Teleost Nonapeptides, Isotocin and Vasotocin Administration Released the Milt by Abdominal Massage in Male Catfish, Clarias magur

Abstract

In the present work the nonapeptides i.e., isotocin and vasotocin alone or in a combination were tested in C. magur to evaluate their effect on stripping by abdominal massage. Also, we used chitosan-carbon nanotube nanocomposites to conjugate the nonapetides isotocin (abbreviated as COOH-SWCNTCSPeP) and isotocin and vasotocin (COOH-SWCNTCSPePs) with the aim of sustaining the effect for a longer duration. The conjugation of nonapeptides with nanocomposites was confirmed by Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Two experiments were conducted to study the effect of naked (without nanoparticles) and conjugated nonapeptides on the milt release by stripping. Both the experiments consisted of eight treatments which included four naked groups two nanoconjugated groups and two controls. Both naked and nonconjugated formulations were successful in stripping the male catfish. The mRNA expression of selected reproductive genes was analysed to decipher the effect of nanopeptides at the molecular level. Nonapeptide treatment either naked or nanoconjugated, resulted in the upregulation of the transcript level of genes. Histological analysis revealed the concentration of spermatozoa was more in peptide injected groups than in the controls. The synergistic effects of nonapeptides and Ovatide had a positive impact on GSI. Thus, the present formulations were successful in stripping the male catfish to obtain the milt with significant reproductive success. Even though the naked groups perform better but the number of males required to fertilize the eggs in nanoconjuagted groups was smaller making it worth using for the delivery of nonapeptides.

Keywords: catfish; milt; nanoparticles; nanotube; stripping.

Figure 1

FTIR of CS (chitosan), COOH-SWCNT (single-walled carbon nanotubes), COOH-SWCNTCS (single-walled carbon nanotubes with chitosan), COOH-SWCNTCSPePs (Chitosan-carbon nanotubes with nonapeptides).

Figure 2

SEM results of (A) COOH-SWCNTs (single-walled carbon nanotubes) and (B) COOH-SWCNTCSPEPs (Chitosan-carbon nanotubes with nonapeptides).

Figure 3

TEM results of (A) COOH-SWCNT (single-walled carbon nanotubes) and (B) COOH-SWCNTCSPePs (single-walled carbon nanotubes with nonapeptides).

Figure 4

XPS results of COOH-SWCNTCSPePs (single-walled carbon nanotubes with chitosan and nonapeptides).

Figure 5

TGA results of CS (chitosan), COOH-SWCNT (single-walled carbon nanotubes), COOH-SWCNTCS (single-walled carbon nanotubes with chitosan), COOH-SWCNTCSPePs (Chitosan-carbon nanotubes with nonapeptides).

Figure 6

Histological results in different treatments. Here, [N] Negative control and [P] Positive control 4-Spermatids, 5-Spermatozoa, (A–F) are treatments. The photographs were taken at a magnification of 40x.

Figure 7

Histological results in different treatments. Here, 4-Spermatids, 5-Spermatozoa, (A–F) are treatments. The photographs were taken at a magnification of 40x.

Figure 8

mRNA expression levels of different reproductive genes in testes collected at different time points in different treatment groups. The different letters used indicates significant differences and superscripts indicate non-significant differences in mRNA expression level. Data were expressed as mean ± S.E.M.

Figure 9

Hormonal levels in blood serum collected at different time points in a different group of treatments. The different letters used indicates significant differences and superscripts indicate the non-significant difference in hormonal levels. Data were expressed as mean ± S.E.M.