Persistence of fish populations in the upper Paraná River: effects of water regulation by dams     

É. A. Gubiani  L. C. Gomes  A. A. Agostinho  E. K. Okada 《Ecology of Freshwater Fish》2007,16(2):191-197

Abstract –  River–floodplain systems present intense temporal variations in physical, chemical and biological factors. These variations are closely related to alterations in water levels, which have been attributed to the flood pulse. As several species are strictly related to the flood pulse to fulfil their life cycle, the pulse may be seen as a dispersal mechanism of species onto a floodplain. In this study, we determine how dam construction influenced the persistence of Prochilodus lineatus population, a large migratory fish species from the upper Paraná River floodplain. Data used were collected in two distinct periods, from April 1992 to March 1993 and from January 1999 to December 2001. Fish were collected using seining nets in six (monthly in the first period) and seven (quarterly in the second period) isolated lagoons. The fraction of occupied lagoons was high in the first period (higher than 0.65), when flood was intense. However, in the second period, when the flood pulse did not happen or was short, the fraction of occupied lagoons sharply decreased over time (from 0.85 to 0.22). For the first period, no model fitted to data, but for the second period, a negative linear model (named drought-dependent model) presented good fit ( r ² = 0.97). Therefore, it is possible to infer that long and intense flood pulses are important to maintain the persistence of P. lineatus populations in the floodplain. The artificial control of water levels prompted by dams disrupts this dynamic, reducing persistence to critical levels.  相似文献   

Formation of the thiocyanate conjugate of chlorogenic acid in coffee under acidic conditions in the presence of thiocyanate and nitrite: possible occurrence in the stomach     

Takahama U  Tanaka M  Oniki T  Hirota S  Yamauchi R 《Journal of agricultural and food chemistry》2007,55(10):4169-4176

The objective of the present study was to elucidate how chlorogenic acid in coffee was transformed under acidic conditions simulating the mixture of saliva and gastric juice. When coffee was incubated in acidified saliva that contained nitrite and SCN-, in addition to nitric oxide (NO), four major components were detected. Two of the four components (components 3 and 4) were generated when chlorogenic acid was incubated in acidified saliva and when incubated in an acidic buffer solution in the presence of both nitrite and SCN-. By the incubation of chlorogenic acid in acidic nitrite in the absence of SCN-, components 3 and 4 were not formed but the quinone of chlorogenic acid and nitrated chlorogenic acid were formed. The result indicates that SCN- was indispensable for nitrous acid induced formation of components 3 and 4. Component 4 was isolated and its structure was determined to be (E)-5'-(3-(7-hydroxy-2-oxobenzo[d] [1,3]oxathiol-4-yl)acryloyloxy)quinic acid. Component 3, which was suggested to be 2-thiocyanatochlorogenic acid, seemed to be formed by the reaction between SCN- and the quinone of chlorogenic acid. As it has been reported that the quinone of chlorogenic acid can react with thiols and can decompose producing H2O2, the formation of component 4 can reduce the toxic effects of the quinone of chlorogenic acid.  相似文献   

Incidence of ovulation without coital stimuli in captive Japanese black bears (Ursus thibetanus japonicus) based on serum progesterone profiles     

Okano T  Nakamura S  Nakashita R  Komatsu T  Murase T  Asano M  Tsubota T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2006,68(10):1133-1137

The purpose of this study was to ascertain whether or not Japanese black bears (Ursus thibetanus japonicus) are induced ovulators. The progesterone levels of female bears kept with a male and allowed to mate (n=2) and female bears allowed contact with a male through bars but not allowed to mate (n=6) during the mating season increased significantly in late October. Based on this result, the female bears were considered to have ovulated. Females isolated from males (n=3) were ovarioectomized after the mating season, and no corpora lutea were observed, indicating they had not ovulated. These findings suggest that Japanese black bears may be induced ovulators that ovulate with stimuli from males and without coitus at a high rate.  相似文献   

Persorption of luminal antigenic molecule and its specific antibody via apoptotic epithelial cells of intestinal villi and Peyer's patches into peripheral blood in rats     

Yuji M  Tsubata M  Chin K  Onishi S  Inamoto T  Qi WM  Warita K  Yokoyama T  Hoshi N  Kitagawa H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2006,68(12):1297-1305

The possibility of persorption of bovine serum albumin (BSA) molecules from mucous epithelial cells and its mechanism were investigated in rats orally pre-immunized by BSA for 14 consecutive days. In the small and large intestines, both the BSA antigen (BSA-Ag) and its specific antibody (SpAb) were absorbed by the epithelial cells at the late apoptotic stage (ApoEp), and were subsequently transcytosed by membranes of the small vesicles. The basal cytoplasms containing highly-concentrated BSA-Ag and SpAb were occasionally fragmented into small cytoplasmic droplets that were secreted into the lamina propria. In Peyer's patches, both BSA-Ag and SpAb were more actively absorbed and transcytosed toward the dome area by the ApoEp of the dome apex than by the M cells. BSA-Ag and SpAb were finally persorbed into the portal blood and lymph, but were never secreted into the bile. They were also engulfed by macrophage-like cells in the villous lamina propria, mesenteric lymph node and spleen, and by hepatocytes in the liver. These findings suggest that sensitized soluble luminal antigens are taken up by ApoEp in the small intestine and are finally persorbed into the peripheral blood. The uptake of luminal antigen might be mediated by its luminal SpAb.  相似文献   

Detection of a small number of Cryptosporidium parvum oocysts by sugar flotation and sugar centrifugation methods     

Fujino T  Matsuo T  Okada M  Matsui T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2006,68(11):1191-1193

Detection rates from the samples including a small number of Cryptosporidium parvum oocysts were compared between the sugar flotation and the sugar centrifugal flotation methods. As the results, the oocysts were detected from 70 and 80 of 100 samples including 6.0x10(2) and 1.0x10(3) oocysts per 1 ml by the flotation method, respectively, whereas from 52 and 53 of the same samples by the centrifugal flotation method. Therefore, it was considered that the flotation method is the most suitable method for the detection from samples including a small number of Cryptosporidium oocysts. It is also suggested that results of the sugar flotation method were reliable for samples including more than 1.0x10(3) oocysts/ml.  相似文献   

Diagnosis of olfactory neuroblastoma in a dog by magnetic resonance imaging     

Kitagawa M  Okada M  Yamamura H  Kanayama K  Sakai T 《The Veterinary record》2006,159(9):288-289

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Benzodiazepines inhibit the acetylcholine receptor-operated potassium current (IK.ACh) by different mechanisms in guinea-pig atrial myocytes     

Okada M  Mizuno W  Nakarai R  Matada T  Yamawaki H  Hara Y 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2012,74(7):879-884

The anticholinergic effects of 7 benzodiazepines, bromazepam, camazepam, chlordiazepoxide, diazepam, lorazepam, medazepam and triazolam, were compared by examining their inhibitory effects on the acetylcholine receptor-operated potassium current (I(K).(ACh)) in guinea-pig atrial myocytes. All of these benzodiazepines (0.3-300 μM) inhibited carbachol (1 μM)-induced I(K).(ACh) in a concentration-dependent manner. The ascending order of IC(50) values for carbachol-induced I(K).(ACh) was as follows; medazepam, diazepam, camazepam, triazolam, bromazepam, lorazepam and chlordiazepoxide (>300 μM). The compounds, except for bromazepam, also inhibited I(K).(ACh) activated by an intracellular loading of 100 μM guanosine 5'-[γ-thio]triphosphate (GTPγS) in a concentration-dependent manner. The ascending order of IC(50) values for GTPγS-activated I(K).(ACh) was as follows; medazepam, diazepam, camazepam, lorazepam, triazolam chlordiazepoxide (>300 μM) and bromazepam (>300 μM). To clarify the molecular mechanism of the inhibition, IC(50) ratio, the ratio of IC(50) for GTPγS-activated I(K).(ACh) to carbachol-induced I(K).(ACh), was calculated. The IC(50) ratio for camazepam, diazepam, lorazepam, medazepam and triazolam was close to unity, while it for chlordiazepoxide could not be calculated. These compounds would act on the GTP binding protein and/or potassium channel to achieve the anticholinergic effects in atrial myocytes. In contrast, since the IC(50) ratio for bromazepam is presumably much higher than unity judging from the IC(50) values (104.0 ± 30.0 μM for carbachol-induced I(K).(ACh) and >300 μM for GTPγS-activated I(K).(ACh), it would act on the muscarinic receptor. In summary, benzodiazepines had the anticholinergic effects on atrial myocytes through inhibiting I(K).(ACh) by different molecular mechanisms.  相似文献   

Relationship between pH and Temperature in the Ruminal Fluid of Cows, Based on a Radio-Transmission pH-Measurement System     

Kimura A  Sato S  Kato T  Ikuta K  Yamagishi N  Okada K  Mizuguchi H  Ito K 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2012,74(8):1023-1028

To assess the relationship between pH and temperature in the ruminal bottom fluid, circadian changes were monitored using cows fed a control diet (C diet) or a rumen acidosis-inducing diet (RAI diet) by using a wireless radio-transmission pH- measurement system. These two parameters were measured simultaneously at 10-min intervals on day 14 after commencement of feeding. Compared to the mean ruminal pH for 60 min immediately after the morning feeding (0 hr), significantly lower pH was noted 3-13 hr later (P<0.05) and 4-19 hr later (P<0.01) in cows fed the C and RAI diets, respectively, although the reduction in the latter was much higher than that in the former. In contrast, significantly higher ruminal temperature was found at 8 and 12-14 hr later (P<0.05) and 6, 8, and 10-19 hr later (P<0.01) in cows fed the C and RAI diets, respectively. A significant negative correlation was observed between the lowest ruminal pH and its corresponding ruminal temperature in cows fed the C and RAI diets (r=-0.722 and -0.650, P<0.01, respectively), suggesting active fermentation and volatile fatty acid production in the rumen. However, ruminal pH profiles may not be predictable by measuring only ruminal temperature because decreases in ruminal pH were preceded by increases in ruminal temperature, and circadian changes in pH and temperature were associated with ruminal fermentation.  相似文献   

Superoxide dismutase activity as a measure of hepatic oxidative stress in cattle following ethionine administration     

Abd Ellah MR  Okada K  Goryo M  Oishi A  Yasuda J 《Veterinary journal (London, England : 1997)》2009,182(2):336-341

The goal of this study was to assess if oxidative stress, as measured by alterations in the concentrations of antioxidant enzymes in the liver and erythrocytes of cattle, could be induced following dl-ethionine administration. Whole blood, serum and liver biopsy samples were collected 0, 4, 7 and 10 days after intra-peritoneal ethionine administration to five cows. The activities of the antioxidant enzymes copper zinc superoxide dismutase (Cu, Zn SOD) and catalase were assessed in the liver biopsies which were also examined histopathologically.Significant increases in hepatic Cu, Zn SOD concentrations (P < 0.01) were noted on days 7 and 10 post-treatment. Hepatic catalase activity decreased significantly (P < 0.01) on days 4, 7 and 10 post-treatment and erythrocyte Cu, Zn SOD activity was significantly increased on day 10. Serum biochemical analysis revealed a significant increase (P < 0.01) in non-esterified fatty acid concentrations on day 4 and significant decreases in total cholesterol and phospholipid levels on days 4 (P < 0.05), 7 (P < 0.01) and 10 (P < 0.01). In this model system, dl-ethionine administration was effective in inducing oxidative stress particularly reflected in the liver.  相似文献   

Lipid peroxides and antioxidants in serum of neonatal calves     

Inanami O  Shiga A  Okada K  Sato R  Miyake Y  Kuwabara M 《American journal of veterinary research》1999,60(4):452-457

OBJECTIVE: To examine the association between oxidative stress and antioxidants in neonatal calves after birth. SAMPLE POPULATION: Sera from 6 healthy Holstein-Friesian cows and 7 of their newborn calves were obtained at various intervals after birth. PROCEDURE: Lipid peroxides in serum of cows and their newborn calves were estimated by measuring concentrations of thiobarbituric acid-reactive substances (TBARS). The antioxidative activities of neonatal sera were evaluated by measuring their superoxide-scavenging activities, ferroxidase activities, and the concentration of bilirubin-associated albumin. RESULTS: Concentration of TBARS in neonatal sera within 1 day after birth was significantly higher than concentrations > or = 2 days after birth and concentrations in serum of the dams. In contrast, antioxidative activities of neonatal sera, evaluated on the basis of superoxide-scavenging activities, ferroxidase activities, and concentration of bilirubin-associated albumin 3 hours after birth, were significantly lower than antioxidative activities in sera of the dams. CONCLUSIONS: Susceptibility of calves to oxidative stress during the neonatal period may be explained by the immature defense system against superoxide radicals.  相似文献