Mice learn to identify and discriminate sugar solutions based on odor cues.

This study examined how olfaction impacts ingestive responses of mice to sugar solutions. Experiment 1 asked whether naïve C57BL/6 (B6) mice could identify 1 M glucose, fructose, or sucrose solutions based on odor cues, during a 30-min 2-bottle acceptability test. We tested mice both before and after they were rendered anosmic with ZnSO4 treatment. We used 2 indirect measures of odor-mediated response: number of trials initiated and latency to initiate licking. Before ZnSO4 treatment, the mice learned how to identify 1 M glucose and fructose (but not sucrose) solutions based on odor cues. ZnSO4 treatment eliminated their ability to identify the glucose and fructose solutions. Experiment 2 asked whether 2 d of exposure to a 1 M glucose, fructose, or sucrose solution improved the identification of the same sugar solution. Following exposure, the B6 mice identified all 3 sugar solutions based on odor cues. Experiment 3 asked whether T1R3 knockout mice (i.e. mice lacking the T1R3 subunit of the T1R2 + R3 sweet taste receptor) could learn to discriminate 0.44 M glucose and fructose solutions based on odor cues. All mice were subjected to a 1-h preference test, both before and after exposure to the 0.44 M glucose and fructose solutions. During exposure, the experimental mice received ZnSO4 treatment, whereas the control mice received saline treatment. Before exposure, neither type of mouse preferred the glucose solution. After exposure, the control mice preferred the glucose solution, whereas the experimental mice did not. Our results reveal that mice can learn to use odor cues to identify and discriminate between sugar solutions.

Fabrication of bacterial cellulose/PVP nanofiber composites by electrospinning.

This study aimed to address a significant challenge in the application of bacterial cellulose (BC) within tissue engineering and regenerative medicine by tackling its inherent insolubility in water and organic solvents. Our team introduced a groundbreaking approach by utilizing zinc sulfate (ZnSO4) as a solvent to render BC soluble, a novel contribution to the literature. Subsequently, the obtained soluble BC was combined with varying concentrations of polyvinylpyrrolidone (PVP). Notably, we pioneered the fabrication of BC/PVP composite scaffolds with customizable fiber surface morphology and regulated degradation rates through the electrospun technique. Several key parameters, such as PVP concentration (8%, 15%, 12%, and 20% w/v), applied voltage (22, 15, and 12 kV), and a fixed nozzle-collector distance of 10 cm with a flow rate of 0.9 mL/h, were systematically evaluated so as to find the optimum parameter created BC/PVP product with electrospun. For electrospun BC/PVP products, a voltage of 12 kV was found to be optimal. Intriguingly, our findings revealed enhanced cell adhesion and proliferation in BC/PVP electrospun products compared with using PVP membranes alone. Specifically, cell viability for PVP and PVP/BC electrospun products was determined as 50.73% and 79.95%, respectively. In terms of thermal properties, the BC/PVP electrospun product exhibited a mass loss of 82.6% at 380°C, while PVP alone experienced 90.2% mass loss at around 280°C. Furthermore, the protein adhesion capacities were measured at 62.3 ± 1.2 µg for PVP and 99.4 ± 2 µg for BC/PVP electrospun products, whereas product showed no biodegradation over 28 days and had notable water retention capacity. In conclusion, our research not only successfully attained nanofiber morphology but also showcased enhanced cell attachment and proliferation on the BC/PVP electrospun product.

Safety Assessment of Zinc Salts as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of 27 inorganic and organometallic zinc salts as used in cosmetic formulations; these salts are specifically of the 2+ (II) oxidation state cation of zinc. These ingredients included in this report have various reported functions in cosmetics, including hair conditioning agents, skin conditioning agents, cosmetic astringents, cosmetic biocides, preservatives, oral care agents, buffering agents, bulking agents, chelating agents, and viscosity increasing agents. The Panel reviewed the relevant data for these ingredients, and concluded that these 27 ingredients are safe in cosmetics in the present practices of use and concentration described in this safety assessment when formulated to be non-irritating.

Modulating the transcriptomic profile of multidrug-resistant Klebsiella pneumoniae biofilm formation by antibiotics in combination with zinc sulfate.

BACKGROUND: Klebsiella pneumoniae is a significant healthcare-associated pathogen. We investigated the antimicrobial interaction pattern between zinc sulfate and antibiotics against K. pneumoniae biofilm on the phenotypic and genotypic levels. METHODS: Determining the minimum biofilm inhibitory concentrations and the transcriptomic profile of K. pneumoniae biofilm formation genes post-treatment were carried out to evaluate the effect on the phenotypic and genotypic levels, respectively. RESULTS: Zinc enhanced the antibiofilm potentials of cephalosporins, aminoglycosides, and ertapenem, whereas it antagonizes the effectiveness of fluoroquinolones and meropenem on the phenotypic level. On the molecular level, zinc enhanced the anti-biofilm efficacies of cephalosporins (cefotaxime, ceftriaxone, ceftazidime, cefpirome, and cefepime) via down-regulating the expression of biofilm-related genes by 18-, 38-, 5-, 77- and 2-folds, respectively. Zinc in combination with aminoglycosides (kanamycin, gentamicin, and amikacin) reduced the expression of biofilm-related genes by 40-, 2602- and 20-folds, respectively, and by 2-folds in combination with ertapenem. However, a reduction in the down-regulatory potentials of fluoroquinolones was recorded following combination with zinc by 2-, 2-, 15- and 14-folds, respectively, and an up-regulation in the expression levels of the tested genes by 2-folds in the case of zinc/meropenem combination. CONCLUSIONS: Results revealed variable interaction patterns between different antibiotics in combination with zinc. Current findings also shed light on the antibiofilm potentials of zinc/antibiotics combinations especially when combining zinc with fluoroquinolones or meropenem to avoid their antagonistic effects.

Effects of two concentrations of dietary tribasic zinc sulfate on growth performance, gut morphology, and zinc transporter expression levels in pigs.

Tribasic zinc sulfate (TBZ) is insoluble in water and chemically less active than zinc sulfate, making it more suitable to be used in pig diet. To investigate the effects of TBZ on the growth performance, gut morphology, and zinc transporter expression levels, we performed a single-factor experiment and 168 pigs were allocated to three groups with seven pens per treatment. Pigs were either fed a basal diet without zinc supplementation (control group), or a basal diet supplemented with TBZ at 100 mg/kg diet (LTBZ group) or 1000 mg/kg diet (HTBZ group). We found that daily weight gain and feed intake were higher in the LTBZ group than in the HTBZ and control groups. The pigs in the LTBZ group had a higher villus height and villus height/crypt depth ratio when compared with other pigs. Moreover, the pigs in the LTBZ group exhibited higher mRNA expression levels of solute carrier family 39 and lower expression levels of solute carrier family 30 than those fed the HTBZ-supplemented diet. Together, these results indicate that TBZ may potentially be used as a dietary zinc source for young growing pigs and that dietary supplementation with LTBZ benefits growth performance and gut morphology.

Enhanced ß-glucan and pullulan production by Aureobasidium pullulans with zinc sulfate supplementation.

The effects of mineral salts on the production of exopolysaccharides, including ß-glucan and pullulan, by Aureobasidium pullulans CCTCC M 2012259 were investigated. Zinc sulfate at certain concentrations decreased dry biomass but favored to the biosynthesis of both exopolysaccharides. When 100 mg/L zinc sulfate was added to the fermentation medium, production of ß-glucan and pullulan increased by 141.7 and 10.2%, respectively, when compared with that noted in the control without zinc sulfate addition. To reveal the physiological mechanism underlying improved ß-glucan and pullulan production, key enzymes activities, energy metabolism substances, intracellular uridine diphosphate glucose (UDPG) levels, and gene expression were determined. The results indicated that zinc sulfate up-regulated the transcriptional levels of pgm1, ugp, fks, and kre6 genes, increased activities of key enzymes involved in the biosynthesis of UDPG, ß-glucan and pullulan, enhanced intracellular UDPG content, and improved energy supply, all of which contributed to the increment in ß-glucan and pullulan production. The present study not only provides a feasible approach to improve the production of exopolysaccharides but also contributes to better understanding of the physiological characteristics of A. pullulans.

Efficacy of zinc sulfate on indirect hyperbilirubinemia in premature infants admitted to neonatal intensive care unit: a double-blind, randomized clinical trial.

BACKGROUND: Hyperbilirubinemia is a common neonatal problem. Studies conducted on the effectiveness of zinc salts on serum indirect bilirubin levels in newborns have yielded different results, all calling for further research. This study aimed to determine the effect of oral zinc sulfate on indirect hyperbilirubinemia in preterm infants admitted to the neonatal intensive care unit. METHODS: A randomized double-blind clinical trial was performed in the neonatal intensive care unit of Vali-e-Asr Hospital in Birjand, Iran. The study population comprised neonates aged between 31 and 36 gestational weeks, who required phototherapy in the neonatal intensive care unit. A total of 60 neonates were selected by census and allocated into an experimental group and a control group. In addition to phototherapy, the experimental group received 1 cc/Kg zinc sulfate syrup (containing 5 mg/5 cc zinc sulfate; Merck Company, Germany), and the control group received a placebo syrup (containing 1 cc/kg sucrose). Data were analyzed in SPSS-21 software using the independent t-test, repeated-measures ANOVA, Bonferroni post-hoc test, and Mann-Whitney test. P-values smaller than 0.05 were considered significant. RESULTS: Bilirubin level changes in the experimental and control groups six hours after intervention were - 1.45 ± 3.23 and - 0.49 ± 0.37 (p = 0.024), respectively. The changes 24 and 48 h after intervention were-3.26 ± 2.78 and - 1.89 ± 1.20 (p = 0.017) in the experimental group and - 4.89 ± 2.76 and - 3.98 ± 2.32 (p = 0.23) in the control group, respectively. There was no significant difference in the phototherapy duration between the two groups (p = 0.24). CONCLUSIONS: The results of this study showed that the use of zinc sulfate syrup in preterm infants with indirect hyperbilirubinemia significantly reduced bilirubin levels within 48 h of treatment. TRIAL REGISTRATION: Trial registration: IRCT, IRCT2015120825439N1. Registered 21 February 2016, http://irct.ir/trial/21277.

Toxicity assessment of zinc sulfate: A commonly used compound.

Because zinc sulfate (ZnSO4) is widely used in many fields such as biomedicine, electronics, and chemistry, it is important to evaluate its toxic effects. In this study, the cyto-genotoxic effects of ZnSO4 on meristematic cells in the root tip of Allium cepa L. were investigated. After calculating the effective concentration (EC50 = 70 ppm) of ZnSO4, A. cepa root tip cells were suspended for 24, 48, 72, and 96 h in solutions of 35 ppm (EC50/2), 70 ppm (EC50), and 140 ppm (EC50 × 2) concentrations. Using the counts of dividing cells, the mitotic index (MI) was calculated. Chromosome aberration index (CAI) was determined from percentages of abnormal cells. When the obtained data were statistically evaluated, it was determined that all application concentrations caused a significant decrease in MI and an increase in CAI compared to the control group (distilled water). It was concluded that increased ZnSO4 dose concentrations and exposure times caused cytotoxicity and genotoxicity in the root cells of A. cepa L.

Valorisation of waste galvanizing dross: Emphasis on recovery of zinc with zero effluent strategy.

Galvanizing dross-a waste product from steel industries but it can be a potential secondary resource for zinc through urban mining and recycling. In this concern, a novel and scalable recycling route with zero effluent strategy is developed for the recovery of zinc from galvanizing dross as high grade zinc salts along with value-added products through hydrometallurgical processing. In particular, as-such dross block was leached in 9% (v/v) sulphuric acid medium, wherein strong hydrogen gas effervescence results in alleviating the pulverization and stirring requirements; which are material and energy intensive. Leached zinc is purified and recovered as high purity ZnSO4.(H2O/7H2O) and Zn3(PO4)2.4H2O through controlled crystallization and phosphate precipitation respectively; which find application in fertilizers and anti-corrosive paints. Temperature difference method was opted for the crystallization of zinc sulfate salts, wherein 70 °C and 30 °C were found to be stability range of crystallization of ZnSO4.H2O and ZnSO4.7H2O respectively. ZnSO4-H2O phase diagram is developed using Factsage calculations to corroborate crystallization study. Moreover, exhaustive thermodynamic analysis of Zn2+-PO43--H2O system at 303 K on precipitation of zinc phosphate using di-ammonium hydrogen phosphate (80-240 g/L) is conducted and the results reveal that with increasing pH (3-6), intermediate hydrogen phosphate species (H3PO4, H2PO4- and H2PO42-) decompose to produce stable PO43- ions leading to zinc phosphate precipitation. Impurity like Iron and supernatant solution left after crystallization are recovered as hydrated iron-calcium sulfate mixture and ammonium sulfate salt respectively. This explored route is economical and easily adaptable with zero effluents, therefore, transcends serious challenges in terms of energy requirement, scale-up and effluent generation.

Evaluation of acquired passive immunity in mule foals up to 60 days of age.

Ten mule foals were used to investigate serum IgG concentration. Blood was collected from mares and foals on the day following parturition (D1), at 48 and 72 hr after birth (D2 and D3), and on D7, D14, D21, D28, D35, D42, and D60. Serum IgG concentration was determined by zinc sulfate turbidity test and was above 400 mg/dl at all time points, except for one foal on D2. Mean values were above 800 mg/dl from D1 to D7 and at D60. The difference between mares and foals at each collection time was significant, except at D1. For all other days, foal IgG values were lower than the mare IgG values. Mean IgG concentrations were lower from D14 to D42 compared with D1 and D60. The results show that the critical period for the mule foal is at D28, which can be a vulnerable window for infections. The variation pattern in IgG values is similar to that in data published for horse and donkey foals. There are no published studies to date on the subject, and the present contribution enables further understanding of the newborn mule foal.

A review of diagnostic tests for diagnosing failure of transfer of passive immunity in dairy calves in New Zealand.

The aim of this review is to critically assess the test characteristics and practicality of published data on direct and indirect tests for diagnosing failure of transfer of passive immunity (FPT) in dairy calves in New Zealand, to provide recommendations for veterinary practitioners, and to examine the recommended sample size for assessing herd-level prevalence of FPT and the confidence in the results obtained. The definition of FPT is based on measurement of concentrations of IgG in serum of neonatal calves after colostrum intake. The gold standard method for measurement of concentrations of IgG is radial immunodiffusion. However its cost, requirements for laboratory equipment, and the time taken to obtain results have meant that alternative tests have been developed. The turbidimetric immunoassay and ELISA also directly measure concentrations of IgG. Indirect tests include measurement of concentrations of total proteins (TP) in the laboratory or using a refractometer, γ-glutamyl transferase (GGT) activity, and the zinc sulfate turbidity (ZST) test. Of the indirect tests, measurement of concentrations of TP in the laboratory or using a refractometer combine high specificity and sensitivity with a consistent association with concentrations of IgG in calves between 1-7 days of age. Using a refractometer is less accurate than direct measurement in a laboratory, but is still a suitable test if low cost and speed are important. Although GGT activity is strongly associated with concentrations of IgG in serum, the relationship varies with time after birth. Therefore the target thresholds change with time, increasing error compared to the measurement of concentrations of TP in serum. Similarly, factors other than total concentrations of IgG have a significant effect on the association with ZST test, complicating interpretation. Thus, when direct measurement of concentrations of IgG is not feasible, the recommendation is that concentrations of TP in serum should be used as the diagnostic test for diagnosis of FPT, providing calves are not dehydrated. Using a sample size of 12 calves is suitable for estimating whether the herd-level prevalence of FPT is <20% or >20%, if there are no calves or >5 calves diagnosed with FPT, respectively, but is limited in diagnostic confidence when 1-4 calves test positive. Diagnostic interpretation can be significantly improved if tests of FPT are used alongside information on the likely risk of FPT on the tested farm.

Efficacy of zinc sulfate on concurrent chemoradiotherapy induced taste alterations in oral cancer patients: A double blind randomized controlled trial.

OBJECTIVES: To observe the efficacy of zinc sulfate on taste alterations in oral cancer patients receiving concurrent chemotherapy with radiotherapy. METHODS: Seventy patients were randomly assigned to both intervention and control group at Oncology Section of Atomic Energy Medical Centre Karachi from September 2017 to March 2018. One group received zinc sulfate capsules (50 mg TDS daily after meals) and the other group received placebo (thrice after meals). Patients were advised to start taking capsules on the first day of their chemoradiation. Both the groups continued the capsules a month after their CCRT ended. RESULTS: Sweet taste was most effected by cancer and its treatment followed by bitter and salty taste. Sour taste was least effected. When both the groups were compared for four tastes for detection threshold, the differences in observation at 3 stages of median IQR were not significant. For recognition threshold between zinc sulfate and placebo, no significant difference was observed in median IQR for salty taste and bitter taste. However, sweet taste (baseline p-value 0.245, end p-value 0.010, follow-up p-value 0.038) was statistically significant at end of CCRT and follow-up stage and sour taste (baseline p-value 0.24, end p-value 0.006, follow-up p-value 0.898) at end of CCRT only. CONCLUSION: Zinc sulfate was not found to be beneficial in preventing chemoradiation induced taste alterations. Taste and smell alterations are common in patients with cancer and do not receive sufficient support to manage taste alterations. This area requires more research to develop a comprehensive understanding of the nature and its management.

Utility of polaprezinc in reducing toxicities during radiotherapy: a literature review.

Chemoradiotherapy is important for treating malignancies. However, radiation-induced toxicities develop as chemoradiotherapy-related complications. Various agents reduce or prevent toxicities, but there are no standard treatments. Polaprezinc (PZ), a chelating compound used for gastric ulcers, has antioxidant and free radical scavenging effects. Although few studies have evaluated PZ and radiation-induced normal tissue damage, several clinical studies have shown the efficacy of PZ for oral mucositis, esophagitis, proctitis and taste alterations during and after radiotherapy. Moreover, preclinical data support the clinical data, indicating good potential of testing PZ in future trials. However, as there are only few well-documented review articles on PZ use in cancer treatment, we conducted this literature review. PZ reduced several radiation-induced toxicities and improved the quality of life.

Zinc protection in fetal rats for maternal mercury exposure-induced growth retardation is probably associated with S100B expression.

AIM: The study was conducted to investigate the effects of maternal mercury exposure on fetal rat development and zinc protection in mercury-exposed rats. METHODS: Pregnant rats were subjected to zinc sulfate pre-feeding, mercury exposure and zinc sulfate co-feeding. The control rats were administered distilled water. On day 19, the placental weight, overall weight, size and tail length of fetal rats, mercury content and S100B level in the placenta were determined using Western blot analysis. RESULTS: Compared with the control, mercury exposure at 2.0 mg/kg.d significantly reduced placental weight and fetal development, resulting in reduced fetal weight, size and tail length, while zinc pre-feeding increased placental weight and other fetal developmental parameters. Compared with mercury exposure, co-feeding with zinc significantly reduced mercury-induced injury in the fetal rats. S100B and mercury content levels were significantly elevated in rats maternally exposed to methylmercury chloride, compared with the unexposed control, while co-feeding with methylmercury chloride and zinc sulfate significantly reduced S100B and mercury levels in the placenta. CONCLUSION: Maternal exposure to mercury results in increased S100B in the placenta. Zinc sulfate feeding could reduce S100B and mercury levels, thereby protecting the rats from mercury damage. S100B level may be used to measure the antagonism between zinc and mercury during pregnancy.

Effect of zinc sulfate supplementation on premenstrual syndrome and health-related quality of life: Clinical randomized controlled trial.

AIM: The purpose of study was to assess the effect of zinc sulfate (ZS) supplementation on premenstrual syndrome (PMS) and health-related quality of life (QoL). METHODS: This was a double-blind randomized and placebo-controlled trial using the parallel technique conducted between June 2013 and May 2014. A total of 142 women (age, 20-35 years) with PMS were allocated to either the ZS or placebo group. The women in the intervention group received ZS 220-mg capsules (containing 50 mg elemental zinc) from the 16th day of the menstrual cycle to the second day of the next cycle. Data were collected using the Premenstrual Symptoms Screening Tool (PSST) and 12-item Short-Form Health Survey Questionnaire. RESULT: The prevalence of moderate to severe PMS in the ZS group significantly decreased throughout the study period (9.5% in the first, 6% in the second and 2.6% in the third month of the study, P < 0.001), but in the control placebo group this reduction was seen only in the first month of the study (14.2% in the first, 13.7% in the second and 13.5% in the third month, P = 0.08). Also, ZS improved the PSST component scores throughout the study period. The mean scores of QoL in physical and mental components were significantly improved in the ZS intervention group. However, the differences were statistically significant only 3 months after the intervention. CONCLUSION: Zinc sulfate, as a simple and inexpensive treatment, was associated with improvement of PMS symptoms and health-related QoL. Additional studies are warranted to confirm these findings.

Synthesizing slow-release fertilizers via mechanochemical processing for potentially recycling the waste ferrous sulfate from titanium dioxide production.

The goal of this study is aimed to develop a novel process to recycle the ferrous sulfate, the by-product of titanium dioxide industry. Zinc sulfate was added in the process of milling ferrous sulfate with calcium carbonate (CaCO3). The sulfates were transformed into carbonates to serve as slow-release fertilizers by co-grinding the starting materials of FeSO4·7H2O, ZnSO4·7H2O, and CaCO3 with small amounts of water in a planetary ball mill. The prepared samples were characterized by X-ray diffraction (XRD) analysis and quantitative measurements of the soluble ratios in water and 2% citric acid solution. It was found that Fe and Zn ions as sulfates were successfully combined with CaCO3 to form the corresponding Fe and Zn carbonates respectively. After milling, the release ratios of Fe and Zn nutrients in distilled water could be controlled at 0.1% and 0.7% respectively. Meanwhile, the release ratios of them in 2% citric acid solution were almost 98% and 100%. Milling speed was the critical parameter to facilitate the transformation reaction. The proposed process, as an easy and economical route, exhibits evident advantages, namely allowing the use of widely available and low-cost CaCO3 as well as industrial wastes of heavy metal sulfates as starting samples to prepare applicable products.

Zinc Supplementation in Adult Mechanically Ventilated Trauma Patients is Associated with Decreased Occurrence of Ventilator-associated Pneumonia: A Secondary Analysis of a Prospective, Observational Study.

BACKGROUND: Ventilator-associated pneumonia (VAP) is a type of lung infection that typically affects critically ill patients undergoing mechanical ventilation (MV) in the Intensive Care Unit (ICU). The aim of this analysis is to determine potential association between zinc supplementation with the occurrence of VAP in adult mechanically ventilated trauma patients. SUBJECTS AND METHODS: This secondary analysis of a prospective observational study was carried out over a period of 1 year in ICUs of one teaching hospital in Iran. A total of 186 adults mechanically ventilated trauma patients, who required at least 48 h of MV and received zinc sulfate supplement (n = 82) or not (n = 104) during their ICU stay, were monitored for the occurrence of VAP until their discharge from the ICU or death. RESULTS: Forty-one of 186 patients developed VAP, 29.09 days after admission (95% confidence interval [CI]: 26.27-31.9). The overall incidence of VAP was 18.82 cases per 1000 days of intubation (95% CI: 13.86-25.57). Patients who received zinc sulfate supplement have smaller hazard of progression to VAP than others (hazard ratio: 0.318 [95% CI: 0.138-0.732]; P < 0.0001). CONCLUSION: The findings show that zinc supplementation may be associated with a significant reduction in the occurrence of VAP in adult mechanically ventilated trauma patients. Further well-designed randomized clinical trials to confirm the efficacy of this potential preventive modality are warranted.

Maternal behavior influences development of a reflexive action pattern in the newborn rat.

This study examined the effect of maternal behavior on the expression and postnatal development of a reflexive behavior in rat pups. In neonatal rats, the leg extension response (LER) is a bilateral hyperextension of the hindlimbs in response to maternal anogenital licking (AGL). Past research has found that intranasal application of zinc sulfate (ZnSO4 ) to the dam induces hyponosmia, thereby reducing the incidence of AGL. In this study, pregnant dams received intranasal application of air (control), distilled water (control), or ZnSO4 on the day before birth and every other day thereafter until postnatal day 9 (P9). The LER was experimentally evoked in pups, using a vibrotactile device, at P1, P5, or P10. Pups born to ZnSO4 -treated dams showed significantly shorter bilateral LER durations and significantly smaller ankle angles than pups born to control dams. Reduction of overall maternal AGL approached significance, and afternoon AGL was significantly reduced. These data suggest that maternal behavior influenced development of the LER in rat pups, demonstrating the influence of maternal care on behavioral development during the perinatal period.

Exposure to Zinc Sulfate Results in Differential Effects on Olfactory Sensory Neuron Subtypes in Adult Zebrafish.

Zinc sulfate is a known olfactory toxicant, although its specific effects on the olfactory epithelium of zebrafish are unknown. Olfactory organs of adult zebrafish were exposed to zinc sulfate and, after 2, 3, 5, 7, 10 or 14 days, fish were processed for histological, immunohistochemical, ultrastructural, and behavioral analyses. Severe morphological disruption of the olfactory organ was observed two days following zinc sulfate exposure, including fusion of lamellae, epithelial inflammation, and significant loss of anti-calretinin labeling. Scanning electron microscopy revealed the apical surface of the sensory region was absent of ciliated structures, but microvilli were still present. Behavioral analysis showed significant loss of the ability to perceive bile salts and some fish also had no response to amino acids. Over the next several days, olfactory organ morphology, epithelial structure, and anti-calretinin labeling returned to control-like conditions, although the ability to perceive bile salts remained lost until day 14. Thus, exposure to zinc sulfate results in rapid degeneration of the olfactory organ, followed by restoration of morphology and function within two weeks. Zinc sulfate appears to have a greater effect on ciliated olfactory sensory neurons than on microvillous olfactory sensory neurons, suggesting differential effects on sensory neuron subtypes.

Research Note: Relative bioavailability of zinc in zinc hydroxychloride for chicks.

A chick assay was conducted to determine the effects of Zn source on performance and to establish a Zn relative bioavailability value (RBV) for a new source of Zn hydroxychloride. In the assay, 8-day-old chicks were fed a Zn-deficient soy protein concentrate diet supplemented with 0, 7, and 15 mg Zn/kg from feed grade ZnSO4 monohydrate for 14 d to establish a standard response curve. The same basal diet was supplemented with 3, 7, and 10 mg Zn/kg from a new Zn hydroxychloride (SAMZn). A second source of Zn hydroxychloride (IBZn) was supplemented at 10 mg Zn/kg as a direct comparison to the highest level of SAMZn. Weight gain increased (P < 0.05) with increasing Zn level, regardless of source. Weight gain of chicks fed 7 mg Zn/kg from SAMZn was not different (P > 0.05) from chicks fed 15 mg Zn/kg from ZnSO4. Weight gain was not different (P > 0.05) when comparing the 2 sources of Zn hydroxychloride supplemented at 10 mg Zn/kg. Tibia ash Zn and total tibia Zn were increased (P < 0.05) by all Zn sources and responded linearly (P < 0.05) to Zn supplementation from ZnSO4 and SAMZn. Total tibia Zn concentration was not different (P > 0.05) for chicks fed 10 mg Zn/kg from either source of Zn hydroxychloride. Multiple linear regression of total tibia Zn on supplemental Zn intake (R2 = 0.95) resulted in a RBV of 115% for SAMZn compared with ZnSO4 (set at 100%). The RBV of SAMZn was higher (P < 0.05) than ZnSO4. In conclusion, relative bioavailability of Zn (based on tibia Zn) in Zn hydroxychloride from SAMZn was higher than feed grade ZnSO4 based on multiple regression slope-ratio analysis and was similar to that of IBZn Zn hydroxychloride based on tibia Zn responses to 10 mg/kg supplemental dietary Zn.