Journal of Genetics and Genomics

Gene Duplication and the Evolution of Plant MADS-box Transcription Factors

Chiara A. Airoldi, Brendan Davies

2012, 39(4): 157-165. doi: 10.1016/j.jgg.2012.02.008

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Abstract:
Since the first MADS-box transcription factor genes were implicated in the establishment of floral organ identity in a couple of model plants, the size and scope of this gene family has begun to be appreciated in a much wider range of species. Over the course of millions of years the number of MADS-box genes in plants has increased to the point that the Arabidopsis genome contains more than 100. The understanding gained from studying the evolution, regulation and function of multiple MADS-box genes in an increasing set of species, makes this large plant transcription factor gene family an ideal subject to study the processes that lead to an increase in gene number and the selective birth, death and repurposing of its component members. Here we will use examples taken from the MADS-box gene family to review what is known about the factors that influence the loss and retention of genes duplicated in different ways and examine the varied fates of the retained genes and their associated biological outcomes.

V-ATPase, ScNhx1p and Yeast Vacuole Fusion

Quan-Sheng Qiu

2012, 39(4): 167-171. doi: 10.1016/j.jgg.2012.02.001

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Abstract:
Membrane fusion is the last step in trafficking pathways during which membrane vesicles fuse with target organelles to deliver cargos. It is a central cellular reaction that plays important roles in signal transduction, protein sorting and subcellular compartmentation. Recent progress in understanding the roles of ion transporters in vacuole fusion in yeast is summarized in this article. It is becoming increasingly evident that the vacuolar proton pump V-ATPase and vacuolar Na⁺/H⁺ antiporter ScNhx1p are key components of the vacuole fusion machinery in yeast. Yeast ScNhx1p regulates vacuole fusion by controlling the luminal pH. V-ATPases serve a dual role in vacuolar integrity in which they regulate both vacuole fusion and fission reactions in yeast. Fission defects are epistatic to fusion defects. Vacuole fission depends on the proton translocation activity of the V-ATPase; by contrast, the fusion reaction does not need the transport activity but requires the physical presence of the proton pump. V₀, the membrane-integral sector of the V-ATPase, forms trans-complexes between the opposing vacuoles in the terminal phase of vacuole fusion where the V₀ trans-complexes build a continuous proteolipid channel at the fusion site to mediate the bilayer fusion.

Imipramine Inhibits Adipogenic Differentiation in Both 3T3-L1 Preadipocytes and Mouse Marrow Stromal Cells

Haifang Li, Chi-chun Fong, Yao Chen, Guoping Cai, Mengsu Yang

2012, 39(4): 173-180. doi: 10.1016/j.jgg.2012.03.003

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Abstract:
Imipramine (IM) has been widely used clinically for the treatment of mental disorders. Its actions on tissues or organs other than the nervous system also need to be understood for its proper clinical use. In this study, the effects of IM on adipogenic differentiation in both 3T3-L1 preadipocytes and mouse marrow stromal cells (MSCs) were investigated. The results showed that fewer adipocytic cells were developed from 3T3-L1 preadipocytes in the presence of 0.001 to 1μmol/L of IM as compared to control. Similar inhibitory effect was also observed in mouse MSCs. The decrease in the formation of adipocytes was accompanied with significant down-regulation at mRNA expression of the early adipogenic transcription factor, peroxisome proliferator-activated receptor γ2 (PPARγ2). Western blot analysis further revealed that the protein expression of PPARγ2 was reduced markedly in cells treated with IM at concentrations of 0.01, 0.1 and 1μmol/L, suggesting that the suppression on PPARγ2 was involved in IM's inhibition on MSCs adipogenesis. Moreover, IM at the above concentrations could stimulate the mRNA expression of β2-adrenergic receptor (AR) and β3-AR, which implicated that the effect of IM on adipogenic differentiation was partially mediated by β-ARs. Our results demonstrated for the first time that the conventional antidepressive imipramine exerts accompanied inhibitory effect on adipocyte formation, which may have possible clinical implications.

Identification of Sheep Ovary Genes Potentially Associated with Off-season Reproduction

Lei Chen, Ka Liu, Zongsheng Zhao, Hugh T. Blair, Peng Zhang, Daquan Li, Runlin Z. Ma

2012, 39(4): 181-190. doi: 10.1016/j.jgg.2012.03.002

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Abstract:
Off-season reproduction is a favorable economic trait for sheep industry. Hu sheep, an indigenous Chinese sheep breed, demonstrates a higher productivity of lambs and displays year-around oestrous behavior under proper nutrition and environment. The genetic basis behind these traits, however, is not well understood. In order to identify genes associated with the off-season reproduction, we constructed a suppression subtractive hybridization (SSH) cDNA library using pooled ovary mRNAs of 6 oestrous Hu females as a tester and the pooled ovary mRNAs of 6 non-oestrous Chinese Merino females as a driver. A total of 382 resulting positive clones were obtained after the SSH. We identified 114 differentially up-regulated genes in oestrous Hu sheep by using subsequent screening and DNA sequencing, of which 8 were previously known, 93 were reported for the first time in sheep, and 13 were novel with no significant homology to any sequence in the DNA databases. Functions of the genes identified are related to cell division, signal transduction, structure, metabolism, or cell defense. To validate the results of SSH, 6 genes (Ntrk2, Ppap2b, Htra1, Nid1, Serpine2 and Foxola) were selected for conformational analysis using quantitative real-time PCR (qRT-PCR), and two of them (Htral and Foxo1a) were verified by Northern blot. All of the 6 genes were differentially up-regulated in the ovary of oestrous Hu. It is obvious that off-season reproduction is a complex trait involving multiple genes in multiple organs. This study helps to provide a foundation for the final identification of functional genes involved in the sheep ovary.

Prader–Willi Syndrome: 16-Year Experience in Hong Kong

Ivan F.M. Lo, Ho Ming Luk, Tony M.F. Tong, Kent K.S. Lai, Daniel H.C. Chan, Albert C.F. Lam, David K.H. Chan, Edgar W.L. Hau, Connie O.Y. Fung, Stephen T.S. Lam

2012, 39(4): 191-194. doi: 10.1016/j.jgg.2012.02.005

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Abstract:

2012 Vol. 39, No. 4