Hershey Alfred and Martha Chase

Hershey Alfred and Martha Chase

Hershey Alfred Day (1908-1997)

Hershey Alfred Day was an American biologist. He shared a 1969 Nobel Prize for investigating the mechanism of viral infection in living cells. He was born in Owosso, Michigan, and received his B. S. in chemistry at Michigan State University in 1930 and his Ph. D. in bacteriology in 1934, taking a position shortly thereafter at the Department of Bacteriology at Washington University in St.Louis. He began performing experiments with bacteriophages[1] with Italian-American Salvador Luria and German Max Delbruck in1940, They organized a nonofficial “phage group” and observed that when two different strains of bacteriophage have infected the same bacteria, the two viruses may exchange genetic information. He moved to Cold Spring Harbor, New York in 1950 to join the Carnegie Institution of Washington’s Department of Genetics. He explores the construction of bacteriophages, the mechanism of their infecting the bacteria and soon he performed the famousblender experiment with Martha Chase in 1952. This experiment provided more evidence that DNA, not protein, was the genetic material.

Martha Cowles Chase (1927- 2003)

Martha Cowles Chase was born in Shaker Heights, Ohio. She was a young laboratory assistant in the early 1950s when she participated in one of the most famous experiments in 20th century biology. Devised by American bacteriophage expert Alfred Hershey at Cold Spring Harbor Laboratory in New York, the famous experiment demonstrated the genomic properties of DNA over proteins. By marking bacteriophages with radioactive isotopes, Hershey and Chase were able to trace protein and DNA to determine which is the molecule of heredity.

The brief description of their discovery

As by that time it was already known, that the elements, which are responsible for the physical properties of an organism are genes and that the genes are resided in chromosomes, so the problem was to find out which component of chromosomes are responsible or the containing of the heredity information. The chromosomes are consisted of a) nucleic acid DNA and b) of proteins, which are connected with the DNA. The bacteriophages, as all viruses, haven’t cellular construction unlike all the living organisms on the Earth. They consist simply of the nucleic acid (DNA or RNA) and protein, which cover it. If a bacteriophage infects the bacteria, then it first binds to the cell’s outer surface and then injects its hereditary information into the cell. There this information directs the production of thousands of new virus particles within the cell. The host bacterial cell eventually falls apart, releasing the newly made viruses. In 1952 Alfred Hershey and Martha Chase set out to identify the material injected into the bacterial cell at the start of an infection. They used a strain of bacteriophage known asT2, which contains DNA and designed an experiment to distinguish between the alternative hypotheses that the genetic material was DNA or that it was protein. They labeled the DNA of these T2 bacteriophages with a radioactive isotope of phosphorus, and, at the same time, labeled their protein coats radioactively with an isotope of sulfur,. Since the radioactive 32P and 35 S emit particles of very different energies when they decay, they are easily distinguished. The labeled viruses were permitted to infect bacteria. The bacterial cells were then agitated violently to shake the protein coats of the infecting viruses loose from the bacterial surfaces to which they were attached. Spinning the cells at high speed so that they were pulled from solution by the centrifugal forces, Hershey and Chase found, that the 35S label (and thus the virus protein) was now predominantly in solution with the dissociated virus particles, whereas the 32P label (and thus the DNA) had transferred to the interior of the cells. The viruses subsequently released from the infected bacteria contained the 32P label. So the hereditary information injected into the bacteria that specified the new generation of virus particles was DNA, not protein.

Hershey and Chase announced their results in a 1952 paper. The experiment inspired American researcher James D. Watson, who along with England's Francis Crick figured out the structure of DNA at the Cavendish Laboratory of the University of Cambridge the following year.

лñßÇ ²Éýñ»¹ ¨ سñó â»Ç½

²Èü𺸠кðÞÆ

(1908-1997)

²Ù»ñÇϳóÇ Ï»Ýë³µ³Ý, 1969Ã. Üáµ»ÉÛ³Ý Ùñó³Ý³ÏÇ ¹³÷Ý»ÏÇñ` µÅßÏáõÃÛ³Ý ¨ ýǽÇáÉá·Ç³ÛÇ µÝ³·³í³éáõÙ: ÌÝí»É ¿ 1908Ã.-ÇÝ ØÇãÇ·³Ý Ý³Ñ³Ý·Ç úíáëá ù³Õ³ùáõÙ: ²í³ñï»É ¿ ØÇãÇ·³ÝÇ ùáÉ»çÁ, ëï³ó»É µ³Ï³É³íñÇ ¨ Ù³·ÇëïñáëÇ ³ëïÇ׳ÝÝ»ñ: лﳷáõÙ ³ß˳ï»É ¿ ì³ßÇÝ·ïáÝÇ Ñ³Ù³Éë³ñ³ÝÇÝ ÏÇó µÅßÏ³Ï³Ý ÇÝëïÇïáõïÇ µ³Ïï»ñÇáÉá·Ç³ÛÇ µ³ÅÝáõÙ áñå»ë ¹³ë³Ëáë: àõëáõÙݳëÇñ»É ¿ µ³Ïï»ñÇáý³·»ñÇÝ, ÇÝãÁ µ»ñ»É ¿ Ýñ³Ý Ù»Í Ñ³çáÕáõÃÛáõÝÝ»ñÇ:

1969Ã-ÇÝ Ð»ñßÇÝ ÙÇ ËáõÙµ ³ÛÉ ·ÇïݳϳÝÝ»ñÇ Ñ»ï Ù»Ïï»Õ ¹³ñÓ³í µÅßÏáõÃÛ³Ý ¨ ýǽÇáÉá·Ç³ÛÇ Üáµ»ÉÛ³Ý Ùñó³Ý³Ï³ÏÇñ. §íÇñáõëÝ»ñÇ ·»Ý»ïÇÏ³Ï³Ý Ï³éáõóí³ÍùÇ ¨ í»ñ³ñï³¹ñÙ³Ý Ù»Ë³ÝǽÙÝ»ñÇÝ í»ñ³µ»ñíáÕ Ñ³Ûï³Ý³·áñÍáõÃÛáõÝÝ»ñÇ Ñ³Ù³ñ¦:

زð² âºÆ¼

(1927-2003)

ÌÝí»É ¿ úѳÛá Ý³Ñ³Ý·Ç Þ»Çù»ñ лÇÃë ù³Õ³ùáõÙ: ܳ ¹»é¨ë »ñǹ³ï³ñ¹ ɳµáñ³Ýï ¿ñ, »ñµ 1950 Ã-Ç ëϽµÇÝ ³ñ¹»Ý Ù³ëݳÏó»ó 20-ñ¹ ¹³ñÇ Ï»Ýë³µ³ÝáõÃÛ³Ý ³Ù»Ý³Ñ³ÛïÝÇ ÷áñÓ»ñÇó Ù»ÏÇÝ: ²Û¹ ÷áñÓÁ ³ÛÅÙ ÏñáõÙ ¿ лñßÇ – â»Ç½Ç ÷áñÓ ³Ýí³ÝáõÙÁ:

¸ñ³Ýó ϳï³ñ³Í ÷áñÓÇ Ñ³Ù³éáï Ýϳñ³·ñáõÃÛáõÝÁ

ºñµ µ³Ïï»ñÇáý³·Á Ý»ñËáõÅáõÙ ¿ µ³Ïï»ñdzÛÇ µççÇ Ù»ç, ³å³ ݳ.

³/ ϳñáÕ ¿ ÇÝùÁ ù³Ûù³Ûí»É µççÇ ý»ñÙ»ÝïÝ»ñÇ ³¹»óáõÃÛ³Ý ï³Ï,

µ/ µçÇçÁ ϳñáÕ ¿ ù³Ûù³Ûí»É,

·/ ϳñáÕ ¿ Ý»ñÙáõÍí»É µ³Ïï»ñdzÛÇ Å³é³Ý·³Ï³ÝáõÃÛáõÝÝ ³å³ÑáíáÕ Ñ³Ù³Ï³ñùÇ Ù»ç ¨ Ýáñ áõÕáõÃÛáõÝ Ïï³ µ³Ïï»ñdzÛÇ µççÇÝ ëï»ÕÍ»Éáõ ѳ½³ñ³íáñ Ýáñ µ³Ïï»ñÇáý³·»ñÇ:

ÆÝãå»ë µáÉáñ íÇñáõëÝ»ñÁ, µ³Ïï»ñÇáý³·»ñÁ ãáõÝ»Ý µçç³ÛÇÝ Ï³éáõóí³Íù áõ ϳ½Ùí³Í »Ý ÝáõÏÉ»ÛݳÃÃíÇó ¨ Ýñ³Ý ³ñï³ùÇÝÇó å³ïáÕ ëåÇï³Ïáõó³ÛÇÝ Ã³Õ³ÝÃÇó:

ø³ÝÇ áñ 20-ñ¹ ¹³ñÇ Ï»ë»ñÇÝ ³ñ¹»Ý ѳÛïÝÇ ¿ñ, áñ ûñ·³ÝǽÙÇ ýǽÇÏ³Ï³Ý Ñ³ïϳÝÇßÝ»ñÇ Ñ³Ù³ñ å³ï³ë˳ݳïáõ »Ý ·»Ý»ñÁ¨ áñ ¹ñ³Ýù ·ïÝíáõÙ »Ý µççÇ ÏáñǽáõÙ ï»Õ³Ï³Ûí³Í ùñáÙáëáÙÝ»ñáõÙ, áñáÝù ¿É Çñ»Ýó Ñ»ñÃÇÝ Ï³½Ùí³Í »Ý ëåÇï³ÏáõóÝ»ñÇó áõ ÝáõÏÉ»ÛݳÃÃáõÝ»ñÇó: гÛïÝÇ ¿ñ ݳ¨ »ñÏáõ ïÇåÇ ÝáõÏÉ»ÇݳÃÃáõ` ¸Ü ¨ èÜÂ:

1943 Ã-ÇÝ Ð»ñßÇÝ ¨ ÙÇ ËáõÙµ ³ÛÉ ·ÇïݳϳÝÝ»ñ ϳ½Ù»óÇÝ ÙÇ áã å³ßïáÝ³Ï³Ý ·Çï³Ñ»ï³½áï³Ï³Ý ËáõÙµ, áñÝ áõëáõÙݳëÇñáõÙ ¿ñ 7 µ³Ïï»ñáý³·»ñÇ, áñáÝù í³ñ³ÏáõÙ ¿ÇÝ ³ÕÇù³ÛÇÝ óáõåÇÏÇÝ:

1946Ã-ÇÝ Ð»ñßÇÝ ÷áñÓݳϳÝáñ»Ý ³å³óáõóáõÙ ¿ íÇñáõëÝ»ñÇ ·»Ý»ñÇ ÷á˳ϻñåáõÙÁ, ÇëÏ ¨ë »ñÏáõ ï³ñÇ ³Ýó ݳ áã ÙdzÛÝ Ï³ñáÕ³ÝáõÙ ¿ Ýϳñ³·ñ»É µ³Ïï»ñÇáý³·»ñÇ Ï³éáõóí³ÍùÁ, ³ÛÉ Ý³¨ µ³ó³ïñ»ó, û ÇÝãå»ë »Ý ¹ñ³Ýù í³ñ³ÏáõÙ µçÇçÝ»ñÁ:

Üñ³ Ùß³Ï³Í Ù»Ãá¹Á Ñ»ï¨Û³ÉÝ ¿ñ. áñå»ë½Ç ï»ëÝ»ñ ³ñ¹Ûáù ÝáõÏÉǻݳÃÃáõÝ Ã» ëåÇï³ÏáõóÝ ¿ Çñ»Ýó ·»Ý Ý»ñϳ۳óÝáõÙ, ݳ ëï³ó³í ³ÛÝåÇëÇ ý³·»ñÇ ÝÙáõßÝ»ñ, áñáÝó ÙÇ Ù³ëÇ ëåÇï³Ïáõó³ÛÇÝ Ã³Õ³ÝÃÇ Ï³½ÙÇ Ù»ç Ý»ñÙáõÍí³Í ¿ñ é³¹Çá³ÏïÇí ÍÍáõÙµ`35 S, ÇëÏ Ù³ëÇ Ùáï ¸ÜÂ-Ç ÙáÉáÏáõÉÇ Ù»ç Ý»ñÙáõÍí³Í ¿ñ é³¹Çá³ÏïÇí ýáëýáñ` 32P (ëåÇï³ÏáõóáõÙ ãϳ ýáëýáñ, ÇëÏÝ ³ÙÇݳÃÃíáõÙ` ÍÍáõÙµ): ÂáõÛÉ ï³Éáí, áñ ³Û¹ µ³Ïï»ñÇáý³·»ñÁ í³ñ³Ï»Ý ³ÕÇù³ÛÇÝ óáõåÇÏÇ µçÇçÝ»ñÇÝ, ݳ é³¹Çá³ÏïÇí ǽáïáåÝ»ñÇÝ Ñ»ï¨»Éáõ ÙÇçáóáíå³ñ½»ó, áñ ý³·»ñÁ ³Ùñ³ÝáõÙ »Ý µ³Ïï»ñdzÛÇ Ù»Ùµñ³ÝÇÝ ëåÇï³Ïáõó³ÛÇÝ Çñ»Ýó åáãÇÏáí, ÇëÏ ÝáõÏÉ»ÇݳÃÃáõÝ, áñÁ ·ïÝíáõÙ ¿ñ ëåÇï³Ïáõó³ÛÇÝ Ã³Õ³ÝÃÇ ï³Ï, ³ÝóÝáõÙ ¿ µ³Ïï»ñdzÛÇ Ý»ñëÁ:

лñßÇÝ ¨ â»Ç½Á ³ñӳݳ·ñ»óÇÝ Çñ»Ýó ëï³ó³Í ³ñ¹ÛáõÝùÝ»ñÇ Ù³ëÇÝ 1952 Ãí³Ï³ÝÇÝ: ²Ûë ÷áñÓÁ á·¨áñ»ó ³Ù»ñÇϳóÇ Ñ»ï³½áïáÕ æ»ÛÙë àõáÃëáÝÇÝ, áñÁ µñÇï³Ý³óÇ ·ÇïÝ³Ï³Ý üñ»ÝëÇë øñÇÏÇ Ñ»ï ÙdzëÇÝ µ³ó³Ñ³Ûï»ó ¸ÜÂ-Ç Ï³éáõóí³ÍùÁ` ³ñ¹»Ý ¹ñ³ ѳçáñ¹ ï³ñí³ Ù»ç:

1

[1] Bacteriophages are kind of viruses, which infect bacteria