The influence of physical environmental factors on the activity of Rhizobium in soil and in symbiosis

RESP-675

Genetic polymorphisms in molecules of innate immunity and susceptibility to infection with Wuchereria bancrofti in South India

A pilot study was conducted to determine if host genetic factors influence susceptibility and outcomes in human filariasis. Using the candidate gene approach, a well-characterized population in South India was studied using common polymorphisms in six genes (CHIT1, MPO, NRAMP, CYBA, NCF2, and MBL2). A total of 216 individuals from South India were genotyped; 67 normal (N), 63 asymptomatic microfilaria positive (MF+), 50 with chronic lymphatic dysfunction/elephantiasis (CP), and 36 tropical pulmonary eosinophilia (TPE). An association was observed between the HH variant CHIT1 genotype, which correlates with decreased activity and levels of chitotriosidase and susceptibility to filarial infection (MF+ and CP; P = 0.013). The heterozygosity of CHIT1 gene was over-represented in the normal individuals (P = 0.034). The XX genotype of the promoter region in MBL2 was associated with susceptibility to filariasis (P = 0.0093). Since analysis for MBL-sufficient vs insufficient haplotypes was not informative, it is possible the MBL2 promoter association results from linkage disequilibrium with neighboring loci. We have identified two polymorphisms, CHIT1 and MBL2 that are associated with susceptibility to human filarial infection, findings that merit further follow-up in a larger study

Source of the northeastern Idaho batholith: isotopic evidence for a Paleoproterozoic terrane in the northwestern U.S.

The northeastern portion of the Idaho batholith (NIB) intruded Proterozoic rocks of the Belt-Purcell supergroup between SO and 90 Ma. Whole-rock Sm-Nd isotopic analyses of batholithic rocks yield depleted mantle model ages (T oM) between 1. 72 and 1.93 Ga and values of eNd between -17. 7 and - 21.2, similar to associated metamorphic rocks and within the range for Belt-Purcell sedimentary rocks. Premagmatic zircons from one sample of the NIB were analyzed individually using the SHRIMP ion microprobe and yielded a single age population at 1.74 Ga. This apparently single-aged source contrasts with the range of ages reported for zircons from sedimentary rocks of the Belt-Purcell supergroup and suggests that the batholith was not the product of melting Belt-Purcell sediments, nor was it significantly contaminated with these sediments. The source of the batholith, however, appears to be of appropriate age and composition to be a major contributor of sediment to the Belt basin. In addition, the near coincidence of TOM and the age derived from premagmatic zircons in one sample suggests the source of at least part of the batholith was extracted largely from 1.74 Ga depleted mantle, with little or no input from older rocks. If so, this crust may represent a possible continuation of crust of similar age and character exposed to the north in the Canadian cordillera and to the south in Nevada, Arizona, and southeastern California

U-Pb-Hf-REE-Ti zircon and REE garnet geochemistry of the Cambrian Attunga eclogite, New England Orogen, Australia: Implications for continental growth along eastern Gondwana

The timing and location of eclogite metamorphism is central to understanding subduction events responsible for the assembly of eastern Gondwana. The Attunga eclogite is one of only six eclogites in Australia and occurs as small blocks within a schistose serpentinite mélange known as the Weraerai terrane, along the Peel Fault of the southern New England Orogen. Our zircon data reveal the presence of high Th/U oscillatory zoned magmatic zircon with a weighted mean 206Pb/238U age of 534 ± 14 Ma and recrystallized metamorphic domains with an age of 490 ± 14 Ma. The latter have lower Th/U ratios, mostly no Eu anomalies and heavy rare earth element (HREE)‐depleted patterns. Garnet rims demonstrate that the final stages of garnet growth occurred in a HREE‐depleted environment, due to coeval formation with metamorphic zircon. Direct application of the Ti‐in‐zircon thermometer to metamorphic zircon yields temperatures of 770–610°C. Hf isotopic analyses of the zircons have an average εHf(t) of +13, indicating a juvenile crustal signature. We interpret the Attunga eclogite to be an indicator of Late Cambrian subduction beneath an oceanic suprasubduction zone prior to accretion against eastern Gondwanan in the latest Devonian. Phillips et al. (2015) suggest two metamorphic age populations within the Attunga eclogite, based on U‐Pb zircon and 40Ar/39Ar phengite data. These are ~515 Ma and ~480 Ma. We confirm these data, but our zircon trace element chemistry data indicate that the Early Cambrian age (530 Ma) represents igneous protolith formation rather than eclogite metamorphism

Earth's oldest mantle fabrics indicate Eoarchaean subduction

The extension of subduction processes into the Eoarchaean era (4.0-3.6 Ga) is controversial. The oldest reported terrestrial olivine, from two dunite lenses within the ~3,720 Ma Isua supracrustal belt in Greenland, record a shape-preferred orientation of olivine crystals defining a weak foliation and a well-defined lattice-preferred orientation (LPO). [001] parallel to the maximum finite elongation direction and (010) perpendicular to the foliation plane define a B-type LPO. In the modern Earth such fabrics are associated with deformation of mantle rocks in the hanging wall of subduction systems; an interpretation supported by experiments. Here we show that the presence of B-type fabrics in the studied Isua dunites is consistent with a mantle origin and a supra-subduction mantle wedge setting, the latter supported by compositional data from nearby mafic rocks. Our results provide independent microstructural data consistent with the operation of Eoarchaean subduction and indicate that microstructural analyses of ancient ultramafic rocks provide a valuable record of Archaean geodynamics

Evidence for Life on Earth before 3,800 Million Years Ago

It is unknown when life first appeared on Earth. The earliest known microfossils (approx. 3,500 Myr before present) are structurally complex, and if it is assumed that the associated organisms required a long time to develop this degree of complexity, then the existence of life much earlier than this can be argued. But the known examples of crustal rocks older than approx. 3,500 Myr have experienced intense metamorphism, which would have obliterated any fragile microfossils contained therein. It is therefore necessary to search for geochemical evidence of past biotic activity that has been preserved within minerals that are resistant to metamorphism. Here we report ion-microprobe measurements of the carbon-isotope composition of carbonaceous inclusions within grains of apatite (basic calcium phosphate) from the oldest known sediment sequences a approx. 3,800 Myr-old banded iron formation from the Isua supracrustal belt, West Greenland, and a similar formation from the nearby Akilia island that is possibly older than 3,850 Myr. The carbon in the carbonaceous inclusions is isotopically light, indicative of biological activity; no known abiotic process can explain the data. Unless some unknown abiotic process exists which is able both to create such isotopically light carbon and then selectively incorporate it into apatite grains, our results provide evidence for the emergence of life on Earth by at least 3,800 Myr before present

Sources of variability in the measurement of Ascaris lumbricoides infection intensity by Kato-Katz and qPCR

Background Understanding and quantifying the sources and implications of error in the measurement of helminth egg intensity using Kato-Katz (KK) and the newly emerging “gold standard” quantitative polymerase chain reaction (qPCR) technique is necessary for the appropriate design of epidemiological studies, including impact assessments for deworming programs. Methods Repeated measurements of Ascaris lumbricoides infection intensity were made from samples collected in western Kenya using the qPCR and KK techniques. These data were combined with data on post-treatment worm expulsions. Random effects regression models were used to quantify the variability associated with different technical and biological factors for qPCR and KK diagnosis. The relative precision of these methods was compared, as was the precision of multiple qPCR replicates. Results For both KK and qPCR, intensity measurements were largely determined by the identity of the stool donor. Stool donor explained 92.4% of variability in qPCR measurements and 54.5% of observed measurement variance for KK. An additional 39.1% of variance in KK measurements was attributable to having expelled adult A. lumbricoides worms following anthelmintic treatment. For qPCR, the remaining 7.6% of variability was explained by the efficiency of the DNA extraction (2.4%), plate-to-plate variability (0.2%) and other residual factors (5%). Differences in replicate measurements by qPCR were comparatively small. In addition to KK variability based on stool donor infection levels, the slide reader was highly statistically significant, although it only explained 1.4% of the total variation. In a comparison of qPCR and KK variance to mean ratios under ideal conditions, the coefficient of variation was on average 3.6 times larger for KK highlighting increased precision of qPCR. Conclusions Person-to-person differences explain the majority of variability in egg intensity measurements by qPCR and KK, with very little additional variability explained by the technical factors associated with the practical implementation of these techniques. qPCR provides approximately 3.6 times more precision in estimating A. lumbricoides egg intensity than KK, and could potentially be made more cost-effective by testing each sample only once without diminishing the power of a study to assess population-level intensity and prevalence

Treatment of W. bancrofti (Wb) in HIV/Wb Coinfections in South India

Background: The disease course of human immunodeficiency virus (HIV) is often altered by existing or newly acquired coincident infections. Methodology/Principal Findings: To assess the influence of pre-existing Wuchereria bancrofti infection on HIV progression, we performed a case-controlled treatment study of HIV positive individuals with (FIL+) or without (FIL-) W. bancrofti infection. Twenty-eight HIV+/FIL+ and 51 matched HIV+/FIL- subjects were treated with a single dose of diethylcarbamazine and albendazole (DEC/Alb) and followed for a year at regular intervals. Sixteen of the HIV+/FIL+ subjects (54%) and 28 of the HIV+/FIL- controls (57%) were on antiretroviral therapy (ART) during the study. Following treatment, no differences were noted in clinical outcomes between the 2 groups. There also was no significant difference between the groups in the HIV viral load at 12 months as a percentage of baseline viral load (HIV+/FIL+ group had on average 0.97 times the response of the HIV+/FIL- group, 95% CI 0.88, 1.07) between the groups. Furthermore, there were no significant differences found in either the change in viral load at 1, 3, or 6 months or in the change in CD4 count at 3, 6, or 12 months between the 2 groups. Conclusions/Significance: We were unable to find a significant effect of W. bancrofti infection or its treatment on HIV clinical course or surrogate markers of HIV disease progression though we recognized that our study was limited by the smaller than predicted sample size and by the use of ART in half of the patients. Treatment of W. bancrofti coinfection in HIV positive subjects (as is usual in mass drug administration campaigns) did not represent an increased risk to the subjects, and should therefore be considered for PLWHA living in W. bancrofti endemic areas