家兔三叉神经终止核对颏舌肌肌电活动的调制作用

本工作在35只氨基甲酸乙酯麻醉、自主呼吸的家兔上观察了刺激三叉神经终止核(NTV)对颏舌肌肌电活动的影响。结果发现,电刺激NTV和NTV内微量注射谷氨酸钠都能使颏舌肌出现明显的易化效应。电刺激NTV背侧与腹侧时,颏舌肌肌电反应的潜伏期分别为5.9±0.7ms和3.0±0.4ms,电刺激舌下神经核时颏舌肌反应的潜伏期为2.2±0.2ms。结果提示三叉神经终止核的兴奋可加强颏舌肌的活动从而减小上呼吸道阻力。     

Subtractive phage display technology identifies zebrafish marcksb that is required for gastrulation

In the present study, we used a phage display technique to screen differentially expressed proteins from zebrafish post-gastrula embryos. With a subtractive screening approach, 6 types of single-chain Fv fragments (scFvs) were screened out from an scFv antibody phage display library by biopanning against zebrafish embryonic homogenate. Four scFv fragments (scFv1, scFv3, scFv4 and scFv6) showed significantly stronger binding to the tailbud embryos than to the 30%-epiboly embryos. A T7 phage display cDNA library was constructed from zebrafish tailbud embryos and used to identify the antigens potentially recognized by scFv1, which showed the highest frequency and strongest binding against the tailbud embryos. We acquired 4 candidate epitopes using scFv1 and the corresponding genes showed significantly higher expression levels at tailbud stage than at 30%-epiboly. The most potent epitope of scFv1 was the clone scFv1-2, which showed strong homology to zebrafish myristoylated alanine-rich C-kinase substrate b (Marcksb). Western blot analysis confirmed the high expression of marcksb in the post-gastrula embryos, and the endogenous expression of Marcksb was interfered by injection of scFv1. Zebrafish marcksb showed dynamic expression patterns during embryonic development. Knockdown of marcksb strongly affected gastrulation movements. Moreover, we revealed that zebrafish marcksb is required for cell membrane protrusion and F-actin alignment. Thus, our study uncovered 4 types of scFvs binding to zebrafish post-gastrula embryos, and the epitope of scFv1 was found to be required for normal gastrulation of zebrafish. To our knowledge, this was the first attempt to combine phage display technique with the embryonic and developmental study of vertebrates, and we were able to identify zebrafish marcksb that was required for gastrulation.     

研究报告: 斑马鱼“裂头病”病原的分离与鉴定及常见疾病诊断

目的 斑马鱼是生命科学研究中应用最广的实验动物之一,其健康状况关乎实验数据的质量和结果的可信度。2018年以来,中国斑马鱼鱼房内出现危害性极高的新型鱼病“裂头病”,其病原未知,防治困难。确定“裂头病”的病原,并提出鱼房管理健康建议,可帮助研究者防止鱼病带来的损失。方法 对“裂头病”病鱼脑组织进行病原分离,对分离的病原理化特征、16S rDNA同源性进行分析,采用回归感染试验确认病原菌。分析121例鱼病数据,总结中国斑马鱼鱼房各类常见疾病种类及发病因素。结果 确定“裂头病”病原为鮰爱德华氏菌。2017至2021年国内斑马鱼鱼房数据显示,50.4%的健康问题由非生物因素直接或者间接导致;致死率最高的问题是气体中毒。在已知病原中细菌性病原最为常见,占比83.46%。结论 “裂头病”病原为鮰爱德华氏菌。近一半鱼房健康问题是由非生物因素导致。致病率最高的为细菌性病原。因此,实验室日常工作中,加强设备维护,稳定优良水质,保证卫生管理措施,是防止鱼病发生的主要手段。     

The cDNA and genomic DNA organization of a novel toxin SHT-I from spider Ornithoctonus huwena

Spider venoms are complex mixtures of neurotoxicpeptides, proteins and low molecular mass organicmolecules. Their neurotoxic activity is due to the interac-tion of the venom components with cellular receptors, inparticular ion channels. Spider venoms have…     

Sequences of Transgene Insertion Sites in Transgenic F4 Common Carp

Transgenic Research -     

The EIM algorithm in the joint segregation analysis of quantitative traits

In this article, a new algorithm for obtaining the maximum likelihood estimators (MLEs) of parameters in the joint segregation analysis (JSA) of multiple generations of P1, F1, P2, F2 and F2:3 (MG5) for quantitative traits was set up. Firstly, owing to the fact that the component variance of the heterogeneous genotype in F2:3 included both the first-order genetic parameters (denoted by the means of distributions) and the second-order parameters, a simple closed form for the MLEs of the means of component distributions did not exist while the expectation and maximization (EM) algorithm was used. To simplify the estimation of parameters, the first partial derivative of the above variance on the mean in the sample log-likelihood function was omitted. However, this would be remedied by the iterated method. Then, variances of component distributions for segregating populations were partitioned into major-gene, polygenic and environmental variances so that the generally iterated formulae for estimating the means as well as polygenic and environmental variances of component distributions in the maximization step (M-step) of the EM algorithm were obtained. Therefore, the EM algorithm for estimating parameters in the JSA model for the MG5 was simplified. This is called the expectation and iterated maximization (EIM) algorithm. Finally, an example of the inheritance of the resistance of soybean to beanfly showed that the results of mixed inheritance analysis in this paper coincided with those in both Wang & Gai (2001) and Wei et al. (1989), so the EIM algorithm was appropriate.     

Urinary Levels of N-Nitroso Compounds in Relation to Risk of Gastric Cancer: Findings from the Shanghai Cohort Study

BackgroundN-Nitroso compounds are thought to play a significant role in the development of gastric cancer. Epidemiological data, however, are sparse in examining the associations between biomarkers of exposure to N-nitroso compounds and the risk of gastric cancer.MethodsA nested case-control study within a prospective cohort of 18,244 middle-aged and older men in Shanghai, China, was conducted to examine the association between urinary level of N-nitroso compounds and risk of gastric cancer. Information on demographics, usual dietary intake, and use of alcohol and tobacco was collected through in-person interviews at enrollment. Urinary levels of nitrate, nitrite, N-nitroso-2-methylthiazolidine-4-carboxylic acid (NMTCA), N-nitrosoproline (NPRO), N-nitrososarcosine (NSAR), N-nitrosothiazolidine-4-carboxylic acid (NTCA), as well as serum H. pylori antibodies were quantified in 191 gastric cancer cases and 569 individually matched controls. Logistic regression method was used to assess the association between urinary levels of N-nitroso compounds and risk of gastric cancer.ResultsCompared with controls, gastric cancer patients had overall comparable levels of urinary nitrate, nitrite, and N-nitroso compounds. Among individuals seronegative for antibodies to H. pylori, elevated levels of urinary nitrate were associated with increased risk of gastric cancer. The multivariate-adjusted odds ratios for the second and third tertiles of nitrate were 3.27 (95% confidence interval = 0.76–14.04) and 4.82 (95% confidence interval = 1.05–22.17), respectively, compared with the lowest tertile (P for trend = 0.042). There was no statistically significant association between urinary levels of nitrite or N-nitroso compounds and risk of gastric cancer. Urinary NMTCA level was significantly associated with consumption of alcohol and preserved meat and fish food items.ConclusionThe present study demonstrates that exposure to nitrate, a precursor of N-nitroso compounds, may increase the risk of gastric cancer among individuals without a history of H. pylori infection.     

光照和温度对氮饥饿及饱和营养条件下石莼(Ulva lactuca)的硝态氮吸收动力学影响

为探讨海藻养分吸收能力并以高效养分过滤器筛选为目标,以N饥饿和N饱和的石莼为材料,研究了3种光照及温度因子及其交互作用对不同N素营养限制状态下石莼NO3-吸收动力学特征的影响。结果表明:N饱和条件下,随着光照的增强,石莼对NO3-的最大吸收速率也增加;30℃条件下,光照强度的增加虽然使得其最大吸收速率提高,但Vmax/Km在中等光强下最大;20℃最有利于石莼对NO3-的吸收。N饥饿条件下,石莼对NO3-的吸收速率显著大于非饥饿状态。在10℃和20℃条件下,呈现与N饱和条件下相似的规律,但在30℃条件下,中等光强石莼对NO3-的最大吸收速率最高。在10℃和20℃条件下,增加光强促进石莼对NO3-的吸收,但30℃条件下光强的增加并未起到促进作用。饥饿状态下的石莼的NO3-吸收速率较高,当石莼吸收NO3-饱和时,依然可以以较低的速率继续吸收环境中的NO3-。     

不同年龄阶段马占相思( Acacia mangium)人工林营养元素的生物循环

对马占相思人工林6种营养元素(N、P、K、Ca、Mg、S)的含量、积累、分布和生物循环特点以及随林分年龄的变化趋势进行了研究.结果表明(1)林木不同组分营养元素含量的大小次序为树叶＞干皮＞活枝＞枯枝或树根＞干材;各组分和凋落物中营养元素含量以N最高,其次是Ca或K,然后是S和Mg,P最低;林地土壤中,以K的含量最高,其次是Ca、Mg、N和P,S最低;随林龄的增加,0～40cm土壤N、P和S含量呈增加趋势;(2)4年、7年生和11年生林分营养元素总积累量分别为1022.08、1997.08和2633.45 kg·hm-2,其中乔木层营养元素贮存量依次占73.64%、82.39% 和83.65%,林下植被层依次占13.74%、8.74%和6.20%,地表现存凋落物层依次占12.62%、8.87%和10.16%;乔木层以N积累量最大,占总贮存量的53.90%～60.07%,P最小,仅占0.90%～1.23%;(3)马占相思林中不同组分营养元素积累量的分配随林龄的增长发生变化,由4年生以树叶和树枝占主导,逐渐转移到7年生和11年生以干材和树皮为主导;(4)林分营养元素年积累量依次为7年生(235.06 kg·hm-2·a-1)＞11年生(200.26 kg·hm-2·a-1)＞4年生(188.16kg·hm-2·a-1);林木各组分营养元素年积累量总的变化趋势为树干＞树叶＞树枝＞根系＞树皮,同一组分各营养元素年积累量与各组分营养元素积累量变化顺序一致,即为N＞Ca＞K＞S＞M＞P;(5)林分营养元素年吸收量分别为382.35、432.04 kg·hm-2·a-1和403.15 kg·hm-2·a-1,年归还量分别为194.19、196.98 kg·hm-2·a-1和202.89 kg·hm-2·a-1,营养元素的循环系数分别为0.51、0.46和0.50,利用系数为0.51、0.26和0.18,周转期为3.88、8.35和10.86.可见,马占相思人工林早期营养元素利用率低,归还速率较快,林分生长到近熟期(11a)时营养元素的周转期较长,但其归还速率仍然较快,有利于林地地力的恢复、维持和提高.