Distribution of taste buds in layer‐type chickens: Scanning electron microscopic observations

The distribution of taste buds of layer‐type chickens, from day 1 (H1) to day 140 (H140) post‐hatching, were investigated histologically and with a scanning electron microscope. Two types of openings were observed on the oral epithelium: large openings that were greater than 10 μm in width, and had an ellipsoid or spindle shape; and small openings that were less than 7 μm in width, and had a circular or polygon shape. It was defined that the former represent the openings of the salivary glands, and the latter are those of the taste buds. The number of taste buds remained constant from H1 to H140. Therefore, no significant change was observed between these two time points. To investigate the distribution of the taste buds in the whole oral cavity, a distribution map was created.     

Estradiol inhibits hepatic stellate cell area and collagen synthesis in the chicken liver

Hepatic stellate cells (HSCs) are the main collagen‐producing cells in the liver. The HSC area and amount of collagen fibers are different between male and female chickens. This study was performed to confirm the effect of estradiol on collagen synthesis in the growing chicken liver. Blood estradiol levels in chicks were compared at 4 and 8 weeks of age, and the collagen fibril network in liver tissue was observed at 8 weeks by scanning electron microscopy. Intraperitoneal administrations of estradiol and tamoxifen to male and female chicks, respectively, were performed daily from 5 to 8 weeks of age. The areas of HSCs and collagen contents were measured in the liver tissue. The blood estradiol level was higher in females than in males, and the collagen fibril network was denser in males than in females at 8 weeks of age. Estradiol administration in males induced decreases in the HSC area and collagen content of the liver. Conversely, tamoxifen administration in females induced an increase in the HSC area but did not facilitate collagen synthesis. Based on these results, estradiol inhibits the area and collagen synthesis of HSCs in the growing chicken liver under normal physiological conditions.     

Cytokeratin‐positive folliculo‐stellate cells in chicken adenohypophysis

Folliculo‐stellate (FS) cells are non‐endocrine cells found in the adenohypophysis and are identified in many animals by the S100 protein marker. Although keratin is another FS marker in several animals, there is no information on localization of keratin in the avian adenohypophysis. In this study, localization of cytokeratin in chicken adenohypophyseal cells was investigated immunohistochemically. Basic cytokeratin (bCK)‐positive cells were arranged radially in the cell cords with their cytoplasmic processes reaching the basal lamina. The cell bodies encircled a follicle in the center of the cell cord. Furthermore, the bCK‐positive cells were also S100B‐positive. Growth hormone, prolactin, adrenocorticotrophic hormone, and luteinizing hormone β‐subunit did not co‐localize with the bCK‐positive cells. In addition, the bCK‐positive cells had a laminin‐positive area in their cytoplasm. Transmission electron microscopy observed agranular cells equipped with several microvilli that encircled a follicle. These results indicate that bCK‐positive cells in the chicken adenohypophysis may be a predominant FS cell population and produce laminin. It is suggested that they function as sustentacular cells to sustain the adjacent endocrine cells and the structure of the cell cords in the chicken adenohypophysis.     

Association between preoperative characteristics and risk of anaesthesia-related death in dogs in small-animal referral hospitals in Japan

Objective

To explore the major risk factors linking preoperative characteristics and anaesthesia-related death in dogs in referral hospitals in Japan.

Evaluation of the Modifying Effect of Inhalation of Mainstream Cigarette Smoke on Mouse Bladder Carcinogenesis

Cigarette smoking is one of the major risk factors of bladder cancer in humans. To date, however, there is no experimental evidence for the effects of inhalation exposure to mainstream cigarette smoke on bladder carcinogenesis. The purpose of the present study was to evaluate the effect of inhalation of mainstream cigarette smoke on mouse bladder carcinogenesis using a cigarette smoke inhalation exposure system. Six-week-old male C57BL mice were administered 0.025% N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) in their drinking water for 8 weeks and then divided into 2 groups and exposed to 0 or 300 mg/m³ wet total particulate matter mainstream cigarette smoke for 2 h per day, five times per week, for 22 weeks. The incidences of bladder tumors (papilloma and urothelial carcinoma) tended to increase in the cigarette smoke-exposed group (25.0%) compared with the controls (15.8%), albeit without a statistically significant difference. We also evaluated mRNA expression levels of cytochrome P450 (cyp) enzymes and proliferating cell nuclear antigen (PCNA) in the bladder epithelium. Expression of cyp1a1 was significantly increased in the cigarette smoke-exposed group. Cigarette smoke exposure did not have a significant effect on the expression of cyp1a2, cyp 1b1, cyp 2a4, cyp 2b10, cyp 2e1, or PCNA. In conclusion, limited exposure to mainstream cigarette smoke for 22 weeks, caused a significant increase in cyp1a1 expression. This increase coupled with the nonsignificant increase in bladder tumors suggests that a longer period of exposure is required to clarify the effects of cigarette smoke on bladder carcinogenesis.     

Immunocytochemical localization of gonadotropins during the development of XX and XY Nile tilapia

Gonadal development and steroidogenesis in teleosts is regulated by two gonadotropic hormones; luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Earlier studies in tilapia have shown that FSH-β and LH-β appear by 14 days after hatching (dah), results from the current study corroborate with these previous reports in tilapia. Here we demonstrate the appearance of LH in pituitary between 14 and 20 dah. In addition to this the present study primarily focuses on any possible differences in appearance of LH-β and FSH-β immunoreactivity between XX and XY population of Nile tilapia. LH immunoreactivity was found to be lower in pituitary of XX fish when compared to XY fish. The development of FSH-β immunoreactivity in pituitary of the Nile tilapia is also presented. Overall, it remains to be established what significance these findings on the appearance of gonadotropins hold for sex differentiation in tilapia. F. Sakai and I. Swapna contributed equally.     

Role of steriod hormones in sex change of protogynous wrasse

The endocrine mechanisms of sequential hermaphroditism were investigated in protogynous wrasse, Halichoeres trimaculatus. Administration of aromatase inhibitor and androgen both stimulated sex change, while estrogen suppressed the induced sex inversion. The results suggest that removal of estrogen is a key step to initiate sex change.     

Behaviour of immature yellowtails (Seriola quinqueradiata) observed by electronic data-recording tags

The long-term behaviour of immature yellowtails, Seriola quinqueradiata , was studied using electronic data-recording tags in Sagami Bay, Japan, during the autumn and early winter. Temperature or depth data were continuously recorded for 5–69 days on six yellowtails. The temperature recorded from the 0-year-old yellowtails showed only small variations (<0.5°C day⁻¹) around the SST on the coast, indicating the 0-years stayed in the immediate coastal area with little horizontal movement. The 1-year-old yellowtail showed larger temperature variations that reached 3°C day⁻¹, which implies distinctly larger horizontal movements than the 0-year-olds. Depth records showed the 0-years stayed around 10 m while the 1-year yellowtail swam in deeper water (mainly 10–30 m) with large variations. The latter often dived to 40 m in the daytime, but shallower than the depth of the thermocline. Both temperature and depth records showed apparent diurnal patterns. Comparing the fish data with environmental conditions, it is suggested that 1-year yellowtails stay close to the coast during the night, move at dawn to feed in the daytime and return at dusk via a frontal zone. In addition, wind stress could change yellowtails' behaviour.     

Detection of indoleamine 2,3-dioxygenase 1-expressing cells in canine normal and tumor tissues

Cancer immunotherapy is a novel cancer treatment for canine tumors. Indoleamine 2,3-dioxygenase 1 (IDO1) is overexpressed in some human tumors and inhibits antitumor immunity. In this study, we comprehensively evaluated expression pattern of IDO1 and the nature of IDO1-expressing cells in canine normal and tumor tissues. In normal tissue samples, IDO1 expression was detected only in the lymph nodes, spleen, tonsil tissues, and colon tissues. In contrast, IDO1-positive tumor cells were observed in several tumor tissue types. This is the first study to evaluate IDO1 expression in canine normal and tumor tissues, and the results suggest that IDO1 is a promising target for novel cancer immunotherapy in dogs with tumors.     

Gustducin is expressed in the taste buds of the chicken

We investigated the expression of gustducin in chicken taste buds using molecular biological, biochemical and immunohistochemical techniques. Expression of a gustducin‐like sequence was detected by RT‐PCR in the tissues containing taste buds, and corresponded to the predicted gustducin gene in the chicken. Expression of this sequence was not detected in the brain, heart, liver, pancreas, intestine, kidney and testis of the chicken. The expressed sequence had a high specificity for oral tissues that contained taste buds. These results suggest that the detected sequence was the chicken gustducin gene. Next, we generated a polyclonal antiserum against the chicken gustducin protein to observe its localization in the oral tissues. The results revealed that the chicken gustducin was specifically expressed in the taste buds. It is suggested that the chicken has a gustatory system mediated by gustducin, and chicken gustducin is a reliable marker for taste buds or taste cells. This is the first molecular biological, biochemical and immunohistochemical demonstration of the presence of gustducin in the chicken.