Plasma concentrations of progesterone and testosterone in captive woolly opossums (Caluromys philander)

Plasma testosterone and progesterone concentrations were measured in captive woolly opossums, a didelphid marsupial originating from neotropical forests in French Guyana. Although not exposed to cyclic environmental conditions as in the field, both sexes exhibited spontaneous circannual changes in sexual hormones. Males showed synchronous variations in plasma testosterone characterized by significant elevated concentrations during April and September (8.6 +/- 1 ng/ml, N = 5) and lower levels from May to July (3.6 +/- 0.4 ng/ml). In females, synchronous periods of 2-3 successive oestrous cycles occurred. Between these periods, females remained acyclic. The oestrous cycle, determined by urogenital smears, lasted 28-45 days (n = 14) and included a 20-day spontaneous luteal phase in which progesterone concentrations reached 30-40 ng/ml plasma. Even though testosterone concentrations in paired males increased significantly in response to oestrous periods of the paired females, spontaneous circannual rhythms of sexual activity were not well synchronized between the sexes in captivity. When compared to field data, sexual activity of captive animals followed a pattern similar to that in wild animals, without any changes in males but with a delay of 3 months in females.     

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.     

Carpal ontogeny in Monodelphis domestica and Caluromys philander (Marsupialia)

Carpal bones have experienced numerous changes during marsupial evolution, even though their diversity and development remain poorly studied. The aim of this work was to document adult form and the pattern of mesenchymal tissue condensation and formation of chondrification and ossification centers in the hand of two marsupials. Two fundamental questions were asked: whether the loss of embryonic precursors was associated with the loss of adult elements, or whether there were developmental signs of ancestral mammalian elements that have been fused or lost in marsupial taxa. We were also interested to find out whether there is sexual dimorphismus in the carpals, as has been reported for some didelphids. Histological sections, cleared and stained specimens and macerated skeletons representing an ontogenetic series of Monodelphis domestica were used to document carpal development. Comparisons were made with perinatal stages of Caluromys philander and with adult specimens of other marsupials. A prenatal M. domestica in the 13th day after conception has a cell condensation that because of its position is homologized with a centrale, which is at birth already lost or fused. Neonatal M. domestica and C. philander have the number and arrangement of their adult carpal anatomy. Trapezium and trapezoid start ossification later than most other carpals, while pisiform and prepollex are the last to do so. Adult males of M. domestica have relatively larger and more robust pisiforms, compared to other carpals, than females. This sexual dimorphism develops relatively late as it was not recorded in male specimens around 160 days old. An extra sesamoid bone located just distal to the radius and proximo-palmar to the scaphoid was recorded in specimens of C. philander, C. derbianus and Didelphis virginiana.     

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.     

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.     

Demographic consequences of population subdivision on the long-furred woolly mouse opossum (Micoureus paraguayanus) from the Atlantic Forest

Habitat destruction and fragmentation severely affected the Atlantic Forest. Formerly contiguous populations may become subdivided into a larger number of smaller populations, threatening their long-term persistence. The computer package VORTEX was used to simulate the consequences of habitat fragmentation and population subdivision on Micoureus paraguayanus, an endemic arboreal marsupial of the Atlantic Forest. Scenarios simulated hypothetical populations of 100 and 2000 animals being partitioned into 1–10 populations, linked by varying rates of inter-patch dispersal, and also evaluated male-biased dispersal. Results demonstrated that a single population was more stable than an ensemble of populations of equal size, irrespective of dispersal rate. Small populations (10–20 individuals) exhibited high instability due to demographic stochasticity, and were characterized by high rates of extinction, smaller values for metapopulation growth and larger fluctuations in population size and growth rate. Dispersal effects on metapopulation persistence were related to the size of the populations and to the sexes that were capable of dispersing. Male-biased dispersal had no noticeable effects on metapopulation extinction dynamics, whereas scenarios modelling dispersal by both sexes positively affected metapopulation dynamics through higher growth rates, smaller fluctuations in growth rate, larger final metapopulation sizes and lower probabilities of extinction. The present study highlights the complex relationships between metapopulation size, population subdivision, habitat fragmentation, rate of inter-patch dispersal and sex-biased dispersal and indicates the importance of gaining a better understanding of dispersal and its interactions with correlations between disturbance events.     

Synchronization of oestrous cycles in sable antelope

Techniques for manipulating the oestrous cycle of sable antelope, Hippotragus niger, were evaluated in a captive population of 24 females maintained at the Smithsonian Institution's Conservation and Research Center in Front Royal, VA, USA. A secondary objective was to demonstrate the effectiveness of fecal steroid monitoring techniques as a non-invasive method of tracking experimental manipulations. Controlled Internal Drug Releasing (CIDR) devices designed for cattle (type B, reduced in length by 5 cm to fit the sable antelope's smaller reproductive tract) were more effective than CIDR devices designed for goats (type G) at delivering progesterone into circulation, and maintained serum progesterone at levels up to 86.1+/-7.8% of normal luteal concentrations in females whose spontaneous ovarian activity had been inhibited with melengestrol acetate. Serum progesterone and fecal progestagen measurements were highly correlated (P<0.05). Synchronization treatments of prostaglandin (PG) F2alpha alone and in combination with modified CIDR-B devices (12-day insertion interval) were both effective in inducing synchronized ovulation, however the PGF2alpha/modified CIDR-B treatment resulted in more precise synchrony and a shorter latency to ovulation than did PGF2alpha alone. In a separate experiment to characterize the temporal relationship between synchronization treatment, behavioral oestrus and ovulation, onset of behavioral oestrus occurred 34.1+/-5.7 h following PGF2alpha/modified CIDR-B treatment. Mean duration of the induced oestrus was 24.9+/-4.3 h. The first detectable rise in fecal progestagens occurred 5.1+/-1.0 and 4.1+/-1.0 days following PGF2alpha/modified CIDR-B treatment in groups of females housed with and without an adult male, respectively, indicating that the presence of a male did not accelerate the onset of the induced cycle.     

Isolation and characterization of microsatellite loci in the woolly mouse opossum,Micoureus paraguayanus (Marsupialia: Didelphimorphia)

Five microsatellite loci were isolated and characterized within the woolly mouse opossum (Micoureus paraguayanus), a Neotropical marsupial, using an enrichment cloning procedure. Between four and seven alleles were detected per locus, with expected heterozygosity ranging from 0.358 to 0.560. These microsatellites should provide useful markers in a variety of genetic analyses to examine parentage, inbreeding, population structure and population dynamics in fragmented forest habitats.     

Male Grey squirrel (Sciurus carolinensis) reproductive cycles in Britain

A synchronized seasonal cycle of sexual regression and development is described for the male Grey squirrel in Britain. Sexual development is maximal in December and May and minimal in August. The seasonal cycle can be overriden, but this is exceptional. Comparisons with previous work and the suggestion that the synchronized seasonal sexual cycle is general for Grey squirrels in Britain, and probably America, are made.     

Effects of urine from pregnant and lactating female house mice on oestrous cycles of adult females.

It was demonstrated that mice treated with urine from pregnant or lactating females experienced longer periods of oestrus than did mice treated with water or urine from singly caged females. Application of urine by means of perforated capsules placed in the cage of the test mouse showed that the factor(s) responsible for the longer periods of oestrus was an airborne pheromone. The females experiencing longer oestrous periods ovulated (ova in oviducts), became pregnant and gave birth.     

Male diet and age influence to inhibit female remating in Ceratitis capitata (Diptera: Tephritidae)

This study evaluated the influence of age and adult nutritional status of Ceratitis capitata males on their ability to inhibit female remating. Their roles and that of copula duration on the amount of sperm transferred to female spermathecae were also analysed. After emergence, adults were kept in separate groups according to their diets (either high protein – 6.5 g of brewer’s yeast, or low protein – 3.5 g of brewer’s yeast) and their age at the time of use in experiments (4, 8, 12, 16 and 20 days old). The results demonstrated that: (i) male age was not a factor that influenced remating when females mated with well‐nourished males; however, the youngest males (4 days old) in the low‐protein group were less efficient in preventing female remating; (ii) 12‐ and 16‐day‐old males fed on a high‐protein diet transferred and produced more sperm than males of other groups; (iii) there was no correlation between copula duration and the amount of sperm transferred to the female; the longest copula durations were observed among low‐protein‐diet/20‐day‐old males. These results suggest that age and nutrition influence the ability of the males to inhibit female remating. The sterile insect technique is most effective when females do not remate after coupling with sterile males, and therefore, the capacity to inhibit female remating is an important characteristic of males released in the field.     

Remote temperature sensing of oestrous cycles in cattle

Radio transmission of deep-body temperature changes in cattle was found to be a feasible method of collecting information for husbandry decisions. Oestrous cycles were plotted and ovulations detected so that cattle were effectively bred artificially. Abnormalities of the cycle pattern accurately indicated abnormal reproductive phenomena. The presence of febrile illness was also detectable. The occurrence of silent oestrus was clearly demonstrated.     

Male axillary secretions influence women's menstrual cycles: a critique

W. B. Cutler et al. report in the December 1986 issue of Hormones and Behavior (20, 463-473), that women treated with axillary extract from male donors showed reduced variability in menstrual cycle lengths and a reduced proportion of aberrant cycles. The initial samples--seven subjects treated with the male extract and nine subjects treated with blank/ethanol--did not differ significantly in the frequency of aberrant and normal cycles. The cycles of four subjects who were having weekly coital activity were removed from the samples, since coital activity has been shown to be associated with normal-length cycles. The frequency differences of aberrant and normal cycles in the reduced extract and placebo samples were statistically significant. The experiment's conclusions are questionable because (1) the decision to remove the cycles of the four women who had weekly coital activity was not justified by the evidence from this experiment and (2) the researchers lacked an observed preexperimental data base from which to measure changes in the women's cycle lengths.     

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.