Reproductive biology of the male Cape porcupine, Hystrix africaeaustralis

The reproductive tract of the male Cape porcupine is morphologically and histologically similar to that of New World hystricomorph rodents. Males are reproductively active throughout the year and attained sexual maturity (complete spermatogenesis) at an age of 8-18 months. Testes weight, epididymides weight and seminiferous tubule diameter attained asymptotic values at the age of 23-30 months. A tendency towards seasonality in the activity of accessory glands, preceded and accompanied by an increase in circulating plasma testosterone values, may be considered as a factor enforcing seasonal breeding in females. Testosterone concentrations in pubertal males were significantly higher than those recorded in sexually mature males.     

Maternal photoperiodic history affects offspring development in Syrian hamsters

During the first 7 weeks of postnatal life, short day lengths inhibit the onset of puberty in many photoperiodic rodents, but not in Syrian hamsters. In this species, timing of puberty and fecundity are independent of the early postnatal photoperiod. Gestational day length affects postnatal reproductive development in several rodents; its role in Syrian hamsters has not been assessed. We tested the hypothesis that cumulative effects of pre- and postnatal short day lengths would restrain gonadal development in male Syrian hamsters. Males with prenatal short day exposure were generated by dams transferred to short day lengths 6 weeks, 3 weeks, and 0 weeks prior to mating. Additional groups were gestated in long day lengths and transferred to short days at birth, at 4 weeks of age, or not transferred (control hamsters). In pups of dams exposed to short day treatment throughout gestation, decreased testis growth was apparent by 3 weeks and persisted through 9 weeks of age, at which time maximum testis size was attained. A subset of males (14%), whose dams had been in short days for 3 to 6 weeks prior to mating displayed pronounced delays in testicular development, similar to those of other photoperiodic rodents. This treatment also increased the percentage of male offspring that underwent little or no gonadal regression postnatally (39%). By 19 weeks of age, males housed in short days completed spontaneous gonadal development. After prolonged long day treatment to break refractoriness, hamsters that initially were classified as nonregressors underwent testicular regression in response to a 2nd sequence of short day lengths. The combined action of prenatal and early postnatal short day lengths diminishes testicular growth of prepubertal Syrian hamsters no later than the 3rd week of postnatal life, albeit to a lesser extent than in other photoperiodic rodents.     

Functional anatomy of the ovaries of pregnant and lactating Cape porcupines, Hystrix africaeaustralis

The constituent cell types of the ovary of the porcupine were similar to those of New World hystricomorph rodents and accessory corpora lutea and luteal bodies were formed through the luteinization of the membrana granulosa or theca interna of antral follicles. All luteal bodies were histologically similar. The total volume of luteal tissue per female was not affected by fetal age and was unrelated to circulating concentrations of maternal plasma progesterone. Maternal plasma progesterone concentrations were correlated with fetal age. Follicular activity occurred throughout pregnancy but was not affected by fetal age or related to circulating values of oestradiol-17 beta. The formation of accessory corpora lutea during pregnancy is regarded as important in supplementing progesterone during pregnancy.     

Demography of a Cape porcupine, Hystrix africaeaustralis, population

The Cape porcupine is a large (12.0 kg), nocturnal hystricomorph rodent and widely distributed throughout southern Africa. The present paper examines age-specific survival, mortality and fecundity rates in a population, evaluates the roles of possible density-dependent changes of population parameters in the regulation of porcupine numbers, and describes the life history strategy of the species. The study is based on data sets obtained from animals collected during 1977/78 and during 1981/82. Changes in demographic characteristics are ascribed to an artificial reduction in density, resulting in the relaxation of social factors inhibiting reproduction in young adults.     

Pre- and post-natal development of pouched mice, Saccostomus campestris

Pre- and post-natal growth of the pouched mouse ( Saccostomus campestris ) were investigated and growth curves were calculated as described by Stevens (1951). Measured values of foetal weights put into Huggett & Widdas' equation (1951) revealed that the actual correction factor for species with a gestation period of 50 days or shorter was different from the one given by Huggett & Widdas. Therefore, the calculated value of specific growth velocity for pouched mice was lower than when using the correction factor given by Huggett & Widdas (1951).
Ninety percent of the asymptotic body weight was attained at an average age of 135.2 and 143.1 days for males and females, respectively, while 90% of the asymptotic body length was achieved when males and females were 71.9 and 69.3 days old, respectively. Post-natal growth rates of females and males were not significantly different from each other, and the average rate of weight increase for male and female pouched mice was lower than for other rodents studied (see Case, 1978).
Ages at which tooth eruption, eye-opening and eye usage occurred were also recorded.     

Variation in maternal investment in a small cervid; the effects of cohort,sex, litter size and time of birth in roe deer (Capreolus capreolus) fawns

 We investigated the effects of cohort, sex, litter size and time of birth on birth weights and postnatal growth rates of roe deer fawns in a highly reproductive Norwegian population. By repeatedly recapturing radio-collared individuals, a total of 950 weights were obtained from 231 fawns of known age. In accordance with earlier studies, there was a period of linear growth during the first month following birth. Mean postnatal growth rates of 155 g/day are the highest yet recorded for roe deer; however, the mean birth weights of fawns were lower than those reported from populations in continental Europe. During the period of linear growth, we found no sex differences. However, growth rates were affected both by time of birth and litter size; fawns born early had lower growth rates than fawns born during or after the peak calving period, and fawns in triplet – groups had lower growth rates than either fawns in twin – groups or single fawns. Despite a fourfold increase in population density during the study, this factor was not able to explain variation in postnatal growth rates, although cohort effects on birth weight were evident. Received: 13 May 1996 / Accepted: 26 June 1996     

Molecular evolution of rodent insulins

Several trees of amino acid sequences of rodent insulins were derived with the maximum-parsimony procedure. Possible orthologous and paralogous relationships were investigated. Except for a recent gene duplication in the ancestor of rat and mouse, there are no strong arguments for other paralogous relationships. Therefore, a tree in agreement with other biological data is the most reasonable one. According to this tree, the capacity to form zinc-binding hexamers was lost once in the ancestor of the hystricomorph rodents, followed by moderately increased evolutionary rates in the lineages to African porcupine and chinchilla but highly increased rates in at least three independent lines to other taxa of this suborder: guinea pig, cuis, and Octodontoidea (coypu and casiragua).      

Effects of feed restriction during pregnancy on maternal reproductive outcome,foetal hepatic IGF gene expression and offspring performance in the rabbit

Primiparous female rabbits have high nutritional requirements and, while it is recommended that they are subjected to an extensive reproductive rhythm, this could lead to overweight, affecting reproductive outcomes. We hypothesised that restricting food intake during the less energetic period of gestation could improve reproductive outcome without impairing offspring viability. This study compares two groups of primiparous rabbit does in an extensive reproductive programme, one in which feed was restricted from Day 0 to Day 21 of gestation (R021), and another in which does were fed ad libitum (control) throughout pregnancy. The mother and offspring variables compared were (1) mother reproductive outcomes at the time points pre-implantation (Day 3 postartificial insemination [AI]), preterm (Day 28 post-AI) and birth; and (2) the prenatal offspring characteristic IGF system gene expression in foetal liver, liver fibrosis and foetus sex ratio, and postnatal factor viability and growth at birth, and survival and growth until weaning. Feed restriction did not affect the conception rate, embryo survival, or the number of morulae and blastocysts recovered at Day 3 post-AI. Preterm placenta size and efficiency were similar in the two groups. However, both implantation rate (P < 0.001) and the number of foetuses (P = 0.05) were higher in the R021 mothers than controls, while there was no difference in foetal viability. Foetal size and weight, the weights of most organs, organ weight/BW ratios and sex ratio were unaffected by feed restriction; these variables were only affected by uterine position (P < 0.05). Conversely, in the R021 does, foetal liver IGBP1 and IGF2 gene expression were dysregulated despite no liver fibrosis and a normal liver structure. No effects of restricted feed intake were produced on maternal fertility, prolificacy, or offspring birth weight, but control females weaned more kits. Litter weight and mortality rate during the lactation period were also unaffected. In conclusion, pre-implantation events and foetal development were unaffected by feed restriction. While some genes of the foetal hepatic IGF system were dysregulated during pregnancy, liver morphology appeared normal, and the growth of foetuses and kits until weaning was unmodified. This strategy of feed restriction in extensive reproductive rhythms seems to have no significant adverse effects on dam reproductive outcome or offspring growth and viability until weaning.     

Properties of proteins binding plasma progesterone in pregnant Cape porcupines (Hystrix africaeaustralis).

The properties of progesterone-binding proteins in plasma of pregnant Cape porcupines were investigated using radiolabelled progesterone and either progesterone or cortisol as competing ligands as well as native plasma and heated (60 degrees C for 30 min) plasma. The results demonstrated that plasma from pregnant porcupines contains corticosteroid-binding globulin, but that it constitutes a significant portion of plasma progesterone-binding proteins only during the early stages of pregnancy. Corticosteroid-binding globulin of porcupines appears to be as heat labile as that of guinea-pigs. Concentrations of progesterone-binding proteins in plasma increased during pregnancy to reach concentrations at the eleventh week that were 25 times higher than those of progesterone; concentrations increased significantly (r2 = 0.88) with the increase in progesterone concentration. The results indicate that plasma progesterone-binding proteins in Cape porcupines (Old World hystricomorph) are similar in composition to those in guinea-pigs (New World hystricomorph).     

The long gestation of the small naked mole-rat (Heterocephalus glaber Rüppell, 1842) studied with ultrasound biomicroscopy and 3D-ultrasonography

The naked mole-rat (Heterocephalus glaber) is one of the two known mammalian species that live in a eusocial population structure. Here we investigate the exceptionally long gestation period of 70 days observed in the mole-rat queen. The course of seven successful pregnancies in two individuals was recorded in a colony of captive naked mole-rats using ultrasound biomicroscopy (UBM) and 3D-ultrasonography. We establish a catalogue of basic reference ultrasound data for this species by describing the ultrasonographic appearance of reproductive organs, calculating growth curves to predict gestational age and defining ultrasonographic milestones to characterize pregnancy stages. Mean litter size was 10.9±2.7, of which 7.2±1.5 survived the weaning period. Mean interbirth interval was 128.8±63.0 days. The reproductive success in our colony did not differ from previously published data. In the queen the active corpora lutea had an anechoic, fluid filled centre. Using UBM, pregnancy could be detected 53 days before parturition. The period of embryonic development is assumed to last until 30 days before parturition. Embryonic resorptions were detected frequently in the queen, indicating that this might be an ordinary event in this species. We discuss the extraordinary long gestation period of this small rodent and postulate that the long gestation is beneficial to both the eusocial structure and longevity. An increased litter size, twice as large as for other rodents of similar size, seemingly compensates for the doubling of pregnancy length. We demonstrate that the lifetime reproductive effort of a naked mole-rat queen is equivalent to the mass of offspring that would be produced if all of the females of a colony would be reproducing.     

The Ontogeny of Encephalization: Tradeoffs Between Brain Growth,Somatic Growth,and Life History in Hominoids and Platyrrhines

This study examines variation in brain growth relative somatic growth in four hominoids and three platyrrhines to determine whether there is a trade-off during ontogeny. I predicted that somatic growth would be reduced during periods of extensive brain growth, and species with larger degrees of encephalization would reach a smaller body size at brain growth completion because more energy is directed towards the brain. I measured cranial capacity and skeletal size in over 500 skeletal specimens from wild populations. I calculated nonlinear growth curves and velocity curves to determine brain/body growth allometry during ontogeny. In addition, I calculated linear regressions to describe the brain/body allometry during the postnatal period prior to brain size reaching an asymptote. The results showed that somatic growth is not substantially reduced in species with extensive brain growth, and body size at brain growth completion was larger in species with greater degrees of encephalization. Furthermore, large body size at brain growth completion was not correlated with interbirth interval, but was significantly correlated with prolonged juvenile periods and late age at maturity when data were corrected for phylogeny. These results indicate that neither reduction in body growth nor reproductive rate are compensatory mechanisms for the energetic costs of brain growth. Other avenues for meeting energetic costs must be in effect. In addition, the results show that somatic growth in encephalized species is particularly slow during the juvenile period after brain growth at or near completion, suggesting that these growth patterns are explained by reasons other than energetic costs.     

The biology and use of the African brush-tailed porcupine (Atherurus africanus, Gray, 1842)as a food animal. A review

The brush-tailed porcupine (Atherurus africanus) is a hystricomorph rodent, which frequents the forests of West and Central Africa. With an average weight of 3 kg, it is a favourite source of meat for urban and rural populations of Gabon, Nigeria, Cameroon or Congo. Hunted in large quantities, its price is often higher than that of other game or domestic animals. Although its current productivity in captivity is limited to a single young per birth and two to three births per year per female, this species could be a good candidate for minilivestock programmes in African forest areas if its current reproductive potential in captivity could be improved. Further research should be encouraged on its biology and reproduction since the current level of hunting for this species is probably not sustainable. Captive breeding programmes could play a role in assessing a better knowledge of the species' biology, and in reducing the effects of intensive hunting in areas where this activi ty is no longer sustainable.     

Evolution of the zygomasseteric construction in Rodentia,as revealed by a geometric morphometric analysis of the mandible of Graphiurus (Rodentia,Gliridae)

Graphiurus is a peculiar taxon among the monophyletic Gliridae (order Rodentia) in showing hystricomorphy of the zygomasseteric architecture of the skull [large infraorbital foramen (IOF), and correlative muscular arrangements). We analysed 34 extant genera taken from two groups of sciurognath rodents that share a large IOF (hystricomorph and myomorph) using elliptical Fourier transform in order to appraise whether this feature of cranial morphology was also accompanied by similar changes in mandible shape. The mandible of Graphiurus is distinct from those of all other hystricomorph sciurognath rodents in showing a more elongated coronoid process and a shorter angular process. Thus, two distinct zygomasseteric organizations (i.e. myomorphy and hystricomorphy of graphiurines) are associated with a similar mandible shape characterized by a well‐developed coronoid process. Results show that hystricomorphy of graphiurines was achieved convergently with other hystricomorph rodents. Protrogomorphy is the plesiomorphic condition in Gliridae and hystricomorphy is an autapomorphic feature of Graphiurus. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 807–821.     

Reproductive synchrony and annual variation in foetal growth rate in the long-fingered bat (Miniopterus schreibersii)

Mating in the long-fingered bat (Miniopterus schreibersii) from the East Cape region of South Africa occurred during a four-week period in April and May, and implantation was delayed until August. Analyses of foetal age and estimated dates of conception indicate that after implantation, the progression of pregnancy within the population was synchronous both within and between years. It is suggested that implantation, probably initiated by increasing day length, occurred at about the same time throughout the population and thus synchronized reproduction. In the final month of pregnancy foetal growth rate and, consequently, the timing of parturition in the three years of the study varied. These variations were correlated with variations in rainfall and it is suggested that the failure of the November rains in 1990 would have caused a reduction in insect abundance and that this was responsible for the decrease in foetal growth rate and the delay in parturition.     

Expression and localisation of ephrin-B1, EphB2, and EphB4 in the mouse testis during postnatal development

The erythropoietin-producing hepatocellular receptor B (EphB) class and ephrin-B ligand have been implicated in boundary formation in various epithelia. We recently found that ephrin-B1 and EphB2/EphB4 exhibit complementary expression in the epithelia along the excurrent duct system in the adult mouse testis. Moreover, the organisation and integrity of the duct system is indispensable for the transport of spermatozoa. Here, we examined ephrin-B1, EphB2 and EphB4 expression in the mouse testis during postnatal development. RT-PCR analysis revealed that the relative expression levels of these molecules decreased with age in early postnatal development, and were similar to those of adults by four weeks of age. Furthermore, immunostaining revealed that the excurrent duct system compartments exhibiting complementary expression of ephrin-B1 and EphB2/EphB4 were formed by two weeks of age. Meanwhile, ephrin-B1 and EphB4 were effective markers for spermatogonia in the neonatal testis due to their negative expression in gonocytes. Alternatively, EphB2 was a suitable marker for assessing completion of the first wave of spermatogenesis in puberty, due to its strong expression in the elongated spermatids of seminiferous tubules. Lastly, ephrin-B1 and EphB4 proved to be markers of both foetal and adult Leydig cells during postnatal development, as they were expressed in CYP17A1-positive cells. This study is the first to investigate the expression of ephrin-B1, EphB2, and EphB4 in normal mouse testes during postnatal development. The expression patterns of ephrin-B and EphBs may represent suitable tools for examining organisation of the excurrent duct system and monitoring reproductive toxicity during postnatal development.     

Ovarian maturity,egg development,and offspring generation of the deep-water shrimp Plesionika edwardsii (Decapoda,Pandalidae) from three isolated populations in the eastern North Atlantic

Ovarian maturity, egg development and brood size were analysed for three isolated populations (Madeira, the Canary Islands and Cape Verde Islands) of Plesionika edwardsii (Decapoda, Pandalidae) in the eastern Atlantic. Multiple colour patterns were observed at the same ovarian maturity stage, which was verified histologically, invalidating the extensive use of ovarian colour as a maturity stage criterion. The physiological size at sexual maturity, based on the maturity of the ovaries, was higher in Madeira (carapace length of 19.73?mm) and decreased to the Cape Verdes (16.39?mm). Synchronic ovarian maturation was observed during the embryo incubation process, and ovigerous females bearing embryos at the final stage of development were found throughout the year. Females are multiple spawners during the reproductive season, after which the reproductive process ends and a rest period begins. The absence of females larger than the size at sexual maturity with ovaries in Stage 1, the incubation of embryos in the final developmental stages, suggests that the resting period begins with a process that reabsorbs the energy located in the ovaries and that the resting period occurs asynchronously in females in each of the studied populations. Embryo size was independent of female body size in the three populations studied, but increased with the developmental stage. A power equation was used to describe the relationship between brood size and female body size in the three areas studied. The mean number of external Stage I embryos carried by females decreased from Madeira (n?=?7868) to the Cape Verdes (n?=?3781), where less energy, in terms of the number of embryos and the size of the eggs, was invested in reproduction. Although female size decreases from north to south, the egg number was higher in Madeira than in the Cape Verdes for the same size range.     

Glucose-6-phosphate dehydrogenase activity in individual rat hepatocytes of different ploidy classes. I. Developments during postnatal growth

The glucose-6-phosphate dehydrogenase (G6PDH) activity of isolated male rat hepatocytes has been investigated in relationship to the ploidy classes of the cells during the first 20 weeks of postnatal growth. The G6PDH activity in the individual cells was measured with an improved quantitative cytochemical method. The data obtained showed that throughout the whole period of postnatal growth there existed a proportional relationship between the genome copies per cell and the amount of G6PDH activity per cell for binuclear diploid (BD), mononuclear tetraploid (MT) and binuclear tetraploid (BT) cells but not for mononuclear diploid (MD) cells. In the MD cells, which are the stem cells of the liver parenchyma, the activity measured was 1.5 times higher than expected. Furthermore, during postnatal growth, the G6PDH activity per hepatocyte was low at the age of 2 weeks, increased somewhat after weaning (5 weeks) and then more dramatically after 8 weeks to reach a maximum between 12 and 16 weeks. This development occurred in MT and BT cells at an earlier age than in MD and BD cells, in which the increase in enzyme activity followed some 3 weeks later. Castration of the rats before puberty did not influence the development of the amount of G6PDH activity per cell of any of the ploidy classes.     

Blood glucose concentration in caviomorph rodents

Hystricomorph rodents are a group of species that belong to the suborder Hystricognathi. They mainly inhabit South American (caviomorph) and African (phiomorph) habitats. This group of rodents has a divergent insulin structure. For example, insulin in this group of rodents exhibits only 1-10% of biological activity in comparison to other mammals. Therefore, hystricomorph rodents may hypothetically be unable to regulate blood glucose concentration as non-hystricomorph mammals. In this work we evaluated blood glucose concentration in nine species of caviomorph rodents, with emphasis on species belonging to the families Abrocomidae, Ctenomyidae and Octodontidae. Specifically we: (1) measured glucose concentrations after a fasting period; and (2) conducted a glucose tolerance test. In the latter assay we used Octodon degus as a representative species of the genus Octodon. Results showed that blood glucose concentration values after fasting, and in the glucose tolerance test, were within the expected range for mammals. We postulate that this group of rodents has compensatory traits that may permit the maintenance of standard values of plasma glucose.     

Insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-3, phosphoisoforms of IGFBP-1 and postnatal growth in very-low-birth-weight infants

Small preterm infants experience a unique postnatal period characterized by slow growth, inadequate nutrition and growth inhibiting treatments. Many have already been growth-restricted in utero. Studying this period is important when developing growth optimizing strategies for these infants and, in a broader context, as a model of extreme conditions that restrict growth. By following short-term growth of 48 very-low-birth-weight (VLBW; birth weight <1,500 g) infants for 9 postnatal weeks, we found that circulating insulin-like growth factor (IGF)-I and IGF binding protein (IGFBP)-3 levels are low and reflect rigorously measured (knemometry and weight) concurrent growth velocity. Moreover, weight growth velocity is correlated with the ratio of lesser to highly phosphorylated IGFBP-1 but not with absolute IGFBP-1 concentrations. Thus, IGF-I, IGFBP-3 and the phosphorylation status of IGFBP-1 in circulation are likely to be involved in growth regulation during the postnatal period in VLBW infants.     

Effects of lithocholic acid exposure throughout pregnancy on late prenatal and early postnatal development in rats

The effects of lithocholic acid (LCA) on late prenatal and early postnatal development were studied. LCA was given in the diet (0.8% by weight) or administered in the drinking water (0.8%) throughout the entire period of pregnancy. The addition of LCA to the drinking water caused a significant reduction in the weight of 20-day-old fetuses as well as their placentas and livers. Feeding LCA to pregnant rats affected postnatal growth of the offspring: their weight was significantly lower than control values until 6 weeks of age. The pattern of postnatal growth was similar in the experimental and control rats. The retardation in growth and development of the offspring was accompanied by microscopic and biochemical changes in their livers.