The reproductive system of male rock hyrax (Procavia and Heterohyrax)

The male genitalia of the rock hyrax (Procavia and Heterohyrax) are described. Features of the gross anatomy and histology of the testes and male accessory organs are presented, and comparison is made between the sexually active and sexually quiescent animal.
Microscopical observations have revealed the main area of storage of spermatozoa in this mammal and partly on these grounds, a new nomenclature for different parts of the reproductive system is proposed. Seasonal variations in male sexual activity in these mammals are also discussed, in addition to anatomical considerations.     

Steroidogenic correlates of pregnancy in the rock hyrax (Procavia capensis)

In pregnant rock hyraxes isolated leucocytes metabolise both [3H]pregnenolone and [3H]progesterone while whole blood, erythrocytes and an erythrocyte/leucocyte mixture only metabolised [3H]progesterone. Plasma displayed no tendency to metabolically convert any one of these two steroids. In whole blood [3H]progesterone appears to be converted to 5alpha-pregnane-3,20-dione and a compound with chromatographic properties similar to that of 5alpha-pregnan-3alpha-ol-20-one. 5Alpha-pregnane-3,20-dione exhibited a high relative binding affinity for the uterine progesterone eceptor (94%), but 5alpha-pregnan-3alpha-ol-20-one displayed very little affinity for the same receptor (0.4%). 5Alpha-pregnane-3,20-dione may therefore aid in the maintenance of pregnancy. Corpora lutea metabolised progesterone to 17alpha-hydroxyprogesterone, a compound exhibiting no progestational function because of its low relative binding affinity for the uterine progesterone receptor (2%). Progesterone appears to be the main product of the corpus luteum. However, 5alpha-pregnane-3,20-dione circulated at concentrations approximately 8.5 times higher than progesterone, probably due to the metabolic conversion of progesterone to 5alpha-pregnane-3,20-dione by the blood. We conclude that in the hyrax progesterone, produced by the corpora lutea, enters the circulation, where it is reduced to 5alpha-pregnanes. 5Alpha-pregane-3,20-dione may then be transported to the uterus where it binds to the progesterone receptor to assist in the maintenance of pregnancy. This mechanism appears to be analogous to that of the African elephant which is phylogenetically related to the hyrax, except that in the elephant the 5alpha-reduced metabolites are produced by luteal tissue and not the blood.     

Geographic mitochondrial DNA variation in the rock hyrax, Procavia capensis.

Restriction-fragment-length polymorphisms in mitochondrial DNA (mtDNA) were used to evaluate geographic population genetic structure in the rock hyrax, Procavia capensis, a species which occurs widely, though restricted to rocky habitat, throughout South Africa. Ten restriction endonucleases were employed to assay mtDNAs from 55 specimens representing 10 localities. Haplotypes showed strong geographic patterning, and estimates of nucleotide sequence divergence indicate two major clades thought to be dispersing along separate routes. The divergence time of approximately 2 Myr between clades is relatively high for intraspecific variation. We speculate that the marked genetic break distinguishing the northwestern populations from those constituting the south/central clade may be indicative of two species in what has conventionally been regarded as P. capensis.     

Electron microscopic structure and innervation of the carotid baroreceptor region in the rock hyrax (Procavia capensis).

Semi-thin plastic sections reveal that the carotid baroreceptor region in the rock hyrax comprising the origin of the internal carotid artery has a preponderantly elastic structure and a thick tunica adventitia. In contrast, the common carotid artery has a musculoelastic structure, whereas the cranial segment of the internal carotid artery (immediately distal to the baroreceptor areas) shows the features of a muscular artery. Electron microscopy discloses the presence of sensory nerve endings within the parts of the tunica adventitia adjoining the preponderantly elastic zone of the internal carotid artery. These nerve endings are characterized by varicose regions containing a large quantity of mitochondria. Bundles of collagen fibers in the tunica adventitia form convolutions or whorls around the nerve terminals and often terminate on the surface of the elastic fibers or into the basement membranes of the neuronal profiles. The large content of elastic tissue in the tunica media of the baroreceptor region may render the vessel wall highly distensible to intraluminal pressure changes. This, in turn, would facilitate the transmission of the stimulus intensity to the sensory nerve terminals located in the tunica adventitia. It is suggested that the stretching of elastic fibers may form the main mechanical event leading to the distortion of the associated nerve terminals. However, a change in the geometrical configuration of the bundles of collagen under the influence of the elastic fibers may provide a better insight into the mechanisms of distortion of the baroreceptors related to and/or in contact with collagen fibers.     

Age determination and growth in the hyrax Procavia capensis (Mammalia: Procaviidae)

The use of eye lens weight, tooth eruption and tooth attrition has been investigated as a method for age determination in the hyrax. Illustrations are presented on the stages of eruption to reduce subjectivity of eruption criteria and to aid age determination. All teeth are fully erupted and in wear by five years of age, from which point age determination can be based on attrition of M3. Growth with age is described by means of the von Bertalanffy equation. Asymptotic weight is reached by 60 months, asymptotic body length and body girth by 40 months, and hindfoot length by 35 months. The asymptotes and the coefficient of catabolism (K) are compared with values obtained in other studies.     

The primary structure of hemoglobins from the domestic cat (Felis catus, Felidae)

The complete primary structure of the two hemoglobin components of the domestic cat (Felis catus) is presented. The major component (A) accounts for 60-70% whereas the minor component (B) constitutes 30-40% of the total hemoglobin. Separation of the polypeptides was carried out in buffers containing 8M urea on CM-Cellulose. The sequence was studied by Edman degradation of tryptic and cyanogen bromide cleavage products in a liquid phase sequencer. The sequence is compared for homology with human hemoglobin. The beta-chain of the minor components (beta B) has a blocked N-terminal residue identified as acetylserine whereas that of the major component (beta A) is free glycine. The two hemoglobins have identical alpha-chains and differ with respect to their beta-chains at the following positions (beta B/beta A): beta NA1 Ac-Ser/Gly, beta A1 Ser/Thr, beta H17 Ser/Asn and beta HC1 Arg/Lys. The structural and functional aspects of these exchanges are discussed.     

The primary structure of the hemoglobins of the adult jaguar (Panthera onco, Carnivora)

The primary structure of the hemoglobins from Jaguar (Panthera onco) are presented. Electrophoretic separations without and with a dissociating agent revealed the presence of two hemoglobin components, alpha 2 beta I2 and alpha 2 beta II2. The separation of the hemoglobin components was achieved by ion-exchange chromatography. The globin chains were separated by ion-exchange chromatography and also by reversed phase HPLC. The amino-acid sequences of the native chains and peptides were determined by liquid-phase and gas-phase sequencing. N-Acetylserine was detected by FAB-mass spectroscopy as N-terminal group of the beta I chain. The sequences are compared with that of human hemoglobin (Hb A).     

Carnivora: primary structure of the hemoglobins from ratel (Mellivora capensis)

The erythrocytes of adult ratel contain two hemoglobin components, with two alpha- and one beta-chains. In this paper, their complete amino acid sequences are presented. The two alpha-chains differ in one residue at position 34 (Ala----Val) only. The primary structure of the chains was determined by sequencing the N-terminal regions (45 steps) and the tryptic peptides after their isolation from the digests by reversed-phase high-performance liquid chromatography. The alignment of these peptides was deduced from homology with other carnivora globins. The alpha-chains show 21 and the beta-chains 11 exchanges compared with human globin chains. In the alpha-chains, one heme- and two alpha 1/beta 1 contacts are exchanged. In the beta-chains there are three exchanges which involve one alpha 1/beta 1-, one alpha 1/beta 2- and one heme-contact. Between the ratel hemoglobin and those of carnivora a high degree of homology was found.     

Perissodactyla: the primary structure of hemoglobins from the lowland tapir (Tapirus terrestris): glutamic acid in position 2 of the beta chains

The hemoglobins from a lowland tapir (Tapirus terrestris) were analysed and the complete primary structure is described. The globin chains were separated on CM cellulose column in 8M urea and the amino-acid sequences were determined in the liquid phase sequenator. The results show that globin consists of two alpha chains (alpha I and alpha II) and beta major and beta minor components. The alpha chains differ only at one position: alpha I contains aspartic acid and alpha II glycine. The beta chains are heterogeneous: aspartic and glutamic acid were found at position beta 21 and beta 73 of the beta major components and asparagine and serine at position beta 139. In the beta minor components four positions were found with more than one amino acid, namely beta 2, beta 4, beta 6 and beta 56. The sequences are compared with those of man, horse and rhinoceros. Four residues of horse methemoglobin, which are involved in the alpha 1 beta 1 contacts are substituted in tapir hemoglobins. In the alpha chains: alpha 107(G14)Ser----Val, alpha 111-(G18) Val----Leu, alpha 115(GH3) Asn----Asp or Gly; in the beta chains: beta 116(G18) Arg----Gln. The amino acid at beta 2 of the major components is glutamic acid while glutamine and histidine are found in the minor components. Although glutamic acid, a binding site for ATP, does not interact with 2,3-bisphosphoglycerate, glutamine and histidine in the minor components are responsible for the slight effect of 2,3-bisphosphoglycerate on tapir hemoglobin.     

The primary structure of the hemoglobins of a southern hemisphere lamprey (Mordacia mordax, Cyclostomata)

Mordacia mordax is a southern hemisphere lamprey belonging to Mordaciidae, a primitive family of Cyclostomata. Adult erythrocytes contain three monomeric hemoglobins which can be easily separated by cellulose acetate electrophoresis and isolated by ion-exchange chromatography. The N-terminal regions, and the tryptic peptides from each chain were submitted to automated Edman degradation; the alignment of the fragments was obtained by homology with the other Petromyzonoidea hemoglobins hitherto sequenced. Our results confirm the phylogenic distance between lampreys and hag-fish hemoglobins. As was observed for Petromyzon marinus species, two hemoglobins of Mordacia mordax are very close, as they differ only at 7 positions.     

Inermicapsifer beveridgei n. sp. (Cestoidea: Anoplocephalidae) from Procavia capensis (Hyracoidea) in Israel, with notes on two species of Hymenolepis

Inermicapsifer beveridgei n. sp. from Procavia capensis differs from all other species in the genus in having 150-174 testes per segment. The closest species is I. hyracis (Rudolphi, 1810) Janicki, 1919, with 75-120 testes. Hymenolepis vogeae Singh, 1956 and H. horrida (Linstow, 1901) Lühe, 1910, are briefly discussed.