Killer factor

Many foods such as alcohoHc beverages, pickles, cheese, and fish sauce are preserved by fermentation. Spontaneous fermentations by mixed populations of yeasts and bacteria are normally iavolved. Preservation results from a lowering of pH or the formation of ethanol. Yeasts do not produce antibiotics, although isolates of a number of species produce a toxia ("killer factor") lethal to other yeasts. 

Similar techniques were used by Shinohara et al (71) to develop hybrids with increased production of fusel alcohols and esters. Protoplast fusion techniques have been used to confer amylolytic activity to brewery yeasts (22) and ethanol tolerance to wine yeasts (70) Farris et al (72) used protoplast fusion to produce hybrids with killer factor that is, the ability to secrete proteinic toxins. Kunkee and coworkers (25) utilized a leucine auxotrophic mutant strain of S. cerevisiae (UCD Montrachet 522) to produce base wine for brandy production the mutant strain produces less isoamyl alcohol, reducing the quantity of fusel alcohols in the subsequent brandy. And Thornton (48) discussed the progress in utilizing plasmid vectors to introduce new genes into wine yeasts he cautioned, however, that until the yeast genome is better understood that direct gene manipulation techniques will be of limited value. 

Resistance to contamination Acquisition of killer phenotype Transfer of killer factor via rare mating Young (1981)... 

Young, T. W. (1981). The genetic manipulation of killer factor into brewing yeast. Journal of the Institute of Brewing, 87, 292-295. 

This phenomenon, the killer factor, was discovered in S. cerevisiae but killer strains also exist in other yeast genera such as Hansemla, Candida, Kloeckem, Hanseniaspora, Pichia, Tom-lopsis, Kluyveromyces and Debaryomyces. Killer yeasts have been classified into 11 groups according to the sensitivity reaction between strains as well as the nature and properties of the toxins involved. The killer factor is a cellular interaction model mediated by the proteinic toxin excreted. It has given rise to much fundamental research (Tipper and Bostian, 1984 Young, 1987). Barre (1984, 1992), Radler (1988) and Van Vuuren and... 

The determinants of the killer factor are both cytoplasmic and nuclear. In S. cerevisiae, the killer phenomenon is associated with the presence of double-stranded RNA particles, virus-Uke particles (VLP), in the cytoplasm. They are in the same category as non-infectious mycovirus. There are two kinds of VLP M and L. The M genome (1.3-1.9 kb) codes for the K toxin and for the immunity factor (R). The L genome (4.5 kb) codes for an RNA polymerase and the proteinic capsid that encapsulates the two genomes. Killer strains (K+R+) secrete the toxin and are immune to it. The sensitive cells (K R ) do not possess M VLP but most of them have L VLP. The two types of viral particles are necessary for the yeast cell to express the killer phenotype (K+R+), since the L mycovirus is necessary for the maintenance of the M type. 

Barre P. (1978) Killer factor activity under vinification conditions. Vth International Symposium on Yeasts, Montpellier. 

Woods, D.R. E.A. Bevan. 1968. Studies on the nature of the killer factor produced by Saccharomyces cerevisiae. Heredity 21 121-130. 

Eukaryotic cells carry genetic information not only in the nucleus but also in organelles, such as mitochondria in yeast. In addition to that, there are cytoplasmic genetic factors known which cannot be associated with cell organelles, such as the killer factor and the factor. 

A great number of various substituted aminophenyl derivatives of thiazolium, and their organic or metallic complexes, have been patented as weed-killers or regulating growth factors of plants (135-138). 

Ah = Antibody IL = interleukin TNF =tumornecrosis factor INF = interferon LAK =lymphocyte-activated killer CSF =colony stimulating factors and FGF = fibroblast growth factor. 

COPD is a chronic inflammatory disease that results from prolonged and repeated inhalation of particles and gases, chronic (or latent) infection or an interaction of these factors. In many cases, the inflammation persists even when the exposure (in most cases smoking) is stopped. Prominent among the infiltrating leukocytes are neutrophils, CD8+ lymphocytes (Co-receptor for the T-cell receptor. CD8+ is specific for the class IMHC protein. It is expressed on the surface of cytotoxic T-cells and natural killer cells.) and CD68+ monocytic cells (A lysosomal antigen. All cells that rich in... 

Takeda, K. et al., Involvement of tumor necrosis factor-related apoptosis-inducing ligand in surveillance of tumor metastasis by liver natural killer cells, Nat. Med., 7, 94, 2001. 

T cells are lymphocytes produced by the thymus gland. There are two types of T cells involved in immune response CD4+ (CD positive, helper cells) and CD8 (CD positive, also called T killer, or suppressor, cells). When the APCs present the antigens to CD4+ helper T cells, the secretory function is activated and growth factors such as cytokines are secreted to signal the proliferation of CD8" killer cells and B cells. When the CD8" ... 

Aste-Amezaga M, D Andrea A, Kubin M, Trinchieri G Cooperation of natural killer cell stimulatory factor/ interleukin-12 with other stimuli in the induction of cytokines and cytotoxic cell-associated molecules in human T and NK cells. Cell Immunol 1994 156 480-492. 

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