Release of heat pretreatment-induced dormancy in lettuce seeds by ethylene or cytokinin in relation to the production of ethylene and the synthesis of 1-aminocyclopropane-1-carboxylic acid during germination

The germination of lettuce (Lactuca sativa L.) seeds was greatly reduced when the seeds were heated at 97°C for 30 h prior to imbibition. This dormancy was effectively released when ethylene (1–100 ppm) or benzyladenine (BA) (0.005–0.05 mM) was applied during the imbibition period. Ethylene was not required during the early part of imbibition, but was essential during the period immediately prior to radicle protrusion. Treatment with 1-aminocyclopropane-1-carboxylic acid (ACC) (0.1–10 mM) stimulated germination, but was not as effective as ethylene or cytokinin treatment. During the germination of nondormant lettuce seeds, ethylene production increased rapidly and reached a peak at 24 h, which coincided with the emergence of the radicle, and then declined; the level of ACC increased as ethylene production rate increased, but remained at a high level after radicle protrusion. In heat-pretreated dormant lettuce seeds, the increases in percent germination, ethylene production, and ACC levels were all delayed and lower than those of nondormant seeds, and these increases were accelerated by treatment with ethylene or cytokinin.     

碳量子点对模式植物拟南芥的生物效应研究

以模式植物拟南芥（Arabidopsis thaliana（L.）Heynh）为材料,从生理及分子层面研究碳量子点（Carbon quantum dots,CQDs）对拟南芥生物效应的影响。结果显示,CQDs能被拟南芥根部吸收并连续运输到叶片,对种子萌发率无明显影响,但能显著促进幼苗主根伸长和株重的增加。幼苗叶片叶绿体中色素含量随CQDs浓度的升高而显著降低。脯氨酸与丙二醛含量随CQDs浓度的升高呈先上升后下降趋势。超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性随CQDs浓度的升高呈先上升后下降趋势,在抗氧化酶系统中起主导作用;叶片内源过氧化氢（H₂O₂）的积累随CQDs浓度的升高而升高,具有显著的浓度依赖效应。与其他纳米材料处理不一样的是,硫同化及胁迫相关基因在CQDs处理后表达量下调,这可能与CQDs粒子本身的特性有关。     

溶液流动对等电溶菌酶晶体生长的影响

本文对等温自由生长和强制性溶液生长的等电溶菌酶的晶体形态进行了研究,发现这些形态变化与溶液相的流动密切相关,指出生物晶体生长停止是由于生长晶体周围的溶质贫乏造成的;通过某些手段减薄或消除这一溶质贫乏区,就可以保证晶体的持续生长。本文的研究对改善大尺寸晶体的生长提供了一条途径。     

无机营养对春小麦抗旱适应性的影响

本文研究了无机营养对春小麦一些抗旱适应性的影响,主要包括:渗透调节的大小和变化过程、可溶性糖的积累、脯氨酸的积累、叶片导度的变化、离体叶片的失水速率、叶面积和耗水量的变化、根系生长和根/植冠值,并且分析了各个处理植株的水分利用效率(WUE)和产量的变异。认为,在干旱条件下,无机营养对于春小麦不同器官、不同生理功能,并不都具有一致的作用。有的利于提高植株的抗旱性,有的可以改变一些适应性产生的时间和发展过程,有的则不利于植株的抗旱性。通过综合分析,提出旱地施肥使作物增产的主要原因是,营养元素满足了作物生长所需,促进了根系发育,利于吸收水分、维持水分平衡和正常生理功能,但对作物自身的耐旱性并没有产生显著影响。     

Differences in the In Vitro and In Vivo 5-Hydroxytryptamine Extraction Performance Among Three Common Microdialysis Membranes

The present study summarizes the results of an in vitro and in vivo comparison of the apparent 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid, and 3,4-dihydroxyphenylacetic acid dialysis performance of three types of membrane frequently used in intracerebral microdialysis experiments. The dialysis fiber types examined were a regenerated cellulose Cuprophan (GF), a proprietary polycarbonate ether (CMA), and a polyacrylonitrile/sodium methallylsulfonate copolymer (HOSPAL). The experiments unexpectedly revealed that the HOSPAL membrane-equipped probes displayed clearly aberrant 5-HT diffusion dynamics compared with GF and CMA probes, demonstrable not only in vitro, but also in in vivo experiments. In vitro, the GF and CMA membrane-equipped probes exhibited maximum relative recovery for 5-HT already in the first 20-min sample, whereas the 5-HT recovery of HOSPAL probes increased in a very slow and protracted manner over a period of a little less than 2 h. The GF and CMA probes further displayed an immediate washout of 5-HT when the probes were subsequently transferred to artificial CSF only-containing medium (no 5-HT), whereas approximately 2 h was required to yield near-total extinction of dialysate 5-HT with the standard HOSPAL probes. In vivo, the rat ventral hippocampal dialysate 5-HT output responses to K+ (100 mM) infusion, to Ca2+ omission, and to systemic 8-hydroxy-2-(di-n-propylamino)tetralin injection were all markedly retarded and blunted when HOSPAL instead of GF membrane-equipped probes were used. However, the 5-hydroxyindoleacetic acid and 3,4-dihydroxyphenylacetic acid extraction in vitro and in vivo were comparable using either of the membrane types.(ABSTRACT TRUNCATED AT 250 WORDS)     

High-mobility group and other nonhistone substrates for nuclear histoneN-acetyltransferase

A variety of nonhistone proteins and polyamines has been studied for their substrate activity for nuclear histone N-acetyltransferase. Nonhistone chromatin high-mobility group (HMG) proteins are found to be as good a substrate for the enzyme as histones. The enzyme also acetylates spermidine and spermine. However, protamine, bovine serum albumin, and ubiquitin are not substrates. Chymotryptic peptides of histone and HMGs retained about 64% of the substrate activity, but trypsin treatment reduced the substrate activity by more than 85%. Both N-acetyltransferase activities for HMGs and histones are copurified through salt extraction, polyethylene glycol fractionation, and chromatography on DEAE-cellulose, phosphocellulose columns, and a HPLC anionic-exchange column. The highly purified nuclear histone acetyltransferase shows similar optimal pH and ping-pong kinetics for both HMGs and histones. The Km for HMG is 0.25 mg/ml. HMGs are able to accept the acetyl group from isolated acetyl-enzyme intermediate. Denatured gel analysis shows that HMG 1 and HMG 2 are the major proteins acetylated. High salt concentrations, mononucleotides, and DNA, which inhibit histone substrate activity of the enzyme, also inhibit HMG substrate activity. These observations suggest that there is a major nuclear N-acetyltransferase which is responsible for the acetylation of both histones and HMGs and perhaps also of spermine and spermidine. Thus the regulation of the structure and function of chromatin through postsynthetic acetylation can be achieved by a single nuclear N-acetyltransferase.     

JmjC-KDMs KDM3A and KDM6B modulate radioresistance under hypoxic conditions in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC), the most frequent esophageal cancer (EC) subtype, entails dismal prognosis. Hypoxia, a common feature of advanced ESCC, is involved in resistance to radiotherapy (RT). RT response in hypoxia might be modulated through epigenetic mechanisms, constituting novel targets to improve patient outcome. Post-translational methylation in histone can be partially modulated by histone lysine demethylases (KDMs), which specifically removes methyl groups in certain lysine residues. KDMs deregulation was associated with tumor aggressiveness and therapy failure. Thus, we sought to unveil the role of Jumonji C domain histone lysine demethylases (JmjC-KDMs) in ESCC radioresistance acquisition. The effectiveness of RT upon ESCC cells under hypoxic conditions was assessed by colony formation assay. KDM3A/KDM6B expression, and respective H3K9me2 and H3K27me3 target marks, were evaluated by RT-qPCR, Western blot, and immunofluorescence. Effect of JmjC-KDM inhibitor IOX1, as well as KDM3A knockdown, in in vitro functional cell behavior and RT response was assessed in ESCC under hypoxic conditions. In vivo effect of combined IOX1 and ionizing radiation treatment was evaluated in ESCC cells using CAM assay. KDM3A, KDM6B, HIF-1α, and CAIX immunoexpression was assessed in primary ESCC and normal esophagus. Herein, we found that hypoxia promoted ESCC radioresistance through increased KDM3A/KDM6B expression, enhancing cell survival and migration and decreasing DNA damage and apoptosis, in vitro. Exposure to IOX1 reverted these features, increasing ESCC radiosensitivity and decreasing ESCC microtumors size, in vivo. KDM3A was upregulated in ESCC tissues compared to the normal esophagus, associating and colocalizing with hypoxic markers (HIF-1α and CAIX). Therefore, KDM3A upregulation in ESCC cell lines and primary tumors associated with hypoxia, playing a critical role in EC aggressiveness and radioresistance. KDM3A targeting, concomitant with conventional RT, constitutes a promising strategy to improve ESCC patients’ survival.Subject terms: Predictive markers, Cancer     

Statures in Han populations of China

<正>Dear Editor,Shortly after initiating the"Physical Anthropological Research on Han Chinese"research project,we applied uniform sampling methods as well as methods and instruments of measurement to obtain a complete set of measurements of physical anthropological indicators among Han populations across China.Among these measurements,body stature was a key indicator.Currently,there should be reliable     

The Unique GGA Clathrin Adaptor of Drosophila melanogaster Is Not Essential

The Golgi-localized, γ-ear-containing, ARF binding proteins (GGAs) are a highly conserved family of monomeric clathrin adaptor proteins implicated in clathrin-mediated protein sorting between the trans-Golgi network and endosomes. GGA RNAi knockdowns in Drosophila have resulted in conflicting data concerning whether the Drosophila GGA (dGGA) is essential. The goal of this study was to define the null phenotype for the unique Drosophila GGA. We describe two independently derived dGGA mutations. Neither allele expresses detectable dGGA protein. Homozygous and hemizygous flies with each allele are viable and fertile. In contrast to a previous report using RNAi knockdown, GGA mutant flies show no evidence of age-dependent retinal degeneration or cathepsin missorting. Our results demonstrate that several of the previous RNAi knockdown phenotypes were the result of off-target effects. However, GGA null flies are hypersensitive to dietary chloroquine and to starvation, implicating GGA in lysosomal function and autophagy.