Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Elephants”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed2006

The role of foraging behaviour in the sexual segregation of the African elephant.

Elephants (Loxodonta africana) exhibit pronounced sexual dimorphism, and in this study we test the prediction that the differences in body size and sociality are significant enough to drive divergent foraging strategies and ultimately sexual segregation. Body size influences the foraging behaviour of herbivores through the differential scaling coefficients of metabolism and gut size, with larger bodied individuals being able to tolerate greater quantities of low-quality, fibrous vegetation, whilst having lower mass-specific energy requirements. We test two distinct theories: the scramble competition hypothesis (SCH) and the forage selection hypothesis (FSH). Comprehensive behavioural data were collected from the Pongola Game Reserve and the Phinda Private Game Reserve in South Africa over a 2.5-year period. The data were analysed using sex as the independent variable. Adult females targeted a wider range of species, adopted a more selective foraging approach and exhibited greater bite rates as predicted by the body size hypothesis and the increased demands of reproductive investment (lactation and pregnancy). Males had longer feeding bouts, displayed significantly more destructive behaviour (31% of observations, 11% for females) and ingested greater quantities of forage during each feeding bout. The independent ranging behaviour of adult males enables them to have longer foraging bouts as they experience fewer social constraints than females. The SCH was rejected as a cause of sexual segregation due to the relative abundance of low quality forage, and the fact that feeding heights were similar for both males and females. However, we conclude that the differences in the foraging strategies of the sexes are sufficient to cause spatial segregation as postulated by the FSH. Sexual dimorphism and the associated behavioural differences have important implications for the management and conservation of elephant and other dimorphic species, with the sexes effectively acting as distinct "ecological species".

Animals↗
PubMed1995

Morphology of the deciduous tusk (tush) of the African elephant (Loxodonta africana).

The tusk of the African elephant is preceded by a deciduous tooth generally known as the tush. Tushes from nine elephant fetuses and six calves younger than 1 year were exposed by dissection and described morphologically. All tushes consisted of a crown, root and pulpal cavity, the formation of which is completed soon after birth. They reached a maximum length of 5 cm, appeared not to erupt through the skin and were pushed aside and resorbed during enlargement of the distally located primordium of the tusk. Dental enamel, which covered the crown, could easily be removed and consisted of rods with an interwoven arrangement; the dentine-enamel junction was flat. Cellular cementum extended for variable distances over the crown and the dentine was tubular in nature. Although the tush apparently has no function, it provides the anlage and orientation for the development of its permanent successor.

Animals↗
PubMed1977

Primary structures of alpha-crystallin A chains of elephant, whale, hyrax and rhinoceros.

As part of a study of the evolutionary development of the eye lens protein alpha-crystallin the 173-residue A chain of this protein has been studied in elephant, whale, hyrax and rhinoceros. The primary structures were inferred mainly from amino acid compositions of peptides obtained by enzymic digestions and CNBr cleavage. The positions of substitutions, as compared to the known bovine A chain, were confirmed by Edman degradation. In accordance with the previously observed slow rate of evolution of the A chain only a small number of substitutions was found among these species. Elephant and hyrax share a number of unique substitutions, strongly indicating a common ancestry of these two species within the mammalian class.

Amino Acid Sequence↗
PubMedDate not supplied

Arteriosclerosis in the African elephant: Part 2. Medial sclerosis.

SUMMARY: A type of spontaneous arteriosclerosis, described as medial sclerosis and quite distinct from atherosclerosis, was found in the aortas, coronary arteries and aortic branch arteries of free-living elephants (Loxodonta africana) in Uganda and Kenya. The lesions took the form of calcified fibrotic plaques in the inner tunica media. The calcification appeared to commence in the internal elastic lamina and was associated with atrophy of medial smooth muscle fibres and their replacement by fibrous tissue. In the aorta, medial sclerosis was found to be associated with aortic dilatation, decreased wall thickness and decreased extensibility. These changes were shown to result in substantial increases in the tangential stresses carried by the tissues of the aorta and coronary arteries. As with atherosclerosis, medial sclerosis increased progressively with age; and the approximate involvement of the aorta at different ages could be predicted from linear regression equations. There was no difference in the severity of lesions between male and female animals. Biochemically, the lesions of medial sclerosis were associated with decreased amounts of elastin and increased amounts of collagen in arterial walls. Arterial tissue showing medial calcification always contained less than 30% elastin by weight. In addition, the severity of medial sclerosis in individual elephants was found to be positively correlated with the concentration of calcium in their sera. The pathogenesis of these lesions is discussed and it is suggested that mechanical stress, medial anoxia and high serum calcium levels all contribute to the aetiology of medial sclerosis.

Africa, Eastern↗
PubMed1990

Longitudinal study of haematological and biochemical constituents in blood of the Asian elephant (Elephas maximus).

1. Haematological parameters and biochemical analytes were determined in four elephants over a period of one year. 2. The haematological profile remained constant over time and was similar between animals. 3. Values for biochemical analytes were stable except for alkaline phosphatase, gamma glutamyl transferase and creatinine which rose during musth in male elephants. 4. The association of elevated enzyme levels with increased testosterone concentrations is discussed.

Alkaline Phosphatase↗
PubMed1992

Heat exchange by the pinna of the African elephant (Loxodonta africana).

1. Surface temperatures of the pinnae of four female African elephants were measured at ambient temperatures between 14 and 32 degrees C using infrared thermography. Instantaneous heat losses calculated using those values ranged from 10.67 to 76.2 W under the observed conditions. 2. Using a value of 17 kcal/kg/day, those heat losses account for 0.65-4.64% of the animals' standard metabolic rates, considering one side of one ear only. 3. A model of heat flow across a flat vertical plate was constructed and compared to the actual values. Up to 100% of an African elephant's heat loss needs can be met by movement of its pinnae and by vasodilation. 4. Thermography indicates that the temperature distribution pattern across the pinna changes with ambient temperature and that areas of specialized motor control exist.

Animals↗
PubMed2006

Structural determination of the oligosaccharides in the milk of an Asian elephant (Elephas maximus).

Milk of an Asian elephant (Elephas maximus), collected at 11 days post partum, contained 91 g/L of hexose and 3 g/L of sialic acid. The dominant saccharide in this milk sample was lactose, but it also contained isoglobotriose (Glc(alpha1-3)Gal(beta1-4)Glc) as well as a variety of sialyl oligosaccharides. The sialyl oligosaccharides were separated from neutral saccharides by anion exchange chromatography on DEAE-Sephadex A-50 and successive gel chromatography on Bio Gel P-2. They were purified by high performance liquid chromatography (HPLC) using an Amide-80 column and characterized by 1H-NMR spectroscopy. Their structures were determined to be those of 3'-sialyllactose, 6'-sialyllactose, monofucosyl monosialyl lactose (Neu5Ac(alpha2-3)Gal(beta1-4)[Fuc(alpha1-3)]Glc), sialyl lacto-N-neotetraose c (LST c), galactosyl monosialyl lacto-N-neohexaose, galactosyl monofucosyl monosialyl lacto-N-neohexaose and three novel oligosaccharides as follows: Neu5Ac(alpha2-3)Gal(beta1-4)[Fuc(alpha1-3)]GlcNAc(beta1-3)Gal(beta1-4)Glc, Neu5Ac(alpha2-6)Gal(beta1-4)GlcNAc(beta1-3)Gal(beta1-4)GlcNAc(beta1-3)Gal(beta1-4)Glc, and Neu5Ac(alpha2-3)Gal(beta1-4)[Fuc(alpha1-3)]GlcNAc(beta1-3)Gal(beta1-4)[Fuc(alpha1-3)]GlcNAc(beta1-3)Gal(beta1-4)Glc. The higher oligosaccharides contained only the type II chain (Gal(beta1-4)GlcNAc); this finding differed from previously published data on Asian elephant milk oligosaccharides.

Animals↗
PubMed2005

Milk composition of a free-ranging African elephant (Loxodonta africana) cow during early lactation.

Only one study previously reported comprehensively on the composition of African elephant's (Loxodonta africana) milk that was collected from 30 dead animals. In the current study milk was obtained from a tame but free-ranging African elephant cow without immobilization during the period when she was 4-47 days postpartum. At the respective collection times the nutrient content was 21.8 and 25.0 g protein; 56.0 and 76.0 g fat; 71.1 and 26.0 g sugars per kilogram of milk. The protein fraction, respectively, consisted of 10.0 and 14.0 g caseins/kg milk and of 11.8 and 11 g whey proteins/kg milk. During lactation the lactose content dropped from 52.5 to 11.8 g/kg milk, while the oligosaccharide content increased from 11.8 to 15.2 g/kg milk. The oligosaccharide was characterized as a galactosyllactose, which is digestible by cellulase. Electrophoresis and identification of protein bands showed a similar migrating sequence of proteins as seen in cow's milk, but some of the corresponding proteins were less negatively charged. The lipid fraction contains a high content of capric and lauric acids, approximately 60% of the total fatty acids, and low content of myristic, palmitic and oleic acids.

Albumins↗
PubMed2006

Elephant dung decomposition and coprophilous fungi in two habitats of semi-arid Botswana.

In order to understand the impact of habitat changes on ecosystem processes caused by increased populations of elephants, elephant dung decomposition was studied in semi-arid Botswana. Dung decomposition rates were studied with and without the presence of arthropods, using pairs of exposed dung and dung enclosed in nylon-mesh bags, respectively. Dung decomposition rates were lower in the absence of arthropods. The rates in the late wet season were higher in the scrubland than in the woodland. In the early dry season, immediately after the wet season, the rates were higher in the woodland than in the scrubland. The difference in decomposition rates between habitats was attributed to microclimatic conditions created by vegetation cover. With regard to fungal succession, Cladosporium cladosporioides and Eurotium brefeldianum occurred only in the late stages of dung decomposition whereas Talaromyces helicus, Cercophora coprophila and Sporormiella minima occurred in all the stages. Although there was no significant difference in Shannon-Weiner fungal species diversity index between habitats, seasons, dung ages and laboratory incubation periods, there were significant differences in fungal community composition between these parameters. Species richness was higher in the late wet season than in the early dry season, indicating the importance of moist conditions for a large diversity of fungal species.

Animals↗
PubMed2005

Placentation in the African elephant, Loxodonta africanus: III. Ultrastructural and functional features of the placenta.

Successful transfer of nutrients to the elephant fetus during pregnancy relies on a variety of placental modifications. Our light and electron microscopical investigations show that the structure is endotheliochorial from implantation to term, with unicellular, never syncytial trophoblast. Light and electron microscope immunocytochemistry shows the restriction of the glucose transporter 1 isoform to the basolateral surfaces of the trophoblast, with the glucose transporter 3 restricted to the apical plasmalemma of the trophoblast. Glucose transport to the fetus therefore requires a sequential use of both isoforms. Light and electron microscope cytochemistry indicate the presence of iron deposits only in the haemophagous zones confirming their iron transport function. No trophoblast areas with high concentrations of Calcium binding protein, specialised for Calcium transport were found. In situ hybridisation demonstrated the presence of IGF-II mRNA in the trophoblast from the earliest stage, with TGFbeta1 and HGF-SF mRNA expressed subsequently but only IGF-II and HGF mRNA present in the second half of pregnancy. The results are briefly discussed in terms of placental growth and function and indicate that the elephant placenta is another example of a unique solution to the variety of problems posed by a resident fetus.

Animals↗
PubMed1998

Histogenesis of the chequered pattern of ivory of the African elephant (Loxodonta africana).

This study aimed to propose a hypothesis on the events which lead to the development of the characteristic chequered pattern of elephant ivory. Twenty fragments of ivory and six elephant tusks were obtained through the National Parks Board of South Africa. Polished surfaces were prepared in sagittal and longitudinal planes and the characteristics of the distinctive chequered pattern described. Light- and electron-microscopical techniques and image analyses were employed to determine the morphological basis of the pattern and to describe the spatial distribution, density and morphology of the dentinal tubules. These investigations showed that the distinctive pattern was the result of the sinusoidal, centripetal course followed by dentinal tubules. The apical, slanted part of the sinusoidal curve is the result of the centripetally moving odontoblast, which, during formation of ivory, progresses towards the centre of the tusk on a decreasing circumference. It is suggested that this leads to cell crowding, increased pressure between odontoblasts and subsequent apical movement of their cell bodies, cell degeneration and fusion. Odontoblastic degeneration and fusion probably relieve the pressure between the crowded odontoblasts by reducing their numbers and the remaining odontoblasts now orientate their centripetal course towards the tip of the tusk, thereby forming the anterior-directed part of the sinusoidal path of the tubule. As odontoblasts progress centripetally the diameter of the pulpal cavity decreases further and the processes of apical movement, fusion and degeneration of odontoblasts are repeated. This occurs until the pulpal cavity is obliterated.

Anatomy, Cross-Sectional↗
PubMed2002

Medetomidine a novel immobilizing agent for the elephant (Elephas maximus).

Medetomidine was injected by the intramuscular route at the rates of 3 and 5 microg/kg body weight into two groups of Indian elephants (Elephas maximus). Sedation was induced at 6.20 (0.81) and 5.90 (0.60) min respectively after injection. The duration of anaesthesia was 66.20 (10.4) and 134.20 (24.12) min, respectively and recovery occurred at 125.80 (25.23) and 205.89 (29.3) min. The notable signs of sedation exhibited by the elephants were protrusion of penis, complete relaxation of trunk, flaccidity of tail and drooping of the ears with a head down position. During sedation, physiological parameters recorded were bradycardia, decreased respiration and hypothermia.

Adrenergic alpha-Agonists↗
PubMed1997

The elephant's respiratory system: adaptations to gravitational stress.

Elephants have had to adapt to gravitational stresses imposed on their very large respiratory structures. We describe some unusual features of the elephant's respiratory system and speculate on their functional significance. A distensible network of collagen fibers fills the pleural space, loosely connects lung to chest wall but appears not to constrain lung-chest wall movements. Myriad spaces within the network and its rich supply of capillaries suggest effective local sources and sinks for pleural fluid that may replace the gravity-dependent flows of smaller mammals. The lung is partitioned into approximately equal to 1 cm3 parenchymal units by a system of thick, elastic septa that ramify throughout the lung from origins on the lung's elastic external capsule. Parenchymal units suspended upon the elastic septal system protect dependent alveoli from compression, thereby reducing the usual gravitational gradient of lung expansion. Intra-pulmonary airways are devoid of cartilage, instead they appear to derive resistance to collapse from tethering forces of the attached septa.

Adaptation, Physiological↗
PubMed2001

Immunolocalization of zona pellucida antigens in the ovarian follicle of dogs, cats, horses and elephants.

A comparative evaluation of the location of immunoreactive porcine zona pellucida (pZP) glycoproteins was performed with polyclonal rabbit anti-pZP antibodies on ovarian sections of the dog, cat, horse, and elephant. For this, formalin (light microscopy) and glutaraldehyde (transmission electron microscopy [TEM]) fixed ovarian sections were incubated with antibodies raised against highly purified pZP. Staining patterns were determined with diaminobenzidine (DAB) at the light level. The dog ZP had a distinct staining distribution that is characterized by intense staining around the periphery of the ZP and the oolemma and less dense staining throughout the width of the ZP. In dog follicles that contained multiple oocytes, there were oocytes of identical and dissimilar stages. Cat ovarian sections showed uniform staining of the ZP. Horse results showed uniform staining of ZP and ooplasm, and granulosa cells (GC). Elephant sections showed staining of the ZP with dense staining at the oolemma, as well as staining of the ooplasm. In all species the staining of the ZP was not evident until GC differentiation. In all cases there was no staining of ovarian tissue with control normal rabbit serum. Specific staining patterns of ZP were evaluated by TEM and immunogold staining. The immunogold-linked anti-pZP antibodies stained the ZP matrix in all species. There was staining of ooplasm organelles suggesting that ZP secretion originates from the oocyte of the dog and cat. In addition, follicular and ZP measurements were taken that allowed accurate characterization of follicle stage. These findings suggest that in all four species the ZP is recognized by anti-pZP antibodies and there is also evidence to suggest the possible origins of ZP glycoproteins.

Animals↗
PubMed2003

Placentation in the African elephant (Loxodonta africana): II morphological changes in the uterus and placenta throughout gestation.

The gross and microscopic development of the zonary endotheliochorial placenta in the African elephant was studied in 22 gravid uteri that ranged in gestational stage from 0.5 to 20.6 months. The conceptus only ever occupies one horn of the uterus and is associated with 2-5 large corpora lutea that persist in the ipsilateral ovary throughout gestation. Initially, the trophoblast in the equatorial region of the conceptus completely replaces the lumenal epithelium of the endometrium to which it is apposed. Blunt upgrowths of endometrial stroma then develop, each closely invested by trophoblast, and containing the capillaries that will vascularize this maternal component of the resulting placental band. With advancing gestation the lamellate stromal upgrowths increase markedly in length and become much thinner, thereby bringing the trophoblast into intimate contact with the endothelium of the maternal capillaries. They also become folded or pleated to increase the total area of intimate feto-maternal contact. At the lateral edges of the placental band the lamellae bend over towards the endometrium to form a blind cleft. Leakage of blood into this area creates haemophagous zones in which phenotypically specialized trophoblast cells phagocytose the blood components. The presence of large resorbing blood clots and circumferential scars in the uteri of three post parturient animals initiated the hypothesis that, when the standing elephant gives birth at term, the passage of the 120 kg fetus through the vagina may wrench the placenta off the endometrium by severing its very narrow maternal placental hilus. The resulting intrauterine haemorrhage may then play a role in preventing further conception for around 2 years.

Animals↗
PubMed1998

Isolation and characterisation of immunoglobulin g and IgG subclasses of the African elephant (Loxodonta africana).

Immunoglobulins were precipitated from pooled African elephant sera with ammonium sulphate and separated by gel filtration and fast protein liquid chromatography (ion exchange). Analysis of the fractions by SDS-PAGE showed IgG of 150 kDa with up to five subclasses, each having heavy chains of 57 kDa and light chains of 27 kDa. Three monoclonal antibodies against human IgG and polyclonal antibodies against canine, bovine, cameline, equine, phocine and feline IgG showed strong cross-reactivity with the African elephant IgG subclasses. No serum molecules corresponding to IgM or IgA could be detected, even when ammonium sulphate precipitation was used at 50% saturation.

Animals↗
PubMed1998

The efficacy of an experimental oil-adjuvanted encephalomyocarditis vaccine in elephants, mice and pigs.

An oil-adjuvanted inactivated encephalomyocarditis (EMC) vaccine was developed to protect a wild population of elephants against a natural outbreak of disease. The experimental vaccine was initially tested for efficacy by challenging mice and pigs. Mice showed protection against challenge and pigs developed high antibody levels. Since both vaccinated and control pigs failed to develop clinical disease, apparently due to the low virulence of the strain in this species, protection in pigs could not be evaluated. Vaccinated elephants developed high antibody titers which protected all vaccinates from a challenge roughly two months post-vaccination, whereas controls developed fatal or sub-clinical myocarditis. This is the first report of an inactivated EMC vaccine inducing high antibody titers in domestic and wild animal species. Due to the potency of this vaccine and the acceptability of the oil adjuvant used, it has potential for use in animals in zoological collections as well as in the pig industry.

Adjuvants, Immunologic↗
PubMed2002

Utility of maternal serum total testosterone analysis for fetal gender determination in Asian elephants (Elephas maximus).

It has been shown in some species that fetal testes produce testosterone early in gestation. This study investigated the possibility that fetal testosterone may be reflected in maternal serum levels in the Asian elephant (Elephas maximus). Weekly serum samples were collected from seventeen pregnant captive Asian elephants and analyzed via radioimmunoassay (RIA) for total testosterone levels. Nine of the cows carried male fetuses and eight carried female fetuses. A non-random pattern over time (P<0.01) was observed in cows carrying either a male or female fetus. Mean maternal serum total testosterone was significantly higher in cows carrying male versus female fetuses (P<0.01). Mean trimester values indicate that first trimester values are not significantly different among male versus female groups. The second and third trimester values of cows carrying male fetuses were higher than cows carrying female fetuses, (P<0.01 and <0.05, respectively). The results of this study show that it is possible via RIA of maternal serum for total testosterone to determine the gender of calves during gestation.

Animals↗