Cellular localization of thiol-proteinase inhibitor in the epidermis of the newborn rat

Summary In cichlid, poecilid and centrarchid fishes luteinizing hormone releasing hormone (LHRH)-immunoreactive neurons are found in a cell group (nucleus olfactoretinalis) located at the transition between the ventral telencephalon and olfactory bulb. Processes of these neurons project to the contralateral retina, traveling along the border between the internal plexiform and internal nuclear layer, and probably terminating on amacrine or bipolar cells. Horseradish peroxidase (HRP) injected into the eye or optic nerve is transported retrogradely in the optic nerve to the contralateral nucleus olfactoretinalis where neuronal perikarya are labeled. Labeled processes leave this nucleus in a rostral direction and terminate in the olfactory bulb. The nucleus olfactoretinalis is present only in fishes, such as cichlids, poecilids and centrarchids, in which the olfactory bulbs border directly the telencephalic hemispheres. In cyprinid, silurid and notopterid fishes, in which the olfactory bulbs lie beneath the olfactory epithelium and are connected to the telencephalon via olfactory stalks, the nucleus olfactoretinalis or a comparable arrangement of LHRH-immunoreactive neurons is lacking. After retrograde transport of HRP in the optic nerve of these fishes no labeling of neurons in the telencephalon occurred. It is proposed that the nucleus olfactoretinalis anatomically and functionally interconnects and integrates parts of the olfactory and optic systems.     

Differential Distribution of Gonadotropin-Releasing Hormone Variants in the Brain of Hydrochaeris hydrochaeris (Mammalia, Rodentia)

1.In a previous paper we reported evidence for the presence of mGnRH- and sGnRH-like peptides in the preoptic–hypothalamic region of the capybara Hydrochaeris hydrochaeris (Montaner et al., 1998). In that study, the presence of a cGnRH-II like molecule in olfactory bulb extracts was suggested.2.The capybara, the largest living rodent in the world, belongs to the order Hystricomorpha, which is considered to be one of the oldest groups of rodents. Some authors consider that this group is the ancestor of all remaining rodents.3.In this study we have characterized GnRH molecular variants found in extracts from the olfactory bulbs and the mesencephalic region of capybara. These regions represent the two GnRH neuronal systems: the terminal nerve–septopreoptic and the midbrain systems.4.An indirect method combining reverse-phase high-performance liquid chromatography (RP-HPLC) and radioimmunoassay (RIA) was used to characterize GnRH variants. The analysis of both extracts with two different RIA systems revealed three immunoreactive GnRH peaks, coeluting with mGnRH, cIIGnRH, and sGnRH synthetic standards. These results were additionally supported by serial dilution studies with specific antisera.5.To our knowledge this the first report on the presence of three GnRH variants in the brain of an eutherian mammal. These results suggest that, similarly to other vertebrates, the expression of multiple GnRH variants may also be a common pattern in mammals.     

Taste responses in primates to citric and acetic acid

By means of two-bottle preference tests, the threshold values in four South American primate species were evaluated for citric acid and compared with those for acetic acid. Aotus trivirgatusshows a special preference for both acid compounds. These physiological findings may reflect the ecology of Aotus.     

Brain weight-body weight relationships in 12 species of nonhuman primates

Necropsy data from a Primate Center were used in a study of the brain weight-body weight relationships of 12 species of nonhuman primates. The sample sizes ranged from six Cercopithecus aethiops to 163 Macaca mulatta. By plotting mean brain-mean body weight of each species on log-log paper, it was shown that the straight line fitting the plots of all species had a slope of 0.72. Slopes for three species of the genus Macaca, and for six species of the family Cebidae, were 0.61 and 0.81 respectively. Coefficients of determination of the three lines were greater than 0.90. Two species of the family Cebiade, Saimiri sciureus and Aotus trivirgatus, had equivalent body weights, but the former had a 30% larger brain than the latter. The results suggest that brain-body weight scaling characteristics of primate species can be studied effectively using necropsy data. Some statistically significant discrepancies between these and published data, however, show that more data are required to describe these characteristics with greater certainty.     

Mapping bone cell distributions to assess ontogenetic origin of primate midfacial form

Midfacial reduction in primates has been explained as a byproduct of other growth patterns, especially the convergent orbits. This is at once an evolutionary and developmental explanation for relatively short snouts in most modern primates. Here, we use histological sections of perinatal nonhuman primates (tamarin, tarsier, loris) to investigate how orbital morphology emerges during ontogeny in selected primates compared to another euarchontan (Tupaia glis). We annotated serial histological sections for location of osteoclasts or osteoblasts, and used these to create three‐dimensional “modeling maps” showing perinatal growth patterns of the facial skeleton. In addition, in one specimen we transferred annotations from histological sections to CT slices, to create a rotatable 3D volume that shows orbital modeling. Our findings suggest that growth in the competing orbital and neurocranial functional matrices differs among species, influencing modeling patterns. Distinctions among species are observed in the frontal bone, at a shared interface between the endocranial fossa and the orbit. The medial orbital wall is extensively resorptive in primates, whereas the medial orbit is generally depositional in Tupaia. As hypothesized, the orbital soft tissues encroach on available interorbital space. However, eye size cannot, by itself, explain the extent of reduction of the olfactory recess. In Loris, the posterior portion of medial orbit differed from the other primates. It showed evidence of outward drift where the olfactory bulb increased in cross‐sectional area. We suggest the olfactory bulbs are significant to orbit position in strepsirrhines, influencing an expanded interorbital breadth at early stages of development. Am J Phys Anthropol 154:424–435, 2014. © 2014 Wiley Periodicals, Inc.     

Cranial endocast of Anagale gobiensis (Anagalidae) and its implications for early brain evolution in Euarchontoglires

Anagalids are an extinct group of primitive mammals from the Asian Palaeogene thought to be possible basal members of Glires. Anagalid material is rare, with only a handful of crania known. Here we describe the first virtual endocast of an anagalid, based on the holotype of Anagale gobiensis (AMNH 26079; late Eocene, China), which allows for comparison with published endocasts from fossil members of modern euarchontogliran lineages (i.e. primates, rodents, lagomorphs). The endocast displays traits often observed in fossorial mammals, such as relatively small petrosal lobules and a low neocortical ratio, which would be consistent with previous inferences about use of subterranean food sources based on heavy dental wear. In fact, Anagale gobiensis has the lowest neocortical ratio yet recorded for a euarchontogliran. This species was olfaction-driven, based on the relatively large olfactory bulbs and laterally expansive palaeocortex. The endocast supports previous inferences that relatively large olfactory bulbs, partial midbrain exposure and low encephalization quotient are ancestral for Euarchontoglires, although the likely fossorial adaptations of Anagale gobiensis may also partly explain these traits. While Anagale gobiensis is a primitive mammal in many aspects, some of its derived endocranial traits point towards a new, different trajectory of brain evolution within Euarchontoglires.     

Immunocytochemical localization of luteinizing hormone-releasing hormone within the olfactory bulb of pigs

LHRH was immunocytochemically localized within the olfactory bulb of prepubertal (n = 3), ovariectomized (n = 3), and hypophyseal-stalk-transected (HST) female pigs (n = 3). Perikarya of LHRH-immunoreactive neurons of all pigs were sparsely distributed mostly in the rostral half of the olfactory bulb, along the ventromedial and ventrolateral edge of the olfactory nerve layer, or at its interace with the glomerular layer. Processes from these cells and other LHRH containing axons either entered individual glomeruli forming a network within its interior or coursed around glomeruli penetrating into the external granular layers. Additional fibers penetrated into similar regions of the accessory olfactory bulb. Irregularly shaped perikarya were also detected within the internal granular layer of the ventral olfactory bulb, but only in tissue from HST pigs. From analysis of serial sections, there was no evidence of LHRH projections across the olfactory peduncle that connects the olfactory bulb with adjacent brain regions. If olfactory LHRH neurons are involved in reproductive behavior and physiology in the pig, this pathway involves additional unidentified intervening neurons. Endocrine factors probably influence the expression of immunoreactive LHRH in the internal granule layer, since their presence was revealed only in HST pigs.     

Effects of unilateral olfactory deprivation in the developing opossum,Monodelphis domestica

Unilateral naris closure in young rodents leads to striking alterations in the development of the ipsilateral olfactory system. One of the most pronounced effects is a 25% reduction in the size of the experimental olfactory bulb, a change that stems in part from decreased cell survival. Since naris occlusion in rodents alters the system more during development than in adulthood, we investigated the consequences of olfactory deprivation in a species that is born in a very immature state, Monodelphis domestica. In this pouchless marsupial, offspring are born after a short 14-day gestation. In the present study, the thymidine analogue bromodeoxyuridine was used to examine early postnatal neurogenesis in the olfactory bulb. Unlike rats and mice, neurogenesis of the main output neurons (the mitral cells) continues into postnatal life. Unilateral naris closure was begun on postnatal day 4 (P4) or P5 in Monodelphis and continued for 30 or 60 days. Laminar volume measurements revealed a significant reduction in the size of the experimental bulb following 60, but not 30, days of early olfactory deprivation. Mitral cell number estimates indicated a significant reduction after both 30 and 60 days of naris closure. The immaturity of Monodelphis offspring may render the population of mitral cells susceptible to the effects of olfactory deprivation. These findings suggest that afferent activity plays a role in the survival of all bulb neurons, irrespective of cell class. © 1997 John Wiley & Sons, Inc. J Neurobiol 33: 429–438, 1997     

Positional cues that are strictly localized in the telencephalon induce preferential growth of mitral cell axons

In mice, mitral cells are the major efferent neurons of the main olfactory bulb and elongate axons into a very narrow part of the telencephalon to form a fiber bundle referred to as the lateral olfactory tract (LOT). To clarify the mechanisms responsible for guidance of mitral cell axons along this particular pathway, we co-cultured mouse embryo main olfactory bulbs with the telencephalons, and analyzed the pathways taken by mitral cell axons. Ingrowth of mitral cell axons into the telencephalon was observed in those co-cultures in which the olfactory bulbs had been exactly combined to their normal pathway (the LOT position) of the telencephalon. The axons grew preferentially along the LOT position, and formed a LOT-like fiber bundle. When the olfactory bulbs were grafted at positions apart from their normal pathway, however, no mitral cell axons grew into the telencephalon. Neocortical fragments combined with the telencephalon projected fibers into the telencephalon in random directions. These results suggest that the LOT position of the telencephalon offers a guiding pathway for mitral cell axons and that guiding cues for mitral cell axons are extremely localized. © 1996 John Wiley & Sons, Inc.     

Central connections of the olfactory bulb in the bichir,Polypterus palmas,reexamined

Summary Central connections of the olfactory bulb of Polypterus palmas were studied with the use of horseradish peroxidase and cobalt-tracing techniques. The olfactory bulb projects to subpallial and palliai areas in the ipsilateral telencephalon; a projection to the contralateral subpallium is noted via the habenular commissure. A further target of secondary olfactory fibers is a caudal olfactory projection area in the ipsilateral hypothalamus. No labeling was seen in the anterior commissure and in the contralateral olfactory bulb. The medial and the lateral pallium receive secondary olfactory fibers in distinct areas. Neurons projecting to the bulb are found in the ipsilateral subpallium, mainly in one dorsal longitudinal nucleus. The main connection with the tel- and diencephalon is mediated via the medial olfactory tract. This tract also contains fibers to the contralateral telencephalon, and to the hypothalamus. The smaller lateral olfactory tract mediates fibers to the lateral pallium. The organization of pathways of secondary olfactory fibers in the telencephalon is described. The present findings are compared to those obtained in species possessing an inverted forebrain.This investigation was supported by grants from the Deutsche Forschungsgemeinschaft to DLM     

Bulbil production in Narcissus: the effect of temperature and duration of storage on bulb unit development and subsequent propagation by twin-scaling

The growth of bulb components and carbohydrate content of Narcissus bulbs was followed during storage at 5–30 ^oC, and the productivity of twin-scale propagules cut from bulbs after these storage treatments was studied. Growth of daughter bulb unit components was greatest during storage at 9–15 ^oC, and greatly inhibited at 30 ^oC. Concentrations of soluble sugars were highest following 30 ^oC storage, and higher in intermediate bulb scales than in outer or inner scales. Bulbil production on twin-scales was greatest on propagules cut from the intermediate scales, and in bulbs previously stored at 15 or 30 ^oC.     

Environmental control of collateral branching and target invasion of mitral cell axons during development

During development, mitral cell axons, the major efferents of the olfactory bulb, exhibit a protracted waiting period in the lateral olfactory tract (LOT) before giving off collateral branches and innervating the target olfactory cortex. To investigate the target invasion mechanism, a series of heterochronic and heterotopic cocultures of olfactory bulbs with various olfactory cortical strips were conducted. These experiments indicated that development of collateral branches is triggered by environmental cues but not by intrinsic mechanisms in mitral cells. The collateral-inducing cues are apparently different from the cues directing outgrowth of primary mitral cell axons. Coculture experiments also indicated that the target olfactory cortex undergoes a developmental change to become accessible to mitral cell fibers. Primary mitral cell axons, however, still preferred the LOT position over such accessible piriform cortex when encountered both the locations. These results suggest that mitral cell projection comprises multiple steps which are controlled by various environmental cues.     

Developmental changes in cytochrome oxidase histochemistry in the main and accessory olfactory bulbs of embryonic and neonatal garter snakes (Thamnophis sirtalis spp.)

Developmental studies examining the changes in oxidative metabolic activity are useful for understanding how and if the vomeronasal and olfactory systems respond to stimulation during embryogenesis. Garter snakes are good candidates for examining the potential functionality of the vomeronasal system in utero. In adult garter snakes, the vomeronasal system mediates many behaviors. Neonatal garter snakes exhibit these same behaviors, and the vomeronasal system has been shown to mediate feeding behavior in neonates. Using cytochrome oxidase histochemistry, we examined changes in the oxidative metabolic activity of main and accessory olfactory bulbs of embryonic and neonatal garter snakes (Thamnophis sirtalis sirtalis and T. s. parietalis). Cytochrome oxidase staining is greater in the accessory olfactory bulb than in the main olfactory bulb of embryonic garter snakes. However, neonates show no differences in the staining of the accessory and main olfactory bulbs, suggesting a change in the stimulation of the main olfactory bulb after birth. This is the first report of cytochrome oxidase histochemistry in reptiles and in the vomeronasal system of embryonic vertebrates. © 1993 Wiley-Liss, Inc.     

Localized and discrete changes in neuropeptide (LHRH and TRH) and neurotransmitter (NE and DA) concentrations within the olfactory bulbs of male mice as a function of social interaction

Individually housed male mice were exposed to either an intact male or an ovariectomized female mouse for 1 min and decapitated at 5, 15, or 60 min to examine the hypothesis whether discrete changes in olfactory bulb neuropeptide (LHRH and TRH) and neurotransmitter (NE and DA) concentrations would occur following onset of exposure. A nonexposed control group (decapitated at time 0) was also included. Bilateral olfactory bulbs were dissected into anterior dorsal (ADOB) and posterior dorsal (PDOB) olfactory bulb fragments and prepared for radioimmunoassays (LHRH and TRH) or radioenzymatic assays (NE and DA). Concentrations of LHRH and NE, but not of TRH and DA, from the PDOB were significantly greater than those of ADOB fragments. Exposure to a male resulted in a significant increase of PDOB LHRH at 5 min following exposure and a significant increase in LHRH at 15 min following female exposure. Norepinephrine within the ADOB and PDOB and DA within the PDOB demonstrated a statistically significant increase at 60 min following exposure to an ovariectomized female. In marked contrast, no statistically significant changes were obtained following male exposure. These results not only demonstrate a preferential localization of neuroregulators within the olfactory bulb of male mice but discrete changes in the concentration of these neuroregulators in response to male or female exposure, suggesting the possibility that some processing and coding of chemical cue information during social encounters already occurs at the level of the olfactory bulb.     

The quantitative relationship between olfactory axons and mitral/tufted cells in developing Xenopus with partially deafferented olfactory bulbs

Partial deafferentation of the olfactory bulb in Xenopus embryos was performed to analyze the effects of afferent innervation on the development of the central olfactory structure. In an attempt to analyze a possible early inductive role of the olfactory axons, one olfactory placode was removed before differentiation of the neural tube began (stages 26–31). A morphological and quantitative analysis was performed on larvae at the onset of metamorphic climax (stage 58). When the single olfactory nerve innervated one side of the rostral telencephalon, a single olfactory bulb developed on that side and no olfactory bulb formed on the contralateral side. When the nerve innervated the midline of the rostral telencephalon, a smaller-than-normal, fused olfactory bulb developed. Partial deafferentation at these early stages resulted in a significant reduction in the number of olfactory axons (to approximately one-half of control values) and a corresponding decrease in the number of mitral/tufted cells (output neurons of the olfactory bulb). To control for possible damage to the neural tube during olfactory-placode removal, a portion of the neural tube directly beneath one of the olfactory placodes was removed in embryos. In these animals, the neural tube regenerated within 24 h and formed a normal olfactory bulb; olfactory axon and mitral/tufted-cell numbers were not significantly different from controls. In conclusion, olfactory-afferent innervation was critical for differentiation of the olfactory bulb, and decreasing the number of olfactory axons resulted in a reduction in the number of output neurons of the olfactory bulb. © 1993 John Wiley & Sons, Inc.     

A New Method for Intraerythrocytic Cultivation of Malaria Parasites (Plasmodium coatneyi and P. falciparum)

SYNOPSIS. Infected blood (from the rhesus monkey with P. coatneyi or an Aotus trivirgatus monkey with P. falciparum) was placed in a special vial equipped with an overflow tube 2–3 mm above the bottom of the vial. A slow flow (50 ml per day) of culture medium was maintained over the settled layer of red cells. In favorable experiments both species of parasites went thru 2 cycles of development without addition of fresh erythrocytes. so that late schizonts and young rings were present after 4 as well as after 2 days of incubation. There was, however, no increase in total parasite number.     

Use of spatial, visual, and olfactory information during foraging in wild nocturnal and diurnal anthropoids: A field experiment comparing Aotus, Callicebus, and Saguinus

Early in their evolution, the ancestors of anthropoid primates radiated from a nocturnal to a diurnal niche. Foraging during the night differs from foraging during the day in terms of the availability of light and color cues, and in the movement of odor molecules through the canopy. In this study, we compared the ability of nocturnal and diurnal New World monkeys to use perceptual cues (i.e., the sight or smell of food) and spatial information (place predictability) in within-patch foraging decisions. An experimental field study was conducted on wild groups of night monkeys (Aotus nigriceps), tamarins (Saguinus imperator imperator and S. fuscicollis weddelli), and titi monkeys (Callicebus cupreus) at the Zoobotanical Park/UFAC, Rio Branco, Brazil. Our research design included the construction of feeding stations located in the home range of the study groups. Each feeding station consisted of eight visually identical feeding platforms located in a circular arrangement. In all test settings, two platforms at each feeding station contained a food reward (banana), and the remaining six platforms contained a sham reward (yellow plastic or inaccessible banana). In the night-monkey experiments, each feeding platform was illuminated by a 40-W red bulb to aid the researcher in observing their behavior. When the location of reward sites was predictable over time, individuals in all four species successfully relocated food rewards based solely on spatial information. Each species was also successful in using visual information to distinguish real from sham food rewards. However, only night monkeys and one group of emperor tamarins used olfactory information alone to locate food rewards. Overall, the species' performances did not clearly differentiate Aotus from diurnal New World primates in these experiments.     

Distribution of salmon gonadotrophin releasing-hormone in the brain and pituitary of the sea bass (Dicentrarchus labrax)

Summary The distribution of salmon gonadotrophin-releasing hormone (sGnRH) was studied in the brain and pituitary of two-year-old immature sea bass (Dicentrarchus labrax) by means of an enzymoimmunoassay (EIA) for sGnRH and immunocytochemistry. The EIA for sGnRH is a competitive assay using a tracer made of sGnRH coupled to acetylcholinesterase from an electric eel. The separation of free and bound tracer is achieved by coating the plates with mouse anti-rabbit IgG monoclonal antibodies. Displacement curves generated by sGnRH and extracts from pituitary and different brain regions showed a good parallelism allowing the assay to be used for sGnRH measurements in this species. Although all parts of the brain contained measurable levels of sGnRH, the highest concentrations were found in the pituitary, the olfactory bulbs and the telencephalon. These data were confirmed by immunocytochemistry. Cell bodies were found in the olfactory bulbs, ventral telencephalon, preoptic region and mediobasal hypothalamus. Immunoreactive fibers could be observed in all parts of the brain including the optic tectum, the cerebellum (corpus and valvula), the vagal lobe, the medulla oblongata and the rostral spinal cord. In most cases, these fibers do not form well defined bundles; however, there was clearly a continuum of immunoreactive fibers, extending from the olfactory bulbs to the pituitary, and along which all the cell bodies described above were located. In the ventral telencephalon and the preoptic region, clear pictures of varicose positive fibers contacting immunoreactive perikarya could be observed. These data indicate that sGnRH is most likely an endogenous peptide in the brain of the sea bass, although the presence of other forms of GnRH cannot be excluded at this point. This study also demonstrates that the general organization of the GnRH systems in the sea bass is highly similar to what has been described in most freshwater teleost species, and provides basis for further studies on the neuroendocrine control of gonadotrophin release in this commercially important species.     

The Efferent Connections of the Olfactory Bulb and Accessory Olfactory Bulb in the Snakes,Thamnophis sirtalis and Thamnophis radix

The efferent connections of the olfactory bulb and accessory olfactory bulb of two species of garter snakes, Thamnophis sirtalis and T. radix were studied with experimental anterograde degeneration techniques. Axons of cells located in the olfactory bulb terminate ipsilaterally in all parts of the anterior olfactory nucleus, olfactory tubercle and lateral pallium. In addition, some axons enter the ipsilateral stria medullaris thalami, cross the midline in the habenular commissure, enter the contralateral stria medullaris thalami and terminate in the contralateral lateral pallium. The axons of cells in the accessory olfactory bulb course through the telencephalon completely separated from the fibers of olfactory bulb origin and terminate predominantly in the nucleus sphericus. These results confirm previous reports of the separation between the central projections of the olfactory and vomeronasal systems in a variety of vertebrates. The totality of the separation between these two systems coupled with the extensive development of the vomeronasal-accessory bulb system in these snakes suggests that they may be ideal subjects for further research on the functional significance of the vomeronasal system.