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Biomedical subjects

K Dabrowski

Publications and source records attributed to K Dabrowski.

At least 19 recordsLinked to original sources
PubMed2006

Indispensable amino acid concentrations decrease in tissues of stomachless fish, common carp in response to free amino acid- or peptide-based diets.

The premise that free amino acid or dipeptide based diets will resolve the nutritional inadequacy of formulated feeds for larval and juvenile fish and improve utilization of nitrogen in comparison to protein-based diets was tested in stomachless fish, common carp (Cyprinus carpio L.) larvae. We examined the postprandial whole body free amino acid (FAA) pool in fish that were offered a FAA mixture based diet for the duration of 2 or 4 weeks. We found that the total amount and all indispensable amino acids concentrations in the whole body decreased after a meal. We then fed juvenile carp with dietary amino acids provided in the FAA, dipeptide (PP), or protein (live feed organisms; brine shrimp Artemia salina nauplii, AS) forms. Histidine concentrations in the whole fish body increased in all dietary groups after feeding whereas all other indispensable amino acids decreased in FAA and PP groups in comparison to the AS group. Taurine appears to be the major osmotic pressure balancing free amino acid in larval freshwater fish which may indicate a conditional requirement. We present the first evidence in larval fish that in response to synthetic FAA and PP diets, the whole body indispensable free AA concentrations decreased after feeding. This study shows that amino acids given entirely as FAA or PP cannot sustain stomachless larval fish growth, and may result in depletion of body indispensable AA and most of dispensable AA. The understanding of these responses will determine necessary changes in diet formulations that prevent accelerated excretion of amino acids without protein synthesis.

Amino Acids↗
PubMed2004

Effect of diets containing gossypol on blood parameters and spleen structure in tilapia, Oreochromis sp., reared in a recirculating system.

The high cost of fish meal in tilapia diets warrants the potential use of cottonseed meal (CSM) as an alternative source of high quality protein. The effects of varying levels of CSM (0, 25, 50, 75 and 100%) as fish meal protein replacement on growth, blood parameters, spleen characteristics, free and bound gossypol in blood plasma, haemoglobin and haematocrit were determined in tilapia. Gossypol (C(30)H(30)O(8)) is a polyphenolic substance found in cottonseed that has known toxic effects in fish. Tilapias (n = 219, average weight = 11.3 +/- 3.9 g) were randomly distributed into 15, 32-L glass aquaria, representing five dietary treatments and three replicates per treatment. Each aquarium containing 13-16 fish was supplied with thermoregulated, recirculating water (27 +/- 1 degrees C) at 1 L min(-1) flow rate and photoperiod was constant (12 h L/12 h D). Fish fed 25-50% CSM protein replacement showed similar body weights and total lengths as the controls at the completion of the 16-week trial. Fish fed 75 and 100% CSM protein replacement showed a significant decline in body weight and total length. Fish fed 25-100% CSM protein replacement had significantly lower haematocrit and haemoglobin (ANOVA/LSD, P < 0.05) compared with levels in controls. The decline was most prominent in groups fed diets with 50-100% CSM protein replacement. Total and free gossypol concentrations of blood plasma significantly increased with increasing levels of CSM replacement (P < 0.05). No gossypol was found in blood plasma of fish from the control group. The occurrence of immature and abnormal erythrocytes was significantly greater among fish fed 75 and 100% CSM diets compared with fish fed 0-50% CSM diets. Spleen-somatic index (spleen weight/body weight x 100) did not differ between control fish and fish fed 50-100% CSM diets. Spleen abnormalities, such as large depositions of haemosiderin and melanin pigments and proliferation of melano-macrophage centres, lymphocytic depletion of the white pulp areas (hypocellularity), and presence of vacuoles and necrotic areas were observed among fish fed 50-100% CSM protein diets. In general, the pathological effects of gossypol in tilapia (low haemoglobin and haematocrit levels, abundance of immature red blood cells or polychromatocytes, abnormal spleen morphology) were similar to the effects of vitamin E and/or vitamin C deficiencies observed in other studies.

Analysis of Variance↗
PubMed2004

Developmental aspects and factors influencing the synthesis and status of ascorbic Acid in the pig.

Ascorbic acid synthesis in the pig occurs at mid-pregnancy, but activity of the enzyme l-gulono-gamma-lactone oxidase (GLO) declines thereafter during gestation and remains low when the pig nurses the sow. During late gestation the ascorbic acid concentration in the fetus increases, but serum and liver ascorbic acid concentration in the sow declines without affecting the dam's liver GLO activity. It is presumed that as gestation progresses an increased amount of maternal ascorbic acid is transferred to the fetus and to the mammary gland. Colostrum and milk are rich sources of the vitamin and supply the nursing pig with ascorbic acid. The available data suggest that high amounts of ascorbic acid appear to suppress liver GLO activity in the pig. Upon weaning, when exogenous vitamin C is generally not provided, liver GLO activity and serum ascorbic acid increases. During the initial periods postweaning, some reports have indicated growth benefits of supplemental vitamin C. Body tissues differ in their concentrations of ascorbic acid, but tissues of high metabolic need generally have greater concentrations. The corpus luteum in the female, the testis in the male, and the adrenal glands in all pigs contain greater concentrations of the vitamin. Knockout genes preventing ascorbic acid synthesis in pigs have demonstrated poor skeletal and collagen formation and poor antioxidant protection. Under periods of stress ascorbic acid declines in the adrenal, but the pig rapidly recovers to its resting state once the stressor agent is removed. Although there are periods when supplemental vitamin C has been shown to promote pig performance (e.g., during high environmental stress and early postweaning), supplemental vitamin C has not been shown to routinely enhance pig performance.

Animals↗
PubMed2003

The effect of fasting, prolonged swimming, and predator presence on energy utilization and stress in juvenile walleye (Stizostedion vitreum).

We evaluated how two diets with different lipid levels (4% vs. 10%) influenced nutrient expenditure in juvenile walleye Stizostedion vitreum subjected to starvation, prolonged swimming, and predator presence. We also determined how exercise and predator presence influenced stress indicators such as blood plasma cortisol and glucose. Groups of six fish were placed in triplicate rectangular wire cages per treatment and submerged randomly in three artificial stream compartments at a water temperature of 14 degrees C. Three treatments were established: (A) no water current and no predator, (B) water current (1.5 body lengths s(-1)) and no predator, (C) water current and predator. Six 1-year-old muskellunge (Esox masquinongy, 28.4+/-2.3 cm) were used as predators. They were allowed to swim freely outside walleye cages and were fed with walleye. To simulate poststocking period of fasting, walleyes were exposed to experimental treatments for 6 weeks and were deprived of food. Regardless of the prior diet, fish weight significantly declined in all treatments but no differences were found among them. Lipids declined in both dietary groups of fish; in turn, body moisture increased. Protein levels were only affected in fish fed with high-lipid diet prior to the experiment and subjected to current and predator presence. Plasma glucose gradually declined in fish fed with high-lipid diet prior to the study; whereas in the fish fed with low-lipid diet before the experiment, it remained low regardless of the treatment severity. Plasma cortisol concentrations never exceeded 30 ng ml(-1) indicating no signs of acute stress during the experiment. We concluded that fish fed with diet containing higher lipid levels prior to stocking would possess better potential of withstanding adverse conditions and better survival once released to the wild.

Animal Feed↗
PubMed2002

A mixture of cottonseed meal, soybean meal and animal byproduct mixture as a fish meal substitute: growth and tissue gossypol enantiomer in juvenile rainbow trout (Oncorhynchus mykiss).

Diets incorporating three different sources of extracted cottonseed meal (CM), soybean meal and an animal protein mixture were evaluated for juvenile rainbow trout. Fish averaging 0.96 g were divided into groups of 30; 3 groups per treatment, and each group was fed one of four diets for a 16-week period. Fish meal (FM) was replaced on a 25% protein basis by each of three different sources of CM from California (CA), Tennessee (TN), and Arkansas (AR), U.S.A. In the three CM-containing diets another 25% soybean meal protein and 50% animal protein mixture were also incorporated to completely replace FM protein. The results of growth rate and feed utilization showed that FM could be entirely replaced by a mixture of plant proteins (CM and soybean meal) and animal by-product proteins. Hematocrit levels were significantly lower in the group fed CM-containing diets than in the control. The findings suggest that CM can be used as a good protein source by the incorporation of at least 15% in diets (25% of fish meal protein replacement), and that the nutritive values of CM in juvenile trout can be different due to their different origin. Significantly higher concentrations of total gossypol were found in faeces of CM-TN (5.8 +/- 0.4 micromol/g) and CM-AR (5.6 +/- 0.6) groups than in that of CM-CA (3.7 +/- 0.4) group. It was documented that gossypol enantiomers, present in an equal proportion in diets, selectively accumulated in liver and bile, whereas equal proportions of (+)- and (-)-enantiomers were found in whole-body and faeces. Depending on CM source, fish can absorb approximately 35-50% of dietary gossypol, and the majority of the absorbed gossypol seemed to be excreted.

Animal Feed↗
PubMed2001

Gossypol isomers bind specifically to blood plasma proteins and spermatozoa of rainbow trout fed diets containing cottonseed meal.

We investigated the role of gossypol isomers binding to blood plasma, seminal plasma and spermatozoa to elucidate gossypol anti-fertility action in the teleost fish, rainbow trout (Oncorhynchus mykiss). Growth and hematological indicators of males were depressed when fish meal protein in diets was completely replaced with cottonseed meal. The cottonseed meal contained equal proportions of (-) (47.8+/-1.6%) and (+) gossypol isomers. Concentrations of spermatozoa were decreased with increasing proportions of gossypol in diets (from 0.22% to 0.95%); however, sperm motility and fertilizing ability were not affected. In contrast to mammals, steroid hormone concentrations were not suppressed in fish given diets with gradual increase of gossypol level. Gossypol concentrations were 100-fold higher in blood plasma than in seminal plasma, confirming a barrier in gossypol transfer between the general circulation and the testis. Spermatozoa accumulated predominantly (+) enantiomer (65-75%) with decreasing proportions as dietary gossypol concentrations increased. Spermatozoa bound most of the gossypol contained in the semen; however, this did not result in impairment of the sperm motility apparatus. Teleost fish sperm rely on ATP stores that accumulate during maturation as a source of energy during activation. In addition, the duration of sperm movement is short in these fish. As such, we hypothesize that the major action of gossypol on mammalian sperm, which is uncoupling of oxidative phosphorylation, does not impair the energy supply required for flagellar beating in fish spermatozoa.

Animals↗
PubMed2001

Sex steroids in plasma of lake whitefish Coregonus clupeaformis during spawning in Lake Erie.

Lake whitefish, Coregonus clupeaformis, were collected from the Western basin of Lake Erie during spawning. Free and conjugated (sulfated and glucuronidated) steroids including testosterone (T), 11-ketotestosterone (11-kT), estradiol-17beta (E2) and 17,20beta-dihydroxy-4-pregnen-3-one (17,20betaP) were measured in the plasma by radioimmunoassay. In males, the progression of spermiation was characterized by a significant decrease in plasma free steroids, whereas the levels of conjugated steroids remained similar and low, except for sulfated and glucuronidated testosterone. Plasma sex steroids did not correlate with the density or the motility of the spermatozoa. In females, the concentration of plasma T was significantly higher in preovulating than in ovulating females. The levels of E2 and 17,20betaP in ovulating lake whitefish exhibited large variations ranging from below detection limit to 0.9 ng ml(-1) and from 0.2 to 13 ng ml(-1), respectively. Analysis of conjugated steroids revealed high levels of glucuronidated and sulfated 17,20betaP and glucuronidated T in females ovulating in December. However, no significant differences in the proportion of the conjugated steroids were observed.

Animals↗
PubMed2001

Ascorbic acid synthesis in fetal and neonatal pigs and in pregnant and postpartum sows.

The ontogeny of ascorbic acid synthesis and its concentration in fetal pigs from mid- to late gestation, and the effect of birth order and premature or normal delivery ages were evaluated. In Experiment 1, fetal pigs were collected from three sows at 60, 80, 100, 107 and 111 d of development. Liver L-gulono-gamma-lactone oxidase (GLO) activity and ascorbic acid concentration were measured. High liver GLO activity in fetal liver occurred at 60 d but declined as pregnancy advanced (P < 0.01), whereas ascorbic acid concentration increased (P < 0.01). Experiment 2 evaluated ascorbic acid synthesis and concentration in neonates born early (1st and 2nd) or late (7th and 8th) in the birthing sequence, or when born 2 d prematurely vs. the normal delivery age. Pigs born early in the birthing sequence (P < 0.01) and those born at the natural delivery age (P < 0.05) had higher liver ascorbic acid concentrations, but liver GLO activity did not differ among groups. Sows were killed at each period; liver GLO activity was constant during gestation but increased postpartum (P < 0.01). Liver ascorbic acid concentration was constant during gestation, except for a decline during late gestation, and increased postpartum (P < 0.05). These results suggest that more ascorbic acid was transferred from the dam to the fetuses as pregnancy advanced, possibly suppressing fetal GLO activity. Thus, fetal liver GLO activity was the primary source of ascorbic acid during early fetal development, but more fetal ascorbic acid was transferred from the dam during later pregnancy.

Animals↗
PubMed2001

Liver L-gulonolactone oxidase activity and tissue ascorbic acid concentrations in nursing pigs and the effect of various weaning ages.

In Experiment 1, we evaluated liver L-gulono-gamma-lactone oxidase (GLO) activity and tissue concentration of ascorbic acid in young pigs from birth to weaning (14 d) and through a 28-d postweaning period; in Experiment 2, we evaluated the effect of three weaning ages on these measurements. Sow colostrum and milk collected in both experiments demonstrated a linear decline (P < 0.01) in ascorbic acid concentration as lactation progressed. In Experiment 1, three pigs were killed at 0, 3, 7, 14, 21, 28, 35 and 42 d of age for determining liver GLO activity and serum and tissue ascorbic acid. Liver GLO activity decreased by 80% from 0 to 3 d of age and remained low until d 14 (weaning). After weaning, liver GLO activity increased linearly (P < 0.01). Tissue ascorbic acid concentrations decreased during the nursing period and again after weaning, but then increased to 42 d of age (P < 0.01). In Experiment 2, pigs were weaned at 10, 17 or 24 d of age. Three pigs from each group were killed at weaning and at each week postweaning until 38 d of age. Liver GLO activity was low during the nursing period but increased linearly (P < 0.01) for each group during the subsequent postweaning period. Pig serum and tissue ascorbic acid concentrations increased postweaning in each group. These results suggest that a factor in sow's milk, possibly ascorbic acid, suppressed liver GLO activity of nursing pigs but upon weaning, liver GLO activity of pigs increased in a linear manner (P < 0.01).

Age Factors↗
PubMed2001

Reproductive efficiency and maternal-offspring transfer of gossypol in rainbow trout (Oncorhynchus mykiss) fed diets containing cottonseed meal.

In a preceding study, complete substitution of fish meal protein with cottonseed meal (CM) protein did not affect the survival or growth rate of adult rainbow trout over a 6-mo period. Gossypol, a naturally occurring compound in cottonseeds, has an antifertility effect in terrestrial animals, but information regarding salmonid fish is lacking. Female rainbow trout in this experiment were fed diets with either 0, 25, 50, 75, or 100% (diets 1 to 5) of the fish meal protein replaced with CM protein until first maturation and spawning to study long-term effects on growth and reproduction. Feeding diets containing CM over a total period of 10 mo did not result in differences in growth and mortality compared to the control group (P > 0.05). Increased CM incorporation levels resulted in decreased (P < 0.05) blood hemoglobin (10.6 +/- 1.3, 8.4 +/- 1.8, 7.3 +/- 1.1, 6.9 +/- 0.8, and 5.6 +/- 1.4 g/dL) and hematocrit (49.6 +/- 3.9, 38.5 +/- 9.3, 34.4 +/- 3.7, 34.8 +/- 4.9 and 28.0 +/- 6.8%) levels in diets 1 to 5, respectively. The CM incorporation level had no effect (P > 0.05) on the number of eggs produced per female but led to a reduction (P < 0.05) in egg weight. Eyed stage survival of embryos was low in all dietary groups and did not show differences (P > 0.05). However, an increasing CM incorporation level led to a linear increase (P < 0.05) in the number of females that produced no viable embryos (23.1, 37.5, 42.9, 60.0, and 71.4%). Gossypol in the diet was absorbed by the female trout and transferred to the eggs (0, 2.2 +/- 0.5, 6.7 +/- 1.6, 10.6 +/- 4.2, and 20.0 +/- 2.6 micrograms/g in diets 1 to 5, respectively). A high concentration of gossypol remained in the juveniles at the swim-up stage (endogenous yolk-absorbed) (0.6 +/- 0.3, 2.4 +/- 0.3, 3.4 +/- 0.0, and 4.7 +/- 1.0 micrograms/g, diets 2 to 5, respectively). The findings suggest that replacement of the dietary fish meal protein with CM protein has no effect on fish growth and mortality but may lead to a reduction in reproductive performance in female rainbow trout.

Animals↗
PubMed2000

Induction of gynogenesis in muskellunge with irradiated sperm of yellow perch proves diploid muskellunge male homogamety.

Diploid gynogenesis was induced in muskellunge Esox masquinongy using UV-irradiated muskellunge sperm as the first step in producing monosex females. In this approach, we have to rely on negative controls as an indirect reference for sperm genetic material destruction. In the first experiment, equal proportions of gynogenetic females and males were produced. Negative controls, UV-irradiated sperm without heat shock, yielded some normal hatching larvae, described as spontaneous diploids. In the second experiment, muskellunge eggs were activated using sperm from yellow perch. Because hybrids between these species are not viable, we produced unambiguous gynogens. When UV-irradiated yellow perch sperm was used to inseminate muskellunge eggs, haploids resulted (22.5% +/- 2.8% survival to the eyed stage). To produce diploid gynogens, a heat shock of 31 degrees C was applied to inseminated eggs 20 min after activation for a duration of 6 min. This process yielded several hundreds of gynogens for rearing. Several treatments of masculinizing hormone, 17alpha-methyltestosterone (MT), were carried out. Fish were dissected and gonads examined histologically for sex determination. Gynogens produced using yellow-perch sperm confirmed the presence of males in the control group, whereas the MT bath treatment (400 microg/liter) resulted in the production of fish with ovotestis. These results provide evidence for male homogamety in muskellunge and imply that a change of strategy is needed to produce monosex populations.

Animals↗
PubMed2000

In vitro effect of gossypol acetate on yellow perch (Perca flavescens) spermatozoa.

Gossypol, a known antispermatogenic agent from the cotton plant genus Gossypium, was found to inhibit yellow perch sperm motility in vitro and lactate dehydrogenase activity in spermatozoa when used in a dose-dependent manner. This toxin also significantly decreased sperm fertilizing ability. Exposure of sperm suspension to a 200-µM concentration of gossypol caused sperm immobilization and a consequent lack of fertilization. Effects of gossypol on sperm motility and fertilizing ability were partially reversible when sperm suspensions were transferred to solutions without gossypol. This reversibility was proportional to the gossypol concentration. We observed a significant increase of abnormal embryos produced by the fertilization of spermatozoa pretreated with gossypol. This implies that gossypol could affect the sperm genome. The results indicate a usefulness for yellow perch sperm in studies of gossypol action mechanisms. Results of in vitro experiments suggest a potential for reproductive impairment in fish when using cottonseed-containing diets or organic fertilizers in yellow perch aquaculture. However, these observations should be confirmed in in vivo experiments with yellow perch and other species.

Journal Article↗
PubMed2000

Effects of gossypol on sperm viability and plasma sex steroid hormones in male sea lamprey, Petromyzon marinus.

Male sea lampreys Petromyzon marinus were injected with different doses of gossypol acetic acid in an attempt to sterilize them for use in a program for controlling the sea lampreys through the release of sterile males. Two lots of sea lamprey were used in these experiments. The first lot was divided into three groups and fish were injected intraperitoneally (i.p.) with 0.2 ml 50% ethanol as a control group or with gossypol suspended in ethanol at 100 and 200 mg/kg. The second lot was also divided into three groups and fish were either injected i.p. with vehicle as controls or gossypol at 25 and 50 mg/kg. Sperm weight, concentrations and motility were recorded after 31, 36 and 40 days or 24, 28 and 33 days in lots 1 and 2, respectively. Blood was collected from the caudal vessel prior to injections with gossypol and after 40 or 33 days in lots 1 and 2, respectively. Plasma levels of estradiol-17beta (E2), testosterone (T), progesterone (P) and 17,20beta-dihydroxy-4-pregnen-3-one (17,20betaP) were measured by radioimmunoassay. At the end of the experiment, the testis were removed and fixed in Bouin's solution for histological examination. High mortality was observed at the day of injection in the group treated with 200 mg/kg (84.6%), 100 mg/kg (41.7%), and 50 mg/kg (25%). Sperm concentrations were higher in control fish in comparison to most of the treated groups during the first sperm sampling (day 31 or 24), but then differences disappeared. At each sampling, sperm motility was higher in control groups than in treated groups and significant differences were observed (e.g. between control and 50 mg gossypol/kg). Fertility, evaluated at optimized sperm/egg ratio (5 x 10(4) sperm/egg) did not differ among treatments and controls. Changes in mean plasma sex steroid levels in the various treated groups were not significant, but a trend of decreasing plasma E2 was observed with increasing dose of gossypol. The structure of the testis was examined at the end of the experiment using light microscopy and appeared to be unchanged in gossypol-treated lampreys as compared to that of control animals. These findings suggest that gossypol injection into lamprey interferes with some of the reproductive parameters. Although high mortality rate precludes a single i.p. injection of gossypol as a favorable mode of chemosterilization in the lamprey, it would be useful to reassess the means of transfer of gossypol to reproductive tissues. This notion is further supported by the results of an in vitro sperm toxicity assay which revealed that gossypol, at a dose of 100 microM, has an antifertility action in this species.

Animals↗
PubMed2000

Characteristics of sperm acrosin-like activity of paddlefish (Polyodon spathula Walbaum).

Spermatozoa of paddlefish and sturgeon fishes (Acipenseriformes), unlike teleost fish, have an acrosome. The objectives of this study were to characterize acrosin-like activity of cryopreserved sperm of paddlefish (Polyodon spathula) and to test and compare stability of paddlefish acrosin-like activity with that of lake sturgeon and bull spermatozoa. Mean acrosin-like activity of cryopreserved paddlefish sperm was 0.372 +/- 0.067 microU/10(6) spermatozoa. This activity was 79% higher in the whole semen than in spermatozoa. Highest activity was recorded at pH 8.0 and 8.5. Triton X-100, zinc ions and 4'-acetamidophenyl 4-guanidinobenzoate (AGB) inhibited the activity. Amidase activity was also inhibited by N-alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK) and N-tosyl-L-phenylalanine chloromethyl ketone (TPCK). TLCK at concentrations of 0.1 and 1.0 mM gave a significant decrease in activity of 19 and 61%, respectively. However, TPCK significantly inhibited amidase activity (by 19%) only at concentration 1.0 mM. After acidification and 60 min incubation at 4 degrees C of sperm suspensions only 4% of the activity was retained. A similar phenomenon was observed in the case of lake sturgeon but not bull sperm. These results suggest that trypsin-like activity of Acipenserid fish resembles rather fish trypsin that mammalian one. In frozen-thawed paddlefish sperm a minute chymotrypsin-like activity was also indicated, when GPNA was used as substrate. This activity amounted to 0.0415 +/- 0.0138 microU/10(6) spermatozoa and was 18% of total amidase activity. This suggests that chymotrypsin-like activity may also be present in paddlefish spermatozoa.

Acrosin↗
PubMed2000

Effects of diets containing gossypol on reproductive capacity of rainbow trout (Oncorhynchus mykiss).

We evaluated five practical diets in which 0%, 25%, 50%, 75%, and 100% (dietary treatments 1-5) of fish meal protein was replaced by solvent-extracted cottonseed meal protein. Adult rainbow trout (initial average weight 247 +/- 8 g) were fed the diets over a period of 131 days during which a general 2-fold body weight increase occurred. The total diet gossypol concentration (free and protein-bound) showed a gradual increase with increased cottonseed meal substitution. Blood samples were collected on Days 0, 64, 112, and 131 for hematological and steroid hormone determination in plasma of males and females. Hemoglobin content was significantly reduced in fish from treatment 5 (7.9 +/- 0.3 g/dl) in comparison to treatments 1-3 (10.3-10.9 g/dl). After 112 and 131 days of feeding, testis weights, concentrations of testosterone, and 11-ketotestosterone were elevated in fish from dietary treatments 2 and 3 in comparison to control and diets 4 and 5. On Day 71, sperm were collected from 6 fish per dietary treatment to assess sperm quality. No significant differences in sperm concentrations (7.2-9.8 x 10(9)/ml), motility (78-89%), and standardized (300 x 10(5) sperm/egg) fertilizing ability (18.9-22.6% hatched embryos) were found. Total gossypol concentrations in blood plasma differed significantly among treatments, and the levels were among the highest ever recorded in animals fed cottonseed-supplemented diets (2.9 +/- 0.2, 11.7 +/- 4.1, 21.7 +/- 1.4, and 29.9 +/- 3.9 microg/ml, for treatments 2-5, respectively). The major portion of gossypol in blood plasma was protein-bound (81-93%). This was in contrast to minute amounts of gossypol present in seminal plasma, mostly in free form (0.02-0.18 microg/ml), which indicates the presence of a barrier between general circulation and the testis with respect to gossypol distribution in lower vertebrates. Thus, the reproductive parameters of male rainbow trout examined in this study were not significantly affected by feeding cottonseed meal for 131 days.

Animal Feed↗
PubMed1999

Uptake and depletion of plasma 17alpha-methyltestosterone during induction of masculinization in muskellunge, Esox masquinongy: effect on plasma steroids and sex reversal.

Oral administration of 17alpha-methyltestosterone (MT) was used to induce masculinization of sexually undifferentiated muskellunge, Esox masquinongy. Three groups of muskellunge (mean weight, 2.5 +/- 0.6 g) were submitted to MT treatment (15 mg of MT/kg) for 60 days. An additional one group was used as a control (hormone-free diet). Food was distributed over a 10-h period by using automatic belt feeders. Blood was sampled in both control and treated fish at different intervals during and after feeding: before (0 h), at 3 h, 6 h, and cessation of feeding (10 h), and after a fast of 22 h (32 h). MT had no significant effect on growth and survival in muskellunge 6 months after the treatment. Concentrations of plasma MT increased during the feeding period and reached their maximum levels 6 or 10 h after starting feeding. This rapid increase of MT indicated a rapid absorption of this steroid. Plasma MT levels then declined and reached a radir by 22 h after cessation of feeding, suggesting that MT is rapidly metabolized and excreted. The profiles of plasma testosterone during the MT treatment did not differ significantly between control and MT-treated groups. During and after the MT treatment, the concentration of plasma testosterone did not differ significantly between control and MT-treated groups. Moreover, no sexual dimorphism of testosterone levels was observed. Six months after treatment, the sex ratio in MT-treated groups (33% males, 62% females, and 5% intersex) was opposite to control (70% and 30%, respectively) and differed significantly. This suggests that at 15 mg of MT/kg over 60 days, a paradoxical feminization took place.

Animals↗