Portable-size artificial uterine system for viviparous shark embryos.

In this study, we developed a portable artificial uterus specifically designed for viviparous elasmobranchs (sharks and batoids). This new method is different from the previous method owing to the absence of fluid-cleaning filters, a smaller amount of incubation fluid, and the use of a mini-sized refrigerator for temperature control. Due to these modifications, the total weight decreased to approximately 40 kg, which is less than one-twentieth that of the previous system.

Fluorescent cacao oil: A material suited for highlighting blood vessel in macro-scale dissection.

This study describes a novel method to highlight vascular networks in animal tissue during macro-scale dissection using cacao oil and ultraviolet (UV) fluorescent dye. This is a three-step method: 1) injecting warmed cacao oil containing oil-based UV fluorescent dye ("fluorescent cacao oil" or FCO) into the blood vessels of a dead animal; 2) lowering the temperature to solidify the FCO in blood vessels; and 3) illuminating blood vessels with UV light when the specimen is dissected. This method uses the unique properties of cacao oil, which is solid at room temperature but becomes liquid at 40°C.

Volume of the whale shark and their mechanism of vertical feeding.

The present study provides a noninvasive method to estimate the body volume of sharks (Elasmobranchii, Selachii) using a computational geometric model. This method allows the volume of sharks to be estimated from lateral and ventral photographs assuming an elliptical body cross-sectional geometry. A comparison of the estimated and actual body volumes of several shark species showed that the estimation error was < 0.

Armored eyes of the whale shark.

This report elaborates on adaptations of the eyes of the whale shark Rhincodon typus (Elasmobranchii, Rhincodontidae), including the discovery that they are covered with dermal denticles, which is a novel mechanism of eye protection in vertebrates. The eye denticle differs in morphology from that of the dermal denticles distributed over the rest of the body, consistent with a different function (abrasion resistance). We also demonstrate that the whale shark has a strong ability to retract the eyeball into the eye socket.

Stealth breathing of the angelshark.

For benthic fishes, breathing motion (e.g., oral, pharyngeal, and branchial movements) can result in detection by both prey and predators.

Morphology of a Hidden Tube: Resin Injection and CT Scanning Reveal the Three-dimensional Structure of the Spiracle in the Japanese Bullhead Shark Heterodontus japonicus (Chondrichthyes; Heterodontiformes; Heterodontidae).

The spiracle of elasmobranchs (sharks, skates, and rays) is a gill-slit-derived tube located behind the eye. Its inner structure was well studied in the late nineteenth to early twentieth century, but its entire morphology has rarely been characterized and is poorly understood. The present study shows the three-dimensional morphology of the spiracular tube for the first time, using resin injection and CT scanning, in the Japanese bullhead shark.

Development of the Lunate-Shaped Caudal Fin in White Shark Embryos.

The lunate-shaped caudal fin in lamnid sharks is a morphological specialization for their thunniform mode of locomotion, but its developmental process during gestation has been poorly investigated. Observations of 21 embryonic specimens of the white shark (Carcharodon carcharias) revealed that their caudal fin morphology drastically changes from strongly heterocercal to lunate-shaped through ontogeny. This morphological change involves (1) rapid elongation of the ventral lobe, (2) increased upward curvature of the vertebra within the caudal fin, and (3) formation of keels at both lateral sides of the caudal fin base.

Aerobic Dechlorination of Dichloromethane Using Biostimulation Agent BD-C in Continuous and Batch Cultures of Xanthobacter autotrophicus GJ10.

It is important to construct microbiological treatment systems for organic solvent-contaminated water. We developed a continuous culture supplemented with a biostimulation agent named BD-C, which is formulated from canola oil, and Xanthobacter autotrophicus strain GJ10 for an aerobic dichloromethane (DCM)-dechlorinating microorganism. The continuous culture was a chemostat constructed using a 1 L screw-capped bottle containing artificial wastewater medium with 2.

Dental ontogeny of a white shark embryo.

Unlike most viviparous vertebrates, lamniform sharks develop functional teeth during early gestation. This feature is considered to be related to their unique reproductive mode where the embryo grows to a large size via feeding on nutritive eggs in utero. However, the developmental process of embryonic teeth is largely uninvestigated.

How great white sharks nourish their embryos to a large size: evidence of lipid histotrophy in lamnoid shark reproduction.

The great white shark (Carcharodon carcharias) exhibits viviparous and oophagous reproduction. A 4950 mm total length (TL) gravid female accidentally caught by fishermen in the Okinawa Prefecture, Southern Japan carried six embryos (543-624 mm TL, three in each uterus). Both uteri contained copious amounts of yellowish viscous uterine fluid (over 79.

Eye retraction in the giant guitarfish, Rhynchobatus djiddensis (Elasmobranchii: Batoidea): a novel mechanism for eye protection in batoid fishes.

Eye retraction behavior has evolved independently in some vertebrate linages such as mudskippers (fish), frogs and salamanders (amphibians), and cetaceans (mammals). In this paper, we report the eye retraction behavior of the giant guitarfish (Rhynchobatus djiddensis) for the first time, and discuss its mechanism and function. The eye retraction distance was nearly the same as the diameter of the eyeball itself, indicating that eye retraction in the giant guitarfish is probably one of the largest among vertebrates.

Ultrasound and physical models shed light on the respiratory system of embryonic dogfishes.

Embryos of live-bearing elasmobranchs (sharks, skates, and rays) must acquire oxygen in the uterus for several months to more than a year, but the mechanisms of delivery and uptake are still largely unknown. Diagnostic sonography performed on a captive Japanese dogfish (Squalus japonicus) showed that a late-stage embryo used buccal movement to pump uterine fluid, suggesting that the embryo acquires oxygen from uterine fluid via gill ventilation. It has been assumed that embryonic respiration in aplacental sharks depends on oxygen supplied by the uterine wall.

Onset of buccal pumping in catshark embryos: how breathing develops in the egg capsule.

Respiration in fishes involves buccal pumping, which is characterized by the generation of nearly continuous water flow over the gills because of the rhythmic expansion/compression of the pharyngeal cavity. This mechanism is achieved by the functions of the vascular, skeletal, and muscular systems. However, the process by which the embryo establishes the mechanism remains a mystery.

Live-bearing manta ray: how the embryo acquires oxygen without placenta and umbilical cord.

We conducted an ultrasonographic experiment on a pregnant manta ray, Manta alfredi (Chondrichthyes, Batoidea). This study showed how the embryo of the live-bearing elasmobranchs respires in the body of the female. In the embryonic stage, the manta ray embryo takes in uterine fluid by buccal-pumping.

Rapid reductive dechlorination of trichloroethene in contaminated ground water using biostimulation agent, BD-1, formulated from canola oil.

A case study of the bioremediation of groundwater contaminated with trichloroethene (TCE) was conducted using the biostimulation agent, BD-1. TCE levels were monitored by gas chromatography-mass spectroscopy. Total organic carbon (TOC) and volatile fatty acids (VFAs) were analyzed to investigate the environmental fate of BD-1.

Detailed investigations of polymer/metal multilayer matching layer and backing absorber structures for wideband ultrasonic transducers.

Detailed investigations of multilayer front and back matching layers and a novel backing absorber have been conducted, the detailed theory for which was presented in a previous paper. To design useful structures using the simple proposed equations, the material parameters of the constituent layers must be identified. Therefore, polyimide (for the matching layer) and adhesive-backed copper tape (for the absorber) were characterized by bonding them to polyvinylidene fluoride-trifluoroethylene P(VDF-TrFE) copolymer ultrasonic transducers and then applying a parameter-fitting algorithm to the resulting impedance data.

Novel multi-layer polymer-metal structures for use in ultrasonic transducer impedance matching and backing absorber applications.

This paper presents a novel design principle for designing multilayer polymer-metal structures which are well suited for front surface impedance conversion (matching) and for back surface acoustic absorption. It is shown that a polymer layer with an outer metal layer, when loaded by a low impedance propagation medium, acts as an efficient impedance converter. The resulting impedance seen at the inner polymer surface is increased and the structure provides the same performance as a traditional quarter-wavelength matching layer.

New symmetric reflector ultrasonic transducers (SRUT).

This paper proposes a new structure composed of reflector plates mounted in front and in back of the transducer at an angle of 45 degrees, so that acoustic waves from front and back of the transducer are combined to form a single main beam. This principle is applicable to both transmitters and receivers. Because the propagation path lengths of the 2 beams are identical, they constructively add at all frequencies.

Narrowband impedance matching layer for high efficiency thickness mode ultrasonic transducers.

A new matching layer design concept has been proposed for narrowband continuous wave (CW) devices. Analysis has shown that the mechanical impedance of a resonant-type transducer in thickness mode CW operation does not equal its acoustic impedance rhoVs but roughly equals rhoVs/Q, where p is density, Vs is acoustic velocity, and Q is the mechanical quality factor. The value of rhoVs/Q is much lower than the acoustic impedance of water for any transducer material, including lead zirconium titanate (PZT), single crystals, or polyvinylidene fluoride (PVDF).

New type of matching layer for air-coupled ultrasonic transducers.

This paper presents a new concept in the design of an impedance matching structure for air coupled ultrasonic transducers. A reflective layer structure is inserted between the transducer and propagation medium with a small air space. Adjusting the air space and the reflectivity of the inserted structure causes the transducer impedance to match with the impedance of the propagation medium.

Cylindrical PVDF film transmitters and receivers for air ultrasound.

Cylindrical polyvinylidene fluoride (PVDF) film transducers for transmission and reception of 40-kHz ultrasonic waves in air have been investigated. A key feature of such transducers is their omni-directional polar response. An optimized structure comprises a cylindrical PVDF film element resting on a spool without a mechanical bond to it.