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Biomedical subjects

M Fingerman

Publications and source records attributed to M Fingerman.

At least 19 recordsLinked to original sources
PubMed2000

Inhibition of ovarian growth by cadmium in the fiddler crab, Uca pugilator (Decapoda, ocypodidae).

The effect of cadmium chloride (1 mg/L) on oocyte growth of the fiddler crab, Uca pugilator, was studied during the slow vitellogenesis phase of ovarian maturation of this carb. In vivo experiments were done with both intact and eyestalkless crabs. The intact cadmium-exposed crabs exhibited a significantly lower oocyte diameter than the controls at the end of the 2-week exposure period, but no significant differences were detected among the eyestalkless crabs, suggesting that the effect of cadmium could be on the sinus gland in the eyestalks, increasing secretion of the gonad-inhibiting hormone (GIH). To test this hypothesis, in vitro experiments were done, incubating pieces of ovary with and without eyestalk tissue, in the presence of thoracic ganglion, needed for oocyte growing due to the secretion of the gonad-stimulating hormone (GSH). Only when eyestalk tissue was present in the incubation media was oocyte growth inhibited by cadmium compared to the controls. These results strongly suggest that cadmium acts at least in part to increase the secretion of GIH from the sinus gland. GIH could then in turn act by (a) inhibiting secretion of GSH by the thoracic ganglion, (b) directly inhibit the oocytes, or (c) both (a) and (b).

Animals↗
PubMed1999

Effects of estrogenic agents on chitobiase activity in the epidermis and hepatopancreas of the fiddler crab, Uca pugilator.

The effects of exposure of the fiddler crab, Uca pugilator, to the estrogenic xenobiotics Aroclor 1242, diethylstilbestrol (DES), endosulfan, and 4-octylphenol on chitobiase activity in the epidermis and hepatopancreas were investigated. Endosulfan at 0.05 and 0.20 mg/liter significantly inhibited chitobiase in the epidermal and hepatopancreatic tissues of U. pugilator exposed for 3 days. After a 7-day exposure there was a significant decrease in epidermal chitobiase activity in the animals exposed to Aroclor 1242 at 8.0 mg/liter, DES at 5.0 mg/liter, and endosulfan at 0.05 and 0. 20 mg/liter, while Aroclor 1242 at 2.0 and 8.0 mg/liter and endosulfan at 0.05 and 0.20 mg/liter significantly inhibited chitobiase activity in the hepatopancreas. 4-Octylphenol at 2.0 and 10.0 mg/liter had no significant effect on epidermal chitobiase activity, while 7 days of exposure to 10.0 mg/liter 4-octylphenol significantly inhibited hepatopancreatic chitobiase activity. Because chitobiase is necessary for the partial digestion of the chitinous exoskeleton as part of the molting process, inhibition of this enzyme by these estrogenic agents can account for at least some of the slowing of molting that occurs when crustaceans are exposed to these agents. Possible mechanisms regarding the decline of chitobiase activity in the presence of estrogenic agents are presented.

Acetylglucosaminidase↗
PubMed1999

Effects of exposure to diethyl phthalate, 4-(tert)-octylphenol, and 2,4,5-trichlorobiphenyl on activity of chitobiase in the epidermis and hepatopancreas of the fiddler crab, Uca pugilator.

Seven-day exposure of fiddler crabs, Uca pugilator, to diethyl phthalate at 50.0 mg l-1 significantly inhibited the activity of chitobiase (also known as N-acetyl-beta-glucosaminidase) in the epidermis and hepatopancreas. Epidermal chitobiase activity of crabs exposed to 10.0 mg l-1 4-(tert)-octylphenol for 7 days significantly decreased. PCB29 at 0.5 and 2.0 mg l-1 significantly inhibited chitobiase activity in the epidermis and hepatopancreas of crabs exposed for 3 days. The inhibitory effects rendered by diethyl phthalate and PCB29 can at least partly account for the delayed molting they cause because chitobiase is needed to break down the old exoskeleton of crustaceans prior to ecdysis. Since chitinolytic enzymes are apparently the products of ecdysteroid regulated genes in arthropods, the decline in chitobiase activity after exposure to diethyl phthalate, 4-(tert)-octylphenol, and PCB29 along with the delayed molting they cause strongly suggests that these xenobiotics disturb the Y-organ-ecdysteroid receptor axis. Such disturbance may involve an interaction between ecdysteroid receptors and steroid mimics where the steroid mimics act as antagonists of endogenous steroid molting hormones, and/or arise from the interference with synthesis and excretion of ecdysteroids by these compounds.

Acetylglucosaminidase↗
PubMed1999

Patterns of N-acetyl-beta-glucosaminidase isoenzymes in the epidermis and hepatopancreas and induction of N-acetyl-beta-glucosaminidase activity by 20-hydroxyecdysone in the fiddler crab, Uca pugilator.

A new staining method for detection of N-acetyl-beta-glucosaminidase on denaturing SDS polyacrylamide gels was developed. The isoenzyme pattern of N-acetyl-beta-glucosaminidase in the epidermis of the fiddler crab, Uca pugilator, is different from that in the hepatopancreas. Two isoforms of N-acetyl-beta-glucosaminidase, with molecular weights of 89 and 45.6 kDa, are present in the hepatopancreas while there is only one form of N-acetyl-beta-glucosaminidase, 89 kDa, in the epidermis. No sexual dimorphism was found in these patterns of N-acetyl-beta-glucosaminidase isoenzymes. The characteristic isoenzyme patterns in the epidermis and hepatopancreas occurred consistently throughout the molting cycle. Injections of the molting hormone, 20-hydroxyecdysone, at 25 microg/g live weight, into crabs in premolt substage D1, significantly increased N-acetyl-beta-glucosaminidase activity in the epidermis by 86%. Since only one form of N-acetyl-beta-glucosaminidase, 89 kDa, is present in the epidermis, the elevation in epidermal enzymatic activity after 20-hydroxyecdysone administration is entirely accounted for by this N-acetyl-beta-glucosaminidase isoenzyme. The results reported herein are the first direct evidence that in a crustacean N-acetyl-beta-glucosaminidase activity is regulated by the steroid molting hormone.

Acetylglucosaminidase↗
PubMed1998

Hormonally-regulated functions in crustaceans as biomarkers of environmental pollution.

The effects of organic and inorganic contaminants on functions regulated by hormones in crustaceans are being investigated with increasing frequency because several of these phenomena show promise of being useful biomarkers of environmental contamination. Heavy metals and organic compounds have been found in studies with crustaceans to negatively affect hormonally-regulated functions, specifically reproduction, molting, blood glucose level, and pigmentary effectors. Neurotransmitters, including 5-hydroxytryptamine and dopamine, have been identified as being involved in stimulating or inhibiting release of specific crustacean neurohormones such as the pigment-dispersing and pigment-concentrating ones involved in color changes. The effects of pollutants on at least some of these hormonally-regulated processes appear due at least in part to impacting release of a neurohormone, possibly by affecting release of the neurotransmitter that normally stimulates release of that particular neurohormone.

Animals↗
PubMed1997

Effects of cadmium and mercury on ovarian maturation in the red swamp crayfish, Procambarus clarkii.

In vivo mercury significantly inhibited ovarian maturation in the red swamp crayfish, Procambarus clarkii. 5-Hydroxytryptamine (5-HT) induced ovarian maturation in vivo. Cadmium and mercury inhibited this 5-HT-induced maturation. Ovarian explants incubated with mercury and either brain or muscle demonstrated significant inhibition of [14C]leucine incorporation into ovarian proteins compared to the corresponding groups incubated without mercury. In the absence of mercury the brain, which contains a gonad-stimulating hormone (GSH), induced significantly more incorporation of this amino acid than occurred in the ovaries incubated with muscle. These metals may have exerted their inhibitory effects by directly inhibiting protein synthesis in the ovaries, inhibiting 5-HT-stimulated GSH release, and preventing the ovaries from responding to this hormone.

Animals↗
PubMed1997

Metal accumulation in crayfish, Procambarus clarkii, exposed to a petroleum-contaminated Bayou in Louisiana.

Red swamp crayfish (Procambarus clarkii) were placed for a period of 7 days in Bayou Trepagnier, a Louisiana waterway which received petroleum-laden effluents from a manufacturing complex several decades ago. However, coolant water from the plant continued to be released into the bayou until 1995. Analyses of sediments at the exposure site revealed heavy contamination by lead, chromium, and copper, while concentrations of arsenic and cadmium were very low. Significant bioaccumulation of lead was observed in the hepatopancreas and gills of 7-day-exposed crayfish, whereas chromium accumulated the most in the gills and blood. Concentrations of copper in the crayfish did not change during the course of the study, suggesting that this essential metal constituent of the respiratory pigment is successfully regulated even when crayfish are exposed to relatively high levels of copper in the sediments. There was no metal accumulation in the abdominal muscle of the crayfish. That damage to the hepatopancreas occurred during the exposure is suggested by histopathological studies which revealed swollen and vacuolated R cells and an increase in the pH of the digestive juices. Blood glucose levels, as well as ovarian and hepatopancreatic indices, were unchanged. This study demonstrates that accumulation of nonessential metals in crayfish tissues in a wetland environment contaminated by mixed pollution (metals and hydrocarbons) reflects the concentrations of metals in the sediment.

Animals↗
PubMed1997

Effects of estrogenic xenobiotics on molting of the water flea, Daphnia magna.

The effects of five xenobiotics, 2,4,5-trichloribiphenyl (PCB29), the polychlorinated biphenyl (PCB) Aroclor 1242, diethyl phthalate, lindane, and 4-octylphenol, on molting of Daphnia magna were investigated. All except PCB29 are known to have unexpected estrogenicity in vertebrates. Daphnids exposed to PCB29, Aroclor 1242, and diethyl phthalate took significantly more time to complete four molts than did the controls. The inhibitory effects of these ortho-chlorinated PCBs suggest that certain structural features, most probably including ortho-chlorination, are related to the ability of a PCB to affect molting. Agents with multicyclic structures, such as PCBs, are more effective in inhibiting molting than are single-ringed xenobiotics, such as diethyl phthalate, which suggests that hydrophobicity may be a requirement for binding to the ecdysteroid receptor. These molt-inhibiting agents with multiple rings appear to bear more structural resemblance to the steroidal molting hormones of arthropods, the ecdysteroids, than do the single-ringed ones. While the possibility of alternative mechanisms, such as impairment of ecdysteroidogenesis exists, the results obtained herein support the hypothesis that some xenobiotics which disrupt endocrine processes in vertebrates can also interfere with the hormonally regulated molting process in arthropods through acting as antagonists of endogenous ecdysteroids by binding to and thereby blocking the ecdysteroid receptor.

Animals↗
PubMed1996

Accumulation and physiological and biochemical effects of cadmium in a simple aquatic food chain.

The toxicity of cadmium with regard to the vegetative reproduction of duckweed, Lemna gibba, grown in sterile culture, was determined. The EC50 was found to be 800 ppb. Duckweed grown in 2.24 ppm cadmium (supplied as cadmium nitrate) for 7 days accumulated 98.5% of the available cadmium from the growth medium. Plants that had been grown for 7 days in 2.24 ppm cadmium and control plants were fed to red swamp crayfish, Procambarus clarkii, for 14 days. The concentrations of cadmium were measured in hepatopancreata and muscles of crayfish on Day 0 and in crayfish fed duckweed grown in cadmium for 14 days. Accumulation of this metal in hepatopancreata increased 26-fold, i.e., 176.80 ppb on Day 0 to 4657.56 ppb on Day 14, and in muscles almost 7-fold, i.e., 6.75 ppb on Day 0 to 46.28 ppb on Day 14. Crayfish fed cadmium-containing duckweed demonstrated inhibition (55% after 14 days of feeding) of acetylcholinesterase activity in their central nervous tissue compared to crayfish fed cadmium-free duckweed. The ovarian index and total lipids content in the ovaries of crayfish fed cadmium-containing duckweed demonstrated significant increases on Day 14.

Animals↗
PubMed1996

In vivo assessment of opioid agonists and antagonists on ovarian maturation in the red swamp crayfish, Procambarus clarkii.

The possible involvement of an endogenous opioid system in the regulation of ovarian development in the red swamp crayfish, Procambarus clarkii, was investigated in vivo. Injections of the opioid, methionine (Met) enkephalin, into females significantly slowed ovarian maturation in a dose-dependent manner. In contrast, injection of the general opioid antagonist, naloxone, produced dose-dependent ovarian maturation. Furthermore, the highly selective delta opioid agonist, DADLE, also inhibited ovarian maturation, whereas a highly selective delta receptor antagonist, ICI-174,864, stimulated ovarian maturation. In view of these results and the fact that Met-enkephalin is a relatively selective delta receptor agonist, we hypothesize that in the crayfish the inhibitory effect of Met-enkephalin involves this type of binding site. Furthermore, it is hypothesized that the inhibitory action of these opioids is due to either (a) stimulation of release of the gonad-inhibiting hormone, (b) inhibition of release of the gonad-stimulating hormone or (c) both (a) and (b).

Animals↗
PubMed1995

Effect of cadmium chloride on physiological color changes of the fiddler crab, Uca pugilator.

The effects of cadmium exposure on the color change system of the fiddler crab, Uca pugilator, were determined. Crabs were either immersed in 10 ppm cadmium chloride solutions or injected with 8.5 micrograms cadmium/g body weight. The crabs exposed to cadmium, either by injection or immersion, were less able to bring about dispersion of the pigment in their integumentary melanophores than were the unexposed crabs. Cadmium did not affect the melanophores directly. This decreased black pigment dispersion was apparently due to effects of cadmium on the neuroendocrine processes that control the melanophores. The neuroendocrine complex in the eyestalk is the source of a black pigment-dispersing hormone (BPDH). Eyestalks of crabs kept in clean water contained 3.27 times more BPDH than did the eyestalks of the cadmium-exposed crabs. Histological studies revealed that cadmium exposure results in depletion of the neurosecretory material in the eyestalks and brain. It is hypothesized that cadmium inhibits BPDH synthesis in neurosecretory (neuroendocrine) cells, resulting in decreased ability of exposed crabs to disperse their black pigment.

Animals↗
PubMed1995

Naphthalene-induced atresia in the ovary of the crayfish, Procambarus clarkii.

Female crayfish, Procambarus clarkii, were exposed to 10 ppm naphthalene to determine its effect on ovarian development. Ovaries were removed for examination after 1, 2, 4, 6, 8, 10, 12, and 15 days of exposure to the naphthalene. Crayfish that had been exposed to naphthalene for 15 days were then returned to clean freshwater for 1, 2, 4, 5, 7, 10, and 15 days to determine whether the ovaries would recover from the naphthalene exposure. The ovarian index, which reflects the weight of the ovary, decreased gradually over the 15-day naphthalene exposure period. The previtellogenic and vitellogenic oocytes degenerated. Intense atresia along with yolk resorption led to this decrease in the ovarian index. In contrast, the ovaries of the control crayfish developed into ripe gonads. However, immature oocytes reappeared in the ovaries of the crayfish subjected to depuration, which suggests that the ovary of P. clarkii can recover from naphthalene-induced atresia.

Animals↗
PubMed1995

Dopaminergic and enkephalinergic involvement in the regulation of blood glucose in the red swamp crayfish, Procambarus clarkii.

In in vivo experiments injection of dopamine (DA) or leucine enkephalin (L-Enk) produced hypoglycemia in intact red swamp crayfish, Procambarus clarkii. In contrast, neither compound had a significant effect on the circulating glucose concentration in eyestalkless individuals. With intact crayfish spiperone, a DA receptor blocker, inhibited this hypoglycemic action of DA but not this action of L-Enk. In contrast, in intact crayfish naloxone, a competitive opioid antagonist, inhibited the in vivo hypoglycemic actions of both L-Enk and DA. In vitro, both DA and L-Enk reduced the rate of release of the crustacean hyperglycemic hormone (CHH) from isolated eyestalk neuroendocrine tissue. These results suggest that both DA and L-Enk act to inhibit release of CHH by affecting the eyestalk neuroendocrine complex and that the enkephalinergic inhibitory neuron follows the dopaminergic inhibitory neuron in the chain of neurons which leads to the neuroendocrine cells that secrete CHH.

Animals↗
PubMed1995

A neurotransmitter role for red-pigment-concentrating hormone in ovarian maturation in the red swamp crayfish Procambarus clarkii

The influence of red-pigment-concentrating hormone (RPCH) on ovarian maturation in the red swamp crayfish Procambarus clarkii was studied using both in vivo and in vitro techniques. In vivo, RPCH stimulated ovarian maturation. However, RPCH did not affect the ovary in vitro when only RPCH, muscle and ovarian explants were used. But when RPCH, thoracic ganglia, which are known to contain gonad-stimulating hormone-like (GSH-like) activity, and ovarian explants were incubated together, significant ovarian maturation ensued. The calcium ionophore A23187 mimicked RPCH both in vivo and in vitro. These results provide evidence to support the hypothesis that RPCH has a role as a neurotransmitter in Procambarus clarkii to stimulate GSH release, with calcium acting as a second messenger for RPCH.

Journal Article↗