sponge systematics important for studying evolution and in the search for bioactive compounds....

Sponge Systematics

Important for studying evolution and in the search for bioactive compounds.

Morphology ; Limited to type and structure of skeleton & spicules.

Some focus on cytology, biochemistry & reproduction.

Molecules; DNA (different genes for different relationships.

Sponge Taxonomy

Class Calcarea

• Only sponges that possess spicules composed of calcium carbonate. • Spicules are straight or have 3-4 rays. • Today, their diversity is greatest in the tropics, predominantly in shallow waters•Exclusively marine•all three levels of organisation; asconoid, syconoid and leuconoid.

Why might calcareous sponges be absent from deep ocean environments, while sponges with siliceous spicules inhabit these habitats?

Why are calcareous sponges absent from fresh water?

Taxonomy cont.

Class Hexactinellida

• Glass sponges; characterized by siliceous spicules consisting of six rays intersecting at right angles• Widely viewed as an early branch within the Porifera

•Largely deep sea forms, exclusively marine

•Includes Venus flower basket

•Animal a mixture of cells and blocks of syncytial tissue (not true tissue)

Many biologists think deep water glass sponges are the oldest living animals

What are the advantages of the syncitial nature of hexactinellids for evolution ?

What advantage might syncitial tissues have in terms of spicule formation?

Taxonomy cont.

Class Demospongiae

• Greater than 90 % of the 15,000 known living sponge species are demosponges.

• Demosponge skeletons are composed of spongin fibers and/or siliceous spicules

• Siliceous spicules with one to four rays not at right angles, All members express the leuconoid body form

Why are Demosponges the most abundant and diverse type of sponges?

Morphology

Taken from Kelly-Borges and Pomponi (1994)

Class Demospongia

oviparous

viviparous

Spongosorites suberitoides

Two juvenile Pagurus impressus in hermit crab sponges, Florida

(photo taken from Floyd Sandford’s web page (www.public.coe.edu/departments/Biology/hermit.html)

MORPHOLOGY

Phylogenetic Reconstruction employing maximumparsimony. Bootstrap proportions above each branch arefrom maximum parsimony analysis while those below eachbranch are from distance matrix analysis.

10

Svenza zeai Halichondria sp. Axinyssa ambrosia

Bath sponge 3Bath sponge 3Bath sponge 2

71100

Axinella cateriPolymastia aurantiumSpheciospongia vespariumParahaphoxya sp.

Spirastrella coccineaS.coccinea

60

Topsentia porrectaHymeniacidon sp.

97

Aaptos sp.Spongosorites suberitoides

Suberites sp.77

96

69

55100

8251

94

9967

DNA

McCormack GP, Kelly M. (2002). New indications of the phylogenetic affinity of Spongosoritessuberitoides, Diaz et al., 1993 (Porifera, Demospongiae) as revealed by 28S ribosomal DNA.Journal of Natural History 36:1009-1021.

Order Lithistida

• Traditionally combined within one order due to the common possession of interlocking siliceous desma skeleton.

• Recent evidence suggests polyphyly.

• “...in short, many uncertainties exist in the classification of the lithistids, and the systematics of the group is relatively poorly known..” (Levi, 1991).

Clip

1950s ; Cryptotheca; discovery of spongouridine and spongothymidine led to the discovery of the anti-HIV drug AZT. In fact these compounds can be considered to be the precursor of all nucleoside drugs!!

Discodermia and Theonella produce several secondary metabolites. T. swinholi produces swinholide which shows antifungal and antitumor activities.

Discodermia sp.

A tetraclonal desmas, fungiform zygoses at the ends of the zygomes (Z)

B short-shafted discotriene (D), acanthose microrhabd microscleres(M), oxeas(O)

Theonella sp.

C tetraclonal desmas with zygoses at the ends of the zygomes (Z), strongyles with tylote ends (S), microscleres one size (M)

D short-shafted phyllotriaenes

Corallistes sp.

E dicranoclonal desmas with zygoses along the zygomes.

F long-shafted dichotriene, spined streptaster microscleres

Symbiosponge (1998-2001)

Most diverse, pharmacutically interesting sponges occur on tropical coral reefs….endangered, many not numerically prominent. Practice of collecting and isolating compounds largely indiscriminatory. Yet some evidence suggesting related sponges produced related compounds.

Aims: study relationships between sponges, what compounds were produced. Also a study of endosymbiotic bacteria (thought to actually produce the compounds).

McCormack et al. (2002). J. Zool. Syst.Evol.Res.

DNA

Reconciling molecules and morphology in a definitive phylogeny of the Order

Haplosclerida.

AimProduce a robust phylogeny of the Order Haplosclerida.

Using ≥ 3 loci (18S rDNA, 28S rDNA, mtCox I); ≥140 species

Test ability of gene regions to produce robust phylogeny by comparing different genes.Test ability of morphological methods to reconstruct phylogeny.Compare. Map morphological characters onto gene trees, also chemistry.

IRCSET project grant. 2003-2006

FUTURE WORK

• Focus on Irish sponges; – diversity, – reproduction, – novel compounds– Investigate the microbial diversity within sponges– Investigate the nature of the symbiosis.– Search for interesting genes coding (biosynthetic

pathways, development etc)– Cultivation methods for sponges, symbionts, genes