Recombinant Bovine Somatotropin

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Recombinant Bovine Somatotropin

• Team 11
• Amanda, Chantal, Ben, Kyle, Lisa, and Christina

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What is bST?

• Bovine Somatotropin is a naturally occurring
  peptide hormone
• Produced by the pituitary gland in cattle
• Promotes growth in calves and milk production in
  lactating cows
• Furthering cow development, Recombinant Bovine
  Somatotropin (rbST) was synthetically reproduced
  to increase milk production in dairy cows

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bST vs. rbST

• bST
• Four types produced by the pituitary gland
• Between 190-191 amino acids long
• Difference of only one or two amino acids

• rbST
• Synthetically produced by bacteria NOT IN THE
  PITUITARY GLAND
• Same sequence except for the terminal amino acid
• Met -gt Ala

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How rbST is produced

• Cow somatotropin gene is spliced into the plasmid
  of the E.coli K-12 bacterium
• Bacteria are incubated
• E.coli are ruptured and separated to purify rbST
• Made into a slow- release, injectable form to be
  delivered to the cow

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rbST Generation
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Physiology

• The bST and rbST trigger the production of
  Insulin- Like Growth Factor 1 in the liver and
  stimulate prolactin and placental lactogen
  hormones in mammary tissue to produce milk
• Follows a similar process to the insulin receptor
  cascade
• Promotes cell growth and multiplication

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IGF 1 Cascade
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rbST In Vivo

• Increases propionate and glucose
• Reduced lipogenesis
• Does not change the bST levels found in the milk
  by any measurable amount
• Increases milk produced by one cow by 10- 40 on
  average per milking 8- 12 lbs per cow, per day

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Posilac

• Created by pharmaceutical company Monsanto
• Only FDA approved means to increase milk
  production in cows
• Administered by means of intramuscular injections
• 9 million dairy cows- one third nation wide are
  supplemented with Posilac

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Controversies and Hearsay

• rbST is said to increase mastitis, infertility
  and lameness in cows
• In humans, IGF-1 can cause cancer, diabetes, and
  hypertension
• Causes severe economic problems among small dairy
  communities due to overabundance of milk
  available

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rbST Reality Check

• 25 increased risk of mastitis 18 infertility
  50 lameness/ lethargy
• Mastitis infected milk cannot and should not be
  sold, because its gross. p
• bST is species limited and WILL NOT bind to human
  cell receptors
• IGF-1 has been associated with an increased risk
  of cancer- still being studied
• No increase of bST found in milk since it is
  broken down by protein digestion

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However

• Canadas health administration has not yet
  approved the use of Posilac
• European Union declared the use of rbST as safe,
  but a moratorium was placed on its sale by 25
  nations within Europe
• Japan, Australia and New Zealand have banned the
  use and sale of Posilac

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Summary

• rbST is a nearly identical synthetic form of bST
• Used to increase growth and milk production in
  cows
• However controversial, most is grounded in very
  little to no fact
• Mitochondrial inner membranes are very
  impermeable !

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References

• Mills, Lisa. Science and Social Context. London
  McGill- Queens University Press, 2002.
• http//www.monsantodairy.com/
• www.monsantodairy.com/about/history/index.html
• Blundell, T.L. et al. Insulin- like growth
  factor A model for tertiary structure
  accounting for immunoreactivity and receptor
  binding. Proc. Natl. Acad. Sci. Vol. 75 (1978)
  180-184.
• Larsen, Hans. Milk and the Cancer Connection.
  Iternational Health News. 76 (1998).
• www.wikipedia.org/wiki/Bovine_Somatotropin
• http//www.pubmedcentral.nih.gov/articlerender.fcg
  i?artid280709
• http//www.hc-sc.gc.ca/dhp-mps/vet/issues-enjeux/r
  bst-stbr/index_e.html
• http//www.rbstfacts.org/

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Any Udder Questions?

• Q. Where do Russians get their milk?
• A. From Mos-cows! ?

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How this topic relates to class

• bST is a protein hormone
• Uses endocrine, perocrine, and autocrine
  signaling
• Amino acid sequencing
• Plasma membrane receptors
• As it turns out, the inner mitochondrial membrane
  is very impermeable! to these growth hormones