Age-Related Changes of NADPH-Diaphorase Positivity in the Rat Rostral Migratory Stream

Summary Accumulating evidence confirms that nitric oxide (NO), a versatile diffusible signaling molecule, contributes to controling of adult neurogenesis. We have previously shown the timing of NADPH-diaphorase (NADPH-d) positivity within the rat rostral migratory stream (RMS) during the first postnatal month. The present study was designed to describe further age-related changes of NO presence in this neurogenic region. The presence of NO synthesizing cells in the RMS was shown by NADPH-d histochemistry and neuronal nitric oxide synthase (nNOS) immunohistochemistry. The phenotypic identity of nitrergic cells was examined by double labeling with GFAP and NeuN. Systematic qualitative and quantitative analysis of NADPH-d-positive cells was performed in the neonatal (P14), adult(5 months) and aging (20 months) rat RMS. 1. Nitrergic cells with different distribution pattern and morphological characteristics were present in the RMS at all ages examined. In neonatal animals, small, moderately stained NADPH-d-positive cells were identified in the RMS vertical arm and in the RMS elbow. In adult and aging rats a few labeled cells could be also detected in the RMS horizontal arm. NADPH-d-positive cells in adult and aging rats were characterized by long varicose processes and displayed dark labeling in comparison to the neonatal group. 2. Double immunolabeling has revealed that nNOS-immunoreactivity co-localized with that of NeuN. This indicates that nitrergic cells within the RMS are neurons. 3. Quantitative analysis showed that the number of NADPH-d-positive cells increases with advancing age. The presence of NO producing cells in the RMS of neonatal adult and aging rats indicates, that this proliferating and migratory area is under the influence of NO throughout the entire life of the animals.     

Fluoro Jade-B Detection of Dying Cells in the SVZ and RMS of Adult Rats After Bilateral Olfactory Bulbectomy

A novel fluorochrome, Fluoro-Jade B, was used to detect dying precursor cells in the subventricular zone (SVZ) and rostral migratory stream (RMS) of adult rats after bilateral olfactory bulbectomy and in control intact rats. The animals in experimental group were left to survive 3 days and from 3 till 16 months after surgical procedure. 1. In the control animals, Fluoro-Jade B positive cells were visible in the SVZ and within the whole extent of the RMS. The number of Fluoro-Jade B positive cells increased in the elbow in comparison to the rest parts of the RMS. 2. In the experimental animals surviving either 3 days or from 3 till 16 months after bilateral olfactory bulbectomy, Fluoro-Jade B positive cells displayed the similar pattern of distribution as in the control animals. However, some quantitative differences in the labeled cells number along the rostral migratory pathway appeared. 3. The average number of degenerating cells within the control SVZ and RMS was 26.24+/- 0.686. In bulbectomized animals, regardless of survival time, an insignificant increase of Fluoro-Jade B positive cells number occurred. We can conclude that dying of precursor cells is a physiological process running within the SVZ/RMS in both control and experimental animals. Moreover, this physiological process is not influenced by survival period after bilateral olfactory bulbectomy. Our results demonstrate Fluoro-Jade B as a useful marker of dying cells.     

Distinct bacterial dissemination and disease outcome in mice subcutaneously infected with Borrelia burgdorferi in the midline of the back and the footpad

Subcutaneous inoculation of mice with Borrelia burgdorferi, the causative agent of Lyme disease, results in established infection and the development of acute arthritis and carditis, hallmarks of human disease. Because conflicting results may originate from the site of subcutaneous inoculation, we addressed the dissemination capacity of spirochetes injected in the shoulder region versus the footpad. Spirochetes inoculated in the footpad disseminated to a lesser extent to distant organs, such as the ear and the heart. This resulted in distinct degrees of joint and cardiac inflammation at the peak of the disease. The differences eventually leveled out. These results suggest that caution must be exercised in the interpretation of results obtained with routes of inoculation that do not closely represent the natural site of infection.     

N-CWS灌胃对小鼠移植性肿瘤及免疫功能的影响

为了考察红色诺卡氏菌细胞壁骨架(Nocardia rubra cell wall skeleton,N-CWS)灌胃给药对小鼠的体内抑瘤效应及其免疫调节作用,采用小鼠肉瘤S_(180)的移植性肿瘤模型,检测N-CWS灌胃给药的抑瘤活性;同时观察N-CWS体内细胞毒作用和对正常小鼠的毒性、免疫器官重量、巨噬细胞(MΦ)吞噬功能及脾淋巴细胞转化的影响.结果显示,小鼠灌服N-CWS的LD_(50)＞1.2 g/kg;N-CWS 200、400、800 mg/kg剂量灌胃小鼠对S_(180)有明显的抑制作用,其抑瘤率分别为63.33%、71.11%、64.88%;与对照组比较,N-CWS可增加免疫器官重量和提升外周血白细胞数量、能明显提高小鼠MΦ的吞噬活性及显著提高淋巴细胞转化率(P＜0.05),同时N-CWS激活了的MΦ对肿瘤细胞的细胞毒效应亦明显增强(P＜0.05).因此N-CWS适用于口服给药,对小鼠移植性肿瘤有明显的抑制作用,其抗肿瘤作用可能与增强机体免疫功能有关.     

A mutation in the pericentrin gene causes abnormal interneuron migration to the olfactory bulb in mice

Precise control of neuronal migration is essential for proper function of the brain. Taking a forward genetic screen, we isolated a mutant mouse with defects in interneuron migration. By genetic mapping, we identified a frame shift mutation in the pericentrin (Pcnt) gene. The Pcnt gene encodes a large centrosomal coiled-coil protein that has been implicated in schizophrenia. Recently, frame shift and premature termination mutations in the pericentrin (PCNT) gene were identified in individuals with Seckel syndrome and microcephalic osteodysplastic primordial dwarfism (MOPD II), both of which are characterized by greatly reduced body and brain sizes. The mouse Pcnt mutant shares features with the human syndromes in its overall growth retardation and reduced brain size. We found that dorsal lateral ganglionic eminence (dLGE)-derived olfactory bulb interneurons are severely affected and distributed abnormally in the rostral forebrain in the mutant. Furthermore, mutant interneurons exhibit abnormal migration behavior and RNA interference knockdown of Pcnt impairs cell migration along the rostal migratory stream (RMS) into the olfactory bulb. These findings indicate that pericentrin is required for proper migration of olfactory bulb interneurons and provide a developmental basis for association of pericentrin function with interneuron defects in human schizophrenia.     

Effects of body condition and water temperature on Anguilla anguilla glass eel migratory behavior

Glass eels arriving from the sea use alternative migratory tactics, leading either to the colonization of rivers or to an early settlement in marine or estuarine habitats. In the field, the migration may be environmentally affected by water temperature and the migratory behavior could be physiologically dependent on the body condition (energetic status). To investigate how these environmental and physiological effects on the migration are behaviorally mediated, we experimentally tested the effects of changes in water temperature and body condition on locomotor activity (upstream swimming) and salinity preference of Anguilla anguilla glass eels. Low water temperature reduced significantly both locomotor activity and preference for freshwater, in accordance with field data showing that low water temperatures hinder both the estuarine migration and river recruitment. Glass eels switched from a freshwater- towards a saltwater-preference as their body condition decreased, confirming that the energetic status may affect the migratory behavior. We suggest that, in the wild, this condition-dependent change in salinity preference of low body condition glass eels induces an early settlement in marine or estuarine habitats. Such a behavioral shift, stopping the energy expenditure linked to river-oriented migratory behavior, may be adaptive by limiting the probability of death due to exhaustion. Our results show that the glass eel migratory behavior, through locomotor activity and salinity preference, may be controlled by interacting physiological and environmental factors.     

Stochastic dynamics of magnetosomes and a mechanism of biological orientation in the geomagnetic field

The rotations of nanoscopic magnetic particles, magnetosomes, embedded into the cytoskeleton are considered. Under the influence of thermal disturbances, a great number of magnetosomes are shown to move chaotically between two stable equilibrium positions, in which their magnetic moments are neither parallel nor antiparallel to the static Earth's magnetic field (MF). The random rotations attain the value of order of a radian. The rate of the transitions and the probability of magnetosomes to be in the different states depend on the MF direction with respect to an averaged magnetosome's orientation. This effect explains the ability of migratory animals to orient themselves faultlessly in long term passages in the absence of the direct visibility of optical reference points. The sensitivity to deviation from an "ideal" orientation is estimated to be 2-4 degrees. Possible involvement of the stochastic dynamics of magnetosomes in biological magnetic navigation is discussed.     

标记回收法确认我国北方地区草地螟的迁飞

为了证实草地螟Loxostege sticticalis L.（鳞翅目： 螟蛾科）由我国华北越冬区向东北迁飞危害的假说并提供直接的证据, 采用网捕成虫喷雾染料标记释放回收的方法,于2009年越冬代草地螟成虫盛发期间（6月1-4日）分别在内蒙古武川县（41.07°N, 111.42°E）和察右中旗（41.13°N, 112.58°E）的6个标放点共标记当地越冬代草地螟成虫约181万头并自然释放。标记释放后, 在东北、 西北和华北11个草地螟常发省（市、 区）组织各级监测预警部门利用虫情测报灯、 捕虫网和性诱剂诱捕器等多种器械进行回收, 先后于2009年6月7-29日在内蒙古科右中旗、 乌兰浩特、 扎兰屯分别回收到由察右中旗标记释放的成虫9头, 在辽宁省北票市回收到由武川县标记释放的成虫1头。标记释放点至回收点直线距离为725~1 117 km。这是迄今为止世界上确认的草地螟最远迁飞距离。这些证据不仅证实了我国越冬代草地螟成虫能从华北迁往东北危害, 而且为进一步了解草地螟的种群动态规律, 改善草地螟的预测预报技术提供了重要的科学依据。     

增大罐压提高脱氮假单胞菌发酵生产维生素B12的产量

【目的】提高发酵罐的罐压,增加维生素B12的产率。【方法】利用常规代谢通量分析(MFA)方法,对脱氮假单胞菌生产维生素B12的发酵过程进行研究。【结果】发现随着VB12合成速率的加快,磷酸烯醇式丙酮酸(PEP)羧化生成草酰乙酸(OAA)的通量明显加大,以满足维生素B12合成对前体的需求。根据该分析结果,对发酵工艺进行了改进,即在脱氮假单胞菌进入合成维生素B12阶段时,提高发酵罐的罐压,增加发酵液中二氧化碳的溶解度,从而强化了羧化回补途径。维生素B12的产率明显增加,发酵160 h的产物浓度为176 mg/L,比对照批次终浓度147 mg/L高出了19.7%。【结论】通过增大罐压提高了脱氮假单胞菌进入合成维生素B12的产量。