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PubMed2006

Lobomycosis in Atlantic bottlenose dolphins from the Indian River Lagoon, Florida.

OBJECTIVE: To determine the prevalence of lobomycosis, a mycotic infection of dolphins and humans caused by a yeastlike organism (Lacazia loboi), among dolphins in the Indian River Lagoon in Florida. DESIGN: Cross-sectional study. ANIMALS: 146 Atlantic bottlenose dolphins. PROCEDURE: Comprehensive health assessments of bottlenose dolphins in the Indian River Lagoon of Florida (n = 75) and in estuarine waters near Charleston, SC (71), were conducted during 2003 and 2004. Bottlenose dolphins were captured, examined, and released. Skin lesions were photographed and then biopsied. Tissue sections were stained with H&E and Gomori methenamine silver stains for identification of L. loboi. RESULTS: 9 of 30 (30%) dolphins captured in the southern portion of the Indian River Lagoon had lobomycosis, whereas none of the 45 dolphins captured in the northern portion of the lagoon or of the 71 dolphins captured near Charleston, SC, did. Affected dolphins had low serum alkaline phosphatase activities and high acute-phase protein concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that lobomycosis may be occurring in epidemic proportions among dolphins in the Indian River Lagoon. Localization of the disease to the southern portion of the lagoon, an area characterized by freshwater intrusion and lower salinity, suggests that exposure to environmental stressors may be contributing to the high prevalence of the disease, but specific factors are unknown. Because only dolphins and humans are naturally susceptible to infection, dolphins may represent a sentinel species for an emerging infectious disease.

Acute-Phase Proteins↗

PubMed1998

Anatomic site and interanimal variability in morphologic characteristics of bottlenose dolphin (Tursiops truncatus) skin likely to affect dermal absorption studies.

OBJECTIVE: To investigate anatomic site and interanimal variability in dolphin skin for use in development of models for cutaneous absorption studies. SAMPLE POPULATION: Skin from 30 healthy free-ranging bottlenose dolphins (17 males and 13 females grouped by age) and 10 captive males between 13 and 19 years old. PROCEDURE: Biopsy specimens were collected from the 10 male dolphins at 3 anatomic sites and from the 30 dolphins at 1 site; specimens were evaluated by light microscopy. Stratum externum thickness, minimal depth to the vasculature, and maximal epidermal depth were measured at 4 locations on 4 sequential sections. Comparisons of replicate measurements for 3 skin characteristics were made within and among anatomic sites, between dolphins of the same sex and approximate age, and across males and females of various ages. RESULTS: The stratum externum in male dolphins was thicker. Differences attributable to age and anatomic site were not significant. Variation attributable to differences in stratum externum thickness between dolphins was significant. Differences among body sites within the same dolphin were significant but were not consistent from dolphin to dolphin. Mean stratum externum thickness was not different between males of the 2 cohorts, but mean maximal epidermal depth and mean minimal depth to the vasculature were different. Variances within the 2 male cohorts were not significantly different. CONCLUSIONS: Studies affected by stratum externum thickness should eliminate the effect attributable to sex difference by using dolphins of the same sex or grouping analytical data by sex. Precision could be improved without increasing the total number of dolphins by collecting more than 1 sample/dolphin.

Animals↗

PubMed2005

Differences in DDT and PCB residues between common and striped dolphins from the southwestern Mediterranean.

Organochlorine concentrations (OCs) and stable isotopes were investigated in the blubber of common dolphins (Delphinus delphis) and striped dolphins (Stenella coeruleoalba) from the southwestern Mediterranean. Samples were obtained from dolphins entangled in fishing nets during the 1992-1994 fishing season and from biopsies taken in 1992. Intrapopulation variations were studied, but because most of the dolphins were juveniles or calves (90%), no significant differences were found on the basis of reproductive condition or sex. Only mature male common dolphins showed significantly higher levels of most of the compounds studied than immature individuals did. There were quantitative and qualitative interspecific differences in organochlorine compounds profile. As compared to common dolphins, striped dolphins carried higher concentrations of organochlorine concentrations (OCs), their %DDE/tDDT and PCB/tDDT ratios were significantly higher, and recalcitrant PCB congeners were more abundant. Distribution and information on composition of stomach contents would in principle support a higher exposure to OCs in common dolphins as compared to striped dolphins, thus apparently contradicting the observed results. However, stable isotopes showed that striped dolphins exploit a higher trophic level, thus explaining observed differences. Interspecific dissimilarities in metabolic capacity to handle OCs may be an added factor. Although in the two species OC concentrations exceeded levels considered to be ineffective in marine mammals, pollution-induced effects on populations could not be properly assessed.

Adipose Tissue↗

PubMed2003

Epidemiology of tattoo skin disease in bottlenose dolphins Tursiops truncatus from the Sado estuary, Portugal.

We report on the epidemiology of tattoo disease in a community of bottlenose dolphins Tursiops truncatus from the Sado estuary, Portugal. The presence of tattoos (T++) and tattoo-like (T+) lesions was examined in 586 photographic records of 35 dolphins taken from 1994 to 1997. Images were rated into 3 categories: good (GI), average (AI) and poor (PI). Dolphins positive for T++ lesions were observed in 19 GI. Dolphins with T+ lesions were seen in 39 GI, 23 AI and 6 PI. For statistical analysis the dolphins were divided into 2 age classes (immature and adult) and the data grouped into 2 periods (1994-1995 and 1996-1997). Minimum prevalence of T++ lesions in 32 dolphins was 21.9% in 1994-1995 and 15.6% in 1996-1997. Variation in prevalence of tattoo disease between the 2 age classes was examined for each period, excluding animals with T+ lesions or considering them either positive or negative for tattoos. Prevalence of the disease was significantly higher in immature dolphins than in adults during both periods, except in the first one when T+ lesions were considered as true tattoos. Temporal variation in prevalence of tattoo disease was examined in 23 adults. Prevalence was significantly higher in 1994-1995 (39.1%) than in 1996-1997 (17.4%). Differences in the number and quality of pictures did not cause significant biases that could have favoured the detection of lesions between age classes or periods. Minimal persistence of the disease ranged between 3 and 45.5 mo. The lesions converted into light grey marks when healing, but may recur. The presence of very large lesions in 2 adult dolphins affected for years may be related to the contamination of the estuary. The high prevalence of the disease, its long persistence, as well as higher frequency in immature individuals, suggest that it is endemic in bottlenose dolphins from the Sado estuary. The contribution of tattoo disease to the decline of this community should be investigated. Three of the 5 dolphins that died during this study had T++ and T+ lesions.

Age Factors↗

PubMed2005

Organochlorine pesticides, polychlorinated biphenyls, and polybrominated diphenyl ethers in Irrawaddy dolphins from India.

The Irrawaddy dolphin (Orcaella brevirostris) is at risk of extinction throughout its range as a result of incidental catches, habitat degradation, and pollution. Populations of Irrawaddy dolphins are constrained by the species' narrow habitat requirement-lagoons, estuaries, rivers, and lakes-and are therefore particularly vulnerable to the effects of human activities. In this study, for the first time, concentrations of organochlorine (OC) pesticides, polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) were determined in tissues of Irrawaddy dolphins collected from Chilika Lake, India, to understand the status of contamination. Dichlorodiphenyltrichloroethane and its metabolites (DDTs) were the predominant contaminants found in Irrawaddy dolphins; the highest concentration found was 10,000 ng/g lipid weight in blubber. Hexachlorocyclohexanes (HCHs) were the second most prevalent contaminants in dolphin tissues. Concentrations of PCBs, chlordanes, hexachlorobenzene, tris(4-chlorophenyl)methane, and tris(4-chlorophenyl)methanol were in the ranges of few ng/g to few hundreds of ng/g on a lipid-weight basis. In general, concentrations of OC pesticides and PCBs in Irrawaddy dolphins were lower than the concentrations reported for coastal and riverine dolphins collected in Asia. PBDEs were detected in the blubber of Irrawaddy dolphins at concentrations ranging from 0.98 to 18 ng/g lipid weight. BDE congener 47 accounted for 60% to 75% of the total PBDE concentrations. Although these results establish the baseline levels of persistent organic pollutants in Irrawaddy dolphins, efforts should be made to decrease the sources of contamination by DDTs and HCHs in Chilika Lake.

Adipose Tissue↗

PubMed2004

Bottlenose dolphin (Tursiops truncatus) calves appear to model their signature whistles on the signature whistles of community members.

Bottlenose dolphins are unusual among non-human mammals in their ability to learn new sounds. This study investigates the importance of vocal learning in the development of dolphin signature whistles and the influence of social interactions on that process. We used focal animal behavioral follows to observe six calves in Sarasota Bay, Fla., recording their social associations during their first summer, and their signature whistles during their second. The signature whistles of five calves were determined. Using dynamic time warping (DTW) of frequency contours, the calves' signature whistles were compared to the signature whistles of several sets of dolphins: their own associates, the other calves' associates, Tampa Bay dolphins, and captive dolphins. Whistles were considered similar if their DTW similarity score was greater than those of 95% of the whistle comparisons. Association was defined primarily in terms of time within 50 m of the mother/calf pair. On average, there were six dolphins with signature whistles similar to the signature whistles of each of the calves. These were significantly more likely to be Sarasota Bay resident dolphins than non-Sarasota dolphins, and (though not significantly) more likely to be dolphins that were within 50 m of the mother and calf less than 5% of the time. These results suggest that calves may model their signature whistles on the signature whistles of members of their community, possibly community members with whom they associate only rarely.

Acoustic Stimulation↗

PubMed2006

A dolphin peripheral blood leukocyte cDNA microarray for studies of immune function and stress reactions.

A microarray focused on stress response and immune function genes of the bottlenosed dolphin has been developed. Random expressed sequence tags (ESTs) were isolated and sequenced from two dolphin peripheral blood leukocyte (PBL) cDNA libraries biased towards T- and B-cell gene expression by stimulation with IL-2 and LPS, respectively. A total of 2784 clones were sequenced and contig analysis yielded 1343 unigenes (archived and annotated at ). In addition, 52 dolphin genes known to be important in innate and adaptive immune function and stress responses of terrestrial mammals were specifically targeted, cloned and added to the unigene collection. The set of dolphin sequences printed on a cDNA microarray comprised the 1343 unigenes, the 52 targeted genes and 2305 randomly selected (but unsequenced) EST clones. This set was printed in duplicate spots, side by side, and in two replicates per slide, such that the total number of features per microarray slide was 19,200, including controls. The dolphin arrays were validated and transcriptomic profiles were generated using PBL from a wild dolphin, a captive dolphin and dolphin skin cells. The results demonstrate that the array is a reproducible and informative tool for assessing differential gene expression in dolphin PBL and in other tissues.

Animals↗

PubMed2002

Captive dolphins, Tursiops truncatus, develop signature whistles that match acoustic features of human-made model sounds.

This paper presents a cross-sectional study testing whether dolphins that are born in aquarium pools where they hear trainers' whistles develop whistles that are less frequency modulated than those of wild dolphins. Ten pairs of captive and wild dolphins were matched for age and sex. Twenty whistles were sampled from each dolphin. Several traditional acoustic features (total duration, duration minus any silent periods, etc.) were measured for each whistle, in addition to newly defined flatness parameters: total flatness ratio (percentage of whistle scored as unmodulated), and contiguous flatness ratio (duration of longest flat segment divided by total duration). The durations of wild dolphin whistles were found to be significantly longer, and the captive dolphins had whistles that were less frequency modulated and more like the trainers' whistles. Using a standard t-test, the captive dolphin had a significantly higher total flatness ratio in 9/10 matched pairs, and in 8/10 pairs the captive dolphin had significantly higher contiguous flatness ratios. These results suggest that captive-born dolphins can incorporate features of artificial acoustic models made by humans into their signature whistles.

Animal Communication↗

PubMed2004

Geographic variations in the whistles of spinner dolphins (Stenella longirostris) of the Main Hawai'ian Islands.

Geographic variations in the whistles of Hawai'ian spinner dolphins are discussed by comparing 27 spinner dolphin pods recorded in waters off the Islands of Kaua'i, O'ahu, Lana'i, and Hawai'i. Three different behavioral states, the number of dolphins observed in each pod, and ten parameters extracted from each whistle contour were considered by using clustering and discriminant function analyses. The results suggest that spinner dolphin pods in the Main Hawai'ian Islands share characteristics in approximately 48% of their whistles. Spinner dolphin pods had similar whistle parameters regardless of the island, location, and date when they were sampled and the dolphins' behavioral state and pod size. The term "whistle-specific subgroup" (WSS) was used to designate whistle groups with similar whistles parameters (which could have been produced in part by the same dolphins). The emission rate of whistles was higher when spinner dolphins were socializing than when they were traveling or resting, suggesting that whistles are mainly used during close-range interactions. Spinner dolphins also seem to vary whistle duration according to their general behavioral state. Whistle duration and the number of turns and steps of a whistle may be more important in delivering information at the individual level than whistle frequency parameters.

Animals↗

PubMed2000

Isolation and characterization of a Helicobacter sp. from the gastric mucosa of dolphins, Lagenorhynchus acutus and Delphinus delphis.

Gastric ulcerations in dolphins have been reported for decades. Some of these lesions were associated with parasitic infections. However, cases of nonparasitic gastric ulcers with no clearly defined etiology also have been reported in wild and captive dolphins. Considerable speculation exists as to whether dolphins have Helicobacter-associated gastritis and peptic ulcer disease. The stomachs of seven stranded Atlantic white-sided dolphins, Lagenorhynchus acutus, and 1 common dolphin, Delphinus delphis, were assessed for the presence of Helicobacter species. Novel Helicobacter species were identified by culture in the gastric mucosa of two of the eight dolphins studied and by PCR in seven of the eight dolphins. The gram-negative organisms were urease, catalase, and oxidase positive. Spiral to fusiform bacteria were detected in gastric mucosa by Warthin Starry staining. Histopathology revealed mild to moderate diffuse lymphoplasmacytic gastritis within the superficial mucosa of the main stomach. The pyloric stomach was less inflamed, and bacteria did not extend deep into the glands. The lesions parallel those observed in Helicobacter pylori-infected humans. Bacteria from two dolphins classified by 16S rRNA analysis clustered with gastric helicobacters and represent a novel Helicobacter sp. most closely related to H. pylori. These findings suggest that a novel Helicobacter sp. may play a role in the etiopathogenesis of gastritis and gastric ulcers in dolphins. To our knowledge this represents the first isolation and characterization of a novel Helicobacter sp. from a marine mammal and emphasizes the wide host distribution and pathogenic potential of this increasingly important genus.

Animals↗

PubMed2001

Serum lipid peroxide and alpha-tocopherol concentrations and superoxide dismutase activity in captive bottle-nosed dolphins.

OBJECTIVE: To evaluate serum lipid peroxide (LPO) and alpha-tocopherol concentrations and superoxide dismutase (SOD) activity in captive bottle-nosed dolphins and to evaluate effects of storage on production of LPO in various marine fish. ANIMALS: 16 bottle-nosed dolphins. PROCEDURE: 8 dolphins (group A) were fed chub mackerel and herring (high fat) and arabesque greenling and banded blue-sprat (low fat); the other 8 dolphins (group B) were fed chub mackerel and Pacific saury (high fat) and shishamo smelt and Japanese horse mackerel (low fat). Each group had been on these respective diets for 3 years. Serum LPO and alpha-tocopherol concentrations, serum SOD activity, and superoxide production by neutrophils were measured. All types of marine fish were frozen at -20 C for 6 months, and concentrations of LPO were measured at various time points. RESULTS: Serum LPO concentrations in group-A dolphins were significantly higher than those in group B. Serum alpha-tocopherol concentrations and SOD activity in group A were significantly lower than those in group B. A significant negative correlation was found between serum LPO and alpha-tocopherol concentrations in all 16 dolphins. The LPO concentrations in mackerel and herring fed to group-A dolphins were higher than those of other fish. Concentrations of LPO in herring stored for 3 and 6 months at -20 C were higher than those in herring before freezing and in herring stored for 1 month. CONCLUSIONS AND CLINICAL RELEVANCE: Serum LPO and alpha-tocopherol concentrations in captive bottle-nosed dolphins may be strongly influenced by high amounts of polyunsaturated fatty acid and LPO found in marine fatty fishes. High concentrations of serum LPO, as found in group-A dolphins, were associated with decreased antioxidative states. Monitoring of serum LPO and alpha-tocopherol concentrations and serum SOD activity may be useful for the management of captive marine mammals.

Animals↗

PubMedDate not supplied

[Effect of additional loading on kinematics and hydrodynamics of dolphins].

The results of comparative measurements of hydrodynamic resistance of a solid model of dolphin and of additional load imitating an autonomous apparatus placed on the dolphin body are presented. The loading included cylinders (with rounded anterior and posterior ends) and spheres. They were fixed on the dorsal fin of the dolphin model in such a way that the interrelationship between the load and the model by a water stream minimal. In several experiments, a thick ring (dr = 10 mm) was fixed in the region of the dolphin respiratory opening to reach the turbulence of the boundary layer. The dolphin model with loads was towed in a speed range between 1.0 and 4.5 m/s. It was shown that the hydrodynamic resistance of additional loads is comparable with the resistance of the solid dolphin model. For the entire spectrum of loading in the preset range of towing speeds, the coefficient of hydrodynamic resistance of loading (according to the area of the wet body surface) was from 10 to 145% of the coefficient of the dolphin model resistance. It was assumed that the results of the measurements of kinematics and hydrodynamic characteristics of a freely-swimming dolphin can substantially differ from the results obtained on a dolphin carrying devices (at restricted power of the animal). Similar problems can also arise if the animals will carry devices with a higher hydrodynamic resistance.

Animals↗

PubMed1976

Staphylococcus aureus infections of captive dolphins (Tursiops truncatus) and oceanarium personnel.

Samples from blowhole and pharynx of 1 dolphin ill with a respiratory tract infection and 31 healthy dolphins at 2 oceanariums were examined by bacteriologic cultural technique. During the same period, nasal and volar forearm skin samples were collected from 32 healthy personnel and from a furuncle on the forearm of 1 attendant. Coagulase-positive staphylococci were isolated from 8 dolphins (including the ill dolphin) and from 14 persons. Antibiotic sensitivity patterns (8 drugs were tested) differed markedly for the staphylococcal isolates recovered from dolphins, as compared with those from persons. Staphylocci from the dolphins were totally or partially sensitive to every antibiotic, whereas almost all of the isolates from persons were resistant to penicillin and ampicillin, as well as to certain other antibiotics. Staphylococcus bacteriophage typing revealed that only 1 isolate from a dolphin could be typed (type D11). Six of the isolates from persons were typable, but no isolate was sensitive to only type D11. It was concluded that, although Staphylococcus aureus could be isolated commonly from captive dolphins, there was no evidence of cross infection between the dolphins and the oceanarium personnel.

Animals↗

PubMed2000

Precocial development of axial locomotor muscle in bottlenose dolphins (Tursiops truncatus).

At birth, the locomotor muscles of precocial, terrestrial mammals are similar to those of adults in both mass, as a percent of total body mass, and fiber-type composition. It is hypothesized that bottlenose dolphins (Tursiops truncatus), marine mammals that swim from the instant of birth, will also exhibit precocial development of locomotor muscles. Body mass data from neonatal and adult dolphins are used to calculate Grand's (1992) Neural and Muscular Indices of Development. Using these indices, the bottlenose dolphin is a Condition "3.5" neonate, where Condition 4 is the documented extreme of precocial development in terrestrial mammals. Moreover, myosin ATPase (alkaline preincubation) analyses of the epaxial locomotor m. extensor caudae lateralis show that neonatal dolphins have fiber-type profiles very similar to those of adults. Thus, based on mass and myosin ATPase activity, muscle development in dolphins is precocial. However, succinic dehydrogenase and Nile red histochemistry demonstrate that neonatal dolphin muscle has mitochondrial and lipid distributions different from those found in adults. These data suggest that neonates have a lower aerobic capacity than adults. Dolphin neonates may compensate for an apparent lack of aerobic stamina in two ways: 1) by being positively buoyant, with a relatively increased investment of their total body mass in blubber, and 2) by "free-riding" off their mothers. This study investigates quantitatively the development of a dolphin locomotor muscle and offers suggestions about adaptations required for a completely aquatic existence.

Animals↗

PubMed2003

Can dolphins heal by ultrasound?

In recent years, dolphin-assisted therapy has become very popular and an increasing number of facilities offer therapy programs with dolphins worldwide. To this date, there are no studies concerning the behavior of dolphins during these therapies. As a result of speculations that the echolocation of dolphins may play an important role for the success of the therapy and the high publicity of this in the media, people pay much more for dolphin-assisted than for other animal-assisted therapy programs. Based on publications in medicine, we will show that ultrasound emitted by dolphins could have an effect on biological tissue under some circumstances; such as sufficient intensity, repeated application over several days or weeks and a certain application duration per session. We recorded 83 sessions at the "Dolphins Plus", a fenced area with ocean water in the Florida Keys. Our observations demonstrate that only one out of five observed dolphins behave significantly differently towards patients compared to other humans and that the duration of the observed close contacts did not meet the requirements for common ultrasound therapies.

Analysis of Variance↗

PubMed1998

Trace metal pollution in Hong Kong: implications for the health of Hong Kong's Indo-Pacific hump-backed dolphins (Sousa chinensis).

The territorial waters of Hong Kong are highly contaminated with anthropogenic pollutants, including trace metals. Hong Kong's population of Indo-Pacific hump-backed dolphins (Sousa chinensis) inhabits an area where a high volume of sewage waste discharge and the close proximity of contaminated mud pits mean a considerable potential for trace metal contamination. Trace metal concentrations in the muscle tissue of fish caught from areas of high dolphin abundance are notable. However, in order to gauge the amount of trace metal consumed by dolphins, whole fish must be analysed. Whole fish from areas of high dolphin abundance have considerably higher trace metal loads than muscle tissue alone. Considering the consumption of prey items by dolphins, a daily intake of trace metals was estimated as As, 410-518; Cd, 34-44; Co, 4-5; Cr, 40-50; Cu, 44-56; Hg, 51-66; Mo, 22-27; Ni, 19-24; Pb, 320-403; Se, 99-125 and Zn, 388-490 (microgram kg-1 body wt. per day). Concentrations of arsenic, chromium, lead, molybdenum and nickel in dolphin tissues were an order of magnitude lower than in prey items, suggesting these elements may be excreted by this species. Mercury concentrations in dolphin tissues were, however, an order of magnitude higher than in prey items and could be considered potentially health threatening (max: 906 micrograms kg-1 dry wt.). Hong Kong's Indo-Pacific hump-backed dolphin population has a high dietary intake of trace metals which may, especially in the case of mercury, be a cause for concern.

Animals↗

PubMed1999

Serum alpha- and gamma-tocopherols, retinol, retinyl palmitate, and carotenoid concentrations in captive and free-ranging bottlenose dolphins (Tursiops truncatus).

Concentrations of retinol, retinyl palmitate, beta-carotene, alpha-carotene, cryptoxanthin, lutein, lycopene, alpha-tocopherol, and gamma-tocopherol were measured in blood samples collected from 15 captive and 55 free-ranging bottlenose dolphins (Tursiops truncatus). From June 1991 to June 1994, blood samples were collected from captive animals residing at two locations; at Seven Seas (Brookfield Zoo, Brookfield, IL) and Hawk's Cay (Marathon Key, FL). Blood samples were collected from free-ranging animals from June 1991 to June 1996. Retinol levels were not significantly different between captive dolphin groups. However, Seven Seas animals had higher (P < 0.01) serum retinol concentrations compared to free-ranging animals (0.061 vs 0.041 microgram/ml). Retinyl palmitate was not detected in the serum of captive or free-ranging dolphins. Alpha-tocopherol levels were significantly (P < 0.05) higher for Seven Seas dolphins (16.4 micrograms/ml) than for Hawk's Cay (13.0 micrograms/ml) and free-ranging dolphins (12.5 micrograms/ml). Gamma-tocopherol concentrations were similar among captive and free-ranging dolphins. Free-ranging dolphins showed levels of circulating carotenoids (lutein and beta-carotene) while the captive animals did not. Additional carotenoids (lycopene, alpha-carotene and cryptoxanthin) were analyzed but not detected in any samples. Serum vitamin differences between captive and free-ranging dolphins may reflect the natural diet or indicate some potential biological or nutritional status significance.

Animals↗

PubMed1998

Mechanism of spectral tuning in the dolphin visual pigments.

The absorption maxima of both rod and cone visual pigments of the bottlenose dolphin (Tursiops truncatus) are blue-shifted relative to those of terrestrial mammals. A comparison of the sequence of the dolphin rod photopigment gene with that of the bovine rod suggests that, fo the 28 nonidentical amino acids, three amino acid substitutions at positions 83, 292, and 299 in the dolphin rod pigment are responsible for the 10 nm blue shift in absorption maxima. A similar comparison of the dolphin long-wavelength sensitive (LWS) cone photopigment gene with those of the human LWS cones suggests that a single substitution at position 292 (using the convention of rhodopsin numbering) in the dolphin LWS cone pigment results in a blue shift in absorption maxima. A mutagenesis study reveals that the combination of the three dolphin specific substitutions in the bovine rod pigment (83D to 83N, 292A to 292S, and 299A to 299S) causes a blue shift from the wild-type lambdamax of 499 nm to 389 nm. The single substitution in the dolphin LWS cone pigment (292S to 292A) causes a red shift from the wild-type lambdamax of 524 nm to 552 nm. The interactions of the three amino acids identified in the rod pigment with the chromophore may be a general mechanism for blue shifting in rod visual pigments. Furthermore, the single substitution in the dolphin LWS opsin gene is a novel mechanism of wavelength modulation in mammalian LWS pigments.

Animals↗