Food Toxins Research Articles

Journey from food toxins to food safety: Transition over a century in service of nation.

Since the first report of lathyrism in 1926, the ICMR-National Institute of Nutrition (NIN) at Hyderabad, India, has made tremendous contributions in the field of food toxins/food safety for the benefit of the people. The present article highlights the Institute's work on various food toxins/foodborne diseases since its inception and discusses the important contributions made in the context of public health protection that formed the basis for several national policies on their prevention and control. The investigations on food toxins, in the initial decades, were limited to the description of lathyrism and its endemicity. Subsequently, the horizon was broadened to include the problem of mycotoxins and mycotoxicosis, which had received global attention and variety of other disease outbreaks investigations leading to total food safety transition in the forthcoming decades. Important contributions in epidemiological investigations, reproduction of the disease in experimental animals, surveillance and monitoring studies, development of methods for detection of food toxins and contaminants, evolving strategies for prevention and control and developing the concept of risk assessment and risk management for addressing food safety issues in the country are discussed.

Development of immunodetection system for botulinum neurotoxin serotype E.

Background & objectives:Botulism, a potentially fatal paralytic illness, is caused by the botulinum neurotoxins (BoNTs) secreted by Clostridium botulinum. It is an obligate anaerobic, Gram-positive, spore-forming bacterium. BoNTs are classified into seven serotypes based on the serological properties. Among these seven serotypes, A, B, E and, rarely, F are responsible for human botulism. The present study was undertaken to develop an enzyme-linked immunosorbent assay (ELISA)-based detection system for the detection of BoNT/E.Methods:The synthetic gene coding the light chain of BoNT serotype E (BoNT/E LC) was constructed using the polymerase chain reaction primer overlapping method, cloned into pQE30UA vector and then transformed into Escherichia coli M15 host cells. Recombinant protein expression was optimized using different concentrations of isopropyl-β-D-1-thiogalactopyranoside (IPTG), different temperature and the rBoNT/E LC protein was purified in native conditions using affinity column chromatography. The purified recombinant protein was checked by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and further confirmed by western blot and matrix-assisted laser desorption ionization-tandem time-of-flight (MALDI-TOF). Polyclonal antibodies were generated against rBoNT/E LC using Freund's adjuvant in BALB/c mice and rabbit. Sandwich ELISA was optimized for the detection of rBoNT/E LC and native crude BoNT/E, and food matrix interference was tested. The developed antibodies were further evaluated for their specificity/cross-reactivity with BoNT serotypes and other bacterial toxins.Results:BoNT/E LC was successfully cloned, and the maximum expression was achieved in 16 h of post-induction using 0.5 mM IPTG concentration at 25°C. Polyclonal antibodies were generated in BALB/c mice and rabbit and the antibody titre was raised up to 128,000 after the 2nd booster dose. The developed polyclonal antibodies were highly specific and sensitive with a detection limit about 50 ng/ml for rBoNT/E LC and 2.5×103 MLD50 of native crude BoNT/E at a dilution of 1:3000 of mouse (capturing) and rabbit (revealing) antibodies. Further, different liquid, semisolid and solid food matrices were tested, and rBoNT/E LC was detected in almost all food samples, but different levels of interference were detected in different food matrices.Interpretation & conclusions:There is no immune detection system available commercially in India to detect botulism. The developed system might be useful for the detection of botulinum toxin in food and clinical samples. Further work is in progress.

The connection between food toxicology and lifestyle disorders - A literature review

Around 39% of the adult world population is overweight and 13 % are obese (WHO). One of the major reasons for this (As per Harvard Researchers) is certain food toxins responsible for increasing “craveability” of junk food. Another study suggests the presence of certain chemical obesogens which disrupt the leptin and ghrelin (appetite hormones) also affect the size of adipocytes. Prevalence of polycystic ovarian syndrome is claimed to be varying between 6-10% in various studies including the major ones from National institute of Health (NIN), Rotterdam and Androgen excess society. Thyroid on the other hand is affecting 10% of the population (as per a study conducted in 8 major cities of India) The sedentary lifestyle, convenience foods & improper cooking practices though are to be blamed for the increasing prevalence of all lifestyle disorders but at the same time the increasing exposure to environmental toxins including microbiological, natural food toxins, polymer leaching and its residues including phthalates and bisphenols and the biological magnification of the pesticides across the food chain are all the more responsible for the hormonal imbalances caused by the chemicals mimicking the hormones in the natural biochemical processes hence causing the lifestyle disorders. The purpose of this presentation is to compile and highlight the most common toxins affecting the nutritional status of the masses, their common sources and mode of action. The presentation also puts light on the solution-based approach (including the importance of an Anti- inflammatory diet) and steps which can be taken to rectify the fundamentals which are going wrong.

Final twist in marine toxin structural saga

In the mid-1990s, scientists started to notice cases across Europe of people falling ill from a new kind of shellfish food poisoning. The culprit, researchers discovered, was a family of marine toxins called azaspiracids. The structures of these amorphous toxins have been difficult for chemists to pin down, though some have come very close. A pair of papers from the laboratory of Craig J. Forsyth at Ohio State University now corrects the stereochemistry of a key position in azaspiracid-3 and details a total synthesis of the reassigned structure (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201711006; Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201711008). A synthetic route to the azaspiracids along with accurate structures could help scientists develop assays to detect the toxins in food. Forsyth’s lab had been working on an azaspiracid synthesis in 2004 when K. C. Nicolaou, then at Scripps Research Institute California, reported a 96-step synthesis that revised

Acrylamide-induced changes in femoral bone microstructure of mice.

Acrylamide (AA) is one of the most common toxins in foods. Its effect on bone microstructure has not been investigated. The aim of our study was to analyze the impact of acute exposure to AA on femoral bone microstructure in mice. Adult animals were treated perorally with 2 doses of AA (E1 group, 1 mg/kg b.w.) in a 24-h period and with 3 doses of AA (E2 group, 1 mg/kg b.w.) in a 48-h period. Mice exposed to AA had smaller sizes of primary osteon's vascular canals. Secondary osteons were significantly smaller in mice from E2 group; however their increased number (from 38 % to 77 %) was identified in both E1 and E2 groups. In these groups, a higher number of resorption lacunae (from 100 % to 122 %) was also found. The values for bone volume, trabecular number were increased and that for trabecular separation was decreased in mice administered AA. Significantly higher value of bone surface was observed in mice from E1 group whereas trabecular thickness was increased in E2 group. The effect of AA on microstructure of compact and trabecular bone tissues is different. In our study, one dose of AA was used and acute effects of AA were investigated. Therefore, further studies are needed to study mechanisms by which AA acts on bone.

First report of methicillin‐resistant Staphylococcus aureus in tank cultured dusky kob (Argyrosomus japonicus), and evaluation of three phenotypic methods in the detection of MRSA

AbstractThis study was conducted to ascertain the occurrence of methicillin‐resistant Staphylococcus aureus (MRSA) in marine finfish (Argyrosomus japonicus) harvested from the wild and two re‐circulatory aquaculture systems, and evaluating the reliability of three phenotypic methods in the detection of methicillin resistance. A total of 120 dusky kob fish were sampled for S. aureus detection using conventional methods and confirmed by polymerase chain reaction (PCR) targeting the nuc gene. Methicillin resistance was determined by molecular detection of the mecA gene. Using mecA as the defining standard, the specificities and sensitivities of cefoxitin disc diffusion, oxacillin screen agar, and growth of S. aureus on Brilliance MRSA II Agar were evaluated. A total of 321 presumptive S. aureus isolates were recovered by culture, out of which 202 (62.9%) were confirmed by PCR. Of these, 33 (16.3%) strains were mecA positive while 169 (83.7%) were mecA negative. The sensitivities and specificities of MRSA detection was 93.9 and 91.7%, 81.8 and 92.3%, and 87.9 and 94.1% for cefoxitin disc, oxacillin screen agar test, and Brilliance MRSA II agar, respectively. This is so far the first report of MRSA in dusky kob aquaculture in South Africa. In the absence of molecular techniques, cefoxitin disc diffusion test is recommended along with any other phenotypic method to improve MRSA detection from samples of veterinary origin.Practical implicationsMethicillin‐resistant Staphylococcus aureus currently presents one of the greatest challenges for medical research worldwide, as well as is one of the most important causes of bacteria gastroenteritis due to preformed toxins in foods. There is a dearth of knowledge on marine foods as carriers/sources of MRSA infection. There are also major discrepancies obtained with MRSA detection methods, making effective detection of this pathogen complicated. The results from this study show that healthy aquaculture fish are reservoirs of MRSA, thus it is necessary to regularly monitor marine foods. Cefoxitin disc diffusion test is recommended as the preferred method for detection of MRSA from fish/food samples where molecular methods are lacking.

Paper‐based microfluidic aptasensor for food safety

AbstractFood analysis is requiring rapid, accurate, sensitive, and cost‐effective methods to monitor and guarantee the safety and quality to fulfill the strict food legislation and consumer demands. In this study, a nano‐materials enhanced multipurpose paper‐based microfluidic aptasensor was developed as a sensing tool for accurate detection of food allergens and food toxins. graphene oxide (GO) and specific aptamer‐functionalized quantum dots (QDs) were employed as probes, the fluorescence quenching, and recovering of the QDs caused by the interaction among GO, aptamer‐functionalized QDs, and the target protein were investigated to quantitatively analyze the target concentration. The homogenous assay was performed on the paper‐based microfluidic chip, which significantly decreased the sample and reagent consumption and reduced the assay time. Egg white lysozyme, ß‐conglutin lupine and food toxins, okadaic acid and brevetoxin standard solutions, and spiked food samples were successfully assayed by the presented aptasensor. Dual‐target assay was completed within 5 min, and superior sensitivities were achieved when testing the samples with commercial enzyme linked immunosorbent assay kits side by side.Practical applicationsThe present aptasensor provides a simple, accurate method for rapid quantitative analysis of allergens or toxins in food. This method is able to achieved rapid on‐site detection of potential allergen/toxin contaminations, which is a critical necessity for individuals with food allergies and other types of food sensitivities. In addition, the present method can be easily implemented into routine analysis to help food producers and regulations secure the safety and compliance of food products.

The frequency of shiga-like toxin (stx1 and stx2) and EHEC-hlyA in food by multiplex PCR

Abstract Aim: The aim of the present study was to determine the frequency of shiga-like toxin (stx1 and stx2) and drug resistance profiles food-borne Escherichia coli O157:H7 in Hatay province, Turkey. Methods: The presence of the virulence genes (stx1, stx2, hlyA) in a total of 150 E.coli isolates were studied with multiplex PCR. Results: A total of 327 salad samples were analyzed. E. coli O157:H7 was detected in 150 (45.8 %) out of 327 analyzed samples. Of these 150 isolates, the presence of hly-A gene was detected in 32 (21.3%) E.coli isolates. A total of five (15.6%) isolates in this 32 hlyA positive isolates had stx2 gene, two (6.3%) of them had stx1 gene and one (3.1%) of the isolates was found to be positive for both stx1 and stx2 genes. It was found that all E.coli O157:H7 isolates were resistant to erythromycin. While the highest rate of antibiotic resistance was observed for ampicillin (68.8%), no antibiotic resistance against cefuroxime, ciprofloxacin and cephaperasone was identified. Conclusions: The results obtained in our province showed that E.coli strains isolated from salad samples were found to have some important virulence genes such as stx1, stx2, and hlyA. The stx2 frequency was found to be higher than stx1 frequency. Also, it was observed that there was not any significant correlation between drug resistance profiles and presence of toxin genes in E.coli O157:H7 strains. As a result, increasing frequency of STEC O157 serotype among foodborne pathogens is a growing public health problem.

The balancing act of foraging: mammalian herbivores trade-off multiple risks when selecting food patches.

Animals face multiple risks while foraging such as the risk of acquiring inadequate energy from food and the risk of predation. We evaluated how two sympatric rabbits (pygmy rabbits, Brachylagus idahoensis, and mountain cottontail rabbits, Sylvilagus nuttallii) that differ in size, use of burrows, and habitat specialization in the sagebrush-steppe of western North America respond to different types and levels of perceived risks (i.e., fitness cost × probability of occurrence), including fiber and toxins in food, exposure to predation, and distance from a refuge. We measured food intake by the rabbits at paired food patches that varied in these risks and used the method of paired comparisons to create a relative ranking of habitat cues, which revealed an animal's perceived risk on a single scale representing an integrated response to a variety of risks. Pygmy rabbits perceived exposure to predation risk and distance from a burrow as riskier than did cottontails, whereas cottontails perceived dietary toxin as riskier. Pygmy rabbits consumed lower quality food, containing higher fiber or toxins, thereby avoided feeding in exposed patches or traveling far from their burrow to forage. In contrast, cottontails fed in exposed patches and traveled farther from the burrow to obtain higher quality food. We have shown how risks can be integrated into a single model that allows animals to reveal their perceptions of risks on a single scale that can be used to create a spatially explicit landscape of risk.

Analysis of T-2 Toxin Removal Factors in a Lactococcus Fermentation System

The objective of this work was to determine the bacterial strains and factors that most efficiently degrade T-2 toxin in foods or animal feed. To determine the most efficient strain and optimal incubation times for degradation of T-2, the rate of T-2 removal by three lactic acid bacteria strains was quantified by liquid chromatography plus tandem mass spectrometry after incubation in de Man Rogosa Sharpe broth with 50 ng mL-1 T-2 at 37°C for 96 h. Various components of the most efficient degradation strain fermentation systems were extracted, and the ability to remove T-2 was assayed. Lactococcus lactis CAMT22361 was the most efficient degradation strain for removing T-2. Yeast extract powder interfered with L. lactis CAMT22361 in the degradation process. T-2 toxin was removed by various components of the L. lactis CAMT22361 cells in the following order: nonprotein material of the extracellular fraction > protein in the extracellular fraction > whole cell ≈ cell wall > cell intracellular matrix fluid. T-2 removal rates were 54.08% ± 0.79%, 43.65% ± 0.84%, 43.09% ± 0.87%, 41.98% ± 0.8%, and 23.45% ± 0.66%, respectively. The nonprotein fraction in the extracellular fluid was most likely the key component in L. lactis CAMT22361 and hence would be the most desirable cellular component to be used to remove T-2 from food or feed.

DNA Aptamer–Target Binding Motif Revealed Using a Fluorescent Guanine Probe: Implications for Food Toxin Detection

DNA aptamers are single-stranded oligonucleotides that are generated by an in vitro selection method to bind targets with high affinity and specificity. Understanding molecular recognition by DNA aptamers is of fundamental importance in the development of biosensor applications. The small molecule ochratoxin A (OTA) is a fungal-derived food toxin, and OTA DNA aptamers have been established for the development of rapid detection platforms required for food safety. One such OTA aptamer (OTAA) is a guanine-rich DNA oligonucleotide that folds into an antiparallel G-quadruplex (GQ) upon OTA binding, although structural details of the GQ fold and its interaction with OTA are currently unknown. In the present study, the fluorescent nucleobase analogue, 8-thienyl-2′-deoxyguanosine (ThdG), was inserted into various G sites of OTAA to determine the probe impact on GQ folding and OTA binding affinity. Our results suggest that OTAA contains three lateral (l) loops connecting two stacked G-tetrads with an anticlockwise loop progression to afford a −(lll) GQ topology. The phenolic ring system of OTA undergoes π-stacking interactions with the G-tetrads of OTAA. Our results also demonstrate aptamer sites that can be modified with ThdG to afford a fluorescent light-up signal upon OTA binding.

Detection Methodologies for Pathogen and Toxins: A Review.

Pathogen and toxin-contaminated foods and beverages are a major source of illnesses, even death, and have a significant economic impact worldwide. Human health is always under a potential threat, including from biological warfare, due to these dangerous pathogens. The agricultural and food production chain consists of many steps such as harvesting, handling, processing, packaging, storage, distribution, preparation, and consumption. Each step is susceptible to threats of environmental contamination or failure to safeguard the processes. The production process can be controlled in the food and agricultural sector, where smart sensors can play a major role, ensuring greater food quality and safety by low cost, fast, reliable, and profitable methods of detection. Techniques for the detection of pathogens and toxins may vary in cost, size, and specificity, speed of response, sensitivity, and precision. Smart sensors can detect, analyse and quantify at molecular levels contents of different biological origin and ensure quality of foods against spiking with pesticides, fertilizers, dioxin, modified organisms, anti-nutrients, allergens, drugs and so on. This paper reviews different methodologies to detect pathogens and toxins in foods and beverages.

Integrated Smartphone-App-Chip System for On-Site Parts-Per-Billion-Level Colorimetric Quantitation of Aflatoxins

We demonstrate herein an integrated, smartphone-app-chip (SPAC) system for on-site quantitation of food toxins, as demonstrated with aflatoxin B1 (AFB1), at parts-per-billion (ppb) level in food products. The detection is based on an indirect competitive immunoassay fabricated on a transparent plastic chip with the assistance of a microfluidic channel plate. A 3D-printed optical accessory attached to a smartphone is adapted to align the assay chip and to provide uniform illumination for imaging, with which high-quality images of the assay chip are captured by the smartphone camera and directly processed using a custom-developed Android app. The performance of this smartphone-based detection system was tested using both spiked and moldy corn samples; consistent results with conventional enzyme-linked immunosorbent assay (ELISA) kits were obtained. The achieved detection limit (3 ± 1 ppb, equivalent to μg/kg) and dynamic response range (0.5-250 ppb) meet the requested testing standards set by authorities in China and North America. We envision that the integrated SPAC system promises to be a simple and accurate method of food toxin quantitation, bringing much benefit for rapid on-site screening.

Determination of mycotoxins in fruit berry by-products using QuEChERS extraction method

Fruit berries by-products are mainly elaborated with berry but most of them mixed with other fruits, grapes, plums or apples. These present favourable properties for the growth of a great range of mycotoxins mould producers. Consequently, alternariol (AOH), alternariol monomethyl ether (AME), tentoxin (TEN), aflatoxins (AFB1, AFB2, AFG1, AFG2) and ochratoxin A (OTA) are the main mycotoxins that should be present in berries by-products. To establish a reliable analytical method of these mycotoxins on two fruit berries by-products (jam and juice), four different QuEChERS extraction method were evaluated. Recoveries obtained were higher than 74% and 76% in berries juice and jam berries, respectively. LDs for berries jam were from 2 to 8 ng/g and for berries juice from 0.1 to 3 ng/ml. The optimized procedure was applied to analyse 52 berries fruit by-products including 32 berries juice and 20 berries jam randomly collected from different markets in Valencia, Spain. 57% and 71% of berries juice samples presented aflatoxins and Alternaria mycotoxins, respectively. OTA was detected only in a blueberry juice (5% at 7.8 ng/ml). This work should contribute to EFSA's recommendations to develop sensitive analytical methods and generate more analytical data concerning the occurrence of Alternaria toxins in food and feed.

Detection of ochratoxin A by aptamer-assisted real-time PCR-based assay (Apta-qPCR).

Detection of food toxins with high sensitivity is very important and challenging. Ochratoxin A (OTA) is frequently present as food contaminant in contaminated grains and grain derivatives such as bread and beer. In this work, a target-induced dissociation (TID) based aptamer-assisted real-time PCR-based assay (apta-qPCR) is developed that features effective detection of OTA. Apta-qPCR effectively combines the capabilities of aptamer to be amplified, being a nucleotide sequence, with its specific interaction with the corresponding target molecule. Compared to commonly used fluorescence-based and colorimetric methods, the sensitivity of qPCR to detect a nucleotide sequence (aptamer) has ameliorated the sensitivity of the aptamer-based detection of OTA. Here, the OTA aptamer was immobilized on the magnetic beads coated with d(T)25 (dT beads). A sequence complementary to the OTA-binding portion of the aptamer was used as a linker between dT beads and the aptamer sequence. When OTA was added, the aptamer was released from the dT beads due to TID. The resulting assay was able to detect 0.009ng/mL OTA with a wide dynamic range of 0.039-1000ng/mL. Apta-qPCR can be easily transferred to other small molecules for highly sensitive detection using corresponding aptamers.

Microfluidic fabrication of photonic encoding magnetized silica microspheres for aptamer-based enrichment of Ochratoxin A

Photonic encoding magnetized silica microspheres were synthesized from a polydisperse system containing silica and Fe3O4 nanoparticles by using a microfluidic self-assembly device. The optical and structural properties of the magnetized microspheres were characterized by scanning electron microscopy and reflection spectra. The concentration of Fe3O4 nanoparticles in polydisperse system was found to strongly affect the characteristics of magnetized microspheres. They possess a Janus face, are porous, and possess structural color (red). The magnetic characteristic of the synthesized microspheres is not lost after they are immersed in piranha solution for 12 h. The magnetized microspheres were applied to aptamer-based enrichment of the food toxin Ochratoxin A (OTA). Methods for immobilization of OTA aptamer on the microsphere surfaces were investigated. The modified microspheres can extract up to 80% of OTA if the surface of the microspheres is loaded with 275 ng·cm−2 of aptamer and the number of microspheres is 200. The work provides a new pathway for aptamer-based enrichment of small molecules from complex matrixes.

Development and Validation of a Liquid Chromatography-Tandem Mass Spectrometry Method Coupled with Dispersive Solid-Phase Extraction for Simultaneous Quantification of Eight Paralytic Shellfish Poisoning Toxins in Shellfish

In this study, a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for simultaneous determination of eight paralytic shellfish poisoning (PSP) toxins, including saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins (GTX1–4) and the N-sulfo carbamoyl toxins C1 and C2, in sea shellfish. The samples were extracted by acetonitrile/water (80:20, v/v) with 0.1% formic and purified by dispersive solid-phase extraction (dSPE) with C18 silica and acidic alumina. Qualitative and quantitative detection for the target toxins were conducted under the multiple reaction monitoring (MRM) mode by using the positive electrospray ionization (ESI) mode after chromatographic separation on a TSK-gel Amide-80 HILIC column with water and acetonitrile. Matrix-matched calibration was used to compensate for matrix effects. The established method was further validated by determining the linearity (R2 ≥ 0.9900), average recovery (81.52–116.50%), sensitivity (limits of detection (LODs): 0.33–5.52 μg·kg−1; limits of quantitation (LOQs): 1.32–11.29 μg·kg−1) and precision (relative standard deviation (RSD) ≤ 19.10%). The application of this proposed approach to thirty shellfish samples proved its desirable performance and sufficient capability for simultaneous determination of multiclass PSP toxins in sea foods.

Optimized Nanocrystalline Silicon Oxide Impedance Immunosensor Electronic Tongue for Subfemtomolar Estimation of Multiple Food Toxins

Nanocrystalline silicon oxide (nc-SiO2) immunosensor array-based electronic tongue (E-tongue) has been recently reported to simultaneously detect multiple food toxins with subfemtomolar sensitivity. However, the quantification in these reports is quite imprecise leading to an error of more than 100%. In this paper, the quantification accuracy of multiple food toxin detection in the subfemtomolar range has been improved by more than 90% through upgraded design of the E-tongue system by incorporating two major modifications. First, the pore geometry of the nc-SiO2 immunosensors has been optimized to obtain the best combination of sensitivity, selectivity, and reproducibility through the evaluation of a figure of merit. Second, in the multivariate data processing using partial least squares discriminate analysis, additional input parameters corresponding to selectivity and standard deviations of the experimentally measured data have been incorporated. The final set of input parameters include peak frequency corresponding to maximum impedance sensitivity, bandwidth of the impedance sensitivity characteristics, cutoff frequency from noise spectroscopy, and their standard deviations. The optimized E-tongue system is capable of quantifying 0.1 fg/ml Aflatoxin B1 and Ochratoxin A with an error of only 10% and 20%, respectively, which is a remarkable achievement in the domain of food toxin detection. The proposed E-tongue system is low cost with minimal operator dependence and hence has immense potential for commercial deployment.

The repertoire of bitter taste receptor genes in canids.

Bitter taste receptors (Tas2rs) play important roles in mammalian defense mechanisms by helping animals detect and avoid toxins in food. Although Tas2r genes have been widely studied in several mammals, minimal research has been performed in canids. To analyze the genetic basis of Tas2r genes in canids, we first identified Tas2r genes in the wolf, maned wolf, red fox, corsac fox, Tibetan fox, fennec fox, dhole and African hunting dog. A total of 183 Tas2r genes, consisting of 118 intact genes, 6 partial genes and 59 pseudogenes, were detected. Differences in the pseudogenes were observed among nine canid species. For example, Tas2r4 was a pseudogene in the dog but might play a functional role in other canid species. The Tas2r42 and Tas2r10 genes were pseudogenes in the maned wolf and dhole, respectively, and the Tas2r5 and Tas2r34 genes were pseudogenes in the African hunting dog; however, these genes were intact genes in other canid species. The differences in Tas2r pseudogenes among canids might suggest that the loss of intact Tas2r genes in canid species is species-dependent. We further compared the 183 Tas2r genes identified in this study with Tas2r genes from ten additional carnivorous species to evaluate the potential influence of diet on the evolution of the Tas2r gene repertoire. Phylogenetic analysis revealed that most of the Tas2r genes from the 18 species intermingled across the tree, suggesting that Tas2r genes are conserved among carnivores. Within canids, we found that some Tas2r genes corresponded to the traditional taxonomic groupings, while some did not. PIC analysis showed that the number of Tas2r genes in carnivores exhibited no positive correlation with diet composition, which might be due to the limited number of carnivores included in our study.

Acrylamide: a common food toxin related to physiological functions and health.

Acrylamide (AA) is a highly reactive organic compound capable of polymerization to form polyacrylamide, which is commonly used throughout a variety of industries. Given its toxic effect on humans and animals, the last 20 years have seen an increased interest in research devoted to the AA. One of the main sources of AA is food. AA appears in heated food following the reaction between amino acids and reduced sugars. Large concentrations of AA can be found in popular staples such as coffee, bread or potato products. An average daily consumption of AA is between 0.3-2.0 microg/kg b.w. Inhalation of acrylamide is related with occupational exposure. AA delivered with food is metabolized in the liver by cytochrome P450. AA biotransformation and elimination result in formation of toxic glycidamide (GA). Both, AA and GA can be involved in the coupling reaction with the reduced glutathione (GSH) forming glutathione conjugates which are excreted with urine. Biotransformation of AA leads to the disturbance in the redox balance. Numerous research proved that AA and GA have significant influence on physiological functions including signal propagation in peripheral nerves, enzymatic and hormonal regulation, functions of muscles, reproduction etc. In addition AA and GA show neurotoxic, genotoxic and cancerogenic properties. In 1994, International Agency for Research on Cancer (IARC) classified acrylamide as a potentially carcinogenic substance to human.