Pax7 shows higher satellite cell frequencies and concentrations within intrafusal fibers of muscle spindles

Intrafusal fibers within muscle spindles make up a small subpopulation of muscle fibers. These proprioceptive fibers differ from most extrafusal fibers because, even in maturity, their diameters remain small, and they retain expression of developmental myosins. Although both extrafusal and intrafusal fibers contain satellite cells (SCs), comparatively little is known about intrafusal SCs. Analyzing chicken fast-phasic posterior (PLD) and slow-tonic anterior (ALD) latissimus dorsi muscles, we show that SCs of both intrafusal and extrafusal fibers express Pax7. We further test the hypotheses that intrafusal fibers display parameters reflective of extrafusal immaturity. These hypotheses are that intrafusal fibers contain (a) higher SC frequencies (number of SC nuclei/all nuclei within basal lamina) and concentrations (closer together) and (b) smaller myonuclear domains than do adjacent extrafusal fibers. IHC techniques were applied to PLD and ALD muscles excised at 30 and 138 days posthatch. The hypotheses were validated, suggesting that intrafusal fibers have greater capacities for growth, regeneration, and repair than do adjacent extrafusal fibers. During maturation, extrafusal and intrafusal fibers show similar trends of decreasing SC frequencies and concentrations and increases in myonuclear domains. Thus, extrafusal and intrafusal fibers alike should exhibit reduced capacities for growth, regeneration, and repair during maturation.     

Evolution and functional divergence of monocarboxylate transporter genes in vertebrates

Monocarboxylate transporters (MCTs) form a gene family with an ancient past. The identification of MCTs (MCHs) from bacteria, protozoa, fungi, invertebrates, as well as vertebrates, but not from plants and virus, allowed illuminating the phylogenetic and evolutionary history of this gene family. The significant expansion of vertebrate MCT genes should have primarily occurred after the divergence of vertebrates and invertebrates, but before the divergence time between ray-finned fish and mammals. The divergence of insect MCTs should have at least occurred in the common ancestor of fruit fly, beetle, and honeybee. Fungi monocarboxylate transporter homologues (MCHs) might evolve independently from an ancient ancestor. The results of functional divergence analysis provided statistical evidences for shifted evolutionary rate and/or changes of amino acid property after gene duplication. The sliding window analysis of the d(N)/d(S) ratio values showed that strong functional constraints must impose on the N- and C-terminal domains of vertebrate MCTs. These corresponding regions may play crucial roles for functionality of MCT proteins.     

颈前路“杂交式”与颈后路治疗多节段脊髓型颈椎病的临床比较

目的:比较颈前路"杂交式"减压融合与颈后路全椎板减压侧块内固定术治疗多节段脊髓型颈椎病的临床特点。方法:选择36例行"杂交式"颈前路治疗及33例行颈后路全椎板减压侧块内固定术治疗的多节段脊髓型颈椎病患者,观察两组患者手术前后一般资料、出血量、手术时间、颈椎生理曲度、JOA评分及并发症的发生情况。结果:两组患者术前的一般资料包括年龄(颈前路组:56.23±7.64岁,颈后路组:55.76±8.18岁)、性别(颈前路组:22男/14女,颈后路组:20男/13女)、颈椎生理曲度D值(颈前路组:7.41±3.14,颈后路组:8.19±2.74)、JOA评分(颈前路组:9.08±1.09分,颈后路组:8.82±1.26分)、病程(颈前路组:17.24±7.36月,颈后路组:15.75±5.78月)和受累节段(颈前路组:3.11±0.26个,颈后路组:3.24±0.39个)比较差异均无统计学意义(P0.05)。与颈后路相比,颈前路的术中出血量(颈前路组:221.79±178.02 mL,颈后路组:483.07±434.25 mL)更少,差异有统计学意义(P0.05),手术时间(颈前路组:196.54±51.88 min,颈后路组:175.12±54.93 min)更长,但差异无统计学意义(P0.05)。随着时间的延长,颈前路组患者颈椎生理曲度和JOA评分逐渐增大,而颈后路组患者椎生理曲度减少,JOA评分逐渐增大,差异有统计学意义(P0.05)。颈前路组出现植骨未融合、声音嘶哑和脑脊漏液,颈后路组发生轴性疼痛和C5神经根麻痹,但两组患者并发症的发生率比较差异无统计学意义(颈前路组:13.89%,颈后路组:12.12%)(P0.05)。结论:颈前路"杂交式"减压融合与颈后路全椎板减压侧块内固定术在治疗多节段脊髓型颈椎病上各有优点,临床根据患者的情况而采取合适的治疗方式。     

Drosophila Chitinase 2 is expressed in chitin producing organs for cuticle formation

The architecture of the outer body wall cuticle is fundamental to protect arthropods against invading pathogens and numerous other harmful stresses. Such robust cuticles are formed by parallel running chitin microfibrils. Molting and also local wounding leads to dynamic assembly and disassembly of the chitin-matrix throughout development. However, the underlying molecular mechanisms that organize proper chitin-matrix formation are poorly known. Recently we identified a key region for cuticle thickening at the apical cell surface, the cuticle assembly zone, where Obstructor-A (Obst-A) coordinates the formation of the chitin-matrix. Obst-A binds chitin and the deacetylase Serpentine (Serp) in a core complex, which is required for chitin-matrix maturation and preservation. Here we present evidence that Chitinase 2 (Cht2) could be essential for this molecular machinery. We show that Cht2 is expressed in the chitin-matrix of epidermis, trachea, and the digestive system. There, Cht2 is enriched at the apical cell surface and the dense chitin-matrix. We further show that in Cht2 knockdown larvae the assembly zone is rudimentary, preventing normal cuticle formation and pore canal organization. As sequence similarities of Cht2 and the core complex proteins indicate evolutionarily conserved molecular mechanisms, our findings suggest that Cht2 is involved in chitin formation also in other insects.     

Limb Patterning: From Signaling Gradients to Molecular Oscillations

The developing forelimb is patterned along the proximal–distal and anterior–posterior axes by opposing gradients of retinoic acid and fibroblast growth factors and by graded sonic hedgehog signaling, respectively. However, how coordinated patterning along both axes is accomplished with temporal precision remains unknown. The limb molecular oscillator hairy2 was recently shown to be a direct readout of the combined signaling activities of retinoic acid, fibroblast growth factor and sonic hedgehog in the limb mesenchyme. Herein, an integrated time-space model is presented to conciliate the progress zone and two-signal models for limb patterning. We propose that the limb clock may allow temporal information to be decoded into positional information when the distance between opposing signaling gradients is no longer sufficient to provide distinct cell fate specification.     

动物数能力的研究进展

动物数能力(numerical competence)是比较心理学、认知心理学和认知神经科学研究的热点之一。研究表明：(1)动物具有相对数量判断能力(relative numerousness judgments)和数量顿识能力(subitizing);(2)动物是否具有计数能力(counting)尚存在争议;(3)动物没有数量估算能力(estimation)。神经生理学研究发现,猴的后顶叶和前额叶在数功能方面扮演重要角色。     

Indiscelio: A new genus of Scelionidae (Platygastroidea) from India

A new scelionine genus Indiscelio Veenakumari, Popovici and Talamas is described from India with type species Indiscelio aulon Veenakumari, Popovici and Talamas. Both sexes are described and imaged. Affinities with morphologically similar genera are discussed.     

Dorsal-ventral signaling in limb development

In both Drosophila wings and vertebrate limbs, signaling between dorsal and ventral cells establishes an organizer that promotes limb formation. Significant progress has been made recently towards characterizing the signaling interactions that occur at the dorsal—ventral limb border. Studies of chicks have indicated that, as in Drosophila, this signaling process requires the participation of Fringe. Studies of Drosophila have indicated that Fringe functions by inhibiting the ability of Notch to be activated by one ligand, Serrate, while potentiating the ability of Notch to be activated by another ligand, Delta. Recent studies of both Drosophila and vertebrates have also shed new light on the signaling activity of the dorsal—ventral boundary limb organizer, and have highlighted how this organizer is maintained by feedback mechanisms with neighboring cells.