THE EFFECT OF INSULIN ON GLUCOSE UPTAKE AND GLYCOGEN SYNTHESIS IN THE LIVER FLUKE FASCIOLA HEPATICA L

Author(s):  
L. SEKARDI
2021 ◽  
Vol 120 (3) ◽  
pp. 979-991
Author(s):  
Rebekah B. Stuart ◽  
Suzanne Zwaanswijk ◽  
Neil D. MacKintosh ◽  
Boontarikaan Witikornkul ◽  
Peter M. Brophy ◽  
...  

AbstractFasciola hepatica (liver fluke), a significant threat to food security, causes global economic loss for the livestock industry and is re-emerging as a foodborne disease of humans. In the absence of vaccines, treatment control is by anthelmintics; with only triclabendazole (TCBZ) currently effective against all stages of F. hepatica in livestock and humans. There is widespread resistance to TCBZ and its detoxification by flukes might contribute to the mechanism. However, there is limited phase I capacity in adult parasitic helminths with the phase II detoxification system dominated by the soluble glutathione transferase (GST) superfamily. Previous proteomic studies have demonstrated that the levels of Mu class GST from pooled F. hepatica parasites respond under TCBZ-sulphoxide (TCBZ-SO) challenge during in vitro culture ex-host. We have extended this finding by exploiting a sub-proteomic lead strategy to measure the change in the total soluble GST profile (GST-ome) of individual TCBZ-susceptible F. hepatica on TCBZ-SO-exposure in vitro culture. TCBZ-SO exposure demonstrated differential abundance of FhGST-Mu29 and FhGST-Mu26 following affinity purification using both GSH and S-hexyl GSH affinity. Furthermore, a low or weak affinity matrix interacting Mu class GST (FhGST-Mu5) has been identified and recombinantly expressed and represents a new low-affinity Mu class GST. Low-affinity GST isoforms within the GST-ome was not restricted to FhGST-Mu5 with a second likely low-affinity sigma class GST (FhGST-S2) uncovered. This study represents the most complete Fasciola GST-ome generated to date and has supported the potential of subproteomic analyses on individual adult flukes.


2021 ◽  
Vol 293 ◽  
pp. 109427
Author(s):  
Jane Lamb ◽  
Emma Doyle ◽  
Jamie Barwick ◽  
Michael Chambers ◽  
Lewis Kahn

Nature ◽  
1963 ◽  
Vol 198 (4876) ◽  
pp. 204-204 ◽  
Author(s):  
D. TEODOROVIĆ ◽  
I. BERKEŠ ◽  
M. MILOVANAVIĆ

Parasitology ◽  
1990 ◽  
Vol 101 (3) ◽  
pp. 395-407 ◽  
Author(s):  
A. W. Stitt ◽  
I. Fairweather

SUMMARYSpermatogenesis and the fine structure of the mature spermatozoon of Fasciola hepatica have been studied by transmission electron microscopy. The primary spermatogonia display a typical gonial morphology and occupy the periphery of the testis. They undergo 3 mitotic divisions to give rise to 8 primary spermatocytes forming a rosette of cells connected to a central cytophore. The primary spermatocytes undergo 2 meiotic divisions, resulting in 32 spermatids that develop into spermatozoa. Intranuclear synaptonemal complexes in primary spermatocytes confirm the first meiotic division. The onset of spermiogenesis is marked by the formation of the zone of differentiation which contains 2 basal bodies and a further centriole derivative, the central body. The zone extends away from the spermatid cell to form the median process; into this migrates the differentiated and elongate nucleus. Simultaneously, 2 axonemes develop from the basal bodies. During development, they rotate through 90° to extend parallel to the median process. The migration of the nucleus to the distal end of the median process coincides with the fusion of the axonemes to the latter to form a monopartite spermatozoon. The mature spermatozoon possesses 2 axonemes of the 9 + ‘1’ pattern typical of parasitic platyhelminths, 2 elongate mitochondria and a variable array of peripheral microtubules. The nuclear region of the spermatozoon is immotile. The value of sperm ultrastructure as a taxonomic tool in platyhelminth phylogeny is discussed.


2008 ◽  
Vol 294 (1) ◽  
pp. E28-E35 ◽  
Author(s):  
Michale Bouskila ◽  
Michael F. Hirshman ◽  
Jørgen Jensen ◽  
Laurie J. Goodyear ◽  
Kei Sakamoto

Insulin promotes dephosphorylation and activation of glycogen synthase (GS) by inactivating glycogen synthase kinase (GSK) 3 through phosphorylation. Insulin also promotes glucose uptake and glucose 6-phosphate (G-6- P) production, which allosterically activates GS. The relative importance of these two regulatory mechanisms in the activation of GS in vivo is unknown. The aim of this study was to investigate if dephosphorylation of GS mediated via GSK3 is required for normal glycogen synthesis in skeletal muscle with insulin. We employed GSK3 knockin mice in which wild-type GSK3α and -β genes are replaced with mutant forms (GSK3α/βS21A/S21A/S9A/S9A), which are nonresponsive to insulin. Although insulin failed to promote dephosphorylation and activation of GS in GSK3α/βS21A/S21A/S9A/S9Amice, glycogen content in different muscles from these mice was similar compared with wild-type mice. Basal and epinephrine-stimulated activity of muscle glycogen phosphorylase was comparable between wild-type and GSK3 knockin mice. Incubation of isolated soleus muscle in Krebs buffer containing 5.5 mM glucose in the presence or absence of insulin revealed that the levels of G-6- P, the rate of [14C]glucose incorporation into glycogen, and an increase in total glycogen content were similar between wild-type and GSK3 knockin mice. Injection of glucose containing 2-deoxy-[3H]glucose and [14C]glucose also resulted in similar rates of muscle glucose uptake and glycogen synthesis in vivo between wild-type and GSK3 knockin mice. These results suggest that insulin-mediated inhibition of GSK3 is not a rate-limiting step in muscle glycogen synthesis in mice. This suggests that allosteric regulation of GS by G-6- P may play a key role in insulin-stimulated muscle glycogen synthesis in vivo.


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