334 research outputs found
Induction of ovarian maturation by means of dietary hormonal treatment in Austropotamobius pallipes
The freshwater crayfish Austropotamobius pallipes is an annual species with low fecundity and a long embryonic development. Restocking programmes for this species have recently been prompted in many countries in Europe because of its ecological importance in the freshwater ecosystem. The role and interactions of neurotransmitters which intervene in crustacean reproduction have been identified but they are not still completely understood. Ovarian development appears to be under the control of two hormones: the vitellogenesis-inhibiting hormone and the gonad stimulating hormone (Fingermann, 1997)
Time Dynamics of the Down-Coupling Phenomenon in 3-D NAND Strings
We present a detailed analysis of the time
dynamics of the down-coupling phenomenon (DCP) in 3-D
NAND Flash memory strings. The transient time dynamics
of the channel potential following the wordline (WL) bias
transition fromthe pass voltage to zero is studied via numerical
simulation, highlighting the existence of three temporal
regimes controlledby different physical processes: electron
emission from traps, hole injection from the string edges
followed by capture, and propagation along the string. The
impact of these processes is separately studied, followed
by an analysis of the dependence of the DCP recovery time
on architectural parameters. Results highlight the relevant
physics and can be used as a design guideline for NAND
strings with reduced sensitivity to the DCP
Are immune responses gender-related in Carabus lefebvrei (Coleoptera: Carabidae)?
The \u201clive hard, die young\u201d theory predicts the evolution of gender differences in immunocompetence, with males having a weaker immune system than females. To test this hypothesis in Carabus lefebvrei, total and basal phenoloxidase (PO) activities and lysozyme-like enzyme activity were compared among males and females of different reproductive status. The sexual dimorphism occurred only in reproductively active adults and for total and basal PO levels, while no significant differences were recorded between sexes in virgin adults. Differences were not recorded for lytic activity between sexes. Basal PO and lytic activities decreased in both males and females after mating, while the total PO value increased in males and decreased in females. Thus, resources seem to be invested to increase the humoral response in pre-reproductive phase forming a barrier against pathogens and preserving the fecundity and longevity of both sexes. Males preserve their survivorship in reproductive phase by increasing enzymatic levels in hemolymph to avoid fitness reduction due to the increased exposure to pathogen as result of mating. Females shift resources from PO and lytic activity to other physiological systems involved in reproduction in order to maximize their fitness
Gender-related variations in hemolymph parameters of Carabus lefebvrei (Coleoptera: Carabidae): HPLC analysis and phenoloxidase activity
We characterized the enzymatic activity of basal and total phenoloxidase and HLPC and SDS-PAGE profiles in hemolymph of Carabus lefebvrei males and females at different reproductive status. The phenoloxidase activity was activated by trypsin and inhibited by phenoloxidase activity specific inhibitor phenylthiourea. Our results demonstrated that both in males and females, there were no significant differences in the basal phenoloxidase activity between reproductive and virgin beetles, while the total phenoloxidase activity increased significantly in virgin specimens. Thus, resources seem to be invested to increase the humoral response in pre-reproductive phase forming a barrier against pathogens and preserving the fecundity and longevity of both sexes. The hemolymph DOPA-MBTH assay on polyacrilamide gel electrophoresis showed a high activity of monomeric form with an apparent molecular weight of 90 kDa and a dimer of about 170 kDa, also multimeric bands were present in both sexes. In the SDS-PAGE general protein pattern, specific bands were evident for reproductive and virgin males and females as biochemical markers of sexual difference in immunocompetence. Reproducible differences in peaks were recorded in HPLC analysis performed on virgin and reproductive males and females
Ultrasonic spray coating as an approach for large-area polymer OLEDs: The influence of thin film processing and surface roughness on electrical performance
In this article we present a detailed comparison of ultrasonic spray coating and spin coating for the fabrication of polymer organic light-emitting diodes (OLEDs). Single-carrier devices of hole-transporting polymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4’(N-(4-sec-butylphenyl))) diphenylamine] (TFB) were fabricated by ultrasonic spray coating. Uniform reference devices using spin coating were also made. We have shown, across a range of device thicknesses from 37 nm to 138 nm, typical of those used in OLED hole-transport layers, that there is no statistical difference in the hole-injection efficiency between ultrasonic spray coating and spin coating. We have also demonstrated the importance of controlling the roughness of the films and we determine a threshold of 10 nm average roughness below which injection efficiency is not controlled by roughness. However, above 10 nm roughness we find a reduction in injection efficiency up to an 86 % loss in performance for roughnesses of the order of 40 % the thickness of the film. By optimising the deposition parameters, in order to allow the wet films to start to equilibrate, we find a wide processing window for smooth uniform films with excellent injection efficiency. This work reinforces the importance of ultrasonic spray coating as a potential route to high volume manufacturing of OLED based technology
Effects of X-ray irradiation on haemocytes of Procambarus clarkii (Arthropoda: Decapoda) males
The red swamp crayfish Procambarus clarkii is an invasive alien species spreading worldwide. The sterile male release technique (SMRT) is among the methods used to contrast the growth of P. clarkii populations within invaded areas. In this study males underwent X-ray sterilisation with a dose of 40 Gy and their immunocompetence was analysed in comparison to untreated animals to ascertain whether radiation can affect welfare parameters other than reproductive organs. The present research investigated the immune function in P. clarkii males in term of (1) morphological haemocyte characterisation by transmission electron microscopy to identify the main phagocyting haemocyte after in vivo artificial non-self challenge with latex beads; (2) total and differential haemocyte counts; and (3) basal and total phenoloxidase activities as components of the humoral defence. Three types of circulating haemocytes were characterised via transmission electron microscopy: hyaline, semigranular and granular haemocytes. The ultrastructural features of haemocyte granules allowed the characterisation of a fourth type of haemocyte, the medium granule haemocyte. In vivo artificial non-self-challenge with latex beads identified the semigranular haemocytes as primarily involved in phagocyting activity. Circulating haemocytes of males irradiated with a dose of 40 Gy, after 20 days, showed a significantly lower diameter in the granules of hyaline and semigranular haemocytes, but no other evident ultrastructural alterations in comparison with un-irradiated animals were found. Irradiated males showed a significant decrease of about 80% of circulating haemocytes and an increase in frequency of semigranular and granular haemocytes. No significant differences in basal and total phenoloxidase activity were recorded and this could, in part, explain the good survival level of irradiated males despite the drastic decline of the haemocyte number. This study represents the basis to appraise whether SMRT affects important functions, such as those of the immune system, in addition to altering the gonad tissue
Novel Protocol for the Chemical Synthesis of Crustacean Hyperglycemic Hormone Analogues — An Efficient Experimental Tool for Studying Their Functions
The crustacean Hyperglycemic Hormone (cHH) is present in many decapods in different isoforms, whose specific biological functions are still poorly understood. Here we report on the first chemical synthesis of three distinct isoforms of the cHH of Astacus leptodactylus carried out by solid phase peptide synthesis coupled to native chemical ligation. The synthetic 72 amino acid long peptide amides, containing L- or D-Phe3 and (Glp1, D-Phe3) were tested for their biological activity by means of homologous in vivo bioassays. The hyperglycemic activity of the D-isoforms was significantly higher than that of the L-isoform, while the presence of the N-terminal Glp residue had no influence on the peptide activity. The results show that the presence of D-Phe3 modifies the cHH functionality, contributing to the diversification of the hormone pool
The main actors involved in parasitization of Heliothis virescens larva
At the moment of parasitization by another insect, the host Heliothis larva is able to defend itself by the activation of humoral and cellular defenses characterized by unusual reactions of hemocytes in response to external stimuli. Here, we have combined light and electron microscopy, staining reactions, and immunocytochemical characterization to analyze the activation and deactivation of one of the most important immune responses involved in invertebrates defense, i.e., melanin production and deposition. The insect host/parasitoid system is a good model to study these events. The activated granulocytes of the host insect are a major repository of amyloid fibrils forming a lattice in the cell. Subsequently, the exocytosed amyloid lattice constitutes the template for melanin deposition in the hemocel. Furthermore, cross-talk between immune and neuroendocrine systems mediated by hormones, cytokines, and neuromodulators with the activation of stress-sensoring circuits to produce and release molecules such as adrenocorticotropin hormone, alpha melanocyte-stimulating hormone, and neutral endopeptidase occurs. Thus, parasitization promotes massive morphological and physiological modifications in the host insect hemocytes and mimics general stress conditions in which phenomena such as amyloid fibril formation, melanin polymerization, pro-inflammatory cytokine production, and activation of the adrenocorticotropin hormone system occur. These events observed in invertebrates are also reported in the literature for vertebrates, suggesting that this network of mechanisms and responses is maintained throughout evolution
Genome-wide meta-analysis associates HLA-DQA1/DRB1 and LPA and lifestyle factors with human longevity
Genetically predicted cortisol levels and risk of venous thromboembolism
Introduction - In observational studies, venous thromboembolism (VTE) has been associated with Cushing’s syndrome and with persistent mental stress, two conditions associated with higher cortisol levels. However, it remains unknown whether high cortisol levels within the usual range are causally associated with VTE risk. We aimed to assess the association between plasma cortisol levels and VTE risk using Mendelian randomization.
Methods - Three genetic variants in the SERPINA1/SERPINA6 locus (rs12589136, rs11621961 and rs2749527) were used to proxy plasma cortisol. The associations of the cortisol-associated genetic variants with VTE were acquired from the INVENT (28 907 cases and 157 243 non-cases) and FinnGen (6913 cases and 169 986 non-cases) consortia. Corresponding data for VTE subtypes were available from the FinnGen consortium and UK Biobank. Two-sample Mendelian randomization analyses (inverse-variance weighted method) were performed.
Results - Genetic predisposition to higher plasma cortisol levels was associated with a reduced risk of VTE (odds ratio [OR] per one standard deviation increment 0.73, 95% confidence interval [CI] 0.62–0.87, p
Conclusions - This study provides evidence that genetically predicted plasma cortisol levels in the high end of the normal range are associated with a decreased risk of VTE and that this association may be mediated by blood pressure. This study has implications for the planning of observational studies of cortisol and VTE, suggesting that blood pressure traits should be measured and accounted for
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