INTRODUCTION ALGAL CHARACTERISTIC AND DIVERSITY LECTURE 2

1. INTRODUCTION ALGAL CHARACTERISTIC AND DIVERSITY LECTURE 2

2. Algae includes…. · Cryptophytes · Prymensiophytes (Haptophytes) · Dinophytes (Dinoflagellates) · Introduction to the Ochrophytes · Diatoms · Raphidophytes and Chrysophyceans · Synurophyceans, silicoflagellates, pedinelids, tribophyceans · Phaeophytes (Brown algae) · Rhodophytes (Red algae) · Introduction to the Green algae · Prasinophyceans · Ulvophyceans · Trebouxiophyceans · Chlorophyceans · Charophyceans · Ecology of macroalgae and periphyton · Introduction to phycology · Basics of algal biology · Reproduction in algae · The role of algae in biogeochemistry · Algae in biological associations · The role of algae in aquatic food webs · Taxonomy and Systematics of Algae · Phytoplankton size in ecology · The physical environment: temperature, light, turbulence · Growth of phytoplankton · Losses of phytoplankton · Swimming and bouyancy · Cyanobacteria · The origin of eukaryotic algae · Euglenophytes

3. INTRODUCTION TO ALGAL CHARACTERISTICS AND DIVERSITY PHYCOLOGY=STUDY OF ALGAE Phycology is the science (gr. logos) of algae (gr. phycos). This discipline deals with the morphology, taxonomy, phylogeny, biology, and ecology of algae in all ecosystems

4. FOSSIL HISTORY OF ALGAE • 3.5 billion yrs ago • Cyanobacteria—first algae • Prokaryotes—lack membrane bound organelles • Later eukaryotes evolved—mitochondria, chloroplasts, and chromosomes containing DNA.

5. Where are algae abound? • Kelp  forest up to 50 m height are the marine equivalent to terrestrial forest; mainly built by brown algae. • Some algae encrust with carbonate, building reef-like structures; Cyanobacteria can from rock-like structures in warm tidal areas: stromatolites.

6. Where are algae abound? • Algae grow or are attached to animals and serve as camouflage for the animal • Algae live as symbionts in animals such as Hydra, corals, or the protozoan ciliate Paramecium; in corals they are referred to as zooxanthellae

7. Where are algae abound? • Small algae live on top of larger algae: epiphyton • Algae in free water: phytoplankton • Terrestrial algae • Algae have adapted to life on land and occur as cryptobiotic  crusts in desert and grassland soils or endocryptolithis algae in rocks 

8. Where are algae abound? • Algae live on the snow cover of glaciers and in the brine channels of sea ice. • A symbiosis of algae and fungi produced the lichens, which are pioneer plants, help convert rock into soil by excreting acids, stabilize desert soil, are sensitive to air pollution

9. Where are algae abound? • Algae can cover trees or buildings green or live in the hollow hairs of ice bears

10. Algal Blooms • Algae can be so dominant that they discolor the water  • Higher amounts of nutrients are usually the cause • Algal blooms can have harmful effects on life and ecosystem: • Reduced water clarity causes benthic communities to die off • Fish kills are common effects • 50% of algal blooms produce toxins harmful to other organisms, including humans • Algal blooms produce a shift in food web structure and species composition • Algal blooms can mostly be linked to sewage input or agricultural activities, leading to nutrient pollution: Eutrophication

12. Summery of the lecture one • We can find Algae in different Size (from some microns to more than 60 meters) • We can find Algae in different region (soil, water, animal , plants … etc) • Some of algae are prokaryotes and others are eukaryotes.

13. Summery of the lecture one • In the aquatic ecosystems we can find algae as : • Attachment: • Epipelic / on the clay • Epipzamic / on the sand • Epilithic / on the rocks. • Epiphytic / on the plants • Epizoic / on the animals • Endozoic / in the animals body • Endophytic / in the plants body • As Plankton: • Euphytoplankton / all the life cycle is plankton • Tychophytoplankton / some of the life cycle is plankton

14. Summery of the lecture one • According to environments we can subdivided Algae in to : • Halophyts: in region with high salinity. • Thermophyts: in region with high temperature. • Cryptophyts: in the region with low temperature. • In the trrastrial environments we can classified Algae in to : • Lithophyts • Epidaphics • Endodaphics • Casmolithics

15. ALGAE • How are algae similar to higher plants? • How are algae different from higher plants?

16. Similarities • Presence of cell wall—mostly cellulosic. • Autotrophs/Primary producers—carry out photosynthesis • Presence of chlorophyll a

17. Differences • Algae lack the roots, stems, leaves, and other structures typical of true plants. • Algae do not have vascular tissues—non vascular plants • Algae do not form embryos within protective coverings—all cells are fertile. • Variations in pigments. • Variations in cell structure—unicellular, colonial and multicellular forms.

18. PROKARYOTIC VS EUKARYOTIC ALGAE Prokaryotes ---No nuclear region and complex organelles—chloroplasts, mitochondria, golgi bodies, and endoplasmic reticula. -- Cyanobacteria. Chlorophylls are on internal membranes of flattened vesicles called thylakoids-contain photosynthetic pigments. Phycobiliproteins occur in granular structures called phycobilisomes. • Prokaryote algal cell Source: http://www.botany.hawaii.edu/faculty/webb/BOT311/Cyanobacteria/Cyanobacteria.htm

19. Prokaryotic and Eukaryotic Algae • Eukaryotes ---Distinct chlorplast, nuclear region and complex organelles. --- Thylakoids are grouped into grana pyrenoids are centers of carbon dioxide fixation within the chloroplasts of algae and hornworts. Pyrenoids are not membrane-bound organelles, but specialized areas of the plastid that contain high levels of ribulose-1,5-bisphosphate carboxylase/oxygenase granum with a Stack of thylakoids pyrenoid

20. Forms of Algae • BODY OF AN ALGA=THALLUS • DIVERSITY IN MORPHOLOGY ----MICROSCOPIC Unicellular, Colonial and Filamentous forms. Source: http://images.google.com/images

21. Forms of Algae MACROALGAE

22. Forms of Algae MICRO ALGAE

23. Forms of Algae • Unicells: single cells, motile with flagellate (like Chlamydomonas and Euglena) or nonmotile (like Diatoms)

24. 2. Multicellular form: the vegetation forms are in six forms: • Colonies: • Assemblage of individual cells with variable or constant number of cells that remain constant throughout the colony life in mucilaginous matrix (containing an extracellular matrix made of a gelatinous glycoprotein), these colonies may be motile (like Volvox and Pandorina) or nonmotile (like Scendesmus and Pediastrum).

25. Coenobium: Colony with constant number of cells, which cannot survive alone; specific „tasks“ among groups of cells is common (is a colony containing a fixed number of cells, with little or no specialization)

26. b. Aggregations: is aggregation of cells that have ability to simple division (so, its colony but unconstant in form and size), the aggregations are in several types: • Palmelloid form: non-motile cells embedded in mucilage (like Tetraspora).

27. Dendroid form: resembling a tree in form or in pattern of growth (Dinobryon).

28. Amoeboid or Rhizopodial form such as Chlorarachnion.

29. c. Filaments: daughter cells remain attached after cell division and form a cell chain; adjacent cells share cell wall (distinguish them from linear colonies!); maybe unbranched (uniseriate such as Zygnema and Ulthrix) or branched (regular mutiseriate such as Cladophora or unregulermutiseriate such as Pithophora). Cladophora Pithophora

30. d. Coenocytic or siphonaceaousforms: one large, multinucleate cell without cross walls such as Vaucheria

31. e. Parenchymatous (such as Ulva ) and algae: mostly macro-scopic algae with tissue of undifferentiated cells and growth originating from a meristem with cell division in three dimensions

32. ; pseudoparenchymatous (such as Batrachospermum) pseudoparenchymatous superficially resemble parenchyma but are composed of apprised filaments

33. f. Erect thallus forms: Thallus, from LatinizedGreek (thallos), meaning a green shoot or twig, is an undifferentiated vegetative tissue (leaves, roots, and stems) of some non-mobile organisms such as Chara and Nitella. Chara

34. CELLULAR ORGANIZATION • Flagella=organs of locomotion. • Chloroplast=site of photosynthesis. Thylakoids are present in the chloroplast. The pigments are present in the thylakoids. • Pyrenoid-structure associated with chloroplast. Contains ribulose-1,5-bisphosphate Carboxylase, proteins and carbohydrates. • Eye-spot=part of chloroplast. Directs the cell towards light. Source: A Biology of the Algae By Philip Sze, third edition, WCB MCGraw-Hill

35. Variations in the pigment constitution • Chlorophylls (green) • Carotenoids (brown, yellow or red) • Phycobilins (red pigment-phycoerythrin blue pigment –phycocyanin)

36. Summery of lecture two: Forms of algae Multicellular Unicellular • Colonies • 2. Aggregations • Palmelloid (Tetraspora) • Dendroid (Dinobryon) • Amoeboid (Chlororachnion) • 3.Filaments • 4. Coenocytic / Vaucheria • 5.Parenkematus/ Ulva • 6. Psedoparenkematus/ Batrachospermum • 7. Erect thallus / Chara Non motile(Chlorella) Motile (Euglena)

37. Growth in algae • Diffuse or generalized growth: (Ulva). • Localized growth: • Apical growth: (Chara, Cladophora). • Basal growth: (Bulbochaete). • Intercalary growth: (Laminaria, Oedogonium). • Trichothallic growth: (Ectocarpus)

38. Growth in algae Apical and intercalary Tricothallic

39. Reproduction in algae The reproduction of algae can be discussed under two types, namely, asexual reproduction and sexual reproduction. The former type refers to reproduction in which a new organism is generated from a single parent. In case of sexual type, two haploid sex cells are fused to form a diploid zygote that develops into an organism. Let's discuss in brief about the asexual and sexual reproduction in algae along with examples.

40. First: Asexual Reproduction includes: • 1. Vegetation reproduction: • In unicellular algae: simple cell division some time called binary fission (such as Gleocapsa). • In multicellular (colonies, filamentous, thallus, etc) by: • Fragmentation such as Microsystis. • Hormogonia: A small, motile filament, formed by some Cyanobacteria, that detaches and grows by cell division into a new filament such as Oscillatoria. • Propagules: a structure capable of producing a new individual such as Sphacelaria.

41. Vegetative reproduction Cell Division A cell could not keep growing bigger forever. Food molecules could not reach the inside of a large cell fast enough to keep it alive. So when a cell reached a certain size it had to divide into two smaller cells called daughters. The daughters grew and, when they reached that certain size, they too divided, this processes called binary fission.

42. Vegetative reproduction Hormogonia in Oscillatoria

43. Vegetative reproduction Propagules

44. 2. Another method of asexual reproduction in algae is by formation of spores; the algal species Ulothrix, Chlamydomonas and Chlorella reproduce by this method. Depending upon the algal species, the spores can be produced in normal vegetative cells or specialized cells called sporangia. They are either motile called zoo spores or non motile called akinete spores.

45. Ulotrix

46. There are a lot of types of akinete spores such as: • Autospores: immobile spores that cannot develop flagella such as Chlorella. • Aplanospores: immobile spores that may nevertheless potentially grow flagella. • Hypnospores: A thick-walled resting cyst. • Tetraspores: spores produced by a tetrasporophyte, characteristic of red algae. • Statospores: spores that are not actively discharged from the algal fruiting body • Auxospores: A spore in diatom algae that leads to reformation of an enlarged vegetative cell.

47. Second: Sexual Reproduction: As already mentioned, sexual reproduction takes place by the union of male and female gametes. The gametes may be identical in shape and size called isogamy or different called heterogamy. Some of the simplest forms of algae like Spirogyra reproduce by the conjugation method of sexual reproduction. In the process of conjugation, two filamentous strands (or two organisms) of the same algae species exchange genetic material through the conjugation tube. Among two strands, one acts as a donor and another serves as a receiver. After exchanging the genetic material, two strands separate from each other. The receiver then give rise to a diploid organism.

48. Second: Sexual Reproduction: Isogamy: is the form of sexual reproduction in which the gametes produced are identical in shape, size and motility. There is no structural distinction between "male" and "female" gametes. Pairs of isogametes align themselves with their flagellar poles touching and after several seconds, the motile gametes fuse to form a single, non-motile, diploid zygote.

49. Second: Sexual Reproduction: Isogametes, less commonly, may be non-motile structures. A specific example exhibiting non-motile isogametes is the reproductive process known as conjugation, in Figure below, the conjugating Spirogyra identify the four stages of the process as outlined. Isogamy in Spirogyra sp.

50. A. Resting filaments of alga cells. B. Formation of conjugation tubes between two adjacent filaments. C. Cytoplasmic contents of each cell form a compact mass, representing an isogamete. The isogametes from one filament migrate through the conjugation tubes into the adjacent filament. The two isogametes unite to form a zygote. Each zygote eventually undergoes meiosis to form four haploid cells. One haploid cell will form a new filament by mitosis, the other three degenerate.