Elektronenmikroskopische Analyse der Musterbildung im Antheridium derPolypodiaceae

An electron microscopical investigation of the cell walls in young antheridia ofPolypodium crassifolium andPlatycerium alcicorne confirms the classical developmental model as postulated byStrasburger and byKny. The structure of the basal cell walls, both of the funnel cell and of the operculum, and especially the evidence of plasmodesmata in those walls, disprove the widely accepted interpretation presented 1951 byDavie.

     

A contribution to the Mesochorinae (Hymenoptera: Ichneumonidae) of Turkey

We present a first account of the species of the subfamily Mesochorinae (Hymenoptera: Ichneumonidae) found in Turkey and give distributional records for 5 genera and 23 species. Among them, 3 genera (Cidaphus Förster, 1869; Mesochorella Szepligeti, 1911; Stictopisthus Thomson, 1886) and 20 species are new for the fauna of Turkey.     

Effect of Some Chelating Agents on Growth and Antheridial Production in Male Clones of Three Mosses Grown In Vitro

The present work deals with the effect of the chelating agentsethylenediamine-di(o-hydroxyphenylacetic acid) [EDDHA] ethylenediamine tetra acetic acid [EDTA] and their iron salts, salicylicacid and ferric citrate on growth and antheridial productionin male clones of three dioecious mosses: Barbula gregaria,Bryum coronatum and Philonotis turneriana., Barbula and Bryumdevelop antheridia in ordinary cultural conditions on basalmedium, whereas Philonotis remains sterile. In Barbula and BryumEDDHA and EDTA enhance the percentage of fertile gametophytes.Fe-EDDHA and Fe-EDTA increase antheridial production as wellas vegetative growth and the former effect is more striking.In this respect Fe-EDDHA is better than Fe-EDTA for Barbula,whereas the reverse is true for Bryum. Salicylic acid inhibitsantheridial production and vegetative growth. Ferric citrateenhances vegetative growth in all three mosses. In Barbula andBryum it also stimulates antheridial production, and this effectis more marked than that on vegetative growth. None of the chelatestested induces antheridia in Philonotis. antheridial production, Barbula gregaria (Mitt.) Jaeg., Bryum coronatum Schwaegr., Philonotis turneriana (Schwaegr.) Mitt., mosses, chelating agents, bryophyta     

Chara tomentosa Antheridial Plasmodesmata at Various Stages of Spermatogenesis

Chara tomentosa antheridial plasmodesmata are described during proliferation and spermiogenesis. In antheridial filament cells which are cycling completely synchronously, unplugged plasmodesmata are filled with light cytoplasm. The same plasmodesmata are observed after cessation of mitotic division followed by the onset of synchronous spermiogenesis. Walls separating cells at different cell cycle stages and dividing antheridial filaments into asynchronous domains are plugged with a dense osmophilic substance. Similarly plugged plasmodesmata are present between antheridial cells of different types, e.g., capitular cells and antheridial filaments. In mid spermiogenesis when abundant endoplasmic reticulum (ER) appears temporarily it penetrates into plasmodesmata enabling cell-to-cell transport via ER cisternae. In late spermiogenesis there are no cisternae in plasmodesmata. This revised version was published online in July 2006 with corrections to the Cover Date.     

ON THE CYTOLOGY OF ANTHERIDIUM FORMATION IN THE FERN SPECIES ONOCLEA SENSIBILIS. I. CYTOLOGY OF CELL PLATE AND CELL WALL FORMATION

In the four-celled antheridium of the fern species Onoclea sensibilis a central spermatogenous cell is enveloped by a jacket of three cells. Starting from the base, the jacket comprises the cup-shaped basal cell, the ring cell—both of which encircle the spermatogenous cell—and the cap cell. The lower wall of the spermatogenous cell has the configuration of a funnel; its upper wall is dome shaped. The choice of whole antheridia for study instead of sectioned ones has, for the first time, made it possible to study the formation of the uniquely shaped antheridial cell plates step by step. The cell plate antecedent of the funnel wall has the configuration of a funnel. This conclusion conflicts with Davie's contention that this cell wall is oriented transversely at first and acquires funnel-shape secondarily. The present studies further show that the funnel cell plate forms from base to rim. This finding contrasts with a report that in another fern species this cell plate begins to form on one side of the initial and then proceeds circularly around it. The base of the funnel cell plate attaches to the basal wall of the antheridium initial in a separate event. The genesis of the dome-shaped upper wall of the spermatogenous cell is described for the first time.     

The role of asymmetric cell division in pteridophyte cell differentiation. I. Localized metal accumulation and differentiation inVittaria gemmae andOnoclea prothallia

Summary In gemmae ofVittaria graminifolia and prothallia ofOnoclea sensibilis, cell differentiation is initiated by nuclear migration and geometrically asymmetric cell division. The small daughter cells inVittaria develop into antheridia in the presence of gibberellic acid or into rhizoids or new prothallia in its absence. Antheridial differentiation from asymmetric division is induced inOnoclea byPteridium antheridiogen, whereas rhizoid or vegetative cell formation occurs in its absence. Although asymmetric cytokinesis initiates differentiation, it does not in itself determine the developmental fate of the smaller cell. Several histochemical techniques demonstrate that prior to nuclear migration and cell division, Ca²⁺ accumulates in the cytoplasm and wall of the cell at the site where asymmetric division will occur, regardless of the developmental fate of the small cell. The cytoplasmic localization of Ca²⁺ appears to reflect a mobilization of Ca²⁺ from within the cell that eventually moves into the cell wall. We propose that this internal accumulation of Ca²⁺ leads to a localized decrease in cytosolic [Ca²⁺] which in turn may regulate developmental events such as nuclear migration.Publishing prior to 1984 as Alix R. Bassel.     

ON THE RELEASE OF SPERMS IN ATRICHUM

An antheridium of Atrichum contracts when it opens. This contraction rapidly ejects much of the mass of sperms because a fluid present in the base of the antheridial chamber acts as an hydraulic ram. The residue of sperms is slowly extruded as the same fluid takes up water. Photographs allow the construction of time courses that directly demonstrate the existence of two phases (rapid vs. slow) in sperm release. Antheridia open as quickly in 1 m sucrose as they do in water. Molar sucrose allows only the rapid phase of sperm release, caused by the contraction of the jacket, and the antheridia remain only partly emptied. This behavior in sucrose solution provides a convenient test for similarities among antheridia. The mechanism of sperm release that occurs in Atrichum occurs in Polytrichum and Mnium as well.     

Effect of Some Known Growth Regulators on Growth and Fertility in Male Clones of the Moss Microdus brasiliensis (Dub.) Ther.

Among the auxins (IAA, 2,4-D, NAA and NOA) LAA proves inhibitoryfor antheridial formation. The rest promote this response, andNAA is most effective. Cytokinin (2iP) stimulates vegetativegrowth as well as antheridial formation, but the effect is morepronounced on the former. Interaction of kinetin and IAA provesbetter for antheridial production as compared to IAA alone.Gibberellic acid enhances gametangial induction as well as vegetativegrowth at lower levels (10^–8–10^–8 mol dm^–3).With abscisic acid both the responses are markedly reduced.Anti-auxins and cycocel promote antheridial production and vegetativegrowth. Testosterone is more potent than progesterone in promotingantheridial formation and vegetative growth. Key words: Fertility, growth hormones, moss     

The cytology of Halidrys siliquosa (L) Lyngb

Resting nuclei in vegetative apices and developing receptaclesof Halidrys siliquosa (L) Lyngb. contain several large, Feulgen-positivegranules. The number of granules varies from two to nine inboth vegetative cells and developing gametangia. Approximately55 chromosomes have been counted in the meristoderm cells ofthe apical groove, and approximately 30 in the first, second,and third divisions of the antheridial initials.     

ANALYSIS OF STARCH ACCUMULATION AND GERMINATION IN ONOCLEA SPORES

Previous studies have shown that low fluences of light accelerate starch accumulation and enhance germination of Onoclea spores. Fluence response curves for induction of starch accumulation were compared with fluence response curves for enhancement of germination in order to determine if the two photoresponses in Onoclea spores have a common photoreceptor. Fluence response curves indicate that both responses were proportional to the log of the fluence and that the relative fluence efficiencies of the four wavelength regions tested were similar for induction of both germination and starch accumulation. Red (600–720 nm) irradiation was the most efficient, while green (500–600 nm), blue (400–520 nm), and far-red (720–900 nm) irradiations showed a decreasing order of efficiency for induction of the responses. A correlation coefficient between the amount of starch accumulated as a result of red irradiation and the final percent germination was calculated to be 0.964. These results support the hypothesis that a common photoreceptor mediates both photoinduced germination and starch accumulation. 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) inhibits photosynthesis by blocking the flow of electrons from Photosystem II to Photosystem I. At 0.1 mM DCMU failed to inhibit both photoinduced starch acumulation and germination. This result and the greater efficiency of red than blue light, the low fluence functional for induction, and the fluence dependency argue against the participation of photosynthesis in photoinduced starch accumulation. A similar conclusion has been previously drawn for photoenhancement of Onoclea spore germination. Additionally, the effects 0.01–1.0 mm cycloheximide and 100 μl/l ethylene on photoinduced starch accumulation were investigated. Neither agent inhibited starch accumulation, whereas both substances inhibited germination 70–90% when applied at a time coincidental with the period of rapid starch accumulation. These results indicate that the photoinduction of starch accumulation does not have an ethylene sensitive stage nor does it require protein synthesis as does photoenhancement of germination of Onoclea spores.     

HETEROTHALLISM AND SEXUALITY IN ASCOBOLUS STERCORARIUS

Bistis, G. N., and J. R. Raper. (Harvard U., Cambridge, Mass.) Heterothallism and sexuality in Ascobolus stercorarius. Amer. Jour. Bot. 50(9): 880–891. Illus. 1963.—The steps in the sexual development of the heterothallic ascomycete, Ascobolus stercorarius, are: (1) induction of antheridial hyphae and antheridia; (2) induction of ascogonial hyphae and ascogonia; (3) directed growth of the trichogyne; and (4) plasmogamy. Although this sequence occurs in each of the 2 reciprocal combinations (A –antheridial/a-ascogonial and a-antheridial/A-ascogonial), several differences between the 2 combinations have been found. The differences are especially apparent with regard to antheridial induction and the pattern of proliferation of ascogonial hyphae. A study of the specificity of the agents regulating the sexual reactions between the 2 mating-types has confirmed previously described class-specificity at antheridial induction (sexual activation). Experiments utilizing substituted oidia have demonstrated an absence of mating-class specificity in trichogyne attraction and even at plasmogamy. The incipient fruiting bodies which result from illegitimate fusions (a X a and A X A), however, stop growing after 24 hr. This cessation of development suggests the presence of a second block to self-fertility in the sexual process of this species.     

SPERMATOGENESIS IN A HOMOSPOROUS FERN,ONOCLEA SENSIBILIS

A detailed study of spermatogenesis in a homosporous fern, Onoclea sensibilis L., is presented from the formation of the first spermatogenous cell to the release of the sperm. Two different walls are deposited around the developing spermatids at specific developmental stages as opposed to one wall reported for other species. Most ultrastructural changes that occur in Onoclea during spermatid differentiation resemble those described in previous studies on other fern species, with the following exceptions: 1) A previously undescribed structure appears during midspermatid stage. This dense layer of amorphous material with a row of evenly spaced light areas occurs between the anterior portion of the mitochondrion associated with the multilayered structure and the anterior plasmalemma of the spermatid. 2) An early stage in blepharoplast formation resembles that which occurs in the heterosporous fern Marsilea, in contrast to that which has been reported in Platyzoma, the only other homosporous fern studied at this stage. 3) The osmiophilic crest does not form as early as reported in other ferns. 4) The cap cell of Onoclea is removed intact, rather than collapsing or forming a pore during sperm release. Observations are reported on the number of sperm per antheridium, the time course of spermatogenous cell mitosis, and of differentiation of spermatids into sperm. In Onoclea, an antheridium may contain either 32 or 64 sperm. Regardless of the final number of sperm, each has approximately the same volume.     

PIN2-like proteins may contribute to the regulation of morphogenetic processes during spermatogenesis in <Emphasis Type="Italic">Chara vulgaris</Emphasis>

Key message

PIN2-like auxin transporters are expressed, preferentially in a polarized manner, in antheridial cells of freshwater green alga Chara vulgaris , considered to be the closest relative of the present-day land plants.

Abstract

Chara vulgaris represents a group of advanced multicellular green algae that are considered as the closest relatives of the present-day land plants. A highly specialized structure of its male sex organs (antheridia) includes filaments consisting of generative cells, which after a series of synchronous divisions transform into mature sperm, and non-generative cells comprising outer shield cells, cylindrical manubria, and central complex of capitular cells from which antheridial filaments arise. Immunofluorescence observations indicate that PIN2-like proteins (PIN2-LPs), recognized by antibodies against PIN-FORMED2 (PIN2) auxin transporter in Arabidopsis thaliana, are expressed in both types of antheridial cells and, in most of them, preferentially accumulate in a polarized manner. The appearance of PIN2-LPs in germ-line cells is strictly confined to the proliferative period of spermatogenesis and their quantities increase steadily till antheridial filaments reach the 16-celled stage. An enhanced level of PIN2-LPs observed in the central cell walls separating two asynchronously developing parts of antheridial filaments (characterized by the plugged plasmodesmata) is correlated with an enhanced deposition of callose. Intense PIN2-LPs immunofluorescence maintained in the capitular cells and its altering polarity in manubria suggest a pivotal role of these cells in the regulation of auxin transport directionality during the whole time of antheridial ontogenesis. Immunohistochemical staining of IAA revealed a clear-cut correspondence between localization sites of auxins and PIN2-LPs. It seems probable then that a supplementary developmental mechanism has evolved in Chara, by which all antheridial elements may be integrated at the supra-cellular level via plasma membrane-targeted PIN2-LPs and auxin-mediated processes.

     

Symplasmic isolation ofChara vulgaris antheridium and mechanisms regulating the process of spermatogenesis

Summary The antheridium ofChara vulgaris L. is connected by plasmodesmata with the thallusvia a basal cell. Prior to the initiation of spermatozoid differentiation these plasmodesmata are spontaneously broken, resulting in symplasmic isolation of the antheridium.Premature plasmolytically evoked symplasmic isolation of the antheridium leads to a 2–4 fold reduction in the length of antheridial filaments and the elimination of 1–2 cell cycles from the first stage of spermatogenesis.Autoradiographic and cytophotometric studies have shown that, as a result of induced symplasmic isolation of the antheridium, endomitotic DNA synthesis was blocked both in the young manubria (after 24 hours) and in the capitular cells (after 48 hours). In the antheridial filaments DNA synthesis was inhibited together with either elimination of divisions and induction of spermatid differentiation or developmental block. We propose that breakage of plasmodesmata connecting the antheridium with the thallus is a signal which releases, in all antheridia, mechanisms that (i) block endomitotic DNA synthesis in the manubria, (ii) restrict the growth rate and the divisions of antheridial filament cells, and (iii) induce spermiogenesis in these antheridia in which the manubria attained the sufficient level of polyploidy.This work is supported by the Polish Academy of Sciences within the project CPBP 04.01.5.05.     

Effects of Population Density on Sex Expression in Onoclea sensibilis L. on Agar and Ashed Soil

Population density affected the sex expression of agar-growngametophytes of Onoclea sensibilis L. The time of onset of sexualitywas advanced, the proportion of females was increased, and thegrowth rate of individuals was greater at lower densities. Populationdensity had no effect on the sex expression of Onoclea grownon ashed soil, and there was no difference in growth rate ofindividuals grown on ashed soil at different densities. Covariateanalysis, using thallus width as a measure of growth rate, indicatedthat the effect of density on sex expression was mostly associatedwith growth rate. The differing effects of population densityon agar and ashed soil demonstrate that substrate influencessex expression in Onoclea. This influence is most dramatic insingle-gametophyte cultures, where agar cultures produced 97per cent females and ashed soil cultures 100 per cent males. Onoclea sensibilis L., sensitive fern, fern gametophytes, sexuality, population density     

MICROGAMETOPHYTE DEVELOPMENT IN THE PALEOZOIC SEED FERN FAMILY CALLISTOPHYTACEAE

Well-preserved stages of microgametophyte development are described from pollen produced by the Paleozoic seed fern family Callistophytaceae. Microgametophyte development in both the Middle Pennsylvanian pollen organ Idanothekion and Upper Pennsylvanian Callandrium involved the initial production of an axial row of at least three small prothallial cells proximally and a large embryonal cell distally. The arrangement and form of these cells is like that present in some extant genera of the Pinaceae. The prothallial cells were relatively large in comparison with extant gymnosperms, occupying the entire region of the cap-pus, and were apparently all primary. Evidence is presented that in Callandrium further development involved an anticlinal division of the large distal cell (antheridial initial) into a small generative cell contained within a larger tube cell. Previously described microgametophytes of the late Paleozoic order Cordaitales are reinterpreted and are shown to consist of an embryonal cell and three to four discoidal prothallial cells in an axial row like that of the Callistophytaceae. Microgametophytes thus far described from the Paleozoic are remarkably modern in appearance and provide no evidence to support the generally held view that the seed plant microgametophyte is an extremely reduced sexual phase that has arisen through the loss of almost all of the vegetative cells and the sterile outer cells of the antheridium. Evidence to support or refute this view will depend upon the discovery of microgametophytes from older groups of seed plants than those for which they are now known.     

Regulation of Growth and Gametangial Formation in Riccia gangetica Ahmad by Some Amino Acids

The present work deals with the effect of six amino acids: asparagine,aspartic acid, glutamic acid, glycine, serine, and tryptophan,on growth and gametangial formation in Riccia gangetica. Allthe amino acids tested enhance vegetative growth, and amongthese glutamic acid proves best. The total number of rhizoidsis reduced in response to amino acids. Aspartic acid and glutamicacid favour antheridial production. In contrast, asparagine,serine, and tryptophan enhance archegonial formation, and amongthese asparagine elicits the best response. Glycine proves bestfor antheridial production, and also increases the number ofarchegonia. Key words: Riccia gangetica, Amino acids, Growth, Gametangial formation     

A DNA excision repair system for Neisseria gonorrhoeae

Summary The removal of pyrimidine dimers from deoxyribonucleic acid of ultraviolet irradiated cultures of Neisseria gonorrhoeae can not be readily ascertained by using radioactively labeled thymidine percursors. However, by adapting the alkaline agarose gel technique of Achey et al. (Photochem Photobiol 29, 305–310, 1979), it was possible to demonstrate that this human pathogen does possess an active excision repair system that functions on pyrimidine dimers.This work was performed as partial fulfillment for a Doctoral Thesis by L.A. Campbell.     

AQUATIC FUNGI OF ICELAND: ACHLYA AMERICANA

Twenty-one isolates of Achlya with smooth-walled oogonia, small, eccentric oospores, and a preponderance of monoclinous antheridial branches are characterized quantitatively and qualitatively. The isolates are separated into nine series, and the parameters through which they relate to and digress from one another are discussed. At most, three quantitative characteristics separate the various groups. The distinctive features of isolates in two series are unstable in culture. A concept of broad species limits is applied to A. americana.     

Observations on the Cytology of Halidrys siliquosa (L.) Lyngb.

A study of the cytology of Halidrys siliquosa suggests thatit has a haploid thallus with reduction division immediatelyfollowing fertilization. There appear to be eight chromosomesin vegetative cells and developing antheridial and oogonialcells. Typical ‘bouquet’ and diakinesis stages suggestinga reduction division have been seen on germination of the zygote.