bluuebunny/crossref_metadata_2025_split huggingface dataset:
State‐dependent fertility in pinnipeds: contrasting capital and income breeders
Authors: Boyd I. L. 
Published: November 2003

Abstract1. The study tested the hypothesis that the occurrence of pregnancy in mammals that are capital breeders will be most closely related to state variables that are indices of food stores. Income breeders would not be expected to have the same relationship.2. The study examined the relationships between mass, time of year, age and body length with the occurrence of pregnancy in three species of pinniped. This included two capital breeders (Crabeater Seal, Lobodon carcinophagus Hombron & Jacquinot, and Grey Seal, Halichoerus grypus Fabricius) and one income breeder (Antarctic Fur Seal, Arctocephalus gazella Peters). Multiple logistic regression analysis was used to examine the relationships and the interactions between the different state variables.3. In both the capital breeders the state variables used in the study explained approximately twice the amount of variability (55% compared with 25%) in the occurrence of pregnancy than in the income breeder. Mass was the dominant state variable among both the capital breeders whereas in the income breeder mass was less important both relative to other state variables and in absolute terms. The results support the conclusion that the occurrence of pregnancy in capital breeders is more sensitive to body reserves than it is in income breeders.4. The results also support the conclusion that life histories are the end result of a variety of functional responses to different state variables that have differing degrees of influence. In particular a size‐structured approach to studies of population dynamics in pinnipeds may be a more informative way of predicting population responses to environmental variability than the more traditional age‐structured approach.
Particle feeding in Aphodius dung beetles (Scarabaeidae): old hypotheses and new experimental evidence
Authors: P. Holter 
Published: November 2003

Abstract1. Published studies of the highly specialized mouthparts of adult scarabaeid dung beetles have proposed that the beetles feed on (1) liquid with minute particles, squeezed out of the dung by the mandibular molars, and/or (2) dung particles that are finely ground by the same molars. These hypotheses were tested experimentally.2. The maximum size of ingested particles was determined in six Aphodius species (Scarabaeidae, Aphodiinae) feeding on dung with latex‐balls of known diameters. The probability of ingestion decreased with particle size. The diameter of balls with a 5% chance of ingestion varied between species from <5 µm to about 25 µm. This maximum size, which precludes hypothesis (1), was related to feeding habits, not to body mass.3. Simple experiments did not indicate any comminution by the mouthparts of dung particles.4. It is suggested that coarse (mostly indigestible) particles are rejected by filtering setae and that the remaining small particles, prior to ingestion, are concentrated on the molars by squeezing which eliminates superfluous water.5. Since 40–50% of the dry matter in fresh dung from grazing cows, sheep and horses consisted of particles <20 µm, food competition among adult Aphodius seems unlikely in spite of their selective feeding.
Causes and consequences of mass loss upon predator encounter: feeding interruption, stress or fit‐for‐flight?
Authors: Veen I. T. Van Der , Sivars L. E. 
Published: November 2003

Abstract1. Birds have been shown to lose mass upon predator encounters. This mass loss has generally been assumed to be caused by the feeding interruption the birds experience upon encountering the predator. However, birds may lose this mass because of predator stress and because they prepare themselves for flight (fit‐for‐flight). In this experiment the aim was to distinguish between effects of feeding interruptions and stress or fit‐for‐flight on the mass loss of Yellowhammers (Emberiza citrinella L.) upon predator exposure.2. When exposed to a 45‐min feeding interruption, the birds lost only a quarter of the mass they lost when they were moved to another room and exposed to a stuffed Sparrowhawk (Accipiter nisus) for 1 min at that beginning of the feeding interruption. This indicates that mass loss upon predator exposure is not just due to the feeding interruption birds experience upon encountering a predator, but is probably, to a large extent, due to both predator stress and fit‐for‐flight.3. When the stuffed Sparrowhawk was replaced with a dummy (an opaque plastic bottle), mass loss upon exposure was similar to the loss in the Sparrowhawk treatment. This indicates that moving the birds to another room, which occurred in both these treatments, may to a large extent be the cause of the mass loss.4. During the same day, the birds regained 92% of their losses. However, regaining those losses was partly postponed to the end of the day, which indicates that the birds faced a trade‐off between starvation and predation risk, and were able to respond to that trade‐off by altering their diurnal trajectory of mass increase. By postponing foraging to the end of the day, the birds decreased the mass‐dependent costs of predation risk.
Functional interaction of Escherichia coli RNA polymerase with inorganic polyphosphate
Authors: Kusano Shuichi , Ishihama Akira 
Published: November 2003

Background:RNA polymerase from the stationary growth phase cells of Escherichia coli is tightly associated with an acidic compound(s) and exhibits altered promoter selectivity, with reduced transcriptional activity of the genes highly expressed in the exponentially growing cells. Here we have examined the nature of the RNA polymerase‐associated acidic compound(s).Results:RNA polymerase isolated from stationary‐phase cells of E. coli was found to be tightly associated with inorganic polyphosphates (poly P), and cannot be dissociated even after chromatography on phosphocellulose or DNA‐cellulose columns. Since RNA polymerase–poly P complexes reconstituted in vitro showed similar properties, poly P was not binding covalently. The inhibitory effects of poly P on transcription were examined using two forms of the holoenzyme, one containing σ70, the major σ for transcription of the genes expressed during exponential cell growth and the other containing σ38, the principal σ in the stationary growth phase. At low salt concentrations, poly P inhibited transcription by both Eσ70 and Eσ38 holoenzymes. With an increase in the concentration of potassium glutamate, the poly P inhibition was relieved. At high salt concentrations, the Eσ70 holoenzyme is not able to function, but the Eσ38 holoenzyme is however activated.Conclusions:These results show that poly P may play a role in the promoter selectivity control of RNA polymerase in E. coli which is growing under conditions of high osmolarity and in the stationary growth phase.
A globular complex formation by Nda1 and the other five members of the MCM protein family in fission yeast
Authors: Adachi Yasuhisa , Usukura Jiro , Yanagida Mitsuhiro 
Published: November 2003

Background:In the fission yeast Schizosaccharomyces pombe, Nda1, Nda4, Mis5 and Cdc21 proteins belong to the MCM (minichromosome maintenance) protein family which is thought to have six members. Each MCM member is required for the early stages of DNA replication, and has a well‐conserved central 200‐amino acid domain containing a putative ATP binding motif. However, the precise molecular functions of MCM proteins are not yet clear.Results:We investigated the physical interaction of Nda1 protein with the other fission yeast MCM proteins using specific antibodies. Immunoprecipitation of Nda1 protein leads to the co‐precipitation of all the other members of the fission yeast MCM protein family. We purified the MCM protein complex by a combination of column chromatography. The native molecular weight of the MCM complex was estimated by gel filtration to be 560 kDa. The purified fraction contained nearly equal quantities of the six MCM proteins. Electron microscope observation showed that the MCM complex has a globular shape with a central cavity.Conclusions:We have developed a procedure to purify fission yeast MCM proteins in a native hetero‐oligomeric complex form for the first time, which opens an avenue to further biochemical analysis.
Switching yeast from meiosis to mitosis: double‐strand break repair, recombination and synaptonemal complex
Authors: Zenvirth Drora , Loidl Josef , Klein Shoshana , Arbel Ayelet , Shemesh Ronen , Simchen Giora 
Published: November 2003

Background:When Saccharomyces cerevisiae cells that have begun meiosis are transferred to mitotic growth conditions (‘return‐to‐growth’, RTG), they can complete recombination at high meiotic frequencies, but undergo mitotic cell division and remain diploid. It was not known how meiotic recombination intermediates are repaired following RTG. Using molecular and cytological methods, we investigated whether the usual meiotic apparatus could repair meiotically induced DSBs during RTG, or whether other mechanisms are invoked when the developmental context changes.Results:Upon RTG, the rapid disappearance of meiotic features—double‐strand breaks in DNA (DSBs), synaptonemal complex (SC), and SC related structures—was striking. In wild‐type diploids, the repair of meiotic DSBs during RTG was quick and efficient, resulting in homologous recombination. Kinetic analysis of double‐strand breakage and recombination indicated that meiotic DSB formation precedes the commitment to meiotic levels of recombination. DSBs were repaired in RTG in dmc1, but not rad51 mutants, hence repair did not occur by the usual meiotic mechanism which requires the Dmc1 gene product. In haploids, DSBs were also repaired quickly and efficiently upon RTG, showing that DSB repair did not require the presence of a homologous chromosome. In all strains examined, SC and related structures were not required for DSB repair or recombination following RTG.Conclusions:At least two pathways of DSB repair, which differ from the primary meiotic pathway(s), can occur during RTG: One involving interhomologue recombination, and another involving sister‐chromatid exchange. DSB formation precedes commitment to recombination. SC elements appear to prevent sister chromatid exchange in meiosis.
Two closely‐related left‐right asymmetrically expressed genes, lefty‐1 and lefty‐2: their distinct expression domains, chromosomal linkage and direct neuralizing activity in Xenopus embryos
Authors: Meno Chikara , Ito Yuzuru , Saijoh Yukio , Matsuda Youichi , Tashiro Kosuke , Kuhara Satoru , Hamada Hiroshi 
Published: November 2003

Background:Vertebrates have numerous lateral asymmetries in the position of their organs, but the molecular basis for the determination of left–right (L‐R) asymmetries remains largely unknown. TGFβ‐related genes such as lefty and nodal are L‐R asymmetrically expressed in developing mouse embryos, and may be involved in L‐R determination.Results:We have identified two highly conserved genes, lefty‐1 and lefty‐2, in the mouse genome. These two genes are tightly linked on mouse chromosome 1. lefty‐1 and lefty‐2 are both expressed in a L‐R asymmetric fashion in mouse embryos. However, the major expression domains of the two genes are different: lefty‐1 expression is predominantly confied to the left side of ventral neural tube, whereas lefty‐2 is strongly expressed in the lateral plate mesoderm on the left side. In embryos homozygous for the iv and inv mutation, which cause situs inversus, the expression sites of both genes are affected, either reversed or bilaterally, indicating that lefty‐1 and lefty‐2 are downstream of iv and inv. Although Lefty‐1 and Lefty‐2 prepro‐proteins are not readily processed in cultured cells, BMP2‐Lefty chimeric proteins can be processed to a secreted form. We have examined the activities of Lefty‐1 and Lefty‐2 in Xenopus embryos. In animal cap explants, Lefty‐1 and Lefty‐2 induce neural cells in the absence of mesoderm induction. The direct neuralizing activities of Lefty‐1 and Lefty‐2 thus seem remarkably similar to those of BMP antagonists such as noggin and chordin, suggesting that the action of Lefty‐1 and Lefty‐2 may be to locally antagonize BMP (bone morphogenic protein)‐mediated signals in tissues positioned on the left side of the mouse embryos.Conclusion:There are two lefty genes in mice (lefty‐1 and lefty‐2), both of which are expressed in a L‐R asymmetric fashion and are downstream of iv and inv. Lefty‐1 and Lefty‐2 possess direct neuralizing activity in Xenopus embryos, resembling the activities of BMP antagonists.
A novel form of the myeloid‐specific zinc finger protein (MZF‐2)
Authors: Murai Kasumi , Murakami Hiroshi , Nagata Shigekazu 
Published: November 2003

Background:Myeloid cell development is controlled by tissue‐specific transcription factors. Human myeloid zinc finger protein (MZF‐1) is a putative transcription factor containing 13 zinc fingers, and has been suggested that it regulates the development of neutrophilic granulocytes.Results:Here, we have isolated the murine and human cDNAs which encode a novel form of MZF protein (MZF‐2). Murine and human MZF‐2 proteins consisted of 814 and 775 amino acids, respectively, and have identity of 75.3% between them. The C‐terminal half of human MZF‐2, carrying the zinc finger domains, was completely identical with that of human MZF‐1, whereas the N‐terminal half of MZF‐2 was different from the corresponding region of human MZF‐1, and was coded by distinct exons. MZF‐2 mRNA was expressed in myeloid cells, particularly in the cells committed to the neutrophilic lineage, and down‐regulated by G‐CSF.Conclusions:MZF‐1 and MZF‐2 mRNAs seem to be produced by the alternative use of two different transcription initiation sites. The distinct N‐terminal half of MZF‐2 carries two characteristic domains, a leucine‐rich domain called LeR and an acidic domain, which suggests a unique function of MZF‐2 in neutrophil development.
Functional analyses of mammalian protein kinase C isozymes in budding yeast and mammalian fibroblasts
Authors: Nomoto Satoshi , Watanabe Yasuyuki , Ninomiya‐Tsuji Jun , Yang Li‐Xia , Kiuchi Kazutoshi , Hagiwara Masatoshi , Hidaka Hiroyoshi , Matsumoto Kunihiro , Irie Kenji 
Published: November 2003

Background:The PKC1 gene of Saccharomyces cerevisiae encodes a homologue of mammalian protein kinase C (PKC) that is required for yeast cell growth. Pkc1 has been proposed to regulate a protein kinase cascade which includes the Bck1, Mkk1/Mkk2 and Mpk1 kinases. The functional relationship between Pkc1 and mammalian PKCs is unknown. Another signal transduction in Saccharomyces cerevisiae, the mating pheromone signalling pathway, is mediated by a heterotrimeric G protein, and causes cell cycle arrest in the G1 interval. It is not clear whether PKC is involved in this pathway. The effects of overexpression of PKCs in mammalian cells have been widely studied to analyse the function of PKCs in vivo.Results:We isolated a human cDNA which encodes a protein kinase C type η (PKC‐η) by complementation of pkc1 mutations in Saccharomyces cerevisiae. The human PKC‐η was able to complement the growth defect caused by the deletion of PKC1, whereas PKC‐η was unable to suppress the defect caused by deletion of BCK1. We also isolated human cDNAs that can suppress the adaptation defect of sst2. One of them encodes a protein kinase C type δ (PKC‐δ). Expression of this gene in yeast stimulated an adaptation to the pheromone response. Human PKC‐δ suppressed the adaptation defect of a pheromone receptor mutation lacking its C‐terminal domain, but not that of a G protein β‐subunit mutation eliminating signal‐induced phosphorylation, and not the lethality of the gpa1 null mutation. Moreover, overexpression of PKC‐η in NIH3T3 cells induced anchorage‐independent growth.Conclusions:PKC‐η has a biological activity which is closely related to Pkc1, and PKC‐η activates the Pkc1‐mediated pathway through an activation of the Bck1 kinase that is a homologue of MAP kinase kinase kinase. PKC‐η appears to play a critical role in growth control of yeast and mammalian cells. Suppression experiments with PKC‐δ suggest that PKC‐δ desensitizes the pathway by regulating an aspect of G protein function.
A single copy of linker H1 genes is enough for proliferation of the DT40 chicken B cell line, and linker H1 variants participate in regulation of gene expression
Authors: Takami Yasunari , Nakayama Tatsuo 
Published: November 2003

Background:There is general agreement that large numbers of histone H1 are necessary for maintenance of the higher order structure of chromatin in higher eukaryotes. The chicken H1 gene family comprises six members per haploid genome, the total copy number being 12, and they encode six H1 variants which are considerably different from each other in amino acid sequence. We recently established that in two chicken DT40 mutants (1/2Δ110kb and Δ57kb), which lack, respectively, one allele of the gene cluster of 110 kb carrying six H1 genes, plus 33 core histone genes, and two copies each of four of the six H1 genes included in an ≈ 57 kb segment of the cluster, expression of the remaining H1 genes is increased, resulting in constant steady‐state levels of total H1 mRNAs. These results gave rise to the simple questions of how many H1 genes and how many H1 variants, at minimum, are necessary for the viability of DT40 cells.Results:We generated two DT40 mutants, Δ10/12H1 and Δ11/12H1, which are devoid, respectively, of two copies each of five H1 genes, and those plus a single copy of the last H1 gene, in addition to 17 core histone genes. Analyses involving a RNase protection assay, SDS‐PAGE and acid‐urea‐PAGE revealed, not only that in the Δ10/12H1 mutant the steady‐state levels of total H1 mRNAs and the amounts of histone H1 were not changed, but also that in the Δ11/12H1 mutant both were approximately one‐half the normal levels, and the amounts of HMG proteins were increased about twofold. No alteration in the growth rate or global chromatin structure was observed in either mutant. On the other hand, the protein patterns on 2D‐PAGE of the Δ11/12H1 mutant were definitely distinct from those of the wild‐type cell line.Conclusion:These results indicate not only that a lack of five of the six H1 variants causes changes in the protein patterns, but also that only a single copy of the H1 genes is enough for cell proliferation.
Hepatitis C virus liver disease in women infected with contaminated anti‐D immunoglobulin
Authors: SHEEHAN M.M. , DOYLE C.T. , WHELTON M. , KENNY‐WALSH E. 
Published: November 2003

Screening for hepatitis C virus (HCV) infection is carried out by detection of antibodies to the virus (enzyme‐linked immunosorbent assay (ELISA) and recombinant immunoblot assay (RIBA)) with confirmation by identification of HCV RNA genome in serum (polymerase chain reaction (PCR)). We describe the histological features on liver biopsy in 88 women with chronic HCV infection (serum positive on ELISA, RIBA and PCR) acquired from virus contaminated anti‐D immunoglobulin. For the majority of these patients the time interval from virus infection to presentation was between 17 and 18 years. We separately assessed necroinflammatory disease activity and architectural features on liver biopsy and applied a scoring system which permitted semi‐quantitative documentation of abnormal features. Only three women showed liver biopsies within normal limits (± focal steatosis). The remaining 85 cases showed a predominantly mild or moderate degree of disease activity with interface hepatitis (56.8% of cases), spotty necrosis, apoptosis and focal inflammation (88.6% of cases) and portal inflammation (90.9% of cases). Confluent necrosis was an uncommon finding (2.3% of cases).Assessment of architectural features showed normal appearance in 35.2% of biopsies. The predominant architectural abnormality noted was portal tract fibrosis. Ten per cent of cases, however, showed significant fibrous band and/or nodule formation.
Chemotherapy‐induced acral erythema in leukemic patients: a report of 15 cases
Authors: Demirçay Zeynep , Gürbüz Oya , Alpdoǧan Tülin Budak , Yücelten Deniz , Alpdoǧan Önder , Kurtkaya Özlem , Bayik Mahmut 
Published: November 2003

Abstract Background Chemotherapy‐induced acral erythema is a distinct localized cutaneous response to certain systemic chemotherapeutic agents. Methods Between January 1990 and December 1994, from a total of 76 leukemic patients who have received combination chemotherapy consisting of cytosine arabinoside and anthracycline antibiotics, 15 patients developed chemotherapy‐induced acral erythema. Fourteen of the patients had acute myelocytic leukemia, and one of them had chronic myelogenous leukemia in blast phase. Clinical features of these 15 patients have been analysed. Biopsy specimens obtained from eight of the patients were also evaluated for histopathologic alterations. Results The overall incidence of this reaction was found to be 19.7% in our group of patients receiving this chemotherapy protocol. The onset of reaction varied from the fourth to the seventeenth days of the chemotherapy and resolved within 2 weeks in most of the patients. Lesions appeared as well‐defined erythema and edema involving the palmar surfaces in all of the patients. In nine of the patients the reaction recurred with subsequent chemotherapies. Scattered necrotic keratinocytes, vacuolar alterations of the basal layer, and mild to moderate perivascular lymphocytic infiltration in the dermis were the histopathologic findings observed in the biopsy specimens. Conclusions Chemotherapy‐induced acral erythema is a frequent reaction in patients who are receiving high‐dose chemotherapy. For patients in whom this self‐limited condition develops, reassurance is the mainstay of therapy. Awareness of this reaction is also important to be able to differentiate it from acute graft versus host disease in patients who receive bone marrow transplants.
Treatment of chromoblastomycosis with itraconazole, cryosurgery, and a combination of both
Authors: Bonifaz Alexandro , Martínez‐Soto Esperanza , Carrasco‐Gerard Eugenio , Peniche Jorge 
Published: November 2003

Abstract Background Chromoblastomycosis is a subcutaneous mycosis, seen frequently in tropical areas, and caused by dematiaceous fungi. It produces nodulo‐verrucous lesions in the arms and legs. There is no treatment of choice for this disease and sometimes a combination of chemotherapy and physical therapy is necessary. Methods The study included 12 patients diagnosed with chromoblastomycosis by means of fungal and histopathologic tests. The patients were assigned to three treatment groups: patients with small lesions, not greater than 15 cm2 in area, were assigned to Group 1, in which the treatment consisted of itraconazole 300 mg/day, or to Group 2, in which the treatment consisted of one or more sessions of open‐spray cryosurgery. Patients with large lesions were assigned to Group 3 and started treatment with itraconazole 300 mg/day, until a maximal reduction of lesions occurred, and then underwent one or several cryosurgery sessions. Clinical, fungal, and laboratory tests were performed in each group before, during, and at the completion of treatment. Results Positive cultures of Fonsecaea pedrosoi were obtained in 11 out of 12 patients. Two out of four patients in Groups 1 and 3 had a clinical and fungal cure and the remaining patients experienced significant improvement. All four patients included in Group 2 achieved a cure. No important side‐effects were seen among the patients included in any of the two itraconazole groups, and only two out of eight patients reported gastric discomfort. The cryosurgery group reported only normal complications of the process, such as edema and pain; two out of eight patients had a superimposed infection. Conclusions The results of itraconazole and cryosurgery were good in cases with small lesions; antifungal therapy being more appropriate for flexion areas. The combination of itraconazole, to reduce the size of the lesions, with subsequent treatment of the remaining lesions with cryosurgery, represents a new alternative in the treatment of patients with large lesions. Both types of therapy are considered safe, with few side‐effects.