bluuebunny/crossref_metadata_2025_split huggingface dataset:
Termination of vitellogenesis in follicles of the moth, Plodia interpunctella: Changes in oocyte and follicular epithelial cell activities
Authors: Zimowska Grażyna , Shirk Paul D. , Silhacek Donald L. , Shaaya Eli 
Published: February 2005

AbstractThe production and uptake of the follicular epithelium yolk protein (FEYP) is terminated coincident with the initiation of vitelline membrane synthesis in follicles of the Indianmeal moth, Plodia interpunctella (Hübner). This was determined by visualizing the cytolocalization of the FEYP subunits YP2 and YP4 using antisera to immunolabel ultrathin sections or whole‐mounted ovaries. Both subunits of FEYP were detectable in the Golgi apparatus and associated secretory granules of the follicular epithelial cells (FC) in vitellogenic follicles. Before the follicles entered the terminal growth phase, the oocytes began production of specialized organelles, late yolk spheres. Following the appearance of late yolk spheres in the oocyte, the FC initiated the production of vitelline membrane proteins and the rapid clearance of YP2 from their cytoplasm. No YP2 was detected in the Golgi apparatus or in the secretory granules of FC from follicles in terminal growth phase, although YP4 was detected in these organelles. The vitelline membrane of follicles in termal growth phase was a bilayered structure with an electron‐dense layer of vitelline membrane proteins that originated in the FC and an electron‐translucent layer containing yolk proteins. During this period, late yolk spheres were observed fused with the oolemma exposing and possibly releasing their contents to the electron‐translucent layer of the vitelline membrane. From this evidence, we suggest that during termination of vitellogenesis, the oocyte and FC work in concert to end uptake of yolk proteins and begin the synthesis of egg membranes, and that the oocyte contributes to the production of vitelline membrane by the release of previously sequestered yolk proteins. © 1995 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Multicellular‐vesicle‐promoting polypeptide from Trichoplusia ni: Tissue distribution and N‐terminal sequence
Authors: Ferkovich Stephen M. , Miller Stephen G. , Oberlander Herbert 
Published: February 2005

AbstractAn N‐terminal amino acid sequence of a 16.9 kDa hemolymph polypeptide, “Vesicle Promoting Factor” (VPF) from Trichoplusia ni, revealed a high sequence homology (70%) with Manduca sexta apolipophorin‐III. A polyclonal antibody developed against VPF, however, was not immunoreactive with either purified M. sexta or T. ni apolipophorin‐III. Immunoblots of tissue homogenates of T. ni indicated that VPF was present in imaginal wing discs, central nervous system (CNS), silk glands, midgut and hemocytes from fifth instar larvae, and also in the IAL‐TND1 cell line which can grow as either fluid‐filled multicellular vesicles or multicellular aggregates. VPF was also detected immunologically in the hemolymph of adults of T. ni, and in hemolymph of adults and larvae of Galleria mellonella and Heliothis virescens. Testes, midgut, hemocytes, and wing discs, but not Malpighian tubules, of T. ni released VPF into tissue culture medium during a 3 h incubation period. © 1995 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Identification, characterization, and developmental profile of a high molecular weight, juvenile hormone‐binding protein in the hemolymph of the migratory grasshopper, Melanoplus sanguinipes
Authors: Ismail Sheikh M. , Gillott Cedric 
Published: February 2005

AbstractIn the hemolymph of Melanoplus sanguinipes, a high molecular weight juvenile hormone binding protein (JHBP) was identified by photoaffinity labelling and found to have a Mr of 480,000. The JHBP, purified using native gel electrophoresis followed by electroelution, has an equilibrium dissociation constant for JH III of 2.1 nM and preferentially binds JH III over JH I. Antibody raised against JHBP recognized only the 480,000 band. Under denaturing conditions the native JHBP gave a single band with a Mr 78,000. The antibody against native JHBP recognized only the 78,000 protein in SDS‐treated hemolymph samples, indicating that JHBP is a hexamer in this species. The concentration of JHBP fluctuates in both the sexes during nymphal and adult development in parallel with total protein content of hemolymph. © 1995 Wiley‐Liss, Inc.
Hormonal regulation of sex pheromone biosynthesis in the turnip moth, Agrotis segetum
Authors: Zhu Junwei , Millar Jocelyn , Löfstedt Christer 
Published: February 2005

AbstractPheromone production in the female turnip moth, Agrotis segetum, is under the control of a brain factor. This factor was demonstrated to be a proteinaceous substance termed pheromone biosynthesis activating neuropeptide‐like substance (PBAN‐like substance). The sex pheromone of Swedish A. segetum includes (Z)‐5‐decenyl acetate, (Z)‐7‐dodecenyl acetate, and (Z)‐9‐tetradecenyl acetate as major components. Decapitation of a female decreased pheromone production significantly. Pheromone production was restored by injection of homogenates of either male or female brain‐suboesophageal ganglion or the corpora cardiaca alone. Pheromonotropic activity was also found in homogenates of the female thoracic ganglion and abdominal ganglion that were obtained during scotophase. Injection of female brain and thoracic ganglion homogenates made from insects during the scotophase induced two and four times as much Z7‐12:OAc, respectively, as injection with similar homogenates from photophase. As little as one‐eighth female equivalent (FE) brain homogenate was sufficient to increase the amount of Z7‐12:OAc. The effect of brain homogenate on pheromone titer reached its maximum after 30 min. The activity of the PBAN‐like substance present in female brain extracts was not correlated to the age of the donor. Injection of hemolymph collected during either photophase or scotophase into decapitated females did not increase the pheromone titer. The target site of the PBAN‐like substance was not the pheromone gland, and the ventral nerve cord was not involved in the transportation of the PBAN‐like substance, which implies a mode of action different from what has been reported in other moths. Brain homogenates obtained during photophase from females of African A. segetum, Spodoptera littoralis, or Ostrinia nubilalis as well as synthetic Bombyx‐PBAN also induced pheromone production in decapitated Swedish female A. segetum. © 1995 Wiley‐Liss, Inc.
Genetic and molecular studies of apterous: A gene implicated in the juvenile hormone system of Drosophila
Authors: Shtorch Atalia , Werczberger Ruth , Segal Daniel 
Published: February 2005

AbstractThe apterous (ap) gene in Drosophila melanogaster encodes a homeodomain transcription factor. It is required for the development of the wings and of a subset of embryonic muscles. The gene has been implicated in the juvenile hormone (JH) system because mutations in ap lead to JH deficiency, and are associated with defective histolysis of the larval fat body, arrested vitellogenesis, sterility, and aberrant sexual behavior, all of which are dependent on JH.We describe here the use of hemizygotes and germ‐line clones, of X‐ray‐and hybrid dysgenesis‐induced lethal ap alleles to determine the primary role of the gene during development. We find that ap lethality is polyphasic, but occurs primarily at the larval and pupal stages. The lethal phenotype is not associated with any overt morphological abnormality, suggesting that death occurs from a systemic malfunction. Strong interallelic complementation for the wing phenotype was found between some ap mutations induced by hybrid‐dysgenesis. By Northern blot analysis, we demonstrate an increase in ap expression in pupae and adults as compared to embryos and larvae, suggesting that it is developmentally regulated. Finally, primer extension is used to determine the transcription start site of the gene. © 1995 Wiley‐Liss, Inc.
Uses of vaccinia virus as a vector for the production of live recombinant vaccines
Authors: Smith Geoffrey L. , Moss Bernard 
Published: February 2005

AbstractVaccinia virus, the world's oldest vaccine, was used originally for the eradication of smallpox. It is now being genetically engineered to create new live vaccines for use against other infectious agents of medical and veterinary importance. Genes coding for antigens of several pathogens have been linked to vaccinia virus transcriptional regulatory signals and inserted into the vaccinia virus genome. The resultant recombinant viruses are infectious, express the foreign gene, stimulate specific immune responses in vaccinated animals and can protect against disease caused by the corresponding pathogen.
Newly discovered activities for calcitriol (1,25‐dihydroxyvitamin D3): Implications for future pharmacological use
Authors: Simpson Robert U. , Weishaar Ronald 
Published: February 2005

AbstractRecent studies have yielded new insights into the critical importance of adequate vitamin D3 intake and metabolism. Investigations of the actions of 1,25‐dihydroxyvitamin D3 (calcitriol) on novel target tissues has revealed that this hormone has functions other than its recognized action in regulating blood calcium and phosphate levels. Reports have characterized calcitriol receptors and activities in organs and tissues as diverse as pancreas, skeletal and heart muscle, blood cells, brain, skin, pituitary, parathyroid, kidney, bone and intestine. These studies suggest functions for calcitriol as varied as the regulation of insulin and prolactin secretion, muscle contractility, immune cell metabolism, melanin synthesis and differentiation of blood cells. This information may ultimately help us to understand the etiologies of several kinds of organ dysfunction and lead to the development of tissue‐specific agents for new therapies.
Molecular biology of T‐cell‐derived lymphokines: A model system for proliferation and differentiation of hemopoietic cells
Authors: Arai K. , Yokota T. , Miyajima A. , Arai N. , Lee F. 
Published: February 2005

AbstractMany lymphokine genes have now been cloned from activated T cells and their products have been expressed in mammalian cells. Use of these recombinant lymphokines has provided the opportunity to evaluate both the spectrum of their biological activities and the mechanisms of their action in promoting proliferation and differentiation of hemopoietic and lymphoid cells. Characterization of the structure of lymphokine genes will provide information about their regulated expression in T‐cell activation.
Mechanisms underlying induction and maintenance of long‐term potentiation in the hippocampus
Authors: Lynch M. A. 
Published: February 2005

AbstractLong‐term potentiation (LTP) in the hippocampus is accompanied by a number of changes on both sides of the synapse. It is now generally considered that the trigger for initiating LTP is the entry of calcium into the postsynaptic area through the NMDA‐associated channel while the mechanism(s) underlying the maintenance of LTP are less well understood and probably involve contributions from both sides of the synapse.
Molecular insights into breast cancer from transgenic mouse models
Authors: Dickson Robert B. , Gottardis Macro M. , Merlino Glenn T. 
Published: February 2005

AbstractWe desperately need to know more of the biological details of the onset and progression of breast cancer. The disease is of startlingly high incidence (approaching 1 in 9 women), our current therapies for the disease are inadequate once it has metastasized, and the disease is characterized by excessive morbidity and mortality.Most of the growth and differentiation of the mammary gland occurs relatively late in life: during sexual maturation, and then cyclically during pregnancy and lactation. Normal as well as malignant growth is regulated by endocrine hormones as well as by local tissue factors, such as polypeptide growth factors, Cancer seems to progress as hyperplastic ductal or lobular epithelial growth, acquiring progressive genetic changes (including those of oncogenes and tumor suppressor genes) leading to clonal outgrowths of progressively more malignant cells. The nature of proliferative controls and the relevant genetic changes are the subjects of the current review.
Evolution of the vertebrate Hox homeobox genes
Authors: Krumlauf Robb 
Published: February 2005

AbstractOne of the most remarkable recent findings in developmental biology has been the colinear and homologous relationships shared between the Drosophila HOM‐C and vertebrate Hox homeobox gene complexes. These relationships pose the question of the functional significance of colinearity and its molecular basis. While there was much initial resistance to the validity of this comparison, it now appears the Hox/HOM homology reflects a broad degree of evolutionary conservation which has reawakened interest in comparative embryology and evolution.The evolutionary conservation of protein motifs in many gene families (including those for growth factors, secreted and membrane bound signalling factors, adhesion molecules, cytoplasmic receptor kinases, nuclear receptors and transcription factors) has lead to speculation on the extent to which these homology relationships represent common developmental processes and underlying molecular mechanisms. Structural identities in a protein may indicate the biochemical/molecular function that a protein plays in cellular and developmental processes, without reflecting a conserved role in a cascade of developmental events. However, the analysis of genes encoding transcription factors has provided evidence suggesting that there are gene complexes in arthropods and vertebrates which are true homologues and which may share common roles in the specification of regional identity along embryonic A‐P axis. These genes comprise the Box/HOM‐C homeotic complexes. This review will detail some of the evidence for this proposed relationship and will speculate on the functional implications.
Meiosis, mitosis and microtubule motors
Authors: Sawin Kenneth E. , Endow Sharyn A. 
Published: February 2005

AbstractA framework for understanding the complex movements of mitosis and meiosis has been provided by the recent discovery of microtubule motor proteins, required for the proper distribution of chromosomes or the structural integrity of the mitotic or meiotic spindle. Although overall features of mitosis and meiosis are often assumed to be similar in mechanism, it is now clear that they differ in several important aspects. These include spindle structure and assembly, and timing of chromosome segregation to opposite poles. Here we review progress in the functional characterization of several newly identified microtubule motor proteins, emphasizing their possible roles in spindle structure and function.
Differential repair of excision gaps generated by transposable elements of the ‘Ac family’
Authors: Rommens Caius M. T. , Van Haaren Mark J. J. , Nijkamp H. John J. , Hille Jacques 
Published: February 2005

AbstractStudies on transposable elements of the Ac family have led to different models for excision gap repair in either plants or Drosophila. Excision products generated by the plant transposable elements Ac and Tam3 imply a more or less straightforward ligation of broken ends; excision products of the Drosophila P element indicate the involvement of ‘double‐strand break’ (DSB) repair. Recent findings that excision products of Ac and Tam3 can also contain traces of the element ends indicate, however, that DSB repair might be an alternative repair mechanism in plants. A functional DSB repair mechanism in plants can also be deduced from the observed rapid increases of Ac copy number during plant development and from the involvement of Ac in the generation of internal Ac deletions. On the other hand, alternative repair mechanisms may also be functional in Drosophila, because some of the ‘footprints’ generated upon P excision can be explained by a mechanism that has been postulated for excision gap repair in plants. It is concluded that plants and Drosophila can use similar repair mechanisms, but that the predominance of a certain repair mechanism is determined by the host.
Multi‐allelic self‐incompatibility polymorphisms in plants
Authors: Charlesworth Deborah 
Published: February 2005

AbstractThe multi‐allelic self‐incompatibility polymorphisms in angiosperms have long interested geneticists and population geneticists, but the limits of classical genetic resolution were reached many years ago. In recent years, new progress has been made by molecular genetic approaches. Intriguing similarities to and differences from the fungal systems are emerging. The polymorphism at these loci is now known to be even more baroque than appeared from classical genetic studies. Alleles differ so much at the level of both the DNA and protein sequence that they would be difficult to recognise as products of the same locus, were it not for the presence of certain conserved regions. Despite the successes of the recent work, the locus responsible for the specificity of the incompatibility reaction in pollen, and the mechanism of self‐incompatibility, remain elusive.
The role of thymidylate synthase as an RNA binding protein
Authors: Chu Edward , Allegra Carmen J. 
Published: February 2005

AbstractThymidylate synthase plays a central role in the biosynthesis of thymidylate, an essential precursor for DNA biosynthesis. In addition to its role in catalysis and cellular metabolism, it is now appreciated that thymidylate synthase functons as an RNA binding protein. Specifically, thymidylate synthase binds with high affinity to its own mRNA, resulting in translational repression. An extensive series of experiments has been performed to elucidate the molecular elements underlying the interaction between thymidylate synthase and its own mRNA. In addition to characterization of the underlying cis‐ and trans‐acting elements, recent studies have shown that thymidylate synthase has the capacity to bind specifically to other cellular RNA species. While the biological significance of these other RNA/thymidylate synthase interactions remains to be defined, this work suggests a potential role for TS in coordinately regulating several critical aspects of cellular metabolism.
The role of chromosome ends during meiosis inCaenorhabditis elegans
Authors: Wicky Chantal , Rose Ann M. 
Published: February 2005

AbstractChromosome ends have been implicated in the meiotic processes of the nematodeCaenorhabditis elegans. Cytological observations have shown that chromosome ends attach to the nuclear membrane and adopt kinetochore functions. In this organism, centromeric activity is highly regulated, switching from multiple spindle attachments all along the chromosome during mitotic division to a single attachment during meiosis.C. eleganschromosomes are functionally monocentric during meiosis. Earlier genetic studies demonstrated that the terminal regions of the chromosomes are not equivalent in their meiotic potentials. There are asymmetries in the abilities of the ends to recombine when duplicated or deleted. In addition, mutations in single genes have been identified that mimic the meiotic effects of a terminal truncation of the X chromosome. The recent cloning and characterization of theC. eleganstelomeres has provided a starting point for the study of chromosomal elements mediating the meiotic process.
The biogenesis of lysosomes: Is it a kiss and run, continuous fusion and fission process?
Authors: Storrie Brian , Desjardins Michel 
Published: February 2005

AbstractMolecules are transferred to lysosomes, the major, acid pH, digestive compartment in eukaryotic cells, by a complex series of pathways that converge at a late endosome/prelysosomal compartment. Here, we discuss the relationship between this compartment and the lysosome. We propose that lysosomes are maintained within cells by a repeated series of kiss and run, transient fusion and fission processes with the late endosome/prelysosome compartment. Directionality to these processes may be conferred by pH gradients and retrieval mechanisms. The future challenge in testing this and any other proposed hypothesis for lysosomal biogenesis will be the establishment of molecular mechanisms.
The vagaries of variegating transgenes
Authors: Martin David I. K. , Whitelaw Emma 
Published: February 2005

AbstractExpression of transgenes in mice, when examined with assays that can distinguish individual cells, is often found to be heterocellular, or variegated. Line‐to‐line variations in expression of a transgene may be due largely to differences in the proportion of cells in which it is expressed. Variegated silencing by centromeric heterochromatin is well described, but other factors may also affect transgene silencing in mice. Tandem arrays of transgenes themselves form heterochromatin, and some cell lineages may tend to silence transgenes because of extensive facultative heterochromatin in their nuclei. The cis‐acting transcriptional control elements within a transgene inhibit silencing, and strainspecific differences in chromatin proteins may strongly influence the extent of variegation. The accessibility of multiple differentiated cell lineages in mice suggests that they may provide a tool for dissecting the role of chromatin‐mediated silencing in cell differentiation and tissue‐specific gene expression.
Drosophila Hox complex downstream targets and the function of homeotic genes
Authors: Graba Yacine , Aragnol Denise , Pradel Jacques 
Published: February 2005

AbstractHox complex genes are key developmental regulators highly conserved throughout evolution. The encoded proteins share a 60‐amino‐acid DNA‐binding motif, the homeodomain, and function as transcription factors to control axial patterning. An important question concerns the nature and function of genes acting downstream of Hox proteins. This review focuses on Drosophila, as little is known about this question in other organisms. The noticeable progress gained in the field during the past few years has significantly improved our current understanding of how Hox genes control diversified morphogenesis. Here we summarise the strategies deployed to identify Hox target genes and discuss how their function contributes to pattern formation and morphogenesis. The regulation of target genes is also considered with special emphasis on the mechanisms underlying the specificity of action of Hox proteins in the whole animal.