越南黑叉尾斗鱼展示行为的偏侧化及其对镜面影像的响应

动物行为的偏侧化现象广泛存在于各个类群,特别是具有仪式化展示和打斗行为的鱼类。越南黑叉尾斗鱼(Macropodus spechti)是一种雄性个体间具有模式化展尾行为小型淡水鱼类。本文主要研究越南黑叉尾斗鱼展尾行为或眼睛使用的偏侧化现象,以及镜面影像对其行为的影响。研究发现,越南黑叉尾斗鱼中在个体(94.6%,n=35)和群体(左侧化指数:LⅠ=0.25±0.19)水平均具有明显的左侧化倾向;镜面影像会降低斗鱼的展示强度和左侧化倾向(LⅠ=0.10±0.23),但是,对水面呼吸的频次没有显著影响。这表明,越南黑叉尾斗鱼的左侧化倾向是对"头-尾"相对展示的一种适应,而镜面影像中"头-尾"展示姿势的变化对越南黑叉尾斗鱼的展示行为具有明显影响,但这种影响在反应强度(换气次数)上并没有差异,由此认为越南黑叉尾斗鱼对镜面影像缺乏自我识别能力。同时,由于偏侧化现象的存在,使得使用镜面影像无法获得和真实个体一致的行为响应结果。本研究对未来行为学研究中如何使用镜面影像研究动物行为具有重要的指导意义。     

Solution NMR views of dynamical ordering of biomacromolecules

Background

To understand the mechanisms related to the ‘dynamical ordering’ of macromolecules and biological systems, it is crucial to monitor, in detail, molecular interactions and their dynamics across multiple timescales. Solution nuclear magnetic resonance (NMR) spectroscopy is an ideal tool that can investigate biophysical events at the atomic level, in near-physiological buffer solutions, or even inside cells.

Membrane cholesterol depletion in cortical neurons highlights altered NMDA receptor functionality in a mouse model of amyotrophic lateral sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a chronic neurodegenerative disease affecting upper and lower motor neurons, with unknown aetiology. Lipid rafts, cholesterol enriched microdomains of the plasma membrane, have been linked to neurodegenerative disorders like ALS. The NMDA-receptor subcellular localization in lipid rafts is known to play many roles, from modulating memory strength to neurotoxicity. In this study, performed on the widely used G93A mouse model of ALS, we have shown an equal content of total membrane cholesterol in Control and G93A cortical cultures. Moreover, by electrophysiological studies, we have recorded NMDA- and AMPA-evoked currents which were not significantly different between the two neuronal populations. To study the role of membrane cholesterol on glutamate receptor functionality, we have analysed NMDA and AMPA receptors following cholesterol membrane depletion by methyl-β-cyclodextrin (MβCD). Interestingly, MβCD chronic treatment has provoked a significant reduction of NMDA-evoked currents in both cellular populations which was dose- and time-dependent but significantly higher in ALS neurons compared to Control. The different MβCD effect on NMDA-evoked currents was not due to a different membrane receptor subunit composition but seemed to cause in both neuronal populations a NMDA receptor membrane redistribution. MβCD treatment effect was receptor-specific since no alterations in the two neuronal populations were detected on AMPA receptors.These results lead us to speculate for an altered proteomic composition of lipid rafts in cortical mutated neurons and suggest the need for further studies on the lipid rafts composition and on their interaction with membrane receptors in ALS cortices.     

Metabolism-dependent activation and toxicity of chemicals in nasal glands

The mucosae of the nasal passages contain a large amount of glands which express secretory proteins as well as phase I and phase II biotransformation enzymes. In this review the metabolic activation, covalent binding and toxicity of chemicals in the Bowman's glands in the olfactory mucosa, in the sero-mucous glands in the nasal septum and in the lateral nasal glands and maxillary glands around the maxillary sinuses are discussed. Light microscopic autoradiographic studies have demonstrated a selective covalent binding of nasal toxicants and carcinogens such as halogenated hydrocarbons and N-nitrosamines, especially in the Bowman's glands following a single systemic exposure, suggesting a high rate of metabolic activation of chemicals in these glands. Special attention is put on the herbicide dichlobenil which induces necrosis in the olfactory mucosa following a cytochrome-P450-mediated metabolic activation and covalent binding in the Bowman's glands.     

Plant regrowth response to a stem-boring insect: a swift moth-willow system

To examine plastic willow regrowth response to herbivory, we studied the effect of a boring insect, the swift moth Endoclita excrescens (Hepialidae: Lepidoptera), which does not remove apical meristems, on shoot growth in three willow species—Salix gilgiana, S. eriocarpa, and S. serissaefolia−by direct observations and experiments in the field. We hypothesized that the stem-boring could initiate new lateral bud activation, and result in secondary shoot regrowth without the removal of the primary apical meristems. There were significantly more lateral shoots on naturally attacked than unattacked stems, and a significant positive correlation between lateral shoot density and the number of swift moth tunnels per tree was observed for all three willow species. Artificial boring, and larval infestation, resulted in an increase in the number of lateral shoots, but did not affect growth of current-year shoots. The length of lateral shoots differed between species, being significantly longer in S. gilgiana than S. eriocarpa and S. serissaefolia. The results of this study show that compensatory regrowth can result even if herbivory does not remove the apical meristem. We argue that this type of plant compensatory response is probably widespread, given that the stem-boring is a common feeding type of insect herbivores.     

Ultrastructure de l'organe Ampullaire de Gymnotus carapo (Gymnotidae); Origine et Nature des Mucopolysaccharides

Résumé Les organes sensoriels cutanés de type ampullaire, spécifiques du système de la ligne latérale chez Gymnotus carapo, sont étudiés ici sous leur aspect morphologique et histochimique. Cellules sensorielles et cellules accessoires constituent un épithélium simple tapissant l'ampoule. Innervée par une seule fibre se terminant par un énorme bouton terminal, chaque cellule sensorielle a une surface libre importante, en contact avec les substances muqueuses qui remplissent l'ampoule et le canal intraépidermique. Les cellules accessoires de l'epithélium sensoriel et les cellules de la paroi du canal sont secrétrices des mucopolysaccharides neutres du canal.

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Ultrastructure of the ampullary organ of Gymnotus carapo (Gymnotidae) nature and origin of its polysaccharids

Summary The specific cutaneous organs of the lateral line system in Gymnotus carapo have been observed by morphological and histochemical methods.The ampullary epithelium is constituted by a layer of sensory and accessory cells. Each sensory cell is innervated by one fiber ending with a large terminal bud. The sensory cells have also an important free surface in contact with the mucoïd substances which fill up the ampullae and the intraepidermic canal.The accessory cells of the ampullary epithelium and the cells of the canal's wall produce the canal's neutral mucopolysaccharids.

Ce travail a été réalisé avec l'aide de la Direction de Recherches et Moyens d'Essais, accordée au Dr. T. Szabo (Contrat n 659-594).     

Lateral genomics

More than 20 complete prokaryotic genome sequences are now publicly available, each by itself an unparalleled resource for understanding organismal biology. Collectively, these data are even more powerful: they could force a dramatic reworking of the framework in which we understand biological evolution. It is possible that a single universal phylogenetic tree is not the best way to depict relationships between all living and extinct species. Instead a web- or net-like pattern, reflecting the importance of horizontal or lateral gene transfer between lineages of organisms, might provide a more appropriate visual metaphor. Here, I ask whether this way of thinking is really justified, and explore its implications.     

江豚脊髓的研究

本文研究了江豚脊髓的形态和内部构造,首次报道鲸类脊髓灰质分层和神经核的对应关系,并发现在胸段8—13节 、腰尾段1一6节等白质的侧索中有特殊细胞群,以多极或小三角形细胞为多,也有少数棱形细胞,呈串珠状排列或散在分布,分别与背角I- Ⅴ层相联系,它们显示出与感觉传导系有关,作者认为应分别称之为胸外侧核和腰尾外倒核。     

The Developmental Anatomy of the Seminal Root of Wheat

Wheat embryo usually gives rise to five seminal roots in matured caryopsls, although, the sixth root might develop in some cases. The first one is known as the primary root. Primary root emerged early, and its primodium was distinctly originated from the proembryo and could be gradually identified as three layers of initials. Lateral seminal roots emerged later from the embryonic axis in pairs, and originated from the surrouding cells of the procambium. Differentiation of lateral roots was much more vigorous than that of the first seminal root (primary root), and, its mother cells of metaxylem vessel appeared soon, Lateral seminal roots usually had more metaxylem vessels. In short, only the first root is the primary root, the lateral seminal roots are adventitious in nature, since their structures are similar to those of other adventitious roots.