Japanese Jungle Crows Research Articles

First molecular detection of Sarcocystis ovalis in the intestinal mucosa of a Japanese jungle crow (Corvus macrorhynchos) in Hokkaido, Japan.

Although cysts of Sarcocystis spp. have been detected in domestic and wild animals throughout Japan, their natural definitive hosts have not been fully elucidated. Additionally, in Hokkaido, several Sarcocystis spp. are highly prevalent among wild sika deer (Cervus nippon yesoensis), one of which is S. ovalis. The life cycle of S. ovalis is maintained in corvid birds. To identify the definitive host for S. ovalis in Hokkaido, we investigated its prevalence among corvid birds (Corvus macrorhynchos and C. corone). A total of 42 crow carcasses were collected during August 2015-July 2016 in southern Hokkaido. Examination for coccidian sporocysts in rectal feces and intestinal mucosa, detection of Sarcocystis DNA (18S rRNA gene) from intestinal mucosa samples, and histological observation of intestinal tissue were conducted. No Sarcocystis sporocysts were detected in fecal and mucosal samples by flotation. DNA from intestinal mucosa was positive in one crow (C. macrorhynchos). Phylogenetic analysis demonstrated the isolate clustered with S. ovalis and was closely related to isolates obtained from sika deer in Hokkaido. Histologically, S. ovalis gamogenesis (gamonts or gametes) and oocyst production were observed in the villi of the crow positive for S. ovalis DNA. However, the crow was negative for other coccidian parasites, such as Eimeria, by fecal examination. Our results suggested that crows harbor S. ovalis in the intestine and may serve as a definitive host of S. ovalis in Hokkaido. To our knowledge, this is the first report on a natural definitive host for Sarcocystis spp. prevalent among sika deer in Japan.

Seasonal cycle of leydig cells in the Japanese Jungle Crow (Corvus macrorhynchos)

The investigation was conducted to elucidate seasonal histomorphological changes of Leydig cells in Japanese Jungle crows (Corvus macrorhynchos). All adult crows (n=12) were killed for H&E staining. Histologic data of Leydig cells regarding their locations in the interstitium, appearance and disappearance of lipoidal materials in their cytoplasm, precursor cells and fibroblasts are studied. In the nonbreeding season, in the interstitium, clusters of Leydig cells were found in abundant number. They looked foamy, white and easily visible. Their nuclei were found small and are located eccentrically. During recrudescence, the Leydig cell became less foamy and less white. In peak breeding season, the Leydig cells showed bigger in size and the nuclei became prominent. Cytoplasmic lipoidal material was lowest and cytoplasm was found dense pink. At the end of breeding period, heavy accumulation of lipid materials occurred in the Leydig cell. The clusters of Leydig cells were visible and looked white and foamy again. During this transition, disintegration of Leydig cells occurred after pycnotic nuclei of Leydig cells were found. During involution, new generation of fibroblast like cells appeared in the interstitium. Within the fibroblast like cells, some of them became lipoidal by accumulating lipid materials. Thus a new generation of Leydig cells appeared in the interstitium. These lipoidal cells are thought to be a new generation of Leydig cells for the next breeding season. This study suggests that in seasonally breeding birds, new generation of Leydig cell is derived from fibroblast like cells of the interstitium.Asian J. Med. Biol. Res. June 2015, 1(1): 65-73

Perineuronal satellite neuroglia in the telencephalon of New Caledonian crows and other Passeriformes: evidence of satellite glial cells in the central nervous system of healthy birds?

Glia have been implicated in a variety of functions in the central nervous system, including the control of the neuronal extracellular space, synaptic plasticity and transmission, development and adult neurogenesis. Perineuronal glia forming groups around neurons are associated with both normal and pathological nervous tissue. Recent studies have linked reduction in the number of perineuronal oligodendrocytes in the prefrontal cortex with human schizophrenia and other psychiatric disorders. Therefore, perineuronal glia may play a decisive role in homeostasis and normal activity of the human nervous system.Here we report on the discovery of novel cell clusters in the telencephala of five healthy Passeriforme, one Psittaciform and one Charadriiforme bird species, which we refer to as Perineuronal Glial Clusters (PGCs). The aim of this study is to describe the structure and distribution of the PGCs in a number of avian species.PGCs were identified with the use of standard histological procedures. Heterochromatin masses visible inside the nuclei of these satellite glia suggest that they may correspond to oligodendrocytes. PGCs were found in the brains of nine New Caledonian crows, two Japanese jungle crows, two Australian magpies, two Indian mynah, three zebra finches (all Passeriformes), one Southern lapwing (Charadriiformes) and one monk parakeet (Psittaciformes). Microscopic survey of the brain tissue suggests that the largest PGCs are located in the hyperpallium densocellulare and mesopallium. No clusters were found in brain sections from one Gruiform (purple swamphen), one Strigiform (barn owl), one Trochiliform (green-backed firecrown), one Falconiform (chimango caracara), one Columbiform (pigeon) and one Galliform (chick).Our observations suggest that PGCs in Aves are brain region- and taxon-specific and that the presence of perineuronal glia in healthy human brains and the similar PGCs in avian gray matter is the result of convergent evolution. The discovery of PGCs in the zebra finch is of great importance because this species has the potential to become a robust animal model in which to study the function of neuron-glia interactions in healthy and diseased adult brains.

Apoptosis-mediated seasonal testicular regression in the Japanese Jungle crow (Corvus macrorhynchos)

The present study investigated effects of apoptosis observed during seasonal testicular regression in Japanese Jungle Crows. The study was conducted during January to June 2008, 2009. Testes from adults captured during non-breeding (January), prebreeding (February to mid-March), main-breeding (late March to early May), transition (mid-May to late May), and post-breeding (June) seasons were analyzed. Apoptosis was assessed by in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay. Paired-testis volume increased 95-fold from the non-breeding to the main-breeding season (P < 0.05), and subsequently decreased 26-fold from the main breeding to the post-breeding season (P < 0.05). Testicular activity was evaluated from the total germ cell count and sperm index, which increased 42- and 5-fold, respectively, in the main-breeding season, and subsequently decreased 33- and 5-fold in the post-breeding season. In testes, TUNEL-positive germ cells were at low levels in the non-breeding season, absent in the prebreeding and the main-breeding seasons, and highest in mid-May (P < 0.05). In contrast, TUNEL-positive Sertoli cells occurred only in late-April. In addition, TUNEL-positive fibroblast-like cells were observed in the outer zone of the tunica albuginea in the post-breeding season. Collectively, these data suggested that the seasonal rise in the testicular competence occurred slowly in Japanese Jungle Crows; however, testis function was terminated rapidly after the breeding season. Furthermore, we concluded, similar to other avian species, Sertoli cell apoptosis followed by massive germ cell death was responsible for rapid testicular regression in Jungle Crows.

Ultrastructural and Histochemical Properties of the Olfactory System in the Japanese Jungle Crow, Corvus macrorhynchos

Although it has been commonly believed that birds are more dependent on the vision and audition than the olfaction, recent studies indicate that the olfaction of birds is related to the reproductive, homing, and predatory behaviors. In an attempt to reveal the dependence on the olfactory system in crows, we examined the olfactory system of the Japanese jungle crow (Corvus macrorhynchos) by histological, ultrastructural, and lectin histochemical methods. The olfactory epithelium (OE) of the crow occupied remarkably a small area of the nasal cavity (NC) and had the histological and ultrastructural features like other birds. The olfactory bulb (OB) of the crow was remarkably small and did not possess the olfactory ventricle. The left and right halves of the OB were fused in many cases. In the lectin histochemistry, soybean agglutinin (SBA) and Vicia villosa agglutinin (VVA) stained a small number of the receptor cells (RCs) in the OE and the olfactory nerve layer (ONL) and glomerular layer (GL) on the dorsocaudal region of the OB. Phaseolus vulgaris agglutinin-E (PHA-E) stained several RCs in the OE and the ONL and GL on the ventral region of the OB. These results suggest that 1) the crow has less-developed olfactory system than other birds, and 2) the dedicated olfactory receptor cells project their axons to the specific regions of the OB in the crow.

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.

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.

Microstructure of the feather in Japanese Jungle Crows (Corvus macrorhynchos) with distinguishing gender differences

Assessing gender difference in Japanese Jungle Crows (Corvus macrorhynchos) is difficult by gross observation because both sexes have black plumage colors. Careful observation of the plumage, however, reveals that it is actually iridescent glossy purple and dark-green in color, and that these colors are more marked in adult males than in females. In birds, such iridescent structural colors are generally produced in the feather barbules, where light is scattered constructively by laminar arrays consisting of alternating layers of materials with different refractive indices, namely keratin, melanin and air. We have investigated differences in the microstructure of the feathers of male and female Jungle Crows by means of scanning and transmission electron microscopy. Male birds had more barbs than females, and the length of the prongs was shorter in males than in females. The density of the melanin granules in the cross-section of barbules was higher in males than in females. Moreover, only in males did the melanin granules show an ordered arrangement beneath a keratin cortex layer at the edges of barbules. These results demonstrate that there are microstructural differences in the feathers of male and female Jungle Crows and suggest that the Jungle Crows' feathers may have iridescent coloring that differs according to gender.

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.

Polymorphism of dopamine receptor D4 exon I corresponding region in chicken.

In stockbreeding, there are indications that behavioral traits of livestock have an effect on breeding and production. If the variation in individual behavior is related to that in neurotransmitter-related genes such as in humans, it would be possible to breed pedigrees composed of individuals having behavioral traits that are useful to production and breeding using selection based on genotypes. In this study, we investigated the exon I region of dopamine receptor D4 (DRD4), in which variation is related to psychiatric disorder in humans, in major poultry species namely Japanese quail (Coturnix japonica), chicken (Gallus gallus), ring-necked pheasant (Phasianus colchicus) and helmeted guinea fowl (Numida meleagris). Furthermore, we investigated Japanese cormorant (Phalacrocorax capillatus) and Japanese jungle crow (Corvus macrorhynchos) as an out-group. In these species of birds, the repeat of proline was identified in the region corresponding to the human polymorphic region. The repeat number was 9 in Japanese quail, ring-necked pheasant and Japanese cormorant; 12 in helmeted guinea fowl; and 3 in Japanese jungle crow. However, no polymorphism was found in these species. In contrast, polymorphism was observed in chicken and two alleles with 8 and 9 repeats were identified. Although 9 repeats (allele 9) were predominant in most chicken breeds, Black Minorca had only 8 repeats (allele 8). Intra-breed polymorphism was found in 6 out of 12 breeds, and two alleles (alleles 8 and 9) were detected in these breeds. This polymorphism, which is the first to be reported on a neurotransmitter-related gene in birds, would contribute significant information for elucidation of differences in behavioral traits in chicken breeds.

Near-field visual acuity in Japanese jungle crows ( Corvus macrorhynchos)

The near-field visual acuity of three Japanese jungle crows ( Corvus macrorhynchos) was determined by means of operant conditioning. The task was discrimination of grating stimuli, and the threshold was measured by up-and-down method between sessions. To keep observing distance constant, a photo sensor was used and the head position was behaviorally fixed. The average visual acuity was 8.4 cycles/degree. When compared with other birds, this result is better than that of pigeons, and worse than that of predators.

Genetic properties of conjugative R plasmids in Escherichia coli and Salmonella isolated from feral and domestic pigeons, crows and kites

A total of 62 conjugative R plasmids detected in 48 Escherichia coli and 19 conjugative R plasmids in 16 Salmonella strains from domestic (carrier and emerald) and feral pigeons, crows (Japanese jungle crows and carrion crows) and black kite, were examined for genetic properties. Out of the 62 E. coli R plasmids examined for fertility inhibition (Fi), 29 (46.8%) were Fi+, and the remainder were Fi-. Among the 62 R plasmids, 16 (25.8%) were classified into incompatibility (Inc) group FII, 15 (24.2%) into I alpha, 7 (11.3%) into H1 and 2 (3.2%) into N. The remaining 23 R plasmids could not be classified in this study. Among the 19 Salmonella R plasmids, 4 showed thermosensitive (ts) transfer. Out of the 18 plasmids tested, 13 (72.2%) including 4 ts-R plasmids were Fi-, and the remaining 5 (27.8%) were Fi+. Five R plasmids containing 4 Fi- were IncI alpha, while 4 ts-R plasmids belonged to IncH1 (1 R plasmid) and H2 (3 R plasmids). The remainings were not tested. In E. coli strains, IncFII and I alpha were widely (4 of 6 lots of birds, respectively) distributed, followed by N (2 lots) and H1 (1 lot). IncN R plasmid was detected from domestic pigeons and crows, but not from feral pigeons. In Salmonella strains from 5 lots of birds, IncFII and N plasmids which were detected from E. coli were not found, but IncH2 was detected from domestic pigeons (1 lot) and kite (1 lot). IncI alpha was detected from feral pigeons (1 lot) and kite (1 lot). The potential transfer of R plasmids between Salmonella and E. coli, and of dissemination of the plasmids among the free-flying birds, animals and humans is discussed.