A significant obstacle facing notothenioids as they radiated into pelagic habitats was the ancestral absence of a swim bladder, the gas-filled chamber that most teleosts use to maintain buoyancy.
Some species also don't have swim bladders, gas chambers that help other fish control their buoyancy as they travel up and down the water column.
One large group of fishes, referred to as the Ostariophysi (e.g., catfishes, minnows, and carps), has no air sac adjacent to the labyrinth, but a possibly equivalent condition is achieved through a mechanical connection between the swim bladder and fluid chambers adjacent to the labyrinth.
The scrappy fish achieved both noises using ultra-fast muscles that beat against their swim bladders, air-filled chambers that aid in flotation, the group reports today in The Journal of Experimental Biology.
A chain of three or four small bones, known as the Weberian ossicles, extends from the anterior wall of a part of the swim bladder to a fluid-filled chamber called the atrium, which in turn connects by fluid passages with the two labyrinths in the region of the saccule-lagena complex.
Most are noisemakers and can "vocalize" by moving strong muscles attached to the air bladder, which acts as a resonating chamber, amplifying the sounds.
The size is controlled by inflating the bladder with positive pressure in the chamber, and a hard nodule can be generated using the particle jamming technique; the fine sand in the bladder becomes stiff when it is vacuumed.
Islets were cultured on extracellular matrix-coated chamber slides derived from human bladder carcinoma cells (HTB9, [35]), allowing islets to detach to the slide and spread.
They also have trained ten anatomical region centers – four heart chambers, liver, kidneys, spleen, prostate and bladder.
To test whether ETK upregulation may cause such a phenotype, we further examined the effects of ETK knock-down on bladder cancer cell migration and invasion using the Boyden chamber assays.
In the second trimester, doctors measure abdominal circumference, and check the chambers of the heart, the kidneys and bladder to spot defects and monitor growth.
