bluuebunny/crossref_metadata_2025_split huggingface dataset:
A symbiotic mutant of Sinorhizobium meliloti reveals a novel genetic pathway involving succinoglycan biosynthetic functions
Authors: Griffitts Joel S. , Long Sharon R. 
Published: February 2008

SummaryA large‐scale screen for symbiotic mutants was carried out using the model root nodulating bacterium Sinorhizobium meliloti. Several mutations in the previously uncharacterized gene msbA2 were isolated. msbA2 encodes a member of the ATP‐binding cassette exporter family. This protein family is known to export a wide variety of compounds from bacterial cells. S. meliloti MsbA2 is required for the invasion of nodule tissue, with msbA2 mutant cells stimulating nodule primordium morphogenesis, but failing to invade plant tissue beyond the epidermal cell layer. msbA2 mutants do not exhibit any of the free‐living traits often found to correlate with symbiotic defects, suggesting that MsbA2 may take part in a specifically symbiotic function. In strains that overproduce the symbiotic signalling polysaccharide succinoglycan, loss of MsbA2 function is extremely deleterious. This synthetic lethal phenotype can be suppressed by disrupting the succinoglycan biosynthetic genes exoY or exoA. It can also be suppressed by disrupting putative glycosyltransferase‐encoding genes found upstream of msbA2. Finally, the symbiotic phenotype of a msbA2 null mutant is suppressed by secondary mutations in these upstream transferase genes, indicating that the msbA2 mutant phenotype may be caused by an inhibitory accumulation of a novel polysaccharide that is synthesized from succinoglycan precursors.
Failure of ES‐62 to inhibit T‐helper type 1 responses to other filarial nematode antigens
Authors: AL‐RIYAMI L. , EGAN C. A. , BRADLEY J. E. , LUSTIGMAN S. , HARNETT W. 
Published: February 2008

SUMMARY ES‐62 is a secreted protein of filarial nematodes that possesses multiple immunomodulatory activities. A full characterization of these activities awaits elucidation but to date it has been shown that ES‐62 can inhibit pro‐inflammatory/Th1 immune responses and in some studies, it has been found to actively support Th2 development. As an active filarial nematode infection is associated with a Th2‐like immunological phenotype, this study investigated whether ES‐62 was likely to be responsible for, or at least contribute to, this phenotype. Specifically, we determined ES‐62's effect on the immune response to two other filarial nematode antigens, chosen for their ability to promote Th1 responses. The two antigens were recombinant Onchocerca volvulus‐Fatty acid And Retinol‐binding‐1 (rOv‐FAR‐1) and recombinant Onchocerca volvulus‐Activation associated Secreted Protein‐1 (Ov‐ASP‐1). Overall the results show that in spite of its previously characterized immunomodulatory properties, ES‐62 was unable to modulate/reverse the Th1 immune responses induced by the two Onchocerca antigens. Therefore, in this study no support is provided for the idea that ES‐62 might be a major player in facilitating the overall immunological phenotype in filariasis and reasons for this somewhat surprising outcome are discussed.
Heterosis in the freezing tolerance, and sugar and flavonoid contents of crosses between Arabidopsis thaliana accessions of widely varying freezing tolerance
Authors: KORN MARINA , PETEREK SILKE , MOCK HANS‐PETER , HEYER ARND G. , HINCHA DIRK K. 
Published: February 2008

ABSTRACTHeterosis is defined as the increased vigour of hybrids in comparison to their parents. We investigated 24 F1 hybrid lines of Arabidopsis thaliana generated by reciprocally crossing either C24 or Col with six other parental accessions (Can, Co, Cvi, Ler, Rsch, Te) that differ widely in their freezing tolerance. The crosses differed in the degree of heterosis for freezing tolerance, both in the non‐acclimated state and after a 14 d cold acclimation period. Crosses with C24 showed more heterosis than crosses with Col, and heterosis was stronger in acclimated than in non‐acclimated plants. Leaf content of soluble sugars and proline showed more deviation from mid‐parent values in crosses involving C24 than in those involving Col, and deviations were larger in acclimated than in non‐acclimated plants. There were significant correlations between the content of different sugars and leaf freezing tolerance, as well as between heterosis effects in freezing tolerance and sugar content. Flavonoid content and composition varied between accessions, and between non‐acclimated and acclimated plants. In the crosses, large deviations from the mid‐parent values in the contents of different flavonols occurred, and there were strikingly strong correlations between both flavonol content and freezing tolerance, and between heterosis effects in freezing tolerance and flavonol content.
Population structure and mating system of Ascochyta rabiei in Tunisia: evidence for the recent introduction of mating type 2
Authors: Rhaiem A. , Chérif M. , Peever T. L. , Dyer P. S. 
Published: February 2008

The population structure of Ascochyta rabiei (teleomorph: Didymella rabiei) in Tunisia was estimated among five populations sampled from the main chickpea growing regions using simple sequence repeat markers (SSR) and a mating type (MAT) marker. Mating type 2 isolates (MAT1‐2) had reduced genetic and genotypic diversity relative to mating type 1 isolates (MAT1‐1). This result, coupled with previous observations of lower overall frequency and restricted geographical distribution of MAT1‐2 in Tunisia, and recent (2001) observation of the sexual stage, support the hypothesis of a recent introduction of MAT1‐2. Despite the presence of both mating types in Nabeul, Kef and Jendouba, the hypothesis of random mating was rejected in these locations with multilocus gametic disequilibrium tests. Highly significant genetic differentiation (θ = 0·32, GST = 0·28, P < 0·001) was detected among populations and genetic distance and cluster analyses based on pooled allele frequencies revealed that populations from Nabeul and Kef were distinct from those in Beja, Bizerte and Jendouba. More than 70% of total gene diversity (HT = 0·55) detected was attributable to variation within populations compared to 28% among populations. This result, coupled with the occurrence of private alleles in each population, suggests that gene flow is currently limited among populations, even those separated by short geographic distances. The presence of two main genetic clusters was confirmed using Bayesian model‐based population structure analyses of multilocus genotypes (MLGs) without regard to geographic origin of samples. The presence of MAT1‐2 isolates in both clusters suggests at least two independent introductions of MAT1‐2 into Tunisia that are likely to be the result of importation and planting of infected chickpea seeds.
Functional divergence of the duplicated AtKIN14a and AtKIN14b genes: critical roles in Arabidopsis meiosis and gametophyte development
Authors: Quan Li , Xiao Rong , Li Wuxing , Oh Sung‐Aeong , Kong Hongzhi , Ambrose J. Christian , Malcos Jennelle L. , Cyr Richard , Twell David , Ma Hong 
Published: February 2008

SummaryGene duplication is important for gene family evolution, allowing for functional divergence and innovation. In flowering plants, duplicated genes are widely observed, and functional redundancy of closely related duplicates has been reported, but few cases of functional divergence of close duplicates have been described. Here, we show that the Arabidopsis AtKIN14a and AtKIN14b genes encoding highly similar kinesins are two of the most closely related Arabidopsis paralogs, which were formed by a duplication event that occurred after the split of Arabidopsis and poplar. In addition, AtKIN14a and AtKIN14b exhibit varying degrees of coding sequence divergence. Further genetic studies of plants carrying atkin14a and/or atkin14b mutations indicate that, although these two genes have similar functions, there is clear evidence for functional divergence. Although both genes are important for male and female meiosis, AtKIN14a plays a more critical role in male meiosis than AtKIN14b. Moreover, either one of these two genes is necessary and sufficient for gametophyte development, indicating that they are redundant for this function. Therefore, AtKIN14a and AtKIN14b together play important roles in controlling plant reproductive development. Our results suggest that the AtKIN14a and AtKIN14b genes have retained similar functions in gametophyte development and female meiosis, but have evolved partially distinct functions in male meiosis, with AtKIN14a playing a more substantive role.
Characterization of oral lactobacilli as potential probiotics for oral health
Authors: Kõll P. , Mändar R. , Marcotte H. , Leibur E. , Mikelsaar M. , Hammarström L. 
Published: February 2008

Introduction:  Intestinal lactobacilli have been successfully used as probiotics to treat gastrointestinal disorders, but only limited data are available for the probiotic properties of oral lactobacilli to combat oral diseases. We aimed to characterize oral lactobacilli for their potential probiotic properties according to the international guidelines for the evaluation of probiotics, and to select potential probiotic strains for oral health.Methods:  The study included 67 salivary and subgingival lactobacilli of 10 species, isolated from healthy humans. All strains were identified using amplified ribosomal DNA restriction analysis, tested for antimicrobial activity against oral pathogens, tolerance of low pH and bile content. Thereafter, the lysozyme tolerance and antibiotic susceptibility of 22 potential probiotic strains were assessed.Results:  The majority of strains suppressed the growth of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Streptococcus mutans, but none inhibited Candida albicans. The lowest pH tolerated by lactobacilli following 4 h of incubation was pH 2.5, but none of the strains grew at this pH. All strains tolerated a high concentration of lysozyme (10 mg/ml) and half of the strains tolerated a high concentration of human bile [5% volume/volume (V/V)]. Four Lactobacillus plantarum and two Lactobacillus oris strains expressed resistance to tetracycline and/or doxycycline.Conclusions:  Strains of L. plantarum, Lactobacillus paracasei, Lactobacillus salivarius, and Lactobacillus rhamnosus expressed both high antimicrobial activity and high tolerance of environmental stress. The absence of transferable antibiotic‐resistance genes in L. plantarum strains remains to be confirmed. These results suggest a potential for oral lactobacilli to be used as probiotics for oral health.
Variation of anti‐Fas antibodies in different lots of intravenous immunoglobulin
Authors: Reipert B. M. , Stellamor M. T. , Poell M. , Ilas J. , Sasgary M. , Reipert S. , Zimmermann K. , Ehrlich H. , Schwarz H. P. 
Published: February 2008

Background and Objectives  Previous studies have presented evidence that human immunoglobulin G preparations for intravenous use contain antibodies directed against the death receptor Fas (CD95). The function of these antibodies was described as either antagonistic or agonistic; therefore, inhibiting or stimulating Fas‐dependent apoptosis. Based on these reports, we asked whether the proportion of antagonistic and agonistic anti‐Fas activities differs between different lots of intravenous immunoglobulin (IVIG). Variations between lots would open the possibility to preselect suitable lots of IVIG for different therapeutic purposes.Materials and Methods  Eleven lots of IVIG were tested for their ability to induce or inhibit Fas‐dependent apoptosis. The biological significance of anti‐Fas antibodies was confirmed by including anti‐Fas antibodies purified from IVIG and IVIG depleted of anti‐Fas antibodies in the study.Results  All 11 lots inhibited FasL‐induced apoptosis. In addition, five lots stimulated apoptosis in the absence of FasL. Depletion of anti‐Fas antibodies from IVIG abolished the capacity of IVIG to inhibit FasL‐induced apoptosis, but reduced the ability to induce apoptosis only slightly.Conclusion  The inhibition of FasL‐induced apoptosis by IVIG is because of the presence of antagonistic anti‐Fas antibodies. The activity of these antibodies differs considerably between different lots. On the other hand, the induction of apoptosis by IVIG is probably because of the concerted action of a range of different antibodies. The variation in the proportion of stimulating and inhibiting anti‐Fas activities between different lots of IVIG opens the possibility to preselect suitable lots for different therapeutic purposes.
Dose‐Dependent Immunohistochemical and Ultrastructural Changes After Oral Methylphenidate Administration in Rat Heart Tissue
Authors: Take G. , Bahcelioglu M. , Oktem H. , Tunc E. , Gözil R. , Erdogan D. , Calguner E. , Helvacıoglu F. , Giray S. G. , Elmas C. 
Published: February 2008

SummaryMethylphenidate, more commonly known as Ritalin, is a piperidine derivative and is the drug most often used to treat attention deficit/hyperactivity disorder, one of the most common behavioural disorders of children and young adults. Our aims were to investigate dose‐dependent immunohistochemical D2 expression and ultrastructural changes of the rat heart tissue, and to demonstrate possible toxicity of the long‐term and high dose use of the methylphenidate. In this study, 27 female pre‐pubertal Wistar albino rats, divided into three different dose groups (5, 10 and 20 mg/kg) and their control groups, were used. They were treated orally with methylphenidate dissolved in saline solution for 5 days/week during 3 months. At the end of the third month, after perfusion fixation, left ventricle of cardiac tissue was removed. Paraffin, semi‐thin and thin sections were collected and immunohistochemical, terminal deoxynucleotidyl transferase‐mediated Dig‐dUTP nick end labelling assay and ultrastructural studies were performed. In conclusion, we believe that Ritalin is dose‐related affecting dopaminergic system to increase heart rhythm and contraction. Thus, this drug may cause degenerative ultrastructural changes in mitochondrial path.
Spectral Overlap in Songs and Temporal Avoidance in a Peruvian Bird Assemblage
Authors: Planqué Robert , Slabbekoorn Hans 
Published: February 2008

AbstractAcoustic signals are very important in communication among conspecifics for many animals, especially in relatively dark, densely foliated habitat such as tropical rainforest. However, as many species all have to use the same acoustic space, this may lead to interference and masking. Songs will function efficiently in attracting mates or defending territories depending on the level of spectral and temporal overlap with songs of other species in the local community. As signal efficiency has direct fitness consequences, organisms may have evolved a strategy to avoid competition for acoustic space. We hypothesize that, as a consequence, species in a complex rainforest community may show spectral segregation or temporal avoidance: singing at a different frequency or at a different time. As doing both is superfluous and acoustic space is limited, we expect a negative correlation between spectral and temporal overlap. We tested this hypothesis in recordings of 20 vocally dominant bird species from 14 families in a Peruvian rainforest. Using pair‐wise comparisons between bird species, we found one significant correlation between spectral overlap and temporal overlap. All others were non‐significant. However, we did find that, at frequencies more often used by multiple bird species, there was significantly less overlap than expected if all species were just singing randomly ignorant of each other’s songs. Our analyses indicate that short‐term auditory feedback mechanisms may also operate in the biodiverse environments of the tropics and may explain part of the community dynamics of acoustic signalling in the rainforest.
Early Developmental Conditions and Male Attractiveness in Zebra Finches
Authors: Naguib Marc , Heim Claudia , Gil Diego 
Published: February 2008

AbstractTraits used in mate choice are often costly to produce or maintain, and thus can reflect an individual’s current condition. Mate choice, however, might not only be influenced by the current condition of a potential partner, but also by the condition it had experienced during its early development which can have strong and long‐lasting effects on various traits. Here we studied the effects of different early developmental conditions, imposed by brood size manipulations (small, medium and large broods), on male attractiveness as measured by female choice experiments in zebra finches (Taeniopygia guttata). In three different experiments, we allowed females to choose between males that had been raised in different experimental brood sizes. In none of the experiments, females showed a significant preference for males which had experienced better developmental conditions, i.e. were raised in the relatively smaller experimental broods. Song rate was higher in males coming from small than large broods, but females did not prefer males that sang more. These results suggest that sexual attractiveness either was not affected by our experimental treatment or that males subsequently had compensated in their overall attractiveness for negative effects of early developmental conditions.
The Meaning of Jolts by Fish Clients of Cleaning Gobies
Authors: Soares Marta C. , Bshary Redouan , Cardoso Sónia C. , Côté Isabelle M. 
Published: February 2008

AbstractCooperative interactions offer the inherent possibility of cheating by each of the interacting partners. A key challenge to behavioural observers is to recognize these conflicts, and find means to measure reliably cheating in natural interactions. CleanerfishLabroides dimidiatuscheat by taking scales and mucus from their fish clients and such dishonest cleaning has been previously recognized in the form of whole‐body jolts by clients in response to cleaner mouth contact. In this study, we test whether jolts may be a general client response to cheating by cleaners. We experimentally varied the ectoparasite loads of yellowtail damselfish (Microspathodon chrysurus), a common client of the cleaning gobyElacantinus evelynae, and compared the rates of jolts on parasitized and deparasitized clients. As predicted if jolts represent cleaner cheating, deparasitized clients jolted more often than parasitized clients, and overall jolt rates increased over time as client parasite load was presumably reduced by cleaning activity. Yellowtail damselfish in the wild jolted significantly less frequently than those in captivity, which is consistent with a loss of ectoparasites during capture. Our results suggest that jolts by clients of cleaning gobies are not related to the removal of ectoparasites. Client jolts may therefore be a generally accurate measure of cheating by cleanerfish.
The Effect of Within‐Flock Spatial Position on the Use of Social Foraging Tactics in Free‐Living Tree Sparrows
Authors: Mónus Ferenc , Barta Zoltán 
Published: February 2008

AbstractThe benefit of producer (searches for own food) or scrounger (exploits the others’ food discoveries) foraging tactic in a group of socially feeding animals may depend on where the individual searches for food within the group. Scrounging may be more advantageous in the centre of the group, having more individuals around to join, while producing may be more beneficial at the edges, where more unexplored food patches may be found. This study shows within‐flock position correlates with foraging tactic use of feeding birds in socially foraging tree sparrows, Passer montanus. Sparrows staying closer to the centre of the flock found their food patches more frequently by joining (i.e. use more frequently the scrounging tactic) than those staying toward the edges. To our knowledge this is the first field study demonstrating the relationship between spatial position and foraging tactic use. We investigated this relationship under different perceived predation hazard, and found that under elevated risk of predation, central individuals may increase their use of joining more than individuals on the periphery of the flock. Moreover, we show that extremely specialized use of searching tactics may be very infrequent in tree sparrows. As both within‐flock position and search tactic use can be altered very quickly and without leaving the flock, individuals may easily alter them in order to adjust their behaviour.
Expression of COX‐1, COX‐2, and PPAR‐γ in the gastric mucosa of children with Helicobacter pylori infection
Authors: Haruna Hidenori , Shimizu Toshiaki , Ohtsuka Yoshikazu , Yarita Yukiko , Fujii Tohru , Kudo Takahiro , Yamashiro Yuichiro 
Published: February 2008

AbstractBackground: Gastric inflammation in patients with Helicobacter pylori infection is considered to be regulated by many kinds of inflammatory and cytoprotective factors. The present study examined the effects of cyclo‐oxygenase (COX)‐1, ‐2, and peroxisome proliferator‐activated receptor‐γ (PPAR‐γ) on gastric mucosal injury in children with H. pylori infection.Methods: The subjects were 24 children who underwent endoscopy for the evaluation of anemia or gastrointestinal symptoms, and they were divided into two groups: a H. pylori‐positive group and ‐negative group. The numbers of neutrophils in the gastric mucosa of children with and without H. pylori infection and expression of COX‐1, ‐2, and PPAR‐γ were examined, using reverse transcription–polymerase chain reaction.Results: The numbers of neutrophils were significantly higher in the H. pylori‐positive group than in the H. pylori‐negative group. The ratio of COX‐1 mRNA to COX‐2 mRNA in the H. pylori‐positive group was significantly lower than that in the H. pylori‐negative group. The ratio of PPAR‐γ m‐RNA to β‐actin mRNA was significantly higher in the H. pylori‐positive group than the H. pylori‐negative group.Conclusions: Enhanced production of COX‐2 and PPAR‐γ in the gastric mucosa has cytoprotective and anti‐inflammatory effects, although the relationship to the carcinogenic activity of COX‐2 and PPAR‐γ should be clarified.
Assessment of myocardial involvement using cardiac troponin‐I and echocardiography in rheumatic carditis in İzmir, Turkey
Authors: Tavli Vedide , Canbal Abdullah , Şaylan Berna , Saritaş Türkay , Meşe Timur , Atlihan Füsun 
Published: February 2008

AbstractBackground: Acute rheumatic carditis is still a major problem in developing countries. Cardiac troponin‐I (cTnI) has been identified as a sensitive and specific marker in the diagnosis of myocarditis in children and adults.Methods: A prospective study was performed using Doppler echocardiography and cTnI in order to detect myocardial involvement in 26 consecutive patients with acute rheumatic valvular disease. Patients were divided into two groups: group 1, rheumatic fever with carditis (n > 16); group 2, rheumatic fever without carditis (n > 10).Results: Clinically age, gender, body temperature, heart rate and white blood count did not differ significantly between the groups and the age‐matched control group. C‐reactive protein, erythrocyte sedimentation rate, anti‐streptolysin‐O were significantly different. Left ventricular fractional shortening was normal in all patients (group 1, 37 ± 10%; group 2, 34 ± 5%; NS). Left ventricular dimensions were larger in group 1, in which all patients except two had moderate to severe mitral and/or aortic valvular regurgitation (5.05 ± 0.75 cm/m2) compared to group 2, in which none had valvular regurgitation (3.27 ± 0.26 cm/m2, P < 0.05). None of the patients in either group presented with or developed pericarditis. Mean cTnI was 0.12 ± 0.034 ng/mL in group 2 and 0.077 ± 0.02 in group 1, the difference of which was not statistically significant. Neither significant cTnI elevations nor echocardiographic systolic function abnormalities were found in the present patients with rheumatic carditis.Conclusions: The present results indicate the absence of myocardial involvement in acute rheumatic carditis without congestive heart failure.