Laufer Hans

No Thumbnail Available
Last Name
Laufer
First Name
Hans
ORCID

Filters

2004 - 2009 2 2010 - 2012 2
4
4
Reset filters

Settings

Search Results

Now showing 1 - 4 of 4
  • Article
    Response of the American lobster to the stress of shell disease
    (National Shellfisheries Association, 2005-10) Laufer, Hans ; Demir, Neslihan ; Biggers, William J.
    Shell disease is a problem affecting lobsters in eastern Long Island Sound causing disfiguration of the shell, decreasing the lobsters' value, and whereas mild and medium levels of the disease are not lethal, ultimately, severe cases result in mortality. Levels of the molting hormone, ecdysone, were quantitated, using a radioimmunoassay (RIA), in hemolymph of animals exhibiting shell disease. Our results indicate that levels of ecdysone were increased in the hemolymph of shell-diseased lobsters, with a medium level of expression of the disease to 89 ± 32 ng/mL (n = 76), whereas unaffected, presumably healthy ones had 57 ± 16 ng/mL (n = 210). In 7 of 10 months of the year shell-diseased animals had higher ecdysone levels in their hemolymph than unaffected animals. In addition, ecdysone levels were abnormally high, 165 ± 53 ng/mL (n = 5), in shell-diseased ovigerous lobsters, whereas normal unaffected ovigerous ones had low levels of this hormone, 13 ± 4 ng/mL (n = 7). These results indicate that shell disease may induce lobsters to alter the systemic levels of ecdysone, possibly serving as a defensive measure, allowing the animals to ward off the effects of shell disease through induced molting.
  • Article
    Endocrine-disrupting alkylphenols are widespread in the blood of lobsters from southern New England and adjacent offshore areas
    (National Shellfisheries Association, 2012-06) Jacobs, Molly W. ; Laufer, Hans ; Stuart, James ; Chen, Ming ; Pan, Xuejun
    Endocrine-disrupting pollutants in rivers and oceans represent a poorly understood but potentially serious threat to the integrity of aquatic and coastal ecosystems. We surveyed the hemolymph of lobsters from across southern New England and adjacent offshore areas for 3 endocrine-disrupting alkylphenols. We found all 3 compounds in hemolymph from every year and almost every region sampled. Prevalence of contamination varied significantly between regions, ranging from 45% of lobsters from southern Massachusetts to 17% of lobsters from central Long Island Sound. Mean contamination levels varied significantly as a function of region, year sampled, and collection trip, and were highest overall in lobsters from western Long Island Sound and lowest in lobsters from central Long Island Sound. Surprisingly, lobsters from offshore areas were not less contaminated than lobsters from inshore areas. Contamination levels also did not vary as a function of lobster size or shell disease signs. Contaminated lobsters held in the laboratory did not retain alkylphenols, suggesting that hemolymph contamination levels represent recent, rather than long-term, exposure. Our data set is the first, to our knowledge, to survey endocrine-disrupting contaminants in a population across such a broad temporal and spatial scale. We show that alkylphenol contamination is a persistent, widespread, but environmentally heterogeneous problem in lobster populations in southern New England and adjacent offshore areas. Our work raises serious questions about the prevalence and accumulation of these endocrine-disrupting pollutants in an important fishery species.
  • Article
    The effect of alkylphenols on lobster shell hardening
    (National Shellfisheries Association, 2012-06) Laufer, Hans ; Chen, Ming ; Johnson, Michael ; Demir, Neslihan ; Bobbitt, James M.
    Alkylphenols, anthropogenic estrogenic endocrine disruptors in vertebrates, have been found in lobsters (Homarus americanus) in New England sites. We hypothesize that alkylphenols interfere in the shell hardening during molting. We used an in vitro cuticle bioassay to investigate the effects of 2 alkylphenolic compounds—2,4-bis-(dimethylbenzyl) phenol (compound 3) and bisphenol A (BPA; 4,4′-dihydroxy-2,2-diphenylpropane (also referred to as 4,4′-(propan-2-ylidene) diphenol)) on tyrosine incorporation during the hardening of new cuticle following lobster molting. During sclerotization, both alkylphenols and cold tyrosine competed with C14-tyrosine incorporation in a concentration-dependent manner. This process was also phenoloxidase dependent, as treatment with phenylthiourea (PTU; a phenoloxidase inhibitor) significantly decreased C14-tyrosine incorporation. We also found that incorporation of C14-2,4-bis-(dimethylbenzyl) phenol during the shell hardening process was inhibited by cold alkylphenol, cold tyrosine, or PTU, and competition was concentration dependent. Furthermore, incorporation of tyrosine and derivatives into new cuticle decreased with time after molting from 27% incorporation 1 day after a molt to 6% by 4 days after a molt. In nonmolting cuticles, there was no incorporation of alkylphenol or tyrosine derivatives. When lobsters were injected with 2,4-bis-(dimethylbenzyl) phenol during the premolt stage, it took the shells 12 ± 1 days to harden sufficiently to resist deflection by 5 lb pressure exerted by a pressure gauge, compared with 7 ± 1 days for control shells. Thus, shell hardening is delayed significantly by the presence of 2,4-bis-(dimethylbenzyl) phenol. The effects of this compound on shell hardening may result in lobsters' susceptibility to microbial invasion and, therefore, may contribute to the onset of shell disease.
  • Article
    Identification of juvenile hormone-active alkylphenols in the lobster Homarus americanus and in marine sediments
    (Marine Biological Laboratory, 2004-02) Biggers, William J. ; Laufer, Hans
    We have identified, by gas chromatography/mass spectrometry, four alkylphenols that are present in the hemolymph and tissues of the American lobster Homarus americanus and in marine sediments. These alkylphenols are used industrially in antioxidant formulations for plastic and rubber polymer manufacturing, and are similar in structure to a known endocrine disruptor, bisphenol A. The compound 2-t-butyl-4-(dimethylbenzyl)phenol was present at concentrations of 0.02 to 1.15 µg/ml in hemolymph and 8.95 to 21.58 µg/g in sediments. A second compound, 2,4-bis-(dimethylbenzyl)phenol, was present at concentrations between 0.07 and 19.78 µg/ml in hemolymph and 138.94 to 224.89 µg/g in sediment, while a third compound, 2,6-bis-(t-butyl)-4-(dimethylbenzyl)phenol, was found at concentrations between 0.01 and 13.00 µg/ml in hemolymph, 2.55 and 6.11 µg/g in hepatopancreas, and 47.85 and 74.66 µg/g in sediment. A fourth compound, 2,4-bis-(dimethylbenzyl)-6-t-butylphenol, was found at concentrations of 0.20 to 70.71 µg/ml in hemolymph, 23.56 to 26.89 µg/g in hepatopancreas, and 90.68 to 125.58 µg/g in sediment. These compounds, along with bisphenol A, 4-dimethylbenzylphenol, and nonylphenol, display high juvenile hormone activity in bioassays. Alkylphenols at high concentrations are toxic to crustaceans and may contribute significantly to lobster mortality; at lower concentrations, they are likely to have endocrine-disrupting effects.