RESUMO
Beef marbling is caused by intramuscular deposition and it is an economically important trait in the beef industry. Vitamin A (VA) is an important feed supplement for cattle, but it can hinder marbling if provided in excess. In cattle, VA forms various derivatives such as all-trans retinoic acid (ATRA) and 9-cis retinoic acid (9cRA). Therefore, we investigated the genes involved in bovine intramuscular adipogenesis after VA treatment with ATRA and 9cRA. Differential gene expression levels were validated by microarray analysis in a clonal bovine intramuscular preadipocyte (BIP) cell line derived from the intramuscular adipose tissue of Japanese Black cattle. BIP cells were harvested 6 days after adipogenic stimulation with either 1 µmol/L ATRA, 1 µmol/L 9cRA or non-retinoic acid control. The ATRA- and 9cRA-treated cells exhibited reduced transcription of genes involved in the circulatory system and muscle development compared with the no retinoic acid (RA) treatment. In addition, the ATRA- and 9cRA-treated cells exhibited increased transcription of genes involved in the immune system, protein kinase B signaling and responses to various stimuli. These results demonstrate the lower expression of muscle development in ATRA- and 9cRA-treated BIP cells during adipogenesis.
Assuntos
Adipócitos/citologia , Diferenciação Celular/genética , Músculo Esquelético/citologia , Análise de Sequência com Séries de Oligonucleotídeos , Transcriptoma/efeitos dos fármacos , Tretinoína/farmacologia , Adipogenia/genética , Tecido Adiposo/citologia , Alitretinoína , Ração Animal , Animais , Bovinos , Células Cultivadas , Suplementos Nutricionais , Qualidade dos Alimentos , Carne , Proteínas Proto-Oncogênicas c-akt/fisiologia , Transdução de Sinais/genética , Transcrição Gênica/efeitos dos fármacosRESUMO
To investigate genes involved in intramuscular adipogenesis in ruminants, 16 genes with dramatic variable expression were selected. These were selected from the differentiation- and proliferation-phase libraries of our previous serial analysis of gene expression (SAGE) studies of a clonal bovine intramuscular preadipocyte (BIP) cell line. We harvested the BIP cells over 12 days after adipogenic stimulation with all-trans retinoic acid (ATRA). Quantitative real-time PCR confirmed the earlier SAGE study results of the expression patterns of 15 of the genes. On day 6, TG accumulation increased significantly in the BIP cells but was completely inhibited in the 3T3-L1 cells (the monogastric reference). ATRA enhanced expression levels of six genes whereas it suppressed expression of eight genes on day 3 of adipogenesis in the BIP cells. Forty-eight hours after transfection, the messenger RNA expression level of the adipose differentiation-related protein (ADFP), encoded by one of the upregulated genes, in the ADFP small interference RNA (siRNA)-transfected cells was 3.5% of that in negative control-transfected cells. Also, 6 days after induction the TG level in the ADFPâ siRNA-transfected cells was 21.8% lower than that in negative control-transfected cells. This analysis of gene expression profiles after ATRA treatment will contribute to our understanding of the molecular mechanisms involved in bovine intramuscular adipogenesis.
Assuntos
Adipócitos/metabolismo , Adipogenia/genética , Proteínas de Membrana/genética , Músculos/metabolismo , Transcriptoma/efeitos dos fármacos , Tretinoína/farmacologia , Adipócitos/citologia , Animais , Sequência de Bases , Bovinos , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/genética , Linhagem Celular , Dados de Sequência Molecular , Músculos/citologia , Perilipina-2 , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/genética , Reação em Cadeia da Polimerase em Tempo Real , Fatores de Tempo , Transfecção , Triglicerídeos/metabolismo , Regulação para CimaRESUMO
Experiences of odours at meals are thought to affect food preference in many animals. To study appetite modulation by odours, we established a new experimental system based on the modification of a previous method, where flies fed sucrose flavoured with D-limonene subsequently showed reduced appetite to plain sucrose. In this new experimental system, a fly population was divided into two groups: (1) the "simultaneous" group of flies was exposed to D-limonene and sucrose simultaneously for 10 min, and (2) the "separate" group of flies was exposed to sucrose alone for 10 min, and 1h later, to limonene for 10 min. The appetite of flies in the "separate" group for sucrose was unaffected by the experiment, but the appetite of flies in the "simultaneous" group was significantly decreased, and this effect lasted for > or = 3 days. To investigate if this appetite modulation by D-limonene was based on long-term memory formation (protein synthesis), we examined the effects of the protein synthesis inhibitor, cycloheximide. Injection of cycloheximide 1h after exposure to limonene and sucrose inhibited the appetite suppression in the "simultaneous" group of flies. In addition, to exclude the possibility that D-limonene exerted its effect through taste, rather than odour, we examined the effect of removing of the olfactory organs, antennae and maxillary palps on appetite modulation by D-limonene. When the olfactory organs were removed, no reduction in appetite was observed in the flies in the "simultaneous" group, indicating olfaction. In our new and effective appetite-modulation system for flies, modulation of appetite by olfactory detection of D-limonene was shown.
