Ca2+ homeostasis alterations induced by 2,4-dichlorophenoxyacetic butyl ester and 2,4-dichlorophenoxyacetic acid on avian skeletal muscle

Discrepant effects of copper (II) stress on different types of skeletal muscles in chicken: Elements and amino acids

Different distributions of 28 elements and 17 amino acids in pectoralis, wing biceps brachii and leg gastrocnemius of chicken upon CuSO₄ (300 mg/kg) exposure for 90 days were investigated. Accompanied by copper accumulation, pathological injuries were observed in those three kinds of skeletal muscles using histological and ultrastructural methods. Based on data obtained, we analyzed leg gastrocnemius displayed the most increases (P < 0.000) in all three kinds of elements detected, including macroelements (131%), essential microelements (129%) and toxic microelements (179%) than the other two skeletal muscles. Furthermore, decreased total amino acids (P = 0.006), a susceptibility of lipid peroxidation/oxidative stress and a disequilibrium of nutrition and taste were analyzed in the leg gastrocnemius, indicating an unsuitability for human consumption. Intriguingly, these anomalies were scarce in pectoralis and wing biceps brachii. Combined with multivariate analysis we may conclude that leg gastrocnemius are more vulnerable to copper stress than pectoralis and wing biceps brachii in chicken.

The action of 2,4-Dichlorophenoxyacetic acid on the isolated heart of insect and amphibia

The action of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) on the isolated heart of the frog (Rana ridibunda) and two insects, the honeybee (Apis mellifera macedonica) and the beetle (Tenebrio molitor), was investigated using basic electrophysiological methods. The results of this study showed that a concentration of 1 μM 2,4-D was required to reduce the force and the frequency of the isolated heart of the honeybee to about 70% of the initial contraction in less than 20 min. To cause the same effects on the atria of the frog, 45 μM 2,4-D was required and on the isolated heart of the beetle, over 1000 μM of 2,4-D. The presence of an extensive system of gap junctions found in the honeybee is most probably the cause of the unusual sensitivity of its heart to 2,4-D, compared with the heart of the beetle, where no gap junctions were identified.

In vivo and in vitro binding of 2,4-dichlorophenoxyacetic acid to a rat liver mitochondrial protein

2,4-dichlorophenoxyacetic acid (2,4-D) is a hormonal herbicide widely used in the world because of its efficacy in the control of broadleaf and woody plants. In this study we have demonstrated in vivo covalent binding of the phenoxyherbicide 2,4-D to a single protein of 52 kD (from rat liver mitochondrial preparation) detected through immunoblotting studies with the specific antiserum for 2,4-D. The direct involvement of 2,4-D in the formation of the adduct has also been demonstrated in vitro, using liver mitochondrial preparations exposed to 14C-UL-2,4-D. Radiolabeled protein separated by SDS-PAGE and afterwards electroeluted showed a single labeled protein of 52 kD. When mitochondria exposed to radiolabeled xenobiotic were devoid of their outer membrane, the specific activity observed suggest that protein involved in covalent interaction belongs to the inner mitochondrial membrane. We propose that covalent binding of the phenoxyherbicide 2,4-D to a very specific single protein of 52 kD observed in vitro and in vivo may be related to known alterations of the mitochondrial function.

Characterization of 2,4-dichlorophenoxyacetic acid transport and its relationship with polyamines in Azospirillum brasilense

We have previously shown that 2,4-dichlorophenoxyacetic acid (2,4-D) inhibits Azospirillum brasilense growth, the synthesis of DNA, RNA and proteins. These toxic effects are prevented when polyamines are added to the culture medium. The purposes of our research were to determine the effects of the herbicide on the number of viable Azospirillum brasilense cells, characterize the 2,4-D transport system and to study the effects of polyamines upon the latter in this microorganism. We found that 2,4-D reduced the number of viable cells and that 2,4-D transport is energy-independent, since it was not affected by metabolic inhibitors. Polyamines did not alter 2,4-D uptake, further supporting the hypothesis that the herbicide most likely produces its toxic effects by interfering with the polyamine metabolism.

Effects of 2,4-dichlorophenoxyacetic acid on Rhizobium sp. growth and characterization of its transport

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) produced a deleterious effect on the growth of Rhizobium sp. M4, that was reversed by transferring the cells to a fresh control medium. The uptake of 2,4-D by Rhizobium sp. was not affected by chloramphenicol, indicating that it is constitutive rather than inducible. The mechanism of transport also appears to be energy independent, since uptake was not inhibited by azide or arsenate.

Biochemical alterations in skeletal muscle induced by 2,4-dichlorophenoxyacetic butyl ester during chick embryonic development

2,4-Dichlorophenoxyacetic butyl ester (2,4-D b.e.) (3.1 mg/egg) was applied on fertile hen eggs before starting the incubation. Chicks hatched from treated eggs showed motor dysfunctions, postural troubles and edematous muscles. The electromyography revealed muscular weakness, prolonged motor distal latency, and myotonia. The biochemical composition of leg and complexus muscles from 1-day-old chicks was determined. A significant diminution (24%) in the glycogen level of leg muscles was produced by the treatment. There was a small increase (15%) in sarcoplasmic proteins from leg muscles and an increase of a 20 kD protein in the myofibrillar proteins from complexus muscles. Even though total lipid content was not changed, 2,4-D b.e. treatment produced a diminution of sterol esters (20%) and phosphatidylcholine (11%) and an increase of phosphatidylserine (61%), triglycerides (37%) and free fatty acids (FFA) (448%) in leg muscles. Increases of phosphatidylethanolamine (16%), sterols (58%) and FFA (267%) were detected in complexus muscles. A remarkable increase (700-1500%) of unsaturated FFA, e.g. oleic, linoleic and arachidonic acids, was observed. Considering the avian embryo lipid metabolism, it is proposed that FFA and triglycerides were accumulated because they could not be metabolized in the mitochondria. Since FFA are potent cytotoxic compounds, their increase may be a key factor in the 2,4-D b.e. toxic action in muscle and other tissues during embryonic development.