Phaeoceros Laevis Research Articles

Ultrastructure of a Fungal Endophyte in Phaeoceros laevis (L.) Prosk. (Anthocerotophyta)

The gametophyte of the anthocerotophyte Phaeoceros laevis is associated with an aseptate fungus that forms extracellular thick-walled hyphae, intercellular thin-walled hyphae, and intracellular arbuscules. Vesicles are formed by swelling of inter- or intracellular hyphae and are common in summer. The fungus colonizes the parenchyma of the host, except at the growing apices, and is always absent from the epidermal cells. The intracellular hyphae are enclosed by an interfacial region that consists of the invaginated host plasmalemma, a light zone extending from the host periplasm, and a matrix continuous with the host wall. Bacterium-like organelles and two types of electron-dense granules are found in the fungal hyphae. Infected host cells show increased cytoplasmic contents; the single chloroplast loses starch and the pyrenoid and forms numerous convoluted branches that are intermingled with the arbuscular hyphae. The arbuscule eventually degenerates, producing intracellular clumps of collapsed hyphae. Ce...

The development of the placenta in the anthocerote Phaeoceros laevis (L.) Prosk

The development of the placenta in the anthocerote Phaeoceros laevis (L.) Prosk. was studied by transmission electron microscopy. By the time the sporophyte emerges from the involucre, a conspicuous placental region is formed by the intrusive growth of sporophyte foot haustorial cells into the adjacent gametophyte vaginula tissue. The separation of gametophyte cells by haustorial cells and their incorporation into the placenta are preceded by the loosening and swelling of their walls and the formation of a periplasmic space. This process causes the disruption of the plasmodesmata, and may eventually result in the complete isolation and consequent degeneration of the cells. Crystals are commonly observed in the vacuoles of gametophyte placental cells. Crystals become more abundant during cytoplasmic degeneration, and are released in the placental lacunae that result from the complete dissolution of gametophyte cells. During the subsequent phase of capsule elongation, the gametophyte placental cells that retain the symplastic connection with the adjoining gametophyte parenchyma develop a wall labyrinth typical of transfer cells. Obliteration of the wall labyrinth by deposition of lightly staining wall material is observed later in sporophyte development, in concomitance with capsule dehiscence. Crystals are negative to the periodic acid/thiocarbohydrazide/silver proteinate test for carbohydrates whilst they are completely digested by pepsin or protease, denoting protein composition.

CHLOROPLAST DEVELOPMENT IN LIGHT‐ AND DARK‐GROWN SPOROPHYTES OF PHAEOCEROS LAEVIS (L.) PROSK. (ANTHOCEROTOPHYTA)

SummaryChloroplast development in light and in darkness was investigated in the sporophyte of the anthocerote, Phaeoceros laevis (L.) Prosk. In both light‐and dark‐grown sporophytes, chloroplasts with an elaborate inner membrane system were found in chlorenchyma cells about 3 mm from the sporophyte base. Development in the dark resulted in a net increase of the average number of grana per unit of chloroplast area and of thylakoids per granum, and a parallel diminution in the chlorophyll a/b ratio. Substantial amounts of chlorophyll were synthesized in the dark. Small, paracrystalline arrays of membranes associated with extensive thylakoid stacks were found in immature plastids of dark‐grown sporophytes. These structures disappeared during early stages of subsequent chloroplast differentiation. These results are the first indication that the anthocerotes do not require light for the differentiation of their photosynthetic apparatus.

Zytologie der Blaualgen-Hornmoos-Symbiose bei Anthoceros laevis aus Island

Summary Luxuriant populations of Blasia pusilla L. and Anthoceros laevis L., both with symbiotic Nostoe sphaericum VAUCH., were found at the margins of icelandic hot springs in September 1978. Cytology of the Nostoc-Anthoceros laevis symbiosis was studied by light, transmission and scanning electron microscopy, and compared with available data on other Cyanophyte-Hornwort or -Hepatic symbioses. Some notes on the establishment of the Nostoc-Blasia symbiosis are added. Nostoc phycobionts develop intercellularly in the Anthoceros laevis gametophyte. Heterocyst frequency is increased from about 5 % in freeliving to about 37 % in symbiotically grown colonies. In heterocysts as well as in vegetative cells cyanophycin granules are found; this is due to abundance and accumulation of combined nitrogen. Carboxysomes, but no phycobilisomes are seen in vegetative cells, possibly indicating C-heterotrophic growth (or at least reduced photosynthetic activity) although the key enzyme of the Calvin cycle is present. Anthoceros cells bordering upon Nostoc colonies show changed cell wall structure and poorly developed, proplastid-like chloroplasts.

Physiological Evaluation of the Nutritional Autonomy of a Hornwort Sporophyte

The nutritional relationship between sporophytes and parent gametophytes of Phaeoceros laevis (L.) Prosk. was studied by (1) radioactive tracers to follow glucose uptake, CO2 fixation, and indoleacetic acid transport; (2) enzyme histochemistry to test for enhanced actvity in specialized transfer cells at the sporophyte-gametophyte interface; and (3) polarography to determine photosynthetic and respiratory rates. Based on fresh weight, sporophytes photosynthesize at almost twice the rate of gametophytes. The carbon fixed by photosynthetic sporophytes is sufficient for self-maintenance but not for sustained growth. Higher relative respiratory rates account for the observed nutritional reliance of sporophytes upon gametophytes. Enhanced enzymatic activity in transfer cells is correlated with net carbon transfer from gametophyte thalli. Mobilization of gametophyte reserves may be influenced by basipetally transported auxin from the sporophyte meristem. Labeled carbon accumulates in the intercalary meristem and in spores following uptake.

Membrane Potential in Phaeoceros laevis

Gametophyte cells of Phaeoceros laevis (L.) Prosk. have vacuole electric potentials (PDs) of about -175 millivolts; the steady PD is not affected by light but small transient PDs result after changing from light to darkness or darkness to light. The PD is more negative than the Nernst potentials for any of the permeating ions. Changes in the concentration of any one of the external ions between 0.1 and 10 mm have only a very small effect on the PD. Increases in external pH cause the PD to depolarize by a few millivolts. Azide, 2,4-dinitrophenol, and NH(4)Cl each cause rapid and reversible depressions of the PD; the effects of these agents are similar in magnitude in the light and in the dark. Anoxia depolarizes the PD by about 30 millivolts in the light and by about 60 millivolts in the dark. Ouabain and 3-(3,4-dichlorophenyl)-1,1-dimethylurea have no effects on the PD. It is concluded that the membrane potential is controlled by an electrogenic efflux pump, possibly for H(+). It is also concluded that the source of energy for the pump is respiration and not photosynthesis.

Additions to the Bryoflora of Iowa

Nineteen county records are reported from collections made in Waubonsie State Park, Fremont County, Iowa, including two species new to the state, Fissidens osmundoides Hedw. and Frullania brittoniae Evans. A series of collections from Waubonsie State Park (Washington twp., T67N,R42W) were made by the junior author in June of 1976 as part of a Fremont County foray cosponsored by the Iowa Ornithological Union and The Iowa State Preserves Board. The park features xeric, loess bluffs with sheltered ravines supporting oak-hickory forest. Identifications of these collections were made by the senior author, and the results were compared with the county flora reported by Conard (1956). The 35 species collected in the park included 19 species not previously reported from the county, of which two species are new to Iowa, as well as the second report of Tortella tortuosa and the third report of Leskeella nervosa in Iowa. Eight records reflect a significant westward extension of the Iowa distribution of that species. In the county records listed below significant extensions are noted with an asterisk (*) and state records with a dagger (t). Specimens are deposited at Conard Bryophyte Herbarium, University of Iowa, Iowa City (IA). The records are as follows: Atrichum angustatum (Brid.) B.S.G., *Barbula fallax Hedw., Bryum lisae DeNot var. cuspidatum (B.S.G.) Marg., *Bryum pseudotriquetrum (Hedw.) Gaertn., Meyer & Scherb., *Callicladium haldanianum (Grev.) Crum, *Desmatodon obtusifolius (Schwaegr.) Schimp., Dicranella varia (Hedw.) Schimp., Entodon cladorrhizans (Hedw.) C.Muell., Entodon seductrix (Hedw.) C.Muell., tFissidens osmundoides Hedw., tFrullania brittoniae Evans, Frullania eboracensis Gott., Leskea obscura Hedw., *Leskeella nervosa (Brid.) Loeske, Phaeoceros laevis (L.) Prosk., *Pohlia nutans (Hedw.) Lindb., Pylaisiella selwynii (Kindb.) Crum, Steere & Anderson, *Rhynchostegiella compacta (C.Muell.) Loeske and *Tortella tortuosa (Hedw.) Limpr. LITERATURE CITED CONARD, H. S. 1956. Mosses and liverworts of Iowa. Iowa Acad. Sci. 63: 345-354. FRANK D. BOWERS, Department of Biology, University of Wisconsin-Stevens Point, Stevens Point, WI 54481. JAMES H. PECK, Department of Biology, University of Wisconsin-La Crosse, La Crosse, WI 54601. 0007-2745/78/448$0.35/0 This content downloaded from 207.46.13.0 on Tue, 17 May 2016 06:01:48 UTC All use subject to http://about.jstor.org/terms

Sexual Life Cycle of Three Species of Funariaceae in Culture

Three species of the Funariaceae (Physcomitrella patens (Hedw.) B.S.G., Physcomitrium pyriforme (Hedw.) Hampe and Funaria hygrometrica Hedw.) have been cultured under sterile conditions on Knop's inorganic me- dium (liquid and agar) to determine the conditions and minimum time nec- essary for completion of the sexual life cycle (spore to spore). According to the data presented, the life cycle of F. hygrometrica may be completed in 4 months, P. pyriforme in 3 months and P. patens in 2 months. In all three species the critical factor for the induction and maturation of gametangia is cold temperature. Delineation of the life cycle makes these organisms suitable for genetic study. Studies concerning the reproductive phase in bryophytes in culture have been relatively few. Voth and Hammer (1940) implicated photoperiod as the stimulus nec- essary for gametophore production in Marchantia. Morris (1961) stated that in five species of leafy liverworts the onset of sexual reproduction is controlled primarily by photoperiod. Benson-Evans (1964) reported that four species of Marchantiales and six of Jungermanniales are long-day plants, while Riccia glauca and Anthoceros laevis are short-day plants. She also cited some evidence that the photoperiodic effect is operative in many liverworts only within certain temperature limits. Ridgway (1967) reported that in species of Anthoceros, Phaeoceros and Notothylas, photoperiod is critical in initiation of antheridia while temperature has little effect. Contrary to the cases reported for the liverworts and hornworts, temperature does seem to be the

A CYTOLOGICAL ANALYSIS OF THE NOSTOC‐BRYOPHYTE RELATIONSHIP

SUMMARYA comparative light and electron microscope study has been made of the Nostoc colonies within the thalli of Blasia pusilla and the three British species of Anthoceros, and also of the Nostoc isolated from each bryophyte. From their morphology in culture two taxa of Nostoc have been identified; N. sphaericum from Anthoceros punctatus, A. husnotii and A. laevis, and N. calcicola from other gatherings of Anthoceros laevis and Blasia. These findings support the notion that the algal‐bryophyte associations are none specific.Within bryophyte thalli, the Nostoc trichomes are closely packed and specific features cannot be recognized. Mucilaginous sheaths are much less extensive and there is no evidence that the alga thrive in mucilage produced by the adjacent bryophyte cells. Heterocyst frequencies as high as 50% in the bryophytic Nostoc spp. strikingly recall the Azolla, Gunnera and cycad‐blue‐green algal symbioses. Akinetes, readily produced in culture were only seen in the Nostoc from dormant Anthoceros. The absence of phycobilisomes and high heterocyst frequencies in the bryophytic Nostoc spp. corroborates physiological data that the algae receive organic carbon from their hosts which enable them to fix nitrogen heterotrophically.The Nostoc colonies in both Blasia and Anthoceros are extensively penetrated by multi‐cellular bryophytic filaments. Whereas in Anthoceros these comprise highly vacuolate, thin‐walled cells, which sometimes contain intracellular Nostoc trichomes, in Blasia the filaments are thick‐walled and often develop labyrinthine wall ingrowths. This transfer cell morphology may be interpreted as an adaptation facilitating interchange of metabolites between Blasia and Nostoc. Its absence in Anthoceros perhaps indicates a far less harmonious relationship or may be related to the higher nutrient status of the habitats where the Anthoceros spp. were collected.

An ultrastructural study of spermatogenesis inAnthoceros laevisL. with particular reference to the multilayered structure

SummaryThe structure and ontogeny of the multilayered structure (MLS) in Anthoceros are described. The microtubular band, or outer MLS layer, comprises 13 (rarely 14) microtubules and forms the cytoskeletal framework responsible for nuclear metamorphosis (1). In mid-spermatids three lamellar strata can be recognised. Prior to their disappearance as the spermatids near maturity the lamellar plates become occluded with osmiophilic material continuous with that of the osmiophilic crest. This latter structure and the strip of osmiophilic material beneath the anterior mitochondrion may have a mechanical function in the motile gametes, Flagellum structure is similar to that in other bryophytes and Isoetes but stellate profiles are absent from the basal bodies of Anthoceros.

Factors Initiating Antheridial Formation in Six Anthocerotales

In species of Anthoceros, Phaeoceros, and Notothylas, photoperiod is the critical environmental factor in the initiation of antheridia while tempera- ture (10-250 C) has little effect. The purpose of this investigation was to study some environmental factors which effect the initiation of sexuality in several species of Anthocerotales as evidenced by the formation of antheridia. Although numerous studies of environmental stimuli which induce the reproductive phase in algae, fungi, and flowering plants have appeared, only recently have such studies of hepatics been reported. Photoperiod was implicated in gametophore pro- duction in Marchantia (Voth & Hamner, 1940; Anthony, 1962) and in the initiation of sexuality in five species of Jungermanniales (Morries, 1961). Recently, extensive investigations of conditions which evoke initiation of sexuality in liverworts have been published by Benson-Evans (1965), who reported that four species of Marchantiales and six of Jungermanniales are long-day plants (16-18 hours of light diurnally), while Riccia glauca and Anthoceros laevis are short-day plants (6-8 hours of light diurnally). She also cited some evidence that the photoperiodic effect is operative in many liver- worts only within certain temperature limits. In Preissia quadrata, Pellia epiphylla, and Anthoceros laevis, however, the photoperiodic induction of sexuality is operative over a wide temperature range, she found. In Cryptothallus mirabilis (Benson-Evans, 1961), temperature alone, particularly during the dark period, appears to be most influential. Monroe (1965) also found that temperature was the limiting factor in inducing sexuality in the moss Funaria hygrometrica.

The Aseptic Culture of Liverworts in Microphytotrons

The Aseptic Culture of Liverworts in Microphytotrons

The 1958 Foray of the American Bryological Society

The 1958 Foray of the American Bryological Society was held in the vicinity of Greencastle, Indiana, under the guidance of Winona H. Welch. In all, 22 persons attended the Foray which was held August 23 and 24, prior to the American Institute of Biological Sciences meetings at Bloomington, Indiana. An informal organization period and social hour was held the evening of August 22 in Harrison Hall at DePauw University. Highlights of the evening included pictures of the Hattori Botanical Laboratory and Japanese bryologists. The pictures were collected by Dr. Paul Redfearn during a visit to Japan. Dr. \Welch then presented a brief history of bryology in Indiana and showed portrait slides of many of the botanists who figured in the historical sketch. This was followed by a tour of the Department of Botany and Bacteriology and a display of historically significant books on bryology and lichenology. The meeting was adjourned with refreshments. The next morning the participants breakfasted together and then proceeded to Fern Cliff, Lucietn M. Underwood's famous collecting site in Putnam County. On exposed clay soil near the parking area, Mannia fragrans, Phaeoceros laevis and a sterile Fossombronia were growing in mixture with Bryum argenteum and Weissia vziridula. A short walk led to a second-growth deciduous woodland where Platygyrium repens, Rhynchostegium serrulatum, Atrichum angustatum, Entodon seductrix, Anomodon attenuatus and Frullania eboracensis were abundant. The cliffs

The Structure of Anthoceros laevis in relation to its Water Supply

Journal Article The Structure of Anthoceros laevis in relation to its Water Supply Get access IVOR ISAAC IVOR ISAAC University College of Suansea, and Botany SchoolCambridge Search for other works by this author on: Oxford Academic PubMed Google Scholar Annals of Botany, Volume 5, Issue 2, April 1941, Pages 339–352, https://doi.org/10.1093/oxfordjournals.aob.a087397 Published: 01 April 1941

On the Number of Chloroplasts in the Cells of the Sporophyte of Anthoceros laevis

In a study of the morphology of the gametophyte and sporophyte of Anthoceros laevis L., the writer was somewhat surprised to find in stained microtome sections of the sporophyte the presence of but one chloroplast in cell, since in the literature one is given the impression that sporophyte cells contain regularly two chloroplasts (Campbell 'I8, pp. I21, 142, 597). Inasmuclh as the single chloroplast in cell of the gametophyte, in all North American species, seems to be an organ as permanent as the nucleus, it would be natural to suppose that the cells of the sporophyte mnight contain two chloroplasts, one being derived from the egg and the other from the sperm in the form of a very small primordium. Hofmeister, as early as I862, stated in regard to the number of chloroplasts found in the sporophyte that cells of the upper part of the young fruit [A. laevis L. and A. putnctatus L.] contain without exception two chlorophyll bodies; but that in the inner tissue of the stem fgametophyte] the appearance of two chlorophyll bodies is unusual. Campbell ('i8, p. I42) in describing the sporophyte of A. fusiformis and A. Pearsoni, says that there is a doubling of chloroplasts in the sporophyte, and specifically that each epidermal cell contains two large chloroplasts like that of the gametophyte. He refers also to Schimper ('85) as having lnoted that the chloroplasts double in the sporophyte of Anthoceros. The statement of Schimper (i1c. cit. p. 21) pertains to A. laevis. The spore-mother-cell shows regularly only one chloroplast. Therefore the presence of two chloroplasts in the vegetative cells of the sporophyte would be strange and not easily explained. Strasburger ('80) and Davis ('99) have traced the complete history of the spore-mother-cell and its two divisions to form the tetrad. Barring nuclear details, it is not at all difficult to observe all phases of the division of the spore-mother-cells in the fresh material, since the spores mature gradually and the sporemother-cells readily separate from other.

THE PYRENOID OF ANTHOCEROS

The single chloroplast of the cells of the gametophyte of the Anthocerotes, with its pyrenoid-like central region, has long been known. Notwithstanding this, detailed descriptions of these chloroplasts and pyrenoids and comparisons with those of the algae, on the one hand, and with the chloroplasts of the liverworts on the other, seem to be lacking. As early as I85I von Mohl (I4) called attention to the fact that there were wohl 50 bis IOO Amylumk6rner in the chloroplasts of Anthoceros, but he did not relate them to the starch aggregations to be found in the green algae. The voluminous earlier literature on the morphology of Anthoceros, as far as I can determine, contains only bare mentions of the chloroplasts and pyrenoids. Leitgeb (g) in fact seems to have made no reference whatever to these structures. Schimper (i8) states that the pyrenoids of Anthoceros zeigten nach Entfernung der Starke durch Verdunklung nur noch corrodierte, unregelmassig eckige Umrisse. His figures I5 and I6 are apparently surface views of entire, living cells and show only diffuse central regions which have no resemblance to the plastids as seen in stained material. Davis (5) in an account of the nuclear division and the fission of the chloroplasts in the spore mother cells of Anthoceros laevis makes no reference to a pyrenoid and nothing in his figures suggests such a structure. He is unable to identify plastids in the archesporial cells and only as these cells become spore mother cells can the single, very minute chloroplast be identified. This chloroplast enlarges rapidly and undergoes two fissions, thus forming the four chloroplasts of the spore tetrad. The large chloroplasts of the mature spores are filled with conspicuous starch grains, becoming thus storage vesicles of starch. Campbell (3, 4) has made the most important recent contribution