Lipid transporters and receptor in salmon louse (Lepeophtheirus salmonis) : Effect of RNAi Knockdown on oogenesis, embryonal development and larval maturation

The salmon louse, Lepeophtheirus salmonis, is a marine ectoparasite of salmonids in the Northern Hemisphere. At present, salmon louse infestation is considered as one of the biggest challenges in the salmon farming industry, causing huge economic losses, and also considered a threat to wild populations of salmonids. Control of salmon lice on farmed salmon has mainly depended on the use of chemotherapeutants. However, over the past few years, the salmon louse has developed resistance against most available chemicals. As a consequence, non-chemical treatment methods such as cleaner fish have been introduced in salmon farming, but the production, health and welfare in the cleaner fish have been challenging. It is, therefore, evident that new treatment methods are needed to control this parasite. For this purpose, further understanding of the biology of this parasite is crucial to identify new principles or drug targets. Lipids are an important source of energy for the growth and reproduction of animals. Other functions include their role in cellular signalling and as structural components in the cell membranes. In oviparous animals, females deposit lipids to maturing eggs to be utilized during embryogenesis and larval development. Transport of lipids through the circulation of animals to developing oocytes is facilitated by lipoproteins, which consist of lipids and protein components known as apolipoproteins. Lipoproteins carry lipids from the site of synthesis or storage to the site of utilization/storage while lipoprotein receptors facilitate uptake of lipoproteins. Previous studies in vertebrates and some insects showed that maturation of these lipoproteins is under the control of another protein known as microsomal triglyceride transfer protein (MTP). Female salmon lice produce large numbers of lipid-enriched eggs throughout its life span. Similar to other oviparous animals, female louse accumulates a large amount of lipids in developing eggs during vitellogenesis. In female salmon lice, transport of maternal lipids to growing oocytes of female lice has not been addressed before. Presence of genes encoding MTP, apolipoproteins (apoLps) and lipophorin receptor (LpR) may suggest a similar mechanism of lipid metabolism/transport as found in other organisms. Lipoproteins require for extracellular transport of lipids to different tissues of animals and assembly, as well as secretion of these lipoproteins depend upon MTP. In oviparous species, female supply enough lipids to oocytes to secure successful embryogenesis and early larval development. It is likely that female salmon lice use similar lipoprotein based mechanism to supply maternal lipids to growing oocytes. Therefore it is important to study the role of MTP in the supply of lipids to growing oocytes. Three transcript variants of MTP were found in the salmon louse and all variants transcribed differently in different tissues of an adult female. Functional studies conducted through RNAi induced transcript knock down confirmed that female lice produce offspring with very low lipid contents and survival rate of 10-30% compare to control group animals. The present study suggests that MTP has an important function in reproduction and lipid metabolism in salmon louse and may be considered in the development of a new anti-parasitic treatment method. Protein components of lipoproteins, apoLPs, are essential in the transport of lipids to different tissues of animals through their interaction with cell surface lipoprotein receptors. Similar to other oviparous animals, it is possible that female salmon louse use lipoproteins for the transport of maternal lipids to growing oocytes where apoLps of lipoproteins bind with lipoprotein receptors and release lipids to the oocytes. In salmon lice, two apoLps encoding genes (LsLp1 and LsLp2) were identified. Expression of both genes was found in the intestine and sub-cuticular tissue of adult female louse. RNAi mediated-knockdown of both genes in female louse confirmed significant reduction of transcripts levels. Female lice injected with LsLp1 double-stranded RNA produced short egg-strings as well as significantly fewer offspring compared to control lice. Knockdown of LsLp2 did not show any effect on the eggstring production and numbers of offspring compared with control lice. Functional studies were conducted through RNAi suggested that LsLp1 play an important role in reproduction of female lice. Previous studies in different organisms show that members of low-density lipoprotein receptor (LDLR) superfamily mediate the endocytosis of lipoproteins. In salmon louse genome database, single gene homologous to insect lipophorin receptor was identified and named as L. salmonis lipophorin receptor (LsLpR). The LsLpR consists of 16 exons and encodes a protein of 952 amino acids. Structural analysis showed that the predicted structure of LsLpR contains five functional domains similar to LpR of insects. Phylogenetic analysis placed LsLpR together with LpR of insects. The highest abundance of LsLR transcripts was found in copepodids and adult females. In adult females, receptor transcripts and proteins were found in the ovary and vitellogenic oocytes. While in larvae, the LsLpR transcripts were found in the neuronal somata of the brain and in the intestine. Possible functions of LsLpR in reproduction and lipid metabolism were investigated through RNA interference. Knockdown in larvae decreased the transcription of LsLpR by 44-54%, and knockdown of LsLpR in adult female lice reduced the number of offspring by 72% compared with control lice.Doktorgradsavhandlin

An unsuspected bleeding Meckel\u27s diverticulum in an adult detected on mesenteric angiography

Meckel\u27s diverticulum is usually asymptomatic and found in almost 2% of the population. Haemorrhage from a Meckel\u27s diverticulum is common in children but rare in adults. Here we report a case of 20 years old male with recurrent gastrointestinal bleeding. Meckel\u27s diverticulum was diagnosed due to abnormal vascularity on mesenteric angiography and embolization was performed. Diagnosis was correlated with other radiological imaging and later elective resection was performed. This case is reported to emphasize the potential role of mesenteric angiography in the detection and management of bleeding Meckel\u27s diverticulum and correlation with other radiological imaging

Microsomal triglyceride transfer protein in the ectoparasitic crustacean salmon louse (Lepeophtheirus salmonis)

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Two apolipoproteins in salmon louse (Lepeophtheirus salmonis), apolipoprotein 1 knock down reduces reproductive capacity

The salmon louse, Lepeophtheirus salmonis is an ectoparasite of salmonid fish in the Northern Hemisphere, causing large economical losses in the aquaculture industry and represent a threat to wild populations of salmonids. Like other oviparous animals, it is likely that female lice use lipoproteins for lipid transport to maturing oocytes and other organs of the body. As an important component of lipoproteins, apolipoproteins play a vital role in the transport of lipids through biosynthesis of lipoproteins. Apolipoproteins have been studied in detail in different organisms, but no studies have been done in salmon lice. Two apolipoprotein encoding genes (LsLp1 and LsLp2) were identified in the salmon lice genome. Transcriptional analysis revealed both genes to be expressed at all stages from larvae to adult with some variation, LsLp1 generally higher than LsLp2 and both at their highest levels in adult stages of the louse. In adult female louse, the LsLp1 and LsLp2 transcripts were found in the sub-epidermal tissue and the intestine. RNA interference-mediated knockdown of LsLp1 and LsLp2 in female lice resulted in reduced expression of both transcripts. LsLp1 knockdown female lice produced significantly less offspring than control lice, while knockdown of LsLp2 in female lice caused no reduction in the number of offspring. These results suggest that LsLp1 has an important role in reproduction in female salmon lice.publishedVersio

Sustainable growth rate, corporate value of US firms within capital and labor market distortions: The moderating effect of institutional quality

Research background: Understanding how distortions in capital and labor markets affect corporate value and sustainable growth is crucial in today's economy. These distortions can disrupt resource allocation and economic sustainability. Additionally, the role of institutional quality in shaping these dynamics requires thorough exploration.Purpose of the article: We quantify the effect of capital and labor market distortions on corporate value and sustainable growth rate (SGR) and how this association is moderated by institutional quality.Methods: Stemming from the sample criteria, we calibrated a final sample of 1971 United States-listed manufacturing firms for 2012–2022. This research offers insights into market inefficiencies and institutional effects. Progressing towards objectives, we use advanced techniques like feasible generalized least squares and generalized methods of moments. These methods help us rigorously analyze complex relationships among study variables.Findings & value added: Three key findings emerge: first, capital and labor market distortions have a negative and significant influence on corporate value and sustainable growth. Our primary finding implies that increasing distortions significantly reduce sustainable growth's value and potential. Second, we find institutional quality has a positive significant effect on corporate value and sustainable growth. Third, institutional quality positively moderates the association between capital and labor market distortions, corporate value, and sustainable growth. Findings suggest that institutional quality, as a potential mechanism, improves the efficiency of resource allocation and optimizes the sustainable economic system to lessen the negative effect of factor market distortions on corporate value and SGR. Besides, we conduct robustness checks to validate our findings. Finally, we offer policymakers and stakeholders actionable insights

Firm climate change risk and financial flexibility: Drivers of ESG performance and firm value

This study investigates how a firm's climate change risk (FCCR) and financial flexibility (FIFL) affect its value and environmental, social, and governance (ESG) performance. We use data from publicly listed US firms for 2012–2021. We employed four estimation methods: bootstrap quantile regression, feasible generalised least squares, a generalised method of moments, and fixed effects with Driscoll-Kraay standard errors. Our main findings indicate that climate change risk has a negative effect on firm value and a positive effect on ESG performance and that financial flexibility moderates these effects by reducing risk and enhancing value. These results are robust against alternative measures and estimation techniques. Our study provides novel insights into the influence of climate risk and financial flexibility on firm value and ESG performance. We also discuss the implications of our results for academics, practitioners, and policymaker

Prognostically Significant Fusion Oncogenes and Gene Mutations in Pakistani AML Patients

Background: The onset and progression of leukemia is associated with many genetic abnormalities including gene mutations and production of fusion oncogenes. Molecular studies on fusion oncogenes and mutations in different populations have been done. However, not much research on correlation of the fusion oncogenes with acute myeloid leukemia have been done in Pakistan.Methods: Genetic analysis of 105 AML patients was done to investigate AML1-ETOand CBFB-MYH11 fusion oncogenes and mutations in NPM1 and NRAS genes. The genomic DNA and cDNA were subjected to amplification, electrophoresis, and Sanger sequencing.Results: The frequency of AML1-ETO was 26% in AML patients and 34.2% in AML-M2 patients. CBFB-MYH11 was present in 11.4% AML patients. A total of six mutations in 4 regions of NPM1 gene and 2 regions of NRAS gene were detected. 3’UTR of NPMI gene had three variants; g.1128C>T (57.1%), g.1185-/T insertion (80.95%), and g.1163A>T (57.14%) while c.867_871subGTGGA >CAAGTTTGC (2.86%) was present in exon 12. NRAS gene had two mutations c.12C>T (51.4%) and c.33A>T (11.43%) in exon 2. c.867_871subGTGGA >CAAGTTTGC , and g.1163A>T in NPM1 gene and c.33A>T in NRAS gene were the novel findings in this ethnic population.Conclusion: This genetic analysis may help to modulate the treatment strategies and improve survival of patients.Keywords: Acute Myeloid Leukemia; Fusion Oncogenes; AML; AML1-ETO; CBFB-MYH11; AML-M2; Nucleophosmin, NPM1; NRAS