Classification and Characters of Oedogonium

Is Oedogonium unicellular or multicellular?

What is the name of the basal cells in Oedogonium?

Is Oedogonium autotrophic or heterotrophic?

What is Macrandrous?

                                    Oedogonium

Classification:-

Phylum – Algae

category – Chlorophyaecae 

Order – Oedogoniales 

Family – Oedogoniaceae

Genius - Oedogonium

Thallus Character:-

Oedogonium

This order is basically a bunch of fresh-water algae.

Members choose to grow in quieter things and shun flowing waters.

They usually occur hooked up by a special stick cell.

The plant body is un-branched (Oedogonium) or branched (Oedocladium, Bulbochaete). Filaments area unit created of organelle, cylindrical cells.

 every cell is larger long than in width and contains a well developed reticulate plastid introduction of several pyrenoids.

cellular division is exclusive. it's in the course of the formation of the cap of cell membrane material.

fruitful structures like zoospores, androspores and male gametes possess a hoop of diverse flagella round the anterior finish. Such a sort of flogging is thought of as stephanokont.

agamogenesis takes place by the formation of multi-flagellate zoospores made individually per zoosporangium.

Species area unit homothallic still as heterothallic.

Thallus:-

The plant part is created of inexperienced, multicellular, unbranched Filaments.

The plant part is split into 3 components :

The lower-most basal cell or constraint.

 The added cells.

 The upper-most top cell.

 Hold Fast:

Oedogonium Thallus

The filament is hooked up by means that of specially differentiated basal cells.

The constraint is found in aquatic species and it seldom happens in terrestrial forms.

. In terrestrial forms, it should offer out fibril like outgrowths.

 The stick or basal the cell is a club formed, broad, spherical in higher half and slim in the lower half.

The lower terminal a part of basal cells is multi-lobed, disc-like or finger formed that attaches the filament to the substrate.

Chloroplasts area unit absent or poorly developed in basal cell thence it doesn't participate in the chemical process.

Intercalary Cells:

All cells of the filament in between the top cell and also the basal cell area unit added cells.

The added cells of filaments have base-apex polarity and this can be maintained even once filaments break and become free-floating.

 All added cells area unit alike, just some cells once division develops cap in higher half. Such cells area unit known as cap cells.

Apical Cell:

The terminal cell of the filament referred to as a top cell. it's spherical or dome formed.

 

 In some species e.g., O. Ciliata, the top cell is tapering and offers rise to slim hair like structure.

The top cell is inexperienced because of chlorophyll and takes half in chemical action.

Cell Structure of Oedogoniales:

The cell's area unit is elongated and cylindrical.

The cell membrane is usually thick, rough and rigid.

 it's created from 3 coaxial layers, the inner polysaccharide, middle pectose and therefore the outer layer is a polysaccharide in nature.

The living substance consists of skinny semipermeable membrane, cytoplasm, central cavity, reticulate plastid and therefore the nucleus.

The center of the cell is occupied by an outsized central cavity that contains the cell sap.

The cell sap contains excretions, secretions, and inorganic compounds.

 

The energid happens as a skinny layer between the central cavity and therefore the inner cell membrane.

The plastid is characteristically reticulate, extending or covering the complete cell and skirting the energid.

 

The strands of the reticulum are also broad or slim relying upon the species. In most of the cases, the strand area unit parallels to the long axis of the cell.

 

Many pyrenoids area unit gifts at the intersections of the reticulum, Pyrenoids area unit coated with starch plates.

There is a single giant nucleus, it's biscuit formed or lentiform and lies within the center of the cell, internal to the plastid.

 The nucleus possesses 1-2 nucleoli, and thread-like or elongated chromosomes.

 

The cell additionally contains mitochondria, histologist bodies, endoplasmic reticulum and therefore the different cell organelles.

Cell Division:

We know that once a cell divides into 2 female offspring cells, 2 separate processes area unit concerned, one is the organic process and therefore the difference is cell elongation together with the cell walls.

 In the organic process the living substance divides, the primary sign of that is that the division of nucleus.

 

In cell elongation, the cell elongates step by step and uniformly.

The method of organic process and growth of the cell membrane is exclusive and peculiar in Oedogonium.

The cell membrane doesn't elongate in the usual manner.

The process of organic process in Oedogonium takes place in following stages:

 

(i) The nucleus from edge moves towards the center and slightly towards the higher a part of the cell 

(ii) Since the wall doesn't elongate within the usual manner, the cytoplasmatic wall material gathers within the style of a “ring” around the inner wall at the higher finish of the cell.

(iii) The nucleus divides mitotically and there's the formation of a groove within the ring.

(iv) the ensuing stage is that the elongation or stretching of the female offspring cells by breaking apart of the wall layers around the groove of the ring.

 The lower cell elongates to the previous level of the ring.

The higher one additionally elongates to an identical extent. the method of elongation is completed at intervals quarter-hour.

 

(v) alongside the completion of elongation, a cross wall formation between the 2 is additionally completed. The distal finish of the higher cell contains a little portion of the recent parent wall that seems because of the top cap.

 

It is evident that the outer wall of the recently divided higher cell with the “cap” springs from the ring except the “cap” that belongs to the recent parent wall, whereas, within the lower cell laterals wall area unit those of the recent parent cell.

 

“Cap cells” sometimes divide repeatedly showing as several caps as there are divisions and therefore the position and variety of such cells during a filament is restricted characters.

 

 The cell divisions area unit usually added and generally terminal.

 

 

Reproduction in Oedogoniales:

The replica in Oedogonium takes place by vegetative, parthenogenetic and sexual strategies.

(i) Vegetative Reproduction:

Vegetative replica takes place by fragmentation and akinete formation.

(A) Fragmentation:

Oedogonium filament breaks into several tiny fragments that have the capability to grow into complete filaments underneath favorable conditions.

Fragmentation takes place because of any of the subsequent reasons:

(a) Accidental breaking of the filaments.

(b) Dying or dehydration of added cells.

(c) The disintegration of added cells because of conversion in sporangia.

(d) Mechanical injury to the filament.

(e) modification within the environmental conditions.

(B) Akinete formation:

The akinetes area unit shaped underneath unfavorable conditions.

 

 Akinetes area unit changed vegetative cells that become swollen, spherical or oval, Venetian red and thick-walled.

 

These area unit made in reserve starch and orange-red colored oil.

Akinetes area unit shaped enchained of ten to forty .(Akinetes germinate directly underneath favorable conditions.

(ii) Parthenogenetic Reproduction:

Asexual reproduction takes place by suggests that of multi-flagellate zoospores created separately in added cap cell.

 principally the recently shaped cap cell functions because of the zoosporangium.

Several factors management spore formation of that high pH scale and CO2concentration of the medium and diurnal rhythm of sunshine and darkness area unit vital.

 

The zoospores don't seem to be shaped enchained and one the sterile cell is often a gift between 2 zoosporangia.

 

The cell that functions as zoosporangium gets crammed with lush reserve food and a small contraction of the energid from the cell membrane takes place.

The central cavity disappears the plastid frees itself from one finish of the cell and becomes conic.

The nucleus involves lie close to this plastid.

 a little lens formed hyaline region is created between the wall and therefore the nucleus. This hyaline bald spot later forms the anterior finish of the spore.

 

At the bottom of this hyaline space a hoop of basal grains seems and from every basal granule or blepharoplasty, a flagellum arises.

The basal granules area unit connected to every different by fibrous strand. A crown of regarding thirty flagella is created round the hyaline spot.

The mature spore is oval, spherical or pear-formed structure.

The spore is uninucleate  and contains a hoop formed plastid.

 The spore is dark inexperienced in color except at the hyaline pointed top finish. A sub-top ring of flagella is a gift and such trouncing is named stephanokontic kind.

When the spore is mature, the wall of the zoosporangium splits close to the top region and therefore the adjacent cell moves apart to create a spot for the liberation of spore.

The mucilage substance is secreted at the bottom of the spore that helps within the liberation of spore.

 The spore comes out of the zoosporangium during a delicate adhesive cyst that presently gets dissolved and therefore the zoospores area unit liberated in water.

Germination of Zoospore:

After liberation, the spore swims for regarding Associate in Nursing hour.

Then it settles and attaches itself to a solid stratum with its anterior finish downwardly.

 when the attachment flagella area unit was withdrawn and it starts elongation.

The lower hyaline half elongates to create fastener and therefore the higher half divides repeatedly to create new filament.

Sexual Reproduction:

The amphimixis in genus Oedogonium is of advanced oogamous kind.

Sexual reproduction is a lot of frequent in still waters than in running water.

The factors influencing amphimixis area unit alkalic medium, deficiency of nutrition, lightweight and dark periods and accrued temperature.

The protoctist genus exhibits sexual dimorphism as a result of the male and therefore the feminine gametes dissent morphologically in addition to physiologically.

 The male gametes area unit made in antheridia and therefore the feminine gametes area unit made in oogonia.

Depending upon the character of antheridia manufacturing plants, genus Oedogonium species area unit of 2 types:

(i) Macrandrous:

If the antheridia area unit made on traditional size plant, genus Oedogonium forms area unit referred to as macrandrous.

Macrandrous species could also be paroicous or dioecian. In paroicous macrandrous species antheridia and oogonia area unit made on a similar plant e.g., O. fragile, O. hirnii, O. kurzii and O. nodulosum.

 In dioecian macrandrous species antheridia and oogonia area unit made on separate male and feminine plants of traditional size.

(ii) Nannandrous:

The female or oogonia bearing plants area unit traditional.

The antheridia area unit made on a special form of tiny or dwarf plants, referred to as Dwarf males or Nannandria.

The dwarf male's area unit shaped by androspores that area unit made in androsporangia.

If androsporangia and oogonia area unit shaped on the same plant, the genus Oedogonium forms area unit referred to as gynandrosporous e.g., O. concatinatum.

 If androsporangia and oogonia area unit shaped on totally different plants, genus Oedogonium forms area unit referred to as idioandrosporous e.g., O. confertum, O. iyengarii and O. setigerum.

According to some algologists, nanoporous species-area unit a lot of primitive.

Antheridia:

(i) In macrandrous forms:

The antheridia develop on traditional filaments, terminal or added in position.

The initial cell which supplies rise to antheridia is named reproductive structure cell.

It is unremarkably a cap cell. The reproductive structure cell divides by transversal division to create associate degree higher smaller cell referred to as reproductive structure and a lower larger cell referred to as sister cell.

The sister cell divides repeatedly to create a row of 2-40 antheridia.

Rarely the antheridia area unit made individually. The antheridia area unit broad, flat, short cylindrical, uninucleate cells.

The contents of associate degree reproductive structure cells divide either longways or transversally into 2.

The two antherozoids area unit positioned side-by-side or one on top of the opposite if divisions area unit longitudinal and transversal severally.

The antherozoids area unit liberated within the same fashion as zoospores .The liberated antherozoids or spermatozoids or sperms area unit pale inexperienced or yellowish green, oval or pear formed.

The antherozoids area unit motile concerning thirty sub-apical flagella gift at the bottom of beak or hyaline spot .

The flagella area unit typically longer than the body of gamete e.g., in O. crassum and O. kurzii.

 The antherozoids swim freely in water before they reach oogonia and participate in fertilization. The antherozoids area unit kind of like zoospores in structure however these area unit smaller than zoospores.

(ii) In nannandrous forms:

The antheridia area unit shaped on short or dwarf male plants referred to as dwarf males or nannandria .The dwarf male filament is made by the germination of a special form of reproductive structure referred to as androspore.

The associate degreedrospore is made individually inside an androsporangium.

 Androporangia area unit a lot of or less similar trying to the antheridia of macrandrous forms and area unit made in an exceedingly similar manner from a cell .

The androsporangia area unit flat, discoidal cells slightly larger than antheridia.

Each androsporangium produces one androspore even as within the case of spore. 

Liberation of androspore is analogous thereto of a spore.

 The androspores look kind of like spore apart from the smaller size. The androspores area unit motile and have a subpolar ring of flagella.

After swimming concerning for a few time, the androspore settles on oogonial wall e.g., O. ciliatum or on the supporting cell e.g., O. concatenatum. 

The androspore germinates into a dwarf male or nannandrium. Germlings at one celled stage could divide and turn out 2 antherozoids e.g., O. deplandrum, O. perspicuum .

The nannandrium or dwarf male may be a number of cells long. it's a basal attaching cell the stem and every one others cells area unit reproductive structure cells.

 In several cases cap is gift at the highest of the top reproductive structure.

The living substance of every reproductive structure cell divides to create 2 sperms or antherozoids that area unit kind of like antherozoids of macrandrous species.

The reproductive structure of nannandrium produces single gamete. The antherozoids area unit free by disorganization of reproductive structure cell or through the gap.

 Pascher thought-about the nanandrous forms as primitive and macrandrous as specialised however an oversized range of phycologists contemplate that nannandrous species are evolved from macrandrous species.

Oogonia:

In genus Oedogonium {the feminine|the feminine} reproductive organ oogonia area unit extremely differentiated female gametangia. These area unit largely added however typically may be terminal e.g., O. palaiense.

The structure and development of oogonium is identical in macrandrous and nannandrous species. Like antheridia any freely divided or actively growing cap cell functions because the oogonial cell. The oogonial cell divides by transversal division into 2 unequal cells, the higher cell and therefore the lower cell.

The higher larger cell forms oogonium and therefore the lower smaller cell perform as supporting cell or suffultory cell. In some species the oogonial mother cells directly forms the oogonium.

Supporting cell is absent is O. americanum. If any of the 2 divided cells once more functions as oogonial cell several oogonia area unit shaped in chain.

In paroicous species the suffultory cell could divide to create antheridia. The higher cell contains a lot of protoplasm, food and enlarges into spherical or flask formed oogonium.

The oogonium additionally secretes growth hormones that induce suffultory cell to extend in size.

The energid in oogonium metamorphosis’s into one egg or gamete. The gamete is non-motile, inexperienced because of pigment and encompasses a central nucleus.

 because the egg cell matures, the nucleus moves to outer boundary, the gamete retracts slightly from the oogonial wall and develops a hyaline or receptive spot simply outside the nucleus.

The receptive spot receives antherozoids for fertilization.

At receptive spot a pore is created by gelatinization of inclose proliferous species and a transversal slit is created in plate species.

 In each species a skinny membrane is deposited on the inner node of the exit that functions as a channel leading right down to egg cell.

In some species a mucilage drop is extruded through gap to draw in antherozoids.

In macrandrous paroicous species, wherever antheridia and oogonia develop on a similar plant, the genus Oedogonium species area unit protogynous i.e., the event of oogonia takes place before development of antheridia to make sure cross-fertilization.

Fertilization:

The mature egg secretes chemical substance or mucilage to draw in antherozoids or the antherozoids could enter oogonium through the slit.

 The antherozoids swim through the gap of oogonial wall and enter the egg through hyaline receptive spot . just one male gamete is ready to fuse with egg cell.

After plasmogamy and karyogamy the male nucleus and feminine nucleus fuse to create a diploid fertilized ovum nucleus.

The fertilized ovum secretes a thick wall around itself and forms spore. the color of the spore changes from inexperienced to sepia.

 The spore is liberated by the disintegration of oogonial wall.

Germination of oospore:

Oospore could be a resting reproductive structure however typically it will germinate directly.

The period of rest for spore could also be a year or a lot of.

The fertilized ovum could need chilling before germination.

 The diploid spore nucleus undergoes cell meiosis to create four haploid nuclei before germination.

The diploid spore divides to create four haploid female offspring protoplasts.

 every female offspring energid metamorphosis into a spore additionally referred to as as zoomeiospore.

The zoomeiospores area unit liberated in an exceedingly cyst . before long the cyst disappears and as in reproduction the zoospores develop to form genus Oedogonium plants.

In some cases out of 4 nuclei a number of could degenerate forming but four zoomeiospores.

In heterothallic forms e.g., O. plagiostomum, 2 swarmer’s create to male and therefore the 2 swarmer’s create to feminine plants.

Under bound conditions meioaplanospores area unit shaped rather than zoomeiospores

Life Cycle :-

Macrandrous Forms:

Oedogonium macrandrous species may be paroicous or homothallic, if antheridia and oogonia area unit made on same filament.

Oedogonium macrandrous species may be dioecian or heterothallic if antheridia area unit made on male plants and oogonia area unit made on separate feminine plants.