bluuebunny/crossref_metadata_2025 huggingface dataset:
Fitness cost of parasitoid avoidance behavior in the arrowhead scale, Unaspis yanonensis Kuwana
Authors: Matsumoto Takashi , Itioka Takao , Nishida Takayoshi
Published: October 2003

We examined trade‐offs between fitness components and the parasitoid avoidance behavior of the arrowhead scale, Unaspis yanonensis Kuwana (Homoptera: Diaspididae). We examined the performance of two settling modes: singleton and double settling with the burrower under the burrowee. Each of these modes differs in vulnerability to parasitism by Aphytis yanonensis DeBach et Rosen and Coccobius fulvus Compere et Annecke (Hymenoptera: Aphelinidae), and performance. Field and laboratory observations revealed smaller body size and lower parasitism of burrower scales, while both singletons and burrowees showed the opposite tendency (larger body size and a greater parasitism rate). Laboratory observations under parasitoid‐free conditions revealed greater mortality and reduced growth rate for simulated burrowers than for singletons during the 40‐day nymphal period. This suggests that competition for food resources reduces performance. The results also suggest trade‐offs between parasitoid avoidance and resource acquisition ability in U. yanonensis. The trade‐offs also explain our previous findings, that introduction of the parasitoids increased the proportion of burrowers, but that within seven years equilibrium was reached at fairly low levels (ca. 5%) in the field, even under intense parasitism.
The effect of stem diameter on European corn borer behavior and survival: potential consequences for IRM in Bt‐corn
Authors: Losey John E. , Carter Maureen E. , Silverman Susan A.
Published: October 2003

The ability of non‐crop plants to support complete development of insect pests is an important factor for determining the impact of those plants on resistance management programs for transgenic crops. We assessed the effect of one physical factor, plant stem diameter, on the ability of plants to support full development of the European corn borer (ECB), Ostrinia nubilalis Hübner (Lepidoptera: Crambidae), the target pest of transgenic Bt‐corn. In the field, European corn borer larvae were significantly more likely to tunnel and survive in plants with larger stem diameters. Larvae were 40× more likely to survive on corn, the largest plant tested, compared to many of the smaller plants. In the laboratory, larvae were more likely to survive in and less likely to abandon the largest diet‐filled artificial stems that varied only in stem diameter. In conditions simulating those that an ECB larvae would encounter upon abandoning a host, larvae survived up to three weeks and were able to locate corn as a new host with a significantly higher frequency than would be expected if they were foraging randomly. These results indicate that the probability of ECB larval survival to maturity on a plant other than corn is relatively low and thus these smaller stemmed non‐corn plants may not make a substantial contribution to the pool of susceptible adults. Conversely, since more mature larvae are not as susceptible as neonates, any larvae that partially develop on non‐corn plants and subsequently colonize Bt‐corn may not be exposed to a lethal dose of the toxin. Since some proportion of the individuals that survive could be partially resistant heterozygotes the presence of non‐corn host plants could facilitate the development of resistant ECB populations.
Interspecific competition between the braconid endoparasitoids Glyptapanteles porthetriae and Glyptapanteles liparidis in Lymantria dispar larvae
Authors: Marktl Robert C. , Stauffer Christian , Schopf Axel
Published: October 2003

The effect of interspecific competition between the solitary endoparasitoid Glyptapanteles porthetriae Muesebeck (Hymenoptera: Braconidae) and the gregarious Glyptapanteles liparidis Bouché (Hymenoptera: Braconidae), was investigated in larvae of Lymantria dispar L. (Lepidoptera: Lymantriidae). Host larvae were parasitized by both wasp species simultaneously in premolt to the 2nd or the 3rd host instar or in an additional approach with a 4‐day delay in parasitization by the second wasp species. Host acceptance experiments revealed that both wasp species do not discriminate between unparasitized host larvae and larvae parasitized previously by the same or the other species. In more than 90% female wasps parasitized the larva they encountered first. During the period of endoparasitic development, larvae of the competing parasitoid species never attacked the egg stage of the other species. When host larvae were parasitized simultaneously by both wasp species, the rate of successful development of both species depended on the age of the host larva at the time of its parasitization; G. liparidis emerged successfully from 44% of host larvae parasitized during the premolt to 2nd instar, G. porthetriae from 28%, and in 20% of the hosts both parasitoid species were able to develop in one gypsy moth larva. However, when host larvae were parasitized simultaneously during premolt to the 3rd instar, G. liparidis was successful in 90% of the hosts, compared to 8% from which only G. porthetriae emerged. In the experiments with delayed oviposition, generally the species that oviposited first succeeded in completing its larval development. Larvae of the species ovipositing with four days delay were frequently attacked and killed by larvae of the first parasitizing species or suffered reduced growth. As the secondary parasitoid species, G. porthetriae‐larvae were never able to complete their development, whereas G. liparidis developed successfully in at least 12,5% of the multiparasitized host larvae. Thus, multiparasitism of gypsy moth larvae by both Glyptapanteles species corresponds to the contest type; however, G. porthetriae is only able to develop successfully as the primary parasitoid of young host larvae.
Host recognition in the pupal parasitoid Trichopria drosophilae: a morpho‐functional approach
Authors: Romani Roberto , Isidoro Nunzio , Bin Ferdinando , Vinson S. Bradleigh
Published: October 2003

The diapriid wasp Trichopria drosophilae Perkins (Hymenoptera: Diapriidae) attacks and develops in puparia of the common fruit fly, Drosophila melanogaster Meigen (Diptera: Drosophilidae). Host recognition of T. drosophilae was studied using both a morphological and behavioural approach. Scanning and electron microscopical observations of female parasitoid antennae showed the presence of two types of sensilla, which we named MGS1 and MGS2. The former are present on the ventral side of both the apical (A11) and sub‐apical (A12) antennomeres, while the latter occur only on A12. Ultrastructural features suggest a gustatory function for these sensilla. Arena bioassays using intact or antennaectomised females and intact host puparia showed that MGS2 are necessary for achieving host acceptance. Further bioassays, where the host's anterior spiracles were covered with wax, led to a very low level of host acceptance. We suggest that the secretion produced by glands associated with the anterior spiracles act as a contact kairomone, which has to be perceived by MGS2 in order to elicit host recognition. The removal of both the female apical antennomeres (A12) led to the failure of the parasitoid to recognize its host.
The role of glucosinolates and their hydrolysis products in oviposition and host‐plant finding by cabbage webworm, Hellula undalis
Authors: Mewis I. , Ulrich Ch. , Schnitzler W.H.
Published: October 2003

The cabbage webworm, Hellula undalis (Fabricius) (Lepidoptera: Pyralidae), a tropical pest on crucifers (Brassicaceae), differentiated among host‐plant species for oviposition in laboratory and field tests. White mustard, Sinapis alba (L.) var. Selinda, was the preferred host‐plant, followed by Brassica juncea (L.) Czern. et. Coss var. Canadian brown mustard, and pak‐choi, Brassica campestris L. ssp. chinensis var. Joi Choi, Black Behi and Bai Tsai. Glucosinolates (GS), secondary plant compounds characteristic to the Cruciferae plant family, and their breakdown products were analyzed by using HPLC and GC‐MS‐techniques. Species differed in GS composition and concentration. Content of GS was highest in S. alba with progressively lower contents detected in B. juncea and B. chinensis. The aromatic GS, 4‐hydroxybenzyl‐GS and benzyl‐GS, were detected in S. alba. In B. juncea the alkenyl GS, allyl‐GS, dominated, whereas in varieties of B. chinensis indolyl and alkenyl GS predominated. Oviposition of H. undalis females on the non‐host‐plant Vigna unguiculata ssp. sesquipedalis (L.) Fruwirth was stimulated by application of GS extracts from the crucifer species; the extract from S. alba was preferred, followed by extracts from B. juncea and B. chinensis. Hydrolysis of GS in the plant extract from B. chinensis causes loss of the oviposition stimulatory effect of the extract. Application of the GS, allyl‐GS, and benzyl‐GS also stimulated oviposition by H. undalis. Significantly more eggs were laid on leaves treated with the aromatic GS, benzyl‐GS, than with the alkenyl GS, allyl‐GS. Host‐plant odor attracted H. undalis females but not males, in behavioral assays conducted in a Y‐tube olfactometer. Low concentrations of the GS hydrolysis product, allyl‐isothiocyanate, induced anemotaxis of females, but a high concentration of allyl‐isothiocyanate was repellent. Oviposition by H. undalis females was not stimulated by host‐plant volatiles. Females laid eggs on inserted traps and the walls of the Y‐tube regardless of presence or absence of host‐plant odor. The relevance of these results in the context of crucifer‐insect interactions is discussed.
Trap cropping effect on oviposition behaviour of the leek moth Acrolepiopsis assectella and the diamondback moth Plutella xylostella
Authors: Åsman Karolina
Published: October 2003

The potential of trap cropping as a pest control strategy was explored for two specialist moth species, where oviposition behaviour determines larval distribution. Oviposition behaviour was studied at three different scales: Individual plants in the laboratory, small scale field experiments with and without cages, and medium scale field trials. The study insects were the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), a specialist on Brassica species and the leek moth, Acrolepiopsis assectella (Z.) (Lepidoptera: Acrolepiidae), a specialist on Allium species. The diamondback moth preferred Indian mustard, Brassica juncea (L.) over white cabbage, B. oleracea var alba (L.). The leek moth did not show preference when offered leek, Allium porrum (L.) and chives, A. schoenoprasum (L.). However, the leek moth did prefer to oviposit on plants of a larger biomass over smaller plants. In both the small scale and the medium scale field studies the trap crops reduced the number of eggs laid on the primary crop. The total number of eggs laid in the monoculture and the trap crop treatments were the same in the small scale field cage study, but the females distributed their eggs differently. More eggs were laid on trap crops compared with primary crops and this pattern was also validated in the medium scale field trials. In this study only the direct effects of trap cropping were considered. Indirect effects of vegetation diversity such as enhancement of natural enemies could potentially increase the efficacy of trap cropping.
Death from donor-transmitted malignancy despite emergency liver retransplantation
Authors: Lipshutz Gerald S. , Baxter-Lowe Lee Ann , Nguyen Tim , Jones Kirk D. , Ascher Nancy L. , Feng Sandy
Published: October 2003

Transplantation of organs procured from donors with malignancies identified subsequent to implantation presents a significant dilemma regarding the optimal management strategy to simultaneously minimize the risk for cancer transmission and recipient morbidity. In this report, we present a patient who underwent orthotopic liver transplantation for hepatitis B cirrhosis. The donor had no previous history of cancer. On autopsy, enlarged mediastinal lymph nodes led to the discovery of a 1-cm lung tumor. Histological examination showed pulmonary adenocarcinoma with metastatic mediastinal disease. Despite urgent retransplantation within 7 days, the recipient developed metastatic pulmonary adenocarcinoma diagnosed 11 months after transplantation and died soon thereafter. Analysis of short tandem repeat regions of chromosomal DNA from the recipient, the 2 liver donors, and the posttransplantation tumor corroborates that the first donor was the source of the malignancy. This case of donor-transmitted malignancy underscores the need for vigilance by the procuring surgeon in identifying potential malignancy during organ retrieval and use of a full autopsy on selected donors after organ procurement. (Liver Transpl 2003;9:1102-1107.)
Sequence variation in the hypervariable region 1 of hepatitis C virus and posttransplantation recurrent hepatitis
Authors: Silini Enrico , Belli Luca , Brambilla Sabrina , Foti Luciana , Gritti Chiara , Lisa Antonella , Alberti Alberto Battista , Vinci Marilina , De Carlis Luciano , Rondinara Gianfranco , Pinzello Giovanbattista
Published: October 2003

Hepatitis C virus (HCV) shows remarkable genetic variation in both populations and individuals, in whom it circulates as quasispecies (QS). Sequence variation within an infected host has adaptive significance and reflects the modes and intensity of selection mechanisms operating on the virus. We investigated the sequence diversity of hypervariable region 1 of HCV in liver transplant recipients and correlated it with the recurrence of hepatitis. Twenty-six patients were considered during a 2-year period; all had graft reinfection, and 14 patients developed hepatitis recurrence. Cloned sequences were obtained from sera collected before or within 1 month after orthotopic liver transplantation (OLT) and at 3 and 24 months thereafter. Sequence diversity within single sera and over consecutive samples was analyzed quantitatively by matrix comparison and phylogenetic analysis. Propagation of viral QS in the graft was markedly dependent on individual factors. Viral QS in post-OLT sera were less complex and evolved slower compared with immunocompetent subjects with chronic hepatitis. Sequence variation was greater during the first 3 months post-OLT than during the remaining period. Genetic diversity within single samples was not related to hepatitis recurrence or other clinical features. Conversely, sequence diversity over consecutive samples was reduced in patients who experienced hepatitis recurrence, in particular, in those infected with genotype 1b and with an HLA-DR mismatched graft. Selection of viral sequences was markedly impaired in liver transplant recipients and tended to be greater early after OLT. Reduced sequence turnover correlated negatively with the outcome of graft reinfection.
Poor survival after liver retransplantation: Is hepatitis C to blame?
Authors: Watt Kymberly D.S. , Lyden Elizabeth R. , McCashland Timothy M.
Published: October 2003

Data from 1990 to 1996 suggest that the prevalence of hepatitis C virus (HCV) infection in repeated orthotopic liver transplantation (re-OLT) is increasing, and patient survival may be worse. Aims of the study are to: (1) assess the prevalence of HCV in re-OLT, (2) compare survival between primary OLT and re-OLT for HCV versus non-HCV diseases, and (3) evaluate Model for End-Stage Liver Disease (MELD) scores in re-OLT. The United Network for Organ Sharing database for adult patients undergoing primary OLT or re-OLT from January 1996 to June 2002 was analyzed. Patients with malignancy or those who underwent re-OLT within 30 days of primary OLT were excluded. A total of 22,120 primary OLTs and 2,129 re-OLTs were performed. HCV was noted in 9,564 primary OLTs (43.2%) and 899 re-OLTs (42.2%). Overall 1, 3, and 5-year patient survival rates were 86%, 79%, and 73% for primary OLT, but 67%, 56%, and 52% for re-OLT (P < .001). Survival rates of patients with HCV at 1, 3, and 5 years were 86%, 76%, and 68% for primary OLT and 61%, 50%, and 45% for re-OLT (P < .001). Survival was less for patients with HCV compared with those with autoimmune hepatitis (AIH) and hepatitis B for re-OLT (P < .01). However, survival after re-OLT was no different for those with HCV than for those with all other causes. MELD scores between 11 and 20 were the most common for re-OLT. A marked decreased in survival was noted in all patients who underwent re-OLT with MELD scores greater than 25. HCV prevalence in OLT has reached a plateau in recent years. Survival after re-OLT is inferior to that for primary OLT, but re-OLT survival appears to have improved. Survival after re-OLT is lower in patients with HCV compared with those with AIH and hepatitis B, but no different than for those with most other liver diseases. Survival appeared worse in patients who underwent re-OLT with a MELD score greater than 25.
Generation of hepatocytes from cultured mouse embryonic stem cells
Authors: Kuai Xiao Ling , Cong Xiao Qian , Li Xiu Lan , Xiao Shu Dong
Published: October 2003

Embryonic stem (ES) cells are pluripotent cells derived from the inner cell mass of fertilized blastocysts in vitro. ES cells can be induced to undergo differentiation into potentially all cell types. The aim of this study is to examine the differentiating potential of mouse ES cells into hepatocytes in the presence of retinoic acid (RA), hepatocyte growth factor (HGF), and β-nerve growth factor (β-NGF). RA, HGF, and β-NGF were added to the cell culture. Hepatocyte induction was confirmed morphologically, as well as biochemically, through immunohistochemical assays of α1-antitrypsin (α1-AT) and alfafetaprotein (AFP) expression and reverse-transcriptase polymerase chain reaction tests for the presence of albumin, transthyretin, glucose 6 phosphates, hepatic nuclear factor 4, and SAPK/ERK kinase-1 (SEK1) messenger RNA, produced only by functioning hepatocytes. Fifteen days after the addition of HGF and β-NGF to the cell culture, many epithelioid cells were noticed. α1-AT, AFP, albumin, transthyretin, glucose 6 phosphates, hepatic nuclear factor 4, and SEK1 messenger RNA expression also was detected, indicating successful ES cell differentiation into functioning hepatocytes. However, in the presence of RA alone, only transthyretin messenger RNA was positive, whereas no other expression pertaining to functioning hepatocytes could be detected. In the presence of HGF and β-NGF, mouse ES cells can differentiate into functioning hepatocytes, whereas RA function is limited.
Outcomes of hepatitis C- and hepatitis B core antibody-positive grafts in orthotopic liver transplantation
Authors: Saab Sammy , Chang Albert J. , Comulada Scott , Geevarghese Sunil K. , Anselmo Dean R.M. , Durazo Francisco , Han Steven , Farmer Douglas G. , Yersiz Hasan , Goldstein Leonard I. , Ghobrial Mark R. , Busuttil Ronald W.
Published: October 2003

The use of hepatitis B core antibody (HBcAb)- and hepatitis C virus antibody (HCV+) liver grafts for transplantation in selected populations has not affected patient and graft survival. We reexamined the clinical outcomes of using these HBcAb+ and HCV+ grafts at our institution, in addition to studying recipients of combined HBcAb+/HCV+ grafts. We identified 377 patients who underwent transplantation for either hepatitis B and/or hepatitis C, or received both HBcAb+ and HCV+ grafts. Patient and graft survival at 5 years posttransplantation was 73% and 71%, respectively, in the HBcAb+ grafts compared with 81% and 75% in the HBcAb− grafts (P = .65; P = .94). For HCV+ grafts, patient and graft survival at 5 years posttransplantation was 89% and 73%, respectively, compared with 69% and 59% in the HCV− grafts; (P = .22; P = .77). The 5-year patient and graft survival rate in those who received combined HBcAb+/HCV+ grafts was 74% and 69%, respectively, and there was no statistical difference compared with the HBcAb+ and HCV+ grafts (P = .76; P = .90). The 5-year patient and graft survival rate in patients who received dual HBV prophylaxis with hepatitis B immunoglobulin (HBIg) and lamivudine was 88% and 84%, respectively, which was significantly higher than for patients who received single prophylaxis or no prophylaxis (P < .01; P = .02). Our study supports previous observations that patient and graft survival is not affected with the use of HBcAb+ and HCV+ grafts, and that dual prophylaxis with HBIg and lamivudine offers substantial survival benefits. Furthermore, the use of combined HBcAb+/HCV+ grafts did not impact patient or graft survival. This provides a potential new pool of donor livers that can be used for transplantation in select patients.
Positive T lymphocytotoxic cross-match in living donor liver transplantation
Authors: Sugawara Yasuhiko , Makuuchi Masatoshi , Kaneko Junichi , Kishi Yoji , Hata Shojiro , Kokudo Norihiro
Published: October 2003

The influence of lymphocytotoxic cross-match on survival or acute rejection in living donor liver transplantation (LDLT) has not been well examined. We analyzed 133 consecutive adult LDLT cases and assessed patient survival and acute rejection rates. Patients with a positive T lymphocytotoxic cross-match (n = 12) had a significantly higher chance of rejection within 6 weeks of LDLT (67% versus 28%, P < .001). All of the rejection episodes were successfully treated with bolus methylprednisolone therapy or anti-T cell monoclonal antibody. T lymphocytotoxic cross-match-positive grafts had no influence on patient survival (79% versus 90% at 3 years, P = .91). The results show that a positive cross-match graft should not be considered a contraindication for LDLT.
Increased risk of cholestatic hepatitis C in recipients of grafts from living versus cadaveric liver donors
Authors: Gaglio Paul J. , Malireddy Srikar , Levitt Brian S. , Lapointe-Rudow Dianne , Lefkowitch Jay , Kinkhabwala Milan , Russo Mark W. , Emond Jean C. , Brown Robert S.
Published: October 2003

Histologic injury caused by recurrent hepatitis C virus (HCV) has been reported in up to 90% of HCV-infected patients who undergo liver transplantation with a cadaveric graft. However, the natural history of HCV after living donor liver transplantation (LDLT) is not well described. We performed a retrospective analysis of 68 consecutive HCV-infected adult patients: 45 recipients of cadaveric grafts (CAD) were compared with 23 LDLT patients. Elevated serum transaminases, positive HCV RNA, and liver biopsy consistent with histologic evidence of HCV defined recurrence. When comparing CAD with LDLT, both the incidence of HCV recurrence and time to recurrence were not different. The overall incidence of severe sequelae of HCV recurrence, either cholestatic hepatitis, grade III-IV inflammation, and/or HCV-induced graft failure requiring retransplantation, was also not different when comparing CAD with LDLT. However, when comparing CAD versus LDLT, no CAD patient developed cholestatic hepatitis C, compared with 17% of LDLT who developed this complication (P = .001). Thus, in this patient population, the timing and incidence of HCV recurrence were not different when comparing CAD versus LDLT, but the incidence of cholestatic hepatitis was significantly greater in patients with HCV who underwent LDLT.
Recurrence of primary biliary cirrhosis after liver transplantation: Histologic estimate of incidence and natural history
Authors: Sylvestre Pamela B. , Batts Kenneth P. , Burgart Lawrence J. , Poterucha John J. , Wiesner Russell H.
Published: October 2003

The goals of this study were to determine the rate of recurrent primary biliary cirrhosis (PBC) after orthotopic liver transplantation (OLT) based on strict morphologic criteria and to evaluate histologic progression of recurrent PBC over time. Strict criteria for PBC recurrence were established as the presence of a florid duct lesion or destructive lymphocytic cholangitis within a dense portal infiltrate. Of the 784 OLTs performed at the Mayo Clinic during the first 12 years of the program, 100 met criteria for the PBC study group, and 35 met criteria for the control group. Strict histologic criteria for recurrent PBC were observed in 17 of 100 (17%) study patients (14 with florid duct lesion, 3 with destructive lymphocytic cholangitis within dense portal infiltrate). Mean follow-up for the PBC group was 4.7 years (range, 1.0 to 13.8). Mean time to recurrence was 3.7 years (median, 3.1; range, 0.3 to 7.9). In those who met strict criteria for recurrent PBC, 2 of 17 progressed to septal fibrosis (stage 3). No florid duct lesions, destructive lymphocytic cholangitis, or septal fibrosis were observed in the control group. Other less specific morphologic features of PBC (portal infiltrates, plasma cells, dense lymphoplasmacytic infiltrates, and lymphocytic cholangitis) were also evaluated in the course of this study. Based on strict criteria, a conservative histologic estimate of the rate of recurrent PBC is 17% with a mean of 4.7 years of follow-up. When criteria for histologic recurrence are expanded to include moderate lymphocytic cholangitis with lymphoplasmacytic portal infiltrate, the recurrence rate of PBC is estimated as 26%.
Population Genetics of IndigenousQuercus roburL. Populations and of Derived Half‐Sib Families has Implications for the Reproductive Management of the Species
Authors: Bakker E. G. , Van Dam B. C. , Van Eeuwijk F. A. , Jacobsen E.
Published: October 2003

Abstract:In the Netherlands indigenousQuercus roburL. populations are rare and have been maintained as patches in ancient woodland. For adequate conservation of these populations, information about genetic variation and population structure is necessary. In order to assess the genetic variation and structure of these populations, microsatellite polymorphisms were studied in two autochthonous populations. These two populations differed slightly for their gene diversity, which was as high as was observed forQ. roburpopulations in France and Germany. For reforestation purposes there is an interest in the genetic variation of a half‐sib family harvested from one tree. The gene diversity of the two studied half‐sib families ‐ obtained from a forest and an urban area ‐ was similar, but relatively low. This indicates that, for reforestation purposes, seeds should be harvested from many different trees in order to obtain a population with a genetic variation as high as was observed for an autochthonous population.
Accessory Pollen Adhesive from Glandular Trichomes on the Anthers of Leonurus sibiricus L. (Lamiaceae)
Authors: Moyano F. , Cocucci A. , Sérsic A.
Published: October 2003

Abstract: Glandular trichomes (ca. 16 per anther) on the anthers of Leonurus sibiricus produce a secretion that, when touched, is liberated at once and becomes sticky when in contact with the air. With successive visitations of the pollinators (species of Bombus in naturalized populations) the number of secretion‐containing glands on each anther diminishes by mechanical rupture. On the pollinators, the secretion mixed with pollen was found adhered to the integument on the parts making contact with the anthers and stigma, mostly on the scape of the antennae. These trichomes are anatomically identical to the glandular scales common in the entire family and are formed by a multicellular cuticle‐bounded structure, with a foot and head. The secretion is accumulated as a milky emulsion under the cuticle, outside the primary cell wall, and is liberated by rupture of the cuticle. The composition possibly differs from what generally distinguishes these glandular trichomes, i.e. volatile oils that give these plants their particular smell. Such volatile compounds are generally assumed to have defensive or attractive functions, different from those observed in this study, which would be strictly mechanical.
Homomorphic Self‐Incompatibility, with Stylar Rejection Site, in Luehea grandiflora Mart. and Zucc. (Tiliaceae‐Malvaceae s.l.)
Authors: Gibbs P. E. , Oliveira P. E. , Taroda Ranga N.
Published: October 2003

Abstract: The breeding system of Luehea grandiflora (Tiliaceae‐Malvaceae s.l.) was investigated using hand pollinations and fluorescence microscopy studies of pollen tube growth. Although selfed flowers persisted for some 10 days, our study indicates that L. grandiflora is self‐incompatible, with self pollen tube inhibition in the upper style, as occurs in many taxa with homomorphic, gametophytic self‐incompatibility (GSI). L. grandiflora is only the second species reported within the Malvales with homomorphic stylar inhibition. This result is discussed within the context of a report for self‐compatibility in this species, and we also consider the phylogenetic implications for the occurrence of GSI in the family Malvaceae s.l.
Daucus carota Cells Contain Specific DNA Methyltransferase Inhibitors that Interfere with Somatic Embryogenesis
Authors: Pedrali‐Noy G. , Bernacchia G. , do Rosario Alvelos M. , Cella R.
Published: October 2003

Abstract: Results reported in this paper show that carrot cells contain a thermostable inhibiting activity for cytosine‐5‐DNA methyltransferase that, upon filtration chromatography, can be resolved into three major peaks. Inhibiting activity was found in all plant species tested, though at a concentration lower than in carrot. These inhibiting activities differ in size, sensitivity to various hydrolytic treatments, specificity for DNA METases of eukaryotic and bacterial origin and kinetics of inhibition. Results of chemical analyses indicate that the inhibitors differ from lipidic inhibitors described in Escherichia coli and Streptomyces sp. and, given their sensitivity to proteinase K, appear to have a proteinaceous nature. The addition of these inhibitors (Sephadex G25 peak II and peak III) to actively growing suspension rice cells reduced the rate of in vivo DNA methylation without interfering with DNA synthesis. Peak II also induced a general demethylation effect in carrot cell suspension, even if weaker than that caused by 5‐azacytidine. Interestingly, inhibitors suppressed carrot embryogenesis but did not prevent undifferentiated cell proliferation of suspension cultures.
Evolution of Protein Targeting into “Complex” Plastids: The “Secretory Transport Hypothesis”
Authors: Kilian O. , Kroth P. G.
Published: October 2003

Abstract: In algae different types of plastids are known, which vary in pigment content and ultrastructure, providing an opportunity to study their evolutionary origin. One interesting feature is the number of envelope membranes surrounding the plastids. Red algae, green algae and glaucophytes have plastids with two membranes. They are thought to originate from a primary endocytobiosis event, a process in which a prokaryotic cyanobacterium was engulfed by a eukaryotic host cell and transformed into a plastid. Several other algal groups, like euglenophytes and heterokont algae (diatoms, brown algae, etc.), have plastids with three or four surrounding membranes, respectively, probably reflecting the evolution of these organisms by so‐called secondary endocytobiosis, which is the uptake of a eukaryotic alga by a eukaryotic host cell. A prerequisite for the successful establishment of primary or secondary endocytobiosis must be the development of suitable protein targeting machineries to allow the transport of nucleus‐encoded plastid proteins across the various plastid envelope membranes. Here, we discuss the possible evolution of such protein transport systems. We propose that the secretory system of the respective host cell might have been the essential tool to establish protein transport into primary as well as into secondary plastids.
Photobiont Selectivity and Interspecific Interactions in Lichen Communities. I. Culture Experiments with the Mycobiont Fulgensia bracteata
Authors: Schaper T. , Ott S.
Published: October 2003

Abstract: Lichen communities are characterised by interspecific interactions that not only include interactions between different lichen species but also between the symbionts within a single lichen species. The community “Bunte Erdflechtengesellschaft”, growing on weathered calciferous rocks known as Gravel Alvar on Gotland (Baltic Sea, Sweden), shows a high complexity of inter‐ and intraspecific interactions, including Fulgensia bracteata, F. fulgens, Toninia sedifolia, Squamarina cartilaginea, Psora decipiens and Lecidea lurida. F. bracteata and F. fulgens are the dominant species of this community, showing a tendency to overgrow the other species involved and even parasitic behaviour. Culture experiments have been performed to investigate the selectivity of the mycobiont of F. bracteata towards a variety of potential photobionts. The results provide evidence for the selectivity of the mycobiont and varying compatibility of the respective symbionts that can be interpreted as a cascade of interdependent processes of specific and non‐specific reactions of the symbionts involved.
Emission of Methane and Nitrous Oxide by Australian Mangrove Ecosystems
Authors: Kreuzwieser J. , Buchholz J. , Rennenberg H.
Published: October 2003

Abstract: The fluxes of the greenhouse gases methane (CH4) and nitrous oxide (N2O) were measured in mangrove wetlands in Queensland, Australia, using the closed chamber technique. Large differences in the fluxes of both gases from different study sites were observed, which presumably depended on differences in substrate availability. CH4 emission rates were in the range of 20 to 350 μg m‐2 h‐1, whereas N2O fluxes were lower, amounting to ‐ 2 to 14 μg m‐2 h‐1. In general, the field sites with high substrate availability showed higher emissions than sites with poor nutrient supply. This assumption is supported by the observation of dramatically increased N2O emissions (150 ‐ 400 μg m‐2 h‐1) if study sites were artificially fertilised with additional N. As expected, N fertilisation did not alter CH4 fluxes during the period of investigation. In the present study, it was confirmed that the mangrove vegetation may play a role as a transport path for CH4 and N2O by facilitating diffusion out of the soil. Prop roots from Rhizophora stylosa emitted CH4 and N2O at rates of 2.6 and 3.3 μg m‐2 root surface h‐1, respectively, whereas the soil of this stand acted as a sink for CH4. As a consequence, the ecosystem as a whole could constitute a CH4 source despite CH4 uptake by the soil. In contrast to prop roots, the presence of pneumatophores in Avicennia marina led to a significant increase in CH4 emissions from mangrove soils, but did not enhance N2O emissions. These findings indicate that mangrove ecosystems may be considered a significant source of N2O and that anthropogenic nutrient input into these ecosystems will lead to enhanced source strengths. For an up‐scaling of greenhouse gas emissions from mangrove forests to a global scale, more information is needed, particularly on the significance of vegetation.
High Temperature Effects on Light Sensitivity in the Two High Mountain Plant Species Soldanella alpina (L.) and Rannunculus glacialis (L.)
Authors: Streb P. , Aubert S. , Bligny R.
Published: October 2003

Abstract: The susceptibility to high temperature‐induced photoinhibition was investigated in leaves of two high mountain plant species, S. alpina and R. glacialis. In both species, PSII was similarly photoinactivated at 38 °C in the light. However, recovery from damage was much faster in S. alpina and depended on protein synthesis. In contrast, recovery was independent from protein synthesis in R. glacialis. Heat‐induced photoinactivation in both species was accompanied by: (1) a decrease in relative photosynthetic electron transport rates, (2) an increase in non‐photochemical chlorophyll fluorescence quenching, (3) a strong accumulation of zeaxanthin, (4) a marked decrease in soluble carbon metabolites and (5) an increase in lipid metabolism products, which was more pronounced in R. glacialis than in S. alpina. These results indicate that carbon assimilation was inhibited and that membranes were affected. Lipid peroxidation and possible membrane disintegration might limit the repair of damaged PSII in R. glacialis, while S. alpina appears to be protected by carotenoids and antioxidants. A marked decrease in α‐tocopherol content and an increase in reduced ascorbate indicated lipid peroxide scavenging activity in S. alpina. When zeaxanthin synthesis was impaired by DTT, photoinhibition increased and α‐tocopherol accumulated in R. glacialis. The increased susceptibility of R. glacialis leaves to light‐induced photoinhibition after growth at moderate temperature (Streb et al., 2003a) and the inability to repair heat‐induced damage might limit the distribution of R. glacialis to lower altitudes in the Alps.
Cytochemical Localization of Phenolic Compounds in Columella Cells of the Root Cap during Maturation of Seeds of Brassica napus L.
Authors: Stefanowska M. , Zobel A. M. , Kuraś M.
Published: October 2003

Abstract: Ultrastructural localization of phenolic compounds in the columella of the root cap of a canola embryo in Brassica napus L. during subsequent seed maturation stages was investigated. In bright green seeds the first signs of maturation and appearance of the first phenolic structures in the cell nuclei and cytoplasm in the area of the initial centre were found. Phenolics spread acropetally, gradually covering the whole columella in the dark green seeds. An increase in the number of phenolics occurred, together with an increase in the number of endoplasmic reticulum structures and in storage materials. In brown seeds, together with ultrastructural degradation and the end of production of storage substances, the number of phenolic deposits in the nucleus and cytoplasm decreases until their disappearance in black dormant seeds. Simultaneously, numerous phenolic deposits appear between the plasmalemma and the cell walls in the outer layer of the cap columella.
Characterisation of the Chloroplast DNA psbT‐H Region and the Influence of Dyad Symmetrical Elements on Phylogenetic Reconstructions
Authors: Quandt D. , Müller K. , Huttunen S.
Published: October 2003

Abstract: The tandemly arranged genes psbT, psbN, and psbH code for proteins of photosystem II and are located in the large single copy region (LSC) of the chloroplast genome, downstream of psbB. So far, most of the studies dealing with this region have been interested in the organization and transcription of the psbB operon, while less is known about the transcription of psbN or the phylogenetic utility of this region. In the current study we discuss a sigma70‐type bacterial promoter motif upstream of psbN and present its consensus sequence for bryophytes. An analysis of the 3′ flanking inverted repeat sequences revealed a dyad symmetrical element, which is able to form a stable stem‐loop structure. This hairpin structure is characterised for land plants, with an emphasis on bryophytes. Furthermore, we observed an inversion of up to 9 bases in the loop region of the hairpin structure, which occasionally occurred in different unrelated bryophyte families, orders and classes. Small inversions are frequently obscured in the alignment since, during automatic alignment, many gap‐weighting schemes may not introduce gaps, nor does a manual insertion of gaps always seem needed at first glance. In subsequent phylogenetic analyses, minute inversion may overweight a particular mutation by interpreting the single inversion event as multiple apomorphic substitutions, which is particularly problematic since such inversion events are known to often be highly homoplastic. In the present study we use the psbT‐N spacer as an example to quantify the effect of such small inversions, contrasting the phylogenetic structure obtained with and without information from the hairpin loop. We show that obscured minute inversions can highly significantly reduce the robustness of the phylogenetic hypothesis inferred from the data set.
The Effect of Elevated UV Radiation on Fucus spp. (Fucales, Phaeophyta) Zygote and Embryo Development
Authors: Schoenwaelder M. E. A. , Wiencke C. , Clayton M. N. , Glombitza K. W.
Published: October 2003

Abstract: This study has shown that in Fucus serratus and Fucus distichus, young zygotes and embryos are highly susceptible to elevated levels of both UVA (UVAR) and UVB radiation (UVBR). Zygotes treated with UVAR are able to polarise and germinate, but are very slow to divide; if they do, they often have skewed division planes or deformed rhizoids. Those treated with UVAR and UVBR remain spherical, they do not polarise, germinate to form rhizoids or undergo cell division. We suggest that the UVR may be affecting the cytoskeleton. Conversely, zygotes and embryos of Fucus spiralis are able to withstand these same UVR levels and, at the light microscope level, appear to develop normally. When the brown algal phenolic compound phloroglucinol was placed in a filter covering the developing embryos, normal development was seen under all treatments. Phenolic compounds protect the developing fucoids from UVR. In comparison with the other two species, Fucus spiralis grows high up on the shore and is exposed for much longer periods of time and, presumably, to higher levels of natural UVR. The failure of the juvenile stages of F. serratus and F. distichus to withstand UVR stress may have implications for the continued survival of these species in the intertidal, and may prove detrimental to the population as a whole if UVR levels increase.
Seed Dispersal and Demography of Pioneer Trees: The Case of Hortia arborea
Authors: Melo F. P. L. , Tabarelli M.
Published: October 2003

Abstract: This study investigates the relationships among seed dispersal, patterns of seedling recruitment and the spatial distribution of a pioneer tree (Hortia arborea, Rutaceae) in the Brazilian Atlantic forest. The study was carried out at Dois Irmãos Reserve, a 387.4 ha reserve in northeastern Brazil. Fruit shadow concentrated beneath parental trees (74.6 % < 6 m distant) and fruit removal averaged 5.6 % (0 ‐ 25.5 %). Agoutis (Dasyprocta prymnolopha, Rodentia) ate fruits in the forest and in captivity and were the only vertebrates recorded feeding on Hortia fruits. Agoutis, however, destroyed 86.7 % of the seeds they ingested. In addition, only one seed from an expected number of 1980 germinated in a treefall gap after it passed through the digestive tract of agoutis. Both seed germination and seedling recruitment were restricted to gaps, and occurred among seeds manually released from the pulp or among those from fruits that naturally rotted in gaps. Moreover, exposed seedlings were taller than those covered by plants in a gap. H. arborea appears to self‐maintain populations in the same patches of forest, which are delimited by a pool of old and newly created gaps. More specifically, there is successful recruitment in patches occupied by parents, resulting in dense clumps of H. arborea.
The Molecular Regulation of Leaf Form
Authors: Fleming A. J.
Published: October 2003

Abstract: Recent research has provided significant advances in the identification of gene products which influence leaf form. In this review, a summary of this progress is made and an outline sketched of the future directions and challenges facing workers in this area. An overall view is taken in which the present characterisation of the molecular architects of leaf morphogenesis is envisaged to link up eventually with the final downstream elements of differential tissue growth which, integrated over developmental time, lead to the range of leaf forms observed in nature.
Reactive oxygen species and ethylene play a positive role in lateral root base nodulation of a semiaquatic legume
Authors: D'Haeze Wim , De Rycke Riet , Mathis René , Goormachtig Sofie , Pagnotta Sophie , Verplancke Christa , Capoen Ward , Holsters Marcelle
Published: October 2003

Lateral root base nodulation on the tropical, semiaquatic legume
Sesbania rostrata
results from two coordinated, Nod factor-dependent processes: formation of intercellular infection pockets and induction of cell division. Infection pocket formation is associated with cell death and production of hydrogen peroxide. Pharmacological experiments showed that ethylene and reactive oxygen species mediate Nod factor responses and are required for nodule initiation, whereby induction of division and infection could not be uncoupled. Application of purified Nod factors triggered cell division, and both Nod factors and ethylene induced cavities and cell death features in the root cortex. Thus, in
S. rostrata
, ethylene and reactive oxygen species act downstream from the Nod factors in pathways that lead to formation of infection pockets and initiation of nodule primordia.
Human cytomegalovirus UL83-coded pp65 virion protein inhibits antiviral gene expression in infected cells
Authors: Browne Edward P. , Shenk Thomas
Published: October 2003

The initial interaction of human cytomegalovirus with fibroblasts triggers, and then partially blocks, an innate immune response pathway that leads to the induction of IFN-responsive genes and proinflammatory chemokines. Infection of fibroblasts with human cytomegalovirus inhibited their ability to respond to exogenous IFN. Consistent with the observation that the block did not depend onde novoviral protein synthesis, ectopic expression of the viral UL83-coded pp65, an abundant virion protein, inhibited IFN signaling. Furthermore, DNA array analysis showed that infection with a pp65-deficient mutant virus caused a much stronger induction of many IFN-response and proinflammatory chemokine RNAs than infection with wild-type virus. The nuclear DNA-binding activities of transcription factors NF-κB and IRF1 were induced to a much greater extent after infection with the pp65-deficient mutant than with wild-type virus. IFN-stimulated gene factor 3 DNA-binding was modestly enhanced, whereas IRF3 activity was not affected by mutation of pp65. Together, these results imply that pp65, which is delivered to newly infected cells in the virion, antagonizes a pathway that affects NF-κB and IRF1 and prevents the accumulation of mRNAs encoded by numerous cellular antiviral genes.
Inorganic polyphosphate stimulates mammalian TOR, a kinase involved in the proliferation of mammary cancer cells
Authors: Wang Lihong , Fraley Cresson D. , Faridi Jesika , Kornberg Arthur , Roth Richard A.
Published: October 2003

Inorganic polyphosphate (poly P), chains of hundreds of phosphate residues linked by “high-energy” bonds as in ATP, has been conserved from prebiotic times in all cells. Poly P is essential for a wide variety of functions in bacteria, including virulence in pathogens. In this study, we observe the unique and many-fold stimulation by poly P
in vitro
of the protein kinase mTOR (mammalian target of rapamycin). To explore the role of poly P in mammalian cells, a yeast polyphosphatase, PPX1, was inserted into the chromosomes of MCF-7 mammary cancer cells. The transfected cells are markedly deficient in their response to mitogens, such as insulin and amino acids, as seen in their failure to activate mTOR to phosphorylate one of its substrates, PHAS-I (the initiation factor 4E-binding protein). In addition, the transfected cells are severely reduced in their growth in a serum-free medium. On the basis of these findings, we suggest that poly P (and/or PPX1) serves as a regulatory factor in the activation of mTOR in the proliferative signaling pathways of animal cells.