Kanchil Research Articles

Three-dimensional Image Analysis of the Thin Abdominal Wall in the Naked Mole-rat and the Lesser Mouse Deer

Three-dimensional Image Analysis of the Thin Abdominal Wall in the Naked Mole-rat and the Lesser Mouse Deer

Functional morphology of the mastication muscles in the lesser and greater mouse deer.

The mastication muscles were examined in the lesser (Tragulus javanicus) and greater mouse deer (Tragulus napu) to clarify the form of the mastication muscles in these primitive artiodactyls. The M. masseter was well-developed in both species, however the attachment area of its origin was not confirmed in the rostral facial part. The masseter bundles were not observed on the lateral side of the maxilla bone, and their origin was restricted to the zygomatic arch area. This suggests that the M. masseter may not act as a motor raising the mandible rostro-dorsally, but pull the insertion vertically unlike the highly derived grazer of Bovidae. The Crista temporalis was weak and the M. temporalis was thin in the mouse deer, and this indicates that the M. temporalis may not be important in the mastication in the primitive artiodactyls. These findings suggest that the browser such as mouse deer has been adapted for the feeding on soft leaves, and functional-morphologically different in mastication strategy from the grazer such as developed Bovidae species. The architecture of the mastication muscles was not different between the two species. However, in the muscle weight ratios per body weight, the M. temporalis and the M. digastricus were significantly smaller in greater mouse deer than in lesser mouse deer.

Energy expenditure in relation to activity of lesser mouse deer ( Tragulus javanicus)

Heat production (HP) of male and female mouse deer during eating, standing and sitting was determined using the open circuit respiration chamber (RC). The time taken for similar activities was also determined in an outdoor enclosure (OD). The animals were fed kangkong ( Ipomoea aquatica), sweet potato ( Ipomoea batatas) and rabbit pellet ad libitum. Male mouse deer consumed more dry matter (DM), organic matter (OM) and gross energy (GE) than female. The time for each activity of male and female mouse deer kept in RC and OD was similar. The average time spent in RC and OD for both male and female, respectively, for sitting (956 and 896 min/day) was significantly ( P<0.01) longer than standing (463 and 520 min/day) and eating (21 and 24 min/day). Heat production for male and female mouse deer, respectively, during eating was the highest (0.44 and 0.43 kJ/kg W 0.75/min) followed by standing (0.37 and 0.33 kJ/kgW 0.75/min) and sitting (0.26 and 0.26 kJ/kg W 0.75/min). The difference in HP per min during standing between male and female was significant ( P<0.05). The HP for 08.00–14.00 h and 14.00–20.00 h periods were higher than 20.00–02.00 h and 02.00–08.00 h periods. The overall HP for males during 08.00–14.00 h and 14.00–20.00 h periods were significantly ( P<0.05) higher (114.8 and 119.2 kJ/kg W 0.75) than female (107.5 and 110.4 kJ/kg W 0.75), respectively.

Preference Test on Feed and Nutrient Intakes in Male and Female Lesser Mouse Deer (Tragulus Javanicus) in Captivity

A preference test on feed and nutrient intakes were conducted on four male (1.25±0.08 kg) and four female (1.21±0.15 kg) lesser mouse deer (Tragulus javanicus) in captivity. Each animal was kept in individual cages placed in a well-ventilated animal house. The experiment was conducted in two weeks, where the first week was for adaptation to the feeds and the second week for measurements of nutrient intake, nutrient digestibility and nitrogen balance. The feeds offered were kangkong (Ipomoea aquatica), long bean (Vigna sinensis) and french bean (Phaseolus vulgaris) as roughages and proteinaceous feeds; sweet potato (Ipomoea batatas) and carrot (Daucus carota) as carbohydrate-rich feeds; and commercial rabbit pellet (0.3 cm diameter and 0.5 cm long) as a complete feed. The dry matter (DM) content of each feed in the order mentioned above was 7.1, 6.1, 3.9, 18.5, 6.2 and 87.6%, respectively. Long bean had the highest protein (CP) content (29.7%), while sweet potato had the lowest (6.2%). The CP contents of other feeds were within the range of 14.2 -25.1%. Among the feeds, carrot had the lowest energy content (3.83 kcal/g) and long bean the highest (4.67 kcal/g). When fresh weight of the feed was considered, the male mouse deer consumed sweet potato the most (86.3±12.90 g/d), but the female had a high preference for carrot (79.2±9.76 g/d). The other feeds were consumed in lesser amounts. However, in terms of DM of the feed, the amount of commercial pellet consumed was the highest for both male (45.0±5.10%) and female (44.7±7.38%) mouse deer, followed by sweet potato (33.1±4.43% and 22.4±7.73% for male and female, respectively), Significant (p<0.05) differences in DM, organic matter (OM) and gross energy (GE) intakes were observed between male and female mouse deer. The male consumed higher amount of DM, OM and GE than the female. The total DM intake was 40.7±2.24 g/d/kg W0.75 for male and 35.9±1.72 g/d/kg W0.75 for female mouse deer. Percentage digestibilities of DM, OM, CP and GE were within 72.7-80.8% and were not significantly different between male and female mouse deer. However, male mouse deer had significantly (p<0.05) higher digestible DM, OM and GE intakes than the female. Both male and female mouse deer were in positive nitrogen balance (0.6 g N/d/kg W0.75). The male mouse deer gained 7.6±3.45 g/d, while the female gained 4.3±2.40 g/d.

Topographical localization of lipofuscin pigment in the brain of the aged fat-tailed dwarf lemur (Cheirogaleus medius) and grey lesser mouse lemur (Microcebus murinus): comparison to iron localization.

The present study was undertaken to explore the distribution of lipofuscin in the brain of cheirogaleids by autofluorescence and compare it to other studies of iron distribution. Aged dwarf (Cheirogaleus medius) and mouse (Microcebus murinus) lemurs provide a reliable model for the study of normal and pathological cerebral aging. Accumulation of lipofuscin, an age pigment derived by lipid peroxidation, constitutes the most reliable cytological change correlated with neuronal aging. Brain sections of four aged (8-15 year old) and 3 young (2-3 year old) animals were examined. Lipofuscin accumulation was observed in the aged animals but not in the young ones. Affected regions include the hippocampus (granular and pyramidal cells), where no iron accumulation was observed, the olfactory nucleus and the olfactory bulb (mitral cells), the basal forebrain, the hypothalamus, the cerebellum (Purkinje cells), the neocortex (essentially in the pyramidal cells), and the brainstem. Even though iron is known to catalyse lipid oxidation, our data indicate that iron deposits and lipofuscin accumulation are not coincident. Different biochemical and morphological cellular compartments might be involved in iron and lipofuscin deposition. The nonuniform distribution of lipofuscin indicates that brain structures are not equally sensitive to the factors causing lipofuscin accumulation. The small size, the rapid maturity, and the relatively short life expectancy of the cheirogaleids make them a good model system in which to investigate the mechanisms of lipofuscinogenesis in primates.

Duration of activity and period of circadian activity–rest rhythm in a photoperiod-dependent primate, Microcebus murinus

Under free-running conditions, the grey lesser mouse lemur expresses a circadian activity–rest rhythm with a period particularly short (22.50 ± 0.6 h) for a mammal. Light exerts a strong suppressive effect upon activity. After transfer from nycthemeral to free-running conditions the duration of activity was systematically increased. This extension took place in the first cycle and was characterized by both a phase advance in activity onset and an even larger phase delay in activity offset. This phenomenon was more pronounced after long day entrainment. Any shift of the light–dark cycle was followed the next day by a corresponding shift in activity onset. The phase response curve pattern was similar to that already described for nocturnal mammals. Due to the strength of light as a zeitgeber and the plasticity of the response to photic conditions, the mouse lemur appears as a convenient species for chronobiological studies on non-human primates.

Male Genital Organs and Accessory Glands of the Lesser Mouse Deer, Tragulus javanicus

Gross anatomical features of the male genital organs and accessory genital glands of the lesser mouse deer ( Tragulus javanicus ) are described. The long fibroelastic penis lacks a prominent glans and is coiled at its free end to form two and one-half turns. Near the tight coils of the penis, on the right ventrolateral aspect, lies a U-shaped ventral process. The scrotum is prominent, unpigmented, and devoid of hair and is attached close to the body, high in the perineal region. The ovoid, obliquely oriented testes carry a large cauda and caput epididymis. Accessory genital glands consist of paired, lobulated, club-shaped vesicular glands, and a pair of ovoid bulbourethral glands. A well-defined prostate gland was not observed on the surface of the pelvic urethra. Many features of the male genital organs of T. javanicus are pleisomorphic, being retained from suiod ancestors of the Artiodactyla.

Energetic Advantage of Nest-Sharing in a Solitary Primate, the Lesser Mouse Lemur (Microcebus murinus)

Energetic benefits provided by sharing a nest were investigated by measuring resting metabolic rate in the lesser mouse lemur ( Microcebus murinus ), a nocturnal solitary primate that usually groups in a nest during its diurnal rest. Resting metabolic rate was measured on 32 individuals maintained either alone or grouped with one, two, or three conspecifics originating from the same social group. In this seasonal breeder, individual resting metabolic rate varied significantly from 1.08 ± 0.03 to 1.47 ± 0.05 ( SE ) ml O2 h™1g™1 for nonbreeding and breeding seasons, respectively. During the breeding season, both sexes reduced their energetic expenditure by 20% when grouped in pairs, and maximal energetic benefit (40%) was achieved when three animals nested together. During the nonbreeding season, maximal energetic gain was observed when as few as two animals nested together because resting metabolic rate was already decreased. Finally, when three or four animals shared the same nest, resting metabolic rate was minimal, independent of sex and season, at 0.88 ml O2 h™1g™1, suggesting that nest-sharing in this solitary primate is an important strategy to minimize energetic costs to cope with seasonal shortage of food.

Thermoregulatory responses to variations of photoperiod and ambient temperature in the male lesser mouse lemur: a primitive or an advanced adaptive character?

The lesser mouse lemur, a small Malagasy primate, is exposed to strong seasonal variations in ambient temperature and food availability in its natural habitat. To face these environmental constraints, this nocturnal primate exhibits biological seasonal rhythms that are photoperiodically driven. To determine the role of daylength on thermoregulatory responses to changes in ambient temperature, evaporative water loss (EWL), body temperature (Tb) and oxygen consumption, measured as resting metabolic rate (RMR), were measured in response to ambient temperatures ranging from 5 degrees C to 35 degrees C, in eight males exposed to either short (10L:14D) or long (14L:10D) daylengths in controlled captive conditions. In both photoperiods, EWL, Tb and RMR were significantly modified by ambient temperatures. Exposure to ambient temperatures below 25 degrees C was associated with a decrease in Tb and an increase in RMR, whereas EWL remained constant. Heat exposure caused an increase in Tb and heat loss through evaporative pathways. Thermoregulatory responses to changes in ambient temperature significantly differed according to daylength. Daily variations in Tb and EWL were characterized by high values during the night. During the diurnal rest, lower values were found and a phase of heterothermia occurred in the early morning followed by a spontaneous rewarming. The amplitude of Tb decrease with or without the occurrence of torpor (Tb < 33 degrees C) was dependent on both ambient temperature and photoperiod. This would support the hypothesis of advanced thermoregulatory processes in mouse lemurs in response to selective environmental pressure, the major external cue being photoperiodic variations.

Age-related effects on reproductive function and sexual competition in the male prosimian primate, Microcebus Murinus

AUJARD, F. AND M. PERRET. Age-related effects on reproductive function and sexual competition in the male prosimian primate. Microcebus murinus. PHYSIOL BEHAV 64(4) 513–519, 1998.—In the male lesser mouse lemur ( Microcebus murinus), a polygamous long-day breeder of which the life span may reach 12–14 years, the effects of aging on socio-sexual relationships were studied on 44 captive animals of various ages. In this primate, new dominance relationships must be established at the beginning of each breeding season. During the breeding season induced by exposure to artificial long days, preoestrous females were introduced into cages of paired males to elicit sexual competition. Sexual behaviors, social interactions through chemical signals, and dominance relationships were recorded in paired males either of similar age (young or aged pairs), or of mixed ages. In all pairs, competition for priority access to females always occurred and dominance relationships were established unrelated to body weight. Although aged animals exhibited significantly less number of sexual and aggressive behaviors, they outranked younger males excepted when reaching oldest age. Independent of male’s age, the typical pattern of seasonal rhythm of testosterone was observed, but aged males demonstrated a significant reduction in mean hormonal levels (25.5 ± 2.8 ng/mL, n = 8) compared to young animals (50 ± 2.7 ng/mL, n = 8). Moreover, their hormonal response to photoperiod was phase-shifted leading to reduced testosterone values when females entered oestrus. Despite the fact that testosterone levels and sexual behaviors decreased with aging in this primate, older males reached a dominant position, increasing thus their reproductive success.

An osteometrical study of the cranium and mandible of the lesser mouse deer (Chevrotain), Tragulus javanicus.

The lesser mouse deer (Tragulus javanicus) is one of the most primitive ruminants. Skulls of lesser mouse deer were measured to evaluate their growth. The age was estimated from the eruption and attrition of molars on the mandible. A total of 95 specimens was divided into five age groups, and the growth pattern in each sex was established for some measurements. The relative growth coefficients were calculated for the head and body length and several parts of the cranium and mandible against the profile length. Sexual dimorphism could not be found on the skull in any age group except for measurements related to the upper canine. However, females showed a higher value in head and body length in the oldest group. This feature was consistent with an interpretation of mouse deer society as monogamous. Growth was more rapid in length than in width. Various statistical analyses showed that the visceral cranium related to masticatory facility was much better developed than the neurocranium. However, observations on the shape of the mandible ramus and of the premolars implied that the masticatory function was not suitable for taking roughage. This speculation agreed with previous reports on the feeding habits and digestive organs of the mouse deer.

Topographical localization of iron in brains of the aged fat-tailed dwarf lemur (Cheirogaleus medius) and gray lesser mouse lemur (Microcebus murinus).

Iron deposits in the human brain are characteristic of normal aging but have also been implicated in various neurodegenerative diseases. Among nonhuman primates, strepsirhines are of particular interest because hemosiderosis has been consistently observed in captive aged animals. In particular, the cheirogaleids, because of their small size, rapid maturity, fecundity, and relatively short life expectancy, are a useful model system for the study of normal and pathological cerebral aging. This study was therefore undertaken to explore iron localization in the brain of aged cheirogaleids (mouse and dwarf lemurs) with histochemistry and magnetic resonance microscopy. Results obtained with both techniques were comparable. There was no difference between old animals in the two species. The young animals (3 years old) showed no iron deposits. In the old animals (8-15 years old), iron pigments were mainly localized in the globus pallidus, the substantia nigra, the neocortical and cerebellar white matter, and anterior forebrain structures, including the nucleus basalis of Meynert. This distribution agrees with previous findings in monkeys and humans. In addition, we observed iron in the thalamus of these aged non-human primates. Microscopic NMR images clearly reveal many features seen with the histochemical procedure, and magnetic resonance microscopy is a powerful method for visualizing age-related changes in brain iron.

Topographical localization of iron in brains of the aged fat‐tailed dwarf lemur Cheirogaleus medius and gray lesser mouse lemur Microcebus murinus

Iron deposits in the human brain are characteristic of normal aging but have also been implicated in various neurodegenerative diseases. Among nonhuman primates, strepsirhines are of particular interest because hemosiderosis has been consistently observed in captive aged animals. In particular, the cheirogaleids, because of their small size, rapid maturity, fecundity, and relatively short life expectancy, are a useful model system for the study of normal and pathological cerebral aging. This study was therefore undertaken to explore iron localization in the brain of aged cheirogaleids (mouse and dwarf lemurs) with histochemistry and magnetic resonance microscopy. Results obtained with both techniques were comparable. There was no difference between old animals in the two species. The young animals (3 years old) showed no iron deposits. In the old animals (8–15 years old), iron pigments were mainly localized in the globus pallidus, the substantia nigra, the neocortical and cerebellar white matter, and anterior forebrain structures, including the nucleus basalis of Meynert. This distribution agrees with previous findings in monkeys and humans. In addition, we observed iron in the thalamus of these aged nonhuman primates. Microscopic NMR images clearly reveal many features seen with the histochemical procedure, and magnetic resonance microscopy is a powerful method for visualizing age-related changes in brain iron. Am. J. Primatol. 45:291–299, 1998. © 1998 Wiley-Liss, Inc.

Effect of Vomeronasal Organ Removal on Male Socio-Sexual Responses to Female in a Prosimian Primate ( Microcebus murinus)

In most mammals, olfactory cues play an important role in regulating socio-sexual behaviors, but the relative contributions of the main olfactory system and the vomeronasal system remain unclear. The lesser mouse lemur, a nocturnal prosimian, possesses well-developed chemosensory structures, including a functional vomeronasal organ (VNO). In this primitive primate, social communication and competition between males for priority access to receptive females includes reliance on urinary chemical cues. To assess the role of the VNO in mediating males’ behavioural responses to females, sexually-experienced intact males (C, n = 8) or males deprived of their VNO (VNX, n = 8) were put in pairs and their socio-sexual behaviors in response to a preoestrous female were monitored. Independent of social context (with or without female), VNX males exhibited less sniffing behaviors than C males, but their marking behaviors, although reduced, were not significantly different. Removal of the VNO dramatically reduced the frequency of both sexual behaviors (anogenital investigations, mounts) and intermale aggressive behaviors. However, VNO removal did not impair successful mating and had no effect on plasma testosterone levels. Lastly, VNX males always exhibited a significantly lower general activity level than C males. The decrease in sexual behaviors and the lack of aggressive intermale competition in responses to a preoestrous female possibly proceed from functional disturbances of central nervous areas connected to the vomeronasal system rather than from a chemosensory deficit per se.

Change in Photoperiodic Cycle Affects Life Span in a Prosimian Primate (Microcebus murinus

The lesser mouse lemur, a small prosimian primate, exhibits seasonal rhythms strictly controlled by photoperiodic variations. Exposure to day lengths shorter than 12 h results in complete sexual rest, fattening, lethargy, and reduced behavioral activities; whereas exposure to day lengths greater than 12 h induces sexual activity, an increase in behavioral activities, and high hormonal levels. The objective of this study was to test whether long-term acceleration of seasonal rhythms may affect survival and longevity of this primate. In captivity, acceleration of seasonal rhythms was obtained by exposing the animals to an accelerated photoperiodic regimen consisting of 5 months of long photoperiod followed by 3 months of short photoperiod. The age-specific survival rate in animals exposed from birth to accelerated photoperiodic conditions (n = 89) was compared to the age-specific survival rate of animals maintained under a natural photoperiod (n = 68). Independent of sexes, the mean life span (45.5 +/- 2.1 months) and maximal survival (79.3 +/- 3.3 months) were significantly (p < .01) shortened in mouse lemurs exposed to the accelerated photoperiodic cycle compared to those in animals living under annual photoperiod (63.2 +/- 2.5 and 98 +/- 3.9 months for mean life span and maximal survival, respectively). This reduction of about 30% of life span was not accompanied by a desynchronization of biological rhythms under photoperiodic control and was not related to an increase in reproduction or in duration of time spent in active conditions. However, when the number of seasonal cycles experienced by 1 individual is considered rather than chronological age, the mean life span was 5 seasonal cycles and maximum survival reached 9-10 cycles, independent of sex or of photoperiodic regimen. These results suggest that in mouse lemurs, as in other seasonal mammals, longevity may depend on the expression of a fixed number of seasonal cycles rather than on a fixed biological age.

Manipulation of sex ratio at birth and maternal investment in female mouse lemurs ( Microcebus murinus, Primates)

The lesser mouse lemur, a polygynous prosimian primate, demonstrates significant bias of sex ratio at birth in agreement with the predictions of the Local Competition Resource model for adaptive adjustment of sex ratios. When isolated prior to conception, females overproduced daughters while grouped females demonstrated a significant inverse tendency. Biased sex ratios were dependent neither on mother's body condition nor on litter size, suggesting that bias occurred at conception. The maternal investment allocated to offspring in terms of foetal growth, infant growth and survival until weaning did not differ according to the sex of newborn. Nevertheless, male newborn promoted maternal behaviour during early infancy (from birth to day 15) since in litters without males, survival and growth of neonate females significantly decreased. In mouse lemurs, social communication primarily relies on olfactory cues and significant biased sex ratios can be obtained by exposing isolated females to urinary cues from other females. Urinary stimulation was delivered from the beginning of sexual activity until oestrus. The direction of bias depended upon the temporal occurrence of chemical signal exposure, while female fecundity depended upon its duration. Possible mechanisms involved in sex biased conception are discussed.

Manipulation of sex ratio at birth by urinary cues in a prosimian primate

The lesser mouse lemur (Microcebus murinus) is a prosimian primate which presents evidence of sex ratio bias of offspring that agrees with the direction of bias predicted by the local resource competition model for facultative sex ratio adjustment. That is, females overproduced sons when grouped prior to mating, whereas isolated females exhibited the opposite tendency. In this solitary species, social communication relies heavily on urinary chemical signals. To test the hypothesis that sex biases induced by social factors may be linked to urinary cues, isolated females were exposed (n = 76) or not (control group, n = 16) to urinary cues from other reproductively active females from the beginning of the breeding season (induced by long photoperiod) until oestrus. During that period, females were either continuously (n = 17) or partially (n = 59) exposed to chemosignal stimulation. Females in oestrus were placed in contact with a breeding male and subsequently isolated until they gave birth. All females entered oestrus but the timing of oestrus was significantly delayed by 1 week in urine-exposed females. A general depressive effect of long-term urine exposure on fecundity was demonstrated, involving fewer impregnations, higher abortion frequency and smaller litter sizes. Among females giving birth (n = 55) to a total of 129 young, a significant positive correlation was found between sex ratio bias towards males and the duration of urine exposure. However, the shift in sex ratio at birth depended on the duration of urine stimulation during a sensitive period extending from the beginning of the long photoperiod until the beginning of the follicular phase. In the absence of urinary cues during the sensitive period, females significantly overproduced daughters (32% males of 53 newborn). As urine exposure increased during the sensitive phase, the proportion of males in litters increased from 54% males (n = 50) in partially urine-exposed females to a significant bias towards males (69.2% of 26 newborn) in totally exposed females. The biased sex ratio in response to chemical cues did not show consistent relationships with maternal body weight, parity or litter size. Although the intrinsic mechanisms involved in sex-biased conceptions are not known, chemical cues could interact with the photoperiodic control of gonadotropin secretions.

Adaptation of skeletal myofiber types to arboreality

Skeletal muscles of primates are composed of fast-twitch/glycolytic (FG), fast-twitch/oxdative/glycolytic (FOG), and slow-twitch/oxidative (SO) myofibers, which are classified by differences in histochemical reactivity of reduced nicotinamide adenine dinucleotide dehydorgenase, mitochondrial glycerol-3-phosphate dehydrogenase, and myosin ATPase. The postural muscles have many SO myofibers. The locomotory muscles have many fast-twitch (FG and FOG) myofibers. The limb muscles of Japanese macaques, rhesus macaques, lesser bushbabies, and gray lesser mouse lemurs contain FG, FOG, and SO myofibers, whereas the muscles of slow lorises have FOG and SO myofibers and no FG myofibers. SO myofibers are involved in postural maintenances and function in preventation of fall from trees. FOG myofibers are used for continuous movements and locomotary and FG myofibers for short bursts of high activity. The SO and FOG myofibers are necessary for climbing a tree and living on a tree, adaptation to aloreality. Although the FG myofibers are dispensable in arboreal monkeys, they are developed greatly in primates' muscles that generate a large propulsive force for running, climbing, jumping, and leaping. The composition of myofiber types differs in analogous muscles. The differences are correlated with locomotory patterns of primates.

Molecular phylogeny based on the ?-casein and cytochrome b sequences in the mammalian suborder Ruminantia

Nucleotide sequences for the kappa-casein precursor proteins have been determined from the genomic DNAs or hair roots of the Ruminantia. The coding regions, exons 2, 3, and 4, were amplified separately via the three kinds of PCRs and then directly sequenced. The primers were designed from the sequence of bovine kappa-casein gene; they were applicable for the amplification of the kappa-casein genes from the 13 species in the Ruminantia except exon 2 of the lesser mouse deer. These results permitted an easy phylogenetic analysis based on the sequences of an autosomal gene. A phylogenetic tree was constructed from the mature kappa-casein sequences and compared with the tree of the cytochrome b genes which were sequenced from the same individuals. The Cervidae (sika deer, Cervus nippon) were separated from the branch of the Bovidae on the tree of kappa-casein genes with a relatively high confidence level of the bootstrap analysis, but included in the branch of the Bovidae on the tree of cytochrome b genes. The kappa-casein tree indicated a monophyly of the subfamily Caprinae, although the internal branches were uncertain in the Caprinae. The tree based on the nucleotide sequences of cytochrome b genes clearly showed the relationships of the closely related species in the genus Capricornis consisting of serow (C. smatorensis), Japanese serow (C. crispus), and Formosan serow (C. swinhoei). These results would be explained by the difference of resolving power between the kappa-casein and the cytochrome b sequences.

Sexual responses to urinary chemosignals depend on photoperiod in a male primate

In male lesser mouse lemurs, testicular size and plasma testosterone levels are controlled by photoperiodic variations but can be modified by urinary cues from conspecifics. To test whether urinary cues may have differential effects on testicular size and testosterone levels depending on the photoperiodic state of the receiver, isolated males were exposed for 4 wk to urinary cues from oestrous females or dominant males:—at the beginning of the breeding season induced by long photoperiod (LD),—during refractoriness to LD leading to spontaneous sexual regression and during sexual quiescence exhibited by males kept in short photoperiod (SD). Urinary chemosignals from females were always stimulatory producing significant increases in testosterone levels. By contrast, urinary cues from dominant males produced significant differential effects on reproductive function. They depressed sexual function only at the beginning of the breeding season. During SD or during refractoriness to LD, chemosignals were stimulatory leading to increases in testosterone levels and full development of testes. These results demonstrate that the same chemosignal may have opposite effect on sexual function of the receiver depending on endocrine mechanismsset up by photoperiod.