The effects of soil phosphorus on aboveground biomass are mediated by functional diversity in a tropical cloud forest

Plant and Soil - Soil phosphorus is a key driver of plant biodiversity and aboveground biomass (AGB) in tropical forests. A plant community’s ability to exploit such limiting resources may be...     

Selenium-Alleviated Hepatocyte Necrosis and DNA Damage in Cyclophosphamide-Treated Geese by Mitigating Oxidative Stress

Biological Trace Element Research - Selenium (Se) has been well recognized as an immune-enhancing agent with antioxidant and anti-tumor properties. The commonly used chemotherapy drug,...     

Variable Spontaneous Mutation and Loss of Heterozygosity among Heterozygous Genomes in Yeast

Mutation and recombination are the primary sources of genetic variation. To better understand the evolution of genetic variation, it is crucial to comprehensively investigate the processes involving mutation accumulation and recombination. In this study, we performed mutation accumulation experiments on four heterozygous diploid yeast species in the Saccharomycodaceae family to determine spontaneous mutation rates, mutation spectra, and losses of heterozygosity (LOH). We observed substantial variation in mutation rates and mutation spectra. We also observed high LOH rates (1.65–11.07×10⁻⁶ events per heterozygous site per cell division). Biases in spontaneous mutation and LOH together with selection ultimately shape the variable genome-wide nucleotide landscape in yeast species.     

LINC00205 modulates the expression of EPHX1 through the inhibition of miR-184 in hepatocellular carcinoma as a ceRNA

Several studies have shown that low expression of epoxide hydrolase 1 (EPHX1) is closely associated with varying human cancers, including hepatocellular carcinoma (HCC). This study aims to explore the potential mechanism of EPHX1 silencing and revealed a novel regulatory pathway in the pathogenesis of HCC. In this study, micro ribonucleic acid (miR)-184 was predicted and validated to be a regulator of EPHX1 through experiments, and its expression was negatively correlated with the messenger RNA (mRNA) levels of EPHX1 in primary tumors. Elevation of EPHX1 suppressed cell proliferation and migration as well as cell cycle progression, and induced apoptosis, while downregulation of miR-184 exhibited the opposite effect on cellular processes. Moreover, LINC00205 interacted with miR-184 and was markedly downregulated in tumors. The effects of the miR-184 inhibitor on cell proliferation, apoptosis, and migration were reversed in part by the transfection with LINC00205 small interfering RNAs. In addition, LINC00205 acted as a molecular sponge to positively regulate the mRNA and protein levels of EPHX1 via regulating miR-184. The tumorigenicity of HCC cells was enhanced by LINC00205 shRNA but diminished by overexpression of EPHX1 in vivo. Clinically, the EPHX1 expression in patients with HCC was markedly downregulated. Taken together, the results of this study suggest that as a competing endogenous RNA, LINC00205 may regulate EPHX1 by inhibiting miR-184 in the progression of HCC and that targeting the LINC00205/miR-184/EPHX1 axis may provide a treatment protocol for patients.     

小白链霉菌ε-聚赖氨酸降解酶生理功能分析

[目的] 研究小白链霉菌（Streptomyces albulus）中ε-聚赖氨酸降解酶（Pld）的分布特征和生理功能。[方法] 利用生物信息学手段对已报道的ε-聚赖氨酸（ε-PL）产生菌的Pld进行挖掘和分析,再通过遗传学方法对小白链霉菌M-Z18基因组中存在的两种pld进行敲除、回补和过表达,最后研究重组菌降解ε-PL能力、最小ε-PL抑制浓度（MIC）及其合成ε-PL情况。[结果] PldⅠ和PldⅡ广泛且同时分布于小白链霉菌中,蛋白序列高度保守;PldⅠ、PldⅡ在小白链霉菌M-Z18中均能行使降解ε-PL的功能,但PldⅡ降解活性占主导地位且PldⅠ和PldⅡ对降解ε-PL具有协同作用;pldⅠ、pldⅡ过表达重组菌对ε-PL的MIC值显著提高,其中双过表达pldⅠ和pldⅡ菌株对ε-PL的MIC值是出发菌株的2.19倍。构建的pld重组菌与出发菌株相比,在考察pH值范围内（pH 3.0-5.5）的ε-PL产量未表现出显著差异。[结论] 小白链霉菌中广泛分布PldⅠ和PldⅡ且序列高度保守,主要生理功能是保护小白链霉菌在中性环境中免受自身产物ε-PL的抑制。     

Structural insights into the targeting of mRNA GU-rich elements by the three RRMs of CELF1

The CUG-BP, Elav-like family (CELF) of RNA-binding proteins control gene expression at a number of different levels by regulating pre-mRNA splicing, deadenylation and mRNA stability. We present structural insights into the binding selectivity of CELF member 1 (CELF1) for GU-rich mRNA target sequences of the general form 5′-UGUN_xUGUN_yUGU and identify a high affinity interaction (K_d ∼ 100 nM for x = 2 and y = 4) with simultaneous binding of all three RNA recognition motifs within a single 15-nt binding element. RNA substrates spin-labelled at either the 3′ or 5′ terminus result in differential nuclear magnetic resonance paramagnetic relaxation enhancement effects, which are consistent with a non-sequential 2-1-3 arrangement of the three RNA recognition motifs on UGU sites in a 5′ to 3′ orientation along the RNA target. We further demonstrate that CELF1 binds to dispersed single-stranded UGU sites at the base of an RNA hairpin providing a structural rationale for recognition of CUG expansion repeats and splice site junctions in the regulation of alternative splicing.     

Mycorrhizal preference promotes habitat invasion by a native Australian orchid: Microtis media

Background and Aims

Mycorrhizal specialization has been shown to limit recruitment capacity in orchids, but an increasing number of orchids are being documented as invasive or weed-like. The reasons for this proliferation were examined by investigating mycorrhizal fungi and edaphic correlates of Microtis media, an Australian terrestrial orchid that is an aggressive ecosystem and horticultural weed.

Methods

Molecular identification of fungi cultivated from M. media pelotons, symbiotic in vitro M. media seed germination assays, ex situ fungal baiting of M. media and co-occurring orchid taxa (Caladenia arenicola, Pterostylis sanguinea and Diuris magnifica) and soil physical and chemical analyses were undertaken.

Key Results

It was found that: (1) M. media associates with a broad taxonomic spectrum of mycobionts including Piriformospora indica, Sebacina vermifera, Tulasnella calospora and Ceratobasidium sp.; (2) germination efficacy of mycorrhizal isolates was greater for fungi isolated from plants in disturbed than in natural habitats; (3) a higher percentage of M. media seeds germinate than D. magnifica, P. sanguinea or C. arenicola seeds when incubated with soil from M. media roots; and (4) M. media–mycorrhizal fungal associations show an unusual breadth of habitat tolerance, especially for soil phosphorus (P) fertility.

Conclusions

The findings in M. media support the idea that invasive terrestrial orchids may associate with a diversity of fungi that are widespread and common, enhance seed germination in the host plant but not co-occurring orchid species and tolerate a range of habitats. These traits may provide the weedy orchid with a competitive advantage over co-occurring orchid species. If so, invasive orchids are likely to become more broadly distributed and increasingly colonize novel habitats.