Simrank: Rapid and sensitive general-purpose k-mer search tool

Background  

Terabyte-scale collections of string-encoded data are expected from consortia efforts such as the Human Microbiome Project . Intra- and inter-project data similarity searches are enabled by rapid k-mer matching strategies. Software applications for sequence database partitioning, guide tree estimation, molecular classification and alignment acceleration have benefited from embedded k-mer searches as sub-routines. However, a rapid, general-purpose, open-source, flexible, stand-alone k-mer tool has not been available.     

Arabidopsis type I metacaspases control cell death

Metacaspases are distant relatives of animal caspases found in protozoa, fungi, and plants. Limited experimental data exist defining their function(s), despite their discovery by homology modeling a decade ago. We demonstrated that two type I metacaspases, AtMC1 and AtMC2, antagonistically control programmed cell death in Arabidopsis. AtMC1 is a positive regulator of cell death and requires conserved caspase-like putative catalytic residues for its function. AtMC2 negatively regulates cell death. This function is independent of the putative catalytic residues. Manipulation of the Arabidopsis type I metacaspase regulatory module can nearly eliminate the hypersensitive cell death response (HR) activated by plant intracellular immune receptors. This does not lead to enhanced pathogen proliferation, decoupling HR from restriction of pathogen growth.     

Tunneling into a single magnetic atom: spectroscopic evidence of the kondo resonance

The Kondo effect arises from the quantum mechanical interplay between the electrons of a host metal and a magnetic impurity and is predicted to result in local charge and spin variations around the magnetic impurity. A cryogenic scanning tunneling microscope was used to spatially resolve the electronic properties of individual magnetic atoms displaying the Kondo effect. Spectroscopic measurements performed on individual cobalt atoms on the surface of gold show an energetically narrow feature that is identified as the Kondo resonance-the predicted response of a Kondo impurity. Unexpected structure in the Kondo resonance is shown to arise from quantum mechanical interference between the d orbital and conduction electron channels for an electron tunneling into a magnetic atom in a metallic host.     

蕃茄果实环裂性遗传效应及其与射裂、耐压性相关的初步研究

通过3个杂文组合、4个世代、1988～1990年3年试验结果数据,估算了蕃茄果实环裂性的遗传效应.表明控制蕃茄果实环裂的基因效应符合加性——显性遗传模型,杂种后代环裂性平均值以高环裂(不抗环裂)为超显性或介于双亲间偏于不抗环裂一边,环裂性的广义遗传力为64.6％.基因加性效应在不同品种组合间存在差异.环裂性与射裂性呈极显著的正相关;环裂性与耐压性、射裂性与耐压性分别是显著和极显著的负相关.故欲获得抗环裂、抗射裂、耐压的新品种,只需对其中一个性状进行直接选择,就能间接使其余两个性状相应得到改进,适于采用杂交、回交育种方法。     

Hassell-Rogers模型参数的简化回归计算

本文提出了Hasscll-Rogers模型中参数计算的一种简便方法。即先用Beddington提出的亚模型计算出a’和T_h,代入Hasscll-Rogers公式,再用一元回归求出m和c值。文中以玉米螟赤眼蜂在不同自身密度和寄主密度下寄生的实验数据作实例,用上述方法求出了Hasscll-Rogcrs模型的理论公式。对原数据的拟合效果经x~2检验显著适合。该算法与用Marquardt法在IBM-PC微机上计算所得结果也十分接近。     

应用抗O抗原单克隆抗体对692个沙门氏菌分离株的分群鉴定

应用抗沙门氏菌菌体抗原O_1、O_2、O_3、O_4、O_7、O_8、O_9,O_(11)、O_(12)、O_(19)一组单克隆抗体(单抗)对692个沙门氏菌分离株进行鉴定,结果A群4株、B群210株、C_1群61株、C_2群109株、D_1群119株、E群182株和F群7株.这一结果与用常规O血清进行的平行试验的鉴定结果一致.同时,这组单抗与172株非沙门氏菌分离菌株不反应.说明这组单抗可以取代常规O单因子血清和A-F群O多价血清用于沙门氏菌的分群鉴定。     

苏新棕壳蛋鸡自别雌雄配套系的研究——配套纯系(苏新A、B、C、D系)的培育

应用伴性遗传原理,以引进的鸡种为材料,根据其特点分成4个类型,分别采用自群繁殖、回交、测交等方法逐步提高基因纯合率,建立基本群.在选育过程中,大量繁殖,加大选择压,并建立若干家系,采用家系选择和个体选择相结合的方法,培育成功了苏新A、B、C、D4个纯系,A、B系带有纯合金色基因(ss),C、D系带来纯合银色基因(SS).各系500日龄入舍母鸡产蛋量均在210枚以上,蛋重57g以上,受精率90-95％,产蛋期淘汰率5-7％,蛋料比1:2.8左右。     

电超滤法(EUF)测定土壤钾素状况的合理性

通过化学方法提取的钾和电超滤方法提取的钾分别与作物吸钾量的相关性试验,证实了在水稻土钾素供应状况的研究方面,电超滤方法较之一般的化学提取方法无论从理论上还是在实际测定中都更具合理性。     

新城疫病毒的抗独特型单克隆抗体的研制——新城疫单克隆抗独特型疫苗研究(Ⅱ)

作者用纯化 FE_8和 LA_(15-6)2株抗新城疫病毒(NDV)中和性单抗(MAb_1)分别免疫 BALB/c /小鼠,经杂交瘤技术获得2株抗独特型单克隆抗体(MAb_2),分别命名为AFE_8Id_(16-6)和ALA_(15-6)Id.在血凝抑制阻断试验(BHI)中,2株MAb_2都能阻断FE_8MAb_1抑制NDV血凝活性,BHI效价分别达1:8和1:4.在中和抑制试验(NIT)中,2株MAb_2在 1:10～1:80稀释时均可特异地抑制FE_8MAb_1中和NDV的能力,使部分试验鸡胚死于NDV感染.这些结果不仅表明,2株MAb_2的抗原结合位点是针对FE_8MAb_1独特型决定簇的,而且提示它们的可变区构形和与FE_8MAb_1相结合的NDV抗原决定簇或其邻近结构相似.这2株MAb_2可用于新城疫单克隆抗独特型疫苗的研究。