Promoter I of the ovine acetyl-CoA carboxylase-alpha gene: an E-box motif at -114 in the proximal promoter binds upstream stimulatory factor (USF)-1 and USF-2 and acts as an insulin-response sequence in differentiating adipocytes.

Acetyl-CoA carboxylase-alpha (ACC-alpha) plays a central role in co-ordinating de novo fatty acid synthesis in animal tissues. We have characterized the regulatory region of the ovine ACC-alpha gene. Three promoters, PI, PII and PIII, are dispersed throughout 50 kb of genomic DNA.

Calcium signalling--an overview.

Calcium (Ca2+) is an almost universal intracellular messenger, controlling a diverse range of cellular processes, such as gene transcription, muscle contraction and cell proliferation. The ability of a simple ion such as Ca2+ to play a pivotal role in cell biology results from the facility that cells have to shape Ca2+ signals in the dimensions of space, time and amplitude. To generate the variety of observed Ca2+ signals, different cell types employ components selected from a Ca2+ signalling 'toolkit', which comprizes an array of signalling, homeostatic and sensory mechanisms.

Ovine adipose tissue monounsaturated fat content is correlated to depot-specific expression of the stearoyl-CoA desaturase gene.

The basis for the variation in fatty acid composition in different ovine adipose tissue depots was investigated. The proportion of stearic (C18:0) and oleic (C18:1) acids vary in a site-specific fashion; abdominal depots (omental and perirenal) contain relatively more C18:0 than C18:1, and carcass depots, especially sternum, have a markedly higher proportion of C18:1. Additionally, expression of a number of lipogenic enzyme genes (stearoyl-CoA desaturase [SCD], acetyl-CoA carboxylase-alpha [ACC-alpha], lipoprotein lipase [LPL]) and the cytoskeletal protein gene alpha-tubulin vary among depots, although the pattern of variation differs for each mRNA.

Present and future studies on lipogenesis in animals and human subjects.

Lipogenesis occurs in all vertebrate species and has a critical role in energy balance, providing a means whereby excess energy can be stored as a fat. The metabolic pathways involved and their tissue distribution in different species, including man, are well known. The responses of lipogenesis to diet and to physiological and pathological states have been the subject of many studies.

Insulin-glucocorticoid interactions in the regulation of acetyl-CoA carboxylase-alpha transcript diversity in ovine adipose tissue.

Transcription of the acetyl-CoA carboxylase (ACC)-alpha gene is initiated from two promoters, promoter I (PI) and promoter II (PII) such that transcripts demonstrate heterogeneity in their 5' untranslated regions (UTR). Exons 1 and 2 (E1 and E2) are the primary exons in transcripts initiated from PI and PII respectively; E5 is the first coding exon present in all transcripts. In addition alternative exon splicing results in transcripts that either include or exclude a 47 nucleotide sequence corresponding to E4, such that E[1/4/5] and E[1/5] type transcripts result from PI activity, whereas transcripts containing E[2/4/5] or E[2/5] in the 5'UTR result from PII.

Microwave Spectra of the Methylpolyynes CH3(C identical withC)4H and CH3(C identical withC)5H.

Following the laboratory detection by Fourier transform microwave spectroscopy of the four new methylcyanopolyynes described in the accompanying paper by W. Chen et al. (J.

Microwave Spectra of the Methylcyanopolyynes CH3(C&tbond;C)nCN, n = 2, 3, 4, 5.

The ground state rotational spectra of four methylcyanopolyynes CH3(C&tbond;C)2CN, CH3(C&tbond;C)3CN, CH3(C&tbond;C)4CN, and CH3(C&tbond;C)5CN were measured between 6 and 22 GHz by Fourier transform microwave spectroscopy. For CH3(C&tbond;C)2CN, previously observed by Alexander et al. [J.

Elucidation of a promoter activity that directs the expression of acetyl-CoA carboxylase alpha with an alternative N-terminus in a tissue-restricted fashion.

Previous studies in rats and humans have demonstrated that acetyl-CoA carboxylase alpha (ACC-alpha), the principal ACC isoenzyme in lipogenic tissues, is transcribed from two promoters, PI and PII, that operate in a tissue-specific fashion. Each promoter gives rise to ACC-alpha mRNA isoforms that differ in their 5' untranslated regions but essentially encode the same protein product. In the present study we demonstrate that such a pattern of promoter usage is evident in sheep tissues but in addition we have detected the expression of a novel ACC-alpha mRNA isoform that is expressed in a variety of tissues including kidney, lung, liver and mammary gland, where it is markedly induced during lactation.

Stearoyl-CoA desaturase mRNA is transcribed from a single gene in the ovine genome.

Clones corresponding to ovine stearoyl-CoA desaturase (SCD) cDNA were isolated from an adipose tissue cDNA library. All of these clones represented a single mRNA species as judged by restriction fragment and DNA sequence analysis. RNase protection analysis demonstrated that this SCD transcript is highly expressed in adipose tissue and liver, and in the mammary gland of lactating animals.

Hormonal control of insulin-like growth factor-binding protein-5 production in the involuting mammary gland of the rat.

We have demonstrated a 50-fold increase in the concentration of insulin-like growth factor-binding protein-5 (IGFBP-5) in milk after 2 days of mammary involution induced by removal of the suckling young. IGFBP-5 was identified by its immunoreactivity with an antiserum to IGFBP-5 and was shown by in situ hybridization to be synthesized by the secretory epithelial cells undergoing apoptosis. Smaller increases in IGFBP-2 and -4 messenger RNAs (mRNAs) were also evident, but neither protein could be detected on Western ligand blots of milk.

Repression of the acetyl-CoA carboxylase gene in ovine adipose tissue during lactation: the role of insulin responsiveness.

We have investigated the mechanisms whereby lipogenesis is markedly suppressed in adipose tissue depots of lactating sheep. Expression of the gene encoding acetyl-CoA carboxylase (ACC), the flux-determining enzyme of the lipogenic pathway, is reduced approximately threefold in both omental and subcutaneous adipose tissue depots during late pregnancy and remains so into lactation when compared with non-pregnant, non-lactating animals. By comparison, total ACC enzyme activity in these adipose depots is suppressed approximately 25- to 30-fold in lactation.

First astronomical detection of the cumulene carbon chain molecule H2C6 in TMC-1.

The cumulene carbenes are important components of hydrocarbon chemistry in low-mass star-forming cores. Here we report the first astronomical detection of the long-chain cumulene carbene H2C6 in the interstellar cloud TMC-1, from observations of two of its rotational transitions: J(K,K') = 7(1,7) --> 6(1,6) at 18.8 GHz and 8(1,8) --> 7(1,7) at 21.

Detection and Characterization of the Cumulene Carbenes H2C5 and H2C6.

Two cumulene carbenes, H2C5 and H2C6, were detected in a supersonic molecular beam by Fourier transform microwave spectroscopy. Their rotational and leading centrifugal distortion constants were determined with high accuracy, such that the entire radio spectrum can now be calculated. Like the known carbenes H2C3 and H2C4, both molecules have singlet electronic ground states and linear carbon-chain backbones.

Mammary protein synthesis is acutely regulated by the cellular hydration state.

The effect of cell-volume pertubations on mammary tissue protein synthesis has been examined. Cell-swelling, induced by a hyposmotic shock, increased the rate of incorporation of radiolabelled leucine and methionine into trichloroacetic acid precipitable material. The incorporation of radiolabel under both isosmotic and hyposmotic conditions was inhibited by cycloheximide.

The role of prolactin and growth hormone in the regulation of casein gene expression and mammary cell survival: relationships to milk synthesis and secretion.

We have compared involution of the rat mammary gland, induced by litter removal, where milk accumulation occurs, with involution induced in the presence of the suckling young by combined PRL and GH deficiency. Both treatments induced involutionary processes involving apoptosis, as judged by DNA ladders and resulted in significant decreases in the DNA content of the gland. Surprisingly, the effects of hormone deprivation on protein output in milk were principally explained by the loss of secretory cells, as there were only modest decreases in casein messenger RNA (mRNA) expression and protein synthesis rates per U DNA in vitro.