Role of keratinocyte‐derived factors involved in regulating the proliferation and differentiation of mammalian epidermal melanocytes

Melanocytes characterized by the activities of tyrosinase, tyrosinase‐related protein (TRP)‐1 and TRP‐2 as well as by melanosomes and dendrites are located mainly in the epidermis, dermis and hair bulb of the mammalian skin. Melanocytes differentiate from melanoblasts, undifferentiated precursors, derived from embryonic neural crest cells. Because hair bulb melanocytes are derived from epidermal melanoblasts and melanocytes, the mechanism of the regulation of the proliferation and differentiation of epidermal melanocytes should be clarified. The regulation by the tissue environment, especially by keratinocytes is indispensable in addition to the regulation by genetic factors in melanocytes. Recent advances in the techniques of tissue culture and biochemistry have enabled us to clarify factors derived from keratinocytes. Alpha‐melanocyte‐stimulating hormone, adrenocorticotrophic hormone, basic fibroblast growth factor, nerve growth factor, endothelins, granulocyte‐macrophage colony‐stimulating factor, steel factor, leukemia inhibitory factor and hepatocyte growth factor have been suggested to be the keratinocyte‐derived factors and to regulate the proliferation and/or differentiation of mammalian epidermal melanocytes. Numerous factors may be produced in and released from keratinocytes and be involved in regulating the proliferation and differentiation of mammalian epidermal melanocytes through receptor‐mediated signaling pathways.     

A microhistological survey on the trees of a relict subtropical laurel forest from the Macaronesian Islands as a base for assessing vertebrate plant diet

A microhistological collection and its respective key on the leaves and fleshy fruits produced by the mostly endemic trees that integrate the relict laurel forest in the Macaronesian Islands are presented. Epidermal tissues from the adaxial and abaxial surfaces of leaves and fruits of 23 species were extracted by scraping and prepared on individual microscope slides. An optical microscope with a camera lucida fixed at magnifications of ×400 was used to analyse and to draw the morphological traits of epidermal tissues to the same scale. Furthermore, quantitative data for those congeneric species were also obtained by using an image analysis program system. The results indicate that this microhistological method permits the differentiation of practically all species of trees present in the Macaronesian laurel forest. Furthermore, most species belonging to the same taxa (genus or family) show a general common pattern in the morphology of the different epidermal traits. Lastly, despite the effort that constitutes the preparation of plant microhistological collections of a determined ecosystem, it is of basic importance because it makes possible the performance of feeding ecological studies of several herbivorous and frugivorous vertebrate species. These results provide crucial information that elucidates the functioning of the food web and energetic flux dynamics of the Macaronesian laurel forest ecosystem.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 409–426.     

中国大蒜芥属（十字花科）叶表皮微形态学研究

利用光学显微镜观察了中国十字花科大蒜芥属9种1变种植物的叶表皮形态。结果表明：中国大蒜芥属植物叶上表皮细胞通常为多边形,垂周壁平直或弓形,少有稍浅波状,叶下表皮细胞为不规则形,垂周壁波状或深波状;气孔器类型均以不等细胞型为主,少有无规则型,偶有平列型。依据叶表皮特征,可将中国大蒜芥属划分为三种类型：（1）叶上表皮无气孔分布或偶见;（2）叶上表皮气孔常明显几个聚成一簇或排成短列,气孔密度小于叶下表皮;（3）叶上表皮气孔比较均匀分布,气孔密度与叶下表皮近相似。     

27种木犀属植物叶表皮微形态特征的研究

利用光学显微镜和扫描电子显微镜观察了27种木犀属植物的叶表皮,测量并统计了气孔器类型、气孔大小、气孔密度、气孔指数及腺点密度等指标,以明确各种的叶表皮细胞形状及垂周壁式样、表皮角质膜、蜡质纹饰及气孔外拱盖的具体特征。结果显示:木犀属植物叶下表皮有气孔器,形状为圆形、椭圆形;气孔器类型多为不规则型,只有总状桂花和狭叶木犀为环列型;气孔器外围角质层有放射状、条状、环状、颗粒状等多种类型;叶表皮细胞形状有无规则形和多边形2种;下表皮腺点的数目远远大于上表皮。研究表明,木犀属植物气孔器和叶表皮细胞特征在种之间差异比较明显,可以作为种间鉴定的重要依据,具有重要的分类学意义。     

杜鹃花属照山白叶表皮及花粉形态的研究

利用光学显微镜和扫描电子显微镜对杜鹃花属植物照山白的叶表皮及花粉形态进行了观察,该种的叶表皮细胞表面光滑,胞间界限明显;叶上下表皮均有盾状鳞,上表皮仅有针状毛;气孔器仅见于下表皮,分布稀疏,副卫细胞和保卫细胞表面光滑。扫描电镜下可见该种的花粉为四合花粉,呈正四面体排列,具三沟,表面纹饰为负网状雕纹,局部区域有大颗粒状突起。     

不同烟草品种叶下表皮微形态学特征的研究

利用扫描电镜及光学显微镜对烤烟、晒烟及野生烟共29个品种叶下表皮微形态学特征进行了观察,发现相同类型的烟草品种间表现出一些共同特征,但不同类型的烟草品种间其叶下表皮微形态学特征又存在一定的差异。烤烟气孔外拱盖内缘较丰富,晒烟次之,野生烟在所观察的品种中只有1种类型;烤烟气孔密度和长度的变幅比较大,晒烟则比较稳定;烤烟、晒烟细胞间多有突起,保卫细胞极区常见“T”型加厚,绝大多数有角质环边;而所观察的两个野生烟品种均无细胞间突起,无保卫细胞极区加厚,亦无角质环边。这些观察结果为烟草分类研究提供了有价值的参考依据。同时本文还探讨了烟草亲本与子代之间在叶下表皮微形态学特征上的关联性。     

不同产地华中五味子叶表皮结构和导管分子的解剖学特征及其与环境因子的关系

在光学显微镜下观察了不同产地华中五味子(Schisandra sphenanthera Rehd.et Wils．)叶表皮结构和导管分子特征,应用多元回归方法对不同产地华中五味子的叶表皮特征及导管分子特征与环境因子的关系进行了分析。观察的指标有叶表皮特征(气孔器密度、气孔器指数、气孔器长宽、气孔器面积、气孔极区角质加厚、气孔器类型、表皮细胞垂周壁形状、分泌细胞密度及叶表面角质条纹)和导管分子特征(导管分子长度、直径、长／直径比值及穿孔板类型)。观察结果：上表皮有极少量气孔器和分泌细胞分布。在下表皮,气孔器类型为平列型和侧列型,气孔器指数为15．05％-22．53％,气孔器长59．2—74．2μm,气孔器宽37．9—46．8μm,分泌细胞密度为1．45／mm^2-3．99／mm^2。导管分子以具缘纹孔导管为主,穿孔板包含单穿孔和梯状穿孔板。导管分子长957．8—1270．2μm,导管分子直径85．0—136．7μm。随着产地的不同,华中五味子叶下表皮结构和导管分子的解剖特征有明显的差异。分析结果显示：年均气温与气孔器面积和气孔器长度,年降水量与气孔器宽度以及相对湿度与分泌细胞密度之间关系密切。随着年平均气温的升高,气孔器面积、气孔器长度呈减少的趋势,R^2值分别为0．74、0．71。随着年降水量的增加,气孔器宽呈减小的趋势,R^2值为0．64;导管分子长／直径比值增加,R^2值为0．46。相对湿度与分泌细胞密度呈正相关,R^2为0．63。     

Reappraisal of Microtropis macrocarpa C.Y. Cheng & T.C. Kao (Celastraceae), a critically endangered species endemic to Yunnan, China

Microtropis macrocarpa C.Y. Cheng & T.C. Kao has been treated as a synonym of Microtropis macrophylla Merr. & Freeman in most taxonomic reports in China. According to our study, M. macrocarpa is an independent species endemic to Yunnan, China. Microtropis macrophylla and Microtropis pachyphylla Merr. & Freeman should be treated as synonyms of Microtropis longifolia Wall. ex Kurz. M. macrocarpa is also identified as a critically endangered species, CR B 1 ab (i,ii,iii,v), based on the IUCN Red List Categories and Criteria. The foliar surface, anther and pollen structures were also observed with a scanning electron microscope.     

Morphological characteristics of leaf epidermis and size variation of leaf, flower and fruit in different ploidy levels in Buddleja macrostachya (Buddlejaceae)

Buddleja macrostachya (Buddlejaceae) is a widespread shrub native to the Sino-Himalayan mountains and beyond. It has been found to occur at two ploidy levels, hexaploid, 2n=6x=114 and dodecaploid, 2n=12x=228. To determine if morphological characters might be used as indicators of ploidy levels, we measured floral and fruit length, relative and absolute leaf size, trichome density on both leaf surfaces, and stomatal density and length in different populations of B. macrostachya. In general, flower and fruit length, absolute leaf size, and stomatal length increased with an increase at ploidy level (P<0.01), whereas adaxial cell and stomatal density decreased with an increase at ploidy level (P<0.01). We found no conspicuous differences in relative leaf size (P>0.05) in different populations. Other characters studied such as trichome type, cuticular membrane and ornamentation of stomata, cell and stomatal shape, and anticlinal wall pattern were quite constant in this species. Thus it appears that flower and fruit length, absolute leaf size, and stomatal frequency and length can be used to distinguish hexaploid from dodecaploid cytotypes either in the field or in herbarium specimens.