bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of the hetero‐octameric ATP phosphoribosyl transferase complex from Thermotoga maritima by a tRNA synthetase‐like subunit
Authors: Vega M. Cristina , Zou Peijian , Fernandez Francisco J. , Murphy Gavin E. , Sterner Reinhard , Popov Alexander , Wilmanns Matthias 
Published: January 2005

SummaryThe molecular structure of the ATP phosphoribosyl transferase from the hyperthermophile Thermotoga maritima is composed of a 220 kDa hetero‐octameric complex comprising four catalytic subunits (HisGS) and four regulatory subunits (HisZ). Steady‐state kinetics indicate that only the complete octameric complex is active and non‐competitively inhibited by the pathway product histidine. The rationale for these findings is provided by the crystal structure revealing a total of eight histidine binding sites that are located within each of the four HisGS–HisZ subunit interfaces formed by the ATP phosphoribosyl transferase complex. While the structure of the catalytic HisGS subunit is related to the catalytic domain of another family of (HisGL)2 ATP phosphoribosyl transferases that is functional in the absence of additional regulatory subunits, the structure of the regulatory HisZ subunit is distantly related to class II aminoacyl‐tRNA synthetases. However, neither the mode of the oligomeric subunit arrangement nor the type of histidine binding pockets is found in these structural relatives. Common ancestry of the regulatory HisZ subunit and class II aminoacyl‐tRNA synthetase may reflect the balanced need of regulated amounts of a cognate amino acid (histidine) in the translation apparatus, ultimately linking amino acid biosynthesis and protein biosynthesis in terms of function, structure and evolution.
The tale of two RNA polymerases: transcription profiling and gene expression strategy of bacteriophage Xp10
Authors: Semenova Ekaterina , Djordjevic Marko , Shraiman Boris , Severinov Konstantin 
Published: January 2005

SummaryBacteriophage Xp10 infects rice pathogen Xanthomonas oryzae. Xp10 encodes its own single‐subunit RNA polymerase (RNAP), similar to that found in phages of the T7 family. On the other hand, most of Xp10 genes are organized in a manner typical of lambdoid phages that are known to rely only on host RNAP for their development. To better understand the temporal pattern of viral transcription during Xp10 development, we performed global transcription profiling, primer extension, chemical kinetic modelling and bioinformatic analyses of Xp10 gene expression. Our results indicate that true to its mosaic nature, Xp10 relies on both host and viral RNAPs for expression of genes coding for virion components and host lysis. The joint transcription of the same set of genes by two types of RNA polymerases is unprecedented for a bacteriophage. Curiously, such a situation is realized in chloroplasts.
Diversity and differentiation in two populations of Gibberella circinata in South Africa
Authors: Britz H. , Coutinho T. A. , Wingfield B. D. , Marasas W. F. O. , Wingfield M. J. 
Published: January 2005

Gibberella circinata[anamorph Fusarium circinatum (= F. subglutinans f.sp. pini)] causes pitch canker and is an important pathogen in South African pine nurseries. The initial outbreak of the pitch canker fungus was limited to a single nursery at Ngodwana in Mpumalanga Province. Subsequently, several other pine nurseries in South Africa became infected. Most of these outbreaks were relatively small except for the outbreak in the Klipkraal nursery (Mpumalanga Province). The genetic diversity, population differentiation and relative frequencies of the sexual and asexual cycles among two South African subpopulations were determined to establish whether immigration, mutation and/or recombination contributed towards population structure. The allelic diversity of the initial population (Ngodwana) was observed to be lower (0·16) than that of the more recent Klipkraal population (0·25). Approximately 4% (GST = 0·04) of total gene diversity could be attributed to differences among the subpopulations. Furthermore, six new vegetative compatibility groups (VCGs) have been identified since the initial outbreak of G. circinata in South Africa 10 years ago. The relatively low allelic diversity and low level of genetic differentiation suggest restricted gene flow among subpopulations, and indicate that the pathogen has been introduced recently. However, the amount of allelic and VCG diversity suggests that multiple genotypes have been introduced into South Africa. The increases in effective population number, allelic diversity and new VCGs over the past 10 years suggest that sexual reproduction might be occurring.
Genetic variation in Candidatus Phytoplasma australiense
Authors: Streten C. , Gibb K. S. 
Published: January 2005

This study examined whether genes that are less conserved than the 16S rRNA gene can distinguish Candidatus Phytoplasma australiense strains that are identical based on their 16S rRNA genes, with a view to providing insight into their origins and distribution, and any patterns of association with particular plant hosts. Sequence analysis of the tuf gene and rp operon showed that Ca. P. australiense strains could be differentiated into four subgroups, named 16SrXII‐B (tuf‐Australia I; rp‐A), 16SrXII‐B (tuf‐New Zealand I; rp‐B), 16SrXII‐B (tuf‐New Zealand II) and 16SrXII‐B (rp‐C). Strawberry lethal yellows 1, strawberry green petal, Australian grapevine yellows, pumpkin yellow leaf curl and cottonbush witches’ broom phytoplasmas were designated members of the 16SrXII‐B (tuf‐Australia I; rp‐A) subgroup. The strawberry lethal yellows 2 and cottonbush reduced yellow leaves phytoplasmas were assigned to the 16SrXII (tuf‐New Zealand II; rp‐B) subgroup. No relationship was observed between these phytoplasma subgroups and collection date, location or host plant. However, the study revealed evolutionary divergence in the 16SrXII group.
A combined agar‐absorption and BIO‐PCR assay for rapid, sensitive detection of Xylella fastidiosa in grape and citrus
Authors: Fatmi M. , Damsteegt V. D. , Schaad N. W. 
Published: January 2005

Application of the polymerase chain reaction (PCR) to disease diagnosis is limited in part by the presence of PCR inhibitors. Inhibition can be overcome and sensitivity increased by culturing bacteria on agar media prior to PCR (termed BIO‐PCR). However, Xylella fastidiosa grows slowly, requiring 10–14 days for visible colonies to appear. In this study an agar‐absorption BIO‐PCR method for detecting X. fastidiosa in grape and citrus plants was developed. Optimum lengths of time for absorption of inhibitors by the agar medium or enrichment of bacteria on the medium were determined for Pierce's disease of grape and citrus variegated chlorosis. When petioles of grape and citrus leaves with symptoms were spotted onto agar media, the spots washed after various time intervals and assayed for X. fastidiosa by real‐time PCR, 97% (31 out of 32) and 100% (six out of six) of spots were positive after 2 days and 4 h for grape and citrus, respectively. With direct PCR, only 12·5% (four out of 32) and 33% (two out of six) of spots were positive, respectively, and visible X. fastidiosa colonies were evident after 10 and 14 days, respectively. In a separate experiment with samples from a different vineyard, 46% (13 out of 28) of the grape samples (agar spots) were positive after 1 day and 93% (26 out of 28) after 5 days using agar‐absorption PCR. In contrast, all samples were negative by direct PCR. Viable X. fastidiosa were recovered from all samples after 14 days. Further tests with eight randomly selected grape petioles from three Texas vineyards known to have Pierce's disease resulted in 50% being positive by a simple 24 h agar‐absorption PCR assay, whereas none was positive by direct PCR. Overall, 10 out of 16 (63%) vines from five vineyards (two in California and three in Texas) were positive after the 24 h agar‐absorption PCR assay. In contrast, only one vine was positive by direct PCR. This simple agar absorption‐based PCR assay protocol should prove useful for the routine detection of X. fastidiosa and other slow‐growing bacteria in the presence of PCR inhibitors.
Morphological and molecular characterization of the sudden‐death syndrome pathogen of soybean in Brazil
Authors: Arruda G. M. T. , Miller R. N. G. , Ferreira M. A. S. V. , Café‐Filho A. C. 
Published: January 2005

Brazilian Fusarium isolates causing soybean sudden death syndrome (SDS) were characterized by comparing them with other Fusarium isolates associated with soybean root rot, as well as F. solani f.sp. glycines isolates associated with the disease in the USA, using molecular (mitochondrial and nuclear rDNA), morphological, cultural and pathogenic characteristics. On the basis of pathogenicity data, and restriction fragment length polymorphism and sequence analysis of the rDNA internal transcribed spacer (ITS) regions, isolates formed a group distinct from nonSDS F. solani isolates, as well as other Fusarium species. ITS sequence analysis also revealed that Brazilian isolates were distinct from the majority of SDS pathogens from the USA (Fusarium virguliforme) and conformed to Fusarium tucumaniae.
THE DIAPAUSE FACTOR FROM THE SILKWORM, BOMBYX MORI L.: PURIFICATION AND INACTIVATION EXPERIMENTS
Authors: SONOBE HARUYUKI 
Published: January 2005

The diapause factor, which is responsible for the induction of èmbryonic dia pause in the silkworm (Bombyx mori L.), has been partially purified from the extract of adult heads by means of protein purification procedures, including the use of gel filtration of Sephadex, column chromatography on Dowex 1, isoelectric focusing and phenol extraction.Two species of the diapause factor could be recognized in respect to their molecular weight. They were separated by Sephadex G‐25 and their molecular weights were estimated to be about 2,000 and 5,000 from the gel filtration results. The smaller species was purified about 90‐fold in specific activity, and its isoelectric point was determined by isoelectric focusing to be at about pH 4.5.The biological activity of the partially purified principle could be abolished by incubation with several proteolytic enzymes (trypsin, α‐chymotrypsin and pronase), or by treatment with amino acid‐modifying reagents such as tyrosinase, N‐bromosuccinimide or 2‐hydroxy‐5‐nitrobenzyl bromide, but was not affected by incubation with neuraminidase, cyanogen bromide or photooxidation in the presence of methylene blue.
THE LIFE CYCLE OF THE FRESHWATER COPEPOD EUCYCLOPS SERRULATUS (FISCHER) AND ITS USE IN A BIOASSAY FOR DECAPOD OVARIAN STIMULATING AND INHIBITING SUBSTANCES
Authors: ØU TAKASHI , MAEKAWA KAZUO , CALDWELL MARGARET J. 
Published: January 2005

The first section of this article deals with the description of life cycle in the freshwater copepod Eucyclops serrulatus for the use of bioassay in decapod ovarian stimulating and inhibiting substance.In the second section, the methods and results of administration of substances from the crab, Eriocheir japonicus were described. Extracts of the thoracic ganglion, brain and leg muscle of the crab added to culture of Eucyclops serrulatus which reached Stage VI of the copepodid or shortly after their moult to adulthood. The former two group of animals rapidly bore egg sacs in comparison with the control muscle group. The number of animals carrying egg sacs or not were counted exactly from the shadowgraph of the animals.This new bioassay system using copepods and their shadowgraph counting will be useful not only for future test of ovarian stimulating and inhibiting substance but also for all further works such as the test of moulting hormone.
STRUCTURE AND FORMATION OF THE COLLAR IN CHOANOCYTES OF TETILLA SERICA (LEBWOHL), DEMOSPONGE
Authors: WATANABE YOKO 
Published: January 2005

There are two types of collar in the choanocytes of adult Tetilla serica: one type is a continuous cytoplasmic tube and the other consists of discontinuous microvilli. The former is found in the small flagellated chamber and is considered to belong to a young choanocyte in the process of differertiation. To confirm this idea, very young choanocytes which are about to differentiate the collar were examined during embryogenesis.The youngest choanocytes are noticed forming aggregations of small cells in 3‐day larvae. Around the flagellum in each choanocyte, there is a depression which will become wider. At first, the collar is observed as a ring of cytoplasm; next this extends outward and becomes thinner, and finally it divides into microvilli. The microvillous collar is formed by the opening of vesicles and fusion of their membranes. These vesicles are considered to be derived from the Golgi complex. The process of collar formation through fusion of vesicles is discussed.
DIFFERENCES IN SENSITIVITY TO CA ION LACK BETWEEN MYOBLASTS AND LARGE MYOTUBES FROM CHICKEN BREAST MUSCLE
Authors: Ozawa Eijiro 
Published: January 2005

Large myotubes degenerated in Ca‐deficient medium containing Mg ion. Numerous vacuoles appeared in the cytoplasm and then grew larger. The cells were disrupted and eventually detached from the culture dish. The time course of the destruction process differed from cell to cell and the rate of reduction of creatine kinase in the culture dish was constant irrespective of the time after the removal of Ca ion. Most of the myoblasts survived in Ca‐deficient medium, after almost all the large myotubes had disappeared. These myoblasts fused to form new myotubes when Ca ion was supplied.Myotubes formed from myoblasts which had been cultured with Ca‐deficient medium for 2 weeks also degenerated on Ca removal.Sr ion added to Ca‐deficient medium did not completely prevent the destruction of myotubes but decreased the rate of their reduction.
Studies on the Formation and State of Determination of the Trunk Organizer in the Newt, Cynops Pyrrhogaster III. Tangential Induction in the Dorsal Marginal Zone
Authors: KANÉDA ITERUO 
Published: January 2005

Analysis of the course of differentiation of combinants between the presumptive prechordal plate (PcP) and presumptive ectoderm (PE) by time‐lapse filming showed that the PcP of early gastrulae has the capacity to induce mesoderm (notochord, muscle cells and migrating cells) in the PE. The mesoderm‐inducing capacity of the PcP decreases sharply during gastrulation. Following invagination in the mid‐gastrula, the PcP completely loses its mesoderm‐inducing capacity. This change also occurred when the PcP of the earliest gastrula was aged in vitro for 18 hr. This shows that the mesoderm‐inducing capacity of the PcP decreases autonomously with aging.PE transplanted into the presumptive trunk organizer region of the dorsal marginal zone of the earlist gastrula, became mesodermized within 12 hr. It is clear that this mesodermization of the transplanted PE is due to “tangential induction” from the PcP. The stepwise formation of the trunk organizer in Cynops pyrrhogaster is discussed in consideration of these results.
Histogenesis of the Os Penis and Os Clitoridis in Rats
Authors: MURAKAMI RYUTARO , MIZUNO TAKEO 
Published: January 2005

The development of the os penis in normal male rats and the os clitoridis in the females treated with testosterone were studied histologically and histochemically. Alcian blue‐positive materials, alkaline phosphatase activities and calcium deposit were detected. The os penis of the rats was composed of a proximal segment and a distal one. The proximal segment of the os penis was formed by the fusion of a membrane bone in its distal half and an ossifying hyaline cartilage in its proximal half. The distal segment of the os penis developed as a fibrocartilage bone.Two steps were demonstrated in the development of the os penis: the formation of the rudiments, and the differentiation of the proximal and distal segments. The treatment of newborn females with testosterone induced an os clitoridis homologous to the proximal segment of the os penis. The development of the os clitoridis was compared with that of the os penis.
Genetic Analysis of Developmental Mechanisms in Hydra. XV. Nematocyte Differentiation in Strains with Altered Developmental Gradients*
Authors: NISHIMIYA CHIEMI , FUJISAWA TOSHITAKA , WANEK NANCY , SUGIYAMA TSUTOMU 
Published: January 2005

Nematocyte differentiation from the interstitial stem cells in hydra occurs non‐uniformly along the body column. The relative ratios of the 4 nematocyte types produced vary gradually from head to foot along the body axis (Bode and Smith, 1977). To find out whether this regional variation in nematocyte differentiation along the body column is related to the gradients of the head‐activation and head‐inhibition potentials, nematocyte differentiation patterns were examined in strains which have significantly different developmental gradients along their body columns. Five strains of hydra, including a wild‐type, two mutant strains and two chimeric (mutnt/wild‐type) strains, were investigated.It was found that the regional variations in the nematocyte differentiation were similar in all the strains examined, and that no significant differences of the variation existed that could be attributed to the differences of the developmental gradients in these strains. This suggests that nematocyte differentiation is strongly affected by the axial position along the body column, but that the gradients of the morphogenetic potentials involved in head formation are not involved in this effect. Instead, some other parameter(s) of axial position not directly associated with these gradients must be responsible for the positional effect on nematocyte differentiation.
Sperm Nuclear Transformation and Aster Formation Related to Metabolic Behaviour in Amphibian Eggs
Authors: BÜHLER MARTAI. , PETRINO TERESA , LEGNAME ARNALDO H. 
Published: January 2005

Bufo arenarum oocyte maturation is related to important modifications in the metabolism of carbohydrates. Such changes involve a different relative participation of the main oxidative routes and are under the influence of seasonal variations of the pituitary activity.Ovulated coelomic oocytes obtained during the winter period, were unable to initiate cleavage after injection of a sperm suspension. The extent of sperm head transformation and aster formation in the cytoplasm of oocytes with a different metabolic behaviour (obtained during the winter and summer periods) were studied.Our results show that sperm nuclear transformation and DNA synthesis were quite similar in both types of oocytes. In contrast to summer oocytes, in which the pronucleus was sourranded by an aster, no aster structure was formed in winter ooctyes notwithstanding pronucleus formation occurred.These results suggest that the failure to develop aster may explain the lack of cleaving in winter oocytes. It appears that the metabolic changes, aster formation and the capability to cleave are closely related and could be dissociated from oocyte nuclear maturation in this species.
Prospective Neural Areas and their Morphogenetic Movements during Neural Plate Formation in the Xenopus Embryo. II. Disposition of Transplanted Ectoderm Pieces of X. borealis Animal Cap in Prospective Neural Areas of Albino X. laevis gastrulae.
Authors: SUZUKI AKIO S. , HARADA KEIICHI 
Published: January 2005

Small pieces of the animal cap of X. borealis gastrulae were transplanted into various regions of the noninvoluting marginal zone of albino X. laevis gastrulae, and the distribution of the donor cells was analyzed by quinacrine fluorescence staining.The present study indicated that the prospective central nervous system (CNS) lies as a belt‐shaped area in the noninvoluting marginal zone of early gastrulae. This belt‐shaped prospective neural area extends as far as 0.7 mm (115° to the vegetal pole) above the blastopore in the dorsal midline and 1.3 mm lateral (130° to the dorsal midline) to the dorsal midline. The ectoderm of the dorsal region extends in the animal‐vegetal direction and forms the ventral side of the CNS. The dorsalateral and lateral regions converge toward the dorsal midline and extended in the animal‐vegetal direction. The former constitutes the lateral side of the anterior CNS, and the latter the dorso‐lateral side of the posterior CNS.The outer layer of ectoderm which was transplanted onto the inner layer of the host gastrula differentiated into neural tissues.The prospective areas of the CNS and their morphogenetic movement during Xenopus embryogenesis are also discussed with regard to neural induction.
Yolk Phosphoprotein Metabolism during Early Development of the Fish, Oryzias latipes
Authors: Murakami Masahiro , Iuchi Ichiro , Yamagami Kenjiro 
Published: January 2005

Changes in yolk phosphoproteins of Oryzias latipes embryos during early development were examined by electrophoresis. Four phosphoproteins were identified in the yolk of blastulae by polyacrylamide gel electrophoresis. Two of them were high molecular weight phosphoproteins containing 0.7% (w/w) phosphorus and with similar amino acid compositions to that of vitellogenin. The other two were low molecular weight phosphoproteins, characterized by high contents of phosphorus [12.2% (w/w)] and serine (44.8 mole%) and low contents of aromatic amino acid residues. From these characteristics, together with their behaviors on DEAE‐cellulose chromatography and electrophoresis and low stainability with dyes, the latter two were concluded to be phosvitins. These phosvitins were isolated and partially characterized.The yolk phosphoproteins, especially the phosvitins, were degraded, their amounts in embryos decreased throughout early development. Studies on the mechanism of endogenous phosphoprotein degradation strongly suggested the participation of some protease(s) that was precipitated on centrifugation of the egg homogenate at 14,000 × g for 10 min.
The Wavy Erythropoiesis of Developing Chick Embryos. Isolation of Each Wave by a Differential Lysis and Identification of the Constituent Erythroid Types
Authors: Cirotto Carlo , Barberini Lanfranco , Arangi Ileana 
Published: January 2005

Erythroid carbonic anhydrase (CA) activity of chick embryos from the third day of incubation to the egg hatching has been determined. Five minor activity peaks with maxima at 3, 6, 9, 15 and 17 days of development and a major one with maximum at 19 days have been found. The correlation between the peak distribution and the timing of release into the blood stream of waves of newly produced erythroid cells has been demonstrated on the basis of the following observations: 1) a linear correlation exists between red cell maturation and increase of CA activity; 2) chick red cells undergo lysis in the “Ørskov” medium when their CA activity exceeds a threshold value (23±3 Units/109 red cells); and 3) the lysis kinetics of red cells in the Ørskov medium is proportional to their CA content. We have thus been able to distinguish the immature erythroid forms from the mature ones on the basis of their behaviour in the Ørskov medium. In the blood of developing chick embryos, we have found waves of newly produced red cells at about 2, 4, 7, 10, 16 and 18 days of development.The same experimental criteria allowed us to detect the waves of red cell production in the erythropoietic organs. One wave has been detected in the blood islands at about 2 days; four waves in the yolk sac at about 5, 6, 11 and 15 days; two waves in the spleen at about 18 and 20 days; two waves in the bone marrow at about 19 days of incubation and 1 day after hatching.Primitive erythroid cells are produced in the first two waves: that of blood islands at 2 days and that of yolk sac at 5 days. Definitive red cells are produced in the other waves with the exception of the second wave of spleen and of the second wave of bone marrow, which are constituted by red cells of adult type.