Transneuronal degeneration in the Rolando substance of the primate spinal cord evoked by axotomy-induced transganglionic degenerative atrophy of central primary sensory terminals

Summary Transection of the sciatic nerve in Rhesus monkeys and the consequent transganglionic degenerative atrophy (TDA) of central terminals of primary afferents result in transneuronal degeneration of substantia gelatinosa (SG) cells. Severe degeneration is characterized by an increased electron density of the nucleus and by conspicuous shrinkage of the cytoplasm, mitochondrial swelling, dilation of cisterns of the rough-surfaced endoplasmic reticulum, accumulation of free ribosomes and an electron-dense material in the cytoplasm. In the mild form, dilation of cisternal elements of the endoplasmic reticulum, swollen mitochondria and accumulation of free ribosomes takes place. About 10% of SG cells in segment L₅ undergo the severe form whereas the rest shows signs of the mild form. Cytoplasmic alterations that occur during transneuronal degeneration seem to start at the level of subsurface cisterns. Dendrites and axons of transneuronally degenerating SG cells also show a conspicuous electron density. By analyzing the synaptic relationships of such darkened dendrites, connections in the upper dorsal horn can be deciphered. Modular units of the primary nociceptive analyzer that evaluate noxious and innocuous inputs on the basis of thin versus thick (AC/A) afferent activity and subjecting them to descending control appear to be recruited from structurally dispersed elements of synaptic glomeruli. These are arranged alongside dendritic processes of large antenna cells which relay impulses to projection cells of the spinothalamic tract.     

The effects of feedback lighting on the circadian drinking rhythm in the diurnal new world primate Saimiri sciureus

Feedback lighting provides illumination primarily during the subjective night (i.e., the photosensitive portion of the circadian cycle) in response to a given behavior. This technique has previously been used to test the nonparametric model of entrainment in nocturnal rodents. In three species (Rattus norvegicus, Mesocricetus auratus, and Mus musculus), the free-running period of the locomotor activity rhythm was similar whether the animals were exposed to continuous light or discrete light pulses occurring essentially only during the subjective night (i.e., feedback lighting). In the current experiments, feedback lighting was presented to squirrel monkeys so that light fell predominantly during the subjective night. Feedback lighting was linked to the drinking behavior in this diurnal primate so that when the animal drank, the lights went out. Despite the seemingly adverse predicament, the monkeys maintained regular circadian drinking rhythms. Furthermore, just as the period of the free-running activity rhythms of nocturnal rodents exposed to continuous light or feedback lighting were similar, the period of the drinking rhythms of the squirrel monkeys in continuous light and feedback lighting were comparable (25.6 +/- 0.1 and 25.9 +/- 0.1 hours, respectively), despite a substantial decrease in the total amount of light exposure associated with feedback lighting. The free-running period of monkeys exposed to continuous dark (24.5 +/- 0.1 hours) was significantly shorter than either of the two lighting conditions (P < 0.001). The results presented for the drinking rhythm were confirmed by examination of the temperature and activity rhythms. Therefore, discrete light pulses given predominately during the subjective night are capable of simulating the effects of continuous light on the free-running period of the circadian rhythms of a diurnal primate. The response of squirrel monkeys to feedback lighting thus lends further support for the model and suggests that the major entrainment mechanisms are similar in nocturnal rodents and diurnal primates.     

Localization and identification of nuclear radioactivity in the pituitary gland and genital tract after administering 3H-testosterone, 3H-dihydrotestosterone,or 3H-estradiol to male rhesus monkeys

Summary Target cells for testosterone, dihydrotestosterone, and estradiol in the pituitary gland and genital tract of the male primate were localized by thaw-mount autoradiography, and high performance liquid chromatography was used to identify the metabolites of these steroids in cell nuclei. Castrated rhesus monkeys were injected with ³H-testosterone, ³H-dihydrotestosterone, or ³H-estradiol and killed 60 min later. In the anterior pituitary gland, fewer cells were labeled and less radioactivity was taken up by cell nuclei following the administration of either ³H-testosterone (4% of pars distalis cells and 5 dpm/g DNA) or ³H-dihydrotestosterone (5% of cells and 13 dpm/g DNA) than following the administration of ³H-estradiol (43% of cells and 214 dpm/g DNA). Most of the radioactivity in nuclei was in the form of the unmetabolized parent compound (78–94%). In prostate, seminal vesicles, and penis, ³H-dihydrotestosterone was the predominant form of nuclear radioactivity following both ³H-testosterone (67–90%) and ³H-dihydrostestosterone (94–97%) administration, and both androgens labeled epithelial and smooth muscle cells. In contrast, ³H-estradiol was taken up in unchanged form, by cell nuclei of the genital tract and it labeled connective tissue fibroblasts, but not epithelial cells. Thus, the distributions of target cells for androgens and estrogens were clearly different in all these tissues, and the uptake of testosterone resembled that of its androgenic rather than that of its estrogenic metabolite.     

The genetic structure of a primate species: Rhesus macaques and other Cercopithecine monkeys

Among rhesus macaques (Macaca mulatta)and other cercopithecine monkeys, social groups occupying adjacent home ranges (i.e., members of the same local population) exchange individuals and genes and thus exhibit marked genetic similarities. To assess the degree to which this pattern extends beyond the local population, the genetic structure of M. mulattaand six other primate species was determined using Nei’s (1973) gene-diversity analysis. The genetic similarities seen among social groups in the Dunga Gali population of M. mulatta (Melnick et al.,1984a) can be seen over the entire species range. Comparison of these results with the structures of other similarly organized primate species indicates that (1) the average social group contains most of its local population’s genetic diversity, (2) the average local population contains the majority of the genetic diversity found in the region to which it belongs, and (3) the proportion of species gene diversity found in the average regional population varies substantially between species. Genetic homogeneity within local and regional populations is probably the product of gene flow. The application of a number of analytical models of selection and gene flow strongly suggests that gene flow, genetic drift, and zoogeography offer a more parsimonious and plausible explanation for interspecific variation in regional differentiation than does stabilizing selection.     

Social organization and ecology of proboscis monkeys (Nasalis larvatus) in mixed coastal forest in Sarawak

Data are presented from a 16-month study of proboscis monkeys in an area of mixed coastal forest in Sarawak. The population density, social organization, and feeding and ranging behavior are described in detail. Results are compared with those from other primates in an attempt to understand why females of certain species (including proboscis monkeys) transfer between social groups. The scarcity of available food and reasons for the limited habitat preferences of proboscis monkeys are also discussed.     

A case of diverticular disease of the colon in a Japanese monkey (Macaca fuscata)

Diverticular disease of the colon was detected in a female Japanese monkey by X-ray examination. The monkey was 15 years old and had been kept under captive conditions for nine years. Lack of appetite and activity, and constipation were observed. The monkey was given fiber-rich vegetables and wild plants, and its appetite and activity then improved. Based on a consideration of various factors, it is suggested that one possible cause of the diverticulosis in this case was a low dietary fiber intake.     

Group size and stability: Why do gibbons and spider monkeys differ?

Gibbons and spider monkeys have similar diets, body size, and locomotor patterns. They are therefore expected to be subject to similar socioecological rules. However their grouping patterns differ. Gibbons live in small stable groups, whereas spider monkey form unstable sub-groups that vary from small to large during different seasons. If similar principles apply to the two species, food abundance should vary more for spider monkeys than for gibbons; food density should be similar for the two species when spider monkey sub-groups are the same size as gibbon groups; and the highest level of food abundance should be higher for spider monkeys than for gibbons. These predictions are upheld for a comparison of particular populations ofHylobates muelleri andAteles geoffroyi.     

Rhesus monkey (Macaca mulatta) complex learning skills reassessed

Results from three experiments on basic learning and transfer in rhesus monkeys (Macaca mulatta) are reported in which fully automated testing paradigms, afforded by the Language Research Center's Computerized Test System (LRC-CTS), were employed. Performance levels for discrimination learning set, transfer index, and mediational-learning testing were uniformly higher than was predicted from the literature, in contrast to previous reports of compromised learning under similar conditions (automated apparatus, planimetric stimuli, spatial discontiguity between stimuli and response loci). Analyses reveal relatively advanced learning set performance, transfer-index ratios, and positive transfer of learning even at stringent criterion levels. Moreover, the data suggest that rhesus monkeys tested in these experiments exhibit mediational instead of associative learning strategies, as do great apes and in contrast to previous reports of rhesus learning. We argue that the LRC-CTS enhances learning by nonhuman primate subjects, obviating those factors, reported in the literature from experiments in which manual or other automated systems were employed, that compromise learning.     

促性腺激素诱导猕猴排卵周期中卵巢纤溶酶原激活因子与抑制因子的变化

在用 PMSG 和 hUG 诱导猕猴排卵过程中,我们研究了 pA 和它的抑制因子 PAI-1与排卵的关系。实验结果表明,由促性腺激素所诱导出的卵巢 tPA 活性的增加与排卵密切相关,在排卵前达到高峰,而排卵后明显下降;uPA 只在排卵后的颗粒细胞大量出现;PAI-1分泌高峰比 tPA 峰值早出现12—24小时;排卵来临时,tPA 的明显上升导致 PAl-1的空然下降。上述实验结果说明,卵巢中 tPA 和 PAI-1活性的这种平衡性的变化可能在排卵机制和维持卵巢的正常生理功能中起重要作用,而 uPA 或许与黄体形成的调节有某些关系。