Reelin regulates male mouse reproductive capacity via the sertoli cells

Reelin plays important roles in brain development. Reeler mutant mice that lack the protein reelin (RELN) suffer from cell type- and region-dependent changes in their neocortical layers, and adult reeler mutant mice have dilated seminiferous tubules. Meanwhile, the mechanism by which Reelin regulates the spermatogenic cell development in mice and their reproductive abilities remains unclear. In the present study, we used reeler mutant mice to investigate the effects of Reelin on reproduction in mice. The results indicated variations in sex hormone expression among the reeler mice, indicating that they produce few offspring and their spermatogenic cells are irregularly developed. Moreover, glial cell line-derived neurotrophic factor (GDNF)/GDNF family receptor alpha 1, Ras/extracellular regulated protein kinases (ERK), and promyelocytic leukemia zinc finger (PLZF)/chemokine (C-X-C motif) receptor 4 (CXCR4) serve as potential regulatory pathways that respond to the changes in sertoli cells and the niche of male germ cells. Our findings provided valuable insights into the role of reeler in the reproductive abilities of male mice and development of their spermatogonia stem cells.     

LEAFY COTYLEDON 2 activation is sufficient to trigger the accumulation of oil and seed specific mRNAs in Arabidopsis leaves

LEAFY COTYLEDON 2 (LEC2) is a key regulator of seed maturation in Arabidopsis. To unravel some of its complex pleiotropic functions, analyses were performed with transgenic plants expressing an inducible LEC2:GR protein. The chimeric protein is functional and can complement lec2 mutation. Interestingly, the induction of LEC2 leads to the accumulation of storage oil in leaves. In addition, short-term induction and use of translation inhibitors allowed to demonstrate that LEC2 can directly trigger the accumulation of seed specific mRNAs. Consistent with these results, the expression of three other major seed regulators namely, LEC1, FUS3, and ABI3 were also induced by LEC2 activation.     

五指山猪近交系精原干细胞体外培养研究

对不同发育阶段五指山小型猪(WZSP)近交系的睾丸组织,采用不同的消化和培养方法进行了一系列的探索、研究。实验显示培养SSCs的最佳时限为仔猪出生后1~20日龄;对不同日龄仔猪采用不同消化方法,以DMEM为基础培养液并添加不同成分,34℃,5%CO2培养箱中饱和湿度条件下培养,可获得较好的分离培养结果;原代SSCs在培养8d后,SSCs开始增殖,桑椹状的SSCs集落半悬浮隆突生长;SSCs集落AKP染色,细胞呈阳性反应;对SSCs细胞团在STO饲养层上进行传代培养,SSCs贴壁良好,培养4d左右大部分SSCs集落和单细胞消失;采用曲精细管组织贴壁培养法也同样获得桑椹状SSCs集落,细胞集落在培养5d后出现,半悬浮生长。此外,睾丸组织在4℃PBS液中存放24h后,仍可作为SSCs分离、培养的材料。结果表明本研究初步掌握了WZSP近交系精原干细胞体外分离、培养的技术方法,为其进一步深入研究提供了技术方法和操作依据。     

小熊猫精原干细胞的分选与培养

野生动物的保护手段主要包括就地保护、易地保护与离体保护。精原干细胞（SSCs）是雄性动物维持生殖能力的根本,既能通过自我更新产生新细胞,也能通过分化产生精子,在小熊猫（Ailurus fulgens）离体保护方面具有广阔的应用前景。动物睾丸中精原干细胞数量极少,分离纯化与体外培养对于其研究和应用至关重要。本研究选择整合素α6（ITGA6）蛋白作为精原干细胞分子标记,采用免疫磁珠分选（MACS）技术富集了3月龄小熊猫睾丸中的ITGA6阳性细胞。流式细胞术检测发现分选后ITGA6阳性细胞纯度可达74.27% ± 8.73%,显著高于分选前（32.60% ± 3.06%）。将分选后的细胞接种到层粘连蛋白包被的细胞培养板中,用含胶质细胞源性神经营养因子（GDNF）、表皮细胞生长因子（EGF）与成纤维细胞生长因子（bFGF）的培养基进行体外培养。培养10 d后,在显微镜下可观察到典型的精原干细胞集落,结合逆转录PCR（RT-PCR）和细胞免疫荧光染色发现这些细胞集落特异性表达精原干细胞分子标记蛋白ITGA6、早幼粒细胞白血病锌指蛋白（PLZF）和胸腺细胞分化抗原1（THY1）,同时也表达生殖细胞标记蛋白VASA和DAZL。本研究结果证实,ITGA6可作为小熊猫精原干细胞的分子标记用于细胞分选富集,同时初步建立的培养体系也为小熊猫精子发生机制与应用研究提供材料。     

Germ Cell Transplantation and Testis Tissue Xenografting in Mice

Germ cell transplantation was developed by Dr. Ralph Brinster and colleagues at the University of Pennsylvania in 1994^1,2. These ground-breaking studies showed that microinjection of germ cells from fertile donor mice into the seminiferous tubules of infertile recipient mice results in donor-derived spermatogenesis and sperm production by the recipient animal². The use of donor males carrying the bacterial β-galactosidase gene allowed identification of donor-derived spermatogenesis and transmission of the donor haplotype to the offspring by recipient animals¹. Surprisingly, after transplantation into the lumen of the seminiferous tubules, transplanted germ cells were able to move from the luminal compartment to the basement membrane where spermatogonia are located³. It is generally accepted that only SSCs are able to colonize the niche and re-establish spermatogenesis in the recipient testis. Therefore, germ cell transplantation provides a functional approach to study the stem cell niche in the testis and to characterize putative spermatogonial stem cells. To date, germ cell transplantation is used to elucidate basic stem cell biology, to produce transgenic animals through genetic manipulation of germ cells prior to transplantation^4,5, to study Sertoli cell-germ cell interaction^6,7, SSC homing and colonization^3,8, as well as SSC self-renewal and differentiation^9,10.Germ cell transplantation is also feasible in large species¹¹. In these, the main applications are preservation of fertility, dissemination of elite genetics in animal populations, and generation of transgenic animals as the study of spermatogenesis and SSC biology with this technique is logistically more difficult and expensive than in rodents. Transplantation of germ cells from large species into the seminiferous tubules of mice results in colonization of donor cells and spermatogonial expansion, but not in their full differentiation presumably due to incompatibility of the recipient somatic cell compartment with the germ cells from phylogenetically distant species¹². An alternative approach is transplantation of germ cells from large species together with their surrounding somatic compartment. We first reported in 2002, that small fragments of testis tissue from immature males transplanted under the dorsal skin of immunodeficient mice are able to survive and undergo full development with the production of fertilization competent sperm¹³. Since then testis tissue xenografting has been shown to be successful in many species and emerged as a valuable alternative to study testis development and spermatogenesis of large animals in mice¹⁴.     

大鼠精原干细胞的高效分离和纯化方法

精原干细胞是精子发生的基础,是永久分化成精子的克隆源,它既可以自我更新维持体内干细胞的数量,又可以增殖分化形成各阶段的生精细胞直至成熟精子。本文以22～25日龄Wistar-Iamichi大鼠为研究对象,利用两步酶消化法分离得到睾丸曲细精管细胞悬液,根据精原干细胞与曲细精管细胞悬液中体细胞(支持细胞及少量的管周细胞)及各级分化的生精细胞贴壁能力及对细胞外基质粘附力的不同,将大鼠精原干细胞进行纯化。经纯化后,5只大鼠的睾丸可以得到约3×10~5个精原干细胞,该精原干细胞在体外培养可形成克隆,并且该克隆可表达精原干细胞特异的标记基因GFRα1和CDH1。本文所介绍的高效分离和纯化大鼠精原干细胞的方法,操作简便,且得到的精原干细胞具有很高的活力和增殖能力,该方法为今后大鼠精原干细胞的长期培养及操作研究奠定了基础。     

New insights on the reparative cells in bone regeneration and repair

Bone possesses a remarkable repair capacity to regenerate completely without scar tissue formation. This unique characteristic, expressed during bone development, maintenance and injury (fracture) healing, is performed by the reparative cells including skeletal stem cells (SSCs) and their descendants. However, the identity and functional roles of SSCs remain controversial due to technological difficulties and the heterogeneity and plasticity of SSCs. Moreover, for many years, there has been a biased view that bone marrow is the main cell source for bone repair. Together, these limitations have greatly hampered our understanding of these important cell populations and their potential applications in the treatment of fractures and skeletal diseases. Here, we reanalyse and summarize current understanding of the reparative cells in bone regeneration and repair and outline recent progress in this area, with a particular emphasis on the temporal and spatial process of fracture healing, the sources of reparative cells, an updated definition of SSCs, and markers of skeletal stem/progenitor cells contributing to the repair of craniofacial and long bones, as well as the debate between SSCs and pericytes. Finally, we also discuss the existing problems, emerging novel technologies and future research directions in this field.