Control of luteolysis in the one-humped camel (Camelus dromedarius). (1/284)

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.  (+info)

Rumen ciliate protozoal fauna of native sheep, friesian cattle and dromedary camel in Libya. (2/284)

Rumen ciliate species and composition were surveyed on the native sheep, Friesian-cattle and dromedary (one-humped) camels kept in Libya. As a result of survey, 5 genera including 14 species with 5 formae in native sheep, 9 genera including 27 species with 6 formae in Friesian-cattle and 6 genera including 13 species and 7 formae in dromedary camels were identified. All of the ciliate species and their percentage composition detected from the Libyan sheep and cattle in this examination were similar to those found from corresponding animals in the other countries. Libyan camels lacked some peculiar ciliate species found from camels in the other countries, but had many cosmopolitan species common with those in the domestic ruminants, suggesting that ciliate faunae of camel are easily affected by the other domestic ruminants kept together. The ciliate density was estimated as 105/ml in every host species.  (+info)

Hybridizing Old and New World camelids: Camelus dromedarius x Lama guanicoe. (3/284)

Thirty female dromedary camels were inseminated on a total of 50 occasions with 2-4 ml of fresh guanaco semen diluted with an equal volume of commercially available camel semen extender. Similarly, nine female guanacos were inseminated on 34 occasions with 4-6 ml of fresh, diluted camel semen. Only two of the dromedary females conceived; one aborted a female foetus on day 260 of gestation and the other gave birth to a stillborn female calf on day 365. Six conceptions occurred in the female guanacos. Two of these conceptuses, diagnosed by ultrasound, were resorbed between days 25 and 40 of gestation, one female foetus was aborted on day 291, another female foetus was aborted on day 302, and one female calf was stillborn on day 365 of gestation. The sixth foetus, a male, was born prematurely but alive after a 328-day gestation. It had a phenotypic appearance intermediate between that of a camel and a guanaco and its hybrid parentage was confirmed by the DNA fingerprinting of eight llama microsatellites. To our knowledge, this is the first viable hybrid ever to be produced between Old World and New World camelids, which have been reproductively isolated from one another for at least 11 million years. The preponderance of female hybrids is in accordance with Haldane's law. Histological examination of their ovaries revealed a failure of meiosis, with only an occasional abnormal oocyte surrounded by follicle cells. Although the diploid chromosone number of camels and guanacos is the same (2n = 74), sufficient genetic change has taken place to make the pairing of homologous chromosomes no longer possible.  (+info)

Characteristics of a Kenyan camelpox virus. (4/284)

A virus was isolated from pock-like vesicular eruptions of camels in Northern Kenya. This virus was shown to be a pox virus with many characteristics of members of the Orthopox group. It appears to be identical with camelpox strains from Iran and has similar properties to certain East African variola strains.  (+info)

Isolation and structure of an untriakontapeptide with opiate activity from camel pituitary glands. (5/284)

The isolation of an untriakontapeptide from camel pituitary extracts has been described. Its structure has been determined and shown to be identical to the sequence of carboxyl-terminal 31 amino acids of ovine beta-lipotropin. The peptide possesses very low lipotropic activity but significant opiate activity.  (+info)

Camel heavy-chain antibodies: diverse germline V(H)H and specific mechanisms enlarge the antigen-binding repertoire. (6/284)

The antigen-binding site of the camel heavy-chain antibodies devoid of light chain consists of a single variable domain (V(H)H) that obviously lacks the V(H)-V(L) combinatorial diversity. To evaluate the extent of the V(H)H antigen-binding repertoire, a germline database was constructed from PCR-amplified V(H)H/V(H) segments of a single specimen of Camelus dromedarius. A total of 33 V(H)H and 39 V()H unique sequences were identified, encoded by 42 and 50 different genes, respectively. Sequence comparison indicates that the V(H)Hs evolved within the V(H) subgroup III. Nevertheless, the V(H)H germline segments are highly diverse, leading to a broad structural repertoire of the antigen-binding loops. Seven V(H)H subfamilies were recognized, of which five were confirmed to be expressed in vivo. Comparison of germline and cDNA sequences demonstrates that the rearranged V(H)Hs are extensively diversified by somatic mutation processes, leading to an additional hypervariable region and a high incidence of nucleotide insertions or deletions. These diversification processes are driven by hypermutation and recombination hotspots embedded in the V(H)H germline genes at the regions affecting the structure of the antigen-binding loops.  (+info)

Caseous lymphadenitis caused by Corynebacterium ulcerans in the dromedary camel. (7/284)

Caseous lymphadenitis that affected the dorsal and ventral superficial lymph nodes in the left cervicothoracic region of a young dromedary camel is described. The agent isolated was Corynebacterium ulcerans. To our knowledge, this is the first description of purulent lymphadenitis caused by C. ulcerans in a species belonging to the Camelidae.  (+info)

Ruminant relaxin in the pregnant one-humped camel (Camelus dromedarius). (8/284)

We have determined the cDNA sequence of preprorelaxin in the pregnant one-humped camel by employing reverse transcription- and rapid amplification of cDNA ends-polymerase chain reaction. Camel preprorelaxin consisted of 600 base pairs (bp) encoding a protein of 199 amino acids (aa) with a signal peptide of 25 aa (75 bp), a B domain of 28 aa (84 bp), a C domain of 121 aa (366 bp), and an A domain of 24 aa (72 bp). The N terminus of the C domain of camel prorelaxin contained the unique proline-rich repetitive sequence (-RPAP)(3)-(-K/RPAL-)(2), and within the B domain the classical -GRELVR- receptor binding motif was found. Camel preprorelaxin showed highest homology with porcine (74.6%) and equine (65.4%) relaxin. The ovary and the uteroplacental unit were a dual source of relaxin in the pregnant dromedary. Within the ovary, weak expression of relaxin was detected in large luteal cells of the mature corpus luteum. In the ovarian follicles, immunoreactive relaxin, but not relaxin mRNA, was detected in the granulosa and theca interna cell layer. Beginning at around Day 93 of gestation and coinciding with increasing interdigitation of the fetal villus with the underlying maternal endometrium, uterine luminal epithelial cells in the uteroplacental tissue expressed relaxin. Weak expression of immunoreactive relaxin, but not relaxin mRNA, was observed in villous trophoblast cells. Pseudostratified trophoblast cells at the base of the placental villi and multinucleate giant cells did not express relaxin.  (+info)