Histological changes in insulin-immunoreactive pancreatic ?-cells, and suppression of insulin secretion and somatotrope activity in brook trout (Salvelinus fontinalis) maintained on reduced food intake or exposed to acidic environment

1992 ◽  
Vol 10 (3) ◽  
pp. 229-243 ◽  
Author(s):  
D. B. Mackett ◽  
W. H. Tam ◽  
J. N. Fryer
Keyword(s):  
Insulin Secretion ◽  
Food Intake ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Acidic Environment ◽  
Histological Changes ◽  
Pancreatic Cells

The development and maturation of vitellogenic oocytes, plasma steroid hormone levels, and gonadotrope activities in acid-stressed brook trout (Salvelinus fontinalis)

1996 ◽  
Vol 74 (4) ◽  
pp. 587-593 ◽  
Author(s):  
W. H. Tam ◽  
Xiaomin Zhang
Keyword(s):  
Food Intake ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Ph Control ◽  
Oocyte Development ◽  
Control Fish ◽  
Control Group ◽  
Food Control ◽  
Neutral Ph ◽  
Sequence Of Events

Brook trout (Salvelinus fontinalis) were divided into a control group at neutral pH, a food-restricted control (Ph–food control) group at neutral pH, and an acid-stressed (pH 4.15) group, and were maintained under these conditions from August 14 to November 1. The food for the pH–food control group was restricted to simulate the reduced food intake of the acid-stressed fish. Throughout September, oocyte development in the acid-stressed fish was accelerated and the oocytes weighed 36–54% more than those of the pH control fish. By late September these oocytes had reached ovulatory size. Then a shift from predominantly high estrogen to high 17α,20β-dihydroxy-4-pregnen-3-one levels occurred in the circulation. Ovulation followed and by October 19 all acid-stressed trout had ovulated. The same sequence of events occurred significantly later in the pH control fish and ovulation was not complete on November 1. Although their oocytes were larger than those of pH control fish in September, hormonal changes and ovulation in pH–food control fish occurred at the same time as in pH control fish. The results suggest that while the reduced food intake during acid stress might have contributed to accelerated oocyte growth, the full effect of chronic acid exposure was responsible for advancing oocyte development, maturation, and ovulation.

Local Integrin Activation in Pancreatic Cells Targets Insulin Secretion to the Vasculature

2018 ◽  
Author(s):  
WannJun Gan ◽  
OanhhHoang Do ◽  
Louise Cottle ◽  
Elena Kosobrodova ◽  
Justin CooperrWhite ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Integrin Activation ◽  
Pancreatic Cells

Parasite-induced susceptibility to predation in diplostomiasis

Parasitology ◽  
1982 ◽  
Vol 85 (3) ◽  
pp. 495-501 ◽  
Author(s):  
P. Brassard ◽  
M. E. Rau ◽  
M. A. Curtis
Keyword(s):  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Marked Decrease ◽  
Infected Fish ◽  
Induced Susceptibility ◽  
Diplostomum Spathaceum

Guppies (Lebistes reticulatis) exposed to doses as low as 25 cercariae of Diplostomum spathaceum for 30 min were consistently and significantly more susceptible to predation by brook trout (Salvelinus fontinalis) than uninfected controls. The increase in susceptibility to predation was correlated with a marked decrease in the activity of infected fish.

scholarly journals Brook trout passage performance through culverts

2016 ◽  
Vol 73 (1) ◽  
pp. 94-104 ◽  
Author(s):  
Elsa Goerig ◽  
Theodore Castro-Santos ◽  
Normand Émile Bergeron
Keyword(s):  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Structural Characteristics ◽  
Passive Integrated Transponder ◽  
Complex Interactions ◽  
Factors Influencing ◽  
Several Variables ◽  
And Behavior ◽  
Steep Slopes ◽  
Corrugated Metal

Culverts can restrict access to habitat for stream-dwelling fishes. We used passive integrated transponder telemetry to quantify passage performance of >1000 wild brook trout (Salvelinus fontinalis) attempting to pass 13 culverts in Quebec under a range of hydraulic and environmental conditions. Several variables influenced passage success, including complex interactions between physiology and behavior, hydraulics, and structural characteristics. The probability of successful passage was greater through corrugated metal culverts than through smooth ones, particularly among smaller fish. Trout were also more likely to pass at warmer temperatures, but this effect diminished above 15 °C. Passage was impeded at higher flows, through culverts with steep slopes, and those with deep downstream pools. This study provides insight on factors influencing brook trout capacity to pass culverts as well as a model to estimate passage success under various conditions, with an improved resolution and accuracy over existing approaches. It also presents methods that could be used to investigate passage success of other species, with implications for connectivity of the riverscape.

Food Specialization By Individual Trout

1972 ◽  
Vol 29 (11) ◽  
pp. 1615-1624 ◽  
Author(s):  
James E. Bryan ◽  
P. A. Larkin
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Stomach Contents ◽  
Cutthroat Trout ◽  
Salmo Gairdneri ◽  
Potential Prey ◽  
Repeated Observation ◽  
Size Growth ◽  
Salmo Clarki

Analyses of stomach contents showed that the kinds of prey eaten by brook trout (Salvelinus fontinalis), cutthroat trout (Salmo clarki), and rainbow trout (Salmo gairdneri) were seldom distributed at random among the individuals. Repeated observation of food eaten by individuals in a stream and ponds showed that prey types were eaten in proportions which were characteristic for an individual.Specialization occurred on several different kinds of prey. Although the degree of specialization was higher during shorter intervals, the data suggested that some specialization persisted for half a year. There were no striking correlations between degree of specialization and other individual properties such as size, growth rate, weight of food, number of food items, previous specialization, or area of recapture.In addition to the observations on trout in relatively undisturbed habitats, a field experiment was conducted using laboratory-reared rainbow trout held in small ponds. The food of each trout in the experiment was sampled repeatedly. In analysis of variance, interaction among the individuals and kinds of prey eaten showed that food specialization occurred. Both the absolute and relative abundance of potential prey were constant during the experiment.

scholarly journals THE HYPOPHYSIS AND SECRETION OF INSULIN

1942 ◽  
Vol 75 (5) ◽  
pp. 547-566 ◽  
Author(s):  
B. A. Houssay ◽  
V. G. Foglia ◽  
F. S. Smyth ◽  
C. T. Rietti ◽  
A. B. Houssay
Keyword(s):  
Insulin Secretion ◽  
B Cells ◽  
Blood Sugar ◽  
Anterior Pituitary ◽  
Blood Sugar Level ◽  
Pituitary Hormone ◽  
Pituitary Extract ◽  
Histological Changes ◽  
High Blood Sugar ◽  
Anterior Pituitary Hormone

The ability of the pancreas, from various types of dogs, to correct diabetic hyperglycemia has been studied (Table XI). The pancreas from one animal was united by a vascular union with the neck blood vessels of another dog which had been pancreatectomized for 20 hours. The time necessary to reduce the blood sugar level to 120 mg. per cent was determined. 1. Pancreas from 6 hypophysectomized dogs produced a normal insulin secretion, showing that an anterior pituitary hormone is not necessary for its production or maintenance. 2. In 14 of 17 normal dogs given anterior pituitary extract for 3 or more consecutive days and presenting diabetes (fasting blood sugar 150 mg. per cent or more) the pancreas showed diminished insulin production. 3. In animals which remained diabetic after discontinuing the injections of hypophyseal extract, the pancreas islands were markedly pathologic and the insulin secretion was practically nil. 4. When hyperglycemia existed on the 2nd to 5th day but fell later, the insulin secretion of 5 dogs was normal in 2, supernormal in 1, and less than normal in 2. Histologic examination showed a restoration of beta cells. 5. In 14 dogs resistant to the diabetogenic action of anterior pituitary extract, as shown by little or no change in blood sugar, the pancreatic secretion of insulin was normal in 6 cases, supernormal in 3, and subnormal in 5 cases. Clear signs of hyperfunction of B cells were observed. In 6 resistant animals a high blood sugar (150 mg. per cent) appeared shortly before transplanting, but insulin secretion was normal in 4, supernormal in 1, and subnormal in 1 case. 6. With one injection of extract and 1 day of hyperglycemia the capacity of the pancreas to secrete insulin was not altered. 7. A high blood sugar level lasting 4 days does not alter the islets. The hypophyseal extract acts, therefore, by some other mechanism. In normal dogs, the continuous intravenous infusion of glucose for 4 days maintained the blood sugar at levels as high as those after pituitary extract. In these animals the B cells were hyperplastic and insulin secretion normal. 8. Anterior hypophyseal hyperglycemia is due at first to extrapancreatic factors which are the most important, and last only during the injections of extracts. Pancreatic factors appear afterwards and are responsible for permanent diabetes. Hypophyseal extract produces histological changes in many tissues and damages the Langerhans islands. The coexistent high blood sugar probably exhausts the B cells and exaggerates their injury. 9. In all cases there is a relation between the cytology of the islet B cells and the insulin secreting capacity.

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