Development of cell surface activity and cell surface adhesiveness in early embryos of the newt,Cynops pyrrhogaster

The development of cell surface activity and adhesiveness was examined in relation to cleavage number in early embryos of the newt, Cynops pyrrhogaster. Both large hyaline bleb formation and surface adhesiveness to substratum were manifested in presumptive ectodermal cells isolated from embryos after the eleventh cleavage (mid-blastula stage). Scanning electron microscopy of the inner surface of the blastocoelic wall (presumptive ectodermal cell layer) revealed the formation of large blebs after the eleventh cleavage. Treatment with alcian blue and lanthanum nitrate demonstrated the accumulation of an extracellular matrix (ECM) on the surface of large blebs.     

The ultrastructure of mitosis during sporangiogenesis inWoronina pythii (Plasmodiophoromycetes)

Summary Mitotic divisions during sporangiogenous plasmodial cleavage inWoronina pythii were studied with transmission electron microscopy. We conclude that these nuclear divisions (e.g., transitional nuclear division, and sporangial mitoses) share basic similarities with the cruciform nuclear divisions inW. pythii and other plasmo-diophoraceous taxa. The major distinction appeared to be the absence of nucleoli during sporangial mitosis and the presence of nucleoli during cruciform nuclear division. The similarities were especially evident with regard to nuclear envelope breakdown and reformation. The mitotic divisions during formation of sporangia were centric, and closed with polar fenestrae, and characterized by the formation of intranuclear membranous vesicles. During metaphase, anaphase, and telophase, these vesicles appeard to bleb from the inner membrane of the original nuclear envelope and appeared to coalesce on the surface of the separating chromatin masses. By late telophase, the formation of new daughter nuclear envelopes was complete, and original nuclear envelope was fragmented. New observation pertinent to the mechanisms of mitosis in thePlasmodiophoromycetes include a evidence for the incorporation of membrane fragments of the original nuclear envelope into new daughter nuclear envelopes, and b the change in orientation of paired centrioles during sporangial mitosis.     

青花菜BoSCL3基因的克隆和渍水胁迫下的表达特征分析

为了解SCL3 (scarecrow-like 3)基因的功能,从青花菜(Brassica olreacea var. italica)中克隆得到1个SCL3基因,命名为BoSCL3,其cDNA全长1 355 bp,编码446个氨基酸。BoSCL3分子量为49.96 kD,为疏水性蛋白,与油菜(B. napus)、芜菁(B. rapa)中SCL3蛋白的亲缘关系最近,同科植物的SCL3具有较高的同源性。荧光定量PCR分析结果表明,青花菜BoSCL3基因表达量随渍水胁迫时间延长先下降后上升,推测其可能参与渍水胁迫响应。这为探讨青花菜BoSCL3基因响应渍水胁迫的分子机制提供理论依据。     

EhRho1 regulates plasma membrane blebbing through PI3 kinase in Entamoeba histolytica

The protozoan parasite Entamoeba histolytica causes amoebiasis, a major public health problem in developing countries. Motility of E. histolytica is important for its pathogenesis. Blebbing is an essential process contributing to cellular motility in many systems. In mammalian cells, formation of plasma membrane blebs is regulated by Rho‐GTPases through its effectors, such as Rho kinase, mDia1, and acto‐myosin proteins. In this study, we have illuminated the role of EhRho1 in bleb formation and motility of E. histolytica. EhRho1 was found at the site of bleb formation in plasma membrane of trophozoites. Overexpression of mutant EhRho1 defective for Guanosine triphosphate (GTP)‐binding or down‐regulating EhRho1 by antisense RNA resulted in reduced blebbing and motility. Moreover, serum‐starvation reduced blebbing that was restored on serum‐replenishment. Lysophosphatidic acid treatment induced bleb formation, whereas wortmannin inhibited the process. In all these cases, concentration of GTP‐EhRho1 (active) and Phosphatidylinositol 4,5‐bisphosphate (PIP2) inversely correlated with the level of plasma membrane blebbing. Our study suggests the role of EhRho1 in blebbing and bleb‐based motility through PI3 kinase pathway in E. histolytica.     

The GRAS protein SCL13 is a positive regulator of phytochrome-dependent red light signaling, but can also modulate phytochrome A responses

Phytochrome photoreceptors enable plants to perceive divergent light signals leading to adaptive changes in response to differing environmental conditions. However, the mechanism of light signal transduction is not fully understood. Here we report the identification of a new signaling intermediate from Arabidopsis thaliana, Scarecrow-like (SCL)13, which serves as a positive regulator of continuous red light signals downstream of phytochrome B (phyB). SCL13 antisense lines exhibit reduced sensitivity towards red light, but only a distinct subset of phyB-mediated responses is affected, indicating that SCL13 executes its major role in hypocotyl elongation during de-etiolation. Genetic evidence suggests that SCL13 is also needed to modulate phytochrome A (phyA) signal transduction in a phyB-independent way. The SCL13 protein is localized in the cytoplasm, but can also be detected in the nucleus. Overexpression of both a nuclear and cytoplasmic localized SCL13 protein leads to a hypersensitive phenotype under red light indicating that SCL13 is biologically active in both compartments. SCL13 is a member of the plant-specific GRAS protein family, which is involved in various different developmental and signaling pathways. A previously identified phytochrome A signaling intermediate, PAT1, belongs to the same subbranch of GRAS proteins as SCL13. Although both proteins are involved in phytochrome signaling, each is specific for a different light condition and regulates a different subset of responses.     

Developmental Expression of D-Galactoside-Binding Lectin in Sea Urchin (Anthocidaris crassispina) Eggs

The spatial and temporal expression of a sea urchin (Anthocidaris crassispina) egg lectin (SUEL) during early embryogenesis was studied using antiserum raised against SUEL. Western blotting analysis revealed the presence of SUEL in all stages so far examined, from unfertilized eggs to gastrula stage embryos. Immunofluorescence and immunoelectron microscopic observation showed that SUEL was stored in small electron-dense granules which migrated to the cortex within 10 min after fertilization. SUEL was localized in the cortical cytoplasm of the blastomere during cleavage stages and subsequently migrated to the outer surface of the embryo, including the invaginated portion of the gastrula. Immunoelectron microscopic study indicated that SUEL was deposited in the hyaline layer at least at the mid gastrula stage. Migration of SUEL to the cortex was significantly reduced by treatment with cytochalasin B, suggesting that actin filaments play an important role in this translocation. Exogenously added SUEL was adsorbed at the surface of unfertilized eggs and hatched embryos, but not to embryos with fertilization membrane. Lactose inhibited this adsorption, suggesting the presence of an endogenous glycoligand(s) specific for SUEL on the surface of unfertilized eggs and in the hyaline layer. We conclude that SUEL is secreted at a certain stage of embryogenesis and specifically adsorbed to the hyaline layer. Temporal changes in extraembryonic matrices caused by SUEL seem to play an important role in developmental morphogenesis.     

The “hyaline body” of the root parasiteAlectra orobanchoides benth. (Scrophulariaceae)—Its anatomy,ultrastructure and histochemistry

Summary Differentiation of a specialized tissue, the so-called hyaline body, has been demonstrated in the haustorial neck of the root parasite,Alectra orobanchoides, growing on some of its hosts,Helianthus annum L. andSesamum indicum L. This body is characterized by small, but densely structured cells and unusual extracellular deposits. The entire tissue, as well as the deposits, enlarge drastically during development of the parasite. The hyaline tissue is closely associated with conductive elements-especially the phloem-which traverse and surround the body. Histochemical characterization of the extracellular deposits revealed a polysaccharidic as well as proteinaceous components. The possible role of the hyaline body is at present still obscure.     

毛竹PeSCL3基因表达特征及其启动子活性研究

为探讨毛竹(Phyllostachys edulis)SCL3基因的表达特征及其启动子活性,采用同源克隆的方法从毛竹中分离到SCL3同源基因Pe SCL3的编码区(ORF)和上游启动子序列(Pe SCL3p)。序列分析表明,Pe SCL3的ORF为1335 bp,推测编码含444氨基酸的蛋白,该蛋白与水稻(Oryza sativa)的SCL3同源性高达93.9%。Pe SCL3p长度为1358 bp,含有脱落酸(ABA)应答元件ABRE、赤霉素(GA3)应答元件GARE-motif和P-box、干旱诱导MYB结合位点等多种作用元件。实时定量PCR分析结果表明,Pe SCL3在毛竹叶中的表达丰度最高,其次是茎和根,而鞘中的最低;Pe SCL3的表达受GA3的抑制,受ABA、Na Cl和干旱的诱导。转Pe SCL3p∷GUS拟南芥(Arabidposis thaliana)的GUS染色结果表明,根尖、顶端生长点和子叶叶柄均被染成蓝色,尤其根尖的染色最深。这表明Pe SCL3对毛竹的生长发育,尤其是根系,可能起着重要的调控作用。     

The morphometrics and colouration of the European pond turtle Emys orbicularis in Lubuskie province (West Poland)

The European pond turtle Emys orbicularis, is an endangered species in Poland. The region of the Ilanka River, in the western part of the country (Lubuskie province), is the most densely inhabited area by the species. Several populous sites are dispersed over the whole area of the province. Over the past 10 years, 279 turtles were captured at 11 sites. In 218 individuals, those with a straight carapace length (SCL) between 2.10–12.10 cm, sex was not determined; the remaining 61 with SCL 13.33–19.85 cm were sexed. Females had bigger bodies and were heavier than males. The SCL of females was 17.10 ± 1.7 cm (average ± SD, n = 33), their body mass (BM) was 790.6 ± 228.7 g (n = 27), and in the case of males SCL was 15.44 ± 1.5 cm and BM was 554.2 ± 138.8 g (n = 28). SCL of the smallest egg laying female was 15.30 cm, and SCL of the smallest mating male was 13.33 cm. The colouration of the turtles which undergoes change with age can be varied.     

Pearl millet downy mildew (Sclerospora graminicola): Zoosporogenesis

Summary Cleavage of the zoosporangial cytoplasm ofSclerospora graminicola, the causal agent of pearl millet downy mildew, is by means of the fusion of cleavage vesicles and vesicles containing the extruded axoneme with the cell membrane. This type of zoosporogenesis linksS. graminicola to other Peronosporalean species, and is very similar to that seen for all uniflagellate species examined to date, while it separates it from species of theSaprolegniales where zoosporogenesis is brought about by the expansion of the central vacuole, or where the plasmalemma alone is used.The origin of the cleavage vesicles appears to be from the dictyosomes and not from the finger-print bodies which are rapidly formed in large numbers after axoneme formation and after the cleavage. vesicles have started to appear in the cytoplasm.     

Inhibition of placental growth factor improves surgical outcome of glaucoma surgery

Excessive post‐operative wound healing with subsequent scarring frequently leads to surgical failure of glaucoma filtration surgery (trabeculectomy). We investigated the hypothesis that placental growth factor (PlGF) plays a role in post‐operative scar formation, and that it therefore may be a target for improvement of filtration surgery outcome. ELISA experiments showed that PlGF levels were significantly increased in aqueous humour of glaucoma patients and after VEGF treatment, which may indicate an important contribution of this growth factor to wound healing after trabeculectomy. Using a mouse model of glaucoma filtration surgery, we were able to show that intracameral injection of a previously characterized anti‐PlGF antibody (ThromboGenics NV) significantly improved surgical outcome by increasing bleb survival and bleb area. This was associated with a significant reduction in post‐operative proliferation, inflammation and angiogenesis during the first post‐operative days after surgery, and with a decrease in collagen deposition at later stages. Furthermore, inhibition of PlGF seemed to be more effective than anti‐VEGF‐R2 treatment in improving surgical outcome, possibly via its additional effect on inflammation. These results render PlGF an appealing target for ocular wound healing and point to potential therapeutic benefits of PlGF inhibition for the prevention of surgical failure.     

Water permeability of plant cuticles

Using the system vapor/membrane/liquid, permeability coefficients of cuticular transpiration (P _ct) were determined as functions of water activity in the vapor (a _wv). Enzymatically isolated cuticular membranes (CM) of Citrus aurantium L. and nonisolated CM of onion bulb scales and eggplant fruits were investigated. P _ct of Citrus and eggplant CM decreased with decreasing a _wv, while permeability coefficients of CM of onion were independent of a _wv. Extraction of soluble cuticular lipids (SCL) from the CM of Citrus increased permeability coefficients by a factor of approximately 500. This extraction had no effect on the dependence of P _ct on a _wv.Treating cuticular membranes as a resistance network consisting of SCL and the polymer matrix, it is shown that the permeability of onion CM is determined by the resistance of the SCL arranged in series with the polymer matrix. In this type of CM liquid and vapor are separated by a continuous, nonporous layer of SCL, and the driving force of transpiration is the gradient of partial pressure of water vapor across the SCL layer. In the CM of Citrus and eggplant, the SCL layer is traversed by polar pores that swell or shrink depending on a _wv. However, liquid continuity is maintained across these membranes down to a _wv=0.22, the lowest value used. In this type of membrane the driving force of transpiration is the water potential gradient across the membrane.Abbreviations CM cuticular membrane - MX polymer matrix - SCL soluble cuticular lipids - HEPES N-2-hydroxyethylpiperazine-N-2-ethane sulfonic acid - MES (N-morpholino)ethane sulfonic acid - SADH succinic acid 2,2-dimethyl hydrazide     

Conditioning of the culture medium by suspension cells and formation of somatic proembryo in Araucaria angustifolia (coniferae)

Summary Cell masses of Araucaria angustifolia cultured in LP liquid medium showed different uptake and utilization patterns for different sugars. Fructose was slowly utilized by cell growth during the lag phase. After this lag period, fructose concentration decreased quickly, corresponding to the start of linear growth. Glucose rapidly decreased following fructose depletion. The level of extracellular proteins in the culture medium increased for the first 5 d after cell inoculation, during the transition from the lag phase to the high-growth phase. The pH of the medium decreased through the first half of the culture period (4.94) and increased (5.6) thereafter. Proembryos originated from a single cell, without a cleavage process. Suspensor cells and proembryonal groups developed independently. Only embryogenic cells divided and formed a suspensor or a proembryo group, which differentiated further along the longitudinal axis. The pathway observed for proembryo formation in Araucaria differs from the model proposed for other conifers, which show cleavage polyembryony.     

Three new <Emphasis Type="Italic">Ophiostoma</Emphasis> species isolated from Japanese red pine

Three new species of Ophiostoma found on Japanese red pine are described as Ophiostoma pusillum sp. nov., O. botuliforme sp. nov., and O. nigrogranum sp. nov. Ophiostoma pusillum is characterized by oblong ascospores and a Hyalorhinocladiella anamorph. Ophiostoma botuliforme has ostioles covered with a hyaline gelatinous cap, allantoid ascospores, and a Pesotum anamorph with hyaline to pale brown stipes. Ophiostoma nigrogranum has hyaline ostiolar hyphae with rounded tips, allantoid ascospores, and sclerotium-like structures.Contribution no. 172, Laboratory of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba     

Description ofAvesicladiella gen. nov. (hyphomycetes) for two undescribed leaf litter microfungi

The new hyphomycete genusAvesicladiella with two species,A. britannica sp. nov., type species, andA. microsperma sp. nov., is described and illustrated. Both species are leaf litter microfungi. The genus closely resemblesVesicladiella, Circinotrichum, Gyrothrix, Ceratocladium andVermiculariopsiella, several hyphomycete genera with comparable characters such as superficial hyphal networks; production of setae; absence of conidiophores; lageniform or ampulliform conidiogenous cells; and hyaline aseptate conidia produced in clusters around the apices of conidiogenous cells. The new genus differs from these by its hyaline, septate setae, typical ‘phialidic’ conidiogenous cells, and hyaline, aseptate cylindrical conidia.     

Conservation and Diversification of <Emphasis Type="Italic">SCARECROW</Emphasis> in Maize

The SCARECROW (SCR) gene in Arabidopsis is required for asymmetric cell divisions responsible for ground tissue formation in the root and shoot. Previously, we reported that Zea mays SCARECROW (ZmSCR) is the likely maize ortholog of SCR. Here we describe conserved and divergent aspects of ZmSCR. Its ability to complement the Arabidopsis scr mutant phenotype suggests conservation of function, yet its expression pattern during embryogenesis and in the shoot system indicates divergence. ZmSCR expression was detected early during embryogenesis and localized to the endodermal lineage in the root, showing a gradual regionalization of expression. Expression of ZmSCR appeared to be analogous to that of SCR during leaf formation. However, its absence from the maize shoot meristem and its early expression pattern during embryogenesis suggest a diversification of ZmSCR in the patterning processes in maize. To further investigate the evolutionary relationship of SCR and ZmSCR, we performed a phylogenetic analysis using Arabidopsis, rice and maize SCARECROW-LIKE genes (SCLs). We found SCL23 to be the most closely related to SCR in both eudicots and monocots, suggesting that a gene duplication resulting in SCR and SCL23 predates the divergence of dicots and monocots. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Multinucleate cyst formation in Acetabularia mediterranea after x-irradiation

Cells of Acetabularia mediterranea were irradiated with increasing doses of X-rays (64.5–258·10^-4 kC kg^-1). The cells are radioresistant up to 193.5·10^-4 kC kg^-1 in terms of growth and progression through he life cycle but the morphogenesis of whorls, caps, and cysts is accompanied by morphological alterations. Microscopical examination of cyst bearing caps in irradiated cells has shown the presence of giant cysts neighboring particularly small ones. Photographic recording of cyst development showed that the multinucleate cap cytoplasm partitions into multinucleate portions rather than uninucleate ones as in the control cells. After complete cleavage a cyst wall is deposited onto the multinucleate cytoplasm. In contrast to uninucleate cysts with one lid the wall contains multiple lids. Their number appears to correspond to the number of nuclei in the cytoplasm compartment during cleavage. The results indicate that X-rays preferentially inhibit the synthesis of a factor which plays a role in establishing the normal spatial morphogenetic pattern necessary for cyst formation.     

The effect of monensin on gametogenesis and zoosporogenesis in the aquatic fungus,Allomyces macrogynus

Summary Cytoplasmic cleavage in the gametangia and zoosporangia ofA. macrogynus was studied using monensin, an ionophore known to disrupt several endomembrane functions in plant and animal cells. Monensin interfered with normal gamete and zoospore formation in a dose dependent manner such that at a 20 M concentration very abnormal cells were released from the reproductive structures. It was evident that monensin's effect was most pronounced during the first 25 minutes of gametogenesis and parallels in time the onset and continuation of the cytoplasmic cleavage events. Observations using fluorescence and differential interference contrast microscopy indicated that the ionophore inhibited normal cytoplasmic cleavage resulting in the production of multinucleate cells, many of which had either no flagella or multiple flagella. Transmission electron microscopy showed that the monensin-treated gametangia had many large vacuoles which contained amorphous electron-opaque material. X-ray microprobe analysis demonstrated that the elemental composition of the large vacuoles was identical to that of the dense globular inclusions seen in untreated gametangia, and morphological analysis confirmed the relationship between these endomembrane structures. Thus this swollen endomembrane component probably is not involved in the cleavage process. Single endomembrane cisternae which were very common in untreated gametangia were seldom seen in monensin-treated preparations. Instead, many smaller electron-transparent vacuoles were observed. These swollen cisternae may both represent monensin-modified Golgi apparatus equivalents and/or play a critical role during the process of gametogenesis and zoosporogenesis inA. macrogynus.     

Development of the hyaline layer around the planktonic embryos and larvae of the asteroid Patiriella calcar and the presence of associated bacteria

Summary

The hyaline layer (HL) around the embryos and larvae of Patiriella calcar is examined by transmission electron microscopy. P. calcar hatches at the gastrula stage and develops through a lecithotrophic planktonic brachiolaria. The hyaline layer of unhatched P. calcar is poorly developed and is comprised of wispy fibrils scattered among the epithelial microvilli. Fibrils are also occasionally seen associated with the inner surface of the fertilization envelope. By the hatched gastrula stage, the hyaline layer is organized into three strata: the intervillous layer, the supporting layer and the coarse outer meshwork layer. Seven-day-old brachiolaria also have a hyaline layer comprised of three strata. In these larvae the supporting layer elevates away from the epithelial surface due to the tuft-like organization of the underlying microvilli. This results in the formation of local outpockets giving the surface of the HL a lobed appearance. Bacteria are occassionally seen in the intervillous layer, particularly in association with the outpockets. These bacteria are phagocytosed by the epithelial cells and, in larvae that have bacteria, may play an augmentive role in larval nutrition. The structure of the hyaline layer of P. calcar is compared with that of the hyaline layer of other Patiriella species to determine if it is more similar to the external coats around its planktonic (P. regularis) or benthic (P. exigua) developing congeners. The comparison shows that the hyaline layer of P. calcar is virtually identical to that of P. regularis, a similarity that may reflect the pelagic life histories of these species.     

Teliospores of smut fungi general aspects of teliospore walls and sporogenesis

Summary The concept and nomenclature for the elements of teliospore walls in smut fungi are presented and a survey of teliosporogenesis is given, as seen by light and transmission electron microscopy. Four developmental types are distinguished: the Ustilago, Microbotryum, Tilletia, and Entorrhiza type. In the Ustilago type, sporogenous hyphae are completely segmented into teliospore initials which are embedded in a hyaline matrix formed by gelatinised hyphal walls (found in species ofAnthracoidea, Cintractia, Heterotolyposporium, Kuntzeomyces, Macalpinomyces, Melanopsichium, Sporisorium, Testicularia, Tolyposporium junci, Trichocintractia, and species ofUstilago infecting members of the family Poaceae). In the Microbotryum type, septate sporogenous hyphae are also completely segmented into teliospore initials, however, they are not surrounded by a hyaline matrix (Microbotryum, Sphacelotheca, Ustilago spp. infecting dicotyledons). A yeast-like budding of teliosporogenic cells is observed for some species ofMicrobotryum, Sphacelotheca, andUstilago infecting dicotyledons. In the Tilletia type, teliospores differentiate locally in the sporogenous hyphae, in an apical or intercalary position, without a hyaline matrix (Conidiosporomyces, Doassinga, Entyloma, Erratomyces, Ingoldiomyces, Neovossia, Oberwinkleria, Rhamphospora, Tilletia). In all these types, the teliospore initials first develop a hyaline sheath under which the ornamentation, the exosporium, sometimes a middle layer, and the endosporium are successively deposited by the fungal cell. In the Entorrhiza type, the teliospores develop inside vital host cells with the wall of the sporogenous hypha included into the teliospore wall. The fungus develops a middle layer and an electron-transparent endosporium inside the hyphal wall while a layer forming the ornamentation is deposited onto the hyphal wall, probably by vesicles of dictyosomes of the host cell.Part 164 in the series Studies in Heterobasidiomycetes from the Botanical Institute, University of Tübingen