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Major Families (major + family)
Selected AbstractsThere are three major families of crystallins: misnaming of ,B crystallinACTA PHYSIOLOGICA, Issue 4 2009P. G. Sreekumar No abstract is available for this article. [source] Widespread hermaphroditism in freshwater gastrotrichsINVERTEBRATE BIOLOGY, Issue 4 2001Mitchell J. Weiss Abstract. Freshwater members of the phylum Gastrotricha were long thought to lack male gametes and to exist exclusively as parthenogenetic females. The surprising 1978 discovery of sperm in the common species Lepidodermella squamata raised the question of how many other freshwater gastrotrichs might likewise be hermaphroditic. In a comparative study of species from across both major families, sperm have been found in every species examined intensively. They were detected in 19 species of Chaetonotidae (from Aspidiophorus, Chaetonotus, Heterolepidoderma, Ichthydium, Lepidodermella, and Polymerurus) and 3 species of Dasydytidae (from Haltidytes, Setopus, and Stylochaeta), characteristically occurring ventrally in single unilateral or (more often) 2,12 bilateral packets. Their shape ranges from filiform (length in Chaetonotus bisacer, ,40 ,m) to rodlike, spindlelike, oval, and possibly spherical (some in Stylochaeta scirtetica measure only 1 ,m). With light microscopy, a dense nucleus appears to fill the entire volume of these aflagellate cells. Spermatogenesis within cysts (maximally, 16 sperm/clone) is evidently characteristic of both families, each cyst generating one large residual body. Sperm-bearers display oocytes with sometimes distinctive cytoplasmic elements and a posterior X-organ whose organization can be complex. Evidence supports an unusual life cycle in which parthenogenesis is followed by simultaneous hermaphroditism. These findings may illuminate the reproductive characters as well as ancestry of marine and brackish-water taxa of Chaetonotida. [source] Object-oriented approach to drug design enabled by NMR SOLVE: First real-time structural tool for characterizing protein,ligand interactionsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue S37 2001Daniel S. Sem Abstract As a result of genomics efforts, the number of protein drug targets is expected to increase by an order of magnitude. Functional genomics efforts are identifying these targets, while structural genomics efforts are determining structures for many of them. However, there is a significant gap in going from structural information for a protein target to a high affinity (Kd,<,100 nM) inhibitor, and the problem is multiplied by the sheer number of new targets now available. nature frequently designs proteins in classes that are related by the reuse, through gene duplication events, of cofactor binding domains. This reuse of functional domains is an efficient way to build related proteins in that it is object-oriented. There is a growing realization that the most efficient drug design strategies for attacking the mass of targets coming from genomics efforts will be systems-based approaches that attack groups of related proteins in parallel. We propose that the most effective drug design strategy will be one that parallels the object-oriented manner by which nature designed the gene families themselves. IOPE (Integrated Object-Oriented PharmacoEngineering) is such an approach. It is a three-step technology to build focused combinatorial libraries of potential inhibitors for major families and sub-families of enzymes, using cogent NMR data derived from representatives of these protein families. The NMR SOLVE (Structurally Oriented Library Valency Engineering) data used to design these libraries are gathered in days, and data can be obtained for large proteins (>,170 kDa). Furthermore, the process is fully object-oriented in that once a given bi-ligand is identified for a target, potency is retained if different cofactor mimics are swapped. This gives the drug design process maximum flexibility, allowing for the more facile transition from in vitro potency to in vivo efficacy. J. Cell. Biochem. Suppl. 37: 99,105, 2001. © 2002 Wiley-Liss, Inc. [source] Viscometric properties of viscosity index improvers in lubricant base oil over a wide temperature range.LUBRICATION SCIENCE, Issue 2 2000Part I: Group II base oil Capillary viscometry has been employed to measure the viscosities of dilute polymer solutions over the temperature range -10 to 150 °C. A Group II base oil containing 95% saturates was used as solvent for an olefin copolymer (OCP), a hydrogenated diene copolymer (HDP), and a polymethacrylate (PMA). These three polymers represent the three major families of viscosity index (VI) improvers used nowadays in lubricant formulations. Intrinsic viscosities and Huggins' constants were also determined. The thickening effects of the olefin copolymer and the hydrogenated diene copolymer were found to be higher at low temperatures (e.g., 40 °C) than at higher ones (e.g., 100 °C), which phenomenon was attributed to stronger intermolecular hydrodynamic interactions at low temperatures, as indicated by the Huggins constants. For the hydrogenated diene copolymer and the polymethacrylate polymer, the viscosity increased abruptly when the temperature went below 10 °C. This unusual observation was attributed to the crystallisation of a small fraction of the base oil. Based on the intrinsic viscosity data, it was concluded that at temperatures between 10 and 150 °C, the polymer coil dimension remains a constant for the olefin copolymer and the hydrogenated diene copolymer VI improvers, but increases with increasing temperature for the polymethacrylate VI improver. [source] Epigenetic chromatin modifiers in barley: I. Cloning, mapping and expression analysis of the plant specific HD2 family of histone deacetylases from barley, during seed development and after hormonal treatmentPHYSIOLOGIA PLANTARUM, Issue 3 2009Kyproula Demetriou Epigenetic phenomena have been associated with modifications of chromatin structure. These are achieved, in part, by histone post-translational modifications including acetylations and deacetylations, the later being catalyzed by histone deacetylaces (HDACs). Eukaryotic HDACs are grouped into three major families, RPD3/HDA1, SIR2 and the plant-specific HD2. HDAC genes have been analyzed from model plants such as Arabidopsis, rice and maize and have been shown to be involved in various cellular processes including seed development, vegetative and reproductive growth and responses to abiotic and biotic stress, but reports on HDACs from other crops are limited. In this work two full-length cDNAs (HvHDAC2-1 and HvHDAC2-2) encoding two members of the plant-specific HD2 family, respectively, were isolated and characterized from barley (Hordeum vulgare), an agronomically important cereal crop. HvHDAC2-1 and HvHDAC2-2 were mapped on barley chromosomes 1H and 3H, respectively, which could prove useful in developing markers for marker-assisted selection in breeding programs. Expression analysis of the barley HD2 genes demonstrated that they are expressed in all tissues and seed developmental stages examined. Significant differences were observed among tissues and seed stages, and between cultivars with varying seed size, suggesting an association of these genes with seed development. Furthermore, the HD2 genes from barley were found to respond to treatments with plant stress-related hormones such as jasmonic acid (JA), abscisic acid (ABA) and salicylic acid (SA) implying an association of these genes with plant resistance to biotic and abiotic stress. The expression pattern of HD2 genes suggests a possible role for these genes in the epigenetic regulation of seed development and stress response. [source] Host relationships at plant family level in Dendrothrips Uzel (Thysanoptera: Thripidae: Dendrothripinae) with a new Australian speciesAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 1 2003Rita Marullo Abstract The genus Dendrothrips Uzel (Thysanoptera: Thripidae, Dendrothripinae) comprises 50 described species from the Old World, including a fourth species from Australia, D. williamsi sp. n. For many of these species no host plant has been recorded, but the genera and families of the recorded host plants of 27 species are tabulated. These thrips are mainly associated with trees and shrubs, and the plant families involved come from five of the six subclasses of the Dicotyledonae. Several Dendrothrips species are recorded from Oleaceae and Flacourtiaceae, but none from the major families of tropical trees, Moraceae and Lauraceae. [source] In vitro neuromuscular activity of snake venomsCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 9 2002Wayne C Hodgson Summary 1.,Snake venoms consist of a multitude of pharmacologically active components used for the capture of prey. Neurotoxins are particularly important in this regard, producing paralysis of skeletal muscles. These neurotoxins can be classified according to their site of action (i.e. pre- or post-synaptic). 2.,Presynaptic neurotoxins, which display varying phospholipase A2 activities, have been identified in the venoms of the four major families of venomous snakes (i.e. Crotalidae, Elapidae, Hydrophiidae and Viperidae). The blockade of transmission produced by these toxins is usually characterized by a triphasic effect on acetylcholine release. Considerable work has been directed at identifying the binding site(s) on the presynaptic nerve terminal for these toxins, although their mechanism of action remains unclear. 3.,Post-synaptic neurotoxins are antagonists of the nicotinic receptor on the skeletal muscle. Depending on their sequence, post-synaptic toxins are subdivided into short- and long-chain toxins. These toxins display different binding kinetics and different affinity for subtypes of nicotinic receptors. Post-synaptic neurotoxins have only been identified in venoms from the families Elapidae and Hydrophiidae. 4.,Due to the high cost of developing new antivenoms and the reluctance of many companies to engage in this area of research, new methodologies are required to test the efficacy of existing antivenoms to ensure their optimal use. While chicken eggs have proven useful for the examination of haemorrhagic venoms, this procedure is not suited to venoms that primarily display neurotoxic activity. The chick biventer cervicis muscle has proven useful for this procedure, enabling the rapid screening of antivenoms against a range of venoms. 5.,Historically, the lethality of snake venoms has been based on murine LD50 studies. Due to ethical reasons, these studies are being superseded by in vitro studies. Instead, the time taken to produce 90% inhibition of nerve-mediated twitches (i.e. t90) in skeletal muscle preparations can be determined. However, these two procedures result in different rank orders because they are measuring two different parameters. While murine LD50 determinations are based on ,quantity', t90 values are based on how ,quick' a venom acts. Therefore, knowledge of both parameters is still desirable. 6.,In vitro neuromuscular preparations have proven to be invaluable tools in the examination of snake venoms and isolated neurotoxins. They will continue to play a role in further elucidating the mechanism of action of these highly potent toxins. Further study of these toxins may provide more highly specific research tools or lead compounds for pharmaceutical agents. [source] Integrin signaling through FAK in the regulation of mammary stem cells and breast cancerIUBMB LIFE, Issue 4 2010Jun-Lin Guan Abstract Focal adhesion kinase (FAK) is a cytoplasmic tyrosine kinase identified as a key mediator of intracellular signaling by integrins, a major family of cell surface receptors for extracellular matrix, in the regulation of different cellular functions in a variety of cells. Upon activation by integrins through disruption of an autoinhibitory mechanism, FAK undergoes autophosphorylation and forms a complex with Src and other cellular proteins to trigger downstream signaling through its kinase activity or scaffolding function. A number of integrins are identified as surface markers for mammary stem cells (MaSCs), and both integrins and FAK are found to play crucial roles in the maintenance of MaSCs in studies using mouse models, suggesting that integrin signaling through FAK may serve as a functional marker for MaSCs. Consistent with previous studies linking increased expression and activation of FAK to human breast cancer, these findings suggest a novel cellular mechanism of FAK promotion of mammary tumorigenesis by maintaining the pools of MaSCs as targets of oncogenic transformation. Furthermore, FAK inactivation in mouse models of breast cancer also reduced the pool of mammary cancer stem cells (MaCSCs), decreased their self-renewal in vitro, and compromised their tumorigenicity and maintenance in vivo, suggesting a potential role of integrin signaling through FAK in breast cancer growth and progression through its functions in MaCSCs. This review discusses these recent advances and future studies into the mechanism of integrin signaling through FAK in breast cancer through regulation of MaCSCs that may lead to development of novel therapies for this deadly disease. © 2010 IUBMB IUBMB Life, 62(4): 268,276, 2010 [source] Remodeling of the SCF complex-mediated ubiquitination system by compositional alteration of incorporated F-box proteinsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 1 2010Mitsunori Kato Abstract Ubiquitination regulates not only the stability but the localization and activity of substrate proteins involved in a plethora of cellular processes. The Skp1,Cullin,F-box protein (SCF) complexes constitute a major family of ubiquitin protein ligases, in each member of which an F-box protein serves as the variable component responsible for substrate recognition, thereby defining the function of each complex. Here we studied whether the composition of F-box proteins in the SCF complexes is remodeled under different conditions. We exploited stable isotope labeling and MS for relative quantification of F-box proteins in the SCF complexes affinity-purified en masse from budding yeast cells at log and post-diauxic phases, and revealed an increment of Saf1, an F-box protein involved in entry into quiescence, during the diauxic shift. Similarly, we found that Met4 overexpression induces a specific increment of Met30, the F-box protein responsible for ubiquitination of Met4. These results illustrate a cellular response to environmental and genetic perturbations through remodeling of the SCF complex-mediated ubiquitination system. Compositional alteration of incorporated F-box proteins may redirect the activity of this system toward appropriate substrates to be ubiquitinated under individual conditions for the maintenance of cellular homeostasis. [source] REVIEW ARTICLE: Toll-Like Receptors at the Maternal,Fetal Interface in Normal Pregnancy and Pregnancy DisordersAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 6 2010Kaori Koga Citation Koga K, Mor G. Toll-like receptors at the maternal,fetal interface in normal pregnancy and pregnancy disorders. Am J Reprod Immunol 2010 Toll-like receptors (TLR) form the major family of pattern recognition receptors (PRR) that are involved in innate immunity. Innate immune responses against microorganisms at the maternal,fetal interface may have a significant impact on the success of pregnancy, as intrauterine infections have been shown to be strongly associated with certain disorders of pregnancy. At the maternal,fetal interface, TLRs are expressed not only in the immune cells but also in non-immune cells such as trophoblasts and decidual cells; moreover, their expression patterns vary according to the stage of pregnancy. Here, we will describe potential functions of TLRs in these cells, their recognition and response to microorganisms, and their involvement in the innate immunity. The impact of TLR-mediated innate immune response will be discussed via animal model studies, as well as clinical observations. [source] | |||||||||||||