缢基蜈蚣藻的修订——基于形态观察、早期发育及分子序列分析

通过形态结构和早期发育过程的观察,结合分子分析,对采自青岛(模式标本产地)的缢基蜈蚣藻(Grateloupia constricata Li et Ding)进行了重新鉴定。结果表明:(1)藻体直立,单生或丛生,呈红褐色或紫红色,质地黏滑,软骨质,高10—30 cm,主枝扁平; 1—3回羽状分枝,小枝对生、互生或偏生,基部缢缩;藻体由皮层及髓部构成,皮层由7—10层细胞组成,厚80—120μm,髓部由不规则排列的髓丝组成,雌配子体的果胞枝生殖枝丛主枝和辅助细胞生殖枝丛主枝分别由6个和5个细胞构成,为典型的Grateloupia(6cpb—5auxb)型;四分孢子囊经十字分裂形成。上述特征均与亚洲蜈蚣藻(G. asiatica Kawaguchi et Wang)一致。(2)缢基蜈蚣藻孢子的早期发育类型为"间接盘状体"型,其早期发育过程与亚洲蜈蚣藻一致。(3)基于rbcL基因序列构建的系统树显示, 8个缢基蜈蚣藻样本之间无碱基差异,与青岛和大连的亚洲蜈蚣藻均无碱基差异,形成独立的进化支,与韩国和日本的亚洲蜈蚣藻碱基差异分别为2 bp(0.17%)和3 bp(0.25%),均属于种内差异;...     

THE BIOLOGY OF HARVEYELLA MIRABILIS (CRYPTONEMIALES; RHODOPHYCEAE). V. HOST RESPONSES FO PARASITE INFECTION1,2

The thallus of Harveyella mirabilis (Reinsch) Schmitz & Reinke is composed of vegetative rhizoidal cells growing intrusively between adjacent cells of the red algal hosts (Odonthalia and Rhodomela) and a protruding reproductive pustule. Although primarily composed of Harveyella cells, host medullary and cortical cells also occur in the emergent pustule. In both tissue regions, Harveyella cells are connected to host cells by secondary pit connections initiated by the host. Direct penetration of host cells by rhizoidal cells of Harveyella occasionally occurs, resulting in host cell death. Degeneration of host medullary cells beneath the pustule may result in a hollow branch and the cortical cells undergo cell division forming a thick palisade layer of randomly associated, photo-synthetically active cells. It is within these branches that the parasite overwinters vegetatively. Host medullary and cortical cells dispersed in the emergent pustule show few of the degenerative responses noted in host cells adjacent to parasite rhizoidal cells. Rather, host cell division, chloroplast division and photosynthetic assimilation of H¹⁴CO^?₃ all increase. Spherical virus-like solitary bodies (S-bodies) occur in all Harveyella cells and in all host cells attached to Harveyella by secondary pit connections. The possibility that these structures may induce the infective response in the host is discussed.     

MORPHOLOGY OF THE SUBANTARCTIC RED ALGA CENACRUM SUBSUTUM GEN. ET SP. NOV. (RHODYMENIALES) FROM MACQUARIE ISLAND1

The red alga Cenacrum subsutum gen. et sp. nov. is described from material collected at Macquarie Island in the subantarctic between November 1977 and February 1978. The habit and carposporophyte development are similar to members of the family Rhodymeniaceae (Rhodymeniales), but certain vegetative features are unique. The frond is a variously incised or lobed foliose blade with hollow apices above and a medulla which becomes progressively filled basipetally with ingrowing rhizoidal filaments. Details of carpogonial branch, auxiliary cell, connecting cell and gonimoblast anatomy are given, as well as observations on the habitats and distribution of the species.     

Zur Entwicklung und funktionellen Anatomie des Phylloids vonLaminaria hyperborea

The persistent thallus of the phaeophyceanLaminaria hyperborea produces annually a new phylloid, formed by a meristematic zone between stipe and old phylloid. The growing frond is nourished with assimilates from the old one. Young and old phylloid are linked by a collar. Frond and stipe are of very similar anatomical structure. The frond is coated by a one-layer-meristoderm, which forms the external cortex. Using the position of slime ducts as border, the parenchymatous cortex can be subdivided into outer and inner cortex. Between inner cortex and medulla numerous transitions exist. The medulla itself is mainly composed of longitudinally arranged trumpet cells and hyphae. Frond enlargement is caused by the activity of both meristoderm and cortex. Not only cell divisions but also elongation in medulla and inner cortex contribute to growth of the frond. The frond diameter is decreased by this elongation process. Corresponding stretching occurs in the network of slime ducts. Swelling of longitudinal primary walls, accompanied by incorporation of alginate, facilitates the separation of cell strands, and across the medulla hyphae and crosslinks of both inner-cortex-layer cells form. Cells of the inner cortex continously differentiate to elements of the medulla. Trumpet cells within the outer part of the medulla are often branched and connected by hyphae to parenchymatous cells of the inner cortex. Toward the central part of the medulla, trumpet cells elongate and finally attain a length of 1000 µm; they form thick secondary longitudinal walls with ringshaped thickenings, reducing the lumen diameter. Crosswalls and whole cells are often plugged with callose and have, apparently, ceased to translocate.     

Development of the siphonous green alga Penicillus and the Espera state*

The thallus of Penicillus is composed of two filament types: axial filaments of indeterminate growth and laterals of determinate growth. In vegetative reproduction new plants arise from horizontal rhizoids. Four stages can be distinguished in development. In the primordium stage the tip of a rhizoid swells and forms a primordium. In the germling stage ascending and descending axial filaments arise from the primordium, the former grow into a fascicle and give rise to lateral saccate branches, each of which forms an ascending and a descending arm and branches further into rhizoid-like branchlets. Together these structures constitute the foundation of the stipe. At the same time the descending axial filaments elongate and become main rhizoidal filaments with lateral rhizoidal branchlets. In the early juvenile stage the stipe is formed. The elongating ascending axial filaments form a medulla while their laterals produce a cortex. In the late juvenile stage the axial filaments form the capitulum. The Espera state of Penicillus lacks a stipe since the ascending axial filaments do not join in a fascicle. Espera has been grown in laboratory cultures from Penicillus plants collected in the Caribbean region and also been found uncommonly in nature in this area. This state may be a response to environmental stress. The flattening of thalli and their orientation perpendicular to the direction of waves are discussed. A comparison of Penicillus and Codium indicates that at least two types of development exist in multiaxial Eusiphoniidae.     

Morphology and life history of four Japanese species of Elachista (Elachistaceae, Phaeophyceae), including a new record of E. fucicola

Elachista fucicola (Velley) Areschoug (Elachistaceae, Phaeophyceae) is newly recorded from Japan, and compared with three previously described species, Elachista coccophorae Takamatsu, Elachista mollis Takamatsu and Elachista okamurae Yoshida. All species showed direct‐type life histories in culture without sexual fusion. Prostrate filaments of E. fucicola formed globular plurilocular zoidangia similar to those reported from Atlantic isolates of this species. However, these were different from uniseriate plurilocular zoidangia of the three Japanese species. Furthermore, the position of a meristematic region in assimilatory filaments and the morphology of paraphyses can easily distinguish these from E. fucicola. Previously emphasized differences in cell length : width ratios in assimilatory filaments showed only slight differences. Elachista coccophorae is characterized by thick‐walled assimilatory filaments and curved paraphyses, and the absence of downwardly growing rhizoidal filaments. Elachista mollis and E. okamurae are very similar. However, germlings from plurizoids formed on erect filaments of E. mollis showed characteristic pseudodiscoid growth in culture. Halothrix coccophorae Ohta and Elachista zosterae Noda are reduced to synonyms of E. coccophorae and E. mollis, respectively.     

Morphogenesis in the red alga,Griffithsia pacifica: Regeneration from single cells

Summary The regeneration of plants of the red alga Griffithsia pacifica from single, isolated cells is described. Regeneration can start from any cell and is triggered by the removal of an abutting cell. An isolated, single shoot cell forms a shoot and a rhizoidal cell within one day. The shoot then adds new cells by apical division at the rate of 1–2 cells/day; branches are formed at predictable but not fixed locations by budding of subapical cells. Each shoot cell enlarges for 6–8 days. The resulting plant consists of uniseriate, pseudodichotomously-branched shoot filaments with multicellular rhizoidal filaments at their base. The predictability and rapidity of this development combined with the large size of these cells (1.0×0.2 mm) facilitate developmental studies on this organism.     

Recent developments in the systematics of the Gigartinaceae (Gigartinales, Rhodophyta) based on rbcL sequence analysis and morphological evidence

The phylogenetic systematics of the Gigartinaceae is discussed for seven genera and three undescribed generic lineages and 65 taxa representing 62 species based on an analysis of rbcL sequences and morphological evidence. An examination of rbcL trees resulting from analyses of these taxa identifies seven lineages: (i) ‘Gigartina’ alveata; (ii) Rhodoglossum/Gigartina; (iii) Chondracanthus; (iv) Ostiophyllum; (v) Sarcothalia; (vi) ‘Gigartina’ skottsbergii; and (vii) a large clade containing Iridaea/‘Sarcothalia’, Mazzaella and Chondrus. These lineages and Chondrus are strongly supported; however, two groups, Iridaea/‘Sarcothalia’ and Mazzaella, receive no bootstrap support. The morphology of the female reproductive system is investigated with the aid of computer-generated, color-coded tracings of photographs of cystocarps seen in cross section at different developmental stages. Seven basic cystocarp types were found which corresponded to species groups seen in rbcL trees. These were: (i) a ‘Gigartina’ alveata group in which the carposporangia-bearing filaments develop apomictically from gametophytic cells; (ii) a Rhodoglossum/Gigartina group in which gonimoblast filaments penetrate the surrounding envelope fusing progessively with envelope cells; (iii) a Chondracanthus group in which gonimoblast filaments penetrate the envelope but fuse with envelope cells only at late developmental stages; (iv) a Sarcothalia group in which the gonimoblast filaments displace an envelope composed mainly of secondary gametophytic filaments and link to envelope cells by terminal tubular gonimoblast cells; (v) an Iridaea group similar to the Sarcothalia group, but with an envelope composed of a mixture of medullary cells and secondary gametophytic filaments; (vi) a Mazzaella group that lacks a true envelope and in which gonimoblast filaments connect to modified gametophytic cells by means of terminal tubular cells; (vii) a Chondrus group in which gonimoblast filaments penetrate the medulla and link to modified medullary cells by means of conjunctor cells forming secondary pit connections. The further separation of these groups into genera is based largely on tetrasporangial characters.     

DEVELOPMENT OF THE CARPOSPOROPHYTE OF KALLYMENIA RENIFORMIS (TURNER) J. AGARDH1

The development of the carposporophyte in Kallymenia reniformis involves an elaborate series of interactions between reproductive and vegetative tissues. Following fertilization, the inner cells of the carpogonial branches form processes that unite with the supporting cell and with each other, giving rise to a large fusion cell. A number of medullary filaments are enveloped and incorporated within the developing fusion cell. Secondary filaments may be produced from medullary cells outside the fusion cell after connecting filaments have been initiated. Connecting filaments are nonseptale and wind their way through the medulla. The presence of a connecting filament in the vicinity of an auxiliary cell appears to initiate a complex sequence of responses. Vegetative filaments are produced in the medulla and inner cortex that grow centripetally toward the auxiliary cell and fuse with one another, forming a network of secondary tissue. One of the vegetative cells may penetrate the auxiliary cell, while others intrude into subsidiary cells connecting them with the network. An ostiolate pericarp is initiated in the cortex above the auxiliary cell. The connecting filament fuses with the auxiliary cell and also with some of the surrounding vegetative cells, forming an irregular lobed structure. Gonimoblast is initiated in scattered pockets from vegetative cells in the vicinity of the auxiliary cell apparatus.     

Responses of medullary neurons to moving visual stimuli in the common toad

Summary Intracellular recording and labeling of cells from the toad's (Bufo bufo spinosus) medulla oblongata in response to moving visual (and tactual) stimuli yield the following results. (i) Various response types characterized by extracellular recording in medullary neurons were also identified intracellularly and thus assigned to properties of medullary cell somata. (ii) Focussing on monocular small-field and cyclic bursting properties, somata of such neurons were recorded most frequently in the medial reticular formation and in the branchiomotor column but less often in the lateral reticular formation. (iii) Visual object disrimination established in pretectal/tectal networks is increased in its acuity in 4 types of medullary small-field neurons. The excitatory and inhibitory inputs to these neurons evoked by moving visual objects suggest special convergence likely to increase the filter properties. (iv) Releasing conditions, temporal pattern, and refractoriness of cyclic bursting neurons resemble membrane characteristics of vertebrate and invertebrate neurons known to play a role in premotor/motor activity. (v) Integrating functions of medullary cells have an anatomical correlate in the extensive arborizations of their dendritic trees; 5 morphological types of medullary neurons have been distinguished.Abbreviations A stripe moving in antiworm configuration - (W) moving in worm configuration - S square - BMC branchiomotor column - EPSP excitatory postsynaptic potential - IPSP inhibitory postsynaptic potential - RetF medullary reticular formation - RF receptive field - M neurons response properties of medullary neurons - T neurons classes of tectal neurons - TH neurons classes of thalamic/pretectal neurons - tr.tb.d. tractus tecto-bulbaris directus - tr.tbs.c. tractus tecto-bulbaris et spinalis cruciatus     

Studies on four new species of the malacocarpic Sargassum (Sargassaceae, Heterokontophyta) in China

In this paper, four new species of malacocarpic Sargassum are described: S. fuliginosoidesTseng et Lu sp. nov. is characterized by its discoid holdfast, the presence of the bulbs on the basal parts of the primary branches and very thick, lanceolate leaves. S. gemmiphorum Tseng et Lu sp. nov. is characterized by its conical holdfast, usually branched axis and very long, narrow, thin, denticulate leaves. S. shandongense Tseng, Zhang et Lu sp. nov. is characterized by its discoid holdfast, flattened primary branches, its leaves mostly entire or wavy at the margins and its racemose to paniculate receptacles. S. qingdaoense Tseng et Lu sp. nov. is characterized by the presence of the glandular dots on the ultimate branches and elongated lanceolate, acute, mostly wavy leaves.     

MORPHOLOGY AND TAXONOMY OF MERISTIELLA GEN. NOV. (SOLIERIACEAE,RHODOPHYTA) 1

Eucheuma acanthocladum (Harvey) J. Agardh, E. gelidium (J Agardh) J. Agardh, E. echinocarpum Areschoug and E. schrammii(P. et H. Crouan) J. Agardh from the tropical and warm temperate waters of the western Atlantic Ocean and Caribbean Sea are transferred to a new genus, Meristiella. Meristiella exhibits the following Unique combination of characters among genera in the Solieriaceae: (1) rotated periaxial cells, (2) a loosely filamentous medulla. (3) an auxiliary cell complex, (4) Single and twin connecting filaments and (5) spinose cystocarps composed of a central, small-celled placentum, based on its reproductive features, Meristiella. is assigned to the tribe Agardhielleae. Culture experiments and herbarium studies provide evidence that E, gelidium and E. acantghocladum are conspecific. Lectotypes are designated for the included species.     

A critical survey of the evidence for the occurrence of Helminthocladia agardhiana Dixon [H. hudsoni J. Ag. pro parte] in Europe

An examination of cystocarps from the rarely collected southern Australian alga currently known as Lomentaria corynephora (J. Agardh) Kylin has shown it to be a member of the Rhodymeniales but incorrectly placed in Lomentaria. As it is not referable to any of the genera presently ascribed to the order, the new genus Semnocarpa is proposed to accommodate its suite of unique features. Semnocarpa closely resembles Lomentaria in habit and in having basally septate branches, a peripheral network of widely separated medullary filaments around the cell-free (but mucilage-filled) centres of the main and lateral axes, gland cells directed inwardly on scattered medullary cells, and tetrasporangia produced laterally from surface cortical cells that line deep cavities in the branch surfaces. Features of the mature cystocarp, however, strongly differentiate Semnocarpa from Lomentaria. The carposporophyte has a fusion cell in which outlines of the component cells remain discernible, as opposed to having a fully consolidated fusion cell, and is laxly enclosed in a system of filaments derived from surrounding inner cortical cells. The cystocarp is entirely submerged within the bearing branch, there being no protuberant pericarp derived from the outer cortex of the sort previously thought to be a uniform feature of the family Lomentariaceae and virtually all Rhodymeniales. These features suggest that Semnocarpa is likely to be a highly derived member of the Lomentariaceae. A second species is newly described from material collected in Western Australia. Semnocarpa minuta sp. nov. differs from S. corynephora in its exclusively epiphytic habit, two-layered medulla, smaller stature and extensive crustose holdfast.     

Sahlingia nov. gen. based on Erythrocladia subintegra (Erythropelfidales,Rhodophyta)

Because of significant differences in their morphologies and growth patterns Erythrocladia irregularis and E. subintegra cannot be considered congeneric. The frond of E. irregularis consists of branched filaments with free ends, whereas the thallus of E. subintegra represents an orbicular disc with marginal growth. Therefore a new genus, Sahlingia, is created to include E. subintegra.     

THE MICROFIBRILLAR STRUCTURE OF THE CELL WALLS OF THE FILAMENTOUS FUNGUS, Allomyces

Cell walls of the fungus, Allomyces, were isolated by chemical procedures, using either potassium permanganate oxidation or glacial acetic acid-hydrogen peroxide treatment followed by dilute mineral acid. The structure of the treated walls was investigated by means of electron microscopy and electron diffraction analysis which showed that rhizoidal walls were especially suitable for observation. Chitin microfibrils exist in the extreme tips of rhizoidal walls, and tend to lie in a preferred longitudinal orientation. Older rhizoidal wall segments show a crossed fibrillar structure under a thin layer of short randomly arranged microfibrils. In the possession of systems of crossed fibrils these walls are like the cell walls of certain green algae. Walls of branch rhizoidal filaments were observed in the early stages of development, in which case the observed microfibrillar orientations are such that it is possible to envisage their origin from pre-existing fibrils that have passively reoriented. With respect to the continued growth of the filaments, however, it is difficult to explain the observed microfibrillar arrangements in terms of the "multi-net" theory. Hyphal walls usually show two layers, the outer consisting of microfibrils arranged randomly, and the inner consisting of well oriented microfibrils running parallel with the longitudinal axis of the hypha. The oriented inner layer appears to be similar in structure to the secondary wall of the Phycomyces sporangiophore.     

Comparative morphology and systematics of Chondrymenia lobata from the Mediterranean Sea and a phylogeny of the Chondrymeniaceae fam. nov. (Rhodophyta) based on rbcL sequence analyses

The Chondrymeniaceae Rodríguez-Prieto, G. Sartoni, S.-M. Lin & Hommersand, fam. nov., is proposed for Chondrymenia lobata. Analyses of rbcL sequences place the new family in a large gigartinalean assemblage that comprises the Cystocloniaceae–Solieriaceae complex. Plants are decumbent and growth takes place by division of multiple apical cells at the margin of the blade. Thalli consist of an outer cortex of subspherical to elongate cortical cells arranged in anticlinal rows, a subcortex of cells cross-linked by lateral arms, and a large central medulla composed of primary medullary filaments intermixed with numerous rhizoidal filaments. Male stages are reported in monoecious individuals. Inactive carpogonial branches consist of a two-celled filament that is directed inwards from the supporting cell. Functional carpogonial branches are oriented outwardly, with the carpogonia and trichogynes pointed towards the thallus surface. After presumed fertilization, the carpogonium fuses with the hypogynous cell and transfers the zygote nucleus. The hypogynous cell, in turn, fuses with the supporting cell which contains many haploid nuclei. The resulting fusion cell functions as an auxiliary cell that cuts off a single gonimoblast initial, which produces the gonimoblast filaments. Gametophytic cells close to the auxiliary cell unite with it to form a placental fusion network of variable size and outline, and a placental fusion cell. Proximal gonimoblast cells fuse with the placental fusion cell, while the distal cells differentiate into branched chains of subspherical carposporangia. The superficial similarity of the outwardly developed osteolate cystocarp is responsible for Kylin's (1956) placement of Chondrymenia in his family Sarcodiaceae; however, the manner in which the placenta is formed is more like that seen in the Cystocloniaceae–Solieriaceae complex.     

中华白花丹参与其近缘种的形态分类鉴定

该研究采用光学显微镜和扫描电镜相结合的方法,对中华白花丹参(Salvia sinealba)与其近缘种丹参(S.miltiorrhiza)及山东丹参(S.shandongensis)根的解剖学、叶表皮、花及花粉粒进行了系统地比较研究。结果表明:中华白花丹参(S.sinealba)根的中央部位有多数薄壁细胞,在根横切面射线薄壁细胞间及韧皮部外侧与次生皮层部位有多数裂隙;叶片上表皮细胞外平周壁具有细密平行丝状褶皱(SEM);花冠白色;花粉粒椭圆形,外壁具网状雕纹,网眼较大,多角形,少为单穿孔。上述这些显著的特征,不仅为中华白花丹参在植物分类学上的地位提供了形态解剖学依据,而且为近缘种丹参及山东丹参的分类鉴定提供了佐证,同时也为中华白花丹参这一特有新资源的保护和开发利用提供了资料。     

Requirement of Stat3 Signaling in the Postnatal Development of Thymic Medullary Epithelial Cells

Thymic medullary regions are formed in neonatal mice as islet-like structures, which increase in size over time and eventually fuse a few weeks after birth into a continuous structure. The development of medullary thymic epithelial cells (TEC) is dependent on NF-κB associated signaling though other signaling pathways may contribute. Here, we demonstrate that Stat3-mediated signals determine medullary TEC cellularity, architectural organization and hence the size of the medulla. Deleting Stat3 expression selectively in thymic epithelia precludes the postnatal enlargement of the medulla retaining a neonatal architecture of small separate medullary islets. In contrast, loss of Stat3 expression in cortical TEC neither affects the cellularity or organization of the epithelia. Activation of Stat3 is mainly positioned downstream of EGF-R as its ablation in TEC phenocopies the loss of Stat3 expression in these cells. These results indicate that Stat3 meditated signal via EGF-R is required for the postnatal development of thymic medullary regions.     

Fertile and sterile frond segments of the lyginopterid seed fern Feraxotheca

Fertile and sterile frond segments of the lyginopterid seed fern Feraxotheca culcitaus are described. In both the fertile and sterile specimen three orders of frond axes are borne alternately and in the same plane. Antepenultimate and penultimate frond axes are characterized by a C-shaped vascular bundle and numerous canals containing a golden-colored material in the fossilized condition. Synangia with only four sporangia demonstrate radial symmetry; bilateral symmetry is present in larger synangia. Pinnules possess dichotomous venation, with a single vein entering each lobe of the deeply incised lamina. A single canal occurs below each vein, and vein ends have an amplified vascular bundle. Morphologically Feraxotheca compares most closely with the compression genus Crossotheca. The morphology of the vascular bundle in the largest pinna is similar to a Lower Carboniferous specimen of Rhodea.     

Atypical development of Chaetomorpha antennina in culture (Cladophorales,Chlorophyta)

The green seaweed genus Chaetomorpha is characterized by unbranched filaments. Molecular phylogenetic data indicate that Chaetomorpha forms a clade that is nested in a paraphyletic assemblage of branched species (Cladophora). It follows that the unbranched condition is evolutionarily conserved and likely evolved early in the evolution of this clade. In this study we show that under laboratory culture conditions, the filaments of C. antennina frequently produce lateral branches, similar to Cladophora. Our results thus indicate that the unbranched thallus architecture is not entirely genetically constrained, but at least in part subject to morphological plasticity. Additionally, culture observations of C. antennina allowed a detailed study of rhizoidal development, which seems unique among Cladophorales.