Genetic diversity and population structure of Tunisian wild Kermes oak (Quercus coccifera L.): Assessment by ISSR molecular markers and implication for conservation

Molecular Biology Reports - In Tunisia, Kermes oak (Quercus coccifera L.) populations are severely destroyed due to deforestation. Nowadays, no preservation programs are attempted, yet, to conserve...     

Effect of hydroxytyrosol‐rich preparations on phenolic‐linked antioxidant activity of seeds

Hydroxytyrosol‐rich extract (HRE) and hydroxytyrosol‐rich olive mill wastewater (HROMW) were used as exogenous growth enhancers to stimulate tomato seedling vigor. The tomato seeds soaking in 10% w/v HROMW or HRE solutions were optimum in maximally enhancing seedling performance according to biochemical seed vigor parameters. Biochemical parameters as the average glucose‐6‐phosphate dehydrogenase (G6PDH) activity in HRE‐treated seeds (915.11 nmoles min^?1 mg^?1 protein) was higher than control (629.58 nmoles min^?1 mg^?1 protein) and correlated with the increased phenolic content (3530 μg g^?1 fw) and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH)‐based antioxidant activity (70.60%), respectively. Some key enzymes, guaiacol peroxidase (GPX) (6100.65 nmoles min^?1 mg^?1 protein) and catalase (2.04 μmoles min^?1 mg^?1 protein), were also higher in response to treatments and correlated with enhanced phenolic content and antioxidant activity. This study supports the hypothesis that the exogenous phenolic application stimulates the pentose phosphate pathway through an over‐expression of endogenous phenolic synthesis and an increase in free‐radical scavenging antioxidant activity. Therefore, the current study indicates the enhancement of seed vigor by HRE especially and HROMW as reflected by the stimulation of biochemical responses.     

Synergistic plant–microbe interactions between endophytic bacterial communities and the medicinal plant <Emphasis Type="Italic">Glycyrrhiza uralensis</Emphasis> F.

Little is known about the composition, diversity, and geographical distribution of bacterial communities associated with medicinal plants in arid lands. To address this, a collection of 116 endophytic bacteria were isolated from wild populations of the herb Glycyrrhiza uralensis Fisch (licorice) in Xinyuan, Gongliu, and Tekesi of Xinjiang Province, China, and identified based on their 16S rRNA gene sequences. The endophytes were highly diverse, including 20 genera and 35 species. The number of distinct bacterial genera obtained from root tissues was higher (n?=?14) compared to stem (n?=?9) and leaf (n?=?6) tissue. Geographically, the diversity of culturable endophytic genera was higher at the Tekesi (n?=?14) and Xinyuan (n?=?12) sites than the Gongliu site (n?=?4), reflecting the extremely low organic carbon content, high salinity, and low nutrient status of Gongliu soils. The endophytic bacteria exhibited a number of plant growth-promoting activities ex situ, including diazotrophy, phosphate and potassium solubilization, siderophore production, auxin synthesis, and production of hydrolytic enzymes. Twelve endophytes were selected based on their ex situ plant growth-promoting activities for growth chamber assays to test for their ability to promote growth of G. uralensis F. and Triticum aestivum (wheat) plants. Several strains belonging to the genera Bacillus (n?=?6) and Achromobacter (n?=?1) stimulated total biomass production in both G. uralensis and T. aestivum under low-nutrient conditions. This work is the first report on the isolation and characterization of endophytes associated with G. uralensis F. in arid lands. The results demonstrate the broad diversity of endophytes associated with wild licorice and suggest that some Bacillus strains may be promising candidates for biofertilizers to promote enhanced survival and growth of licorice and other valuable crops in arid environments.     

Effects of the Preparation Method on the Formation of True Nimodipine SBE-β-CD/HP-β-CD Inclusion Complexes and Their Dissolution Rates Enhancement

The aims of this study were to enhance the solubility and dissolution rate of nimodipine (ND) by preparing the inclusion complexes of ND with sulfobutylether-b-cyclodextrin (SBE-β-CD) and 2-hydroxypropyl-b-cyclodextrin (HP-β-CD) and to study the effect of the preparation method on the in vitro dissolution profile in different media (0.1 N HCl pH 1.2, phosphate buffer pH 7.4, and distilled water). Thus, the inclusion complexes were prepared by kneading, coprecipitation, and freeze-drying methods. Phase solubility studies were conducted to characterize the complexes in the liquid state. The inclusion complexes in the solid state were investigated with differential scanning calorimetry (DSC), X-ray diffractometry (X-RD), and Fourier transform infrared spectroscopy (FT-IR). Stable complexes of ND/SBE-β-CD and ND/HP-β-CD were formed in distilled water in a 1:1 stoichiometric inclusion complex as indicated by an A_L-type diagram. The apparent stability constants (Ks) were 1334.4 and 464.1 M⁻¹ for ND/SBE-β-CD and ND/HP-β-CD, respectively. The water-solubility of ND was significantly increased in an average of 22- and 8-fold for SBE-β-CD and HP-β-CD, respectively. DSC results showed the formation of true inclusion complexes between the drug and both SBE-β-CD and HP-β-CD prepared by the kneading method. In contrast, crystalline drug was detectable in all other products. The dissolution studies showed that all the products exhibited higher dissolution rate than those of the physical mixtures and ND alone, in all mediums. However, the kneading complexes displayed the maximum dissolution rate in comparison with drug and other complexes, confirming the influence of the preparation method on the physicochemical properties of the products.     

模拟降水对古尔班通古特沙漠生物结皮表观土壤碳通量的影响

水分是控制干旱区生态过程的重要环境因素,在水分受限制的生态系统中,降水通过改变土壤的干湿状态直接控制地下生物过程。生物结皮作为干旱区主要的地表覆盖物,能利用空气中有限的水分进行光合作用,其自身的碳交换是干旱区土壤碳通量的重要组成部分。通过模拟0(对照)、2、5 mm和15 mm 4个降水梯度,利用红外气体分析仪,对古尔班通古特沙漠中部生物结皮以及裸地表观土壤碳通量进行测量,探讨不同强度降水条件下生物结皮对表观土壤碳通量的影响,结果表明:(1)降水增加了生物结皮表观土壤碳释放量,2、5 mm和15 mm 3种降水处理累积碳释放量分别是对照的151.48%、274.97%、306.44%,并且随着降水后时间的延长,表观土壤碳通量逐渐减小直至达到降水前的水平;(2)生物结皮与裸地的表观土壤碳通量对降水的响应不同,对照和最大降水量下,生物结皮表观土壤碳通量大于裸地,但是2 mm和5 mm降水后,生物结皮表观土壤碳通量小于裸地,并且二者在2 mm降水时差异显著(P<0.05),而在其它降水处理下无显著差异;(3)连续两次降水事件,活性碳在初级降水后的大量释放使得二次降水后释放量下降,其中裸地碳释放量下降速率与降水强度正相关。本研究说明,在探求荒漠地区土壤碳交换对降水的响应规律时,应该考虑生物结皮的影响以及连续降水事件的差异。     

Molecular and biochemical characterization of an extracellular serine-protease from <Emphasis Type="Italic">Vibrio metschnikovii</Emphasis> J1

A protease-producing bacterium was isolated from an alkaline wastewater of the soap industry and identified as Vibrio metschnikovii J1 on the basis of the 16S rRNA gene sequencing and biochemical properties. The strain was found to over-produce proteases when it was grown at 30°C in media containing casein as carbon source (14,000 U ml⁻¹). J1 enzyme, the major protease produced by V. metschnikovii J1, was purified by a three-step procedure, with a 2.1-fold increase in specific activity and 33.3% recovery. The molecular weight of the purified protease was estimated to be 30 kDa by SDS-PAGE and gel filtration. The N-terminal amino acid sequence of the first 20 amino acids of the purified J1 protease was AQQTPYGIRMVQADQLSDVY. The enzyme was highly active over a wide range of pH from 9.0 to 12.0, with an optimum at pH 11.0. The optimum temperature for the purified enzyme was 60°C. The activity of the enzyme was totally lost in the presence of PMSF, suggesting that the purified enzyme is a serine protease. The kinetic constants K _m and K _cat of the purified enzyme using N-succinyl-l-Ala-l-Ala-l-Pro-l-Phe-p-nitroanilide were 0.158 mM and 1.14 × 10⁵ min⁻¹, respectively. The catalytic efficiency (K _cat /K _m) was 7.23 × 10⁸ min⁻¹ M⁻¹. The enzyme showed extreme stability toward non-ionic surfactants and oxidizing agents. In addition, it showed high stability and compatibility with some commercial liquid and solid detergents. The aprJ1 gene, which encodes the alkaline protease from V. metschnikovii J1, was isolated, and its DNA sequence was determined. The deduced amino acid sequence of the preproenzyme differs from that of V. metschnikovii RH530 detergent-stable protease by 12 amino acids, 7 located in the propeptide and 5 in the mature enzyme.     

Study of the Effect of Phosphorus on Mineral Nutrition of Faba Bean « Vicia fabae L.»

Our study focuses on the study of the phosphorus efficiency on the mineral nutrition of a leguminous plant; to study this efficiency, we tested the effect of increasing doses of phosphorus on the mineral nutrition of faba bean and on the concentration of Nt (total nitrogen), Pi (available phosphorus), KE (exchangeable potassium), C (organic carbon), and the organic matter (OM) rate in the rhizospheric soil after harvest, as well as the concentration of N, P, K, Na, and Ca in the roots, stems, leaves, and seeds of faba bean. The faba bean crop was subjected to four phosphorus doses (P0?=?0 kg/ha; P1?=?70 kg/ha; P2?=?140 kg/ha; P3?=?210 kg/ha). The main results obtained showed that the concentration of the mineral elements in the different faba bean parts reacted differently to the phosphorus treatments. Regarding the dosage of nutrients in the different parts of the faba bean, the results obtained highlight that Pi deficiency in the soil does not only affect phosphate nutrition but can also affect the absorption of other mineral elements, a synergy is recorded between the K concentration in the roots and in the stems with the organic carbon in the soil, and an antagonism between K and Na in the different parts of the plant. All the results obtained in this work show that a phosphate fertilization for doses between 70 kg/ha and 140 kg/ha of P2O5 improves the microbial life of soil microorganisms.

     

Propylbenzmethylation at Val-1(α) markedly increases the tetramer stability of the PEGylated hemoglobin: A comparison with propylation at Val-1(α)

Background

Hemoglobin (Hb)-based oxygen carriers (HBOCs) are potential pharmaceutical agents that can be used in surgery or emergency medicine. PEGylation can modulate the vasoactivity of Hb and is a widely used approach to develop HBOCs. However, PEGylation can significantly enhance the tetramer–dimer dissociation of Hb, which may perturb the structure of Hb and increase its observed adverse effect. Thus, it is necessary to increase the tetramer stability of the PEGylated Hb.

Methods

Propylbenzmethylation at Val-1(α) of HbA was carried out to stabilize the Hb tetramer. The propylbenzmethylated Hb at Val-1(α) (PrB-Hb) was used as the starting material for site-specific PEGylation at Cys-93(β) of Hb using maleimide PEG. Structural and functional properties, autoxidation rate and thermal stability of the resultant product (PEG-PrB-Hb) were measured.

Results

Propylbenzmethylation at Val-1(α) led to 25-fold and 24-fold decreases in the tetramer–dimer dissociation constant of HbA and PEG-Hb, respectively. The increased tetramer stability is due to the enhanced hydrophobicity of the area around Val-1(α) and the increased polar interaction of Hb upon propylbenzmethylation. Thus, the structural and functional properties of PEG-Hb were improved, and its autoxidation rate and thermal denaturation were decreased.

Conclusion

Propylbenzmethylation at Val-1(α) showed higher ability than propylation at Val-1(α) to improve the structural and functional properties and decrease the side effect of PEG-Hb.

General significance

Our study can facilitate the biotechnological development of stable PEGylated Hb as more advanced HBOC. Our study is also expected to improve the stability of the tetrameric or dimeric proteins (e.g., uric oxidase) by propylbenzmethylation at their N-terminus.