Low sensitiveness of taxonomic distinctness indices to human impacts: Evidences across marine benthic organisms and habitat types

Ecological indicators likely constitute the mainstream tools in assessing the quality of aquatic ecosystems as they condense composite biological information into single measures, easier to handle for environmental managers and more understandable for non-scientific users. However, sampling settings can influence the performance of most indices, and their use is often constrained to specific habitat types. Average taxonomic distinctness (Δ⁺) and variation in taxonomic distinctness (Λ⁺) may represent promising tools in overcoming sampling bias, and potentially applicable to a wide range of environmental contexts. In marine systems, such metrics showed higher sensitivity than classical indices in discriminating among perturbed and unperturbed conditions, though a number of studies found Δ⁺ and Λ⁺ also varying along natural gradients, suggesting a lower ability to discern human-driven variations from natural variability than what expected. Here, analyzing existing data sets from previous impact assessment studies, we test the response of Δ⁺ and Λ⁺ in detecting the effects of different sources of anthropogenic disturbance on marine mollusks and polychaetes from Mediterranean soft sediments and hard substrates. Our results showed that neither classical univariate analyses on Δ⁺ and Λ⁺ values nor their associated statistical framework were able to discern among perturbed and unperturbed sites, highlighting a low sensitiveness of such metrics in detecting assemblage variations related to anthropogenic disturbance. Δ⁺ and Λ⁺ are based on presence/absence data, and assume impacts being likely to induce variations in taxonomic structures of assemblages. As a consequence, they could experience reduced discrimination power when impacts mostly affect relative abundances of organisms rather than assemblage composition, or drive species replacement within higher taxa. Our results also showed that habitat type could strongly affect taxonomic relatedness of species within assemblages, and that this effect can vary among different organisms, suggesting that the departures from expectation of Δ⁺ and Λ⁺ values might not be always univocally attributable to human perturbations, since possibly depending on habitat effects. Taxonomic distinctness indices can provide useful additional information on taxonomic diversity of assemblages, crucial to better address the wide concept of biological diversity. However, the effectiveness of such measures in disclosing the effects of human disturbance is still unclear, requiring further investigations especially on their potential application in defining the ecological status of coastal rocky systems.     

Gastric bypass does not normalize obesity‐related changes in ghrelin profile and leads to higher acylated ghrelin fraction

Objective:

Gastric bypass (GBP) lowers food intake, body weight, and insulin resistance in severe obesity (SO). Ghrelin is a gastric orexigenic and adipogenic hormone contributing to modulate energy balance and insulin action. Total plasma ghrelin (T‐Ghr) level is low and inversely related to body weight and insulin resistance in moderately obese patients, but these observations may not extend to the orexigenic acylated form (A‐Ghr) whose plasma concentration increase in moderate obesity.

Design and Methods:

We investigated the impact of GBP on plasma T‐, A‐, and A/T‐Ghr in SO patients (n = 28, 20 women), with measurements at baseline and 1, 3, 6, and 12 months after surgery. Additional cross‐sectional comparison was performed between nonobese, moderately obese, and SO individuals before GBP and at the end of the follow‐up period.

Results:

Before GBP, SO had lowest T‐Ghr and highest A/T‐Ghr profile compared with both nonobese and moderately obese individuals. Lack of early (0‐3 months from GBP) T‐Ghr changes masked a sharp increase in A‐Ghr and A/T‐Ghr profile (P < 0.05) that remained elevated following later increments (6‐12 months) of both T‐ and A‐Ghr (P < 0.05). Levels of A‐Ghr and A/T‐Ghr at 12 months of follow‐up remained higher than in matched moderately obese individuals not treated with surgery (P < 0.05).

Conclusions:

The data show that following GBP, early T‐Ghr stability masks elevation of A/T‐Ghr, that is stabilized after later increments of both T‐ and A‐hormones. GBP does not normalize the obesity‐associated elevated A/T‐Ghr ratio, instead resulting in enhanced A‐Ghr excess. Excess A‐Ghr is unlikely to contribute to, and might limit, the common GBP‐induced declines of appetite, body weight, and insulin resistance.     

Morphological and Metabolic Changes in the Nigro-Striatal Pathway of Synthetic Proteasome Inhibitor (PSI)-Treated Rats: A MRI and MRS Study

Systemic administration of a Synthetic Proteasome Inihibitor (PSI) in rats has been described as able to provide a model of Parkinson’s disease (PD), characterized by behavioral and biochemical modifications, including loss of dopaminergic neurons in the substantia nigra (SN), as assessed by post-mortem studies. With the present study we aimed to assess in-vivo by Magnetic Resonance (MR) possible morphological and metabolic changes in the nigro-striatal pathway of PSI-treated rats. 10 animals were subcutaneously injected with PSI 6.0 mg/kg dissolved in DMSO 100%. Injections were made thrice weekly over the course of two weeks. 5 more animals injected with DMSO 100% with the same protocol served as controls. The animals underwent MR sessions before and at four weeks after the end of treatment with either PSI or vehicle. MR Imaging was performed to measure SN volume and Proton MR Spectroscopy (¹H-MRS) was performed to measure metabolites changes at the striatum. Animals were also assessed for motor function at baseline and at 4 and 6 weeks after treatment. Dopamine and dopamine metabolite levels were measured in the striata at 6 weeks after treatment. PSI-treated animals showed volumetric reduction of the SN (p<0.02) at 4 weeks after treatment as compared to baseline. Immunofluorescence analysis confirmed MRI changes in SN showing a reduction of tyrosine hydroxylase expression as compared to neuron-specific enolase expression. A reduction of N-acetyl-aspartate/total creatine ratio (p = 0.05) and an increase of glutamate-glutamine-γ amminobutirrate/total creatine were found at spectroscopy (p = 0.03). At 6 weeks after treatment, PSI-treated rats also showed motor dysfunction compared to baseline (p = 0.02), accompanied by dopamine level reduction in the striatum (p = 0.02). Treatment with PSI produced morphological and metabolic modifications of the nigro-striatal pathway, accompanied by motor dysfunction. MR demonstrated to be a powerful mean to assess in-vivo the nigro-striatal pathway morphology and metabolism in the PSI-based PD animal model.     

Identification and Functional Characterization of Three NoLS (Nucleolar Localisation Signals) Mutations of the CDC73 Gene

Hyperparathyroidism Jaw-Tumour Syndrome (HPT-JT) is characterized by primary hyperparathyroidism (PHPT), maxillary/mandible ossifying fibromas and by parathyroid carcinoma in 15% of cases. Inactivating mutations of the tumour suppressor CDC73/HRPT2 gene have been found in HPT-JT patients and also as genetic determinants of sporadic parathyroid carcinoma/atypical adenomas and, rarely, typical adenomas, in familial PHPT. Here we report the genetic and molecular analysis of the CDC73/HRPT2 gene in three patients affected by PHPT due to atypical and typical parathyroid adenomas, in one case belonging to familial PHPT. Flag-tagged WT and mutant CDC73/HRPT2 proteins were transiently transfected in HEK293 cells and functional assays were performed in order to investigate the effect of the variants on the whole protein expression, nuclear localization and cell overgrowth induction. We identified four CDC73/HRPT2 gene mutations, three germline (c.679_680delAG, p.Val85_Val86del and p.Glu81_Pro84del), one somatic (p.Arg77Pro). In three cases the mutation was located within the Nucleolar Localisation Signals (NoLS). The three NoLS variants led to instability either of the corresponding mutated protein or mRNA or both. When transfected in HEK293 cells, NoLS mutated proteins mislocalized with a predeliction for cytoplasmic or nucleo-cytoplasmic localization and, finally, they resulted in overgrowth, consistent with a dominant negative interfering effect in the presence of the endogenous protein.     

Neurogenic potential of mesenchymal-like stem cells from human amniotic fluid: the influence of extracellular growth factors

Amniotic fluids contain human stem cells, among which mesenchymal stem cells could be isolated. These cells have multipotent differentiation ability and no tumorigenic potential after transplantation in mice. These features make them good candidates for in vitro studies and for therapeutic purposes. The aim of this study was to isolate mesenchymal stem cell-like cultures from different amniotic fluids in order to study in vitro their neurogenic potential and assess if this process could be reproducible and standardized. We focused attention on the possible differential effects of soluble growth factors. Immunophenotypical and molecular characterization showed that the 31 amniotic fluid-derived cultures expressed mesenchymal markers as well as some stemness properties. These cells also appeared to be responsive to purines or acetylcholine showing an intracellular calcium increase, also reported for mesenchymal stem cells derived from other sources. Interestingly, in the presence of retinoic acid, these cells assumed a neuronal-like morphology. In addition, functional and molecular analyses revealed that retinoic acid-treated cells showed immature electric functional properties, the expression of neuronal markers and stemness genes. In conclusion, even if further investigations are required, the results presented here contribute to support the finding that amniotic fluid contains cells able to differentiate in vitro towards neural-like lineage in the presence of retinoic acid. The ability of retinoic acid to induce a possible neuronal progenitor culture makes the model useful to study a possible in vivo transplantation of these cells and to contribute to define the protocols for cell therapy.     

arouser reveals a role for synapse number in the regulation of ethanol sensitivity

A reduced sensitivity to the sedating effects of alcohol is a characteristic associated with alcohol use disorders (AUDs). A genetic screen for ethanol sedation mutants in Drosophila identified arouser (aru), which functions in developing neurons to reduce ethanol sensitivity. Genetic evidence suggests that aru regulates ethanol sensitivity through its activation by Egfr/Erk signaling and its inhibition by PI3K/Akt signaling. The aru mutant also has an increased number of synaptic terminals in the larva and adult fly. Both the increased ethanol sensitivity and synapse number of the aru mutant are restored upon adult social isolation, suggesting a causal relationship between synapse number and ethanol sensitivity. We thus show that a developmental abnormality affecting synapse number and ethanol sensitivity is not permanent and can be reversed by manipulating the environment of the adult fly.     

Specific Association of Growth-associated Protein 43 with Calcium Release Units in Skeletal Muscles of Lower Vertebrates

Growth-associated protein 43 (GAP43), is a strictly conserved protein among vertebrates implicated in neuronal development and neurite branching. Since GAP43 structure contains a calmodulin-binding domain, this protein is able to bind calmodulin and gather it nearby membrane network, thus regulating cytosolic calcium and consequently calcium-dependent intracellular events. Even if for many years GAP43 has been considered a neuronal-specific protein, evidence from different laboratories described its presence in myoblasts, myotubes and adult skeletal muscle fibers. Data from our laboratory showed that GAP43 is localized between calcium release units (CRUs) and mitochondria in mammalian skeletal muscle suggesting that, also in skeletal muscle, this protein can be a key player in calcium/calmodulin homeostasis. However, the previous studies could not clearly distinguish between a mitochondrion- or a triad-related positioning of GAP43. To solve this question, the expression and localization of GAP43 was studied in skeletal muscle of Xenopus and Zebrafish known to have triads located at the level of the Z-lines and mitochondria not closely associated with them. Western blotting and immunostaining experiments revealed the expression of GAP43 also in skeletal muscle of lower vertebrates (like amphibians and fishes), and that the protein is localized closely to the triad junction. Once more, these results and GAP43 structural features, support an involvement of the protein in the dynamic intracellular Ca²⁺ homeostasis, a common conserved role among the different species.Key words: GAP43, RyR, skeletal muscle, Xenopus, Zebrafish