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关键词： Beta-carbonic anhydrase   Trichomonas vaginalis   Protozoan   Kinetics   Inhibition   Homology modeling  

摘要： Trichomonas vaginalis is a unicellular parasite and responsible for one of the most common sexually transmittable infections worldwide, trichomoniasis. Carbonic anhydrases (CAs) are enzymes found in all lifeforms and are known to play a vital role in many biochemical processes in organisms including the maintenance of acid-base homeostasis. To date, eight evolutionarily divergent but functionally convergent forms of CAs (alpha, beta, gamma, delta, zeta, eta, theta, and iota) have been discovered. The human genome contains only alpha-CAs, whereas many clinically significant pathogens express only beta-CAs and/or gamma-CAs. The characterization of pathogenic beta- and gamma-CAs provides important knowledge for targeting these biomolecules to develop novel anti-invectives against trichomoniasis. Here, we report the recombinant production and characterization of the second beta-CA of T. vaginalis (TvaCA2). Light scattering analysis revealed that TvaCA2 is a dimeric protein, which was further supported with in silico modeling, suggesting similar structures between TvaCA2 and the first beta-CA of T. vaginalis (TvaCA1). TvaCA2 exhibited moderate catalytic activity with the following kinetic parameters: k(cat) of 3.8 x 10(5) s(-1) and k(cat)/K-M of 4.4 x 10(7) M-1 s(-1). Enzyme activity inhibition was studied with a set of clinically used sulfonamides and sulfonamide derivates. Twenty-seven out of the 39 compounds resulted in inhibition with a nanomolar range. These initial results encourage for future work entailing the design of more potent inhibitors against TvaCA2, which may provide new assets to fight trichomoniasis. Key messages center dot Protozoan parasite Trichomonas vaginalis has two beta-carbonic anhydrases (TvaCA1/2). center dot TvaCA1/TvaCA2 represents promising targets for antitrichomonal drug development. center dot TvaCA2 is a dimer of 20.3 kDa and possesses moderate catalytic activity. center dot The most efficient inhibitor was clinical drug acetazolamide

关键词： Nitrogen fixation   Biotechnology   Agriculture   Genomics  

摘要： Given their remarkable beneficial effects on plant growth, several Azospirillum isolates currently integrate the formulations of various commercial inoculants. Our research group isolated a new strain, Azospirillum sp. UENF412522, from passion fruit rhizoplane. This isolate uses carbon sources that are partially distinct from closelyrelated Azospirillum isolates. Scanning electron microscopy analysis and population counts demonstrate the ability of Azospirillum sp. UENF-412522 to colonize the surface of passion fruit roots. In vitro assays demonstrate the ability of Azospirillum sp. UENF-412522 to fix atmospheric nitrogen, to solubilize phosphate and to produce indole-acetic acid. Passion fruit plantlets inoculated with Azospirillum sp. UENF-41255 showed increased shoot and root fresh matter by 13,8% and 88,6% respectively, as well as root dry matter by 61,4%, further highlighting its biotechnological potential for agriculture. We sequenced the genome of Azospirillum sp. UENF-412522 to investigate the genetic basis of its plant-growth promotion properties. We identified the key nif genes for nitrogen fixation, the complete PQQ operon for phosphate solubilization, the acdS gene that alleviates ethylene effects on plant growth, and the napCAB operon, which produces nitrite under anoxic conditions. We also found several genes conferring resistance to common soil antibiotics, which are critical for Azospirillum sp. UENF-412522 survival in the rhizosphere. Finally, we also assessed the Azospirillum pangenome and highlighted key genes involved in plant growth promotion. A phylogenetic reconstruction of the genus was also conducted. Our results support Azospirillum sp. UENF-412522 as a good candidate for bioinoculant formulations focused on plant growth promotion in sustainable systems.

关键词： Morphology  

摘要： Allium mongolicum Regel is a high-quality plant resource but highly perishable with short shelf life of 1-2 days. Changes in postharvest quality and microbiological population on A. mongolicum regulated by poly (butylene adipate-co-terephthalate)/poly (butylene succinate), poly (butylene adipate-co-terephthalate)/polycaprolactone, poly (butylene adipate-co-terephthalate)/poly (L-lactide) and poly (butylene adipate-co-terephthalate)/polypropylene MAP were investigated during near-freezing storage. The results showed all four MAPs could reduce the respiration rate, water loss, decay rate and malondialdehyde content significantly and maintain the morphology, color and typical flavor of A. mongolicum effectively which also had high level acceptable commercial score as well as ascorbic acid and chlorophyll contents. However, the preservation effect packed with poly (butylene adipate-co-terephthalate)/polypropylene was significantly better than the other three films in which it could establish an optimal atmospheric condition with O-2 concentration of 0.34%-0.53% and CO2 concentration of 4.53%-6.13% and the A. mongolicum had the highest level of postharvest quality, the lowest level of physiological metabolism and surface microorganisms, and its shelf life could reach 18 days. Practical applications Allium mongolicum Regel has delicious taste, high nutritional value, and bioactive ingredients good for human health but with short shelf life which is a great challenge to the storage and sales. Therefore, maintaining postharvest quality and extending shelf life are significant to the industry development for A. mongolicum. However, studies on its preservation are not available. Modified atmosphere packaging is a cheap, safe and effective method to keep produce fresh. In this study, the shelf life of A. mongolicum was extended significantly in the treatment of poly (butylene adipate-co-terephthalate)/polypropylene MAP. It provided an effective solution for the storage problem

关键词： Castration   Glycogen   Lactic acid   MFI   Tenderness   Shear force  

摘要： The aim of this study was to investigate the course of glycogenolysis, ATP breakdown and fragmentation of myofibrillar proteins in the semitendinosus muscle of a progeny of LimousinxHolstein-Friesian (LMx) and CharolaisexHolstein-Friesian (CHx) (bulls and steers) and to describe the changes in the above parameters over time and its relationship with beef texture. The hypothesis that beef from bulls and steers of different crossbreeds required the same ageing time to achieve satisfactory tenderness was also tested. Cattle crossbreeding did not affect the amount of muscle glycogen, and castration did not differentiate it until 3 h post-mortem. The interaction between crossbreeding and castration was found, and the highest shear force values were observed in CHx bulls, whereas the lowest was in CHx steers. Beef obtained from CHx was found to be more predestined to short ageing, and LMx required longer ageing to achieve good tenderness. The R-values more strongly influenced subsequent beef texture than pH values.

ISBN: (纸本)9787122406842

关键词： Mercury   Bellamya bengalensis   Oxygen consumption rate   Behaviour   Total haemocyte count   Biochemical parameters  

摘要： The widespread occurrence of Mercury (Hg) and its derivatives in the aquatic environment and risks to the health of local populations has necessitated investigations into its toxic effects on sessile species. The toxicity of Mercury was observed sequentially from 96 h acute exposure regime (behavioural endpoints) to chronic durations (haematological and biochemical toxicity endpoints) in Bellamya bengalensis. Time-dependent lethal endpoints for acute toxicity (LC50) of mercury i.e., 24,48,72 and 96 h were estimated as 0.94, 0.88, 0.69 and 0.40 mg/l respectively. Threshold effect values i.e., LOEC (Lowest Observed Effect Concentration), NOEC (No Observed Effect Concentration) and MATC (Maximum Acceptable Toxicant Concentration) at 96 h were found to be 0.10, 0.05, 0.039 mg/l respectively. The study of oxygen consumption rate and behavioural changes during acute toxicity and haematological and biochemical responses during chronic toxicity to sublethal concentrations (10% and 20% of 96 h LC50) of mercury to the snail were also conducted. The organisms showed initial elevation at 24 h but later gradual decrease in oxygen consumption rate with the increase of concentration of mercury and time of exposure. For behavioural studies, variable test concentrations from 0.00 to 1.00 mg/l were used for 24, 48, 72 and 96 h. The crawling activity and clumping tendency decreased with the progress of time at all treatment periods and stopped ultimately at 96 h of exposure from 0.7 mg/l onwards whereas touch reflex was not observed at 96 h exposure at all treatments except at 0.09 mg/l. In haemocyte count, no significant variation was observed among control values between various exposure periods (p 0.05) though variations were observed in sub-lethal concentrations versus control at all treatment duration (7, 14, 21, 28d, p < 0.05). In biochemical response study, the protein content in hepatopancreas of the snails treated at sublethal concen-trations of mercury (10% and 20% of 96 h L

关键词： Microparticle   Growth performance   Oxidative stress   Transcriptome   Metabolism disorders  

摘要： Microplastics (MPs) are pollutants that are widely distributed in the aquatic environment. Fish are directly exposed to water and are at risk of ingesting a large amount of MPs. In the present study, the grass carp were exposed to two concentrations of MPs (1000 and 100 mu g/L) and fluorescence signals were detected in the liver digestion solution. Grass carp exposed to MPs for 21-days showed liver cytoplasmic vacuolation and inhibited growth. At the end of the exposure period, the fish treated with MPs exhibited inhibition of the antioxidant system and enhancement oxidative stress in comparison with the control group. The transcriptome analysis of grass carp was then performed to reveal the molecular mechanism of the response to MPs. In total, 1554 differentially expressed genes (DEGs) were identified. The results of GO and KEGG pathway analysis of the DEGs identified energy metabolism-related pathways and peroxisome proliferator-activated receptor (PPAR) signaling pathway. Taken together, the present study not only highlighted oxidative stress and metabolism disorders related to MP ingestion, but also determined the risk of MP exposure to teleost.

关键词： Retinal degenerative diseases   G protein-coupled receptors   Protein folding   Conformational stability   Ligand binding  

摘要： Mutations in the photoreceptor protein rhodopsin are known as one of the leading causes of retinal degeneration in humans. Two rhodopsin mutations, Y102H and I307N, obtained in chemically mutagenized mice, are currently the subject of increased interest as relevant models for studying the process of retinal degeneration in humans. Here, we report on the biochemical and functional characterization of the structural and functional alterations of these two rhodopsin mutants and we compare them with the G90V mutant previously analyzed, as a basis for a better understanding of in vivo studies. This mechanistic knowledge is fundamental to use it for developing novel therapeutic approaches for the treatment of inherited retinal degeneration in retinitis pigmentosa. We find that Y102H and I307N mutations affect the inactive-active equilibrium of the receptor. In this regard, the mutations reduce the stability of the inactive conformation but increase the stability of the active conformation. Furthermore, the initial rate of the functional activation of transducin, by the I307N mutant is reduced, but its kinetic profile shows an unusual increase with time suggesting a profound effect on the signal transduction process. This latter effect can be associated with a change in the flexibility of helix 7 and an indirect effect of the mutation on helix 8 and the C-terminal tail of rhodopsin, whose potential role in the functional activation of the receptor has been usually underestimated. In the case of the Y102H mutant, the observed changes can be associated with conformational alterations affecting the folding of the rhodopsin intradiscal domain, and its presumed involvement in the retinal binding process by the receptor.

关键词： Chromosome doubling   Essential oil   Gene expression   Peppermint   Salt-tolerance  

摘要： Peppermint (Mentha piperita L.) is an important medicinal aromatic plant. In this study, the morphology, physiology, biochemistry and gene expression of chromosomes doubling peppermint (D1 lines) were analyzed. The analysis showed that D1 lines had larger, thicker and darker leaves, and stronger roots when planted in the pots, but delayed growth in the field condition. Under NaCl stress, the D1 lines increased cell oxidative defense through more active antioxidant enzymes and decreased the oxidative damages of cell membrane, leading to a significantly greater survival rate and photosynthesis intensity than WT lines. The size and density of glandular trichomes of D1 lines was larger, which contributed to its higher essential oil yield. In addition, chromosome doubling reduced the inhibition of NaCl stress on essential oil yield and quality, through changing the expression of genes in the oil biosynthesis pathway. The traits of chromosome doubling peppermint provide new technical and theoretical evidence for peppermint germplasm improvement.

关键词： 生物化学   高等学校   教材  

ISBN: (纸本)9787568930789

摘要： 本书重点讨论了蛋白质，核酸、酶、糖类和脂质等生物大分子的结构、功能以及结构与功能之间的关系，同时介绍了这些生物大分子的重要生物化学性质及相关分离、分析技术的基本原理和应用特点；其次，对糖类、脂质、氨基酸、核苷酸的分解代谢和合成代谢及其代谢调节进行了系统、微要介绍；最后，主要以原核生物为例讨论了从DNA到RNA再到蛋白质的遗传信息流的分子机制。同时，在各章中插入了知识拓展框和典型习题，体现了内容的新颖性、趣味性和实用性。本书内容编写精炼、前后呼应、富布逻辑、图文并茂，适合作为生物科学专业理科教材，同时也适合医学和大农学类相关专业本科生使用。