Floral reduction in Crepis tectorum (Asteraceae): tradeoffs and dominance relationships

The present investigation of Crepis tectorum examines the extent to which tradeoffs and patterns of dominance contribute to the association between flower size (head width) and degree of self-fertility among populations adapted to rock outcrops. Partial correlation analyses of phenotypic data from a F2 generation derived from a cross between two outcrop plants and of family means representing one of the parent populations indicate that small-flowered plants fail to reallocate resources to flower and fruit production, that small flower size offers little or no advantage in terms of autofertility, and that floral reduction has little influence on the rate of flower development. Hence, it may be necessary to invoke factors other than tradeoffs to explain the decline in flower size associated with the evolution of autogamy in C. tectorum. Comparison of parent and Fl hybrid means in the crossing experiment suggests incomplete dominance in the alleles for large flower size. Under the assumption that Fl hybrid means reflect the average degree of dominance across loci, I propose inbreeding depression as the basis for some of the reduction in floral morphology.     

顶鼻康吉鳗嗅囊形态的光镜与扫描电镜观察

用光学显微镜和扫描电镜观察了5尾不同体长顶鼻康吉鳗标本嗅囊的形态结构。结果表明：顶鼻康吉鳗嗅囊近卵圆型;嗅囊长径与眼径的比值为1．3～1．6;单个嗅囊的嗅板数为82～122片;嗅板厚度约100μm;嗅板垂直对称地排列于嗅轴两侧,不同部位的嗅板大小和形状不一致;嗅板从嗅轴向两侧分出,至嗅囊腔顶部几乎相互接触;嗅板远离嗅轴端和向嗅囊腔一侧游离,其余部分与嗅囊膜相连;嗅板向嗅囊腔的游离缘分布有许多嗅孔;未观察到次级嗅板,但在嗅板的表面具有脊状隆起和凹陷;嗅板表面密被纤毛,包括非感觉纤毛、感觉纤毛和微绒毛,嗅板远离嗅轴的端部还观察到一种大型的杆状纤毛。嗅板表面存在大量纤毛表明,顶鼻康吉鳗嗅囊的水动力机制应属纤毛摆动型（isosmates）。     

粉尘螨生殖系统形态学研究

粉尘螨Dermatophagoides farinae是一种重要的医学螨类。本文用光镜和扫描电镜研究了粉尘螨雌雄生殖系统的形态和结构。结果表明：雄性生殖系统由睾丸、输精管、 附腺、射精管、阳茎及附属交配器官组成。睾丸位于血腔末端,不成对,精原细胞、精母细胞和精子依照精子发育的顺序有规则地分布在其内部。雌性生殖系统包括交配孔、囊导管、储精囊、囊导管、卵巢、输卵管、子宫、产卵管及产卵孔,其中卵巢由一个中央营养细胞和围绕其周围的卵母细胞组成。     

Correlative 3D imaging of whole mammalian cells with light and electron microscopy

We report methodological advances that extend the current capabilities of ion-abrasion scanning electron microscopy (IA-SEM), also known as focused ion beam scanning electron microscopy, a newly emerging technology for high resolution imaging of large biological specimens in 3D. We establish protocols that enable the routine generation of 3D image stacks of entire plastic-embedded mammalian cells by IA-SEM at resolutions of ∼10–20 nm at high contrast and with minimal artifacts from the focused ion beam. We build on these advances by describing a detailed approach for carrying out correlative live confocal microscopy and IA-SEM on the same cells. Finally, we demonstrate that by combining correlative imaging with newly developed tools for automated image processing, small 100 nm-sized entities such as HIV-1 or gold beads can be localized in SEM image stacks of whole mammalian cells. We anticipate that these methods will add to the arsenal of tools available for investigating mechanisms underlying host-pathogen interactions, and more generally, the 3D subcellular architecture of mammalian cells and tissues.     

Comparative study of the corneal epithelium in some reptiles inhabiting different environments

El‐Bakry, A.M. 2011. Comparative study of the corneal epithelium in some reptiles inhabiting different environments. —Acta Zoologica (Stockholm) 92 : 54–61. The vertebrate cornea functions in either aquatic or aerial environments and in some cases in both. In terrestrial and aerial vertebrates, the cornea contributes most of the refractive powers of the eye because of the large variation in refractive index between the air and the cornea. The present study aimed to examine and compare the main features of the corneal epithelial surface of three reptilian species related to three different families (Caretta caretta, Varanus griseus and Mabuya quinquetaeniata) and inhabiting different environment, by light, scanning (SEM) and transmission electron microscopy. The mean epithelial cell densities of the species of the study were 8.670 ± 3.134, 5.945 ± 2.144 and 2.124 ± 713 respectively. The corneal epithelium of the three species observed by SEM showed a similarity to one another indicating that the apical cell surfaces possess regular polygonal cells with varieties of microprocesses. These microprocesses were represented by microplicae, numerous microvilli and some long microridges in C. caretta, microplicae and minute microholes in V. griseus and microplicae intermingled with short microvilli in M. quinquetaeniata. According to the densities of these microprocesses, three polymorphic cell types (light, medium and dark) appeared in C. caretta, light and medium cell types were observed in V. griseus and medium and dark cell types were noticed in M. quinquetaeniata. Different types of tight adhesions were observed by transmission electron microscopy between the cell borders of the epithelial cells which differ according to environment where the species occupy. In conclusion, variation in the structure of the corneal epithelial cells appears to be related to the living environment, such as aerial, terrestrial and aquatic ones, which is occupied by every species.     

The Structure and Morphogenesis of the Ventral Ciliature in Paraurostyla hymenophora*

SYNOPSIS. The structure and morphogenesis of the ventral ciliature of Paraurostyla hymenophora (Stokes) are described. The oral primordium apparently originates in association with transverse cirrus #6, from which it migrates anteriorly simultaneous with kinetosomal proliferation. The primordium eventually forms an elongate ciliary field from which the future opisthe's fronto-ventro-transverse (FVT) and undulating membrane primordial fields arise. Concomitantly, the future proter's FVT primordial field is initiated by the disaggregation of frontal cirri #4, #5, and #6. Primordia then develop simultaneously within marginal and ventral cirral rows by a disaggregation of cirri within the respective rows, and do not give rise to new cirri until the FVT fields complete segregation into discrete cirri. Near the completion of cirral production from the FVT primordia, each ventral cirral primordium (VCP) forms the 2 rightmost transverse cirri. Segregation of new cirri within the marginal cirral primordia and VCP then occurs, eventually replacing all old cirri within their respective marginal and ventral cirral rows. At the end of cortical morphogenesis, all old ciliary organelles, with the exception of the adoral zone of membranelles, are either reorganized or replaced. These results suggest an evolutionary affinity between the ventral and marginal cirral rows and raise questions about the control of the developmental competence of individual primordia.     

The pollen morphology of Vicia (Leguminosae)

The pollen morphology of 32 species of the genus Vicia was studied using scanning and transmission electron microscope (SEM and TEM). The interstitia of the pollen of the examined species were found to be either regular columellate, irregular columellate, or granular. The granular pattern was recognized to be apomorphy against the columellate patterns in the tribe Vicieae by comparison with the pollen in the tribes Vicieae, Cicereae, Galegeae, Hedysareae, and Trifolieae. The group of Vicia species having the apomorphy was congruent with that having a known apomorphy of the pistil character. This group with such synapomorphies may be monophyletic, though it is treated as polyphyletic in the present infrageneric system of Vicia.     

Pollen morphology of the Dimorphandra group (Leguminosae,Caesalpinioideae)

The Dimorphandra group, as traditionally circumscribed, is a rather diverse assemblage of genera in Leguminosae subfamily Caesalpinioideae that share certain morphological characteristics with the basally branching lineages of subfamily Mimosoideae. It currently comprises 51 species in seven genera: Burkea (1 species), Dimorphandra (26 species), Erythrophleum (10 species), Mora (6 species), Pachyelasma (1 species), Stachyothyrsus (2 species) and Sympetalandra (5 species). This study investigates the pollen morphology of 25 samples from 19 species of all seven genera. Pollen of the Dimorphandra group is small, isopolar, trizonocolporate and released in monads. Apertures are almost equal to polar length, with correspondingly small apocolpial areas. The shape of the aperture apices varies from acute to wide and rounded. Surface ornamentation is psilate, perforate, microreticulate, or perforate‐rugulate. The wall structure is usually columellate with a well developed foot layer. The pollen is small and unspecialised, agreeing with a previously noted pattern of more fixed and homogenous pollen structure in the more derived clades in subfamily Caesalpinioideae, compared with the great diversity of pollen types found in the basally branching lineages.     

Floral ontogeny in ficinia and isolepis (cyperaceae), with focus on the nature and origin of the gynophore

BACKGROUND AND AIMS: The generic delimitations of Ficinia and Isolepis, sister genera in the Cypereae, are blurred. Typical Ficinia flowers have a lobed gynophore, which envelops the base of the nutlet, whereas in Isolepis the character is considered to be absent. Some former species of Isolepis, lacking the gynophore, were recently included in Ficinia. The floral ontogeny of representative taxa in Ficinia and Isolepis were investigated with the aim of evaluating the origin and nature of the gynophore in the Cypereae. METHODS: The spikelet and floral ontogeny in inflorescences collected in the field was investigated using scanning electron microscopy (SEM) and light microscopy (LM). KEY RESULTS: SEM images of Isolepis setacea and I. antarctica, Ficinia brevifolia, F. minutiflora, F. zeyheri and F. gracilis, and LM sections of F. radiata, show that the gynoecium in Ficinia is elevated above the flower receptacle by the development of a hypogynous stalk. From its apex, a (often three-)lobed cup is formed, which envelopes the basal part of the later nutlet. In developing flowers of I. antarctica, a rudimentary hypogynous stalk appears. In I. setacea, rudiments of a hypogynous stalk can be observed at maturity. In F. radiata and F. zeyheri, intralocular hairs are present in the micropylar zone. At the surface of developing gynoecia in flowers of F. gracilis, star-shaped cuticular structures appear which disappear again at maturity. CONCLUSIONS: The overall floral ontogeny of all species studied occurs following a typical scirpoid pattern, though no perianth primordia are formed. The gynophore in Ficinia originates as a hypogynous stalk, from which the typical gynophore lobes develop. The gynophore is not homologous with the perianth.     

长角凤仙花（凤仙花科）的花器官发生和发育

以不同发育时期的长角凤仙花Impatiens longicornuta Y.L.Chen（凤仙花科Balsaminaceae）为材料,利用扫描电镜技术观察了其花器官的分化及其发育过程。长角凤仙花为两侧对称花,具2枚侧生萼片,唇瓣囊状,旗瓣具鸡冠状突起,雄蕊5枚,子房上位,5心皮5室。其花器官分化顺序为向心式,萼片—花瓣—雄蕊—雌蕊原基。2枚侧生萼片先发生,然后近轴萼片（即唇瓣）原基和2枚前外侧萼片原基近同时发生;但是这3枚萼片原基的发育不同步,远轴的2枚前外侧萼片原基的发育渐渐滞后,然后停止发育,最后渐渐为周围组织所吸收,直至消失不见。花瓣原基中,旗瓣原基最先发生,4个侧生花瓣原基相继成对发生,且之后在基部成对愈合形成翼瓣;5枚雄蕊原基几乎同时发生,5个心皮原基轮状同时发生。本文结果支持凤仙花属植物为5基数的花,并进一步证实了唇瓣的萼片来源;此外,研究结果表明花器官早期发育资料对植物系统与进化研究具有重要参考价值。