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1.
Gilbert Turian 《Protoplasma》1956,47(1-2):135-138
Summary The gametes ofAllomyces javanicus exhibit a nuclear cap essentially made of ribonucleoprotein with sulphydryl groups.When dipped in phosphate buffered solutions of boric acid M/20–M/400, the male and female gametangia ofAllomyces liberate giant male and female gametes. Such giant gametes exhibit either a single regular nuclear cap (with 2 or 3 nuclei) or a massive and irregular basophilic formation (with 4–10 nuclei).Boric acid may interfere with ribonucleic acid, essential constituent of the nuclear cap, during the cleavage of the gamete-units in the gametangia. 相似文献
2.
Peroxidases in Acetabularia: their possible role in development 总被引:1,自引:0,他引:1
Thérèse Vanden Driessche Claire Kevers Thomas Gaspar Roland Caubergs 《Differentiation; research in biological diversity》1984,27(1-3):175-181
Abstract. Crude enzymatic extracts from Acetabularia exhibit very low peroxidase activity after a lag period. Starch gel electrophoresis of extracts from growing algae shows a single, extremely anodic band. Extracts of small, slow-growing or cap-bearing algae, which do not grow any more, do not exhibit any peroxidase band. Cytochemical staining with benzidine reveals changes in both the quantity and distribution of peroxidase along the polarized Acetabularia cell. The homogenous staining of small algae becomes distributed along a negative apico-basal gradient when the algae initiate their rapid growth phase. This polarized pattern is repeated on the hair whorls. A similar developmental sequence directs cap growth, with an initial intense staining reaction of the primordium, which later leaves only the corona inferior stained blue. Finally, the Acetabularia cell remains slightly blue at the edges of the rhizoidal out-growths and cap rays. Crude extracts of Acetabularia induce a lag in standard horseradish peroxidase (HRP) activity. The inhibitor is always present in small and growing algae; it is sometimes absent or less active in cap-bearing algae. In no case does it change the kinetics of the HRP reaction with guaïacol. The lag is completely suppressed by pretreatment with either H2 O2 or ascorbate oxidase. The changes in peroxidase activity, correlated with developmental stage and according to a polarized gradient, suggest that the enzyme could be involved in some way in the control of morphogenesis in Acetabularia . An inhibitor of peroxidase activity, which disappears as the cap matures, might, in turn, exert a regulatory function. 相似文献
3.
Summary. The configuration and distribution of polyadenylated RNA (poly(A)+ RNA) during cyst formation in the cap rays of Acetabularia peniculus were demonstrated by fluorescence in situ hybridization using oligo(dT) as a probe, and the spatial and functional relationships
between poly(A)+ RNA and microtubules or actin filaments were examined by immunofluorescence microscopy and cytoskeletal inhibitor treatment.
Poly(A)+ RNA striations were present in the cytoplasm of early cap rays and associated with longitudinal actin bundles. Cytochalasin
D destroyed the actin filaments and caused a dispersal of the striations. Poly(A)+ RNA striations occurred in the cytoplasm of the cap rays up to the stage when secondary nuclei migrated into the cap rays,
but they disappeared after the secondary nuclei were settled in their positions. At that time, a mass of poly(A)+ RNA was present around each of the secondary nuclei and accumulated rRNA. This mass colocalized with microtubules radiating
from the surface of each secondary nucleus and disappeared when the microtubules were depolymerized by butamifos, which did
not affect the configuration of actin filaments. These masses of poly(A)+ RNA continued to exist even after the cap ray cytoplasm divided into cyst domains. Thus two distinct forms of poly(A)+ RNA population, striations and masses, appear in turn at consecutive stages of cyst formation and are associated with distinct
cytoskeletal elements, actin filaments and microtubules, respectively.
Correspondence and reprints: Graduate School of Kuroshio Science, Kochi University, 2-5-1 Akebono-cho, Kochi 780-8520, Japan. 相似文献
4.
D. Menzel 《Protoplasma》1986,134(1):30-42
Summary The cytoskeleton in the siphonous, marine green algaAcetabularia is visualized by immunocytochemistry using antibodies against plant alfa tubulin and animal smooth muscle actin. In the vegetative phase of the life cycle, when the cell grows a cylindrical stalk and until the reproductive cap is completed, actin forms continuous, parallel bundles that extend through the entire length of the stalk and cap rays respectively. Microtubules (MTs) cannot be detected until the primary nucleus, located in the rhizoid of the giant cell, divides to form thousands of secondary nuclei. MTs can then be seen radiating from each secondary nucleus that is encountered in the stalk on its migration upwards into the cap rays. They are oriented mostly parallel to the long axis of the cell. At arrival in the cap rays up to the white spot stage, when nuclei assume equidistant positions in the cap ray cytoplasm, a radiating system of MTs forms around each nucleus and dramatically increases until impressive radial arrays have developed. This phase coincides with a disappearance of actin bundles in the cap rays, but they are retained in the stalk cytoplasm. Shortly after that additional MTs appear around the disk like partitions of cap ray cytoplasm. Concomitantly, bundles of actin reappear colinearly with the circumferrential MTs eventually forming complete rings around each disk of cap ray cytoplasm. During this process the compartments of the future cysts are gradually bulging outwards and simultaneously the rings of actin sink inwards until domes are formed with the nuclei fixed in the top centers of the domes. At this stage the peripheral areas of the radiating MT systems around the nuclei start to break down, whereas the circumferrential MT systems remain intact. Subsequently, the rings of both actin and MTs decrease in diameter, and finally contract to a spot opposite the nucleus, while the cysts continue to develop their oval shape. After the cysts have become separated, they round up and enter several rounds of nuclear divisions. MTs form short radial arrays around each nucleus with minor changes due to a reduction of MTs during division followed by a reappearance after completion of each division. Actin is rearranged in the cysts to a cortical network of randomly oriented, short bundles, that is maintained until gamete formation sets in.These findings accentuate the involvement of Cytoskeletal elements in the key steps of morphogenesis inAcetabularia to an extent that is unknown in higher plants. 相似文献
5.
《Journal of bryology》2013,35(3):581-591
AbstractMonoclonal cultures of Fossombronia brasiliensis were grown with different photoperiods, temperatures and inorganic nitrogen sources. The subsequent vegetative growth and production of gametangia is described. A quantitative analysis of the numbers of antheridia and archegonia and their relative proportions is given. At 18°C, F. brasiliensis was found to be a short-day plant, with a critical night length of between six and twelve hours, while at 10°C it exhibited quantitative SD plant properties. Plants produced more male gametangia at 18°C and more female gametangia at 10°C. Nitrogen as nitrate consistently produced more gametangia than the ammonium source. 相似文献
6.
In contrast to cytochalasin D which selectively prevents differentiation of female gametangia, cytochalasins A, B and E also
masculinizeAllomyces arbuscula by preventing septation between female and male gametangia, thereby allowing the dominant expression of the male characteristics. 相似文献
7.
In this study, the effects of UVA and UVB rays on antioxidant enzymes (superoxide dismutase, glutathione peroxidase, catalase) were examined in the corneal epithelium. The corneas of albino rabbits were irradiated with a UV lamp generating UVA (365 nm wavelength) or UVB rays (312 nm wavelength), 1 x daily for 5 min, from a distance of 0.03 m, over 4 days (shorter procedure) or 8 days (longer procedure). In contrast to UVA rays, which did not evoke significant disturbances, UVB rays changed the activities of antioxidant enzymes. The longer repeated irradiation with UVB rays was performed, the deeper the observed decrease in antioxidant enzymes. The shorter procedure evoked a more profound decrease of glutathione peroxidase and catalase (the enzymes cleaving hydrogen peroxide) than of superoxide dismutase, an enzyme scavenging superoxide radical and producing hydrogen peroxide during the dismutation reaction of a superoxide free radical. This may contribute to an insufficient hydrogen peroxide cleavage at the corneal surface and danger to the cornea from oxidative damage. After the longer procedure (UVB rays), the activities of all antioxidant enzymes were very low or completely absent. In conclusion, repeated irradiation of the cornea with UVB rays evokes a deficiency in antioxidant enzymes in the corneal epithelium, which very probably contributes to the damage of the cornea (and possibly also deeper parts of the eye) from UVB rays and the reactive oxygen products generated by them. 相似文献
8.
Brief treatment with hypertonic solutions induced gamete discharge from gametangia in the coenocytic green alga Bryopsis plumosa (Hudson) C. Agardh. It is known that gamete discharge in this alga is triggered by a change from darkness to light. However, in this study mature gametangia, incubated for 30–120 s in artificial seawater (ASW) with an additional 0.4–0.6 M NaCl and then transferred into pure ASW, discharged gametes in darkness. The treatment did not affect the motility of the gametes. Addition of sucrose (1.0–1.2 M) to ASW also induced gamete discharge in darkness. Similar results were obtained by adding KCl (0.4 M) or mannitol (1.2 M) to ASW. Continuous incubation of gametangia in such hypertonic solutions also induced gamete discharge but led to a delay and a reduction in the rate of gamete discharge, and a loss of gamete motility. In gametangia treated with the hypertonic solutions, as well as in those exposed to light, shortening of the gametangial length was observed before gamete discharge. 相似文献
9.
Summary Cytoplasmic cleavage in the gametangia and zoosporangia ofA. macrogynus was studied using monensin, an ionophore known to disrupt several endomembrane functions in plant and animal cells. Monensin interfered with normal gamete and zoospore formation in a dose dependent manner such that at a 20 M concentration very abnormal cells were released from the reproductive structures. It was evident that monensin's effect was most pronounced during the first 25 minutes of gametogenesis and parallels in time the onset and continuation of the cytoplasmic cleavage events. Observations using fluorescence and differential interference contrast microscopy indicated that the ionophore inhibited normal cytoplasmic cleavage resulting in the production of multinucleate cells, many of which had either no flagella or multiple flagella. Transmission electron microscopy showed that the monensin-treated gametangia had many large vacuoles which contained amorphous electron-opaque material. X-ray microprobe analysis demonstrated that the elemental composition of the large vacuoles was identical to that of the dense globular inclusions seen in untreated gametangia, and morphological analysis confirmed the relationship between these endomembrane structures. Thus this swollen endomembrane component probably is not involved in the cleavage process. Single endomembrane cisternae which were very common in untreated gametangia were seldom seen in monensin-treated preparations. Instead, many smaller electron-transparent vacuoles were observed. These swollen cisternae may both represent monensin-modified Golgi apparatus equivalents and/or play a critical role during the process of gametogenesis and zoosporogenesis inA. macrogynus. 相似文献
10.
Abstract The convex shape of the outer end of the cap rays in Acetabularia mediterranea is a typical species specific character, probably determined by a corresponding «morphogenetic substance» of nuclear origin. When cysts differentiate, the outer end of the rays looses its convexity, becoming flat or concave. This phenomenon, which is observed only in laboratory cultures, may be related to a probable fall in the internal pressure of the cell. 相似文献
11.
Gina Purelis Skucas 《American journal of botany》1966,53(10):1006-1011
A study was made of the discharge papillae of zoosporangia (ZS), as well as of resistant sporangia and gametangia, of Allomyces (mainly A. × javanicus). It was found that they differ considerably. The discharge papillae of the resistant sporangia apparently arise by a blister-like modification of the inner wall, whereas those of the ZS and the gametangia consist of a pulley-shaped, refractile plug securely placed in a hole in the wall. This plug can be successfully removed from the ZS wall by treatment with sulfuric acid. Solubility and histochemical tests were used to identify the material of the ZS plugs and the results indicate that the material is a pectic substance, most likely protopectin. The plugs of the gametangia presumably have the same composition. A preliminary study was also made of the discharge papillae of representatives of other families of the aquatic Phycomycetes. The results indicate that such pulley-shaped plugs filling a pore in the wall are characteristic only of the ZS and the gametangia of members of the family Blastocladiaceae to which Allomyces belongs. 相似文献
12.
Peter Fähnrich 《Archives of microbiology》1977,112(3):255-261
Polysomes were isolated both from growing gametophytes of Allomyces arbuscula and from gametangia prepared from mycelia at different periods during gametogenesis. Analysis of polysomes by sucrose gradients showed that ribosomes present in the gametangia monosome pool were shifted into polysomes. This shift was found to be correlated with gametangia differentiation. The ribosome distribution remained virtually unchanged during the early stage of gamete formation. In mature gametes and swarming zygotes a low level of polysomes was detected. Labeling of rRNA by 32PO4 demonstrated a de novo synthesis of monosomes throughout the period of gametangia differentiation. No incorporation of 32PO4 was found to be present in ribosomes prepared from gametangia after onset of gamete formation. On the basis of these labeling experiments it is concluded that radioactivity in polysomes extracted from mature gametes and swarming zygotes can be attributed in part to conserved mRNA.Synchronous formation of gametangia was induced by transferring the vegetative mycelia from growth medium into a low salt buffer. Under these conditions the incorporation of either 32PO4 or 3H-uridine into RNA, particularly into rRNA, was found to be markedly decreased. This obviously indicates a shutdown of RNA synthesis. rRNA from induced mycelia examined by polyacrylamide gel electrophoresis was found to be severely degraded. In contrast to this, rRNA isolated from ribosomes of developing gametangia and from gametes exhibited no degradation products. It is suggested that endonucleases cause rRNA hydrolysis in the hyphal cytoplasm during gametangia differentiation. Ribosomes compartmentalized in gametangia seem to be inaccessible to nucleases during the later process of gametogenesis.
Abkürzungen MAK Methyl-Albumin-Kieselgur - PAA Polyacrylamid - stains all 4,5,4,5-Dibenzo-3,3-diäthyl-9-methylthiacarbocyaninbromid (Serva, Heidelberg) 相似文献
Abkürzungen MAK Methyl-Albumin-Kieselgur - PAA Polyacrylamid - stains all 4,5,4,5-Dibenzo-3,3-diäthyl-9-methylthiacarbocyaninbromid (Serva, Heidelberg) 相似文献
13.
Phenology, morphology, life history and responses to different temperature and photoperiod conditions were studied in Japanese Stypocaulon durum (Ruprecht) Okamura. Erect thalli of the species were collected year-round, but the mature thalli forming either uniloc-ular sporangia or two different types of plurilocular structures (evidently gametangia) on separate thalli were found only in winter. ln culture, an isomorphic life history is suggested for the species, alternating between a sporophyte forming unilocular sporangia and gam-etophytes forming plurilocular macro- (female) and micro- (male) gametangia. Contents of unilocular sporangia were not released, but germinated in situ, developing into erect thalli forming plurilocular gametangia. Macrogametangia released aplanogametes (oospores), but male gametangia appeared to be non-functional, although flagellated cells were once formed in the loc-uli. This is the first report of plurilocular gametangia in the species. Although the species grew well and matured under considerably lower temperature conditions than European Stypocaulon scoparium (L.) Sauvageau, its temperature requirements showed similarity to northwestern Atlantic Stypocaulon species. This supports the notion that northwestern Atlantic Stypocaulon is conspecific with S. durum. 相似文献
14.
Phyllis J. Morrison 《Archives of microbiology》1977,113(3):173-179
The possible role of mitochondria in determining the sex of the gametangia of Allomyces macrogynus was investigated. Quantitative studies of mitochondrial distribution in vegetative hyphae confirmed previous reports of apical mitochondrial clustering. However, by the time the male and female gametangia were partitioned off, no significant difference in mitochondrial distribution between the two sexes was present. Possible mechanisms for the redistribution of mitochondria during early differentiation are discussed. In addition, cytochrome oxidase activity was demonstrated in all mitochondria of both male and female gametangia by the use of diaminobenzidine. It is concluded that neither mitochondrial distribution nor differential mitochondrial activity plays a determining role in the differentiation of the sexual cells in Euallomyces.Abbreviations %M
percent area occupied by mitochondria
- DAB
diaminobenzidine 相似文献
15.
Eva Tigerschiöld 《Nordic Journal of Botany》1989,8(6):639-648
Gametophytes of the fern family Thelypteridaceae were cultivated aseptically under controlled conditions and investigated with the scanning electron microscope. This report concerns six species, viz. Sphaerostephanos arbuscula S. subtruncatus, S. unitus, Macrothelypteris torresiana, Amauropelta hakgalensis and Pneumatopteris truncata . The gametophytes have some features in common. They are more or less heart-shaped and have glandular trichomes on surfaces and margins. In the middle is an elongated cushion bearing gametangia and rhizoids on the lower surface. Antheridia are of the type common to leptosporangiates, consisting of a basal cell, a ring cell and a cap cell. Archegonia consist externally of four rows of cells meeting at the top with triangular cells. The following features are distinguishing. The form of the margin of the thallus, type of hairiness, and the abundance of glandular hairs. Acicular hairs occur in Sphaerostephanos unitus and Pneumatopteris truncata . In Amauropelta hakgalensis the archegonium deviates from the common type in having a basal layer that consists of eight cells instead of four. In Macrothelypteris torresiana the four or three top cells are markedly irregular. In Sphaerostephanos arbuscula and Amauropelta hakgalensis the antheridial cap cell is sometimes divided. The manner of opening of antheridia and release of spermatozoids varies in each of the species investigated. This investigation reveals that it is possible to identify the species from gametophyte characters only. 相似文献
16.
Federico J. Castillo Geneviève Cotton Claire Kevers Hubert Greppin Thomas Gaspar Thérèse Vanden Driessche 《Differentiation; research in biological diversity》1987,33(3):17-23
Abstract. The level of peroxidase activity utilizing ascorbic acid changes during the development of the green alga, Acetabularia mediterranea. During development almost parallel levels of peroxidase activity and ascorbic acid content are detectable: both steadily decrease as algae progress from very young, slowly growing cells to the rapid growth stage and then to cells exhibiting differentiation into primordium and cap. Changes in the levels of the enzyme and its substrate in the cytoplasm and periplasm were demonstrated using biochemical and cytochemical procedures. Concomitant with these developmental changes, we also observed changes in the stage-specific patterns of ascorbic acid concentration: growing algae exhibit a pronounced negative apicobasal gradient of ascorbic acid. Acetabularia cultivated at 1,200 lux (the normal intensity in a 12-h-light/12-h-dark cycle) and at 700 lux (intensity at which growth is reduced, and cap formation is delayed) were also compared. The higher light intensity induced a moderate decrease in the ascorbic acid content without noticeable changes in the compartmental distribution in the cytoplasm and periplasm, and an increase in the level of periplasmic peroxidase activity with little change in the total peroxidase activity. Catalase was found to be present at very low levels and is unlikely to play a role in H2 O2 catabolism. Possible roles for ascorbic acid and peroxidase in the development of Acetabularia are discussed. 相似文献
17.
Accessory copulatory structures in the bursa of Pomphorhynchus bulbocolli include 2 suckers on the inner surface and bursal rays. A stylet was present in the penis of this species. Two suckers were present in the bursa of Acanthocephalus dirus, but bursal rays and a stylet in the penis were not observed. This is the first report of suckers present in the bursas of acanthocephalans. Copulatory cement caps and holes surrounded by a ring approximating the inner bursal diameter and not covered by a cap were present on the sides of some P. bulbocolli, indicating the possibility of hypodermic insemination in this species. 相似文献
18.
Changes in Intracellular Distribution of Thiol Groups During the Development of Acetabularia mediterranea 总被引:1,自引:0,他引:1
LANGENDONCKT ANNE VAN; DRIESSCHE THERESE VANDEN 《Journal of experimental botany》1992,43(12):1643-1650
A cytochemical study of intracellular thiol distribution inAcetabularia mediterranea intact cells was performed using thefluorescent thiol-labelling agent monobromobimane (mBBr). Differentdevelopmental stages were examined during the vegetative phaseand generative phase of the algal life cycle up to cyst maturation.Important changes in thiol localization have been found to coincidewith turning-points ofAcetabularia development. During the rapid growth phase, overall thiol content steadilyincreased along the stalk, being maximal shortly before capdifferentiation. At this stage, the thiol distribution patternparalleled that of cap morphogenesis essential processes: thiolsbeing accumulated at the apex where morphogenesis is going tobe expressed. High thiol contents were also present in the rhizoidal partof the alga throughout the vegetative phase. At the onset ofthe generative phase, important alterations in rhizoid thioldistribution coincided with the presumptive time of nucleardivision. Overall thiol content strongly decreased and thiolsbecame highly concentrated in definite zones localized in thecentral area of the rhizoid. Later on, during the sequence of morphogenetic events leadingto cyst differentiation, changes in thiol localization and relativecontent were observed in the cap rays. Positioning of secondarynuclei into the cap coincided with a high increase in thiolcontent in the entire cap. During the process of cyst formation,thiol content slightly decreased and thiols were localized incyst domains. Thiol distribution was also studied during regenerative processesafter merotomy. A spatio-temporal coincidence was shown withcell wall regeneration. Key words: Acetabularia, thiols, development, bromobimanes 相似文献
19.
Salgueiro Lage Celso Luiz Esquibel Maria Apparecida 《Plant Cell, Tissue and Organ Culture》1997,48(2):77-81
Methylene blue as an alternative treatment to gamma rays to stimulate growth in sweet potato tissue cultures, was applied
in two different ways:
– pre-incubation of nodal explants with methylene blue for 1 h using urea as a permeabilizer;
– methylene blue directly incorporated into the culture medium.
Both treatments stimulated growth, but the better performance being obtained with the second treatment, which had no toxic
effect. The activity and electrophoresis pattern of peroxidase after treatment ofIpomoea batatas plantlets with methylene
blue or gamma rays did not show similar results for the two treatments. Peroxidase activity was greater in leaves of gamma
ray treated plants compared to the non-treated control. The results obtained with the Methylene blue treatment did not significantly
change the peroxidase activity relative to the control.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
20.
《Journal of bryology》2013,35(3):206-215
AbstractOctoblepharum albidum Hedw. is an autoicous moss commonly occurring in tropical savannas, dry forests, rainforests and coastal habitats. It frequently reproduces by spores and asexual structures (gemmae and protonemata or buds at leaf tips), making it a good model for understanding how reproductive traits change with respect to habitat type. Our aims were to characterize the different life-history traits in O. albidum relative to sexual and asexual cycles and to detect variations in reproductive performance among the different habitats, trade-offs among these traits, and relationships among reproductive traits and plant length. We studied colonies from two Atlantic rainforests and two coastal sites in north-eastern Brazil. Shoots in the coastal sites, compared to those of the forest sites, had higher numbers of sporophytes, male and female branches per shoot, male gametangia per sexual branch, and longer setae. Numbers of female gametangia per sexual branch did not differ between forest and coastal sites. A male-biased sex ratio of branches and gametangia occurred in all sites. Compared to gemmae, sporophytes and protonemata or buds were more likely to be found on longer shoots than on shorter ones, but this relationship was only applicable to forest sites. The abundant production of gemmae and protonemata or buds at leaf tips, and sporophytes (spores) in O. albidum are important components in explaining colonization success and maintenance in this tropical moss. Longer sporophytic setae in addition to a higher reproductive performance (especially for number of male gametangia and sporophytes per shoot) may favour spore dispersal and colonization in plants of coastal sites. 相似文献