Influence of exercise on cardiac and skeletal muscle myofibrillar proteins

The purpose of this study was to examine the Ca²⁺-Mg²⁺ myofibrillar ATPase and protein composition of cardiac and skeletal muscle following strenuous activity to voluntary exhaustion. Sprague-Dawley rats (200 g) were assigned to a control and exercised group, with the run group completing 25 m·min^–1 and 8% grade for 1 hour. Following activity, the myocardial Ca²⁺–Mg²⁺ myofibrillar ATPase activity -pCa relationship had undergone a rightward shift in the curve. Electrophoretic analysis revealed a change in the pattern of cardiac myofibrillar protein bands, particularly in the 38–42 Kdalton region. Enzymatic analysis of myofibrillar proteins from plantaris muscle, revealed no change in Ca²⁺ regulation following exercise. Electronmicrographic and electrophoretic analysis revealed extensively disrupted sarcomeric structure and a change in the ratio of several plantaris myofibrillar proteins. No difference was observed for myosin: Actin: tropomyosin ratios; however a dramatic reduction in 58 and 95 Kdalton proteins were evident. The results indicate that prolonged running is associated with similar responses in cardiac and skeletal muscle myofibrillar protein compositions. The abnormalities in myofibrillar ultrastructure may implicate force transmission failure as a factor in exercised-induced muscle damage and/or fatigue.     

Carotenoids and carotenoid metabolism in Carcinus maenas (Crustacea: Decapoda)

The carotenoid pigments of the hepatopancreas, ovaries and epidermis of Carcinus maenas were investigated. The following pigments were identified: β-carotene, δ-carotene, echinenone, isocryptoxanthin, canthaxanthin, lutein, zeaxanthin, flavoxanthin and astacene.
The relative abundance of these pigments in the three tissues and the presence of possible hydroxy and keto intermediates suggest the metabolism of astaxanthin from β-carotene. The metabolic pathway in Carcinus is discussed in relation to recent studies on other invertebrates.     

Carotenoids and carotenoid metabolism in Carcinus maenas (Crustacea: Decapoda)

The carotenoid pigments of the hepatopancreas, ovaries and epidermis of Carcinus maenas were investigated. The following pigments were identified: β-carotene, δ-carotene, echinenone, isocryptoxanthin, canthaxanthin, lutein, zeaxanthin, flavoxanthin and astacene.
The relative abundance of these pigments in the three tissues and the presence of possible hydroxy and keto intermediates suggest the metabolism of astaxanthin from β-carotene. The metabolic pathway in Carcinus is discussed in relation to recent studies on other invertebrates.     

Comparison of α1-Adrenergic Receptor-Stimulated Inositol Phosphate Formation in Primary Neuronal and Glial Cultures

alpha 1-Adrenergic receptor binding sites and norepinephrine-stimulated 3H-inositol phosphate (3H-InsP) accumulation were measured in primary cultures of neurons and glia from 1-day-old rat brains. The density of alpha 1-adrenergic receptor binding sites was approximately three times higher in membranes from neurons compared to glia. Although norepinephrine was slightly more potent in stimulating 3H-InsP formation in neurons than in glia, the maximal response was greater in glial cells. Norepinephrine-stimulated 3H-InsP formation remained constant for [3H]inositol prelabelling periods of 1-14 days in neurons, whereas the response increased with time in glia and was maximal after 7-10 days of prelabelling. Both the incorporation of [3H]inositol into lipid and basal levels of 3H-InsPs were lower in glial cells than in neurons, which accounted for the greater percent stimulation in glia. Pretreatment with phenoxybenzamine decreased norepinephrine-stimulated 3H-InsP formation in a dose-dependent manner in both neurons and glia by decreasing the maximal response without altering potency. HPLC separation showed that similar types of 3H-InsPs were accumulated in neurons and glial cells. These results demonstrate that alpha 1-adrenergic receptors exist on both neurons and glial cells and activate 3H-InsP accumulation in both cell types. Although receptor density is higher in neurons than in glia, the 3H-InsP response is higher in glia. This difference does not appear to be due to different receptor reserves, but may be due to differential coupling mechanisms in the two cell types.     

Localization of sequences regulating ancestral and acquired sites of esterase6 activity in Drosophila melanogaster

We have broadly defined the DNA regions regulating esterase6 activity in several life stages and tissue types of D. melanogaster using P- element-mediated transformation of constructs that contain the esterase6 coding region and deletions or substitutions in 5' or 3' flanking DNA. Hemolymph is a conserved ancestral site of EST6 activity in Drosophila and the primary sequences regulating its activity lie between -171 and -25 bp relative to the translation initiation site: deletion of these sequences decrease activity approximately 20-fold. Hemolymph activity is also modulated by four other DNA regions, three of which lie 5' and one of which lies 3' of the coding region. Of these, two have positive and two have negative effects, each of approximately twofold. Esterase6 activity is present also in two male reproductive tract tissues; the ejaculatory bulb, which is another ancestral activity site, and the ejaculatory duct, which is a recently acquired site within the melanogaster species subgroup. Activities in these tissues are at least in part independently regulated: activity in the ejaculatory bulb is conferred by sequences between -273 and -172 bp (threefold decrease when deleted), while activity in the ejaculatory duct is conferred by more distal sequences between -844 and -614 bp (fourfold decrease when deleted). The reproductive tract activity is further modulated by two additional DNA regions, one in 5' DNA (-613 to -284 bp; threefold decrease when deleted) and the other in 3' DNA (+1860 to +2731 bp; threefold decrease when deleted) that probably overlaps the adjacent esteraseP gene. Collating these data with previous studies suggests that expression of EST6 in the ancestral sites is mainly regulated by conserved proximal sequences while more variable distal sequences regulate expression in the acquired ejaculatory duct site.      

Calcium and calcium-binding proteins in the nucleus

Calcium has long been known to play a role as a key cytoplasmic second messenger, but until relatively recently its possible involvement in nuclear signal transduction and the regulation of nuclear events has not been extensively studied. Evidence revealing the presence of transmembrane nuclear Ca²⁺ gradients and a variety of intranuclear Ca²⁺ binding proteins has fueled renewed interest in this key ion and its involvement in cell-cycle timing and division, gene expression, and protein activation. This review will offer an overview of the current state of knowledge and theory regarding calcium orchestration of nuclear functions and events and discuss possible future directions in this field of study.     

Phylogenetic diversification of immunoglobulin genes and the antibody repertoire

Immunoglobulins are encoded by a large multigene system that undergoes somatic rearrangement and additional genetic change during the development of immunoglobulin-producing cells. Inducible antibody and antibody-like responses are found in all vertebrates. However, immunoglobulin possessing disulfide-bonded heavy and light chains and domain-type organization has been described only in representatives of the jawed vertebrates. High degrees of nucleotide and predicted amino acid sequence identity are evident when the segmental elements that constitute the immunoglobulin gene loci in phylogenetically divergent vertebrates are compared. However, the organization of gene loci and the manner in which the independent elements recombine (and diversify) vary markedly among different taxa. One striking pattern of gene organization is the "cluster type" that appears to be restricted to the chondrichthyes (cartilaginous fishes) and limits segmental rearrangement to closely linked elements. This type of gene organization is associated with both heavy- and light-chain gene loci. In some cases, the clusters are "joined" or "partially joined" in the germ line, in effect predetermining or partially predetermining, respectively, the encoded specificities (the assumption being that these are expressed) of the individual loci. By relating the sequences of transcribed gene products to their respective germ-line genes, it is evident that, in some cases, joined-type genes are expressed. This raises a question about the existence and/or nature of allelic exclusion in these species. The extensive variation in gene organization found throughout the vertebrate species may relate directly to the role of intersegmental (V<==>D<==>J) distances in the commitment of the individual antibody-producing cell to a particular genetic specificity. Thus, the evolution of this locus, perhaps more so than that of others, may reflect the interrelationships between genetic organization and function.      

Considerations for operational space definition and optimization of a no-salt flowthrough hydrophobic interaction chromatography purification step

No-salt flowthrough hydrophobic interaction chromatography (HIC) has been shown to effectively remove process and product-related impurities from bioprocess streams. In this publication, a panel of six antibodies has been used to demonstrate operating principles for the application of no-salt flowthrough HIC in antibody purification processes. The results indicate that no-salt flowthrough HIC provides robust aggregate clearance across operating conditions including flow rate, and variations in resin ligand density. Additionally, HMW reduction has an optimal pH range relative to the isoelectric point of each molecule and high molecular weight (HMW) reduction can be improved by altering the total protein load and/or HMW concentration to drive binding of high molecular weight species to the resin.