Sur la culture des spores et le développement du thalle de Botryocladia chiajeana (Menegh.) Kylin (Rhodyméniales,Rhodyméniacées)

Abstract

On the culture of spores and the development of the thallus of Botryocladia chiajeana (Menegh.) Kylin (Rhodymeniales, Rhodymeniaceae). - The complete development of Botryocladia chiajeana has been studied in culture. Spore germination and sporeling development is of the discalis mediatus type described by Inoh (1947). The hollow vesiculous branches filled with a mucilage derive from the spacing of the erect filaments which form the stipe. The authors compare this development of the thallus with that described for other Rhodymeniales.     

Glomus claroideum forms an arbuscular mycorrhiza-like symbiosis with the hornwort Anthoceros punctatus

Glomus claroideum (Schenck & Smith emend. Walker & Vestberg) were investigated for ability to form arbuscular mycorrhiza-like symbioses with the hornwort Anthoceros punctatus (L.). Spores were transferred to a cellulose acetate filter on water agar and a small portion of an Anthoceros thallus was placed directly upon the spores. Light-microscope observations 20 days after inoculation revealed branched hyphae growing within the thallus. After 45 days, arbuscules and vesicles were studied by light- and electron-microscopy. After 60 days in water agar culture, the colonised Anthoceros thalli were transferred to a low-nutrient medium agar. Hyphae spread in the agar and newly formed spores were observed 5 weeks after the transfer. After 4 months, about 1000 spores were formed in each Petri dish. This is the first report of an experimentally established arbuscular mycorrhiza-like symbiosis between an identified fungus belonging to the Glomales and a bryophyte. Accepted: 11 January 2000     

Some PreHminary Observations on the Water Reladons of a Mesophytic Moss,Thamnium alopecurum (Hedw.) B. & S.

Abstract

Measurements of lobe elongation of the thalloid liverworts Pallavicinia lyellii and Pellia epiphylla were made on shaded streambanks at Silwood Park using a photographic technique. The average cumulative growth of Pallavicinia over 12 months from 1 August 1989 was 8.7 mm compared to 24.7 mm for Pellia. Monthly growth increments of Pallavicinia were positively correlated with average air temperature and accumulated temperatures (day-degrees) in each period. Growth of Pellia was unrelated to temperature. Neither species showed a correlation of growth with rainfall amounts or numbers of wet days, probably because thallus hydration is governed predominantly by soil wetness. Pallavicinia appears to coexist with the more vigorous Pellia by tolerating drier niches than can be endured by Pellia. Persistence of Pallavicinia at this site may be due to the presence of both sexes and frequent colonization of fresh surfaces by spores.     

Porphyra monospore system (Bangiales, Rhodophyta): A model for the developmental biology of marine plants

We have developed an experimental system of cohort monospores from clonal culture of leafy gametophytes in Porphyra yezoensis Ueda (strain TU-1). This system is quite different from traditional systems for algal protoplast experimentation, which require expensive enzymatic treatment and utilize an ineffective method of preservation. Cohort monospores were obtained by utilizing a mode of asexual reproduction in the culture strain (monospores) and artificial regulation (thallus length, temperature, light, etc.) of monospore release. When the leafy gametophytes that formed monospores were frozen at - 20°C in a cryoprotective solution composed of 5% DMSO and 5% dextran in 100% seawater, about 98% survived for 3 months. When stored at 5°C without cryoprotectants, these leafy gametophytes could be kept without monospore release for 1 week. Maximum monospore yield was about 3000 spores per 100 gametophytes, and germination rate was about 70%, This system will accelerate developmental biology studies in Porphyra.     

Intercellular assimilate translocation in Gracilaria cornea (Gracilariaceae,Rhodophyta)

Assimilate translocation has been identified and characterized in Gracilaria cornea under different conditions. Carbon fixation and translocation were carried out by inserting the base part of the thallus into a bicarbonate labeled solution in seawater and exposing its upper part to the air (open system) or to a non-labeled solution above a rubber septum (closed system). After a pulse-chase treatment in the light, three separate sections of each thallus were extracted by DMF (high moleuclar weight photosynthates) or by ethanol (low molecular weight). The results indicate a high rate of active photosynthate translocation which is directly related to inorganic carbon gradients in the thallus, and probably also to sugar gradients in the thallus. Translocation parameters of Gracilaria cornea are lower than of brown algae, as Gracilaria does not contain specific translocation tissues.     

A new Indian species of Riccia L. with connections to northern Australia

Introduction. During a recent explorative field trip to the Western Ghats a new species of Riccia was discovered with possible links to the northern Australian species, Riccia caroliniana Na-Thalang.

Key Results. Morphological similarities between the new species, R. sahyadrica and R. caroliniana include the ventral positioning of the photosynthetic tissue in the ventral section of the thallus in specialised structures known as ventral lamellae. These form a v-shaped patterning along the ventral surface of the thallus and are unique to these two species. Both species also bear similar spores with differences in the micro-ornamentation. Differences between the two species also extend to sexual condition, whereby R. caroliniana is dioicous and R. sahyadrica is monoicous.

Conclusions. A new species, Riccia sahyadrica Manju & Cargill is described and illustrated and compared to the only other morphologically similar species, R. caroliniana endemic to northern Australia. Both species possess the unique characteristic of bearing ventral photosynthetic tissue in contrast to the dorsal position typically seen in all other Riccia species.     

Sur le développement des spores et la formation du thalle rampant de Kallymenia microphylla J. Ag. (Rhodophyceae,Cryptonemiales)

Abstract

On the spore development and the growth of Kallymenia microphylla J. Ag. (Rhodophyceae, Cryptonemiales) creeping thallus. — The filamentous creeping axis produced by spore grows into a terminal cell and then branches out into a monostratified creeping thallus looking like a disc. This creeping thallus is looking exactly like that of the Rhodocorton haucki (Schiffner) Hamel. Compared to the other species of Kallymenia, we find out that this creeping thallus has cellular fusions as well; they are more frequent and appear quite early here.     

ThePorphyra species of Helgoland (Bangiales,Rhodophyta)

This revision of sevenPorphyra species of Helgoland was based on a study of the structure of their fertile thalli and the behaviour of their spores. Regarding the reproductive organization the species may be arranged in two groups.P. leucosticta andP. purpureo-violacea are obligate monoecious species. Asexual thalli have never been observed in the field. The other five species are generally dioecious. Isomorphic sexual thalli and asexually propagating ones are mixed in uniform populations. Carpospores originating from sexual fusion develop into the diploid Conchocelis phase. Sporangia of asexual plants, though homologous in formation, produce spores of different kinds: aplanospores that give rise to the vegetative thallus directly (inP. umbilicalis, P. insolita n. sp. andP. ochotensis) and spores that develop into haploid Conchocelis (inP. laciniata and inP. linearis). P. laciniata — formerly considered synonymous withP. purpurea — is an independent species. “In an investigation into the life-history of an alga the aim should be to obtain a series of observations of the development of the thallus from the germinating spore and then of the development of the reproductive organs on the mature thallus. In cases where both sexual and asexual spores are formed the germination of both types of spore should be followed, ...” (Drew, 1954, p. 184)     

A review of the life history,reproduction and phenology of Gracilaria

The basic life history of the red alga Gracilaria is of the three-phase Polysiphonia type but a number of species show deviations. Plants can bear both gametangia and tetrasporangia, either on separate parts of the thallus or on the same. Explanations include the in situ germination of tetraspores (allowing gametophytic thalli to be epiphytic on tetrasporophytes), the coalescence of spores or developing discs (resulting in chimaeras), mitotic recombination during cell division in the mature diploid thallus (resulting in patches of diploid male and female cells on the tetrasporophyte), a mutation eliminating the repression of female expression allowing haploid male plants to be bisexual and initial failure of cell walls to form during the development of tetraspores. Polyploids can be produced from plants with diploid gametangia. The sexes and phases are usually morphologically identical but gametophytes or their parts may be smaller. The growth rates of the sexes may differ and diploid juveniles may survive better than haploid. Neither polyploidy nor hybridization results in superior growth. The sex ratio is probably 1:1 but females may appear to be more abundant. Diploid and haploid phases are usually either about equal or diploids predominate, often depending on the type of substratum. At high latitudes reproduction peaks in late summer whereas in the tropics it may be high all year. In temperate regions growth rate is fastest and biomass highest in late summer; in the tropics peak biomass is mainly in the winter. Spermatia are effective for only a few h. Spores vary in size around 25 \m, diploid ones usually being larger. Cystocarps or tetrasporangia in the field may not currently be releasing spores. In the laboratory spore release shows a diurnal rhythm, peaking during the night or day according to the species. All the above attributes are potentially important in planning and executing Gracilaria cultivation.     

OBSERVATIONS ON CHYTRIDIACEOUS PARASITES OF PHANEROGAMS. VIII. UROPHLYCTIS (PHYSODERMA) PLURIANNULATUS AND U. MAJUS

Sparrow , Frederick K. and Yamunga Lingappa . (U. Michigan, Ann Arbor.) Observations on chytridiaceous parasites of phanerogams. VIII. Urophlyctis (Physoderma) pluriannnlatus and U. majus. Amer. Jour. Bot. 47(3): 202—209. Illus. 1960.—Urophlyctis pluriannulatus, an obligate parasite of Sanicula spp., has an endobiotic phase which is strongly polycentric and produces small crateriform galls on the petioles and blades of the host leaves. The agent accomplishing infection is not known but is probably a zygote. The first cell of the parasite established in the host is the so-called “primary turbinate organ.” This becomes multinucleate, is somewhat pyriform and becomes multicellular by 2 methods: (1) by cleavage into peripheral segments; or (2) by division into cells, each with its own cell wall. Replication of the thallus is accomplished by the production of nucleated outgrowths bearing haustoria which elongate, become ribbon-like, somewhat roughened and lumened, and produce distally turbinate organs of a second order. Tertiary, etc. turbinate organs are produced in like manner. Resting spores usually form at the tip of an extremely short outgrowth from the apex of a turbinate organ. These bear a supra-equatorial crown of 7—10 branched haustoria. Rarely, monocentric thalli are formed, in which a single turbinate organ becomes converted into a resting spore. All nuclear division figures were intranuclear. The fungus produced marked enlargement of infected host cells and their nuclei, and caused division of neighboring cells. As development continues, lysis of the surrounding host walls takes place and a large cavity bearing a dense symplast and numerous host nuclei is formed, within which is the thallus of the parasite. At maturity, all traces of symplast and of fungus, except for resting spores, disappear. Urophlyctis majus, a parasite on leaves of Rumex orbiculatus, hitherto known only from its resting spore stage, has a pattern of development strikingly similar to that of U. pluriannulatus. Here, however, turbinate cells only form peripheral segments. Furthermore, the “hyphae” are smooth and without a lumen. Aside from size differences, the mature thallus with resting spores, unbranched (not branched) haustorial tufts, etc. is like that of the Sanicula parasite. The galls produced were compartmentalized, dark red to black, usually surrounded by a reddish zone, and early dropped from the leaf. No undoubted evidence of the epibiotic gametangial phase was found in either species.     

The significance of thallus size for the water economy of the cyanobacterial old-forest lichen Degelia plumbea

Rosette-formed, circular thalli of Degelia plumbea were studied in the laboratory. Regardless of thallus size, the optimal quantum yield of photosystem II (F _V/F _M) remained at a high, constant level during a drying cycle starting with fully hydrated thalli until the thallus water content reached about 200%. Net photosynthesis reached a maximum level at this hydration level. Thereafter, both F _V/F _M and net photosynthesis fell rapidly to zero at a water content of somewhat less than 100%. There was a highly significant, positive relationship between thallus size and the water-holding capacity, as well as a strong, negative correlation between size and water loss per thallus area. Consequently, an increase in thallus size from 1 to 36 cm² lead to a tenfold prolongation of the photosynthetically active period during a drying cycle at a low radiation regime. The improved water-holding capacity in larger thalli is mainly a result of a thicker hypothallus. The fast desiccation of small thalli suggests that the regeneration of D. plumbea could be severely hampered by nearby logging that raises the evaporative demand by increasing radiation loads and wind exposure at remaining lichen sites. Received: 12 December 1997 / Accepted: 20 March 1998     

Two new species of Distichophyllum from Malaya

Abstract

The germination and establishment abilities of different types of propagules under natural conditions is an area in bryophyte reproductive biology that is largely unknown. In some species gametophyte fragments, rather than spores, may be primarily responsible for establishment of new colonies in nature, and the presence of other mosses may have an effect on establishment processes. These ideas were tested experimentally using four species of Tortula grown in a glasshouse under semi-natural conditions. The relative germination and growth abilities of spores and gametophytic fragments were tested under each combination of the following treatments: (1) continuous hydration (using a mist system), or periodic drying; (2) substrate of bare sand, a clump of Dicranum scoparium, or (for spores only) the clump of Tortula from which sporophytes were taken. Fragments produced new shoots much more quickly than spores under either hydration condition but spores germinated at a higher rate. Germination rates of both spores and fragments were greatly reduced (usually to zero) in clumps of Tortula or Dicranum under either hydration condition. Some differences between species were noted. In a further experiment filter-sterilized water extracts of each species were applied to spores on agar. Again, strong effects on spore germination and protonemal growth were noted. Patterns of inhibition differed between species and reflected those found in the previous experiment, indicating that the inhibition effect may be due to a water soluble chemical rather than the physical properties of the moss clumps. These studies present the first experimental evidence for the chemical inhibition of spores by mature plants. When taken together with previous reports of chemical interactions among protonemal systems, considerable ecological significance of these results is suggested.     

大型绿藻浒苔藻段及组织块的生长和发育特征

通过将浒苔叶状体分为基部、中部和顶端三部分分别进行切段和切碎处理,在实验室条件下,用液体浅层培养的方法,系统地研究了其组织和细胞的生长和发育特性。显微观察的结果显示：切段培养条件下,基部和中部的藻段均可在其形态学下端形成假根,在形态学上端产生类似叶状体的突起。藻段的发育具极性,但是其极性并不绝对的,在1.0 mm的基部藻段两端都观察到了假根的形成。虽然顶端的藻段和组织块全都形成和释放了孢子,未见明显的营养生长,但是在培养早期,其下端仍然具有形成假根的能力。浒苔各部位藻段和组织块释放的和滞留于孢子囊内的孢子都可以立即萌发成苗。快速生长的中基部藻段形成了气囊,致使其漂浮于培养基上。有很多藻段和组织块形成和释放了生殖细胞,释放到外界以及滞留于孢子囊内的孢子均可立即附着萌发。数据分析表明：藻段的生长具有极性,不同部位相同长度的藻段生长率差异明显,基部藻段的生长率高于中部藻段,顶部藻段无明显的营养生长。藻段的生长与其原始长度和在藻体中所处的位置有密切关系;藻段和组织块的再生与藻体的完整性及其在藻体中所处的位置有关。     

Präadaption bei Flechten iranischer Halbwüsten

25 species of lichens have been collected in semidesertic to desertic areas of Iran. On the basis of spatial relations to the substrate and anatomical features of the thallus three main groups (one with a subdivision based on colour and morphology of the thallus) can be differentiated. Selective advantages and peculiarities in connection with the desert habitat are pointed out, such as inverse thallus-structure, a dense network of skeletal hyphae in the substrate in otherwise epilithic species, proliferating areolae of the thallus, immersed pycnidia with trichogynes and brownish spores in groups with usually colourless spores. Most of the species are wide-spread in arid and often also in humid regions; only one species,Verrucaria buschirensis J. Steiner, seems to be endemic. The prevalence of cyanophilic lichens in deserts may have phylogenetic reasons, as these groups appear to date back to periods without higher vegetation and a desert-like environment.

Herrn Prof. Dr. L.Geitler zum 80. Geburtstag gewidmet.     

INFECTION OF AEDES AEGYPTI LARVAE BY AXENIC CULTURES OF THE FUNGAL GENUS SMITTIUM (TRICHOMYCETES)

Spores from axenic cultures of Smittium spp., isolated from various geographical locations and from different dipteran hosts (mosquito, black fly, and chironomid larvae), were fed to mosquito larvae (Aedes aegypti). We were able to demonstrate some host specificity at the insect family level, but no significant differences in infectivity by isolates from different geographical areas. Spore germination and thallus attachment were observed in the host hindgut within 1.5 hr post spore ingestion. Preliminary studies indicate that S. culisetae has little effect on A. aegypti larvae when they are reared under conditions that promote pupation within 5–6 days. However, ingestion of large numbers of spores by 1st instar larvae growing under suboptimal nutritional conditions may produce fungal growth detrimental to larvae.     

SETTLEMENT AND SURVIVAL OF POLYSIPHONIA LANOSA (CERAMIALES) SPORES ON ASCOPHYLLUM NODOSUM AND FUCUS VESICULOSUS (FUCALES)1

The settlement patterns of spores of Polysiphonia lanosa (L.) Tandy on Ascophyllum nodosum (L.) Le Jolis and Fucus vesiculosus L. were studied using a flow tank. Settlement sites were defined as ‘sheltered’ or ‘exposed.’ Surface area calculations revealed non-random settlement on A. nodosum, with higher than expected spore frequencies on the thallus and lateral pits and lower than expected frequencies on the vesicles. Settlement of F. vesiculosus was random and significantly lower than on A. nodosum. On the shore, survival of sporelings from September (post-sporulation) to May (pre-sporulation) was highly non-random on both basiphytes. On A. nodosum, lateral pits ('sheltered') showed the highest survival frequency. Here the proportion of surviving sporelings increased over the study period, whereas the proportion on open thallus area ('exposed') decreased. On F. vesiculosus also preferential survival occurred on ‘sheltered’ sites such as vesicle/thallus interfaces and wounds. Between September and May, all P. lanosa sporelings were lost from ‘exposed’ areas (thallus surface and vesicles). Overall, frequencies of surviving sporelings were much greater on A. nodosum than on F. vesiculosus. These results are discussed with reference to basiphyte morphology, epiphyte removal mechanisms and the survival stratagy of P. lanosa.     

Trichostomopsis aaronis (Lor.) Agnew & Townsend new to the U.S.S.R.

Abstract

Occurrence of Ptilidium pulcherrimum in transects and spore dispersal from a single colony have been studied in a coastal spruce forest in northern Sweden. The main substrate type was rotting wood with 75% of all occurrences. Annual spore production was 68,500 spores/m² forest, 640,000 spores/m² substrate and 44,000,000 spores/m² colony. Almost 50% of the spores were deposited within 2.5 m of the colony. Annual spore deposition between colonies was estimated to be between 24,000–39,000 and deposition on the main substrate, decaying logs, was about 340–600 spores/m² forest. P. pulcherrimum showed a clumped distribution pattern up to about a 15 m neighbourhood distance. This pattern could not be explained by a similar clumping of the substrate. Instead a limitation by distance in establishment due to a deficit of spores is assumed.     

Dimostrazione ultrastrutturale di un componente parietale anomalo in Trichophyton mentagrophytes trattato con Phosfon D

Abstract

An abnormal cell wall component in Trichophyton mentagrophytes treated with Phosfon D: ultrastructural demonstration. – Phosfon D, a growth-retarding chemical in higher plants, at the concentration of 5 × 10^?4 M inhibits the development of the dermatophytic fungus Trichophyton mentagrophytes. In the treated samples the diameter of the thallus is about 50% smaller than normal. The mycostatic effect of Phosfon D is accompanied by characteristic alterations of the cell wall ultrastructure with the appearance of dense granular masses not revealable after conventional fixation, but only after employing TAPO containing fixatives.     

Calymperastrum,a new genus of Pottiaceae

Abstract

Annual growth rate and spore and capsule production was studied in 50 colonies of the epixylic hepatic, Ptilidium pulcherrimum in northern Sweden. Radial growth rate was independent of colony size but varied from year to year (mean value 5.2 mm year^?1, range 3.5–6.3 mm year^?1). Size at first sporophyte production was estimated to be 68 cm² and the age of first reproduction was estimated to be about 9 years. It was estimated that antheridia were formed the third year. No correlation between growth rates and reproduction was observed. Capsule density as well as capsule and spore production increased significantly with increased colony size. Differences between years in spore and capsule production (up to six-fold) were observed. The mean number of spores per capsule was 27 400 but significant differences between colonies (range from 18 000 to 44 000) were observed.     

Changes in Thallus Weight and Size in the Green Alga Ulva fenestrata under Artificial Conditions

From August to October 2002, daily measurements of the thallus weight and area were taken in sporophytes and male and female gametophytes of Ulva fenestrata at similar developmental phases. The algae were reared in aquaria at a constant temperature (22 ± 0.5°C); illumination was applied for 12h a day at a photosynthetically active radiation intensity of 400 E/(m² s). All generations showed a linear increase in the thallus weight and area over time with the same relative daily increment (8 to 15%). Generations differed significantly in time to onset of sporogenesis or gametogenesis. The female gametophyte, sporophyte, and male gametophyte began to release gametes or spores in 7, 10, and 15 days, respectively. A scheme for the distribution of cells among age groups is proposed. The scheme seems to account for the linear pattern of thallus growth.