Insights into the development of Notocotylus attenuatus (Digenea: Notocotylidae) in Lymnaea stagnalis: from mother sporocyst to cercariae

Notocotylus attenuatus (Digenea: Notocotylidae) is a monostome fluke parasitizing the intestinal caeca of waterfowl that uses an injection apparatus to infect its intermediate snail host. Morphology of the invading larva (a sporocyst), and the intramolluscan larval development of this fluke have not been characterized extensively. In this study, experimental infections of Lymnaea stagnalis using N. attenuatus eggs resulted in the development of sporocysts containing one germ ball or mother redia between 12 and 21 days post exposure (p.e.) within the hepatopancreas. Independent mother rediae and developing daughter rediae were present between day 25 and day 42 p.e. Cercariae, within the body of rediae, were detected 42 days p.e. The development of daughter rediae and cercariae started posteriorly in the body of parent redia and these larvae migrated anteriorly during development towards the birth pore. A cercaria was also observed emerging from the birth pore and released cercariae maturated further within the snail hepatopancreas prior to leaving the snail. The intramolluscan development was completed 45 days p.e. when the first fully formed cercariae were shed into the outer environment. These data detail the fascinating post-embryonic development of N. attenuatus and highlight the intricate nature of larval transitions within its snail host.     

Notocotylus ikutai n. sp. (Digenea: Notocotylidae) from lymnaeid snails and anatid birds in Hokkaido,Japan

An unknown species of the genus Notocotylus (Digenea: Notocotylidae) was found as the larval stage from the lymnaeid snail, Radix auricularia, in a static water area of the Chubetsu River, Hokkaido, the northernmost island of Japan. A DNA barcoding identification system was applied to detect the adult stage. Through the inspection of anatid game birds in Hokkaido, Anas crecca, Anas platyrhynchos, Anas zonorhyncha, and Mareca penelope were demonstrated to serve as the definitive hosts. The detailed morphological features of the species were characterized using adults raised experimentally in immunosuppressed mice and naturally developed larvae in R. auricularia. Although the species is morphologically similar to Notocotylus attenuatus and Notocotylus magniovatus in both adult and larval stages, its taxonomic independence was confirmed by a comprehensive study based on molecular phylogeny, morphology, and ecology. Here we propose Notocotylus ikutai n. sp. for this species. The migratory behavior of the anatid hosts and the North-Eurasian distribution of R. auricularia suggest that the new species is widely distributed in the northern Far East.     

Effect of medium copper concentration on the growth,uptake and intracellular balance of copper and zinc in Menkes' and normal control cells

The precise nature of the variation in cellular copper load against medium copper concentration is defined using a comprehensive logarithmically incremented series of medium copper concentrations ranging from low levels (4.8 p.p.b.) through normal to toxic levels (40 p.p.m.) in which fibroblasts were grown followed by determination of intracellular content. Menkes' fibroblasts showed an unexpected plateau region of stable intracellular copper content against a change in medium concentration of over 100-fold, albeit only when sufficient copper was present in the medium (0.08–8.0 p.p.m.). Thus, Menkes' cells are clearly capable of balancing uptake/efflux providing copper availability allows. Simultaneous analysis of cellular copper and zinc load at various medium copper concentrations shows an indistinguishable intracellular copper:zinc ratio between the two cell lines. The nature of non-labeled copper uptake by fibroblasts over a 40 min and 7 day period is reported. During the 40 min period copper uptake (20 p.p.m.) was essentially the same in both cell lines. However, copper absorbed was superimposed upon large pre-existing copper pools in the case of Menkes' cells only. Advantages of techniques determining non-labeled copper in copper uptake/efflux experiments are discussed in the light of these results. Fibroblast growth studies showed that, compared with normal cells, Menkes' cells are significantly (P < 0.01) more growth sensitive to extended exposure to low copper concentrations. Thus, Menkes' disease appears to be not only a result of copper maldistribution but also a direct result of an inability of Menkes' cells to function normally in low copper environments.     

Toxicity of cadmium and zinc to Diplostomum spathaceum (Trematoda: Diplostomidae) cercarial survival

The toxicity of cadmium and zinc at concentrations ranging from 0.1 to 10000 microg/l was investigated with cercariae of Diplostomum spathaceum at three temperatures (12, 20, 25 degrees C) and three levels of water hardness (distilled water, soft water, hard water). Under most environmental conditions survival of cercariae was reduced by increasing metal concentration. Increasing water hardness and decreasing water temperature caused an increase in the survival of both control and metal exposed cercariae. However, with decreasing temperature increased survival of metal-exposed cercariae above the control occurred at a number of low metal concentrations. Differences in the relative toxicity of cadmium and zinc to cercariae was dependent on the environmental conditions of exposure. The two heavy metals demonstrated little toxicity to cercariae during the period of maximum cercarial infectivity (0-5 h).The mechanisms of metal toxicity and their effects on cercarial survival are discussed.     

The influence of salinity on the cercariae of three species of Schistosoma

Donnelly F. A., Appleton C. C. and Schutte C. H. J. 1984. The influence of salinity on the cercariae of three species of Schistosoma. International Journal for Parasitology14: 13–21. The effect of salinity on the longevity and infectivity of cercariae of Schistosoma mattheei, Schistosoma haematobium and Schistosoma mansoni was determined. No significant differences in cercarial longevity occurred (p > 0.05) in low salinities (0–5.25%), whereas further increases in salinity resulted in progressive decreases in survival. In salinities ? 17.5%, cercariae were incapable of surviving for longer than 11 min. A maximum life-span of up to 122 h was recorded for some S. mattheei cercariae. Cercarial infectivity, as indicated by worm returns, was reduced progressively with increasing salinity up to a lethal limit of 10.5%. Differences in the salinity tolerance of the cercariae of the three species were discussed.     

Biomethanation of spent wash: Heavy metal inhibition of methanogenesis in synthetic medium

Five heavy metals detected in distillery waste were lead (1.0–8.8 μg/ml), copper (1.7–15.7 μg/ml), zinc (3.1–11.8 μg/ml), iron (36.0–43.5 μg/ml), and manganese (3.0–5.1 μg/ml). Their toxicity to biomethanogenesis in a synthetic medium containing 1% sodium acetate, propionate, or butyrate was measured by batch fermentation, after cultivating the bacterial biomass semicontinuously. Lead, copper, and zinc in decreasing order were found to be toxic to biomethanogenesis. Lead at the concentration of 10 μg/ml completely stopped methane production. Iron did not produce any notable change in the process while manganese stimulated the rate of methane production. The toxicity of lead, copper, and zinc to methanogenic bacteria and methane production was dose-dependent but the growth of acetogenic bacteria was impaired at higher concentrations (2.5–10.0 μg/ml) of lead, copper, and zinc. Manganese stimulated the growth of only methanogenic bacteria, but not that of non-methanogenic bacteria or acetic acid production. The reduction in the synthesis of acetic acid via butyrate was more in the presence of these three metals than the synthesis of this acid via propionate.     

Heavy metal tolerance of marine phytoplankton. III. Combined effects of copper and zinc ions on cultures of four common species

The combined effects of copper and zinc ions on the growth of three marine diatoms and one dinoflagellate in culture have been studied. The two metals were found to act synergistically to all algae except Phaeodactylum tricornutum Bohlin. With this species an antagonistic effect was observed. Addition of zinc ions reduced the inhibition of growth caused by the more toxic copper ions. Zinc toxicity to this alga increased at low concentration of magnesium, indicating a common route for divalent metal ions in general.     

Life-cycle,delimitation and redescription of Catatropis verrucosa (Frölich, 1789) Odhner, 1905 (Trematoda: Notocotylidae)

The life-cycle of Catatropis verrucosa (Frölich, 1789) Odhner, 1905 has been completed experimentally starting from infected snails collected along the River Danube in Europe. Each stage of the life-cycle is redescribed. Taxonomic problems are discussed and the main features of the species are listed. Synonyms for C. verrucosa are Fasciola verrucosa Frölich, 1789, F. anseris Gmelin, 1790, Monostoma verrucosa (Frölich, 1789) Zeder, 1800, and Catatropis charadrii Skrjabin, 1915. Other names, such as Notocotylus triserialis Diesing, 1839, Notocotyle triseriale (Diesing, 1839) Diesing, 1850, Monostoma verrugueux Dujardin, 1845, “Monostoma sp. du canard” of Blanchard (1847), Notocotyle verrucosum (Frölich, 1789) Monticelli, 1892, N. verruqueux Railliet, 1895, and Distoma verrucosum (Frölich, 1789) Wolffhugel, 1900, were found to represent adults and/or larvae of C. verrucosa. Conversely, but less often, adults and larvae of other species were found described and illustrated as C. verrucosa. One of these, C. verrucosa of Joyeux (1922), was renamed Pseudocatatropis joyeuxi Kanev & Vassilev, 1986. Occasionally, authors actually working with C. verrucosa ascribed their results to different species. Based on experimental life-cycle studies, the following facts were demonstrated. (1) The first intermediate hosts are the prosobranch freshwater snails Bithynia tentaculata (Linnaeus, 1758) and B. leachi (Leach, 1818). (2) The same snails are also first intermediate hosts for Notocotylus imbricatus (Looss, 1893) Szidat, 1935, N. parviovatus Yamaguti, 1934, and N. ponticus Tschiaberaschvili, 1966. In all these species, the species characteristics are expressed by the adult morphology only, and the larvae cannot be identified by morphological criteria. It is proposed that tri-oculate monostome cercariae found in naturally infected B. tentaculata and B. leachi be referred to as “Cercaria imbricata group”. These cercariae include Cercaria imbricata Looss, 1893, C. helvetica I Dubois, 1928, C. triophthalmia Faust, 1930, C. fennica I Wikgren, 1956; C. ephemera of Lutta (1934); C. monostomi of Mathias (1925), Lutta (1934) and Zdun (1961), Cercaria Notocotylus attenuatus of Francalanci & Manfredini (1969), and Monostome cercaria I Emmel, 1943. (3) There is no second intermediate snail host in the life-cycle of C. verrucosa. (4) The final hosts are birds. (5) The adult worms possess, on the ventral body surface, a median ridge and two lateral rows of 12 (range 11–14) papillae per row.     

Toxicity of zinc to schistosoma Mansoni Cercariae in a Chemically Defined Water Medium

Time-until-death studies were run on cercariae of Schistosoma mansoni in 15 concentrations of zinc (from zinc sulfate) ranging from 57.6 ppm to 1 ppb. A chemically defined water medium was used for the dilution and control medium, and a partially enclosed slide chamber was perfected for the detailed observation of test cercariae. In concentrations of less than 57.6 ppm, zinc was found to have little lethal effect on cercariae during that period in which these larvae were most likely to be infective (0–6 hours) after emergence. Zinc concentration of 1 ppb killed all test cercariae within 46 hours at 21–22°C.At the highest concentration tested, 57.6 ppm zinc immobilized all test organisms within 6 hours at 21–2°C. The average time for 100 percent mortality for the control was 49 hours. The cercaricidal effects of zinc were shown to be insignificant in concentrations that would not be detrimental to other aquatic organisms.     

The role of bithyniid snails (Gastropoda: Bithyniidae) as hosts of trematodes of the family notocotylidae in ecosystems of different climatic zones of the West Siberian Plain

The results of long-term investigations (1994–2012) of an infection rate of trematodes of the family Notocotylidae Lühe, 1909 in the first intermediate hosts (Bithyniidae family) are discussed. The bithyniid snails (11348 Bithynia troscheli (Paasch, 1842) and 4347 Bithynia tentaculata (Linne, 1758) in 1994–2012 from Western Siberia have been studied. Parthenitae and cercariae of the family Notocotylidae belong to three species: Notocotylus imbricatus Looss, 1894, Szidat; N. parviovatus Yamaguti, 1934 [syn.: N. chionis Baylis, 1928] and Catatropis verrucosa (Frohl.) Odhner, 1905. The extensiveness of infection of bithyniid snails by the tre-matodes (parthenitae and cercariae) of the family Notocotylidae in rivers basin Ob, Irtich, Karacyk and Chany Lake is analysed. The level of the infection of bithyniid snails by trematodes (parthenitae and cercariae) does not exceed one percent in different reservoirs. The similar data have been obtained during long-term studies in the estuare of the Kargat river, and in the Ob river (near Novosibirsk). The percentage of infected B. tentaculata was significantly higher than of infected B. troscheli in the total (1.79 and 0.32% accordingly, χ² = 95.1, p < 0.001), and in different reservoirs, too. The infected bithyniid snails are recorded in waterbodies of all four basins only in steppe (0.52 ± 0.37%) and forest-steppe zones (0.76 ± 0.07%). Bithyniid snails from waterbodies of the forest zone of the West Siberian Plain were not infected with parthenitae and cercariae of the family Notocotylidae.     

Reduction of marine phytoplankton reproduction rates by copper and cadmium

The reproduction rates of 38 clones of marine phytoplankton were measured in media in which free cupric ion activity was controlled at different levels using a NTA-cupric ion buffer system. The major trend among species in their resistance to copper toxicity was a phylogenetic one, with cyanobacteria being the most sensitive, diatoms the least sensitive, and coccolithophores and dinoflagellates intermediate in sensitivity. The reproduction rates of most of the cyanobacteria were reduced at cupric ion activities above 10⁻¹² M, while most eukaryotic algae still had maximum reproduction rates at 10⁻¹¹ M. Four species, Emiliana huxleyi (Lohm.) Hay & Mohler, Skeletonema costatum (Grev.) Cleve, Thalassiosira pseudonana (Hustedt) Hasle & Heimdal and Thalassiosira oceanica (Hustedt) Hasle were particularly resistant to copper, being able to reproduce well at the highest cupric ion activities tested, 10^−9.5 M and 10^−9.2 M. There was no major difference, however, between neritic and oceanic species in their sensitivity to copper.The sensitivity of 20 species of marine phytoplankton to free cadmium ion activity was measured in a similar manner using an NTA-cadmium ion buffer system. As observed with copper, the prokaryotic cyanobacteria were the most sensitive to cadmium toxicity, diatoms were the least sensitive, and coccolithophores and dinoflagellates were intermediate. All cyanobacteria tested were dead at a cadmium ion activity of 10^−9.3 M whereas the reproduction rates of most of the eukaryotic algae were not reduced significantly until 10^−8.3 M.Comparison of these data with natural concentrations in sea water implies that cadmium is not an important ecological factor in unpolluted waters but natural copper concentrations may inhibit the reproduction of some phytoplankton species, especially cyanobacteria, in upwelled sea water. Copper may influence the seasonal succession of species.     

Chromium removal from water by three species of dyckweeds

The effects of exogenous chromium (Cr) on the growth of three species of duckweeds: Spirodela punctata (G.F.W. Meyer) Thomps., Spirodela polyrhiza (L.) Schleiden and Lem na gibba L., were examined at Cr concentrations ranging from 0.1 to 20 p.p.m. Using ⁵¹Cr radiotracer methodology, it was demonstrated in Experiment 1 that sorption was directly related to ambient Cr concentrations after 8 days of exposure. At and above 1.0 p.p.m. Cr, negative effects on growth were evident, with seasonal variations apparently also affecting Cr uptake and toxicity. Chrome tolerance, based on the percentage of control growth achieved by exposed plants, showed S. polyrhiza to be the least tolerant to Cr, while S. punctata and L. gibba were more tolerant at concentrations above 1.0 p.p.m. In Experiment 2, duckweeds grown in nutrient-rich water with an initial concentration of 10 p.p.m. exhibited substantial growth, with bioaccumulation of Cr increasing with time.The possible use of various types of biological treatment systems for the removal of Cr from wastewater is discussed.     

In vitro effects of bis(N-[4-(hydroxyphenyl)methyl]-2-pyridinemethamine)zinc perchlorate monohydrate 4 on the physiology and interaction process of Leishmania amazonensis

Leishmaniasis is one of the most relevant neglected tropical diseases in the world, affecting 14 million people. Despite the high morbidity, mortality and socio-economic impact, few therapeutic options are available for this disease. To make matters worse, the available molecules have several limitations such as limited efficacy, high cost, side effects and increased resistance. In this context, our group previously synthesized new compounds with anti-leishmania potential being the bis(N-[4-(hydroxyphenyl)methyl]-2-pyridinemethamine)zinc perchlorate monohydrate 4 (complex 4) the most promising one. Therefore, this present work revealed some morphological and physiological changes promoted by complex 4 on Leishmania amazonensis promastigotes as well as it was evidenced its potential against intramacrophage amastigotes. Complex 4 promoted a progressive reduction on the promastigotes size and a remarkable increase on the granularity/complexity as judged by flow cytometry. Transmission electron microscopy (TEM) analysis revealed extensive mitochondrial and plasma membrane alterations, although plasma membrane integrity remained. The mitochondrial changes observed by TEM were accompanied by a decrease in the activity of mitochondrial dehydrogenases with increased production of reactive oxygen species. Interestingly, promastigotes also showed changes in lipid metabolism. Besides the very low toxicity to macrophages, complex 4 had a great effect on intramacrophage amastigotes, displaying an IC₅₀ of 3.91 μM. Collectively, the data presented here reinforce the potential of aminopyridyl compounds complexed to zinc against L. amazonensis. Thus, our work serves as a basis for in vivo assays to be designed or even the synthesis of more selective/effective compounds with lower cost.     

Toxicity of common biocides used in aquaculture to embryos and larvae of Brachymystax tsinlingensis Li

Brachymystax tsinlingensis Li is a threatened fish species endemic to China. With the problems of environmental factors and seeding breeding diseases, it is important to further improve the efficiency of seeding breeding and the basis of resource protection. This study investigated the acute toxicity of copper, zinc and methylene blue (MB) on hatching, survival, morphology, heart rate (HR) and stress behaviour of B. tsinlingensis. Eggs (diameter: 3.86 ± 0.07 mm, weight: 0.032 ± 0.004 g) of B. tsinlingensis were selected randomly from artificial propagation and developed from eye-pigmentation-stage embryos to yolk-sac stage larvae (length: 12.40 ± 0.02 mm, weight: 0.03 ± 0.001 g) and exposed to different concentrations of Cu, Zn and MB for 144 h in a series of semi-static toxicity tests. The acute toxicity tests indicated that the 96-h median lethal concentration (LC₅₀) values of the embryos and larvae were 1.71 and 0.22 mg l⁻¹ for copper and 2.57 and 2.72 mg l⁻¹ for zinc, respectively, whereas the MB LC₅₀ after 144-h exposure for embryos and larvae were 67.88 and 17.81 mg l⁻¹, respectively. The safe concentrations of copper, zinc and MB were 0.17, 0.77 and 6.79 mg l⁻¹ for embryos and 0.03, 0.03 and 1.78 mg l⁻¹ for larvae, respectively. Copper, zinc and MB treatments with concentrations greater than 1.60, 2.00 and 60.00 mg l⁻¹, respectively, led to a significantly low hatching rate and significantly high embryo mortality (P < 0.05), and copper and MB treatments with concentrations greater than 0.2 and 20 mg l⁻¹ led to significantly high larvae mortality (P < 0.05). Exposure to copper, zinc and MB resulted in developmental defects, including spinal curvature, tail deformity, vascular system anomalies and discolouration. Moreover, copper exposure significantly reduced the HR of larvae (P < 0.05). The embryos exhibited an obvious change in behaviour, converting from the normal behaviour of emerging from the membrane head first to emerging tail first, with probabilities of 34.82%, 14.81% and 49.07% under copper, zinc and MB treatments, respectively. The results demonstrated that the sensitivity of yolk-sac larvae to copper and MB was significantly higher than that of embryos (P < 0.05) and that B. tsinlingensis embryos or larvae might be more resistant to copper, zinc and MB than other members of the Salmonidae family, which benefits their resource protection and restoration.     

Isolation and properties of the outer membrane of plant mitochondria.

The outer membrane of turnip (Brassica rapa L.) mitochondria was isolated by incubating the mitochondria with a dilute digitonin solution and differential centrifuging. The outer membrane fraction was not contaminated by inner membrane enzymes and lacked an NADPH-cytochrome c reductase. However it possessed very active NADH-cytochrome c, dichloroindophenol and ferricyanide reductases which were insensitive to antimycin A, Amytal and low (less than 10 μm) concentrations of Dicumarol. p-Chloromercuribenzoate (ClHgBzO^?) and high concentrations (greater than 10 μm) of Dicumarol inhibited the reductases, ClHgBzO^? almost completely. Preincubation of the outer membrane with NADH protected it from ClHgBzO^? inhibition. An acid phosphatase and an NADPH-ferricyanide reductase were also detected, but the latter was only loosely bound to the membrane. The NADH dehydrogenase of the outer membrane was insensitive to ethylene glycol-bis(β-aminoethyl ether)N,N′-tetraacetate (1 mm) and was not stimulated by CaCl₂ (0.5 mm), thus differing from the external NADH oxidase of the inner membrane (Coleman, J. O. D., and Palmer, J. M. (1971) FEBS Lett., 17, 203–208). Respiratory-linked oxidation of exogenous NADH by intact mitochondria showed a similar pattern of inhibition by ClHgBzO^? as did the outer membrane, but was inhibited strongly by low concentrations of Dicumarol (5 μm inhibited by 70%).     

A preliminary study of the use of benthic algae as biological indicators of heavy metal pollution in Sørfjorden,Norway

Concentrations of zinc, copper, lead and cadmium in seawater and in some benthic algae from Sørfjorden are reported. The concentration factors for Fucus vesiculosus and Ascophyllum nodosum are in good agreement with values given by other authors, even though the zinc concentrations are about ten times larger than those found in most previous work. The concentration factors obtained for zinc and cadmium are essentially the same in the whole area; however, for copper and lead the values decrease towards the mouth of the fjord.     

Alteration of Plasma Trace Elements in Patients Undergoing Open Heart Surgery

Trace elements may contribute to myocardial dysfunction and susceptibility of the phospholipid cell membrane to free-radical damage and oxidative changes. We studied the concentration of trace elements copper, zinc, and magnesium in cardiac surgery. Fifty-four consecutive patients for elective coronary artery bypass grafting (n?=?30) and valve replacement (n?=?24) were studied. Blood samples were collected every 30 min (T1–T5) during cardiopulmonary bypass and postoperatively (T6–T9). Plasma concentrations of copper, zinc, and magnesium were measured with flame atomic absorption spectrophotometry. The concentrations of copper, zinc, and magnesium were significantly different during and after cardiopulmonary bypass (p?<?0.01). The zinc concentration at T7 and T8 (p?<?0.01) and the copper concentration at T1, T9 (p?<?0.05) were significantly different between two groups. However, the magnesium concentration had no significant differences between the two groups (p?>?0.05). In patients undergoing valve replacement or coronary artery bypass grafting, the concentrations of copper and zinc decreased significantly during cardiopulmonary bypass. Our study suggests that the current cardiopulmonary bypass protocol is adequate in the maintenance of c magnesium. However, the low copper and zinc concentrations found in the present study may suggest that in the future, supplementation particularly of copper and zinc may become a necessary procedure in cardiac surgery with cardiopulmonary bypass.     

The role of zinc chelate of hydroxy analogue of methionine in cadmium toxicity: effects on cadmium absorption on intestinal health in piglets

Cadmium (Cd) is a toxic heavy metal that poses a threat to the health of humans and animals. It can cause serious damage to the small intestine, which is the main absorption site of Cd and the primary target organ after oral administration. Our previous study found that zinc chelate of hydroxy analogue of methionine (Zn-HMTB), a new type of feed additive, decreased Cd accumulation in the liver and kidneys. The aim of this study was to investigate the effect of Zn-HMTB on Cd absorption and Cd-induced toxicity in the small intestine of piglets. Twenty-four piglets (Landrace × Large White, 13.22 ± 0.58 kg BW) were randomly divided into four dietary treatment groups: basal diet, and diets containing 30 mg/kg Cd from CdCl₂ and 0, 100 or 200 mg/kg Zn from Zn-HMTB. The experiment lasted 27 days. The feed intake and final BW of each piglet were recorded at the end of the experiment. Gastrointestinal (GI) tract tissue and samples of liver, kidney, spleen, heart, lung and longissimus muscle tissue and faeces were collected. The concentrations of Cd and metal trace elements in the GI tract and organs were analysed, as was the relative messenger RNA (mRNA) expression of inflammatory cytokines and metal element transporters in the small intestine, and epithelial apoptosis in the small intestine. The results showed that, compared with Cd-treated piglets, piglets in the Zn-HMTB and Cd cotreatment groups had less Cd deposition in the stomach, ileum, caecum, colon, liver, kidneys, spleen, lungs, heart and muscles (P < 0.05), and lower Cd concentrations in faeces (P < 0.05), suggesting that Zn-HMTB increased Cd absorption and the excretion of Cd in other forms (possibly urine). Zinc chelate of hydroxy analogue of methionine increased Zn deposition in the jejunum and the relative mRNA expression of divalent metal transporters 1 and zinc transporter 5 in the duodenum (P < 0.05), indicating that Zn-HMTB may promote the absorption and transportation of Cd and Zn together by upregulating metal element transporters. Competition between Zn and Cd may be responsible for accelerating Cd excretion. Furthermore, Zn-HMTB reduced Cd-induced apoptosis of enterocytes and inflammatory stimuli in the small intestine, suggesting that Zn-HMTB reduced Cd-induced toxicity to the small intestine. These results suggest that Zn-HMTB can be helpful in decreasing Cd accumulation in the GI tract and organs of piglets and relieving Cd-induced toxicity to the small intestine but cannot reduce the absorption of Cd.