Toll-like receptors

Bacteria

large group of unicellular, prokaryotes, bacteria.

The bacteria are usually more

, micrometers in length and have a wide range of forms from areas

rods and spirals (,

). Bacteria are widely distributed in each habitat

on earth, growing in soil, acidic hot

sources, radioactive waste, water and deep in the

crust, as well as organic matter and

, living bodies of plants and animals. There

usually 40000000 bacterial cells in one gram of soil and

million bacterial cells in a milliliter

Freshwater, everyone has

about five nonillion (5 ‡ 10

) >> << bacteria on Earth, forming much of the biomass >> worlds. Figure 1 <<. Bacteria are in many cellular forms. Figure 2. Most bacteria have a diameter in the range of 1

ET (micrometer) to 5 them. Left to right:

spherical (cocci), bacteria, bacillary (bacilli)

bacteria spiral bacteria. Bacteria are vital nutrients

processing, many steps in nutrient cycles

depending on these organisms, such as

fixing nitrogen from the atmosphere and

decay. However, most bacteria do not

characterized, and only about half

types of bacteria have species that can be grown in the lab

. The study of bacteria

known as bacteriology, microbiology department. There are about ten times more >> << bacterial cells in the human flora

bacteria as human cells in the body >> <<, with lots of bacteria on the skin and how to >> << intestinal flora. The vast majority of bacteria in the body

disposed protective effect on the immune system, and

little helpful. Bacteria

be profiled in this section are those

pathogenic to humans, causing infections

(

). Figure 3. Areas of the body that are prone

different types of bacteria. Click to enlarge. Gram-negative bacteria have relatively

thin cell wall consisting of several layers of peptidoglycan surrounded by

second lipid membrane containing strattera 25mg lipopolysaccharides and lipoproteins

(). These bacteria not

retain crystal violet dye in the Gram staining protocol

because of their lipopolysaccharides outer layer >>. In grams << test

contrasting color (usually safranina) is added after the crystal violet color

all gram-negative bacteria with

, red or pink. On the other hand,

positive bacteria retain the crystal violet dye

when washing in bleaching solutions >> << because they have no external >> << membranes, but rather they have thickened

peptidoglycan layer. illustrates the difference

to antigens associated with two

different types of bacteria. Figure 4. The outer surface of Gram-negative bacteria: Note

LPS in the outer membrane. Figure 5. Antigens involved in

host response to bacteria: Gram-positive and

gram-negative bacteria. Click to enlarge. Pathogenic features

Gram-negative bacteria often associated with some components

Gram-negative cell wall,

including lipopolysaccharides (also known as

LPS or endotoxin) layer (

). People

LPS can induce both innate and adaptive immune

,

response characterized by cytokine production and immune system

activation. For example, LPS can cause a cascade

supplement, which is part of the innate immune response

and bind to Toll-like receptors

(TLR-4) on B-lymphocytes to cause

adaptive, humoral response without

T-helper cells, thus, LPS is known as

T-independent antigens. Inflammation is a common result >> << cytokine production, which can also produce

host toxicity. Protection against gram-negative bacterial

infection: antibodies produced by B-lymphocytes, such as

immunoglobulin M (IgM) are effective against bacterial

extracellular pathogens. Antibodies

can protect against gram-negative bacteria

accession to the surface and activation of complement. Activated complement cascade induces the formation

in the membrane attack complex (MAC), which produces holes or pores in >> << outer membrane. Antibodies attached to >> << bacteria can also join such as phagocytes >> << macrophages through Fc receptors of phagocytes

process called

- opsonizatsiyi (

). It promotes phagocytosis

and bacterial removal. In addition, amendments related

bacteria can attach to phagocytes via complement receptors

(CR), which promotes phagocytosis

(

). Figure 6. Examples of antibody-mediated mechanisms against gram-negative bacterial

infection. A. Cytoplasmic membrane

2. A thin layer of peptidoglycan

(which is much thinner than that of gram-positive bacteria

)

3. Outer membrane containing lipopolysaccharides

(LPS consisting of lipid

main polysaccharides, as well as the antigen) outside the peptidoglycan layer

,

4. Porins exist in the external >> << membranes that act as pores for particular molecules

5. There is space between the

layers of peptidoglycan and secondary >> << cell membrane called Peryplazma

6. S-layer directly

attached to the outer membrane, not peptidoglycan

7. If present, flagella in

four supporting rings instead of two

8. No teyhoevye acid or acids lipoteyhoevaya

There are 9. Lipoproteins are added

on the polysaccharide backbone. 10. Most do not sporuliruyut

In general, cell wall

Gram-negative microorganisms are much more complex than

cell wall of gram-positive bacteria. From outside the membrane, it is

the following:

peptidoglycan layer two

nm in thickness, forming 5% of the cell wall

mass, often associated with outside

designing molecules lipoproteins

outer membrane consisting of a lipid bilayer, similar to >> << some respects to the membrane that

contains protein molecules and (on its inner aspect

) lipoproteins related

peptidoglycan. Other proteins form

transmembrane water-filled channels called

porynov by which hydrophilic antibiotics >> << are free to move. Complex polysaccharides

forming the outer surface of the major components >>. They differ << strains of bacteria and

main determinants of antigenicity. Complex polysaccharides >>

<< a source of endotoxin, which in vivo, trigger different

aspects of inflammatory response by activating complement

causing fever. Gram-negative bacillus E. coli E. coli E. coli Gram-negative cocci Neisseria g onorr hoeae.

,