bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vivo studies on the roles of Tic110, Tic40 and Hsp93 during chloroplast protein import
Authors: Kovacheva Sabina , Bédard Jocelyn , Patel Ramesh , Dudley Penny , Twell David , Ríos Gabino , Koncz Csaba , Jarvis Paul 
Published: November 2008

SummaryA multisubunit translocon of the inner envelope membrane, termed Tic, mediates the late stages of protein import into chloroplasts. Membrane proteins, Tic110 and Tic40, and a stromal chaperone, Hsp93, have been proposed to function together within the Tic complex. In Arabidopsis, single genes, atTIC110 and atTIC40, encode the Tic proteins, and two homologous genes, atHSP93‐V and atHSP93‐III, encode Hsp93. These four genes exhibited relatively uniform patterns of expression, suggesting important roles for plastid biogenesis throughout development and in all tissues. To investigate the roles played by these proteins in vivo, we conducted a comparative study of T‐DNA knockout mutants for each Tic gene, and for the most abundantly expressed Hsp93 gene, atHSP93‐V. In the homozygous state, the tic110 mutation caused embryo lethality, implying an essential role for atTic110 during plastid biogenesis. Homozygous tic110 embryos exhibited retarded growth, developmental arrest at the globular stage and a ‘raspberry‐like’ embryo‐proper phenotype. Heterozygous tic110 plants, and plants homozygous for the tic40 and hsp93‐V mutations, exhibited chlorosis, aberrant chloroplast biogenesis, and inefficient chloroplast‐import of both photosynthetic and non‐photosynthetic preproteins. Non‐additive interactions amongst the mutations occurred in double mutants, suggesting that the three components may cooperate during chloroplast protein import.
A study in scarlet: enzymes of ketocarotenoid biosynthesis in the flowers of Adonis aestivalis
Authors: Cunningham Francis X. , Gantt Elisabeth 
Published: November 2008

SummaryThe red ketocarotenoid astaxanthin (3,3′‐dihydroxy‐4,4′‐diketo‐β,β‐carotene) is widely used as an additive in feed for the pigmentation of fish and crustaceans and is frequently included in human nutritional supplements as well. There is considerable interest in developing a plant‐based biological production process for this valuable carotenoid. Adonis aestivalis (Ranunculaceae) is unusual among plants in synthesizing and accumulating large amounts of astaxanthin and other ketocarotenoids. The formation of astaxanthin requires only the addition of a carbonyl at the number 4 carbon of each β‐ring of zeaxanthin (3,3′‐dihydroxy‐β,β‐carotene), a carotenoid typically present in the green tissues of higher plants. We screened an A. aestivalis flower library to identify cDNAs that might encode the enzyme that catalyzes the addition of the carbonyls. Two closely related cDNAs selected in this screen were found to specify polypeptides similar in sequence to plant β‐carotene 3‐hydroxylases, enzymes that convert β‐carotene (β,β‐carotene) into zeaxanthin. The Adonis enzymes, however, exhibited neither 4‐ketolase nor 3‐hydroxylase activity when presented with β‐carotene as the substrate in Escherichia coli. Instead, the products of the Adonis cDNAs were found to modify β‐rings in two distinctly different ways: desaturation at the 3,4 position and hydroxylation of the number 4 carbon. The 4‐hydroxylated carotenoids formed in E. coli were slowly metabolized to yield compounds with ketocarotenoid‐like absorption spectra. It is proposed that a 3,4‐desaturation subsequent to 4‐hydroxylation of the β‐ring leads to the formation of a 4‐keto‐β‐ring via an indirect and unexpected route: a keto‐enol tautomerization.
Arabidopsis SHMT1, a serine hydroxymethyltransferase that functions in the photorespiratory pathway influences resistance to biotic and abiotic stress
Authors: Moreno Juan Ignacio , Martín Raquel , Castresana Carmen 
Published: November 2008

SummaryWe found that a recessive mutation, shmt1‐1, causes aberrant regulation of cell death resulting in chlorotic and necrotic lesion formation under a variety of environmental conditions. Salicylic acid‐inducible genes and genes involved in H2O2 detoxification were expressed constitutively in shmt1‐1 plants in direct correlation with the severity of the lesions. The shmt1‐1 mutants were more susceptible than control plants to infection with biotrophic and necrotrophic pathogens, developing severe infection symptoms in a high percentage of infected leaves. In addition, mutants carrying shmt1‐1 or a loss‐of‐function shmt1‐2 allele, were smaller and showed a greater loss of chlorophyll and greater accumulation of H2O2 than wild‐type plants when subjected to salt stress. SHMT1 was map‐based cloned and found to encode a serine hydroxymetyltransferase (SHMT1) involved in the photorespiratory pathway. Our results indicate that this enzymatic activity plays a critical role in controlling the cell damage provoked by abiotic stresses such as high light and salt and in restricting pathogen‐induced cell death, supporting the notion that photorespiration forms part of the dissipatory mechanisms of plants to minimize production of reactive oxygen species (ROS) at the chloroplast and to mitigate oxidative damage. Moreover, results shown here indicate that whereas production of ROS is an essential component of the hypersensitive defense response, the excessive accumulation of these toxic compounds impairs cell death containment and counteracts the effectiveness of the plant defenses to restrict pathogen infection.
Identification of Arabidopsis thaliana transformants without selection reveals a high occurrence of silenced T‐DNA integrations
Authors: Francis Kirk E. , Spiker Steven 
Published: November 2008

SummarySeveral recent investigations of T‐DNA integration sites in Arabidopsis thaliana have reported ‘cold spots’ of integration, especially near centromeric regions. These observations have contributed to the ongoing debate over whether T‐DNA integration is random or occurs preferentially in transcriptionally active regions. When transgenic plants are identified by selecting or screening for transgenic activity, transformants with integrations into genomic regions that suppress transcription, such as heterochromatin, may not be identified. This phenomenon, which we call selection bias, may explain the perceived non‐random distribution of T‐DNA integration in previous studies. In order to investigate this possibility, we have characterized the sites of T‐DNA integration in the genomes of transgenic plants identified by pooled polymerase chain reaction (PCR), a procedure that does not require expression of the transgene, and is therefore free of selection bias. Over 100 transgenic Arabidopsis plants were identified by PCR and compared with kanamycin‐selected transformants from the same T1 seed pool. A higher perceived transformation efficiency and a higher frequency of transgene silencing were observed in the PCR‐identified lines. Together, the data suggest approximately 30% of transformation events may result in non‐expressing transgenes that would preclude identification by selection. Genomic integration sites in PCR‐identified lines were compared with those in existing T‐DNA integration databases. In PCR‐identified lines with silenced transgenes, the integration sites mapped to regions significantly underrepresented by T‐DNA integrations in studies where transformants were identified by selection. The data presented here suggest that selection bias can account for at least some of the observed non‐random integration of T‐DNA into the Arabidopsis genome.
Scale effects and constraints for sound production in katydids (Orthoptera: Tettigoniidae): correlated evolution between morphology and signal parameters
Authors: MONTEALEGRE‐Z F. 
Published: November 2008

AbstractMale katydids (Orthoptera: Tettigoniidae) produce mating calls by rubbing the wings together, using specialized structures in their forewings (stridulatory file, scraper and mirror). A large proportion of species (ca. 66%) reported in the literature produces ultrasonic signals as principal output. Relationships among body size, generator structures and the acoustic parameters carrier frequency (fc) and pulse duration (pd), were studied in 58 tropical species that use pure‐tone signals. A comparative analysis, based on the only available katydid phylogeny, shows how changes in sound generator form are related to changes infcandpd. Anatomical changes of the sound generator that might have been selected viafcandpdare mirror size, file length and number of file teeth. Selection for structures of the stridulatory apparatus that enhance wing mechanics via file‐teeth and scraper morphology was crucial in the evolution of ultrasonic signals in the family Tettigoniidae.
Fitness differences associated withPgiSNP genotypes in the Glanville fritillary butterfly (Melitaea cinxia)
Authors: ORSINI L. , WHEAT C. W. , HAAG C. R. , KVIST J. , FRILANDER M. J. , HANSKI I. 
Published: November 2008

AbstractAllozyme variation at the phosphoglucose isomerase (PGI) locus in the Glanville fritillary butterfly (Melitaea cinxia) is associated with variation in flight metabolic rate, dispersal rate, fecundity and local population growth rate. To map allozyme to DNA variation and to survey putative functional variation in genomic DNA, we cloned the coding sequence ofPgiand identified nonsynonymous variable sites that determine the most common allozyme alleles. We show that these single‐nucleotide polymorphisms (SNPs) exhibit significant excess of heterozygotes in field‐collected population samples as well as in laboratory crosses. This is in contrast to previous results for the same species in which other allozymes and SNPs were in Hardy–Weinberg equilibrium or exhibited an excess of homozygotes. Our results suggest that viability selection favoursPgiheterozygotes. Although this is consistent with direct overdominance atPgi, we cannot exclude the possibility that heterozygote advantage is caused by the presence of one or more deleterious alleles at linked loci.
Pistil anatomy and pollen tube development in Polygala vayredae Costa (Polygalaceae)
Authors: Castro S. , Silva S. , Stanescu I. , Silveira P. , Navarro L. , Santos C. 
Published: November 2008

AbstractLow seed ovule ratios have been observed in natural populations of Polygala vayredae Costa, a narrowly endemic species from the oriental pre‐Pyrenees. To evaluate physical and nutritional constraints and pollen tube attrition in this endemic species, stigma and style anatomy, as well as pollen tube development along the pistil were investigated using light and fluorescence microscopy. The structural morphology of the stigmatic region was also examined with scanning electron microscopy. Pollen grains that reached the stigmatic papillae came into contact with a lipid‐rich exudate and germinated easily. Although a large number of pollen grains reach the stigmatic papillae, few pollen tubes were able to grow into the style towards the ovary. The style was hollow, with the stylar channel beginning a few cells below the stigmatic papillae. Initially, the stylar channel area was small compared to other levels of the style, and was surrounded by lipid‐rich, highly metabolic active cells. Furthermore, lipid‐rich mucilage was detected inside the stylar channel. At subsequent style levels towards the ovary, no major reserves were detected histochemically. The reduced intercellular spaces below the stigmatic papillae and the reduced area of the stylar channel at its commencement are suggested to physically constrain the number of pollen tubes that can develop. In subsequent levels of the style, the stylar channel could physically support a larger number of pollen tubes, but the lack of nutritional reserves cannot be disregarded as a cause of pollen tube attrition. Finally, the number of pollen tubes entering the ovary was greater than the number of ovules, suggesting that interactions occurring at this level play a major role in the final reproductive outcome in this species.
Effect of elevation on spatio‐temporal patterns of olive fly (Bactrocera oleae) populations in northern Greece
Authors: Kounatidis I. , Papadopoulos N. T. , Mavragani‐Tsipidou P. , Cohen Y. , Tertivanidis K. , Nomikou M. , Nestel D. 
Published: November 2008

AbstractThe spatio‐temporal patterns of olive fly populations in a managed olive‐growing region in the area of Chalkidiki in northern Greece were followed during 2005. The trapping grid consisted of 700 traps. Throughout the growing season (July–October), McPhail traps loaded with ammonium sulphate were inspected at 5‐day intervals. Trapping data were analysed using Getis–Ord local spatial statistics. Clustering of trapped flies was significantly related to elevation, which ranged from sea level to 700 m above sea level. The effect of elevation upon clustering depended on seasonal climatic patterns. During the summer, ‘hot‐spots’ (i.e. significant aggregations of captured insects) were located at intermediate to high elevations and ‘cold‐spots’ (i.e. areas with significantly low numbers of captured insects) were found in the valleys. In contrast, during the fall, ‘hot‐spots’ were detected at lower elevations and ‘cold‐spots’ at higher elevations. Population phenology seemed to affect spatial patterns. During periods of low population levels across the entire region, clusters of traps with relatively high amounts of captured insects were found at lower elevations. Pest management activities may have affected population levels throughout the region, but our data set does not allow quantifying their effectiveness. Our data suggest that differences in environmental temperature, as a result of altitudinal cline and season, may affect both the size of the olive fly population and its spatial patterns. The implementation of spatio‐temporal analyses for management of the olive fly is discussed.
Forms of Reproductive Disorders in Cattle and Buffaloes in Middle Egypt
Authors: Ali A , Abdel‐Razek A Kh , Derar R , Abdel‐Rheem HA , Shehata SH 
Published: November 2008

ContentsThe objective of this study was to investigate the common forms of reproductive disorders and trends of fertility in cattle and buffaloes in Middle Egypt, and investigate nutritional deficiencies or imbalances as a cause of infertility. During the period from 2003 to 2006 a total of 4276 animals (2755 cattle and 1521 buffaloes) were examined, during winter and summer at three districts of Middle Egypt. Based on the owner complains, animals were categorized as anestrum, repeat breeder and those for pregnancy diagnosis. Feedstuffs of these districts were assessed for nutrient and mineral contents. Animals were examined by rectal palpation and by transrectal ultrasonography. The results showed that, ovarian inactivity was the most common cause of anestrum, whereas endometritis was the main frequent finding of repeat breeding. District, season and year affected the incidences of infertility. The pregnancy rate remained constant (cattle) or increased (buffaloes) from 2003 to 2006. The incidence of ovarian inactivity in both species decreased over the same period. In winter, the commonly used feedstuffs would be adequate to supply the animals with needs, but in summer, rations seem to be deficient in many essential nutrients. In conclusion, ovarian inactivity is the main cause of infertility in cattle and buffaloes in Middle Egypt. There is a link between poor nutrition in summer and the high incidence of ovarian inactivity. Fertility trends during the past few years are encouraging.
Effects of Growth Hormone on Nuclear Maturation of Ovine Oocytes and Subsequent Embryo Development
Authors: Shirazi A , Shams‐Esfandabadi N , Ahmadi E , Heidari B 
Published: November 2008

ContentsThe objective of this study was to determine the effect of the presence of recombinant ovine growth hormone either alone or together with follicle stimulating hormone (FSH) during ovine oocyte in vitro maturation (IVM) on nuclear maturation and subsequent embryo development. Moreover, the effect of growth hormine (GH) on embryo development whether influenced by the presence of foetal bovine serum (FBS) was assessed. The abattoir‐derived oocytes were randomly divided into four treatment groups and cultured in maturation medium supplemented with: (i) 0.05 IU/ml FSH; (ii) 300 ng/ml roGH; (iii) FSH + roGH; and (iv) no FSH and GH (control). The percentages of germinal vesicle‐stage oocytes in GH‐treated group after 8 h of culture was significantly higher than the FSH and FSH + GH groups and lower than control (22.4%, 8.7%, 9.1%, and 32% respectively). The percentage of MII‐stage oocytes was significantly increased in the presence of GH after 16 and 24 h of culture compared to the control (44.7% and 83.1% vs 32.6% and 73.6% respectively). There was no significant synergism between GH and FSH in terms of nuclear maturation. The blastocyst rates in serum‐supplemented groups were enhanced by the presence of FSH and GH compared to the control (35.4% and 31.3 vs 11.4% respectively). Compared with either GH or FSH alone, the subsequent embryo development (blastocyst rate), however, was negatively influenced by co‐presence of both hormones (22.8%). In contrast, the corresponding values were not affected in the absence of serum. In conclusion, GH had positive effect on nuclear maturation of sheep oocytes. Moreover, the pattern of the effect of GH on embryo development was influenced by the presence of FBS during IVM.
Effect of hCG on Early Luteal Serum Progesterone Concentrations in PG600‐Treated Gilts
Authors: Manjarin R , Dominguez JC , Castro MJ , Alegre B , Driancourt MA , Kirkwood RN 
Published: November 2008

ContentsGilt oestrus and ovulation responses to injection of a combination of equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG) (PG600) can be unpredictable, possibly reflecting inadequate circulating LH activity. The objective of this study was to determine the effect of PG600 followed by supplemental hCG on gilt ovarian responses. In experiment 1, 212 Hypor gilts (160 day of age) housed on two farms in Spain received intramuscular (i.m.) injections of PG600 (n = 47), or PG600 with an additional 200 IU hCG injected either concurrently (hCG‐0; n = 39), or at 24 h (hCG‐24; n = 41) or 48 h (hCG‐48; n = 45) after PG600. A further 40 gilts served as non‐injected controls. Ovulation responses were determined on the basis of initial blood progesterone concentrations being <1 ng/ml and achieving >5 ng / ml 10 d after the PG600 injection. The incidence of ovulating gilts having progesterone concentrations >30 ng/ml were recorded. During the study period, 10% of control gilts ovulated whereas 85–100% of hormone‐treated gilts ovulated. There were no significant differences among hormone groups for proportions of gilts ovulating. The proportions of gilts having circulating progesterone concentrations >30 ng/ml were increased (p ≤ 0.02) in all hCG treated groups compared with the PG600 group. In experiment 2, a total of 76 Hypor gilts at either 150 or 200 days of age were injected with PG600 (n = 18), 400 IU eCG followed by 200 IU hCG 24 h later (n = 20), PG600 followed by 100 IU hCG 24 h later (n = 17), or 400 IU eCG followed by 300 IU hCG 24 h later (n = 21). Blood samples were obtained 10 days later for progesterone assay. There were no effects of treatment or age on incidence of ovulation, but fewer 150‐day‐old gilts treated with PG600 or 400 IU eCG followed by 200 IU hCG had progesterone concentrations >30 ng / ml. We conclude that hCG treatment subsequent to PG600 treatment will generate a higher circulating progesterone concentration, although the effect is not evident in older, presumably peripubertal, gilts. The mechanism involved and implications for fertility remain to be determined.
Baguio Mineral District: An oceanic arc witness to the geological evolution of northern Luzon, Philippines
Authors: Yumul Graciano P. , Dimalanta Carla B. , Tam Tomas A. , Ramos Estephanie Gera L. 
Published: November 2008

AbstractThe Baguio Mineral District exposes rock formations that evince the geological and tectonic evolution of this district from a subduction‐related marginal basin to an island arc setting. Available onshore and offshore data are consistent with an Early (onset phase) to Middle (developed phase) Miocene arc polarity reversal from the east (termination of subduction along the proto‐East Luzon Trough) to the west (initiation of subduction along the Manila Trench). Geophysical modeling and geochemical data calculation showed a 30 ± 5 km crustal thickness for the mineral district. Subduction‐related multiple arc magmatism and ophiolite accretion contributed to crustal thickening. Recent information on the Oligo–Miocene Zigzag and Klondyke formations in the mineral district reveal that the marginal basin, where these rocks were deposited, has received eroded materials from adjacent terrains characterized by siliceous lithologies. Furthermore, adakitic rocks, high permeable zones and extensional zones which are exploration markers applied to identify possible mineralization targets, are prevalent in the mineral district. The geological evolution that the district had undergone mimics the evolution of island arcs worldwide in general and northern Luzon in particular.
K‐ and Si‐rich glasses in harzburgite from Damaping, north China
Authors: Zhu Yongfeng 
Published: November 2008

AbstractA study of potassium‐ and silica‐rich glass (SiO2 = 65.3–67.4%, K2O = 7.1–9.8%, Na2O = 4.4–6.5%) in spongy clinopyroxene rims from anhydrous spinel harzburgite, collected from Damaping (Hannuoba, north China), is reported here. The corroded surface of clinopyroxene along with clear chemical zonation (homogeneous core and partially melted rim) suggests that incongruent melting of primary clinopyroxene is responsible for generating the Si‐rich glass in clinopyroxene rims. The degree of clinopyroxene melting is estimated to be higher than 15%. In order to generate glass with K2O contents of 7.0 to 9.8% by clinopyroxene melting at a degree of 15% in a closed system, K2O contents in the primary clinopyroxene should be greater than 1.0 wt%, suggesting a very deep origin for the Damaping harzburgite.
The role of HPV testing in patients with possible high‐grade cervical cytology
Authors: Rao Archana , Pather Selvan , Dalrymple Chris , Mackie Adam , Deans Rebecca , Carter Jonathan 
Published: November 2008

AbstractAim:  To assess the role of human papillomavirus (HPV) testing for high‐risk types in an Australian population with the equivalent cytological result of atypical squamous cells of undetermined significance – possible high‐grade (ASC‐H).Methods:  A retrospective review was conducted of all patients referred with a ‘possible high‐grade squamous abnormality’ Pap‐smear result who underwent HPV testing for 13 high‐risk types, colposcopy and directed biopsy, and any subsequent treatment.Results:  The study included 100 patients. Overall, 79% of patients had a positive test for high‐risk HPV DNA types. Histopathology was available for 98 patients and demonstrated that 47% of patients had confirmed high‐grade dysplasia. HPV testing had a high sensitivity (98%), but low specificity (40%) for the detection of high grade dysplasia, and a negative predictive value of 95%.Conclusions:  The results of this study suggest that among patients with the equivalent of ASC‐H cytology, a negative HPV DNA test for high‐risk types is a good predictor of the absence of high‐grade dysplasia. HPV testing in this patient population therefore has the potential to reduce the number women referred for colposcopy.