Daylight effect on melatonin secretion in adult female guanacos (Lama guanicoe)

The wild South American camelids developed a strategy of seasonal reproduction during spring and summer with singleton birth. The photoperiod is one of the factors that may modulate this seasonality where light would be translated into a hormonal signal. This study evaluated the influence of changes in daily light intensity on melatonin concentration in captive guanacos under a long‐day photoperiod (16 hr light/8 hr dark; 33 ‘28′S). Mean melatonin concentration was 28.3 ± 20.3 pg/ml, with a maximum of 52.14 ± 17.19 pg/ml at 23:30 and minimum of 14.29 ± 6.64 pg/ml at 08:30 (p < .001). There was a negative association between light intensity and melatonin concentration (r = ?0.57; p < .001). The results indicate that guanacos respond to variation in daily environmental light with a hormonal response and point to a circannual rhythm as a function of the photoperiod.     

Immunohistochemical Expression of Cyclooxygenase‐2 (COX‐2) in Feline Endometrial Adenocarcinoma and in Normal and Hyperplastic Endometria

Cyclooxygenase‐2 (COX‐2) is overexpressed in several human and animal neoplasms, including the human endometrial carcinoma. It has been suggested as a prognostic marker and a potential therapeutic target. This study aimed to (i) clarify histological aspects of feline endometrial adenocarcinomas (FEA) of the papillary serous type and (ii) characterize COX‐2 immunohistochemical expression in normal, hyperplastic and neoplastic endometrium in this species. Archived paraffin‐embedded tissue samples of 33 FEA, eight cystic endometrial hyperplasias (CEHs) and 21 samples of normal, healthy endometrium in the follicular (FS; n = 10) and luteal (LS; n = 11) stages were evaluated. Histological evaluation of haematoxylin and eosin‐stained sections of the FEA revealed a papillary proliferation of neoplastic cells of serous type, accompanied by clear and multinucleated cells. Other architectural arrangements mainly included solid and tubular growth. Randomly distributed areas of necrosis within the tumours were commonly observed. Invasion of the myometrium, of the serosa and of the vascular and/or lymphatic vessels was not constant features. The mean number of mitoses was higher in FEA compared to non‐neoplastic endometrium. COX‐2 scores were lower in FEA (p = 0.003) and CEH (p = 0.05) when compared to normal epithelium (NE). The loss of the membrane apical reinforcement in epithelial cells was observed in FEA samples, which was accompanied by the dislocation of COX‐2 labelling into the cytoplasm and the perinuclear area; in contrast, in epithelial cells in the healthy and hyperplastic endometria, the immunoreaction showed the characteristic pattern of apical membrane reinforcement, suggestive of the membrane polarization. COX‐2 epithelial scores were higher in the FS than in the LS. No differences were found in stromal COX‐2 expression between normal, CEH and FEA groups, but it was higher in the LS than in the FS. In summary, loss of COX‐2 compartmentalization in neoplastic epithelial cells might be one of the molecular events underlying endometrial carcinogenesis.     

Age-related NADH oxidase (arNOX) activity is significantly reduced in coelomic fluid of long-lived sea urchins

Age-related NADH oxidase (arNOX) is a cell surface protein shed into the circulation and other body fluids, which generates superoxide. The activity increases with age in human tissues and body fluids (serum, saliva, and perspiration) and is a potential source of age-related oxidative damage. We measured arNOX activity in the coelomic fluid of sea urchin species with different life spans. Coelomic fluid of long-lived sea urchin species Strongylocentrotus purpuratus and Strongylocentrotus franciscanus exhibited low levels of arNOX compared to the short-lived urchin species Lytechinus variegatus. arNOX activity was positively correlated with animal size in L. variegatus, whereas with S. purpuratus and S. franciscanus, arNOX activity and animal size were inversely correlated. The inverse correlation of arNOX activity with life span and decreased levels of arNOX with age in the long-lived species is consistent with a contribution of reduced arNOX activity to slower aging.