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Background

The DAZ family genes boule, daz and dazl encode RNA binding proteins essential for fertility of diverse animals including human. dazl has bisexual expression in both mitotic and meiotic germ cells, whereas daz has male premeiotic expression, and boule is largely a unisexual meiotic regulator. Although boule has been proposed as the ancestor for dazl/daz by gene duplication, it has been identified only in invertebrates and mammals. It has, however, remained unclear when and how the DAZ family has evolved in vertebrates.

Methodology and Principal Findings

This study was aimed at identifying and characterizing the DAZ family genes in fish as the basal vertebrate. We show that boule and dazl coexist in medaka and stickleback. Similar to the medaka dazl (Odazl), the medaka boule (Obol) is maternally supplied and segregates with primordial germ cells. Surprisingly, Obol is expressed in adult germ cells at pre-meiotic and meiotic stages of spermatogenesis and oogenesis. However, the maximal meiotic Obol expression in spermatocytes contrasts with the predominant pre-meiotic Odazl expression in spermatogonia, and the diffuse cytoplasmic Obol distribution in early oocytes contrasts with the Odazl concentration in the Balbinani''s body.

Conclusions

The identification of fish boule and dazl genes provides direct evidence for the early gene duplication during vertebrate evolution. Our finding that Obol exhibits bisexual expression in both embryonic and adult germ cells considerably extends the diversity of boule expression patterns and offers a new insight into the evolutions of DAZ family members, expression patterns and functions in animal fertility.  相似文献   

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Teng H  Cai W  Zhou L  Zhang J  Liu Q  Wang Y  Dai W  Zhao M  Sun Z 《PloS one》2010,5(10):e13342

Background

Ionotropic glutamate receptors in the central nervous system play a major role in numerous brain functions including learning and memory in many vertebrate species. NR2 subunits have been regarded as rate-limiting molecules in controlling the optimal N-methyl-D-aspartate (NMDA) receptor''s coincidence-detection property and subsequent learning and memory function across multi-species. However, its evolutionary mode among vertebrate species remains unclear.

Results

With extensive analysis of phylogeny, exon structure, protein domain, paralogon and synteny, we demonstrated that two-round genome duplication generated quartet GRIN2 genes and the third-round fish-specific genome duplication generated extra copies of fish GRIN2 genes. In addition, in-depth investigation has enabled the identification of three novel genes, GRIN2C_Gg, GRIN2D-1_Ol and GRIN2D-2_Tr in the chicken, medaka and fugu genome, respectively. Furthermore, we showed functional divergence of NR2 genes mostly occurred at the first-round duplication, amino acid residues located at the N-terminal Lig_chan domain were responsible for type I functional divergence between these GRIN2 subfamilies and purifying selection has been the prominent natural pressure operating on these diversified GRIN2 genes.

Conclusion and Significance

These findings provide intriguing subjects for testing the 2R and 3R hypothesis and we expect it could provide new insights into the underlying evolution mechanisms of cognition in vertebrate.  相似文献   

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Background

De novo glycerolipid synthesis begins with the acylation of glycerol-3 phosphate catalyzed by glycerol-3-phosphate acyltransferase (GPAT). In mammals, at least four GPAT isoforms have been described, differing in their cell and tissue locations and sensitivity to sulfhydryl reagents. In this work we show that mitochondrial GPAT2 overexpression in CHO-K1 cells increased TAG content and both GPAT and AGPAT activities 2-fold with arachidonoyl-CoA as a substrate, indicating specificity for this fatty acid.

Methods and Results

Incubation of GPAT2-transfected CHO-K1 cells with [1-14C]arachidonate for 3 h increased incorporation of [14C]arachidonate into TAG by 40%. Consistently, arachidonic acid was present in the TAG fraction of cells that overexpressed GPAT2, but not in control cells, corroborating GPAT2''s role in synthesizing TAG that is rich in arachidonic acid. In rat and mouse testis, Gpat2 mRNA was expressed only in primary spermatocytes; the protein was also detected in late stages of spermatogenesis. During rat sexual maturation, both the testicular TAG content and the arachidonic acid content in the TAG fraction peaked at 30 d, matching the highest expression of Gpat2 mRNA and protein.

Conclusions

These results strongly suggest that GPAT2 expression is linked to arachidonoyl-CoA incorporation into TAG in spermatogenic germ cells.  相似文献   

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Background

The Chinese mitten crab Eriocheir sinensis belongs to the Class Crustacea, Decapoda, Brachyura. The spermatozoon of this species is of aflagellated type, it has a spherical acrosome surrounded by the cup-shaped nucleus, which are unique to brachyurans. For the past several decades, studies on the spermatogenesis of the mitten crab mainly focus on the morphology. Compared with the extensive study of molecular mechanism of spermatogenesis in mammals, relatively less information is available in crustacean species. Myosin Va, a member of Class V myosin, has been implicated in acrosome biogenesis and vesicle transport during spermatogenesis in mammals. In the present study we demonstrate the expression and cellular localization of myosin Va during spermatogenesis in E. sinensis.

Methodology/Principal Findings

Western blot demonstrated that myosin Va is expressed during spermatogenesis. Immunocytochemical and ultrastructural analyses showed that myosin Va mainly localizes in the cytoplasm in spermatocytes. At the early stage of spermiogenesis, myosin Va binds to the endoplasmic reticulum vesicle (EV) and proacrosomal granule (PG). Subsequently, myosin Va localizes within the proacrosomal vesicle (PV) formed by PG and EV fusion and locates in the membrane complex (MC) at the mid spermatid stage. At the late spermatid stage, myosin Va is associated with the shaping nucleus and mitochondria. In mature spermatozoon, myosin Va predominates in acrosomal tubule (AT) and nucleus.

Conclusions/Significance

Our study demonstrates that myosin Va may be involved in acrosome biogenesis and nuclear morphogenesis during spermatogenesis in E. sinensis. Considering the distribution and molecular characteristics of myosin Va, we also propose a hypothesis of AT formation in this species. It is the first time to uncover the role of myosin Va in crustacean spermatogenesis.  相似文献   

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