The anaplerotic pyruvate carboxylase from white shrimp Litopenaeus vannamei: Gene structure, molecular characterization, protein modelling and expression during hypoxia.

Hypoxic zones are spreading worldwide in marine environments affecting many organisms. Shrimp and other marine crustaceans can withstand environmental hypoxia using several strategies, including the regulation of energy producing metabolic pathways. Pyruvate carboxylase (PC) catalyzes the first reaction of gluconeogenesis to produce oxaloacetate from pyruvate. In mammals, PC also participates in lipogenesis, insulin secretion and other processes, but this enzyme has been scarcely studied in marine invertebrates. In this work, we characterized the gene encoding PC in the white shrimp Litopenaeus vannamei, modelled the protein structure and evaluated its gene expression in hepatopancreas during hypoxia, as well as glucose and lactate concentrations. The PC gene codes for a mitochondrial protein and has 21 coding exons and 4 non-coding exons that generate three transcript variants with differences only in the 5'-UTR. Total PC expression is more abundant in hepatopancreas compared to gills or muscle, indicating tissue-specific expression. Under hypoxic conditions of 1.53 mg/L dissolved oxygen, PC expression is maintained in hepatopancreas, indicating its key role even in energy-limited conditions. Finally, both glucose and lactate concentrations were maintained under hypoxia for 24-48 h in hepatopancreas.

Amide Formation: Choosing the Safer Carbodiimide in Combination with OxymaPure to Avoid HCN Release.

It has been reported that DIC can react with OxymaPure to render an oxadiazole compound with the concomitant formation of HCN. Here we demonstrate that this reaction is not a feature of all carbodiimides but rather depends on the alkyl structure that flanks the two N atoms of the carbodiimide. Furthermore, we have identified two carbodiimides, TBEC and EDC·HCl, whose reaction with OxymaPure is exempt from HCN formation.

Tea Bags for Fmoc Solid-Phase Peptide Synthesis: An Example of Circular Economy.

Peptide synthesis is an area with a wide field of application, from biomedicine to nanotechnology, that offers the option of simultaneously synthesizing a large number of sequences for the purpose of preliminary screening, which is a powerful tool. Nevertheless, standard protocols generate large volumes of solvent waste. Here, we present a protocol for the multiple Fmoc solid-phase peptide synthesis in tea bags, where reagent recycling steps are included. Fifty-two peptides with wide amino acid composition and seven to twenty amino acid residues in length were synthesized in less than three weeks. A clustering analysis was performed, grouping the peptides by physicochemical features. Although a relationship between the overall yield and the physicochemical features of the sequences was not established, the process showed good performance despite sequence diversity. The recycling system allowed to reduce N, N-dimethylformamide usage by 25-30% and reduce the deprotection reagent usage by 50%. This protocol has been optimized for the simultaneous synthesis of a large number of peptide sequences. Additionally, a reagent recycling system was included in the procedure, which turns the process into a framework of circular economy, without affecting the quality of the products obtained.

The tea-bag protocol for comparison of Fmoc removal reagents in solid-phase peptide synthesis.

Several factors have influenced the increasing presence of peptides as an important class of Active Pharmaceutical Ingredients. One is the continued development of synthetic methodologies for peptide synthesis. Herein, we investigated the Fmoc removal step, using the tea-bag strategy. In this regard, three different secondary amines: piperidine, 4-methylpiperidine, and piperazine, were evaluated. As a result of this study, 4-methyl piperidine showed to be an excellent alternative to the usually used piperidine in terms of purity and compliance with green chemistry principles as well.

Mitochondrial manganese superoxide dismutase from the shrimp Litopenaeus vannamei: Molecular characterization and effect of high temperature, hypoxia and reoxygenation on expression and enzyme activity.

Climate warming has been increasing ocean water temperature and decreasing oxygen concentrations, exposing aquatic organisms to environmental stress conditions. The shrimp Litopenaeus vannamei manages to survive these harsh environmental conditions by enhancing their antioxidant defenses, among other strategies. In this study, we report the mitochondrial manganese superoxide dismutase (mMnSOD) nucleotide and deduced amino acid sequences and its gene expression in L. vannamei tissues. The deduced protein has 220 amino acids with a signal peptide of 20 amino acids. Expression of mMnSOD was analyzed in hepatopancreas, gills and muscle, where gills had highest expression in normoxic conditions. In addition, shrimp were subjected to high temperature, hypoxia and reoxygenation to analyze the effect on the expression of mMnSOD and SOD activity in mitochondria. High temperature and hypoxia showed a synergistic effect in the up-regulation on expression of mMnSOD in gills and hepatopancreas. Moreover, induction in SOD activity was found in the mitochondrial fraction from gills of normoxia at high temperature, probably due to an overproduction of reactive oxygen species caused by an elevated metabolic rate due to the stress temperature. These results suggest that the combined stress conditions of hypoxia and high temperature trigger molecularly the antioxidant response in L. vannamei in a higher degree than only one stressor.

Chemical Synthesis and Functional Analysis of VarvA Cyclotide.

Cyclotides are circular peptides found in various plant families. A cyclized backbone, together with multiple disulfide bonds, confers the peptides' exceptional stability against protease digestion and thermal denaturation. In addition, the features of these antimicrobial molecules make them suitable for use in animal farming, such as aquaculture. Fmoc solid phase peptide synthesis on 2-chlorotrityl chlorine (CTC) resin using the "tea-bag" approach was conducted to generate the VarvA cyclotide identified previously from Viola arvensis. MALDI-TOF mass spectrometry determined the correct peptide amino acid sequence and the cyclization sites-critical in this multicyclic compound. The cyclotide showed antimicrobial activity against various Gram-negative bacteria, including recurrent pathogens present in Chilean aquaculture. The highest antimicrobial activity was found to be against Flavobacterium psychrophilum. In addition, membrane blebbing on the bacterial surface after exposure to the cyclotide was visualized by SEM microscopy and the Sytox Green permeabilization assay showed the ability to disrupt the bacterial membrane. We postulate that this compound can be proposed for the control of fish farming infections.

Deprotection Reagents in Fmoc Solid Phase Peptide Synthesis: Moving Away from Piperidine?

The deprotection step is crucial in order to secure a good quality product in Fmoc solid phase peptide synthesis. 9-Fluorenylmethoxycarbonyl (Fmoc) removal is achieved by a two-step mechanism reaction favored by the use of cyclic secondary amines; however, the efficiency of the reaction could be affected by side reactions and by-product formation. Several aspects have to be taken into consideration when selecting a deprotection reagent: its physicochemical behavior, basicity (pKa) and polarity, concentration, and time of reaction, toxicity and disposability of residues and, finally, availability of reagents. This report presents a comparison of the performance of three strategies for deprotection using microwave-assisted Fmoc peptide synthesis. Four peptide sequences were synthesized using Rink amide resin with a Liberty Blue™ automated synthesizer and 4-methylpiperidine (4MP), piperidine (PP), and piperazine (PZ) as Fmoc removal reagents. In the first instance all three reagents behaved similarly. A detailed analysis showed a correlation between the hydrophobicity and size of the peptide with the yield and purity of the obtained product. The three reagents are interchangeable, and replacement of piperidine could be advantageous regarding toxicity and reagent handling.

Hepcidin, Cathelicidin-1 and IL-8 as immunological markers of responsiveness in early developmental stages of rainbow trout.

During the early developmental stage of salmonids, high mortality occurs largely as a result of pathogens. These cause low immune competence in fry, producing disease, decreasing production and finally leading to economic losses. Therefore, the aim of this study was to characterise the developmental stages in which rainbow trout acquires immune response capability when challenged with LPS from Pseudomona aeruginosa for 8 h, studying the hepcidin, cathelicidin-1 and IL-8. Total RNA was extracted from fry at 34, 42, 56 and 66 days post hatching (dph). Hepcidin and cathelicidin-1 transcripts were detected only at days 34 and 42, whereas the IL-8 transcript was detected from day 34 to day 66. To analyse the protein expression in the fry, polyclonal anti-peptide antibodies were generated in rabbit. These three immune sera demonstrated the ability to recognise the whole molecule in biological samples. Immunofluorescence showed that skin, gills and intestine mainly responded to the LPS challenge, indicating that these portals of pathogen entry are capturing LPS. This study constitutes a valuable approach, since it has the potential to identify molecules with biological activity that can be used to evaluate the status of fry in culture.

Miocardiopatía peripartum: descripción de un caso clínico / Miocardiopatía peripartum: description of a clinical case

Describe un caso ingresado al Hospital "Luis Vernaza" de la ciudad de Guayaquil, con síntomas clínicos y pruebas complementarias tales como: Ecocardiogramas, EKG y Rx, que demostraban el diagnóstico de la entidad, conocida como Miocardiopatía peripartum. El propósito de este artículo es hacer una revisión del cuadro clínico y de la terapéutica, ya que es una patología poco frecuente.