bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postnatal growth and reproductive biology of Rhinolophus hipposideros (Chiroptera: Rhinolophidae)
Authors: Reiter Guido 
Published: February 2004

AbstractThe timing of birth and postnatal growth in lesser horseshoe bats Rhinolophus hipposideros were studied during 2000 and 2001 at three maternity roosts located in the provinces of Carinthia and Salzburg, Austria. Postnatal growth curves for length of forearm and body mass were determined separately for the different colonies and years. Cooler weather during June 2001 coincided with a median birth date that was 8 days later than in 2000, whilst the difference between colonies was 4 and 5 days, respectively, for the pooled data of both years. Cool temperatures in June also coincided with a longer duration of the parturition period. Postnatal growth rates were higher than in most other bat species but differences between years and colonies were considerable. These differences may be attributed to the ambient roost temperatures, whereby the young of two cooler roosts showed significantly reduced growth rate during 8 days of cool weather in 2000. Moreover, later born and therefore smaller pups were more strongly affected by low temperatures than earlier born and larger ones. The mean length of forearm of young lesser horseshoe bats at the beginning of September equalled that of adult bats, whilst their body mass was still lower. Non‐volant juveniles did not cluster following the nightly emergence of adult females, and a preferred location within the roosts could not be identified. High and very low roost temperatures, however, did have an influence on the location of non‐volant young in the colonies.
PCR‐RFLP identification of mustelid species: European mink (Mustela lutreola), American mink (M. vison) and polecat (M. putorius) by analysis of excremental DNA
Authors: Gómez‐Moliner B. J. , Cabria M. T. , Rubines J. , Garin I. , Madeira M. J. , Elejalde A. , Aihartza J. , Fournier P. , Palazón S. 
Published: February 2004

AbstractRecent advances in molecular scatology have allowed the development of reliable and non‐invasive methods that can be applied in monitoring of small carnivores, without disturbance of the animals. Here a method is described that can be used to differentiate European mink Mustela lutreola, polecat M. putorius and American mink M. vison based on the analysis of DNA extracted from faeces. It consists of a nested PCR of a region of the mitochondrial D‐loop followed by digestion of the resulting 240 bp amplicons with the restriction enzymes RsaI and MspI. The restriction patterns of both enzymes, when used together, are found to detect species‐specific sequence variation. Two different haplotypes for European mink (AA, AB), another two for the polecat (AC, AD) and one for American mink (BC) can also be discriminated by this technique. Two new haplotypes for the mitocondrial D‐loop of mustelids are described after DNA sequencing.
Male mate choice in the Botswana armoured ground cricket Acanthoplus discoidalis (Orthoptera: Tettigoniidae; Hetrodinae). Can, and how, do males judge female mating history?
Authors: Bateman Philip W. , Ferguson J. W. H. 
Published: February 2004

AbstractIn species of many taxa, males alter their investment in ejaculates depending on perceived levels of male–male competition and female mating history/age. Males of the tettigoniid Acanthoplus discoidalis produce a large sperm ampulla and associated spermatophylax, resulting in a long refractory period for males. Female A. discoidalis mate once before laying eggs, and then mate and lay eggs in a random order. The males, therefore, only have a high confidence of paternity when mating with virgins. Male A. discoidalis were studied to determine if they alter their investment in sperm count, spermatophylax mass and water content of spermatophylaces when mating with virgin and non‐virgin females. No difference in investment in any spermatophore characteristics between virgins and non‐virgins was found, but males do reject non‐virgins more often, preferring to transfer spermatophores to virgin females. Males seem to prefer females of a lower mass, where higher mass may reflect increasing female age (and hence likelihood of previous matings) through advanced development of eggs. Outright rejection, rather than changes in spermatophore investment may be because of constraints in tailoring large spermatophores that develop over relatively long periods of time between matings.
Evidence for functional segregation in the directionally asymmetric male genitalia of the spider Metagonia mariguitarensis (González‐Sponga) (Pholcidae: Araneae)
Authors: Huber Bernhard A. 
Published: February 2004

AbstractThe asymmetric male and female genitalia of the spider Metagonia mariguitarensis (González‐Sponga) are described, based on semi‐thin serial sections and SEM photographs, and several male genital and non‐genital characters are measured and analysed statistically. Left male genital bulbs are significantly larger than right bulbs while right palpal tibiae are significantly stronger than left tibiae, suggesting a functional segregation into a more predominantly displaying right palp and a more predominantly sperm‐transferring left palp. Despite several structural differences between right and left male palps, however, there is no indication of qualitative differences: both bulbs transfer sperm, and both palps are provided with a full set of muscles. The female internal genitalia are provided with an unpaired receptacle that is connected to the uterus externus by a wide and complicated duct and to the valve separating uterus externus from uterus internus by a short narrow duct. This resembles entelegyne genitalia, but the functional details remain unknown. The evolution of asymmetric genitalia is discussed in a wider framework, with the conclusion that the causes of asymmetry in spiders may be different from those in other arthropods such as insects and copepods.
Sensitivity and selectivity in protein structure comparison
Authors: Sierk Michael L. , Pearson William R. 
Published: February 2004

AbstractSeven protein structure comparison methods and two sequence comparison programs were evaluated on their ability to detect either protein homologs or domains with the same topology (fold) as defined by the CATH structure database. The structure alignment programs Dali, Structal, Combinatorial Extension (CE), VAST, and Matras were tested along with SGM and PRIDE, which calculate a structural distance between two domains without aligning them. We also tested two sequence alignment programs, SSEARCH and PSI‐BLAST. Depending upon the level of selectivity and error model, structure alignment programs can detect roughly twice as many homologous domains in CATH as sequence alignment programs. Dali finds the most homologs, 321–533 of 1120 possible true positives (28.7%–45.7%), at an error rate of 0.1 errors per query (EPQ), whereas PSI‐BLAST finds 365 true positives (32.6%), regardless of the error model. At an EPQ of 1.0, Dali finds 42%–70% of possible homologs, whereas Matras finds 49%–57%; PSI‐BLAST finds 36.9%. However, Dali achieves >84% coverage before the first error for half of the families tested. Dali and PSI‐BLAST find 9.2% and 5.2%, respectively, of the 7056 possible topology pairs at an EPQ of 0.1 and 19.5, and 5.9% at an EPQ of 1.0. Most statistical significance estimates reported by the structural alignment programs overestimate the significance of an alignment by orders of magnitude when compared with the actual distribution of errors. These results help quantify the statistical distinction between analogous and homologous structures, and provide a benchmark for structure comparison statistics.
Using lanthanide ions to align troponin complexes in solution: Order of lanthanide occupancy in cardiac troponin C
Authors: Gay Grant L. , Lindhout Darrin A. , Sykes Brian D. 
Published: February 2004

AbstractThe potential for using paramagnetic lanthanide ions to partially align troponin C in solution as a tool for the structure determination of bound troponin I peptides has been investigated. A prerequisite for these studies is an understanding of the order of lanthanide ion occupancy in the metal binding sites of the protein. Two‐dimensional {1H, 15N} HSQC NMR spectroscopy has been used to examine the binding order of Ce3+, Tb3+, and Yb3+ to both apo‐ and holo‐forms of human cardiac troponin C (cTnC) and of Ce3+ to holo‐chicken skeletal troponin C (sTnC). The disappearance of cross‐peak resonances in the HSQC spectrum was used to determine the order of occupation of the binding sites in both cTnC and sTnC by each lanthanide. For the lanthanides tested, the binding order follows that of the net charge of the binding site residues from most to least negative; the N‐domain calcium binding sites are the first to be filled followed by the C‐domain sites. Given this binding order for lanthanide ions, it was demonstrated that it is possible to create a cTnC species with one lanthanide in the N‐domain site and two Ca2+ ions in the C‐domain binding sites. By using the species cTnC•Yb3+•2 Ca2+ it was possible to confer partial alignment on a bound human cardiac troponin I (cTnI) peptide. Residual dipolar couplings (RDCs) were measured for the resonances in the bound 15N‐labeled cTnI129–148 by using two‐dimensional {1H, 15N} inphase antiphase (IPAP) NMR spectroscopy.
Nucleotide‐induced switch in oligomerization of the AAA+ ATPase ClpB
Authors: Akoev Vladimir , Gogol Edward P. , Barnett Micheal E. , Zolkiewski Michal 
Published: February 2004

AbstractClpB is a member of the bacterial protein‐disaggregating chaperone machinery and belongs to the AAA+ superfamily of ATPases associated with various cellular activities. The mechanism of ClpB‐assisted reactivation of strongly aggregated proteins is unknown and the oligomeric state of ClpB has been under discussion. Sedimentation equilibrium and sedimentation velocity show that, under physiological ionic strength in the absence of nucleotides, ClpB from Escherichia coli undergoes reversible self‐association that involves protein concentration‐dependent populations of monomers, heptamers, and intermediate‐size oligomers. Under low ionic strength conditions, a heptamer becomes the predominant form of ClpB. In contrast, ATPγS, a nonhydrolyzable ATP analog, as well as ADP stabilize hexameric ClpB. Consistently, electron microscopy reveals that ring‐type oligomers of ClpB in the absence of nucleotides are larger than those in the presence of ATPγS. Thus, the binding of nucleotides without hydrolysis of ATP produces a significant change in the self‐association equilibria of ClpB: from reactions supporting formation of a heptamer to those supporting a hexamer. Our results show how ClpB and possibly other related AAA+ proteins can translate nucleotide binding into a major structural transformation and help explain why previously published electron micrographs of some AAA+ ATPases detected both six‐ and sevenfold particle symmetry.
Directed discovery of bivalent peptide ligands to an SH3 domain
Authors: Ferguson Monique R. , Fan Xiuzhen , Mukherjee Munia , Luo Jinquan , Khan Raza , Ferreon Josephine C. , Hilser Vincent J. , Shope Robert E. , Fox Robert O. 
Published: February 2004

AbstractThe Caenorhabditis elegans SEM‐5 SH3 domains recognize proline‐rich peptide segments with modest affinity. We developed a bivalent peptide ligand that contains a naturally occurring proline‐rich binding sequence, tethered by a glycine linker to a disulfide‐closed loop segment containing six variable residues. The glycine linker allows the loop segment to explore regions of greatest diversity in sequence and structure of the SH3 domain: the RT and n‐Src loops. The bivalent ligand was optimized using phage display, leading to a peptide (PP‐G4‐L) with 1000‐fold increased affinity for the SEM‐5 C‐terminal SH3 domain over that of a natural ligand. NMR analysis of the complex confirms that the peptide loop segment is targeted to the RT and n‐Src loops and parts of the β‐sheet scaffold of this SH3 domain. This binding region is comparable to that targeted by a natural non‐PXXP peptide to the p67phox SH3 domain, a region not known to be targeted in the Grb2 SH3 domain family. PP‐G4‐L may aid in the discovery of additional binding partners of Grb2 family SH3 domains.
Structure of the archaeal translation initiation factor aIF2β from Methanobacterium thermoautotrophicum: Implications for translation initiation
Authors: Gutiérrez Pablo , Osborne Michael J. , Siddiqui Nadeem , Trempe Jean‐François , Arrowsmith Cheryl , Gehring Kalle 
Published: February 2004

AbstractaIF2β is the archaeal homolog of eIF2β, a member of the eIF2 heterotrimeric complex, implicated in the delivery of Met‐tRNAiMet to the 40S ribosomal subunit. We have determined the solution structure of the intact β‐subunit of aIF2 from Methanobacterium thermoautotrophicum. aIF2β is composed of an unfolded N terminus, a mixed α/β core domain and a C‐terminal zinc finger. NMR data shows the two folded domains display restricted mobility with respect to each other. Analysis of the aIF2γ structure docked to tRNA allowed the identification of a putative binding site for the β‐subunit in the ternary translation complex. Based on structural similarity and biochemical data, a role for the different secondary structure elements is suggested.
Cytoarchitecture and musculotopic organization of the facial motor nucleus in Cebus apella monkey
Authors: Horta‐Júnior J. A. C. , Tamega O. J. , Cruz‐Rizzolo R. J. 
Published: February 2004

AbstractThe architecture and musculotopic organization of the facial motor nucleus in the Cebus apella monkey (a New World primate) were investigated using histological techniques and a multiple labelling strategy, in which horseradish peroxidase‐conjugated neuroanatomical tracers (CTB‐HRP and WGA‐HRP) and fluorescent tracers were injected into individual facial muscles. The facial motor nucleus was formed by multipolar motoneurons and had an ovoid shape, with its rostrocaudal axis measuring on average 1875 µm. We divided the nucleus into four different subnuclei: medial, intermediate, dorsal and lateral. Retrograde labelling patterns revealed that individual muscles were innervated by longitudinal functional columns of motoneurons. The columns of the orbicularis oculi, zygomaticus, orbicularis oris, auricularis superior, buccinator and platysma muscles were located in the dorsal, intermediate, lateral, medial, lateral and intermediate subnuclei, respectively. However, the motoneuron columns of the levator labii superioris alaeque nasi muscle and frontalis muscle could not be associated with a specific subnucleus. The present results confirm previous studies regarding the musculotopic organization of the facial motor nucleus. However, we observed some particularities in terms of the relative size of each column in C. apella, which might be related to the functional and behavioral importance of each muscle in the particular context of this primate.
Perspectives on hyperphalangy: patterns and processes
Authors: Fedak Tim J. , Hall Brian K. 
Published: February 2004

AbstractHyperphalangy is a digit morphology in which increased numbers of phalanges are arranged linearly within a digit beyond the plesiomorphic condition. We analyse patterns and processes of hyperphalangy by considering previous definitions and occurrences of hyperphalangy among terrestrial and secondarily aquatic extant and fossil taxa (cetaceans, ichthyosaurs, plesiosaurs and mosasaurs), and recent studies that elucidate the factors involved in terrestrial autopod joint induction. Extreme hyperphalangy, defined as exceeding a threshold condition of 4/6/6/6/6, is shown only to be found among secondarily aquatic vertebrates with a flipper limb morphology. Based on this definition, hyperphalangy occurs exclusively in digits II and III among extant cetaceans. Previous reports of cetacean embryos having more phalanges than adults is clarified and shown to be based on cartilaginous elements not ossified phalanges. Developmental prerequisites for hyperphalangy include lack of cell death in interdigital mesoderm (producing a flipper limb) and maintenance of a secondary apical ectodermal ridge (AER), which initiates digit elongation and extra joint patterning. Factors of the limb‐patterning pathways located in the interdigital mesoderm, including bone morphogenetic proteins (BMPs), BMP antagonists, fibroblast growth factors (FGFs), growth/differentiation factor‐5 (GDF‐5), Wnt‐14 and ck‐erg, are implicated in maintenance of the flipper limb, secondary AER formation, digit elongation and additional joint induction leading to hyperphalangy.
Shareholding structure, depoliticization and firm performance
Authors: Wong Sonia M. L. , Opper Sonja , Hu Ruyin 
Published: February 2004

AbstractIn this study we use a dataset that provides information on Chinese Communist Party grassroots organizations’ political control over decision‐making in China's listed firms. Specifically, we examine how different types of shareholders affect (1) the party's level of decision‐making power and (2) the implications of party control for firm performance. We obtain two major results. First, we find that the proportion of shares held by domestic individual shareholders is negatively related to the party's level of decision‐making power. Second, we find that the existence of large institutional investors is associated with a reduced negative performance effect of party control. Our results suggest that both the exit and the voice channels may offer mechanisms for depoliticizing China's listed firms and improving their performance. This study both addresses an important corporate governance issue relevant to China's listed firms and offers interesting information in terms of comparative studies of corporate governance and reform strategies in transitional economies.
A golden shot: how ballistic single cell transformation boosts the molecular analysis of cereal–mildew interactions
Authors: Panstruga Ralph 
Published: February 2004

SUMMARYDespite considerable technical progress in past years, genetic manipulation of cereals remains a tedious task. Thus, transgenic approaches in monocot species to study plant–microbe interactions are limited to date. Transient gene expression in single epidermal cells mediated by particle bombardment has emerged recently as an attractive alternative for testing the impact of (over‐)expressing or silencing single host genes in the context of cereal–powdery mildew interactions. The ease and pace of this assay enables the analysis of candidate genes within a fraction of the time needed to generate stable transgenic lines. Genetically encoded fluorescent sensors expressed in single cells are ideally suited to monitor gene expression, subcellular protein localization and changes of physiological parameters at the single cell level. Likewise, single cell gene expression can be employed to study protein–protein interactions of fluorophore‐tagged polypeptides by fluorescence resonance energy transfer or fluorescence (cross) correlation spectroscopy. An integrated approach, combining single cell gene expression technology with modern cell biological tools and single cell sampling via laser capture microdissection, may provide in‐depth insights into the molecular events in epidermal host cells in the course of cereal–mildew interactions.
Developmental expression and biochemical properties of a β‐1,4‐endoglucanase family in the soybean cyst nematode, Heterodera glycines
Authors: Gao Bingli , Allen R. , Davis E. L. , Baum T. J. , Hussey R. S. 
Published: February 2004

SUMMARYThe soybean cyst nematode, Heterodera glycines, produces β‐1,4‐endoglucanases (cellulases) that are secreted during infection of soybean. The gene structures of three, hg‐eng‐4, hg‐eng‐5 and hg‐eng‐6, of the six β‐1,4‐endoglucanase genes, all family 5 glycosyl hydrolases previously identified from H. glycines, are presented here. Furthermore, we present the detailed expression analyses of β‐1,4‐endoglucanase genes as well as the biochemical properties of four H. glycines endoglucanase enzymes. Two of the endoglucanases, HG‐ENG‐5 and HG‐ENG‐6, differed significantly in their amino acid sequence of the catalytic domains and their gene structure from that of the other four β‐1,4‐endoglucanases. Quantitative real‐time RT‐PCR revealed distinct developmental expression differences among the hg‐eng family members during the early stages of parasitism and relatively low expression levels in late parasitic stages, with the exception of the adult male stage for some eng genes. Recombinant HG‐ENGs degraded carboxymethylcellulose and optimum enzyme activity ranged from pH 5.5 for HG‐ENG‐5 to pH 8 for HG‐ENG‐6. EDTA, Ca2+, Co2+, Mg2+ and Fe2+ did not affect enzyme activity of any ENG protein, whereas Zn2+, Cu2+ and Mn2+ inhibited enzyme activity from 23% to 73% in some cases. In tests with 12 different polysaccharide substrates, enzyme activity was restricted to β‐1,4 linkages with all ENG proteins tested. Only HG‐ENG‐5 and HG‐ENG‐6 had relatively high activity on xylan and slightly degraded microcrystalline cellulose. Together, these data reveal distinct differences in expression and biochemistry of cyst nematode parasitism genes and proteins, respectively, and cast light on the intricate interactions between a parasitic animal and its plant host.
Reprogramming plant gene expression: a prerequisite to geminivirus DNA replication
Authors: Hanley‐Bowdoin Linda , Settlage Sharon B. , Robertson Dominique 
Published: February 2004

SUMMARYGeminiviruses constitute a large family of plant‐infecting viruses with small, single‐stranded DNA genomes that replicate through double‐stranded intermediates. Because of their limited coding capacity, geminiviruses supply only the factors required to initiate their replication and use plant nuclear DNA polymerases to amplify their genomes. Many geminiviruses replicate in differentiated cells that no longer contain detectable levels of host DNA polymerases and associated factors. To overcome this barrier, geminiviruses induce the accumulation of DNA replication machinery in mature plant cells by reprogramming host gene expression. The mammalian DNA tumour viruses activate host genes required for DNA replication by binding to the retinoblastoma protein, a negative regulator of cell cycle progression, and relieving repression through the E2F family of transcription factors. In this review, we discuss recent experiments showing that geminiviruses also modulate components of the retinoblastoma/E2F transcription regulatory network to induce quiescent plant cells to re‐enter the cell cycle and regain the capacity to support high levels of DNA replication. Regulation of the cell division cycle and its integration with developmental pathways is complex, with many factors, including hormones, sucrose and environmental signals, controlling re‐entry into the plant cell cycle. Geminivirus interactions with these regulatory networks are likely to determine if and where they can replicate their genomes in different plant tissues and hosts.
The influence of follicular migration on T‐cell differentiation
Authors: Smith Karen M. , Brewer James M. , Mowat Allan Mci. , Ron Yacov , Garside Paul 
Published: February 2004

SummaryThe sequence of events that leads to the development of a T‐dependent B‐cell response has been studied for many years and much attention has focused on the importance of these interactions for the B cell and the antibody response. While a role for B cells in T‐cell memory has been demonstrated, the cellular and molecular mechanisms underlying this are unclear and the importance for T cells to migrate into follicles and interact with B cells has received relatively little attention. These interactions between T and B lymphocytes are facilitated by a co‐ordinated series of migration events within lymph nodes and here we propose that this migration and these events are essential for the terminal differentiation of all CD4+ T cells and without it tolerance may result.