M. H. Salem

Toxic effects of carbofuran and glyphosate on semen characteristics in rabbits

The present study was undertaken to investigate the effect of chronic treatment with two sublethal doses of Carbofuran (carbamate insecticide) and Glyphosate (organophosphorus herbicide) on body weight and semen characteristics in mature male New Zealand white rabbits. Pesticide treatment resulted in a decline in body weight, libido, ejaculate volume, sperm concentration, semen initial fructose and semen osmolality. This was accompanied with increases in the abnormal and dead sperm and semen methylene blue reduction time. The hazardous effect of these pesticides on semen quality continued during the recovery period, and was dose-dependent. These effects on sperm quality may be due to the direct cytotoxic effects of these pesticides on spermatogenesis and/or indirectly via hypothalami-pituitary-testis axis which control the reproductive efficiency.

Protective role of ascorbic acid to enhance semen quality of rabbits treated with sublethal doses of aflatoxin B1

Aflatoxins are toxic to a wide variety of animals, including man. The antioxidant ascorbic acid (AA) plays an important role in various physiological processes in the body including detoxification of different toxic compounds. The objective of this study was to evaluate the effects of AA on productive and reproductive characteristics of mature male rabbits given two sublethal doses (15 or 30 microg/kg of body weight; every other day) of aflatoxin B(1) (AFB(1)). The experiment lasted 18 weeks and included two periods: a treatment period (first 9 weeks) where the animals were given the tested materials, and a recovery period (second 9 weeks) where all the drugs were withdrawn. Results showed that live body weight (LBW), dry matter intake (DMI), relative testes weight (RTW), and serum testosterone were significantly reduced (P<0.05) by treatment with AFB(1) in a dose-dependent manner, and these effects continued during the recovery period. Aflatoxin treatment also decreased (P<0.05) ejaculate volume, sperm concentration, total sperm output, sperm motility index, and semen initial fructose concentration. The negative effects of aflatoxin on semen characteristics were dose-dependent and continued during the recovery period. Treatment with AA increased (P<0.05) LBW, DMI, RTW, serum testosterone concentration, improved semen characteristics, and alleviated the negative effects of AFB(1). Aflatoxin treatment increased (P<0.05) the numbers of abnormal and dead sperms in a dose-dependent manner, and this effect continued during the recovery period. Treatment with AA alleviated the negative effects of AFB1 during treatment and recovery periods. Results demonstrated the beneficial influences of AA in reducing the negative effects of AFB(1) on production and reproduction of male rabbits.

Influence of ascorbic acid supplementation on the haematological and clinical biochemistry parameters of male rabbits exposed to aflatoxin B1.

This study was undertaken to evaluate the effectiveness of L‐ascorbic acid (AA) in alleviating the toxicity of aflatoxin B1 (AFB1) in male New‐Zealand white rabbits. Five rabbits (6 months of age and mean body weight 3.12 kg) per group were assigned to 1 of 6 treatment groups: 0 mg AA and 0 mg AFB1/kg BW (control); 20 mg AA/kg BW; 15 μg AFB1/kg BW; 15 μg AFB1 plus 20 mg AA/kg BW; 30 μg AFB1/kg BW; 30 μg AFB1 plus 20 mg AA/kg BW. Rabbits were orally administered their respective doses every other day for 9 weeks, followed by a 9‐week recovery period where all drugs were withdrawn. Evaluations were made for hemato‐biochemical parameters and enzymatic activities. Results showed that AFB1 significantly (p < 0.05) decreased hemoglobin (Hb), total erythrocytic count (TEC) and packed cell volume (PCV), in a dose‐dependent manner, and these effects were continued during the recovery period. Ascorbic acid caused an increase in these parameters, and alleviated the negative effect of AFB1 during the treatment period. Additionally, serum concentrations of total protein, albumin and glucose were significantly (P < 0.05) declined by treatment with the high dose of aflatoxin and these effects were continued during the recovery period. Ascorbic acid caused non‐significant increases in these parameters and alleviated the harmful effect of AFB1. On the other hand, aflatoxin treatment caused significant increases (P < 0.05) in the activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (AlP) during the treatment period in a dose dependent manner, and this effect was continued during the recovery period, especially with the high dose. Also, treatment with the high dose of aflatoxin caused significant increases (P < 0.05) in cholesterol and total bilirubin. Ascorbic acid caused significant decreases in these parameters and alleviated the harmful effects of AFB1. Whereas, Total leukocyte count (TLC), urea and creatinine were not significantly affected by aflatoxin‐treatment. Generally, it is interesting feature that the treatment with AA alone had no negative effects on most of the previous parameters. Also, the presence of AA could diminished the adverse effects of AFB1 on most of hematological and biochemical values, and enzymatic activities in rabbits.

Effect of organophosphorus (dimethoate) and pyrethroid (deltamethrin) pesticides on semen characteristics in rabbits

The present study was undertaken to determine the effect of chronic treatment with two sublethal doses of Dimethoate (organo-phosphorus) or Deltamethrin (pyrethroid) on body weight and semen characteristics in adult male rabbits. Pesticide treatment resulted in a decline in body weight, libido, ejaculate volume, sperm concentration and semen initial fructose; and an increase in abnormal and dead sperm and methylene blue reduction time. In this regard Dimethoate showed greater effects than Deltamethrin. The hazardous effect of these pesticides on semen quality continued during the post-treatment period, and was dose-dependent. This deleterious effect on sperm formation together with the decline in libido suggest a decrease in testosterone secretion by pesticide treatment.

Reproductive toxicological effects of gossypol on male rabbits: semen characteristics and hormonal levels

The objective of this study was to evaluate the effects of two sublethal doses (4 and 20 mg/kg live weight (LW); every other day) of gossypol on semen and hormonal characteristics of male rabbits. The experiment lasted 16 weeks and included two periods: a treatment period (first 8 weeks) where the animals were given the test materials, and a recovery period (second 8 weeks) where drugs were withdrawn. Results showed that LW and respiration rate (RR) decreased ( P P P 3 ) and testosterone. This was accompanied by reductions ( P P P 3 and testosterone returned to control levels after withdrawal of gossypol, while the effect of this drug on other parameters continued during the recovery period.

A sensitive sperm‐motility test for the assessment of cytotoxic effect of pesticides

A sensitive sperm-motility test for the evaluation of cytotoxic effects of carbofuran and glyphosate in a defined protein-free culture medium is described. The sperm motility was compared to that obtained with a protein-containing medium. The use of protein-free medium considerably increased the sensitivity of sperm cells from rabbit and human to the toxic effects of the pesticide. The respective IC50 values (the concentration needed to cause 50% inhibition of sperm motility) in protein-free medium of carbofuran and glyphosate were 321 and 48.2 microM with human sperm, and 116 and 23.5 microM with rabbit sperm. Whereas, the corresponding values in protein-containing medium were 920 and 740 microM, and 910 and 500 microM with human and rabbit sperm, respectively. Our results show that testing human and rabbit sperm in protein-free medium proves to be a more sensitive method than that in protein-containing medium. Additionally, the use of rabbit sperm is a more sensitive test system than human sperm. This study suggests that the rabbit sperm test appears to have a potential for the assessment of toxicity on human reproduction.

In vitro gossypol induced spermatozoa motility alterations in rabbits

The objectives of the present study were to: (i) examine the in vitro dose response of rabbit spermatozoa motility to the antifertility agent gossypol (GOS) and (ii) determine whether filtered (FIL) and unfiltered (UNFIL) GOS differ in their magnitude of effect. Rabbit semen belonging to adult males (n = 5; 12–14 months) were cultured with UNFIL GOS and FIL GOS (5% solution) and subsequently diluted (1:1–7) for analysis using a Computer Assisted Semen Analyzer (CASA) system in 5 time periods (0, 60, 120, 180 and 360 minutes). At Time 0, no significant change in rabbit spermatozoa motility (MOT) and progressive motility (PROG) with GOS FIL was noted, while increases were observed with GOS UNFIL. At Time 60, weak changes were noted for MOT and PROG. After 120 minutes of culture with both GOS FIL and GOS UNFIL, MOT and PROG decreased significantly in some experimental groups. However, no differences were recorded for both the parameters at Times 180 and 360, with the exception of PROG in the GOS UNFIL category (groups A, B, E, F and G), where a significant decrease was noticed. Detailed evaluation of the distance and velocity parameters revealed reduction in all these studied markers after 60 and 120 minutes of in vitro culture with both GOS FIL and GOS UNFIL, indirectly confirming the PROG decrease. Straightness (STR), linearity (LIN), wobble (WOB), amplitude of lateral head displacement (ALH) and beat cross frequency (BCF) mostly remained unaltered at all time periods for GOS FIL, where as some minor alterations were noticed in GOS UNFIL category for STR, LIN, WOB, ALH and BCF parameters at Time 0, 60 and 120. The present study confirms the dose and time dependent alterations of rabbit spermatozoa motility parameters by GOS. The GOS dynamics in our experiment shows that rabbit spermatozoa as a biological material can indicate a GOS inhibition of motility. Obtained data for the first time indicates a higher immobilizing potential of unfiltered GOS in comparison to filtered GOS in its inhibitory action of spermatozoa motility parameters in rabbits.

In vitro effect of profenofos, fenvalerate and dimilin on protein and RNA biosynthesis by rabbit liver and muscle tissues

The present study was carried out to investigate the effect of Curacron (profenofos), Sumicidin (fenvalerate) and Dimilin (difluobenzuron) on the in vitro rate of protein and RNA synthesis by rabbit liver and muscle tissues. The synthesis of protein and RNA were significantly stimulated in the liver and inhibited in the muscle by graded doses of these insecticides. Profenofos showed maximum effect on protein synthesis in both tissues at a dose of 0.2 microgram/mL, while the maximum effect on RNA synthesis occurred at 0.2 microgram/mL, while the maximum effect on RNA synthesis occurred at 0.2 microgram mL in the liver and at 2 micrograms/mL in the muscle. Fenvalerate caused maximum stimulation in both liver protein and RNA synthesis at a dose of 2 micrograms/mL, and maximum inhibition in the muscle at 10 and 0.2 micrograms/mL for protein and RNA synthesis respectively. The maximum effect of Dimilin on both tissues was reached at 5 micrograms/mL for protein synthesis and at 0.2 microgram/mL for RNA synthesis. The effect of Dimilin on RNA synthesis was more pronounced in both tissues than its effect on protein synthesis, but this trend was reversed in the case of profenofos and fenvalerate. Present data also showed antagonism between these insecticides on the rate of protein and RNA synthesis.

In vitro effect of aflatoxin B1 on the transcriptional activity of DNA template, chromatin and soluble DNA-dependent RNA polymerases in buffalo liver

The effect of aflatoxin B1 on the DNA template and DNA-dependent RNA polymerases in buffalo liver was studied. Aflatoxin B1 inhibited both Mg2+- and Mn2+-activated RNA polymerases in a dose-dependent manner. At 10 micrograms the inhibition of both enzymes was almost complete. The inhibitory effect on the solubilized enzymes was higher than the chromatin-bound, suggesting a direct effect at the enzyme level. On the other hand, incubating DNA or deoxyribonucleoprotein (DNP) with 2 micrograms aflatoxin reduces its transcriptional capacity with a greater effect on the Mg2+-activated RNA polymerase than the Mn2+-activated enzyme. These results suggest that aflatoxin B1 inhibits in vitro transcription in buffalo liver at both enzyme and template levels.

Isolation, purification and characterization of enzyme(s) responsible for .conversion of sterigmatocystin to aflatoxin B1

ZusammenfassungZellfreie Extrakte vonAspergillus flavus ATCC 5517/A 228 waxen aktiv bei der Umwandlung von Sterigmatocystin in Aflatoxin B1. Der Extrakt wurde mit Ultrogel ACA-54 gereinigt und ergab 10 Proteinpeaks, von denen Peak VI aktiv bei der Sterigmatocystin-Umwandlung war. Dieses Protein ergab eine Bande bei der PAG-Elektrophorese; zusätzlich wurde dieses auf der DEAE-Sephadex A-50-Säule gereinigt und dabei 2 Proteinpeaks festgestellt. Nur einer dieser Gipfel zeigte enzymatische Aktivitat und ergab eine Bande bei der PAG- und SDS-Elektrophorese. Optimal für die enzymatische Aktivität waren 28 °C und ein pH-Wert von 8. Die maximale Umwandlung wurde mit 0,6 mg Enzymprotein auf 48 × 10−8mol Sterigmatocystin gefunden. Zn2+, Co2+ und Mn2+ beschleunigten die Umwandlung, während EDTA, PHMB und PMSF die enzymatische Aktivität in Abhängigkeit von der angewandten Menge hemmten. Die Aminosäure-Analyse zeigte, daß das Enzym 22 Aminosäuren enthält, von denen drei unbekannt waren. Das Enzym hatte ein Molekulargewicht von 64 000 dalton bei der Gelfiltration bzw. 70 000 dalton bei der SDS-PAGE.SummaryThe cell-free extract prepared fromAspergillus flavus ATCC 5517/A 228 showed activity in converting sterigmatocystin to aflatoxin B1. The extract was purified on Ultrogel AcA-54 and resulted in ten protein peaks, one of which (peak VI) showed activity in sterigmatocystin conversion. The protein in this peak gave one protein band using polyacrylamide gel (PAG)-disc electrophoresis. For further purification, protein(s) in peak VI were applied on DEAE-Sephadex A-50 and two protein peaks were detected. Only one peak showed enzyme activity which showed homogeneity as one band on PAGE and sodium dodecyl sulphate (SDS)-PAGE. The optimum temperature for the enzyme activity was 28 °C and the optimum pH was 8. The maximum conversion resulted from the action of 0.6 mg enzyme protein on 48 × 10−8mol Sterigmatocystin. Zn2+, Co2+ and Mn2+ enhanced the enzyme acitivity, while ethylenediaminetetraacetic acid, parahydroxymercuric benzoate and phenylmethylsulphonic fluoride inhibited the enzyme activity in a dose-dependent manner. Amino-acid analysis showed the presence of 22 amino acids, three of which are unknown. The enzyme has a molecular weight of 64,000 daltons (by gel filtration) and 70,000 daltons (by SDS-PAGE).