Digestive Alkaline Proteases from Zosterisessor ophiocephalus, Raja clavata, and Scorpaena scrofa: Characteristics and Application in Chitin Extraction

The aim of this work was to study some biochemical characteristics of crude alkaline protease extracts from the viscera of goby (Zosterisessor ophiocephalus), thornback ray (Raja clavata), and scorpionfish (Scorpaena scrofa), and to investigate their applications in the deproteinization of shrimp wastes. At least four caseinolytic proteases bands were observed in zymogram of each enzyme preparation. The optimum pH for enzymatic extracts activities of Z. ophiocephalus, R. clavata, and S. scrofa were 8.0-9.0, 8.0, and 10.0, respectively. Interestingly, all the enzyme preparations were highly stable over a wide range of pH from 6.0 to 11.0. The optimum temperatures for enzyme activity were 50°C for Z. ophiocephalus and R. clavata and 55°C for S. scrofa crude alkaline proteases. Proteolytic enzymes showed high stability towards non-ionic surfactants (5% Tween 20, Tween 80, and Triton X-100). In addition, crude proteases of S. scrofa, R. clavata, and Z. ophiocephalus were found to be highly stable towards oxidizing agents, retaining 100%, 70%, and 66%, respectively, of their initial activity after incubation for 1 h in the presence of 1% sodium perborate. They were, however, highly affected by the anionic surfactant SDS. The crude alkaline proteases were tested for the deproteinization of shrimp waste in the preparation of chitin. All proteases were found to be effective in the deproteinization of shrimp waste. The protein removals after 3 h of hydrolysis at 45°C with an enzyme/substrate ratio (E/S) of 10 were about 76%, 76%, and 80%, for Z. ophiocephalus, R. clavata, and S. scrofa crude proteases, respectively. These results suggest that enzymatic deproteinization of shrimp wastes by fish endogenous alkaline proteases could be applicable to the chitin production process

ESG Disclosure and the Cost of Capital: Is There a Ratcheting Effect over Time?

In recent years, the CSR disclosure–firm risk relationship has raised the acute interest of capital providers, regulators, debtholders, and academic researchers. In addition to the mounting corporate social responsibility (CSR) disclosure issues, one particular area that has increasingly attracted the attention of academics, practitioners, and policymakers is the dynamic of CSR disclosure. The effects of institutional pressures and the relative nature of reputation have amplified expectations over time, resulting in a dynamic CSR disclosure strategy to meet those expectations. However, studies on the relationship between CSR disclosure and firm risk over time are still in their premature stages. Thus, this paper seeks to contribute to the literature on firm risk and CSR disclosure by examining the effect of ESG disclosure on the cost of capital over time. The study examines a sample of 430 S&P 500 US firms observed over the 2011 to 2019 period. Our results indicate that the three dimensions do not have the same effect. Governance disclosure decreases the cost of capital during the first years, and in later years, the effect becomes positive. Over time, social disclosure increases the cost of capital. However, environmental disclosure shows a negative and significant effect on the cost of capital during the first years but no significant effect later in time. Our results contribute to explaining the dynamic effect of CSR disclosure. A predominant feature to consider is the evolution of CSR disclosure over time. Steadily, US firms are moving away from some CSR disclosure activities to others. However, firms that abandoned some existing CSR disclosure commitments may face aggressive responses from stakeholders. US firms have to be more cautious when linking CSR disclosure to firm risk over time, recognizing the long-term benefits and drawbacks of CSR disclosure

A new approach of action recognition based on Motion Stable Shape (MSS) features

International audienceAction recognition is actually considered as one of the most challenging areas in computer vision domain. In this paper, we propose a new approach based on utilization of motion boundaries to generate Motion Stable Shape (MSS) features to describe human actions in videos. In fact, we have considered actions as a set of human poses. Temporal evolution of each human pose is modeled by a set of new MSS feature's. Motion stable shapes of considered poses are defined by specific regions located at the borders of movements. Our modelisation is composed of different steps. First, a volume of optical flow frames highlighting the principal motions in poses is substracted. Then, motion boundaries are computed from the previous optical flow frames. Finally, maximally Stable Extremal Regions (MSER) are applied to motion boundaries frames in order to obtain MSS features. To predict classes of different human actions, the MSS features are combined with a standard bag-of-words representation. To prove the efficiency of our developed model, we have performed a set of experiments on four datasets: Weizmann, KTH, UFC and Hollywood. Obtained experimental results show that the proposed approach significantly outperforms state-of-the-art methods

Video Action Classification: A New Approach Combining Spatio-temporal Krawtchouk Moments and Laplacian Eigenmaps

International audienceAction classification and recognition is a challenging research area that has significant applications in computer vision domain including robotics, video surveillance, human-computer interaction and multimedia retrieval. Action classification domain uses a large variety of approaches. This paper proposes a new approach for video actions classification based on extension of Krawtchouk moments in spatio-temporal domain. In fact, Krawtchouk moments have interesting properties for describing structural and temporal information of a time varying video sequence.The proposed approach is composed of three main steps. First, the original video is transformed into a spatio-temporal volume of images. Then, silhouettes of human in movement are extracted from these images to define a 3D shape. In the third step, higher order spatio-temporal Krawtchouk moments are applied to the obtained 3D shapes and Laplacian eigenmaps is used to achieve dimension reduction for different moments vectors. Finally, we use SVM algorithm and computed descriptors to classify actions in videos. This new approach has been validated on the two video datasets Weizmann and KTH. Experimental results show a good classification rate compared to other approaches using different descriptors

A new method using moments correlation for action change detection in videos

International audienceAutomated characterization of human actions plays an important role in video indexing and retrieval for many applications. Action change detection is considered among the most necessary element to ensure a good video description. However, it is quite challenging to achieve detection without prior knowledge or training. Usually humans are practicing different actions in the same video and their silhouettes give significant information for characterizing human poses in each video frame. We have developed an approach based on pose descriptors of these silhouettes, cross correlations matrices and Kullback-Leibler distance to detect action changes. In this paper, we will focus firstly on the specific problem of change detection in videos. After that, the proposed approach for action change detection will be detailed and tested on Weizman dataset. Finally, experimental results has been analyzed and showed the good performance of our approach

An efficient approach for video action classification based on 3d Zernike moments

International audienceAction recognition in video and still image is one of the most challenging research topics in pattern recognition and computer vision. This paper proposes a new method for video action classification based on 3D Zernike moments. These last ones aim to capturing both structural and temporal information of a time varying sequence. The originality of this approach consists to represent actions in video sequences by a three-dimension shape obtained from different silhouettes in the space-time volume. In fact, the given video is segmented in space-time volume. Then, silhouettes are extracted from obtained images of the video sequences volumes and 3D Zernike moments are computed for video, based on silhouettes volumes. Finally, least square version of SVM (LSSVM) classifier with extracted features is used to classify actions in videos. To evaluate the proposed approach, it was applied on a benchmark human action dataset. The experimentations and evaluations show efficient results in terms of action characterizations and classification. Further more, it presents several advantages such as simplicity and respect of silhouette movement progress in the video guaranteed by 3D Zernike moment

New Photothermal Deflection Method to Determine Thermal Properties of Bulk Semiconductors

5th International Conference on Diffusion in Solids and Liquids (DSL-2009)International audienceIn this paper, we present a new Photothermal Deflection Technique (PTD) to determine thermal properties of bulk doped or undoped semiconductor such as GaAs, GaSb, InAs, etc. The method proposed here consists in covering the sample with a thin graphite layer in order to increase the photothermal signal and to ovoid any reflection on the sample surface. This method deals with the analysis of the logarithm of amplitude and phase variation of the photothermal signal versus square root modulation frequency where the sample placed in air is heated by a modulated light beam coming from a halogen lamp. So the best coincidence between experimental curves and corresponding theoretical ones gives simultaneously the best values of thermal conductivity and thermal diffusivity of the sample. These obtained values are in good agreement with those found in literature. The advantage of applying this method in this way lies in its simplicity and its sensibility to both thermal conductivity and thermal diffusivity

Characterization and Potential Use of Cuttlefish Skin Gelatin Hydrolysates Prepared by Different Microbial Proteases

Composition, functional properties, and in vitro antioxidant activities of gelatin hydrolysates prepared from cuttlefish skin were investigated. Cuttlefish skin gelatin hydrolysates (CSGHs) were obtained by treatment with crude enzyme preparations from Bacillus licheniformis NH1, Bacillus mojavensis A21, Bacillus subtilis A26, and commercial alcalase. All CSGHs had high protein contents, 74.3–78.3%, and showed excellent solubility (over 90%). CSGH obtained by alcalase demonstrated high antioxidant activities monitored by β-carotene bleaching, DPPH radical scavenging, lipid peroxidation inhibition, and reducing power activity. Its antioxidant activity remained stable or increased in a wide range of pH (1–9), during heating treatment (100°C for 240 min) and after gastrointestinal digestion simulation. In addition, alcalase-CSGH was incorporated into turkey meat sausage to determine its effect on lipid oxidation during 35 days of storage period. At 0.5 mg/g, alcalase-CSGH delayed lipid oxidation monitored by TBARS and conjugated diene up to 10 days compared to vitamin C. The results reveal that CSGHs could be used as food additives possessing both antioxidant activity and functional properties

Evaluation of Hypoglycemic and Hypolipidemic Activities

Abstract Functional properties and antioxidant activities in vitro and hypoglycaemic and hypolipidemic activities in vivo of protein hydrolysates prepared from muscle of grey triggerfish (Balistes capriscus) were investigated. Baliste protein hydrolysates (BPHs) were obtained by treatment with crude enzyme preparations from Bacillus mojavensis A21 (BPH-A21), crude enzyme extract from sardinelle (Sardinella aurita) viscera (BPH-S) and crude enzyme extract from Zebra blenny (Slaria basilisca) viscera (BPH-Z). The protein hydrolysate BPH-A21, BPH-S and BPH-Z contained high protein content 87.61%, 74.53% and 54.18%, respectively. The protein hydrolysates had an excellent solubility and possessed interfacial properties, which were governed by their concentrations. Analysis of amino acid composition revealed that Baliste capriscus protein hydrolysates (BPHs) were valuable sources of essential amino acids and rich in lysine and Arginine, which is one of the active ingredients for blood glucose control by inducing insulin release in both rats and humans. Treatment of alloxan-induced diabetic rats (AIDR) with BPHs revealed a significant inhibition of α -amylase activity in serum, as well as a reduction of blood glucose and glycated hemoglobin (HbA1c) levels in diabetic rats. Further, BPHs also decreased significantly the triglyceride (TG), totalcholesterol (TC) and LDL-cholesterol (LDL-c) levels in the serum and liver of diabetic rats, while they increased the HDL-cholesterol (HDL-c) level, which helped to maintain the homeostasis of blood lipids. Furthermore, BPHs exhibited potent protective effects against heart attack markers by reversing myocardial enzyme serum back to normal levels. BCPHs may also a marked decrease in the level of serum bilirubin as well as in the activities of alanine aminotransferase (ALT), alkaline phosphatase (ALP), and gamma-glutamyl transpeptidase (GGT). These beneficial effects of BPHs were confirmed by histological findings in the hepatic and pancreatic tissues of diabetic rats. Indeed, they avoid lipid accumulation in the hepatocytes and protect the pancreatic β-cells from degeneration. Overall, the findings of the current study indicate that BPHs significantly attenuated hyperglycemia and hyperlipidemia in AIDR. The antioxidant activities of protein hydrolysates at different concentrations were evaluated using various in vitro antioxidant assays, including 1,1-diphenyl-2-picrylhydrazyl (DPPH.) radical method, reducing power assay, chelating activity, β-carotene bleaching and DNA nicking assay. All protein hydrolysates showed varying degrees of antioxidant activity. BPH-Z had the highest DPPH radical scavengingactivity (95% at 40 mg/ml) and higher ability to prevent bleaching of β-carotene than BPH-S and BPH-A21 (p<0.05). However, BPH-S exhibited the highest metal chelating activity (76,24% at 0,4 mg/ml) and the strongest protection against hydroxyl radical induced DNA breakage (p<0.05)

Angiotensin I-converting enzyme inhibitory peptides FQPSF and LKYPI identified in Bacillus subtilis A26 hydrolysate of thornback ray muscle Authors

Angiotensin I-converting enzyme (ACE) inhibitory peptides have been searched in thornback ray (Raja clavata) muscle hydrolysed with Bacillus subtilis A26 proteases until a hydrolysis degree of 18.35%. The hydrolysate showed an IC50 of 0.83 mg mL−1. To identify peptides responsible for this activity, the extract was eluted through size-exclusion chromatography and fractions collected. The highest ACE inhibitory activity was found for fractions F2 and F3 which had IC50 of 0.42 and 0.51 mg mL−1, respectively. These fractions were analysed by nano-liquid chromatography coupled to tandem mass spectrometry (nLC-MS/MS). A total of 131 and 108 peptide sequences mainly derived from actin, myosin heavy chain and procollagen alpha 1 chain proteins were identified in fractions F2 and F3, respectively. FQPSF and LKYPI showed the best results with an IC50 of 12.56 and 27.07 μM, respectively. These results prove the potential of thornback ray muscle hydrolysate as a source of ACE inhibitory peptides.This work was funded by a grant from the Ministry of Higher Education and Scientific Research of Tunisia and grant Prometeo/2012/001 from Conselleria d´Educació Cultura i Sport of Generalitat Valenciana, both are acknowledged. JAEDOC- CSIC postdoctoral contract cofounded by ESF to L.M. is also acknowledgedPeer reviewe