Biodegradation of trichloroethylene and toluene by indigenous microbial populations in soil.

The biodegradation of trichloroethylene (TCE) and toluene, incubated separately and in combination, by indigenous microbial populations was measured in three unsaturated soils incubated under aerobic conditions. Sorption and desorption of TCE (0.1 to 10 micrograms ml-1) and toluene (1.0 to 20 micrograms ml-1) were measured in two soils and followed a reversible linear isotherm. At a concentration of 1 micrograms ml-1, TCE was not degraded in the absence of toluene in any of the soils. In combination, both 1 microgram of TCE ml-1 and 20 micrograms of toluene ml-1 were degraded simultaneously after a lag period of approximately 60 to 80 h, and the period of degradation lasted from 70 to 90 h. Usually 60 to 75% of the initial 1 microgram of TCE ml-1 was degraded, whereas 100% of the toluene disappeared. A second addition of 20 micrograms of toluene ml-1 to a flask with residual TCE resulted in another 10 to 20% removal of the chemical. Initial rates of degradation of toluene and TCE were similar at 32, 25, and 18 degrees C; however, the lag period increased with decreasing temperature. There was little difference in degradation of toluene and TCE at soil moisture contents of 16, 25, and 30%, whereas there was no detectable degradation at 5 and 2.5% moisture. The addition of phenol, but not benzoate, stimulated the degradation of TCE in Rindge and Yolo silt loam soils, methanol and ethylene slightly stimulated TCE degradation in Rindge soil, glucose had no effect in either soil, and dissolved organic carbon extracted from soil strongly sorbed TCE but did not affect its rate of biodegradation.     

Rates of apparent photosynthesis,respiration and dry matter accumulation in maize canopies

The rates of canopy apparent photosynthesis (P_C) and canopy respiration (R_c) were studied during vegetation season in two erectophile and two planophile hybrids of maize (Zea mays L.) grown at two canopy densities [7.5 plants m^-2 (HD) and 4.5 plants m^-2 (LD)]. Large differences in P_C, R_c, R_C/P_C, leaf area index (LAI), dry matter accumulation and grain yield were found among hybrids and plant densities. Variations in P_C and R_C were associated mainly with changes in LAI. There was also found change in P_C per unit LAI with time. The average R_C/P_C was 28.9 % for all treatments throughout the vegetation season. P_C and R_C per unit dry matter were higher in LD than in HD and decreased throughout the measurement period. The HD stand had higher P_C and yield in hybrids with erectophile foliage, whereas LD stand had higher P_C after male tetrad and got higher yield in hybrids with planophile foliage. Only R_C in hybrids of the two foliage types was higher under HD than under LD throughout the vegetation period.     

Post-repolarization block of cardiac sodium channels by saxitoxin.

Phasic block of rat cardiac Na+ current by saxitoxin was assessed using pulse trains and two-pulse voltage clamp protocols, and the results were fit to several kinetic models. For brief depolarizations (5 to 50 ms) the depolarization duration did not affect the rate of development or the amplitude of phasic block for pulse trains. The pulse train data were well described by a recurrence relation based upon the guarded receptor model, and it provided rate constants that accurately predicted first-pulse block as well as recovery time constants in response to two-pulse protocols. However, the amplitudes and rates of phasic block development at rapid rates (> 5 Hz) were less than the model predicted. For two pulse protocols with a short (10 ms) conditioning step to -30 mV, block developed only after repolarization to -150 mV and then recovered as the interpulse interval was increased. This suggested that phasic block under these conditions was caused by binding with increased affinity to a state that exists transiently after repolarization to -150 mV. This "post-repolarization block" was fit to a three-state model consisting of a transient state with high affinity for the toxin, the toxin bound state, and the ultimate resting state of the channel. This model accounted for the biphasic post-repolarization block development and recovery observed in two-pulse protocols, and it more accurately described phasic block in pulse trains.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isolation and identification of a novel tandemly repeated DNA sequence in the centromeric region of human chromosome 8

EcoRI subclones, designated as 50E1 and 50E4, were independently obtained from a cosmid clone previously mapped to the centromeric region of human chromosome 8. Southern blot hybridization analyses suggested that both subclones contain repetitive DNA sequences different from the chromosome 8 specific alphoid DNA. DNA sequence analysis of the 704 bp insert of 50E1 and the 1, 962 bp insert of 50E4 revealed that both inserts contained tandemly repeated units of 220 bp. Fluorescence in situ hybridization studies confirmed these two subclones to be specifically located on the centromeric region of chromosome 8. A 220 bp consensus sequence, derived from nine monomeric repeats, showed no significant homology to alphoid consensus sequences or to other currently known human centromeric DNA sequence. Furthermore, no significant homology was found with any other DNA sequence deposited in the EMBL or GenBank databases, indicating that this chromosome 8 specific repetitive DNA sequence is novel. From slot blot experiments it was estimated that 0.013% of the human genome comprises 1,750 of these monomeric repeats, residing on the centromeric region of chromosome 8 in tandem array(s).     

Long-term changes in Noctiluca scintillans blooms along the Chinese coast from 1933 to 2020

Noctiluca scintillans is one of the most common harmful algal species and widely known due to its bioluminescence. In this study, the spatial distribution, seasonal variations, and long-term trends of N. scintillans blooms in China and the related drivers were analyzed and discussed. From 1933 to 2020, a total of 265 events of N. scintillans blooms were recorded in Chinese coastal waters, with a total duration of 1052 days. The first N. scintillans bloom occurred in Zhejiang in 1933, and only three events were recorded before 1980. From 1981 to 2020, N. scintillans caused harmful algal blooms (HABs) almost every year, both the average duration and the proportion of multiphase HABs showed an increasing trend. 1986–1992, 2002–2004, and 2009–2016 were the three peak periods with a frequency of no less than five events of N. scintillans blooms per year. In terms of spatial distribution, N. scintillans blooms spread from the Southeast China Sea to the Bohai Sea after 2000, Guangdong, Fujian, and Hebei were the three provinces with the highest numbers of recorded events of N. scintillans blooms. Moreover, 86.8% of the events of N. scintillans blooms occurred in spring (March, April, and May) and summer (June, July, and August). Among environmental factors, the dissolved inorganic phosphate, dissolved silicate and chemical oxygen demand were significantly correlated with the cell density of N. scintillans during N. scintillans blooms, and most of N. scintillans blooms were recorded in the temperature range of 18.0–25.0°C. Precipitation, hydrodynamics, water temperature, and food availability might be the main factors affecting the spatial–temporal distribution of N. scintillans blooms along the Chinese coast.     

基于差异基因表达谱的Microbacterium sp. XT11降解黄原胶潜能挖掘

为挖掘微杆菌(Microbacterium sp.)XT11在黄原胶降解过程中起关键作用的功能基因,预测黄原胶降解通路,利用转录组测序技术对该菌株在不同碳源培养条件下的转录本进行测序,对差异基因进行功能富集分析。结果表明,菌株XT11以葡萄糖为对照组,以黄原胶为碳源时可获得上调差异基因213个。显著上调的基因主要富集在聚糖降解、淀粉和蔗糖代谢途径、ABC转运、苯丙氨酸代谢、丙酮酸代谢五个KEGG途径。碳水化合物活性酶(Carbohydrate-active enzymes, CAZymes)功能注释表明,位于同一基因簇上的4个CAZymes基因和黄原胶降解直接相关,其余的CAZymes基因具有潜在的黄原胶降解活性。此外,预测到磷酸转移酶系统(phosphotransferase system, PTS)和ABC转运途径(ABC transporters)参与了胞外黄原胶降解中间产物的跨膜转运。挖掘了菌株XT11中黄原胶降解过程中的功能基因,并阐述了菌株XT11的黄原胶降解通路。     

异叶三宝木的二萜成分及抗菌活性研究

为研究异叶三宝木(Trigonostemon heterophyllus)的二萜成分及其抗菌活性,采用硅胶柱层析、凝胶柱层析、高效液相色谱对萃取物进行分离纯化,结合现代波谱技术对所得化合物进行结构鉴定,并通过牛津杯法和2倍稀释法检测化合物对革兰氏阴性菌大肠杆菌(Escherichia coli)以及革兰氏阳性菌肺炎双球菌(Pneumococcus)的生长抑制活性和MIC值。从异叶三宝木中分离得到了6个化合物,包括5个二萜类, 1个木脂素类,分别鉴定为trigonochinene E (1)、neoboutomannin (2)、6,9-O- dedimethyltrigonostemone (3)、stelltian B (4)、3,4-secosonderianol (5)、biondinin A (6)。化合物1、2、3、5对大肠杆菌有抑制作用,MIC值分别为9.375、18.75、18.75、18.75 μg/mL。化合物2、3、4、6为首次从该种植物中分离得到,化合物4为首次从该属植物中分离得到。除化合物4外,其他化合物都有一定的抗菌活性,且化合物1、2、3对大肠杆菌抑制作用强于阳性对照硫酸卡那霉素。     

四种主要大豆食叶害虫种群空间分布型及其应用研究

通过分层随机与连片调查获得114个样本．利用微机分别对豆天蛾卵和豆天蛾．银纹夜蛾．棉铃虫．豆灰蝶及混合种群的幼虫．进行了4种频次分布型检验和6项聚集度指标的测定．结果表明．上述害虫在豆田内均属零集分布．中分析了聚集原因．提出了“Z”字型10样点,每样点以1／3m双行为单位的抽样方法．确立了在两种允许误差下的抽样数量．进行了序贯抽样分析。     

花生种子老化相关蛋白质的初步研究

本文以粤油 116花生(Arachis hypogaea L.)为材料,对不同处理种子的除子叶“种胚”(以下简称“种胚”)的蛋白质进行了研究.实验结果表明,当花生种子活力下降到一定程度时,其“种胚”内出现一种新蛋白质( pI6.2、MW 10 KD),随种子老化程度加深,含量逐渐增多.我们认为该蛋白质与花生种子老化存在着一定的相关关系,可作为该种子老化的标志.     

Blockage of MDM2-mediated p53 ubiquitination by yuanhuacine restrains the carcinogenesis of prostate carcinoma cells by suppressing LncRNA LINC00665

Prostate cancer (PCa) is a challenging issue for men's health worldwide due to its uncontrolled proliferation and high metastatic potential. Increasing evidence has supported plant extracts and natural plant derivatives as promising antitumor therapy with less toxic side effects. Yuanhuacine is an active component isolated from Daphne genkwa and can effectively suppress the tumorigenesis of several cancers. However, its role in PCa remains unclear. In this study, yuanhuacine dose-dependently inhibited the proliferation and induced apoptosis of PCa cells. Moreover, yuanhuacine also restrained the invasion and migration of PCa cells. Mechanically, yuanhuacine decreased the ubiquitination and degradation of p53 protein, and ultimately increased p53 levels, which was regulated by inhibiting the phosphorylation and total protein levels of mouse double minute 2 (MDM2). Moreover, elevation of MDM2 reversed the suppressive efficacy of yuanhuacine in PCa cell viability, invasion, and migration. The network pharmacologic and bioinformatics analysis confirmed that MDM2 might be a common target of D. genkwa and LINC00665. Furthermore, yuanhuacine inhibited LINC00665 expression. Upregulation of LINC00665 reversed yuanhuacine-mediated inhibition in MDM2 protein expression and suppressed p53 levels by enhancing its ubiquitination in yuanhuacine-treated cells. Importantly, the inhibitory effects of yuanhuacine on cell viability and metastatic potential were offset after LINC00665 elevation. Together, the current findings highlight that yuanhuacine may possess tumor-suppressive efficacy by inhibiting LINC00665-mediated MDM2/p53 ubiquitination signaling. Therefore, this study indicates that yuanhuacine may be a promising candidate for the treatment of PCa.