Selective Breeding and Transgenic Animals

Selective Breeding and Transgenic Animals

• Animal breeders have long sought to improve traits like growth, milk yield, and feeding efficiency in farm animals.
• Phenotypic selective breeding, enhancing superior genetic traits, increased domestic animal productivity.
• Before molecular genetics, genetic regulation & function were observed through inherited characteristics or spontaneous mutations.
• Selective breeding was a pre-existing practice for trait enhancement.

Defining Transgenic Animals

• Transgenic animal: An animal altered by the introduction of recombinant DNA through human intervention.
• Transgenesis: Insertion of cDNA (from mRNA) into animal cells, directly manipulating DNA for gene expression.
• Developmental Biology and Genetic Engineering facilitated transgenic animal creation.
• Early gene transfers into mice showed foreign DNA integration & phenotypic modification was achievable.

DNA Transfer Methods and Applications

• Some DNA transfer methods cause random gene addition, targeted gene integration (homologous recombination/gene replacement), and mutation.
• Targeted mutation: Making a gene nonfunctional (knock-out) or less functional (knock-in).
• Current routine use of transgenic animals (mostly mice) is in human disease research.
• Potential agricultural applications include improved feed use, faster growth, disease resistance, leaner meat/other desirable qualities, and environmentally friendly animal waste.

Transgenic Animal Production & Design

• Transgenic animals carry a foreign gene (recombinant DNA) in their genome.
• Transgenic DNA usually includes sequences for incorporation & expression by host cells.
• Transgenic animals are modified to enhance traits.
• The first transgenic organism was E. coli, followed by a mouse with SV-40 viral DNA. SV-40 transgene was not expressed. The first expressing transgene animal was a mouse with cloned growth hormone.

Methods for Transgenic Livestock Production

• Various methods exist for producing transgenic livestock, including micro-injection, embryonic stem-cell, retrovirus, sperm-mediated, transposon-mediated, and nuclear transfer.

Ensuring Transgene Functionality

• For a transgene to function properly, integration of the appropriate promoter and regulatory sequences is needed.
• Some genes require an enhancer, potentially located away from the promoter.
• Correct fusion of promoters/enhancers is important for targeted gene expression.

Transgenic Animal Strategies

• Enhancing animal value for production traits and conventional animal products (e.g., milk, meat).
• Generating animals for biosynthesizing non-conventional commercial products.

Overall Applications

• Transgenic animal technology: Identifying/manipulating genes and their applications in domesticated farm animals.
• Improve animal productivity.

Explore the concepts of selective breeding and the creation of transgenic animals. Understand how genetic engineering has influenced animal traits and productivity through various DNA transfer methods. This quiz will test your knowledge on these fundamental biotechnological practices.