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Increased gene dosage for β - and κ -casein in transgenic cattle improves milk composition through complex effects

View Article: PubMed Central - PubMed

ABSTRACT

We have previously generated transgenic cattle with additional copies of bovine β- and κ casein genes. An initial characterisation of milk produced with a hormonally induced lactation from these transgenic cows showed an altered milk composition with elevated β-casein levels and twofold increased κ-casein content. Here we report the first in-depth characterisation of the composition of the enriched casein milk that was produced through a natural lactation. We have analyzed milk from the high expressing transgenic line TG3 for milk composition at early, peak, mid and late lactation. The introduction of additional β- and κ-casein genes resulted in the expected expression of the transgene derived proteins and an associated reduction in the size of the casein micelles. Expression of the transgenes was associated with complex changes in the expression levels of other milk proteins. Two other major milk components were affected, namely fat and micronutrients. In addition, the sialic acid content of the milk was increased. In contrast, the level of lactose remained unchanged. This novel milk with its substantially altered composition will provide insights into the regulatory processes synchronizing the synthesis and assembly of milk components, as well as production of potentially healthier milk with improved dairy processing characteristics.

No MeSH data available.


Concentration of total β-casein and κ-casein in TG3 and control milk.Shown are the β-casein and κ-casein levels found in a 24 h milk sample of seven transgenic TG3 (black) and six wild type control (red) cows at early, mid, peak and late lactation.
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f2: Concentration of total β-casein and κ-casein in TG3 and control milk.Shown are the β-casein and κ-casein levels found in a 24 h milk sample of seven transgenic TG3 (black) and six wild type control (red) cows at early, mid, peak and late lactation.

Mentions: Natural lactation milk samples from seven TG3 and six control cows were analyzed by high-performance liquid chromatography (HPLC) to quantify the levels of β-casein and κ-casein produced in the milk of these animals. In the TG3 line the normal gene dosage of two endogenous copies for β-casein has been increased by approximately five extra transgene copies16. Despite this, we detected only a small increase in total β-casein in the TG3-derived milk samples compared with control samples (Fig. 2). In early lactation samples, there was no apparent difference in the β–casein levels. A slight difference became noticeable in milk collected at peak and mid lactation, and was most prominent in late lactation samples with an approximate 15% (P < 0.001) increase in β-casein in the TG3-derived milk compared with control milk.


Increased gene dosage for β - and κ -casein in transgenic cattle improves milk composition through complex effects
Concentration of total β-casein and κ-casein in TG3 and control milk.Shown are the β-casein and κ-casein levels found in a 24 h milk sample of seven transgenic TG3 (black) and six wild type control (red) cows at early, mid, peak and late lactation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120311&req=5

f2: Concentration of total β-casein and κ-casein in TG3 and control milk.Shown are the β-casein and κ-casein levels found in a 24 h milk sample of seven transgenic TG3 (black) and six wild type control (red) cows at early, mid, peak and late lactation.
Mentions: Natural lactation milk samples from seven TG3 and six control cows were analyzed by high-performance liquid chromatography (HPLC) to quantify the levels of β-casein and κ-casein produced in the milk of these animals. In the TG3 line the normal gene dosage of two endogenous copies for β-casein has been increased by approximately five extra transgene copies16. Despite this, we detected only a small increase in total β-casein in the TG3-derived milk samples compared with control samples (Fig. 2). In early lactation samples, there was no apparent difference in the β–casein levels. A slight difference became noticeable in milk collected at peak and mid lactation, and was most prominent in late lactation samples with an approximate 15% (P < 0.001) increase in β-casein in the TG3-derived milk compared with control milk.

View Article: PubMed Central - PubMed

ABSTRACT

We have previously generated transgenic cattle with additional copies of bovine &beta;- and &kappa; casein genes. An initial characterisation of milk produced with a hormonally induced lactation from these transgenic cows showed an altered milk composition with elevated &beta;-casein levels and twofold increased &kappa;-casein content. Here we report the first in-depth characterisation of the composition of the enriched casein milk that was produced through a natural lactation. We have analyzed milk from the high expressing transgenic line TG3 for milk composition at early, peak, mid and late lactation. The introduction of additional &beta;- and &kappa;-casein genes resulted in the expected expression of the transgene derived proteins and an associated reduction in the size of the casein micelles. Expression of the transgenes was associated with complex changes in the expression levels of other milk proteins. Two other major milk components were affected, namely fat and micronutrients. In addition, the sialic acid content of the milk was increased. In contrast, the level of lactose remained unchanged. This novel milk with its substantially altered composition will provide insights into the regulatory processes synchronizing the synthesis and assembly of milk components, as well as production of potentially healthier milk with improved dairy processing characteristics.

No MeSH data available.