Gastric evacuation in the young lemon shark,Negaprion brevirostris,under field conditions

Synopsis Gastric evacuation in young lemon sharks, Negaprion brevirostris, was studied in a field enclosure. Regression analysis was used to evaluate the adequacy of linear, exponential, and square root models in describing the decrease in stomach contents with time after feeding. The linear model produced the best fit and was thus used to compare gastric evacuation at the three temperatures. Gastric evacuation in young lemon sharks is considerably longer than for carnivorous teleosts but shorter than for other elasmobranchs. These differences are the result of differing energy requirements determined by the physiology and behavior of the species.     

Metabolism of glycerate-2,3-P2--IV. Effect of Hg2+ on the enzymes involved in the metabolism of glycerate-2,3-P2 in pig skeletal muscle

Type M phosphoglycerate mutase and skeletal muscle bisphosphoglycerate synthase-phosphatase from pig are similarly affected by Hg2+. Both enzymes lose the phosphoglycerate mutase and the glycerate-2,3-P2 synthase activities, and increase the glycerate-2,3-P2 phosphatase activity upon Hg2+-treatment. In contrast, bisphosphoglycerate phosphatase from pig skeletal muscle is inactivated by Hg2+. These results confirm the similarity between phosphoglycerate mutase and bisphosphoglycerate synthase-phosphatase. In addition they support the existence of separate binding sites for monophosphoglycerates and for bisphosphoglycerates at the phosphoglycerate mutase active site.     

Control analysis of transition times

Summary The present theoretical basis of Control Analysis is extended with the definition of Transition Time Response Coefficients. Some new relationships between local and global coefficients defined in Control Analysis are presented. These relationships are in the form of matrix products constructed in a priori form. The use of these straightforward relationships is shown in an exemplary application corresponding to an experimental system consisting of the glycolytic degradation from glucose to glyceraldehyde-3-phosphate.     

The Occurrence of White Sharks, Carcharodon carcharias, Around the Balearic Islands (Western Mediterranean Sea)

The regular presence of the white shark, Carcharodon carcharias, off the Balearic Islands (western Mediterranean) is shown from 27 captures carried out with trap nets between the 1920s and 1970s and from eight attacks on cetaceans and marine turtles from the 1990s to the present. The geographic distribution, seasonality and population structure of the species in the area are analysed and discussed in relation to environmental conditions and to the proposed distribution of this species in the Mediterranean Sea.     

Depolarization metric spaces for biological tissues classification

Classification of tissues is an important problem in biomedicine. An efficient tissue classification protocol allows, for instance, the guided‐recognition of structures through treated images or discriminating between healthy and unhealthy regions (e.g., early detection of cancer). In this framework, we study the potential of some polarimetric metrics, the so‐called depolarization spaces, for the classification of biological tissues. The analysis is performed using 120 biological ex vivo samples of three different tissues types. Based on these data collection, we provide for the first time a comparison between these depolarization spaces, as well as with most commonly used depolarization metrics, in terms of biological samples discrimination. The results illustrate the way to determine the set of depolarization metrics which optimizes tissue classification efficiencies. In that sense, the results show the interest of the method which is general, and which can be applied to study multiple types of biological samples, including of course human tissues. The latter can be useful for instance, to improve and to boost applications related to optical biopsy.     

Effects of different methods of ovarian stimulation in adult rats

The in vitro fecundation programs normally use different ovarian stimulation agents. The purpose of the present study was to compare the effects of some of these agents on indices of ovulation and serum levels of estradiol, progesterone, and FSH. Treatments studied consisted of clomiphene citrate, PMSG alone and in combination with clomiphene citrate, pure human FSH and epimestrol. The data obtained show PMSG alone and PMSG plus clomiphene citrate to be the most effective treatments, in terms of number of oocytes harvested. No differences were noted between serum levels of oestradiol, progesterone and FSH.     

Vanadate inhibits 2,3-bisphosphoglycerate dependent phosphoglycerate mutases but does not affect the 2,3-bisphosphoglycerate independent phosphoglycerate mutases

There are two types of phosphoglycerate mutases. The 2,3-bisphosphoglycerate dependent phosphoglycerate mutases are inhibited by vanadate. In contrast, the 2,3-bisphosphoglycerate independent mutases are not affected. The effect of vanadate varies with pH, and can be reversed by dilution, EDTA and norepinephrine. The differential effect of vanadate on the two types of phosphoglycerate mutases supplies a novel way to easily differentiate both types of enzymes. In addition, it may contribute to the clarification of the mechanism of action of the 2,3-bisphosphoglycerate independent phosphoglycerate mutases.     

Differential protein expression in endothelial cells exposed to serum from patients with acute graft-vs-host disease,depending on steroid response

Graft-versus-host disease (GVHD) is a complication of allogeneic haematopoietic cell transplantation. Endothelial injury is crucial as pathophysiological substrate for GVHD. GVHD first-line treatment is high-dose corticosteroids, although some patients are steroid-refractory. Through the present study, we compared the endothelial proteomic profiles in response to serum from steroid-refractory acute GVHD (SR-aGVHD) and steroid-sensitive acute GVHD (SS-aGVHD) patients. Blood samples from SR-aGVHD (n = 4) and SS-aGVHD (n = 8) patients were collected at aGVHD diagnosis. Endothelial cell cultures were exposed (48 h) to patients' serum. Protein extraction and proteomic analysis were performed. Differences were statistically evaluated by multivariate analysis. Forty-four proteins contributed to separate all samples into the two study groups, among which 15 participated significantly (p < 0.05), 10 exhibiting a fold change >1.2. Differentially expressed proteins were mainly associated with oxidative phosphorylation (Cytochrome C oxidase subunit 6B1, CX6B1), inflammation and angiogenesis (Apolipoprotein D, APOD), cell survival (Rapamycin-insensitive companion of mTOR, RICTR), and oxidative stress (Riboflavin kinase, RIFK). This pilot study used a novel approach to distinguish the aGVHD response to steroid treatment. The proteins differentially expressed could constitute potential biomarkers for steroid-treatment response. These findings signify a step forward to identify the mechanisms of response to steroids, of high clinical relevance considering the SR-aGVHD elevated mortality.     

The association of metabotropic glutamate receptor type 5 with the neuronal Ca2+-binding protein 2 modulates receptor function

Metabotropic glutamate (mGlu) receptors mediate in part the CNS effects of glutamate. These receptors interact with a large array of intracellular proteins in which the final role is to regulate receptor function. Here, using co-immunoprecipitation and pull-down experiments we showed a close and specific interaction between mGlu₅ receptor and NECAB2 in both transfected human embryonic kidney cells and rat hippocampus. Interestingly, in pull-down experiments increasing concentrations of calcium drastically reduced the ability of these two proteins to interact, suggesting that NECAB2 binds to mGlu₅ receptor in a calcium-regulated manner. Immunoelectron microscopy detection of NECAB2 and mGlu₅ receptor in the rat hippocampal formation indicated that both proteins are codistributed in the same subcellular compartment of pyramidal cells. In addition, the NECAB2/mGlu₅ receptor interaction regulated mGlu_5b-mediated activation of both inositol phosphate accumulation and the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway. Overall, these findings indicate that NECAB2 by its physical interaction with mGlu_5b receptor modulates receptor function.