维生素B_1对丙二醛修饰小牛血清白蛋白的影响

不同来源的活性羰基化合物(主要是非酶糖基化和脂质过氧化中间产物)能和多种蛋白发生交联反应,导致其结构的改变及功能的丧失.利用小牛血清白蛋白/丙二醛(BSA/MDA)这一蛋白羰基应激模式,检测不同浓度的MDA对BSA吸光和荧光的影响.同时,通过向BSA/MDA反应体系加入不同浓度的维生素B1(VB1),检测VB1对蛋白羰基修饰的抑制作用.实验结果表明,蛋白的羰基修饰生成了老年色素类荧光物质(APFs),同时使蛋白的羰基含量增加;VB1在一定程度上抑制了蛋白羰基含量的增加.     

A Bayesian Nonparametric Approach for Mapping Dynamic Quantitative Traits

In biology, many quantitative traits are dynamic in nature. They can often be described by some smooth functions or curves. A joint analysis of all the repeated measurements of the dynamic traits by functional quantitative trait loci (QTL) mapping methods has the benefits to (1) understand the genetic control of the whole dynamic process of the quantitative traits and (2) improve the statistical power to detect QTL. One crucial issue in functional QTL mapping is how to correctly describe the smoothness of trajectories of functional valued traits. We develop an efficient Bayesian nonparametric multiple-loci procedure for mapping dynamic traits. The method uses the Bayesian P-splines with (nonparametric) B-spline bases to specify the functional form of a QTL trajectory and a random walk prior to automatically determine its degree of smoothness. An efficient deterministic variational Bayes algorithm is used to implement both (1) the search of an optimal subset of QTL among large marker panels and (2) estimation of the genetic effects of the selected QTL changing over time. Our method can be fast even on some large-scale data sets. The advantages of our method are illustrated on both simulated and real data sets.     

Synthesis of a novel fluorescent probe based on 7‐nitrobenzo‐2‐oxa‐1,3‐diazole skeleton for the rapid determination of vitamin B12 in pharmaceuticals

A new fluorescent probe, 4‐N,N‐di(2‐hydroxyethyl)imino‐7‐nitrobenzo‐2‐oxa‐1,3‐diazole (HINBD) was synthesized in a single step with reasonably good yield. The water‐soluble HINBD emits strongly in the visible region (λ_ex = 479 nm, λ_em = 545 nm) and is stable over a wide range of pH values. It was found that vitamin B₁₂ (VB₁₂) had the ability to quench the fluorescence of HINBD, and the quenched fluorescence intensity was proportional to the concentration of VB₁₂. A method for VB₁₂ determination based on the quenching fluorescence of HINBD was thus established. Interference effects of various substances, including sugars, vitamins, amino acids, inorganic cations and some organic substances have been studied. Under optimal conditions, the linear range is 0.0–2.4 × 10^–5 mol/L. The determination limit is 8.3 × 10^–8 mol/L. The method was applied to measure VB₁₂ in pharmaceutical preparations with satisfactory results. Copyright © 2013 John Wiley & Sons, Ltd.     

N-acetylglucosaminyltranferase VB expression enhances beta1 integrin- dependent PC12 neurite outgrowth on laminin and collagen

N-acetylglucosaminyltransferase VB (GnT-VB, -IX) is a newly discovered glycosyltransferase expressed exclusively in high levels in neuronal tissue during early development. Its homolog, GnT-V, is expressed in many tissues and modulates cell-cell and cell-matrix adhesion. The ability of GnT-VB to regulate cell-matrix interactions was initially investigated using the rat pheochromocytoma PC12 neurite outgrowth model. PC12 cells stably transfected with GnT-VB consistently showed an enhanced rate of nerve growth factor (NGF)-induced neurite outgrowth on collagen and laminin substrates. Levels of TrkA receptor phosphorylation and downstream ERK activation induced by NGF were not influenced by GnT-VB expression. No significant difference was observed in the rate of neurite outgrowth when cells were cultured on non-coated culture dishes, indicating that integrin-ECM interaction is required for the stimulatory effects. Neurite outgrowth induced by manganese-dependent activation of beta1 integrin on collagen and laminin substrates, however, showed a significant increase in neurite length for the PC12/GnT-VB cells, compared with control cells, suggesting that the enhancement is most likely mediated by alteration of beta1 integrin-ECM interaction by GnT-VB. These results demonstrate that GnT-VB expression can modulate the rate of neurite outgrowth by affecting beta1 integrin-ECM interaction.     

The facilitatory influence of anterior cingulate cortex on ON-OFF response of tactile neuron in thalamic ventrobasal nucleus

The structures of limbic system have been found to modulate the auditory, visual and pain afferent signals in the related nuclei of thalamus. One of those structures is anterior cingulate cortex (ACC) that influences nocuous response of the pain-sensitive neurons in the ventropostero-lateral nucleus of thalamus. Thus, we inferred that ACC would also modulate tactile information at the thalamic level. To test this assumption, single units were recorded extracellularly from thalamic ventrobasal nucleus (VB). Tactile ON-OFF response and the relationship between different patterns of the responses and the parameters of tactile stimulation were examined. Furthermore, the influence of ACC on the tactile ON-OFF response was studied. ACC stimulation was found to produce a facilitatory effect on the OFF-response of ON-OFF neurons. It lowered the threshold of the off-response of that neuron, and therefore changed the response pattern or enhanced the firing rate of the OFF-response of the neuron. The study on receptive fields of ON-OFF neurons showed that the excitation of the ACC could change an ON-response on the verge of a receptive field into an ON-OFF response. The above results suggest that the ACC modulation sharpens the response of a VB neuron to a moving stimulus within its receptive field, indicating that the limbic system can modulate tactile ascending sensory information.     

腺苷钴胺素合成酶基因cobs 的克隆及其在产1,3-丙二醇菌中的应用

甘油脱水酶是催化由甘油到1,3-丙二醇过程中的关键酶,它需要在辅酶B_(12)存在的情况下才能有效的进行催化;而在此催化过程中甘油脱水酶会出现失活现象,研究表明辅酶B_(12)可以有效的促使甘油脱水酶复活。因此,辅酶B_(12)在由甘油生物催化生产1,3-丙二醇过程中起到非常重要的作用。本研究利用PCR扩增技术,从Escherichia K-12菌株中扩增出产VB_(12)关键酶—腺苷钴胺素合成酶基因cobs,其序列与NCBI上已经公布的序列比对,同源性为99.6%,将基因cobs与产1,3-丙二醇关键酶基因dhaB、yqhD在Klebsiella pneumoniae中共表达,发酵结果显示重组菌所需额外添加的VB_(12)由原始菌株的0.01 g/L下降到0.004 g/L。     

The low affinity binding sites of the vitamin D-dependent calcium-binding protein and their functional role in calcium transport

Calcium- and other divalent cation-binding properties of the vitamin D-dependent calcium-binding protein isolated from the duodenal mucosa of chicks were studied using the flow dialysis technique and ⁴⁵Ca. It was found that the calcium-binding protein along with the high affinity binding sites has approximately 40 low affinity binding sites with K_a of about 1000 M^?1. The low affinity sites possess of certain specificity towards binding of Ca. The affinity of the calcium-bindin protein for other divalent cations depends on the ionic radius. It is suggested that the low affinity binding sites of the calcium-binding protein take part in calcium transport organization across the intestinal epithelium.     

Mutagenic evaluation of clonazepam using in vitro and in vivo bacterial tests.

The mutagenicity of an anti-epileptic drug, clonazepam, and its metabolites was studied by three repair (rec, pol and uvr) assays and reversion (Ames') tests. No detectable induction of mutation could be found in any tests by them per se or via metabolism in rat and mouse.     

The pyruvate-lactate axis modulates cardiac hypertrophy and heart failure

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