• Molecules and Cells
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• 제38권7호
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• pp.597-603
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• 2015

Biosynthesis of the phytohormone ethylene is under tight regulation to satisfy the need for appropriate levels of ethylene in plants in response to exogenous and endogenous stimuli. The enzyme 1-aminocyclopropane-1-carboxylic acid synthase (ACS), which catalyzes the rate-limiting step of ethylene biosynthesis, plays a central role to regulate ethylene production through changes in ACS gene expression levels and the activity of the enzyme. Together with molecular genetic studies suggesting the roles of post-translational modification of the ACS, newly emerging evidence strongly suggests that the regulation of ACS protein stability is an alternative mechanism that controls ethylene production, in addition to the transcriptional regulation of ACS genes. In this review, recent new insight into the regulation of ACS protein turnover is highlighted, with a special focus on the roles of phosphorylation, ubiquitination, and novel components that regulate the turnover of ACS proteins. The prospect of cross-talk between ethylene biosynthesis and other signaling pathways to control turnover of the ACS protein is also considered.

• Asian-Australasian Journal of Animal Sciences
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• 제7권2호
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• pp.279-288
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• 1994

Three experiments were conducted with female Japanese Saanen goats to investigate the effects of rumen protected methionine (RPMet) on N utilization and whole-body protein turnover. Whole-body leucine flux from which whole-body protein turnover rates were derived was measured by primed- continuous infusion of L-[$^{15}N$] leucine in combination with gas chromatography-mass spectrometry. Throughout the experiments RPMet was added to a diet to supply 1.5 g DL-methionine per goat per day. Irrespective of the major N sources (i.e., protein or urea) in the diet, both N deposition and whole-body protein synthesis were increased (p<0.05), and urinary N excretion was decreased (p<0.05) by supplementing with RPMet, but not by supplementing with methionine. It was concluded, therefore, that under the present experimental conditions, the RPMet supplement was efficiently bypassed to result in enhanced body protein synthesis of the goat.

• Asian-Australasian Journal of Animal Sciences
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• 제18권1호
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• pp.133-140
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• 2005

Although amino acids are substrates for the synthesis of proteins and nitrogen-containing compounds, it has become more and more clear over the years that these nutrients are also extremely important as regulators of body protein turnover. The branched-chain amino acids (BCAAs) together or simply leucine alone stimulate protein synthesis and inhibit protein breakdown in skeletal muscle. However, it was only recently that the mechanism(s) involved in the regulation of protein turnover by BCAAs has begun to be defined. The acceleration of protein synthesis by these amino acids seems to occur at the level of peptide chain initiation. Oral administration of leucine to food-deprived rats enhances muscle protein synthesis, in part, through activation of the mRNA binding step of translation initiation. Despite our knowledge of the induction of protein synthesis by BCAAs, there are few studies on the suppression of protein degradation. The recent findings that oral administration of leucine rapidly reduced $N^{\tau}$-methylhistidine (3-methylhistidine; MeHis) release from isolated muscle, an index of myofibrillar protein degradation, indicate that leucine suppresses myofiblilar protein degradation. The details of the molecular mechanism by which leucine inhibits proteolysis is just beginning to be elucidated. The purpose of this report was to review the current understanding of how BCAAs act as regulators of protein turnover.

• Asian-Australasian Journal of Animal Sciences
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• 제2권3호
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• pp.235-236
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• 1989

• Asian-Australasian Journal of Animal Sciences
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• 제2권3호
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• pp.200-201
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• 1989

• Asian-Australasian Journal of Animal Sciences
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• 제13권5호
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• pp.702-710
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• 2000

A large portion of total energy expenditure associated with ruminant livestock production goes towards maintenance. Approximately 55% of whole body energy use is consumed by visceral tissues (including internal organs) with the majority of this going to the liver and gastrointestinal tract. Muscle and adipose tissues consume about 27% of total body energy expenditure. Metabolic components within the viscera responsible for the majority of energy consumption include ion transport, protein turnover, substrate cycling, and urea synthesis (liver). Within muscle tissue of growing animals ion transport and protein turnover account for most of the energy expenditure. Protein synthesis consumes approximately 23% of whole body energy use and visceral tissues account for proportionally more of whole body protein synthesis than skeletal muscle. Research efforts focused on improving energetic efficiency of the tissues and metabolic mechanisms responsible for the majority of whole animal energy expenditure should provide information leading to more efficient production of an edible product.

• Asian-Australasian Journal of Animal Sciences
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• 제24권4호
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• pp.485-492
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• 2011

The influence of high temperature on mammary cell turnover during the dry period is still unclear. The objective of this study was to investigate mammary cell turnover and p53 protein expression in the mammary tissue under high temperature conditions. Mammary gland biopsy samples from 8 dairy cows were obtained at 7, 25, 40, and 53 d during the dry period in summer or spring (n = 4, each season). Cell cycle, cell turnover, and p53 protein expression were analyzed by flow cytometry. During the dry period in summer, the percentage of mammary epithelial cells in the G0/G1 phase was the highest, but those in the S and G2/M phases were lower. However, the proportion of cells in the different stages of the cell cycle was not significantly different among the different biopsy time points, except in the G2/M phase. Under different temperature conditions, the cells were significantly different in their apoptotic rate and proliferation index; moreover, the tendencies of these indicators to change significantly differed. In general, the samples under high temperature conditions showed significantly lower apoptotic rates and proliferation indices. Under high temperature conditions, the apoptotic rate and proliferation index were the lowest (2.17% and 3.26%, respectively) at day 40, and the highest at day 53 (3.67% and 4.61%, respectively). However, under normal temperature conditions, the values of these indicators were the lowest (7.60% and 5.54%, respectively) at day 7, and almost the highest at day 25 (12.85% and 6.47%, respectively). Moreover, p53 protein expression was significantly higher under high temperature conditions than under normal temperature conditions, except at day 25. The level of p53 protein was the lowest (13.10%) under high temperature conditions at day 25, but was the highest (26.07%) under normal temperature conditions. Our findings suggest that high temperature delayed the G2/M phase of the cell cycle and the cell turnover rate, but remarkably increased p53 protein expression. Thus, the results indicate that high temperature extends the recovery period of mammary epithelial cells.

• BMB Reports
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• 제29권6호
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• pp.549-554
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• 1996

Phosphoinositide turnover in response to platelet-derived growth factor, epidermal growth factor, and bradykinin was evaluated in NIH 3T3 cells. Platelet-derived growth factor and bradykinin induced a significant increase in incorporation of $^{32}P$ into phosphatidylinositol (PI), phosphatidylinositol 4-monophosphate (PIP), and phosphatidylinositol 4.5-bisphosphate ($PIP_2$) in serum-starved NIH 3T3 cells. However, epidermal growth factor increased incorporation of $^{32}P$ into these phosphoinositides by only a small amount. Stimulation with platelet-derived growth factor, not bradykinin, caused a rapid elevation of PI and PIP kinase activities that were maximally activated within 10 min. The maximal levels of their elevation in cells with plateletderived growth factor stimulation were 3.2-fold for PI kinase, and 2.1-fold for PIP kinase. Short term pretreatment of NIH 3T3 cells with phorbol 12-myristate 13-acetate, activator of protein kinase C. caused an approximately 60% decrease in platelet-derived growth factor-induced PI kinase activities, indicating the feedback regulation of phosphoinositide turnover by protein kinase C. These results suggest that although the enhancement of phosphoinositide turnover is a rapidly occurring response in platelet-derived growth factor- or bradykinin-stimulated NIH 3T3 cells, phosphoinositide kinases may be associated with initial signal transduction pathway relevant to platelet-derived growth factor but not to bradykinin.

• 한국가금학회지
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• 제43권4호
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• pp.213-218
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• 2016

본 연구는 고온 스트레스 하에 타우린 첨가가 육계의 간에서 heat shock protein 70(hsp 70) 및 cell free system 상태에서 단백질 합성에 미치는 영향을 조사하였다. 공시동물은 1일령 육계 120수를 2주간 사육 후, 대조(CO, $24^{\circ}C$)와 고온스트레스 처리($34^{\circ}C$)에서 타우린을 공급하지 않은 처리구(HO)와 타우린 0.1%를 공급한 처리구(HT)로 나누어 3처리 4반복, 반복 당 10수씩 배치하였다. 고온 스트레스는 3, 6, 9, 12일간 진행하였다. 최종 체중과 간 무게는 HO와 HT가 CO보다 유의적으로 낮았다(P<0.05). 그러나 타우린을 첨가한 HT은 HO보다 유의적으로 높았다(P<0.05). 육계 간에서 hsp70 발현은 HO가 CO와 HT보다 유의적으로 높았으나(P<0.05), CO와 HT는 유의적인 차이가 없었다. In vitro 실험에서 고온 및 타우린은 21일령 육계 간의 총 단백질 합성률에 영향을 미치지 않았다. 따라서 타우린 섭취가 in vivo 육계의 성장에서 고온 스트레스를 완화시키지만, 생체 내의 단백질 합성에 직접적인 영향을 미치지 않는 것을 보이며, 이러한 결과는 타우린이 다양한 생리학적 기전을 통해 단백질 turnover 대사에 간접적으로 영향을 미칠 수 있다는 것으로 사료된다.

• 동아시아식생활학회지
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• 제17권1호
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• pp.1-10
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• 2007

The effects of mulberry-leaf powder Tofu(MPT) on anthropometric measurements, including bone mineral density(BMD) in the right carpus, biochemical bone turnover markers, serum levels of lipids and macrominerals, were investigated in 30 smoking male adults who lived in Choongnam were given MPT(100 g/day) for 4 weeks. The average ages, number of smoked cigarettes and packyear were 22.38 years, 15.12/day and 3.54 years, respectively. The nutrient contents per 100 g MPT were 86.10 kcal energy, 8.98 g protein, 0.53 mg fiber, 211.33 mg Ca and 1.59 g fat. Anthropometric measurements, including dietary intake using the 24-hours recall method, carpal BMD using DEXA, serum levels of protein, albumin and glucose, lipid profiles (cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol) with Al(atherosclerosis index), HTR, CRF, LHBt, some biomarkers of BMD(serum alkaline phosphatase activity, osteocalcin, urinary DPD), and serum macrominerals(Ca, Ca/P ratio, Mg) and Pb were analyzed before and after consumption of MPT. After MPT consumption, dietary intakes of plant protein, total Ca and plant Ca increased significantly, but there were no significant differences in anthropometric measurements, BMD with bone metabolism markers, serum levels of protein, albumin or glucose, lipid profiles with AI, HTR, LHR and CRF.