Bacillariophyta, Kieselalgen

Transcription

1 Bacillariophyta, Kieselalgen

2 general characteris-c

3 mostly marine or freshwater ecosystems planktonic, benthic photoautotrophy, mixotrophy important in primary produc8on symbiosis, parasi8c, toxic single cell, solitary living, colonial common features with heterokonts prac8cal use general characteris-c

4 unique features

5 unique features also in extreme habitats abundant in ecosystems high species diversity siliceous / glass cell wall (shell, frustule) non-flagellar locomo8on diplon8c life cycle diminu8on of cells

6 cell structure

7 cell structure

8 siliceous / glass cell wall (shell, frustule) cell structure

9 cell structure

10 non-flagellar locomo8on - raphe; filamentous centrics cell structure

11 life cycle

12 life cycle diminu8on of cells of popula8ons asexual proces - vegeta8ve cell division

13 life cycle

14 vegeta8ve reproduc8on life cycle

15 life cycle

16 life cycle diplon8c life cycle zoids are only gamets of centric diatoms

17 centric diatoms life cycle

18 centric diatoms life cycle

19 pennate diatoms life cycle

20 pennate diatoms life cycle

21 Detail: Vegeta8ve cells are solitary (Fig. 1). AJer sexualiza8on they pair ac8vely and bond together, side-by-side (Fig. 2). Ini8ally, they look exactly the same as they did during mito8c interphase (Fig. 2). As cells enter meio8c prophase, the protoplast is reorganized through movements of the chloroplast and nucleus (Fig. 3) and the nucleus expands and becomes much more obvious than at any other 8me during the whole life cycle. The cells are now gametangia. Slight further rearrangements of the protoplast (Fig. 4) accompany an unequal cytokinesis at the end of meiosis I. Each gametangium forms a single large gamete (Fig. 4). The thecae split apart locally in the zone where the gametangia are in contact and an aperture is formed between them (note the bulges in this region in Fig. 4). The gamete from one gametangium moves through the aperture into the other gametangium, fusing with the gamete there to form a zygote (Fig. 5), leaving behind a small residual body (Fig. 5, arrow). The donor gametangium (m) can be designated as 'male', the recipient 'female'. The zygote undergoes some internal rearrangement and constructs a special wall to form an 'auxospore', which then expands at both ends to produce an elongate, cigar-shaped cell (Fig. 6), within which a new frustule is formed. Expansion is parallel to the long axis of the female gametangium. The auxospore contains two chloroplasts, one inherited from the male gametangium, the other from the female gametangium.

22 life cycle - centrics - pennates sexual process - auxospores

23 life cycle Euno$a soleirolii Cra$cula res8ng cysts / cells inner frustules

24 systema-cs of diatoms

25 systema-cs of diatoms Williams (2007) in Unravelling the algae

26 systema-cs of diatoms Chromalveolata - Heterokontophyta (Stramenopiles, Ochrophytes) Bacillariophyta ancestor similar to Parmales, the closest rela8ves: Bolidophyceae Tetraparma Bolidomonas Guillou et al. (1999)

27 systema-cs of diatoms CMB hypothesis (Coscino-Medio-Bacillariophyceae) Sorhannus (2007); Sims et al. (2006); Kooistra et Medlin (1996)

28 systema-cs of diatoms Theriot et al. (2009)

29 evolu-on of diatoms

30 evolu-on of diatoms fossil diatoms: the oldest from mesozoic (jurassic 185 and cretaceous 120 mil) marine pennate at the end of cretaceous (70 mil) freshwater pennate from eocene (60 mil) diversified assemblages of diatoms in miocene (24 mil)

31 evolu-on of diatoms molecular clock: origin in permian (267 mil) to jurassic (162 mil) marine radial planktonic ( mil) bi/mul8polar centrics ( mil) araphid pennate (125 mil) raphid pennate (96,5 mil) Sorhannus (2007); Medlin et al. (1997); Simonsen (1979)

32 ecology of diatoms

33 marine phytoplankton ecology

34 ecology - seasonal blooms freshwaters - microhabitats

35 ecology streams freshwaters standing waters

36 habitat adapta8ons ecology

37 ecology Hemiaulus with symbio8c blue-green algae + Epithemia turgida Rhopalodia gibba Rhizosolenia Chaetoceros diatoms as endosymbionts: Foraminifera and Dinoflagellata

38 invasive Didymosphenia geminata ecology

39 toxic diatoms ecology domoic acid ASP amnes8c shellfish poisioning Pseudo-nitzschia

40 mixotrophy without chloroplasts parazi8c diatoms ecology Bevestrello et al. (2000); Hellebust et al. (1997)

41 prac-cal use of diatoms

42 diatomaceous earth prac-cal use

43 prac-cal use complete sequence of genom Thalassiosira pseudonana Phaeodactylum tricornutum

44 prac-cal use biofuel - oil produc8on - e.g.: Chaetoceros muelleri, Fistulifera/Navicula saprophila, Nitzschia communis Chelf (1990); Hellebust et al. (1997); Ben-Amotz et al. (1985)

45 prac-cal use biomonitoring / paleolimnology

46 prac-cal use nanotechnology Losic et al. (2009); Pérez-Cabero et al. (2008)

47 esthe8c images prac-cal use

48 iden-fica-on of diatoms

49 iden-fica-on

50 iden-fica-on

51 iden-fica-on hip://researcharchive.calacademy.org/research/diatoms/names/index.asp

52 iden-fica-on species concepts Amato et al. (2007); Potapova et Hamilton (2007); Mann (1999)

53 iden-fica-on

54 iden-fica-on

55 symmetry iden-fica-on

56 processes iden-fica-on

57 perfora8on iden-fica-on

58 raphe / pseudoraphe iden-fica-on

59 iden-fica-on teratological forms Falasco et al. (2009)

60 representa-ves of diatoms

61 representa-ves Coscinodiscus Thalassiosira

62 representa-ves Ac$noptychus Arachnoidiscus

63 representa-ves Tricera$um Chaetoceros Rhizosolenia

64 representa-ves Hemiaulus Biddulphia Terpsinoe

65 representa-ves Mastogloia Lyrella Diploneis

66 representa-ves Stephanodiscus Cyclotella

67 representa-ves Aulacoseira Melosira

68 representa-ves Tabellaria Asterionella

69 representa-ves Meridion Diatoma

70 representa-ves Staurosira Pseudostaurosira Synedra Fragilaria

71 representa-ves Cocconeis Achnanthidium Planothidium

72 representa-ves Navicula Pinnularia

73 representa-ves Frustulia Cra$cula

74 representa-ves Sellaphora Lu$cola Fistulifera Muelleria

75 representa-ves Neidium Euno$a

76 representa-ves Cymbopleura Cymbella Encyonema

77 representa-ves Gomphonema Didymosphenia

78 representa-ves Nitzschia Surirella

79 representa-ves Epithemia Rhopalodia