北京鸭中脑网状结构内神经核团的形态学及细胞构筑研究(二)

用 10只北京鸭脑的 Nissl染色连续切片 ,在光镜下观察了分布于中脑网状结构内的红核、脚桥被盖核、中脑深核、外侧丘系核、外侧丘系腹侧核、乳头状核等的形态学及细胞构筑。结果表明 :(1)红核和中脑深核均未分出明显亚核 ;(2 )脚桥被盖核分成两个亚核 ,与其它禽类有异 ;(3 )首次观察到外侧丘系核的尾段有一个深染的结构 ;(4 )北京鸭的外侧丘系腹侧核及乳头状核与其它禽类相似。     

大鼠视前内侧区的传入性神经纤维联系,HRP,EB,NY法研究

本文应用轴突逆行运输HRP、EB、NY研究大鼠视前内侧区的传入性神经纤维联系。所用三种示踪剂结果基本一致。结果为:在外侧隔核、外侧嗅束核、杏仁内侧核、下丘脑外侧区、下丘脑腹内侧核和乳头体前腹核内观察到密集的标记细胞。在杏仁皮质核、杏仁中央核、下丘脑室旁核、下丘脑后核、弓状核、乳头体上核、丘脑腹核尾侧部、未定带、腹侧被盖区、脚间核、中缝正中核和背核内观察到较多标记细胞。在中脑中央灰质腹侧部、兰斑核、外侧臂旁核及海马腹下角内观察到少数标记细胞。     

北京鸭中脑网状结构内神经核团的形态学细胞构筑研究（二）

用10只北京鸭脑的Nissl染色连续切片，在光镜下观察了分布于中脑网状结构内的红核、脚桥被盖核、中脑深核、外侧丘系核、外侧丘系腹侧核、乳头状核等和形态学及细胞构筑。结果表明：（1）红核和中脑深核均未分出明显亚核；（2）脚桥被盖核分成两个亚核，与其它禽类有异：（3）首次观察到外侧丘系核的尾段有一个深染的结构；（4）北京鸭的外侧丘系腹侧核及乳头状核与其它禽类相似。     

豚鼠脑桥被盖部位HRP逆行标记的传入联系

本研究应用HRP微电泳技术,将HRP注射至豚鼠脑桥的腹侧被盖和背侧被盖,追踪其逆行传入投射。将HRP注射至脑桥腹侧被盖后,中脑上丘腹侧的中脑水管周围灰质和网状结构交界处(MSR),具有较密集的标记神经元。此外,在下丘腹侧的楔状核(MLR)、三叉神经脊束核、延髓网状巨细胞核、前庭内和外侧核、蓝斑及其腹侧的网状结构部分以及脊髓颈膨大灰质,也观察到了标记细胞。将HRP注射至脑桥背侧被盖后,脑桥尾侧网状核和延髓巨细胞网状核的标记神经元较多,前庭内、外侧核和外侧楔束核也见到标记细胞,中脑部位仅在红核及其附近见到少量标记细胞。蓝斑及其腹侧的网状结构部分和脊髓灰质未见标记细胞。     

树鼩脑干儿茶酚胺神经元的分布

应用FAGLU荧光组化技术观察了树鼩脑干儿茶酚胺神经元(简称CA神经元)的位置分布及其形态特征。结果表明,CA神经元主要分布于下列核区:延髓的腹外侧网状核(LRN),孤束核(Sol);脑桥的面神经核(nVll).脑桥尾侧网状校(PnC),第四脑室顶外侧壁,蓝斑(Lc),脑桥头端与中脑尾端移行部的中缝背核(DR)、中央上核(cs),腹外侧臂旁核(VLPB)、中央灰质腹侧(Vcg);中脑的黑质(SN)、和腹侧被盖区(VTA)。     

大鼠三叉神经脊束核吻侧亚核背内侧部及邻接的外侧网状结构的传出投射——WGA-HRP顺行追踪研究(中脑核—丘脑投射通路研究之二)

在已探明三叉神经中脑核神经元中枢突向三叉神经脊束核吻侧亚核的背内侧部(Vodm)及邻接的网状结构(LRF)投射的基础上,本文作者用WGA—HRP顺行标记法追踪了Vodm和其邻接的LRF传出投射的终止部位,以期探索Vme—丘脑通路中第三级神经元的所在。结果发现Vodm及邻接的LRF除投射到一些脑神经运动核、臂旁核、下橄榄主核腹肢内端外,还发现了前人未曾注意到的沿三叉神经感觉主核内缘存在且向腹侧伸延的一个带状区内有浓密的标记终末终止。此标记终末带区在上橄榄核背侧,三叉神经运动核腹侧以及三叉神经感觉主核的背内侧部等处增大,而上橄榄核背侧及三叉运动核腹侧的终末区以往并无人注意到在此有与之相应的核团。     

大鼠脑干到前额叶皮质的传入投射——WGA-HRP法研究

用WGA-HRP法研究了25只大鼠前额叶皮质的脑干传入投射。在前扣带回背部、前边缘区及岛叶无颗粒皮质背部注射WGA-HRP后,脑干中的逆行标记细胞大致可分为三类。第一类为单胺类神经元集中的核团,其中蓝斑、腹侧被盖区、黑质致密部、中缝背核、中央上核及尾侧线形核等广泛投射到前额叶皮质各部,而外侧网状核、连合核、中缝大核、A_4、A_5、臂旁核、黑质网状部及颅侧线形核投射到前额叶皮质各部的数量不同。外侧网状核、连合核、中缝大核、A_4、A_5到前额叶皮质的投射文献上尚未见报道。第二类为与眼肌运动有关的核团,如E-W核、导水管周灰质、中脑网状结构及脑桥吻侧网状核。第三类为与感觉有关的核团,如臂旁核、三叉神经感觉主核及连合核。     

猫丘脑中央外侧核的皮质下传入联系

本实验用HRP逆行性轴浆运输技术,对猫丘脑中央外侧核的传入纤维联系及其局部定位关系进行了观察。投射至丘脑中央外侧核尾侧区的主要核团包括:外侧膝状体腹核背侧带、丘脑网状核特别是它的背侧部、上丘深层,以同侧为主。板内核、丘脑下部外侧区和黑质网状部神经元的轴突终止在同侧丘脑中央外侧核吻侧区。丘脑中央外侧核全长的传入起自脑干网状结构和前庭神经核,呈双侧投射。前者以同侧为主,后者以对侧占优势。同侧未定带,顶盖前区、动眼神经核周围的细胞群、对侧三叉神经感觉主核、楔束核、薄束核以及小脑齿状核内也含有少量标记细胞。我们还观察到HRP注射中心区位于中央外侧核并扩散至丘脑腹前核者,同侧脚内核含大量HRP阳性细胞,而Gudden被盖腹侧核内充满密集的标记终末。这些结果表明,丘脑中央外侧核可能涉及多种感觉和运动功能。     

神经特异性转录因子DAT1 mRNA在大鼠中枢神经系统的定位

目的 观察神经特异性转录因子(DAT1)在大鼠中枢神经系统中的定位。方法 原位杂交组织化学染色。结果 在大鼠中枢神经系统中，DAT1 mRNA阳性反应产物主要位于胞质和突起内，DAT1 mRNA阳性神经元可见于大脑、小脑、丘脑、脑干、脊髓。强阳性信号主要出现于嗅球、梨状皮质、纹状皮质、内嗅皮质、海马CA1区、齿状回、丘脑后外侧核、红核、被盖背侧核、延髓中央网状核、三叉神经运动核、舌下神经核、迷走神经核、楔束外核、疑核等部位；中等强度着色主要分布于大脑皮质Ⅱ～Ⅵ层、海马CA2区和CA3区、杏仁核、苍白球、内侧膝状体、外侧膝状体、视上核、未定带、弓状核、室旁核、黑质、中脑网状核、脑桥网状核、巨细胞网状核、外侧网状核、斜方体内侧核、前庭神经核、蜗神经背核、楔束核、中缝背核；在隔核、乳头体前核、上丘浅灰质层、下丘中央核、下丘外侧核、中央灰质、三叉神经中脑核、三叉脊束核、孤束核、下橄榄核、中央上核、小脑顶核、小脑间置核、小脑外侧核、脊髓灰质及丘脑的大部分核团可见弱的阳性细胞。结论 DAT1广泛分布于大鼠中枢神经系统内，其分布与多巴胺能神经分布密切相关，提示该基因对大鼠中枢神经系统活动，尤其是多巴胺能神经递质活动具有重要的调节功能。     

多巴胺能中脑——杏仁核通路

本实验用神经元逆行荧光标记和单胺荧光组化联合法研究了大白鼠杏仁核内多巴胺能神经纤维的起源及投射特点。一侧杏仁核注射荧光标记物后,同侧黑质致密部背内份和被盖腹侧区背外份有较多的多巴胺神经元被标记。黑质外侧部、A_8群所在部位及对侧黑质致密部和被盖腹侧区亦有少数多巴胺细胞被标记。同侧黑质致密部和被盖腹侧区内还观察到少数非多巴胺能逆行标记细胞。杏仁核与同侧尾壳核、伏隔核或额前皮质配对注射不同荧光标记物后,同侧被盖腹侧区与黑质致密部的背侧区与腹侧区之间有不少多巴胺神经元被逆行荧光双标记。     

Experimental reproduction of an Enterococcus cecorum infection in Pekin ducks

Enterococcus cecorum (EC) was thus far only known as a pathogen for broilers and broiler breeders. Recently there was evidence of EC field outbreaks in Pekin duck flocks in Germany. In this study we experimentally reproduced an EC infection in Pekin ducks. At 12 days post hatch, groups of Pekin ducks were infected orally, via the thoracic air sac or intravenously with 1.5 × 10⁹ colony-forming units (CFU) of EC per bird or via the air sac with 8.5 × 10⁵ or 8.5 × 10⁷ CFU per bird. Ducks of the intravenously infected group showed 100% mortality after 2 days post infection. The air sac inoculated high-dose group exhibited a mortality rate of 67%. Birds that were infected with 8.5 × 10⁵ and 8.5 × 10⁷ CFU showed 6.7% mortality after 7 days post infection. Dead birds displayed pneumonia, airsacculitis, pericarditis and splenitis and EC was re-isolated from these organs. Surviving birds of all groups apart from the orally infected ducks demonstrated clinical signs such as huddling, reduced mobility and diarrhoea. Furthermore, they showed gross pathological lesions including airsacculitis and splenitis and lower bodyweights than the control group at necropsy on days 7, 14 and 21 post infection. The present study clearly confirms that EC is pathogenic for Pekin ducks after experimental infection via the intravenous route or the respiratory tract. EC therefore has to be considered as an emerging avian pathogen not only in broilers but also in Pekin ducks.     

Influenza virus subtypes in aquatic birds of eastern Germany

Summary We report the findings of a 12-year surveillance study (1977–89) of avian influenza A viruses in eastern Germany. Viruses were isolated directly from feral ducks (n=236) and other wild birds (n=89); from domestic ducks (n=735) living on a single farm; and from white Pekin ducks (n=193) used as sentinels for populations of wild aquatic birds; mainly sea birds. The efficiency of virus isolation was 9.9% overall, with considerable variability noted among species: 8.7% in wild ducks, 0.9% in other feral birds and 38% in Pekin ducks. Use of sentinel ducks in wild pelagic bird colonies improved virus detection rates fivefold, suggesting that this approach is advantageous in ecological studies. Among the 40 different combinations of hemagglutinin (HA) and neuraminidase (NA) subtypes we identified, H6N1 predominated (23.6% for all avian species), followed by H4N6 (11%). Among individual species, the frequency profiles favored H2N3 (20.8%) and H4N6 (20.3%) in feral ducks; H7N7 (22.3%), H4N6 (24.4%) and H2N3 (10.4%) in Pekin ducks used as sentinels; and H6N1 (34.8%) and H6N6 (15.1%) in domestic ducks maintained on a single farm. By relying on sentinel birds for serological assays, it was possible to trace an influenza season in feral swan populations, beginning in August and continuing through the winter months. Comparison of subtype distribution of influenza viruses for Europe and North American showed significant differences. This supports the fact of two geographically distinct gene pools of influenza viruses in birds connected with their distinct flyways of each hemisphere. The high frequency of isolation of H2 influenza viruses is of considerable interest to those interested in the recycling of this subtype in humans. Similarly the frequent isolation of H7N7 influenza viruses raises concern about reservoirs of potentially pathogenic influenza virus for domestic poultry. Our results confirm the existence of a vast reservoir of influenza A viruses in European aquatic birds, which possesses sufficient diversity to account for strains that infect lower animals and humans.This article is dedicated to the memory of Dr. Herbert Sinnecker who died in 1991 at the age of 61. He was the Director of the Institute of Viral Zoonosis in the former German Democratic Republic (GDR). It was Herbert Sinnecker's forsight and understanding of the need to resolve the origin of human and animal influenza pandemics that initiated the studies described in this article. He developed novel epidemiological and ecological methods that permitted definition of the influenza virus gene pool in central Europe. The unification of Germany made it possible to publish this article; otherwise, the studies encouraged and organized by H. Sinnecker would have been lost to the scientific community.     

Development of an in-house ELISA for detection of antibodies against Enterococcus cecorum in Pekin ducks

ABSTRACT

Enterococcus cecorum (EC) is known to cause skeletal lesions in broiler chickens and also systemic infections in Pekin ducks. Despite the importance of the pathogen, there is still a lack of serological diagnostic tools for the detection of EC infections. Here we describe the development of an in-house indirect enzyme-linked immunosorbent assay (ELISA) for the detection of EC-specific antibodies and its application by examination of 67 sera from experimentally infected Pekin ducks, 710 field samples from four Pekin duck breeder flocks previously vaccinated with inactivated vaccines, and 80 samples from commercial Pekin ducks coming from vaccinated parent flocks. All groups that had been experimentally inoculated via the air sac route were positive in the new ELISA, with significantly (P?≤?0.05) increased mean sample/positive (S/P) ratios of 0.71–2.70 at days 7, 14 and 21 post-infection, while orally inoculated ducks and the EC-free control group remained negative with mean S/P ratios of 0.0–0.15. Antibodies were also detected in each of four vaccinated Pekin duck breeder flocks; 67.8% of the samples were antibody positive. The highest S/P ratios were found between 16 and 26 weeks (median S/P ratios from 0.15 to 1.03), but antibodies were still detected in some serum samples in weeks 61–67 post-hatch. No antibodies were detected in the commercial Pekin ducks. Antibody development in the ducks may be influenced by the composition of the inactivated vaccine. The new ELISA provides a useful tool for investigations of response to EC infections and vaccinations.     

Observations on host range and control of goose virus hepatitis

A number of experiments were done with a strain of goose hepatitis virus (isolated from sick goslings in the Netherlands in 1969. This virus was easily grown in embryonating eggs of the Muscovy duck (Cairina moschata) as well as in embryonating goose eggs. It also proved possible to adapt it to White Pekin duck eggs. The susceptibility of embryonating eggs obtained by crossing Muscovy drakes with Pekin ducks was intermediate between that of eggs from the two parental breeds. It was not possible to adapt goose hepatitis virus to growth in chicken embryos. The sensitivity of goslings to the goose hepatitis virus was found to vary considerably according to the farms from which they came. These differences were caused by variations 'in the quantity of parentally derived antibodies. One day-old Muscovy ducklings appeared to be at least as sensitive to the virus as goslings. However, disease symptoms could not be produced with goose hepatitis virus in Pekin ducklings nor in ducklings obtained by crossing Muscovy drakes and Pekin ducks. Treatment with homologous immune serum protected susceptible goslings and Muscovy ducklings against the disease. Under farm conditions, mortality was reduced from 30 to 3%. A breeding flock of adult Muscovy ducks, which had by serum therapy survived a goose hepatitis infection at an early age, produced ducklings resistant to the goose hepatitis virus. Over 100 flocks of geese, totalling more than 6,000 birds, were actively immunized with goose hepatitis Virus. The progeny produced in the following breeding season resisted, almost without exception, a challenge at one day of age with virulent goose hepatitis virus.     

The use of conventional radiography and computer-assisted tomography as instruments for demonstration of gross pathological lesions in the cranium and cerebrum in the crested breed of the domestic duck (Anas platyrhynchos f.dom.)

According to literature reports, the crested breed of the domestic duck (Anas platyrhynchos f. dom.) is described as a variety with high pre- and post-natal mortalities, malformations in skull and brain anatomy, and various central nervous deficiencies in affected birds. A detailed examination as to the cause and pathogenesis of these neurologic disorders has not yet been conducted, nor has an explanation concerning the inheritance of the feather crest been found. By using two non-invasive radiographic techniques, conventional radiography and computer-assisted tomography, living ducks were examined. Our studies have demonstrated that brain and skull anatomy of ducks of various breeds (Crested, Abacot Ranger, and German Pekin) can be well visualized using computer-assisted tomography. The Crested ducks investigated in this study showed abnormal fatty tissue deposits in the tentorium cerebelli, cranial malformations, and variable bone formations in the thickened hypodermis of the crest. In comparison with computer-assisted tomography, only parts of the skull changes were detected with conventional radiography; in no case could fat bodies be seen with this imaging method. An increase of the cranial capacity in the Crested ducks compared with other breeds examined (Abacot Ranger, German Pekin ducks) was found in morphometric studies carried out by computerassisted tomography. This increase of cranial capacity in Crested ducks results from an increase of the tentorial fatty depot during craniogenesis, as an enlargement of the fat body can influence cranium growth as long as the cranial bones are not yet fused. Thus, in comparison with other phenotypically similar domesticated birds like the crested chicken, the expression of the feather crest in domestic ducks demonstrates symptomatologic differences.     

Brightness and pattern discrimination deficits in the pigeon after lesions of nucleus rotundus

Summary Pigeons were trained to peck one of two discs on which were projected visual stimuli. One brightness and three pattern discrimination problems were presented. Correct responses were rewarded with grain. After the discriminations were learned, bilateral electrolytic lesions were placed stereotaxically in 13 birds, and sham operations were performed in three birds. Those birds with lesions in nucleus rotundus demonstrated severe deficits in performance of the visual discriminations. Following prolonged post-operative retraining, a gradual return to pre-operative levels of performance was observed. The post-operative relearning proceeded at a much slower rate than the pre-operative learning. Control birds with lesions in dorsal thalamus, telencephalon and mesencephalon, or sham operations, all showed considerable post-operative savings. On the basis of the anatomical, electrophysiological and behavioral data available at present, nucleus rotundus appears to be a thalamic relay of visual information from optic tectum to telencephalon in the bird.Abbreviations AnLen Ansa Lenticularis - Ant Comm Anterior Commissure - D Th Dorsal Thalamus - LFB Lateral Forebrain Bundle - L Gd Lateral Geniculate Nucleus, Pars Dorsalis - L Gv Lateral Geniculate Nucleus, Pars Ventralis - OMT Occipito-Mesencephalic Tract - Op Ch Optic Chiasm - Op Tr Optic Tract - Ov Nucleus Ovoidalis - Pretec Pretectal Nuclei - Rot Nucleus Rotundus - Rot Ect Tr Rotundo-Ectostriatal Tract - Sept Septum - SMT Septo-Mesencephalic Tract - Spir Lat Nucleus Spiriformis Lateralis - Spir Med Nucleus Spirformis Medialis - St M Stria Medullaris - Sub-Pretect Subpretectal Nucleus - Tect Tectum - Tri Nucleus Triangularis - TTT Tecto-Thalamic Tract This research was supported in part by Grant NsG189-61 from the National Aeronautics and Space Administration and Contract DA49—193—MD—2397 from the Office of the Surgeon General, U.S. Army.     

Pathogenicity of two Egyptian H5N1 highly pathogenic avian influenza viruses in domestic ducks

Domestic ducks have been implicated in the dissemination and evolution of H5N1 highly pathogenic avian influenza (HPAI) viruses. In this study, two H5N1 HPAI viruses belonging to clade 2.2.1 isolated in Egypt in 2007 and 2008 were analyzed for their pathogenicity in domestic Pekin ducks. Both viruses produced clinical signs and mortality, but the 2008 virus was more virulent, inducing early onset of neurological signs and killing all ducks with a mean death time (MDT) of 4.1 days. The 2007 virus killed 3/8 ducks with a MDT of 7 days. Full-genome sequencing and phylogenetic analysis were used to examine differences in the virus genes that might explain the differences observed in pathogenicity. The genomes differed in 49 amino acids, with most of the differences found in the hemagglutinin protein. This increase in pathogenicity in ducks observed with certain H5N1 HPAI viruses has implications for the control of the disease, since vaccinated ducks infected with highly virulent strains shed viruses for longer periods of time, perpetuating the virus in the environment and increasing the possibility of transmission to susceptible birds.     

DDE feeding and plasma osmoregulation in ducks, guillemots, and puffins.

To assess the possibility that organochlorine pesticide disruption of osmoregulation is responsible for recent large kills of young seabirds, we have studied the effects of DDE feeding (10-250 ppm) on plasma osmoregulation and nasal gland function in the following species: mallared and white Pekin ducks (both Anas platyrhynchos), black guillemot (Cepphus grylle), and common (Fratercula arctica). Other investigators have recently reported that dietary DDE (10-1,000 ppm) inhibits nasal gland secretion in freshwater-maintained mallards; our initial experiments with white Pekins showed no such inhibition during either freshwater or seawater maintainance. Moreover, DDE had minimal effects on plasma electrolyte levels and total nasal gland Na-K-ATPase activities in all species studied. Liver DDE levels in experimental ducks and guillemots were comparable to those reported for seabirds found dead after kills; levels in starved experimental puffins were much higher. Thus DDE at environmental levels does not affect osmoregulation or nasal gland Na-K-ATPase either in ducks or in two species of oceanic birds.