Histology of vermiform appendix-like organ in slow loris.

The vermiform appendix-like organ (VALO) of the slow loris was investigated for its histology and immunohistochemical characteristics. The VALO has a much thinner wall with flat folded mucosa and shallower crypts than the cecal mucosa, while cellular components and population of the mucosa were similar to those of the cecum. No coalescent lymph nodules were seen in the submucosa. Immunohistochemically 5-HT-positive cells in the crypts and CD3- and CD8-positive lymphocytes in the lymph nodules were shown in the VALO as well as in the cecum. These findings suggest that the VALO is a low-differentiated vermiform appendix of the slow loris.     

Multidirectional chromosome painting reveals a remarkable syntenic homology between the greater galagos and the slow loris

We report on the first reciprocal chromosome painting of lorisoids and humans. The chromosome painting showed a remarkable syntenic homology between Otolemur and Nycticebus. Eight derived syntenic associations of human segments are common to both Otolemur and Nycticebus, indicative of a considerable period of common evolution between the greater galago and the slow loris. Five additional Robertsonian translocations form the slow loris karyotype, while the remaining chromosomes are syntenically equivalent, although some differ in terms of centromere position and heterochromatin additions. Strikingly, the breakpoints of the human chromosomes found fragmented in these two species are apparently identical. Only fissions of homologs to human chromosomes 1 and 15 provide significant evidence of a cytogenetic link between Lemuriformes and Lorisiformes. The association of human chromosomes 7/16 in both lorisoids strongly suggests that this chromosome was present in the ancestral primate genome.     

Reproductive and dietary parameters in wild greater galago populations

Information concerning habitat, body size, reproductive status, and diet was recorded from 348 greater galagos, captured at six different localities in Tanzania and southern Africa between 1953 and 1955. The localities extended from Pemba Island in the north to Chikwawa, Malawi, in the south and varied broadly in the same order in degree of climatic aridity— from well-watered clove and coconut plantations to seasonally very dry woodland. Animals from the three northern localities fell within the geographic range of Galago garnettii,while the rest were assumed to be G. crassicaudatus.Statistical analysis of body size parameters confirmed this allocation. Data on fetal occurrence, vaginal and labial condition, and lactation indicate a restricted breeding season for both species, with peak proportions in estrus in August in G. garnettiiand in May-July in G. crassicaudatus.Gut content data indicate a variety of foods, with a preponderance in the northern localities of soft fruit such as mango, pawpaw, and coconut pulp; gum was a major carbohydrate source in the southernmost localities. Contrary to expectations, tooth damage, in the form of both loss and breakage, was much more prevalent in G. garnettiithan in G. crassicaudatus.The teeth most commonly lost were the upper incisors— perhaps because of the high acid and sugar content of a frugivorous diet. The high incidence of breakage of the lower incisors and upper canines indicates the inclusion of hard-shelled food sources in the diet of G. garnettii.     

Observations on the pyramidal tract of the slow loris

The pyramidal system of the slow loris was investigated physiologically and histologically. The cerebral response to medullary pyramid stimulation was mapped and found to distribute in two separate foci, rostral to the hand and foot somatosensory foci. The tract was found to contain about 204,000 fibers at the midolivary level on one side, with about 85% of the fibers less than 2 Μm and 1% greater than 4 Μm. Calculation of the amplitude and configuration of the true antidromic response, based on the histological findings, disagreed with the observed response. The latter was found to be analogous to the rwave of the American opossum, which appears to result from intracortical pyramidal tract collateral activation of the cerebral neurons. This response is not present in the macaque monkey.     

Effects of social and inanimate enrichment on the behavior of yearling rhesus monkeys

Certain types of inanimate environmental enrichment have been shown to positively affect the behavior of laboratory primates, as has housing them in appropriate social conditions. While social housing is generally advocated as an important environmental enhancement, few studies have attempted to measure the influence of social conditions on the effects of inanimate enrichment or to compare the relative merits of social and inanimate enhancements. In the present study, inanimate enrichment (predominately physical and feeding enhancements) resulted in increased species-typical behavior for socially restricted subjects. However, social enrichment (living in groups) appeared to be more beneficial for young rhesus monkeys, leading to increased species-typical activities and decreased abnormal activities. The behavior of one cohort of yearling rhesus monkeys (Macaca mulatta) housed in small peer groups was compared with the behavior of four yearling cohorts housed in single cages. Half the animals in each cohort received a three-phase enrichment program and the rest served as controls. Group-housed yearlings spent significantly more time feeding and exploring and significantly less time behaving abnormally, self-grooming, and drinking than did singly housed yearlings. Enriched subjects spent significantly more time playing by themselves, and significantly less time self-grooming and exploring than did controls. Among group-housed subjects only, there were no differences between enriched and control monkeys. Captive primates should be housed socially, whenever appropriate, as the first and most important step in an enrichment program, with the provision of inanimate enhancements being considerably less important. Limited resources for inanimate enrichment programs instead should be focused on those individuals who can not be housed socially. © 1996 Wiley-Liss, Inc.     

Effects of ovariectomy and estradiol replacement therapy upon the sexual and aggressive behavior of the greater galago (Galago crassicaudatus crassicaudatus)

The effects of ovariectomy and estradiol treatment upon sexual and aggressive behavior were studied in a prosimian primate, the greater galago. Ovariectomized galagos were sexually unreceptive and frequently aggressive, but retained their sexual attractiveness to males. When females were treated with estradiol monobenzoate, however, their aggression and refusals of males' mounting attempts decreased markedly. Although males mounted these females, they usually failed to copulate, possibly because the females did not perform certain postural adjustments which assist males to intromit. Estradiol benzoate alone, even in large doses, does not fully restore patterns of mating behavior in ovariectomized female greater galagos. These observations on a prosimian primate are in striking contrast to the results of similar work on Old World monkeys and chimpanzees.     

Locomotion of the slow loris in a designed substrate context

This report analyzes the locomotion of a slow loris, Nycticebus coucang, in a designed substrate context composed of dowels varying in: (1) thickness, including diameters of 42mm, 20mm, 10mm, and 7mm; (2) inclination, including horizontal, diagonal, and vertical; (3) density, with one-half the cage more densely furnished with dowels than the other. Tabulation of frequencies of use of these different classes of substrate revealed preferences for thicker (20mm and 42mm) and more horizontally inclined surfaces, but not for either of the two sections of the cage. The data for the parameters of thickness and inclination agree with those obtained by Charles-Dominique ('71) for free-ranging Perodicticus, both sets contrasting with his data on substrate use by the sympatric Arctocebus. Locomotor performance, as judged by gait and segmental kinematic patterns, was, however, markedly different in the two sections, as well as on the wire wall of the cage. Analysis of these quantitative and qualitative data suggests that the interaction between the cheiridea and substrate parameters frequently determines the expression of other features of locomotor performance.     

Protein polymorphism and genetic divergence in slow loris (genusNycticebus)

In this study, protein electrophoresis was assayed to detect genetic variation in GenusNycticebus. A total of 29 samples (2N. coucang and 27N. pygmaeus) were analyzed for 42 genetic loci. In the 27 samples ofN. pygmaeus, 4 loci were observed to be polymerphic. Therefore, the estimatedP value (proportion of polymorphic loci) is 0.095, theA value (average number of alleles each locus) is 1.045, and theH value (mean individual heterozygosity) is 0.040. After comparing theH ofN. pygmaeus with those of other primates reported, we found that the protein variation inN. pygmaeus is slightly lower than the average level. Additionally, we also observed obivious allele difference betweenN. pygmaeus andN. coucang. There are no shared alleles between these two species in eight loci. TheNei's genetic distance between them was calculated as 0.2541, which falls in the spectrum of genetic difference between species in primates.     

Activity budget and positional behavior of the Mysore slender loris (Loris tardigradus lydekkerianus): implications for slow climbing locomotion.

Both predator defense and feeding ecology models have been proposed to explain the relatively slow climbing locomotion of the Lorisinae. During a study of the socioecology of the Mysore slender loris (Loris tardigradus lydekkerianus) in Tamil Nadu, India, six categories of behavior and eleven different postures were recorded to estimate a general activity budget for the slender loris, and are examined here particularly in relation to slow climbing locomotor strategies. Reactions to potential predators are also described. The main study population was composed of 15 animals. Activity budgets were compiled in three ways: all instantaneous point samples collected over 1,173 h pooled (n = 13,717), the means of individual lorises (n = 15) and behavior at the moment of first contact (n = 357). No significant difference was found between these three data sets. Approximately 45% of the activity budget was spent in inactive behaviors including sitting vigilant, resting and sleeping. Foraging and traveling comprised nearly half the activity budget, with the rest of the time spent grooming. The most common postures assumed by lorises were sitting and quadrupedal walking. Individual lorises were relatively gregarious and spent up to half their activity budget with other animals. Unlike pottos and angwantibos, lorises did not freeze, head butt or drop from branches in reaction to potential predators, but either ignored them, fled or made loud calls. Cryptic and slow climbing locomotion were used before traveling on open ground between discontinuous substrates, thereby supporting hypotheses relating to predator pressure, and also before capturing fast moving insect prey, supporting hypotheses relating to diet. It is proposed that a divergence in foraging strategies between bushbabies and lorisines may be the best adaptive explanation for their behavioral and morphological differences, including predator defense mechanisms.     

Density and microhabitat use of Bengal slow loris in primary forest and non-native plantation forest

The extent of planted forests has greatly increased in the tropics, but their conservation value while assumed to be low, is largely unknown. We compared the density and microhabitat selection of a nocturnal arboreal primate, the Bengal slow loris (Nycticebus bengalensis), in mostly undisturbed, evergreen tropical forest to those in 15-18 year old Acacia/Leucaena plantations with significant secondary regrowth, and <15 year old plantations with little regrowth. Based on estimates derived from distance sampling, loris densities in older plantations were nearly identical to primary forest (4.26 vs. 4.00 lorises per square kilometer), although encounter rates were three times higher in the older plantations probably owing to the lower detection probability in the more complex vegetation of the primary forest. The mean density estimate for the younger plantation was one-third of the above habitats (1.27 lorises per square kilometer), although not statistically different. Lorises tended to use larger diameter and taller trees, with a greater crown depth than randomly sampled trees, and tended to avoid habitats with sparsely crowned trees. The older plantations had trees with lower basal area and shorter stems than the primary forest; however, the older plantations contained higher densities of Bauhinia lianas, a commonly eaten food source and did not contain the red giant flying squirrel (Petaurista petaurista), a potential competitor. Although it is unknown whether the Bengal slow loris would persist without the presence of primary forest in the landscape, we suggest that older plantations have conservation value for at least selected species and as such, could be better managed to increase this value.     

Excretion of radiolabeled estradiol metabolites in the slow loris (Nycticebus coucang)

The excretion pattern of estradiol was studied in the slow loris Nycticebus coucang) and the ring-tailed lemur (Lemur catta) in order to compare steroid excretion in two representative prosimian species. Daily urinary estrone conjugate measurements in the female loris provided little information when applied over prolonged periods. As a result of these negative data, a metabolic study was performed to determine if estrogen excretion patterns in the slow loris differed from those in the lemur, where urinary assays proved a useful tool in characterizing reproductive cycles. Radio-labeled estradiol was injected intravenously, and serial urine and fecal collections were analyzed for radiolabeled metabolites. The results of these studies demonstrate that more than 92% of the radiolabel was excreted in the feces of the loris, in contrast to only 16% excreted in the feces of the lemur.     

Interactions between a wild Bornean orang-utan and a Philippine slow loris in a peat-swamp forest

All documented orang-utan–loris interactions have been from Sumatra, where lorises were opportunistically preyed upon by orang-utans. In this paper, we describe two accounts of the Bornean orang-utan (Pongo pygmaeus wurmbii) interacting with the Philippine slow loris (Nycticebus menagensis). The interactions were by two adolescent female orang-utans. No attempts to catch the loris were observed on either occasion. Neither interaction was hostile. During the second observation, which was more detailed, we considered the behaviour to be play rather than aggression or attempted predation. Based upon the lack of interest from the adult females during these rare encounters, we propose that the behaviour represents play or non-aggressive exploration rather than predation.     

Composition of muscle fibers in the slow loris,using the m. biceps brachii as an example

Histological examination of the skeletal muscle of the slow loris, which displays slow movement and locomotion among the prosimians, revealed a muscle fiber composition which differed from the general condition in mammals. Three types of muscle fiber cells were therefore analyzed quantitatively in order to elucidate their specificity. The skeletal muscle of the limbs of the slow loris was predominantly composed of red muscle fibers (type I) showing persistent tonic contraction.