus Calamette Gurein Vaccine for tuberculosis

BCOP= blood colloidal osmotic pressure

BMR= basis metabolic rate

BOD= biochemical oxygen demand

CHP= capsular hydrostatic pressure

CNS= central nervous system

COD= chemical oxygen demand

CRF= corticotropin releasing factor in the endocrine system

CS= cytochrome system

Man= 100 years

Horse= 65 years

Parrot= 150 years

Whale= 40 years

Dog= 25 years

Elephant= 90 years

Turtle= 200 years

Cat= 40 years

Monkey= 25 years

Malaria is caused by a protozoan parasite, Plasmodium, and is carried and spread to various persons and places by the female mosquito, Anopheles.

History of Discovery: In older times it was supposed that malaria disease was caused by poisonous gases. The plasmodium germ as the causative agent of malaria was discovered in 1880 by Charles Laveran. Sir Patrick Manson suggested that malarial parasites are probably introduced into our blood by the bite of mosquito. Dr. Ross (1897) finally discovered the presence of malarial parasites in the body of female mosquito which had fed on the blood of malarial patient. He was awarded Nobel Prize in the year 1902 for working out the complete cycle of malarial parasites. It was Grassi in 1917 who studied the cycle of human malaria in Anopheles.

Species of Plasmodium: About 4 species are known to infect man and cause different kinds of malaria.

(a) Plasmodium malariae- causes Quartan malaria.

(b) P. vivax- causes Benign tertian malaria.

(c) P. falciparum- causes Malignant tertian malaria.

(d) P. ovale- causes mild tertian malaria.

Of these four species, P. vivax is the most widespread and prevailing species of the temperature region; and P. falciparum is confined to warmer countries only.

Life Cycle: The life cycle of Plasmodium consists of an exogeneous sexual phase called sporogony which multiplies in female mosquito and an endogeneous asexual phase called schizogony which takes place in man. Thus, it is genetic, i.e., life cycle is completed in two different kinds of hosts- one vertebrate (man) and the other invertebrate (mosquito). Mosquito is termed the primary or final host while man, the secondary or intermediate host.

It is a parasitic flagellate inhabiting the blood and other fluids of all groups of vertebrates from fishes to mammals. It is transmitted to them by blood sucking invertebrates like insects and leeches.

The adult trypanosoma consists of a fusiform body pointed at both ends. A single oral nucleus is present in the center.

There is a single flagellum arising from a minute  granule, the blepharoplast, near the posterior end of the body. Near the blepharoplast, there is a large body called the kinetoplast. There is a thin irregular rippling fold called the undulating membrane along one of the margins of the body. The flagellum extends forwards along the free edge of the undulating membrane and then projects freely in front of the body.

Reproduction occurs by longitudinal binary fission.

Several species of Trypanosoma are pathogenic to man and domestic animals. T. gambiense causes sleeping sickness in man. The parasite first lives in the blood and then enters the cerebrospinal fluid of the brain and spinal cord. The blood sucking tse- tse flies (Glossina palpalis) act as vectors.

The study of the animal behaviour is called Ethology which originates from two greek words “Ethos” meaning “Character” or “Habit” or “Custom” and “logos” meaning “Study” which was used earlier to interpret character through the study of body gesture or it may be called as descriptive study of the “habitats of animals”. Animal behaviour is the study of motor activities patterns as observed in the activity of rat when it will be exposed to a strange environment (motor activity). The feeding response of rat signifies specific activity pattern. In a “behaviour” of an organism, a number of specific behaviours combine with each other. Behaviour includes all those processes by which an  animal senses the external world and the internal states of its bodies and responds to changes which it perceives. Ethology deals with the study of animal behaviour in its natural habitat. The display of specific behaviour pattern of an organism is dependent on its genetic make up and the environment in which it inhabits. The behavioural science of Ethology developed from the works of A. Vesalius (1543) and Darwin and Wallaces’ theory of evolution. A. Vesalius (1543) gave the structural details of human brain in his work “De Humani Corporis Fabrica” which has provided first insight of the nervous system (Grier 1984). Neurobiology, physiology and psychology are the backbones of behavioural studies of animals. Herbert Spencer (1855) in his book “Principles of Psychology”  dealt with the mental continuity in the psychology of lower animals to that of higher animals and supported the theory of inheritance of acquired characteristics proposed by Lamarck. This was expanded further in 1896 from reflex behaviour to choice or free will behaviour.

Further researches from 1890 to 1910 dealt with the mechanism of internal control of behaviour. Such works developed independently to each other and provided basis for establishing new branches like ethology, neurobiology and comparative psychology.

Behaviour may be defined as the observable act of animals (Grier 1984) which is dependent on ecology and sociobiology on one hand and neurobiology on the other hand.

According to Kendel (1976) behariour can be defined “as all observable muscular and secretory responses to changes in an animal’s internally or external environment”. It includes muscular contraction, secretions, courtship and communication. Behariour includes five parameters which are patterns, stimuli, mechanisms, levels and consequences. Pattern is a beharioural unit which occurs after a stimulus. The stimulus may be any information, which an organism collects by its sensory organsm interpreting it in the nervous system and reacting to it. Only specific informations are interpreted and used in motor activity which is known as behaviroural stimulus. A stimulus may be useful at one time but becomes useless on another occasion. Finally one must observe the consequences of performing an act.

International code of Zoological Nomenclature is huge documents of great importance to preserve the given names of different animals and to increase their universality and uniqueness. It includes several clauses and their sub-divisions. It was internationally accepted at the 5th Conference of the International Commission on Zoological Nomenclature, held in Berlin in 1910. The modern rules have, however, been published in 1964.

The hereditary colorectal cancer syndrome is commonly known as familial adenomatous polyposis coli (FAP), where hundreds of polyps are found. This is associated with APC mutation.

There is another kind of hereditary predisposition of colon cancer where there is any increase in the number of polyps. The patient with this condition is called hereditary nonplyposis colorectal cancer or HNPCC. In these cases the tumor cells exhibit a normal number and karyotypes of the chromosomes.

The DNA repairing mechanism is one of the important events in the cellular function. Because of the absence of proof reading proteins, spontaneous mutation of the remaining functional gene produces a clone of somatic cells that accumulate mutations unusually rapidly. Thus most cancers arise from cells deficient in mismatch proof reading, therefore, have a greatly enhanced chance of becoming cancerous. We are fortunate that most of us inherit two good copies of each gene that encodes a mismatch proof reading protein. Mutations in any one of this gene inevitable DNA replication error and immediately elevate the spontaneous mutation rate by a hundred fold or more. These genetically unstable cells allow a clone of cells to progress malignancy. This genetic instability produces changes in the chromosomes; because the changes occur in short mono or dinucleotide repeat. This type of mutation in mismatch repair genes are found in about 15% of colorectal cancer, with no inheritable mutation and the chromosome karyotype is also normal.