bluuebunny/crossref_metadata_2025 huggingface dataset:
A crystal milestone: The structure of regulated Src
Authors: Superti‐Furga Giulio , Gonfloni Stefania
Published: February 2005

The viral and cellular forms of the Src protein tyrosine kinases take a prototypic role in oncology and signal transduction research, by virtue of being holders of an impressive number of ‘firsts’. Our understanding of the biochemistry and physiology of Src has therefore always been used as a reference for our general advancement in the field of protein phosphorylation and growth control. The recent solution of the crystal structure of two members of the Src family(1,2) represents a milestone in these disciplines and, as usual, provides a general lookout post for developments to come.
Evolution of the multi‐tubulin hypothesis
Authors: Wilson Patricia G. , Borisy Gary G.
Published: February 2005

Microtubules are organized into diverse cellular structures in multicellular organisms. How is such diversity generated? Although highly conserved overall, variable regions within α‐ and β‐tubulins show divergence from other α‐ and β‐tubulins in the same species, but show conservation among different species. Such conservation raises the question of whether diversity in tubulin structure mediates diversity in microtubule organization. Recent studies probing the function of β‐tubulin isotypes in axonemes of insects(1) suggest that tubulin structure, through interactions with extrinsic proteins, can direct the architecture and supramolecular organization of microtubules.
A regulatory switch involving a Clp atpase
Authors: Lazazzera Beth A. , Grossman Alan D.
Published: February 2005

Clp ATPase chaperone proteins are found in procaryotes and eucaryotes. Recently, ClpC of Bacillus subtilis was found to be part of a regulatory switch(1). ClpC, in combination with the MecA and ComS proteins, regulates the activity of a transcription factor, ComK, which is necessary for the development of genetic competence (the ability to bind and take up exogenous DNA). The complex of ClpC:MecA:ComK renders ComK inactive. Interaction between ComS and the ternary complex releases active ComK. This regulatory switch controls ComK activity in response to cell density signals that affect production of ComS. Regulated interaction between Clp ATPases and target proteins might prove to be widespread.
Dorso‐ventral limb polarity and origin of the ridge: On the fringe of independence?
Authors: Zeller Rolf , Duboule Denis
Published: February 2005

Molecular and developmental studies of limb pattern formation have recently gained widespread attention. The fact that vertebrate limbs are amenable to both genetic and embryological manipulations has established this model system as a valuable paradigm for studying vertebrate development. Limb buds are polarised along all three major axes and the establishment of the dorso‐ventral (DV) polarity is dependent upon cues localised in the trunk, where a DV ectodermal interface is produced by confrontation of dorsal and ventral identities. By analogy to Drosophila imaginal disc development, this interface has been proposed to determine and position an ectodermal organising centre, the Apical Ectodermal Ridge (AER), controlling limb bud outgrowth. Recent fate mapping studies(1) and studies of genes regulating DV limb polarity(2‐6), AER formation(7,8) and differentiation(9) suggest, however, that DV patterning and AER induction, though coordinately regulated during limb bud outgrowth, may early on be more dissociated than expected.
A telomerase mutant defective in sister chromatid separation at mitosis
Authors: Nakaseko Yukinobu , Yanagida Mitsuhiro
Published: February 2005

The telomere is a functional domain of the chromosome, located at the extreme ends, and is essential for normal chromosome stability. Chromosomes lacking telomeres are inherited improperly, and mutations in the telomeric repeat sequences are thought to lead to senescence and possibly to cancer. The molecular mechanisms maintaining chromosomes by telomeres, however, have been unclear. Results recently reported by Kirk et al.(1) offer an insight into new telomerase function. They have identified a novel telomerase mutation that blocks sister chromatid separation in mitosis.
The SCL/TAL1 gene: Roles in normal and malignant haematopoiesis
Authors: Robb Lorraine , Begley C. Glenn
Published: February 2005

SCL (TAL1/TCL5) is a member of the helix‐loop‐helix family of transcription factors. Originally identified because of its involvement in a tumour‐specific chromosomal translocation, overexpression of the SCL gene is the most common molecular abnormality found in human T cell leukaemia. Transgenic models have now formally demonstrated that overexpression of SCL within the T cell lineage is capable of causing malignant transformation. Gene targeting experiments have revealed that the SCL gene is crucial for the development of primitive haematopoiesis in the mouse and is also required for the generation of all adult haematopoietic lineages. Biochemical studies have indicated some of the proteins which interact with SCL and this has refined the hypotheses concerning the mechanisms by which SCL plays a role in leukaemogenesis and haematopoietic development.
Why are Hox genes clustered?
Authors: Mann Richard S.
Published: February 2005

The evolutionarily conserved genomic organization of the Hox genes has been a puzzle ever since it was discovered that their order along the chromosome is similar to the order of their functional domains along the antero‐posterior axis. Why has this colinearity been maintained throughout evolution? A close look at regulatory sequences from the mouse Hox clusters(1,2) suggests that enhancer sharing between adjacent Hox genes may be one reason. Moreover, characterizing the activity of one of these mouse enhancers in Drosophila(2) illustrates that despite many similarities, not all Hox clusters are built in the same way.
Epithelial stem cells
Authors: Jones Philip H.
Published: February 2005

New molecular markers for epidermal stem cells have enabled their isolation both in vitro and from the epidermis lying between hair follicles. Micro‐dissection experiments have localised a second population of stem cells within hair follicles. Epidermal stem cells have a patterned distribution in vivo. The patterning can be reconstituted in vitro, showing that it is generated by interactions between keratinocytes and that the differentiation of epidermal stem cells is regulated by signals from other keratinocytes. Recent evidence from transgenic mice suggests that stem cell behaviour in the gut may be regulated by similar cell‐cell interactions in vivo. Candidate genes for mediating these interactions are the homologues of Drosophila cell fate patterning genes such as Notch and Wingless and the Cadherin family of cell‐cell adhesion molecules. The roles of stem cells and of mutations of the Patched gene in epithelial carcinogenesis are discussed.
Regulation of gene expression in developing epidermal epithelia
Authors: Byrne Carolyn
Published: February 2005

Skin is one of the most thoroughly studied epithelia and can be used as a model for transcriptional control of epithelial differentiation. In particular, the stages of epidermal development and differentiation from a simple epithelium are well characterized. Temporal gene expression during development can be used to assign roles for transcription factors in epidermal differentiation. Approaches to understanding transcriptional regulation in epidermis include extensive promoter analysis and expression studies, in some cases coupled to functional studies. This work has not produced any consensus about the importance of any particular factor or class of factors in epidermal specification. There is, as yet, nothing similar to the myo D family of tissue‐specific and cell‐type determining factors in epidermis. These studies, however, have revealed much about control of the differentiation process in epidermis. Most recently, there has been a suggestion that epithelial transcription can be influenced directly by the status of the adhesion complexes at the cell surface, providing a direct link between one of the distinguishing features of the epithelial state and gene transcription.
Epithelial apoptosis
Authors: Metcalfe Anthony , Streuli Charles
Published: February 2005

Apoptosis is an essential part of the normal cellular phenotype repertoire. In the absence of appropriate survival factors, apoptosis is activated through specific signalling cassettes. Epithelia form distinctive three‐dimensional cohesive structures that depend on adhesive interactions in order for these tissues to carry out their specialised roles, such as secretion and reproduction. The cellular programme that triggers apoptosis in epithelial cells has not yet been shown to differ from that in other cell types, yet the unique characteristics of epithelia endow them with specific determinants for survival. In particular, cell‐matrix and cell‐cell interactions are required to prevent entry of epithelial cells into apoptosis, and soluble factors that have profound effects on epithelia, such as steroid hormones or hepatocyte growth factor, also influence their survival. The regenerative capacity of certain epithelia is controlled by intrinsic expression of survival genes within stem cell populations, and may regulate the susceptibility of different epithelial tissues to undergo carcinogenesis.
Problems and paradigms: Morphogens and pattern formation
Authors: Neumann Carl , Cohen Stephen
Published: February 2005

Morphogen gradient theories have enjoyed considerable popularity since the beginning of this century, but conclusive evidence for a role of morphogens in controlling multicellular development has been elusive. Recently, work on three secreted signalling proteins, Activin in Xenopus, and Wingless and Dpp in Drosophila, has stongly suggested that these proteins function as morphogens. In order to define a factor as a morphogen, it is necessary to show firstly, that it has a direct effect on target cells and secondly, that it affects the development of target cells in a concentration‐dependent manner. With these criteria in mind, the evidence available for a variety of proposed morphogens is discussed. While the evidence is not conclusive in most of the cases considered, there is a strong case in favour of the three proteins mentioned above, which suggests that morphogens are potentially of general importance in controlling the development of multicellular organisms.
Molecular evolution of the vertebrate immune system
Authors: Hughes Austin L. , Yeager Meredith
Published: February 2005

Adaptive immunity is unique to the vertebrates, and the molecules involved (including immunoglobulins, T cell receptors and the major histocompatibility complex molecules) seem to have diversified very rapidly early in vertebrate history. Reconstruction of gene phylogenies has yielded insights into the evolutionary origin of a number of molecular systems, including the complement system and the major histocompatibility complex (MHC). These analyses have indicated that the C5 component of complement arose by gene duplication prior to the divergence of C3 and C4, which suggests that the alternative complement pathway was the first to evolve. In the case of the MHC, phylogenetic analysis supports the hypothesis that MHC class II molecules evolved before class I molecules. The fact that the MHC‐linked proteasome components that specifically produce peptides for presentation by class I MHC appear to have originated before the separation of jawed and jawless vertebrates suggests that the MHC itself may have been present at this time. Immmune system gene families have evolved by gene duplication, interlocus recombination and (in some cases) positive Darwinian selection favoring diversity at the amino acid level.
Nuclear calcium and the regulation of the nuclear pore complex
Authors: Perez‐Terzic Carmen , Jaconi Marisa , Clapham David E.
Published: February 2005

In eukaryotic cells the nucleus and its contents are separated from the cytoplasm by the nuclear envelope. Macromolecules, as well as smaller molecules and ions, can cross the nuclear envelope through the nuclear pore complex. Molecules greater than approx. 60 kDa and containing a nuclear localization signal are actively transported across the nuclear membranes, but there has been little evidence for regulatory mechanisms for smaller molecules and ions. Recently, diffusion across the nuclear envelope has been observed to be regulated by nuclear cisternal Ca2+ concentrations. Following depletion of Ca2+ from the nuclear store by inositol 1,4,5‐trisphosphate or Ca2+ chelators, a fluorescent 10 kDa marker molecule was no longer able to enter the nucleus. Distinct conformational states of the nuclear pore complexes depended on the Ca2+ filling state of the nuclear envelope, supporting the assumption that a switch in the conformation of the nuclear pore complex may control the transport of intermediate‐sized molecules across the nuclear envelope. Thus nuclear Ca2+ stores may regulate the conformational state of the nuclear pore complex, and thereby passive diffusion of molecules between the cytosol and the nucleoplasm. The physiological significance of this finding is currently unknown.
Evolution of the spectrin repeat
Authors: Pascual Jaime , Castresana Jose , Saraste Matti
Published: February 2005

We now know that the evolution of multidomain proteins has frequently involved genetic duplication events. These, however, are sometimes difficult to trace because of low sequence similarity between duplicated segments. Spectrin, the major component of the membrane skeleton that provides elasticity to the cell, contains tandemly repeated sequences of 106 amino acid residues. The same repeats are also present in α‐actinin, dystrophin and utrophin. Sequence alignments and phylogenetic trees of these domains allow us to interpret the evolutionary relationship between these proteins, concluding that spectrin evolved from α‐actinin by an elongation process that included two duplications of a block of seven repeats. This analysis shows how a modular protein unit can be used in the evolution of large cytoskeletal structures.
Origin of eukaryotic programmed cell death: A consequence of aerobic metabolism?
Authors: Frade José M. , Michaelidis Theologos M.
Published: February 2005

A marked feature of eukaryotic programmed cell death is an early drop in mitochondrial transmembrane potential. This results from the opening of permeability transition pores, which are composed of adenine nucleotide translocators and mitochondrial porins. The latter share striking similarites with bacterial porins, (including down‐regulation of their pore size by purine nucleotides), suggesting a common origin. The porins of some invasive bacteria play a crucial role during their accommodation inside the host cell and this co‐existence resembles the endosymbiotic origin of mitochondria. The above observations suggest that early in eukaryotic evolution, former invaders may have used porin‐type channels to enter their host and to induce its death when the levels of its cytoplasmic purine nucleotides were dropped. The appearance of adenosine nucleotide translocators in the primitive eukaryotes, which permitted usage of the oxidative metabolism of the invaders, provided the basis for the permeability transition phenomena, now linked to the apoptotic process. Bcl‐2‐type molecules, being able to modulate the permeability transition pores by interaction with adenosine nucleotide translocators, may have played an essential role in conferring a means of controlling apoptosis.
Building a plasmodium: Development in the acellular slime mould Physarum polycephalum
Authors: Bailey Juliet
Published: February 2005

The two vegetative cell types of the acellular slime mould Physarum polycephalum ‐ amoebae and plasmodia ‐ differ greatly in cellular organisation and behaviour as a result of differences in gene expression. The development of uninucleate amoebae into multinucleate, syncytial plasmodia is under the control of the mating‐type locus matA, which is a complex, multi‐functional locus. A key period during plasmodium development is the extended cell cycle, which occurs in the developing uninucleate cell. During this long cell cycle, many of the changes in cellular organisation that accompany development into the multinucleate stage are initiated including, for example, alterations in microtubule organisation. Genes have been identified that show cell‐type specific expression in either amoebae or plasmodia and many of these genes alter their pattern of expression during the extended cell cycle. With the introduction of a DNA transformation system for P. polycephalum, it is now possible to investigate the functions of genes in the vegetative cell types and their roles in the cellular reorganisations accompanying development.
Does sex determination start at conception?
Authors: Erickson Robert P.
Published: February 2005

Recent molecular studies of mammalian sexual determination have been focused on gene expression in the gonadal ridge at the time of appearance of sexual dimorphism: the critical time defined by the ‘Jost principle’. Three lines of evidence suggest that, instead, sex determination may start shortly after conception: (1) the XY preimplantation embryo usually develops more rapidly than the XX preimplantation embryo (this phenotype has been linked to the Y chromosome and will be termed ‘Growth factor Y’); (2) the gene for testis determination, SRY/Sry, and the closely linked genes ZFY/Zfy and Smcy, are transcribed in the preimplantation embryo; and (3) male and female preimplantation embryos are antigenically distinguishable, indicating sex differences in gene expression. The data to support these assertions are reviewed. Possible relationships of these three phenomena to each other and to sex differentiation are discussed. Similarities in mechanisms of sexual determination between marsupial and eutherian mammals are hypothesized. Problems with interpreting male sexual differentiation as being solely due to testosterone and Müllerian inhibiting substance (MIS) are discussed.
Plastids in parasites of humans
Authors: McFadden Geoffrey I. , Waller Ross F.
Published: February 2005

It has recently emerged that malarial, toxoplasmodial and related parasites contain a vestigial plastid (the organelle in which photosynthesis occurs in plants and algae). The function of the plastid in these obligate intracellular parasites has not been established. It seems likely that modern apicomplexans derive from photosynthetic predecessors, which perhaps formed associations with protists and invertebrates and abandoned autotrophy in favour of parasitism. Recognition of a third genetic compartment in these parasites proffers alternative strategies for combating a host of important human and animal diseases. It also poses some fascinating questions about the evolutionary biology of this important group of pathogens.
Biochemistry of molluscan learning and memory
Authors: Nelson Thomas J. , Alkon Daniel L.
Published: February 2005

Studies of learning in marine invertebrates have yielded new information, implicating protein kinase C and calmodulin‐dependent protein kinase as critical components in pathways for learning and memory that are shared with higher vertebrates. Recent advances correlating in vitro biochemical and biophysical measurements with in vivo learning have begun to elaborate the roles in memory storage for these two kinases, their substrates, and signaling proteins such as calexcitin and calmodulin. Other studies have implicated transcription factors associated with kinases such as the cyclic AMP response element binding protein (CREB). These experiments have resulted in a greater understanding of the role of second messengers, principally calcium and cyclic AMP (cAMP), as vehicles for transforming memory‐specific effects occurring at the membrane into permanent DNA‐mediated cellular and structural changes.
An evaluation of what the mouse knockout experiments are telling us about mammalian behaviour
Authors: Keverne Eric B.
Published: February 2005

The early gene knockout studies with a neurobiological focus were directed at fairly obvious target genes and added very little to our knowledge of behavioural neuroscience. On the contrary, since the behavioural consequences were often predictable, this helped confirm that the technology was working. However, a substantial number of knockouts of genes expressed in the brain have been without obvious behavioural consequences, supporting the concept of genetic canalisation and redundancy. Others have produced a behavioural deficit for which there is no obvious explanation. Many cells of different tissue types have a capacity for memory, and in the brain, cells of the hippocampus are important for spatial learning and memory. Deleting genes that are expressed in the happpocampus has received considerable attention in this behavioural context. Although the initial studies experienced problems of interpretation, considerable advances have since been made. Knockout mice are now subject to tests of different forms of learning, multicellular hippocampal recordings, and restricted gene deletion specific to cells of component regions. This multi‐level approach is proving more informative. Nevertheless, there is still a need to recognise that behavioural expression is several steps removed from gene expression, and that the relationship between genes and behaviour can be reciprocal.
Human behavioural genetics of cognitive abilities and disabilities
Authors: Plomin Robert , Craig Ian
Published: February 2005

Although neither the genome nor the environment can be manipulated in research on human behaviour, some of the new tools of molecular genetics can be brought to bear on human behavioural disorders (e.g. cognitive disabilities) and quantitative traits (e.g. cognitive abilities). The inability to manipulate the human genome experimentally has had the positive effect of focusing attention on naturally occuring genetic variation responsible for behavioural differences among individuals in all their complex multifactorial splendour. Genes in such complex multiple‐gene systems are called quantitative trait loci (QTLs), which merge the two worlds of genetic research, quantitative genetics and molecular genetics. Although most genetic research on complex human behaviour has focused on severe mental disorders, cognitive abilities and disabilities may be even more immediately relevant to neuroscience. For example, verbal ability and spatial ability are two of the most heritable cognitive abilities, and reading disability is the first behavioural disability for which replicated QTL linkage has been found. The purpose of this essay is to provide an overview of the genetics of cognitive abilities and disabilities as an example of the impending merger of quantitative genetics and molecular genetics in QTL analysis of complex traits.
Colonic epithelial apoptosis during conventional and endoluminal aortic surgery
Authors: Ghosh J , Khwaja N , Howarth V , Murray D , Murphy M O , Byers R , Walker M G
Published: February 2005

Background

This study characterized the initial modes of colonic mucosal injury during aneurysm surgery and correlated these with proinflammatory cytokine release into the colonic and systemic circulations.

Methods

Twenty-four patients undergoing conventional open aortic aneurysm repair and ten who had endovascular aneurysm repair (EVAR) were recruited. Mucosal biopsies were taken from the sigmoid colon immediately before and after surgery, for histological examination. Inferior mesenteric vein (IMV) and peripheral blood from patients who had conventional surgery was assayed for interleukin (IL) 1β, IL-6 and tumour necrosis factor (TNF) α. Only peripheral blood from patients who had EVAR was assayed.

Results

Conventional aneurysm repair resulted in a threefold increase in columnar epithelial apoptosis. There was a 26-fold increase in IL-6 in IMV blood within 5 min of reperfusion, with an equivalent rise in peripheral blood after 30 min. A 20-fold rise in peripheral blood TNF-α was observed after surgery. Splanchnic IL-6 correlated positively with cross-clamp time and increased apoptosis. No histological changes were seen after EVAR. There were no intraoperative cytokine changes during EVAR, although a postoperative increase in IL-6 and TNF-α was observed.

Conclusion

The lack of columnar epithelial apoptosis following EVAR reflects the relatively minor ischaemic injury incurred during this procedure.
Feasibility, safety, and preliminary efficacy of a novel ePTFE‐covered self‐expanding stent in saphenous vein graft lesions: The Symbiot II trial
Authors: Laarman Gerrit J. , Kiemeneij Ferdinand , Mueller Ralf , Guagliumi Giuglio , Cobaugh Michael , Serruys Patrick W.
Published: February 2005

Compared with percutaneous interventions in native coronary arteries, revascularization of saphenous vein graft (SVG) lesions is associated with increased rates of immediate and long‐term major adverse cardiac events (MACE). The Symbiot II trial was a multicenter prospective study designed to evaluate the feasibility and safety of a novel self‐expanding polytetrafluoroethylene (ePTFE)‐covered stent in the treatment of de novo and restenotic SVG lesions. The primary endpoint was MACE through 30 days postprocedure. Successful Symbiot stent deployment was achieved in 75 of 77 patients (97.4%) with SVG lesions ≤ 35 mm in length (visual assessment). The procedural success rate (defined as < 30% residual stenosis at the target site and no clinical complications) was 83%, and all study device procedures provided grade 3 TIMI flow postprocedure. Within the first 30 days postprocedure, four patients (5.2%) experienced MACE (defined as death, Q‐wave or non‐Q‐wave myocardial infarction, and clinically driven target vessel revascularization), of whom three patients (3.9%) experienced periprocedural non‐Q‐wave myocardial infarction. No subacute stent thrombosis was observed over the 6‐month follow‐up period. No relevant luminal loss at the target site (mean, 0.3 ± 0.9 mm) was observed in the 58 patients (77.3% of enrolled patients) who underwent quantitative coronary angiography at 6 months. The incidences of binary in‐stent restenosis, in‐segment restenosis, and target vessel failure (defined as acute and late‐term MACE through 6 months postprocedure) were low (7.0%, 8.6%, and 14.3%, respectively). The Symbiot self‐expanding ePTFE membrane‐covered stent was associated with a high procedural success rate (97.4%), low incidences of MACE at 30 days (5.2%) and 6 months (14.3%), suggesting that it is safe and effective in the treatment of SVG disease. Catheter Cardiovasc Interv 2005;64:361–368. © 2005 Wiley‐Liss, Inc.
Invasive human magnetic resonance imaging: Feasibility during revascularization in a combined XMR suite
Authors: Dick Alexander J. , Raman Venkatesh K. , Raval Amish N. , Guttman Michael A. , Thompson Richard B. , Ozturk Cengizhan , Peters Dana C. , Stine Annette M. , Wright Victor J. , Schenke William H. , Lederman Robert J.
Published: February 2005

We tested the feasibility and safety of invasive magnetic resonance imaging (MRI) during peripheral angioplasty. Real‐time MRI can image soft tissue and may potentially guide therapeutic procedures without ionizing radiation or nephrotoxic contrast. MRI‐guided diagnostic catheterization has been described recently, but safe and conspicuous catheter devices are not widely available. An active guidewire, which serves as an MRI receiver antenna, might be useful to guide catheterization or even to image atheroma. We describe a combined interventional suite offering both X‐ray fluoroscopy and real‐time MRI. We used a 0.030″ active guidewire receiver coil for invasive MRI after X‐ray lesion traversal in patients undergoing percutaneous iliofemoral artery revascularization. Intravascular MRI was compared with noninvasive MRI, X‐ray angiography, and intravascular ultrasound (IVUS). Seven eligible patients consented to participate, but three were excluded because of lengthy revascularization procedures. Four remaining patients safely underwent combined X‐ray fluoroscopy and real‐time magnetic resonance imaging (XMR) transport, continuous monitoring, and all imaging modalities. There was no device dislodgment, contamination or evidence of heating. The intravascular MRI coil was well visualized except at the tip, but did not provide superior mural imaging compared with IVUS. Therefore, because an adequate safety and workflow experience was obtained, enrollment was terminated after only four subjects. Invasive MRI is feasible and apparently safe during peripheral angioplasty. Patients can safely be transported and monitored in an XMR interventional suite. An active quarter‐wavelength guidewire coil does not provide superior imaging compared with IVUS, but provides satisfactory guidewire visualization. These tools may prove useful for advanced therapeutic procedures in the future. Catheter Cardiovasc Interv 2005;64:265–274. Published 2005 Wiley‐Liss, Inc.
Projections from the spinal trigeminal nucleus to the cochlear nucleus in the rat
Authors: Haenggeli Charles‐André , Pongstaporn Tan , Doucet John R. , Ryugo David K.
Published: February 2005

The integration of information across sensory modalities enables sound to be processed in the context of position, movement, and object identity. Inputs to the granule cell domain (GCD) of the cochlear nucleus have been shown to arise from somatosensory brain stem structures, but the nature of the projection from the spinal trigeminal nucleus is unknown. In the present study, we labeled spinal trigeminal neurons projecting to the cochlear nucleus using the retrograde tracer, Fast Blue, and mapped their distribution. In a second set of experiments, we injected the anterograde tracer biotinylated dextran amine into the spinal trigeminal nucleus and studied the resulting anterograde projections with light and electron microscopy. Spinal trigeminal neurons were distributed primarily inpars caudalisandinterpolarisand provided inputs to the cochlear nucleus. Their axons gave rise to small (1–3 μm in diameter) en passant swellings and terminal boutons in the GCD and deep layers of the dorsal cochlear nucleus. Less frequently, larger (3–15 μm in diameter) lobulated endings known as mossy fibers were distributed within the GCD. Ventrally placed injections had an additional projection into the anteroventral cochlear nucleus, whereas dorsally placed injections had an additional projection into the posteroventral cochlear nucleus. All endings were filled with round synaptic vesicles and formed asymmetric specializations with postsynaptic targets, implying that they are excitatory in nature. The postsynaptic targets of these terminals included dendrites of granule cells. These projections provide a structural substrate for somatosensory information to influence auditory processing at the earliest level of the central auditory pathways. J. Comp. Neurol. 484:191–205, 2005. © 2005 Wiley‐Liss, Inc.
Localization of nitric oxide synthase in the central complex and surrounding midbrain neuropils of the locust Schistocerca gregaria
Authors: Kurylas Angela E. , Ott Swidbert R. , Schachtner Joachim , Elphick Maurice R. , Williams Leslie , Homberg Uwe
Published: February 2005

Nitric oxide (NO), generated enzymatically by NO synthase (NOS), acts as an important signaling molecule in the nervous systems of vertebrates and invertebrates. In insects, NO has been implicated in development and in various aspects of sensory processing. To understand better the contribution of NO signaling to higher level brain functions, we analyzed the distribution of NOS in the midbrain of a model insect species, the locust Schistocerca gregaria, by using NADPH diaphorase (NADPHd) histochemistry after methanol/formalin fixation; results were validated by NOS immunohistochemistry. NADPHd yielded much higher sensitivity and resolution, but otherwise the two techniques resulted in corresponding labeling patterns throughout the brain, except for intense immunostaining but only weak NADPHd staining in median neurosecretory cells. About 470 neuronal cell bodies in the locust midbrain were NADPHd‐positive positive, and nearly all major neuropil centers contained dense, sharply stained arborizations. We report several novel types of NOS‐expressing neurons, including small ocellar interneurons and antennal sensory neurons that bypass the antennal lobe. Highly prominent labeling occurred in the central complex, a brain area involved in sky‐compass orientation, and was analyzed in detail. Innervation by NOS‐expressing fibers was most notable in the central body upper and lower divisions, the lateral accessory lobes, and the noduli. About 170 NADPHd‐positive neurons contributed to this innervation, including five classes of tangential neuron, two systems of pontine neuron, and a system of columnar neurons. The results provide new insights into the neurochemical architecture of the central complex and suggest a prominent role for NO signaling in this brain area. J. Comp. Neurol. 484:206–223, 2005. © 2005 Wiley‐Liss, Inc.
Characterization of Opr deficiency in mouse brain: Subtle defects in dorsomedial telencephalon and medioventral forebrain
Authors: Furushima Kenryo , Murata Takuya , Kiyonari Hiroshi , Aizawa Shinichi
Published: February 2005

Opr/Zic5 is a zinc‐finger gene belonging to, and unique in, the opa/Zic family. Its expression is found in the anterior epiblast and anterior neuroectoderm during gastrulation and early neurulation. Later, we found the expression characteristic in the dorsomedial parts of forebrain and midbrain. However, no defects were apparent in embryonic day 10.5 Opr null mutants, and subtle defects were later found in medial pallium and ventral structures of forebrain, suggesting the compensation of Opr deficiency by its cognate(s). Developmental Dynamics 232:1056–1061, 2005. © 2005 Wiley‐Liss, Inc.
Promoter activity of the retinoic acid receptor gene in the Ciona intestinalis embryo
Authors: Fujiwara Shigeki
Published: February 2005

Retinoic acid regulates development of many chordate‐specific characteristics. The genes encoding retinoic acid receptors (RARs) were isolated only from chordates. In the present study, a genomic DNA fragment containing the promoter region of the RAR gene (Ci‐RAR) in the protochordate Ciona intestinalis was isolated. The transgene containing 1,326 bp of the Ci‐RAR 5′ flanking region was expressed in the epidermis, central nervous system, and muscle. The sequence element necessary for expression in the epidermis seemed to be subdivided into two elements. One was required for activation in the dorsal midline epidermis and the other for the rest of the epidermis. The element responsible for activation in the central nervous system was characterized by putative binding sites for Fox, Ets, and GATA transcription factors. An E‐box sequence was required for the transgene expression in the tail muscle cells. Developmental Dynamics 232:1124–1130, 2005. © 2005 Wiley‐Liss, Inc.
Addition of Carbenes to an Osmium(VI) Nitride Complex
Authors: Leung Chi‐Fai , Wong Tsz‐Wing , Lau Tai‐Chu , Wong Wing‐Tak
Published: February 2005

A series of osmium(VI) nitride complexes containing 8‐quinolinolato ligands, [OsVI(N)(X‐Q)2Cl] (X = H, 5‐Cl, 5‐NO2, 2‐Me; 1a–d), have been synthesized by reaction of HX‐Q with [nBu4N][OsVI(N)Cl4] in the presence of 2,6‐dimethylpyridine. The ν(Os≡N) stretches of these compounds occur at 1056–1075 cm–1, and are within the range (1050–1120 cm–1) found for most osmium nitride species. The structure of 1d has been determined by X‐ray crystallography. The osmium center adopts a distorted octahedral geometry, and the two quinolinolato ligands are cis to each other. The three N atoms are in a facial arrangement, and the Os≡N bond distance is 1.644(6) Å. Complex 1c readily reacts with the carbene precursors bis(1,3‐dialkylimidazolidin‐2‐ylidene) (LR2; R = Me, Et, or CH2Ph) to produce the osmium(IV) azavinylidene species, [OsIV(N=LR)(NO2‐Q)2Cl], which are derived from the formal addition of the carbenes LR to OsVI≡N. The structure of [OsIV(N=LEt)(NO2‐Q)2Cl] (2b) has been determined by X‐ray crystallography. The osmium center has a distorted octahedral geometry in which the facial arrangement of the three N atoms is retained. The Os(1)–N(5) distance of 1.875(6) Å is rather long and, together with the rather acute Os(1)–N(5)–C(19) angle of 133.8(5)°, indicates that there is no significant multiple‐bond character in the Os(1)–N(5) bond. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Oxygen consumption in frog sartorius muscle I. The isometric twitch
Authors: Baskin R. J. , Gaffin S.
Published: February 2005

Direct measurements have shown that the heat output from the frog sartorius muscle stimulated under isometric conditions is maximum when the muscle is at reference length and is decreased at stretched and shortened lengths. Experiments were conducted to determine if oxygen consumption following isometric stimulation varied with length in the same manner as did heat.

A modified version of a differential volumeter was used consisting of two small sealed chambers each containing one of a pair of frog sartorius muscles. In the presence of a CO2 absorbant extra oxygen consumption is indicated by movement of the index drop toward the chamber containing the stimulated muscle.

It was found that at 12°C the oxygen consumption resulting from ten isometric twitches at reference length is 11.93 μ1/g and decreases to 5.10 μ1/g at 0.75 RL and 8.64 μ1/g at 1.25 RL. The absolute value of the oxygen consumption is in agreement with Hill's heat studies using appropriate heat‐oxygen conversion factors. No Feng “stretch response” of an increase in the rate of resting oxygen consumption was observed.

Measurements of developed tension were found to parallel the oxygen consumption and heat curves, being 2.28 kg/cm2 at 1.00 RL and decreasing to 1.45 kg/cm2 at 1.25 RL and approaching zero at 0.75 RL.

At the shortest lengths the oxygen consumption (5.0 μ1/g) is suggested to represent the equivalent of activation heat since no elastic elements were stretched. Such a suggestion is in agreement with heat studies showing that the energy of activation is approximately half of the maximum initial energy liberated in an isometric contraction.
Phosphate incorporation and Na, K‐ATPase activity in human red blood cell ghosts
Authors: Heinz E. , Hoffman J. F.
Published: February 2005

An attempt is described to demonstrate a phosphorylated intermediate correlated with the membrane ATPase reaction in human red cell ghosts. It was found that ghosts incubated with γ‐labeled ATP32 incorporate 400 to 1600 μM P/kg dry weight and that this incorporation required Mg, could be enhanced by the addition of Na and perhaps of strophanthidin but was inhibited by Ca, cooling or heat denaturation. If the total P32 content of ghosts washed with Tris is taken as the Tris‐insoluble fraction, this fraction can be divided, operationally, into the PCA‐insoluble fraction, and the PCA‐soluble fraction‐B. It was found that the PCA‐soluble fraction‐B was composed primarily of unsplit, intact ATP32 (as shown in parallel experiments with C14‐labeled ATP) and some Pi32. The PCA‐insoluble fraction contained only Pi32. If the Pi32 contained in the PCA‐insoluble fraction represents an intermediate in the membrane ATPase, this Pi32 should be exchangeable upon restitution of the ATPase activity. However, this Pi32 was found to be stable and nonexchangeable upon reincubation of prelabeled ghosts under conditions which reactivate the ATPase reaction. Two alternative interpretations were considered: (1) that the P32 that is incorporated into an intermediate product of the ATPase reaction is masked by nonspecific binding of P32 and, (2) that the phosphorylated product is resident in the PCA‐soluble fraction‐B. Further experiments are needed to evaluate these possibilities.
Active transport by the Cecropia midgut. I. Inhibitors, stimulants, and potassium‐transport
Authors: Haskell Judith A. , Clemons Robert D. , Harvey William R.
Published: February 2005

Harvey and Nedergaard ('64 Proc. Nat. Acad. Sci., 51: 757–765) have shown that midguts isolated from mature larvae of the Cecropia silkworm, when perfused in aerated, agitated physiological solution, exhibit a large electrical potential with the lumen‐side positive to the blood‐side. Isotope studies show that potassium carries 83% of the current generated by the midgut when the potential is shortcircuited. These and other data demonstrate that potassium is actively transported from blood‐side to lumen‐side of the midgut epithelium. Neither the potential nor the current requires sodium.

The effects of various chemicals on this sodium‐independent active transport of potassium were examined. The short‐circuit current was rapidly and reversibly inhibited by anoxia and 2,4‐dinitrophenol. An irreversible inhibition was effected by iodoacetate. No observable change was produced by cholinesterase inhibitors, adrenalin, pituitary hormones or small changes in pH. Ouabain, a cardiac glycoside which is thought to be a specific inhibitor of sodium transport, was without effect at concentrations as high as 10−4 M.

Barely affected by 5% CO2, the current was strongly and reversibly depressed by 25% CO2. The carbonic anhydrase inhibitor hygroton at 10−3 M was without effect, but the related sulfonamide cardrase caused 36% inhibition at this concentration. The sulfonamides are barely soluble in water and perhaps penetrate the midgut cells with difficulty. Another type of carbonic anhydrase inhibitor, sodium sulfide, caused reversible inhibitions of 31% at 10−4M and 87% at 10−3 M respectively. Clearly the potassium transporting system of Hyalophora cecropia has important differences from sodium systems, and possibly employs a potassium, hydrogen ion‐linked pump.
SV40‐induced transformation of human diploid cells: Crisis and recovery
Authors: Girardi A. J. , Jensen F. C. , Koprowski H.
Published: February 2005

Nineteen cultures of human embryonic or adult‐tissue cells were exposed to SV40 as primary cultures or developed cell strains in Phase II of cultural life; 12 cultures were exposed to virus in Phase III, at the end of in vitro life. After the expected proliferative response, infected cultures exhibited morphological change, accelerated growth, and prolongation of propagability. After an average of 22.6 weeks for cultures infected as primary explants or in Phase II, the proliferative stage of transformation ended in a stage of “crisis.” Crisis was characterized by progressive decline in vigor of culture proliferation, increasingly abnormal cell division, and limitation in propagability of cells eventually resulting in diminution in cell number. Cytological features of crisis included detachment of cells and appearance of multinucleated and giant cells. Temporally and cytologically, crisis was similar for transformed cells whether of adult or embryonic origin, whether derived from skin, buccal mucosa or lung, whether in Phase II or III of culture life at the time of infection (the “older” cultures entering crisis sooner than the “younger”), and whether propagated continuously or with intervening periods of growth arrest or proliferation in vivo. After a variable time “recovery” of cultures from crisis occurred by repopulation from small groups of surviving but seemingly dormant cells. The new populations, always obtained with care of cultures in crisis, formed continuously propagable cell lines. Control uninfected cultures have always exhibited the finite life terminating in Phase III which is characteristic of human diploid cell strains. Passage of transformed cultures through crisis and recovery was accompanied by loss of capacity to release infectious SV40 and enhancement of production of SV40‐induced complement‐fixing antigen.
Separation of rabbit red cells by density methods and characteristics of separated layers
Authors: Prentice Theodore C. , Bishop Charles
Published: February 2005

Red cells from rabbits (reticulocyte count 1–2%) injected 4–6 days previously with Fe59 were centrifuged in isotonic hypodense media (plasma, buffer, saline) for 30 minutes at 1,600 G and layers were removed to achieve density fractionation. An important criterion of separation was the fractionation ratio (specific activity of hemoglobin in any layer/specific activity of hemoglobin in unfractionated blood) which indicated whether a layer contained mainly “new” or “old” red cells. The most important factor in enhancing the fractionation ratio was the centrifugal force, but time also had an effect. All isotonic media were essentially equivalent, but hypertonic media (sucrose) were quite poor. Dextran and PVP were also not good in promoting density separation. The exact degree of separation achieved by various combinations of conditions is documented, but no system achieves a true equilibrium, as shown by the fact that refractionation can split any fraction into subfractions of higher and lower hemoglobin specific activity. Upper layers were characterized by greater cell size, more reticulocytes, more free cholesterol, phospholipid, and ATP, and a faster rate of glycolysis. The distribution of Fe59 in the fractionated blood was followed serially for up to ten weeks, the most homogeneous distribution being seen only in the first week or two. After that the Fe59 was not sharply restricted to any density fraction. This suggested that the most significant density change takes place as the reticulocyte matures.
Puff development and DNA synthesis in Sciara salivary gland chromosomes in tissue culture
Authors: Cannon Grace B.
Published: February 2005

A method for the tissue culture of salivary glands of Sciara coprophila in a chemically defined medium is presented. When the chromosomes of the posterior lobe of the gland have puffs and the chromosomes of the anterior lobe do not have puffs prior to culture, puffs will develop in the anterior lobe chromosomes within a 24 hour culture period. When these chromosome II puffs are at their largest, fully extended state and a bulb on chromosome III is in a larva nearing pupation, the puffs and bulb become condensed in culture more rapidly than in normal development. This condensed state of the chromatin is thought to be heterochromatin. The uptake of tritiated thymidine was compared in homologous glands of 20 larvae in six different stages of development and all glands were labeled before and after culture, indicating that the culture method does not interfere with DNA synthesis.
Discontinuous decay of the action potential of the rat gastrocnemius as recorded from an intracellular location
Authors: Locke Simeon , Brown Paul B.
Published: February 2005

Fractionation of intracellular action potential has been observed, with (1) an initial graded decline of amplitude and appearance of a notch; (2) a progressive delay and eventual disappearance of a component, with a stepwise decrease in area, and (3) the occasional sequential disappearance of as many as three components of the same order of magnitude in area and amplitude.

The possibilities of block, movement, or extracellularly recorded responses as cause for these physiological “quanta” have been reviewed. One possible hypothesis is the existence of “patches” of membrane with independent characteristics of excitability and responsivity, which become manifest as a result of damage inflected by the electrode.