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Saturday, March 17, 2012

article : Classification Organism with three domain - six kingdom Kingdom Classification System

In the post previous articles click here,  classification system into the five kingdom system. Now This divides cellular organisms into:

The Kingdoms of Organisms:

This presentation has taken as standard the "three domain - six kingdom" model of organism diversity, based on 16S ribosomal RNA sequence comparisons, of Carl Woese and co-workers. This divides cellular organisms into:
  • Bacteria (Eubacteria),
  • Archaea (Archaebacteria) and
  • Eukarya (Eukaryotes; further divided into Protista, Plantae, Animalia and Fungi).
Reference:
GJ Olsen and CR Woese (1993). FASEB Journal 7: 113-123.

However, Robert H Whittaker and Lyn Margulis have suggested that organisms should be divided into five kingdoms: that is,
  • Monera or Procaryotae (prokaryotes, including Bacteria and Archaea)
  • Protista (eukaryotes with single- or colonial cellular organisation, may be photosynthetic)
  • Fungi (generally multinucleate eukaryotes with walled syncytia)
  • Animalia (wall-less eukaryote cells organised into complex organisms)
  • Plantae (generally autotrophic plants, mostly with photosynthetic plastids, simple multicellular to advanced tissue organisation)
This model includes some "plants" as protists, and makes no distinction between Archaea and Bacteria.
Reference:
RH Whittaker and L Margulis (1978). BioSystems 10: 3-18

To complicate matters, James Lake and co-workers have lately proposed a radical re-structuring of the "universal" phylogenetic tree, to split Archaea into Halobacteria, Methanogens and Eocytes. This would mean there are three major groupings of prokaryotes (Eubacteria + Halobacteria, Methanogens and Eocytes), which could all constitute kingdoms on their own, given each is as unrelated to the others as any are to Eukarya.
Reference:
JA Lake (1991). Trends in Biochemical Sciences 16: 46-50.

There is also a 2-empire / 8-kingdom scheme, with Archaeobacteria and Eubacteria as kingdoms in Empire Bacteria, and 6 kingdoms in Empire Eukaryota:
  • Archezoa (primitive eukaryotes without chloroplasts or mitochondria)
  • Protozoa (unicellular wall-less eukaryotes with mitochondria)
  • Chromista (photosynthetic organisms with chloroplasts within the lumen of the rough ER; eg: diatoms, brown algae, cryptomonads, oomycetes)
  • Plantae (photosynthetic organisms with chloroplasts within cytoplasm; all land plants, many green algae)
  • Fungi
  • Animalia
Reference: 
Cavalier-Smith T (1993). Microbiological Reviews 57: 953-994

Source article :

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Article : Classification Organism with Five Kingdom System

Many classification of living things depends on the criteria used. One of the followingclassifications are made based on certain criteria: 


Classification Organism with Five Kingdom Classification System

Once upon a time, all living things were lumped together into two kingdoms, namely plants and animals (at least, that's how I learned it). Animals included every living thing that moved, ate, and grew to a certain size and stopped growing. Plants included every living thing that did not move or eat and that continued to grow throughout life. It became very difficult to group some living things into one or the other, so early in the past century the two kingdoms were expanded into five kingdoms: Protista (the single-celled eukaryotes); Fungi (fungus and related organisms); Plantae (the plants); Animalia (the animals); Monera (the prokaryotes). Many biologists now recognize six distinct kingdoms, dividing Monera into the Eubacteria and Archeobacteria.
All I can say is that the sytem holds true for this week, at least. It might even hold up for a century or two. Accepted systems of classification have changed at a far faster pace than the species have taken to evolve, that's for certain.
Kingdoms are divided into categories called phyla, each phylum is divided into classes, each class into orders, each order into families, each family into genera, and each genus into species. A species represents one type of organism, such as dog, tiger shark, Ameoba proteus (the common amoeba), Homo sapiens (us), or Acer palmatum (Japanese maple). Note that species names should be underlined or written in italics.
Classifying larger organisms into kingdoms is usually easy, but in a microenvironment it can be tricky. If you have had a little biology, a good exercise is to describe individual living things, and to try to classify them as to kingdom.

Monera (includes Eubacteria and Archeobacteria)

Individuals are single-celled, may or may not move, have a cell wall, have no chloroplasts or other organelles, and have no nucleus. Monera are usually very tiny, although one type, namely the blue-green bacteria, look like algae. They are filamentous and quite long, green, but have no visible structure inside the cells. No visible feeding mechanism. They absorb nutrients through the cell wall or produce their own by photosynthesis.

Protista

Protists are single-celled and usually move by cilia, flagella, or by amoeboid mechanisms. There is usually no cell wall, although some forms may have a cell wall. They have organelles including a nucleus and may have chloroplasts, so some will be green and others won't be. They are small, although many are big enough to be recognized in a dissecting microscope or even with a magnifying glass. Nutrients are acquired by photosynthesis, ingestion of other organisms, or both.

Fungi

Fungi are multicellular,with a cell wall, organelles including a nucleus, but no chloroplasts. They have no mechanisms for locomotion. Fungi range in size from microscopic to very large ( such as mushrooms). Nutrients are acquired by absorption. For the most part, fungi acquire nutrients from decaying material.

Plantae

Plants are multicellular and most don't move, although gametes of some plants move using cilia or flagella. Organelles including nucleus, chloroplasts are present, and cell walls are present. Nutrients are acquired by photosynthesis (they all require sunlight).

Animalia

Animals are multicellular, and move with the aid of cilia, flagella, or muscular organs based on contractile proteins. They have organelles including a nucleus, but no chloroplasts or cell walls. Animals acquire nutrients by ingestion.

A "mini-key" to the five kingdoms

Suppose you see something in freshwater that certainly appears to be living. How can you begin to determine what it is? Here is a key (not quite perfect) that you might use to help determine the kingdom to which it belongs.
  • 1. Is it green or does it have green parts?
    • Yes - go to 2
    • No - go to 3
  • 2. Could be a plant or a protist, or blue-green bacteria. Make sure that the green is really part of the organism, though. An animal might have eaten something green, for example.
    • Single-celled? go to 6
    • Multicellular? Plantae. Look for cell walls, internal structure. In the compound microscope you might be able to see chloroplasts.
  • 3. Could be a moneran (bacteria), protist, fungus, or animal.
    • Single-celled - go to 4
    • Multicellular (Look for complex or branching structure, appendages) - go to 5
  • 4. Could be a moneran or a protist. Can you see any detail inside the cell?
    • Yes - Protista. You should be able to see at least a nucleus and/or contractile vacuole, and a definite shape. Movement should be present, using cilia, flagella, or amoeboid motion. Cilia or flagella may be difficult to see.
    • No - Monera. Should be quite small. May be shaped like short dashes (rods), small dots (cocci), or curved or spiral shaped. The largest them that is commonly found in freshwater is called Spirillum volutans. It is spiral shaped, and can be nearly a millimeter long. Except for Spirillum, it is very difficult to see Monerans except in a compound microscope with special lighting.
  • 5. Animalia or Fungi. Is it moving?
    • Yes - Animalia. Movement can be by cilia, flagella, or complex, involving parts that contract. Structure should be complex. Feeding activity may be obvious.
    • No - Fungus. Should be branched, colorless filaments. May have some kind of fruiting body (mushrooms are a fungus, don't forget). Usually attached to some piece of decaying matter - may form a fuzzy coating on or around an object. In water, some bacterial infections of fish and other animals may be mistaken for a fungus.
  • 6. Most likely Protista. If it consists of long, unbranched greenish filaments with no apparent structure inside, it is blue-green bacteria (sometimes mistakenly called blue-green algae), a Moneran.
Most green protists are flagellates, that is, they move rapidly with a spiralling motion. Unless you get them to stop, you can't really see the flagella. Watch out for colonial protists, though, such as Volvox, which forms a spinning ball of green cells. Don't be fooled into thinking it is a plant.
Remember, the more you observe the organism, the more sure you can be. Many living things have stages that make them resemble members of another kingdom.

Source article : 
http://www.ruf.rice.edu

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Thursday, June 11, 2009

Article : More Know about Ascaris lumbricoides

HOSPES & DISEASE NAME

Ascaris lumbricoides,
common saying 'soil transmitted helmint' is the largest of the intestinal nematodes parasitizing humans. It has worldwide in distribution and most prevalent through out the tropics,subtropic,and more prevalent in the countryside than in the city.The disease's name is ascariasis.


¨MORFOLOGY

Adult: The adults are cylindrical in shape, creamy-white or pinkish in color. The female averages 20
-35cm in length, the largest 49cm. The male is smaller, averaging 15-31cm in length and distinctly more slender than the female. The typical curled tail with a pair sickle like copulatory spines. On the tip of the head there are three lips, arranged as "a Chinese word “ 品They have a complete digestive tract. Reproductive organs are tubular. male has a single reproductive tubule. The female has two reproductive tubules and the vulva is ventrally located at the posterior part of the anterior 1/3 of the body. The three lips are seen at the anterior end. The margin of each lip is lined with minute teeth which are not visible at this magnification.

Egg : There are three type of the eggs. They are fertilized eggs, unfertilized eggs and decorticated eggs. We usually describe an egg in 5 aspects: size, color, shape, shell and content.

Fertilized eggs: broad oval in shape, brown in color, an average size 60× 45µm. The shell is thicker and consists of ascaroside, chitinous layer, fertilizing membrane and mammillated albuminous coat stained brown by bile. The content is a fertilized ovum. There is a new-moon(crescent) shaped clear space at the each end inside the shell.

Unfertilized egg: Longer and slender than a fertilized egg. The chitinous layer and albuminous coat are thinner than those of the fertilized eggs without ascaroside and fertilizing membrane. The content is made of many refractable granules various in size.

Decorticated eggs: Both fertilized and unfertilized eggs sometimes may lack their outer albuminous coats and are colorless.


LIFE CYCLE

This worm lives in the lumen of small intestine, feeding on the intestinal contents, where the fertilized female lays eggs. An adult female can produce approximately 240,000 eggs per day, which are passed in feces. When passed, the eggs are unsegmented and require outside development of about three weeks until a motile embryo is formed within the egg.


After the ingestion of embryonated eggs in contaminated food or drink or from contaminated fingers, host digestive juices acts on the egg shell and liberate the larva into the small intestine. These larvae penetrate the intestinal mucosa and enter lymphatics and mesenteric vessels. They are carried by circulation to the liver, right heart and finally to the lungs where they penetrate the capillaries into the alveoli in which they molt twice and stay for 10-14days and then they are carried, or migrate, up the bronchioles, bronchi, and trachea to the epiglottis. When swallowed, the larvae pass down into the small intestine where they develop into adults. The time from the ingestion of embryonated eggs to oviposition by the females is about 60-75 days. The adult worms live for about one year. The ascarid life cycle is as the following diagram.


Pathogenitas

There are two phase in ascariasis:
  1. The blood-lung migration phase of the larvae: During the migration through the lungs, the larvae may cause a pneumonia. The symptoms of the pneumonia are low fever, cough, blood-tinged sputum, asthma. Large numbers of worms may give rise to allergic symptoms. Eosionophilia is generally present. These clinical manifestation is also called Loeffler’s syndrome.
  2. The intestinal phase of the adults. The presence of a few adult worms in the lumen of the small intestine usually produces no symptoms, but may give rise to vague abdominal pains or intermittent colic, especially in children. A heavy worm burden can result in malnutrition. More serious manifestations have been observed. Wandering adults may block the appendical lumen or the common bile duct and even perforate the intestinal wall. Thus complications of ascariasis, such as intestinal obstruction, appendicitis, biliary ascariasis, perforation of the intestine, cholecystitis, pancreatitis and peritonitis, etc., may occur, in which biliary ascariasis is the most common complication.

Diagnosis

¨ The symptoms and signs are for reference only. The confirmative diagnosis depends on the recovery and identification of the worm or its egg.

1. Ascaris pneumonitis: examination of sputum for Ascaris larvae is sometimes successful.
2. Intestinal ascariasis: feces are examined for the ascaris eggs.

(1) direct fecal film: it is simple and effective. The eggs are easily found using this way due to a large number of the female oviposition, approximately 240,000 eggs per worm per day. So this method is the first choice.
(2) brine-floatation method:
(3) recovery of adult worms: when adults or adolescents are found in feces or vomit and tissues and organs from the human infected with ascarids , the diagnosis may be defined.

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articel : Trichuris trichiura

Morphology

Adult: the worm looks like a buggy whip, the anterior 3/5 is slender and the posterior 2/5 is thick. It is pinkish gray in color. The female worm is 3-5 cm in length and has a long slender esophageal region. The male is smaller than the female and has a curved tail. The reproductive organs of male and female are all double tubule.

* Egg: it is barrel or spindle in shape and 50 x 20µm in size. It is brownish and has a translucent polar plug at either ends. The content of the egg is an undeveloped cell


Life cycle

Female releases 1000 to 7000 unembryonated double-plugged eggs each day.Eggs are deposited onto warm, moist shady soil where they embryonate to the L1 stage.
The emrionate egg is the infective stage and is ingested. L1 hatch from the egg in the small intestine and burrow into the mucosa where they are. Adults migrate to the ileocecal and colon regions. Adult worm is inserted into the wall of the intestine penetrating through the mucosa and into the submucosa where blood is ingested.


Pathogenesis:

1.Light infection: Asymptomatic
2.Middle infection: Clinical manifestations are usually abdominal pain, anorexia, diarrhea, constipation .
3. Heavy infection: Bloody diarrhea, emaciation, prolapse of the anus may occur.

Diagnosis:

Discover the eggs in feces by saturated brine flotation method or direct fecal smear.
Treatment and prevention: Same as those of ascariasis

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article : Enterobius vermicularis (Pinworm)

The pinworms are one of the most common intestinal nematodes. The adult worms inhabit the cecum and colon. Right after mating, the male dies. Therefore, the male worms are rarely seen. The female worms migrate out the anus depositing eggs on the perianal skin. Humans get this infection by mouth and by autoinfection.


Morfology

*Adults: The adults look like a pin and are white in color. The female worm measures about 8 to 13 mm in size and is fusiform in shape. The male adult is only 2-5mm. The tail of a male is curved. They die right after mating, thus males are rarely seen. The anterior end tapers and is flanked on each side by cuticular extensions called “ cephalic alae”. The esophagus is slender, terminating in a prominent posterior bulb , which is called esophageal bulb. The cephalic alae and esophageal bulb are important in identification of the species.
*Egg: 50 to 60m by 25 µm, persimmon seed-like, colorless and transparent, thick and asymmetric shell, content is a larva.Anal smear showing large numbers of Enterobius eggs under the lower power. In the background are also two Ascaris eggs.


Life cycle

site of inhabitation: cecum and colon , infective stage: embryonated egg and infective route: by mouth, without intermediate host and reservoir host, life span of female adults: 1-2 months.


About one-third of pinworm-infected persons are asymptomatic, The adult worms may cause slight irritation of the intestinal mucosa.
Major symptom is anal pruritus, which associates with the nocturnal migration of the gravid females from the anus and deposition of eggs in the perianal folds of the skin. Restlessness, nervousness, and irritability, probably resulting from poor sleep associated with anal pruritus,. In young girls, migration of the worms may produce vaginitis and salpingitis or granuloma of the peritoneal cavity.


Diagnosis

Diagnosis depends on recovery of the characteristic eggs. The eggs and the female adults can be removed from the folds of the skin in the perianal regions by the use of the
cellophane tape method. The examination should be made in the morning, before the patient has washed or defecated.


Treatment & Prevention

Since the life span of the pinworm is less than two months, the major problem is reinfection.
Albendazole is the drug of choice. Repeated retreatment may be necessary for a radical cure.

Prevention:
1. treat the patients and carriers
2. individual health
3. public health
4. health education and hygienic habits
*

Epidemiology

Geographical distribution—cosmopolitan in temperate zones with about 30 to 50% of the population infected. It is more common in white than colored people and more prevalent in children than adults. Enterobiasis is most common where people live under crowded conditions such as orphanages, kindergartens, and large families.

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