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At least 19 recordsLinked to original sources

PubMed2005

Phylogeography and population genetics of the endangered Amazonian manatee, Trichechus inunguis Natterer, 1883 (Mammalia, Sirenia).

We used mitochondrial DNA control region sequences to examine phylogeography and population differentiation of the endangered Amazonian manatee Trichechus inunguis. We observe lack of molecular differentiation among localities and we find weak association between geographical and genetic distances. However, nested clade analysis supports restricted gene flow and/or dispersal with some long-distance dispersal. Although this species has a history of extensive hunting, genetic diversity and effective population sizes are relatively high when compared to the West Indian manatee Trichechus manatus. Patterns of mtDNA haplotype diversity in T. inunguis suggest a genetic disequilibrium most likely explained by demographic expansion resulting from secession of hunting and enforcement of conservation and protective measures. Phylogenetic analysis of T. manatus and T. inunguis haplotypes suggests that T. inunguis is nested within T. manatus, effectively making T. manatus a paraphyletic entity. Paraphyly of T. manatus and recent divergence times of T. inunguis and the three main T. manatus lineages suggest a possible need for a taxonomic re-evaluation of the western Atlantic Trichechus.

Animals↗

PubMed2006

Comments on "Intraspecific and geographic variation of West Indian manatee (Trichechus manatus spp.) vocalizations" [J. Acoust. Soc. Am. 114, 66-69 (2003)].

This letter concerns the paper "Intraspecific and geographic variation of West Indian manatee (Trichechus manatus spp.) vocalizations" [Nowacek et al., J. Acoust. Soc. Am. 114, 66-69 (2003)]. The purpose here is to correct the fundamental frequency range and information on intraindividual variation in the vocalizations of Amazonian manatees reported by Nowacek et al. (2003) in citing the paper "Signature information and individual recognition in the isolation calls of Amazonian manatees, Trichechus inunguis (Mammalia: Sirenia)" [Sousa-Lima et al., Anim. Behav. 63, 301-310 (2002)].

Animals↗

PubMed2004

Characterization of a novel close-to-root papillomavirus from a Florida manatee by using multiply primed rolling-circle amplification: Trichechus manatus latirostris papillomavirus type 1.

By using an isothermal multiply primed rolling-circle amplification protocol, the complete genomic DNA of a novel papillomavirus was amplified from a skin lesion biopsy of a Florida manatee (Trichechus manatus latirostris), one of the most endangered marine mammals in United States coastal waters. The nucleotide sequence, genome organization, and phylogenetic position of the Trichechus manatus latirostris papillomavirus type 1 (TmPV-1) were determined. TmPV-1 is the first virus isolated from the order of Sirenia. A phylogenetic analysis shows that TmPV-1 is only distantly related to other papillomavirus sequences, and it appears in our phylogenetic tree as a novel close-to-root papillomavirus genus.

Amino Acid Sequence↗

PubMedDate not supplied

Osmoregulation in wild and captive West Indian manatees (Trichechus manatus).

The ability of West Indian manatees (Trichechus manatus latirostris and Trichechus manatus manatus) to inhabit both freshwater and marine habitats presents an interesting model to study osmoregulation in sirenians. Blood samples were analyzed from manatees held in fresh- and saltwater and from wild animals captured in fresh-, brackish, and saltwater for concentrations of aldosterone, arginine vasopressin, plasma renin activity, Na+, K+, Cl-, and osmolality. Two separate experiments were also conducted on captive animals to evaluate osmoregulatory responses to acute saltwater exposure and freshwater deprivation. Spurious differences were observed in plasma electrolyte and osmolality among the captive and wild groups. Wild brackish water animals exhibited the highest vasopressin concentrations, while wild freshwater manatees had the highest aldosterone levels. A significant correlation between mean vasopressin and osmolality was demonstrated for captive and wild animals. When freshwater animals were acutely exposed to saltwater, osmolality, Na+, and Cl- increased 5.5%, 8.0%, and 14%, respectively, while aldosterone decreased 82.6%. Saltwater animals deprived of freshwater exhibited an almost twofold increase in aldosterone during the deprivation period and a fourfold decrease when freshwater was again provided. Within this group, osmolality increased significantly by 3.4% over the course of the study; however, electrolytes did not change. The lack of consistent differences in electrolyte and osmolality among wild and captive groups suggests that manatees are good osmoregulators regardless of the environment. The high aldosterone levels in wild freshwater animals may indicate a need to conserve Na+, while the high vasopressin levels in wild brackish-water manatees suggest an antidiuretic state to conserve water. Vasopressin levels appear to be osmotically mediated in manatees as in other mammals.

Adaptation, Physiological↗

PubMed1988

The primary structure of the hemoglobin of the Brazilian manatee (Trichechus inunguis, Sirenia).

The hemoglobin of the Brazilian Manatee (Trichechus inunguis, Sirenia) consists of one component. We present the primary structures of the alpha- and beta-chains which have been separated by chromatography on carboxymethyl-cellulose CM-52. The sequences have been determined by automatic Edman degradation with the film technique, using the native chains, tryptic peptides and the C-terminal prolyl-peptide obtained by acid hydrolysis of the Asp-Pro bond of the alpha-chains. Compared to the corresponding human chains we found 27 substitutions in the alpha- as well as in the beta-chains. Three heme contacts and four alpha 1/beta 1 contacts between the subunits are affected by exchanges. The hemoglobin of Trichechus inunguis is compared with those of Elephas maximus, Loxodonta africana, and Procavia habessinica and the monophyletic origin of the superorder Paenungulata is discussed.

Amino Acid Sequence↗

PubMed2000

Diaphragm structure and function in the Florida manatee (Trichechus manatus latirostris).

Relative to many other mammals, little is known about the functional morphology of the four extant species of the order Sirenia. In this study, 166 Florida manatee (Trichechus manatus latirostris) carcasses fresh enough to collect detailed anatomical information were examined to describe the gross anatomy of the diaphragm. Our results show that the Florida manatee's diaphragm differs from those of other mammals in that it: lies in a dorsal plane, rather than in the more typical transverse plane; is located dorsal to the heart and does not attach to the sternum; and attaches medially at the "I"-shaped central tendon to bony projections extending ventrally from the vertebral bodies, forming two distinct hemidiaphragms. The manatee's transverse septum is a separate structure that lies at a right angle to the diaphragm and separates the heart from the liver and other viscera. The extreme muscularity of the diaphragm and the ability of manatees to adjust their position in the water column with minimal external movement suggest that diaphragmatic contractions may change the volume of each pleural cavity to affect buoyancy, roll, and pitch. We also hypothesize that such contractions, in concert with contractions of powerful abdominal muscles, may compress gas in the massive large intestine, and thereby also contribute to buoyancy control.

Animals↗

PubMed2001

Functional morphology of venous structures associated with the male and female reproductive systems in Florida manatees (Trichechus manatus latirostris).

The reproductive organs of Florida manatees (Trichechus manatus latirostris) are surrounded by thermogenic locomotory muscles and insulating fat. Manatees are reported to maintain core body temperatures of 35.6 degrees -36.4 degrees C, temperatures known to interfere with production and maturation of viable sperm in terrestrial mammals. We describe two novel venous plexuses associated with the manatee epididymis. Each epididymis is located in a hypogastric fossa at the caudolateral extremity of the abdominal cavity. Each hypogastric fossa is lined by an inguinal venous plexus that receives cooled blood from a superficial thoracocaudal plexus. We conclude that male manatees may prevent hyperthermic insult to their reproductive tissues by feeding cooled superficial blood to venous plexuses deep within their bodies. Female manatees also possess hypogastric fossae and venous structures similar to those found in male manatees. The ovaries, uterine tubes, and distal tips of the uterine horns are located in the hypogastric fossae. We suggest that the thermovascular structures we describe also prevent hypothermic insult to female manatee reproductive tissues. The venous structures in manatees are functionally similar to structures associated with reproductive thermoregulation in cetaceans and phocid seals. Thus, these thermovascular structures appear to be convergent morphological adaptations that occur in three clades of diving mammals with independent evolutionary histories.

Animals↗

PubMed2002

Viral papillomatosis in Florida manatees (Trichechus manatus latirostris).

The Florida manatee (Trichechus manatus latirostris) is one of the most endangered marine mammals in American coastal waters. Naturally resistant to infectious disease, the manatee immune system appears highly developed to protect it against the harsh marine environment and the effects of human-related injury. In 1997, seven captive Florida manatees developed multiple, cutaneous, pedunculated papillomas over a period of 6 months. Approximately 3 years later, four of the seven manatees developed multiple, cutaneous, sessile papillomas topically and clinically distinct from the initial lesions, some of which are still present. Histologic, ultrastructural, and immunohistochemical features indicated that the two distinct phenotypic lesions were caused by papillomaviruses (PVs). Preliminary immunologic data correlated with daily clinical observations suggested that the manatees were immunologically suppressed and that the papillomas were caused by activation of latent PV infections and reinoculation from active infections. The emergence of PV-induced papillomas in captive manatees, the possibility of activation of latent infection or transmission of active infection to free-ranging manatees, and the underlying cause of immune suppression predisposing manatees to develop viral papillomatosis are serious concerns for the future management of this highly endangered species.

Female↗

PubMed2001

Characterization of kidney epithelial cells from the Florida manatee, Trichechus manatus latirostris.

The West-Indian manatee, Trichechus manatus latirostris, is a herbivorous marine mammal found in the coastal waters of Florida. Because of their endangered status, animal experimentation is not allowed. Therefore, a cell line was developed and characterized from tissue collected during necropsies of the manatees. A primary cell culture was established by isolating single cells from kidney tissue using both enzymatic and mechanical techniques. Primary manatee kidney (MK) cells were subcultured for characterization. These cells were morphologically similar to the cell lines of epithelial origin. An immunocytochemistry assay was used to localize the cytokeratin filaments common to cells of epithelial origin. At second passage, epithelial-like cells had an average population-doubling time of 48 h, had an optimum seeding density of 5 x 10(3) cells/cm2, and readily attached to plastic culture plates with a high level of seeding efficiency. Although the epithelial-like cells had a rapid growth rate during the first three passages, the cloning potential was low. These cells did not form colonies in agar medium, were serum dependent, had a limited life span of approximately nine passages, and possessed cell-contact inhibition. These data suggest that the cells were finite (noncontinuous growth), did not possess transformed properties, and were of epithelial origin. These cells are now referred to as MK epithelial cells.

Animals↗

PubMed2005

Temporal resolution of the Florida manatee (Trichechus manatus latirostris) auditory system.

Auditory evoked potential (AEP) measurements of two Florida manatees (Trichechus manatus latirostris) were measured in response to amplitude modulated tones. The AEP measurements showed weak responses to test stimuli from 4 kHz to 40 kHz. The manatee modulation rate transfer function (MRTF) is maximally sensitive to 150 and 600 Hz amplitude modulation (AM) rates. The 600 Hz AM rate is midway between the AM sensitivities of terrestrial mammals (chinchillas, gerbils, and humans) (80-150 Hz) and dolphins (1,000-1,200 Hz). Audiograms estimated from the input-output functions of the EPs greatly underestimate behavioral hearing thresholds measured in two other manatees. This underestimation is probably due to the electrodes being located several centimeters from the brain.

Acoustic Stimulation↗

PubMed2005

Effects of environmental stressors on lymphocyte proliferation in Florida manatees, Trichechus manatus latirostris.

The health of many Florida manatees (Trichechus manatus latirostris) is adversely affected each year by exposure to cold weather or harmful algal blooms (red tide; Karenia brevis). Exposures can be sublethal, resulting in stressed animals that are rescued and taken to authorized facilities for rehabilitation, or lethal if exposures are prolonged or unusually severe. To investigate whether sublethal environmental exposures can impair immune function in manatees, rendering animals vulnerable to disease or death, mitogen-induced proliferation was assessed in lymphocytes from manatees exposed to cold temperatures (N=20) or red tide (N=19) in the wild, and compared to lymphocyte responses from healthy free-ranging manatees (N=32). All animals sampled for this study were adults. Lymphocytes were stimulated in vitro with either concanavalin A (ConA) or phytohemagglutinin (PHA) and proliferation was assessed after 96 h using incorporation of the thymidine analog, bromodeoxyuridine (BrdU), into newly synthesized DNA. Proliferation of lymphocytes from manatees rescued from exposure to red tide or cold-stress was approximately one-third that of lymphocytes from healthy free-ranging manatees. To examine the direct effects of red tide toxins on lymphocyte function, mitogen-induced proliferation was assessed following co-culture of lymphocytes with K. brevis toxin extracts. Stimulation indices decreased with increasing toxin concentration, with a significant decrease in proliferation occurring in the presence of 400 ng red tide toxins/ml. When lymphocytes from cold-stressed manatees were co-cultured with red tide toxin extracts, proliferative responses were reduced even further, suggesting multiple stressors may have synergistic effects on immune function in manatees.

Animals↗

PubMed2005

Characterization of surface interleukin-2 receptor expression on gated populations of peripheral blood mononuclear cells from manatees, Trichechus manatus latirostris.

An in vitro system to determine surface interleukin-2 receptor (IL-2R) expression on mitogen-stimulated peripheral blood mononuclear cells (PBMC) from free-ranging manatees, Trichechus manatus latirostris was developed. Human recombinant IL-2, conjugated with a fluorescein dye was used in conjunction with flow cytometric analysis to determine changes in surface expression of IL-2R at sequential times over a 48-h period of in vitro stimulation. Surface expression of IL-2R was detected on manatee PBMC, which also cross-reacted with an anti-feline pan T-cell marker. An expression index (EI) was calculated by comparing mitogen-activated and non-activated PBMC. Based on side- and forward-scatter properties, flow cytometric analysis showed an increase in the number of larger, more granular "lymphoblasts" following concanavalin A (Con A) stimulation. The appearance of lymphoblasts was correlated with an increase in their surface expression of IL-2 receptors. Surface IL-2R expression, in Con A-stimulated PBMC, was detected at 16 h, peaked at 24-36 h, and began to decrease by 48 h. Characterization of the IL-2R expression should provide additional information on the health status of manatees, and the effect of their sub lethal exposure to brevetoxin.

Animals↗

PubMed2001

Ultrastructure of the spermatozoa from a Florida manatee (Trichechus manatus latirostris).

Semen was opportunistically collected from a free-ranging, 10-year-old, 275 cm (total length) Florida manatee (Trichechus manatus latirostris) during rehabilitation treatments. Ultrastructure of the spermatozoa was examined by scanning and transmission electron microscopy and differed slightly from that described for other mammals. Comparisons to the manatee's closest phylogenetic relatives, the elephant and hyrax, were made. The manatee spermatozoa had a similar acrosome but a distinct annulus and lacked the dense bodies observed in the neck of the elephant spermatozoa. Additionally, manatee spermatozoa lacked the lateral vacuoles observed in the nuclear chromatin from of the hyrax spermatozoa. These data add to our understanding of manatees and allow for comparative studies with other species that may be useful in phylogenetic and reproductive studies.

Animals↗

PubMed2002

Gross and microscopic observations on the lingual structure of the Florida Manatee Trichechus manatus latirostris.

The tongue of the Florida manatee (Trichechus manatus latirostris) was studied macroscopically, light and electron microscopically. The tongue was slender, muscular and firmly fixed in the oral cavity; only the cranial tip was free and mobile. Numerous filiform papillae were distributed over the dorsal surface of the rostral tongue. Multiple raised, round fungiform-like papillae were distributed over most of the dorsum. Typical fungiform papillae were restricted to the lateral margins of the tongue. Foliate papillae, presenting as multi-fossulate openings, were noted on the caudolateral margins. Open pits were located on the dorsocaudal surface and lateral walls. Microscopic examination showed that most of the lingual dorsum was covered with a thick stratified squamous epithelium. Open pits led to well-developed mucous salivary glands. Glands within the foliate papillae were mostly mucous, although some seromucous glands were present. Taste buds were restricted to the epithelium of the foliate papillae. Throughout the tongue, striated muscle was abundant below the epithelium. Blood vessels, lymph channels and nerve fibres were freely distributed throughout the intermuscular stroma. Nerve fibres reacted positively with neurone specific enolase (NSE) antibody throughout the tongue, including nerve bundles, glands and taste buds. Clear to translucent vacuoles were found juxtaposed to nuclei in the stratum spinosum in the foliate papillae epithelium.

Animals↗

PubMed2003

Vascular adaptations for heat conservation in the tail of Florida manatees (Trichechus manatus latirostris).

Although Florida manatees (Trichechus manatus latirostris) have relatively low basal metabolic rates for aquatic mammals of their size, they maintain normal mammalian core temperatures. We describe vascular structures in the manatee tail that permit countercurrent heat exchange (CCHE) to conserve thermal energy. Approximately 1000 arteries juxtaposed to 2000 veins are found at the cranial end of the caudal vascular bundle (CVB); these numbers decrease caudally, but the 1:2 ratio of arteries to veins persists. Arterial walls are relatively thin when compared to those previously described in vascular countercurrent heat exchangers in cetaceans. It is assumed that CCHE in the CVB helps manatees to maintain core temperatures. Activity in warm water, however, mandates a mechanism that prevents elevated core temperatures. The tail could transfer heat to the environment if arterial blood delivered to the skin were warmer than the surrounding water; unfortunately, CCHE prevents this heat transfer. We describe deep caudal veins that provide a collateral venous return from the tail. This return, which is physically outside the CVB, reduces the venous volume within the bundle and allows arterial expansion and increased arterial supply to the skin, and thus helps prevent elevated core temperatures.

Adaptation, Physiological↗

PubMedDate not supplied

Three-dimensional reconstruction of the angioarchitecture of the ciliary body of the West Indian manatee (Trichechus manatus).

OBJECTIVE: To examine the angioarchitecture of the ciliary body in the West Indian manatee (Trichechus manatus), through the use of three-dimensional reconstruction. PROCEDURE: Specimens from West Indian manatee were preserved in 10% buffered formalin, embedded in paraffin, serial sectioned and stained by Masson trichrome for light microscopic three-dimensional reconstruction and evaluation. RESULTS: The network of blood vessels in the ciliary processes of the West Indian manatee is fed by the major arterial circle that lies mostly near the base of the iris. The branching arterioles give rise to a capillary-sinusoidal bed that extends internally along each process, emptying into two sets of veins, one being elevated. The elevated and nonelevated veins join posteriorly before emptying into the choroidal venous system. CONCLUSIONS: The angioarchitecture of the ciliary body of the West Indian manatee is clearly unique when compared to those previously examined in land mammals. Three-dimensional reconstruction of paraffin sections is an effective means to evaluate vascular patterns in ocular specimens, especially those unavailable for corrosion casting.

Animals↗

PubMedDate not supplied

Comparative anatomy of the ciliary body of the West Indian manatee (Trichechus manatus) and selected species.

OBJECTIVE: To examine the anatomy of the ciliary body in the West Indian manatee (Trichechus manatus), paying close attention to its vascularization and to compare to those of its distant relative, the African elephant (Loxodonta africana), the amphibious hippopotamus (Hippopotamus amphibius) and the aquatic short-finned pilot whale (Globicephala macrorhynchus). PROCEDURE: Specimens from each species were preserved in 10% buffered formalin, and observed stereomicroscopically before being embedded in paraffin, sectioned and stained by Masson trichrome, hematoxylin and eosin, and periodic acid-Schiff for light microscopic evaluation. RESULTS: The network of blood vessels in the ciliary processes of the West Indian manatee appear to have an intricate pattern, especially with regard to venous outflow. Those of the elephant are slightly less complex, while those of the hippopotamus and whale have different vascular patterns within the ciliary body. Musculature within the ciliary body is absent within the manatee and pilot whale. CONCLUSIONS: In general, there appears to be a direct relationship between the increased development of vasculature and the loss of musculature within the ciliary bodies of the aquatic and amphibious mammals presently studied. Specifically, the ciliary body of the West Indian manatee has a comparatively unique construction, especially with regard to its vasculature.

Animals↗

PubMed1999

Estimation of water turnover rates of captive West Indian manatees (Trichechus manatus) held in fresh and salt water.

The ability of West Indian manatees (Trichechus manatus) to move between fresh and salt water raises the question of whether manatees drink salt water. Water turnover rates were estimated in captive West Indian manatees using the deuterium oxide dilution technique. Rates were quantified in animals using four experimental treatments: (1) held in fresh water and fed lettuce (N=4), (2) held in salt water and fed lettuce (N=2), (3) acutely exposed to salt water and fed lettuce (N=4), and (4) chronically exposed to salt water with limited access to fresh water and fed sea grass (N=5). Animals held in fresh water had the highest turnover rates (145+/-12 ml kg-1 day-1) (mean +/- s.e.m.). Animals acutely exposed to salt water decreased their turnover rate significantly when moved into salt water (from 124+/-15 to 65+/-15 ml kg-1 day-1) and subsequently increased their turnover rate upon re-entry to fresh water (146+/-19 ml kg-1 day-1). Manatees chronically exposed to salt water had significantly lower turnover rates (21+/-3 ml kg-1 day-1) compared with animals held in salt water and fed lettuce (45+/-3 ml kg-1 day-1). Manatees chronically exposed to salt water and fed sea grass had very low turnover rates compared with manatees held in salt water and fed lettuce, which is consistent with a lack of mariposia. Manatees in fresh water drank large volumes of water, which may make them susceptible to hyponatremia if access to a source of Na+ is not provided.

Animals↗