Pulsed call sequences as contact calls in Pacific white-sided dolphins (Lagenorhynchus obliquidens).

Pacific white-sided dolphins are a group-living species and appear to exchange "contact calls" to maintain group cohesion. The aim of this study was to find and characterize their contact calls. Calls were recorded from two females at Osaka Aquarium KAIYUKAN (OAK) and three females at Izu-Mito Sea Paradise (IMSP). Because they often produced pulsed calls consecutively, a "pulsed call sequence" was defined as three or more successive pulsed calls occurring within 325 ms, which was calculated using a bout analysis. The pulsed call sequences increased during separation periods and decreased during reunions and were used for vocal exchange, suggesting that the sequences are contact calls in Pacific white-sided dolphins. Most of the pulsed call sequences were classified into unique types; several stereotyped, repeated patterns were found. One sequence type was found at OAK and the two dolphins shared the type; they exchanged sequences with type matching. On the other hand, three sequence types were found in IMSP and the three dolphins shared all of the types; however, each dolphin preferentially used different types and frequently exchanged with their own favorite types but not with type matching. These results suggest that the sequence type may function as an individual and/or group identity.

Acoustic characteristics of biosonar sounds of free-ranging botos (Inia geoffrensis) and tucuxis (Sotalia fluviatilis) in the Negro River, Amazon, Brazil.

Odontoceti emit broadband high-frequency clicks on echolocation for orientation or prey detection. In the Amazon Basin, two odontoceti species, boto (Amazon River dolphin, Inia geoffrensis) and tucuxi (Sotalia fluviatilis), live sympatrically. The acoustic characteristics of the echolocation clicks of free-ranging botos and tucuxis were measured with a hydrophone array consisting of a full-band and an acoustic event recorder (A-tag). The clicks of the two species were short-duration broadband signals. The apparent source level was 201 dB 1 µPa peak-to-peak at 1 m in the botos and 181 dB 1 µPa peak-to-peak at 1 m in the tucuxis, and the centroid frequency was 82.3 kHz in the botos and 93.1 kHz in the tucuxis. The high apparent source level and low centroid frequency are possibly due to the difference in body size or sound production organs, especially the nasal structure, the sound source of clicks in odontoceti.

Sound variation and function in captive Commerson's dolphins (Cephalorhynchus commersonii).

Commerson's dolphin (Cephalorhynchus commersonii), one of the smallest dolphin species, has been reported to produce only narrow-band high-frequency (NBHF) clicks and no whistles. To clarify their sound repertoire and examine the function of each type, we analysed the sounds and behaviour of captive Commerson's dolphins in Toba Aquarium, Japan. All recorded sounds were NBHF clicks with peak frequency >110kHz. The recorded click-trains were categorised into four types based on the changing pattern of their Inter-click intervals (ICI): Decreasing type, with continuously decreasing ICI during the last part of the train; Increasing type, with continuously increasing ICI during the last part; Fluctuating type, with fluctuating ICI; and Burst-pulse type, with very short and constant ICI. The frequency of the Decreasing type increased when approaching an object newly introduced to the tank, suggesting that the sound is used for echolocation on approach. The Burst-pulse type suddenly increased in front of the object and was often oriented towards it, suggesting that it was used for echolocation in close proximity to the object. In contrast, the Increasing type was rarely recorded during approach, but increased when a dolphin approached another dolphin. The Increasing and Burst-pulse types also increased when dolphins began social behaviours. These results suggest that some NBHF clicks have functions other than echolocation, such as communication.

The cuff technique for reconstructing an isolated left vertebral artery in total arch-replacement surgery.

In total arch-replacement surgery, careful attention must be paid to the presence of anomalous arch vessels, because their presence may require surgeons to change the brain-protection strategy during deep hypothermic circulatory arrest and selective cerebral perfusion. The anomaly we most often encounter is an isolated left vertebral artery (ILVA). We describe a case involving a straightforward but physiological way of reconstructing the ILVA in which a cuff is hollowed together with the left subclavian artery.

Continuous synthesis of alkyl ferulate by immobilized Candida antarctica lipase at high temperature.

1-Pentyl, 1-hexyl and 1-heptyl ferulates were continuously synthesized at 60-90 degrees C using a reactor system in which a column packed with ferulic acid powders and another column packed with immobilized Candida antarctica lipase particles were connected in series. Conversions greater than 0.9 were achieved for the synthesis of the 1-hexyl and 1-heptyl ferulates at 90 degrees C. The system could be stably operated for the 1-heptyl ferulate synthesis at 90 degrees C for at least two weeks.

Thermal inactivation of immobilized lipase in 1-alcohols.

The thermal inactivation of immobilized lipase from Candida antarctica in 1-alcohols with four to eight carbons at various temperatures could be well expressed using a model in which heterogeneity in the susceptibility of the enzyme to the inactivation was assumed. It was found that the enthalpy-entropy compensation held for inactivation in 1-alcohols.

Molecular forms of hypothalamic ghrelin and its regulation by fasting and 2-deoxy-d-glucose administration.

Ghrelin, an endogenous ligand for the GH secretagogue receptor, is a hormone expressed in stomach and other tissues, such as hypothalamus, testis, and placenta. This hormone acts at a central level to stimulate GH secretion and food intake. Little is known, however, about the molecular forms and physiological roles of ghrelin within the hypothalamus. In this report, we detail the molecular forms, mRNA expression patterns, and peptide contents of ghrelin within the rat hypothalamus. Using the combination of reverse-phase HPLC and ghrelin-specific RIA, we determined that the rat hypothalamus contains both n-octanoyl-modified and des-acyl ghrelins. Fasting for 24 and 48 h significantly decreased ghrelin mRNA expression in the hypothalamus to 24% and 28% of control values, respectively. Both n-octanoyl-modified and des-acyl ghrelin content in the hypothalamus decreased after 24 and 48 h of fasting. These results contrast the changes in gastric ghrelin after fasting, which decreased in content despite increased mRNA expression. Two hours after injection of 2-deoxy-d-glucose (2-DG), a selective blocker of carbohydrate metabolism, ghrelin peptide levels also decreased. Thus, induction of glucoprivic states, such as fasting and 2-DG treatment, decreased ghrelin gene expression and peptide content within the hypothalamus.