Dry swim bladders and Isinglass; swim bladder (Bexigas natatórias secas e Isinglass; bexiga natatória)

Similarly swim bladder tumors are benign papillary adenomas that protrude into the swim bladder lumen, where the tumor cells are very much larger than the normal mucosal cells—being very tall columnar cells.

Fish maw, also known as swim bladder or fish stomach, is a unique and highly prized ingredient in Asian cuisine.

This delicacy is derived from the swim bladder of various fish species, and it is renowned for its gelatinous texture and ability to absorb the flavors of the dishes it is cooked with.

Fish maw has been a culinary staple in Chinese and Southeast Asian cuisines for centuries, known for its nutritional value and culinary versatility.

It is often used in soups, stews, and braised dishes, where it absorbs the essence of the surrounding ingredients and imparts a rich, savory taste and a pleasingly smooth texture to the dish.

This delicacy is not only celebrated for its culinary attributes but also for its potential health benefits.

It is believed to contain high levels of collagen, which can promote skin health and overall well-being.

Fish maw comes in various shapes and sizes, each with its own unique culinary applications.

Whether you encounter it in the form of dried, shredded pieces or whole swim bladders, fish maw adds a touch of luxury and elegance to any meal.

The fishy ingredient in beer that bothers vegetarians

Many people may not realise the beer in their pint glass contains a product made from fish. Now the Campaign for Real Ale (Camra) is calling on brewers to investigate alternatives for their drinks. But why is fish put in beer anyway?

Ask somebody to list the classic ingredients of beer and the chances are they will come back with: hops, malt, barley and water, with a bit of yeast thrown in for good measure.

It is unlikely the swim bladder of fish would be on the list, but isinglass - a gelatine made using the organ - is in fact very likely to be in your average pint.

Used since the 19th Century as a fining agent to make beer clear, bright and more attractive to drinkers, the odourless added extra is used widely by brewers, from mass-produced brands to small microbreweries.

Its prevalence poses a problem for vegetarians and vegans, many of whom do not realise they need to tread carefully when ordering at the bar.

Now Camra is calling on breweries to examine alternatives to isinglass in beer, is a brewing revolution on the cards?

Swim (gas) bladder

The swim bladder present in most Teleosts lies right above the digestive tract and below the spinal vertebrae (consequently right below the kidney) and is beside the top portion of the pleural ribs.

Swim bladders may be filled with either air or oxygen, thus playing a key role in maintaining neutral buoyancy and lowering energy costs for fish to remain at any certain depth.

In some species, such as the pirarucu, Arapaima gigas, the swim bladder is highly vascularized and functions as a respiratory organ.

The swim bladder may be connected to the digestive tract, more specifically with the esophagus and stomach through a structure called the pneumatic duct.

According to this structure and the evolutionary pattern of the swim bladder, teleost fish can be grouped as physostomous (e.g., pacu, goldfish, carp) or physoclistous (e.g., Siluriformes in general).

Physostomous fish maintain the connection of the swim bladder-esophagus all through the adult stage, whereas physoclistous fish lose the pneumatic duct in the adult phase.

Introduction to the anatomy and physiology of the major aquatic animal species in aquaculture

Special organs (e.g., swim bladder)

Most bony fishes (the ray-finned fishes) have a gas-filled swim bladder (or air bladder or gas bladder), a hydrostatic organ that allows them to be neutrally buoyant in water.

Swim bladders vary in shape and their connections with other internal organs partly because swim bladders perform other functions such as hearing (sound reception), respiration, and sound production.

For example, in mainly freshwater fishes (common carp, catfish, bowfin), the swim bladder is interconnected with the inner ear of the fish .

The swim bladder usually consists of two gas-filled sacs located in the abdominal cavity just below the kidney and above the stomach and intestines of the teleost fish.

It has flexible walls that contract or expand according to the ambient pressure.

Due to its dorsal position, it gives the fish lateral stability.

Fish swim bladders obey Boyle’s law, that is, the swim bladder changes volume as the fish swims up and down in the water, and the ambient (hydrostatic) pressure changes, especially near the surface.

Usually, the swim bladder is about 5% of the body volume of marine fishes (in denser seawater), and about 7% in freshwater fishes, and provides enough lift for neutral buoyancy.

Wim bladders and floats

Swimming is energetically expensive and whilst obviously important for many activities such as pursuing prey, escaping predators and finding a mate, it is energetically advantageous to reduce its use for keeping afloat.

This is where buoyancy devices come in and most of these involve gas-filled structures.

For surface floating organisms (pleuston) these can be fairly simple and nonadjustable surface buoys.

Examples are the large pneumatophores of some species of Siphonophorae such as the Portuguese Man-of-war (Physalia), or the inflated pedal disc of the unusual drifting sea anemones, Actinecta. The pelagic gastropod, Janthina, floats at the surface attached to a raft of air bubbles enclosed in a viscid secretion.

If detached from its raft, the animal sinks and apparently cannot regain the surface. Many large seaweeds including Giant Kelp (Macrocystis) and seashore bladder wracks such as Fucus vesiculosus, Ascophyllum nodosum and Sargassum spp. have air bladders within the thallus which keep them upright in the best position for photosynthesis.

At low tide seashore seaweeds lie around in heaps and their capacity for photosynthesis is much reduced (or zero of course if low tide falls in the dark).

Some siphonophoran colonies including Nanomia and Forskalia float some distance below the surface, but again suspended beneath a gas-filled pneumatophore.

As these colonies are carried to different levels, gas can be released through a sphincter-controlled pore or (in Nanomia at least) more gas added via (invaginated) ectoderm cells lining the float.

An interesting feature of the gas in Nanomia and several other Siphonophorae is that it contains carbon monoxide, a possible advantage being its low solubility in water.

Animals swimming below the surface and moving considerable vertical distances between levels need more than a fixed float because of the pressure changes they will encounter.

Maintaining neutral buoyancy for most of the time and not having to struggle against either sinking or rising saves considerable energy.

The aim basically is to match the animal’s overall density to that of the water.

In pelagic ray-finned fishes and cephalopod molluscs, this is commonly achieved by means of various types of adjustable gas cavity.

Fish swim bladders: A gas-filled swim bladder, situated in the body cavity, is the norm in most pelagic and many benthopelagic ray-finned fishes.

Any diver or snorkeler who comes face to face with a John Dory (Zeus faber) cannot help but be amazed at its ability to hover in front of them, with minimal movements of its fins.

Such fish generally have better buoyancy control than the divers watching them, who are wearing sophisticated buoyancy compensation devices (BCDs).

When a fish with a gas bladder (or a scuba diver wearing a BCD) moves upwards the gas inside the bladder will expand as the hydrostatic pressure falls.

If the fish were unable to do anything about it, it would rapidly gain positive buoyancy and bob up to the surface and the distension of the bladder would be likely to cause damage.

This effect shows dramatically in fish brought quickly to the surface during fishing, when the swim bladder often expands so much that it pushes the gut out through the mouth like a balloon.

Alternatively, during downward movement, the bladder will contract under increasing pressure and this could cause loss of buoyancy and force the fish downward.

Normally, of course, such changes of buoyancy are prevented by the ability of the animal to maintain the volume of the float virtually constant, despite changes of external pressure.

A fish with a closed swim bladder does this by secreting more gas into it during descent, via a vascularized gas gland and removing gas during ascent, via a different thin-walled portion of the bladder.

These actions allow the fish to counteract the tendency of the swim bladder to change volume as the pressure alters.

However, diffusion of gas into and out the swim bladder via diffusion from the blood cannot take place instantly and so most fish with swim bladders are unable to make very rapid changes of depth..

Isinglass

Isinglass is a form of collagen obtained from the dried swim bladders of fish.

The English word origin is from the obsolete Dutch huizenblaas – huizen is a kind of sturgeon, and blaas is a bladder, or German Hausenblase, meaning essentially the same.

The bladders, once removed from the fish, processed, and dried, are formed into various shapes for use.

It is used mainly for the clarification or fining of some beer and wine.

It can also be cooked into a paste for specialised gluing purposes.

Although originally made exclusively from sturgeon, especially beluga, in 1795 an invention by William Murdoch facilitated a cheap substitute using cod.

This was extensively used in Britain in place of Russian isinglass, and in the US hake was important.

In modern British brewing all commercial isinglass products are blends of material from a limited range of tropical fish.

Isinglass - Foods and drinks

Before the inexpensive production of gelatin and other competing products, isinglass was used in confectionery and desserts such as fruit jelly and blancmange.

Isinglass finings are widely used as a processing aid in the British brewing industry to accelerate the fining, or clarification, of beer.

It is used particularly in the production of cask-conditioned beers, although many cask ales are available which are not fined using isinglass.

The finings flocculate the live yeast in the beer into a jelly-like mass, which settles to the bottom of the cask.

Left undisturbed, beer will clear naturally; the use of isinglass finings accelerates the process.

Isinglass is sometimes used with an auxiliary fining, which further accelerates the process of sedimentation.

Non-cask beers that are destined for kegs, cans, or bottles are often pasteurised and filtered.

The yeast in these beers tends to settle to the bottom of the storage tank naturally, so the sediment from these beers can often be filtered without using isinglass.

However, some breweries still use isinglass finings for non-cask beers, especially when attempting to repair bad batches.

Many vegetarians consider beers that are processed with these finings (such as most cask-conditioned ales in the UK) to be unsuitable for vegetarian diets (although acceptable for pescetarians).

According to global data in 2018, along with low-calorie beer and gluten-free beer, beers that are acceptable for strict vegetarians are expected to grow in demand in the coming years.

The demand increase is attributed to millennial consumers, and some companies have introduced vegetarian friendly options or done away with isinglass use.

A beer-fining agent that is suitable for vegetarians is Irish moss, a type of red algae containing the polymer chemical carrageenan.

However, carrageenan-based products (used in both the boiling process and after fermentation) primarily reduce hazes caused by proteins, but isinglass is used at the end of the brewing process, after fermentation, to remove yeast.

Since the two fining agents act differently (on different haze-forming particles), they are not interchangeable, and some beers use both.

Isinglass finings are also used in the production of kosher wines, although for reasons of kashrut, they are not derived from the beluga sturgeon, because this fish is not kosher.

Whether the use of a nonkosher isinglass renders a beverage nonkosher is a matter of debate in Jewish law.

Rabbi Yehezkel Landau, in Noda B'Yehuda, first edition, Yore Deah 26, for example, permits such beverages.

This is the position followed by many kashrut-observant Jews today.

The similar-sounding names has resulted in confusion between isinglass and waterglass, especially as both have been used to preserve eggs.

A solution of isinglass was applied to eggs and allowed to dry, sealing their pores. Waterglass is sodium silicate.

Eggs were submerged in solutions of waterglass, and a gel of silicic acid formed, also sealing the pores of the eggshell.

Isinglass - Conservation

Isinglass is also used as an adhesive to repair parchment, stucco and damage to paintings on canvas.

Pieces of the best Russian isinglass are soaked overnight to soften and swell the dried material.

Next, it is cooked slowly in a double boiler at 45°C while being stirred.

A small amount of gum tragacanth dissolved in water is added to the strained isinglass solution to act as an emulsifier.

When repairing paint that is flaking from parchment, isinglass can be applied directly to an area which has been soaked with a small amount of ethanol.

It is typically applied as a very tiny drop that is then guided, with the help of a binocular microscope, under the edges of flaking paint.

It can also be used to coat tissue or goldbeater's skin.

On paintings this can be used as a temporary backing to either canvas patches or filler until dried.

Here, isinglass is similar to parchment size and other forms of gelatin, but it is unique in that as a dried film the adhesive can be reactivated with moisture.

For this use, the isinglass is cooked with a few drops of glycerin or honey.

This adhesive is advantageous in situations where minimal use of water is desired for the parchment as the isinglass can be reactivated with an ethanol-water mixture.

It also has a greater adhesive strength than many other adhesives used for parchment repair.

Retrovírus de Peixes

Leiomyosarcoma of the Swim Bladder

Leiomyosarcoma of the swim bladder in Atlantic salmon (Salmo salar) was first recognized in salmon raised in captivity at a commercial fish farm in Scotland in 1976.

The disease was observed in 4.6% of the fish that had been placed in a sea cage during the previous year.

These fish were in poor physical condition and had multiple nodular masses on the surface of the swim bladder.

A second outbreak of the disease occurred in 1996 in Atlantic salmon collected from the Pleasant River in Maine that were housed in a fish hatchery in Massachusetts and used as breeding stock for the Atlantic salmon recovery program.

Mortality among affected salmon in the Pleasant River peaked at 35% in the spring of 1998.

Affected fish exhibited signs of lethargy, hemorrhages in the fins and body, and swollen abdomens containing firm nodular masses on the external and internal surfaces of the swim bladder.

The swim bladder of affected salmon was distended by the presence of these masses.

Histologically, the tumors are composed of spindle cells arranged in intertwined bundles divided by collagen bands.

The neoplastic cells exhibit moderate anisocytosis, variable nuclear pleomorphism, frequent pyknotic nuclei, and abundant mitotic figures.

The tumor cells stain positive for desmin and weakly positive for smooth muscle actin, consistent with the diagnosis of leiomyosarcoma.

Electron microscopy was used to examine neoplastic tissue collected from Atlantic salmon during the first outbreak of disease in 1976, which revealed the presence of budding retroviruslike particles.

These observations led investigators to pursue a molecular approach to identify possible retrovirus sequences in swim bladder leiomyosarcomas collected from the second outbreak.

Degenerate PCR primers that target conserved sequences in the RT genes of retroviruses were used to amplify a tumor-associated retroviral sequence.

The complete sequence of Atlantic salmon swim bladder sarcoma virus (SSSV) was obtained and found to be 10.9 kb in length.

SSSV contains gag, pro, pol and env genes and utilizes a methionine-tRNA as a primer for replication.

Full-length viral transcripts and singly spliced env transcripts are detected in tumors.

The virus has not been propagated in cell culture.

SSSV is an exogenous retrovirus that does not contain viral accessory genes, which distinguishes it from the complex fish retroviruses WDSV and WEHV.

Phylogenetic analysis places SSSV between the Gammaretrovirus and Epsilonretrovirus genera.

Unlike mammalian and avian simple retroviruses, related endogenous copies of SSSV are not present in the Atlantic salmon genome.

SSSV-associated tumors contain high proviral copy numbers (≥30 copies per cell) and a polyclonal integration pattern.

The mechanisms that lead to the accumulation of proviruses in tumors are not known.

Gross and microscopic features are used to confirm the presence of swim bladder leiomyosarcoma.

The presence of SSSV can be detected in blood of salmon by PCR.

Salmon can be screened for infection with SSSV using viral-specific PCR primers. There are no vaccines available.

Biology and Ecology of Venomous Marine Scorpionfishes (Family Scorpaenidae)

Biology

Identification: This species is diagnosed by the following characters: dorsal fin is with 13 spines and 10 soft rays; anal fin is with 3 spines and 5 soft rays; and pelvic fin is with 1 spine and 5 soft rays.

Gill rakers are simple, short and robust.

Swim bladder is present. Body of this species is oblong, moderately compressed anteriorly and is strongly compressed posteriorly.

Head is large and its length greater than body depth.

Low membranous tube is associated with anterior and posterior nostrils; and posterior edge of tube on anterior nostril is slightly expanded.

Numerous small papillae are sometimes present on frontal surface of bulge of snout and chin.

Ctenoid scales are covering on head, including cheek, lacrimal, suborbital pit, interopercle, subopercle, and opercle.

Scales are absent on both lips and bulge of snout.

Maxilla is with weakly ctenoid scales; and posterior portion of maxilla is almost entirely scaled or partly scaled as one-third maxilla depth.

Mandible is usually with exposed weakly ctenoid scales.

Ctenoid scales are covering on body and extending onto base of caudal fin; scales on ventral body surface are relatively weak; pectoral-fin base is covered with weakly ctenoid scales; and a row of elongated cycloid scales is present on bases of soft-rayed portions of dorsal and anal fin.

Lateral line is complete. Three sensory pores are present on underside of each dentary; and a small pore is seen on each side of symphysial knob.

Mouth is moderately large, oblique and is forming an angle of c. 40–50° to horizontal axis of head and body; and upper edge of maxilla is swollen laterally forming a low ridge.

Upper jaw is with a band of small slender conical teeth; about 4–6 tooth rows are at front of upper jaw; and about 4 tooth rows are present at front of lower jaw.

Vomer is with a V-shaped patch of 1–5 rows of small teeth.

Dorsal profile of snout is steep, forming an angle of c. 40° to horizontal axis of head and body.

Interorbital ridges are moderately developed, with a row of 0–19 spines.

Interorbital space is shallow, about one-seventh of orbit diameter extending above dorsal profile of head.

Dorsal-fin soft rays are all branched; length of the longest ray is subequal to or slightly longer than that of the longest fin spine; and posteriormost ray is not joined by membrane to caudal peduncle.

Anal-fin soft rays are all branched.

Pectoral fin is long; and usually fifth (branched ray) and tenth (unbranched ray) rays are the longest in relatively small and large specimens, respectively.

Pelvic-fin soft rays are all branched and third ray is the longest, much longer than upper jaw. Caudal fin is rounded. It grows to a maximum length of 95 cm (SL).

Isinglass - preparation

Isinglass é uma gelatina derivada de bexigas natatórias de peixes tropicais que é facilmente solúvel em ácidos organicos e tem sido usada para clarificar bebidas alcoólicas.

O presente trabalho objetivou obter isinglasses a partir de bexigas natatórias dos peixes Pescada-branca (Cynoscion leiarchus) e Bagre (Bagre bagre), realizar caracteriza??o fisco-química (composi??o centesimal) e física (peso, rendimento e cor) das bexigas e dos isinglasses e avaliar as propriedades reológica dos isinglasses (for?a de gel e viscosidade).

As bexigas foram pesadas, lavadas, imersas em solu??o de 0,8M de NaCl por 10 minutos, lavadas novamente, cortadas e submetidas a dois tratamentos para cada espécie.

Bexigas de Bagre: T1BA) Imers?o em solu??o de ácido acético 0,5M e T2BV) Imers?o em vinagre de álcool comercial, ambas na propor??o de 1:30 (g/mL).

Bexigas de Pescada Branca: T1PA) Imers?o em solu??o de ácido acético 0,5M T2PV) Imers?o em vinagre de álcool comercial, ambas na propor??o de 1:50 (g/mL).

Para extra??o do colágeno, as bexigas foram imersas nestas solu??es e mantidas a 4oC, por dois dias.

Posteriormente, o material foi filtrado, obtendo-se assim uma solu??o de colágeno, a qual foi aquecida por 2 horas à 55oC, foi colocada em bandejas plásticas e levadas a estufa, 55oC, para forma??o de filmes de gelatina.

Os rendimentos dos isinglasses foram de 24,55% (T1BA), 24, 05% (T2BV), 39,26% (T1PA) e 34,90% (T2PV).

Houve diferen?a significativa somente nos tratamentos da Pescada Branca.

Os teores de proteína dos isinglasses variaram de 81,99% (T2BV) a 82,98% (T1PA) sendo observada diferen?a significativa para os tratamentos da Pescada Branca.

Os valores de pH em todos os tratamentos foram considerados ácidos quando comparados com os da literatura, em decorrência do método de extra??o.

Os isinglasses dos tratamentos com vinagre apresentaram baixos valores de Bloom (T2BV – 68,07 gf e T2PV – 78,30 gf) enquanto os demais apresentaram médio Bloom (T1BA – 140,47 gf e T1PA – 151,22 gf).

O tratamento das bexigas com ácido acético apresentou maior temperatura de fus?o, indicando assim uma gelatina de melhor qualidade, o que também foi observado quanto à for?a de gel.

Os isinglasses T1BA, T2BV e T2PV apresentaram viscosidade menor do que T1PA e todas as amostras gelificaram antes ou na temperatura de 10°C, considerada adequada para a gelatina.