Viscosity-mediated motion coupling between pairs of trichobothria on the leg of the spider <Emphasis Type="Italic">Cupiennius salei</Emphasis>

Arachnids and insects use long, thin hairs as motion sensors to detect signals contained in the movement of the surrounding air. These hairs often form groups with a small spacing of tens to hundreds of micrometers between them. For air oscillation frequencies of biological interest, the potential exists for viscosity-mediated coupling among hairs in a group affecting their response characteristics. Even a small diameter hair can, in principle, affect the flow field around it and the dynamics of the hairs in its neighborhood. The viscosity-mediated coupling between a pair of hairs is investigated here both experimentally and theoretically. The conditions for the existence of the coupling effect, and its magnitude as a function of relevant parameters, are determined. In the range of biologically relevant frequencies (30–300 Hz), viscous coupling between pairs of hairs is only very small in the case of the spider Cupiennius salei. Theoretical analysis points to the relatively large spacing between hairs (20 to 50 hair diameters) and the tuning of the hairs to the above-mentioned frequencies to explain the practical absence of coupling.     

噪声习服对听觉损伤的保护作用机制探讨

目的:探讨噪声习服对听觉损伤的保护作用机制.方法:建立噪声习服实验动物模型.采用免疫组织化学、激光扫描共聚焦显微镜(LSCM)及图像分析等技术,定量研究噪声习服后毛细胞内纤维状肌动蛋白(F-actin)、钙调蛋白(CaM)、热休克蛋白70(HSP70)的表达及游离Ca2 浓度的变化.结果:噪声暴露后毛细胞中F-actin、CaM及HSP70的表达均呈增加趋势.与噪声损伤暴露组(H组)比较,噪声习服后损伤暴露组(CH组)中F-actin和HSP70的表达均明显增多,CaM的表达具有增加趋势.声暴露后毛细胞内游离Ca2 浓度升高,噪声损伤暴露组毛细胞内游离Ca2 浓度明显高于噪声习服组(C组)和习服后损伤暴露组.结论:噪声习服使毛细胞对于其后声刺激的保护性反应增强,毛细胞内细胞骨架系统的加强及胞内钙稳态的维持在噪声习服的保护机制中具有重要意义.     

Depression of the melting temperature by moisture for alpha-form crystallites in human hair keratin

DSC thermal analysis has been carried out for human hair samples with various moisture contents to investigate the melting temperature depression behavior of alpha-form crystallites in human hair. This is achieved by adopting a novel technique using silicon oil as the thermal medium, which permits hair samples to retain a range of moisture contents in between completely dry and fully saturated. The results show that the melting temperature of the alpha-form crystallites in human hair varies with moisture content from 205 degrees C for dry hair to 155 degrees C for the hair sample with moisture content of 23%. These experimental results are particularly useful for clarification of the conceptual ambiguities associated with the molecular properties of alpha-helices and alpha-form crystallites. Furthermore, the Flory-Huggins theory was employed to determine the water-helix interaction parameter (chi = 4.5) and the alpha-form crystallinity of human hair (22%), a figure consistent with that obtained by the XRD method (21%).     

Reduction mechanism of L-cysteine on keratin fibers using microspectrophotometry and Raman spectroscopy

In order to investigate the reduction mechanism of L-cysteine (Cys) on keratin fibers, cross-sectional samples of virgin white human hair treated with Cys were prepared. The heterogeneous reaction between Cys and keratin fibers involving the diffusion of Cys into human hair was analyzed at the molecular level using microspectrophotometry and Raman spectroscopy. The diffusion pattern of Cys into human hair showed non-Fickian type characteristics, thus indicating the free amino groups of electrostatically interacted with the anionic ions of the fiber surface. The disconnected relative concentration of -SS- groups at various depths of the hair samples with pH 9.0 was less than the Cys relative concentration, indicating that the reaction rate (the disconnection of -SS- groups) was slower than the diffusion rate of Cys into human hair. From these experiments, we concluded that the free amino groups of Cys electrostatically interacted with the anionic ions of the fiber surface, thereby decreasing the reaction rate (the disconnection of -SS- groups) of Cys at pH 9.0.     

MDR-like ABC transporter AtPGP4 is involved in auxin-mediated lateral root and root hair development

Previous data have suggested an involvement of MDR/PGP-like ABC transporters in transport of the plant hormone auxin and, recently, AtPGP1 has been demonstrated to catalyze the primary active export of auxin. Here we show that related isoform AtPGP4 is expressed predominantly during early root development. AtPGP4 loss-of-function plants reveal enhanced lateral root initiation and root hair lengths both known to be under the control of auxin. Further, atpgp4 plants show altered sensitivities toward auxin and the auxin transport inhibitor, NPA. Finally, mutant roots reveal elevated free auxin levels and reduced auxin transport capacities. These results together with yeast growth assays suggest a direct involvement of AtPGP4 in auxin transport processes controlling lateral root and root hair development.     

灵猫科3种兽针毛显微结构比较

对灵猫科大灵猫、小灵猫、花面狸头部针毛显微结构观察与分析,结果表明：1）3种动物针毛的长度大小不同;毛髓质指数存在显著性差异;2）毛鳞片在近根部和近稍部形状存在差别,主体部分等面积鳞片个数大灵猫、小灵猫与花面狸两两差别显著,而大灵猫与小灵猫无显著性差异（P〉0．05）．这些差异有利于分辨灵猫科的3种动物．     

Structural analysis of human hair single fibres by scanning microbeam SAXS

The origin of the curliness of human hair was revealed by scanning microbeam small angle X-ray scattering (SAXS), based on the nanostructure of keratin fibre arrangement. Scanning microbeam SAXS patterns of single hair fibres have been measured across the fibres and the differences in the patterns between the inner and the outer sides of the curvature were successfully detected. The analysis of the equatorial and azimuthal scattering intensity profiles showed that the arrangement of the intermediate filaments was different between the inner and the outer sides of the curvature. From the analogy with Merino and Romny wool, it is suggested that different types of cortices exist in human hair. It is concluded that, regardless of the ethnic origins (African, Caucasian, and Asian), the macroscopic curl shape of the hair fibre originate from the inhomogeneity of the internal nanostructure, arising from inhomogeneous distribution of two types of cortices.     

Immunofluorescent Identification of Melanocytes in Murine Hair Follicles

Summary Immunocytochemical identification of skin cells are difficult due to numerous endogenous autofluorescent components within the cell and the environment. This is particularly evident in hair follicles. This paper reports on a serendipitous modification to an existing method which results in a drastically reduced background fluorescence. Immediately after antigen retrieval, sections exposed to 0.3% hydrogen peroxide in methanol for 30 min at room temperature exhibited low background fluorescence, increased antigenicity and revealed quantifiable numbers of melanocytes. This method is applicable to both human and mouse melanocytes particularly in the hair follicle.     

Recovery of mechano-electrical transduction in rat cochlear hair bundles after postnatal destruction of the stereociliar cross-links

Mechano-electrical transduction (MET) in the stereocilia of outer hair cells (OHCs) was studied in newborn Wistar rats using scanning electron microscopy to investigate the stereociliar cross-links, Nomarski laser differential interferometry to investigate stereociliar stiffness and by testing the functionality of the MET channels by recording the entry of fluorescent dye, FM1-43, into stereocilia. Preparations were taken from rats on their day of birth (P0) or 1–4 days later (P1–P4). Hair bundles developed from the base to the apex and from the inner to outer OHC rows. MET channel responses were detected in apical coil OHCs on P1. To study the possible recovery of MET after disrupting the cross-links, the same investigations were performed after the application of Ca²⁺ chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA) and allowing the treated samples to recover in culture medium for 0–20 h. We found that the structure and function were abolished by BAPTA. In P0–P1 samples, structural recovery was complete and the open probability of MET channels reached control values. In P3–P4 samples, complete recovery only occurred in OHCs of the outermost row. Although our results demonstrate an enormous recovery potential of OHCs in the postnatal period, the structural component restricts the potential for therapy in patients.     

漠河地区养殖的北极狐冬季被毛性状与保温性能的关系

被毛是哺乳动物最主要的特征之一,其保温功能对动物适应寒冷环境意义重大。为了探讨北极狐(Alopex lagopus)在被毛性状上如何适应寒冷的气候条件,对大兴安岭漠河地区人工养殖北极狐的背中部直针毛、上层绒毛、下层绒毛的长度、毛根细度、毛干细度以及毛密度、单个毛束内的毛数量、毛束密度、复合毛囊最大横切面积、1mm2内复合毛囊最大横切面总面积等14个性状因子进行测量分析。结果表明,北极狐绒毛分为上下两层,下层绒毛的长度、毛根细度和毛干细度均小于上层绒毛,上层绒毛长度与直针毛接近,直针毛长度与上层绒毛、下层绒毛长度均不存在显著相关性;毛密度与毛束密度极度正相关(P0.01),但与毛根细度、毛干细度、单个毛束内的毛数量和1mm2内复合毛囊最大横切面总面积不存在显著相关性,且与复合毛囊最大横切面积的相关性较小;复合毛囊最大横切面积受毛根细度、单个毛束内的毛数量和毛束密度的影响较小。北极狐不是通过降低毛细度的方式来增加毛密度以加强保温功能,而是通过改变被毛在皮肤内的分布格局来增加毛密度,以及将有髓质的绒毛分为上下两层来改变被毛空间结构这两种策略提高被毛内静止空气的量以加强保温功能,进而适应高纬度地区的寒冷环境。