Shape discrimination and concept formation in the jungle crow (Corvus macrorhynchos).

We investigated whether jungle crows can learn concepts by using printouts of shapes in a simultaneous two-alternative task. Jungle crows were first trained with a red triangle and red square until they reached the discrimination criterion (80% of correct choices in two blocks of 10 trials each). Then, we tested crows with successive transfer tests to investigate both the discrimination cues being used and concept formation ability, by using novel triangular and non-triangular stimuli. All of the jungle crows learnt to discriminate between the triangle and square during training. The discrimination performance was generally not affected either by changes in the colour of the stimuli or when both shape and colour cues conflicted, with the previously non-rewarded shape but matching colour (red square) versus rewarded shape but non-matching colour (green triangle). The use of only outlines of the familiar stimuli also did not affect discrimination behaviour of crows. In addition, crows significantly discriminated novel triangular shapes during the limited trials given, suggesting their ability to form the concept of triangularity. However, failure to discriminate when the novel stimuli size deviated from the original suggests that there is a limit to shape concept formation in a familiar-novel context in the jungle crow.

Transportation-induced nausea-like behavior in goats and the effects of anti-motion sickness medication.

This study investigated the nausea-like behavior induced by road transportation in goats, and the effects of an anti-motion sickness (MS) medication on this behavior. In the first experiment, 11 adult Shiba goats were road transported twice with either a saline (control) or a commercial anti-MS medication (Travelmin) injection at the first or second transportation. Almost all goats showed nausea-like behavior, which was defined as pointing their heads downward, closing their eyes, and staying relatively still. These goats did not respond when they were touched during blood collection. The anti-MS medication significantly reduced the total time spent in nausea-like behavior (P < 0.05) and tended to increase the frequency of escape attempts during blood collection (P < 0.1). In a second experiment, the effects of the anti-MS medication were examined in goats held under normal housing. The anti-MS medication increased the time spent feeding (P < 0.01) and reduced the time spent in rumination (P < 0.05) but did not change the frequency of lying down nor plasma cortisol concentrations. Our results indicate that the nausea-like behavior in transported goats might be induced, at least in part, by regulatory mechanisms similar to the MS.

Radial polarity in the first cranial neuromast of selected teleost fishes.

The neuromast is a sensory structure of the lateral line system in aquatic vertebrates, which consists of hair cells and supporting cells. Hair cells are mechanosensory cells, generally arranged with bidirectional polarity. Here, we describe a neuromast with hair cells arranged radially instead of bidirectionally in the first cranial neuromast of four teleost species: red seabream (Pagrus major), spotted halibut (Verasper variegatus), brown sole (Pseudopleuronectes herzensteini), and marbled sole (Pseudopleuronectes yokohamae). In these four species, this polarity was identified only in the first cranial neuromast, where it appeared at the rostral edge of the otic vesicle before hatching. We investigated the initial appearance and fate of this unique neuromast using scanning electron microscopy. We also assessed characteristics of radial neuromast pertaining to morphogenesis, development, and innervation using a vital fluorescent marker and immunohistochemistry in V. variegatus. The kinocilium initially appears at the center of each hair cell, then moves to its outer perimeter to form radial polarity by around 7 days postfertilization. However, hair cells arranged radially disappear about 15 days after hatching. This is followed by the appearance of bidirectionally arranged hair cells, indicating that polarity replacement from radial to bidirectional has occurred. In P. herzensteini, both afferent and efferent synapses between the nerve fibers and hair cells were observed by transmission electron microscopy, suggesting that radial neuromast is functional. Our discovery suggests that neuromasts with radial polarity could enable larval fish to assimilate multiaxial stimuli during this life stage, potentially assisting them in detecting small water vibrations or water pressure changes.

Long-term memory of color stimuli in the jungle crow (Corvus macrorhynchos).

Wild-caught jungle crows (n = 20) were trained to discriminate between color stimuli in a two-alternative discrimination task. Next, crows were tested for long-term memory after 1-, 2-, 3-, 6-, and 10-month retention intervals. This preliminary study showed that jungle crows learn the task and reach a discrimination criterion (80% or more correct choices in two consecutive sessions of ten trials) in a few trials, and some even in a single session. Most, if not all, crows successfully remembered the constantly reinforced visual stimulus during training after all retention intervals. These results suggest that jungle crows have a high retention capacity for learned information, at least after a 10-month retention interval and make no or very few errors. This study is the first to show long-term memory capacity of color stimuli in corvids following a brief training that memory rather than rehearsal was apparent. Memory of visual color information is vital for exploitation of biological resources in crows. We suspect that jungle crows could remember the learned color discrimination task even after a much longer retention interval.

High levels of apolipoproteins found in the soluble fraction of avian cornea.

Water-soluble proteins in avian corneas were profiled by two-dimensional electrophoresis and identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Comparative protein profiling of avian and mammalian corneas revealed five major protein spots specifically detected in avian species. These proteins were identified as apolipoproteins A1 and D by tandem mass spectrometry sequencing. This is the first report of the presence of apolipoproteins in avian cornea. These results could provide insight into the role of lipid metabolism in the avian-specific function of cornea.

The effects of cisplatin, an emetic agent, on behavior and plasma cortisol levels in goats.

Ruminants are not considered to experience nausea because they do not possess the emetic reflex. This study examined the effects of administration of cisplatin (cis-diamminedichloro platinum (II): CDDP), a common emetic agent, on the behavior of goats. In Experiment 1, adult Shiba goats received intravenous (IV) administration of CDDP. CDDP-administered goats spent a shorter time feeding (P < 0.01), lied down earlier (P < 0.01), and spent a longer period lying down (P < 0.01) than the saline-administered control goats, and sometimes, they directed their face downward and close their eyes. These behavioral responses were followed by a significant (P < 0.01) increase in plasma cortisol (Cor) levels, which indicated that goats experienced stress. The dose dependency was found in the extent of the CDDP effects. In Experiment 2, the effects of pretreatment of ondansetron (Ond), an antiemetic agent, were examined. Pretreatment of Ond extended the latency of lying (P < 0.01), shortened the time spent lying (P < 0.05), and reduced the extent of the increase in plasma Cor levels (P < 0.01). These results suggested that CDDP administration generated some state of stress in goats via the similar physiological mechanisms as emesis-caused stress in emetic species.

Distribution of retinal cone photoreceptor oil droplets, and identification of associated carotenoids in crow (Corvus macrorhynchos).

The topography of cone oil droplets and their carotenoids were investigated in the retina of jungle crow (Corvus macrorhynchos). Fresh retina was sampled for the study of retinal cone oil droplets, and extracted retinal carotenoids were saponified using methods adapted from a recent study, then identified with reverse-phase high-performance liquid chromatography (HPLC). To assess the effects of saponification conditions on carotenoid recovery from crow retina, we varied base concentration and total time of saponification across a wide range of conditions, and again used HPLC to compare carotenoid concentrations. Based on colors, at least four types of oil droplets were recognized, i.e., red, orange, green, and translucent, across the retina. With an average of 91,202 /mm(2), density gradually declines in an eccentric manner from optic disc. In retina, the density and size of droplets are inversely related. In the peripheral zone, oil droplets were significantly larger than those of the central area. The proportion of orange oil droplets (33%) was higher in the central area, whereas green was predominant in other areas. Three types of carotenoid (astaxanthin, galloxanthin and lutein), together with one unknown carotenoid, were recovered from the crow retina; astaxanthin was the dominant carotenoid among them. The recovery of carotenoids was affected by saponification conditions. Astaxanthin was well recovered in weak alkali (0.06 M KOH), in contrast, xanthophyllic carotenoids were best recovered in strong alkali (0.6 M KOH) after 12 h of saponification at freeze temperature.

Feather microstructure of the black-billed magpie (Pica pica sericea) and jungle crow (Corvus macrorhynchos).

The jungle crow (Corvus macrorhynchos) distribution stretches from eastern Eurasia continent to southeastern Asia. The distribution of the black-billed magpie (Pica pica sericea) stretches from Korea and China to the Kyushu area in Japan. They are both in the Family, Corvidae, and have iridescent feather colors, but the iridescent feather color of the black-billed magpie is more remarkable than that of the jungle crow. We observed the feather microstructure of these birds using electron microscope. On the barbules surface, the barbules twist and prong between the jungle crow and black-billed magpie were not similar. In the barbules cross section, the black-billed magpie showed a complex structure of melanin granules, the jungle crow showed a simple structure of melanin granules.

Microstructure characteristics of the cornea in birds and mammals.

In this study, the microstructure of the cornea was compared among chickens (Gallus gallus), jungle crows (Corvus macrorhynchos), rats (Rattus norvegicus) and rabbits (Oryctolagus cuniculus). The density of keratocytes in the mammals was over 3 times that in the birds. The size of the keratocytes in the birds and rat were significantly lower than those in the rabbit. Using scanning and transmission electron microscopy, the bundles of collagen fibers in the birds were found to be well arranged, while those in the mammals were arranged randomly. The collagen lamellae of the birds were significantly thicker than those of the mammals, and the numbers of collagen lamellae in the birds were significantly smaller than in the mammals. The center-to-center distances between the collagen fibrils of the chicken and rabbit were significantly larger than those of the crow and rat. The densities of collagen fibrils in the chicken and rabbit were significantly less than those of the crow and rat.

Light and electron microscopy study of the pecten oculi of the jungle crow (Corvus macrorhynchos).

In this study, the pecten oculi of a diurnally active bird, the Japanese jungle crow (Corvus macrorhynchos), was examined using light and electron microscopy. In this species, the pecten consisted of 24-25 highly vascularized pleats held together apically by a heavily pigmented 'bridge' and projected freely into the vitreous body in the ventral part of the eye cup. Ascending and descending blood vessels of varying caliber, together with a profuse network of capillaries, essentially constituted the vascular framework of the pecten. A distinct distribution of melanosomes was discernible on the pecten, the concentration being highest at its apical end, moderate at the crest of the pleats and lowest at the basal and lateral margins. Overlying and within the vascular network, a close association between blood vessels and melanocytes was evident. It is conjectured that such an association may have evolved to augment the structural reinforcement of this nutritive organ in order to keep it firmly erectile within the gel-like vitreous. Such erectility may be an essential prerequisite for its optimal functioning as well as in its overt use as a protective shield against the effects of ultraviolet light, which otherwise might lead to damage of the pectineal vessels.

Bilateral innervation of syringeal muscles by the hypoglossal nucleus in the jungle crow (Corvus macrorhynchos).

Bird vocalizations are produced by contractions of syringeal muscles, which are controlled by the hypoglossal nucleus. In oscines, syringeal muscles are controlled by the hypoglossal nucleus ipsilaterally, whereas syringeal innervation is bilateral in non-oscines. We have determined the course of hypoglossal nerves in the jungle crow Corvus macrorhynchos. Our results indicate a cross-over of the hypoglossal nerve from the left side to the right side on the trachea 7 mm rostral to the Musculus sternotrachealis. We also investigated the innervation of the syringeal muscles of jungle crows from the hypoglossal nucleus using the horseradish peroxidase (HRP) method. After HRP was injected into the syringeal muscles on each side, HRP-labeled cells were found bilaterally in the hypoglossal nerve. These results suggest that the syringeal muscles of jungle crows are innervated bilaterally from the hypoglossal nucleus, although these birds are categorized as oscines.

Histological properties of the nasal cavity and olfactory bulb of the Japanese jungle crow Corvus macrorhynchos.

The nasal cavity and olfactory bulb (OB) of the Japanese jungle crow (Corvus macrorhynchos) were studied using computed tomography (CT) and histochemical staining. The nasal septum divided the nasal cavity in half. The anterior and maxillary conchae were present on both sides of the nasal cavity, but the posterior concha was indistinct. A small OB was present on the ventral surface of the periphery of the cerebrum. The OB-brain ratio--the ratio of the size of the OB to that of the cerebral hemisphere--was 6.13. The olfactory nerve bundles projected independently to the OB, which appeared fused on gross examination. Histochemical analysis confirmed the fusion of all OB layers. Using a neural tracer, we found that the olfactory nerve bundles independently projected to the olfactory nerve layer (ONL) and glomerular layer (GL) of the left and right halves of the fused OB. Only 4 of 21 lectins bound to the ONL and GL. Thus, compared with mammals and other birds, the jungle crow may have a poorly developed olfactory system and an inferior sense of olfaction. However, it has been contended recently that the olfactory abilities of birds cannot be judged from anatomical findings alone. Our results indicate that the olfactory system of the jungle crow is an interesting research model to evaluate the development and functions of vertebrate olfactory systems.

Morphological and histochemical study of the nasal cavity and fused olfactory bulb of the brown-eared bulbul, Hysipetes amaurotis.

The brown-eared bulbul (Hysipetes amaurotis) is commonly found in Japan where it is regarded as a harmful bird that causes damage to agricultural products. Few studies have investigated the sensory apparatus of this bird, and consequently little is known of the sensory modalities it uses. Here we analyzed the anatomical and histological properties of the nasal cavity and olfactory bulb (OB) of the bulbul in order to investigate the functional level of olfaction in this species. Although both anterior and maxillary conchae were observed in the bulbul nasal cavity, there was no structure equivalent to the posterior concha. The OB located on the ventral side of the anterior extremity of the cerebrum and the ratio of olfactory bulb size to that of the cerebral hemisphere were very small. Interestingly, the left and right OBs were completely fused at the midline of the cerebrum. Furthermore, certain types of lectins that bind to the olfactory nerve of vertebrates with a well-developed sense of smell also bound positively to the olfactory nerve and glomerular layers of the bulbul OB. These findings suggest that the brown-eared bulbul has an anatomically and functionally less well developed sense of smell compared to other avian species. Although the molecular and developmental mechanisms underlying the fusion of the OB remain unknown, we suggest that the fused OB may offer a unique model for studying the evolution and development of the central olfactory nervous system in vertebrates.

Distribution of the androgen receptor in the diencephalon and the pituitary gland in goats: Co-localisation with corticotrophin releasing hormone, arginine vasopressin and corticotrophs.

Previously it has been shown that androgen suppresses transportation-induced increases in plasma adrenocorticotropic hormone (ACTH), possibly by suppressing the secretion of corticotrophin releasing hormone (CRH) or arginine vasopressin (AVP) from the hypothalamus, or secretion of ACTH from the pituitary gland. The aim of the present study was to examine androgen target sites in the caprine diencephalon and pituitary gland using immunohistochemical methods. The androgen receptor (AR) was expressed strongly in the bed nucleus of the stria terminalis, the medial preoptic area, the arcuate nucleus, the ventromedial hypothalamic nucleus and the suprachiasmatic nucleus in the diencephalon. Between 8% and 11% of CRH and AVP neurons in the paraventricular hypothalamic nucleus (PVN) expressed AR. In the pituitary gland, 7.1% of corticotrophs expressed AR. The results are consistent with the proposal that androgen acts directly and indirectly on CRH and/or AVP neurons in the PVN. The possibility of a direct action of androgen on the corticotrophs in the pituitary gland was also considered.

Melanin-based iridescent feather color in the Jungle Crow.

Sexual differences in Japanese Jungle Crows (Corvus macrorhynchos) are not obvious because both sexes have black plumage. However, closer examination reveals that their plumage color is not only black; it is also iridescent color. Furthermore, the iridescence is more pronounced in adult males than that in females. The iridescence seems to be related to the density and concentration of melanin granules. The density of melanin granule and the concentration of eumelanin in feathers were significantly higher in males than that in females (P<0.01). However, the amount of pheomelanin was below the detection limits in this study.

Androgen suppresses corticotropin-induced increase in plasma cortisol level but enhances the increase in plasma aldosterone level in goats.

Previously we reported that androgen treatment reduced the extent of the increase in plasma cortisol (Cor) levels induced by adrenocorticotropic hormone (ACTH) administration in goats. In this study, we investigated the effect of androgen on the plasma levels of androstenedione and aldosterone. Four castrated male goats, which were treated with either 5alpha-dihydrotestosterone (DHT) or cholesterol (cho), were injected intravenously with 0.005, 0.02 or 0.1 mg of ACTH(1-24). Plasma Cor levels were increased significantly by all doses of ACTH injection, and these extents were lower in DHT-treated goats. Plasma androstenedione levels were also increased by ACTH injection, but DHT treatment seemed to little affect. Plasma aldosterone levels were also increased by ACTH injection, and there were no differences between cho- and DHT treated goats at 15 and 30 min after the ACTH injection. However, when goats were given the lower doses of ACTH (0.02 and 0.005 mg), plasma aldosterone levels were restored rapidly only in cho-treated goats, whereas those in DHT-treated goats were maintained throughout the 60 min experimental period. Consequently, plasma aldosterone levels in DHT-treated goats were higher than those in cho-treated goats at 45 and 60 min. One possible mechanism of the effect of DHT on the ACTH-induced increase in aldosterone synthesis may be the reduction of the activity of P450-17alpha, that is the enzyme to convert pregnenolone to 17alpha-OH-pregnenolone, and this mechanism may also be responsible to the suppressive effect of DHT on the ACTH-induced Cor synthesis.

Innervation of wing membrane in Japanese little horseshoe bats, Rhinolophus cornutus.

The spinal nerves supplying the wing membranes of Japanese little horseshoe bats, Rhinolophus cornutus were studied. The wing membrane was innervated by nerve branches of the radial, ulnar, and median nerves, showing that the membrane was formed from the skin of the forelimb rather than that of the thoracolumbar skin. The radial nerve was mainly composed of the ventral rami of C7-T1, the ulnar nerve by C8-T2, and the median nerve by C8-T1. These components of R. cornutus tended to be from a narrower range of spinal nerves and to position more caudally than those of humans. In addition, the ulnar nerve showed a distribution pattern different from that of other mammals.

Structure of the syringeal muscles in jungle crow (Corvus macrorhynchos).

Birds' vocalizations are produced by the syrinx, which is located between the trachea and the two primary bronchi. Oscine birds have multiple pairs of syringeal muscles in the syrinx. To determine the detailed structure of the syringeal muscle in jungle crows, an oscine bird, a histological study and gross examination of the syrinx were performed. In the histological study, sections of the syrinxes from four jungle crows were stained with Azan and observed. Each syringeal muscle was classified by the limit of the fascia from neighbor fascicules. From the gross examination a 3-D image of the structure of the syringeal muscles was generated. The combined histological and anatomical results show that there are seven pairs of syringeal muscles in jungle crows. Muscle fusions were observed in some of the syringeal muscles. It is likely that each syringeal muscle has a specific role. Jungle crows may be able to generate various calls because they have several pairs of syringeal muscles.

Ganglion cell density and oil droplet distribution in the retina of brown-eared bulbul (Hypsipetes amaurotis) [corrected].

This study was intended to determine the number and density of both retinal ganglion cells and the oil droplets of cone photoreceptor cells in brown-eared bulbul (Hypsipetes amaurotis). For this study birds were killed with proper dose of anesthetic (pentobarbital, 30 mg/kg), and the eyes were removed from the orbital cavity to isolate the retina. For the ganglion cell study retinal whole-mount specimens were prepared and stained with 0.1% cresyl violet. The different types of oil droplets were counted from color microphotographs of freshly prepared retinal samples. The mean total number of ganglion cells was estimated at approximately 2.5 x 10(6); with an average density of 16 523 cells/mm(2). Two high-density areas, namely the central area (CA) and the dorso-temporal area (DTA), are located in the central and dorso-temporal retinas, respectively, in bulbuls (24 032 cells/mm(2) in the CA; 23 113 cells/mm(2) in the DTA). Small ganglion cells persisted in the highest density areas, whereas the largest soma sizes were found in the lowest density areas of the retina. Four types of different colored oil droplets - red, orange, green and clear - were identified with an average density of 29 062/mm(2). Among the different colors, the green oil droplets had a significantly higher population (13 083/mm(2)) than the others across the retina. The central retina had a significantly higher number of all types of oil droplets, at a density of 60 552/mm(2). The density and size of the different colored oil droplets were inversely related across the regions of the retina. Taken together, it is concluded that the CA of the retina is an excellent quality area for visual perception due to peak density of ganglion cells and oil droplets. Moreover, each specific oil droplet makes a distinct contribution to visual perception, thereby ensuring that the bird has a retina that best matches its natural environment and feeding behavior.

Physiological and behavioural effects of an intracerebroventricular injection of corticotropin releasing hormone in goats.

This study investigated the effects of an intracerebroventricular (ICV) injection of corticotropin releasing hormone (CRH) on physiological and behavioural responses in goats. In Experiment 1, saline (control) or saline plus 25 microg of ovine CRH was injected into the third ventricle of castrated male goats. CRH increased plasma cortisol (Cor) levels markedly within 15 min, but had little effect on plasma glucose (Glu). Compared with saline injected goats, CRH decreased the total duration of lying behaviour but increased its frequency, and suppressed rumination and self-grooming. In Experiment 2, the effects of an intravenous (IV) injection of human adrenocorticotropic hormone (ACTH) (1-24) (0.1mg) were examined and an IV injection of saline was used as control. ACTH increased plasma Cor levels markedly, but did not change any behaviour compared with controls. It was concluded that CRH mediated the response of the hypothalamus-pituitary-adrenal (HPA) axis and behaviour following stress in goats, although the CRH-induced behavioural changes were independent of the HPA axis and seemed to be the result of direct action within the central nervous system.