Author Correction: Genetically encoded tags for direct synthesis of EM-visible gold nanoparticles in cells.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Genetically encoded tags for direct synthesis of EM-visible gold nanoparticles in cells.

Genetically encoded tags for single-molecule imaging in electron microscopy (EM) are long-awaited. Here, we report an approach for directly synthesizing EM-visible gold nanoparticles (AuNPs) on cysteine-rich tags for single-molecule visualization in cells. We first uncovered an auto-nucleation suppression mechanism that allows specific synthesis of AuNPs on isolated tags. Next, we exploited this mechanism to develop approaches for single-molecule detection of proteins in prokaryotic cells and achieved an unprecedented labeling efficiency. We then expanded it to more complicated eukaryotic cells and successfully detected the proteins targeted to various organelles, including the membranes of endoplasmic reticulum (ER) and nuclear envelope, ER lumen, nuclear pores, spindle pole bodies and mitochondrial matrices. We further implemented cysteine-rich tag-antibody fusion proteins as new immuno-EM probes. Thus, our approaches should allow biologists to address a wide range of biological questions at the single-molecule level in cellular ultrastructural contexts.

Effects of 17beta-estradiol on distribution of primordial germ cell migration in male chicks.

AIM: To assess whether exogenous estradiol has any effect on migration of primordial germ cells (PGCs) in the chick. METHODS: Fertilized eggs were treated with 17beta-estradiol (E(2)) (80 microg/egg) at stage X (day 0 of incubation), stages 8-10 (incubation 30 h) and 13-15 (incubation 55 h). Controls received vehicle (emulsion) only. Changes in PGC number were measured on different days according to developmental stages. RESULTS: In male right gonads, but not in female left gonads, at stages 28-30 (incubation 132 h) significant decreases in the mean number of PGCs aggregating were observed compared with the controls (P < 0.05) while the total PGC number in the right and left gonads at each stage did not change (P > 0.05). CONCLUSION: The present study provides evidence that E(2) has significant effects on the localization of PGCs in male right, but not female left, gonads of chicken embryos at stages 28-30, compared with controls.

Effects of 2,2',5,5'-tetrachlorobiphenyl (PCB52) on migration of chicken primordial germ cells.

Polychlorinated biphenyls cause developmental and physiological anomalies in the reproductive system. This study investigated the effects of 2,22,5,52-tetrachlorobiphenyl (PCB52), which can produce oestrogenic effects on the homeostasis of chicken primordial germ cells from the initial stage until completion of their settlement in the gonadal primordium. The blastoderm of chicken embryos was injected with 1 (1/4)L PCB52 (10 micromol/L) and oestradiol (100 micromol/L) before incubation, and the number of primordial germ cells was determined during their migration and development. The number of primordial germ cells in germinal crescents in PCB52-treated groups was slightly decreased (P = 0.068), but it was reduced significantly at stages 13-15 and 28-30 (P < 0.01, respectively) compared with controls. No obvious effects on primordial germ cell migration were observed with oestradiol treatments. The present results suggest that the influence of PCB52 on chicken primordial germ cell migration and proliferation may be via its toxic effect, not its oestrogen-mimicking effect, and provide information on the sensitivity of primordial germ cells to the direct action of PCB52.

[Textual research on circulation of the Ming edition of Li Heng's Xiu zhen fang (Pocket Formulary)].

Xiu zhen fang (Pocket Formulary) is a recipe book of the Ming Dynasty, inspired and managed by Zhu Su, compiled by Li Heng of liangyisuo (good physician house) in Zhou wangfu (Zhou's royal palace). The book was compiled and published twice during the reigns of the Hongwu and Yongle Emperors of the Ming Dynasty. Because of its high practicability, there were some editions in circulation, and the book was published several times only in the Ming Dynasty. At present, the earliest extanteditionwas the little character version of Yongle, and the version in the 4(th) year of Zhengde Emperor of the Ming Dynasty was a reprinting edition based on the Yongle edition, sharingthe same edition system. Most of the editions appeared after the reign of Zhengtong Emperor of the Ming Dynasty, titled by "kui ben (head version)" and "da quan (complete edition)" were the editionspublished in the local bookshops, which had rather distinct differences from the Yongle edition system not only in the its format but also in its contents.

Facile deposition of continuous gold shells on Tween-20 modified Fe3O4 superparticles.

A facile method to deposit continuous Au shells on Fe3O4 colloidal superparticles was developed by introducing Tween-20 as a surface modification agent to maintain the colloidal stability of the Fe3O4 superparticles and provide nucleation and growth sites for the Au shells. The Fe3O4-Au core-shell particles showed excellent chemical stability, superparamagnetic properties and efficient photothermal conversion performance under laser irradiation at 808 nm, and were expected to be a useful material for biodetection and cancer therapy.

Contribution of blastoderm cells to Japanese quail (Coturnix coturnix japonica)-Peking duck (Anas platyrhynchos) chimeras.

The purpose of this study was to produce quail-duck chimeras by transferring stage X blastoderm cells and to detect the distribution of donor cells in heterogeneous embryos using PCR. Four experimental groups were made by transferring different amounts of quail blastoderm cells into duck recipients. In early embryonic stages, donor cells labeled with PKH26 fluorescent dye were observed in the head, neural tube and gonads by fluorescent microscopy. A total of 194 duck recipient embryos were injected and 93 survived to hatch. The average hatching rate was 48% (93/194); the hatching rate showed a significant difference among all the groups (P < 0.05). Sixteen somatic chimeras were obtained, 10 of which had black feathers derived from the donor quail. The PCR results showed that donor cells were distributed in various tissues and organs of the phenotypic chimeras. This is the first report on producing Japanese quail-Peking duck chimeras by transferring quail blastoderm cells into the subgerminal cavity of the duck. This technique will provide a basis for the investigation of fertilization barriers in interspecies germline chimeras and will aid conservation of endangered wild birds.

Cloning and characterization of chicken SPATA4 gene and analysis of its specific expression.

The spermatogenesis associated 4 gene (SPATA4, previously named TSARG2) was first cloned from a mouse testis cDNA library and was reported to be a candidate apoptosis-related gene in male germ cells. In this study, we cloned and characterized the SPATA4 gene from chicken (Gallus gallus). Bioinformatics analysis shows that the chicken SPATA4 gene is located on chromosome 4, is made up of six exons, and contains an 860 bp open reading frame encoding a putative protein of 250 amino acids. Further analysis of the SPATA4 gene sequence indicates that it is highly conserved between avian and mammalian species. Multi-tissue RT-PCR results indicate that the chicken SPATA4 gene is specifically expressed in the testis. Moreover, according to multi-time RT-PCR results, the expression of chicken SPATA4 occurs in a development stage-dependent pattern, and is gradually upregulated during the developmental process in chicken testis. All of these results suggest that SPATA4 may play an important role in the chicken spermatogenesis process.