Micronuclei in mouse bone-marrow cells. A simple in vivo model for the evaluation of drug-induced chromosomal aberrations

For studying, in vivo, chromosomal damage in bone-marrow cells of CD mice the following compounds were used: Trenimon®; Endoxanm® (cyclophosphamide); triethylenemelamine (TEM); methyl methanesulfonate (MMS); ethyl methanesulfonate (EMS); mitomycin C; colchicine; N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) and caffeine. In a first set of experiments the compounds were given twice intraperitoneally with an interval of 24 h. In a second set, effects on bone marrow were studied after 2 i.v. or p.o. administrations of TEM or EMS. All compounds except MNNG and caffeine produced bone-marrow depression and micronuclei, depending on the dose. For the active compounds an interesting difference was revealed by a comparison of the lowest effective dose (as measured by micronuclei formation) with the lethal dose. Trenimon, TEM, cyclophosphamide and MMS (some of which are used in human chemotherapy in similar mg/kg doses) were active on mouse bone-marrow at very low doses compared with their lethal doses. On the other hand, colchicine, mitomycin C and EMS exhibited an effect only at doses very close to, or within, the toxic range. Different routes of administration of either TEM or EMS produced similar effects.The results indicate that the test is especially suitable for initial large-scale screening of suspected chromosomal mutagens and spindle poisons. In addition, the use of the relationship between doses required to induce micronuclei and lethal doses in mice provides a practical measure of the relative potencies of such compounds.     

Micronucleus test with vincristine sulfate and colchicine in peripheral blood reticulocytes of mice using acridine orange supravital staining.

The induction of micronuclei in mouse peripheral blood reticulocytes (RETs) was studied with the spindle poisons vincristine sulfate (VINC) and colchicine (COL) using acridine orange (AO) supravital staining. Each chemical was studied independently in two laboratories using the same protocol. Blood samples were prepared at 0, 24, 48, and 72 h after a single intraperitoneal treatment with VINC (0.0625, 0.125, and 0.25 mg/kg) or COL (0.25, 0.5, 1.0, and 2.0 mg/kg). Both VINC and COL induced micronucleated RETs (MNRETs) significantly and dose-dependently with a peak at 48 h after treatment. Maximum frequencies of micronucleated polychromatic erythrocytes (MNPCEs) were observed 24 h after treatment with VINC; thus, the transition time from MNPCEs to MNRETs was about 24 h. Both spindle poisons gave comparable results in the paired laboratories, indicating that the present AO supravital staining method is highly reproducible.     

Effect of 17α-methyl testosterone incorporated diets on growth of spotted snakehead,Channa punctatus and white carp,Cirrhinus mrigala

The effect of different concentrations of 17α-methyl testosterone incorporated diet on growth performance in the fry of Channa punctatus and Cirrhinus mrigala was evaluated. Four different doses of hormone such as 60, 80, 100 and 120?mg/kg in C. punctatus and 40, 60, 80 and 100?mg/kg in C. mrigala were administered through diet for a period of 90?days.Fifth group on a hormone free diet served as a control. The growth performance in terms of length and weight gain of the fry receiving 100?mg/kg in C. punctatus and 60?mg/kg in C. mrigala were significantly higher than those receiving 80, 120 and 0 (untreated control) mg hormone per kg feed. The highest specific growth rate (0.864?±?1.18%WG d^?1) at 100?mg/Kg diet and (2.47?±?1.26%WG d^?1) at 60?mg/kg diet were observed in C. punctatus and C. mrigala respectively, showing positive influence of hormone incorporated diet on the growth performance. However, the survival rate of both the species remained unaffected by different dosages of 17α-methyl testosterone.     

Studies on micronuclei time response and on the effects of multiple treatments of mutagens on induction of micronuclei

Micronuclei time response and the effects of multiple treatments of mutagens on induction of micronuclei were studied. In the time-response investigation, mice were treated once with each of 5 mutagens, then killed at various times. The bone marrow was examined for the presence of micronucleated erythrocytes (MNEs). The maximal frequencies for MNEs occurred around 30 h post treatment for all mutagens tested. To examine the effects of multiple treatments, the frequencies of MNEs observed after a single- or a 5-treatment schedule were compared for 9 mutagens. Both treatment schedules were equally sensitive in detecting alkylating agents and spindle poisons, whereas the 5-treatment schedule was more sensitive for anti-metabolites. The 5-treatment schedule was particularly effective for detecting the anti-metabolites 5-fluorouracil and methotrexate, which require longer than 30 h to induce micronuclei (Maier and Schmid, 1976). These results suggest that it is practicable to sample at 30 h in the single-treatment schedule, and seem to support the usefulness of the 5-treatment schedule in screening tests.     

Stains recently certified

The micronucleus test (Schmid 1975) is widely used as an indicator of cytogenetic damage induced in vivo by clastogens and spindle poisons. Yamamoto and Kikuchi (1980) have recently showed that by comparing the relative size of micronuclei it is possible to determine whether an agent acts as a clastogen or a spindle poison. This finding will undoubtedly increase the use of the technique in routine protocols for the testing of chemicals. Besides, the test is quite sensitive and much simpler and faster than chromosome analysis. One obstacle, however, hinders several laboratories: the increasing unavailability of fetal calf serum. Recently, Das and Kar (1980) have proposed sodium citrate as a substitute for fetal calf serum. However, 1% sodium citrate solution is hypotonic, which fact may pose difficulties for an experimenter having to sacrifice several animals within a short time, a common situation in routine tests. We were able to overcome the problem of hypotonia by replacing fetal calf serum with the isotonic solutions 0.9% NaCl and Ringer's saline for mammals (9.00 g NaCl, 0.42 g KCl, 0.24 g CaCl₂, 0.20 g NaHCO₃, 1000 ml distilled. H₂O) at room temperature.     

Effects of thioglycolic acid on in vivo oocytes maturation in mice

Background

Thioglycolic acid (TGA) is widely used in the hairdressing industry, which mostly caters to women. Recently, TGA has been reported to impair several organs, especially reproductive ones such as testes and ovaries. The reproductive toxicity of TGA on females has become an issue that cannot be neglected.

Methodology/Principal Findings

In the present work, superovulated female mice were percutaneously treated with different doses of TGA (37.81, 75.62, and 151.25 mg/kg). The mice were sacrificed to collect ovulated oocytes, whose numbers were counted and compared. Immunofluorescence-stained oocytes were observed under a confocal microscope to investigate the effects of TGA on spindle morphology, distribution of cortical granules (CGs), and parthenogenetic activation. The number of ovulated oocytes was decreased by TGA. The ovulated oocytes in the 151.25 mg/kg TGA group were significantly less than in the control and in the 37.81 mg/kg TGA groups. The ovulated oocytes in the 75.62 mg/kg TGA group were less than in the 37.81 mg/kg dose group. Abnormal spindle configuration in vivo was also induced by TGA. The spindle areas in the 75.62 and 151.25 mg/kg TGA groups were significantly larger than in the control and 37.81 mg/kg TGA groups. The parthenogenetic activation of ovulated oocytes in vitro was inhibited as well. The percentage of activated oocytes in the 75.62 and 151.25 mg/kg TGA groups was significantly lower than in the control and 37.81 mg/kg TGA groups. The percentage in the 151.25 mg/kg TGA group was also less than in the 75.62 mg/kg group. CG distribution was not affected by TGA.

Conclusion

Mice were percutaneously treated with TGA. Consequently, the number of ovulated oocytes decreased, abnormal spindle configurations were induced, and the parthenogenetic activation of ovulated oocytes was inhibited. CG distribution was not affected.     

Effects of Zinc Glycinate on Productive and Reproductive Performance,Zinc Concentration and Antioxidant Status in Broiler Breeders

An experiment was conducted to investigate the effects of zinc glycinate (Zn-Gly) supplementation as an alternative for zinc sulphate (ZnSO₄) on productive and reproductive performance, zinc (Zn) concentration and antioxidant status in broiler breeders. Six hundred 39-week-old Lingnan Yellow broiler breeders were randomly assigned to 6 groups consisting of 4 replicates with 25 birds each. Breeders were fed a basal diet (control group, 24 mg Zn/kg diet), basal diet supplemented with 80 mg Zn/kg diet from ZnSO₄ or basal diet supplemented with 20, 40, 60 and 80 mg Zn/kg diet from Zn-Gly. The experiment lasted for 8 weeks after a 4-week pre-test with the basal diet, respectively. Results showed that Zn supplementation, regardless of sources, improved (P?<?0.05) the feed conversion ratio (kilogram of feed/kilogram of egg) and decreased broken egg rate, and elevated (P?<?0.05) the qualified chick rate. Compared with the ZnSO₄ group, the 80 mg Zn/kg Zn-Gly group significantly increased (P?<?0.05) average egg weight, fertility, hatchability and qualified chick rate, whereas it decreased (P?<?0.05) broken egg rate. The Zn concentrations in liver and muscle were significantly higher (P?<?0.05) in 80 mg Zn/kg Zn-Gly group than that in ZnSO₄ group. Compared with ZnSO₄ group, 80 mg Zn/kg Zn-Gly group significantly elevated (P?<?0.05) the mRNA abundances of metallothionein (MT) and copper-zinc superoxide (Cu-Zn SOD), as well as the Cu-Zn SOD activity and MT concentration in liver. Moreover, the 80 mg Zn/kg Zn-Gly group had higher (P?<?0.05) serum T-SOD and Cu-Zn SOD activities than that in the ZnSO₄ group. This study indicated that supplementation of Zn in basal diet improved productive and reproductive performance, Zn concentration and antioxidant status in broiler breeders, and the 80 mg Zn/kg from Zn-Gly was the optimum choice for broiler breeders compared with other levels of Zn from Zn-Gly and 80 mg/kg Zn from ZnSO₄.     

Effect of Dietary High Molybdenum on the Cell Cycle and Apoptosis of Kidney in Broilers

The experiment was conducted with the objective of examining the effects of high molybdenum on the cell cycle and apoptosis of kidney in broilers by the methods of flow cytometry. Three hundred 1-day-old Avian broilers were randomly divided into four groups, and fed on diets as follows: control diet (Mo 13 mg/kg) and high molybdenum diets (Mo 500 mg/kg, high molybdenum group I; Mo 1,000 mg/kg, high molybdenum group II; Mo 1,500 mg/kg, high molybdenum group III) for 6 weeks. The results showed that the relative weight of kidney were higher (P?<?0.05 or P?<?0.01), and the cellular percentages of G₀/G₁ phase were lower, and cellular percentages of S phase and the proliferating index were higher in high molybdenum groups II and III than in control group (P?<?0.01). The percentage of renal cell apoptosis was increased in high molybdenum groups II and III when compared with that of control group (P?<?0.01). Immunohistochemical test showed that there were increased frequencies of positive cells containing Bax protein and decreased frequencies of positive cells containing Bcl-2 protein in high molybdenum groups II and III. It was concluded that dietary high molybdenum (1,000 mg/kg and 1,500 mg/kg) impaired the progression of renal cells from S phase to G₂M phase obviously and induced renal cell apoptosis.     

Reversion of apoptotic resistance of TP53-mutated Burkitt lymphoma B-cells to spindle poisons by exogenous activation of JNK and p38 MAP kinases

Defects in apoptosis are frequently the cause of cancer emergence, as well as cellular resistance to chemotherapy. These phenotypes may be due to mutations of the tumor suppressor TP53 gene. In this study, we examined the effect of various mitotic spindle poisons, including the new isocombretastatin derivative isoNH₂CA-4 (a tubulin-destabilizing molecule, considered to bind to the colchicine site by analogy with combretastatin A-4), on BL (Burkitt lymphoma) cells. We found that resistance to spindle poison-induced apoptosis could be reverted in tumor protein p53 (TP53)-mutated cells by EBV (Epstein Barr virus) infection. This reversion was due to restoration of the intrinsic apoptotic pathway, as assessed by relocation of the pro-apoptotic molecule Bax to mitochondria, loss of mitochondrial integrity and activation of the caspase cascade with PARP (poly ADP ribose polymerase) cleavage. EBV sensitized TP53-mutated BL cells to all spindle poisons tested, including vincristine and taxol, an effect that was systematically downmodulated by pretreatment of cells with inhibitors of p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinases. Exogenous activation of p38 and JNK pathways by dihydrosphingosine reverted resistance of TP53-mutated BL cells to spindle poisons. Dihydrosphingosine treatment of TP53-deficient Jurkat and K562 cell lines was also able to induce cell death. We conclude that activation of p38 and JNK pathways may revert resistance of TP53-mutated cells to spindle poisons. This opens new perspectives for developing alternative therapeutic strategies when the TP53 gene is inactivated.     

Establishment of dose-response relationships between doses of Cs-137 γ-rays and frequencies of micronuclei in human peripheral blood lymphocytes

It has been suggested that the yield of micronuclei in human peripheral blood lymphocytes could be used as a biological dosimeter in cases of radiation exposure. In the present study micronuclei were induced in lymphocytes by exposing human blood samples in vitro to various doses of Cs-137 γ-rays. The blood samples were then cultivated using the cytokinesis block method. Coded programs were employed to establish the relationships between the frequencies of micronuclei and various doses of γ-rays. The best fit was obtained by the linear-quadratic model, Y = c + aD + bd², where Y is the yield of micronuclei, D is the dose in Gy and c, a, b, are constants. It seems there is a correlation between the yields of MN in mononuclear cells and the corresponding doses of radiation. Therefore an attempt was made to include these MN in the calculation of the dose-response relationship.     

Behavioral and neurochemical changes in the dopaminergic system after repeated cocaine administration

In order to determine whether repeated cocaine administration produced persistent changes in dopamine (DA) receptor binding and release consistent with behavioral sensitization, rats were treated with either cocaine (25 mg/kg ip) or saline twice daily for 14 consecutive days followed by a 3-d withdrawal period. The DA transporter site was assayed using [³H]GBR 12935, whereas D₁ and D₂ sites were assayed using [³H]SCH 23390 and [³H]spiperone, respectively. The density (B _max) of the DA transporter binding sites in the ST of the cocaine-treated group increased significantly (p<0.05) over controls 3 d after the last injection, whereas the density of striatal D₁ and D₂ binding sites remained unchanged. The DA transporter in the nucleus accumbens (NA) was also studied with [³H]GBR 12935 and was unchanged following drug treatment. D₁ and D₂ binding parameters for the NA were not determined in this study. Furthermore, cocaine administration did not affect the affinities (K _d ) of the radioligands used to label the transporter, D₁, or D₂ sites in any of the studies performed. In addition, striatal DA release was measured using in vivo microdialysis in anesthetized rats. Linear regression analysis on maximal decreases in DA release after apomorphine (0.02, 0.2, and 2.0 mg/kg sc) injection showed no difference in the functional capacity of the ST to modulate DA transmission between control and treated groups. Moreover, animals pretreated with cocaine showed a significant (p<0.01) decrease in locomotor activity (LA) after a presynaptic, autoregulating dose of apomorphine (0.03 mg/kg sc) was given. These results suggest that the effects seen after repeated exposure to cocaine may be regulated, in part, by changes in striatal DA transporter binding site densities and not necessarily by DA-releasing mechanisms or D₁ and D₂ receptor modification.     

Dopaminergic Regulation of Striatal Acetylcholine Release: The Critical Role of Acetylcholinesterase Inhibition

Abstract: This study examined the effects of different levels of acetylcholinesterase (AChE) inhibition on dopaminergic regulation of striatal acetylcholine (ACh) release as estimated by in vivo brain microdialysis. Systemic administration of d-amphetamine (2 or 10 mg/kg) increased the striatal output of ACh when the AChE inhibitor neostigmine (0.1 µM) was present in the perfusion fluid. In contrast, when the same experiments were conducted at 0.01 µM neostigmine, d-amphetamine failed to affect (2 mg/kg) or significantly decreased (10 mg/kg) striatal ACh output. The inhibitory action of the D₂ receptor agonist quinpirole (0.2 mg/kg) was significantly greater at 0.01 µM than at 0.1 µM neostigmine. Similarly, there was a nonsignificant trend for the D₂ antagonist raclopride (1 mg/kg) to stimulate ACh release to a greater extent at the low neostigmine concentration. In contrast, the stimulant effects of systemic administration of the D₁ agonist A-77636 (1.46 mg/kg) on striatal ACh release were the same at the two neostigmine concentrations. These results demonstrate that the concentration of an AChE inhibitor in the perfusion solution can quantitatively and even qualitatively influence the manner in which dopaminergic agents regulate ACh overflow in the striatum. On comparing the present results with earlier reports concerning the effects of d-amphetamine on tissue concentrations of ACh, it is tentatively concluded that a low neostigmine concentration is the more physiologically relevant condition. Under such conditions, at moderate doses d-amphetamine does not appear to alter striatal ACh release, with this likely being due to the opposing actions of D₁ and D₂ receptors. Nevertheless, until the endogenous interstitial concentrations of striatal ACh can be measured by other methods, the physiological relevance of ACh microdialysis studies in the striatum will remain uncertain.     

Effects of Copper-Loaded Chitosan Nanoparticles on Intestinal Microflora and Morphology in Weaned Piglets

The objective of the present study was to investigate the effects of dietary supplementation with copper-loaded chitosan nanoparticles (CNP-Cu) on growth performance, intestinal microflora, and morphology in weaned piglets. A number of 90 weaned piglets (Duroc × Landrace × Yorkshire), weaned at 21?days with body weight of 7.2?±?0.81?kg, were randomly divided into three groups by weight and sex, each treatment including three replicates of ten pigs. The piglets were fed the same basal diet supplemented with 0 (the control group), 100?mg/kg CNP-Cu, and 100?mg/kg chlortetracycline (the positive group). The results showed that 100?mg/kg CNP-Cu significantly increased average daily gain and feed intake and decreased feed/gain ratio and diarrhea rate (P?<?0.05). Compared with the control group, the amount of Escherichia coli in duodenum, jejunal, and caecum were significantly decreased by 100?mg/kg CNP-Cu; the number of lactobacillus in jejunal and caecum were increased (P?<?0.05), and the amount of bifidobacterium in duodenum and caecum were also increased (P?<?0.05). Moreover, the villous height of duodenum, jejunum, and ileum mucosa was significantly increased (P?<?0.05), and the crypt depth was significantly decreased (P?<?0.05). The results indicated that CNP-Cu is beneficial to growth and intestinal microflora and morphology and could be a potential substitution of chlortetracycline in diets of weaned piglets.     

Effects of Nickel Chloride on the Erythrocytes and Erythrocyte Immune Adherence Function in Broilers

This study was conducted to investigate the immune adherence function of erythrocytes and erythrocyte induced by dietary nickel chloride (NiCl₂) in broilers fed on a control diet and three experimental diets supplemented with 300, 600, and 900 mg/kg NiCl₂ for 42 days. Blood samples were collected from five broilers in each group at 14, 28, and 42 days of age. Changes of erythrocyte parameters showed that total erythrocyte count (TEC), hemoglobin (Hb) contents, and packed cell volume (PCV) were significantly lower (p?p?p?p?+/K⁺-ATPase) and calcium adenosine triphosphatase (Ca²⁺-ATPase) activities were significantly decreased (p?p?2-treated groups. The results of erythrocyte immune adherence function indicated that erythrocyte C_3b receptor rosette rate (E-C_3bRR) was significantly decreased (p?p?p?p?2 in excess of 300 mg/kg caused anemia and impaired the erythrocytic integrity, erythrocytic ability to transport oxygen, and erythrocyte immune adherence function in broilers. Impairment of the erythrocytes and erythrocyte immune adherence function was one of main effect mechanisms of NiCl₂ on the blood function.     

Micronuclei and chromosome aberrations in Xenopus laevis spermatocytes and spermatids exposed to adriamycin and colcemid

Cultured testes and spermatocytes from the frog Xenopus laevis have been incubated (40-42 h) with adriamycin or colcemid followed by quantitation of chromosome aberrations in secondary spermatocytes and quantitation of micronuclei in secondary spermatocytes, early round spermatids, and round spermatids with acrosomal vacuoles (AV) at 18-162 h of culture. Micronucleus frequencies were consistently higher in secondary spermatocytes relative to round spermatids after exposure to either adriamycin or colcemid due to a higher rate of micronucleus formation during meiosis I compared to meiosis II. Also, some of the micronuclei formed during meiosis I did not survive meiosis II to form micronucleated spermatids. Micronucleus formation occurred in 3-7% of secondary spermatocytes with detectable chromosome aberrations, depending upon drug treatment. Thus, the ratio of micronuclei to total chromosome aberrations in secondary spermatocytes was always higher in colcemid-treated cells compared to adriamycin-treated cells following 18- and 42-h treatment periods. Adriamycin induced significant increases in micronuclei in both secondary spermatocytes and spermatids after 162 h of culture, the time for initial pachytene stages to develop into secondary spermatocytes and spermatids. The data show that cultured testes and spermatocytes from Xenopus may be used to quantify specific meiotic chromosome aberrations induced by both clastogens and spindle poisons using either a rapid secondary spermatocyte micronucleus assay or meiotic chromosome analysis.     

Comparison of startup and anaerobic wastewater treatment in UASB, hybrid and baffled reactor

An experimental study was carried out to compare the performance of selected anaerobic high rate reactors operated simultaneously at 37?°C. The three reactors, namely upflow anaerobic sludge bed reactor (UASB), hybrid of UASB reactor and anaerobic filter (anaerobic hybrid reactor – AHR) and anaerobic baffled reactor (ABR), were inoculated with the anaerobic digested sludge from municipal wastewater treatment plant and tested with synthetic wastewater. This wastewater contained sodium acetate and glucose with balanced nutrients and trace elements (COD 6000?mg?·?l^?1). Organic loading rate (B _v ) was increased gradually from an initial 0.5?kg?·?m^?3?·?d^?1 to 15?kg?·?m^?3?·?d^?1 in all the reactors. From the comparison of the reactors' performance, the lowest biomass wash-out resulted from ABR. In the UASB, significant biomass wash-out was observed at the B _v 6?kg?·?m^?3?·?d^?1, and in the AHR at the B _v 12?kg?·?m^?3?·?d^?1. The demand of sodium bicarbonate for pH maintenance in ABR was two times higher as for UASB and AHR. The efficiency of COD removal was comparable for all three reactors – 80–90%. A faster biomass granulation was observed in the ABR than in the other two reactors. This fact is explained by the kinetic selection of filamentous bacteria of the Methanotrix sp. under a high (over 1.5?g?·?l^?1) acetate concentration.     

Physiological Saline Solutions as a Useful Tool in Micronucleus and Metaphase Slide Preparations

The micronucleus test (Schmid 1975) is widely used as an indicator of cytogenetic damage induced in vivo by clastogens and spindle poisons. Yamamoto and Kikuchi (1980) have recently showed that by comparing the relative size of micronuclei it is possible to determine whether an agent acts as a clastogen or a spindle poison. This finding will undoubtedly increase the use of the technique in routine protocols for the testing of chemicals. Besides, the test is quite sensitive and much simpler and faster than chromosome analysis. One obstacle, however, hinders several laboratories: the increasing unavailability of fetal calf serum. Recently, Das and Kar (1980) have proposed sodium citrate as a substitute for fetal calf serum. However, 1% sodium citrate solution is hypotonic, which fact may pose difficulties for an experimenter having to sacrifice several animals within a short time, a common situation in routine tests. We were able to overcome the problem of hypotonia by replacing fetal calf serum with the isotonic solutions 0.9% NaCl and Ringer's saline for mammals (9.00 g NaCl, 0.42 g KCl, 0.24 g CaCl₂, 0.20 g NaHCO₃, 1000 ml distilled. H₂O) at room temperature.     

Regulation of Zinc Transporter 1 Expression in Dorsal Horn of Spinal Cord After Acute Spinal Cord Injury of Rats by Dietary Zinc

Zinc concentrations in the dorsal horn of spinal cord are important for wound healing, neurological function, and reproduction. However, the response of the spinal cord to alterations in dietary zinc is unknown in rats after spinal cord injury (SCI). The current study explored cellular zinc levels and zinc transporter 1 (ZnT1) expression in the dorsal horn of spinal cord with different dietary zinc after SCI. A hundred and forty-four male Wistar rats were randomly divided into four groups: sham-operated group (30?mg Zn/kg), zinc-high dietary SCI model group (ZH, 180?mg Zn/kg), zinc-adequate dietary SCI model group (30?mg Zn/kg), and marginal zinc-deficient dietary SCI model group (MZD, 5?mg Zn/kg). To test the hypothesis that dietary zinc may regulate role of ZnT1 expression in dorsal horn after acute SCI, we traced ZnT1 proteins and zinc ions with immunohistochemistry, western blot, and autometallography. Zinc and ZnT1 levels of the dorsal horn in ZH significantly increased after surgery (P?<?0.05), reached peak level (P?<?0.05) on the seventh day, and subsequently levels of their expression began to decrease. But zinc levels and ZnT1 expression of spinal cord in MZD dietary groups decreased (P?<?0.05) in SCI. There was a positive correlation between ZnT1 protein and zinc content in spinal cord (R?=?0.49880, P?=?0.0492). We found that both zinc and ZnT1 expressions in spinal cord are regulated by dietary zinc. These results indicate that dietary zinc may regulate the expression of ZnT1 in the dorsal horn of spinal cord after SCI. ZnT1 may, at the same time, play a significant role in the maintenance of zinc homeostasis in SCI.     

The neuroblast of the grasshopper embryo as a new mutagen test system: I. In vitro radiosensitivity

The neuroblasts of the grasshopper embryo (Chortophaga viridifasciata De Geer) are being studied to determine their suitability for detecting environmental clastogens (chromosome-breaking agents). They are very sensitive to the induction of chromosome breakage by radiation in vivo. Their sensitity, 0.011 break / cell / R, is 4–5 times higher than pollen mother cells of Tradescantia (micronuclei), 10 times higher than either human lymphocytes or Chinese hamster cells (metaphase chromosome aberrations), and 15 times higher than mouse than mouse erythroblasts (micronuclei). Furthermore, they have no spontaneous chromosome breakage, which facilitates the detection of agents that break chromosomes. The present study shows that Chortophaga embryos maintain normal mitotic activity in vitro for 5 cell cycles at 38°C (20 h), and that neuroblasts of embryos grown in vitro have the same radiosensitivity as those of embryos in vivo. Thus in vitro exposure of grasshopper embryos is a promising method for obtaining data on the response of neuroblasts to chemical clastogens.