Long-term prediction of fish growth under varying ambient temperature using a multiscale dynamic model

Background  

Feed composition has a large impact on the growth of animals, particularly marine fish. We have developed a quantitative dynamic model that can predict the growth and body composition of marine fish for a given feed composition over a timespan of several months. The model takes into consideration the effects of environmental factors, particularly temperature, on growth, and it incorporates detailed kinetics describing the main metabolic processes (protein, lipid, and central metabolism) known to play major roles in growth and body composition.     

Apparent recruitment failure for the vast majority of coral species at Eilat,Red Sea

Coral Reefs - The status of coral reefs is often portrayed by parameters (e.g., coverage, bleaching, diseases, nutrients and rugosity) assigned to adult populations. Yet, coral recruitment is...     

Polarization Vision in Cephalopods: Neuroanatomical and Behavioral Features that Illustrate Aspects of Form and Function

Polarization sensitivity (PS), which arises from the orthogonal arrangement of microvilli in the retina, has long been known in shallow-water cephalopods. Micrographs presented herein signify that some deep-water cephalopods may also possess PS. Precise measurements of the angles of microvilli in the retinas of shallow-water octopus, squid and cuttlefish revealed neuroanatomical differences that may explain variation in the limits of polarization angular discrimination in different species and habitats. A question yet unanswered is whether cephalopods can discriminate between polarization and intensity. Recent behavioral experimentation has illustrated that one clear function of PS is enhanced predation: it enables better detection of transparent, opaque, or silvery-reflecting prey. The use of PS for navigation in cephalopods is still controversial, and our recent experiment on squids failed to support this notion. It is possible that cephalopods show polarization patterning produced in their skin as a mode of communication that cannot be detected by polarization-insensitive predators such as many fishes and marine mammals.     

Effects of mitochondrial protein synthesis inhibitors on the incorporation of isoleucine into Plasmodium falciparum in vitro

Plasmodium falciparum was grown in human erythrocytes in vitro and the effect of chloramphenicol, erythromycin, and tetracycline on growth and maturation of the parasites and on their ability to incorporate [3H]isoleucine into protein was observed. Exposure of rings to high concentrations of chloramphenicol had little effect on subsequent maturation of the rings whereas brief (4 h) exposure of trophozoites caused a dose-dependent inhibition of subsequent ring formation. Incorporation of [3H]isoleucine into protein was not affected during at least 6 h of exposure to high concentration of the three drugs examined, but appreciable inhibition was observed after 21 h, with chloramphenicol being the least effective inhibitor. These results suggest that there is a stage-specific effect of inhibition of mitochondrial protein synthesis on subsequent development and that the mitochondria are essential for growth and development even though they lack a functional Krebs cycle.     

Groundnut (Arachis hypogaea L.) cultivars for cultivation on calcareous soils

Summary Studies of incubation experiments showed that the phosphorus turnover under aerobic decomposition in soil starts with a non-biological process, which is rapid and probably due to chemical fixation. The present study allowed a distinction to be made between chemical fixation and biological immobilisation of added phosphorus with special reference to the effects of addition of energy material in the process of biological turnover. Invariably, both glucose and cellulose additions resulted in an increase in phosphorus immobilisation. Comparatively, cellulose acted slowly on phosphorus turnover, with the prospect of more immobilisation in long term experiments. re]19730416     

Bipedal locomotion in Octopus vulgaris: A complementary observation and some preliminary considerations

Lacking an external shell and a rigid endoskeleton, octopuses exhibit a remarkable flexibility in their movements. Bipedal locomotion is perhaps the most iconic example in this regard. Until recently, this peculiar mode of locomotion had been observed only in two species of tropical octopuses: Amphioctopus marginatus and Abdopus aculeatus. Yet, recent evidence indicates that bipedal walking is also part of the behavioral repertoire of the common octopus, Octopus vulgaris. Here we report a further observation of a defense behavior that encompasses both postural and locomotory elements of bipedal locomotion in this cephalopod. By highlighting differences and similarities with the other recently published report, we provide preliminary considerations with regard to bipedal locomotion in the common octopus.     

Complexity of FGF receptors: genetic basis for structural diversity and functional specificity.

Since 1989, the receptors for fibroblast growth factors (FGFs) were cloned and characterized as a subgroup of the family of receptor tyrosine kinases. Four FGF receptor genes were identified, all of which encode membrane-bound glycoproteins containing three immunoglobulin (Ig) -like domains at the extracellular region, where only two of these domains are involved in ligand binding. Three unique features characterize the FGF receptors: 1) overlapping recognition and redundant specificity, where one receptor may bind with a similar affinity several of the seven known FGFs and one FGF may bind similarly to several distinct receptors. 2) The binding of FGFs to their receptors is dependent on the interaction of FGF with cell surface heparan sulfate proteoglycans. 3) A multitude of isoforms of cell-bound or secreted receptors are produced by the same gene. The gene structure of these receptors revealed two major mechanisms that are responsible for the formation of the diverse forms: alternative mRNA splicing, resulting in deletions or alternate exons usage, and internal polyadenylation, resulting in truncated products. These are reminiscent of mechanisms that also operate in the immunoglobulin family to generate diversity and to produce either secreted or cell-bound molecules. Tissue-specific alternative splicing in FGF receptors allows for the generation of two distinct receptors from a single gene because alternative exons determine the sequence of the COOH-terminal half of the third Ig-like domain involved in ligand binding. This represents a novel genetic mechanism to generate receptor diversity and specificity and to increase receptor repertoire.