Cloning, cDNA analysis and prolactin-dependent expression of a marsupial alpha-lactalbumin

1990 ◽  
Vol 2 (6) ◽  
pp. 693 ◽  
Author(s):  
C Collet ◽  
R Joseph ◽  
K Nicholas
Keyword(s):  
Mammary Gland ◽  
Protein Conformation ◽  
Northern Blot Analysis ◽  
Tammar Wallaby ◽  
Amino Acid Residues ◽  
Macropus Eugenii ◽  
Cdna Analysis ◽  
Maximal Induction ◽  
Almost All ◽  
Alpha Lactalbumin

The gene for alpha-lactalbumin has been cloned from a tammar wallaby (Macropus eugenii) mammary gland cDNA library. Tammar alpha-lactalbumin has approximately 50 and 30% homology to the alpha-lactalbumins of eutherians at the levels of nucleotide and protein sequence respectively. Comparison of the inferred tammar polypeptide sequence with the sequence of the eutherian proteins reveals extensive divergence at almost all of the non-essential amino acid residues. However, the hydropathy plots of the tammar protein are almost identical to those of eutherian alpha-lactalbumins, suggesting that protein conformation is conserved. The tammar gene encodes a transcript of approximately 975 bases. Northern blot analysis of hormone-stimulated mammary gland explants shows that maximal induction of alpha-lactalbumin mRNA is dependent on prolactin and that expression is not modulated by other hormones that play a role in the initiation of lactation in eutherians.

PROLACTIN RECEPTORS IN THE MAMMARY GLAND, CORPUS LUTEUM AND OTHER TISSUES OF THE TAMMAR WALLABY, MACROPUS EUGENII

1979 ◽  
Vol 83 (1) ◽  
pp. 79-89 ◽  
Author(s):  
C. SERNIA ◽  
C. H. TYNDALE-BISCOE
Keyword(s):  
Mammary Gland ◽  
Corpus Luteum ◽  
Specific Binding ◽  
Tammar Wallaby ◽  
Binding Activity ◽  
Breeding Cycle ◽  
Macropus Eugenii ◽  
Lactating Mammary Gland ◽  
The Mean ◽  
Ovine Prolactin

SUMMARY Specific binding of radio-iodinated ovine prolactin to subcellular tissue fractions of the tammar wallaby (Macropus eugenii) was investigated. Specific binding was found, in order of decreasing binding activity, in the lactating mammary gland, corpus luteum, corpus albicans, adrenal gland and ovary. Specific binding was absent in kidney, liver, brain and inactive mammary gland. The mean association constant (Ka at 23 °C) was determined as 0·90 × 109, 2·20 × 109, 2·44 × 109, 3·38 × 109 and 10·98 × 1091/mol for mammary gland, adrenal, corpus albicans, corpus luteum and ovary respectively. The mean receptor concentration (N) varied from 92·87 × 10−14 mol/mg protein for the mammary gland to 1·03 × 10−14 mol/mg protein for the ovary. The concentration in the corpus luteum varied between tissue pools collected at different times of the annual breeding cycle. The specificity for prolactin was shown in the mammary gland and corpus luteum by the failure of ovine FSH, LH, GH and TSH to displace 125I-labelled ovine prolactin, whereas it was displaced readily by both ovine and bovine prolactin.

scholarly journals A novel whey protein synthesized only in late lactation by the mammary gland from the tammar (Macropus eugenii)

1987 ◽  
Vol 241 (3) ◽  
pp. 899-904 ◽  
Author(s):  
K R Nicholas ◽  
M Messer ◽  
C Elliott ◽  
F Maher ◽  
D C Shaw
Keyword(s):  
Mammary Gland ◽  
Amino Acid ◽  
Whey Protein ◽  
Sequence Data ◽  
Protein A ◽  
Gel Filtration ◽  
Tammar Wallaby ◽  
Exchange Chromatography ◽  
Macropus Eugenii ◽  
Apparent Homogeneity

A major whey protein which appears in milk from the tammar wallaby (Macropus eugenii) only during the second half of lactation (late lactation protein-A, LLP-A) was purified to apparent homogeneity by ion-exchange chromatography and gel filtration. An Mr of 21,600 +/- 2000 was calculated from its amino acid composition. A computer-based comparison of the sequence of the first 69 amino acid residues with the Atlas of Protein Sequence data base showed no significant homology with known proteins. Antiserum to LLP-A was prepared in rabbits, and single radial immunodiffusion was used to measure the amounts of LLP-A in milk during the first 40 weeks of lactation. LLP-A was first detected at 26 weeks; thereafter its concentration increased abruptly, to reach a maximum of 26 g/l at approx. 36 weeks of lactation. Explants prepared from mammary gland biopsies at 20 and 35 weeks of lactation were exposed to [3H]amino acids for 8 h; immunoprecipitation of tissue extracts showed that, whereas the rate of casein synthesis was the same at both stages of lactation, LLP-A was synthesized only by the 35-week mammary gland.

Molecular characterization and in-vitro hormonal requirements for expression of two casein genes from a marsupial

1992 ◽  
Vol 8 (1) ◽  
pp. 13-20 ◽  
Author(s):  
C. Collet ◽  
R. Joseph ◽  
K. Nicholas
Keyword(s):  
Mammary Gland ◽  
Late Pregnancy ◽  
Tammar Wallaby ◽  
Amino Acid Sequences ◽  
Mrna Levels ◽  
Casein Gene ◽  
Maximal Induction ◽  
Casein Genes ◽  
Β Lactoglobulin

ABSTRACT Two marsupial casein genes have been isolated from a tammar wallaby (Macropus eugenii) mammary gland cDNA library. Comparisons of the tammar α- and β-casein genes with their eutherian homologues reveal extensive divergence at the levels of nucleotide and amino acid sequences. Regions of similarity between the tammar and eutherian Ca2+-sensitive caseins are restricted to the major phosphorylation sites and the signal peptides. Quantification of casein mRNA levels in hormone-stimulated mammary gland explants from tammars in late pregnancy suggests that maximal induction of the β-casein gene is dependent upon prolactin and insulin, while maximal induction of the α-casein gene is dependent upon prolactin, insulin and cortisol. These results are in contrast to earlier studies which show that the maximal induction of a putative 19 kDa casein, α-lactalbumin and β-lactoglobulin in the tammar mammary gland is dependent upon prolactin alone. The expression of the latter three genes is not modulated by other hormones known to play a role in the in-vitro initiation of lactation in eutherians.

164. THE IMPRINT STATUS AND EXPRESSION OF INS IN THE TAMMAR WALLABY, MACROPUS EUGENII

2009 ◽  
Vol 21 (9) ◽  
pp. 82
Author(s):  
J. M. Stringer ◽  
G. Shaw ◽  
A. Pask ◽  
M. B. Renfree
Keyword(s):  
Mammary Gland ◽  
Genomic Imprinting ◽  
Direct Sequencing ◽  
Tammar Wallaby ◽  
Epigenetic Mechanism ◽  
Macropus Eugenii ◽  
Parental Allele ◽  
Absolute Requirement ◽  
Lactation Phase

Genomic imprinting is an epigenetic mechanism that differentially regulates the expression of certain genes, resulting in expression from only one parental allele. It is presumed to have first evolved after the divergence of therian mammals from the monotremes. One imprinted gene, INS is maternally imprinted (paternally expressed) in the eutherian and marsupial yolk sac1,2. INS encodes the precursor to the hormone insulin, which regulates carbohydrate metabolism and has a role in cell growth and, by regulating amino acid and fatty acid transporters, protein synthesis. In rats, mice and several other mammals insulin, in addition to cortisol and prolactin, is an absolute requirement for the onset of lactation and the synthesis of milk3. As imprinting plays an important role in regulating nutrition and growth the role of imprinted genes in the placenta has been the focus for imprinting research. Since the mammary gland provides a critical source of nutrition for the neonate in all mammals it is possible that genomic imprinting may have developed and been maintained in this organ. Given that marsupials deliver tiny, altricial young, it is in the relatively long and complex lactation phase where the mother has most control of the young's growth. Therefore, there may be greater selection for genomic imprinting in the marsupial mammary gland than in the eutherian mammary gland. This study examined the expression and the imprint status of INS in the mammary gland and neonatal tissues of the tammar wallaby, Macropus eugenii. INS expression was detected using PCR and direct sequencing provides evidence of INS imprinting in the mammary gland. This is the first study to identify imprinting in the mammary gland of a marsupial and the first to identify INS imprinting outside of the yolk sac.

Prolactin-dependent accumulation of α-lactalbumin in mammary gland explants from the pregnant tammar wallaby (Macropus eugenii)

1985 ◽  
Vol 106 (3) ◽  
pp. 337-342 ◽  
Author(s):  
K. R. Nicholas ◽  
C. H. Tyndale-Biscoe
Keyword(s):  
Mammary Gland ◽  
Culture Media ◽  
Amino Acid Uptake ◽  
Tammar Wallaby ◽  
Progressive Increase ◽  
Bovine Insulin ◽  
Acid Uptake ◽  
Macropus Eugenii ◽  
Rate Of Increase

ABSTRACT The minimal hormonal requirements for the in-vitro accumulation of α-lactalbumin have been investigated in a marsupial, the tammar (Macropus eugenii). Mammary gland explants from 24-day pregnant tammars cultured in medium containing bovine insulin, cortisol and ovine prolactin showed a progressive increase in accumulation of α-lactalbumin during 4 days of incubation. No increment was observed if prolactin was omitted from the medium. However, a similar rate of increase was observed after 3 days of culture in medium containing prolactin alone. This induction of α-lactalbumin was maximal at a prolactin concentration of approximately 0·02 mg/l, which corresponds to physiological levels during pregnancy and early lactation. The absence of an effect of bovine insulin on tammar explants is not due to a general unresponsiveness to this hormone since insulin-stimulated DNA synthesis and amino acid uptake was evident after 3 days of culture. The inclusion of tri-iodothyronine and raised concentrations of cortisol in culture media have been shown to modulate α-lactalbumin synthesis in eutherian mammals but were without effect in the tammar. In addition, increased levels of progesterone did not inhibit the induction of α-lactalbumin, confirming an earlier invivo study suggesting that progesterone withdrawal may not be the lactogenic trigger in this species. Thus the pregnant tammar is the only species yet described in which α-lactalbumin is induced maximally in vitro in response to a single hormone. J. Endocr. (1985) 106, 337–342

Cellular Components of the Milk of the Tammar Wallaby (Macropus eugenii)

1997 ◽  
Vol 45 (4) ◽  
pp. 423 ◽  
Author(s):  
L. Young ◽  
K. Basden ◽  
D. W. Cooper ◽  
E. M. Deane
Keyword(s):  
Mammary Gland ◽  
Mononuclear Cells ◽  
Tammar Wallaby ◽  
Mammary Glands ◽  
Cell Type ◽  
Phagocytic Cells ◽  
Macropus Eugenii ◽  
Predominant Cell Type ◽  
Cellular Components

The cellular components of colostrum and milk of the tammar wallaby (Macropus eugenii) have been investigated over the period of oestrus, lactation and weaning. Macrophages, neutrophils, lymphocytes and other vacuolated mononuclear cells were identified. The total number and diversity of cells were higher in colostral secretions and in secretions from post-lactational mammary glands. Neutrophils were the predominant cell type in early secretions. Macrophages were more prevalent in the milk of animals that no longer had young attached to the teat. These observations are consistent with suggestions that phagocytic cells play a role in post-lactational repair of the mammary gland but also suggest that non-specific phagocytic protection plays a role in protection of the neonatal marsupial.

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