bluuebunny/crossref_metadata_2025_split huggingface dataset:
Self‐incompatibility in flowering plants
Authors: Dickinson Hugh G. 
Published: February 2005

AbstractSelf‐pollination in some groups of plants is prevented by a sophisticated biochemical signalling system. The molecule active in the female emerges as a highly charged glycoprotein, but the identity of the male determinant remains unknown. Studies of both the molecular biology and the physiology of the interaction suggest that the female polypeptide belongs to a family of glycoproteins which may play an additional, and more general, role in pollination. Pollen compatibility is controlled by one of two genetic systems and new information indicates a mechanism by which they may have arisen, together with the different stigma types with which they are correlated.
Induction of a phosphomannosyl binding lectin activity in Giardia
Authors: Ward Honorine D. , Keusch Gerald T. , Pereira Miercio E. A. 
Published: February 2005

AbstractGiardia lamblia, a protozoan parasite that causes widespread diarrheal disease, expresses a surface membrane associated lectin, taglin, which is specifically activated by limited proteolysis with trypsin, a protease that is present in abundance at the site of infection. When activated, taglin agglutinates enterocytes which are the cells to which the parasite adheres in vivo, and in addition, binds to isolated brush border membranes of these cells. These findings suggest that this lectin may be involved in the host‐parasite interaction. Taglin is most specific for terminal phosphomannosyl residues and its binding to red cells is mediated by cell surface phosphate residues. Hemagglutinating activity induced by taglin is most active at pH6.5 and is dependent on divalent cations. A monoclonal antibody to taglin reacts with the surface membrane of live trophozoites and recognizes a protein of 28/30 kDa in lysates of Giardia trophozoites, by immunoblotting. This finding is confirmed by direct demonstration of lectin activity by erythrocyte binding to proteins electroblotted to nitrocellulose, which revealed specific red cell binding to giardial protein bands in the same molecular weight range as those recognized by the monoclonal antibody.
Molecular machinery required for protein transport from the endoplasmic reticulum to the golgi complex
Authors: Hicke Linda , Schekman Randy 
Published: February 2005

AbstractThe cellular machinery responsible for conveying proteins between the endoplasmic reticulum and the Golgi is being investigated using genetics and biochemistry. A role for vesicles in mediating protein traffic between the ER and the Golgi has been established by characterizing yeast mutants defective in this process, and by using recently developed cell‐free assays that measure ER to Golgi transport. These tools have also allowed the identification of several proteins crucial to intracellular protein trafficking. The characterization and possible functions of several GTP‐binding proteins, peripheral membrane proteins, and an integral membrane protein during ER to Golgi transport are discussed here.
What's new?: From gene to phenotype in Drosophila and other organisms
Authors: Kaiser Kim 
Published: February 2005

AbstractThe growing number of cloned eukaryotic genes lacking a defined or proven biological function poses a major challenge in ‘reverse genetics’. A method is described here that permits efficient screening for new lesions in, or close to, genes corresponding to cloned DNA sequences of interest. The technique involves transposon mutagenesis, followed by screening of DNA isolated from a population of mutagenised individuals (or their progeny) for evidence that the population contains at least one individual in which transposon insertion has occurred at the target locus. Detection of rare individuals within the population is facilitated by the use of the polymerase chain reaction (PCR). Once recognised, specific individuals (or their progeny) are isolated from the population by a process of sib‐selection. In cases where insertion of the transposon has occurred close to, but not within, the target locus, secondary events involving imprecise excision of the transposon will nonetheless allow the isolation of mutant individuals. Though the method was developed specifically for the transposon‐mutagenesis of Drosophila, extensions to other organisms and to other mutagenic strategies are feasible and some of the possibilities are discussed.
Expression of human plasma protein genes in ageing transgenic mice
Authors: Bowman Barbara H. , Yang Funmei , Adrian Gwendolyn S. 
Published: February 2005

AbstractIntroduction of human plasma protein genes into the mouse genome to produce transgenic mice furnishes an in vivo model for correlating chromosomal DNA sequences with developmental and tissue‐specific expression. The liver produces an array of plasma proteins that circulate throughout the body contributing to homeostasis. Non‐hepatic tissue sites of synthesis have been identified where a local provision of plasma proteins in needed. Analysis of expression of human plasma protein genes in ageing transgenic mice appears especialy promising in identifying DNA sequences that respond to environmental adversities such as inflammatory factors, hormonal changes and metal toxicity. The results indicate that human genes encoding and controlling liver plasma proteins serve as useful models for studying genetic regulation in the background of development and ageing.
Cellular and genetic responses to mesoderm induction in Xenopus
Authors: Hopwood N. D. 
Published: February 2005

AbstractMesodermal cell differentiation begins in response to an inductive interaction early in frog development. In parallel with the recent finding that certain peptide growth factors can induce mesoderm, early cellular and genetic responses to the induction have been discovered. I review here recent work on these responses, work that aims to understand how cells respond to inducers to form the complex pattern of the vertebrate mesoderm.
The endoplasmic reticulum and calcium storage
Authors: Koch Gordon L. E. 
Published: February 2005

AbstractCalcium storage is one of the functions commonly attributed to the endoplasmic reticulum (ER) in non‐muscle cells. Several recent studies have added support to this concept. Analysis of reticuloplasm, the luminal ER content, has shown that it contains several proteins (reticuloplasmins) which are prospective calcium storage proteins. One of these, calreticulin, is also present in the sarcoplasmic reticulum (SR). In sea urchin eggs, a calsequestrin‐like protein has been clearly localised to the ER. The recent demonstration that the IP3 receptor, which has similarities with the calcium release channel in the SR is also localised in the ER membrane suggests that calcium stored in the ER is important for intracellular signalling. The alternative view, that the physiologically important calcium store is a specialised organelle, the calciosome, is not supported by these observations. Recent evidence also suggests that ER calcium might be important in ER structure and in the retention of the luminal ER proteins.
The cellular and molecular events of central nervous system remyelination
Authors: Dubois‐Dalcq Monique , Armstrong Regina 
Published: February 2005

AbstractCentral nervous system (CNS)Abbreviations: CNS=central nervous system; PNS=peripheral nervous system; MS=multiple sclerosis; MBP=myelin basic protein; MHC=major histocompatibility complex; EAE=experimental allergic encephalomyelitis; O‐2A=oligodendrocyte‐type 2 astrocyte; GC=galactocerebroside; GFAP=glial fibrillary acidic protein; FGF=fibroblast growth factor; IGF1=insulin‐like growth factor.
regeneration is a subject of great interest, particularly in diseases causing a dramatic loss of neurons. However, some CNS diseases do not affect neurons but damage other cells, such as the myelin‐forming cells — called oligodendrocytes — which are also crucial to the harmonious function of the nervous system. Diseases in which oligodendrocytes and myelin are attacked can cause devastating neurological dysfunction which is sometimes followed by recovery and myelin repair or remyelination. The question of the regeneration potential of oligodendrocytes in experimental and human demyelinating diseases such as multiple sclerosis has been debated for a long time. Present evidence suggests that oligodendrocyte precursor cells persist in the adult CNS and that oligodendrocyte regeneration can occur but may be limited by ongoing disease processes. Here we will briefly review recent advances which have broadened our understanding of the cellular and molecular events of CNS remyelination.
Inhibition of tumor angiogenesis as a strategy to circumvent acquired resistance to anti‐cancer therapeutic agents
Authors: Kerbel Robert S. 
Published: February 2005

AbstractCancers have a formidable capacity to develop resistance to a large and diverse array of chemical, biologic, and physical anti‐neoplastic agents. This can be largely traced to the instability of the tumor cell genome, and the resultant ability of tumor cell populations to generate phenotypic variants rapidly. It is therefore argued that anti‐cancer strategies should be directed at eliminating those genetically stable normal diploid cells that are required for the progressive growth of tumors. Micro‐vascular endothelial cells comprising the tumor vasculature represent such a normal cell target. Moreover, specificity for tumor associated vasculature by anti‐cancer agents may be achieved by virtue of the fact that many of the endothelial cells that comprise these blood vessels are in an immature, cycling, and ‘activated’ state, in contrast to the endothelial cells associated with normal tissue and organ blood vessels.
The structure of the mammalian centromere
Authors: Rattner Jerome B. 
Published: February 2005

AbstractThe mammalian centromere is a multifunctional chromosomal domain with a complexity that is reflected in its higher order structure, DNA sequence organization and protein composition. The centromere plays a major role during cell division where it functions as the site for the integration of the chromosome with the mitotic spindle, the site of the mechanochemical motor responsible for the movement of chromosomes and the major and last point of interaction between sister chromatids. Recent studies have focused on characterizing the components of the centromere and establishing their relationship to its function. The following brief review summarizes some selected aspects of this recent work.
Drosophila chorion genes: Cracking the eggshell's secrets
Authors: Orr‐Weaver Terry L. 
Published: February 2005

AbstractThe chorion genes of Drosophila are amplified in response to developmental signals in the follicle cells of the ovary prior to their transcription. Their expression is regulated both temporally and spatially within this tissue. They thus serve as models both for the regulation of DNA replication and of developmental transcription. The regulatory elements for DNA amplification have been delineated. Their analysis reveals that amplification is mediated by several regulatory regions and initiates at defined origins within the chorion cluster. Proteins involved in amplification are being identified both by mutations affecting amplification and by DNA binding studies. Regulatory elements for temporal as well as spatial control of chorion gene, expression have been characterized, and two candidate transcription factor genes have been cloned.
The molecular genetics of α1 antitrypsin deficiency
Authors: Wu Ying , Foreman Richard C. 
Published: February 2005

AbstractThe human serum protein α1‐antitrypsin is the major source of antiprotease activity found in the blood. The protein is synthesised primarily by liver cells but, to a lesser extent, by at least one other cell type. Expression of the gene has provided a paradigm for studies on transcriptional regulation in liver and of tissue‐specific promoter activity. The pleiomorphic nature of the gene has given rise to a variety of α1‐antitrypsin variants some of which are clinically important. These abnormal variants may be poorly synthesised, rapidly degraded or inefficiently secreted; studies on the molecular mechanisms which underly these events are providing interesting insights into the general processes of protein transport and intracellular protein degradation.
Translational control during early development
Authors: Richter Joel D. 
Published: February 2005

AbstractEarly development in many animals is programmed by maternally inherited messenger RNAs. Many of these mRNAs are translationally dormant in immature oocytes, but are recruited onto polysomes during meiotic maturation, fertilization, or early embryogenesis. In contrast, other mRNAs that are translated in oocytes are released from polysomes during these later stages of development. Recent studies have begun to define the cis and trans elements that regulate both translational repression and translational induction of maternal mRNA. The inhibition of translation of some mRNAs during early development is controlled by discrete sequences residing in the 3′ and 5′ untranslated regions, respectively. The translation of other RNAs is due to polyadenylation which, at least in oocytes of the frog Xenopus laevis, is regulated by a U‐rich cytoplasmic polyadenylation element (CPE). Although similar, the CPE sequences of various mRNAs are sufficiently different to be bound by different proteins. Two of these proteins and their interactions are described here.
Growth cones: The mechanism of neurite advance
Authors: Gordon‐Weeks P. R. 
Published: February 2005

AbstractGrowth cones are the highly motile structures found at the tips of growing axons and dendrites (neurites), which extend from neurones, during the development of the nervous system. They function both as detectors and transducers of extrinsic guidance cues and as regions where the neurite cytoskeleton is assembled. Without concerted neurite assembly, advance cannot occur. Assembly of the neurite cytoskeleton in growing neurites chiefly involves microtubule assembly at the growth cone. Some of the factors that may influence microtubule assembly in growth cones are becoming apparent and include posttranslational modification of tubulin itself and microtubule associated proteins, particularly tau and MAP1B.
Fragile X‐linked mental retardation and the difficulties of reverse genetics
Authors: Jordan Bertrand R. 
Published: February 2005

AbstractFragile X‐linked mental retardation is an enigmatic inheritable syndrome in which severe mental retardation, a cytogenetically detectable fragile site at Xq27.3 (FraX) and a number of dysmorphic features are associated. Genetic analysis shows that the mode of inheritance is more complex than a straightforward X‐linked recessive trait and probably involves a two‐step process for which several models have been proposed. Early attempts ‘at cloning the fragile site’ provided several DNA segments lying in its general vicinity, and large scale DNA mapping methods were extensively applied in an effort to generate maps including this region. These efforts were complemented by more focussed methods such as microdissection; together these approaches have now provided a number of DNA segments within a 5cM interval around FraX, and with the help of these new probes the site is indeed being cloned. Unravelling the nature of the sequence(s) responsible for the mental retardation syndrome will probably take some time, however.
Why is mendelian segregation so exact?
Authors: Crow James F. 
Published: February 2005

AbstractThe precise 1:1 segregation of Mendelian heredity is ordinarily taken for granted, yet there are numerous examples of ‘cheating’ genes that perpetuate themselves in the population by biasing the Mendelian process in their favor. One example is the Segregation Distortion system of Drosophila melanogaster, in which the distorting gene causes its homologous chromosome to produce a nonfunctional sperm. This system depends on three closely linked components, whose molecular basis is beginning to be understood.The system is characterized by numerous modifiers changing the degree of distortion. Mathematical theory shows that unlinked modifiers that change the degree of distortion in the direction of Mendelism always increase in the population. This provides a mechanism for removing cheaters and preserving the honesty of the Mendelian gene‐shuffle.
Parallels between development of embryonic and matrix‐induced endochondral bone
Authors: Carrington Jill L. , Reddi A. H. 
Published: February 2005

AbstractEndochondral bone formation can take place in the embryo, during fracture healing, or in postnatal animals after induction by implanted demineralized bone matrix. This matrix‐induced bone formation recapitulates the embryonic sequence of bone formation morphologically and biochemically. The steps in bone formation in both systems include differentiation of cartilage from mesenchyme, cartilage maturation, invasion of the cartilage by blood vessels and marrow precursors, and formation of bone and bone marrow. Recently, bone inductive molecules from demineralized bone matrix have been purified, sequenced and produced as recombinant proteins. While there are similarities between bone development in the embryo and that after induction by these purified molecules, the molecules responsible for bone induction in the embryo have not yet been defined. Because of similarities between the two methods of bone formation, studies of Bone induction by demineralized bone matrix may help to elucidate mechanisms of embryonic bone induction.
Laminin binding proteins
Authors: Mercurio Arthur M. , Shaw Leslie M. 
Published: February 2005

AbstractCells express many proteins that bind to laminin, the major adhesive component of basement membranes. Some of these, specifically integrins, function as transmembrane receptors that ‘signal’ the presence of laminin on the cell surface to the cytoplasm. Lectins constitute a second class of laminin binding proteins that may augment integrin function by interacting with laminin carbohydrate. Caution must be used in ascribing functions to other laminin binding proteins, especially cytosolic proteins.
Intercommunication between mammalian oocytes and companion somatic cells
Authors: Eppig John J. 
Published: February 2005

AbstractCellular interactions in the mammalian ovarian follicle between its germ‐line and somatic cell components are crucial for its development and function. These interactions are mediated by both membrane gap junctions and paracrine factors. Somatic cell‐to‐oocyte communication is essential for oocyte growth and the regulation of meiotic maturation. In particular, granulosa cells provide nutrients and molecular signals that regulate oocyte development. Oocytes, on the other hand, promote the organization of the follicle, the proliferation of granulosa cells, and the differentiation and function of cumulus cells, a subset of granulosa cells. Determining the nature of the oocyte‐to‐granulosa cell signals remains a key challenge for future work.
Biological activities of oxygenated sterols: Physiological and pathological implications
Authors: Hwang Peter L. 
Published: February 2005

AbstractOxygenated derivatives of cholesterol (oxysterols) are widely distributed in nature, being found in the blood and tissues of animals and man as well as in foodstuff. They exhibit many biological activities which are of potential physiological, pathological or pharmacological importance. Many oxysterols have been found to be potent inhibitors of cholesterol biosynthesis and one or more oxysterols may play a role as the physiologic feedback regulator of cholesterol synthesis. Oxysterols also inhibit cell replication and have cytotoxic properties effects which suggest that these sterols may participate in the regulation of cell proliferation and may be potentially useful as therapeutic agents for cancer. Furthermore, there is considerable evidence that oxysterols may be involved in the pathogenesis of atherosclerosis. Although the mechanism of action of oxysterols in all these instances is not well understood, the existence of cytosolic and microsomal proteins which bind oxysterols with high affinity and specificity suggests that this group of compounds may represent a family of intracellular regulatory molecules.
Altered cellular responsiveness during ageing
Authors: Rattan Suresh I. S. , Derventzi Anastassia 
Published: February 2005

AbstractThe capacity of cells and organisms to respond to external stimuli and to maintain stability in order to survive decreases progressively during ageing. The mitogenic and stimulatory effects of growth factors, hormones and other agents are reduced significantly during cellular ageing. The sensitivity of ageing cells to toxic agents including antibiotics, phorbol esters, radiations and heat shock increases. This failure of homeostasis during cellular ageing does not appear to be due to any quantitative and qualitative defects in the receptor systems. Instead, metabolic defects in the pathways of macromolecular synthesis may be the basis of altered cellular responsiveness during ageing.
The role of DNA double strand breaks in lonizing radiation‐induced killing of eukaryotic cells
Authors: Lliakis George 
Published: February 2005

AbstractA widely accepted assumption in radiobiology is that ionizing radiation kills cells by inducing forms of damage in DNA structures that lead to the formation of lethal chromosome aberrations. One goal of radiation biology research is the identification of these forms of DNA damage, the characterization of the mechanisms involved in their repair and the elucidation of the processes involved in their transformation to chromosome damage, In recent years, evidence has accumulated implicating DNA double stranded breaks as lesions relevant for cell killing. Here, the available information on this topic is reviewed together with the methods most commonly used to quantitate induction and repair of this type of lesion. The presentation concludes with an outline of present research directions and future goals.
Insect antibacterial proteins: Not just for insects and against bacteria
Authors: Kimbrell Deborah A. 
Published: February 2005

AbstractIn response to a bacterial infection, insects launch an array of countermeasures. Among these are the antibacterial proteins, which effectively lyse bacteria or are bacteriostatic. These proteins were generally assumed to be restricted to insects, yet recent information has shown some homologous counterparts in verte brates, including humans. Recent data have revealed that at least some of these proteins can also act against eukaryotic cells, including human infectious Parasites The latter activities have opened up new possibilities for disease control.
Auxin‐binding proteins and their possible roles in auxin‐mediated plant cell growth
Authors: Jones Alan M. , Prasad Paruchuri V. 
Published: February 2005

AbstractLike several other classes of hormones, the class of plant hormones called auxins exert myriad effects on cell development. While auxins are most noted for inducing cell elongation, they are also involved in cell division, cell differentiation, cell and organ polarity, and wound responsiveness. Consistent with this pleiotropy, is the recent identification of several putative auxin receptors that in theory could represent the primary elements of more than one auxin signal pathway leading to distinct responses or leading in parallel to a single response. Our current working hypothesis is that some auxin‐mediated responses may be mediated by multiple receptors. We describe some of what is known about each of the new putative receptors and elaborate on the hypothesis using the example of cell elongation. Specifically for auxin‐induced elongation, we propose that two rapid events, specific gene transcription and cell wall acidification, are separately mediated by at least two receptors, acting in the nucleus and at the plasma membrane, respectively.