Tetramethylpyrazine scavenges superoxide anion and decreases nitric oxide production in human polymorphonuclear leukocytes

Tetramethylpyrazine is one of the active ingredients of the Chinese herb Ligusticum wallichii Franchat. By electron spin resonance spin trapping methods, effects of tetramethylpyrazine on superoxide anion and nitric oxide generated by human polymorphonuclear leukocytes were studied. During the respiratory burst of polymorphonuclear leukocytes induced by N-formylmethionyl-leucyl-phenylalanine, tetramethylpyrazine scavenges superoxide anion dose-dependently, and decreases the production of nitric oxide significantly, but shows no influence on oxygen consumption. These results suggest that the effective protection of tetramethylpyrazine against ischemic brain injury might be due to its scavenging of reactive oxygen species and regulation on nitric oxide production, and consequent prevention of peroxynitrite formation.     

高温胁迫影响红掌生长发育的研究进展

红掌原产于南美洲热带雨林,其具有色彩艳丽的佛焰苞,在适宜的条件下可周年开花,是一种具有极高观赏价值的盆花和切花植物.夏季高温严重影响红掌的生长和观赏价值,增加了红掌的种植成本.对高温胁迫影响红掌外观形态、光合作用、细胞膜热稳定性、渗透调节物质、保护酶活性进行了讨论分析,对高温褪色机理及其应对措施进行了归纳总结,以期为进...     

Phylogenetics of Chondrichthyes and the problem of rooting phylogenies with distant outgroups

Erroneous estimates of ingroup relationships can be caused by attributes in the outgroup chosen to root the tree. Phylogenetic analyses of DNA sequences frequently yield incorrect estimates of ingroup relationships when the outgroup used to "root" the tree is highly divergent from the ingroup. This is especially the case when the outgroup has a different base composition than the ingroup. Unfortunately, in many instances, alternative less divergent outgroups are not available. In such cases, investigators must either target genes with attributes that minimize the problem (slowly evolving genes with stationary base compositions--which are often not ideal for estimating relationships among the more closely related ingroup taxa) or use inference models that are explicitly tailored to deal with an attenuated historical signal with a superimposed non-stationary base composition. In this paper we explore the problem both empirically and through simulation. For the empirical component we looked at the phylogenetic relationships among elasmobranch fishes (sharks and rays), a group whose closest living outgroup, the holocephalan Ghost fishes, are separated from the elasmobranchs by more than 100 million years of evolution. We compiled a data set for analysis comprising 10 single-copy nuclear protein-coding genes (12,096 bp) for representatives of the major lineages within elasmobranchs and holocephalans. For the simulation, we used an evolutionary model on a fixed tree topology to generate DNA sequence data sets which varied both in their distance to the outgroup, and in their base compositional difference between ingroup and outgroup. Results from both the empirical data set and the simulation, support the idea that deviation from base compositional stationarity, in conjunction with distance from the root can act in concert to compromise accuracy of estimated relationships within the ingroup. We tested several approaches to mitigate such problems. We found, that excluding genes with overall faster rates and heterogeneous base compositions, while the least sophisticated of the methods evaluated, seemed to be the most effective.     

The expression of granulocyte/macrophage colony-stimulating factor in activated mouse lymphocytes declines with age

The expression of granulocyte/macrophage colony-stimulating factor (GM-CSF) was studied in spleen lymphocytes isolated from male C57BL/6J mice of 6, 20, and 29 months of age. GM-CSF expression (biological activity and mRNA level) was maximum after culturing the lymphocytes for 45 hr with concanavalin A and phorbol myristate acetate. The induction of both GM-CSF activity and mRNA levels was observed to decline over 60% between 6 and 29 months of age. The age-related decline in the level of GM-CSF paralleled the age-related decline in the mRNA levels of interleukin-2 and interleukin-3.     

Structures of Streptococcus pneumoniae PiaA and Its Complex with Ferrichrome Reveal Insights into the Substrate Binding and Release of High Affinity Iron Transporters

Iron scarcity is one of the nutrition limitations that the Gram-positive infectious pathogens Streptococcus pneumoniae encounter in the human host. To guarantee sufficient iron supply, the ATP binding cassette (ABC) transporter Pia is employed to uptake iron chelated by hydroxamate siderophore, via the membrane-anchored substrate-binding protein PiaA. The high affinity towards ferrichrome enables PiaA to capture iron at a very low concentration in the host. We presented here the crystal structures of PiaA in both apo and ferrichrome-complexed forms at 2.7 and 2.1 Å resolution, respectively. Similar to other class III substrate binding proteins, PiaA is composed of an N-terminal and a C-terminal domain bridged by an α-helix. At the inter-domain cleft, a molecule of ferrichrome is stabilized by a number of highly conserved residues. Upon ferrichrome binding, two highly flexible segments at the entrance of the cleft undergo significant conformational changes, indicating their contribution to the binding and/or release of ferrichrome. Superposition to the structure of Escherichia coli ABC transporter BtuF enabled us to define two conserved residues: Glu119 and Glu262, which were proposed to form salt bridges with two arginines of the permease subunits. Further structure-based sequence alignment revealed that the ferrichrome binding pattern is highly conserved in a series of PiaA homologs encoded by both Gram-positive and negative bacteria, which were predicted to be sensitive to albomycin, a sideromycin antibiotic derived from ferrichrome.     

Actinomycetes inducing phytotoxic or fungistatic activity in a Douglas-fir Forest and in an adjacent area of repeated regeneration failure in Southwestern Oregon

Actinomycetes were isolated from the upper 1 - 3 cm of the soil layer in a well-developed forest and in an adjacent clearcut area where Douglas-fir [Pseudotsuga menziesii (MIRB.) Franco] regeneration had been impaired for two decades. The population density in the clearcut area was two times as high as that in the forested area. The percentage of actinomycetes that inhibited seed germination of the test plants was significantly higher in isolates obtained from the clearcut area than in those obtained from the forested area, and isolates from the clearcut showed five times the phytotoxic effect of those from the forest. Some actinomycete isolates, 4 % from the clearcut and 2.6 % from the forest, significantly reduced in vitro growth of two common ectomycorrhizal fungi of Douglas-fir,Laccaria laccata andHebeloma ovstuliniforme. Two actinomycete isolates from the clearcut reduced fungal growth by 40 % and 73 %. Reduction of the nutrient in the growth medium did not affect the antifungal activity of the actinomycetes. The data support the idea that, along with other factors, phytotoxic and antifungal actinomycetes may suppress natural regeneration or establishment of planted seedlings - either directly or. indirectly - through inhibition of seed germination or of mycorrhizal fungi.     

Genetic mapping of quantitative trait loci affecting carcass and meat quality traits in Beijing ducks (Anas platyrhynchos)

Quantitative trait loci (QTL) for carcass and meat quality traits were detected in a sample of 224 progeny from four males in line VI and 12 females in line V of Beijing ducks. These lines were selected for high body weight at 42 days of age (line VI) or high egg production at 360 days of age (line V). Traits were weights of the carcass, head, neck, shanks, wings, legs, thighs, breast, heart, liver, crop, gizzard, abdominal fat (AFW) and skin fat, as well as fat thickness in the tail, and pH value, shear force, drip loss (DL) (%) and cooking loss (CL) (%) of the breast. Using a half-sib analysis with a multiple QTL model, linkage between the carcass and meat quality traits and 95 microsatellite markers was investigated. Eight genome-wide significant QTL for weight of crop, skin fat, liver, neck, shanks, wings, DL were detected on linkage groups CAU4 and CAU6. One genome-wide suggestive QTL and one chromosome-wide significant QTL for weight of breast were found on CAU1 and CAU4 respectively. Fifteen chromosome-wide suggestive QTL influencing weight of AFW, breast, crop, heart, carcass, thighs, liver, shanks, gizzard, fat thickness in tail, DL (%) and CL (%) were mapped on CAU2, CAU4, CAU5, CAU6, CAU7, CAU10 and CAU13. In addition, two linked QTL for weight of liver and DL (%) were located on CAU2 and CAU7 respectively. The detection of QTL in ducks is a step towards identification of genes influencing these traits and their use for genetic improvement in this species.     

Long COVID and its Management

The pandemic of COVID-19 is the biggest public health crisis in 21^st Century. Besides the acute symptoms after infection, patients and society are also being challenged by the long-term health complications associated with COVID-19, commonly known as long COVID. While health professionals work hard to find proper treatments, large amount of knowledge has been accumulated in recent years. In order to deal with long COVID efficiently, it is important for people to keep up with current progresses and take proactive actions on long COVID. For this purpose, this review will first introduce the general background of long COVID, and then discuss its risk factors, diagnostic indicators and management strategies. This review will serve as a useful resource for people to understand and prepare for long COVID that will be with us in the foreseeable future.     

Indigenous ecological knowledge and natural resource management in the cultural landscape of China’s Hani Terraces

Indigenous ecological knowledge (IEK) can contribute to the management of local ecosystems and landscapes. Cultural landscapes are produced by and reflect the long-term interactions between humans and nature in indigenous societies. Yunnan Province, located in southwestern China, is the homeland of many ethnic groups, and is also a refuge for numerous species of wild plants and animals. Indigenous people in Yunnan, who have rich ecological knowledge, play an important role in the conservation of local biodiversity and the region’s unique terraced agricultural landscapes. We used the Hani people and their outstanding cultural landscape of rice terraces in Yuanyang County of Yunnan Province as a case study to describe their worldview and discuss their formation of IEK; their roles in the preservation of rice landraces and in pest regulation; their management of water, forest, and soil resources; and the vertical landscape pattern and resource-circulation system that has evolved in the areas managed by the Hani. We also discuss the challenges and threats facing the Hani, their IEK, and their cultural landscape, as well as discuss the potential for integration of the Hani’s IEK with modern conservation efforts.