Corpus Callosal Abnormalities in Dogs

Background

Corpus callosal abnormalities (CCA) in dogs have been only sporadically reported and are poorly characterized.

Hypothesis/Objectives

To describe the clinical presentation and magnetic resonance imaging (MRI) characteristics of dogs with CCA.

Animals

Fifteen client‐owned dogs.

Methods

Retrospective study. Records of the contributing institutions were reviewed to identify dogs diagnosed with malformations affecting the corpus callosum (CC); cases in which the CCA was thought to be secondary were excluded.

Results

The most represented breeds were Staffordshire Bull Terriers (5/15) and Miniature Schnauzers (3/15; n = 3, 20%) and the mean age at time of presentation of 19 months (range 3–81 months). The clinical signs most commonly reported were adipsia/hypodipsia with associated hypernatremia (12/15), tremors (6/15), and seizures (6/15). Review of the MR images revealed that 10 dogs had absence of the rostral CC and hypoplasia of the caudal portion, 4 dogs had a diffusely hypoplastic and dysplastic CC, and 1 dog had a diffusely hypoplastic CC. In 14 cases, there was abnormal cortical development with fusion of the ventral frontal lobes and part of the diencephalon, indicating lobar holoprosencephaly.

Conclusions and Clinical Importance

Previous literature has mainly associated CCA with adipsia and only 12 of 15 dogs in the current series demonstrated this abnormality. There are different degrees of the malformation but in 10 dogs the rostral portion of the CC is most severely affected. Fourteen dogs have simultaneous fusion of the midline structures rostral to the CC; this region has several structures involved in thirst regulation and might explain this derangement.     

Effects of microglia-derived IL-1β on differentiation of OPCs in corpus callosum of septic neonatal rats

AIM: To explore whether IL-1β inhibits the oligodendrocyte precursor cell (OPCs) differentiation and affects axonal myelination. METHODS: One-day-old SD rats were randomly divided into control group and LPS group (48 rats in each group). The rats in LPS group were intraperitoneally injected with 1 mg/kg LPS. The rats in control group were injected with an equal volume of PBS. The rats in each group were further divided into 3 h, 24 h, 3 d, 7 d, 14 d and 28 d subgroups after injection. The expression of IL-1β and IL-1R₁ in the rat corpus callosum at 3 h, 24 h, 3 d, 7 d was determined by double immunofluorescence and Western blotting. The myelin basic protein(MBP) expression in the rat corpus callosum at 14 d, 28 d after injection was also measured. In vitro, primary OPCs culture was performed and divided into control group, 30 μg/L IL-1β group, 30 μg/L IL-1β+IL-1Ra group and 30 μg/L IL-1Ra group. The expression of MBP in the OPCs induced differentiation for 3 d was observed by double immunofluorescence and Western blotting. RESULTS: The expression of IL-1β and IL-1R₁ in the rat corpus callosum at 3 h, 24 h, 3 d, 7 d after LPS injection was obviously increased and the expression of MBP in the rat corpus callosum at 14 d, 28 d in LPS group was obviously decreased compared with control group in vivo. The level of MBP was significantly decreased after IL-1β treatment for 3 d in vitro. However, IL-1Ra (IL-1R inhibitor) reversed the down-regulation of MBP expression. IL-1β inhibited the expression of p-ERK, ERK over-expression reversed the down-regulation of MBP expression compared with IL-1β group. CONCLUSION: IL-1β inhibits the differentiation of OPCs, which may be involved in ERK pathways, thus leading to axonal hypomyelination in the corpus callosum of septic neonatal rats.     

条叶百合的离体多倍体诱导

为增强条叶百合的抗性,对其进行多倍体改良,利用不同浓度的秋水仙素附加2.00%二甲亚砜诱变离体培养条叶百合小鳞茎。结果表明:0.10%的秋水仙素溶液诱导效果好,直径1.4cm鳞茎变异率达100%,直径0.7cm鳞茎变异率达92%。经对4株疑似多倍体诱变株系的染色体检测,仅有1个变异株系中含有48条染色体,4倍体细胞占63%,对其切割分离和纯化培养,最终获得1个四倍体株系(2n=4x=48)。除观察到正常的染色体外,株系1、株系3和株系4约30%左右的细胞中含有数目不等的B染色体。     

Gender differences in the rat corpus callosum: An ultrastructure study

Sexual dimorphism exists at all levels of the nervous system, from genetic, anatomical and system levels. The sexual dimorphism in the axonal content of the corpus callosum (CC) has always been controversial; hence, the aim of this study was to analyse the differences in total, myelinated and unmyelinated axons density of various regions of the CC between male and female rats. To assess that, six pairs of adult male and female rats were perfused and the CC was removed and sectioned. Four sections from different subregions of the corpus callosum that represent the genu, anterior body, posterior body, and splenium, were stained, and electron microscopic images were captured using stereological guidelines. Later, the axons density for each subregion was calculated and compared between males and females. The findings of the present study indicated region‐specific differences in the myelinated, unmyelinated or the ratio of myelinated/total axons in the CC between male and female rats.     

条叶百合和垂花百合高效快繁体系的建立

以条叶百合和垂花百合的鳞片为外植体,应用均匀设计法对各步骤各主要因子和水平的作用进行了试验探讨.结果表明:条叶百合鳞茎诱导最适宜的培养基为N6+0.05 mg.L-1IAA+0.01 mg.L-1NAA+0.50 mg.L-1KT,诱导率为95.5%,鳞茎萌发为完整植株的最佳培养基为N6+0.01 mg.L-1IAA,萌发率为94%;垂花百合鳞茎诱导最适宜的培养基为N6+0.05 mg.L-1IAA+0.50 mg.L-1KT,诱导率为95%,鳞茎萌发为完整植株的最佳培养基为N6+0.01 mg.L-1IAA+0.001 mg.L-1NAA,萌发率为92.5%.以鳞茎的切片为材料进行快繁的结果表明,在35-40 d的一个培养周期内,增殖系数达10以上.对不同阶段培养材料的形态及超微结构的观察证明了2种百合的鳞茎发生发育过程.     

Knockout of GPR56 gene inhibits maturation of oligodendrocyte progenitor cells

AIM：To explore the effect of G-protein-coupled protein 56 (GPR56) gene knockout on axonal myelination and the maturation of oligodendrocyte progenitor cells (OPCs) in the corpus callosum of mouse brain. METHODS：Thirty-six GPR56+/- and GPR56-/- mice were selected and divided into GPR56+/- group and GPR56-/- group (18 mice in each group). According to the postnatal days, the mice in each group were further divided into P7, P14, P21 and P28 subgroups. Myelin formation in the corpus callosum of P14, P21 and P28 GPR56+/- and GPR56-/- mice was observed by FluoroMyelin staining. The number of myelinated axons and thickness of myelin sheaths were measured by electron microscopy. The numbers of platelet-derived growth factor alpha receptor-positive (PDGF-aR+) and proteolipid protein-positive (PLP+) cells in the corpus callosum of GPR56+/- and GPR56-/- mice were compared by the methods of immunofluorescence and in situ hybridization. GPR56+/- and GPR56-/- OPCs were cultured using P1 GPR56+/- and GPR56-/- mouse brain cortex and induced differentiation and maturation in vitro. The percentage of GPR56+/- and GPR56-/- O4+ cells in pro-oligodendroblast, immature oligodendrocyte and mature oligodendrocyte stages was compared by O4 immunostaining. RESULTS：The myelin formation was obviously reduced in the corpus callosum of P14, P21 and P28 GPR56-/- mice as compared with GPR56+/- mice. The number of myelinated axons was obviously reduced and the g-ratio value was increased significantly in the corpus callosum of P28 GPR56-/- mice. No significant difference of the PDGF-aR+ cell number in the corpus callosum between P7 d GPR56+/- and GPR56-/- mouse brains was observed. The number of PLP+ cells was significantly decreased in the corpus callosum of P28 GPR56-/- mice as compared with GPR56+/- mice. The percentage of GPR56-/- O4+ cells in pro-oligodendroblast stages was obviously higher than that of GPR56+/- O4+ cells. On the contrary, the percentages of GPR56-/- O4+ cells in immature oligodendrocyte and mature oligodendrocyte stages were significantly reduced. CONCLUSION:GPR56 may be involved in axonal myelination and OPCs maturation in the corpus callosum of mouse brain.     

条叶百合的开花生物学特性研究

以栽培和野生的条叶百合为对象,对其开花年龄、花期、开花动态、花部变异、授粉试验和传粉媒介检验等进行了生物学特性的初步研究。结果表明:2年生条叶百合抽茎率为50.60%,开花率33.38%;3年生植株全部开花。群体花期22 d,开花高峰持续7~8 d;花的起始开放时间在15:30以后,单花开放过程约2~3 h,单花花期为4 d。栽培第2年植株花瓣缺失或畸形的比例明显比自然环境的增多,雄蕊退化和雄蕊长于雌蕊的比率随着栽培时间的增加而增加,雌蕊退化比率随着栽培时间的增加而减少。条叶百合以虫媒、异花授粉为主,虽自交可育,但坐果率较低。从开花前2天授粉到开花第3天时,授粉的每个蒴果所结饱满种子与坐果率都呈明显的递增趋势,开花次日和开花第3天时,其雌蕊的可授性最佳。     

条叶百合×王百合种间杂种的育成

为培育新的百合品种,利用抗性强的野生条叶百合（Ｌｉｌｉｕｍｃａｌｏｓｕｍ）为母本及花筒状、白色的王百合（Ｌｒｅｇａｌｅ）为父本,进行种间杂交。常规授粉的结果,座果率２６％,得到有胚种子占８％;杂种种子在重量、大小及发芽率上均小于亲本,发芽势介于亲本之间;杂种种子为子叶出土萌发类型,与亲本一致。利用种子根尖为材料,所观察到的染色体形态表明,杂种染色体基本具有双亲染色体的特征,说明杂种真实可靠。条叶百合与王百合虽然形态差异大,分类学上分属不同的两个组,但它们之间有一定生殖亲和力,杂种幼苗根系发达,生命力较强。