Stress affects reproduction

A short account of how stress interferes with reproduction in farmed fish

The effects of environmental stress on the physiology of growth in rainbow trout, Salmo gairderi Richardson

There is little doubt that both mammalian and teleost growth hormones can accelerate growth and increase food conversion efficiency in all commonly-reared species of salmonid fish. In those vertebrates that have been closely studied (predominantly mammals), the pituitary hormone somatotropin (GH or growth hormone) is a prime determinant of somatic growth. The hormone stimulates protein biosynthesis and tissue growth, enhances lipid utilization and lipid release from the adipose tissues (a protein-sparing effect) and suppresses the peripheral utilization of glucose. The present study is a prerequisite for future work on growth hormone physiology in salmonids and should contribute to our understanding of the mechanisms of growth suppression in stressed fish. Plasma growth hormone (GH) levels were measured in rainbow trout using a radioimmunoassay developed against chinook salmon growth hormone

Changes in blood cortisol, glucose and lactate in carp retained in anglers' keepnets

Capture of carp from holding tanks by dip-net, or from semi-natural conditions by rod and line, elicits a physiological stress response characterised by elevation of plasma cortisol levels. The transfer of carp to keepnets subsequent to capture does not increase or reduce the magnitude or duration of this response and in both cases plasma cortisol levels have returned to pre-stress levels within 24 hours of the initial disturbance. The post-capture plasma cortisol elevation is accompanied by disturbances in plasma glucose and lactate levels but these are less consistent in severity and duration than the cortisol response. These data suggest that the retention of fish in keepnets following capture, does not represent a source of stress additional to that imposed by capture and has no effect on the rate of recovery of the fish from the initial capture stress

Changes in water quality within anglers' keepnets during the confinement of fish

The influence of mesh size and loading density on conditions within keepnets during the confinement of fish was examined. The performance of a mixed-mesh net was also evaluated. Confinement of fish within nets of a standard diameter and length and of three different mesh sizes for 5 hours resulted in no deleterious changes in levels of dissolved oxygen, unionized ammonia, carbon dioxide, or pH at any of three sample points within each net. Transfer of fish to similar nets at a similar, and a higher, loading for 5 hours resulted in a depletion of oxygen, and accumulation of ammonia, in the high-load nets. No changes in carbon dioxide levels or pH were observed in nets containing either moderate or high loads. Confinement of fish in mixed-mesh nets for 5 hours resulted in a depletion of dissolved oxygen in the lower section of the net and an accumulation of unionized ammonia. There were no changes in carbon dioxide, or pH. These results are discussed with reference to the water quality requirements of freshwater fish. It is concluded that changes in water quality within anglers keepnets during the confinement of fish are not of sufficient magnitude to adversely affect the confined fish

Pheromone reception in salmonid fish: identification and characterization of putative steroid receptors in olfactory tissue of brown and rainbow trout

Specific binding sites for testosterone have been detected in three compartments of olfactory tissue from brown and rainbow trout. Binding of 3H-testosterone to the membrane fraction of olfactory tissue is of high affinity (Kd = 0.5 - 1.9 nM) and limited capacity (Nmax= 30 - 60 fmol mg-1 protein). Binding is reversible, and is eliminated by protease treatment. The binding site exhibits a high degree of ligand specificity, 11β-hydroxytestosterone, 11-ketotestosterone, 17α-hydroxyprogesterone, 17α, 20β-dihydroxy-4-pregnen-3-one, cortisol, and estradiol-17β all fail to displace testosterone at 20-fold excess. These attributes are characteristic of specific steroid receptor proteins. Binding of testosterone within the cytosol fraction is of moderate affinity (Kd = 9.0 - 23.0 nM) and high capacity (Nmax = 0.5 - 2.9 pmol mg-1 protein) and binding of testosterone is more readily displaced by a number of steroid competitors than is the case for the membrane site. The rate of association and dissociation of testosterone from the cytosolic binding site is markedly more rapid than the equivalent processes in the membrane fraction. Binding of testosterone to the nuclear extract is of high affinity (Kd ~ 3.0 nM) and limited capacity (Nmax ~ 50 fmol mg-1 protein). There are no marked differences between species or between sexes in the affinity or capacity of testosterone-binding sites in nuclear extract or membrane fraction. However, cytosolic testosterone-binding sites are three- to four-fold more abundant in rainbow trout than in brown trout, and female rainbow trout have more cytosolic binding sites than male rainbow trout, but a lower affinity for testosterone than male sites. Preliminary evidence supports the involvement of the membrane-associated testosterone-binding site in olfactory processes. Rainbow trout display an EOG response to testosterone at a concentration (10-9 M) which is consistent with the equilibrium dissociation constant (Kd) of the membrane-associated testosterone-binding site. The concentration of ligand at which half the binding sites are saturated (Kd) is in the range 0.5 - 2.0 . 10-9 M for membrane-associated testosterone binding. Binding of 3H-testosterone to the membrane-associated site shows a pH dependency which is comparable to the effects of pH on the EOG response to testosterone in intact fish. The data concerning the attributes of the membrane associated testosterone-binding site are consistent with the olfactory tissue of salmonids possessing the capability to respond to testosterone present in the aquatic environment. The intracellular testosterone-binding sites show characteristics common to testosterone receptors in other fish tissues which are known androgen target tissues. This suggests that the development and/or function of salmonid olfactory tissue may be open to influence by endogenous testosterone. This is the first report of androgen binding to olfactory tissue in fish, and the first report of a membrane-associated androgen binding site in fish

Models of extended hadrons

Imperial Users onl

Investigation of steady state characteristics of hollow cathode internal plasmas using optical emission spectroscopy

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Medical Disinformation: Niche-market Targeting in the Black Press during the AIDS Epidemic

This paper analyzes the distribution of information about AIDS by the Black press from 1983 to 1990. The information in articles published by Amsterdam News, a historically black newspaper, evolves as experts release accurate AIDS information during the same period. The conspiracy theories and false claims attributing AIDS to other populations shown in earlier Amsterdam News publications are corrected over time by helpful, truthful information released by doctors, as shown in later articles. My analysis of this trend relies on theories of niche-market targeting and definitions of mis- and disinformation to create a historical case study of the relationship between disinformation about medical conditions in the Black community and the role of the medical community in addressing that disinformation.https://orb.binghamton.edu/research_days_posters_2023/1075/thumbnail.jp