Evolutionary and epidemiological insights from historical and modern genomes of Xanthomonas oryzae pv. oryzicola, the causal agent of bacterial leaf streak of rice.

Xanthomonas oryzae pv. oryzicola (Xoc) causes bacterial leaf streak (BLS) of rice. This disease represents a major constraint for rice production, a crop feeding more than half of the world's population. Xoc was first described in 1918 in the Philippines and is prevalent in Southeast Asia. Today, BLS is also omnipresent in both East and West Africa where the disease was first reported in the early 1980s. The appearance of Xoc in Africa decades after its first report in Asia suggests that the disease could have been introduced from Asia to Africa. Strict conservation of five Transcription Activator Like (TAL) effectors in whole-genome sequences of 10 strains of Xoc including 3 from West-Africa and 7 from Asia also support this hypothesis. East Africa, and especially Madagascar, where the disease was first described in 1985 is located at the interface between Asia and Africa, hence representing an interesting region to explore the link between strains from Asia and West-Africa. In this study, we i) reconstructed the genome of an historical Xoc strain from herbarium specimen of rice showing symptoms of BLS, sampled in Madagascar in 1931, 50 years before the first description of the disease, and ii) sequenced 9 new modern strains including 5 from Madagascar and East-Africa. The analysis of those new genomes along with previously published ones shed light within the evolutionary and epidemiological history of Xoc.

Adaptation of genetically monomorphic bacteria: evolution of copper resistance through multiple horizontal gene transfers of complex and versatile mobile genetic elements.

Copper-based antimicrobial compounds are widely used to control plant bacterial pathogens. Pathogens have adapted in response to this selective pressure. Xanthomonas citri pv. citri, a major citrus pathogen causing Asiatic citrus canker, was first reported to carry plasmid-encoded copper resistance in Argentina. This phenotype was conferred by the copLAB gene system. The emergence of resistant strains has since been reported in Réunion and Martinique. Using microsatellite-based genotyping and copLAB PCR, we demonstrated that the genetic structure of the copper-resistant strains from these three regions was made up of two distant clusters and varied for the detection of copLAB amplicons. In order to investigate this pattern more closely, we sequenced six copper-resistant X. citri pv. citri strains from Argentina, Martinique and Réunion, together with reference copper-resistant Xanthomonas and Stenotrophomonas strains using long-read sequencing technology. Genes involved in copper resistance were found to be strain dependent with the novel identification in X. citri pv. citri of copABCD and a cus heavy metal efflux resistance-nodulation-division system. The genes providing the adaptive trait were part of a mobile genetic element similar to Tn3-like transposons and included in a conjugative plasmid. This indicates the system's great versatility. The mining of all available bacterial genomes suggested that, within the bacterial community, the spread of copper resistance associated with mobile elements and their plasmid environments was primarily restricted to the Xanthomonadaceae family.

Natural Infection of Cashew (Anacardium occidentale) by Xanthomonas citri pv. mangiferaeindicae in Burkina Faso.

Xanthomonas citri pv. mangiferaeindicae is the causal agent of bacterial canker of mango (Mangifera indica, Anacardiaceae), a disease of international importance. Since the original description of the bacterium in the 1940s, the status of cashew (Anacardium occidentale, Anacardiaceae) as a host species has been unclear. Here, we report the first outbreak of a cashew bacterial disease in Burkina Faso (Western Africa) where X. citri pv. mangiferaeindicae recently emerged on mango. A comprehensive molecular characterization, based on multilocus sequence analysis, supplemented with pathogenicity assays of isolates obtained during the outbreak, indicated that the causal agent on cashew in Burkina Faso is X. citri pv. mangiferaeindicae and not X. citri pv. anacardii, which was previously reported as the causal agent of a cashew bacterial leaf spot in Brazil. Pathogenicity data supported by population biology in Burkina Faso suggest a lack of host specialization. Therefore, the inoculum from each crop is potentially harmful to both host species. Symptoms induced on cashew leaves and fruit by X. citri pv. mangiferaeindicae and nonpigmented strains of X. citri pv. anacardii are similar, although the causative bacteria are genetically different. Thus, xanthomonads pathogenic on cashew may represent a new example of pathological convergence in this bacterial genus.

Bridgehead invasion of a monomorphic plant pathogenic bacterium: Xanthomonas citri pv. citri, an emerging citrus pathogen in Mali and Burkina Faso.

Molecular epidemiology studies further our understanding of migrations of phytopathogenic bacteria, the major determining factor in their emergence. Asiatic citrus canker, caused by Xanthomonas citri pv. citri, was recently reported in Mali and Burkina Faso, a region remote from other contaminated areas. To identify the origin and pathways of these emergences, we used two sets of markers, minisatellites and microsatellites, for investigating different evolutionary scales. Minisatellite typing suggested the introduction of two groups of strains in Mali (DAPC 1 and DAPC 2), consistent with microsatellite typing. DAPC 2 was restricted to Bamako district, whereas DAPC 1 strains were found much more invasive. The latter strains formed a major clonal complex based on microsatellite data with the primary and secondary founders detected in commercial citrus nurseries and orchards. This suggests that human activities played a major role in the spread of DAPC 1 strains via the movement of contaminated propagative material, further supported by the frequent lack of differentiation between populations from geographically distant nurseries and orchards. Approximate Bayesian Computation analyses supported the hypothesis that strains from Burkina Faso resulted from a bridgehead invasion from Mali. Multi-locus variable number of tandem repeat analysis and Approximate Bayesian Computation are useful for understanding invasion routes and pathways of monomorphic bacterial pathogens.

The regional sensitivity of chondrocyte gene expression to coactive mechanical load and exogenous TNF-α stimuli.

Both mechanical load and elevated levels of proinflammatory cytokines have been associated with the risk for developing osteoarthritis (OA), yet the potential interaction of these mechanical and biological factors is not well understood. The purpose of this study was to evaluate the response of chondrocytes to the effects of dynamic unconfined compression, TNF-α, and the simultaneous effects of dynamic unconfined compression and TNF-α. The response to these three treatments was markedly different and, taken together, the response in the gene expression of chondrocytes to the different treatment conditions suggest a complex interaction between structure, biology, and mechanical loading.

First Report of Xanthomonas citri pv. mangiferaeindicae Causing Mango Bacterial Canker on Mangifera indica in Ivory Coast.

Xanthomonas citri pv. mangiferaeindicae causing bacterial canker (or black spot) is a major mango (Mangifera indica L.) pathogen in tropical and subtropical areas (3). The bacterium infects a wide range of mango cultivars, and induces raised, angular, black leaf lesions, sometimes with a yellow chlorotic halo. Fruit symptoms first appear as small water-soaked spots on the lenticels turning into star-shaped, erumpent lesions, which exude an infectious gum, yielding tear-stain patterns. Severe infections cause severe defoliation and/or premature fruit drop. Twig cankers are potential sources of inoculum and weaken branch resistance to winds. Drastic yield losses have been reported at grove scale for susceptible cultivars (3). Mango leaves showing typical angular, black, raised leaf lesions were first observed and collected in April 2014 from trees cv. Kent in five localities of the Korhogo province of Ivory Coast (i.e., the major commercial mango-growing area in this country). Non-pigmented Xanthomonas-like colonies were isolated on KC semi-selective medium (4). Five strains (LL60-1, LL61-1, LL62-1, LL63-1, and LL64-1), one from each locality, were compared by multilocus sequence analysis (MLSA) to the type strain of X. citri and the pathotype strain of several X. citri pathovars, including pvs. anacardii and mangiferaeindicae. This assay targeted the atpD, dnaK, efp, and gyrB genes, as described previously (2). Nucleotide sequences were 100% identical to those of the pathotype strain of X. citri pv. mangiferaeindicae whatever the gene assayed, but differed from any other assayed X. citri pathovar. Leaves of mango cv. Maison Rouge from the youngest vegetative flush were infiltrated (10 inoculation sites/leaf for three replicate leaves on different plants/bacterial strain) as detailed previously (1) with the same five strains. Bacterial suspensions (~1 × 105 cfu/ml) were prepared in 10 mM Tris buffer (pH 7.2) from 16-h-old cultures on YPGA (7 g yeast, 7 g peptone, 7 g glucose, and 18 g agar/liter, pH 7.2). The negative control treatment consisted of three leaves infiltrated with sterile Tris buffer (10 sites/leaf). Plants were incubated in a growth chamber at 30 ± 1°C by day and 26 ± 1°C by night (12-h day/night cycle) at 80 ± 5% RH. All leaves inoculated with the strains from Ivory Coast showed typical symptoms of bacterial canker a week after inoculation. No lesions were recorded from the negative controls. The pathogen was recovered at high population densities (>1 × 106 cfu/lesion) from leaf lesions, typical of a compatible interaction (1) and isolated colonies were identified as the target by atpD sequencing (2). Koch's postulates have therefore been fully verified. This is the first report of the disease in Ivory Coast, a country which has been an internationally significant mango exporter (up to 15,000 tons per year) over the last two decades. A high disease incidence and severity were observed, outlining the need for implementing integrated pest management in mango groves and the production of disease-free nursery stock. This report further expands the distribution of the pathogen in West Africa after its first description from Ghana in 2011 (5) and subsequently in other neighboring countries. References: (1) N. Ah-You et al. Phytopathology 97:1568, 2007. (2) L. Bui Thi Ngoc et al. Int. J. Syst. Evol. Microbiol. 60:515, 2010. (3) L. Gagnevin and O. Pruvost. Plant Dis. 85:928, 2001. (4) O. Pruvost et al. J. Appl. Microbiol. 99:803, 2005. (5) O. Pruvost et al. Plant Dis. 95:774, 2011.

First Report of Xanthomonas citri pv. citri Pathotype A Causing Asiatic Citrus Canker in Grande Comore and Anjouan.

The causal agent of Asiatic citrus canker, Xanthomonas citri pv. citri, is a bacterium of major economic importance in tropical and subtropical citrus-producing areas. X. citri pv. citri pathotype A can cause severe infection in a wide range of citrus species and induces erumpent, callus-like lesions with water-soaked margins evolving to corky cankers and leading to premature fruit, leaf drop, and twig dieback on susceptible cultivars. This quarantine organism can strongly impact citrus markets so it has consequently been subjected to eradication efforts and international quarantine regulations. Asiatic citrus canker occurs on most islands in the Southwest Indian Ocean region including the Mascarene and Seychelles archipelagos. In the Comoros archipelago, the disease was observed for the first time in Mohéli island in 1966 (2), but had not yet been reported in neighboring islands, Grande Comore and Anjouan. In September 2013, leaves of key lime (Citrus aurantifolia) and sweet orange (C. sinensis) showing symptoms of citrus canker were collected from Anjouan, Grande Comore, and Mohéli. Nine Xanthomonas-like strains (three from each of the three islands) were isolated using KC semi-selective medium (5) from diseased samples (LK126-3, LK127-7, LK128-2, LK131-10, LK137-1, LK141-3, LK144-5, LK145-5, LK146-2). Based on a specific PCR assay with 4/7 primers (4), all Xanthomonas-like strains were tentatively identified as X. citri pv. citri. All strains produced a 468-bp amplicon similar to X. citri pv. citri strain IAPAR 306 used as a positive control. Negative control reactions with sterile tris buffer did not produce amplicons. Multilocus sequence analysis (MLSA) targeting six housekeeping genes (atpD, dnaK, efp, gltA, gyrB, and lepA) (1,3) fully identified all strains from the Comoros as X. citri pv. citri. More specifically, eight strains were identified as sequence type ST2 composed of pathotype A strains of X. citri pv. citri (3) (including all strains from the Southwest Indian Ocean region) while one of them (LK141-3 from Mohéli) was identified as a new sequence type based on a non-synonymous single nucleotide polymorphism in gyrB (accession KJ941208). All strains were inoculated by a detached leaf assay (3) onto Mexican lime SRA 140 (C. aurantifolia), Tahiti lime SRA 58 (C. latifolia), sweet orange New Hall Navel SRA 343 (C. sinensis), grapefruit Henderson SRA 336 (C. paradisi), and Ortanique tangor SRA 110 (C. reticulata × C. sinensis). All citrus species inoculated produced typical erumpent, callus-like tissue at wound sites. Xanthomonas-like yellow colonies were re-isolated from lesions produced on Mexican lime. Boiled bacterial suspensions were assayed by PCR with 4/7 primers (4) and produced the expected amplicon, fulfilling Koch's postulates. No lesions developed on the negative control consisting of inoculations with sterile tris buffer. This is the first report of X. citri pv. citri-A causing Asiatic citrus canker in Grande Comore and Anjouan islands confirming the wide distribution of the pathogen in Southwest Indian Ocean islands. Canker-free nurseries and grove sanitation should be implemented to decrease the prevalence of Asiatic canker in the Comoros. References: (1) N. F. Almeida et al. Phytopathology 100:208, 2010. (2) J. Brun. Fruits 26:533, 1971. (3) L. Bui Thi Ngoc et al. Int. J. Syst. Evol. Microbiol. 60:515, 2010. (4) J. S. Hartung et al. Phytopathology 86:95, 1996. (5) O. Pruvost et al. J. Appl. Microbiol. 99:803, 2005.

Novel paradigm enables accurate monthly gestational screening to prevent congenital toxoplasmosis and more.

Background: Congenital toxoplasmosis is a treatable, preventable disease, but untreated causes death, prematurity, loss of sight, cognition and motor function, and substantial costs worldwide. Methods/Findings: In our ongoing USA feasibility/efficacy clinical trial, data collated with other ongoing and earlier published results proved high performance of an Immunochromatographic-test(ICT) that enables accurate, rapid diagnosis/treatment, establishing new paradigms for care. Overall results from patient blood and/or serum samples tested with ICT compared with gold-standard-predicate-test results found ICT performance for 4606 sera/1876 blood, 99.3%/97.5% sensitive and 98.9%/99.7% specific. However, in the clinical trial the FDA-cleared-predicate test initially caused practical, costly problems due to false-positive-IgM results. For 58 persons, 3/43 seronegative and 2/15 chronically infected persons had false positive IgM predicate tests. This caused substantial anxiety, concerns, and required costly, delayed confirmation in reference centers. Absence of false positive ICT results contributes to solutions: Lyon and Paris France and USA Reference laboratories frequently receive sera with erroneously positive local laboratory IgM results impeding patient care. Therefore, thirty-two such sera referred to Lyon's Reference laboratory were ICT-tested. We collated these with other earlier/ongoing results: 132 of 137 USA or French persons had false positive local laboratory IgM results identified correctly as negative by ICT. Five false positive ICT results in Tunisia and Marseille, France, emphasize need to confirm positive ICT results with Sabin-Feldman-Dye-test or western blot. Separate studies demonstrated high performance in detecting acute infections, meeting FDA, CLIA, WHO ASSURED, CEMark criteria and patient and physician satisfaction with monthly-gestational-ICT-screening. Conclusions/Significance: This novel paradigm using ICT identifies likely false positives or raises suspicion that a result is truly positive, rapidly needing prompt follow up and treatment. Thus, ICT enables well-accepted gestational screening programs that facilitate rapid treatment saving lives, sight, cognition and motor function. This reduces anxiety, delays, work, and cost at point-of-care and clinical laboratories. Author's Summary: Toxoplasmosis is a major health burden for developed and developing countries, causing damage to eyes and brain, loss of life and substantial societal costs. Prompt diagnosis in gestational screening programs enables treatment, thereby relieving suffering, and leading to > 14-fold cost savings for care. Herein, we demonstrate that using an ICT that meets WHO ASSURED-criteria identifying persons with/without antibody to Toxoplasma gondii in sera and whole blood with high sensitivity and specificity, is feasible to use in USA clinical practice. We find this new approach can help to obviate the problem of detection of false positive anti- T.gondii IgM results for those without IgG antibodies to T.gondii when this occurs in present, standard of care, predicate USA FDA cleared available assays. Thus, this accurate test facilitates gestational screening programs and a global initiative to diagnose and thereby prevent and treat T.gondii infection. This minimizes likelihood of false positives (IgG and/or IgM) while maintaining maximum sensitivity. When isolated IgM antibodies are detected, it is necessary to confirm and when indicated continue follow up testing in ∼2 weeks to establish seroconversion. Presence of a positive ICT makes it likely that IgM is truly positive and a negative ICT makes it likely that IgM will be a false positive without infection. These results create a new, enthusiastically-accepted, precise paradigm for rapid diagnosis and validation of results with a second-line test. This helps eliminate alarm and anxiety about false-positive results, while expediting needed treatment for true positive results and providing back up distinguishing false positive tests.

Predictive-focus illumination for reducing photodamage in live-cell microscopy.

Due to photobleaching and phototoxicity induced by high-intensity excitation light, the number of fluorescence images that can be obtained in live cells is always limited. This limitation becomes particularly prominent in multidimensional recordings when multiple Z-planes are captured at every time point. Here we present a simple technique, termed predictive-focus illumination (PFI), which helps to minimize cells' exposure to light by decreasing the number of Z-planes that need to be captured in live-cell 3D time-lapse recordings. PFI utilizes computer tracking to predict positions of objects of interest (OOIs) and restricts image acquisition to small dynamic Z-regions centred on each OOI. Importantly, PFI does not require hardware modifications and it can be easily implemented on standard wide-field and spinning-disc confocal microscopes.

Biomedical three-dimensional holographic microimaging at visible, ultraviolet and X-ray wavelengths.

A new imaging technology is under advanced development that has several key advantages over conventional forms of microimaging performed with standard light microscopes, confocal light microscopes, and electron microscopes. The image created by this microscope possesses several unique features: It is intrinsically three-dimensional; it can be formed with very high contrast, a characteristic of the phase-sensitive nature of the recording; the information contained in the image is obtained in a single exposure of the specimen, a feature that eliminates the accumulation of damage to living systems that can occur with techniques utilizing multiple exposures; the method of image construction is fundamentally free from aberration (distortion), thereby obviating the need to employ complex procedures for correction; the exact focal plane of any optical section is digitally determined through computation and is not based on any mechanical adjustments; and the principles of operation, including the computational processes and modalities of image presentation, are uniform over the full range of spectral coverage spanning from the visible (approximately 500 nm) to the X-ray (approximately 0.3 nm) regions. The application of this new technology is expected to open new cost-effective avenues to the understanding, prevention and treatment of broad areas of human disease.

Evidence for associations between the purinergic receptor P2X(7) (P2RX7) and toxoplasmosis.

Congenital Toxoplasma gondii infection can result in intracranial calcification, hydrocephalus and retinochoroiditis. Acquired infection is commonly associated with ocular disease. Pathology is characterized by strong proinflammatory responses. Ligation of ATP by purinergic receptor P2X(7), encoded by P2RX7, stimulates proinflammatory cytokines and can lead directly to killing of intracellular pathogens. To determine whether P2X(7) has a role in susceptibility to congenital toxoplasmosis, we examined polymorphisms at P2RX7 in 149 child/parent trios from North America. We found association (FBAT Z-scores +/-2.429; P=0.015) between the derived C(+)G(-) allele (f=0.68; OR=2.06; 95% CI: 1.14-3.75) at single-nucleotide polymorphism (SNP) rs1718119 (1068T>C; Thr-348-Ala), and a second synonymous variant rs1621388 in linkage disequilibrium with it, and clinical signs of disease per se. Analysis of clinical subgroups showed no association with hydrocephalus, with effect sizes for associations with retinal disease and brain calcifications enhanced (OR=3.0-4.25; 0.004

Netting and pan traps fail to identify the pollinator guild of an agricultural crop.

Pollinator decline is expected to cause significant reductions in food production and plant reproduction. Quantifying the impact of pollinator decline on food production requires survey methods that can identify insect and bee species responsible for pollination of specific crops. To address this issue, we compared the effectiveness of two survey methods, netting and pan traps, at capturing the pollinators of alfalfa, Medicago sativa. Alfalfa is a major component of forage for cows and an important ingredient in chicken feed. We also examined bee species richness and diversity with these two survey methods, and compared these measures among three different colors of pan traps. Netting was more effective at capturing known pollinators of alfalfa, especially those belonging to the Bombus and Apis genera. Pan traps captured a higher bee diversity relative to netting and, like previous studies, each survey method and each trap color was more efficient at capturing certain bee genera. However, without a priori knowledge of pollinators, neither survey method could identify which of the bee species captured could pollinate alfalfa. We therefore recommend direct observations when the goal of a study is to identify pollinators or link pollinator decline to food production.

Computer-aided evaluation of neuroblastoma on whole-slide histology images: Classifying grade of neuroblastic differentiation.

Neuroblastoma (NB) is one of the most frequently occurring cancerous tumors in children. The current grading evaluations for patients with this disease require pathologists to identify certain morphological characteristics with microscopic examinations of tumor tissues. Thanks to the advent of modern digital scanners, it is now feasible to scan cross-section tissue specimens and acquire whole-slide digital images. As a result, computerized analysis of these images can generate key quantifiable parameters and assist pathologists with grading evaluations. In this study, image analysis techniques are applied to histological images of haematoxylin and eosin (H&E) stained slides for identifying image regions associated with different pathological components. Texture features derived from segmented components of tissues are extracted and processed by an automated classifier group trained with sample images with different grades of neuroblastic differentiation in a multi-resolution framework. The trained classification system is tested on 33 whole-slide tumor images. The resulting whole-slide classification accuracy produced by the computerized system is 87.88%. Therefore, the developed system is a promising tool to facilitate grading whole-slide images of NB biopsies with high throughput.

Hot Rocks and Not-So-Hot Rocks on the Seashore: Patterns and Body-Size Dependent Consequences of Microclimatic Variation in Intertidal Zone Boulder Habitat.

Microclimatic variation has emerged as an important driver of many ecological and evolutionary processes. Nonetheless, fine-scale temperature data are still rare in most habitats, limiting our ability to understand the consequences of microclimatic variation under current and future conditions. We measured fine-scale thermal variation in a common, species-rich, but rarely studied habitat with respect to temperature: the airspaces under rocks on intertidal zone boulder shores. The effects of thermal variation were investigated using physiological, behavioral, and demographic responses of the porcelain crab Petrolisthes cinctipes. Habitat temperatures were measured at fine spatial and temporal resolution over 18 months, producing 424,426 temperature records. Microclimatic variation increased with increasing intertidal elevation, particularly with respect to heat extremes. However, mean temperatures were similar across the entire intertidal zone. Overheating risk for P. cinctipes increases with intertidal elevation but is size dependent, as large animals are more heat sensitive than small animals. Still, microclimatic variation high in the intertidal zone provided thermal refugia even under the warmest conditions. Size-dependent thermal responses predicted that large crabs should be rare high in the intertidal zone, which was supported by demographic data. Furthermore, simulations parameterized by our microclimate and organismal data recapitulated demographic patterns. Therefore, interactions between microclimatic variation and size-dependent thermal responses may have significant ecological repercussions that warrant greater attention.

Rocas calientes y rocas no tan calientes en la orilla del mar: patrones y consecuencias dependientes del tamaño del cuerpo de la variación microclimática en el hábitat de rocas intermareales (Hot rocks and not-so-hot rocks on the seashore: patterns and body-size dependent consequences of microclimatic variation in intertidal zone boulder habitat) La variación microclimática se ha convertido en un importante impulsor de muchos procesos ecológicos y evolutivos. No obstante, los datos de temperatura a pequeña escala aún son raros en la mayoría de los hábitats, lo que limita nuestra capacidad de comprender las consecuencias de la variación microclimática en las condiciones actuales y futuras. Medimos la variación térmica a pequeña escala en un hábitat común, rico en especies, pero rara vez estudiado con respecto a la temperatura: los espacios aéreos debajo de las rocas en las costas de rocas de zonas intermareales. Los efectos de la variación térmica se investigaron utilizando respuestas fisiológicas, conductuales y demográficas de los cangrejos de porcelana Petrolisthes cinctipes. Las temperaturas del hábitat se midieron con una resolución espacial y temporal fina durante 18 meses, produciendo 424.426 registros de temperatura. La variación microclimática aumentó con el aumento de la elevación intermareal, particularmente con respecto a los extremos de calor. Sin embargo, las temperaturas medias fueron similares en toda la zona intermareal. El riesgo de sobrecalentamiento de P. cinctipes aumenta con la elevación intermareal, pero depende del tamaño, ya que los animales grandes son más sensibles al calor que los animales pequeños. Aún así, la variación microclimática alta en la zona intermareal proporcionó refugios térmicos incluso en las condiciones más cálidas. Las respuestas térmicas dependientes del tamaño predijeron que los cangrejos grandes deberían ser raramente altos en la zona intermareal, lo que fue respaldado por datos demográficos. Además, las simulaciones parametrizadas por nuestros microclimas y datos organismales recapitularon patrones demográficos. Por lo tanto, las interacciones entre la variación microclimática y las respuestas térmicas dependientes del tamaño pueden tener importantes repercusiones ecológicas que justifican una mayor atención. Translated to Spanish by YE Jimenez (yordano_jimenez@brown.edu).

Rochas quentes e rochas não-tão-quentes à beira-mar: padrões e conseqüências dependentes do tamanho coporal para a variação microclimática no habitat de rochas da zona entremarés (Hot rocks and not-so-hot rocks on the seashore: patterns and body-size dependent consequences of microclimatic variation in intertidal zone boulder habitat) A variação microclimática emergiu como um importante causador de muitos processos ecológicos e evolutivos. No entanto, dados de temperatura em escala fina ainda são raros para a maioria dos habitats, limitando nossa capacidade de compreender as conseqüências da variação microclimática sob condições atuais e futuras. Nós medimos a variação térmica numa escala fina em um habitat comum, rico em espécies, mas raramente estudado em relação à temperatura: os espaços aéreos sob as rochas nas margens dos blocos de pedra da zona entremarés. Os efeitos da variação térmica foram investigados usando respostas fisiológicas, comportamentais e demográficas do caranguejo Petrolisthes cinctipes. As temperaturas do habitat foram medidas em resolução espacial e temporal ao longo de 18 meses, produzindo 424.426 registros de temperatura. A variação microclimática aumentou com o aumento da elevação intertidal, particularmente com relação aos extremos de calor. No entanto, as temperaturas médias foram semelhantes em toda a zona entremarés. O risco de superaquecimento de P. cinctipes aumenta com a elevação intertidal, mas é dependente do seu tamanho, já que os animais grandes são mais sensíveis ao calor do que os pequenos. Ainda assim, a variação microclimática alta na zona entremarés forneceu refúgios térmicos mesmo sob as condições mais quentes. Respostas térmicas dependentes do tamanho previam que os grandes caranguejos deveriam ser raros na zona entremarés, o que era apoiado por dados demográficos. Além disso, as simulações parametrizadas pelos nossos dados de microclima e organismal recapitularam padrões demográficos. Portanto, as interações entre a variação microclimática e as respostas térmicas dependentes do tamanho corporal podem ter repercussões ecológicas significativas que merecem maior atenção. Translated to Portuguese by G Sobral (gabisobral@gmail.com).

Modeling of clusters in a strong 248-nm laser field by a three-dimensional relativistic molecular dynamic model.

A relativistic time-dependent three-dimensional particle simulation model has been developed to study the interaction of intense ultrashort KrF (248 nm) laser pulses with small Xe clusters. The trajectories of the electrons and ions are treated classically according to the relativistic equation of motion. The model has been applied to a different regime of ultrahigh intensities extending to 10(21) W/ cm(2). In particular, the behavior of the interaction with the clusters from intensities of approximately 10(15) W/cm(2) to intensities sufficient for a transition to the so-called "collective oscillation model" has been explored. At peak intensities below 10(20) W/cm(2), all electrons are removed from the cluster and form a plasma. It is found that the "collective oscillation model" commences at intensities in excess of 10(20) W/cm(2), the range that can be reached in stable relativistic channels. At these high intensities, the magnetic field has a profound effect on the shape and trajectory of the electron cloud. Specifically, the electrons are accelerated to relativistic velocities with energies exceeding 1 MeV in the direction of laser propagation and the magnetic field distorts the shape of the electron cloud to give the form of a pancake.

Pulmonary paragonimiasis in Laotian refugee children.

Three Laotian refugee children with chronic pulmonary complaints and findings were found to have pulmonary paragonimiasis during a one-year period in Chicago. These patients ranged from 8 to 11 years of age and the diagnosis was delayed five to six months in two children because of the unfamiliarity of American physicians with signs and symptoms of this disorder. Clinical manifestations included chronic cough for up to two years, apparent hemoptysis in two patients, lack of fever or sweats, and family history negative for tuberculosis. Physical findings included rales and dullness to percussion, clubbing (one patient), and lack of fever or respiratory distress. All three patients showed interstitial infiltrates on chest roentgenogram whereas two had multiple small cystic areas. Moderate eosinophilia was present. Paragonimus westermani ova were found in stools of two patients, in sputum of two patients, and in bronchoscopic specimens in one patient. All patients demonstrated striking clinical and radiologic improvement following treatment with bithionol (50 mg/kg every other day for 15 doses), which was well tolerated. Lung fluke infestation must be considered in Indochinese refugee children with apparent hemoptysis or chronic pulmonary symptoms, and sputum and stool should be examined for P westermani ova.

Neurologic and developmental outcome in treated congenital toxoplasmosis.

BACKGROUND: Earlier studies have shown that infants with untreated congenital toxoplasmosis and generalized or neurologic abnormalities at presentation almost uniformly develop mental retardation, seizures, and spasticity. Children with untreated subclinical disease at birth have developed seizures, significant cognitive and motor deficits, and diminution in cognitive function over time. OBJECTIVE: To determine neurologic, cognitive, and motor outcomes for children with congenital toxoplasmosis who were treated for approximately 1 year with pyrimethamine and sulfadiazine. DESIGN AND METHODS: Systematic, prospective, and longitudinal neurologic, cognitive, and motor evaluations were performed for 36 individuals with congenital toxoplasmosis. These infants were born between December 1981 and January 1991 and were treated with pyrimethamine and sulfadiazine for approximately 1 year beginning in the first months of life. Compliance with medications was documented. These individuals were evaluated in a standardized manner in a single center in the first months of life and at approximately 1, 3.5, 5, 7.5, and 10 years of age. Their cognitive function was compared with the cognitive function of a nearest-age, same-sex sibling when such siblings older than 3.5 years were available for study. RESULTS: Signs of active central nervous system infection (eg, cerebrospinal fluid [CSF] pleiocytosis, hypoglycorrhachia, elevated CSF protein, and, in some instances, seizures and motor abnormalities) resolved during therapy. Six of the 36 children had perinatal seizures. Four had their anticonvulsant therapy discontinued successfully within the first months of life, and two additional children developed new seizures at 3 and 5 years of age. Tone and motor abnormalities resolved by 1 year of age in 12 of 20 infants who exhibited abnormalities of tone and motor function at their initial neonatal evaluation. By February 1992, 29 of the 36 children had been evaluated when they were 1 year old, and 23 (79%) had a mean +/- standard deviation Mental Developmental Index (MDI) of 102 +/- 22 (range, 59 to 140). Six (21%) had a measure of their cognitive function that was less than 50. Results of sequential IQ tests, performed at 1.5 year intervals or greater, did not differ significantly over time (P > .05). Seven children with MDIs greater than 50 were compared with sibling controls; they had scores of 87 +/- 11 (range, 68 to 97) and their siblings had scores of 112 +/- 15 (range, 85 to 132) (P = .008). Seventeen of 18 children without hydrocephalus and six of eight children with obstructive hydrocephalus responsive to shunting had normal or near-normal neurologic and developmental outcomes. Children with hydrocephalus ex vacuo present at birth, with high CSF protein, and with lack of response to shunting have done less well. CONCLUSIONS: Neurologic and developmental outcomes were significantly better for most of these treated children than outcomes reported for untreated children or those treated for only 1 month (P < .001). Although the level of cognitive function for treated children was less than for their uninfected siblings (P < .008), there was no significant deterioration in neurologic and cognitive function of the treated children tested sequentially. These favorable treatment outcomes justify systematic identification and treatment of pregnant women with acute gestational Toxoplasma infection and young infants with congenital toxoplasmosis.

Characteristics of patients receiving or foregoing resuscitation at the time of cardiopulmonary arrest.

OBJECTIVE: To compare clinical, functional and social characteristics of DNR patients at the time of their cardiopulmonary arrest with characteristics of patients who receive cardiopulmonary resuscitation. DESIGN: Retrospective chart review of all 261 patients who had a cardiopulmonary arrest during a 6-month period in an academic institution. SETTING: Teaching Veterans Affairs Medical Center serving a large metropolitan area. MEASUREMENTS: Demographic characteristics, medical diagnoses, and measures of functional status were collected when DNR orders were initiated and at the time of cardiopulmonary arrest. RESULTS: The mean age of the studied group was 62 years. Ninety-nine percent were males, and the majority were non-Hispanic white men. One hundred ninety-eight (76%) patients/proxies elected for limiting treatment. Most (85%) elected a DNR order only. Patients were the most frequently documented participants in advance directive decisions in the DNR group. At the time of cardiopulmonary arrest, a higher proportion of the CPR group had coronary artery disease or chronic renal failure, and a higher proportion of the DNR group had cancer or AIDS. The functional status of the DNR group deteriorated from the time of DNR order to death. At the time of cardiopulmonary arrest, the majority of both groups were dependent in all functional domains, and 70% of the DNR group were stuporous or comatose compared with 47% of the CPR group (P = .05). DNR patients were hospitalized for an average of 13.7 +/- 29.5 days after a DNR order was initiated. Six of the 81 patients who received CPR (7.4%) were alive at discharge. CONCLUSIONS: Patients and physicians deciding to implement a DNR order may be overly focused on medical diagnoses and less so on functional status. A significant proportion of patients with clinical characteristics associated with poor CPR outcome are electing for CPR.

Young children's performance on a task sensitive to the memory functions of the medial temporal lobe in adults--the delayed nonmatching-to-sample task--reveals problems that are due to non-memory-related task demands.

Delayed nonmatching-to-sample performance was examined in children and found to be poor from 12 months until almost 2 years even at 5-s delay, although 5 s is well within such children's memory capacity. After 12 months of age, performance did not differ by delay (5 or 30 s). Because children's problems seemed largely unrelated to the task's memory demands, the 2 final studies explored the role of other cognitive abilities (deduction of an abstract rule, speed of processing, and resistance to interference or distraction). Telling children the rule or quadrupling sample presentation time had little effect. Because a salient stimulus (the reward) might interfere with keeping one's attention on the sample, the reward was omitted during initial sample presentation. This helped; at the 5-s delay, 15-month-olds performed at least as well as 21-month-olds in the basic condition, and 12-month-olds performed almost as well. Implications for the cognitive abilities improving during the 2nd year and for the functions of the medial temporal lobe are discussed.

Immunological responses to injury and grafting in the central nervous system of nonhuman primates.

Allogeneic transplantation for the therapy of human Parkinson's disease is being considered as a viable approach at several clinical centers worldwide. As an attempt to understand the basic biology of central nervous system (CNS) transplantation, our laboratory has developed an experimental nonhuman primate model for human Parkinson's disease and carried out preliminary studies directed at evaluating the potential pathology at the graft site. In addition, studies have been conducted to examine whether such transplantation procedures lead to specific and/or nonspecific immunologic sensitization of the host or results in generalized immunosuppression. Groups of rhesus macaques (Macaca mulatta) were either controls operated (n = 6), autografted with adrenal medullary and peripheral nerve tissue (n = 3), or allografted with fetal mesencephalic tissue (n = 6). Immunohistological studies demonstrated the presence of mononuclear cell infiltrates as early as 1 wk and up to 1 yr postoperatively, although the frequency of the infiltrating cells declined with time. The infiltrates consisted of variable numbers of cells which express CD2+, CD3+, CD4+, CD8+, CD19+, CD22+, CD25+, and CD68+. There appeared to be no difference in the frequency, kinetics, or phenotype of the infiltrating cells in operative controls compared with recipients of auto- or allografts. Tissue sections obtained postoperatively showed low levels of major histocompatibility complex (MHC) Class I antigens and no detectable level of MHC-Class II antigens in neural tissue. A small aliquot of tissue from the operative site was placed in vitro with media containing interleukin-2 (IL-2), which led to the exudation and growth of mononuclear cells that were predominantly CD4+ cells. Phenotypic studies of peripheral blood mononuclear cells (PBMC) from operative controls, auto- and allograft recipient monkeys performed at varying time periods postoperatively failed to show differences in the frequencies of subsets of T-cells, B-cells, NK-cells, or monocytes. Studies on aliquots of the same PBMC failed to show major functional differences in NK-cells, LAK cells, or response to polyclonal mitogens. Finally, recipients of allogeneic mesencephalic grafts failed to show evidence of donor-specific humoral or cellular sensitization. These data indicate that transplantation of autograft adrenal or allograft fetal mesencephalic tissues in the CNS of nonhuman primate did not induce detectable donor-specific sensitization nor nonspecific immunosuppression.