Journal of Genetics and Genomics

New Understandings on Folliculogenesis/Oogenesis Regulation in Mouse as Revealed by Conditional Knockout

Meng-Wen Hu, Zhen-Bo Wang, Heide Schatten, Qing-Yuan Sun

2012, 39(2): 61-68. doi: 10.1016/j.jgg.2012.01.004

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Abstract:
In comparison to conventional knockout technology and in vitro research methods, conditional gene knockout has remarkable advantages. In the past decade, especially during the past five years, conditional knockout approaches have been used to study the regulation of folliculogenesis, follicle growth, oocyte maturation and other major reproductive events. In this review, we summarize the recent findings about folliculogenesis/oogenesis regulation, including the functions of four signaling cascades or glycoprotein domains that have been extensively studied by conditional gene deletion. Several other still fragmented areas of related work are introduced which are awaiting clarification. We have also discussed the future potential of this technology in clarifying gene functions in reproductive biology.

Functional Analysis of Slow Myosin Heavy Chain 1 and Myomesin-3 in Sarcomere Organization in Zebrafish Embryonic Slow Muscles

Jin Xu, Jie Gao, Junling Li, Liangyi Xue, Karl J. Clark, Stephen C. Ekker, Shao Jun Du

2012, 39(2): 69-80. doi: 10.1016/j.jgg.2012.01.005

Abstract (72) HTML PDF (0)

Abstract:
Myofibrillogenesis, the process of sarcomere formation, requires close interactions of sarcomeric proteins and various components of sarcomere structures. The myosin thick filaments and M-lines are two key components of the sarcomere. It has been suggested that myomesin proteins of M-lines interact with myosin and titin proteins and keep the thick and titin filaments in order. However, the function of myomesin in myofibrillogenesis and sarcomere organization remained largely enigmatic. No knockout or knockdown animal models have been reported to elucidate the role of myomesin in sarcomere organizationin vivo. In this study, by using the gene-specific knockdown approach in zebrafish embryos, we carried out a loss-of-function analysis of myomesin-3 and slow myosin heavy chain 1 (smyhc1) expressed specifically in slow muscles. We demonstrated that knockdown of smyhc1 abolished the sarcomeric localization of myomesin-3 in slow muscles. In contrast, loss of myomesin-3 had no effect on the sarcomeric organization of thick and thin filaments as well as M- and Z-line structures. Together, these studies indicate that myosin thick filaments are required for M-line organization and M-line localization of myomesin-3. In contrast, myomesin-3 is dispensable for sarcomere organization in slow muscles.

Arabidopsis AtVPS15 Plays Essential Roles in Pollen Germination Possibly by Interacting with AtVPS34

Wei-Ying Wang, Li Zhang, Shufan Xing, Zhiqiang Ma, Jingjing Liu, Hongya Gu, Genji Qin, Li-Jia Qu

2012, 39(2): 81-92. doi: 10.1016/j.jgg.2012.01.002

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Abstract:
VPS15 protein is a component of the phosphatidylinositol 3-kinase complex which plays a pivotal role in the development of yeast and mammalian cells. The knowledge about the function of its homologue in plants remains limited. Here we report that AtVPS15, a homologue of yeast VPS15p in Arabidopsis, plays an essential role in pollen germination. Homozygous T-DNA insertion mutants of AtVPS15 could not be obtained from the progenies of self-pollinated heterozygous mutants. Reciprocal crosses between atvps15 mutants and wild-type Arabidopsis revealed that the T-DNA insertion was not able to be transmitted by male gametophytes. DAPI staining, Alexander's stain and scanning electron microscopic analysis showed that atvps15 heterozygous plants produced pollen grains that were morphologically indistinguishable from wild-type pollen, whereas in vitro germination experiments revealed that germination of the pollen grains was defective. GUS staining analysis of transgenic plants expressing the GUS reporter gene driven by the AtVPS15 promoter showed that AtVPS15 was mainly expressed in pollen grains. Finally, DUALmembrane yeast two-hybrid analysis demonstrated that AtVPS15 might interact directly with AtVPS34. These results suggest that AtVPS15 is very important for pollen germination, possibly through modulation of the activity of PI3-kinase.

Identification of a Ubiquitin-Binding Structure in the S-Locus F-Box Protein Controlling S-RNase-Based Self-Incompatibility

Guang Chen, Bin Zhang, Lijing Liu, Qun Li, Yu'e Zhang, Qi Xie, Yongbiao Xue

2012, 39(2): 93-102. doi: 10.1016/j.jgg.2012.01.001

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Abstract:
In flowering plants, self-incompatibility (SI) serves as an important intraspecific reproductive barrier to promote outbreeding. In species from the Solanaceae, Plantaginaceae and Rosaceae, S-RNase and SLF (S-locus F-box) proteins have been shown to control the female and male specificity of SI, respectively. However, little is known about structure features of the SLF protein apart from its conserved F-box domain. Here we show that the SLF C-terminal region possesses a novel ubiquitin-binding domain (UBD) structure conserved among the SLF protein family. By using an ex vivo system of Nicotiana benthamiana, we found that the UBD mediates the SLF protein turnover by the ubiquitin–proteasome pathway. Furthermore, we detected that the SLF protein was directly involved in S-RNase degradation. Taken together, our results provide a novel insight into the SLF structure and highlight a potential role of SLF protein stability and degradation in S-RNase-based self-incompatibility.

Molecular Cytogenetic Characterization of Wheat–Thinopyrum elongatum Addition, Substitution and Translocation Lines with a Novel Source of Resistance to Wheat Fusarium Head Blight

Shulan Fu, Zhenling Lv, Bao Qi, Xiang Guo, Jun Li, Bao Liu, Fangpu Han

2012, 39(2): 103-110. doi: 10.1016/j.jgg.2011.11.008

Abstract (64) HTML PDF (2)

Abstract:
Thinopyrum elongatum (2n=2x=14, EE), a wild relative of wheat, has been suggested as a potentially novel source of resistance to several major wheat diseases including Fusarium Head Blight (FHB). In this study, a series of wheat (cv. Chinese Spring, CS) substitution and ditelosomic lines, including Th. elongatum additions, were assessed for Type II resistance to FHB. Results indicated that the lines containing chromosome 7E of Th. elongatum gave a high level of resistance to FHB, wherein the infection did not spread beyond the inoculated floret. Furthermore, it was determined that the novel resistance gene(s) of 7E was located on the short-arm (7ES) based on sharp difference in FHB resistance between the two 7E ditelosomic lines for each arm. On the other hand, Th. elongatum chromosomes 5E and 6E likely contain gene(s) for susceptibility to FHB because the disease spreads rapidly within the inoculated spikes of these lines. Genomic in situ hybridization (GISH) analysis revealed that the alien chromosomes in the addition and substitution lines were intact, and the lines did not contain discernible genomic aberrations. GISH and multicolor-GISH analyses were further performed on three translocation lines that also showed high levels of resistance to FHB. Lines TA3499 and TA3695 were shown to contain one pair of wheat–Th. elongatum translocated chromosomes involving fragments of 7D plus a segment of the 7E, while line TA3493 was found to contain one pair of wheat–Th. elongatum translocated chromosomes involving the D- and A-genome chromosomes of wheat. Thus, this study has established that the short-arm of chromosome 7E of Th. elongatum harbors gene(s) highly resistant to the spreading of FHB, and chromatin of 7E introgressed into wheat chromosomes largely retained the resistance, implicating the feasibility of using these lines as novel material for breeding FHB-resistant wheat cultivars.

2012 Vol. 39, No. 2