染色体展片法观察拟南芥雄性减数分裂过程中的染色体形态

减数分裂指DNA复制1次, 细胞核分裂2次, 产生染色体数目减半的单倍体配子, 是真核生物有性生殖所必需的环节。拟南芥(Arabidopsis thaliana)是分子遗传学研究的传统模式生物。近年来, 随着显微镜技术的快速发展, 利用细胞学方法观察拟南芥减数分裂过程中的染色体形态和同源染色体互作事件, 将有助于深入认识减数分裂的分子遗传机制。该文详细描述了染色体展片法观察拟南芥雄性减数分裂细胞中的染色体形态。     

The novel peptide NbPPI1 identified from Nicotiana benthamiana triggers immune responses and enhances resistance against Phytophthora pathogens

In plants, recognition of small secreted peptides, such as damage/danger‐associated molecular patterns (DAMPs), regulates diverse processes, including stress and immune responses. Here, we identified an SGPS (Ser‐Gly‐Pro‐Ser) motif‐containing peptide, Nicotiana tabacum NtPROPPI, and its two homologs in Nicotiana benthamiana, NbPROPPI1 and NbPROPPI2. Phytophthora parasitica infection and salicylic acid (SA) treatment induced NbPROPPI1/2 expression. Moreover, SignalP predicted that the 89‐amino acid NtPROPPI includes a 24‐amino acid N‐terminal signal peptide and NbPROPPI1/2‐GFP fusion proteins were mainly localized to the periplasm. Transient expression of NbPROPPI1/2 inhibited P. parasitica colonization, and NbPROPPI1/2 knockdown rendered plants more susceptible to P. parasitica. An eight‐amino‐acid segment in the NbPROPPI1 C‐terminus was essential for its immune function and a synthetic 20‐residue peptide, NbPPI1, derived from the C‐terminus of NbPROPPI1 provoked significant immune responses in N. benthamiana. These responses led to enhanced accumulation of reactive oxygen species, activation of mitogen‐activated protein kinases, and up‐regulation of the defense genes Flg22‐induced receptor‐like kinase (FRK) and WRKY DNA‐binding protein 33 (WRKY33). The NbPPI1‐induced defense responses require Brassinosteroid insensitive 1‐associated receptor kinase 1 (BAK1). These results suggest that NbPPI1 functions as a DAMP in N. benthamiana; this novel DAMP provides a potentially useful target for improving plant resistance to Pytophthora pathogens.     

钙盐及模拟干旱互作对大花套唇苣苔种子萌发和幼苗生长的影响

苦苣苔科原大花旋蒴苣苔(former Boea clarkeana Hemsl.)为我国特有的复苏植物,在最近的修订中被并入套唇苣苔属(Damrongia Kerr),更名为大花套唇苣苔[D. clarkeana(Hemsl.)C. Puglisi]。为了探究该植物对喀斯特特殊生境的适应机制,该文以大花套唇苣苔成熟种子为材料,通过观察钙盐和模拟干旱互作试验,研究了干旱和盐胁迫共同作用对其种子萌发和幼苗生长的影响。结果表明:钙盐及模拟干旱互作时,低浓度钙盐可减轻干旱对种子萌发和幼苗生长的抑制作用,且低程度的干旱与低浓度的钙盐相互作用时反而会促进种子萌发和幼苗生长; 低钙盐低干旱复合条件对大花套唇苣苔生长的促进作用体现了该物种对喀斯特地区保水性差的石灰岩土壤基质的专适性,避免了和其他植物直接生态位的竞争。     

Aluminum Trichloride Inhibited Osteoblastic Proliferation and Downregulated the Wnt/β-Catenin Pathway

Aluminum (Al) exposure inhibits bone formation. Osteoblastic proliferation promotes bone formation. Therefore, we inferred that Al may inhibit bone formation by the inhibition of osteoblastic proliferation. However, the effects and molecular mechanisms of Al on osteoblastic proliferation are still under investigation. Osteoblastic proliferation can be regulated by Wnt/β-catenin signaling pathway. To investigate the effects of Al on osteoblastic proliferation and whether Wnt/β-catenin signaling pathway is involved in it, osteoblasts from neonatal rats were cultured and exposed to 0, 0.4 mM (1/20 IC₅₀), 0.8 mM (1/10 IC₅₀), and 1.6 mM (1/5 IC₅₀) of aluminum trichloride (AlCl₃) for 24 h, respectively. The osteoblastic proliferation rates; Wnt3a, lipoprotein receptor-related protein 5 (LRP-5), T cell factor 1 (TCF-1), cyclin D1, and c-Myc messenger RNA (mRNA) expressions; and p-glycogen synthase kinase 3β (GSK3β), GSK3β, and β-catenin protein expressions indicated that AlCl₃ inhibited osteoblastic proliferation and downregulated Wnt/β-catenin signaling pathway. In addition, the AlCl₃ concentration was negatively correlated with osteoblastic proliferation rates and the mRNA expressions of Wnt3a, c-Myc, and cyclin D1, while the osteoblastic proliferation rates were positively correlated with mRNA expressions of Wnt3a, c-Myc, and cyclin D1. Taken together, these findings indicated that AlCl₃ inhibits osteoblastic proliferation may be associated with the inactivation of Wnt/β-catenin signaling pathway.     

Correlation analysis of RDM1 gene with immune infiltration and clinical prognosis of hepatocellular carcinoma

Purpose: Liver hepatocellular carcinoma (LIHC) is one of the most common primary malignant liver tumors worldwide. The RAD52 motif-containing protein 1 (RDM1) has been shown to play a role in mediating DNA damage repair and homologous recombination. The present study was designed to determine the expression of RDM1 and its prognostic value as well as its relationship with immune infiltration in LIHC patients.Methods: Oncomine and Tumor Immunoassay Resource were used to assess the expression of RDM1. PrognoScan and Kaplan–Meier bioinformatics database were used to analyze the impact of clinical influencing factors on prognosis. Finally, the Tumor Immune Assessment Resource (TIMER) and Gene Expression Analysis Interactive Analysis (GEPIA) databases were used to detect the correlation between the expression of RDM1 and expression of marker genes related to immune infiltration. Immunohistochemistry (IHC) method was used to detect the expression level of RDM1 in 90 cases of hepatocellular carcinoma and adjacent normal liver tissues.Results: RDM1 expression was up-regulated in most cancers. The expression of RDM1 was remarkably higher than that of the corresponding normal control genes in LIHC tissues. The increase in RDM1 messenger RNA (mRNA) expression was closely related to the decreases in overall survival (OS) and progression-free survival (PFS). Additionally, the increase in RDM1 mRNA expression was closely related to the infiltration levels of macrophages, CD8⁺ T cells and B cells and was positively correlated with a variety of immune markers in LIHC.Conclusion: The findings of the present study demonstrate that RDM1 is a potentially valuable prognostic biomarker that can help determine the progression of cancer and is associated with immune cell infiltration in LIHC.     

钟冠报春苣苔(苦苣苔科)的分类鉴定

原唇柱苣苔属(Chirita Buch.-Ham. ex D. Don)为一个人为界定的属, 2011年在分子系统学研究的基础上对该属及其近缘属开展了系统发育重建工作,其中绝大部分的原唇柱苣苔属唇柱苣苔组(Sect. Gibbosaccus C. B. Clark)的物种被并入了广义报春苣苔属(Primulina Hance)。然而,由于历史原因和早期经典分类学在研究方法上的局限性以及对现报春苣苔属部分物种的营养器官与生殖器官的认知不够,该属下一些物种的分类仍存在一些问题,亟待深入研究。比如,在对中国和越南分布的苦苣苔科植物开展研究的过程中,作者发现两个报春苣苔属的物种——广布于中国西南和华南直至中南半岛中部的钟冠报春苣苔[Primulina swinglei(Merr.)Mich. Möller & A. Weber]命名人和原被认为是中国与广西特有种的疏花报春苣苔[P. laxiflora(W. T. Wang)Yin. Z. Wang]之间的鉴定存在分类学问题,需要进一步厘清两者之间的关系。该文对这两个物种进行了形态比较,同时通过对这两种植物的原始描述对比、植物标本检查、栽培观察以及野外实地观察,确定疏花报春苣苔是钟冠报春苣苔的异名。此外,还明确了钟冠报春苣苔的后选指定模式标本。     

A Peptide Derived from the HIV-1 gp120 Coreceptor-Binding Region Promotes Formation of PAP248-286 Amyloid Fibrils to Enhance HIV-1 Infection

BackgroundSemen is a major vehicle for HIV transmission. Prostatic acid phosphatase (PAP) fragments, such as PAP248-286, in human semen can form amyloid fibrils to enhance HIV infection. Other endogenous or exogenous factors present during sexual intercourse have also been reported to promote the formation of seminal amyloid fibrils.

Methodology and Principal Findings

Here, we demonstrated that a synthetic 15-residue peptide derived from the HIV-1 gp120 coreceptor-binding region, designated enhancing peptide 2 (EP2), can rapidly self-assemble into nanofibers. These EP2-derivated nanofibers promptly accelerated the formation of semen amyloid fibrils by PAP248-286, as shown by Thioflavin T (ThT) and Congo red assays. The amyloid fibrils presented similar morphology, assessed via transmission electron microscopy (TEM), in the presence or absence of EP2. Circular dichroism (CD) spectroscopy revealed that EP2 accelerates PAP248-286 amyloid fibril formation by promoting the structural transition of PAP248-286 from a random coil into a cross-β-sheet. Newly formed semen amyloid fibrils effectively enhanced HIV-1 infection in TZM-bl cells and U87 cells by promoting the binding of HIV-1 virions to target cells.

Conclusions and Significance

Nanofibers composed of EP2 promote the formation of PAP248-286 amyloid fibrils and enhance HIV-1 infection.