海南五针松人工林分生物量的研究

 本文是对海拔930m的17年生海南五针松(Pinus fanzeliana)人工林分生物量和生产力进行了测定和研究。按平均标准木法和样方收获法分别调查了乔木层,灌木层,草本地被物层和枯枝落叶层。据调查数,建立了估测乔木层单株林木各器官干重的回归方程。方程的相关系数和估测精度都较高,具有参考价值．分析结果表明：林分总生物量平均为161.152t／ha,生产力为10630.69kg／(ha·a),其中：乔木层生物量为149.351t／ha,生产力为11095kg／(ha·a),叶面积为199248.734m2／ha,叶面积指数为19.9149m2／m2。     

MiR-204 regulates cardiomyocyte autophagy induced by ischemia-reperfusion through LC3-II

Background  

Autophagy plays a significant role in myocardial ischemia-reperfusion (IR) injury. So it is important to inhibit autophagy to protect cardiomyocytes besides anti-apoptosis. MiRNA has been demonstrated to protect cardiomyocytes against apoptosis during IR, while whether it has anti-autophagy effect has not been known. The aim of this study was to investigate whether miR-204 regulated autophagy by regulating LC3-II protein, which is the marker of autophagosome during myocardial IR injury.     

雪莲类PEBP基因在大肠杆菌中的表达及鉴定

本实验旨在构建雪莲类PEBP基因原核表达载体,在大肠杆菌中表达并纯化类PEBP基因所编码的蛋白,为进一步研究奠定基础.将雪莲类PEBP基因开放阅读框序列克隆到原核表达载体pET30( )上,转化感受态表达菌株BL21(DE3),低浓度IPTG低温诱导融合蛋白的表达,纯化产物,Western blotting鉴定目的蛋白.IFTG低诱导PEBP,经SDS-PAGE分析,其相对分子量约为28 kD,与预期相符,表达量约占菌体蛋白的26.8%,并且通过亲和层析纯化了重组融合蛋白,Western blotting鉴定为阳性.成功构建了原核表达载体pET-PEBP,获得了高效表达产物,并为进一步研究雪莲类PEBP基因的抗冻功能打下基础.     

Analysis of bacterial communities in rhizosphere soil of continuously cropped healthy and diseased konjac

The bacterial community and diversity in healthy and diseased konjac rhizosphere soils with different ages of continuous cropping were investigated using next-generation sequencing. The results demonstrated that the number of years of continuous cropping significantly altered soil bacterial community and diversity. Soil bacterial Shannon diversity index and Chao 1 index decreased with the increasing cropping years of konjac. After 1 year of cropping, the soil exhibited the highest bacterial relative abundance and diversity. Of the 44 bacterial genera (relative abundance ratio of genera greater than 0.3%), 14 were significantly affected by the duration of continuous cropping and plant status. With increasing continuous cropping, Alicyclobacillus decreased, while Achromobacter, Lactobacillus, Kaistobacter, Rhodoplanes increased after 3 years continuous cropping. Continuous cropping altered the structure and composition of the soil bacterial community, which led to the reduction in the beneficial bacteria and multiplication of harmful bacteria. These results will improve our understanding of soil microbial community regulation and soil health maintenance in konjac farm systems.     

How belowground interactions contribute to the coexistence of mycorrhizal and non-mycorrhizal species in severely phosphorus-impoverished hyperdiverse ecosystems

Background

Mycorrhizal strategies are very effective in enhancing plant acquisition of poorly-mobile nutrients, particularly phosphorus (P) from infertile soil. However, on very old and severely P-impoverished soils, a carboxylate-releasing and P-mobilising cluster-root strategy is more effective at acquiring this growth-limiting resource. Carboxylates are released during a period of only a few days from ephemeral cluster roots. Despite the cluster-root strategy being superior for P acquisition in such environments, these species coexist with a wide range of mycorrhizal species, raising questions about the mechanisms contributing to their coexistence.

Scope

We surmise that the coexistence of mycorrhizal and non-mycorrhizal strategies is primarily accounted for by a combination of belowground mechanisms, namely (i) facilitation of P acquisition by mycorrhizal plants from neighbouring cluster-rooted plants, and (ii) interactions between roots, pathogens and mycorrhizal fungi, which enhance the plants’ defence against pathogens. Facilitation of nutrient acquisition by cluster-rooted plants involves carboxylate exudation, making more P available for both themselves and their mycorrhizal neighbours. Belowground nutrient exchanges between carboxylate-exuding plants and mycorrhizal N₂-fixing plants appear likely, but require further experimental testing to determine their nutritional and ecological relevance. Anatomical studies of roots of cluster-rooted Proteaceae species show that they do not form a complete suberised exodermis.

Conclusions

The absence of an exodermis may well be important to rapidly release carboxylates, but likely lowers root structural defences against pathogens, particularly oomycetes. Conversely, roots of mycorrhizal plants may not be as effective at acquiring P when P availability is very low, but they are better defended against pathogens, and this superior defence likely involves mycorrhizal fungi. Taken together, we are beginning to understand how an exceptionally large number of plant species and P-acquisition strategies coexist on the most severely P-impoverished soils.

     

Allografts of the acellular sciatic nerve and brain-derived neurotrophic factor repair spinal cord injury in adult rats

Objective

We aimed to investigate whether an innovative growth factor-laden scaffold composed of acellular sciatic nerve (ASN) and brain-derived neurotrophic factor (BDNF) could promote axonal regeneration and functional recovery after spinal cord injury (SCI).

Methods

Following complete transection at the thoracic level (T9), we immediately transplanted the grafts between the stumps of the severed spinal cords. We evaluated the functional recovery of the hindlimbs of the operated rats using the BBB locomotor rating scale system every week. Eight weeks after surgery, axonal regeneration was examined using the fluorogold (FG) retrograde tracing method. Electrophysiological analysis was carried out to evaluate the improvement in the neuronal circuits. Immunohistochemistry was employed to identify local injuries and recovery.

Results

The results of the Basso-Beattie-Bresnahan (BBB) scale indicated that there was no significant difference between the individual groups. The FG retrograde tracing and electrophysiological analyses indicated that the transplantation of ASN-BDNF provided a permissive environment to support neuron regeneration.

Conclusion

The ASN-BDNF transplantation provided a promising therapeutic approach to promote axonal regeneration and recovery after SCI, and can be used as part of a combinatory treatment strategy for SCI management.     

The CHD3 remodeler PICKLE associates with genes enriched for trimethylation of histone H3 lysine 27

In Arabidopsis (Arabidopsis thaliana), the ATP-dependent chromatin remodeler PICKLE (PKL) determines expression of genes associated with developmental identity. PKL promotes the epigenetic mark trimethylation of histone H3 lysine 27 (H3K27me3) that facilitates repression of tissue-specific genes in plants. It has previously been proposed that PKL acts indirectly to promote H3K27me3 by promoting expression of the POLYCOMB REPRESSIVE COMPLEX2 complex that generates H3K27me3. We undertook expression and chromatin immunoprecipitation analyses to further characterize the contribution of PKL to gene expression and developmental identity. Our expression data support a critical and specific role for PKL in expression of H3K27me3-enriched loci but do not support a role for PKL in expression of POLYCOMB REPRESSIVE COMPLEX2. Moreover, our chromatin immunoprecipitation data reveal that PKL protein is present at the promoter region of multiple H3K27me3-enriched loci, indicating that PKL directly acts on these loci. In particular, we find that PKL is present at LEAFY COTYLEDON1 and LEAFY COTYLEDON2 during germination, which is when PKL acts to repress these master regulators of embryonic identity. Surprisingly, we also find that PKL is present at the promoters of actively transcribed genes that are ubiquitously expressed such as ACTIN7 and POLYUBIQUITIN10 that do not exhibit PKL-dependent expression. Taken together, our data contravene the previous model of PKL action and instead support a direct role for PKL in determining levels of H3K27me3 at repressed loci. Our data also raise the possibility that PKL facilitates a common chromatin remodeling process that is not restricted to H3K27me3-enriched regions.     

The polysaccharides from Ganoderma lucidum: Are they always inhibitors on human hepatocarcinoma cells?

The antitumor activity of intracellular polysaccharides from submerged fermentation of Ganoderma lucidum was investigated focusing on the inhibition on human liver cancer cells. The polysaccharides inhibited human hepatocarcinoma cell HepG2 during earlier phase with lower dosage but obviously became less functional in later phase regardless of the dosage applied. However, apoptosis of the drugged HepG2 cells appeared in later incubation phase with high dosage, and the apoptosis could be enhanced by supplemental dose of the intracellular polysaccharides. Nevertheless, the intracellular polysaccharides inhibited other human hepatocarcinoma cells such as BEL-7402 and Huh-7 but luckily stimulated human normal liver cell L02 only in a positive dose- and time-dependent manner; so did the sulfated extracellular polysaccharides when it inhibited HepG2 and L02 cells. However, the toxicity of sulfated extracellular polysaccharides to L02 cells can be eliminated by the intracellular polysaccharides.     

Synthetic biology: advancing biological frontiers by building synthetic systems

Advances in synthetic biology are contributing to diverse research areas, from basic biology to biomanufacturing and disease therapy. We discuss the theoretical foundation, applications, and potential of this emerging field.