First case of parthenogenesis in ladybirds (Coleoptera: Coccinellidae) suggests new mechanisms for the evolution of asexual reproduction

Parthenogenesis, the development of unfertilized eggs resulting in the exclusive production of female offspring, is rare in animals relative to sexual reproduction and is mainly reported in invertebrates. It has been hypothesized that polyploidy, hybridization and endosymbiont infections are its major causal events but the mechanisms triggering asexual reproduction remain unclear. Here, we study the proximate causes at the origin of parthenogenesis in the first reported case of asexuality in the Coccinellidae (Coleoptera). The asexual populations were found in the Azores and the Mascarene archipelagos, and were identified as Nephus voeltzkowi Weise, a bisexual species widespread in sub-Saharan Africa. The specimens from both populations are diploid but present different karyotypes and heterozygosities that evoke hybrid origins, commonly associated with parthenogenesis in Coleoptera. However, the close proximity of their genomes (99.8% homology for the complete mitochondrial genome and 99.9% for the complete nuclear ribosomal cluster) together with the congruence between the mtDNA tree and the nuclear tree, and the low heterozygosity levels, suggests that the two populations are not hybrid. We propose that they belong to a single chromosomally polymorphic species undergoing Robertsonian fusions. Furthermore, specimens from both populations are infected with Wolbachia (supergroup B strain), contrary to sympatric bisexual species of the same genus. Although Wolbachia has been shown to induce parthenogenesis in haplodiploid organisms, it has been recently suggested that it could also induce parthenogenesis in hosts with other sex determination systems. Whether chromosome rearrangements and/or Wolbachia infections are post-parthenogenetic events or are at the origin of parthenogenesis still needs to be determined.     

Use of data envelopment analysis to benchmark environmental product declarations—a suggested framework

The International Journal of Life Cycle Assessment - Environmental product declarations (EPDs) are standardized tools based on life cycle assessment (LCA) to communicate and compare environmental...     

刺梨GL2同源基因的克隆、系谱树和表达分析

为了观察刺梨果实的果刺细胞学发育过程,该研究以刺梨‘贵农5号''的cDNA为模板,通过RACE克隆获得刺梨中与拟南芥表皮毛形成GL2的同源基因RrGL2,并对该基因进行生物信息学分析和表达分析。结果表明:(1)刺结构在花芽形成早期基部内的细胞首先不断分裂,向外继续发育,中部的细胞变细、变长形成“针”状结构,顶部的细胞逐渐木质化使刺变硬,形成果刺。(2)通过RACE扩增得到RrGL2的cDNA全长2 292 bp,编码763 aa氨基酸。(3)RrGL2具有Homeodomain同源结构域和StAR磷脂酰胆碱转移蛋白的结构域,RrGL2与其他物种编码的GL2氨基酸同源性高度相似,并且系谱树分析揭示刺梨RrGL2和野草莓的GL2密切相关。(4)qRT-PCR分析表明,RrGL2在茎和果实中的表达水平高于其他组织,在花后7周果刺中的表达最高,是3周和5周果刺中的7.87倍和2.10倍。综上结果发现RrGL2的功能与果刺的形成发育密切相关,该研究为刺梨中刺形成的分子机制和育种提供了理论基础。     

青藏高原草地产量与草畜平衡变化

深入了解青藏高原草地生产力与草畜平衡状态的变化,是青藏高原生态屏障建设和生态环境保护的基础。利用遥感植被指数和叶面积指数产品,基于VIP生态水文过程模型,模拟分析了青藏高原2000—2018年间草地生产力的时空格局,并结合同期农牧业统计资料,分析了青藏高原县域尺度草畜平衡状态的变化。结果表明:青藏高原草地多年平均净初级生产力(NPP)为158.4 g C·m^-2·a^-1;近20年来草地生产力上升趋势明显,显著上升面积的比例为44.7%。气候变暖、降水量增加、草本植物生长期延长和大气CO₂浓度升高是青藏高原草地生产力提高的主要驱动因素。基于草场产量估算的青藏高原平均理论载畜量为1.17 SU·hm^-2,年增长率为0.011 SU·hm^-2。2000年以来青藏高原草地超载情况总体趋于好转,严重超载县的面积比例已降至20%以下,其中超载程度较严重的地区,畜牧业的维持和发展主要依靠作物秸秆补饲。研究结果可为区域农牧业结构调整和生态环境保护提供科学依据。     

翻压山黧豆绿肥与氮肥减施对水稻生长及其养分吸收与产量的影响

为探明种植翻压山黧豆绿肥与减施氮肥下的水稻生产潜力,通过3年田间定位试验,设置冬闲+不施肥(NF)、山黧豆绿肥(GM)、冬闲+常规氮肥(100%N,CK)、山黧豆绿肥+80%常规氮肥(GM+80%N)、山黧豆绿肥+70%常规氮肥(GM+70%N)、山黧豆绿肥+60%常规氮肥(GM+60%N)6个处理,研究不同处理对水稻生长、养分吸收及产量的影响。结果表明：(1)与CK相比,翻压山黧豆绿肥并减施氮肥处理均能够显著提升水稻株高、增加水稻分蘖数、提高水稻干物质积累量,其中以GM+70%N施肥处理提升效果最为明显。(2)GM+70%N施肥处理下,不同生育时期水稻株高、有效分蘖数分别较对照常规施肥(100%N)提升了13.32%~ 15.73%和33.98%~59.47%,水稻干物质积累量提高了23.19%~144.18%,且随着生育时期的推进增加速率依次降低。(3)种植翻压山黧豆绿肥并减施氮肥处理下水稻产量均有所提高,其中GM+70%N和GM+80%N处理显著提高,增产分别达13.84%,7.25%,且GM+70%N处理下水稻植株和籽粒养分吸收更为全面。研究发现,种植翻压山黧豆并适量减施氮肥能有效促进水稻生长和养分的吸收积累,显著提高水稻产量,说明翻压山黧豆绿肥可替代稻田30%~40%的氮肥施入量,并可在避免水稻旺长的同时实现水稻高产,是四川水稻种植较好的耕作措施。     

硅素对水稻幼苗镉积累及抗胁迫应答的调节效应

施硅(Si)可以显著缓解镉(Cd)胁迫对水稻生长发育的毒害效应。本研究通过水培分根试验,研究了Si对水稻幼苗Cd积累及胁迫应答的调节效应。结果表明: Cd胁迫下水稻幼苗的生物量显著降低,加Si可以显著缓解Cd对水稻幼苗生长的抑制效应。水稻幼苗对Cd的吸收、转运和积累明显受到Si的影响,单侧根系Cd胁迫下加Si(Si-Cd+Si,Si-Cd)使根系对Cd的滞留系数达83.3%～83.6%,限制了Cd从根向地上部转移。单侧根系Cd胁迫下非胁迫侧加Si(Si-Cd)处理的植株对Cd的吸收和累积明显增加,尤其是根中Cd的积累量较单侧根系Cd胁迫下无Si(CK-Cd)处理增加了48.2%;而单侧根系Cd胁迫下双侧加Si(Si-Cd+Si)处理则显著降低了根和地上部对Cd的吸收,较CK-Cd处理分别降低了36.7%和54.9%。双侧Cd胁迫下单侧加Si(Cd-Cd+Si)则使根和地上部对Cd的吸收量显著减少,较双侧根Cd胁迫(Cd-Cd)处理分别降低了57.8%和46.5%。Cd胁迫下水稻幼苗根中含较高浓度的Si,加Si则使Cd胁迫下根和地上部积累更多的Si。加Si也影响了水稻幼苗对其他金属元素如钙(Ca)、镁(Mg)、锰(Mn)的吸收,Cd-Cd+Si处理显著增加了根系和地上部的Ca、Mg浓度,但Mn浓度的变化则因Cd胁迫程度而表现不同。加Si对Cd胁迫下根系超氧化物歧化酶(SOD)和过氧化物酶(POD)活性有一定的影响,尤其是Si-Cd处理的胁迫侧POD和非胁迫侧SOD活性显著上升,有利于清除Cd胁迫产生的氧自由基。总之,Si对Cd胁迫下水稻幼苗生长、Cd和Si等的吸收及根系的抗氧化反应有一定的调节效应,植株体内较高的Si浓度有利于增强植株对Cd的耐受性。     

Structural analysis and biochemical properties of laccase enzymes from two Pediococcus species

Prokaryotic laccases are emergent biocatalysts. However, they have not been broadly found and characterized in bacterial organisms, especially in lactic acid bacteria. Recently, a prokaryotic laccase from the lactic acid bacterium Pediococcus acidilactici 5930, which can degrade biogenic amines, was discovered. Thus, our study aimed to shed light on laccases from lactic acid bacteria focusing on two Pediococcus laccases, P. acidilactici 5930 and Pediococcus pentosaceus 4816, which have provided valuable information on their biochemical activities on redox mediators and biogenic amines. Both laccases are able to oxidize canonical substrates as ABTS, ferrocyanide and 2,6-DMP, and non-conventional substrates as biogenic amines. With ABTS as a substrate, they prefer an acidic environment and show sigmoidal kinetic activity, and are rather thermostable. Moreover, this study has provided the first structural view of two lactic acid bacteria laccases, revealing new structural features not seen before in other well-studied laccases, but which seem characteristic for this group of bacteria. We believe that understanding the role of laccases in lactic acid bacteria will have an impact on their biotechnological applications and provide a framework for the development of engineered lactic acid bacteria with enhanced properties.     

Evaluation of Antioxidant,Antibacterial and Enhancement of Antibiotic Action by Punica granatum Leaves Crude Extract and Enriched Fraction against Multidrug-Resistant Bacteria

The aim of this study was to evaluate the phytochemical composition, antioxidant, and antimicrobial potential of crude extract and fractions of Punica granatum leaves. The extract was produced by turbo extraction, after which hexanic, ethyl acetate, and aqueous fractions were obtained by partitioning. The chemical analyses were performed by thin layer chromatography and high-performance liquid chromatography, and the antioxidant activities were assayed by DPPH^. and ABTS^.+. Minimal inhibitory and bactericidal concentrations (MIC/MBC) were applied to twenty-two bacteria. Most strains susceptible to extract/fractions and resistant to antibiotics were selected, and ampicillin, azithromycin, ciprofloxacin, and gentamicin were associated with the ethyl acetate fraction (EAF) against multidrug-resistant strains in modulatory and checkboard models. The data from chromatographic analyses showed flavonoids and tannins in the extract, as well as the enrichment of EAF in phenols, mainly flavonoids. The flavonoids were connected to the electron transfer activity demonstrated in the DPPH^. and ABTS^.+ assays. Gram-positive strains are more susceptible to EAF. The subinhibitory concentrations of P. granatum enhanced the antimicrobial activity of the agents and reduced the EAF individual MIC, and the combination of EAF and antibiotics demonstrated a synergistic effect. These results present a promising approach for developing a therapy in which antioxidant extracts and fractions can be used in combination with antibiotics.     

Cardamonin Presents in Vivo Activity against Schistosoma mansoni and Inhibits Potato Apyrase

Schistosomiasis, a neglected tropical disease caused by Schistosoma species, harms over 250 million people in several countries. The treatment is achieved with only one drug, praziquantel. Cardamonin, a natural chalcone with in vitro schistosomicidal activity, has not been in vivo evaluated against Schistosoma. In this work, we evaluated the in vivo schistosomicidal activities of cardamonin against Schistosoma mansoni worms and conducted enzymatic apyrase inhibition assay, as well as molecular docking analysis of cardamonin against potato apyrase, S. mansoni NTPDase 1 and S. mansoni NTPDase 2. In a mouse model of schistosomiasis, the oral treatment with cardamonin (400 mg/kg) showed efficacy against S. mansoni, decreasing the total worm load in 46.8 % and reducing in 54.5 % the number of eggs in mice. Cardamonin achieved a significant inhibition of the apyrase activity and the three-dimensional structure of the potato apyrase, obtained by homology modeling, showed that cardamonin may interact mainly through hydrogen bonds. Molecular docking studies corroborate with the action of cardamonin in binding and inhibiting both potato apyrase and S. mansoni NTPDases.