Spectrocolourimetry visualized differences in sexual skin colouration in macaques

The females of some catarrhines develop conspicuous sexual skin transformations in their hind limbs. Among macaques (one of the radiated and adapted catarrhine groups with diversified sexual skin transformations), differences in sexual skin colouration between the Japanese macaque Macaca fuscata and the rhesus macaque M. mulatta have not been quantitatively analysed. In this study, the sexual skin colouration of these macaques was spectrocolourimetrically measured in the non-mating season (NMS) and the mating season (MS) and represented in a CIELAB space with the variables L*, a* and b*. The variables L*, a* and b* represent positions on the light-dark, red/magenta-green, and yellow-blue axes, respectively. In the Japanese macaques the average ± SD of L*, a* and b* was 53.61 ± 3.31, 11.51 ± 4.57 and 6.66 ± 2.25 in the NMS and 46.60 ± 2.78, 19.97 ± 2.99 and 8.80 ± 1.34 in the MS, respectively, while in the rhesus macaques the average ± SD of L*, a* and b* was 60.09 ± 3.96, 5.99 ± 4.59 and 5.83 ± 2.37 in the NMS and 52.70 ± 6.54, 13.62 ± 6.86 and 8.07 ± 1.43 in the MS, respectively. The sexual skin of the Japanese macaques was consistently much redder (larger a*) and darker (smaller L*) than that of the rhesus macaques. The smaller L* suggested a greater dermal melanin content in the Japanese macaques. These closely related macaque species have similar but distinct sexual skin colourations. Spectrocolourimetry is thus useful to suggest the histophysiological background of the colouration.

The partially implantable middle ear implant, case reports

The partially implantable middle ear implant (MEI) is clinically useful for bilateral deafness when it is applied to the mixed deafness with a bone conduction threshold of 20-40 dB. Two out of five successful cases are reported. It should be noted that 1.5 years have passed without changes for the first successful implantation. The next step for application of the MEI to more cases is discussed.

Emergence of infectious malignant thrombocytopenia in Japanese macaques (Macaca fuscata) by SRV-4 after transmission to a novel host

We discovered a lethal hemorrhagic syndrome arising from severe thrombocytopenia in Japanese macaques kept at the Primate Research Institute, Kyoto University. Extensive investigation identified that simian retrovirus type 4 (SRV-4) was the causative agent of the disease. SRV-4 had previously been isolated only from cynomolgus macaques in which it is usually asymptomatic. We consider that the SRV-4 crossed the so-called species barrier between cynomolgus and Japanese macaques, leading to extremely severe acute symptoms in the latter. Infectious agents that cross the species barrier occasionally amplify in virulence, which is not observed in the original hosts. In such cases, the new hosts are usually distantly related to the original hosts. However, Japanese macaques are closely related to cynomolgus macaques, and can even hybridize when given the opportunity. This lethal outbreak of a novel pathogen in Japanese macaques highlights the need to modify our expectations about virulence with regards crossing species barriers.

Muscle microvascular adaptation and angiogenic gene induction in response to exercise training are attenuated in middle-aged rats

This study was designed to investigate exercise-induced changes in muscle capillarisation, the mRNA expression of angiogenic genes, and microRNA levels in young and middle-aged rats. Rats in the training groups were subjected to treadmill running 5 days a week for 3 weeks. The exercise protocol for the young (12-week old) group was 20-25 m/min, 40-60 min/day with a gradient of 15%, and for the middle-aged (12-month old) group was 18-20 m/min, 40-60 min/day with a gradient of 5%. The enzyme histochemical identification of capillary profiles was performed on cross-sections of gastrocnemius muscle. Total RNA was isolated, reverse transcription was performed, and mRNA and microRNA levels were determined by real-time PCR. The capillary-to-fibre ratio was significantly increased by exercise training in the young group (by 10%), but only slightly in the middle-aged (by 5%) group. Vascular endothecial growth factor (VEGF) mRNA levels were at significantly higher values after acute exercise (1.6-fold) and the 3-week training protocol (1.9-fold) in the young group, but not in the middle-aged group. VEGF protein expression levels were significantly increased after training in the young group only. Endothelial nitric oxide synthase, VEGF-R2 and thrombospondin-1 mRNA levels were significantly lower in the middle-aged group than in the young group. Anti-angiogenic miR-195 levels were significantly enhanced by exercise training in the middle-aged group only. These results indicated that the exercise-induced adaptation of muscle capillarity was attenuated in middle-aged rats, possibly by the lower induction of VEGF and up-regulation of anti-angiogenic miRNA expression.

Oestrogen-induced activation of preoptic kisspeptin neurones may be involved in the luteinising hormone surge in male and female Japanese monkeys

The oestrogen-induced luteinising hormone (LH) surge is evident in male primates, including humans, whereas male rodents never show the LH surge, even when treated with a preovulatory level of oestrogen. This suggests that the central mechanism governing reproductive hormones in primates is different from that in rodents. The present study aimed to investigate whether male Japanese monkeys conserve a brain mechanism mediating the oestrogen-induced LH surge via activation of kisspeptin neurones. Adult male and female Japanese monkeys were gonadectomised and then were treated with oestradiol-17β for 2 weeks followed by a bolus injection of oestradiol benzoate. Both male and female monkeys showed an oestrogen-induced LH surge. In gonadectomised monkeys sacrificed just before the anticipated time of the LH surge, oestrogen treatment significantly increased the number of KISS1-expressing cells in the preoptic area (POA) and enhanced the expression of c-fos in POA KISS1-positive cells of males and females. The oestrogen treatment failed to induce c-fos expression in the arcuate nucleus (ARC) kisspeptin neurones in both sexes just prior to LH surge onset. Thus, kisspeptin neurones in the POA but not in the ARC might be involved in the positive-feedback action of oestrogen that induces LH surge in male Japanese monkeys, as well as female monkeys. The present results indicate that oestrogen-induced activation of POA kisspeptin neurones may contribute to the LH surge generation in both sexes. The conservation of the LH surge generating system found in adult male primates, unlike rodents, could be a result of the capability of oestrogen to induce POA kisspeptin expression and activation.

Characterization of spontaneous malignant lymphomas in Japanese macaques (Macaca fuscata)

Lymphomas are common spontaneous tumors in nonhuman primates but remain poorly characterized in Japanese macaques (Macaca fuscata). This study examined 5 cases of spontaneous malignant lymphoma in Japanese macaques, focusing on the immunophenotypes and presence of simian lymphocryptoviruses, which are Epstein-Barr virus-related herpesviruses in nonhuman primates. The macaques with lymphoma were 5 to 28 years old, indicating that lymphomas develop over a wide age range. The common macroscopic findings were splenomegaly and enlargement of lymph nodes. Histologic and immunohistochemical analyses revealed that all cases were non-Hodgkin type and exhibited a T-cell phenotype, positive for CD3 but negative for CD20 and CD79α. The lymphomas exhibited diverse cellular morphologies and were subdivided into 3 types according to the World Health Organization classification. These included 3 cases of peripheral T-cell lymphoma, not otherwise specified; 1 case of T-cell prolymphocytic leukemia; and 1 case of an unclassifiable T-cell lymphoma. Positive signals were detected by in situ hybridization in 2 of the 4 examined cases using probes for the Epstein-Barr virus-encoded small RNA (EBER). Furthermore, the presence of M. fuscata lymphocryptovirus 2, a macaque homolog of Epstein-Barr virus, was demonstrated in EBER-positive cases by polymerase chain reaction amplification followed by direct sequencing. Immunohistochemistry using antibody to the Epstein-Barr virus-encoded nuclear antigen 2 was negative, even in the EBER-positive cases. The present study suggests that T-cell lymphoma is more common than B-cell lymphoma in Japanese macaques and that M. fuscata lymphocryptovirus 2 is present in some cases.

Cortisol analysis of hair of captive chimpanzees (Pan troglodytes)

In addition to behavioral evaluations, stress assessments are also important for measuring animal welfare. Assessments of long-term stress are particularly important given that prolonged stress can affect physical health and reproduction. The use of hair cortisol as a marker of long-term stress has been increasing, but there has not yet been any report on the use of such methods with chimpanzees. Therefore, the purpose of this study was to establish and validate a methodology for analyzing hair cortisol in captive chimpanzees. In the first experiment, hair was removed from the arms of nine chimpanzees living in the Kumamoto Sanctuary (KS) and the regrown hair was sampled 3 months later. Fecal samples were collected periodically during the hair-growth period. The results showed that hair cortisol level was positively correlated with the rate of receiving aggression. Although the correlation between hair and fecal cortisol levels was not significant, the individual with the highest hair cortisol concentration also had the highest fecal cortisol concentration. These results suggest that hair cortisol may reflect long-term stress in chimpanzees. In the second experiment, we investigated the physiological factors affecting hair cortisol concentrations. We cut hair from the arms, sides, and backs of 25 chimpanzees living at the KS and the Primate Research Institute. The results revealed that cortisol varied based on source body part and hair whiteness. Therefore, we recommend that hair should always be collected from the same body part and that white hair should be avoided as much as possible.

Intracranial arachnoid cysts in a chimpanzee (Pan troglodytes)

An intracranial arachnoid cyst was detected in a 32-year-old, 44.6-kg, female chimpanzee at the Primate Research Institute, Kyoto University. Magnetic resonance imaging (MRI) and computed tomography (CT) were performed and the cognitive studies in which she participated were reviewed. MRI revealed that the cyst was present in the chimpanzee's right occipital convexity, and was located in close proximity to the posterior horn of the right lateral ventricle without ventriculomegaly. CT confirmed the presence of the cyst and no apparent signs indicating previous skull fractures were found. The thickness of the mandible was asymmetrical, whereas the temporomandibular joints and dentition were symmetrical. She showed no abnormalities in various cognitive studies since she was 3 years old, except a different behavioural pattern during a recent study, indicating a possible visual field defect. Detailed cognitive studies, long-term observation of her physical condition and follow-up MRI will be continued.

Hepatitis E virus outbreak in monkey facility, Japan

An outbreak of hepatitis E virus occurred in an outdoor monkey breeding facility in Japan during 2004–2006. Phylogenetic analysis indicated that this virus was genotype 3. This virus was experimentally transmitted to a cynomolgus monkey. Precautions should be taken by facility personnel who work with monkeys to prevent infection.

Developmental and epigenetic anomalies in cloned cattle

Many of the developmental anomalies observed in cloned animals are related to foetal and placental overgrowth, a phenomenon known as the 'large offspring syndrome' (LOS) in ruminants. It has been hypothesized that the epigenetic control of imprinted genes, that is, genes that are expressed in a parental-specific manner, is at the root of LOS. Our recent research has focused on understanding epigenetic alterations to imprinted genes that are associated with assisted reproductive technologies (ART), such as early embryo in vitro culture (IVC) and somatic cell nuclear transfer (SCNT) in cattle. We have sought and identified single nucleotide polymorphisms in Bos indicus DNA useful for the analysis of parental-specific alleles and their respective transcripts in tissues from hybrid embryos derived by crossing Bos indicus and Bos taurus cattle. By analysing differentially methylated regions (DMRs) of imprinted genes SNRPN, H19 and the IGF2R in cattle, we demonstrated that there is a generalized hypomethylation of the imprinted allele and the biallelic expression of embryos produced by SCNT when compared to the methylation patterns observed in vivo (artificially inseminated). Together, these results indicate that imprinting marks are erased during the reprogramming of the somatic cell nucleus during early development, indicating that such epigenetic anomalies may play a key role in mortality and morbidity of cloned animals.

Developmental patterns of chimpanzee cerebral tissues provide important clues for understanding the remarkable enlargement of the human brain

Developmental prolongation is thought to contribute to the remarkable brain enlargement observed in modern humans (Homo sapiens). However, the developmental trajectories of cerebral tissues have not been explored in chimpanzees (Pan troglodytes), even though they are our closest living relatives. To address this lack of information, the development of cerebral tissues was tracked in growing chimpanzees during infancy and the juvenile stage, using three-dimensional magnetic resonance imaging and compared with that of humans and rhesus macaques (Macaca mulatta). Overall, cerebral development in chimpanzees demonstrated less maturity and a more protracted course during prepuberty, as observed in humans but not in macaques. However, the rapid increase in cerebral total volume and proportional dynamic change in the cerebral tissue in humans during early infancy, when white matter volume increases dramatically, did not occur in chimpanzees. A dynamic reorganization of cerebral tissues of the brain during early infancy, driven mainly by enhancement of neuronal connectivity, is likely to have emerged in the human lineage after the split between humans and chimpanzees and to have promoted the increase in brain volume in humans. Our findings may lead to powerful insights into the ontogenetic mechanism underlying human brain enlargement.