Male influence on oestrous cycles in female woolly opossum (Caluromys philander)

Plasma progesterone concentrations and the occurrence of oestrous cycles were studied in isolated woolly opossums subsequently subjected to male influences during a 40-day period. Pairing (N = 48) or exposure to male urine (N = 15) resulted in all females exhibiting oestrous during the stimulation phase, providing evidence that the activation of ovarian activity in the woolly opossum involves pheromonal cues from males. The latency of occurrence of oestrous in stimulated females depended upon their sexual state before male stimulation. In anoestrous females, the mean latency was 20.7 +/- 0.9 days (N = 35), a value which agrees with the duration of the follicular phase. In females which first entered oestrous before male stimulation, the latency of induced oestrous was inversely correlated to the date of occurrence of the previous oestrous. The inter-oestrous interval was normal (38.1 +/- 1 days, N = 5) when females were in oestrous at the beginning of male stimulation. In contrast, the inter-oestrous interval was significantly shortened (28.7 +/- 2 days, N = 7) or lengthened (51.1 +/- 1.7 days, N = 16) depending on whether females were in the luteal or follicular phases at the beginning of male stimulation. During pairing several females became pregnant and gave birth 24 +/- 0.9 days (N = 13) after copulation. In the woolly opossum, the response to male influences involves mechanisms similar to those observed in eutherians and results in enhancement and synchronization of oestrous cycles in females. Pheromonal interactions could play an important role in synchronizing oestrous cycles in wild females during the dry season, a period when animals regroup to feed on spatially localized food resources.     

Use of zygodactylous grasp by Caluromys philander (Didelphimorphia: Didelphidae)

The present report aims to quantify the use of zygodactylous (opposability of digits II to III) grasping in relation to positional modes and support size and orientation, in the highly arboreal, walking/climbing woolly opossum, Caluromys philander. For this purpose, four captive adult C. philander were intensively video-recorded and their positional behavior, hand grasp, and support size and orientation use were analyzed frame-by-frame. Overall, C. philander used a zygodactylous grasp in 81.3±1.2% of bouts. In terms of support features, this grasp was particularly common on (a) supports that could be wholly and partly held by the animals’ hand and (b) vertical supports in particular. In a comparable manner, zygodactyly dominated during above-support positional modes, but was significantly less used during bridging and suspension. The results show that zygodactyly provided an above-support secure and steady grasp on relatively unstable arboreal supports, by aligning the hand with the main axis of the support. This very likely assisted in controlling over the applied torques during cautious quadrupedal and climbing activities with extended hand contact that characterizes the locomotor strategy of C. philander. These observations need to be further tested by more detailed kinetic studies and on a larger sample of arboreal didelphids.     

Behavior and maintenance of the woolly opossum (Caluromys) in captivity

Circadian activity, general behavior, dietary requirements, and reproductive activity were recorded in a small laboratory colony (four females, six males) of two species of the woolly opossum (Caluromys lanatus and C derbianus) over a period of 3 years. The two species were indiscernable in all aspects of their behavior. Both were completely nocturnal and rarely active during daylight hours. General behavior was apparently related to many variables, particularly individual temperament and cage size. Even docile individuals were more excitable when housed in small cages. Although the woolly opossum is reported to prefer a meat diet, the opossums in this study remained healthy on a meat-egg-fruit diet, and showed a special liking for fruit, especially bananas. Vaginal smears indicated that females of the colony were cyclic, but all attempts to breed them were unsuccessful. Sexual behavior included pre-mount, pelvic-thrust displays on the part of the male, with complete repulsion by all females.     

Plasma progesterone, androstenedione and testosterone concentrations in freemartin heifers.

Plasma concentrations of testosterone, androstenedione and progesterone in freemartins, and normal cyclic and non-cyclic heifers were studied. The plasma testosterone concentrations were in general less than 10 pg/ml in all animals. The mean androstenedione concentration of 28 pg/ml in 10- to 12-month-old freemartins was significantly lower than the mean of 58 to 60 pg/ml for normal 10- to 12-month-old heifers. At 24 months of age the mean androstenedione concentration in the freemartins had risen significantly to 65 pg/ml.     

Chest-rubbing in captive woolly monkeys (Lagothrix lagotricha)

The correlates of chest-rubbing were studied in a captive group of woolly monkeys (Lagothrix lagotricha) to assess possible functions of territorial marking, spacing among competing groups or competing males, reproductive communication, marking to identify familiar environments, selfanointing, and displacement activity. Chest-rubbing was observed only in sexually mature monkeys and was a predominantly male activity. Females increased chest-rubbing when the original adult male died. Chest-rubbing by the first adult male was more common during the two months that he was mating with two females and at times when keepers were likely to be at the exhibit. The results suggest a reproductive function for chest-rubbing in both males and females. There is also support for chest-rubbing as a spacing activity.     

Highly conserved d-loop sequences in woolly mouse opossums Marmosa (Micoureus)

This study reports the occurrence of highly conserved d-loop sequences in the mitochondrial genome of the woolly mouse opossum genus Marmosa subgenus Micoureus (Mammalia, Didelphimorphia, Didelphidae). Sixty-six sequences of Marmosa (Micoureus) demerarae, Marmosa (Micoureus) constantiae, and Marmosa (Micoureus) paraguayanus were amplified using universal d-loop primers and virtually no genetic differences were detected within and among species. These sequences matched the control region of the mitochondrial marsupial genome. Analyses of qualitative aspects of these sequences revealed that their structural composition is very similar to the d-loop region of other didelphid species. However, the total lack of variability has not been reported from other closely related species. The data analyzed here support the occurrence of highly conserved d-loop sequences, and we found no support for the hypothesis that these sequences are d-loop-like nuclear pseudogenes. Furthermore, the control and flanking regions obtained with different primers corroborate the lack of variability of the d-loop sequences in the mitochondrial genome of Marmosa (Micoureus).     

Variations of chromosomal structures in Caluromys philander (Didelphimorphia: Didelphidae) from the Amazon region

Caluromys is considered to be one of the most ancient genera of extant marsupials and is positioned among the basal taxa of the family Didelphidae. At least two species occur in Brazil, C. philander and C. lanatus, both of which have 2n = 14 chromosomes. For the first time, we present evidence of an intrapopulation polymorphism of the sexual chromosome pair in C. philander females from the Central Amazon region. Detailed cytogenetic results of animals from three localities on the Amazon region were analyzed using classical cytogenetics (NOR, C-Band and G-Band) and molecular techniques (18S rDNA and telomere probes). Similar to other conspecific individuals, the diploid number of these animals is 2n = 14, and their fundamental number is 24, with NOR present on the 6th autosomal pair. The X chromosome presented variation detectable by G banding, suggesting a pericentric inversion.     

Food preferences of captive gray short-tailed opossums (Monodelphis domestica)

The gray short-tailed opossum has been a subject in behavioral and biomedical studies for the last quarter century, but researchers know little about its preferred diet. The authors describe a study designed to determine food preferences of this species for the purpose of identifying suitable rewards to be used in behavioral studies.     

Bird predation by captive woolly monkeys (Lagothrix lagotricha)

Vertebrate predation has not been reported for woolly monkeys (Lagothrix lagotricha) in their natural habitat. However, bird predation has been observed in captivity. The present report is based on 15 incidents of bird predation that occurred during a 1-year observational study of the nine woolly monkeys at the Louisville Zoo. All identified captures were by females. The captor and her prey were frequently pursued by the other monkeys. Social rank was related to attempts to steal the prey. Consumption was characterized by much chewing and frequent alternation between the prey and highly fiberous substances. Predation was not characterized by stereotypical behaviors for pursuit or killing of prey, but instead suggested opportunistic capture by a generalized organism. The low frequency of bird predation by captive woolly monkeys may indicate that a similar level of predation has gone undetected in the study ofLagothrix in the wild.     

Diurnal variations in serum testosterone concentrations of captive adult male chacma baboons (Papio ursinus)

Captive adult male chacma baboons (Papio ursinus) housed with natural lighting exposure and blood sampled at 3-hr intervals showed significant diurnal variations in serum testosterone concentrations. Low mean concentrations were found at 0800 hr approximately 1 hr after sunrise and mean concentrations were their highest at 2000 hr approximately 1 ¼ hr after sunset.     

Plasma concentrations of progesterone, oestrogens, testosterone and LH-like activity during the oestrous cycle of the camel (Camelus dromedarius)

Peripheral plasma concentrations of progesterone, total oestrogens and testosterone (measured by RIAs) and LH (monitored by the mouse Leydig cell bio-assay) were measured in 8 female camels for a complete oestrous cycle (23.1 +/- 1.2 days). The absence of an LH surge and a low concentration of progesterone (less than 1 ng/ml) during oestrus (5 days) and throughout the cycle indicated a failure of spontaneous ovulation and absence of a subsequent luteal phase in this species. High concentrations of testosterone and oestrogens indicated that the oestrous cycle in the camel is mostly follicular and that the increasing values of the two hormones during follicular development (5 days) is probably the stimulus to behavioural oestrus.     

Plasma progesterone concentrations in the female Natal clinging bat (Miniopterus schreibersii natalensis)

Plasma progesterone concentrations measured by radioimmunoassay in the Natal clinging bat remained below 2.01 ng/ml during lactational anoestrus but increased significantly during the period of delayed implantation. Values peaked at implantation but were followed by a significant decrease thereafter. Concentrations remained low (less than 6.0 ng/ml) during the initial period of fetal development (153-180 days post coitum) and attained peak values (85.6-181.3 ng/ml) 216-222 days after fertilization. The marked post-implantation increase in progesterone concentrations coincided with a significant increase in placental weight.     

Plasma progesterone concentrations in female little brown bats (Myotis lucifugus) during hibernation

Monthly collections of hibernating little brown bats contained (1) nulliparous females with small uteri and no antral follicles, (2) nulliparous females with swollen uteri and mature follicles, and (3) parous females, which, despite obvious differences in reproductive status, had equivalent plasma progesterone values. During the principal study season, mean monthly progesterone concentrations (measured by radioimmunoassay) showed recurrent increases with an apparent periodicity of about 60 days, but limited data obtained in the subsequent season did not. However, comparison of activity patterns in the two seasons with monthly progesterone concentrations suggests that ovarian activity during hibernation is affected by variations in metabolic level. We saw no evidence that nulliparous bats with small uteri developed antral follicles during hibernation. Despite their apparent immaturity, however, they had cornified vaginae and most were demonstrably inseminated. These indications of oestrus and the lack of differences between their plasma progesterone concentrations and those of patently mature females suggest that they were physiologically post-pubertal but failed to complete folliculogenesis before entering hibernation.     

Pregnancy-specific elevations in fecal concentrations of estradiol, testosterone and progesterone in the domestic dog (Canis familiaris)

Estradiol (E2), testosterone (T) and progesterone (P4) concentrations were determined by enzyme-immunoassay in aqueous extracts of fecal samples obtained during anestrus, proestrus, estrus and metestrus of 11 nonpregnant and 11 pregnant bitches. Fecal hormone concentrations (ng/g) changed in relation to stage of cycle. Mean fecal steroid concentrations in 22 anestrous bitches and 3 ovariectomized bitches were low and similar for E2 (53 +/- 5 and 27 +/- 2), T (60 +/- 7 and 36 +/- 6), and P4 (62 +/- 6 and 86 +/- 15). Within 0 to 3 d of the ovulatory LH surge fecal E2 reached peak concentrations (301 +/- 38). The T peaks (281 +/- 41) were coincident or 1 to 3 d later. Fecal P4 was then elevated for approximately 2 m.o. Between Days 26 and 45 after ovulation, mean fecal P4 concentrations were higher (P < 0.05) in pregnant (401 +/- 60) than in nonpregnant bitches (164 +/- 23) and peak fecal P4 concentrations in individual animals were higher (P < 0.01) in pregnant (812 +/- 121) than in nonpregnant bitches (425 +/- 97). In the same period mean concentrations of E2 (117 +/- 13 vs 61 +/- 5) and T (102 +/- 10 vs 70 +/- 6) were also higher (P < or = 0.05) in pregnant than in nonpregnant bitches. Serum E2, T and P4 concentration were positively correlated (P = 0.1) with concentration in fecal samples obtained one day after serum collection. Although serial fecal ovarian steroid concentrations demonstrate the time course of ovulatory cycles, the diagnostic value of individual fecal samples appears limited. The ratios of peak to basal values were approximately 6, 5 and 7 for E2, T and P4, respectively, and were considerably lower than ratios of 12 to 50 previously reported for serum or plasma concentrations. The results demonstrate that there are pregnancy-specific increases in P4, E2 and T production reflected in fecal concentrations. While such increases are reflected in fecal samples, they are generally not evident in serum or plasma concentrations because of increased hemodilution, metabolism and clearance in pregnant bitches. The physiological stimulus for these increases, presumably ovarian in origin, or the potential role of prolactin is not known.     

Plasma concentrations of testosterone and LH in the male dog

Blood samples were withdrawn every 20 min from 3 conscious intact and 2 castrated mature males during non-consecutive periods of 12 h during the light and dark phases of the lighting schedule (intact dogs) and of 11 h during the light period (castrated dogs). In the intact dogs testosterone concentrations ranged from 0.4 to 6.0 ng/ml over the 24-h period. LH concentrations varied from 0.2 to 12.0 ng/ml. In all animals, LH peaks were clearly followed, after about 50 min, by corresponding testosterone peaks, but no diurnal rhythm could be established. LH concentrations in the castrated dogs were high (9.8 +/- 2.7 (s.e.m.) ng/ml), and still showed an episodic pattern in spite of the undetectable plasma testosterone levels.     

Altered androstenedione to testosterone ratios and LH concentrations during musth in the captive male Asian elephant (Elephas maximus)

Greater concentrations of androstenedione than testosterone were usually present during periods of non-musth in plasma collected weekly for various periods up to 2 years in 8 male Asian elephants (4-35 years of age). For the 6 males that exhibited musth the androstenedione/testosterone ratio shifted greatly in favour of testosterone. The severity of musth was assessed weekly using a scale of 1 to 5 for each of 8 behavioural traits including urine dribbling, temporal gland secretion and aggression. A significant correlation (P less than 0.05) was noted between plasma testosterone concentrations and the musth score value in 5 of 6 musth episodes. Brief shifts in the ratio of two androgens when testosterone predominated (n = 106) were seen during the non-musth period in 3 of the males studied continuously for 2 years. In 82% of these instances, stimuli of a sexual or aggressive nature had occurred in the preceding 48 h (chi 2, P less than 0.01). A heterologous bovine assay was used to measure LH values in plasma collected every 15 min for 12 h. Increases in testosterone concentrations followed pulsatile increases in plasma LH concentrations during 7 non-musth periods in 4 animals. Apart from pulse frequency, increases in the variables describing pulsatile LH secretion were seen in 2 strong musth and 2 mild musth episodes compared to non-musth values. A strong musth, however, was characterized by a much greater increase in pulsatile testosterone secretion than was a mild musth and which may be a function of the duration of musth.