A histological and NMR study of the melon of the striped dolphin (Stenella coeruleoalba)

Scano, Paola; Maxia, Cristina; Maggiani, Federica; Crnjar, Roberto Massimo; Laı̈, Adolfo; Sirigu, P.

doi:10.1016/j.chemphyslip.2004.10.001

Cited by 13 publications

(22 citation statements)

References 12 publications

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“…These fat bodies do not change in lipid content or composition during fasting and starvation, are quite metabolically stable (Pond 1998, Cranford et al 1996, and do not exhibit biochemical stratification (Zahorodny Duggan et al 2009), although acoustic fat depots showed a biochemical composition gradient to channel sound toward ears (Koopman et al 2006). Some studies have addressed the morphology of melon and acoustic fat depots in the striped dolphin (Scano et al 2005, Maxia et al 2007), but performed no comparison with morphological structure from body blubber. Although blubber from position 2 does not properly correspond to the acoustic fat region, it is clearly adjacent to the jaw.…”

Section: Blubber Stratificationmentioning

confidence: 99%

Topographical variation in lipid content and morphological structure of the blubber in the striped dolphin

Gómez–Campos¹,

Borrell²,

Correas³

et al. 2015

Sci. Mar.

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Summary:We investigate stratification patterns and topographical variations in the blubber of the striped dolphin (Stenella coeruleoalba) to gain insights into its regionally-specific functions. We collected blubber from 10 stranded striped dolphins (5 females and 5 males) from the eastern coast of Spain in 2007-2009, at 11 body positions. Histological measurements (adipocyte number and area) and blubber lipid content were analysed for each position. Histological measurements revealed stratification of blubber into outer, middle, and inner layers. Both the adipocyte number and area were largest in the middle layer. The adipocyte number was higher in the outer than the inner layer, whereas the adipocyte area was higher in the inner than the outer layer. The ventral anterior position did not follow this pattern, likely due to its proximity to the acoustic blubber, which is known to have a different biochemical composition. The stratification in morphological blubber characteristics most likely reflects functional differences. The outer layer may provide structural support and act as a mechanical barrier with a minor role in energy storage. The middle layer may be responsible for thermoregulation, and the inner layer could be responsible for energy mobilization, which is favoured by its proximity to the body core and a higher vascularization. In addition, an increasing gradient from dorsal to ventral positions was observed in the mean number of adipocytes and lipid content, with the exception of the caudal region. Although both ventral and dorsal blubber can have insulator and buoyancy functions, the ventral blubber may mainly serve as an energy reserve.Keywords: Stenella coeruleoalba; cetacean; adipocytes; histology; stratification; lipid content. Estructura morfológica y variación topográfica del contenido lipídico en la grasa del delfín listadoResumen: En el presente estudio se investigaron los patrones de estratificación así como las variaciones topográficas en la grasa del delfín listado (Stenella coeruleoalba) con el fin de conocer mejor las posibles funciones regionales de este tejido. Se recolectaron muestras de grasa en 11 posiciones corporales diferentes de 10 delfines listados (5 hembras y 5 machos) varados en la costa este de España entre los años 2007 y 2009. Las medidas histológicas (número de adipocitos y área de los mismos) y el contenido lipídico se analizaron en cada una de las posiciones. Las medidas histológicas mostraron que la grasa se estratificaba en 3 capas: externa, media e interna. Tanto el número de adipocitos como su área eran mayores en la capa media. El número de adipocitos era superior en la capa externa que en la interna, mientras que el área de los adipocitos era mayor en la capa interna que en la externa. Sin embargo, la región ventral anterior no seguía este patrón, probablemente esto sea debido a que esta región se encuentra muy próxima a la grasa acústica, que es conocida por presentar una composición bioquímica diferente al resto de grasa corporal. La estratificación morfológi...

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Section: Blubber Stratificationmentioning

confidence: 99%

Topographical variation in lipid content and morphological structure of the blubber in the striped dolphin

Gómez–Campos¹,

Borrell²,

Correas³

et al. 2015

Sci. Mar.

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“…Taken together, the spatial placement, rates of accumulation and mode of synthesis of these acoustic lipids, in conjunction with their physiological peculiarities, provide a convincing case for a highly specialized system with carefully controlled development. Two recent studies on striped dolphins (Stenella coeruleoalba; Scano et al 2005;Maxia et al 2007) offer further support for the ontogenetic maturation of acoustic fats from a histological perspective; these authors showed that in addition to biochemical accumulation, the melon and jaw fats also undergo morphological changes with age, and they too suggested that this process would result in different sound reception properties. The presence and arrangement of the unusual acoustic lipids also offer a fairly compelling argument from a functional perspective, as completion of acoustic fat development is timed to coincide with independence.…”

Section: Discussionmentioning

confidence: 97%

Life history constrains biochemical development in the highly specialized odontocete echolocation system

Koopman

Zahorodny

2008

Proc. R. Soc. B.

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The vertebrate head has undergone enormous modification from the features borne by early ancestors. The growth of skull bones has been well studied in many species, yet little is known about corresponding soft tissue development. Among mammals, some of the most unusual examples of cranial evolution exist in the toothed whales (odontocetes). Specialized fat bodies in toothed whale heads play important roles in sound transmission and reception. These fat bodies contain unique endogenous lipids, with favourable acoustic properties, arranged in highly organized, three-dimensional patterns. We link variation in developmental rates of acoustic fats with life-history strategy, using bottlenose dolphins and harbour porpoises. Porpoise acoustic fats attain adult configurations earlier (less than 1 year) and at a faster pace than dolphins. The accelerated lipid accumulation in porpoises reflects the earlier need for fully functional echolocation systems. Dolphins enjoy 3-6 years of maternal care; porpoises must achieve total independence by approximately nine months. Further, a stereotypic 'blueprint' for the spatial distribution of lipids is established prior to birth, demonstrating the highly conserved nature of the intricate biochemical arrangement in acoustic tissues. This system illustrates an unusual case of soft tissue development being constrained by life history, rather than the more commonly observed mechanistic or phyletic constraints.

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“…An interesting feature of adipose tissues is that sound speeds through fats are slower than through other types of soft tissues at body temperatures in mammals, excluding the lungs . Gradients in sound speeds and their functional implications have been explored for odontocete acoustic tissues, including the melon and the peri-mandibular fats Blomberg and Lindholm, 1976;Wedmid et al, 1973Scano et al, 2005;Koopman et al, 2006;Zahorodny et al, 2009). For example, Koopman et al (2006) found that the distribution of lipids within perimandibular fats of odontocetes show consistent patterns, where the shortest and branched chain compounds were concentrated in the middle of the inner fat body and around the tympano-periotic complex.…”

Section: Lipid Contentmentioning

confidence: 99%

“…Two key advantages to using AEPs over conventional behavioral hearing studies are that they do not require trained animals and they can be employed outside of the laboratory. For example, AEPs have been used to successfully measure odontocete hearing in capture-release scenarios and in stranded animals (e.g., Nachtigall et al, 2005;Finneran et al, 2009;Mann et al, 2010).…”

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confidence: 99%

The auditory system of the minke whale (Balaenoptera acutorostrata) : a potential fatty sound reception pathway in a mysticete cetacean

Yamato¹

2012

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Despite widespread concerns about the effects of anthropogenic noise on baleen whales (suborder Mysticeti), we lack basic information about their auditory physiology for comprehensive risk assessments. Hearing ranges and sensitivities could be measured if customized equipment and methods were developed based on how baleen whales receive sound. However, sound reception pathways in baleen whales are currently unknown. This thesis presents an integrative approach to understanding hearing in baleen whales through dissections, biomedical imaging, biochemical analyses, and modeling sound propagation through a whale head using the Finite Element Method (FEM). We focused on the minke whale (Balaenoptera acutorostrata) because it is one of the smallest and most abundant mysticete species, reducing logistical difficulties for dissections and experiments. We discovered a large, well-formed fat body extending from the blubber region to the ears and contacting the ossicles. Although odontocetes, or toothed whales, are thought to use specialized "acoustic fats" for sound reception, no such tissues had been described for mysticetes to date. Our study indicates that the basic morphology and biochemical composition of the minke whale "ear fats" are very different from those of odontocete acoustic fats. However, the odontocete and mysticete fatty tissues share some characteristics, such as being conserved even during starvation, containing fewer dietary signals compared to blubber, and having well-defined attachments to the tympano-periotic complex, which houses the middle and inner ears. FE models of the whale head indicated that the ear fats caused a slight increase in the total pressure magnitude by the ears, and this focusing effect could be attributed to the low density and low sound speed of the ear fats in the models. Fatty tissues are known to have lower densities and sound speeds than other types of soft tissues, which may explain why they are an important component of the auditory system of odontocetes, and perhaps mysticete cetaceans as well. In an aquatic habitat where the pinna and air-filled ear canal are no longer effective at collecting and focusing sound towards the ears, we propose that both odontocete and mysticete cetaceans have incorporated fatty tissues into their auditory systems for underwater sound reception.

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A histological and NMR study of the melon of the striped dolphin (Stenella coeruleoalba)

Cited by 13 publications

References 12 publications

Topographical variation in lipid content and morphological structure of the blubber in the striped dolphin

Topographical variation in lipid content and morphological structure of the blubber in the striped dolphin

Life history constrains biochemical development in the highly specialized odontocete echolocation system

The auditory system of the minke whale (Balaenoptera acutorostrata) : a potential fatty sound reception pathway in a mysticete cetacean

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