Role of FSH, numbers of FSH receptors and testosterone in the regulation of inhibin secretion during the seasonal testicular cycle of adult rams

The regulation of inhibin secretion has not been elucidated fully in male ruminants. The aim of this study was to determine the relative importance of FSH and testosterone concentrations, and FSH receptors, in the control of secretion of immunoactive inhibin in rams. In Expt 1, temporal changes in hormone concentrations and testicular FSH binding were determined for two groups of rams (n = 4) kept under opposite, alternating 4 month periods of long (16 h light:8 h dark) and short (8 h light:16 h dark) days. Testicular biopsies (1-2 g) were collected when the testes were regressed, redeveloping, redeveloped and regressing. In Expt 2, separate groups of rams (n = 4) kept under natural photoperiod (latitude 45 degrees 48 minutes N) were designated as controls or passively immunized (for 3 weeks) with sufficient oestradiol antiserum to increase testosterone secretion without altering LH and FSH; this was done when the testes were regressed (non-breeding season) and redeveloped (breeding season). In both groups of rams (Expt 1), 'seasonal' increases in FSH concentrations began a few weeks earlier than did increases in inhibin concentrations. FSH reached maximum concentrations during testicular recrudescence, whereas numbers of FSH receptors in the testis and circulatory inhibin concentrations did not reach peak values until the testes were fully developed. Numbers of FSH receptors per testis, but not FSH concentration, were positively correlated (r = 0.65) with inhibin concentrations across the four stages of the testicular cycle. Near the end of testicular recrudescence early in the breeding season (Expt 2), relatively high FSH concentration was associated with increased abundance of FSH receptor mRNA (90%) and number of receptors (45%) in the testis and increased inhibin concentrations (50%), compared with when the testes were regressed. Moderate, physiological increases in testosterone secretion in immunized rams did not affect inhibin in either season. These results indicate that: (i) FSH stimulation of immunoactive inhibin secretion by Sertoli cells as testes recrudesce is via increases in secretion (early) and cognate receptors (late); (ii) FSH upregulates the synthesis of its own receptor late in recrudescence; and (iii) the positive correlation (r = 0.70) observed between circulatory testosterone and immunoactive inhibin does not reflect a causal relationship.     

The fate of fungicide and insecticide residues in Australian wine grape by-products following field application

Pesticides applied to grape vines before harvest may concentrate in the grape seed due to their high oil solubility. Twenty-four samples of grape marc, representing a range of red and white wine grape varieties, were collected and analysed for selected fungicides and insecticides. Fifteen of the 24 samples were matched with insecticide and fungicide application diaries. Residue concentrations of the fungicides, procymidone, iprodione, cyprodinil, fenhexamid, fludioxinil, pyrimethanil and trifloxystrobin, and the insecticides, indoxacarb and tebufenozide, were higher in grape seed oil and grape seed meal than in the fruit and the marc. The relative concentrations were approximately proportional to the octanol to water partition coefficients, log K_ow. A range of other fungicides and insecticides were detected but were not significantly concentrated in the oil and seed meal relative to fruit and marc. The presence of pesticide residues in grape seed oil and grape seed meal will impact on the possibility of producing these wine by-products.     

Ovarian stimulation with FSH reduces phosphorylation of gonadotrope progesterone receptor and LH secretion in the rat

Administration of human FSH (hFSH) to cyclic rats during the dioestrous phase attenuates progesterone receptor (PR)-dependent events of the preovulatory LH surge in pro-oestrus. The increased bioactivity of the putative ovarian gonadotropin surge inhibiting/attenuating factor induced by hFSH treatment is not associated with a decrease in PR protein expression, and the possibility of its association at a PR posttranslational effect has been raised. The present experiments aimed to analyse PR phosphorylation status in the gonadotrope of rats with impaired LH secretion induced by in vivo hFSH injection. Two experimental approaches were used. First, incubated pro-oestrous pituitaries from hFSH-injected cycling and oestrogen-treated ovariectomized (OVX) rats were used to analyze the effect of calyculin, an inhibitor of intracellular phosphatases, on PR-dependent LH release, which was measured in the incubation medium by RIA. Second, pituitaries taken from hFSH-injected intact cycling and OVX rats and later incubated with P or GNRH1 were used to assess the phosphorylation rate of gonadotrope. The latter was analysed in formalin-fixed, paraffin-embedded tissue sections by immunohistochemistry using a MAB that recognizes the phosphorylated (p) form of PR at Ser294. Calyculin reduced the ovary-mediated inhibition of hFSH in GNRH1-stimulated LH secretion. In addition, the immunohistochemical expression of pSer294 PR was significantly reduced after ovarian stimulation with hFSH in pituitaries from pro-oestrous rats incubated with P or GNRH1. Altogether, these results suggested that the ovarian-dependent inhibitory effect of FSH injection on the preovulatory LH secretion in the rat may involve an increase in dephosphorylation of PR.     

Accumulation, whole-body depletion, and debromination of decabromodiphenyl ether in male sprague-dawley rats following dietary exposure

Decabromodiphenyl ether (BDE-209) isthe major component in the flame-retardant formulation DecaBDE which is incorporated into numerous consumer goods ranging from upholsteries to electronics. Because of the high volume of DecaBDE produced, its presence in consumer products and the environment, and the finding of BDE-209 in the blood of exposed workers, the extent of bioavailability, persistence, and potential debromination are important issues. To measure the bioconcentration, distribution, reductive debromination, and whole-body half-lives of BDE-209 after multiple low doses in an animal model, we dosed rats with a commercial DecaBDE (0.3 microg/g of diet) for 21 days and measured tissue polybrominated diphenyl ether levels during a 21 day withdrawal period. BDE-209, three nona-BDEs, and four octa-BDEs accumulated in the rats and distributed proportionately throughout the body. Only 5% of the total BDE-209 dose was present as parent compound in the rats after 21 days of dosing and <4% in the feces, suggesting extensive metabolism. A nona-BDE (BDE-207) and two octa-BDEs (BDEs-201 and -197) appeared to form via meta-debromination(s) of BDE-209 to a minimal extent (1% of the total BDE-209 dose). The wholebody half-lives tended to increase with decreasing bromination; however, two octa-BDEs, presumably forming from debromination, increased in the rats after 21 days of withdrawal and demonstrated the potential for BDE-209 to form more persistent lipophilic compounds in vivo.     

Functional consequence of exposure to dieldrin on mammary development and function.

The effect of dieldrin (Dln) on the development of the mammary gland and on functional parameters of CID-9 mammary cells in culture was investigated. One-month-old Sprague-Dawley female rats were bred and received intraperitoneal injection with 2.5 or 15 microM Dln during the last trimester of their gestation. Mammary glands of 15-microM Dln-treated rats showed immature alveolar structures by day 18 of gestation and abundant adipose tissue. Dln-treated rats had a lower number of pups, and the weight of pups between days 14 and 31 of age compared with non-treated rats was significantly lower. Long-term exposure of CID-9 mammary cells, cultured under non-differentiation conditions, on plastic, or under differentiation permissive conditions, dripped with EHS-matrix, to 5 or 25 microM Dln was detrimental to cell growth. The short-term effect of Dln exposure (up to 9 h) on CID-9 cells, under the same culture conditions, did not affect their beta-casein mRNA levels, but induced apoptosis, down regulated gap junction intracellular communication and induced IL-6 and TNF-alpha expression.     

固相萃取-高效液相色谱法测定蔬菜中三唑酮、 百菌清和乙烯菌核利残留量

目的建立固相萃取-高效液相色谱-二极管阵列检测法测定蔬菜中三唑酮、百菌清和乙烯菌核利残留量的方法。方法蔬菜样品用乙腈超声提取,加入氯化钠进行盐析脱水,提取液过中性氧化铝柱净化,用正己烷/丙酮(90:10,V:V)淋洗液洗脱,洗脱液水浴氮吹近干,流动相定容后采用高效液相色谱法进行测定,外标法定量。结果三唑酮、百菌清和乙烯菌核利质量浓度在0.02~5.0 mg/L范围内与其峰面积呈良好的线性关系,方法检出限为0.02 mg/kg,加标回收率为89.5%~105.1%,精密度(relative standard deviation,RSD)为0.85%~4.25%。结论该方法操作简单、准确,可应用于蔬菜中三唑酮、百菌清和乙烯菌核利的检测。     

Changes in liking for a no added salt soup as a function of exposure

Multiple exposures have been shown to increase preference for novel foods or flavours. This “mere exposure” effect is also well known anecdotally for changes in preference for tastants within foods, for example reducing sugar in tea or coffee. However, to date, this phenomenon has received little scientific attention. The present study addressed this issue in relation to changes in preference for salt within soup. Following an initial assessment of liking, familiarity and saltiness of six soups varying in salt content (0–337 mg NaCl/ml), 37 participants, previously assessed for their preferred salt level in soup, were allocated to either an exposure group that received 20 ml soup samples with no added salt, to a group that received a 280 ml bowl of this soup, or to a control group that received 20 ml soup samples containing salt at 280 mg/100 g (within normal, commercial range). Soups were presented on eight occasions, at approximately daily intervals. The two groups receiving the no added salt soup showed increases in liking starting at the third exposure, and also evident in a repeat assessment following the exposures. Increases in familiarity of the no added salt soup were also evident during exposure. Rated saltiness of all soups increased as a function of exposure, so a change in saltiness perception could not account for changes in liking for just the no added salt soups. These data suggest that simple exposure to the taste of the no added salt soup was sufficient to increase liking to a level equivalent to the initially more preferred salt level.     

Changes in bovine milk secretion following intramammary infusions of concanavalin A, oyster glycogen, or water

Effects of sterile intramammary infusion of Concanavalin A on milk secretion were contrasted with infusion of oyster glycogen or water. Twenty-four cows were infused intramammary with 100 mg Concanavalin A, oyster glycogen in 20 ml water, or with 20 ml water alone. Concentrations of lactose, somatic cells, immunoglobulins G and A, serum albumin, and activity of N-acetyl-B-D-glucosaminidase were determined in milk. Blood N-acetyl-B-D-glucosaminidase activity and concentrations of blood immunoglobulins G and A and serum albumin were determined. Oyster glycogen and concanavalin A caused inflammation in treated quarters; peak elevations of milk somatic cell counts, serum albumin, immunoglobulin G concentrations, and N-acetyl-B-D-glucosaminidase activity were at 12 to 36 h following treatment. Milk production and lactose concentration were reduced by oyster glycogen and Concanavalin A. Selective indices of relative accumulation of milk immunoglobulins decreased following Concanavalin A and oyster glycogen, whereas the N-acetyl-B-D-glucosaminidase activity selective index generally remained unchanged. Inflammation reduced the selective accumulation of immunoglobulins, and absence of change in the N-acetyl-B-D-glucosaminidase selective index indicated that blood is not a major source of milk N-acetyl-B-D-glucosaminidase.     

Bioaccumulation dynamics and modeling in an estuarine invertebrate following aqueous exposure to nanosized and dissolved silver

Predicting the environmental impact of engineered nanomaterials (ENMs) is increasingly important owing to the prevalence of emerging nanotechnologies. We derived waterborne uptake and efflux rate constants for the estuarine snail, Peringia ulvae, exposed to dissolved Ag (AgNO(3)) and silver nanoparticles (Ag NPs), using biodynamic modeling. Uptake rates demonstrated that dissolved Ag is twice as bioavailable as Ag in nanoparticle form. Biphasic loss dynamics revealed the faster elimination of Ag from Ag NPs at the start of depuration, but similar slow efflux rate constants. The integration of biodynamic parameters into our model accurately predicted Ag tissue burdens during chronic exposure with 85% of predicted values within a factor of 2 of observed values. Zeta potentials for the Ag NPs were lower in estuarine waters than in waters of less salinity; and uptake rates in P. ulvae were slower than reported for the freshwater snail Lymnaea stagnalis in similar experiments. This suggests aggregation of Ag NPs occurs in estuarine waters and reduces, but does not eliminate, bioavailability of Ag from the Ag NPs. Biodynamic modeling provides an effective methodology to determine bioavailable metal concentrations (originating from metal and metal-oxide nanoparticles) in the environment and may aid future ENM risk assessment.     

Gene expression and secretion of LH and FSH in relation to gene expression of GnRH receptors in the brushtail possum (Trichosurus vulpecula) demonstrates highly conserved mechanisms

In eutherian mammals, the gonadotrophins (LH and FSH) are synthesized and stored in gonadotroph cells under the regulation of multiple mechanisms including GnRH. Very little is known about the regulation of gonadotrophin secretion and storage in pituitary glands of marsupials. This study revealed, using quantitative PCR and heterologous RIA techniques, that LHB mRNA expression levels remained constant over the oestrous cycle, regardless of the presence of a preovulatory LH surge, which is characteristic of a hormone secreted under regulation. Our sampling regime was unable to detect pulses of LH during the follicular phase, although GNRHR mRNA levels had increased at this time. Pulses of LH were, however, detected in the luteal phase of cycling females, in anoestrus females and in males. There was a positive correlation between gene expression of FSHB and plasma levels of FSH at different stages of the oestrous cycle and no pulses of FSH were detected at any time; all characteristics of a hormone secreted via the constitutive pathway. Using in situ hybridisation and immunohistochemistry methods, we determined that mRNA expression of LHB and FSHB, and protein storage of gonadotrophins exhibited a similar pattern of localisation within the pituitary gland. Additionally, sexual dimorphism of gonadotroph populations was evident. In summary, these findings are similar to that reported in eutherians and considering that marsupial evolution diverged from eutherians over 100 million years ago suggests that the regulation of gonadotrophins is highly conserved indeed.     

Cathepsin B and glutathione peroxidase show differing transcriptional responses in the grass shrimp, Palaemonetes pugio following exposure to three xenobiotics

The common molecular biology techniques, suppressive-subtractive hybridization (SSH) and semi-quantitative real-time PCR (SQRT-PCR), were used to identify differentially expressed genes in the grass shrimp, Palaemonetes pugio following exposure to three different xenobiotics. Lab-acclimated adult male grass shrimp were exposed to empirically derived 96-hr male-specific LC50 concentrations of fipronil (FP, a phenylpyrazole GABA disrupting pesticide), endosulfan (ES, a cyclodiene GABA disrupting pesticide), or cadmium (Cd), as well as a control (CC). An SSH gene expression library was constructed from surviving shrimp from the fipronil and control exposures. Clones obtained by SSH were identified by searching against the NCBI website. A total of 42 genes were identified that were up-regulated by FP exposure, and 47 that were down-regulated. A subset of the affected genes was tested with SQRT-PCR to verify responsiveness to fipronil, as well as to endosulfan and cadmium. Two genes showed strong and significant responses to the exposures: glutathione peroxidase was significantly up-regulated by all three exposures, while Cathepsin B was strongly responsive to the two pesticides, but not to cadmium.     

Cell death, stress-responsive transgene activation, and deficits in the olfactory system of larval zebrafish following cadmium exposure

Cadmium (Cd) is a well-described environmental pollutant known to have adverse effects in fish, including behavioral deficits. We have previously reported the development of an in vivo system that utilizes hsp70 gene activation as a measure of acute 3 h cadmium toxicity in whole living transgenic zebrafish larvae carrying a stably integrated hsp70-enhanced green fluorescent protein (eGFP) reporter gene. Here, we report that activation of this transgene in olfactory epithelium of zebrafish larvae during 96 h sublethal Cd exposure is predictive of cadmium-induced cell death, altered histological and surface organization of the epithelium, and changes in olfactory dependent behavior. The transgene is first activated in the olfactory epithelium at concentrations below those giving rise to significant defects, but exhibits a more robust response following exposure to Cd at concentrations that begin to cause significant cell death, morphological alterations, and behavioral deficits. Further, the data show that Cd-induced olfactory deficits reported previously in juvenile and adult fish can also occur during larval stages of fish development, and that such behavioral deficits are closely associated with cell death and structural alterations in the olfactory epithelium.     

Body composition and hormonal effects following exposure to mycotoxin deoxynivalenol in the high-fat diet-induced obese mouse

Scope: To characterize the effects of ingesting the common foodborne mycotoxin deoxynivalenol (DON) on body weight and composition in the high‐fat (HF) diet‐induced obese mice, a model of human obesity. Methods and results: Female B6C3F1 mice were initially fed HF diets containing 45% kcal (HF45) or 60% kcal (HF60) as fat for 94 days to induce obesity. Half of each group was either continued on unamended HF diets or fed HF diets containing 10 mg/kg DON (DON‐HF45 or DON‐HF60) for another 54 days. Additional control mice were fed a low‐fat (LF) diet containing 10% kcal as fat for the entire 148‐day period. DON induced rapid decreases in body weights and fat mass, which stabilized to those of the LF control within 11 days. These effects corresponded closely to a robust transient decrease in food consumption. While lean body mass did not decline in DON‐fed groups, further increases were suppressed. DON exposure reduced plasma insulin, leptin, insulin‐like growth factor 1, and insulin‐like growth factor acid labile subunit as well as increased hypothalamic mRNA level of the orexigenic agouti‐related protein. Conclusion: DON‐mediated effects on body weight, fat mass, food intake, and hormonal levels in obese mice were consistent with a state of chronic energy restriction.     

Morphological changes of temperature- and pH-stressed Salmonella following exposure to cetylpyridinium chloride and nisin

The outer membrane of Gram-negative bacteria such as Salmonella, act as a permeability barrier, preventing nisin gaining access to the cytoplasmic membrane. If the outer membrane permeability is reduced, however, Gram-negative bacteria can show nisin sensitivity. In this study, temperature stresses (heating, chilling and freezing), pH stress (pH 4.5, 5.0, 6.0) and cetylpyridinium chloride (CPC)-nisin treatment were used to alter the outer membrane permeability of Salmonella, producing a loss of barrier function and reduced resistance to nisin. The morphological changes in Salmonella were examined using scanning electron microscopy. Temperature and pH-stressed S. typhimurium cells, untreated and treated with CPC-nisin had perturbed cell morphology, including apparent indentations and craters in the cell surfaces and collapsed amorphous bodies.