Molecular Classification of the Earthworm Aporrectodea trapezoids and the Effect of Sodium Nitroprusside and Norepinephrine on the Contractility of Crop and Gizzard Smooth Muscle

Abstract

Background: Earthworms are considered as one of the ecologically important invertebrates with highly cryptic genetic diversity. Since the morphological methods of classification are unprecise, it is necessary to classify the species depending on molecular bases using PCR techniques. In addition, studying the effect of some agonists such as Sodium nitroprusside (SNP) and Norepinephrine (NE) on the smooth muscle of earthworm is yet poorly studied.

Objective: This study focused on the molecular classification using the mitochondrial COX 1 gene as a DNA marker. In addition, it also included the effect of nitric oxide (NO) donor sodium nitroprusside (SNP) and norepinephrine (NE) on the contractility of crop and gizzard smooth muscle of the earthworm.
Martial and Methods: For molecular classification of earthworm, DNA was extracted from crop and gizzard amplified using a universal primer (forward primer LCO14900 and specific reverse primer (SPE-CO1-A25) for amplification of the mitochondrial cytochrome oxidase subunit I (COX1) gene using touchdown PCR technique. For physiological studies, the contractility of crop and gizzard smooth muscles of earthworm was studied using an organ tissue bath containing ringer solution and recording the contraction isometrically. Also, the effect of different doses of SNP and NE on the contractility of the crop and gizzard was studied.
Results: The outcomes demonstrated that universal primers used for the amplification of 523 bps fragment by using Touch down Polymerase Chain Reaction (TD-PCR) identified the species of the earthworm as Aporrectodea trapezoids. The physiological results showed that different doses of norepinephrine (1*10-8 to 1*10-3 M) significantly reduced the contraction of crop and gizzard smooth muscles of the earthworm. While treatment with different doses of SNP (1*10-6 to 1*10-3 M) showed a non-significant (P >0.05) relaxing effect.