6-Hydroxydopamine induced impairment of Pavlovian conditioning in the rabbit

This study employed bilateral, intraventricular injections of 6-hydroxydopamine (6-HDA) to examine the effects of monoamine depletion on Pavlovian conditioning of the rabbit's nictitating membrane response. 6-HDA produced dose-dependent and highly correlated decreases in the rate of acquisition of conditioned responses and in the telencephalic content of 5-HT, DA, and NE. At the highest dose of 6-HDA (1340 g), 5-HT, DA, and NE were reduced by 42, 48, and 89%, respectively, and the number of trials required to achieve criterion acquisition was increased by 123%. Control experiments established that the highest dose of 6-HDA: 1) had no effect on the unconditioned nictitating membrane reflex; 2) had no effect on the threshold of the conditioned stimulus for eliciting conditioned responses; and 3) produced only a small, less than 5%, decrease in nonassociative responding. It was concluded that decreases in 5-HT, DA, and NE can impair associative learning without altering sensory or motor function.Special issue dedicated to Dr. Morris H. Aprison.     

小脑皮层在兔瞬膜条件反射过程中的调制作用

以音调结合气流刺激兔角膜的训练建立瞬膜条件反射,在条件反射率刚达90%,连续出现三组的学习初始阶段,电解损毁小脑半球第六小叶皮层使 D-I 核的学习相关性电活动和瞬膜条件反射消除,但不影响“非条件”反射,而在经一周巩固训练的动物,损毁小脑皮层上述区域不发生影响。D-I 核的细胞自发电活动在学习初期和记忆巩固时期也有所不同。在学习后期,D-I 核的细胞自发电活动频率减低,和在学习初期与损毁小脑皮层后的频率变化相似。实验结果表明:在瞬膜条件反射过程中,以小脑皮层为主导,对瞬膜条件反射的产生和D-I 核的学习相关性电活动具有调制作用。随着记忆巩固过程,D-I 核脱离皮层的控制而发展成为这一学习模式的记忆痕迹基础部位。     

A Mathematical Model of the Cerebellar-Olivary System II: Motor Adaptation Through Systematic Disruption of Climbing Fiber Equilibrium

The implications for motor learning of the model developed in the previous article are analyzed using idealized Pavlovian eyelid conditioning trials, a simple example of cerebellar motor learning. Results suggest that changes in grPkj synapses produced by a training trial disrupt equilibrium and lead to subsequent changes in the opposite direction that restore equilibrium. We show that these opposing phases would make the net plasticity at each grPkj synapse proportional to the change in its activity during the training trial, as influenced by a factor that precludes plasticity when changes in activity are inconsistent. This yields an expression for the component of granule cell activity that supports learning, the across-trials consistency vector, the square of which determines the expected rate of learning. These results suggest that the equilibrium maintained by the cerebellar-olivary system must be disrupted in a specific and systematic manner to promote cerebellar-mediated motor learning.     

Identification of a new contingency-based response in honey bees (Apis mellifera) through revision of the proboscis extension conditioning paradigm

The two experiments reported present new information in the area of classical conditioning experiments with honey bees. Experiment 1 establishes a single unconditioned stimulus (US) technique as a preferred technique for conditioning of the proboscis extension response. Experiment 1 further identifies a new head turn response which occurs when the standard compound US technique is used. Experiment 2 demonstrates that the newly identified head turn response is contingency-based and provides important new response to the repertoire of honey bee learning experiments.     

Studies of aluminum neurobehavioral toxicity in the intact mammal

Summary 1. Aluminum (Al) has been implicated in neurotoxic syndromes in several conditions, including Alzheimer's disease (AD). The developmental stage of the mammalian brain most susceptible to Al was determined in rabbits systemically exposed to Al during the prenatal, postnatal, or second month or for 1 month as adults or as aged subjects. Eyeblink reflex classical conditioning showed an Al-induced learning deficit only in the adult and aged rabbits.2. 4-Aminopyridine, which was reported to improve learning in AD subjects, attenuated this Al-induced learning deficit.3. Conditioned eyeblink acquisition is slower in AD subjects than controls, supporting the Al-loaded rabbit as a model of some AD effects.4. To determine if the Al-loaded rabbit modeled the AD cholinergic deficit, acetylcholine (Ach) overflow was measured in rabbit hippocampus using microdialysis. Aluminum pretreatment reduced basal and potassium-stimulated Ach overflow compared to controls.5. Acetylcholine overflow increased as control rabbits acquired the conditioned eyeblink reflex, then subsequently decreased, although conditioned eyeblink performance continued. In contrast, Al-loaded rabbits showed a delay in conditioned eyeblink acquisition and greatly attenuated Ach overflow. The Al-induced attenuation of Ach overflow may contribute to the Al-induced learning deficit.6. Brain Al entry was studied using microdialysis of blood, brain, and lateral ventricle. Aluminum rapidly entered the brain and lateral ventricle. Frontal cortical Al was greater than lateral ventricular Al, suggesting that Al primarily enters the brain through the cerebral microvasculature.7. The brain/blood Al ratio was always significantly less than 1. This ratio was influenced by the Al form administered, brain site and animal species. Thus, there appears to be an active process moving Al out of brain extracellular fluid (ECF).8. Brain and blood dialysate Ach concentrations were not different after cyanide addition to the dialysate, supporting the conclusion that an active process moves Al out of brain ECF.     

家兔精子膜蛋白rSP10在大肠杆菌中的高效表达及其抗血清的制备

为研究家兔精子膜蛋白rSP10在精子膜上的定位及其免疫原性,将不含编码信号肽序列的rsp10基因插入表达载体pET30a中,N端具有His6肽的融合蛋白re-rSP10得到高效表达,表达产物达细菌总蛋白的67%。经DEAE柱层析纯化表达产物,re-rSP10,产量约为50mg/mL培养物。Western实验结果表明,精子膜蛋白多克隆抗体能识别re-rsp10,说明大肠杆菌表达的re-rSP10具有免疫原性。用纯化的re-rSP10免疫雌性兔,得到re-rSP10专一性多克隆抗血清。将re-rSP10专一性多克隆抗血清加入获能精子中,发现SP10专一性多克隆抗血清严重影响获能精子的运动并且表现为剂量依赖性,但获能精子凝集现象并不明显。     

表达猪瘟病毒E2蛋白的重组腺病毒的构建及其在兔体内的免疫原性分析

为了构建猪瘟重组腺病毒载体疫苗,通过细菌内同源重组法构建了含有猪瘟病毒E2基因的重组腺病毒rAdV-E2.测定其一步生长曲线,同时用间接免疫荧光试验和Western blotting检测外源基因表达,然后用rAdV-E2免疫家兔,免疫后6周用猪瘟兔化弱毒疫苗株(c株)进行攻击,攻毒后3 d取其脾脏,用实时荧光定量RT-PCR检测C株病毒RNA.结果表明,该重组腺病毒传至第10代时,毒价可达1.0×1010TCID<,50/mL;外源基因可在其中得到稳定表达;rAdV-E2接种兔免疫后2周产生猪瘟特异性抗体,免疫后5 W抗体达到峰值,攻毒后rAdV-E2接种兔和C株接种兔均未出现定型热反应,从其脾脏也未检测到C株病毒RNA,而野生型腺病毒接种兔均出现了定型热反应,并且从其脾脏检测大量C株病毒RNA,其含量达到了103拷贝/μL以上.由此表明,rAdV-E2可望开发为猪瘟候选疫苗.     

脂肪酸脱氢酶基因在兔体内表达的生物学效应研究

目的研究脂肪酸脱氢酶基因在兔子体内的生物效应,探索不饱和脂肪酸与兔子免疫的相互作用。方法用壳聚糖(CS)和壳聚糖的聚乙烯亚胺(PEI)、聚乙二醇(PEG)修饰产物(mPEG-O-CS-PEI),对含有脂肪酸脱氢酶基因的真核表达质粒VRMFat-1进行包裹,肌肉注射新西兰白兔,每两周采取抗凝血,检测血液中免疫细胞数量的变化情况,利用气相色谱仪检测动物组织中脂肪酸的含量变化,并通过荧光定量PCR检测免疫细胞内免疫相关基因的表达情况。结果两组实验兔组织中的n-3不饱和脂肪酸含量显著高于对照组(P<0.05),其TLR4、CD3、IL-4和IL-6基因表达水平显著升高(P<0.05)。结论转入的脂肪酸去饱和脱氢酶基因能够在实验兔体内正常表达,初步证明不饱和脂肪酸对兔子的固有免疫和获得性免疫机能均有明显的增强作用。     

Expression and localization of GhH6L,a putative classical arabinogalactan protein in cotton （Gossypium hirsutum）

Arabinogalactan proteins （AGPs） are a large family of highly glycosylated of hydroxyproline-rich glycoproteins that play important roles in plant growth, development, and signal transduction. A cDNA encoding a putative classical AGP named GhH6L was isolated from cotton fiber cDNA libraries, and the deduced protein contains 17 copies of repetitive motif of X-Y-proline-proline-proline （where X is serine or alanine and Y is threonine or serine）. Northern blotting analysis and quantitative RT-PCR results showed that it was preferentially expressed in 10 days post-anthesis （dpa） fibers and was also developmentally regulated. A promoter fragment was isolated from cotton （Gossypium hirsutum） by genome walking PCR. Expression of β-glucuronidase （GUS） gene under the GhH6L promoter was examined in the transgenic Arabidopsis plants; only petiole and pedicel were stained, no staining was detected in other tissues. Subcellular localization indicated that GhH6L was localized to the plasma membrane and in the cytoplasm. These data further our understanding of GhH6L as well as shed light on functional insight to GhH6L in cotton.     

Tracking Auxin Receptors Using Functional Approaches

Functional approaches toward the identification of auxin receptors developed along two major lines: the isolation and characterization of mutants or transgenic plants affected in their responses to the hormone and the study of early auxin effects at the cell level such as expression of specific genes or modifications of plasma membrane properties. The combination of these approaches with those aiming at the molecular characterization of auxin binding proteins as putative auxin receptors allowed to bring further insight into the mechanisms of auxin perception by plant cells. Studies of membrane responses to auxin clearly demonstrated the existence of elementary response chains to auxin at the plasma membrane, the activation of auxin responsive proteins leading to changes in the membrane potential via the stimulation of the proton pump ATPase or the modulation of ion channels. A two-component model is proposed for the organization of functional auxin perception units at the plasma membrane, comprising an auxin-binding moiety related to the major auxin-binding protein from maize (ZmER-abp1), associated to a transmembrane protein. Current research investigates the relevance of this model and tries to assess whether early responses at the plasma membrane share common perception or transduction steps with gene expression responses and participate in more integrated biological responses to auxin.     

Cloning and characterization of the OsNramp family from Oryza sativa,a new family of membrane proteins possibly implicated in the transport of metal ions

The mammalian Nramp1 protein is an integral membrane protein expressed exclusively in macrophages, where it plays a critical role in the ability of these cells to destroy ingested microbes. The bactericidal mechanism of action of Nramp1 remains unknown. We report the identification and characterization of cDNA clones corresponding to three homologues of the mammalian Nramp1 gene from the genome of Oryza sativa, OsNramp1, OsNramp2, and OsNramp3. These three genes encode a novel group of highly similar hydrophobic polypeptides sharing between 64% and 75% sequence similarity, that show similar hydropathy profiles, and predicted secondary structure, including the same number, position, and sequence characteristics (including conserved charges) of transmembrane domains. Together, these define a highly conserved membrane associated hydrophobic core. The three plant proteins show a remarkable degree of sequence similarity with their mammalian counterpart (60% to 70% similarity), including primary and secondary structure elements previously described in ion transporters and channels. Expression studies in normal plant tissues indicate that while OsNramp1 is expressed primarily in roots, and OsNramp2 is primarily expressed in leaves, OsNramp3 is expressed in both tissues. The recent discovery that the yeast Nramp homologue SMF1 functions as a manganese transporter raises the exciting possibility that OsNramp encodes a family of metal ion transporters in plants.     

植物多酚氧化酶的研究进展

阐述了多酚氧化酶的分子结构、生物功能、基因表达等方面的研究进展.     

Cloning of a Novel Rat Gene, DB83, That Encodes a Putative Membrane Protein

Using a partial cDNA sequence and a 5'-RACE technique, we isolateda novel cDNA from rat liver referred to as DB83. DB83 had fourhydrophobic trans-membrane domains and one N-myristoylationsite as well as multiple possible phosphorylation sites. Thedb83 gene was highly expressed in the liver and significantlyin brain, lungs and kidneys. We suggest that DB83 is a tissue-specificputative membrane protein.     

Expression of Chlamydia trachomatis inclusion membrane protein genes IncB and IncC in Escherichia coli

In this study, we have cloned the Chlamydia trachomatis genes incB and incC into the expression plasmid vectors from pET series for the subsequent isolation of recombinant proteins. As a result, we have obtained the first full-length recombinant C. trachomatis proteins IncB and IncC, which can be used for following antibody production and for study of their protein-protein interaction.