Nitrogen fixing bacteria in the gut of Panaque nigrolineatus

[bekateen]

PM sent.

[matthewfaulkner]

Dehn, A. 2010. Physiological, histological, and morphological evidence of microbial symbiosis in a xylophagous catfish Panaque nigrolineatus. Biology Thesis Towson: Towson University.

PRODUCTION OF CELLULOLYTIC ENZYMES BY A MICROBIAL COMMUNITY ISOLATED FROM A WOOD-EATING CATFISH GASTRO-INTENSTINAL TRACT by Rebecca E. Kulp & Damian Smoot.

After reading all this, it makes me wonder all the more which panaques they are studying.

Both of these seem to be from students of Towson University, working with Jay Nelson. Pretty much all the work I've seen from Nelson/Towson Uni has been using

Panaqolus maccus

.

I noticed that in the main paper we're discussing (McDonald et al. 2015), Jay Nelson is credited for "assistance with fish maintenance."

Nelson also worked with a member here (H.N) and produced - Dietary histories of herbivorous loricariid catfishes: evidence from d13C values of otoliths. The fish used were 'P. nigrolineatus' collected from the Rio do Peixe, Aruana, Goias, Brazil. So, they were likely

Panaque cf_armbrusteri`araguaia`

(also not helping, is that I've seen anecdotal evidence that there are at least two forms of Panaque from the rio Araguaia, both resembling P. cf. armbrusteri and P. cf. nigrolineatus).

But I am a bit confused about two things and if one of the better educated folks in this thread might be able to clear things up for me. The fist concerns the identity of the fish involved. Last time I looked at a map, no part of the Xingu is in Peru. When I peruse the cat-e-logue here all of the rivers listed for Panaque nigrolineatus are not anywhere near Peru and the L number is 190. When I check the Aquascape Online site, they show in stock Panaque bathyphilus as L90, Panaque sp. (L191) and Panaque cf. armbrusteri`xingu` L27. If the cat-e-log is correct only Panaque bathyphilus L90 is found in Peru. So I am completely confused as to which fish they were examining. From what I read in this thread it and what Aquascape online states, it appears to me as if the fish being examined is Panaque bathyphilus and not nigrolineatus. Can anybody unconfuse me or correct what I thought I saw to be the case?

There is Panaque sp. L418 (now absorbed into

Panaque titan

) from the rio Huallaga and Maranon in Peru (which is the 'species' that Donovan German used in his work). But I didn't even consider that it could be

Panaque bathyphilus

, so thanks for suggesting it . I probably discounted it because they are so different to the 'royal' Panaque group. Surely just a google search would make that obvious. I suppose that

Panaque schaeferi

is also a possibility given that in their earliest paper (McDonald, 2012) they said the fish were collected from the Peruvian Amazon.

But perhaps the authors only dealt with tissue samples sent to them, never having seen the fish they were from, so just relying on the ID from where they originated. Not having any experience with this sort of work/research, is this a possibility?

Now after having written all this (for a lengthy time period that I'm not willing to admit ), I think that my point was that, given Jay Nelson's involvement, my confidence is somewhat restored and these fish are P. nigrolineatus or P. cf. nigrolineatus.

Sorry for intruding on a scientific thread without having the education to understand it all. I am just curious as well as ignorant here.

This is exactly how I feel, being a twice failed uni student myself, I find it intimidating to be in a conversation with those who are PhD, MSc, etc.

[TwoTankAmin]

Eric thank you for both your kind words and your explanations.

While I am not a scientist, I have some background from my college days as a Psych major in experimental design, controls, population sampling and statistical analysis of results. I guess that is from where my attention to the small details comes. About five years back I discovered Google Scholar and I have been reading papers and abstracts ever since. I have close to 200 bookmarked most of which relate to cycling related issues and the effects/toxicity of ammonia, nitrite and nitrate on fish, inverts and aquatic plants.

I feel that the best way to have healthy fish and tanks is to have as much knowledge as possible about those things that we cannot see in tanks but which form the basis for the ecosystem in any tank.

What makes Planet Cat such a great site is the presence of scientists who are also fish keepers and who are willing to post and to respond to hobbyists like me. The same applies to the people who speak at fish events and whose brains I can pick for a bit. To all of you who are willing to spend time answering questions from hobbyists I would like to offer a big THANK YOU

And now, I return you back to the regularly scheduled Panaque discussion.........

[bekateen]

Matthew, I'd say the same thing to you that I said to TTA; you know what you're talking about. You don't need to feel intimidated to join into any conversation with others just because they have various degrees behind their names. Moreover, even when you don't know what you're talking about, the best way to learn is by asking questions. Heck, if you look back at my start here, I asked plenty of questions and said plenty of dumb things, and I plan on... no, I expect to... keep doing so for a long time to come.

TTA, although this is getting off topic, our appreciation of gut microbes is changing pretty rapidly. Even in humans, the recognition of how beneficial gut microbes can be is reflected in the economic growth of "probiotics" as nutritional supplements. And, if you can tolerate me presenting a somewhat gross, but simultaneously funny (in my opinion) offshoot of this topic, here's where the field has been heading lately: Doctors are performing fecal transplants between people to help individuals with severe cases of antibiotic-resistant bacterial intestinal infections... Yes, it's exactly what it sounds like... And of course, drug companies are all over this - the FDA is considering defining some samples of feces as a "drug" which can be patented and sold. For more info, see this, this, this, this. There are actually DIY videos on YouTube for performing your own fecal transplant (e.g., here).

Cheers, Eric

[mcdonal1]

Hi All,

My name is Ryan McDonald and I am the first author on the paper Nitrogenase diversity and activity in the gastrointestinal tract of the wood-eating catfish Panaque nigrolineatus. It makes me very happy to see there is such an extensive community who shares my interest in these organisms. I would be happy to answer any questions you may have.

Thanks.

[bekateen]

Hi Ryan,

Thank you so much for joining our discussion, and welcome to PlanetCatfish!

I am not an authority on panaque taxonomy, so I'll leave that issue for other people to address. In the mean time, I have three questions for you:

1. What do you know about the auxiliary lobe of the digestive tract in these animals?
2. Do you have any specific ideas or evidence about what particular nutritional benefit these panaques might obtain from the N-fixing bacteria? In your paper, you seemed to be saying that the primary benefit might be to provide essential amino acids and organic micronutrients (vitamins, etc) rather than caloric macronutrients.
3. Do you have any expectations as to how shifting these fish from a wood diet to an algae diet (or vice versa) would affect the bacterial diversity in the guts of these fish?

Again, thank you for offering input here.

Cheers, Eric

[matthewfaulkner]

Ryan,

Just like Eric said, thank you joining this discussion!

Could you shed some light on the origin and identity of the Panaque that you used?

[mcdonal1]

Thanks for the great questions. I will answer them as best as I can.

1. The auxiliary lobe (AL) is a very interesting structure. It is small, bilobed, structure that straddles the midgut at the point where the intestines reverses its coiling direction. Structurally it resembles liver tissue (was previously referred to as the liver-like organ) but there is no known function. However, there is some anecdotal evidence to suggest is it involved in digesta processing. When fed algae wafer,s the feces in the foregut (prior to passing the AL) are a green slurry. However, immediately distal to the AL the digesta turns an almost white color and adopts a chalk-like consistency.
It is still not clear whether the AL contributes significantly to wood digestion. I have previously characterized the microbial community of the AL and found that was very similar to that of that of the surrounding tissue. There were some putative cellulose degrading and nitrogen fixing species identified. However, microscopic analysis of the AL did not identify any obvious structures used to house a symbiotic microbial community (perhaps akin to the shipworm gland of Deshayes or the bacterial pouch of Tetraponera ants).
2. Mature, structural wood is rich in carbohydrates but is extremely nitrogen deficient. The carbon to nitrogen ration of wood is much greater than that of the primary consumer. As such, organisms like termites, shipworms, or any other xylophagic systems need to supplement their diets with alternative nitrogen sources. Every xylophagic system described to date accomplishes this by harboring an extensive diazotrophic (nitrogen-fixing) microbial community which converts atmospheric dinitrogen to ammonia. This process is carried out exclusively by microorganisms and cannot be performed by the catfish. Having read some of the comments in the thread I remember one poster commenting about how ammonia is a fish waste product that is rapidly excreted. This is true, however, the ammonia that is generated by bacteria is not made available to the fish. The process of converting nitrogen gas to ammonia is extremely energy intensive (you are breaking a triple bond). To convert one molecule of atmospheric nitrogen to ammonia requires approximately 16 ATP. As such, the bacteria will not simply release this expensive metabolite into the environment. They very efficiently combine the ammonia with glutamate to form glutamine which is used in a variety of biosynthetic pathways. The nitrogen-containing compounds that made available to the fish will be either secondary metabolites or cellular components of dead/digested bacteria. If p. nigrolineatus is truly xylivorous, the vast majority of nitrogen-containing compounds found in every cell must be the product of biological nitrogen fixation.
The majority of the calories made available to the fish come from the sequential saccharification and fermentation of the structural polysaccharides in plant cell walls. The major component of wood is cellulose which is simply repeating glucose units joined by beta glycosidic linkages. The bacteria in the gut hydrolyze these linkages to release glucose which is used as an energy source by the microorganisms. Since the GI tract is anaerobic, the glucose is fermented to a variety of short chain fatty acids (butyric acid, propionic acid, etc..) which are taken up by the fish through their intestinal epithelium.
3. This is still an area of ongoing research but I certainly believe shifting the diet of P. nigrolineatus will result in a shift in the enteric microbiome. There are a few major factors that influence enteric microbial communities. First is environment (what microorganisms you are exposed to regularly). Second is host genetics. An organism’s immune system is a major force in shaping their microbiome. Third is diet. An organism’s diet ultimately determines what nutrients are available to the enteric microbial community. If an organisms consumes primarily plant material, there will be very little protein or fats available. As such, you would expect organisms capable of efficient polysaccharide hydrolysis and fermentation to out compete other organisms. Conversely, a carnivorous diet might select for a community that had a high capacity for lipid metabolism and proteolysis. Although there are many studies that have shown that diet affects the microbiome, it is still difficult to predict what the resulting community profile will look like.

[bekateen]

Thank you, Ryan. Those are very helpful answers.

I'm thinking about what you wrote in the context of other stories (referenced earlier in this thread) which observed weight loss in these panaques when fed a wood-only diet. If the species identification is correct, these fish are natural wood eaters and not primarily algae eaters. Considering this, then fish in captivity which get fed an algae-only or algae- and wood-diet are probably getting a nutrient-rich diet, relative to what they get in nature. And if we work on the assumption that fish in nature are at least satisfactorily nourished (since they are growing and reproducing), then this would mean fish in captivity should experience greater than normal body growth on the algae diet. As a result, if we then put them on a wood-only diet, I can imagine that there would be a natural metabolic contraction, with an associated weight-loss, or at least serious slowing of growth rate, on this nutrient-limiting diet. This would create the appearance, in the data, that that these fish are not adapted to survive exclusively on a wood-only diet; but it might simply be that their bodies are realigning with a more natural, balanced metabolism and growth rate. Is this consistent with your view about these fish?

By the way, is there any significance to the fact that the coil of the gut changes direction part-way along it's length? Why not continue to coil in one direction? Do you suppose this is creating some kind of counter-current exchange mechanism? I wouldn't think so, since I imagine that (A) the reversed tubes are not anatomically juxtaposed to the earlier segments of the gut, and (B) the walls of the gut are too think to operate as such an exchanger. But honestly, I can't think of any other explanation in nature that fits for such a counter-current organization.

Personally, I think that one of the more perspective-reorienting aspects of this work is that we need to stop limiting ourselves to the idea that herbivorous and xylivorous vertebrates must have large fermentation chambers in their guts, like the stomach of a cow or the cecum of a rabbit (which are both endotherms, whereas panaques are not; so the metabolic demands of panaques are much lower than those of cows and rabbits). And even if it seems to us like this system in the panaques is inadequate for providing the high quantities of caloric and nitrogen-rich nutrients that we expect panaques need, the fact of the matter is... (as I tell my students so often in cases like this)...the fact of the matter is that in nature, these fish represent a successful adaptation to the particular ecosystems where they're found; therefore, no matter how "insufficient their system appears" to be, the reality is that it is "sufficient enough" for the panaques.

Cheers, Eric

[Bas Pels]

Thanks for the above, Ryan.

You did explain why a wood eater would need nitrogen binding, and why this would not result in the excretion of harmful substances.

Still, I wonder the nitrogen binding takes place in the gut. That is, after the food-mass has passed the stomach, which is (at least in mammals) the place where most of the protein downgrading takes place. Bacteria living in the gut will never enter the stomach – therefore I wonder where these bacteria will be processed.

Rabbits eat their own faeces in order to benefit from the bacteria in their gut – but as far as anyone knows, Panaque do not, and I don’t think their mouths are capable of doing this.

Obviously it could be Panaque has changed the order of processing – for a wood eater, having a stomach in the traditional sense (a place to digest protein) will not make sense – and having the right kind of protein in the last part of the gut would certainly make sense – but that would imply these proteins would have to be found.

Perhaps these are even very interesting – most likely the Panaque gut will never become as acidic as a stomach does – if it did, anatomical evidence (the special lining) would most likely been found.

[dw1305]

Hi all,

which observed weight loss in these panaques when fed a wood-only diet. If the species identification is correct, these fish are natural wood eaters and not primarily algae eaters. Considering this, then fish in captivity which get fed an algae-only or algae- and wood-diet are probably getting a nutrient-rich diet, relative to what they get in nature. And if we work on the assumption that fish in nature are at least satisfactorily nourished (since they are growing and reproducing), then this would mean fish in captivity should experience greater than normal body growth on the algae diet. As a result, if we then put them on a wood-only diet, I can imagine that there would be a natural metabolic contraction, with an associated weight-loss, or at least serious slowing of growth rate, on this nutrient-limiting diet. This would create the appearance, in the data, that that these fish are not adapted to survive exclusively on a wood-only diet; but it might simply be that their bodies are realigning with a more natural, balanced metabolism and growth rate

It will be interesting to hear what Ryan says, but I think that these are reasonable assumptions.

I also think that not all wood is equal, by this I mean that the heart wood of trees may be fully lignified (with an extremely high carbon to nitrogen ratio), but that any sap wood eaten by the fish would have more available nutrients present.

Again just a hunch, but there is also the microbial content of the wood to take into account. It may be that the combination of the fishes nitrogen fixing/cellulose degrading gut microflora, and the small addition of available carbohydrates & nitrogen from fungal hyphae etc in the wood, tips the nutrient balance in the fishes favour.

I'm not a microbiologist, or a fish physiologist, but I've always thought that it would be surprising if the only adaptation to wood eating that these fish had developed was their extremely modified dentition.

I've had some correspondence with Joy Watts (and with Donovan German), and she told me that the method of preparation of the gut was important. The reason for this was that, rather than being in a specialized structure, the nitrogen fixing microbial assemblage etc was occurring in a mucus layer lining of the gut.

More details are in this thread <Panaque gut microbes http://www.planetcatfish.com/forum/view ... 4&p=268294>.

cheers Darrel

[mcdonal1]

if we work on the assumption that fish in nature are at least satisfactorily nourished (since they are growing and reproducing), then this would mean fish in captivity should experience greater than normal body growth on the algae diet. As a result, if we then put them on a wood-only diet, I can imagine that there would be a natural metabolic contraction, with an associated weight-loss, or at least serious slowing of growth rate, on this nutrient-limiting diet

This is great point. Often for these experiments we will maintain the fish on mixed diets (wood, algae wafers, hearts of palm, etc...) for several months before switching them to a wood-only diet. Every time I have dissected a fish that was grown on a mixed diet their GI tract was almost completely covered with adipose tissue. Little or no adipose tissue was observed in fish that are switched over to wood-only diets. This weight loss may be due in part simply to loss of this tissue.

In regards to the possibility of the counter current exchange of the GI tract. It is definitely exciting to think about. We do not have any evidence that this is occurring but we also haven't investigated it. Through dissection though it is clear that the proximal and distal intestines sit next to each other in the body cavity. Furthermore they seem to be attached to each other by a thin membrane. This membrane is easily pulled apart with forceps, but it is substantial enough to keep those regions joined as the GI tract is unfurled.

[mcdonal1]

still, I wonder the nitrogen binding takes place in the gut. That is, after the food-mass has passed the stomach, which is (at least in mammals) the place where most of the protein downgrading takes place. Bacteria living in the gut will never enter the stomach – therefore I wonder where these bacteria will be processed

A paper by German (2009) actually showed that aminopeptidase activity is highest in the distal parts of the intestines for P. nigrolineatus (~6x higher activity than the foregut). However, as far as I know, nobody has looked at the stomach explicitly. Since digesta isn't retained in the stomach for any extended time (total gut transit is only a few hours) it would make sense that most protein digestion wold be occurring in the intestines.

[Shane]

An interesting next step might be to make these comparisons across the wood eating genera of loricariidae. In the Rio Tinaco, Venezuela I collected wood eating Panaque (P. nigrolineatus sensu stricto), Lasiancistrus, Cochliodon, and Panaqolus. Why four wood eaters in one fairly minor river? Is each somehow specialized to allow all four spp to coexist without competing?

Ryan, it may interest you to know that the two most widely used common names for P. nigrolineatus in Venezuela are "comacanoa" (canoe eater) and "runacanoa" (canoe destroyer) for their propensity to eat holes through dugout canoes. I have heard similar names are used for Panaque throughout Amazonas (Colombia, Peru, Ecuador, and Brazil) as well.

-Shane

[mcdonal1]

That's really interesting. I have heard stories about how the locals use this behavior to catch the fish. They will go out in their dug-outs and wait to hear for the rasping of catfish. They would then reach in and grab them with their hands. Never seen it done though.

[bekateen]

Still, I wonder the nitrogen binding takes place in the gut. That is, after the food-mass has passed the stomach, which is (at least in mammals) the place where most of the protein downgrading takes place. Bacteria living in the gut will never enter the stomach – therefore I wonder where these bacteria will be processed.

Rabbits eat their own faeces in order to benefit from the bacteria in their gut – but as far as anyone knows, Panaque do not, and I don’t think their mouths are capable of doing this.

Obviously it could be Panaque has changed the order of processing – for a wood eater, having a stomach in the traditional sense (a place to digest protein) will not make sense – and having the right kind of protein in the last part of the gut would certainly make sense – but that would imply these proteins would have to be found.

Perhaps these are even very interesting – most likely the Panaque gut will never become as acidic as a stomach does – if it did, anatomical evidence (the special lining) would most likely been found.

it would make sense that most protein digestion wold be occurring in the intestines.

Hi Bas Pels and Ryan,

I was following up on this issue and I came upon this title: Mansilla, W., Columbus, D., Htoo, J. K., & de Lange, C. F. M. 2013. Urea nitrogen absorbed from the hindgut is used efficiently for body protein deposition in pigs fed a diet deficient in non-essential amino acid nitrogen. Energy and protein metabolism and nutrition in sustainable animal production, 134, 413-414. Alas, I don't have access to this work, but the abstract is intriguing:

Abstract
The absorption of nitrogen (N) from the hindgut of monogastric animals is thought to be of little value for supporting body protein synthesis. However, N that is absorbed from the lower gut, largely in the form of ammonia, can be used for synthesis of non-essential amino acids (NEAA) or converted to urea. The latter can be excreted in urine or recycled into the upper gut and contribute to microbial-produced amino acids that can be of benefit to the host (Fuller, 2012). The objective of the present experiment was to explore the efficiency of using N absorbed from the hindgut for body protein deposition in growing pigs fed a diet deficient in NEAA-N.

A related article (the Masters thesis by the lead author) can be found here: Non-Protein Nitrogen is Used Efficiently for Improving Protein Deposition and Feed Efficiency in Growing Pigs

Abstract
Nitrogen (N) absorbed by the lower gut (caecum and large intestine), primarily in the form of ammonia, is generally considered to be of little nutritional value for growing pigs. The main objective of research presented in this thesis was to explore the effects of providing nonprotein N (NPN) on N retention, urea kinetics, activity of key liver enzymes, and growth performance of pigs fed diets deficient in non-essential amino acid N (NEAA-N). Urea-N infused into the lower gut increased N retention, with an estimated efficiency of 96%. Whole body urea flux and urea recycling into the gastro-intestinal tract were not affected by urea infusion into the lower gut. When feeding growing pigs NEAA-N deficient diets, feed efficiency increased linearly with level of dietary supplementation with ammonium salts. These data support that NPN can be efficiently used for improving N retention and feed efficiency in pigs fed diets deficient in NEAA-N.

In regards to the possibility of the counter current exchange of the GI tract. It is definitely exciting to think about. We do not have any evidence that this is occurring but we also haven't investigated it. Through dissection though it is clear that the proximal and distal intestines sit next to each other in the body cavity. Furthermore they seem to be attached to each other by a thin membrane. This membrane is easily pulled apart with forceps, but it is substantial enough to keep those regions joined as the GI tract is unfurled.

Mansilla's statement that ammonia from the lower gut can be converted into urea and then "recycled" into the upper gut to be used for microbial amino acid production makes me think again of a possible countercurrent circulation pattern (or maybe not exactly countercurrent; maybe just crossing past, like the distal convoluted tubule of the mammalian nephron crosses the efferent arteriole in the kidney, forming the juxtaglomerular apparatus). I wish I had a better picture in my mind of the specific arrangement of the gut in panaques, with the reversing direction of the gut pathway and the potential interaction that might be created between microbes in different sections of the gut as the wood is metabolized.

Before now, I've never heard of vertebrates using ammonia or urea from the diet as a way to boost bodily protein levels, so this is most interesting.

Cheers, Eric

[Bas Pels]

While there are some slight differences between pigs and Panague, this could be quite an interesting route for obtaining proteins.

Obviously, the first question would be the necessary anatomic requirements, and then the fysiological adaptations.

Thanks, Eric

[bekateen]

Yes, slight.

[bekateen]

UPDATE: I've been speaking with Jay Nelson. He was able to compile a list of the fish purchased (in some cases, with source companies and locations) for their

Panaque

research and also a list of publications and presentations which resulted from these purchases. Here is the information he provided me, as written by Jay (*Thank you, Jay Nelson):

4/07: East Coast Zoologicals,

L027

Rio Xingu,

Kulp, Smoot abstracts were with these fish:

• D. Smoot, R. Kulp, J. A. Nelson and J. E. M. Watts. Microbial diversity in the gastrointestinal tract of wood-eating catfish. National Conf. on Undergraduate Res. April.10-12th, 2008 Salisbury University.
• R. Kulp, D. Smoot, J. A. Nelson and J. E. M. Watts. Production of cellulolytic enzymes by a microbial community isolated from a wood-eating catfish gastro-intestinal tract. National Conference on Undergraduate Research. April.10-12th, 2008 Salisbury University.
• D. Smoot, R. Kulp, J. A. Nelson and J. E. M. Watts. Microbial diversity in the gastrointestinal tract of wood-eating catfish. Minorities in research Science Conference. Sept.14-15th, 2007 Baltimore Convention Center.
• K.D. Nguyen, J. A. Nelson and J. E. M. Watts. RFLP analysis of microbial diversity in the gastrointestinal tract of wood-eating catfish. Towson University ASM MD Branch Meeting June 2007 University Baltimore.
• Smoot, D., N. M. Mohamed, J. A. Nelson, H. J. Schreier, and J. E. M. Watts. Investigating the Microbial Communities Associated with Xylophagy in the Gastrointestinal Tract of Panaque nigrolineatus. American Society for Microbiology, General Meeting, Abstract N-174, 2008.
• Smoot, D., R. Kulp, N. Mohamed, J. A. Nelson, H. J. Schreier, and J. E. M. Watts. Microbial communities associated with different regions the gastrointestinal tract of Panaque nigrolineatus, a xylophagous catfish. Twelfth International Symposium on Microbial Ecology, August 17-22, 2008.

4/08: East Coast Zoologicals, Rio Caguan, Caqueta, Colombia-

My graduate student Mickey Dehn ordered the following from Aquascapes, I found this information in his notes.

6/30/2009 Aquascapes, Rio Negro region, Peru
10/22/09 Aquascapes,

L190

, no region,
12/03/09 Aquascapes,

L190

, no region,

• Dehn, A. M. and J.A. Nelson. (2010). Ever eat a palm tree? Growth, histology, and digestive physiology of a wood-eating catfish, Panaque nigrolineatus. 2010 Joint Meeting of Ichthyologists and Herpetologists, Providence RI.

5/02/10: Aquascapes,

L190

, no region, -Ryan McDonald used : Don Stewart comments:

HI Jay, No that is not titanicus in the picture -- it is another new species that gets even bigger. 'Titanicus', however, is in the manuscript in press along with a third species from southern Brazil that looks like nigrolineatus -- but titanicus will appear with a slightly different name. P. nigrolineatus will be restricted to the Orinoco basin, and the 'nigrolineatus' studied by Hiro is another new species not included in our paper. That is being described in a follow-up paper by a Brazilian colleague.

This group is complex with more new species awaiting discovery/description, but as the newspaper article notes, they are hard to catch -- so small samples in museums and striking morphological allometries make it difficult to understand geographic variation. In this new paper, we re-describe the three previously known 'large panaques', so this should open the door to new discoveries. Cheers, Don

• McDonald, R. C., H. J. Schreier, J. A. Nelson, and J. E. M. Watts. Analysis of 16S rRNA genes from a catfish (Panaque nigrolineatus) gastrointestinal tract reveals highly specialized xylan- degrading microbial populations indicative of a xylophagic dietary strategy. 111th Meeting of the American Society for Microbiology, May 5-11, 2011, New Orleans, LA.
• McDonald, R. C., H. J. Schreier, J. A. Nelson, and J. E. M. Watts. Analysis of 16S rRNA genes from the alimentary tract of the wood-eating catfish Panaque nigrolineatus reveals xylan- degrading microbial populations consistent with a xylophagic dietary strategy. Society for General Microbiology, April 11-14, 2011, North Yorkshire, UK.

7/1/11 East Coast Zoologicals,

L191

claim Colombia. Ryan McDonald also used

Both H. Nonogaki & D. Stewart identify as

Panaque titan

• Nelson, J.A., K. McHenry and D. Richards. “INTESTINAL FREE FATTY ACID PRODUCTION BY WATER BREATHING VERSUS AIR-BREATHING PANAQUE NIGROLINEATUS (LORICARIIDAE), A TROPICAL WOOD-EATING CATFISH” Int. Congress on the Biology of Fish, July 2012, Madison WI.

These would most likely be the ones in the recent publication by Schreier, McDonald and company.[/color]

Cheers, Eric

[bekateen]

Also, Jay Nelson gave us an invitation: He still has many of the fish, so if anyone who is knowledgeable about these fish is interested in coming to his lab to examine the fish in order to make a more definitive ID, Jay says we're welcome to come and do so!

Cheers, Eric

[Jools]

Where is the lab?

Jools

[bekateen]

Where is the lab?

Dr. Jay Nelson,
Department of Biological Sciences
Towson University
Towson, Maryland USA 21252
http://pages.towson.edu/nelson

[Jools]

I'd seen that before, my brain being dull. There are lots of fish keepers in that area and a Planet folks too. I reckon someone would be able to take pics at some point. But even a smartphone pic would probably suffice forID.

Cheers

Jools

[matthewfaulkner]

Thanks for you investigating, Eric Like Jools said, a photos would be enough, especially one of the mouth/teeth.

[Krakozawr]

Hello friends!

At first, sorry my English in advance. I hope you will be able to understand
I'm not a scientist, too; I have an education in biology (ichthyology especial) in my background but I have had a loooooong pause and I never really worked in this area. So, my opinion may be just a "semi-educated speculation". But...

What about the weight loss at the wooden diet.
What kind of woods these fishes was receiving?
In the natural habitat, I believe that woods-eaters have unlimited source of woods. And I believe that, in this situation, they eats not exactly WOODS - but only a surface layer of woods, softened and partially destroyed already with fungi, bacterias and algas - so it should not be a clean woods but a rich "cocktail" of partially destroyed woods, bacteria, fungi and algas, which contain alot of protein and other supplements, maybe richest by protein than a regular planted foods. In a real life they just have no needs to eating of under-layers of hardwoods, because they can migrate to a neighbor places, till a cleaned surface will be "restored" - or destroyed - enough to consumption.

If I right, in this situation bacterial digestion of woods may play just a very tiny role in a "energetic" feeding and may working more for help to eliminate a "ballast" of woods, consumed as a side-effect; and some additional benefits by providing some supplements like vitamins etc. If in a laboratory they received just a not sufficient amount of woods, surface cannot be able to be prepared properly by bacteria and fungi, and fishes eats just a clean woods which is not their natural food, and lose their muscle mass, of course...

[dw1305]

Hi all,

What about the weight loss at the wooden diet.
What kind of woods these fishes was receiving?
In the natural habitat, I believe that woods-eaters have unlimited source of woods. And I believe that, in this situation, they eats not exactly WOODS - but only a surface layer of woods, softened and partially destroyed already with fungi, bacterias and algas - so it should not be a clean woods but a rich "cocktail" of partially destroyed woods, bacteria, fungi and algas, which contain alot of protein and other supplements, maybe richest by protein than a regular planted foods. In a real life they just have no needs to eating of under-layers of hardwoods, because they can migrate to a neighbor places, till a cleaned surface will be "restored" - or destroyed - enough to consumption.

If I right, in this situation bacterial digestion of woods may play just a very tiny role in a "energetic" feeding and may working more for help to eliminate a "ballast" of woods, consumed as a side-effect; and some additional benefits by providing some supplements like vitamins etc. If in a laboratory they received just a not sufficient amount of woods, surface cannot be able to be prepared properly by bacteria and fungi, and fishes eats just a clean woods which is not their natural food, and lose their muscle mass, of course...

That would be my suggestion as well, "not all wood is equal".

If you look on page 2. of this thread there are links <"http://www.planetcatfish.com/forum/view ... 4&p=268294"> & <"http://www.planetcatfish.com/forum/view ... an#p241856"> to some earlier discussion on this with Dr Donovan German <"http://german.bio.uci.edu/Research_1.ht ... ecology_of"> as well as to the Towson University papers <http://pages.towson.edu/nelson/Panaque/panaque.html>.

cheers Darrel

[Krakozawr]

Thank you for links Darrel, this is a direct link which mentioned exactly what I mean: http://www.planetcatfish.com/forum/view ... an#p241856

All wood is equal (more-less, if we will forget about tannins and other supplements) - this only a cellulose at least; but not a wood is an energy source for fishes.

[Bas Pels]

It could be Krakozawr was thinking of this: Wild fish, caught and brought to the USA might not be the same as they originally were

It could be bacteria have entered the gut, which was vulnerable because it was empty. We do know Otocinclus can have their guts infected because of being empty, why not Panaque as well.

If this was not Krakozawr's question, his posting made me think of it. Therefore I think he deserves any credit.

I think it is a good question, but if anyone would be offended by it, I'm afraid I'm to blame for putting it this bold.

[bekateen]

...Wild fish, caught and brought to the USA might not be the same as they originally were

It could be bacteria have entered the gut, which was vulnerable because it was empty. We do know Otocinclus can have their guts infected because of being empty, why not Panaque as well.

It sounds like you should develop a new product - probiotics for panaques!

Probiotics for kids' school lunches

In truth, maybe it's not a bad idea. We should encourage Allen Repashy to get on this - maybe he can develop a sawdust-based gel or paste with probiotic microbes in it, essentially aufwuchs in a tube.

[Krakozawr]

...Wild fish, caught and brought to the USA might not be the same as they originally were

It could be bacteria have entered the gut, which was vulnerable because it was empty. We do know Otocinclus can have their guts infected because of being empty, why not Panaque as well.

It sounds like you should develop a new product - probiotics for panaques!

f2a93c0d69416411bc76722fe333fbfa.jpg

In truth, maybe it's not a bad idea. We should encourage Allen Repashy to get on this - maybe he can develop a sawdust-based gel or paste with probiotic microbes in it, essentially aufwuchs in a tube.

I believe that just a little detritus from a healthy tank wit a same /similar species should be OK
By the way, I don't think that it will be so easy to kill all symbiotic bacteria in a digestion tract of a live fish (even with antibiotics) at all, fish should be dead faster. Bacteria's population should be able to restore when environment will be normalized, I believe.