(i) The family Ectocarpaceae is characterized by simple, heterotrichous thalli. 2; [ 10, 15 ]). Our mission is to provide an online platform to help students to share notes in Biology. During fertilisation, many male gametes encircle the female gamete and get entangled by the anterior large flagellum. It is much branched and well-developed. The nuclear divisions are not followed by wall formation and the sporangium remains unilocular (Fig. The diploid nucleus of the initial first undergoes meiosis followed by several mitotic divisions, thus 32-64 hapioid nuclei are formed. Haplodiplontic cycle is the life cycle which is intermediate between haplontic and diplontic. Sexual reproduction may be isogamous, anisogamous or oogamous type. The medium sized meso-gametangia give rise to medium size gametes. 63 The filamentous alga Ectocarpus is being used as a model system to study brown algal 1) haplontic, diplontic. refractus (Kiitz.) They are large, elongated, sessile or short stalked, multicellular structures (Fig. from Roscoff , France, has been studied in culture. E. siliculosus produces unilocular sporangia at 13°C, plurilocular at 19°C and both unilocular and plurilocular at 16°C. The zoospores discharge en-masse in gelatinous matrix through a terminal pore in sporangium. from Roscoff , France, has been studied in culture. The zoospores formed from plurilocular sporangia are alike with the zoospores i.e., zoomeiospores developed in unilocular sporangia but are diploid. The zygospore germinates after 2-3 days. (With Methods)| Industrial Microbiology, How is Cheese Made Step by Step: Principles, Production and Process, Enzyme Production and Purification: Extraction & Separation Methods | Industrial Microbiology, Fermentation of Olives: Process, Control, Problems, Abnormalities and Developments, The best answers are voted up and rise to the top. Features 5. Species like E. spongiosus and E. conigerare are free-floating, E. breviarticulatus and E. coniferus grow on larger algae like Laminaria and Fucus as epiphytes. ). The life history of Ectocarpus fasciculatus var. Gametophytes are dioecious, producing either male or female gametes, which fuse to produce Ectocarpus arabicus, E. filife, E. enhali, E. coniger, E. zeylanicus, E. rhodochortonoides etc. Name the types of nitrogenous bases present in the RNA. refractus (Kiitz.) 3A) enlarges in size and becomes spherical or elongated structure. The zygote undergoes germination without any reduction division and rest. Ectocarpus is found attached on sea rocks. The life history of Ectocarpus fasciculatus var. Hence the reproduction is isogamous but physiologically anisogamous. 4) haplodiplontic, haplontic from Roscoff , France, has been studied in culture. 1C). 3.113B). The apical cell enlarges and functions as sporangial initial. Life Cycle of Ectocarpus: The sexual thalli of Ectocarpus are haploid. The protcplast contains one central nucleus and many chromatophores. The Ectocarpus Life Cycle . Ectocarpus included its small size, the fact that the entire life cycle can be completed relatively rapidly (3 mo) in the laboratory (Müller et al. from Roscoff , France, has been studied in culture. The life history of Ectocarpus fasciculatus var. Ardis. Like unilocular sporangia, the plurilocular sporangia also develop from the terminal cells of the branchlets of diploid sporophytic plant. E. fasciculatus is epizoic species growing on fins of faster. Gametes (right side) released from WT male gametophytes . The haploid plants bear plurilocular gametangia. 2 A). (ii) The thallus mostly shows heterotrichous habit with prostrate creeping disc holdfast and monosiphonous filament making erect system. Majority of the species show physiological anisogamy (Fritsch, 1945), but morphological anisogamy is observed in E. secundus. Privacy Policy3. They are commonly available in both tropical and temperate seas. 2. Our field data invalidated, however, the long‐standing view of an isomorphic alternation of generations. Most of the Ectocarpus species are anisogamous. (ii) The sexual reproduction is isogamous. 4) haplodiplontic, haplontic Sexual Reproduction . 2) diplontic, haplodiplontic. In Ectocarpus the sporophytic and gametophytic plants are morphologically similar hence there is isomorphic alternation of generation (Figs. Ectocarpus exhibits an alternating heteromorphic type of sexual life cycle with isomorphic alternation of generation (Fig. Different species of the genus Ectocarpus (Cr. refractus (Kiitz.) Ec32 has been established as a genomic model for brown algae. 3.113C). This website includes study notes, research papers, essays, articles and other allied information submitted by visitors like YOU. The largest mega-gametangia represent oogonia and the smallest micro-gametangia represent antheridia (Fig. 60 bodyplans [2]. They do not fuse but develop new plant parthenogenetically. Gametes (right side) released from WT male gametophytes . The zoospores remain motile for 4-5 hours and then germinate into diploid thallus which later on bears unilocular and plurilocular sporangia. The zoospores remain motile for hours and then germinate into diploid thallus which later on bears unilocular and plurilocular sporangia. refractus (Kiitz.) Ectocarpus life cycle. 1 B). Some species of Ectocarpus are epiphytic e.g., E. coniferus, and E. breviarticulatus grow on larger algae like Fucus and Laminaria. These life cycles imply complex regulation of chromatin but, at present, very 61 little is known about the role of histone PTMs, for example, in the regulation of developmental 62 and life cycle processes in the brown algae. This is the difference between unilocular and plurilocular sporangia. Ectocarpus. Anisogamy may be of two types : morphological anisogamy (E. secundus) and physiological anisogamy (E. siliculosus). Both Ectocarpus sexual and asexual life cycles are displayed. Ectocarpus reproduces by both asexual and sexual methods. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. Reproductive Structures of Ectocarpus | Algae, Modes of Reproduction in Ectocarpus (404 Words), Chara: Occurrence, Features and Reproduction. The protoplast of each cubical cell in gametangium metamorphosis into single biflagellate pyriform gamete. Welcome to BiologyDiscussion! ), in the unilocular (single-chambered) sporangia. Within short time a germ tube is formed, which divides many times and form prostrate filament (Fig. Gametes (right side) released from WT male gametophytes . Gametes (right side) released from WT male gametophytes . What is the significance of photosynthesis? Physiological anisogamy is very common. These plants are called gametophytic plants as on maturity they bear plurilocular gametangia. 3.111 A). Life history of Ectocarpus in culture. Ardis. (iv) The asexual reproduction takes place by zoospores formed in unilocular and plurilocular sporangia. The unilocular zoosporangia form haploid zoospores and the plurilocular sprogania form diploid zoospores. The diploid plant (2n) develops two types of sporangia. (a) Haplontic, ... ) Haplodiplontic, Diplontic (d) Haplodiplontic, Halplontic Reproduction 7. Life Cycle. The life history of Ectocarpus fasciculatus var. 4. Gametes (right side) released from WT male gametophytes . The unilocular sporangia develop haploid zoospores i.e., zoomeiospores, but the plurilocular sporangia develop diploid zoospores. Which organelle is known as “power house” of the cell? 7. The gametes are biflagellate, motile and are produced in plurilocular gametangia borne on haploid or unisexual plants. In E. padinae three distinct types of plurilocular gametangia are formed. the haploid gametophyte generation. This stage is called clump formation (Fig. The gametes are produced in many-celled, elongated, sessile or shortly stalked, conical structures called plurilocular gametangia produced on haploid plants developing from the meiozoospores. the sexual pheromones and infection of Ectocarpus by viruses. Ardis. 3.11 OF). The life history of Ectocarpus fasciculatus var. It is abundantly found throughout the world in cold waters. Ardis. (iii) The growth is trichothallic and the cell divisions are intercalary. They germinate to produce new diploid sporophytic plant. Life cycle of Ectocarpus siliculosus. The type species for the genus is Ectocarpus siliculosus (Dillwyn) Lyngbye. The flagella are unequal and laterally inserted. The sexual thalli of Ectocarpus are haploid. Watch Queue Queue. This typical life cycle of Ectocarpus exhibits morpholigically identical filaments representing sporophyte and gametophyte—isomorphic alternation of generations. Some species like E. filiferetc, develop multicellular hairs from the prostrate system. Oogamy is absent. 3.11 OB, D). The two generations of the Ectocarpus life cycle exhibit radically different patterns of early development. 3D-F). Both generations consist of uniseriate, branched filaments, but there are some morphological differences between the two generations [ 15, 16 ]. The mature zoospores are liberated from the sporangium through apical or lateral pores. Skip navigation Sign in. Cell Structure 5. The life history of Ectocarpus fasciculatus var. The growth in the prostrate system is apical and in the erect system it is diffuse and intercalary. Morphologically similar multicellular gametophyte and sporophyte generations are easy to identify in cultures under laboratory conditions, where the gametophytes are free floating and sporophytes form compact thalli that are attached to the substratum. In some species one of the two systems may be reduced. refractus (Kiitz.) What is its function? There is no reduction division during the formation of zoospore in plurilocular sporangium. ... Ectocarpus sp. Its diploid nucleus divides mitotically to make diploid Ectocarpus plant. Gametes (right side) released from WT male gametophytes . Ec32 has been established as a genomic model for brown algae. ... life cycle features, and stress tolerance mechanisms. Share Your PPT File. These are unilocular sporangia and pleurilocular or neutral sporangia (Fig. from Roscoff , France, has been studied in culture. In many species of Ectocarpus, the thallus is sparingly to profusely branched, the cells are uniseriate, joined end to end in a row. The sporophytic diploid plant forms two types of sporangia: These two types of zoosporangia may be produced on the same plant or on different plants. The life history of Ectocarpus fasciculatus var. Asexual reproduction. Life Cycle of Ectocarpus. 3.111 B-D). Ectocarpus is word-wide in distribution particulary in colder seas and Polar Regions. These are unilocular sporangia and pleurilocular or neutral sporangia (Fig. The cells are rectangular or cylindrical Fig. Though both are morphologically more or less alike, the gametes are slightly smaller in size than the zoospores. Disclaimer Copyright, Share Your Knowledge The cells are arranged in vertical row (Fig. A large number of male gametes are attracted and cluster around female gamete to make clump formation (Fig. These zoospores are produced in unilocular and plurilocular sporangia (Fig. Ardis. 3.11 OA, B). Ectocarpus is a small, filamentous alga that exhibits limited levels of sexual dimorphism, male and female individuals of the sexual phase of its haploid–diploid life cycle, the gametophyte, are morphologically similar organisms and both produce small flagellated gametes (Luthringer et al. In physiologically anisogamous species, gametes from two filaments of different strains fuse. 1. This typical life cycle of Ectocarpus exhibits morpholigically identical filaments representing sporophyte and gametophyte—isomorphic alternation of generations. refractus (Kiitz.) refractus (Kiitz.) 3.112C, D). To enable functional studies of brown algae, strain Ec32 of the small filamentous alga Ectocarpus sp. 60 bodyplans [2]. These zoospores may be haploid produced in one-celled unilocular sporangia. Plant body … requires two different three amino acid loop extension homeodomain transcription factors The prostrate system serves the function of anchorage with the substratum or on other plants and the erect system is photosynthetic and bears reproductive organs. What is a mushroom shaped gland? refractus (Kiitz.) Life cycle of Ectocarpus siliculosus. Gametes (right side) released from WT male gametophytes . 3.112). The sporophytic plant again develops unilocular and plurilocular sporangia. So, each small cubical cells of plurilocular sporangium contains single diploid nucleus. The erect system develops from the prostrate system which remains free-floating. Both haploid and diploid plants are morphogically identical (Fig. Share Your PDF File Some cells of the prostrate filament become active and form erect filaments. (iii) The alternation of generation is isomorphic. The plurilocular gametangia are either sessile or stalked and vary in shape from ovate to siliquose. refractus (Kiitz.) Ectocarpus Life Cycle and Reproduction. The haploid plants bear plurilocular gametangia. The cytoplasm contains many vacuoles, which are called physodes. 5. The number and shape of chromatophore varies with species. The life history of Ectocarpus fasciculatus var. from Roscoff , France, has been studied in culture. Morphologically more or less alike, the zoospore withdraws its flagella and attach to the wall cell. Secretes a volatile sexual attractant sirenine majority of the cell which functions as sporangial initial becomes enlarged and undergoes mitotic. 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Is being used as a model system to study about these reproductive structures in order to and! To chlorophyll the apex of sporangium produces zoospores ( i.e., zoomeiospores, but there are some morphological differences the!, acronematic and directed backward ( Fig alternating heteromorphic type of sexual life cycle growth.
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