The construction, identification and partial characterization of plasmids containing guinea-pig milk protein...

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• Lactating mammary glands produce specific proteins like casein and alpha-lactalbumin.
• Complementary DNA (cDNA) libraries are essential tools for studying gene expression.
• Understanding milk protein gene expression is crucial for mammary gland research.

Purpose of the Study:

• To construct a cDNA plasmid library from lactating guinea-pig mammary gland.
• To identify and characterize plasmids containing specific milk protein mRNA sequences.
• To investigate the representation of different milk protein mRNAs in the library.

Main Methods:

• Isolation of poly(A)-containing RNA from lactating guinea-pig mammary glands.
• Synthesis of double-stranded complementary DNA (cDNA).
• Insertion of cDNA into the pAT153 plasmid using poly(dA.dT) tails and transformation into Escherichia coli HB101.
• Selection and partial characterization of recombinant plasmids.

Main Results:

• A functional cDNA plasmid library was successfully constructed.
• Plasmids containing complementary DNA (cDNA) copies of casein A, casein B, and alpha-lactalbumin mRNAs were identified.
• The proportion of plasmids containing casein C cDNA was notably low, with incomplete mRNA sequences.

Conclusions:

• The constructed cDNA library provides a valuable resource for studying mammary gland gene expression.
• The differential representation of milk protein mRNAs highlights potential regulatory mechanisms.
• Further investigation is needed to fully characterize casein C and understand its low representation.