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Cathelicidins, a group of peptides having 100 amino acid domains that is habitually proteolytically divided from the exceedingly variable C-terminal antimicrobial domain. In phagocytes, the cathelicidins are usually put away as latent antecedents in secretory granules. Much of the time, the preparing protein is neutrophil elastase contained in a different arrangement of capacity granules. Amid phagocytosis, this twofold framework consolidates to create dynamic antimicrobial peptides. A wealth of evidence exists to suggest cathelicidin's crucial role as an antimicrobial in the protection of epithelial surfaces, particularly the skin. The clinical significance of cathelicidins antimicrobial activity can be seen in patients with Kostmann's syndrome, a rare genetic condition resulting in severe neutropenia. Cathelicidins are precursors of many novel peptides. Cathelicidin-derived antimicrobial peptides range in length from 12 to about 100 residues, and include α-helical peptides, e.g. human LL-37/hCAP18 and pig PMAP-37 ; linear peptides with one or two predominant amino acids, e.g. the bovine Pro- and Arg-rich Bac5 and Bac7  and the Trp-rich indolicidin ; and peptides with one or two disulfide bonds, e.g. bovine cyclic dodecapeptide  and pig protegrins The general lead of the component activating Cathelicidin activity, similar to that of other antimicrobial peptides, includes the breaking down (harming and puncturing) of cell layers of creatures toward which the peptide is dynamic. Cathelicidins don't follow up on solid host cell layer. Collaboration of cationic peptides and contrarily charged lipid films of microorganisms empower their precise, parallel bond and mooring, and killing the layer charge. Changing of the auxiliary and tertiary structure of the peptide changes its opposite introduction, in this way inserting in the lipid bilayer and making transmembrane pores. In its activity against Gram– negative microscopic organisms, the peptide can move over the external film, and in the wake of passing the layer of peptidoglycan, crosses the inward film into the cytoplasm of the bacterial cell. Cathelicidin has also proven to be effective against viral infections including herpes simplex virus, vaccinia virus, and fungal infections.
Defensins are small cysteinerich cationic proteins found in both vertebrates and invertebrates. They have also been reported in plants.  Also they are assorted individuals from a substantial group of cationic host Defense peptides (HDP), generally dispersed all through the plant and creature kingdoms. Defensins and Defensin-like peptides are practically different, disturbing microbial layers and going about as ligands for cellular recognition and signaling. They function as, host defense peptides. They are active against bacteria, fungi and many enveloped and non-enveloped viruses. They consist of 18-45 amino acids including six (in vertebrates) to eight conserved cysteine residues. These (Defensin) are especially plentiful and generally dispersed antimicrobial peptides described by a cationic β-sheet rich amphipathic structure balanced out by a preserved three-disulfide motif. They extend in measure from 29 to 47 amino acids, and are bottomless in numerous vertebrate granulocytes, Paneth cells (specific granule-rich intestinal host guard cells), and on epithelial surfaces. Like the more straightforward magainins and protegrins, defensins likewise shape pores in target films. There is confirming that the permeabilization of target cells is nonlethal unless taken after by Defensin passage into the cell and extra intracellular harm. AMP productions might be both constitutive and inducible. Defensin biosynthesis is specially activated by atomic structures related with pathogens of irresistible operators and furthermore by cytokines. Animals and human alpha and beta defensins separated in 1980th are additionally subdivided into various subtypes. There are numerous subtypes of alpha and beta defensins (e.g., αdef1; αdef3; αdef4; αdef6; βdef1; βdef2; βdef4, and so forth.); in multicellular living beings they assume comparable anti-infection parts against microorganisms, organisms, and even some infections The tadefensins (Θ) have been as of late found in a few individuals from the set of all animals. These antibacterial peptides go about as commit porins on the bacterial cell divider. Not at all like the insects and mammalian defensins, are which for the most part dynamic against bacteria. Plant defensins, with a couple of exemptions, don't have antibacterial movement. Most plant defensins are engaged with resistance against an expansive scope of organisms.  They are not just dynamic against phytopathogenic growths, (for example, Fusarium culmorum and Botrytis cinerea), yet additionally against cook's yeast and human pathogenic organisms, (for example, Candida albicans. Plant defensins have likewise been appeared to hinder the development of roots and root hairs in Arabidopsis thaliana and change development of different tomato organs which can expect numerous capacities identified with safeguard and advancement. 
Researchers from The Rockefeller University have discovered a new class of antibiotics capable of killing off several antibiotic-resistant pathogens. This new family comes from molecules present in a large variety of soils and researchers hope it could be a useful weapon in our medical arsenal.
As reported in Nature Microbiology, the antibiotic compounds are a special class of peptides – special chains of amino acids – which require calcium for antibacterial activity. Calcium-dependent antibiotics are capable of targeting bacteria in a variety of ways and this characteristic makes them particularly effective. They can target the formation of the bacterial cell membrane or even destroy the cell wall.
The team looked for new members of this antibiotic family and tested them against known pathogens. The new antibiotics, called malacidins, were successful in sterilizing methicillin-resistant Staphylococcus aureus, also known as the superbug MRSA, and the bacteria attacked with the malacidins did not develop resistance.

The new family of antibiotics comes from molecules present in large variety of soils. Scientists had analysed more than 1000 unique soil samples across US to better understand how new class of antibiotics is produced and how it can be exploited for fighting bacteria. They had used DNA information that encodes production of antibiotic in daptomycin to study it. This discovery could be a useful weapon in field of medicines.

Significance

Malacidins are distinctive class of antibiotics that are commonly encoded in soil microbiomes. They have never been reported in culture-based NP (Natural Products) discovery efforts.
Malacidins are active against multidrug-resistant pathogens, sterilise methicillin-resistant Staphylococcus aureus  (MRSA) skin infections in animal wound model and did not select for resistance in laboratory conditions.
The malacidins was tested on rats with MRSA skin infections. The condition was cured, and even after 20 days of continued contact with malacidins, the rodents did not experience any side effects.

Concern

Malacidins only target gram-positive bacteria with a very thick cell wall. It is ineffective against gram-negative bacteria which cause cholera, pneumonia, sexually transmitted diseases, and plague. Thus, it does not make it universal cure against all bacteria.

 • We eat about 500kg of food per year.
1.7 liters of saliva is produced each day.
The esophagus is approximately 25cm long.
Muscles contract in waves to move the food down the esophagus. This means that food would get to a person's stomach, even if they were standing on their head.
An adult's stomach can hold approximately 1.5 liters of material.
Every day 11.5 liters of digested food, liquids and digestive juices flow through the digestive system, but only 100 mls is lost in feces.
In the mouth, food is either cooled or warmed to a more suitable temperature.
Our digestive system has its own little mini-brain.                       
     The functioning of the digestive system is regulated by the enteric nervous system (ENS), which is made up of a tremendous amount of nerve cells and is regulated by the same neurotransmitters, most notably serotonin, found in the brain. This similarity has earned the ENS the title of the "Second Brain".our brain and digestive system work in close partnership, a phenomenon that we have first-hand knowledge of any time our stomach flips when we think of something anxiety-provoking — or more dramatically if we experience diarrhea when we are stressed. This collaboration is thought to be essential to our survival as a species; although digestion is essential for life, dealing with threats is just as necessary. The body developed the "flight or fight" system to divert resources away from the digestive system to the systems of the body needed to fight off or run away from things that might do us harm. Dysfunction in the brain-gut connection has been theorized to play a role in the development of functional gastrointestinal disorders (FGDs).

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