Further evidence for the capacity of mirror self-recognition in cleaner fish and the significance of ecologically relevant marks.

An animal that tries to remove a mark from its body that is only visible when looking into a mirror displays the capacity for mirror self-recognition (MSR), which has been interpreted as evidence for self-awareness. Conservative interpretations of existing data conclude that convincing evidence for MSR is currently restricted to great apes. Here, we address proposed shortcomings of a previous study on MSR in the cleaner wrasse Labroides dimidiatus, by varying preexposure to mirrors and by marking individuals with different colors. We found that (1) 14/14 new individuals scraped their throat when a brown mark had been provisioned, but only in the presence of a mirror; (2) blue and green color marks did not elicit scraping; (3) intentionally injecting the mark deeper beneath the skin reliably elicited spontaneous scraping in the absence of a mirror; (4) mirror-naive individuals injected with a brown mark scraped their throat with lower probability and/or lower frequency compared to mirror-experienced individuals; (5) in contrast to the mirror images, seeing another fish with the same marking did not induce throat scraping; and (6) moving the mirror to another location did not elicit renewed aggression in mirror-experienced individuals. Taken together, these results increase our confidence that cleaner fish indeed pass the mark test, although only if it is presented in ecologically relevant contexts. Therefore, we reiterate the conclusion of the previous study that either self-awareness in animals or the validity of the mirror test needs to be revised.

Prosocial and antisocial choices in a monogamous cichlid with biparental care.

Human society is cooperative and characterized by spontaneous prosociality. Comparative studies on endotherm vertebrates suggest that social interdependence causes the evolution of proactive prosociality. To test the generality of this hypothesis, we modify a prosocial choice task for application to the convict cichlid, Amatitlania nigrofasciata, a monogamous fish with biparental care and a strong pair bond. We also affirm that male subjects learn to favor prosocial choices when their mates are the recipients in a neighboring tank. When the neighboring tank is empty, males choose randomly. Furthermore, in the absence of their mates, males behave prosocially toward a stranger female. However, if the mate of the subjects is also visible in the third tank, or if a male is a potential recipient, then subjects make antisocial choices. To conclude, fish may show both spontaneous prosocial and antisocial behaviors according to their social relationships with conspecifics and the overall social context.

Fish focus primarily on the faces of other fish.

"Face" is a special stimulus in humans and, nonhuman primates, and some other social mammals; that is, they perceive the face differently from the other body parts and other stimuli. In these species, the face conveys much information, so individuals examine the face at first sight rather than other body parts. Similar to mammals, the faces of fish also convey much information, but little is known about whether fish pay attention to the face or face-viewing patterns. Here we document the face-viewing patterns of the cichlid fish Neolamprologus brichardi, which can distinguish between conspecifics based on facial colouration. First, we established a method to identify the point at which subject fish inspected. Fish often fixated in direction to their heads toward the object of attention, suggesting that the extended body axis indicated the attention point. Using this attribute, we examined the point of attention of subject fish presented with photographs of conspecifics and heterospecifics. The results revealed that the fish inspected initially and repeatedly at the face and the duration was longer for the face than other body parts.

Do Scales of the Cichlid Altolamprologus compressiceps in Lake Tanganyika Function as a Morphological Defense Against Scale-Eating?

Many cichlid species in the shallow-shore of Lake Tanganyika suffer damage from attacks by the scale-eater Perissodus microlepis. Many prey fish engage in warning behaviors to this predator. It has been hypothesized that, if prey fish have difficulty employing such behavioral tactics, morphological defenses against scale-eating, such as hard scales, will evolve. The shrimp-eating cichlids, Altolamprologus compressiceps (Ac) and Neolamprologus fasciatus (Nf), exhibit hunting behaviors in which they remain motionless for up to 10 seconds while aiming at prey, when they are vulnerable to scale-eating predators; thus, these fish have likely evolved morphological defenses against "scale-attacks". We tested this hypothesis in Ac and Nf, as well as three other predatory fish, Lamprologus callipterus, Lepidiolamprologus elongatus and Lep. attenuatus, that are not motionless for such a long time. Under natural conditions, Ac and Nf were rarely attacked, while the other three species were attacked frequently. When freshly killed specimens of these five species were displayed underwater in the presence of P. microlepis, Ac was rarely attacked, while Nf and the three other species were attacked frequently. Among the five fish species, the force required to tear off scales was highest for Ac, and this force was negatively correlated with the frequency of attacks on the displayed fish. These results support the hypothesis that the hard scales of Ac function as an anti-scale-attack measure, although it remains unclear why free-swimming Nf were rarely attacked while aiming at prey, despite the fact that the force required to tear off its scales was not large.

Anomalous inferior mesenteric artery supplying the ascending, transverse, descending, and sigmoid colons.

We have encountered in our anatomical practice the first case and an extremely rare second case in which the ascending, transverse, descending, and sigmoid colons were supplied by the inferior mesenteric artery. The causes of colic artery anomalies are generally explained in conjunction with the development of the superior mesenteric artery, which is intimately related to embryonic elongation and midgut rotation. However, this embryological model was inapplicable to both cases. This difficulty motivated us to seek possible relationships with reported anomalous inferior mesenteric arteries in adults as well as their embryological causes. We consider that the aberrant right colic artery found in 2009 is an "intermesenteric artery" which anastomoses the superior (or its middle colic branch) and inferior mesenteric artery, but secondarily lost its origin from the superior mesenteric artery. The aberrant colic artery found in 2010 is a "middle-inferior mesenteric artery" in which the inferior mesenteric artery formed a common trunk with remnant middle mesenteric artery.

Facial Recognition in a Discus Fish (Cichlidae): Experimental Approach Using Digital Models.

A number of mammals and birds are known to be capable of visually discriminating between familiar and unfamiliar individuals, depending on facial patterns in some species. Many fish also visually recognize other conspecifics individually, and previous studies report that facial color patterns can be an initial signal for individual recognition. For example, a cichlid fish and a damselfish will use individual-specific color patterns that develop only in the facial area. However, it remains to be determined whether the facial area is an especially favorable site for visual signals in fish, and if so why? The monogamous discus fish, Symphysopdon aequifasciatus (Cichlidae), is capable of visually distinguishing its pair-partner from other conspecifics. Discus fish have individual-specific coloration patterns on entire body including the facial area, frontal head, trunk and vertical fins. If the facial area is an inherently important site for the visual cues, this species will use facial patterns for individual recognition, but otherwise they will use patterns on other body parts as well. We used modified digital models to examine whether discus fish use only facial coloration for individual recognition. Digital models of four different combinations of familiar and unfamiliar fish faces and bodies were displayed in frontal and lateral views. Focal fish frequently performed partner-specific displays towards partner-face models, and did aggressive displays towards models of non-partner's faces. We conclude that to identify individuals this fish does not depend on frontal color patterns but does on lateral facial color patterns, although they have unique color patterns on the other parts of body. We discuss the significance of facial coloration for individual recognition in fish compared with birds and mammals.

[An autopsied case of postinfectious neuromyelitis optica in an 84-year-old man].

An 84-year-old man presented with acute bilateral visual impairment 2 weeks after an upper respiratory tract infection. A few days later, he developed left hemiparesis, followed by paraplegia. The brain magnetic resonance imaging (MRI) showed high-intensity lesions in the right cerebellum, pons, left and right corona radiata, and right putamen. The diffusion weighted image also showed these high-intensity lesions. The spinal MRI showed an edematous, longitudinally extensive, cord lesion at the C5-Th6 level of the spine. Intravenous corticosteroid therapy was initiated, but the patient showed mild improvement. Although methylprednisolone pulse therapy was administered 5 times, he continued to present with clinical relapse and died on day 50. Anti-aquaporin-4 (AQP4) antibodies were detected in the patient's serum. Autopsy findings showed necrotic lesions at the spinal cord, brain, and optic chiasma and nerves. An immunohistopathological study showed the loss of AQP4- and glial fibrillary acidic protein (GFAP)-positive cells, with relatively preserved myelin basic protein (MBP)-positive myelin in the necrotic lesions. We diagnosed the patient as having neuromyelitis optica (NMO) because of the seropositivity for anti-AQP4 antibodies and on the basis of above-mentioned other immunohistochemical findings. It is difficult to distinguish NMO from ADEM clinically, when the patient has a preceding infection. NMO should be considered in patients with multifocal lesions in the central nervous system who have prominent myelitis and optic neuritis, irrespective of the postinfectious onset of the lesions and the sex and age of the patient.

Intravascular large B cell lymphoma diagnosed by senile angioma biopsy.

An 82-year-old man without notable medical history was admitted to our hospital following subacute deterioration of apettite, disorientation and strange behavior. There was spasticity of the right extremities without weakness. LDH and serum soluble IL2 receptor antibody levels were elevated, and as well as the protein level and IgG levels in the cerebrospinal fluid. CT scanning of the brain revealed a lesion at the left corona radiata. The patient's level of consciousness was worsening, and follow-up study of the brain showed a new lesion in the left occipital lobe. Intravascular lymphomatosis was therefore suspected. We performed a skin biopsy from two typical senile angiomas. In one of these biopsy specimens, a capillary hemangioma was present in the mid-reticular dermis and it was filled with abnormal B cells. The diagnosis of intravascular B cell lymphoma (IVL) was thus established. IVL is a rare subtype of extranodal diffuse large B cell lymphoma with a poor outcome. However, it is recently thought that if the diagnosis is established early, aggressive chemotherapy increases survival. Senile angioma is a skin eruption that is considered prevalent for the most part in elderly people. If a patient is suspected to have IVL, and there is no appropriate site of biopsy, it might be beneficial to try a skin biopsy aiming at senile angiomas for early diagnosis.