Genetic variability among and within domestic Old and New World camels at the α-lactalbumin gene (LALBA) reveals new alleles and polymorphisms responsible for differential expression.

α-Lactalbumin (α-LA), which is encoded by the LALBA gene, is a major whey protein that binds to Ca2+ and facilitates lactose synthesis as a regulatory subunit of the synthase enzyme complex. In addition, it has been shown to play central roles in immune modulation, cell-growth regulation, and antimicrobial activity. In this study, a multitechnical approach was used to fully characterize the LALBA gene and its variants in both coding and regulatory regions for domestic camelids (dromedary, Bactrian camel, alpaca, and llama). The gene analysis revealed a conserved structure among the camelids, but a slight difference in size (2,012 bp on average) due to intronic variations. Promoters were characterized for the transcription factor binding sites (11 found in total). Intraspecies sequence comparison showed 36 SNPs in total (2 in the dromedary, none in the Bactrian camel, 22 in the alpaca, and 12 in the llama), whereas interspecies comparison showed 86 additional polymorphic sites. Eight SNPs were identified as trans-specific polymorphisms, and 2 of them (g.112A>G and g.1229A>G) were particularly interesting in the New World camels. The first creates a new binding site for transcription factor SP1. An enhancing effect of the g.112G variant on the expression was demonstrated by 3 independent pGL3 gene reporter assays. The latter is responsible for the p.78Ile>Val AA replacement and represents novel allelic variants (named LALBA A and B). A link to protein variants has been established by isoelectric focusing (IEF), and bioinformatics analysis revealed that carriers of valine (g.1229G) have a higher glycosylation rate. Genotyping methods based on restriction fragment length polymorphism (PCR-RFLP) were set up for both SNPs. Overall, adenine was more frequent (0.54 and 0.76) at both loci. Four haplotypes were found, and the AA and GA were the most common with a frequency of 0.403 and 0.365, respectively. Conversely, a putative biological gain characterizes the haplotype GG. Therefore, opportunities for rapid directional selection can be realized if this haplotype is associated with favorable milk protein properties. This study adds knowledge at the gene and protein level for α-LA (LALBA) in camelids and importantly contributes to a relatively unexplored research area in these species.

Cell factory-based milk protein biomanufacturing: Advances and perspectives.

The increasing global population and protein demand cause global challenges for food supply. Fueled by significant developments in synthetic biology, microbial cell factories are constructed for the bioproduction of milk proteins, providing a promising approach for scalable and cost-effective production of alternative proteins. This review focused on the synthetic biology-based microbial cell factory construction for milk protein bioproduction. The composition, content, and functions of major milk proteins were first summarized, especially for caseins, α-lactalbumin, and ß-lactoglobulin. An economic analysis was performed to determine whether cell factory-based milk protein production is economically viable for industrial production. Cell factory-based milk protein production is proved to be economically viable for industrial production. However, there still exist some challenges for cell factory-based milk protein biomanufacturing and application, including the inefficient production of milk proteins, insufficient investigation of protein functional property, and insufficient food safety evaluation. Constructing new high-efficiency genetic regulatory elements and genome editing tools, coexpression/overexpression of chaperone genes, and engineering protein secretion pathways and establishing a cost-effective protein purification method are possible ways to improve the production efficiency. Milk protein biomanufacturing is one of the promising approaches to acquiring alternative proteins in the future, which is of great importance for supporting cellular agriculture.

Endosperm-specific accumulation of human α-lactalbumin increases seed lysine content in maize.

KEY MESSAGE: This study demonstrated high expression and accumulation of human α-lactalbumin in transgenic maize, and significant improvement of lysine content in maize endosperm. As a high-yield crop, lack of lysine in endosperm storage protein is a major defect of maize (Zea mays L.). Specifically expression of foreign proteins is a potential way to improve lysine content in maize endosperm. Human α-lactalbumin is such a protein with high lysine content and high nutritional value. In this study, the codon-optimized human lactalbumin alpha (LALBA) gene was driven by maize endosperm-specific 27 kD γ-zein promoter, and transformed into maize. Five independent transgenic lines were obtained, and LALBA was highly expressed in endosperm in all these lines. Protein assay indicated that human α-lactalbumin was highly accumulated in maize endosperm. Immuno-localization assay indicated that human α-lactalbumin was mainly deposited into the protein body (PB). Protein interaction assay showed that human α-lactalbumin interacted with 16 kD γ-zein, which might lead to its deposition to the PBs. Amino acid analysis of two independent transgenic lines showed significant increase of lysine contents in transgenic endosperm, with 47.26% and 45.15% increase to their non-transgenic seeds, respectively. We obtained transgenic maize with endosperm-specific accumulation of human α-lactalbumin at high level and increased the lysine content in maize endosperm. This study demonstrated an effective way to improve the nutritional value of maize seeds.

Efficient Bioproduction of Human Milk Alpha-Lactalbumin in Komagataella phaffii.

Alpha-lactalbumin (α-LA; the most abundant whey protein in human milk) contributes to infant development, providing bioactive peptides and essential amino acids. Here, Komagataella phaffii (K. phaffii) was selected as the production host. We found that the K. phaffii host X33 was suitable for expressing the target protein, yielding 5.2 mg·L-1 α-LA. Thereafter, several secretory signal peptides were applied to obtain a higher titer of α-LA. The strain with α-factor secretory signal peptide secreted the highest extracellular titer. Additionally, promoters AOX1, GAP, and GAP(m) were compared and applied. The strain with the promoter AOX1 produced the highest extracellular titer. In addition, coexpressing human protein disulfide isomerase A3 (hPDIA3) increased the titer by 27%. Human α-LA production by the strain X33-pPICZαA-hLALBA-hPDIA3 reached 56.3 mg·L-1 in a 3 L bioreactor. This is the first report of successful secretory human α-LA expression in K. phaffii and lays foundations for the simulation of human milk for infant formulas and further development of bioengineered milk.

The effect of single-nucleotide polymorphism in the promoter region of bovine alpha-lactalbumin (LALBA) gene on LALBA expression in milk cells and milk traits of cows.

Polymorphisms of milk protein genes have been proposed as candidate markers for dairy production traits in cattle. In the present study, a polymorphism was detected in the 5'-flanking (promoter) region of the bovine alpha-lactalbumin (LALBA) gene, a T/C transition located at nucleotide -1,001 relative to the transcription start site g.-1001T > C (NC_037332.1:g.31183170T > C), which is recognizable with PstI restriction endonuclease. In silico analyses showed that this mutation created novel retinoid X receptor alpha and vitamin D receptor transcription factor binding sites. Real-time PCR found that cows with different genetic variants of the promoter demonstrated different levels of expression of LALBA mRNA in milk somatic cells (MSCs). The TT genotype cows demonstrated low expression, whereas those with CT demonstrated much higher expression (P < 0.05). ELISA analysis found milk LALBA protein levels also differed between the TT and CT cows (P < 0.05) and that these levels were not correlated with the mRNA abundance in MSC. Association analysis found that the g.-1001T > C polymorphism in the promoter region of the LALBA gene influenced milk production traits in Polish Holstein-Friesian cows. High daily milk yield and dry matter yield, and high lactose yield and concentration were associated with the TT genotype. The TT genotype cows also had a lower number of somatic cells in the milk, considered as an indicator of udder health status. Therefore, the TT genotype could be more desirable from the breeder's perspective.

Fish lysozyme gene family evolution and divergent function in early development.

Lysozymes are an ancient group of antimicrobial enzymes of the innate immune system. Here we provide a comparative analysis of the evolution and function of lysozymes during early development in fish, the most speciose vertebrate group. In fishes, lineage and species-specific evolution of both C-type (chicken or conventional) and G-type (goose type) genes occurred. Phylogenetic analysis revealed that the teleost lysozyme G-type members group with the tetrapod homologues but the teleost C-type form three different clusters with the tetrapods. Most of the teleost C-type cluster with tetrapod Lyz but there are some that group with the mammalian Lyzl1/2 and LALBA. This suggests that early in gnathostome evolution these genes already existed and that lyzl1/2 and lalba genes are present in fish and tetrapods. Gene synteny analysis to confirm sequence orthologies failed to identify conserved genome regions between teleosts and other vertebrates lysozyme gene regions suggesting that in the ancestral bony fish genome lyz, lyzl1/2, lalba and lyg precursor genes were transposed to different chromosome regions. The homologue of the mammalian lactalbumin (LALBA) gene was identified for the first time in teleosts and was expressed in skin and during egg and larval development. Lysozyme activity was detected in teleost eggs and varied between species and in the gilthead sea bream lyg and lalba transcript abundance differed in eggs and larvae from different brood stock suggesting differences exist in maternal innate immune protection.

Identification and characterization of yak α-lactalbumin and ß-lactoglobulin.

α-Lactalbumin (α-LA) and ß-lactoglobulin (ß-LG) were isolated from yak milk and identified by mass spectrometry. The variant of α-LA (L8IIC8) in yak milk had 123 amino acids, and the sequence differed from α-LA from bovine milk. The amino acid at site 71 was Asn (N) in domestic yak milk, but Asp (D) in bovine and wild yak milk sequences. Yak ß-LG had 2 variants, ß-LG A (P02754) and ß-LG E (L8J1Z0). Both domestic yak and wild yak milk contained ß-LG E, but it was absent in bovine milk. The amino acid at site 158 of ß-Lg E was Gly (G) in yak but Glu (E) in bovine. The yak α-LA and ß-LG secondary structures were slightly different from those in bovine milk. The denaturation temperatures of yak α-LA and ß-LG were 52.1°C and 80.9°C, respectively. This study provides insights relevant to food functionality, food safety control, and the biological properties of yak milk products.

Thermally-Induced Lactosylation of Whey Proteins: Identification and Synthesis of Lactosylated ß-lactoglobulin Epitope.

The high temperatures used in the production of milk may induce modifications in proteins structure. Due to occurrence of the Maillard reaction, lactose binds lysine residues in proteins, affecting the nutritional value. Milk is also an important source of allergenic proteins (i.e., caseins, ß-lactoglobulin and α-lactalbumin). Thus, this modification may also affect the allergenicity of these proteins. Focusing on milk whey proteins, a screening on different Ultra High Temperatures (UHT) and pasteurized milk samples was performed to identify lactosylation sites, in particular in protein known epitopes, and to verify the correlation between lactosylation and the harshness of the treatment. Whey proteins were extracted from milk samples after caseins precipitations at pH 4.6 and, after chymotryptic and tryptic in solution digestion, peptides were analysed by UPLC-MS and LTQ-Orbitrap. Results show the presence of lactosylated lysine residues in several known epitopes. Then, a ß-lactoglobulin epitope was selected and synthesized by solid phase synthesis followed by in solution lactosylation, obtaining high reaction yields and purities. The synthesis of lactosylated allergenic epitopes, described here for the first time, is a useful tool for further studies on the technological impacts on food allergenicity.

Structural analysis and allergenicity assessment of an enzymatically cross-linked bovine α-lactalbumin polymer.

Enzymatic cross-linking is frequently used in bio-processing of dairy products since it could change the physiochemical and functional characterization. In our study, bovine α-lactalbumin was cross-linked by polyphenol oxidase from Agaricus bisporus and the changes in the structure, digestibility and allergenicity of α-lactalbumin were explored after cross-linking, and the structural alterations of the polymers were analyzed by circular dichroism spectroscopy, ultraviolet absorption spectroscopy and fluorescence spectroscopy. The digestibility of cross-linked α-lactalbumin was evaluated by simulated digestion in vitro. After that, the allergenicity of α-lactalbumin polymers was evaluated by detection of the specific IgE binding ability using an animal model. The results showed that the secondary and tertiary structures of various α-lactalbumin polymers exhibited a significant variation compared with those of untreated α-lactalbumin, and the cross-linked α-lactalbumin was relatively less susceptible to digestion. Moreover, the allergenicity of cross-linked polymers decreased significantly. These results suggested that there was a direct correlation between a loss of an α-helix and IgE binding to α-lactalbumin, which indicated that enzymatic cross-linking might be an efficient approach to reduce the allergenicity of bovine α-lactalbumin.

The impact of different mutations at arginine141 on the structure, subunit exchange dynamics and chaperone activity of Hsp16.3.

Hsp16.3, a molecular chaperone, plays a vital role in the growth and survival of Mycobacterium tuberculosis inside the host. We previously reported that deletion of three amino acid residues (142 STN144 ) from C-terminal extension (CTE) of Hsp16.3 triggers its structural perturbation and increases its chaperone activity, which reaches its apex upon the deletion of its entire CTE (141 RSTN144 ). Thus, we hypothesized that Arg141 (R141) and Ser142 (S142) in the CTE of Hsp16.3 possibly hold the key in maintaining its native-like structure and chaperone activity. To test this hypothesis, we generated two deletion mutants in which R141 and S142 were deleted individually (Hsp16.3ΔR141 and Hsp16.3ΔS142) and three substitution mutants in which R141 was replaced by lysine (Hsp16.3R141K), alanine (Hsp16.3R141A), and glutamic acid (Hsp16.3R141E), respectively. Hsp16.3ΔS142 or Hsp16.3R141K mutant has native-like structure and chaperone activity. Deletion of R141 from the CTE (Hsp16.3ΔR141) perturbs the secondary and tertiary structure, lowers the subunit exchange dynamics and decreases the chaperone activity of Hsp16.3. But, the substitution of R141 with alanine (Hsp16.3R141A) or glutamic acid (Hsp16.3R141E) perturbs its secondary and tertiary structure. Surprisingly, such charge tampering of R141 enhances the subunit exchange dynamics and chaperone activity of Hsp16.3. Interestingly, neither the deletion of R141/S142 nor the substitution of R141 with lysine, alanine and glutamic acid affects the oligomeric mass/size of Hsp16.3. Overall, our study suggests that R141 (especially the positive charge on R141) plays a crucial role in maintaining the native-like structure as well as in regulating subunit exchange dynamics and chaperone activity of Hsp16.3.

Polymorphism association and expression analysis of alpha-lactalbumin (LALBA) gene during lactation in Nili Ravi buffalo.

Alpha-lactalbumin has been reported as a highly polymorphic gene that potentially alters the gene expression and is associated with milk composition in dairy breeds. Current study was conducted in two phases. In the first phase, polymorphisms identification in alpha-lactalbumin (LALBA) gene and its association with milk composition was performed. To identify the genetic polymorphism, Nili Ravi buffaloes at their second lactation were selected from Government livestock farm (Buffalo Research Institute, Pattoki). Genomic DNA was extracted from blood samples. After PCR amplification, products were sequenced, and data was analyzed. Results showed that the identified polymorphisms at chromosomal position 34310940 were found associated with major whey protein. In the second phase of study, milk samples were collected from five healthy mastitis-free Nili Ravi buffaloes in their second lactation for expression analysis of alpha-lactalbumin gene at their transition (day 15), mid (day 90), and late (day 250) lactation. Gene expression was observed highest in transition phase with a gradual decrease of expression in mid and late phase of lactation. Further studies are needed to explore the regulation of milk production genes and their translational efficiency during the course of lactation.

Generating Goat Mammary Gland Bioreactors for Producing Recombinant Proteins by Gene Targeting.

Exogenous genes can be site-specifically integrated into the genomic DNA of animals by homologous recombination, generating transgenic animals. These animals have a clear hereditary background, although position effects of the exogenous genes and potential functional disruption of host genes can be caused by the genetic inserts. Therefore, the generation of mammary gland bioreactors via gene-targeting methods is a great asset for producing recombinant proteins in milk. Here, we describe a method of generating gene-targeted goats with the human alpha-lactalbumin gene (hα-LA) integrated into the beta-lactoglobulin gene (BLG) locus. The milk from these goats will be less allergenic and will be enriched with components of human milk protein.

Discrimination by RT-Nested PCR of Alpha-Lactalbumin Transcript Expression in Mammary Tumors.

Alpha-lactalbumin is a protein of milk expressed by mammary epithelial cells and by some breast tumors. The alpha-lactalbumin gene has two transcripts. The expression of transcript 2 has not yet been studied. The main objective of this paper was to establish the expression profile of alpha-lactalbumin at the mRNA level and to develop a technique discriminating between the two transcripts. The study was performed on 46 fresh mammary biopsies: 17 malignant tumors, 13 benign tumors, and 16 adjacent healthy tissues. We developed an RT-nested PCR to detect LALBA gene expression without distinction between transcripts. We also designed an RT-nested PCR that detects transcript 2. Both nested PCRs avoid amplification of potentially contaminating genomic DNA. We show that benign tumors tend to appear at a young age contrarily to malignant tumors appearing later with p value = 0.002. Moreover, LALBA transcript expression varies among tissues more important in benign (69%) than in malignant (35%) tumors with significant p value = 0.041. The intensity of the bands reflected differential expression between patients with concordant data between both RT-nested PCRs. We also performed a qualitative analysis according to histopathological parameters and molecular subtypes. The expression of transcript 2 appeared associated with the HER2+ subtype, while transcript 1 was associated with the luminal A and triple-negative subtypes. In conclusion, we designed specific and sensitive methods to detect LALBA transcripts. We show for the first time a differential expression of these transcripts, but we need to confirm their potential use as markers in breast cancer.

Effects of FGF21-secreting adipose-derived stem cells in thioacetamide-induced hepatic fibrosis.

Mesenchymal stem cells (MSCs) have been investigated to treat liver diseases, but the efficiency of MSCs to treat chronic liver diseases is conflicting. FGF21 can reduce inflammation and fibrosis. We established FGF21-secreting adipose derived stem cells (FGF21_ADSCs) to enhance the effects of ADSCs and transplanted them into thioacetamide (TAA)-induced liver fibrosis mice via the tail vein. Transplantation of FGF21_ADSCs significantly improved liver fibrosis by decreasing serum hyaluronic acid and reducing the expression of fibrosis-related factors such as α-smooth muscle actin (α-SMA), collagen and tissue inhibitor of metalloproteinase-1 (TIMP-1) compared with the Empty_ADSCs by inhibition of p-JNK, NF-κB and p-Smad2/3 signalling. α-lactoalbumin (LA) and lactotransferrin (LTF), secretory factors produced from FGF21_ADSCs inhibited TGF-ß1-induced expression of α-SMA and collagen in LX-2 cells. These results suggest that transplantation of FGF21_ADSCs inhibited liver fibrosis more effectively than Empty_ADSCs, possibly via secretion of α-LA and LTF.

Metabolomics Reveals Aryl Hydrocarbon Receptor Activation Induces Liver and Mammary Gland Metabolic Dysfunction in Lactating Mice.

The liver and the mammary gland have complementary metabolic roles during lactation. Substrates synthesized by the liver are released into the circulation and are taken up by the mammary gland for milk production. The aryl hydrocarbon receptor (AHR) has been identified as a lactation regulator in mice, and its activation has been associated with myriad morphological, molecular, and functional defects such as stunted gland development, decreased milk production, and changes in gene expression. In this study, we identified adverse metabolic changes in the lactation network (mammary, liver, and serum) associated with AHR activation using 1H nuclear magnetic resonance (NMR)-based metabolomics. Pregnant mice expressing Ahr d (low affinity) or Ahr b (high affinity) were fed diets containing beta naphthoflavone (BNF), a potent AHR agonist. Mammary, serum, and liver metabolomics analysis identified significant changes in lipid and TCA cycle intermediates in the Ahr b mice. We observed decreased amino acid and glucose levels in the mammary gland extracts of Ahr b mice fed BNF. The serum of BNF fed Ahr b mice had significant changes in LDL/VLDL (increased) and HDL, PC, and GPC (decreased). Quantitative PCR analysis revealed ∼50% reduction in the expression of key lactogenesis mammary genes including whey acid protein, α-lactalbumin, and ß-casein. We also observed morphologic and developmental disruptions in the mammary gland that are consistent with previous reports. Our observations support that AHR activity contributes to metabolism regulation in the lactation network.

Serum metabolomic profile in genetically modified cows carrying human α­lactalbumin gene.

The present study aimed to investigate the serum metabolomic profiles in genetically modified cows carrying and expressing human lactalbumin α (LALBA) and non­LALBA cows, and identify altered metabolic characteristics following the genetic modification. Serum biochemistry indexes were measured according to protocols recommended by International Federation of Clinical Chemistry. The metabolomic profiles were determined using the serum samples collected from LALBA (n=6) and non­LALBA cows (n=6). Welch's two­sample t­test was used to identify the metabolites that significantly differed between the LALBA and non­LALBA groups (fold­change ≠ 1 and P<0.05), followed by random forest and pathway analysis. The serum biochemistry indexes of LALBA and non­LALBA cows were within the normal ranges of healthy cows. A total of 273 metabolites were detected, among which 79 metabolites, including 46 increased and 33 decreased metabolites, differed significantly between the LALBA and non­LALBA groups. Random forest analysis identified 30 potential key metabolites, including 14 elevated and 16 reduced metabolites. These metabolites were primarily involved in pathways concerning the metabolism of leucine, isoleucine, valine, tryptophan and lipids, such as myristate and eicosapentaenoate. However, the serum in LALBA cow had unique metabolomic signature compared with non­LALBA cows. The accumulation of polyunsaturated fatty acids and amino acids, and the reduced levels of long chain saturated fatty acids in serum may benefit LALBA cows. However, further investigations are required to validate these benefits and the corresponding mechanisms.

Comparison of milk protein composition and rennet coagulation properties in native Swedish dairy cow breeds and high-yielding Swedish Red cows.

Recent studies have reported a very high frequency of noncoagulating milk in Swedish Red cows. The underlying factors are not fully understood. In this study, we explored rennet-induced coagulation properties and relative protein profiles in milk from native Swedish Mountain and Swedish Red Polled cows and compared them with a subset of noncoagulating (NC) and well-coagulating (WC) milk samples from modern Swedish Red cows. The native breeds displayed a very low prevalence of NC milk and superior milk coagulation properties compared with Swedish Red cows. The predominant variants in both native breeds were αS1-casein (αS1-CN) B, ß-CN A2 and ß-lactoglobulin (ß-LG) B. For κ-CN, the B variant was predominant in the Swedish Mountain cows, whereas the A variant was the most frequent in the Swedish Red Polled. The native breeds displayed similar protein composition, but varied in content of αS1-CN with 9 phosphorylated serines (9P) form. Within the Swedish Mountain cows, we observed a strong inverse correlation between the relative concentration of κ-CN and micelle size and a positive correlation between ionic calcium and gel firmness. For comparison, we investigated a subset of 29 NC and 28 WC milk samples, representing the extremes with regard to coagulation properties based on an initial screening of 395 Swedish Red cows. In Swedish Red, NC milk properties were found to be related to higher frequencies of ß-CN A2, κ-CN E and A variants, as well as ß-LG B, and the predominant composite genotype of ß- and κ-CN in the NC group was A2A2/AA. Generally, the A2A2/AA composite genotype was related to lower relative concentrations of κ-CN isoforms and higher relative concentrations of αS1-, αS2-, and ß-CN. Compared with the group of WC milk samples, NC milk contained a higher fraction of αS2-CN and α-lactalbumin (α-LA) but a lower fraction of αS1-CN 9P. In conclusion, milk from native Swedish breeds has good characteristics for cheese milk, which could be exploited in niche dairy products. In milk from Swedish Mountain cows, levels of ionic calcium seemed to be more important for rennet-induced gel firmness than variation in the relative protein profile. In Swedish Red, lower protein content as well as higher fraction of αS2-CN and lower fraction of αS1-CN 9P were related to NC milk. Further, a decrease in the frequency of the composite ß-κ-CN genotype A2A2/AA through selective breeding could have a positive effect on milk coagulation properties.

Generation of ß-lactoglobulin-modified transgenic goats by homologous recombination.

ß-Lactoglobulin (BLG) is a dominant allergen present in the milk of goats and other ungulates, although it is not found in human breast milk. Thus, the presence of BLG restricts the consumption of goat's milk by humans. In the present study, we examined whether the disruption of the BLG gene in goats by homologous recombination (HR) reduced BLG content in goat's milk and decreased the allergic response to milk. In one approach, exon 2 of the BLG gene was efficiently targeted using HR with a BLG knockout vector. In a second approach to disrupt BLG gene expression and drive exogenous human α-lactalbumin (hLA) gene expression, two hLA knock-in constructs were used to target exons 1-4 of the BLG gene via HR, and expression of hLA was then confirmed in goat mammary epithelial cells in vitro. The recombinant clones from both approaches were then used for somatic cell nuclear transfer, generating two transgenic goats possessing a BLG knockout allele or site-specific hLA integration allele. Milk assays demonstrated a reduction in BLG levels in both the BLG knockout and hLA knock-in goats; furthermore, hLA was present in the hLA knock-in goat's milk. Allergenic analysis in mice indicated that the transgenic goat's milk was less allergenic than wild-type goat's milk. These results support the development of gene-targeted animals as an effective tool for reducing allergic reactions to milk and improving nutrition.

An insufficient glucose supply causes reduced lactose synthesis in lactating dairy cows fed rice straw instead of alfalfa hay.

The objective of the present study was to investigate the nutrient availability for milk production in the mammary gland of lactating cows fed different forage-based diets. The 3 diets contained 30% corn stover (CS), 30% rice straw (RS), or 23% alfalfa hay plus 7% Chinese wild rye hay (AH) as a forage source. All diets contained 15% of DM as corn silage and 55% of DM as concentrate. The percentage of milk lactose was always lower in the RS-fed cows than in the cows fed AH or CS during the 12-wk feeding trial ( < 0.01). Ruminal propionate concentrations were lower in the RS group than in the AH group ( = 0.03). The ratio of insulin to glucagon in the mammary venous plasma was greater in the AH group than in the CS or RS group ( = 0.04). The abundance of the pyruvate carboxylase mRNA in the liver was lower in the RS group than in the AH or CS group ( = 0.04), and the abundance of mitochondrial phosphoenolpyruvate carboxykinase, IGF-1 receptor, and phosphofructokinase-liver, phosphofructokinase-muscle, and phosphofructokinase-platelet mRNA in the liver were lower in the RS group than in the AH group ( < 0.05). The mammary glucose uptake was greater in the AH-fed cows than in the CS- or RS-fed cows ( = 0.02). The mRNA abundance of the glucose transporters in the mammary gland was similar among the 3 treatments. The mRNA abundance of α-lactalbumin in the mammary gland of the cows fed RS tended to be greater compared with that of the cows fed AH or CS. The milk potassium concentration was greater in the cows fed RS than those fed AH or CS ( < 0.01). In summary, the insufficient ruminal propionate concentrations in the cows fed RS were associated with lower gluconeogenesis in the liver, resulting in the shortage of glucose supply for mammary utilization.

Can microbes compete with cows for sustainable protein production - A feasibility study on high quality protein.

An increasing population and their increased demand for high-protein diets will require dramatic changes in the food industry, as limited resources and environmental issues will make animal derived foods and proteins, gradually more unsustainable to produce. To explore alternatives to animal derived proteins, an economic model was built around the genome-scale metabolic network of E. coli to study the feasibility of recombinant protein production as a food source. Using a novel model, we predicted which microbial production strategies are optimal for economic return, by capturing the tradeoff between the market prices of substrates, product output and the efficiency of microbial production. A case study with the food protein, Bovine Alpha Lactalbumin was made to evaluate the upstream economic feasibilities. Simulations with different substrate profiles at maximum productivity were used to explore the feasibility of recombinant Bovine Alpha Lactalbumin production coupled with market prices of utilized materials. We found that recombinant protein production could be a feasible food source and an alternative to traditional sources.