Purification and functional characterization of pancreatic insulin from camel (Camelus dromedarius)

Large-scale production of insulin still represents the key step in helping diabetic patients throughout the world. Many species and approaches have been used for the production of insulin. In this study, we purified and characterized for the first time pancreatic insulin from the Arabian camel (Camelus dromedarius) using a modified acid-alcohol extraction method. After extraction insulin was purified using a one-step gel filtration on a Sephadex G-50 column leading to a purification yield of 80 mg/kg (20%) of camel pancreas. The purity of camel insulin was assessed by SDS–PAGE and HPLC using insulin from human, bovine and porcine as standards. Molecular weight was determined for purified camel insulin as 5800 Daltons and its amino acid composition is similar to that known for other species. The functional characterization of purified crude camel insulin was demonstrated in vitro by positive competition by radioimmunoassay and in vivo showing camel insulin inducing acute hypoglycaemia in mice. Together, our study reports for the first time the successful purification of functional insulin from camel pancreas with similar properties compared to other insulin species. This is of great interest given that the camel represents considerable economic worth in many countries.     

Spermatogenesis in the camel (Camelus dromedarius)

Spermatogenesis was studied with the aid of the light and electron microscopes in fourteen sexually mature camels slaughtered at different times of the year. The testes were fixed by vascular perfusion with glutaraldehyde. Spermatogenesis in the camel was generally similar to that of most mammalian species, although some features specific for the camel were observed. Spermatogenesis was found to be continuous throughout the year.     

The locomotion of the camel (Camelus dromedarius)

The feet and gaits of many camels Camelus dromedarius were studied and filmed in Mauritania, Africa. The camel has a digitigrade stance, large feet to support the animal in soft sand, and soles of flexible pads that step readily onto small stones where necessary. The walking stride is long and slow, with the body supported for much of each stride on the two right or two left legs. The pattern of supporting legs was significantly different in slow compared to fast walking camels, and in young compared to adult camels and compared to adults pulling water at the wells. There was no difference in pattern in one individual's walk, when it was either loaded or unloaded. The angles that the leg bones made with each other and with the horizon are depicted for the walk and the pace. The camel is the only animal which paces often and never trots. The pace is an unstable gait only suitable for flat terrain such as that in deserts. It may have evolved from the pace-like walk which is by far the dominant gait in this animal, which spends most of each day walking from plant to plant browsing or grazing. The pace is not used by all camelids, as one author has claimed. The pace and the gallop were only used by the camels at wells, when the animals were chased from the water by men.     

Genotypic characterization of Iranian camel (Camelus dromedarius) isolates of Echinoccocus granulosus

In the present study, Echinoccocus granulosus isolates collected from camels (Camelus dromedarius) in eastern Iran were characterized based on the nucleotide sequences of mitochondrial CO1 and NDI genes. The molecular results for camel isolates demonstrated that at least 2 different genotypes are present, i.e., a buffalo genotype (G3) and the camel genotype (G6). Although the sequences of the Iranian camel genotype (G6) are completely homologous to the reference sequence of G6 (M84666) of E. granulosus , a nucleotide mutation (C to T at position 168) was detected in the CO1 sequences of the Iranian G3 isolates (HM626405) when compared with the reference G3 genotype (M84663). The findings of the present study represent the demonstration of the buffalo strain in camels. As previously reported, humans can be infected by this genotype; accordingly, the epidemiological importance of this genotype in the camel population should be considered in further studies.     

Fine structure of sertoli cells in the camel (Camelus dromedarius)

The testes of fourteen sexually mature camels were fixed by perfusion with glutaraldehyde. The fine structure of Sertoli cells and of their surface specializations towards other Sertoli cells and towards germ cells is described. Sertoli cell nucleolar vacuoles, like those described in several ruminant species, were not found. The general appearance of the camel Sertoli cell suggests that its function is similar to that of other mammals.     

Forestomach motility in the camel (Camelus dromedarius)

There is a cyclical pattern of motility in compartments 1 and 2 of the forestomach of the camel which can be categorized into A- and B-contractions. An average motility cycle is composed of 7 A- and 5 B-contractions and lasts 5 min, including a pause of 2.3 min. The glandular sacs within the caudal sac of compartment 1 contract 1.7 sec earlier than the caudal sac. The proximal part of the canal between compartment 2 and 3 contracts 1.2 sec prior to the distal part. Forestomach motility is stimulated by distention of the cranial sac of compartment 1 and inhibited by distention of the tubiform portion of compartment 3.     

Carbohydrases in camel (Camelus dromedarius) pancreas. Purification and characterization of glucoamylase

The present study analyzed the existence of carbohydrases in camel pancreas compared to some other ruminants. Disaccharidases (maltase, cellobiase, lactase, trehalase and sucrase), glucoamylase and alpha-amylase were detected in pancreas of camel, sheep, cow and buffalo. Enzyme levels in sheep were lower than in the other ruminants. The highest level was detected for alpha-amylase (EC 3.2.1.2). Moderate activity levels were detected for glucoamylase (EC 3.2.1.3) and maltase (EC 3.2.1.20), while other disaccharidases showed very low activity. The results suggested that, in addition to alpha-amylase, glucoamylase and maltase may be synthesized and secreted from pancreas to the small intestine in ruminants. Camel pancreatic glucoamylase was purified and characterized. The purification procedure included glycogen precipitation and chromatography on DEAE-Sepharose and Sepharose 6B. The molecular mass was 58 kDa for native and denatured enzyme using gel filtration and SDS-PAGE, respectively. The enzyme had a pH optimum at 5.5 and a Km of 10 mg starch/mL with more affinity toward potato soluble starch than the other carbohydrates. Glucoamylase had a temperature optimum at 50 degrees C with heat stability up to 30 degrees C. The effect of different cations and inhibitors was examined. The camel pancreatic glucoamylase may possess an essential thiol.     

Purification and characterization of cationic chymotrypsin from the pancreas of the Arabian camel (Camelus dromedarius)

This study reports on the purification and characterization of a cationic enzyme with chymotryptic activity from camel pancreas. The enzyme was purified 52-fold in a 48% yield by a three-step chromatographic procedure consisting of anion-exchange, cation-exchange and affinity chromatographies. The purified enzyme was homogeneous on gel isoelectric focusing and on SDS gel electrophoresis. Its isoelectric point was estimated to be 7.3 and its molecular mass was found to be 23,600 Da. The enzyme was identified as a cationic chymotrypsin according to its physiochemical properties, substrate specificity and susceptibility to inhibition. It was active towards esters of aromatic amino acids but much less active towards a leucine ester. In all cases, the k_cat values of the camel enzyme were less than the corresponding values of bovine chymotrypsin A. It also showed a lower level of kininase activity. Camel chymotrypsin was more susceptible than its bovine equivalent to inhibition by soybean trypsin inhibitor and aprotinin. It showed the same pH optimium as bovine chymotrypsin A for its esterolytic activity, but was more dependent on CaCl₂ for long-term stability.     

Offspring resulting from transfer of cryopreserved embryos in camel (Camelus dromedarius)

The dromedary embryos, collected at hatched blastocyst stage, survived freezing and thawing in the presence of a high concentration of ethylene glycol (7.0 mol/L) with sucrose (0.5 mol/L) and direct plunging in liquid nitrogen. The rate of survival, as judged by the morphological appearance of the embryos after thawing, was high (92%). The transfer of frozen-thawed embryos into the recipients during the breeding (n=20) and non-breeding season (n=25) resulted in two and one pregnancy, respectively. One of the two pregnant recipients, with embryos transferred during the breeding season, delivered a normal healthy male calf at term. To our knowledge, this offspring is the first camelid produced following transfer of a frozen-thawed embryo.     

The intratesticular excurrent ducts of the camel (Camelus dromedarius)

The histology and fine structure of the epithelial cells of the intratesticular excurrent ducts were studied in material collected from fourteen adult camels and fixed by perfusion. The intratesticular excurrent ducts consisted of a terminal segment of the seminiferous tubule, a tubulus rectus, and a rete testis. The terminal segment was lined with modified Sertoli cells which formed a plug-like structure in the receptacle. The tubulus rectus was subdivided into the receptacle, the narrow main part, and the wider distal part, and these parts were lined with different types of epithelium. The rete testis occupied an axial mediastinum testis, and the height of its epithelium varied quite considerably. Degenerated spermatozoa were seen engulfed by the epithelial cells of the entire intratesticular duct system. Light cells, lymphocytes, and macrophages were observed. The fine structure of the epithelium of the intratesticular ducts is discussed in relation to its possible functions.     

Control of luteolysis in the one-humped camel (Camelus dromedarius)

Blood plasma concentrations of 13,14-dihydro-15-keto PGF2 alpha (PGFM) were measured in groups of mature non-pregnant and pregnant camels to study PGF2 alpha release patterns around the time of luteolysis and the timing of the signal for pregnancy recognition. Injection of each of four camels with 10 and 50 mg of PGF2 alpha showed clearly that five times the dose of exogenous hormone produced five times the amount of PGFM in peripheral plasma, thereby indicating that, as in other animal species, PGFM is the principal metabolite of PGF2 alpha in the camel. Serial sampling of three non-pregnant camels on each of days 8, 10 and 12, and three pregnant camels on day 10, after ovulation for 8 h showed a significant (P < 0.05) rise in mean plasma PGFM concentrations only on day 10 in the non-pregnant, but not the pregnant, animals. A single intravenous injection of 20, 50 or 100 iu oxytocin given to three groups of three non-pregnant camels on day 10 after ovulation did not increase their basal serum PGFM concentrations. However, daily treatment of six non-pregnant camels between days 6 and 15 (n = 3) or 20 (n = 3) after ovulation with 1-2 g of the prostaglandin synthetase inhibitor, meclofenamic acid, inhibited PGF2 alpha release and thereby resulted in continued progesterone secretion throughout the period of meclofenamic acid administration. These results showed that, as in other large domestic animal species, release of PGF2 alpha from, presumably, the endometrium controls luteolysis in the dromedary camel. Furthermore, reduction in the amount of PGF2 alpha released is associated with luteal maintenance and the embryonic signal for maternal recognition of pregnancy must be transmitted before day 10 after ovulation if luteostasis is to be achieved. However, the results also indicate that, in contrast to ruminants, the release of endometrial PGF2 alpha in the non-pregnant camel may not be controlled by the release of oxytocin.     

Clinical and anatomical studies of the camel (Camelus dromedarius) genitalia

Clinical and anatomical studies of the genitalia of 294 camel (197 males and 97 females) were carried out between May 1984 and October 1985. Preslaughter (clinical) examination was followed by detailed post-mortem (anatomical) examination and dissection of genitalia at the abattoir. Measurements and weights of the various segments of genitalia were made to establish the baseline data for breeding soundness evaluation in the dromedary in Northern Nigeria.     

Purification of carnitine acetyltransferase from skeletal muscle of the camel (Camelus dromedarius)

The enzyme carnitine acetyltransferase (CAT) catalyzes the reversible transfer of short-chain acyl groups between coenzyme A and L-carnitine, and hence, plays an important role in the -oxidation of fatty acids. Purification and characterization of CAT from desert animal species may help in explaining the involvement of secondary pathways for energy production in these species. In this paper, we report the purification and partial characterization of CAT from the Arabian camel. CAT was purified from the skeletal muscle of the Arabian camel by ammonium sulfate and acetone fractionation, followed by chromatography on DEAF-Sepharose, agarose-Co A and Superose 12 gel filtration columns. CAT was purified by 2937-fold to a specific activity of 94 Units mg^–1. The purified CAT was a monomer of 59 kDa as judged by native and SDS-PAGE, and showed a pl of 5.2. The enzyme displayed maximum activity with propionyl-Co A. Apparent K_m for acetyl-, propionyl- and butyryl-Co A were 27.7, 17.3 and 29 M respectively, while palmitoyl-Co A was not a substrate.     

Comparison of virokine from camel pseudocowpoxvirus (PCPV) with Interleukin 10 of the Dromedary camel (Camelus dromedarius)

Cellular interleukin-10 (IL-10) gene from the peripheral blood mononuclear cells of the healthy Dromedary camel (Camelus dromedarius) and viral IL-10 (vIL-10) from the skin scabs of the Dromedary camels infected with contagious ecthyma (a parapoxviral infection in the camels) were amplified by polymerase chain reaction, cloned and characterized. Sequence analysis revealed that the open reading frame (ORF) of dromedarian camel IL-10 is 537 bp in length, encoding 178 amino acid polypeptide while open reading frame of vIL-10 from camel is 561 bp, encoding 187 amino acid polypeptide. The Dromedary camel IL-10 exhibited 62.6% and 68.5% sequence identity at the nucleotide and amino acid level, respectively, with vIL-10 from camel. Sequence analysis also revealed that the Dromedary camel IL-10 shared 99.4% and 98.3% identity at the nucleotide and amino acid level, respectively, with the Bactrian camel (Camelus bactrianus). But vIL-10 from camel shared 84.7% and 83.4% sequence identity at the nucleotide and amino acid level, respectively, with vIL-10 from reindeer (Rangifer tarandus), which is a ruminant species belonging to the order Artiodactyla. The present study was conducted to evaluate the evolutionary origin of the camel parapoxvirus with parapoxviruses of cattle and sheep and the resultant sequence analysis revealed that camel parapoxvirus is closely related to cattle parapoxvirus than sheep parapoxvirus (Orf virus).     

Fine structure of epididymal spermatozoa in the camel (Camelus dromedarius)

The epididymides from five sexually mature camels were fixed by vascular perfusion with glutaraldehyde, and the spermatozoa from four different regions were studied. The fine structure of the camel spermatozoon is similar to that of related species such as bulls and boars. It is relatively short and has a short middle piece. The main morphological changes during epididymal transit are confined to the acrosome and to the position and structure of the cytoplasmic droplet.     

Levels of glycosylated haemoglobin in the Arabian camel (Camelus dromedarius)

Proportions of glycosylated haemoglobin (Hb) were determined in 10 Arabian camels (Camelus dromedarius) and were compared with normal controls (n = 59) and diabetic patients (n = 47) using the thiobarbituric acid (TBA) method. The level of glycosylated haemoglobin (5.5%) in camels is significantly different from that of normal healthy humans (4.9%) (P less than 0.001). Whereas the glucose levels were comparable, this difference in percentages of glycosylated haemoglobin may be explained by the difference in survival time between human and camel red blood cells.     

A review of reproduction in the female camel (Camelus dromedarius)

The Arabian camel (Camelus dromedarius), the one-humped camel, is a primary inhabitant of the northern half of Africa, the Middle East and Pakistan and India. The dromedary is a multipurpose animal used for transportation, the production of milk and meat, as well as such by-products as wool, hair and hides. Dromedaries are extremely well adapted to their hot, arid environment. Consequently, Arabian camels are of considerable economic importance. Relatively little attention has been paid to the breeding of dromedaries. In the literature, particularly that in the English language, information on reproduction in the dromedary tends to be fragmentary. This review consolidates several widely scattered reports as projected against the author's own experience. It is hoped that the information is of particular help for those in charge of the breeding of dromedaries in zoological gardens and animal parks in countries where the one-humped camel is a rare species.     

The purification, characterization and regulatory properties of liver phosphofructokinase in the Arabian one-humped camel (Camelus dromedarius)

1. Phosphofructokinase from camel liver was purified to homogeneity more than 3600-fold, and the yield of the preparation was 46%. 2.The sodium dodecyl sulphate-treated purified enzyme migrated as a single band in 10% polyacrylamide gel. 3. The enzyme is a tetramer, with a monomer Mr 90,000. 4. The regulatory properties of the purified enzyme from camel liver were studied at pH 7.0. 5. The enzyme displayed cooperativity with respect to fructose 6-phosphate and was inhibited by high concentrations of ATP. 6. The enzyme was also inhibited by citrate, phosphocreatine and 2,3-bisphosphoglycerate. 7. On the other hand, ADP, AMP, glucose 1,6-bisphosphate and fructose 2,6-bisphosphate were all found to be strong activators for camel liver phosphofructokinase.