Effects of contrasting modes of larval development on the genetic structures of populations of three species of prosobranch gastropods

 In south-eastern Australia, the prosobranch gastropods Morula marginalba (Blainville), Cominella lineolata (Lamarck) and Bedeva hanleyi (Angas) have similar fine-scale distributions, but appear to possess very different dispersal capabilities due to contrasting modes of larval development. M.marginalba produce planktonic larvae, whereas C. lineolata and B. hanleyi undergo direct development in benthic egg capsules and emerge as crawling juveniles. To test for possible effects of contrasting life histories on levels of genetic variation within and among populations, a survey was conducted of allozyme variation at six polymorphic loci in 8 to 9 local populations of each species. Collections of snails were made between June 1992 and November 1993. Sampling ranges spanned between 162 and 180 km of coast. Regardless of larval type, proportions of single-locus genotypes in each collection were consistent with the recruitment of offspring which had been generated through random mating. However, genotypic diversity was lower in those species that undergo direct development. Loci surveyed in C. lineolata and B. hanleyi were polymorphic (i.e. frequency of most common allele <95%) in fewer populations than those examined for M.␣marginalba (P <0.001) and, where polymorphisms occurred, also possessed significantly fewer alleles (P <0.001). Consequently, average levels of expected heterozygosity were greater in populations of M. marginalba than in those of either of the other species (P <0.001). Genetic variation among populations, expressed as the standardised variance in allele frequencies (F _ST ), was inversely related to expected larval dispersal capability. The nine collections of M. marginalba showed little overall differentiation (F _ST  = 0.017; P <0.001), reflecting the ability of planktonic larvae to interconnect local populations, and so limit divergence due to drift and natural selection. In contrast, there were high levels of allelic heterogeneity among the nine collections of C. lineolata (F _ST  = 0.523; P <0.001) and eight collections of B. hanleyi (F _ST  = 0.140; P <0.001). These data imply that for species which undergo direct development, local populations are effectively closed and evolve largely independent of one another. Received: 3 May 1996 / Accepted: 12 July 1996     

Settlement-competency periods of larvae of three species of scleractinian corals

The pattern of settlement over time of three broadcast spawning coral species (Cyphastrea serailia, Acanthastrea lordhowensis, and Goniastrea australensis) from the Solitary Islands (30°00′S; 153°20′E) was studied in 1995 and 1996 in order to determine the maximum length of time these larvae could remain in the water column and still retain the ability to settle and metamorphose. Larvae were maintained in aquaria and the number which had settled on biologically-conditioned tile pairs was monitored every 5 to 10 d. While the majority of larvae settled quickly after becoming competent, some larvae survived and settled for extended periods after spawning. Competency periods ranged from 26 d for C. serailia to 56 d for G. australensis and 78 d for A. lordhowensis. These data greatly extend the known competency periods for larvae of broadcast-spawning corals and indicate the potential for transport of broadcast-spawned coral larvae over large distances. Medium to long-distance larval dispersal of the species studied provides a mechanism for their widespread distribution in subtropical regions, on reefs which are often widely spaced and relatively isolated. Received: 27 May 1997 / Accepted: 27 November 1997     

Induction of metamorphosis of two species of sea urchin from Sea of Japan

The induction of metamorphosis in mature larvae by selected chemical compounds and natural substrata was investigated in two species of sea urchins from the Sea of Japan, Strongylocentrotus intermedius and Scaphechinus mirabilis. Glutamine in crystalline form was added directly to water containing mature larvae, and this compound, at a final concentration of 10 g ml^-1, was an inducer of metamorphosis in S. intermedius (100% activity) and S. mirabilis (50% activity). Gutamine, or its natural mimetic molecules, may be an active component of the exogenous cue that induces metamorphosis of S. intermedius larvae. This exogenous cue was produced by the epiphytic calcareous algae, Melobesia spp. that colonized the older sea grass Zostera marina. Glutamic acid was also used as an inducer of metamorphosis for S. intermedius and S. mirabilis larvae (50 to 60% activity), but it was toxic to the larvae.     

Suppression of inhibition of substrate photodegradation by scavengers of hydroxyl radicals: the solvent-cage effect of bromide on nitrate photolysis

In this paper we show that bromide scavenges the ^·OH radicals formed upon photolysis of nitrate, before they leave the solvent cage. Bromide can thus inhibit the in-cage recombination between ^·OH and ^·NO₂. The consequence is an increased generation of ^·NO₂ and nitrite and of Br₂ ^?· + ^·OH, compared to ^·OH alone in the absence of bromide. We show that this effect compensates for the lower reactivity of Br ₂ ^?· compared to ^·OH toward certain organic substrates, e.g. phenol and tryptophan. Our findings could lead to a deep revision of the present views of the role of bromide in saltwater photochemistry.     

Comparison of laboratory rates of predation of five species of marine fish larvae by three planktonic invertebrates: effects of larval size on vulnerability

Rates of predation by the invertebrates Aurelia aurita, Thysanoessa raschi and Euchaeta norvegica on larval stages of cod (Gadus morhua L.), flunder (Platichthys flesus L.), plaice (Pleuronectes platessa L.), herring (Clupea harengus L.), and turbot (Scophthalmus maximus L.) were determined. Experiments were conducted in late winter and early spring 1982 with predators collected in Loch Etive, Scotland and prey obtained from several locations in Great Britain. Early stages of the smallest species, cod, flounder and turbot, tended to be most vulnerable to all three predators, while the early stages of the larger species, plaice and herring, and older stages of all species, were less vulnerable. For all stages and species of larvae, predation rates by the three predators were most closely related to larval length and escape swimming speed. Larval length itself was closely correlated to indices of larval escape ability. Low predation rates on large larvae by E. norvegica could be due to handling difficulties, whereas for A. aurita and T. raschi these low rates were due to escape abilities of the larger larvae. Prey movement is an important stimulus eliciting predation in E. norvegica but not in A. aurita or T. raschi.     

Distribution of dimorphic males of three species of Nematoscelis (Euphausiacea)

Samples collected from the eastern Atlantic Ocean between 40° and 4° N with rectangular and ring nets contained male specimens of Nematoscelis atlantica, N. microps, and N. tenella (Euphausiacea) with saddle-shaped thickenings of chitin on the dorsal surface of some abdominal segments, and with enlarged photophores on the abdominal segments immediately posterior to those with thickenings. Two forms of each species are distinguished by the number and the position of chitinous thickenings and enlarged photophores. Except in a zone off W. Africa (approximately between 22° and 16° N) each form of N. atlantica and N. microps occurs as a distinct population. These populations appear to be characteristic of either the North or South Atlantic Central water, and the overlap zone corresponds approximately with the physical boundary between these water masses and with a faunal transition zone found in this region by other workers. For N. tenella it appears that only one form occurs as a separate population south of 18° N in South Atlantic Central water. Between 28° and 18° N the two forms co-exist.     

Aspects of the biology of resting spores of Thalassiosira nordenskioeldii and Detonula confervacea

Large numbers of resting spores of Thalassiosira nordenskioeldii Cleve and Detonula confervacea (Cleve) Gran were produced when these species were grown at low levels of ammonia and nitrate. The production of resting spores by T. nordenskioeldii was inversely related to temperature. At 0° and 5°C between 68 and 96% of the total cells were resting spores, while at 15°C resting spores were not produced. Resting spores of both species would not survive 7 days in the dark at 20°C. At 0°, 5°, 10° and 15°C, the length of time that the resting spores of both T. nordenskioeldii and D. confervacea remained viable was inversely related to temperature. At 0°C, T. nordenskioeldii remained viable for 576 days. The data suggest that the production of resting spores by these two species does not aid them in the survival of unfavorably high temperatures such as are found in temperate estuaries during the summer. Rather, they appear to be an adaptation for the survival of long periods of darkness in polar regions.     

Genetic evidence of the presence of two species of Crassostrea (Bivalvia: Ostreidae) on the coast of Brazil

 Although oysters are commercially very important in Brazil, there is still much dispute about the number of Crassostrea species occurring on the Brazilian coast. The dispute is centered around C. brasiliana, considered by some authors to be a junior synonym of C. rhizophorae. In this paper we compared, by allozyme electrophoresis, sympatric and allopatric populations of the two putative species. Of the 17 loci analysed, five were diagnostic for the two species in sympatry (gene identity = 0.46 to 0.47), clearly demonstrating that they are distinct biological species. Heterozygosity (h) levels were high for both species (h = 0.24 to 0.28), and no heterozygote deficiencies were observed in any population (local inbreeding, F _IS  = 0.141; P > 0.70). Levels of population structure in C. rhizophorae along 1300 km of coast were very low (population inbreeding, F _ST  = 0.026; P > 0.15), indicating that the planktonic, planktotrophic larvae of these species are capable of long-range dispersal. Received: 14 January 1999 / Accepted: 8 December 1999     

Identification of the sex pheromone of Conogethes pluto: a pest of Alpinia

In recent years, Conogethes pluto (Lepidoptera: Crambidae) has become a major pest of Alpinia and other ornamental gingers in the Northern Territory and Queensland, Australia. This pest damages the flowers and bores into the stems, causing substantial losses to production. Currently, no synthetic sex pheromone is available to monitor or control this pest. This work aims at the identification of the sex pheromone of this pest. Analysis of the sex pheromone gland of female C. pluto by gas chromatography/electroantennogram detector revealed the presence of seven candidate pheromone compounds that elicited electroantennogram responses. Using gas chromatography/mass spectrometry analysis and micro-derivatization reactions, six compounds were identified as (E)-10-hexadecenal, as the main pheromone compound, (Z)-10-hexadecenal, hexadecanal, (E)-10-hexadecen-1-ol, (10E,12E)-hexadeca-10,12-dienal and (3Z,6Z,9Z)-tricosa-3,6,9-triene as minor pheromone compounds. In two-field trapping experiments, C. pluto responded to the six-component blend, and three of six compounds, i.e., (E)-10-hexadecenal, (3Z,6Z,9Z)-tricosa-3,6,9-triene, and (10E,12E)-hexadeca-10,12-dienal were shown to be necessary for attraction. In a subsequent experiment testing various doses (i.e., 0.01, 0.1, and 1 mg) of the six-component blend, the largest number of males was captured in traps baited with a lure loading of 1 mg. The availability of the sex pheromone of C. pluto will enable monitoring and provides the basis for additional control options for this pest.     

Studies of thermodynamics of phosphomidon on fly ash

Adsorption thermodynamic studies of phosphomidon on fly ash at 25° and 50°C have been analysed as adsorption isotherms, Freundlich equations, K_d values and various other thermodynamic parameters. These data were in close agreement with Freundlich isotherms and yield ‘S’ type isotherms at both the temperatures. Thermodynamic constants (K_o) and standard free energy (ΔG°), enthalpy (ΔH°) and entropy changes (ΔS°) have been calculated for predicting the nature of adsorption.     

Numbers,biomass, and caloric content of the echinoderm fauna of the rocky shores of Barbados

The high-energy windward coasts with narrow rocky intertidal regions (Oistens, River Bay) at Barbados, West Indies, had abundant macroscopic algae (mainly Sargassum sp.) and populations of Holothuria glaberrima Selenka and Echinometra lucunter (Linnaeus), while protected ones with a wide rocky intertidal had sparse macroscopic algae and populations of E. lucunter only. The low-energy leeward coasts with wide rocky intertidal regions (Six Men's Bay, Payne's Bay) had no macroscopic algae in the surf zone and populations of E. lucunter only. Numerical densities of E. lucunter were high in all localities; the highest level of 144 m^-2 was found at Six Men's Bay; numerical densities of H. glaberrima were high at both Oistens and River Bay, the highest level of 36 m^-2 being recorded at River Bay. The caloric density of H. glaberrima at River Bay was 412 kcal m^-2. The highest combined density of H. glaberrima and E. lucunter was at Oistens (632 kcal m^-2, with 254 kcal m^-2 being due to E. lucunter). The highest caloric density of E. lucunter at Six Men's Bay was 482 kcal m^-2. Dependence on suspended food probably restricts H. glaberrima to high-energy environments while E. lucunter has an additional food source through its ability to scrape the rock substratum. E. lucunter may be more efficient in catching drift food. Mortality is suggested to be the basis of the failure of E. lucunter to displace H. glaberrima from the high-energy location.     

Effects of ammonia on survival and osmoregulation of various development stages of the shrimp Penaeus japonicus

In Penaeus japonicus, the tolerance to ammonia increased with the development from nauplius to late juvenile. The 48-h LC₅₀ of ammonia in nauplii (III–V), 96-h LC₅₀ in zoeae (I–III), mysis (I–III), post-larvae (PL1) and late juveniles (10.4±1.1 g) were respectively 5.0, 6.1 to 8.1, 9.4 to 10.9, 15.5 and 52.7 mg Nl^-1 (0.5, 0.6 to 0.7, 0.9, 1.3 and 3.1 mg NH₃–Nl^-1). In a chronic experiment (20 d), the LC₅₀ in post-larvae (PL1) was 19.1 (1.4) at 96 h and 16.2 mg Nl^-1 (1.3 mg NH₃–Nl^-1) at 480 h. Osmoregulatory capacity (OC) was calculated as the osmotic gradient between the hemolymph and the external medium at given salinities. The effects of ammonia on OC, Na⁺ and Cl^- regulation and gill Na⁺–K⁺ ATPase activity in late juveniles were examined in fullstrength seawater, SW (1050 mosm kg^-1, 36 S) and in dilute SW (450 mosm kg^-1, 15%.), after 48 or 96 h exposure to various concentrations of ammonia. Ambient ammonia disrupted both hypo- and hyper-osmoregulation; decreased OC resulted from impaired Na⁺ and Cl^- regulation. Gill Na⁺–K⁺ ATPase activity increased in SW and was not affected in dilute SW. The decrease of OC was ammonia-dose-dependent. The threshold ammonia concentrations affecting hypo-OC and hyper-OC were, respectively, 16 (1.3) and 32 mg Nl^-1 (2.3 NH₃–Nl^-1) for a 48 h exposure; these concentrations were lower than the 48-h LC₅₀ value, 65.3 mg Nl^-1 (3.5 NH₃–Nl^-1). The time course of exposure to sublethal ammonia (48 mg Nl^-1) demonstrated that the effect on osmoregulation was time-dependent. This effect was also temporary, and the exposed shrimps recovered control OC values after removal of excessive ambient ammonia. The possibility of using OC as an indicator of physiological condition in osmoregulating crustaceans and the acting mode of ammonia on osmotic and ionic regulation are discussed.     

Determination of persistent organic pollutants in sediment and fish of the western coast of Alexandria,Egypt

Persistent organic pollutants (POPs) were recorded in sediment and fish samples collected from the western coast of Alexandria. Total hydrocarbons (aliphatic+PAHs ) in sediment ranged from 683.8 to 34670.1 ng g ^?1 with an average of 9286.9 ng g ^?1. The sum of C16–C34 of aliphatic fractions was<4000?ng g;^?1, indicating the presence of a fresh petroleum source. For all sediments, the anthracene/phenanthrene ratio was>0.1, suggesting the dominance of a pyrolytic source. Total aliphatics in different fish species ranged from 253 to 11?132 ng g;^?1, while total PAHs ranged from 3862 to 35?746 ng g;^?1 wet weight. Benzo[a]pyrene was the most dominant PAH fraction ranged from 1902.7 to 32 905.5 with an average of 9464.5?ng g;^?1 wet weight in all fish species. Concentrations of polychlorinated biphenyls (PCBs) ranged from 0.79 to 64.9?ng g;^?1 with an average 12.14?ng g;^?1 wet weight. The concentrations of organochlorines in fish species (Euthynnus alleferatus, Scomberomorus commerson, Sphyraena Sphyraena, Diplodus vulgaris, and Alepes djedaba) decreased following the order: PCBs>DDTs>HCHs>total cyclodienes. Concentrations of DDTs in fish tissues ranged from 4.89 to 36.37 ng g^?1 with an average of 16.4?ng g;^?1 wet weight. The concentrations of total HCHs ranged from 0.3 to 65.7?ng g;^?1 with an average of 16.35?ng g;^?1. The present study indicates: (1) fresh petroleum input where Pr/Ph>1; (2) PAHs in sediment<4000 ng g ^?1; (3) BaP concentration exceeded the permissible levels in Alepes djedaba species; (4) DDTs in sediment were below the effective range low level; (5) PCBs>effective range low and相似文献   

Ultrastructure of the digestive gland of larval and adult stages of the sacoglossan Elysia patagonica

Chloroplast retention in the sacoglossan gastropod Elysia patagonica Muniain and Ortea, 1997 was investigated. Intact chloroplasts of the green algae Bryopsis plumosa (Chlorophyta: Bryopsidacea) were observed by transmission electron microscopy in vacuoles of the digestive cells of benthic adults starved for 20 days. Intact chloroplasts from the microalgal Nannochloropsis sp. (Heterokontophyta: Eustigmatophycea) were found in the digestive cells of veliger larvae feeding for 8 days. Similar digestive cells were observed in adults and planktonic larvae of E. patagonica. The retention ability is confirmed in both stages.     

Estimation of abundance of fish populations by capture-recapture experiments

A natural fish population is assumed to be subjected to a number of fishing experiments, during which the captured fish are released after tagging all untagged fish. Assuming that, in thek ^th sampling survey, the tagged and untagged fish are subjected toP _tk andP _uk fishing rates, andS _tk andS _uk survival rates, respectively, the population size can be estimated from an estimate ofP _uk $$\begin{gathered} i.e., 1 - P_{uk} = \hfill \\ P_{tk \cdot } \frac{{S_t (k + 1)}}{{S_u (k + 1)}}\frac{\begin{gathered} Number of fish captured for the first time in \hfill \\ the (k + 1)^{th} survey plus fish belonging to this \hfill \\ group captured later \hfill \\ \end{gathered} }{\begin{gathered} Number of fish captured for the first time in \hfill \\ the k^{th} and captured again in the (k + 1)^{th} \hfill \\ \exp eriment plus fish belonging to this group \hfill \\ which are captured later \hfill \\ \end{gathered} } \hfill \\ \end{gathered}$$ All terms of the right hand side of the above equation are provided by capture-recapture experiments, except the survival rate of untagged fish which may be obtained by other information. This estimate of fishing rate of untagged fish is free from type (A) errors.     

The mouthparts of the members of the Jaera albifrons group of species (Crustacea: Isopoda)

The mouthparts of Jaera albifrons Leach, Jaera ischiosetosa Forsman, Jaera praehirsuta Forsman and Jaera forsmani Bocquet were examined with the light microscope and the Stereoscan electron microscope, and were found to be identical in all species. The structure of the mouthparts indicate that all four species feed by scouring and abrading algal or bacterial films from rocks or Fucus. Food, therefore, does not seem to be an isolating factor involved in the microdistribution of the four species on a shore.     

Respiration of the eggs of the giant cuttlefish Sepia apama

On the roofs of subtidal crevices, the giant cuttlefish (Sepia apama) of southern Australia lays clutches of lemon-shaped eggs which hatch after 3 to 5 mo. Diffusion of oxygen through the capsule and chorion membrane to the perivitelline fluid and embryo was modelled using the equation V˙ _O2 = G _O2(P _O2out−P _O2in), where V˙ _O2 = rate of oxygen consumption, G _O2 = oxygen conductance of the capsule, and P _O2 values = oxygen partial pressures across the capsule. During development, V˙ _O2 rose exponentially as the embryo grew, reaching 5.5 μl h⁻¹ at hatching. Throughout development, the capsule dimensions enlarged by absorption of water into the perivitelline space, increasing G _O2 by a combination of increasing surface area, and decreasing thickness of the capsule. These processes maintained P _O2in high enough to allow unrestricted V˙ _O2 until shortly before hatching. Diffusion limitation of respiration in hatching-stage embryos was demonstrated by (1) increased embryonic V˙ _O2 when P _O2out was experimentally raised, (2) greater V˙ _O2 of resting individuals immediately after hatching, and (3) reduced V˙ _O2 of hatchlings at experimental P _O2 levels higher than P _O2in before hatching. Thus, low P _O2in may be the stimulus to hatch. Potential problems of diffusive gas-exchange are mitigated by the relatively low incubation temperature (12 °C), which may be a factor limiting the distribution of the species to cool, southern waters. Received: 14 August 1999 / Accepted: 24 January 2000     

Spatial heterogeneity of photosynthesis and the effect of temperature-induced bleaching conditions in three species of corals

Heterogeneity in photosynthetic performance between polyp and coenosarc tissue in corals was shown using a new variable fluorescence imaging system (Imaging-PAM) with three species of coral, Acropora nobilis, Cyphastrea serailia and Pocillopora damicornis. In comparison to earlier studies with fibre-optic microprobes for fluorescence analysis, the Imaging-PAM enables greater accuracy by allowing different tissues to be better defined and by providing many more data points within a given time. Spatial variability of photosynthetic performance from the tip to the distal parts was revealed in one species of branching coral, A. nobilis. The effect of bleaching conditions (33°C vs. 27°C) was studied over a period of 8 h. Marked changes in fluorescence parameters were observed for all three species. Although a decline in _PSII (effective quantum yield) and Yi (the first effective quantum yield obtained from a rapid light curve) were observed, P. damicornis showed no visual signs of bleaching on the Imaging-PAM after this time. In A. nobilis and C. serailia, visual signs of bleaching over the 8 h period were accompanied by marked changes in F (light-adapted fluorescence yield), NPQ (non-photochemical quenching) and E _k (minimum saturating irradiance), as well as _PSII and Yi. These changes were most marked over the first 5 h. The most sensitive species was A. nobilis, which after 8 h at 33°C had reached a _PSII value of almost zero across its whole surface. Differential bleaching responses between polyps and coenosarc tissue were found in P. damicornis, but not in A. nobilis and C. serailia. NPQ increased with exposure time to 33°C in both the latter species, accompanied by a decreasing E _k, suggesting that the xanthophyll cycle is entrained as a mechanism for reducing the effects of the bleaching conditions.Communicated by L. Hagerman, Helsingør     

Microstructure of settlement-marks in the otoliths of tropical reef fishes

The morphology and ultrastructure of the otolith settlement-mark was examined in 44 tropical reef-fish species spanning nine families. A classification scheme based on similar otolith characteristics is presented. Three major categories are identified based on changes in increment width and optical qualities of the settlement-mark. Of the 44 species examined, 39 possessed “abrupt” settlement-marks (Type I) characterised by a rapid decrease in increment width (up to 50% reduction) over settlement. Type I settlement-marks were found in all nine families examined. The 39 species spanned the whole range of possible larval durations (Pomacentrus moluccensis, 15 d ± 0 SE; Naso hexacanthus, 91.2 d ± 2.97 SE). Four of the 44 species possessed “zonal” settlement-marks (Type II), featuring a band of increments that are wider than pre-settlement increments. Species in this category are the labrids Corisaygula, Thalassoma bifasciatum, T. lunare and an unidentified acanthurid (Acanthurus sp. 2). One species of acanthurid (N. brevirostris) possessed a “gradual” settlement-mark (Type III), manifest as a gradual decrease in increment width during the settlement period. A possible fourth type was identified from the literature. Gnatholepis thompsoni and Coryphopterus glaucofraenum possessed a settlement-mark with increment widths that increased post-settlement. Available data suggest a poor relationship between the structure of the settlement-mark and the magnitude of metamorphosis (previously reported as internal and external morphological change). Evidence suggests that the increment profile over early development and the increment transitions associated with the settlement event are taxon-specific and may enable late-larval stage fishes to be identified to species level. Received: 21 May 1997 / Accepted: 3 February 1999     

Levels of selected urinary metabolites of volatile organic compounds in a representative sample of US adolescents

Data from National Health and Nutrition Examination Survey for the years 2011–2012 were used to evaluate the variability in the observed levels of 20 urinary metabolites of 16 parent volatile organic compounds by age, gender, race/ethnicity, and smoking status for adolescents aged 12–19 years. Smokers were found to have statistically significantly higher adjusted levels than nonsmokers for selected urinary metabolites of acrylonitrile (p < 0.05) and 1,3-butadiene (p < 0.05). For example, for N-Acetyl-S-(2-cyanoethyl)-L-cysteine, the adjusted levels for smokers were 29.2 ng/mL and 2.0 ng/mL for nonsmokers (p < 0.05). Females were found to have higher adjusted levels of selected metabolites of crotonaldehyde (p < 0.05), cyanide (p < 0.05), and tetrachloroethylene (p < 0.05) than males. For example, the adjusted levels of 2-Aminothiazoline-4-carboxylic acid or ATCA were 218.9 and 108.6 ng/mL for females and males, respectively (p < 0.05). Non-Hispanic whites (NHW) had higher adjusted levels than non-Hispanic blacks (NHB) for selected metabolites of N,N-dimethylformamide (p < 0.05) and ethylbenzene, styrene (p < 0.05). For example, for N-Acetyl-S-(N-methylcarbamoyl)-L-cysteine or AMCC, the adjusted levels for NHW and NHB were 122.7 and 80.2 ng/mL, respectively (p < 0.05). The reverse was true for selected metabolites of carbon-disulfide and tetrachloroethylene. For example, for N-Acetyl-S-(benzyl)-L-cysteine or BMA, adjusted levels for NHW and NHB were 6.7 and 10.3 ng/mL, respectively (p < 0.05).