Does the platelet-activating factor affect the antioxidant defense system?

The platelet-activating factor (PAF) is an inflammatory mediator and it may exert some of its effects by reactive oxygen species (ROS). We investigated the effects of PAF and hyperbaric oxygenation (HBO) on copper (Cu) and zinc (Zn) levels in plasma and the intracellular antioxidant enzyme activities of rats. PAF administration caused a decrease in erythrocyte catalase (CAT) and glutathione peroxidase (GPx) activities and in the plasma zinc level. Following PAF administration, exposure to HBO also caused a decrease in erythrocyte GPx activity. These results support the hypothesis that PAF may produce free oxygen radicals and HBO enhances this effect. The enzyme activities of the antioxidant defense system were found to be affected by these oxidative processes. This is likely to be the result of excessive production of ROS or overutilization and/or inhibition of the antioxidant enzymes.     

N‐terminal guanidinylation of the cyclic 1,4‐ureido‐deltorphin analogues: the synthesis,receptor binding studies,and resistance to proteolytic digestion

The synthesis of a series of N‐guanidinylated cyclic ureidopeptides, analogues of 1,4‐ureido‐deltorphin/dermorphine tetrapeptide is described. The δ‐ and μ‐opioid receptor affinity of new guanidinylated analogues and their non‐guanidinylated precursors was determined by the displacement radioligand binding experiments. Our results indicate that the guanidinylation of cyclic 1,4‐ureidodeltorphin peptide analogues does not exhibit a uniform influence on the opioid receptor binding properties, similarly as reported earlier for some linear peptides. All analogues were also tested for their in vitro resistance to proteolysis during incubation with large excess of chymotrypsin, pepsin, and papain by means of mass spectroscopy. Guanidinylated ureidopeptides 1G–4G showed mixed μ agonist/δ agonist properties and high enzymatic stability indicating their potential as therapeutic agents for treatment of pain. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.     

The levels of melatonin and its metabolites in conditioned corn (<Emphasis Type="Italic">Zea mays</Emphasis> L.) and cucumber (<Emphasis Type="Italic">Cucumis sativus</Emphasis> L.) seeds during storage

The efficiency of pre-sowing conditioning/priming methods used to apply melatonin into seeds was verified: osmopriming in the case of dicot Cucumis sativus and hydropriming of monocot Zea mays seeds. Both priming techniques were selected experimentally as optimal for the studied plant species. Four different seed variants were compared: control non-treated ones, and seeds conditioned with water or with 50 or 500 μM melatonin water solutions. The HPLC–MS quantitative and qualitative analyses were used to determine the content of melatonin and of its potential metabolites in the seeds during 1 year following the conditioning. The control seeds and those conditioned with water contained small amount of endogenous melatonin in both species. However, the level of this indoleamine increased markedly in cucumber and corn seeds primed with exogenous melatonin and it was always correlated with the concentration of melatonin applied. It was noted that melatonin was metabolized during seed storage by its gradual oxidation, thus it protects dry seeds against oxidative stress, prevents potential injuries and significantly increases seeds quality. Interestingly, in the control and water-primed seeds, seasonal fluctuations of endogenous melatonin concentration were noted and significant increase in this indoleamine in the winter month was observed. This suggests that in seeds endogenous melatonin could play a crucial role in seasonal rhythms independently of environmental conditions.     

Morphological separation of aphid species <Emphasis Type="Italic">Cryptomyzus leonuri</Emphasis> Bozhko, 1961 and <Emphasis Type="Italic">Cryptomyzus alboapicalis</Emphasis> (Theobald, 1916) (Hemiptera: Sternorrhyncha: Aphididae)

Aphids of the species Cryptomyzus alboapicalis (Theobald, 1916) and Cryptomyzus leonuri Bozhko, 1961 are very similar morphologically, although exploit different host plants (Lamium album and Leonurus cardiaca, respectively). Morphological characters proposed for the separation of this species couple in the identification key to European Cryptomyzus species appeared to be of little discriminatory power when applied to apterous viviparous females from clonal lineages, whilst alate viviparous females of C. leonuri were not included in the key at all. The aim of this study was to find reliable morphological characters and their combinations for the separation of apterous and alate viviparous females of C. alboapicalis and C. leonuri. Forward stepwise discriminant analysis based on characters without statistically significant (P < 0.05) correlation (|r| ≥ 0.50) with body length resulted in canonical functions enabling correct classification of 95–100% of specimens from clonal lineages involved in the analysis with a priori specified group membership. The post hoc classification gave 95–100% correct identification of individuals from clonal and 85–100% from field-collected samples. The discriminative values of single morphological characters and canonical functions are discussed and modified key for the morphological identification of C. alboapicalis and C. leonuri apterous and alate viviparous females is suggested.     

Glucose deficiency inhibits glycosaminoglycans synthesis in fibroblast cultures

We decided to study the effect of glucose deprivation on glycosaminoglycan (GAG) synthesis and degradation in fibroblast cultures, vitality of these cells and a correlation of these processes with the expression of oxygen/glucose-regulated proteins (ORP150/GRP170). The incorporation of [³H]-glucosamine into both newly synthesised hyaluronic acid and sulphated GAGs and [³⁵S]-sulphate into GAGs was used as an index of glycosaminoglycan synthesis. Quantitative evaluation of newly synthesised GAGs degradation was determined by pulse-chase experiments. We demonstrated that fibroblasts incubated in high glucose medium synthesised significant amounts of GAGs. Most of them were secreted into the culture medium. The shortage of glucose resulted in about 40% reduction in synthesis of GAGs, both those secreted into culture medium and remaining in the cell layer. The pulse-chase experiments demonstrated that the reduced amount of newly synthesised glycosaminoglycans was protected against intracellular degradation. Proportionally less GAGs were degraded in cultures incubated in low glucose than in high glucose media. These phenomena were accompanied by an increase in the expression of chaperon – ORP150 in cultures growing in low glucose medium. We suggest that the increased expression of ORP150 is a factor which prolongs the cell vitality and protects glycosaminoglycans against intracellular degradation induced by glucose deprivation.     

Kinetic study of Lactococcus lactis strains (SLT6 and SLT10) growth on papain-hydrolysed whey

The effect of controlled whey hydrolysis by papain on growth of two lactic acid bacteria isolated from artisanal Leben: Lactococcus lactis var. diacetylactis (SLT6 and SLT10) was investigated. The higher biomass and maximum specific growth rate (μ _max) were obtained after 30 min of hydrolysis. HPLC analysis of peptides showed that whey hydrolysis reduced the amount of peptides of MW > 400 Da and increased those peptides of MW < 400 Da. The two studied strains exhibited different peptide requirements. The pH-controlled batch cultures in 30 min hydrolysed whey followed the Monod kinetic for growth and for lactate production. The values of the key kinetic constants were: maximum specific growth rate (μ _max), 1.08 and 0.56 h^?1; yield biomass on lactose (Y _x/s), 0.20 and 0.18 g g^?1 and saturation constant K _s, 4.2 and 2.8 g L^?1 for SLT6 and SLT10, respectively. When compared with batch experimental data, the model provided good predictions for growth, lactose utilisation and lactate production profiles.     

Comparative geno-plasticity analysis of Mycoplasma bovis HB0801 (Chinese isolate)

Mycoplasma bovis pneumonia in cattle has been epidemic in China since 2008. To investigate M. bovis pathogenesis, we completed genome sequencing of strain HB0801 isolated from a lesioned bovine lung from Hubei, China. The genomic plasticity was determined by comparing HB0801 with M. bovis strain ATCC? 25523?/PG45 from cow mastitis milk, Chinese strain Hubei-1 from lesioned lung tissue, and 16 other Mycoplasmas species. Compared to PG45, the genome size of HB0801 was reduced by 11.7 kb. Furthermore, a large chromosome inversion (580 kb) was confirmed in all Chinese isolates including HB0801, HB1007, a strain from cow mastitis milk, and Hubei-1. In addition, the variable surface lipoproteins (vsp) gene cluster existed in HB0801, but contained less than half of the genes, and had poor identity to that in PG45, but they had conserved structures. Further inter-strain comparisons revealed other mechanisms of gene acquisition and loss in HB0801 that primarily involved insertion sequence (IS) elements, integrative conjugative element, restriction and modification systems, and some lipoproteins and transmembrane proteins. Subsequently, PG45 and HB0801 virulence in cattle was compared. Results indicated that both strains were pathogenic to cattle. The scores of gross pathological assessment for the control group, and the PG45- and HB0801-infected groups were 3, 13 and 9, respectively. Meanwhile the scores of lung lesion for these three groups were 36, 70, and 69, respectively. In addition, immunohistochemistry detection demonstrated that both strains were similarly distributed in lungs and lymph nodes. Although PG45 showed slightly higher virulence in calves than HB0801, there was no statistical difference between the strains (P>0.05). Compared to Hubei-1, a total of 122 SNP loci were disclosed in HB0801. In conclusion, although genomic plasticity was thought to be an evolutionary advantage, it did not apparently affect virulence of M. bovis strains in cattle.     

In vivo and in vitro assessment of brain bioenergetics in aging rats

Brain energy disorders can be present in aged men and animals. To this respect, the mitochondrial and free radical theory of aging postulates that age‐associated brain energy disorders are caused by an imbalance between pro‐ and anti‐oxidants that can result in oxidative stress. Our study was designed to investigate brain energy metabolism and the activity of endogenous antioxidants during their lifespan in male Wistar rats. In vivo brain bioenergetics were measured using ³¹P nuclear magnetic resonance (NMR) spectroscopy and in vitro by polarographic analysis of mitochondrial oxidative phosphorylation. When compared to the young controls, a significant decrease of age‐dependent mitochondrial respiration and adenosine‐3‐phosphate (ATP) production measured in vitro correlated with significant reduction of forward creatine kinase reaction (kfor) and with an increase in phosphocreatine (PCr)/ATP, PCr/Pi and PME/ATP ratio measured in vivo. The levels of enzymatic antioxidants catalase, GPx and GST significantly decreased in the brain tissue as well as in the peripheral blood of aged rats. We suppose that mitochondrial dysfunction and oxidative inactivation of endogenous enzymes may participate in age‐related disorders of brain energy metabolism.     

亏缺灌溉对板蓝根叶片光合生理特性及产量的影响

以北板蓝根(Isatis tinctoria)为研究对象, 于2018年在河西走廊中部干旱绿洲开展水分控制试验, 设轻、中、重度亏水及充分供水4个控水水平, 通过大田试验探究膜下滴灌条件下亏缺灌溉对板蓝根叶片生理指标、灌水量及产量的影响, 为河西地区板蓝根灌溉策略的制定提供理论依据。结果表明, 板蓝根叶片净光合速率(P_n)、蒸腾速率(T_r)和气孔导度(G_s)因营养和肉质根生长期受到亏缺灌溉影响而显著下降, 降幅随亏水程度的加剧而增大, 轻度亏水处理对叶片光合能力的影响不显著, 且在复水之后存在一定的补偿响应; 轻度亏水处理的产量与对照(8 348.91 kg·hm^-2)相比无显著差异, 而其它处理的产量均有不同程度的下降; 灌水量与产量的拟合关系呈二次抛物线, 即产量不随灌水量的增加而升高。因此, 综合分析表明膜下滴灌调亏降低了板蓝根叶片的光合能力, 而营养生长期轻度亏缺灌溉可以节水并提高产量和灌溉效率。