Ocular diagnostics, ophthalmic findings, and conjunctival microbiome in the Chilean flamingo (Phoenicopterus chilensis).

OBJECTIVE: To establish normative data for selected ocular diagnostic tests and commensal conjunctival microflora and describe the incidence of ocular pathology in Chilean flamingos. ANIMALS STUDIED: A total of 41 Chilean flamingos were examined at the Blank Park Zoo in Des Moines, Iowa. PROCEDURES: In 20 flamingos, blink rate was assessed undisturbed in their exhibit, then gentle manual restraint was used to assess palpebral fissure length (PFL), aqueous tear production (phenol red thread test [PRTT] in one eye, endodontic absorbent paper point tear test [EAPPTT] in the other), intraocular pressure (IOP; rebound tonometry), and fluorescein staining. Twenty-one other flamingos were brought to a darkened area for neuro-ophthalmic examination, slit lamp biomicroscopy, and indirect ophthalmoscopy. Swabs from seven flamingos were used for ocular microbiome evaluation. RESULTS: Results are presented as mean ± standard deviation (range). Flamingos comprised 23 females/18 males, aged 11 ± 9.1 (0.7-40) years. Test results: blink rate, 3.7 ± 2 (1-9) blinks/min; PFL, 11.2 ± 1.2 (9-14) mm; IOP, 14 ± 3.2 (10-22) mmHg; EAPPT, 10.2 ± 2.8 (9-14) mm/min; PRTT, 6.8 ± 2.5 (3-13) mm/15 s. Dazzle reflex was positive in four birds examined. Pathologies included cataracts (n = 7 birds), corneal fibrosis (n = 3), endothelial pigment (n = 2), uveal cysts (n = 1), lens luxation (n = 1), and uveitis (n = 1). Ocular microbiome showed high diversity of taxa. CONCLUSIONS: Baseline ocular parameters and incidence of ophthalmic pathology assist veterinarians with disease screening for Chilean flamingos, while the ocular microbiome showed high diversity.

Impact of age on the circadian visual system and the sleep-wake cycle in mus musculus.

Age plays a critical role in disease development and tolerance to cancer treatment, often leading to an increased risk of developing negative symptoms including sleep disturbances. Circadian rhythms and sleep become disrupted as organisms age. In this study, we explored the behavioral alterations in sleep, circadian rhythms, and masking using a novel video system and interrogate the long-term impact of age-based changes in the non-image forming visual pathway on brain anatomy. We demonstrated the feasibility and utility of the novel system and establish that older mice have disruptions in sleep, circadian rhythms, and masking behaviors that were associated with major negative volume alterations in the non-imaging forming visual system, critical for the induction and rhythmic expression of sleep. These results provide important insights into a mechanism, showing brain atrophy is linked to age in distinct non-image forming visual regions, which may predispose older individuals to developing circadian and sleep dysfunction when further challenged by disease or treatment.

IDENTIFICATION AND CORRELATION OF A NOVEL SIADENOVIRUS IN A FLOCK OF BUDGERIGARS (MELOPSITTACUS UNDULATES) INFECTED WITH SALMONELLA TYPHIMURIUM IN THE UNITED STATES.

A flock of budgerigars (Melopsittacus undulates) was purchased from a licensed breeder and quarantined at a zoologic facility within the United States in 2016. Following 82 deaths within the flock, the remaining 66 birds were depopulated because of ongoing clinical salmonellosis despite treatment. Gross necropsy was performed on all 66 birds. Histopathologic examination was performed on 10 birds identified with gross lesions and 10 birds without. Pathologic findings were most often observed in the liver, kidney, and spleen. Lesions noted in the livers and spleens were consistent with published reports of salmonellosis in psittacine species. Multisystemic changes associated with septicemia were not noted, most likely because of antibiotic intervention before euthanasia. Of the 20 budgerigars evaluated by histopathology, six had large basophilic intranuclear inclusion bodies within tubular epithelia in a portion of the kidneys. Electronic microscopy, next-generation sequencing, Sanger sequencing, and phylogenetic analyses were used to identify and categorize the identified virus as a novel siadenovirus strain BuAdV-1 USA-IA43444-2016. The strain was 99% similar to budgerigar adenovirus 1 (BuAdV-1), previously reported in Japan, and to a psittacine adenovirus 5 recently identified in a U.S. cockatiel. Salmonella typhimurium carriers were identified via polymerase chain reaction (PCR) and bacterial culture and compared with viral carriers identified via PCR. Inclusion bodies and Salmonella detection were significant in birds with gross lesions versus those without; however, there was no correlation between budgerigars positive with siadenovirus by PCR and concurrent Salmonella infection. Identifying subclinical siadenovirus strain BuAdV-1 USA-IA43444-2016 infection in this flock significantly differs from a previous report of clinical illness in five budgerigars resulting in death caused by BuAdV-1 in Japan. S. typhimurium remains a significant pathogen in budgerigars, and zoonotic concerns prompted depopulation to mitigate the public health risks of this flock.

Functional and anatomical variations in retinorecipient brain areas in Arvicanthis niloticus and Rattus norvegicus: implications for the circadian and masking systems.

Daily rhythms in light exposure influence the expression of behavior by entraining circadian rhythms and through its acute effects on behavior (i.e., masking). Importantly, these effects of light are dependent on the temporal niche of the organism; for diurnal organisms, light increases activity, whereas for nocturnal organisms, the opposite is true. Here we examined the functional and morphological differences between diurnal and nocturnal rodents in retinorecipient brain regions using Nile grass rats (Arvicanthis niloticus) and Sprague-Dawley (SD) rats (Rattus norvegicus), respectively. We established the presence of circadian rhythmicity in cFOS activation in retinorecipient brain regions in nocturnal and diurnal rodents housed in constant dark conditions to highlight different patterns between the temporal niches. We then assessed masking effects by comparing cFOS activation in constant darkness (DD) to that in a 12:12 light/dark (LD) cycle, confirming light responsiveness of these regions during times when masking occurs in nature. The intergeniculate leaflet (IGL) and olivary pretectal nucleus (OPN) exhibited significant variation among time points in DD of both species, but their expression profiles were not identical, as SD rats had very low expression levels for most timepoints. Light presentation in LD conditions induced clear rhythms in the IGL of SD rats but eliminated them in grass rats. Additionally, grass rats were the only species to demonstrate daily rhythms in LD for the habenula and showed a strong response to light in the superior colliculus. Structurally, we also analyzed the volumes of the visual brain regions using anatomical MRI, and we observed a significant increase in the relative size of several visual regions within diurnal grass rats, including the lateral geniculate nucleus, superior colliculus, and optic tract. Altogether, our results suggest that diurnal grass rats devote greater proportions of brain volume to visual regions than nocturnal rodents, and cFOS activation in these brain regions is dependent on temporal niche and lighting conditions.

LESIONS OF THE FEMALE REPRODUCTIVE TRACT IN JAPANESE MACAQUE ( MACACA FUSCATA) FROM TWO CAPTIVE COLONIES.

Reproductive lesions have been described in various nonhuman primate species, including rhesus macaques ( Macaca mulatta), cynomolgus macaques ( Macaca fascicularis), baboons ( Papio spp.), squirrel monkeys ( Saimiri sciureus), and chimpanzees ( Pan spp.); however, there are few publications describing reproductive disease and pathology in Japanese macaques ( Macaca fuscata). A retrospective evaluation of postmortem reports for two captive M. fuscata populations housed within zoos from 1982 through 2015 was completed, comparing reproductive diseases diagnosed by gross pathology and histopathology. Disease prevalence, organs affected, and median age at death between the two institutions was also compared. Fifteen female captive M. fuscata, ranging in age from 15 to 29 yr were identified with reproductive tract lesions, including endometriosis, endometritis, leiomyoma, leiomyosarcoma, and adenomyosis. No significant differences were identified in disease prevalence, organs affected, and median age of death between the two institutions. Endometriosis was the most common disease process identified and was found in 10 of the 15 cases (66.7%), followed by leiomyoma (4 of 15; 26.7%). In four cases (26.7%), severe endometriosis and secondary hemorrhage was indicated as the cause of death or the primary reason for humane euthanasia. These findings were compared with a separate population of Japanese macaques managed within a research facility in the United States, with a prevalence of endometriosis of 7.6%. This study discusses possible risk factors and potential treatment options for the management of endometriosis in captive M. fuscata.

Normal behavioral responses to light and darkness and the pupillary light reflex are dependent upon the olivary pretectal nucleus in the diurnal Nile grass rat.

The olivary pretectal nucleus (OPT) is a midbrain structure that receives reciprocal bilateral retinal projections, is involved in the pupillary light reflex, and connects reciprocally with the intergeniculate leaflet (IGL), a retinorecipient brain region that mediates behavioral responses to light pulses (i.e., masking) in diurnal Nile grass rats. Here, we lesioned the OPT and evaluated behavioral responses in grass rats to various lighting conditions, as well as their anxiety-like responses to light exposure. While control grass rats remained diurnal, grass rats with OPT lesions exhibited a more night-active pattern under 12h:12h light-dark (LD) conditions. However, when placed in constant darkness, OPT-lesioned grass rats became more active during their subjective day, suggesting that an exaggerated masking response to light may be responsible for the effect of OPT lesions on locomotor activity in LD. To test this hypothesis, we presented dark and light pulses to controls and grass rats with OPT lesions; controls increased their activity in response to light, whereas those with OPT lesions significantly increased activity in response to darkness. Further, when placed in a 7-h ultradian LD cycle, animals with OPT lesions were more active during darkness than controls. OPT lesions also abolished the pupillary light reflex, but did not affect anxiety-like behaviors. Finally, in animals with OPT lesions, light did not induce Fos expression in the ventrolateral geniculate nucleus, as it did in controls. Altogether, these results suggest that masking responses to light and darkness are dependent upon nuclei within the subcortical visual shell in grass rats.

The contribution of the pineal gland on daily rhythms and masking in diurnal grass rats, Arvicanthis niloticus.

Melatonin is a hormone rhythmically secreted at night by the pineal gland in vertebrates. In diurnal mammals, melatonin is present during the inactive phase of the rest/activity cycle, and in primates it directly facilitates sleep and decreases body temperature. However, the role of the pineal gland for the promotion of sleep at night has not yet been studied in non-primate diurnal mammalian species. Here, the authors directly examined the hypothesis that the pineal gland contributes to diurnality in Nile grass rats by decreasing activity and increasing sleep at night, and that this could occur via effects on circadian mechanisms or masking, or both. Removing the pineal gland had no effect on the hourly distribution of activity across a 12:12 light-dark (LD) cycle or on the patterns of sleep-like behavior at night. Masking effects of light at night on activity were also not significantly different in pinealectomized and control grass rats, as 1h pulses of light stimulated increases in activity of sham and pinealectomized animals to a similar extent. In addition, the circadian regulation of activity was unaffected by the surgical condition of the animals. Our results suggest that the pineal gland does not contribute to diurnality in the grass rat, thus highlighting the complexity of temporal niche transitions. The current data raise interesting questions about how and why genetic and neural mechanisms linking melatonin to sleep regulatory systems might vary among mammals that reached a diurnal niche via parallel and independent pathways.

Suprachiasmatic Nucleus and Subparaventricular Zone Lesions Disrupt Circadian Rhythmicity but Not Light-Induced Masking Behavior in Nile Grass Rats.

The ventral subparaventricular zone (vSPVZ) receives direct retinal input and influences the daily patterning of activity in rodents, making it a likely candidate for the mediation of acute behavioral responses to light (i.e., masking). We performed chemical lesions aimed at the vSPVZ of diurnal grass rats (Arvicanthis niloticus) using N-methyl-D,L-aspartic acid (NMA), a glutamate agonist. Following NMA lesions, we placed grass rats in various lighting conditions (e.g., 12:12 light-dark, constant dark, constant light); presented a series of light pulses at circadian times (CT) 6, 14, 18, and 22; and placed them in a 7-h ultradian cycle to assess behavioral masking. Extensive bilateral lesions of the vSPVZ disrupted the expression of circadian rhythms of activity and abolished the circadian modulation of masking responses to light, without affecting light-induced masking behavior per se. We also found that in diurnal grass rats, NMA was capable of destroying not only neurons of the vSPVZ but also those of the suprachiasmatic nucleus (SCN), even though excitotoxins have been ineffective at destroying cells within the SCN of nocturnal rodents. The vulnerability of the grass rat's SCN to NMA toxicity raises the possibility of a difference in density of receptors for glutamate between nocturnal and diurnal species. In cases in which damage extended to the SCN, masking responses to light were present and similar to those displayed by animals with damage restricted to the vSPVZ. Thus, extensive bilateral lesions of the SCN and vSPVZ disrupted the expression of circadian rhythms without affecting acute responses to light in a diurnal species. Our present and previous results suggest that retinorecipient brain areas other than the SCN or vSPVZ, such as the intergeniculate leaflet or olivary pretectal nucleus, may be responsible for the mediation of masking responses to light in the diurnal grass rat.

Intergeniculate leaflet lesions result in differential activation of brain regions following the presentation of photic stimuli in Nile grass rats.

The intergeniculate leaflet (IGL) plays an important role in the entrainment of circadian rhythms and the mediation of acute behavioral responses to light (i.e., masking). Recently, we reported that IGL lesions in diurnal grass rats result in a reversal in masking responses to light as compared to controls. Here, we used Fos as a marker of neural activation to examine the mechanisms by which the IGL may influence this masking effect of light in grass rats. Specifically, we examined the patterns of Fos activation in retinorecipient areas and in brain regions that receive IGL inputs following 1-h light pulses given during the early night in IGL-lesioned and sham-operated grass rats. Three patterns emerged: (1) IGL lesions had no effect on the Fos response to light, (2) IGL lesions resulted in a reversal in Fos responses to light, and (3) IGL lesions resulted in a lack of a Fos response to light. Of specific interest were the suprachiasmatic nucleus (SCN) and the olivary pretectal nucleus (OPT), both of which are retinorecipient and connect reciprocally with the IGL. Light-induced Fos expression in the SCN was unaffected by IGL lesions, whereas the OPT exhibited a significant reduction in Fos expression following a light pulse in animals with IGL lesions. Altogether, our results suggest that the OPT, but not the SCN, exhibits a reversal in Fos responses to light following IGL lesions that reverse masking responses in diurnal grass rats. Our results suggest that interconnections between the IGL and downstream brain areas (e.g., OPT) may play a role in determining the direction of the behavioral response to light.

Distinct retinohypothalamic innervation patterns predict the developmental emergence of species-typical circadian phase preference in nocturnal Norway rats and diurnal nile grass rats.

How does the brain develop differently to support nocturnality in some mammals, but diurnality in others? To answer this question, one might look to the suprachiasmatic nucleus (SCN), which is entrained by light via the retinohypothalamic tract (RHT). However, because the SCN is more active during the day in all mammals studied thus far, it alone cannot determine circadian phase preference. In adult Norway rats (Rattus norvegicus), which are nocturnal, the RHT also projects to the ventral subparaventricular zone (vSPVZ), an adjacent region that expresses an in-phase pattern of SCN-vSPVZ neuronal activity. In contrast, in adult Nile grass rats (Arvicanthis niloticus), which are diurnal, an anti-phase pattern of SCN-vSPVZ neuronal activity is expressed. We hypothesized that these species differences result in part from a weak or absent RHT-to-vSPVZ projection in grass rats. Here, using a developmental comparative approach, we assessed species differences in behavior, hypothalamic activity, and RHT anatomy. We report that a robust retina-to-vSPVZ projection develops in Norway rats around the end of the second postnatal week when nocturnal wakefulness and the in-phase pattern of neuronal activity emerge. In grass rats, however, such a projection does not develop and the emergence of the anti-phase pattern during the second postnatal week is accompanied by increased diurnal wakefulness. When considered within the context of previously published reports on RHT projections in a variety of species, the current findings suggest that how and when the retina connects to the hypothalamus differentially shapes brain and behavior to produce animals that occupy opposing temporal niches.