The plant-derived triterpenoid, cucurbitacin B, but not cucurbitacin E, inhibits the developmental transition associated with ecdysone biosynthesis in Drosophila melanogaster.

In insects, some sterols are essential not only for cell membrane homeostasis, but for biosynthesis of the steroid hormone ecdysone. Dietary sterols are required for insect development because insects cannot synthesize sterols de novo. Therefore, sterol-like compounds that can compete with essential sterols are good candidates for insect growth regulators. In this study, we investigated the effects of the plant-derived triterpenoids, cucurbitacin B and E (CucB and CucE) on the development of the fruit fly, Drosophila melanogaster. To reduce the effects of supply with an excess of sterols contained in food, we reared D. melanogaster larvae on low sterol food (LSF) with or without cucurbitacins. Most larvae raised on LSF without supplementation or with CucE died at the second or third larval instar (L2 or L3) stages, whereas CucB-administered larvae mostly died without molting. The developmental arrest caused by CucB was partially rescued by ecdysone supplementation. Furthermore, we examined the effects of CucB on larval-prepupal transition by transferring larvae from LSF supplemented with cholesterol to that with CucB just after the L2/L3 molt. L3 larvae raised on LSF with CucB failed to pupariate, with a remarkable developmental delay. Ecdysone supplementation rescued the developmental delay but did not rescue the pupariation defect. Furthermore, we cultured the steroidogenic organ, the prothoracic gland (PG) of the silkworm Bombyx mori, with or without cucurbitacin. Ecdysone production in the PG was reduced by incubation with CucB, but not with CucE. These results suggest that CucB acts not only as an antagonist of the ecdysone receptor as previously reported, but also acts as an inhibitor of ecdysone biosynthesis.

Molting method alternative and detection of estrogen receptors by immunohistochemical methods on molted layers.

Three experiments were designed to evaluate the effects of different molting methods on the growth performance, detection of estrogen receptors (ERs), and immunohistochemical properties of some tissues in pre-, during, and post-molting of layers. In experiment 1, 302 Hy-line W-36 were reared from 75 to 76 weeks. In experiment 2, a total of 252 Hy-line W-36 were randomly allocated to 7 groups, with 6 replications and 6 birds in each. Hens fed in the E and D groups reached 30% of loss weight sooner (P < 0.05). Egg production was also sooner stopped in the FW group than in other ones (P < 0.05). In experiment 3, after inducing molting, each group in experiment 2 was divided into 2 groups with and without Humulus lupulus (Hop). The E group feed intake was increased, as compared to groups F and C (P < 0.05). A significant increase in egg weight was found by applying Hop and molting methods (P < 0.05). Days for return to the initial egg production and 10% egg laying were significantly decreased in the birds fed by Hop in the E and D groups (P < 0.05). The W-D, N-D, W-E, and N-E groups sooner returned to 50% egg laying, in comparison to other treatments (P < 0.05). Plasma estrogen and ERs were decreased by the molting programs, as compared with pre-molting; however, Hop increased their post-molting. After the molting period, egg production and ERs were increased significantly, as compared with the pre-molting period. To conclude, the white button mushroom residual, through decreasing ERs, could be used successfully for forced molting, and Hop could lead to a good performance by increasing ERs in the second laying cycle.

Ultrasound-assisted extraction extracts from Stemona japonica (Blume) Miq. and Cnidium monnieri (L.) Cuss. could be used as potential Rhipicephalus sanguineus control agents.

Nicotiana tabacum, Stemona japonica, and Cnidium monnieri are common plants that are widely used for their anti-parasitic properties. The purpose of this study was to evaluate the acaricidal activity of extracts from these plants against the brown dog tick, Rhipicephalus sanguineus. A composition analysis of crude extracts by GC-MS was conducted to discover compounds with acaricidal effects. The toxicity of extraction against the engorged nymphs of R. sanguineus was evaluated by an immersion test. The results showed that the crude extracts of S. japonica and C. monnieri in varying ratios, concentrations, and from different extraction methods, had a killing effect on R. sanguineus. Lethality reached 76.67% ± 0.04410 when using a 1:1 extract of S. japonica:C. monnieri in 75% ethanol with ultrasonic extraction; the crude extract was determined at a concentration of 0.5 g/mL. GC-MS results showed that osthole and 5-hydroxymethylfurfural (5-HMF) are the main components of the extract. These results suggested that ultrasound-assisted extraction (UAE) extracts contained acaricidal components acting against R. sanguineus, which may result in the development of effective extracts of S. japonica and C. monnieri as a source of low-toxicity, plant-based, natural acaricidal drugs.

Effects of Sublethal Chlorpyrifos Exposure on Postlarval American Lobster (Homarus americanus).

The organophosphate pesticide chlorpyrifos has been introduced to the marine environment via adsorption to agricultural soil runoff or as spray drift. Chlorpyrifos affects the survival of some larval decapod crustaceans, but no data exist on the impacts to the American lobster, Homarus americanus. The purpose of the present study was to assess the levels at which chlorpyrifos affects the survival of postlarval H. americanus. Using acute saltwater exposures, the 24- and 48-h median lethal concentrations were established for stage IV H. americanus (1.56 and 1.33 µg/L, respectively). Movement, acetylcholinesterase activity, intermoult period, specific growth rate, and moult increment were measured during exposure to sublethal concentrations. Movement patterns were assessed to establish a 48-h median inhibition concentration for cessation of normal movement (0.66 µg/L). Acetylcholinesterase activity was found to be inhibited immediately post-exposure to 0.50, 0.57, and 0.82 µg/L chlorpyrifos but could be recovered within a period (9-15 d) in clean seawater. Sublethal growth effects of increased intermoult period, decreased specific growth rate, and decreased moult increment were observed during exposure to an environmentally relevant concentration (0.82 µg/L). The present study suggests that H. americanus stage IV larvae were marginally less sensitive to chlorpyrifos compared with other decapods and that acute lethality of H. americanus postlarvae is not likely to occur with chlorpyrifos concentrations previously reported from aquatic environments. Environ Toxicol Chem 2019;38:1294-1301. © 2019 SETAC.

Energy metabolism and survival of the juvenile recruits of the American lobster (Homarus americanus) exposed to a gradient of elevated seawater pCO2.

The transition from the last pelagic larval stage to the first benthic juvenile stage in the complex life cycle of marine invertebrates, such as the American lobster Homarus americanus, a species of high economic importance, represents a delicate phase in these species development. Under future elevated pCO2 conditions, ocean acidification and other elevated pCO2 events can negatively affect crustaceans. This said their effects on the benthic settlement phase are virtually unknown. This study aimed to identify the effects of elevated seawater pCO2 on stage V American lobsters exposed to seven pCO2 levels. The survival, development time, metabolic and feeding rates, carapace composition, and energy metabolism enzyme function were investigated. Results suggested an increase in mortality, slower development and an increase in aerobic capacity with increasing pCO2. Our study points to potential reduction in juvenile recruitment success as seawater pCO2 increases, thus foreshadowing important socio-economic repercussions for the lobster fisheries and industry.

The effects of emamectin benzoate or ivermectin spiked sediment on juvenile American lobsters (Homarus americanus).

This study examined the effects of a range of ½-log concentrations of emamectin benzoate (commercially applied as SLICE®) and ivermectin (commercially applied as IVOMEC®) on juvenile American lobster, Homarus americanus. Phase I of the research assessed acute (up to 4 days) and chronic (30-day) toxicity of sediment dosed with the active ingredients emamectin benzoate (EMB) formulated as SLICE® or ivermectin (IVM) formulated as IVOMEC® at various nominal concentrations (EMB: 15, 48, 150, 475 and 1500 ng g-1 wet sediment; IVM: 3, 9.5, 30, 95 and 300 ng g-1 wet sediment) on juvenile Atlantic lobster (stages IV). Phase II evaluated sublethal effects (e.g., growth, moulting success) of all lobster surviving past the 30 day exposure period, over an additional 41 days. Chemical analysis of EMB and IVM in sediment samples from the exposure tanks revealed a strong linear association (R2 values 0.99 and 0.98 for EMB and IVM, respectively) between nominal dose and measured concentration of compound. EMB exposure concentrations at very high levels (≥ 343.3 ng g-1) were acutely toxic to juvenile lobster such that 100% of lobsters had died after 13 days of exposure. The maximum cumulative mortality of lobsters exposed to the highest concentrations of EMB and IVM was 100% after 10 days and 25 days, respectively. The 10-day LC50 estimates (±â€¯95% CI) for EMB and IVM were 250.23 ±â€¯90.4 and 212.14 ±â€¯202.64 ng g-1, respectively. Using abnormal behaviour as an indicator, the 15-day EC50 estimates (±â€¯95% CI) for EMB and IVM were 96.19 ±â€¯51.42 and 15.82 ±â€¯6.93 ng g-1, respectively. The NOEC (no observed effect concentration) for abnormal behaviour was 0.0 ng g-1 for each product and the LOEC (lowest observed effect concentration) was 8.8 and > 3.0 ng g-1 for EMB and IVM, respectively. Observations on sublethal effects included delayed moulting to stage VI and reduced growth at higher exposure concentrations for both therapeutants. Using failure to moult to stage V or VI as an indicator, the 15-day EC50 estimates (±â€¯95% CI) for EMB and IVM were 32.72 ±â€¯18.26 and 14.00 ±â€¯12.43 ng g-1, respectively. The NOEC for failure to moult to stage V only was 343.3 and 14.7 ng g-1 for EMB and IVM, respectively. Whereas, the LOEC was 1066.7 and > 61.0 ng g-1 for EMB and IVM, respectively. The concentrations of EMB and IVM tested in the present study were acutely toxic to juvenile lobster exposed to the highest dosages (343.3 and 1066.7 ng EMB g-1 and 61.0 and 300.0 ng IVM g-1). There was significant evidence of chronic toxicity, longer exposure increased mortality with LT50 values decreasing with increasing test material concentration.

WAFs lead molting retardation of naupliar stages with down-regulated expression profiles of chitin metabolic pathway and related genes in the copepod Tigriopus japonicus.

Oil pollution is considered being disastrous to marine organisms and ecosystems. As molting is critical in the developmental process of arthropods in general and copepods, in particular, the impact will be adverse if the target of spilled oil is on molting. Thus, we investigated the harmful effects of water accommodated fractions (WAFs) of crude oil with an emphasis on inhibition of chitin metabolic pathways related genes and developmental retardation in the copepod Tigriopus japonicus. Also, we analysed the ontology and domain of chitin metabolic pathway genes and mRNA expression patterns of developmental stage-specific genes. Further, the developmental retardation followed by transcriptional modulations in nuclear receptor genes (NR) and chitin metabolic pathway-related genes were observed in the WAFs-exposed T. japonicus. As a result, the developmental time was found significantly (P<0.05) delayed in response to 40% WAFs in comparison with that of control. Moreover, the NR gene, HR3 and chitinases (CHT9 and CHT10) were up-regulated in N4-5 stages, while chitin synthase genes (CHS-1, CHS-2-1, and CHS-2-2) down-regulated in response to WAFs. In brief, a high concentration of WAFs repressed nuclear receptor genes but elicited activation of some of the transcription factors at low concentration of WAFs, resulting in suppression of chitin synthesis. Thus, we suggest that WAF can lead molting retardation of naupliar stages in T. japonicus through down-regulations of chitin metabolism. These findings will provide a better understanding of the mode of action of chitin biosynthesis associated with molting mechanism in WAF-exposed T. japonicus.

In vitro activity of 3ß-O-tigloylmelianol from Guarea kunthiana A. Juss (Meliaceae) on oogenesis and ecdysis of the cattle tick Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae).

We evaluated the effects of 3ß-O-tigloylmelianol from Guarea kunthiana A. Juss (Meliaceae) on oogenesis, as a larvicide and on ecdysis of the larvae and the nymphs of the cattle tick Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae). On the oogenesis' test, 48 engorged females were divided into three groups, evaluated at 24, 48 and 72 h post-treatment. Half of the females were treated with 0.01% 3ß-O-tigloylmelianol diluted in distilled water and 5% dimethyl sulfoxide (DMSO), while the other half (controls) were exposed to distilled water and 5% DMSO. After treatment, the ovaries were weighed in order to measure the gonadosomatic index (GSI) and were also subjected to standard histological technical tests. On the larvicide and ecdysis' tests, 3ß-O-tigloylmelianol was tested at concentrations of 0.01, 0.005, 0.0025 and 0.00125%. Compared with the controls, there was a reduction of GSI of approximately 50% on the treated group, which started at 48 h post treatment. Overall, the protolimonoid 3ß-O-tigloylmelianol has caused a significant reduction in the number of oocytes. It has also caused alteration of the cytoplasmic and germinal vesicle diameters. Morphological changes, such as vacuolization, chorion irregularity which has modified the oocytes' morphology as well as alterations on the yolk's granules were also observed. The compound was not larvicide, however, interfered in the ecdysis of the larvae and the nymphs. This study shows that the protolimonoid 3ß-O-tigloylmelianol from G. kunthiana acts on oogenesis and ecdysis of R. (B.) microplus, but not as larvicide, indicating that it acts on the endocrine system of the tick.

Effect of vitamins, probiotics and protein level on semen traits and seminal plasma biochemical parameters of post-moult male broiler breeders.

1. A study was designed to investigate the comparative effect of supplementary vitamin E, vitamin C, probiotics and dietary crude protein concentration on semen traits and seminal plasma biochemical parameters in male broiler breeders after Zn-induced moulting. 2. A total of 180 male broiler breeders were induced to moult at 65 weeks of age by mixing ZnO in diet at the rate 3000 mg/kg of feed. After moulting, the males were divided into six groups that were given feed supplemented with: vitamin C (500 IU/kg), vitamin E (100 IU/kg), protein (140 g CP/kg), probiotics (50 mg/kg) and the combination of these components, while one group was kept as a control. Semen samples were collected weekly and semen volume, spermatozoa concentration, motility and dead spermatozoa percentage were determined. Seminal plasma was separated to determine the concentration of total antioxidant capacity (TAC), homocysteine, paraoxonase (PON1), arylesterase, ceruloplasmin, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities. 3. Semen volume was significantly higher in the vitamin E and C groups compared to the control. Spermatozoa motility was higher in the vitamin E group and dead spermatozoa percentage was significantly lower in the vitamin C group compared with the control group. 4. Seminal plasma TAC was higher in the vitamin E group, homocysteine was lower in the vitamin C and E groups. PON1 was higher in the combination group. Arylesterase increased significantly in the vitamin C and combination groups over time. Seminal plasma AST was significantly lower in the vitamin C and E supplemented groups whereas ALT decreased significantly only in the vitamin E group compared with the control. Higher concentrations of ceruloplasmin were observed in the combination group compared with the other treatments. 5. It was concluded that additional vitamin E and C or their combination was the most potent nutrient treatment for improving the semen traits and seminal plasma biochemical characteristics in male broiler breeders after Zn-induced moulting.

Supplementation of dietary vitamins, protein and probiotics on semen traits and immunohistochemical study of pituitary hormones in zinc-induced molted broiler breeders.

The purpose of this study was to investigate the effect of dietary vitamin E and vitamin C, probiotics mixture and protein level and their combination on semen quality and immunohistochemical study of some pituitary hormones in male broiler breeders. One hundred and eighty male broiler breeders 65 weeks old were divided into six groups by completely randomized design. The birds were subjected to zinc-induced molt by mixing zinc oxide at the rate of 3000mg/kg in the feed. After molting, one group was fed control diet (CP16%). The other groups were fed vitamin E (100IU/kg), vitamin C (500IU/kg), probiotics (50mg/L of drinking water), protein (CP14%) and combination of these components. These treatments were given for five weeks. After the feeding period, semen samples were taken and analyzed for semen volume, sperm concentration, motility and dead sperm percentage. Pituitary samples were collected from three birds per replicate and were processed for immunohistochemical study. The results of semen quality parameters revealed that semen volume and sperm motility were significantly high in the vitamin E fed group, while the dead sperm percentage decreased significantly in the vitamin C group. The morphometric analysis revealed that compared to other groups, vitamin E caused a significant increase in the size and area of FSH, LH gonadotropes and lactotropes. These results showed that vitamin E alone may play some role in the enhancement of semen quality and growth of gonadotropes and lactotropes.

Laboratory evaluation of the effects of Manilkara subsericea (Mart.) Dubard extracts and triterpenes on the development of Dysdercus peruvianus and Oncopeltus fasciatus.

BACKGROUND: Studies were carried out to evaluate the effects of Manilkara subsericea extracts and triterpenes on the development of two species of agricultural pest insects, Oncopelus fasciatus and Dysdercus peruvianus. RESULTS: All treatments of insects with M. subsericea extracts induced mortality, delayed development and inhibited moulting. Some extracts assayed (FH, FB and FD in D. peruvianus, and FH, FB and FEA in O. fasciatus) also produced body deformities in the few adults that emerged. Other extracts (FH, FEA, FB, FD and LET in both insects), however, induced either permanent (overaged) or extranumerary nymphs, both of which were unable to achieve the adult stage and reproductive status. The insects were also treated with triterpenes (α- and ß-amyrin acetates) which showed high lethality at 30 days after treatment and delayed the intermoult period so that overaged nymphs were detected. CONCLUSION: The results indicate that extracts and triterpenes from Manilkara subsericea act as potent growth inhibitors of phytophagous hemipteran nymphs. It is also concluded that the mixture of several different molecules in the extracts used produces synergic effects that do not occur after using the triterpenes (PFT) alone. These secondary metabolites in the M. subsericea extracts can potentially be used in integrated control programmes against crop pests.

Effect of vitamins, probiotics and protein on semen traits in post-molt male broiler breeders.

The study aimed to investigate the comparative effect of vitamins E and C, probiotics, lower than normal protein level and the combination of these treatments in male broiler breeders after Zn-induced molting. One hundred and eighty birds at 65 weeks of age were divided into six groups (five replicates per group) in a completely randomized block design. Birds were induced to molt by mixing zinc oxide in feed at the rate of 3000 mg/kg of feed. Upon completion of molting, birds were fed different supplements. One group was kept as a control, while the other groups were fed: vitamin E (100 IU/kg), vitamin C (500 IU/kg), probiotics (50 mg/L of water), lower dietary protein level (14%) or the combination of these treatments. Results revealed that vitamins (E and C) supplementation increased (P<0.05) semen volume, however, sperm motility and egg fertility were significantly higher only in vitamin E supplemented group compared to control. The dead sperm percentage decreased (P<0.05) in vitamin C fed group, whereas, sperm concentration did not differ (P>0.05) between the control and treated groups. The results validate the key role of antioxidant vitamins in male broiler breeders' fertility after Zn-induced molting.

Effects of vitamins, probiotics, and protein level on semen traits and some seminal plasma macro- and microminerals of male broiler breeders after zinc-induced molting.

This study was conducted to investigate the effects of vitamin E, vitamin C, probiotics, dietary protein level, and their combination on semen traits and seminal plasma macro- and microminerals in 65-week-old male broiler breeders after zinc-induced molting. One hundred eighty birds were induced to molt by mixing zinc oxide (3,000 mg/kg) in the diet. The birds were divided into six groups (five replicates) by completely randomized design. One group was kept as control (16% CP), while the other five were supplemented with vitamin E (100 IU/kg feed), vitamin C (500 IU/kg feed) probiotics (50 mg/L), protein level (14% CP), and their combination. Semen samples were weekly collected for determination of semen volume, sperm concentration, motility, and dead sperm percentage. Analyses of Na, K, Ca and Mg, Zn, Fe, Mn, and Cu in seminal plasma were also performed. Overall, mean semen volume was significantly high in vitamin E and C supplemented groups compared to control. Overall mean sperm motility was significantly higher in vitamin E supplemented group, whereas dead sperm percentage was significantly lower in the vitamin C group compared to control. Mineral analyses revealed that overall mean seminal plasma Mg increased significantly in vitamin E and C supplemented groups compared to control. Similarly, significantly high overall mean seminal plasma Cu concentration was observed in vitamins E and C and combination groups. It can be concluded that vitamins have a vital role in improving semen quality and bioavailability of Mg and Cu in seminal plasma of the post-molt cockerels.

Effects of manipulating hypothalamic triiodothyronine concentrations on seasonal body weight and torpor cycles in Siberian hamsters.

Siberian hamsters display photoperiodically regulated annual cycles in body weight, appetite, and reproduction. Previous studies have revealed a profound up-regulation of type 3 deiodinase (DIO3) mRNA in the ventral ependyma of the hypothalamus associated with hypophagia and weight loss in short-day photoperiods. DIO3 reduces the local availability of T(3), so the aim of this study was to test the hypothesis that decreased hypothalamic T(3) availability underlies the short-day-induced catabolic state. The experimental approach was to determine whether a local increase in T(3) in the hypothalamus of hamsters exposed to short days could reverse the behavioral and physiological changes induced by this photoperiod. In study 1, microimplants releasing T(3) were placed bilaterally into the hypothalamus. This treatment rapidly induced a long-day phenotype including increased appetite and body weight within 3 wk of treatment and increased fat mass and testis size by the end of the 10-wk study period. In study 2, hypothalamic T(3) implants were placed into hamsters carrying abdominal radiotelemetry implants. Again body weight increased significantly, and the occurrence of winter torpor bouts was dramatically decreased to less than one bout per week, whereas sham-implanted hamsters entered torpor up to six times a week. Our findings demonstrate that increased central T(3) induces a long-day metabolic phenotype, but in neither study was the molt cycle affected, so we infer that we had not disrupted the initial detection of photoperiod. We conclude that hypothalamic thyroid hormone availability plays a key role in seasonal regulation of appetite, body weight, and torpor.

Effect of an insect juvenile hormone analogue, Fenoxycarb on development and oxygen uptake by larval lobsters Homarus gammarus (L.).

Little attention has been focused on the effect of anthropogenic compounds that disrupt the endocrine systems in crustaceans. Consequently, this study investigated the effects of the juvenile hormone analogue (JHA), Fenoxycarb on selected physiological and developmental processes of the zoeal stages in the European lobster, Homarus gammarus. Chronic exposure to Fenoxycarb (50microg L(-1)) resulted in a significant (p < 0.05) reduction in moult frequency and size at moult. Fenoxycarb exposure extended zoeal duration between zoea I to II (p<0.05) and resulted in total inhibition of the moult from zoea II to III. Significantly greater rates of O2 uptake were observed in Fenoxycarb-exposed larvae in comparison with controls (p<0.05). All rates of O2 uptake decreased significantly between 7 and 12d of exposure (p<0.05). At 12d, exposure to the solvent control no longer influenced rates of O2 uptake, but it was not possible to attribute increased O2 uptake to Fenoxycarb exposure directly, as treated individuals did not moult beyond zoea III. The low exposure concentrations of Fenoxycarb, comparable to those used in plant protection, resulted in endocrine disrupted responses in H. gammarus (albeit with little clear, demonstrable effect on metabolism) a finding that could have important ecological and commercial implications.

The effect of mushroom and pokeweed extract on salmonella, egg production, and weight loss in molting hens.

An experiment was conducted to evaluate the effects of mushroom and pokeweed extract alone or in combination with alfalfa meal on Salmonella spp. population, egg production, and weight loss in laying hens during a 10-d molting period. The trial used 54 active laying hens approximately 77 wk of age that were naturally infected with Salmonella spp. The layers were subjected to 1 of 9 treatment groups, replicated 3 times with 2 hens per replicate cage. The treatment conditions were as follows: 1) full-fed + H(2)0 (FFW), 2) full-fed + mushroom (FFM), 3) full-fed + pokeweed (FFP), 4) nonfed + H(2)0 (NFW), 5) nonfed + mushroom (NFM), 6) nonfed + pokeweed (NFP), 7) full-fed alfalfa meal + H(2)0 (FFAW), 8) full-fed alfalfa meal + mushroom (FFAM), and 9) full-fed alfalfa meal + poke-weed (FFAP). The results showed that the base-10 logarithm values of Salmonella from the ceca significantly increased (P

Effects of waterborne uranium on survival, growth, reproduction and physiological processes of the freshwater cladoceran Daphnia magna.

Acute uranium toxicity (48 h immobilisation test) for Daphnia magna was determined in two different exposure media, differing in pH and alkalinity. LC(50) varied strongly between media, from 390+/-40 microgL(-1)U at pH 7 to 7.8+/-3.2 mgL(-1)U at pH 8. According to the free ion activity model uranium toxicity varies as a function of free uranyl concentration. This assumption was examined by calculating uranium speciation in our water conditions and in those reported in the literature. Predicted changes in free uranyl concentration could not solely explain observed differences in toxicity, which might be due to a competition or a non-competitive inhibition of H(+) for uranium transport and/or the involvement of other bioavailable chemical species of uranium. Chronic effects of uranium at pH 7 on mortality, ingestion and respiration, fecundity and dry mass of females, eggs and neonates were investigated during 21-day exposure experiments. A mortality of 10% was observed at 100 microgL(-1)U and EC(10) for reproduction was 14+/-7 microgL(-1)U. Scope for growth was affected through a reduction in feeding activity and an increase in oxygen consumption at 25 microgL(-1)U after 7 days of exposure. This had strong consequences for somatic growth and reproduction, which decreased, respectively, by 50% and 65% at 50 microgL(-1)U after 7 days and at 25 microgL(-1)U after 21 days. Uranium bioaccumulation was quantified and associated internal alpha dose rates from 2.1 to 13 microGyh(-1) were estimated. Compared to the toxicity of other alpha-emitting radionuclides and stable trace metals, our results confirmed the general assumption that uranium chemical toxicity predominates over its radiotoxicity.

Dynamics of innate immune response in Gallus domesticus using two methods of induced molting.

The aim of this study was to compare the ability of laying hen abdominal macrophages during the second production cycle by using two different methods of induced molting. Two groups of Single Comb White Leghorn hens were induced to molt at the end of their first production cycle using feed restriction and ZnO supplementation. Macrophages were isolated from the abdomen and in vitro cytotoxic ability, at which point macrophage bactericidal moiety nitric oxide (NO) was recorded. Serum IgM and IgG titers against sheep red blood cells (SRBC) were determined at various stages: before molting (BM), 5% production level (5P), peak production stage (PP) and at the end of production (EP) level after fast and Zn-induced molt. Macrophages adherence percentage remained unaffected (p< or =0.05) during all production cycles, whereas the macrophage engulfment percentage and engulfment/cell was significantly higher (p< or =0.05) at PP in both fast and Zn-induced molted groups, as compared to all other studied stages. Macrophage NO production was increased (p< or =0.05) at PP and after SRBC and lipopolysaccrides (LPS) stimulus, when molted with ZnO supplementation. Serum total antibody titer against SRBC increased serum IgG and IgM titers during the second production cycle by Zn-induced molt. However, molting stress greatly reduced IgG and IgM production at the 5P stage. Serum Zn concentration increased with the onset of production but decreased at the EP stage irrespective of their molting regimes. Our results validate the strengthened innate and acquired immune response during the second production cycle after Zn-induced molting instead of fasting.

Relationship between dose of emamectin benzoate and molting response of ovigerous American lobsters (Homarus americanus).

A widely-prescribed treatment to control sea lice on cultured salmon is the administration of feed medicated with SLICE (active ingredient emamectin benzoate (EMB)). High doses of EMB can disrupt the molt cycle of ovigerous American lobsters, causing them to enter proecdysis prematurely and lose their attached eggs when the shell is cast. To determine the dose response to EMB, lobsters were forced to ingest doses that ranged from 0.05 to 0.39 microg g(-1). A significant proportion of lobsters given doses of 0.39 and 0.22 microg g(-1) (37% and 23%, respectively) molted prematurely, almost a year earlier than the control group. All the lobsters in the 0.05 and 0.12 microg g(-1) groups molted at the normal time and the mean time of molt was similar to that of the control group. Thus, the no-observed-effect level (NOEL) and lowest-observed-effect level (LOEL) of EMB on the molt cycle were 0.12 and 0.22 microg EMB g(-1) lobster, respectively. To acquire the LOEL, a 500-g lobster would have to consume 22 g of salmon feed medicated with SLICE at a level of 5 microg EMB g(-1) feed.

Effects of alfalfa and fructooligosaccharide on molting parameters and bone qualities using dual energy X-ray absorptiometry and conventional bone assays.

The aim of this study was to evaluate effects of alfalfa and fructooligosaccharides (FOS) on molting performance and bone parameters compared with the conventional feed withdrawal molting procedure. A total of 36 Single Comb White Leghorn hens (84 wk of age) were used for this experiment. The hens were divided into 6 treatment groups with 6 birds per treatment: pre-trial control (PC), full fed (FF), feed withdrawal (FW), 100% alfalfa (A100), A100 + 0.375% FOS (A100L), and A100 + 0.75% FOS (A100H). At the end of the 9-d molt period, hens were euthanized, and tibia and femurs were collected to evaluate bone qualities using dual-energy x-ray absorptiometry (DXA), Instron (Model 1011 Instron Universal Testing Machine, Instron Corp., Canton. MA), and conventional bone assays. Egg production was recorded during the molting period to evaluate first day out of production, and ovary was also collected to measure ovary weight. Alfalfa molting diets had comparable molting parameters, such as percentage of BW loss, ovary weight, and first day out of egg production, to the conventional feed withdrawal molting procedure, and FOS supplementation did not have any detrimental effects on molting performance. Conventional bone assay and DXA results suggest that hens lose a considerable amount of bone minerals during a molting period. The tibia and femur bone strengths of the FF, FW, A100, and A100L hens were significantly lower than the PC hens, whereas hens fed A100H had similar tibia bone breaking strength to that of the PC hens. The bone parameters measured by conventional assays, bone breaking strength measured by Instron, and bone density and mineral content measured by DXA were highly correlated to each other.