Current Biology Interviews John Bonner

Current Biology has an excellent interview with John Bonner, a Princeton professor emeritus who was a pioneer in the study of cellular slime molds. I like his answer to the following question. It shows a sense of humor.

"Do you have any views on ethics? My views on ethics are based on common sense, not dogma. I have always been fascinated by the continuing discussion of when human life begins. No one seems to mention that life began billions of years ago and has been going strong ever since. I sympathize with the need to treat animals in experiments in the most humane way, but this is a matter that really does not arise in my own work. In fact when I cut up and make grafts on slime mold slugs I do not think of myself as torturing them — a sort of slime mold Doctor Moreau. But maybe I am underestimating their sensibilities."

Bonner also laments on how scientific papers are written today when he reveals that his favorite paper was from 1923:

"Do you have a favorite paper? Yes. G.P. Bidder, The relation of the form of a sponge to its currents (Quart. J. Micr. Sci. 67, 293–323. 1923!). Not only did Bidder do some ingenious experiments on sponge hydrodynamics, but he wrote them up in an exemplary fashion. He wrote the paper in a way that, alas, would no longer be possible in a journal today."

Spongefest '07

Image from BIODIDAC

The answer’s fairly simple: Sponges feed like Protozoa,
And haven’t any enteron like other Metazoa;
Their ‘gastral cells’ are clusters of primaeval Collared Monads,
And their bodies have no traces of muscles, nerves or gonads.
Even their eggs are products of choanocyte divisions,
And therefore carry with them Choanoflagellate traditions:
Flagellate or Amoeboid, with collars or without,
They still are Collared Monads—though certainly more stout.

Walter Garstang (1985) - The Amphiblastula and the origin of sponges in Larval Forms and Other Zoological Verses (University of Chicago Press).

The latest of the the Journal of the Marine Biological Association of the United Kingdom (JMBA) is entirely dedicated to sponges. I believe this is a rather historic event, I doubt if ever before there have been so many Porifera publications (44 articles, 437 pages) in one place at one time. I think every sponge biologist in the world is an author or coauthor here. According to Van Soest's introduction to the special sponge issue:

It is proper and fitting that the Marine Biological Association of the United Kingdom comes forward with a special volume in its Journal covering these various sponge efforts. Right from the start of the Association, way back in 1884, and up to the present, the Journal has published sponge papers on a regular basis. Sponge fisheries and sponge culture were subjects addressed repeatedly in the earlier volumes of the Journal by E. Allen, the first secretary of the Association (1896), G.P. Bidder (1896, 1902) and L.R. Crawshay (1915, 1939). Sponge epigones such as A. Dendy and M. Burton discussed taxonomy, faunistics and ecology in the Journal and contributed to the authorative Plymouth Marine Fauna (e.g. Burton, 1957). Continuing along these lines, the volume presented here unites a series of 43 articles covering a wide range of sponge biodiversity studies, without pretending to delimit past or future eras of sponge research. As such it provides an overview of current sponge biodiversity research at this moment in time, and with 21 nationalities involved demonstrates the strongly international nature of sponge diversity science.

And just in case you forgot how cool sponges are and how they are so important, Van Soest opens the whole shebang with:

Sponges are an integral part of marine benthic communities with a high-impact role in benthic–pelagic coupling processes, as an important source of food for demersal grazers and predators, as hosts of a highly diverse microbial biomass, and as bio-eroders. Sponges provide age-old (hygienic) services to humans and continue to be of interest in modern times as sources of an unprecedented array of useful substances.

Spineless Song of Week - Receptaculites

Receptaculites oweni, Yale Peabody Museum of Natural History. Photo Credit B.S. Lieberman
This week's Spineless Song is a collaboration, once again, between myself and Christopher Taylor from the Catalogue of Organisms. The lyrics are entirely his and I do the strumming, howling and terrible overdubbed solos. This week we are extending our collaboration and making this a joint, cross-blog post. I provide the entertainment and pizzazz, Christopher provides the edutainment and, as typical of him, well researched and interesting articles.

*I recommend opening up this song in a new window (number 12 in the Spineless Song Sidebar!) for your listening pleasure while you head over to Catalogue and read about an interesting and problematic fossil taxon and decide for yourself: Is it a sponge, or is it a plant?

Sung to the tune of Particle Man by They Might Be Giants.

Receptaculites (lyrics by Christopher Taylor)

Receptaculites, Receptaculites,
Sitting around in Devonian times,
Is it a sponge, or is it a plant?
Nobody knows, Receptaculites

Its meroms are close, its body's globose,
A sessile lifestyle's the one that it chose,
But where on the tree are we gonna put those?
How can we say, Receptaculites

Archaeocyath, archaeocyath,
Not quite so much trouble by half,
It's probably a sponge, but may have an out
With Archaeata, Archaeocyath

Archaeocyath, Archaeocyath,
Placed in Archaeata with Receptaculites,
Convergence suspected, they're taken apart,
Not even close, Receptaculites

Cyclocrinites, Cyclocrinites
Looks a bit like Receptaculites,
They may form a class, Together they go,
But we still haven't a clue, Receptaculites

Tuesday Toon

Circadian Clocks in Sponges

Cool stuff! Bora from A Blog Around the Clock has posted an interesting piece giving evidence for biological clocks in the phylum Porifera, sponges if you will. It definitely worth a good reading. For instance, did you know that sponges can move!

"the whole animal rearranges itself as cells move over each other, pulling the spikules along."-Dr. Bora

Porifera Double Whammy! Huge Silicate Spicules (or are you just happy to see me?) and the Evolution of Calcification!

Craig at Deep Sea News posted on new research about a deep sea sponge, Monorhaphis chuni (Hexactinellida), with the world's largest known biosilica structure! This is a silcate spicule that can grow up to 3 meters long. Thats at least a meter longer than you!

Picture is copyright Emily S. Damstra and used by permission.
I don't really know how to construe to enormity of that structure. I could make it so you have to scroll down this post 3 meters, but that would just be annoying. The study Craig is referring to on DSN is by Müller et al., published in the most recent issue of Cell and Tissue Research. The authors carefully studied the formation of these giganto-spicules and helped along the way with silicatein-related proteins. Silica is not a common element in the ocean, though rare at the surface it increases in concentration as you go deeper by about 10-fold. The ability scavenge this rare element and incorporate into a biostructure in itself is a feat, and an expensive one at that! Now multiply that over time to about 3 meters...

This study is an excellent exercise in integrative biology. It merges biochemistry, histology, genetics, morphology and systematics. They determined there were different chemical layers to the spicules, including collagen and the silicateins (potentially a first for the Hexactinellida). The conclusion:

"Based on the data gathered here, we suggest that, in the Hexactinellida, the growth of the spicules is mediated by silicatein or by a silicatein-related protein, with the orientation of biosilica deposition being controlled by lectin and collagen."-Müller et al.

Keeping with the theme of sponge skeletons, but moving away from silica-based to carbonate-based, a study by Jackson et al. in June 29 issue of Science used an approach called Paleogenomics to determine the role of precursor alpha-Carbonic Anhydrases (a-CA's) in calcareous skeleton formation. Paleogenomics uses modern techniques, such as gene and protein expression and phylogenetics, on extant organisms in combination with knowledge of their evolutionary history. a-CA's have evolved through several gene duplication events in the Metazoa for a variety of physiological purposes:

"The chemical reaction [CO2 + H2O ⇆ HCO3− + H+] functions in processing metabolic wastes, regulating pH, fixing carbon, and transporting ions across organic membranes. The metalloenzyme carbonic anhydrase is pivotal to these processes by catalyzing this reaction approximately 1 million fold."-Jackson et al.

"(D-F) Spherulite calcification begins with an ovoid structure, with subsequent stages increasing in size. Scale bars, 5 mm." Reproduced from Jackson et al.
A very important enzyme with a diverse set of functions cascading down throughout the Metazoa. The aim of this paper, in my opinion was to see what a-CA's looked like in the last common ancestor to the Metazoa (LCAM). Sponge genomes are great to look at for these types of questions because of their basal position on the animal tree of life. They determined the a-CA enzyme is used in biocalcification of the Demosponges. The sponges (and presumably biocalcification) radiated in the Cambrian Explosion, 520-540- million years ago. The LCAM most likely used the a-CA enzyme for a similar purpose. And in fact we see this feature, biocalcification, presevered in several protostome and deuterostome taxa. As with any well written Science paper, there is a succinct final paragraph concluding their results:

"From our data we infer that a core molecular toolkit capable of catalyzing the production of HCO3− (and ultimately CaCO3) was present in the first metazoans and included an a-CA. Subsequently, various metazoan lineages inherited this toolkit and have added to and elaborated upon its key elements to guide, enhance, and inhibit the deposition of CaCO3 in the spectacular variety of ways we see today."-Jackson et al.

Two well-written sponge papers with important evolutionary conclusions. What more could you ask for?

See also a perspective written by Taylor et al. on how sponges are providing insights into animal evolution.