Characterization of casein and alpha lactalbumin of African elephant (Loxodonta africana) milk

Madende, Moses; Osthoff, Gernot; Patterton, H. Elize; Martin, Patrice; Opperman, Diederik J.

doi:10.3168/jds.2014-9195

Cited by 15 publications

(5 citation statements)

References 35 publications

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“…Lactation process in mammary glands is accompanied by high circulating levels of prolactin, thus inducing the expression of β-casein and α-lactalbumin proteins (Madende et al 2015). Lactation involves abrupt changes in endoplasmic reticulum load and expression of ERS pathway proteins in mammary glands (Baldassarre et al 2011).…”

Section: Introductionmentioning

confidence: 98%

Alpha-ketoglutarate enhances milk protein synthesis by porcine mammary epithelial cells

Jiang

Hou

et al. 2016

Amino Acids

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Alpha-ketoglutarate (AKG), a key intermediate in the Krebs cycle, has been reported to promote protein synthesis through activating mechanistic targeting of rapamycin (mTOR) in enterocytes. The study tested the hypothesis that AKG may enhance growth and milk protein synthesis in porcine mammary epithelial cells (PMECs). PMECs were cultured for 96 h in Dulbecco's modified Eagle's-F12 Ham medium (DMEM-F12) containing prolactin (2 µg/ml) and AKG (0 or 1.5 mM). At the end of 96-h culture, the abundance of apoptosis-related proteins (caspase-3, caspase-9), milk-specific proteins (α-lactalbumin and β-casein), mTOR signaling proteins (mTOR, p-mTOR, PERK, p-PERK, eIF2a, P70S6K and p-P70S6K), and endoplasmic reticulum stress (ERS)-associated proteins (BiP and CHOP) in PMEC were determined. Addition of AKG dose-dependently enhanced cell viability in the absence or presence of prolactin, with optimal concentrations of AKG being at 1.0 and 1.5 mM, respectively. In the presence of prolactin, addition of 1.5 mM AKG: (1) decreased (P < 0.05) the abundance of caspase-3 and caspase-9 by 21 and 39 %; (2) enhanced (P < 0.05) the phosphorylation of p-mTOR and p-P70S6K by 39 and 89 %, respectively; (3) increased (P < 0.05) the production of β-casein and α-lactalbumin by 16 and 20 %, respectively; (4) attenuated (P < 0.05) the expression of CHOP by 34 % but promoted (P < 0.05) the expression of BiP by 46 %; (5) increased (P < 0.05) the secretion of lactose by 15 %, when compared to the 0 mM AKG group. Rapamycin (50 nM; an inhibitor of mTOR) attenuated (P < 0.05) the stimulatory effect of AKG on mTOR signaling and syntheses of milk protein and lactose, while relieving (P < 0.05) an inhibitory effect of AKG on expression of proteins related to ERS. Collectively, our results indicate that AKG enhances milk protein production by modulating mTOR and ERS signaling pathways in PMECs.

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Section: Introductionmentioning

confidence: 98%

Alpha-ketoglutarate enhances milk protein synthesis by porcine mammary epithelial cells

Jiang

Hou

et al. 2016

Amino Acids

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“…While some of the milk oligosaccharides are shared with other mammals, certain structures are unique to elephants. The whey protein composition seems to be similar to that of other eutherian milks; however, the caseins only consist of β- and κ-caseins, with the β-casein being phosphorylated on one site compared to the multi-phosphorylated equivalents of cow, horse, and human [ 8 , 9 ]. It has also been shown that the milk composition of Asian and African elephants changes drastically with the progression of lactation—more than observed in any other eutherian milk, but almost the same to that of marsupials [ 2 , 3 ].…”

Section: Introductionmentioning

confidence: 99%

The Dynamic Changes of African Elephant Milk Composition over Lactation

Kobeni

Osthoff

Madende

et al. 2020

Animals

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The combined data of milk composition of 14 African elephants over 25 months of lactation are presented. The milk density was constant during lactation. The total protein content increased with progressing lactation, with caseins as the predominant protein fraction. The total carbohydrates steadily decreased, with the oligosaccharides becoming the major fraction. Lactose and isoglobotriose reached equal levels at mid lactation. The milk fat content increased during lactation, as did the caprylic and capric acids, while the 12 carbon and longer fatty acids decreased. The fatty acid composition of the milk phospholipids fluctuated, and their total saturated fatty acid composition was low compared to the triacylglycerides. The milk ash and content of the major minerals, Na, K, Mg, P, and Ca, increased. Vitamin content was low, Vitamin E occurred in quantifiable amounts, with traces of vitamins A, D3, and K. The energy levels of African elephant milk did not change much in the first ten months of lactation, but they increased thereafter due to the increase in protein and fat content. The overall changes in milk composition appeared to be in two stages: (a) strong changes up to approximately 12 months of lactation and (b) little or no changes thereafter.

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“…Data from the current study support this observation, although we also propose that casein micelles do not strictly require all four casein types for their formation. Recent data from proteomics analysis of African elephant milk, which is devoid of α s -caseins (Madende et al, 2015), shows that this milk contains casein micelles (unpublished). Moreover, its β-casein, which is highly abundant, also displays a very different phosphorylation profile compared to that of cow β-casein, and could potentially take up the role that α s -caseins play in the formation of casein micelles (Madende et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…However, it appears that some mammalian species are devoid of some casein types. African elephant milk, for example, lacks α-caseins, but nevertheless contains casein micelles just as observed in the milk of all mammalian species studied so far (Martin et al ., 2013; Madende et al ., 2015).…”

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confidence: 99%

Comparative genomics of casein genes

Madende

Osthoff

2019

Journal of Dairy Research

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This research paper addresses the hypothesis that comparative genomics can give a new insight into the functionality of casein genes with respect to the casein micelle. Comparative genomics is a rapidly emerging field in computational biology whereby two or more genomes are compared in order to obtain a global view on genomes as well as assigning previously unknown functions for genes. Casein genes are among the most rapidly evolving mammalian genes, with the gene products mainly grouped into four types (αs1-, αs2-, β- and κ-casein). Functionally, casein genes are central to the casein micelle, the exact structure of which is still a subject of intense debate. Moreover, and adding to this complexity, some mammals lack some of the casein genes, although casein micelles have been observed in their milk. This observation has prompted an investigation into the distribution of casein genes across a host of mammalian species. It was apparent from this study that casein gene sequences are very diverse from each other and we confirmed that many mammalian species lack one or more of the casein genes. The genes encoding β- and κ-caseins are present in most mammals whereas α-casein encoding genes are less represented. This suggests different mechanisms for casein micelle formation in different species as well as the functions that are assigned to each individual casein.

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Characterization of casein and alpha lactalbumin of African elephant (Loxodonta africana) milk

Cited by 15 publications

References 35 publications

Alpha-ketoglutarate enhances milk protein synthesis by porcine mammary epithelial cells

Alpha-ketoglutarate enhances milk protein synthesis by porcine mammary epithelial cells

The Dynamic Changes of African Elephant Milk Composition over Lactation

Comparative genomics of casein genes

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