The survey of ectoparasites on two species of Triakids (Mustelus mustelus and M. punctulatus) sharks from Tunisian coasts

Between 2018 and 2020, 696 fish belonging to two species of sharks from the Family Triakidae (Mustelus mustelus and M. punctulatus) were collected from the coasts of Tunisia and inspected for parasites. Six copepod taxa (Perissopus dentatus Steenstrup & Lütken, 1861, Eudactylinella alba Wilson, 1932, Kroyeria lineata Van Beneden, 1853, Nesippus orientalis Heller, 1865 and Lernaeopoda galei Krøyer, 1837, Kroyeria sp.), four isopod species (Anilocra physodes (Linnaeus, 1758), Emetha audouini (H. Milne Edwards, 1840), Ceratothoa parallela (Otto, 1828) and Ceratothoa oestroides (Risso, 1816)) and two monogenean species (Erpocotyle sp1. And Erpocotyle sp2) were collected. A large number of global host records was reported, including the occurrence of E. audouini on M. mustelus and of Erpocotyle sp.2 on M. punctulatus. The study of the diversity of parasites per host species revealed that M. mustelus had a higher parasitic richness compared to M. punctulatus. In this study, it was provided for the first records on ectoparasites on Triakidae sharks from Tunisian coasts and their infection indices.     

Algae as Bio-fertilizers: Between current situation and future prospective

Bio-fertilization is a sustainable agricultural practice that includes using bio-fertilizers to increase soil nutrient content resulting in higher productivity. Soil micro-flora has been exposed to improve soil fertility and increase biomass productivity and identified as a correct environmentally friendly bio-based fertilizer for pollution-free agricultural applies. The majority of cyanobacteria can fix nitrogen from the atmosphere and several species including Anabaena sp., Nostoc sp., and Oscillatoria angustissima is known to be effective cyanobacterial based bio fertilizers. Acutodesmus dimorphus, Spirulina platensis Chlorella vulgaris, Scenedesmus dimorphus, Anabaena azolla, and Nostoc sp. are some of the green microalgae and cyanobacteria species that have been successfully used as bio fertilizers to boost crop growth. Also, Chlorella vulgaris is one of the most commonly used microalgae in bio fertilizer studies. The addition of seaweed species that are Sargassum sp. and Gracilaria verrucosa leads to chemical changes as a soil fertility indicator on clay and sandy soils, and the addition of seaweed conditioner to soil can improve its organic content, return pH to normal, and reduce C/N ratio in both sandy and clay soil. This review provides an effective approach to increase soil fertility via environmentally friendly bio-based fertilizer using micro and macro algae. Instead of the usage of inorganic and organic fertilizers that have polluted impacts to soil as aggregation of heavy metals, in addition to there their human carcinogenic effects.     

Molecular and computational approaches to understand resistance of New Delhi metallo β-lactamase variants (NDM-1, NDM-4, NDM-5, NDM-6, NDM-7)-producing strains against carbapenems

The discovery of NDM-1 and its variants has caused the emergence of antibiotic resistance in the community and hospital setting, causing major concern for health care across the globe. New Delhi Metallo-β-lactamase is known to hydrolyse almost all β-lactam antibiotics. Studies have shown the hydrolytic activates of NDM-1 and some of its variants, however a comparative study of these NDM variants has not been explored in detail. Hence, we proposed to check their catalytic activity by performing a comparative study between NDM-1 and its variants. The study was initiated to clone NDM variants (NDM-1, NDM-4, NDM-5, NDM-6 and NDM-7) followed by overexpression of the recombinant proteins to check their hydrolytic properties against β-lactam antibiotics. The minimum inhibitory concentration of carbapenems antibiotics for bla_NDM-5 clone was found four fold increased, whereas no change was observed in the clones having other variants. The hydrolytic activity of carbapenem with NDM-5 variant was found to be augmented as per the kinetics parameter where Km was decreased and kcat, kcat/Km values increased as compared to the NDM-1. Molecular docking studies were employed to identify the variations in the binding ability among all NDM variants with imipenem or meropenem. Simulation studies at 100?ns showed a good stability of NDM-5 with imipenem and meropenem as compared to NDM-1. CD spectroscopy data revealed significant changes in the secondary structure of NDM variants. We conclude that NDM-5 showed higher hydrolytic activity as compared to other variants. This study provides a comparative analysis of the severity of NDM producing strains.     

Brain Cytochrome Oxidase in Alzheimer''s Disease

A recent demonstration of markedly reduced (-50%) activity of cytochrome oxidase (CO; complex 4), the terminal enzyme of the mitochondrial enzyme transport chain, in platelets of patients with Alzheimer's disease (AD) suggested the possibility of a systemic and etiologically fundamental CO defect in AD. To determine whether a CO deficiency occurs in AD brain, we measured the activity of CO in homogenates of autopsied brain regions of 19 patients with AD and 30 controls matched with respect to age, postmortem time, sex, and, as indices of agonal status, brain pH and lactic acid concentration. Mean CO activity in AD brain was reduced in frontal (-26%: p less than 0.01), temporal (-17%; p less than 0.05), and parietal (-16%; not significant, p = 0.055) cortices. In occipital cortex and putamen, mean CO levels were normal, whereas in hippocampus, CO activity, on average, was nonsignificantly elevated (20%). The reduction of CO activity, which is tightly coupled to neuronal metabolic activity, could be explained by hypofunction of neurons, neuronal or mitochondrial loss, or possibly by a more primary, but region-specific, defect in the enzyme itself. The absence of a CO activity reduction in all of the examined brain areas does not support the notion of a generalized brain CO abnormality. Although the functional significance of a 16-26% cerebral cortical CO deficit in human brain is not known, a deficiency of this key energy-metabolizing enzyme could reduce energy stores and thereby contribute to the brain dysfunction and neurodegenerative processes in AD.     

Cooperativity between integrin activation and mechanical stress leads to integrin clustering

Integrins are transmembrane receptors involved in crucial cellular biological functions such as migration, adhesion, and spreading. Upon the modulation of integrin affinity toward their extracellular ligands by cytoplasmic proteins (inside-out signaling) these receptors bind to their ligands and cluster into nascent adhesions. This clustering results in the increase in the mechanical linkage among the cell and substratum, cytoskeleton rearrangements, and further outside-in signaling. Based on experimental observations of the distribution of focal adhesions in cells attached to micropatterned surfaces, we introduce a physical model relying on experimental numerical constants determined in the literature. In this model, allosteric integrin activation works in synergy with the stress build by adhesion and the membrane rigidity to allow the clustering to nascent adhesions independently of actin but dependent on the integrin diffusion onto adhesive surfaces. The initial clustering could provide a template to the mature adhesive structures. Predictions of our model for the organization of focal adhesions are discussed in comparison with experiments using adhesive protein microarrays.     

Concentations of copper, Zinc, and magnesium in sera from patients with idiopathic dilated cardiomyopathy

Trace elements are known to have a key role in myocardial metabolism. The accumulation (cobalt, arsenic, copper) or deficiency (selenium, zinc) of trace elements may be responsible for idiopathic dilated cardiomyopathy. We investigated the trace element concentrations (Cu, Zn, Mg) in sera from patients with dilated cardiomyopathy by atomic absorption spectrophotometry. We observed that patients with dilated cardiomyopathies have higher copper and lower zinc concentrations in serum than healthy controls. The magnesium concentrations of patients did not differ significantly from that of control subjects.     

Salmonella in wildlife from Trinidad and Grenada, W.I.

Forty-four of 219 animals from Trinidad and Grenada, W.I., yielded 20 serotypes of Salmonella, 16 of which are known to have been associated with human infection in the United States in recent years. Toads (Bufo marinus) provided the greatest number of isolates. Other carriers were mammals, vultures, lizards, a tree-frog and a cave cockroach.     

Neurotoxicity,drugs of abuse,and the CuZn-superoxide dismutase transgenic mice

Administration of methamphetamine (METH) to animals causes loss of DA terminals in the brain. The manner by which METH causes these changes in neurotoxicity is not known. We have tested the effects of this drug in copper/zinc (CuZn)-superoxide dismutase transgenic (SOD Tg) mice, which express the human CuZnSOD gene. In nontransgenic (non-Tg) mice, acute METH administration causes significant decreases in DA and dihydroxyphenylacetic acid (DOPAC) in the striata of non-Tg mice. In contrast, there were no significant decreases in striatal DA in the SOD Tg mice. The effects of METH on DOPAC were also attenuated in SOD Tg mice. Chronic METH administration caused decreases in striatal DA and DOPAC in the non-Tg mice, but not in the SOD-Tg mice. Similar studies were carried out with 1-methyl-1,2,3,6-tetrahydropyridine (MPTP), which also causes striatal DA and DOPAC depletion. As in the case of METH, MPTP causes marked depletion of DA and DOPAC in the non-Tg mice, but not in the SOD Tg mice. These results suggest that the mechanisms of toxicity of both METH and MPTP involve superoxide radical formation.