Variations in the pituitary–interrenal axis and the abundance of circulating blood-cell types in juvenile coho salmon, Oncorhynchus kisutch, during stream residence

1975 ◽  
Vol 53 (12) ◽  
pp. 1882-1891 ◽  
Author(s):  
D. J. McLeay
Keyword(s):  
Blood Cell ◽  
Cell Size ◽  
Seasonal Variations ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Secretory Activity ◽  
Cell Types ◽  
Temperature Acclimation ◽  
Small Lymphocyte ◽  
Natural Stream

According to histological and histometric indices, the pituitary–interrenal axis of juvenile coho salmon residing in a natural stream was inactive in postalevin fry sampled in the spring, and in summer and fall samples of fingerlings, compared with a December sample or with smolts captured the next spring. Interrenal nuclear diameters, interrenal cell size, and epsilon (adrenocorticotropin) cell nuclear diameters were highly positively correlated.The numbers of circulating small lymphocytes and thrombocytes were highest in summer samples. Numbers of circulating large lymphocytes and neutrophils (per thousand cells of all types) were small and did not differ from sample to sample.Histometric indices of pituitary–interrenal axis activity were negatively correlated with numbers of circulating small lymphocytes but were unrelated to thrombocyte counts. Water temperature during sampling was highly negatively correlated with interrenal number and cell size and epsilon-cell nuclear diameters, and positively correlated with small lymphocyte and thrombocyte counts.It was concluded that the pituitary–interrenal axis in juvenile coho salmon was activated by both cold-temperature acclimation and smoltification. Unlike thrombocytes, the seasonal variations in numbers of circulating small lymphocytes were attributed to adrenocortical secretory activity.

Effect of Changes in Streamflow on the Microhabitat Use and Movements of Sympatric Juvenile Coho Salmon (Oncorhynchus kisutch) and Chinook Salmon (O. tshawytscha) in a Natural Stream

1994 ◽  
Vol 51 (7) ◽  
pp. 1644-1652 ◽  
Author(s):  
C. S. Shirvell
Keyword(s):  
Chinook Salmon ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Microhabitat Use ◽  
Net Energy ◽  
Optimal Position ◽  
Juvenile Chinook Salmon ◽  
Natural Stream ◽  
Juvenile Chinook ◽  
Seasonal Streamflow

The microhabitats at positions selected by juvenile coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) following a change in streamflow differed from microhabitats occupied at normal streamflows. At drought streamflow (37% mean seasonal streamflow (MSF)), juvenile coho salmon selected slower, darker, and higher sites above the streambed (P < 0.05) than sites selected at normal (75% MSF) or flood (159% MSF) flows. Juvenile chinook salmon microhabitat use changed similarly with changes in streamflow, but the differences were not significant. Up to one fifth of the fish chose positions with faster water velocities than those available either 30 cm above or 30 cm lateral to them. These fish chose positions inconsistent with the hypothesis of optimal position selection based on maximizing net energy gain. On average, fish moved 6.8 m following a change in streamflow. Juvenile coho salmon generally moved upstream in response to decreasing streamflows and downstream in response to increasing streamflows. Juvenile chinook salmon tended to move offshore and downstream in response to all streamflow changes. These results show that juvenile coho and chinook salmon will move to find suitable microhabitat following a change in streamflow and that the microhabitats are not the same at all streamflows.

Changes in Some Hematological Characteristics of Coho Salmon (Oncorhynchus kisutch) in Response to Acute Exposure to Dehydroabietic Acid (DHAA) at Different Exercise Levels

1976 ◽  
Vol 33 (2) ◽  
pp. 285-289 ◽  
Author(s):  
George K. Iwama ◽  
G. L. Greer ◽  
P. A. Larkin
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Dehydroabietic Acid ◽  
Sedimentation Rates ◽  
Cell Counts ◽  
Blood Cell Counts ◽  
Erythrocyte Sedimentation ◽  
Erythrocyte Sedimentation Rates

To determine if changes in some hematological parameters accompanied acute exposure of juvenile coho salmon (Oncorhynchus kisutch) to dehydroabietic acid (DHAA) at three different exercise levels, clotting times, hematocrits, erythrocyte sedimentation rates, red blood cell counts, and white blood cell counts were monitored over 6-, 12-, 24-, and 48-h exposure periods to 0.75 mg/liter DHAA.White cell counts decreased significantly after 24 h exposure and there was a significant increase in clotting times after 48 h exposure to DHAA. In both cases, differences between experimentals and controls were significant only at low and intermediate exercise levels and not at a high exercise level. Hematocrits, erythrocyte sedimentation rates, and red blood cell counts were not significantly different between experimentals and controls for any of the exposure periods or exercise levels.

Sensitivity of Blood Cell Counts in Juvenile Coho Salmon (Oncorhynchus kisutch) to Stressors Including Sublethal Concentrations of Pulpmill Effluent and Zinc

1975 ◽  
Vol 32 (12) ◽  
pp. 2357-2364 ◽  
Author(s):  
D. J. McLeay
Keyword(s):  
Blood Cell ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Sublethal Concentration ◽  
Experimental Conditions ◽  
Cell Counts ◽  
Blood Cell Counts ◽  
Stock Values ◽  
Sublethal Concentrations ◽  
Sensitive Method

Transfer of fish from optimal to high-temperature, crowded holding conditions decreased white blood cell-thrombocyte (WBC-T) counts markedly on 12–96-h exposure. Red blood cell (RBC) counts were increased only slightly at 12 and 48 h. During 28 days acclimatization following transfer to simulated stream compartments, WBC-T counts returned to stock values within 2–4 days, following an initial decline. RBC counts were not altered appreciably.The decline in WBC-T counts of acclimatized fish to a high sublethal concentration of pulpmill effluent was greatest at 24 h. Mean RBC counts were decreased over 24–96 h, but differences were significant at 24 h only. In acclimatized fish exposed to pulpmill effluent, WBC-T counts were decreased (P < 0.001) at concentrations between 0.2 and 0.9 of the 96-h LC50. A 24-h exposure to 15% vol/vol of this effluent had considerably less effect on the WBC-T count when the effluent had been detoxified by foam fractionation.Under similar experimental conditions, exposure to sublethal levels of zinc depressed mean WBC-T counts proportional to concentration, although differences were only significant at 0.5 LC50 and greater. RBC counts were unchanged.The WBC-T response provides a reasonably rapid and sensitive method for measuring stressful levels of pulpmill effluents to salmon. Declines in WBC-T counts are attributable to reduced numbers of circulating small lymphocytes, which could result in decreased resistance of stressed fishes to disease.

scholarly journals Telomere length varies substantially between blood cell types in a reptile

2020 ◽  
Vol 7 (6) ◽  
pp. 192136 ◽  
Author(s):  
Mats Olsson ◽  
Nicholas J. Geraghty ◽  
Erik Wapstra ◽  
Mark Wilson
Keyword(s):  
Blood Cell ◽  
Telomere Length ◽  
Whole Blood ◽  
Phylogenetic Analyses ◽  
Natural Populations ◽  
Cell Types ◽  
Tissue Type ◽  
Telomeric Dna ◽  
Blood Cell Type ◽  
Widespread Phenomenon

Telomeres are repeat sequences of non-coding DNA-protein molecules that cap or intersperse metazoan chromosomes. Interest in telomeres has increased exponentially in recent years, to now include their ongoing dynamics and evolution within natural populations where individuals vary in telomere attributes. Phylogenetic analyses show profound differences in telomere length across non-model taxa. However, telomeres may also differ in length within individuals and between tissues. The latter becomes a potential source of error when researchers use different tissues for extracting DNA for telomere analysis and scientific inference. A commonly used tissue type for assessing telomere length is blood, a tissue that itself varies in terms of nuclear content among taxa, in particular to what degree their thrombocytes and red blood cells (RBCs) contain nuclei or not. Specifically, when RBCs lack nuclei, leucocytes become the main source of telomeric DNA. RBCs and leucocytes differ in lifespan and how long they have been exposed to ‘senescence' and erosion effects. We report on a study in which cells in whole blood from individual Australian painted dragon lizards ( Ctenophorus pictus ) were identified using flow cytometry and their telomere length simultaneously measured. Lymphocyte telomeres were on average 270% longer than RBC telomeres, and in azurophils (a reptilian monocyte), telomeres were more than 388% longer than those in RBCs. If this variation in telomere length among different blood cell types is a widespread phenomenon, and DNA for comparative telomere analyses are sourced from whole blood, evolutionary inference of telomere traits among taxa may be seriously complicated by the blood cell type comprising the main source of DNA.

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