bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hormone-dependent expression of the ovine β-lactoglobulin gene
Authors: Osborne Rebecca , Howell Michael , Clark A. John , Nicholas Kevin R. 
Published: June 2009

SUMMARYThe minimal hormonal requirements for inducing the ovine β-lactoglobulin gene have been investigated using mammary gland explants from ewes in the first half of pregnancy. Quantification of β-lactoglobulin mRNA showed that a combination of insulin, Cortisol and prolactin was required to stimulate the expression of the gene and that this response could not be enhanced by the addition of oestrogen and thyroid hormone to the culture medium. Explants cultured in the presence of insulin, Cortisol and prolactin also demonstrated the capacity to synthesize the protein. Progesterone did not inhibit the induction of the gene, which is consistent with the increase in β-lactoglobulin mRNA observed in vivo in the mammary gland during the final 2 months of pregnancy when the circulating level of progesterone is elevated.
Inhibition of mitogen-induced proliferative responses of lymphocytes by bovine κ-caseinoglycopeptides having different carbohydrate chains
Authors: Otani Hajime , Monnai Makoto , Kawasaki Yoshihiro , Kawakami Hiroshi , Tanimoto Morimasa 
Published: June 2009

SUMMARYBovine κ-caseinoglycopeptides (i.e. residues 106–169, CGP) were prepared from κ-casein digested with rennin and a commercial whey protein concentrate. CGP from whey protein concentrate was further divided into seven CGP fractions having different carbohydrate compositions using FPLC. Unfractionated CGP inhibited lipopolysaccharide (LPS)- and phytohaemagglutinin (PHA)-induced proliferative responses of mouse spleen cells and rabbit Peyer's patch cells. The unfractionated CGP also inhibited antibody responses to sheep red blood cells in mouse spleen cell cultures. However, seven CGP fractions having zero to fiveN-acetylneuraminic acid (NANA) residues had different inhibitory effects on both LPS- and PHA-induced proliferative responses of mouse spleen cells. The inhibitory effect on PHA-induced proliferative responses increased with increasing numbers of NANA residues, whereas that on LPS-induced proliferation was highest with the CGP fraction having two NANA residues. Both inhibitory effects decreased significantly after neuraminidase or chymotrypsin digestion. These findings indicate that both the carbohydrate (particularly the NANA residues) and the polypeptide portions are essential for inhibitory effects on LPS- and PHA-induced proliferative responses of mouse spleen cells.
Immunomodulatory effects of dietary whey proteins in mice
Authors: Wong Chun W. , Watson Dennis L. 
Published: June 2009

SUMMARYStudies on the immunomodulatory properties of dietary whey proteins in mice are reported. Ingestion of bovine milk whey proteins, either as a supplement in an adequately balanced commercial diet or as the only protein source in a balanced diet, consistently enhanced secondary humoral antibody responses following systemic immunization with ovalbumin, when compared with other protein sources such as soyabean protein isolate and ovine colostral whey proteins. After 5–8 weeks of feeding, dietary milk whey proteins enhanced cell-mediated immune responses as revealed by footpad delayed-type hypersensitivity responses, and concanavalin A-induced spleen cell proliferative responses. To monitor nutritional effects of milk whey proteins, live weight, leucocyte counts and clinical changes of diet-fed mice were examined. The present results confirm other previous results that dietary bovine milk whey proteins have immunoenhancing properties in mice and these properties are unlikely to be related solely to the nutritional effects.
Effects ofStaphylococcus aureusproducts on growth and function of bovine mammary myoepithelial cellsin vitro
Authors: Zavizion Boris , John Bramley A. , Politis Ioannis 
Published: June 2009

SUMMARYThe effects of culture supernatants conditioned by the growth ofStaphylococcus aureusM60 onin vitrogrowth and functional properties of bovine mammary myoepithelial cells were examined. Myoepithelial cell proliferation was reduced byStaph, aurexisM60 culture supernatants. Exposure of myoepithelial cells to culture supernatants of isogeneic mutants ofStaph, aureusM60 that produced either α or β toxins reduced proliferation, but to a lesser extent than supernatants from the wild type strain. Thus, α and β toxins may play some role in affecting myoepithelial cell proliferation. Of the cells tested, 42% contracted following addition of oxytocin (10–7M) in the culture medium. Treatment of myoepithelial cells for 15 min withStaph, aureusM60 supernatants, prior to addition of oxytocin in the culture medium, increased the number of cells that contracted to 92%. Exposure of cells for 3 h to the same supernatant, prior to addition of oxytocin in the culture medium, abolished oxytocin responsiveness, had no effect on immunolocalization of actin and vimentin, but affected the localization of α-actinin within myoepithelial cells. Treatment of myoepithelial cells for 3 h with a combination of purified staphylococcal proteinases XVI and XVII-B abolished oxytocin responsiveness and mimicked the effect of theStaph, aureusculture supernatant. We conclude thatStaph, aureusM60 culture supernatant affected proliferation and functional properties of myoepithelial cells.
Milkability of Murciano–Granadina dairy goats. Milk partitioning and flow rate during machine milking according to parity, prolificacy and mode of suckling
Authors: Peris Silvia , Such Xavier , Caja Gerardo 
Published: June 2009

SummaryA total of 78 lactations (25 primiparous and 53 multiparous) in a herd of Murciano–Granadina dairy goats were studied over 3 years. Animals were allocated to two experimental groups: suckling (S) goats were milked once daily until weaning (week 7) and thereafter twice daily; milking (M) goats were milked twice daily from 2 d after parturition. Milk partitioning during milking (machine and machine stripping milk fractions) was recorded every week and the residual milk every 2 weeks. Milk flow rate was studied in 63 lactations on three consecutive days during week 12 or 13. Average machine and machine stripping milk fractions over 210 d were 1·09 and 0·23 1/d for the S and 1·23 and 0·28 1/d for the M group respectively. Machine milk volume and percentage were smaller in the S group during the first 7 weeks of lactation, while the machine stripping fraction was unaffected by group, indicating that this fraction was constant. The average residual milk was 11·1 and 9·2% of total milk in the S and M groups. Goats in their third lactation had the least residual milk (8·9%). Milk flow and total machine milk volume (but not milking time) were affected by parity, second and third lactation goats having higher values. Positive correlations were found between daily milk yield and milk flow characteristics. Residual milk was positively correlated with the machine stripping but not with the machine milk fraction. The results indicated that Murciano–Granadina goats can readily be machine milked, since > 80% of the milk can be obtained without massage or stripping.
Effects of pH and temperature on the water-holding capacity of casein curds and whey protein gels
Authors: Teo Cheng Tet , Munro Peter A. , Singh Harjinder , Hudson Rocky C. 
Published: June 2009

SummaryThe water-holding capacities of mineral acid casein (MAC) curd, rennet casein curd and whey protein concentrate (WPC) gel were determined as a function of pH and temperature by drainage of liquid on a stationary, horizontal screen. As precipitation pH was varied over the range 4·3–5·55, the water-holding capacity of MAC curd ranged from 2·4 to 5·2 g water/g dry casein with minimum water-holding capacity at precipitation pH 5·3. Samples of dried MAC curd over the same range of precipitation pH did not vary significantly in water-holding capacity, and all absorbed ∼2·0 g water/g dry casein. Both rennet casein curd and WPC (170 g total solids/kg) gels increased in water-holding capacity as the pH of the suspending liquid increased in the range 3·5–10, but the changes with pH were much smaller than for MAC curd. For both types of casein curd and for WPC gel, water-holding capacity decreased with increase in temperature in the range 5–90 °C. The results are interpreted largely in terms of changes in electrostatic interactions with pH and changes in hydrophobic interactions with temperature.
Purification of tributyrin esterase fromLactococcus lactissubsp.cremorisE8
Authors: Holland Ross , Coolbear Tim 
Published: June 2009

SummaryA tributyrin esterase was purified fromLactococcus lactissubsp.cremorisE8 using FPLC chromatography. This was the major esterase activity observed in strain E8 and was associated with a single protein with a subunit molecular mass of 29 kDa and a holoenzyme of molecular mass 109 kDa. The enzyme was active against tributyrin andp-nitrophenyl butyrate. The N-terminal sequence of the enzyme was determined. The enzyme had a pH optimum in the neutral range, was stable on freezing at −20 °C, and had a half life of 1 h at 50 °C.
Application of numerical analysis to a number of models for chymosin-induced coagulation of casein micelles
Authors: Hyslop Douglas B. , Qvist Karsten B. 
Published: June 2009

SummaryFour models describing renneting kinetics are evaluated for their ability to describe well documented attributes of the coagulation of casein micelles. The first model is based on a constant flocculation rate parameter. In the second the flocculation rate constant is proportional to the product of the sizes of the aggregating particles. Both models fail to predict proper dependence of rennet coagulation time on enzyme concentration. The third model is based on an energy barrier being reduced in linear proportion to the degree of proteolysis. The enzyme dependency of this model only works when the initial energy barrier is larger than ∼ 50 kBT (where kB is Boltzmann's constant and T the absolute temperature), which does not seem feasible. The fourth model, based on functionality theory, is able to predict proper dependence of rennet coagulation time on enzyme concentration when functionality is ∼ 2.
Iron-supplemented caseins: preparation, physicochemical characterization and stability
Authors: Gaucheron Frédéric , Famelart Marie-Hélène , Graët Yvon Le 
Published: June 2009

SummaryPreparation, physicochemical characterization and stability of iron-supplemented caseins were studied. When ferrous iron (final concentrations of 0·25, 0·5, 1·0 and 1·5 mM) was added to sodium caseinate (final casein concentration 25 g/l), iron binding to caseins was complete. In parallel, an increase in absorbance at 280 nm, a decrease in fluorescence intensity, modifications of reversed-phase HPLC profile, a decrease in pH and an increase in free sodium concentration were observed. Moreover, no release of iron from iron-casein complexes was found between pH 6·5 and 3·7 or after heat treatments or in the presence of inorganic phosphate. Only EDTA disodium salt and trisodium citrate had significant effects on the release of iron bound to caseins.
Effect of somatic cell count and stage of lactation on the quality and storage life of ultra high temperature milk
Authors: Auldist Martin J. , Coats Stephen J. , Sutherland Brian J. , Hardham John F. , McDowell Graham H. , Rogers Graeme L. 
Published: June 2009

SummaryThe effects of bulk milk cell count (BMCC) and stage of lactation on the quality and storage characteristics of UHT milk were investigated. The UHT milk was manufactured in a pilot plant using milk of low BMCC from early and late lactation, and milk of high BMCC from early and late lactation. Upon storage at 20°C, early lactation UHT milk gelled far ahead of late lactation milk. Within each stage of lactation, high BMCC milk tended to gel first. Few differences in the organoleptic properties of the UHT milks were observed. It was apparent that the onset of age gelation may not always be related directly to the level of proteolysis, and that other factors influencing milk composition and the reactions between milk components may play more important roles. At a particular stage of lactation, proteolysis induced by mastitis may hasten the onset of gelation.
Effect of different heat treatments on the strong binding interactions between whey proteins and milk fat globules in whole milk
Authors: Corredig Milena , Dalgleish Douglas G. 
Published: June 2009

SummaryThe heat-induced binding of whey proteins to milk fat globule membranes in whole milk was investigated by quantitative electrophoresis and laser scanning densitometry. Both α-lactalbumin and β-lactoglobulin bound to the surfaces of fat globules when milk was heated in a water bath in the temperature range 65–85 °C. The interaction behaviour of α-lactalbumin did not seem to change with temperature, and the total amount of protein bound was ∼ 0·2 mg/g fat contained in the cream. The quantity of βlactoglobulin interacting with the milk fat globules increased with temperature from 02 to 0·7 mg/g fat between 65° and 85 °C. Even in whole milk heated at batch pasteurization temperatures (60–65 °C), α-lactalbumin and β-lactoglobulin were found attached to the fat globules. The interactions of the whey proteins with intact fat globule membranes were also investigated in milk heated in an industrial system (a pilot scale UHT and high temperature short time module), and the results were compared with those from the laboratory treatment (simple batch heating). The binding of the whey proteins to fat globules differed between milk heated by UHT using indirect steam heating or direct steam injection (DSI). However, the surface load in milk treated by DSI was not comparable to that of milk treated by batch heating or indirect steam heating, because of the changes in fat globule size and membrane composition caused by the DSI process.
Synthesis of plasminogen activator inhibitor 1 by bovine mammary epithelial and myoepithelial cell lines
Authors: Zavizion Boris , Heegard Christian W. , White Jeffrey , Cheli Federica , Politis Ioannis 
Published: June 2009

SummaryConversion of plasminogen to plasmin provides an important source of proteolytic activity in the bovine mammary gland. Plasminogen activator inhibitor 1 (PAI-1) plays a key role in limiting plasminogen activation. The PAI-1 biosynthetic capabilities of various bovine mammary cells were determined. The immortalized epithelial cell lines MAC-T and BME-UV and the myoepithelial cell line BMM-UV were used as model systems. Northern blot analysis indicated that both epithelial and myoepithelial cells contained PAI-1 mRNA. Bovine PAI-1 was encoded by a single mRNA species ∼ 3·0 kb long. BME-UV cells contained 2·0-fold (P< 0·01) the PAI-1 mRNA of MAC-T or BMM-UV cells. Reverse zymography indicated that both epithelial and myoepithelial cells synthesized PAI-1 protein with a molecular mass of ∼ 50 kDa.
Reversibility of shrinkage of mineral acid casein curd as a function of ionic strength, pH and temperature
Authors: Teo Cheng Tet , Munro Peter A. , Singh Harjinder 
Published: June 2009

SummaryMineral acid casein (MAC) curd was subjected to a range of ionic strength, pH and temperature conditions to explore their effects on curd water-holding capacity, particularly the reversibility of shrinkage. The shrinkage of MAC curd on whey removal during the washing stage of casein manufacture could be attributed almost completely to the reduction in ionic strength and not specifically to either calcium or lactose removal. This shrinkage on whey removal during washing could not be reversed by adding whey back to the curd to attain the original ionic environment. In this sense it was irreversible. The pH during formation of MAC curd was more important than later pH adjustments in controlling curd water-holding capacity. The effect of a high precipitation pH in creating a tough, compact curd could not be reversed by subsequently decreasing the pH. However, the effect of a low precipitation pH in creating a soft, open curd could be partly reversed by subsequently increasing the pH. MAC curd shrank by 45% when the temperature was increased from 20 to 80°C. This temperature-dependent shrinkage was virtually fully reversible on cooling. It is suggested that the water-holding capacity of casein curd is governed largely by hydrophobic interactions and that once such interactions have occurred they cannot easily be disrupted by small changes in either pH or ionic strength.
318. The effect of acidity on the production of diacetyl by betacocci in milk
Authors: Cox G. A. 
Published: June 2009

1. The diacetyl production of betacocci isolated from starters, cheese and rye-grass was investigated at pR values ranging from 5.5 to 44. The betacocci produced diacetyl and subsequently partially or wholly destroyed it.2. There was a considerable variation in the amount of diacetyl produced by the different strains of betacocci. Capacity to produce diacetyl could not be correlated with any other property of the organisms.3. The rate of growth of the organisms was progressively slower the lower the pH, but at least as much diacetyl was eventually formed at low pK values as at high pH. values. The results showed that there was an alteration in the metabolism of the organisms, the diacetyl-producing power per unit cell increasing with decreasing pH.4. The results found enable an explanation of the rapid production of diacetyl in mixed starters to be offered.
Variation in the protein composition of bovine casein micelles and serum casein in relation to micellar size and milk temperature
Authors: Davies D. Thomas , Law Andrew J. R. 
Published: June 2009

SummaryThe caseinate complex in bovine milk was partitioned by differential centrifugation at both 20 and 4 °C into 4 micellar fractions and a fraction representing serum casein, and the protein composition of the fractions determined. At both temperatures the relative amount of κ-casein in the micellar caseins increased markedly and that of β-casein decreased appreciably with decreasing micelle size. The relative amount of αs2-casein also tended to decrease with decreasing micelle size, but the relative amounts of αs1- and γ-caseins, and an unidentified casein fraction, showed little systematic variation. The serum casein differed appreciably in composition from the micellar caseins, being very rich in β-casein and comparatively poor in αsl- and αs2-caseins, and the amount present at 4 °C was considerably greater than at 20 °C, with the increase being due almost entirely to β-casein, but with γ-casein also making a significant contribution. The changes in the composition and distribution of micellar and serum caseins induced by cooling milk at 4 °C were completely reversible when the milk was re-equilibrated at 20 °C for 18 h.
Use of deflector shields to reduce intramammary infection by preventing impacts on the teat ends of cows during machine milking
Authors: Griffin Tony K. , Williams Ray L. , Grindal Robert J. , Neave Frank K. , Westgarth David R. 
Published: June 2009

SUMMARYA series of short duration experiments has shown that infections caused by the milking machine or the way in which it is used can be controlled by fitting deflector shields in the teatcup liners. This not only provides a simple means of controlling such infections, but demonstrates that they result from penetration of the streak canal of the teat by contaminated milk particles impacting on the teat ends.
Metabolism of leucine by the isolated perfused goat udder
Authors: Roets Eddy , Massart-Leën Anne-Marie , Peeters Georges , Verbeke Roger 
Published: June 2009

SUMMARYSeven lactating goat mammary glands from 6 goats were perfused for several hours in the presence of [U-14C]L-leucine (4 experiments) or [2-3H; l-14C]DL-leucine (3 experiments) and received adequate quantities of glucose, acetate and amino acids. Radioactivity in casein was mainly recovered in leucine and 90% of casein leucine was derived from free plasma leucine. About 64% of the leucine molecules were used for casein synthesis. Up to 12% of the molecules were channelled into lipid synthesis, while the remaining (up to 24%) were metabolized to CO2. From the3H/14C ratio of casein and casein leucine, it was calculated that 70–80% of the leucine molecules were reversibly transaminated before their incorporation into milk protein. However, only 4–8% of the plasma leucine molecules were transaminated during passage through the udder. Different pools for oxidation and for protein synthesis may be present in the goat mammary gland.
Relationship between fatty acid composition and triglyceride structure of bovine milk fat
Authors: Parodi Peter W. 
Published: June 2009

SUMMARYFourteen samples of milk fat, representing a wide range of individual fatty acid contents, were subjected to stereospecific analysis to determine fatty acid contents at the sn-l-, sn-2- and sn-3-positions of the triglycerides. Highly significant linear relationships were found between the content of a fatty acid at the 3 positions and the content of the same acid in the intact triglycerides. As the content of an acid increased in the triglycerides there were increases in the content of that acid at the 3 positions. When the content of an acid changed in the triglycerides, the content at the 3 stereospecific positions did not change at the same rate. The positions with the highest slope values corresponded to the positions where the individual fatty acids were preferentially esterified.
Partial characterization of cheese-ripening proteinases produced by the yeastKluyveromyces lactis
Authors: Grieve Paul A. , Kitchen Barry J. , Dulley John R. , Bartley John 
Published: June 2009

SUMMARYAn extract ofKluyveromyces lactis416 and a β-galactosidase preparation (Maxilact 40000) contaminated with proteinase, showed similar pH profiles of caseinolytic activity. Similar modes of casein hydrolysis (κ-, > αs-, ≥ β-) were observed at pH 5·0 (the pH of Cheddar cheese), without detection of bitterness. The contaminated Maxilact preparation contained similar proteinase types to those detected in an autolysate ofK. lactis. Both the autolysate and the Maxilact preparation contained acid endopeptidase (proteinase A), serine endopeptidase (proteinase B) and serine exopeptidase (carboxypeptidase Y) activities. Some aminopeptidase activity was also detected in both preparations. There were some differences in apparent molecular weight and charge properties between proteinase A and B and carboxypeptidase Y from the 2 proteinase sources.
Effects of milk protein genetic variants on milk yield and composition
Authors: McLean Douglas M. , Graham E. R. Bruce , Ponzoni Raul W. , McKenzie Hugh A. 
Published: June 2009

SummaryEffects of genetic variants of the milk proteins, αs1-casein, β-casein, κ-casein and β-lactoglobulin (βlg), on milk yield and composition, particularly the protein composition, were investigated in milk samples from 289 Jersey and 249 Friesian cows in eight commercial herds.Milk protein genotypes had no significant effect on yields over a complete lactation of milk and fat, but significant differences in fat content were detected for β-casein (B, A1B, A2 > A1A2) and βlg (B, AB > A) variants. Significant differences between β-lg variants were also found with total solids (B, AB > A), casein (B, AB > A), whey protein (A > AB > B) and βlg (A > AB, AC > B > BC) concentrations. Casein genotypes were not significantly different in total protein and casein concentrations but many differences were found in casein composition. αs1-Casein variants significantly affected αs1-casein (BC > B) and κ-casein (B > BC) concentrations. β-Casein variants affected concentration and proportion of β-casein (A1B, A2B > A1, A1A2, A2, B), αs1-casein (A1, A2 > B) and κ-casein (B > A2) and concentration of whey protein (A1 > most other β-casein variants). κ-Casein variants affected concentration and proportion of κ-casein (B > AB > A), proportion of αs1-casein (A > AB > B) and concentration of βlg (A > AB, B) and α-lactalbumin (A, AB > B). Differences in milk composition were found between breeds, herds and ages, and with stage of lactation. The potential use of milk protein genotypes as an aid in dairy cattle breeding is discussed.