scholarly journals Defective Interference in the Killer System of Saccharomyces cerevisiae

1983 ◽  
Vol 45 (2) ◽  
pp. 800-812 ◽  
Author(s):  
Susan Porter Ridley ◽  
Reed B. Wickner
1990 ◽  
Vol 10 (9) ◽  
pp. 4807-4815 ◽  
Author(s):  
M J Schmitt ◽  
D J Tipper

The double-stranded RNA (dsRNA) viruses of Saccharomyces cerevisiae consist of 4.5-kilobase-pair (kb) L species and 1.7- to 2.1-kb M species, both found in cytoplasmic viruslike particles (VLPs). The L species encode their own capsid protein, and one (LA) has been shown to encode a putative capsid-polymerase fusion protein (cap-pol) that presumably provides VLPs with their transcriptase and replicase functions. The M1 and M2 dsRNAs encode the K1 and K2 toxins and specific immunity mechanisms. Maintenance of M1 and M2 is dependent on the presence of LA, which provides capsid and cap-pol for M dsRNA maintenance. Although a number of different S. cerevisiae killers have been described, only K1 and K2 have been studied in any detail. Their secreted polypeptide toxins disrupt cytoplasmic membrane functions in sensitive yeast cells. K28, named for the wine S. cerevisiae strain 28, appears to be unique; its toxin is unusually stable and disrupts DNA synthesis in sensitive cells. We have now demonstrated that 4.5-kb L28 and 2.1-kb M28 dsRNAs can be isolated from strain 28 in typical VLPs, that these VLPs are sufficient to confer K28 toxin and immunity phenotypes on transfected spheroplasts, and that the immunity of the transfectants is distinct from that of either M1 or M2. In vitro transcripts from the M28 VLPs show no cross-hybridization to denatured M1 or M2 dsRNAs, while L28 is an LA species competent for maintenance of M1. K28, encoded by M28, is thus the third unique killer system in S. cerevisiae to be clearly defined. It is now amenable to genetic analysis in standard laboratory strains.


2007 ◽  
Vol 73 (13) ◽  
pp. 4373-4378 ◽  
Author(s):  
John P. Paluszynski ◽  
Roland Klassen ◽  
Friedhelm Meinhardt

ABSTRACT The gene responsible for self-protection in the Pichia acaciae killer plasmid system was identified by heterologous expression in Saccharomyces cerevisiae. Resistance profiling and conditional toxin/immunity coexpression analysis revealed dose-independent protection by pPac1-2 ORF4 and intracellular interference with toxin function, suggesting toxin reinternalization in immune killer cells.


1990 ◽  
Vol 10 (9) ◽  
pp. 4807-4815
Author(s):  
M J Schmitt ◽  
D J Tipper

The double-stranded RNA (dsRNA) viruses of Saccharomyces cerevisiae consist of 4.5-kilobase-pair (kb) L species and 1.7- to 2.1-kb M species, both found in cytoplasmic viruslike particles (VLPs). The L species encode their own capsid protein, and one (LA) has been shown to encode a putative capsid-polymerase fusion protein (cap-pol) that presumably provides VLPs with their transcriptase and replicase functions. The M1 and M2 dsRNAs encode the K1 and K2 toxins and specific immunity mechanisms. Maintenance of M1 and M2 is dependent on the presence of LA, which provides capsid and cap-pol for M dsRNA maintenance. Although a number of different S. cerevisiae killers have been described, only K1 and K2 have been studied in any detail. Their secreted polypeptide toxins disrupt cytoplasmic membrane functions in sensitive yeast cells. K28, named for the wine S. cerevisiae strain 28, appears to be unique; its toxin is unusually stable and disrupts DNA synthesis in sensitive cells. We have now demonstrated that 4.5-kb L28 and 2.1-kb M28 dsRNAs can be isolated from strain 28 in typical VLPs, that these VLPs are sufficient to confer K28 toxin and immunity phenotypes on transfected spheroplasts, and that the immunity of the transfectants is distinct from that of either M1 or M2. In vitro transcripts from the M28 VLPs show no cross-hybridization to denatured M1 or M2 dsRNAs, while L28 is an LA species competent for maintenance of M1. K28, encoded by M28, is thus the third unique killer system in S. cerevisiae to be clearly defined. It is now amenable to genetic analysis in standard laboratory strains.


2001 ◽  
Vol 36 (2) ◽  
pp. 196-201 ◽  
Author(s):  
F. Seibold ◽  
O. Stich ◽  
R. Hufnagl ◽  
S. Kamil ◽  
M. Scheurlen

2007 ◽  
Vol 45 (08) ◽  
Author(s):  
S Schmechel ◽  
V Schachinger ◽  
F Seibold ◽  
C Tillack ◽  
T Ochsenkühn ◽  
...  

ОВЧИННИКОВ А.А., ОВЧИННИКОВА Л.Ю., КОНОВАЛОВ Д.А. Южно-Уральский государственный аграрный университет Аннотация: В опыте были изучены титры антител против основных инфекционных заболеваний птицы (инфекционный бронхит кур ИБК, болезнь Гамборо, ньюкаслская болезнь) в крови у мясных кур кросса ISA Hubbard F-15, получавших пробиотические кормовые добавки на основе Saccharomyces cerevisiae или Васillus subtilis в количестве 0,50 кг/т комбикорма. Исследования показали, что цыплята суточного возраста уже имеют врожденный иммунитет к широко распространенным инфекционным заболеваниям птицы; титры антител к ИБК и болезни Гамборо до 59-суточного возраста имели тенденцию к снижению, затем повышались и достигали максимума к 151-суточному возрасту, затем плавно снижались. У птицы, получавшей добавки пробиотиков, титр антител к ИБК за продуктивный цикл был выше на 11,2-46,1%, к болезни Гамборо - на 7,2-26,8%, ньюкаслской болезни - на 14,4-27,9% по сравнению с контрольной группой. Установлено также, что периодическое применение пробиотиков в первые 45 сут. выращивания ремонтного молодняка, в периоды разноса кур, пика продуктивности и снижения яйцекладки повышает сохранность поголовья на 0,4-8,2%. Ключевые слова: МЯСНЫЕ КУРЫ, РЕМОНТНЫЙ МОЛОДНЯК, ПРОДУКТИВНЫЙ ПЕРИОД, КОРМОВАЯ ДОБАВКА, ПРОБИОТИКИ, СОХРАННОСТЬ, ТИТРЫ АНТИТЕЛ,


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