Production of Transgenic Mice by Type-A Spermatogonia-Mediated Gene Transfer

Type-A spermatogonia first appear at between 3-7 d postnatally in mice and are the only immortalized diploid cells that reproduce in adulthood in these animals. In our current study, we explored the feasibility of producing stable transgenic mice using these cells. Enhanced pEGFP-N1 plasmids were suspended in ExGen500 transfection reagent and injected at different angles into the testes of 7-d-old male ICR mice. The resulting type-A spermatogonia-mediated gene transfer （TASMGT） mice were then mated with normal females at different stages of sexual maturity （6, 12, and 24 wk）. The integration and expression of the introduced EGFP gene was evaluated in the F1 transgenic offspring by PCR and Southern blotting analysis. The foreign gene integration rates for a low-dose group （15 μL gene suspension injected into each testis） and a high-dose group （30 μL suspensions injected） at the three stages of female sexual maturity tested were 11.76% （2/17）, 14.29% （3/21）, and 11.11% （2/18）, and 5% （1/20）, 5.56% （1/18）, and 0 （0/17）, respectively. The average integration rates for these two dose groups were 12.5% （7/56） and 3.64% （2/55）, respectively, which was a significant difference （P0.05）. Semi-quantitative RT-PCR analysis further showed that the introduced GFP gene was expressed in 3/9 integration mice. In addition, GFP expression was observed in the sperm cells from the TASMGT mice, and also in the embryos and F2 pups from the F1 generation transgenic mice. Hence, although the foreign gene integration rate for TASMGT is not high and the transgenic offspring show as yet unexplained defects, our results indicate that this method is a potentially feasible and reproducible new approach to creating transgenic mice.

PLZF的克隆及其对犏牛未分化精原细胞的增殖作用

【目的】犏牛作为牦牛与黄牛的种间杂交产物,具有优良的生产性能,但其杂种优势的进一步应用却受限于犏牛雄性不育。通过克隆犏牛PLZF,明确其在犏牛和牦牛睾丸组织和未分化精原细胞中的差异表达,并进一步揭示过表达该基因对犏牛未分化精原细胞活性的影响。为阐明犏牛生精停滞的作用机制提供理论基础。【方法】以24月龄公麦洼牦牛和F1代公犏牛为实验动物,通过RT-PCR法克隆得到了犏牛PLZF的CDS序列,并进行了生物信息学分析;通过RT-qPCR法分析PLZF在犏牛和牦牛睾丸组织中的差异表达;采用同源重组的方法构建了PLZF的表达载体,并利用RT-qPCR检测了PLZF过表达效率及其下游靶基因的表达;通过PDT、CCK-8、EdU和免疫荧光检测了过表达PLZF对犏牛未分化精原细胞增殖活性的影响。【结果】克隆获得了犏牛PLZF的CDS区,并通过生物信息学分析发现该基因编码的蛋白序列不包含跨膜结构域和信号肽序列,其三级结构以α螺旋和无规卷曲为主。系统进化树分析表明犏牛PLZF与黄牛PLZF的亲缘关系更近。三级结构预测发现,虽然犏牛、牦牛和黄牛的PLZF蛋白三级结构高度相似,但牦牛PLZF蛋白在531—540位氨基酸处与犏牛和黄牛有较大差异。RT-qPCR发现,PLZF在犏牛睾丸组织和未分化精原细胞中的表达均显著低于牦牛(P<0.05),而在犏牛未分化精原细胞中过表达PLZF后,该基因的表达上调了13.8倍(P<0.01),且能显著增加犏牛未分化精原细胞的增殖活性(P<0.05),表明PLZF表达下调影响了犏牛未分化精原细胞增殖活性。此外,过表达PLZF后,犏牛未分化精原细胞中与增殖相关的基因(Etv5、Bcl6b、Pcna和c-fos)全部显著上调(P<0.05),与分化相关的基因(Stra8、Kit、Dmrt1和Sohlh2)全部显著下调(P<0.05),表明PLZF通过上调增殖相关基因、下调分化相关基因的表达促进犏牛未分化精原细胞增殖。【结论】PLZF在犏牛未分化精原细胞中表达异常降低了犏牛未分化精原细胞增殖活性,导致其数量减少,影响了犏牛的精子发生。本试验为进一步阐明犏牛生精停滞的作用机制提供了理论基础,并为解决犏牛雄性不育问题提供了新的思路。

三氯异氰尿酸通过诱导氧化应激和铁死亡抑制精原细胞增殖

目的探索三氯异氰尿酸(TCCA)对小鼠睾丸精原细胞GC-1氧化应激和DNA甲基化的影响。方法以TCCA 0(细胞对照),97,194和387μmol·L^(-1)处理GC-1细胞24 h;CCK-8法检测细胞存活率;Hoechst 33342染色检测各组细胞形态和凋亡率;流式法检测细胞周期;实时荧光定量PCR(RT-qPCR)检测细胞凋亡相关基因Bax和Fas、氧化应激相关基因线粒体超氧化物歧化酶(SOD2)、铁死亡相关基因谷胱甘肽过氧化酶4(GPX4)、核因子红细胞2相关因子2(Nrf2)、溶质载体家族7成员11(SLC7A11)、二氢乳清酸脱氢酶(DHODH)、DNA甲基化转移酶3A(DNMT3A)和DNA甲基转移酶3L(DNMT3L)mRNA表达水平;Griess法测定GC-1细胞一氧化氮(NO)含量,比色法测定丙二醛(MDA)水平;DCFH-DA荧光探针法测定GC-1细胞活性氧(ROS)水平,DNTB比色法测定还原型谷胱甘肽(GSH)含量,WST-8法测定还原型辅酶Ⅱ(NADPH)含量。结果与细胞对照组相比,TCCA 194和387μmol·L^(-1)组细胞存活率降低(P<0.01),出现细胞核固缩及核碎裂,细胞凋亡率显著增加(P<0.01),细胞被阻滞在G2/M期(P<0.05);TCCA 387μmol·L^(-1)组细胞NO和MDA含量增加(P<0.01),ROS水平升高(P<0.01),GSH和NADPH含量降低(P<0.01),SOD2,GPX4,Nrf2,SLC7A11和DHODH mRNA表达减少(P<0.05,P<0.01);Bax,Fas,DNMT3L和DNMT3A mRNA表达增加(P<0.05,P<0.01)。结论TCCA可降低GC-1细胞存活率,抑制细胞增殖,引起细胞凋亡。其机制可能与其破坏抗氧化系统、增强氧化应激、诱导铁死亡及干扰GC-1细胞甲基化有关。

Type-A半群的表示

给出了Type-A半群的表示,将文献[1]中著名的Vagner表示定理推广到Abandant半群中.证明了如果S是一个半群,则存在一个集合X及S到PJ(X)的单同态.

一种在体标记小鼠精原细胞新生蛋白合成的方法

目的 哺乳动物精子发生是一种由一系列生精细胞组成的连续细胞增殖和分化并最终产生精子的过程。然而,生精细胞的蛋白稳态分析仍缺乏有效手段。本研究的目的是探索一种在体标记并检测生精细胞新生蛋白合成的方法。方法 利用氨基酰tRNAs结构类似物——嘌呤霉素(Puromycin,Puro)以65 mg/kg小鼠体质量的剂量腹腔注射小鼠,1.5 h后,处死小鼠,分离两侧睾丸,其中一侧睾丸用于总蛋白提取,另一侧睾丸用于石蜡切片制备,随后利用Puro特异性抗体分别通过Western blot和免疫荧光检测样品中Puro的含量及定位。结果 Western blot结果显示Puro能够标记总体新生蛋白合成情况;免疫荧光共定位显示Puro在小鼠睾丸中特异性标记的是精原细胞。结论 Puro能够用于小鼠精原细胞新生蛋白质的在体标记,并可通过相应免疫学技术定量分析新生蛋白合成水平。

Downregulation of Col lal induces differentiation in mouse spermatogonia

Col la I （one of the subunit of collagen type I） is a collagen, which belongs to a family of extracellular matrix （ECM） proteins that play an important role in cellular proliferation and differentiation. However, the role of Col lal in spermatogenesis, especially in the control of proliferation and differentiation of spermatogonial stem cells （SSCs）, remains unknown. In this study, we explored effects of downregulation of Collal on differentiation and proliferation of mouse spermatogonia. Loss-of-function study revealed that Oct4 and Plzf, markers of SSC self-renewal, were significantly decreased, whereas the expression of c-kit and haprin, hallmarks of SSC differentiation, was enhanced after Col la I knockdown. Cell cycle analyses indicated that two-thirds of spermatogonia were arrested in S phase after Collal knockdown. In vivo experiments, DNA injection and electroporation of the testes showed that spermatogonia self-renewal ability was impaired remarkably with the loss-of-function of Collal. Our data suggest that silencing of Collal can suppress spermatogonia self-renewal and promote spermatogonia differentiation.

Gene expression dynamics during the gonocyte to spermatogonia transition and spermatogenesis in the domestic yak

Background:Spermatogenesis is a cellular differentiation process that includes three major events:mitosis of spermatogonia,meiosis of spermatocytes and spermiogenesis.Steady-state spermatogenesis relies on functions of spermatogonial stem cells(SSCs).Establishing and maintaining a foundational SSC pool is essential for continued spermatogenesis in mammals.Currently,our knowledge about SSC and spermatogenesis is severely limited in domestic animals.Results:In the present study,we examined transcriptomes of testes from domestic yaks at four different stages(3,5,8 and 24 months of age)and attempted to identify genes that are associated with key developmental events of spermatogenesis.Histological analyses showed that the most advanced germ cells within seminiferous tubules of testes from 3,5,8 and 24 months old yaks were gonocytes,spermatogonia,spermatocytes and elongated spermatids,respectively.RNA-sequencing(RNA-seq)analyses revealed that 11904,4381 and 2459 genes were differentially expressed during the gonocyte to spermatogonia transition,the mitosis to meiosis transition and the meiosis to post-meiosis transition.Further analyses identified a list of candidate genes than may regulate these important cellular processes.CXCR4,a previously identified SSC niche factor in mouse,was one of the up-regulated genes in the 5 months old yak testis.Results of immunohistochemical staining confirmed that CXCR4 was exclusively expressed in gonocytes and a subpopulation of spermatogonia in the yak testis.Conclusions:Together,these findings demonstrated histological changes of postnatal testis development in the domestic yak.During development of spermatogonial lineage,meiotic and haploid germ cells are supported by dynamic transcriptional regulation of gene expression.Our transcriptomic analyses provided a list of candidate genes that potentially play crucial roles in directing the establishment of SSC and spermatogenesis in yak.

17beta-estradiol stimulates proliferation of spermatogonia in experimental cryptorchid mice

Aim： To investigate whether estrogen stimulates the proliferation of spermatogonia or induces spermatogenesis in cryptorchid mice. Methods： Mice were surgically rendered cryptorchid, then treated with different doses of 17β- estradiol （E2） s.c. once a day. Mice were killed at sexual maturity （45 days of age）, and histological analysis and inununofluorescence were performed. Serum follicle stimulating hormone （FSH）, estradiol, testosterone and luteinizing hormone （LH） were measured. Results： Low doses of E2 had no notable effect on spermatogonia, but at higher doses, E2 stimulated the proliferation of spermatogonia. Conclusion： E2 has a dose-related mitogenic effect on spermatogonia.

Genome-wide comparative analysis of type-A Arabidopsis response regulator genes by overexpression studies reveals their diverse roles and regulatory mechanisms in cytokinin signaling

Cytokinin is a critical growth regulator for various aspects of plant growth and development. In Arabidopsis, cytokinin signaling is mediated by a two-component system-based phosphorelay that transmits a signal from the receptors, through histidine phosphotransfer proteins, to the downstream response regulators （ARRs）. Of these ARRs, type-A ARR genes, whose transcription can be rapidly induced by cytokinin, act as negative regulators of eytokinin signaling. However, because of functional redundancy, the function of type-A ARR genes in plant growth and development is not well understood by analyzing loss-of-function mutants. In this study, we performed a comparative functional study on all ten type-A ARR genes by analyzing transgenic plants overexpressing these ARR genes fused to a MYC epitope tag. Overexpression of ARR genes results in a variety of cytokinin-associated phenotypes. Notably, overexpression of different ARR transgenes causes diverse phenotypes, even between phylogenetically closely-related gene pairs, such as within the ARR3-ARR4 and ARR5-ARR6 pairs. We found that the accumulation of a subset of ARR proteins （ARR3, ARR5, ARR7, ARR16 and ARR17; possibly ARR8 and ARR15） is increased by MG132, a specific proteasomal inhibitor, indicating that stability of these proteins is regulated by proteasomal degradation. Moreover, similar to that of previously characterized ARR5, ARR6 and ARR7, stability of ARR16 and ARR17, possibly including ARR8 and ARR15, is regulated by cytokinin. These results suggest that type-A ARR proteins are regulated by a combinatorial mechanism involving both the cytokinin and proteasome pathways, thereby executing distinctive functions in plant growth and development.

Sertoli cell and spermatogonial development in pigs

Background:Spermatogenesis is an intricate developmental process during which undifferentiated spermatogonia,containing spermatogonial stem cells(SSCs),undergo self-renewal and differentiation to generate eventually mature spermatozoa.Spermatogenesis occurs in seminiferous tubules within the testis,and the seminiferous tubules harbor Sertoli and germ cells.Sertoli cells are an essential somatic cell type within the microenvironment that support and steer male germ cell development,whereas spermatogonia are the primitive male germ cells at the onset of spermatogenesis.While the developmental progression of Sertoli cells and spermatogonia has been well established in mice,much less is known in other mammalian species including pigs.Results:To acquire knowledge of Sertoli cell and spermatogonial development in pigs,here we collected as many as nine ages of Duroc porcine testes from the neonate to sexual maturity,i.e.,testes from 7-,30-,50-,70-,90-,110-,130-,150-and 210-day-old boars,and performed histological and immunohistochemical analyses on testis sections.We first examined the development of spermatogenic cells and seminiferous tubules in porcine testes.Then,by immunofluorescence staining for marker proteins(AMH,SOX9,DBA,UCHL1,VASA,KIT,Ki67 and/or PCNA),we delved into the proliferative activity and development of Sertoli cells and of spermatogonial subtypes(pro-,undifferentiated and differentiating spermatogonia).Besides,by immunostaining forβ-catenin and ZO-1,we studied the establishment of the blood-testis barrier in porcine testes.Conclusions:In this longitudinal study,we have systematically investigated the elaborate Sertoli cell and spermatogonial developmental patterns in pigs from the neonate to sexual maturity that have so far remained largely unknown.The findings not only extend the knowledge about spermatogenesis and testicular development in pigs,but also lay the theoretical groundwork for porcine breeding and rearing.

Expression profile of cholecystokinin type-A receptor in gallbladder cancer and gallstone disease

BACKGROUND:Regulatory peptide receptors have attracted the interest of oncologists as a new promising approach for cancer pathology,imaging and therapy.Although cholecystokinin (CCK) is a potent modulator of gallbladder contractility and plays a potential role in pancreatic carcinogenesis through CCK type-A receptor (CCKAR),its role in gallbladder cancer (GBC) is still unknown and immunohistochemical detection of CCKAR in the gallbladder has not yet been reported.This novel case-control study aimed to investigate the expression profile of CCKAR in GBC and gallstone disease (GSD).METHODS:This study included 162 samples of gallbladder:94 from GBC and 68 from GSD.Expression of CCKAR was analyzed by immunohistochemistry and immunoblotting.The results were statistically correlated with disease history including age,sex,presence of gallstone,stage and differentiation.RESULTS:CCKAR was positive in 30/68 (44.1%) of GSD and 72/94 (76.6%) of GBC samples.Fifty-one of the 72 (70.8%) CCKAR-positive GBC samples showed over-expression.Interestingly,consistent results also appeared in the immunoblotting study.CONCLUSIONS:CCKAR expression was significantly increased in GBC compared to GSD.Moreover,CCKAR expression was associated with the degree of tumor differentiation,i.e.,less expression in poorly-differentiated tumors.Thus,it has future prognostic and therapeutic implications in the management of GBC.

Anti-inflammatory and anti-arthritic activity of type-A procyanidine polyphenols from bark of Cinnamomum zeylanicum in rats

Type-A procyanidine polyphenols(TAPP)are reported to have immunomodulatory and anti-inflammatory potential in vitro.The objective of present work is to evaluate potential of TAPP extracted from Cinnamon(Cinnamomum zeylanicum)bark in animal models of inflammation and rheumatoid arthritis in rats.Carrageenan-induced rat paw edema(CPE)and adjuvant induced established arthritis(AIA),in rats were used as the experimental models for inflammation and arthritis respectively.Analgesic activity was evaluated in Randall–Selitto assay in AIA rats.TAPP showed significant anti-inflammatory effect at dose of 4,8 and 25 mg/kg,p.o.but not at 2 mg/kg,p.o.dose in CPE model.The dose of 8 mg/kg,p.o.was selected for the evaluation of anti-arthritic activity in AIA model.TAPP(8 mg/kg,p.o.,daily from day-12 to day-21)treatment in established arthritic rats showed significant reversal of changes induced in AIA with respect to body weight drop(cachexia),ankle diameter,arthritic score,serum C-reactive protein(CRP)levels.Moreover,TAPP was found to be non-ulcerogenic as compared to AIA control rats.However,TAPP did not show analgesic effect on AIA-induced pain as seen in Randall–Selitto assay.In conclusion,TAPP showed disease-modifying potential in animal models of inflammation and arthritis in rats.©2013 Beijing Academy of Food Sciences.Production and hosting by Elsevier B.V.All rights reserved.

Isolation of Subtype Spermatogonia in Juvenile Rats

The present study was aimed at finding an effective method to isolate and purify the subtype of type A spermatogonial stem cells （SSCs） in juvenile rats. Testes from 9-days-old rats were used to isolate germ cells by using two-step enzymatic digestion. The expression of c-kit in the testes of the rats was immunohistochemically detected. After isolation, cell suspension was enriched further by discontinuous density gradient centrifugation. Then type A1-A4 spermatogonia was isolated from the purified spermatogonia with c-kit as the marker by using fluorescence-activated cell sorting （FACS）. Electron microscopy was used to observe their ultrastructure. Finally, highly purified and viable subtype of SSCs was obtained. Cells separation with discontinuous density gradient centrifugation significantly increased the concentration of c-kit positive cells [（18.65±1.69）% after the centrifugation versus （3.16±0.84）% before the centrifugation, P〈0.01]. Furthermore, the recovery and viability were also high [（65.9±1.24）% and （85.6±1.14）%]. It is concluded that FACS with c-kit as the marker in combination with discontinuous density gradient centrifugation can well enrich type A1-A4 spermatogonia from the testes of 9-days-old rats.

A numerical study of generation and propagation of type-a and type-b internal solitary waves in the northern South China Sea

Numerical simulations based on a high-resolution three-dimensional MIT general circulation model(MITgcm)using realistic topography and tidal forcing are conducted to investigate the generation and propagation of the so-called type-a waves(large-amplitude rank-ordered wave packets)and type-b waves(isolated wave packets)in the northern South China Sea.At first,we summarized and analyzed the generation and propagation characteristics of these waves.Then,energy budget at the Luzon Strait is calculated.Energy generation has three local maxima every day,of which the largest one corresponds to the emergence of the type-a wave.Energy flux at the west boundary of the Luzon Strait shows two local maxima each day.The larger one is consistent with the generation of the type-a wave and the smaller one is in correspondence with the generation of the type-b wave.Sensitivity experiments are designed to explore the role of the east and west ridge of the Luzon Strait on the generation and propagation of the type-a and type-b waves.It is found that the east ridge is indispensable on the generation of the type-a wave while the west ridge has little contribution.The west ridge diminishes the type-a waves'amplitude but hardly changes their propagation speed.The type-b waves also come from perturbation signals which originate from the east ridge and are enhanced in amplitude and reduced in propagation speed by the west ridge.

Ionizing Radiation-Induced RPL23a Reduction Regulates Apoptosis via RPL11-MDM2-p53 Pathway in Mouse Spermatogonia

Objective The expression patterns of ribosomal large subunit protein 23 a(RPL23 a)in mouse testes and GC-1 cells were analyzed to investigate the potential relationship between RPL23 a expression and spermatogonia apoptosis upon exposure to X-ray.Methods Male mice and GC-1 cells were irradiated with X-ray,terminal dUTP nick end-labelling(TUNEL)was performed to detect apoptotic spermatogonia in vivo.Apoptotic rate and cell cycle phase of GC-1 cells were analyzed with flow cytometry.Protein interactions were detected by Immunoprecipitation and protein localization as studied by immunofluorescence.Immunoblotting and real-time PCR were applied to analyze to protein and gene expression.Results Ionizing radiation(IR)increased spermatogonia apoptosis,the expression of RPL11,MDM2 and p53,and decreased RPL23 a expression in mice spermatogonia in vivo and in vitro.RPL23 a knockdown weakened the interaction between RPL23 a and RPL11,leading to p53 accumulation.Moreover,knockdown and IR decreased RPL23 a that induces spermatogonia apoptosis via RPL23 a-RPL11-MDM2-p53 pathway in GC-1 cells.Conclusion These results suggested that IR reduced RPL23 a expression,leading to weakened the RPL23 a-RPL11 interactions,which may have activated p53,resulting in spermatogonia apoptosis.These results provide insights into environmental and clinical risks of radiotherapy following exposure to IR in male fertility.The graphical abstract was available in the web of www.besjournal.com.

Production of functional sperm from in vitro-cultured premeiotic spermatogonia in a marine fish

In vitro production of functional gametes can revolutionize reproduction by reducing generation intervals and accelerating genetic breeding in aquaculture,especially in fish with relatively long generations.Nevertheless,functional sperm production from in vitro-cultured spermatogonia remains a challenge in most aquaculture fish.In this study,we isolated and characterized premeiotic spermatogonia from marine four-eyed sleepers(Bostrychus sinensis),which are prone to ovotesticular or sterile testicular development,and induced the differentiation of the spermatogonia into flagellated sperm in a three-dimensional(3D)culture system.Artificial insemination indicated that the in vitro-derived sperm were capable of fertilizing mature oocytes to develop into normal larvae.Furthermore,melatonin significantly promoted spermatogonia proliferation and differentiation through the ERK1/2 signaling pathway,and thus increased the efficiency in functional sperm production.The 3D culture system and resulting functional sperm hold great promise for improving the genetic breeding of aquaculture fish.

FGFs/FGFRs及其介导信号通路基因的异常表达影响犏牛未分化精原细胞增殖活性

旨在研究FGFs(fibroblast growth factors)/FGFRs(fibroblast growth factor receptors)及其介导的Ras和MAPK信号通路基因在牦牛和犏牛未分化精原细胞的差异表达,以探讨犏牛生精停滞的原因。本研究采集健康的24月龄3头公麦洼牦牛和3头F1代公犏牛的睾丸组织,分为牦牛和犏牛两个样品组,每组3个生物学重复。采用HE染色检测牦牛和犏牛精子发生的差异;采用细胞群体倍增时间、CCK-8和EDU染色检测牦牛和犏牛未分化精原细胞增殖能力的差异;采用荧光定量PCR检测6种FGF家族成员、3种FGFR、FGFs/FGFRs介导的Ras和MAPK信号通路基因在牦牛和犏牛未分化精原细胞中的差异表达。与牦牛相比,犏牛生精小管发育异常,生殖细胞类型单一,未分化精原细胞增殖活性显著低于牦牛(P<0.05)。FGF2、FGF4、FGF5、FGF8、FGF9和FGF21在犏牛睾丸组织及FGFs受体FGFR1、FGFR2和FGFR3在犏牛未分化精原细胞的表达都显著低于牦牛(P<0.01)。FGFs/FGFRs介导Ras信号通路基因中,除HRas和ARaf以外,其余基因(Raf1、BRaf、MEK1和ERK)都是在犏牛未分化精原细胞中以更低的水平表达(P<0.01)。FGFs/FGFRs介导MAPK信号通路基因中,p38、MEKK3、MEKK6和ASK1也是在犏牛未分化精原细胞中低表达(P<0.01)。受Ras通路调控的与细胞增殖相关的基因中,只有SHISA6、ID4在犏牛未分化精原细胞中高表达(P<0.01),其余基因(TAF4B、Etv4、GFRα1和Ret)都是在牦牛未分化精原细胞中表达量高(P<0.01)。受Ras和MAPK通路共同调控的与细胞增殖相关的基因中,ETV5和BCL6B都是在牦牛未分化精原细胞中高表达(P<0.01)。受Ras通路调控的与细胞分化相关的基因中,除PIWIL4外,SOX3、NGN3和Stra8都在牦牛未分化精原细胞中高表达(P<0.01)。因此FGFs/FGFRs及其介导的Ras和MAPK通路基因在犏牛未分化精原细胞中的异常表达,降低了未分化精原细胞增殖活性,导致了犏牛没有足够数量的未分化精原细胞进入分化阶段。这可能是犏牛生精停滞的重要原因之一。

Usefulness of Botulinum Toxin Type-A in the Treatment of Chronic Sixth Nerve Palsy

Purpose: The purpose of the study was to evaluate the efficacy of botulinum toxin type A (BTX-A) injection in patients with acquired VI nerve palsy. Methods: Twenty-eight patients (16 F and 12 M), mean age 36.4 +/-- 17.8 DS;range 10 - 69 years with acquired VI nerve palsy, have been treated with BTX-A injection into the ipsilateral medial rectus, at least 6 months after onset. At 6 months follow up, a paresis and a paralysis, were respectively diagnosed if the affected eye could be actively abducted or not, across the mid-line;a simple horizontal rectus muscle procedure was performed for the paresis whilst for the paralysis, both a horizontal and vertical muscle transportation procedure were required. Results: A gradual physiological recovery of the lateral rectus muscle was observed in 9 (32%) patients (GROUP I) and surgical treatment was therefore unnecessary;the remaining 19 cases (68%), of which 5 paresis (GROUP II) and 14 paralysis (GROUP III) underwent surgery and within 1 year were all restored to orthotropia. Conclusion: Botulinum toxin type-A (BTX-A) injection is an invaluable tool in the differential diagnosis between paresis versus paralysis of the VIth nerve, allowing the correct choice of surgical procedure.

The Effect of Variations in Ionic Conductance Values on the Suppression of Repetitive Spiking in a Mathematical Model of Type-A Medial Vestibular Nucleus Neurons

A previous study has proposed a mathematical model of type-A medial vestibular nucleus neurons (mVNn). This model is described by a system of nonlinear ordinary differential equations, which is based on the Hodgkin-Huxley formalism. The type-A mVNn model contains several ionic conductances, such as the sodium conductance, calcium conductance, delayed-rectifier potassium conductance, transient potassium conductance, and calcium-dependent potassium conductance. The previous study revealed that spontaneous repetitive spiking in the type-A mVNn model can be suppressed by hyperpolarizing stimulation. However, how this suppression is affected by the ionic conductances has not been clarified in the previous study. The present study performed numerical simulation analysis of the type-A mVNn model to clarify how variations in the different ionic conductance values affect the suppression of repetitive spiking. The present study revealed that the threshold for the transition from a repetitive spiking state to a quiescent state is differentially sensitive to variations in the ionic conductances among the different types of ionic conductance.

甜味剂乙酰磺胺酸钾的致突变性评价

目的:评价甜味剂乙酰磺胺酸钾的致突变性。方法:细菌回复突变试验(Ames试验)计数各组回复突变菌落数,小鼠精原细胞染色体畸变试验观察各组染色体畸变类型并计算畸变率,小鼠骨髓红细胞微核试验计数各组红细胞微核发生率。结果:Ames试验显示,加或不加S9时,受试物各剂量组、溶剂对照组与空白对照组比较,两次检测各菌株的回复突变数均小于空白对照组2倍;小鼠精原细胞染色体畸变试验显示,受试物各剂量组精原细胞染色体畸变率与对照组比较差异无统计学意义(P>0.05);小鼠骨髓红细胞微核试验显示,受试物各剂量组微核细胞率与对照组比较差异无统计学意义(P>0.05)。结论:乙酰磺胺酸钾未见明显的致突变性。