The Acoustic Detection of Cavitation in Fern Sporangia

Cavitation of water in the annular cells of fern sporangia wasmonitored simultaneously by acoustic detection and visual analysisusing a light microscope. The number of cavitable annular cells was found to be 21.3 ±1.7 (n=40). The number and timing of ultrasonic acoustic emissions(UAE) received from a fully hydrated sporangium allowed to dehydrateon the acoustic probe closely approximated the average numberof cavitable annular cells. The number and timing of audibleacoustic emissions (AAE) was found to be lower than the numberof UAE. AAE were associated with cavitation-induced forwardmovements of the sporangium rather than individual cavitationevents within each annular cell. The results are discussed in view of an hypothesis proposedby Ritman and Milburn (1988) which describes the relationshipbetween the frequency of acoustic emission and the size of theresonating element. Key words: Cavitation, acoustic detection, sporangia     

Davallia (Polypodiales: Davalliaceae) macrofossils from Early Miocene Otago (New Zealand) with in situ spores

Fossil fern fronds referable to the extant fern genus Davallia (Polypodiales: Davalliaceae) bearing sporangia with in situ spores are described from the Early Miocene Foulden Maar diatomite deposit, Otago, New Zealand. The fronds are the first published Southern Hemisphere macrofossil record for the family and provide valuable palaeoclimate data supporting warm conditions in Early Miocene New Zealand. The matching of Davallia fronds to the form spore taxon Polypodiisporites radiatus shows that the genus has had a long, apparently continuous history throughout late Cenozoic New Zealand.     

Secondary Sporangium Formation in Phytophthora Palmivora (Butl.) Butl

Very few sporangia of Phytophthora palmivora germinated directlyand produced secondary sporangia in distilled water and in solutionsof amino acids and carbohydrates at 30 °C. Although 1.0per cent (w / v) peptone and yeast-extract stimulated a highpercentage of germination by formation of germ tubes, less than1.0 per cent of the germinated sporangia produced secondarysporangia. Secondary sporangium formation was induced by transferringgerminated primary sporangia from a nutrient medium of sufficientlyhigh concentration to either distilled water or dilute solutionsof organic and inorganic compounds immediately after emergenceof the germ tubes. The percentage of germinated sporangia formingsecondary sporangia was influenced by both the nature and concentrationof the medium into which they were transferred. The secondarysporangia were significantly smaller than the primary sporangia. Phytophthora palmivora, germination, sporangium, Theobroma cacao L., cocoa     

Plastid Replication in Vegetative Cells, Sporangia, Spores and Sporelings of Red Algae

Ultrastructural aspects of proplastid and chloroplast replicationare described as seen in sections of vegetative cells, sporangia,released spores and sporelings of the red algae Palmaria palmataand Plumaria elegans. Proplastids in apical vegetative cellsshow internal thylakoid formation from peripheral thylakoidsin both species, and proplastid formation by budding from maturechloroplasts has also been observed. Proplastid replicationby fission has been occasionally observed, and genophore divisionin the stroma of proplastids. In vegetative cells, sporangia,spores and sporelings chloroplast formation from mature plastidscan take place by elongation and fission, or by formation ofa discrete group of thylakoids which become pinched off fromthe parent chloroplast, and by irregular expansions of the parentchloroplasts with subsequent multiple fission. Plastid replication, vegetative cells, sporangia, spores, red algae     

VALLITHECA VALENTIA GEN. ET SP. NOV., PERMINERALIZED SYNANGIA FROM THE MIDDLE PENNSYLVANIAN OF OKLAHOMA

Vallitheca valentia gen. et sp. nov. is a permineralized, synangiate fructification of probable seed fern affinities from the Wewoka Formation (Desmoinesian) near Ada, Oklahoma. Synangia are oblong to pyriform, average 1 cm long, and contain 32 to 48 tubular sporangia embedded proximally in ground tissue. The sporangia are arranged within the synangia in a unique pattern: a ring of peripheral sporangia dehisces toward the center of the synangium and a central group of sporangia dehisces outward. This unique arrangement is unlike that of any currently recognized group.     

On separation and identity of fern antheridiogens

Chromatographic studies show that the hormones controlling antheridiuminduction in the fern species Pteridium aquilinum (Polypodiaceae),Anemia phyllitidis and Lygodium japonicum (Schizaeaceae) aredifferent molecular entities. SCHRAUDOLF's report that gibberellic acid induces antheridiain A. phyllitidis and L. japonicum was confirmed. The activityspectrum of GAs towards species of different fern families stronglyresembles that of the native Anemia antheridiogen. However,the native antheridiogens of A. phyllitidis, and of Lygodiumjaponicum, are more species-selective in their action than isGA₃. Preliminary studies have yielded no conclusive evidenceon whether the native antheridiogens are gibberellins. (Received August 21, 1967; )     

蕨类植物孢子囊形态 I. 鳞始蕨科

孢子囊是蕨类植物的繁殖器官, 其形态在蕨类植物的分类和系统发育研究上具有重要意义。用次氯酸钠溶液处理新鲜成熟的孢子囊, 在光学显微镜下获得清晰的孢子囊图像, 系统研究了中国鳞始蕨科4属13种孢子囊的形态特征。结果表明, 鳞始蕨科孢子囊呈椭球形, 孢子囊柄由3列细胞构成, 环带类型为垂直环带。通过分析孢子囊形态数据探讨了中国鳞始蕨科属内及属间差异。结果表明, 乌蕨属(Odontosoria)、香鳞始蕨属(Osmolindsaea)、达边蕨属(Tapeinidium)和鳞始蕨属(Lindsaea)的孢子囊环带细胞数依次减少, 囊蒴体积、唇细胞数和囊壁细胞数的变化由大(多)到小(少)依次为乌蕨属、达边蕨属、香鳞始蕨属和鳞始蕨属。孢子囊属内差异最大的是阔片乌蕨(Odontosoria biflora)与乌蕨(O. chinensis)以及香鳞始蕨(Osmolindsaea odorata)与日本鳞始蕨(O. japonica); 而达边蕨属和鳞始蕨属的属内差异则很小。研究结果为揭示鳞始蕨科系统发育关系提供了形态基础, 特别是提出阔片乌蕨和乌蕨以及香鳞始蕨和日本鳞始蕨在孢子囊形态上的差异值得进一步研究。     

Alteration of the Cell Surface during the Vegetative Cell Cycle of the Unicellular Green Alga Chlamydomonas reinhardtii

Alterations of the cell surface during the vegetative cell cycleof the unicellular green alga Chlamydomonas reinhardtii wereinvestigated using polyclonal antibodies against the purifiedand subsequently deglycosylated insoluble cell wall componentand against a 100 kDa polypeptide of the deglycosylated, chaotrope-solublewall fraction, respectively. Both antibodies recognized epitopeswithin the non-glycosylated domains of a ‘150 kDa’chaotrope-soluble glycoprotein (=GP3B) localized in the outerlayers of the C. reinhardtii cell wall. Immunofluorescence studiesindicated that both antibodies reacted with the surface of ‘late’sporangia (harvested 1 h before liberation of the zoospores),but not with the cell surfaces of released zoospores, growingcells and young sporangia, respectively. After pretreatmentwith aqueous LiCl, however, the cell surfaces of zoospores,growing cells and young sporangia became accessible to theseparticular antibodies. Highly purified preparations of the insolublewall fraction revealed strong immunofluorescence with both antibodiesbut not with the corresponding preimmune sera. Based on thesedata, we concluded that the antigenic sites of the insolubleglycoprotein framework of the C. reinhardtii wall are maskedby LiCl-soluble glycoproteins in single cell stages and youngsporangia, but not or to a lesser extent in the case of themother walls of ‘late’ sporangia. The conclusionwas supported by findings that (I) the multilayered structureof the mother-cell wall was disturbed in ‘late’,but not in young sporangia and that (II) the amounts of chaotropesolublecell wall glycoproteins present in the LiCl-extracts from intactsporangia decreased during ripening of the sporangia. (Received January 10, 1996; Accepted May 27, 1996)     

Changes in the Level of the Protein Nitrogen during Growth of the Gametophyte and the Initiation of the Sporophyte of Dryopteris borreri Newm.

Estimations of the amounts of organic nitrogen in spores anddeveloping gametophytes of Dryopteris borreri, a fern reproducingapogamously and lacking archegonia, have shown that the nitrogenin the gametophytes increases exponentially. The logarithmicrate of increase of the nitrogen remains unchanged during theinitiation and emergence of the sporophyte. Gametophytes aboutto produce sporophytes yielded only filamentous growths whentransferred to a medium containing 8-azaguanine, and the increasein their content of organic nitrogen was very small. The resultsare discussed in relation to similar estimations made by otherworkers upon the gametophytes of Dryopteris erythosora(Eat.)Schott, a fern reproducing sexually. The interpretation placedupon the results obtained for D. erytkrosora is questioned,and a new interpretation of these results, together with thosefor D. borreri, is related to the difference in morphology ofthe two generations in the life cycle of the Polypodiaceousferns.     

Fertile organs and in situ spores of a new dipteridaceous fern Hausmannia sinensis from the Jurassic of northern China

As a representative fossil member of the dipteridaceous fern, genus Hausmannia was reported worldwide from the Mesozoic strata; however, little is known about the fertile structures, including sporangia and in situ spores, of this genus. In this study, a new species Hausmannia sinensis was identified from the Middle Jurassic of Nei Mongol (Inner Mongolia), northern China. The specimens are compressions and are well preserved with details of sporangia and in situ spores. The leaf laminae are broadly fan-shaped, with an almost entire margin. Primary and lateral veins dichotomously branch to form square or polygonal meshes. Each ultimate mesh bears one to two circular sori of 0.4 mm in diameter. Sori are exindusiate; each sorus contains three to six round to ovoid sporangia. The annulus is developed and oblique, with stomial region present in proximal position. Spores are trilete, circular to oval in shape. Both proximal and distal surfaces are covered with baculate to subverrucate sculptures. Spores range from 20 to 30 μm in diameter (average 28 μm), and are comparable to the dispersed genera Baculatisporites Thomas and Pflug and Apiculatisporis Potonié and Kremp. Hausmannia sinensis represents the first compression species of genus Hausmannia form Eurasia, which shows the combination of well-preserved sori, sporangia, annuli and in situ spore characters, and is therefore helpful for further understanding the diversity and evolution of the Dipteridaceae fern lineage through time.     

Further Observations on the Coenopterid Fern Genus, Rhabdoxylon

Two reconstructed specimens of Rhabdoxylon dichotomum are describedfrom Westphalian A coal balls from England and Belgium. Stemsdichotomize repeatedly with up to four petioles borne betweendichotomies. Each dichotomy is closely associated with a foliartrace. Petioles are up to 3 cm long. Unattached rachises reach6 cm in length without branching. All foliar members have asmall monarch vascular strand. Roots are diarch and arise fromthe stems in random arrangement. Foliar and cauline tracheidpitting is scalariform to reticulate. The presence of apicalzones in this genus is recorded for the first time. The habitof R. dichotomum differs significantly from that of R. americanum. Rhabdoxylon, coenopterid fern, stem dichotomy, coal balls     

Enhancement of Apospory in Liquid Culture of Matteuccia struthioptens

Apospory in the fern Matteuccia struthiopteris, which is reportedhere for the first time, was induced more readily in liquidculture than on agar medium. It occurred more frequently fromdetached meristems than from juvenile leaves. Gametophytic outgrowthsbearing rhizoids, but lacking sex organs were found occasionallyon roots. Aposporous gametophytes isolated from liquid culturewere induced to form sporophytes either sexually or apogamously.Both types of sporophyte also behaved aposporously in liquidculture. Matteuccia, fern, apospory, apogamy, liquid culture, detached meristem     

Origin of Exogenous Adventitious Roots in Rhizomes of the Fern Microsorium scolopendria (Polypodiaceae)

Adventitious roots of rhizomes of the fern Microsorium scolopendriaarise exogenously from apical initials which have their originin the cell layer directly beneath the epidermis. Divisionsof the apical initial and its derivatives produce the adventitiousroot apical meristem. Cells between the apical cell and themeristele of the rhizome develop into the root trace. Anatomy, light microscopy, Microsorium scolopendria Burm.) Copel     

Leonophyllum tenellum nov. gen., nov. sp., an enigmatic plant from the Early Jurassic of the Mecsek Mts (Hungary)

The Early Jurassic flora of the Mecsek Mountains is diverse, with numerous representatives of ferns, seed ferns, cycadophytes, ginkgophytes, and conifers. Its (para-)autochthonous deposition, good preservation and low collection bias has permitted researchers to save delicate, small plant remains that would generally be missing from the fossil record. These plant fossils are characterized by having a “filmy” (probably unilayered) structure, thin stalks with flat leaf-like branches and ultimate irregular segments with streamlined epidermal cells having thick cell walls. Due to the absence of sporangia, the plant remains cannot be confidently assigned to any higher plant group, although they show some similarities to thalloid liverworts with raised vegetative bodies and also have some resemblance to the fern family Hymenophyllaceae. The new genus and species Leonophyllum tenellum Barbacka et Kustatscher is erected.     

The Spontaneous Formation of Antheridia in Onoclea is not Blocked by Light

Onoclea sensibilis gametophytes were grown from spores on ashedsoil and agar to determine if the spontaneous formation of antheridiacan be blocked by light. Under most conditions, dark-grown gametophytesformed antheridia later than or at the same time as gametophytesgrown in the light. Under no circumstances was there a rapidonset of maleness in the dark. These results contradict thehypothesis that, in Onoclea, antheridiogen is required to inducemaleness because light inhibits the formation of antheridia.In the light, antheridia formed on heart-shaped thalli. In darkness,antheridia formed on filamentous gametophytes. The timing ofonset of maleness was affected by temperature and the presenceof sucrose. The effect of sucrose on the comparison betweenlight and dark treatments depended on both substrate and temperature Onoclea sensibilis, L., sensitive fern, fern gametophytes, sexuality, light-induced block     

Apogamous sporophyte formation in a fernPteris multifida and its characteristics

When spores of the fern,Pteris multifida, were aseptically cultured in the dark, sporophytic plants were apogamously induced. The plants have been subsequently grown in pots until the development of leaves with many sporangia for observations of meiotic characteristics in their sporocytes. The sporophytic plants originated from spores were estimated to be haploid, and the estimation was supported by abnormal meiosis in sporocytes and the absence of mature spores, but some chromosomes (n=58) formed bivalents in the meiotic process.     

The Effects of Centrifugation on Asymmetric Cell Division and Differentiation of Fern Spores

We have investigated the effects of centrifugation on sporepolarity, asymmetric cell division, and rhizoid differentiationin the sensitive fern Onoclea sensibilis L. Centrifugation at10000 g for 30 min produces a random orientation of spores withstratification of the cell contents. After centrifugation atmost early stages of development, the nucleus retains its normalpattern of migration from the centre of the ellipsoidal sporeto the proximal face and then to an end of the spore, withoutregard to the orientation of stratification. This indicatesthat the polarity of the spore is stable to centrifugation.As long as the nucleus migrates to an end of the spore and asymmetriccell division occurs, the small cell differentiates into a rhizoid.The arrangement of large cytoplasmic organelles appears to haveno influence on nuclear migration, asymmetric cell division,or rhizoid differentiation. The only period during developmentwhen centrifugation blocks asymmetric cell division is immediatelypreceding and during mitosis and cytokinesis. Spores centrifugedat this stage do not complete nuclear migration, and symmetriccell division results, with neither cell differentiating intoa rhizoid. The source of the stable polarity of the spore isdiscussed. cell polarity, rhizoid differentiation, centrifugation, Onoclea sensibilis L., sensitive fern, fern spores     

Experimental Studies of Apospory in Ferns

Apospory in Pteridium aquilinum was found to have several novelfeatures, in particular the rapidity of its occurrence. Outgrowthsfrom detached laminae were detected in as little as 3 days.There was no evidence that failure of co-ordination betweencells, senescence of the sporophytic tissue or unfavourableculture conditions effected the initiation of outgrowths asearlier workers have suggested. The response of Thelypterispalustris was notably slower and more in line with earlier reportsof apospory. Marsilea vestita appeared to be incapable of anyform of aposporous behaviour. The only feature common to all occurrences of apospory in leavesof wild-type ferns is the severance of the lamina from the mainbody of the plant. It is proposed that this may deprive thecells of regulatory substances which maintain the activationof sporophytic genes. The results are also considered in relationto the phase changes in homosporous and heterosporous plantsand the behaviour of fern protoplasts in culture. apospory, ferns, Pteridium aquilinum, Marsilea vestita, Thelypteris palustris     

Phytochrome in the Fern, Adiantum capillus-veneris L.: Spectrophotometric Detection in Vivo and Partial Purification

Spectrophotometric studies of fern phytochrome were performedusing dark-grown leaves of Adiantum. The absorbance differencespectrum between the red- and far-red-light irradiated sampleshowed a photoreversible absorbance change in the far-red region,with a maximum located at 728–730 nm. The concentrationof phytochrome was highest at the leaf tips and decreased graduallyalong the leaf axis. As in the case of angiosperm phytochrome,the level of fern phytochrome decreased under continuous whitelight, and the level increased again when deetiolated tissuewas transferred back to the dark. When the fern tissue was exposedto a pulse of red light, the dark reversion of P_FR to P_R tookplace with almost no destruction of P_FR. Phytochrome could beextracted from light-grown young leaves of the fern with a slightlyalkaline, aqueous buffer that contained 1 M NaCl. The differencespectrum of the partially purified phytochrome from fern wassimilar to that of partially degraded phytochrome from angio-sperms.A polyclonal antibody raised against phytochrome from etiolatedrye seedlings immuno-stained (albeit weakly) a 110-kDa polypeptideafter fractionation by SDS-polyacrylamide gel electrophoresisof the preparation of fern phytochrome. The band was very probablyfern phytochrome since it emitted zinc-induced fluorescence. (Received July 12, 1990; Accepted October 5, 1990)     

Phytochrome Regulation of Expression of mRNA Encoding the Major Light-Harvesting Chlorophyll a/b-Binding Proteins of Photosystem II in the Haploid Phase of Adiantum capillus-veneris

Light regulates development in the fern Adiantum capillus-venerisduring both the haploid gametophyte and diploid sporophyte phases.In this study, we have investigated the role of the photoreceptorphytochrome in haploid spore germination and regulation of expressionof mRNA encoding the major light-harvesting polypeptides ofphotosystem II {Lhcb mRNAs). Both of these responses appearto be induced by phytochrome and inhibited by blue light, acting.throughseparate photoreceptor(s). Characteristics of phytochrome actionwere similar for both responses, showing no induction in thevery low fluence range and an ‘escape’ from far-redreversal for 50% of the response by 6 h. Overall, these resultsshow that phytochrome regulates both a morphological and a molecularprocess in haploid fern spores, and that these processes mayshare a common signal transduction pathway. (Received February 4, 1998; Accepted April 8, 1998)