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Frontiers in Biology, 2014, Volume 9 Issue 3

已有 1922 次阅读 2014-7-15 15:57 |个人分类:Frontiers in Biology期刊进展|系统分类:论文交流

REVIEW

Appetite control: why we fail to stop eating even when we are full?
Kristen DAVIS,Young-Jai YOU
Front. Biol.. 2014, 9 (3): 169-174.   DOI: 10.1007/s11515-014-1309-z
PDF (289KB)

We often eat more than our body needs. We live in an environment where high calorie food is abundant and physical activities are limited. Living in this environment, maintaining healthy bodyweight becomes challenging and obesity becomes a social burden. Why do we continue to eat even after the metabolic needs are satisfied? Feeding is an ancient behavior essential to survive. Thus the mechanisms to regulate appetite, energy expenditure, and energy storage are well conserved throughout animals. Based on this conservation, we study why we fail to control appetite using a simple genetic model system C. elegans. We have discovered certain genetic components that when misregulated have animals eat more and store more fat. In this review we discuss how these genes work in the appetite control circuit to ultimately understand overall appetite control behavior. We will also briefly discuss how social influence affects feeding regardless of the metabolic status of an animal.



The dynamics of murine mammary stem/progenitor cells
Qiaoxiang DONG,Lu-Zhe SUN
Front. Biol.. 2014, 9 (3): 175-185.   DOI: 10.1007/s11515-014-1308-0
 PDF (710KB)

The stem/progenitor cells in the murine mammary gland are a highly dynamic population of cells that are responsible for ductal elongation in puberty, homeostasis maintenance in adult, and lobulo-alveolar genesis during pregnancy. In recent years understanding the epithelial cell hierarchy within the mammary gland is becoming particularly important as these different stem/progenitor cells were perceived to be the cells of origin for various subtypes of breast cancer. Although significant advances have been made in enrichment and isolation of stem/progenitor cells by combinations of antibodies against cell surface proteins together with flow cytometry, and in identification of stem/progenitor cells with multi-lineage differentiation and self-renewal using mammary fat pad reconstitution assay and in vivo genetic labeling technique, a clear understanding of how these different stem/progenitors are orchestrated in the mammary gland is still lacking. Here we discuss the different in vivo and in vitro methods currently available for stem/progenitor identification, their associated caveats, and a possible new hierarchy model to reconcile various putative stem/progenitor cell populations identified by different research groups.



Mesenchymal stem cells in progression and treatment of cancers
Qingguo ZHAO,Fei LIU
Front. Biol.. 2014, 9 (3): 186-194.   DOI: 10.1007/s11515-014-1306-2
PDF (353KB)

Mesenchymal stem or stromal cells (MSCs) from bone marrow or local tissues are recruited to stroma of almost all types of cancers during initiation and/or progression of cancer. The recruited MSCs and their derivative cancer-associated fibroblasts interact with cancer cells to promote stemness, invasion and metastasis of cancer cells. Targeting these cancer-recruited MSCs and/or the interaction between MSCs and cancer cells are promising strategies to improve cancer therapy. On the other hand, the unique tumor-homing capacity of MSCs makes them a promising vehicle to deliver various anti-cancer agents. This review summarized the recent advancement of our understanding on the interaction between MSCs and cancer cells, as well as the potential of MSCs for cancer therapy.


Col10a1 gene expression and chondrocyte hypertrophy during skeletal development and disease
Yaojuan LU,Longwei QIAO,Guanghua LEI,Ranim R. MIRA,Junxia GU,Qiping ZHENG
Front. Biol.. 2014, 9 (3): 195-204.   DOI: 10.1007/s11515-014-1310-6
 PDF (407KB)

The type X collagen gene, COL10A1, is specifically expressed by hypertrophic chondrocytes during endochondral ossification. Endochondral ossification is a well-coordinated process that involves a cartilage intermediate and leads to formation of most of the skeleton in vertebrates during skeletogenesis. Chondrocyte hypertrophy is a critical stage of endochondral ossification linking both bone and cartilage development. Given its specific association with chondrocyte hypertrophy, type X collagen plays essential roles in endochondral ossification. It was previously shown that transgenic mice with mutant type X collagen develop variable skeleton-hematopoietic abnormalities indicating defective endochondral ossification, while mutations and abnormal expression of human COL10A1 cause abnormal chondrocyte hypertrophy that has been seen in many skeletal disorders, including skeletal chondrodysplasia and osteoarthritis. In this review, we summarized the skeletal chondrodysplasia with COL10A1 gene mutation that shows growth plate defect. We also reviewed recent studies that correlate the type X collagen gene expression and chondrocyte hypertrophy with osteoarthritis. Due to its significant clinical relevance, the type X collagen gene regulation has been extensively studied over the past two decades. Here, we focus on recent progress characterizing the cis-enhancer elements and their binding factors that together confer hypertrophic chondrocyte-specific murine type X collagen gene (Col10a1) expression. Based on literature review and our own studies, we surmise that there are multiple factors that contribute to hypertrophic chondrocyte-specific Col10a1 expression. These factors include both transactivators (such as Runx2, MEF2C etc.) and repressors (such as AP1, NFATc1, Sox9 etc.), while other co-factors or epigenetic control of Col10a1 expression may not be excluded.



Role of calmodulin in neuronal Kv7/KCNQ potassium channels and epilepsy
Hee Jung CHUNG
Front. Biol.. 2014, 9 (3): 205-215.   DOI: 10.1007/s11515-014-1305-3
 PDF (615KB)

Neuronal Kv7/KCNQ channels are critical regulators of neuronal excitability since they potently suppress repetitive firing of action potentials. These voltage-dependent potassium channels are composed mostly of Kv7.2 / KCNQ2 and Kv7.3 / KCNQ3 subunits that show overlapping distribution throughout the brain and in the peripheral nervous system. They are also called ‘M-channels’ since their inhibition by muscarinic agonists leads to a profound increase in action potential firing. Consistent with their ability to suppress seizures and attenuate chronic inflammatory and neuropathic pain, mutations in the KCNQ2 and KCNQ3 genes are associated with benign familial neonatal convulsions, a dominantly-inherited epilepsy in infancy. Recently, de novo mutations in the KCNQ2 gene have been linked to early onset epileptic encephalopathy. Notably, some of these mutations are clustered in a region of the intracellular cytoplasmic tail of Kv7.2 that interacts with a ubiquitous calcium sensor, calmodulin. In this review, we highlight the recent advances in understanding the role of calmodulin in modulating physiological function of neuronal Kv7 channels including their biophysical properties, assembly, and trafficking. We also summarize recent studies that have investigated functional impact of epilepsy-associated mutations localized to the calmodulin binding domains of Kv7.2.



Neurotrophin signaling and visceral hypersensitivity
Li-Ya QIAO
Front. Biol.. 2014, 9 (3): 216-224.   DOI: 10.1007/s11515-014-1304-4
PDF (181KB)

Neurotrophin family are traditionally recognized for their nerve growth promoting function and are recently identified as crucial factors in regulating neuronal activity in the central and peripheral nervous systems. The family members including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) are reported to have distinct roles in the development and maintenance of sensory phenotypes in normal states and in the modulation of sensory activity in disease. This paper highlights receptor tyrosine kinase (Trk) -mediated signal transduction by which neurotrophins regulate neuronal activity in the visceral sensory reflex pathways with emphasis on the distinct roles of NGF and BDNF signaling in physiologic and pathophysiological processes. Viscero-visceral cross-organ sensitization exists widely in human diseases. The role of neurotrophins in mediating neural cross talk and interaction in primary afferent neurons in the dorsal root ganglia (DRG) and neurotrophin signal transduction in the context of cross-organ sensitization are also discussed.



TPP1 as a versatile player at the ends of chromosomes
Sijie ZHANG,Zhenhua LUO,Guang SHI,Dan LIU,Zhou SONGYANG,Junjiu HUANG
Front. Biol.. 2014, 9 (3): 225-233.   DOI: 10.1007/s11515-014-1307-1
PDF (454KB)

Telomeres, the ends of linear eukaryotic chromosomes, are tandem DNA repeats and capped by various telomeric proteins. These nucleoprotein complexes protect telomeres from DNA damage response (DDR), recombination, and end-to-end fusions, ensuring genome stability. The human telosome/shelterin complex is one of the best-studied telomere-associated protein complexes, made up of six core telomeric proteins TRF1, TRF2, TIN2, RAP1, POT1, and TPP1. TPP1, also known as adrenocortical dysplasia protein homolog (ACD), is a putative mammalian homolog of TEBP-β and belongs to the oligonucleotide binding (OB)-fold-containing protein family. Three functional domains have been identified within TPP1, the N-terminal OB fold, the POT1 binding recruitment domain (RD), and the carboxyl-terminal TIN2-interacting domain (TID). TPP1 can interact with both POT1 and TIN2 to maintain telomere structure, and mediate telomerase recruitment for telomere elongation. These features have indicated TPP1 play an essential role in telomere maintenance. Here, we will review important findings that highlight the functional significance of TPP1, with a focus on its interaction with other telosome components and the telomerase. We will also discuss potential implications in disease therapies.

RESEARCH ARTICLE

Proteomic analysis of differentially expressed proteins between Xiangyou 15 variety and the mutant M15
Zhen-Qian ZHANG,Gang XIAO,Rui-Yang LIU,Tai-Long TAN,Chun-Yun GUAN,Guo-Huai WANG,She-Yuan CHEN,Xian-Meng WU,Mei GUAN,Qin LI
Front. Biol.. 2014, 9 (3): 234-243.   DOI: 10.1007/s11515-014-1311-5
PDF (602KB)

A high oleic acid rapeseed material M15 (derived from Xiangyou 15 variety) has been received more attention for its significant effect for human health. And it has almost the same physiological characteristic with Xiangyou 15 variety. To find out the difference between high oleic acid rapeseed material and Xiangyou 15 seedling, a comparative proteomic approach based on 2-DE and mass spectrometry was adopted. A total of 277 protein spots showed a significant change in intensity by more than 2.0-fold from M15 compared with Xiangyou 15 variety. Among them, 48 spots that changed at least 3.0-fold were excised from gels and successfully identified by MALDI-TOF/TOF MS. The identified proteins involved in metabolism of carbohydrate and energy (75%), stress and defense (8.3%), photosynthesis (6.3%), protein metabolism (2.1%) and other functions (8.3%). Then real-time quantitative PCR (qPCR) analysis was used to verify the expression levels of differentially expressed proteins, but the results did well agree with the proteomic results. In this work, most of the proteins involved in metabolism of carbohydrate and energy have higher expression in M15, which may reveal M15 has higher metabolism ability. These results provided much information to understand the differences between high oleic acid rapeseed material and Xiangyou 15 variety, which will be useful to screen high oleic rapeseed materials in seedling period.


Fermentative production of dextran using Leuconostoc spp. isolated from fermented food products
C. SUBATHRA DEVI,Shantan REDDY,V. MOHANASRINIVASAN
Front. Biol.. 2014, 9 (3): 244-253.   DOI: 10.1007/s11515-014-1303-5
PDF (884KB)

Leuconostoc spp. (LS1and LI1) isolated from sauerkraut and idli batter was selected for dextran production. To enhance the yield of dextran, effects of various parameters such as sucrose concentration, pH, temperature, incubation and inoculum percentage were analyzed. The optimum sucrose concentration for the Leuconostoc spp. (LS1 and LI1) was found to be 15% and 25% respectively. Isolates produced maximum dextran after 20 h of incubation at 29°C and the optimum pH was found between 8 and 8.5. The inoculum concentration of 7.5% was more favorable for the production of dextran by Leuconostoc spp. (LS1 and LI1). The growth kinetic parameters were studied and compared for the strains LS1 and LI1. Mass production of dextran was carried out using a stirred tank batch reactor. FTIR analysis was done to determine the functional groups of dextran. sephadex is prepared by cross linking dextran using epichlorohydrin and the functional groups are determined by FTIR analysis.




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上一篇:Review--Structural biology of the macroautophagy machinery
下一篇:Frontiers in Biology Volume 9, issue 4

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