A Drosophila tissue polarity locus encodes a protein containing seven potential transmembrane domains

The function of the frizzled (fz) locus in Drosophilia melanogaster is required to coordinate the cytoskeletons of epidermal cells to produce a parallel array of cuticular hairs and bristles (for example on the wild-type wing all hairs point towards the distal tip). In fz mutants it is not the structure of individual hairs and bristles that is altered, but their orientation with respect to their neighbours and the organism as a whole. Mitotic clone analysis indicates that fz has two functions in the developing wing. It is required for the proximal-distal transmission of an intercellular polarity signal, a process that is expected to be at least partly extracellular. It is also required for cells to respond to the polarity signal, which is expected to be a cytoplasmic function. The fz locus could encode either one bifunctional or two single-function proteins. We report here that, in pupae, fz produces a messenger RNA that encodes a protein with seven putative transmembrane domains. Thus, the Fz protein should contain both extracellular and cytoplasmic domains, which could function in the transmission and interpretation of polarity information, respectively. This is the first reported sequence for the protein product of a tissue polarity gene.     

PTK7/CCK-4 is a novel regulator of planar cell polarity in vertebrates

In addition to the apical-basal polarity pathway operating in epithelial cells, a planar cell polarity (PCP) pathway establishes polarity within the plane of epithelial tissues and is conserved from Drosophila to mammals. In Drosophila, a 'core' group of PCP genes including frizzled (fz), flamingo/starry night, dishevelled (dsh), Van Gogh/strabismus and prickle, function to regulate wing hair, bristle and ommatidial polarity. In vertebrates, the PCP pathway regulates convergent extension movements and neural tube closure, as well as the orientation of stereociliary bundles of sensory hair cells in the inner ear. Here we show that a mutation in the mouse protein tyrosine kinase 7 (PTK7) gene, which encodes an evolutionarily conserved transmembrane protein with tyrosine kinase homology, disrupts neural tube closure and stereociliary bundle orientation, and shows genetic interactions with a mutation in the mouse Van Gogh homologue vangl2. We also show that PTK7 is dynamically localized during hair cell polarization, and that the Xenopus homologue of PTK7 is required for neural convergent extension and neural tube closure. These results identify PTK7 as a novel regulator of PCP in vertebrates.     

Fidelity in planar cell polarity signalling

The polarity of Drosophila wing hairs displays remarkable fidelity. Each of the approximately 30,000 wing epithelial cells constructs an actin-rich prehair that protrudes from its distal vertex and points distally. The distal location and orientation of the hairs is virtually error free, thus forming a nearly perfect parallel array. This process is controlled by the planar cell polarity signalling pathway. Here we show that interaction between two tiers of the planar cell polarity signalling mechanism results in the observed high fidelity. The first tier, mediated by the cadherin Fat, dictates global orientation by transducing a directional signal to individual cells. The second tier, orchestrated by the 7-pass transmembrane receptor Frizzled, aligns each cell's polarity with that of its neighbours through the action of an intercellular feedback loop, enabling polarity to propagate from cell to cell. We show that all cells need not respond correctly to the presumably subtle signal transmitted by Fat. Subsequent action of the Frizzled feedback loop is sufficient to align all the cells cooperatively. This economical system is therefore highly robust, and produces virtually error-free arrays.     

Frizzled regulation of Notch signalling polarizes cell fate in the Drosophila eye

The Drosophila eye, a paradigm for epithelial organization, is highly polarized with mirror-image symmetry about the equator. The R3 and R4 photoreceptors in each ommatidium are vital in this polarity; they adopt asymmetrical positions in adult ommatidia and are the site of action for several essential genes. Two such genes are frizzled (fz) and dishevelled (dsh), the products of which are components of a signalling pathway required in R3, and which are thought to be activated by a diffusible signal. Here we show that the transmembrane receptor Notch is required downstream of dsh in R3/R4 for them to adopt distinct fates. By using an enhancer for the Notch target gene Enhancer of split mdelta, we show that Notch becomes activated specifically in R4. We propose that Fz/Dsh promotes activity of the Notch ligand Delta and inhibits Notch receptor activity in R3, creating a difference in Notch signalling capacity between R3 and R4. Subsequent feedback in the Notch pathway ensures that this difference becomes amplified. This interplay between Fz/Dsh and Notch indicates that polarity is established through local comparisons between two cells and explains how a signal from one position (for example, the equator in the eye) could be interpreted by all ommatidia in the field.     

Graded and nonlinear mechanical properties of sensory hairs in the mammalian hearing organ

It is generally agreed that frequency selectivity of the mammalian hearing organ is mainly due to a graded elasticity of the basilar membrane. Recent measurements of basilar membrane motion hair cell receptor potentials and neural tuning curves show that frequency selectivity can be extremely sharp. It has been suggested that in non-mammalian species there are additional tuning mechanisms in the sensory hair cells themselves, either by virtue of their electrical membrane properties or through a gradation in length of their sensory hairs. Indeed, sensory hair mechanical tuning has been demonstrated in the lizard. We have investigated the mechanical properties of sensory hair bundles in the guinea pig organ of Corti, and report here that hair-bundle stiffness increases longitudinally towards the high-frequency end of the cochlea, decreases radially towards the outer rows of cells, and is greater for excitatory than for inhibitory deflection. On the basis of these findings, we suggest that sensory hairs confer frequency-specific, nonlinear mechanical properties on the hearing organ.     

Induction of hair growth by implantation of cultured dermal papilla cells

Mammalian hairs are formed by differentiation and keratinization of cells produced in the epidermal matrix (Figs 3, 4). Using the rodent vibrissa follicle as a model, transplantation studies have shown that the dermal papilla, a discrete population of specialized fibroblasts, is of prime importance in the growth of hair. Papillae induce hair growth when implanted into follicles and can interact with skin epidermis to form new hair follicles. When grown in culture, papilla cells display singular morphological and behavioural characteristics compared with connective tissue cells from other skin sources. We report here that serially cultured adult papilla cells can induce the growth of hair when implanted into follicles which otherwise would not grow hairs. This finding presents an opportunity to characterize properties distinguishing the papilla cell population from other skin fibroblasts, and, more specifically, those which control hair growth. The eventual application of this work to human hair replacement techniques can also be envisaged.     

根瘤菌诱导紫云英根表面传递细胞的观察

对紫云英无菌苗进行接菌处理，以不接菌为对照。于灭菌无氮培养液中培养1周，在接菌处理的紫云英苗中，取根毛密集、形变明显的根段固定，同时在不接菌对照处理的紫云英苗中，截取相应部位根段固定。两组固定的根段分别进行塑料半薄切片光镜观察和超薄切片透射电镜观察。结果发现：经根瘤菌处理的根段，其根表皮细胞的外切向壁上，发育出大量壁内突结构，甚至在根毛细胞四周也发育出大量的壁内突结构，属典型的传递细胞。经透射电镜观察，这些壁内突结构主要为乳头状和盾状结构。而对照苗的根段内未发现壁内突结构，证明紫云英根表皮传递细胞的形成是由紫云英根瘤菌诱导所致。     

Nature of the motor element in electrokinetic shape changes of cochlear outer hair cells

It is the prevailing notion that cochlear outer hair cells function as mechanical effectors as well as sensory receptors. Electrically induced changes in the shape of mammalian outer hair cells, studied in vitro, are commonly assumed to represent an aspect of their effector process that may occur in vivo. The nature of the motile process is obscure, even though none of the established cellular motors can be involved. Although it is known that the motile response is under voltage control, it is uncertain whether the stimulus is a drop in the voltage along the long axis of the cell or variation in the transmembrane potential. We have now performed experiments with cells partitioned in differing degrees between two chambers. Applied voltage stimulates the cell membrane segments in opposite polarity to an amount dependent on the partitioning. The findings show, in accordance with previous suggestions, that the driving stimulus is a local transmembrane voltage drop and that the cellular motor consists of many independent elements, distributed along the cell membrane and its associated cortical structures. We further show that the primary action of the motor elements is along the longitudinal dimension of the cell without necessarily involving changes in intracellular hydrostatic pressure. This establishes the outer hair cell motor as unique among mechanisms that control cell shape.     

Study on a New Method of Reducing the Water Shrinkage of Rabbit Hair Knitted Fabrics

Introduction Rabbithair,asakindofvaluableanimalfibers,has manygoodpropertiessuchasbulk,whiteness,lightness,smoothandgoodwarmthretentionandsoon.Withthe developmentoftextileindustry,theapplicationofrabbit hairscontinuestoexpandandgainmoreandmoreattentions.Productsofhighpercentrabbithairsseemmoreluxurious.However,thereisalayerofscalesonthesurfaceasother animalfibers,fabricsmadeofrabbithairsoftenshrink afterwashing,whichdecreasesthedimensionalstabilityof fabrics,andmakesdailycaredifficult.Inaddit…     

A large scale screen for genes （3rd chromosome） related to Wingless signaling pathway

A wing specific F 1 genetic screen was carried out using the powerful Drosophila genetic system, combined with yeast FRT/FLP and GAL4/UAS system. Form the wing phenotypes and germline clone embryonic cuticle phenotypes observed in these mutant alleles, a number of mutant alleles of known or unknown genes were isolated. Among them, fifteen mutant alleles related to Wingless signal transduction were further isolated; the arm of these mutations located were determined, and their location in the chromosome were roughly mapped.     

A nearly completely articulated rhamphorhynchoid pterosaur with exceptionally well-preserved wing membranes and “hairs” from Inner Mongolia, northeast China

We report a new and nearly completely articulated rhamphorhynchoid pterosaur, Jeholopterus ningchengensis gen. et sp. nov., with excellently preserved fibres in the wing membrane and "hairs" in the neck, body and tail regions. Many of its characteristics such as a short neck, short metacarpals and distinctively long fifth pedal digit are characteristic of rhamphorhynchoids. The new species can be further referred to the 'strange' short-tailed rhamphorhynchoid family Anurognathidae. It is much more complete than the other known members of the family, namely, Anurognathus from Solnhofen, Germany, Batrachognathus from Karatau, Kazakhstan, and Dendrorhynchoides from Beipiao, Liaoning Province, China. The new pterosaur also shows that the wing membrane is attached to the ankle of the hind limb. The pedal digits are webbed. Furthermore, the "hair" of Jeholopterus bears some resemblance to the hair-like integumental structures of the feathered dinosaur Sinosauropteryx although there is yet no direct evidence to argue for or against their homology.     

美洲黑杨种质材料倍性鉴定

【目的】对美洲黑杨种质资源库保存的种质材料进行倍性评估,并对候选多倍体进行倍性鉴定。【方法】利用9对用于多倍体鉴定的SSR引物检测448份美洲黑杨种质材料,根据每个引物扩增位点的等位基因数目对种质材料的倍性进行评估,基于初步鉴定结果筛选出候选多倍体材料。在此基础上,使用流式细胞仪(FCM)对候选多倍体种质材料的倍性进行鉴定。【结果】分子标记基因型分型统计结果显示,9个SSR位点共扩增出129条多态性条带,每个位点的等位基因数为5(Ploidp-10)~25(Ploidp-07)个,平均每个位点的等位基因数为14.33个。9个SSR位点的多态性信息含量(PIC)变动范围为0.46~0.93,平均PIC值为0.76。在检测的448份美洲黑杨种质材料中,440份美洲黑杨种质材料在9个引物位点上扩增出的等位基因数不多于2个;有8份种质材料在2个引物位点上扩增出了3个不同的等位基因,其中编号为1346、16-42、17-49、18-25的4份种质材料在Ploidp-02引物位点扩增出了3个等位基因,而编号为5-43、5-45、15-14、19-37的另外4份种质材料在Ploidp-04引物位点上也扩增出了3个等位基因。分子检测结果表明:该8份种质材料在对应的染色体区域发生了遗传物质增加现象,为候选三倍体种质材料。用FCM对8份三倍体候选种质材料进行倍性鉴定发现,编号为1346的种质材料为三倍体,其余7份种质材料疑似为发生局部染色片段增加的候选非整倍体。【结论】9对SSR分子标记均具有较高的多态性信息含量,可用于美洲黑杨种质资源多倍体初步筛选,结合FCM检测,可在大量样品中快速筛选出多倍体种质材料。     

中国鹅掌楸柱头毛发育的超微结构和物质分泌

<正>作者观察了中国鹅掌楸(Liriodendrom chinense(Hemsl.)Sarg.)柱头毛发育中超微结构的变化并对其分泌物作了定性测定。中国鹅掌楸柱头属湿型柱头,柱头毛由柱头近轴面表皮细胞伸长生长而形成,大多数为单细胞,少数为单列二细胞。柱头毛在发育中细胞器的变化与物质分泌存在相关性。早期,片层状分泌物与粗糙内质网有关,嗜锇小颗粒的出现与线粒体密切相关,而此时,质体尚未发育完善。中、后期的脂类分泌与光滑内质网形成、质体内淀粉消解有关。通过定性测定,早期胞外分泌物的糖类、蛋白和脂类都为负反应,而此后仅脂类显示出强烈正反应。     

朝鲜鹌鹑耳蜗感觉上皮的超微结构研究

对朝鲜鹌鹑耳蜗感觉上皮的超微结构进行了研究。朝鲜鹌鹑耳蜗感觉上皮包括听壶感觉上皮和基乳突感觉上皮两部分。这两部分感觉上皮均由毛细胞和支持细胞构成。毛细胞基部与神经末梢形成突触,顶端角质锥中伸出动纤毛和静纤毛,与鸡的耳蜗毛细胞相似,朝鲜鹌鹑耳蜗毛细胞缺乏动纤毛。     

MIXTA/MIXTA-like基因特征及其对植物表皮细胞分化的调控

植物表皮细胞是植物最外层直接与环境相互作用的细胞,依据其不同功能,分化形成多种具有防卫功能的特化细胞结构,在植物防御、减少蒸腾、授粉媒介吸引、种子散布、次生代谢产物合成与贮存等方面起着重要作用。研究发现MIXTA/MIXTA-like是多种植物表皮细胞分化的关键调控因子。在不同植物中,MIXTA/MIXTA-like作用部位(主要集中在花瓣、叶片、胚珠和子房)和调节方式不同,但最终都是通过调控表皮细胞分化发挥作用。MIXTA/MIXTA-like在表皮毛的形成、角质层生物合成、锥形表皮细胞的分化过程中起着重要的调节作用,其中植物表皮毛发育是一个研究热点。植物表皮毛有多种不同的功能:如叶片被毛是植物抵御取食昆虫的重要表型特征;法国梧桐、杨树、柳树飞絮都是种子成熟过程中表皮毛发育的结果;而黄花蒿中,青蒿素主要在腺毛中合成和储存。因此,开展植物表皮毛发育和调控机制研究具有重要意义。笔者梳理了MIXTA/MIXTA-like基因的特征及其在不同植物表皮细胞分化过程中的生物学功能,阐述了木本植物表皮毛发育调控的分子机制,为加速林木表皮毛发育相关性状的新品种培育提供借鉴。