Journal of Genetics and Genomics

Small but influential: the role of microRNAs on gene regulatory network and 3′UTR evolution

Rui Zhang, Bing Su

2009, 36(1): 1-6. doi: 10.1016/S1673-8527(09)60001-1

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Abstract:
MicroRNAs (miRNAs) are endogenous ∼22 nucleotide noncoding RNAs that regulate the expression of complementary messenger RNAs (mRNAs). Thousands of miRNA genes have been found in diverse species, and many of them are highly conserved. With the miRNA roles identified in nearly all aspects of biological processes, evidence is mounting that miRNAs could represent a new layer of regulatory network, and their regulatory effect might be much more pervasive than previously suspected. Here we focus on the post-transcriptional level gene regulation of miRNAs in animals and review how the miRNAs act to sustain and shape up the expression profiles of specific cell types; how the miRNAs integrate into the existing gene regulatory networks; and how the miRNAs influence the evolution of 3′UTR of mammalian mRNAs.

Molecular characterization and expression analysis of a chicken-type lysozyme gene from housefly (Musca domestica)

Qian Ren, Xiaofan Zhao, Jinxing Wang

2009, 36(1): 7-16. doi: 10.1016/S1673-8527(09)60002-3

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Abstract:
Lysozymes can hydrolyze bacteria and play an important role in animal digestion and innate immunity. The cDNA of a chicken-type lysozyme gene (Mdlys) was cloned from housefly (Musca domestica). The 484 bp full-length cDNA contains a 426 bp open reading frame (ORF) that encodes MdLys of 141 amino acids. Phylogenetic analysis indicated that the MdLys was similar to chicken-type lysozymes. Spatio-temporal expression of Mdlys was analyzed by RT-PCR. The Mdlys transcript can be detected in both midgut and fat body and was expressed at a relatively lower level at the embryo stage. Mdlys mRNA was upregulated 2 h post bacterial challenge, maintained for 2 to 6 h, and slightly declined from 12 to 24 h post-injection. Western blot analysis showed that MdLys was highly expressed in midgut and was also detected in the hemolymph and fat body. MdLys expression was slightly increased in midgut after challenging with Escherichia coli or Staphylococcus aureus. Its expression was also slightly increased in the fat body after challenging with S. aureus, but no obvious change occurred after E. coli challenge. MdLys expression in the hemolymph was not affected by bacterial challenge. In the developmental stages, MdLys expression levels had no obvious change from the first instar to the pupae stage. There was also no variation under 24 h starvation stress. Recombinant MdLys displayed inhibitory activity against Gram-negative and Gram-positive bacteria. Together, these results suggest that MdLys may play an important role in the innate immunity of houseflies.

Transgenic expression of MYB15 confers enhanced sensitivity to abscisic acid and improved drought tolerance in Arabidopsis thaliana

Zhenhua Ding, Shiming Li, Xueli An, Xin Liu, Huanju Qin, Daowen Wang

2009, 36(1): 17-29. doi: 10.1016/S1673-8527(09)60003-5

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Abstract:
Abiotic stresses cause serious crop losses. Knowledge on genes functioning in plant responses to adverse growth conditions is essential for developing stress tolerant crops. Here we report that transgenic expression of MYB15, encoding a R2R3 MYB transcription factor in Arabidopsis thaliana, conferred hypersensitivity to exogenous abscisic acid (ABA) and improved tolerance to drought and salt stresses. The promoter of MYB15 was active in not only vegetative and reproductive organs but also the guard cells of stomata. Its transcript level was substantially upregulated by ABA, drought or salt treatments. Compared with wild type (WT) control, MYB15 overexpression lines were hypersensitive to ABA in germination assays, more susceptible to ABA-elicited inhibition of root elongation, and more sensitive to ABA-induced stomatal closure. In line with the above findings, the transcript levels of ABA biosynthesis (ABA1, ABA2), signaling (ABI3), and responsive genes (AtADH1, RD22, RD29B, AtEM6) were generally higher in MYB15 overexpression seedlings than in WT controls after treatment with ABA. MYB15 overexpression lines displayed improved survival and reduced water loss rates than WT control under water deficiency conditions. These overexpression lines also displayed higher tolerance to NaCl stress. Collectively, our data suggest that overexpression of MYB15 improves drought and salt tolerance in Arabidopsis possibly by enhancing the expression levels of the genes involved in ABA biosynthesis and signaling, and those encoding the stress-protective proteins.

Expression of a rice OsARGOS gene in Arabidopsis promotes cell division and expansion and increases organ size

Bao Wang, Yalin Sang, Jian Song, Xin-Qi Gao, Xiansheng Zhang

2009, 36(1): 31-40. doi: 10.1016/S1673-8527(09)60004-7

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Abstract:
The ARGOS gene in Arabidopsis plays a key role in controlling plant organ size. To determine the function of it's ortholog in rice, a putative ARGOS orthologous gene from rice tissues was isolated and designated as OsARGOS. This gene has only one copy in the rice genome. OsARGOS transcripts were detected in most of rice tissues, particularly in the young tissues, and its expression was induced in rice seedlings by the application of either auxin or cytokinin. Arabidopsis plants expressing OsARGOS led to larger organs, such as leaves and siliques, compared with wild-type plants. Interestingly, the root growth was also enhanced in these transgenic Arabidopsis plants. Therefore, the biomass of the transgenic plants was significantly increased. Further analysis revealed that, different from theARGOS and ARGOS-LIKE genes in Arabidopsis, the OsARGOS gene enlarged organ by an increase in both cell number and cell size. In addition, the transcript levels of several organ size-associated genes regulating either cell division or cell growth were upregulated in the transgenic Arabidopsis plants. We also transferred the OsARGOS gene to rice, but the transgenic plants did not show any changes in organ size compared with the control plants. It is likely that the function of OsARGOS in organ size control depends on other size regulators in rice. The expression of OsARGOS in Arabidopsis may activate the signaling pathways that control cell proliferation and cell expansion during the course of plant growth and development. Since the expression of OsARGOS causes organ enlargement, the potential application of this gene through genetic engineering may significantly improve the production of biomass in agricultural practice.

Index selection on seed traits under direct, cytoplasmic and maternal effects in multiple environments

Wenying Zhang, Haiming Xu, Jun Zhu

2009, 36(1): 41-49. doi: 10.1016/S1673-8527(09)60005-9

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Abstract:
Crop seeds are important sources of protein, oil, and carbohydrates for food, animal feeds, and industrial products. Recently, much attention has been paid to quality and functional properties of crop seeds. However, seed traits possess some distinct genetic characteristics in comparison with plant traits, which increase the difficulty of genetically improving these traits. In this study, diallel analysis for seed models with genotype by environment interaction (GE) effect was applied to estimate the variance-covariance components of seed traits. Mixed linear model approaches were used to estimate the genetic covariances between pair-wise seed and plant traits. The breeding values (BV) were divided into two categories for the seed models. The first category of BV was defined as the combination of direct additive, cytoplasmic, and maternal additive effects, which should be utilized for selecting stable cultivars over multi-environments. The three genetic effects, together with their GE interaction, were included in the second category of BV for selecting special lines to be grown in specific ecosystems. Accordingly, two types of selection indices for seed traits, i.e., general selection index and interaction selection index, were developed and constructed on the first and the second category BV, respectively. These proposed selection indices can be applied to solve the difficult task of simultaneously improving multiple seed traits in various environments. Data of crop seeds with regard to four seed traits and four yield traits based on the modified diallel crosses in Upland cotton (Gossypium hirsutum L.) were used as an example for demonstrating the proposed methodology.

Polymorphic Alu insertions and their associations with MHC class I alleles and haplotypes in Han and Jinuo populations in Yunnan Province, southwest of China

Yufeng Yao, Li Shi, Lei Shi, Keqin Lin, Yufen Tao, Liang Yu, Hao Sun, Xiaoqin Huang, Yanhan Li, Jiayou Chu

2009, 36(1): 51-58. doi: 10.1016/S1673-8527(09)60006-0

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Abstract:
The associations of polymorphic Alu insertions (POALINs) with major histocompatibility complex (MHC) class I genes enable us to better identify origins and evolution of MHC class I region haplotypes in different populations. For further studying origins and evolution of MHC class I region haplotypes in Han and Jinuo populations in Yunnan Province, we investigated frequencies of five POALINs, their associations with HLA-A and -B, the three-loci POALINs haplotype frequencies and HLA/POALIN four-loci haplotype frequencies within the alpha block of MHC class I region. We found that a strong positive association between AluHG and HLA-A*02 is in Jinuo, but not in Yunnan Han. These results suggest that MHC class I region haplotypes of the two studied populations might derive from different progenitor haplotypes and MHC I-POALINs are informative genetic markers for investigating origins and evolution of MHC class I region haplotypes in different populations.

Instructions for authors

2009, 36(1): 59-62. doi: 10.1016/S1673-8527(09)60007-2

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Abstract:

2009 Vol. 36, No. 1