Cdk5/p35 phosphorylates lemur tyrosine kinase-2 to regulate protein phosphatase-1C phosphorylation and activity

Cyclin-dependent kinase-5 (cdk5)/p35 and protein phosphatase-1 (PP1) are two major enzymes that control a variety of physiological processes within the nervous system including neuronal differentiation, synaptic plasticity and axonal transport. Defective cdk5/p35 and PP1 function are also implicated in several major human neurodegenerative diseases. Cdk5/p35 and the catalytic subunit of PP1 (PP1C) both bind to the brain-enriched, serine-threonine kinase lemur tyrosine kinase-2 (LMTK2). Moreover, LMTK2 phosphorylates PP1C on threonine-320 (PP1Cthr32?) to inhibit its activity. Here, we demonstrate that LMTK2 is phosphorylated on serine-1418 (LMTK2ser1?1?) by cdk5/p35 and present evidence that this regulates its ability to phosphorylate PP1Cthr32?. We thus describe a new signalling pathway within the nervous system that links cdk5/p35 with PP1C and which has implications for a number of neuronal functions and neuronal dysfunction.     

Endodermal cell-cell contact is required for the spatial control of Casparian band development in Arabidopsis thaliana

Background and Aims

Apoplasmic barriers in plants fulfil important roles such as the control of apoplasmic movement of substances and the protection against invasion of pathogens. The aim of this study was to describe the development of apoplasmic barriers (Casparian bands and suberin lamellae) in endodermal cells of Arabidopsis thaliana primary root and during lateral root initiation.

Methods

Modifications of the endodermal cell walls in roots of wild-type Landsberg erecta (Ler) and mutants with defective endodermal development – scarecrow-3 (scr-3) and shortroot (shr) – of A. thaliana plants were characterized by light, fluorescent, confocal laser scanning, transmission and cryo-scanning electron microscopy.

Key Results

In wild-type plant roots Casparian bands initiate at approx. 1600 µm from the root cap junction and suberin lamellae first appear on the inner primary cell walls at approx. 7000–8000 µm from the root apex in the region of developing lateral root primordia. When a single cell replaces a pair of endodermal and cortical cells in the scr-3 mutant, Casparian band-like material is deposited ectopically at the junction between this ‘cortical’ cell and adjacent pericycle cells. Shr mutant roots with an undeveloped endodermis deposit Casparian band-like material in patches in the middle lamellae of cells of the vascular cylinder. Endodermal cells in the vicinity of developing lateral root primordia develop suberin lamellae earlier, and these are thicker, compared wih the neighbouring endodermal cells. Protruding primordia are protected by an endodermal pocket covered by suberin lamellae.

Conclusions

The data suggest that endodermal cell–cell contact is required for the spatial control of Casparian band development. Additionally, the endodermal cells form a collet (collar) of short cells covered by a thick suberin layer at the base of lateral root, which may serve as a barrier constituting a ‘safety zone’ protecting the vascular cylinder against uncontrolled movement of water, solutes or various pathogens.     

Brainstem lateral line responses to sinusoidal wave stimuli in the goldfish, Carassius auratus

Extracellular recordings were made from single lateral line units in the medial octavolateralis nucleus in the brainstem of goldfish, Carassius auratus. Units were defined as receiving lateral line input if they responded to the water motions generated by a stationary, sinusoidally oscillating sphere and/or a moving sphere but not to airborne sound and vibrations. Units which responded to airborne sound or vibrations were assumed to receive input from the inner ear and were not further investigated. Responses of lateral line units were quantified in terms of the number of evoked spikes and the degree of phase-locking to a 50 Hz vibrating sphere presented at various stationary locations along the side of the fish. Receptive fields were characterized based on spike rate, degree of phase-locking and average phase angle as a function of sphere location. Four groups of units were distinguished: 1, units with receptive fields comparable to those of primary afferents; 2, units with receptive fields which consisted of one excitatory and one inhibitory area; 3, units with receptive fields which consisted of more than two excitatory and/or inhibitory areas; 4, units with receptive fields which consisted of a single excitatory or a single inhibitory area. The receptive fields of most units were characterized by adjacent excitatory and inhibitory areas. This organization is reminiscent of excitatory-inhibitory receptive field organizations in other vertebrate sensory systems.     

侧脑室引流术在隐球菌性脑膜脑炎早期治疗中的应用

目的观察侧脑室引流术在隐球菌性脑膜脑炎早期治疗中的临床效果,探讨其有效性与安全性。方法对近年来我科治疗的5例初发隐球菌性脑膜脑炎伴高颅压患者的临床资料进行回顾性分析。结果 5例患者经早期行侧脑室引流后临床症状迅速缓解,撤除引流管后症状无加重;5例患者中无一例发生感染等并发症。联合抗真菌治疗后早期真菌学指标好转,长期随访中,4例患者临床治愈,无复发,1例死亡。结论侧脑室引流是隐球菌性脑膜脑炎早期治疗中快速、安全缓解头痛症状及减少并发症的有效手段。     

3 例以延髓麻痹为首发表现的肌萎缩侧索硬化的病例报告

目的:探讨以延髓麻痹为首发症状的肌萎缩侧索硬化的临床特点。方法:报告3例以构音障碍等延髓麻痹症状起病的肌萎缩侧索硬化少见病例,结合文献复习,分析其临床特点。结果:在ALS患者中,以延髓麻痹为首发症状发生率相对较低,多见于老年人,最易表现为构音障碍,患者的生存期缩短,预后不良。结论:对于以延髓麻痹表现起病的ALS患者,要引起重视,及时针对延髓麻痹对症治疗,改善患者生活质量。     

热牙胶充填与冷牙胶侧方加压在根管充填中应用的临床效果比较

目的:比较热牙胶充填与冷牙胶侧方加压在根管充填中应用的临床效果。方法:选择62例急性牙髓炎和根尖周炎患者,均分后分别选择热牙胶充填与冷牙胶侧方加压的方法进行根管充填,比较两组患者根管充填时间、术后牙周疼痛病例和术后3个月后充填质量及临床疗效。结果:两组患者术后牙周疼痛病例比较,差异无统计学意义(P>0.05);其余各方面比较,差异均均有统计学意义(P>0.05),热牙胶组优于冷牙胶组。结论:临床进行根管充填治疗时,应首选热牙胶充填的方式,可显著提高临床疗效,且不增加患者术后牙周疼痛的发生。     

Evolutionary relationships of flavobacterial and enterobacterial endosymbionts with their scale insect hosts (Hemiptera: Coccoidea)

Flavobacteria and Enterobacteriaceae have been previously reported as scale insect endosymbionts. The purpose of this work was twofold: first, to screen different scale insect families for the presence of these endosymbionts by PCR analyses and second, to elucidate the history of cophylogeny between these bacteria and the insects by analysing a portion of 16S rRNA and 18S rRNA gene sequences by two reconciliation tools, CoRe‐PA and Jane. From a survey of 27 scale insects within seven families, we identified Flavobacteria and Enterobacteriaceae as coexisting in ten species that belong to the Ortheziidae, Monophlebidae, Diaspididae and Coccidae families, and we frequently found two closely related enterobacteria harboured in the same individual. Analyses performed with CoRe‐PA and Jane suggest that Flavobacteria from the scale insects analysed have a unique origin, except for Candidatus Brownia rhizoecola (Flavobacteria of Pseudococcidae, Phenacoccinae), which seems to come from a nonscale insect. Nevertheless, cospeciation between Flavobacteria and scale insects is suggested only within the families Monophlebidae, Ortheziidae and Diaspididae, and host switches seem to have occurred from the ancestors of Monophlebidae and Ortheziidae to insects from families Coccidae, Lecanodiaspididae, Eriococcidae and Pseudococcidae. Our analyses suggest that Enterobacteriaceae underwent more evolutionary events (losses, duplications and host switches), and their phylogenies showed a lower proportion of congruent nodes between host and bacteria, indicating a more relaxed relationship with scale insects compared with Flavobacteria.     

5种绿化树种叶片比叶重、光合色素含量和δ~(13)C的开度与方位差异

受太阳活动的影响,树冠不同方位以及内外部的叶片接受到的光照存在差异,造成温度、湿度等小气候因子也存在差异。叶片的形态解剖结构和生理特性等会对外界环境条件的改变发生响应。为了更好地了解树木生长的局部小环境条件差异对树木生长的影响,该文选择国槐(Sophora japonica)、悬铃木(Platanus orientalis)、银杏(Ginkgo biloba)、榕树(Ficus mi-crocarpa)和黄葛榕(F.lacor)5种冠幅较大的树种,通过测定树冠内外部及4个方位上的比叶重(leaf mass per area,LMA)、叶绿素a(chlorophyll a,Chl a)、叶绿素b(chlorophyll b,Chl b)及类胡萝卜素(carotenoid,Car)的含量及碳稳定同位素比率(carbon isotope ratio,δ13C)等指标,研究叶片形态、生理指标等随树冠开度的变化以及方位差异。结果表明,叶片LMA和δ13C均随树冠开度增加而增大,光合色素含量则相反;叶片LMA和δ13C的方位变化则是南向西向北向东向,与叶片所接受到的光强变化规律一致,而光合色素含量的方位差异较复杂、且因树种而异,总的来说,以受光最弱的东向含量最高。上述结果表明,树冠外围和南向、西向的叶片由于接受到的光能较多、温度高、相对湿度小等,其叶片会增大单位面积的重量、减小气孔开度和光合色素含量,从而减少对光能的吸收,也使光合作用降低、δ13C增大,而不同方位光照对光合色素含量的影响机制较为复杂,这些都表明了叶片对周围小气候的形态和生理上的适应。     

Reduced Smoothened level rescues Aβ-induced memory deficits and neuronal inflammation in animal models of Alzheimer's disease

Emerging evidence suggests that neuro-inflammation begins early and drives the pathogenesis of Alzheimer's disease(AD), and anti-inflammatory therapies are under clinical development. However,several anti-inflammatory compounds failed to improve memory in clinical trials, indicating that reducing inflammation alone might not be enough. On the other hand, neuro-inflammation is implicated in a number of mental disorders which share the same therapeutic targets. Based on these observations,we screened a batch of genes related with mental disorder and neuro-inflammation in a classical olfactory conditioning in an amyloid beta(Aβ) overexpression fly model. A Smoothened(SMO) mutant was identified as a genetic modifier of Aβ toxicity in 3-min memory and downregulation of SMO rescued Aβ induced 3-min and 1-h memory deficiency. Also, Aβ activated innate inflammatory response in fly by increasing the expression of antimicrobial peptides, which were alleviated by downregulating SMO.Furthermore, pharmaceutical administration of a SMO antagonist LDE rescued Aβ-induced upregulation of SMO in astrocytes of mouse hippocampus, improved memory in Morris water maze(MWM), and reduced expression of astrocyte secreting pro-inflammatory factors IL-1 b, TNFa and the microglia marker IBA-1 in an APP/PS1 transgenic mouse model. Our study suggests that SMO is an important conserved modulator of Aβ toxicity in both fly and mouse models of AD.     

Brain-controlled synthesis of juvenile hormone in adult insects

Conclusions and future research There is now quite substantial evidence that the MNSC and the LNSC produce CA regulatory substances which are transported along axons and released in the immediate vicinity of the gland cells and that this system forms the most important means of CA control from the brain. The putative allatostatins and allatotropins are most probably neuropeptides. Isolation and identification of these substances are priorities in the coming years. The neuroendocrinological aspects, such as the precise rôle of the MNSC and the LNSC in different species; whether allatotropins and allatostatins arise from a single precursor molecule, and the dynamics of release of the substances from the nerve terminals, provide highly interesting topics. Furthermore, questions concerning control mechanisms of JH-biosynthesis at the cellular and molecular level, including the role of second messengers, the rate limiting steps in the biosynthetic pathway, and the regulation of gland growth still need to be clarified.