Differential C Isotope Discrimination by Fungi during Decomposition of C3- and C4-Derived Sucrose

Stable isotope analysis is a major tool used in ecosystem studies to establish pathways and rates of C exchange between various ecosystem components. Little is known about isotopic effects of many such components, especially microbes. Here we report on the discovery of an unexpected pattern of C isotopic discrimination by basidiomycete fungi with far-reaching consequences for our understanding of isotopic processing in ecosystems where these microbes mediate material transfers across trophic levels. We measured fractionation effects on three ecologically relevant basidiomycete species under controlled laboratory conditions. Sucrose derived from C₃ and C₄ plants is fractionated differentially by these microbes in a taxon-specific manner. The differentiation between mycorrhizal and saprotrophic fungi observed in the field by others is not explained by intrinsic discrimination patterns. Fractionation occurs during sugar uptake and is sensitive to the nonrandom distribution of stable isotopes in the sucrose molecule. The balance between respiratory physiology and fermentative physiology modulates the degree of fractionation. These discoveries disprove the assumption that fungal C processing does not significantly alter the distribution of stable C isotopes and provide the basis for a reevaluation of ecosystem models based on isotopic evidence that involve C transfer across microbial interfaces. We provide a mechanism to account for the observed differential discrimination effects.     

Improvement in the bleaching of kraft pulp with xylanase from Penicillium crustosum FP 11 isolated from the Atlantic forest

Xylanase produced from the newly isolated Penicillium crustosum FP 11 and its potential in the prebleaching of kraft pulp were evaluated using a statistical approach. A Plackett–Burman design (PBD) was carried out to select the significant variables of the medium, these being NaNO₃, KH₂PO₄, MgSO₄, KCl, Fe₂(SO₄)₃, yeast extract, corn stover, and initial pH, in a liquid culture under static conditions for 6 d at 28?°C. Statistical analysis with a central composite design and response surface methodology showed that 0.15% (w/v) KH₂PO₄, 2% (w/v) corn stover, and an initial pH of 6.0 provided the best conditions for xylanase production. Furthermore, xylanase from P. crustosum FP 11 was effective in the bleaching of Eucalyptus kraft pulp, with a significant kappa efficiency of 35.04%. Therefore, the newly isolated P. crustosum FP 11 from the Atlantic Forest biome in Brazil showed two advantages: xylanase production with agricultural residue (corn stover) as a carbon source and an improvement in the bleaching of kraft pulp. Environmental pollution could thus be minimized because of a reduction in the use of chlorine as a bleaching agent.     

Biogenic methane contributes to the food web of a large,shallow lake

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Complete viral RNA genome sequencing of ultra-low copy samples by sequence-independent amplification

RNA viruses are the causative agents for AIDS, influenza, SARS, and other serious health threats. Development of rapid and broadly applicable methods for complete viral genome sequencing is highly desirable to fully understand all aspects of these infectious agents as well as for surveillance of viral pandemic threats and emerging pathogens. However, traditional viral detection methods rely on prior sequence or antigen knowledge. In this study, we describe sequence-independent amplification for samples containing ultra-low amounts of viral RNA coupled with Illumina sequencing and de novo assembly optimized for viral genomes. With 5 million reads, we capture 96 to 100% of the viral protein coding region of HIV, respiratory syncytial and West Nile viral samples from as little as 100 copies of viral RNA. The methods presented here are scalable to large numbers of samples and capable of generating full or near full length viral genomes from clone and clinical samples with low amounts of viral RNA, without prior sequence information and in the presence of substantial host contamination.     

Childhood Adversities and Adult Headache in Poland and Germany

Objective

Various childhood adversities have been found to be associated with chronic pain in adulthood. However, associations were moderate in most studies, i.e. odds ratios (OR) were between one and two.

Method

An internet survey was performed in 508 Polish and 500 German subjects. A total of 19 childhood adversities were selected and their associations with headaches explored. Age, gender and country were included as potential confounders, as well as their two-way interaction with the risk factors.

Results

Two strong risk factors were identified. (1) A combined score for physical and emotional neglect showed an odds ratio (OR) of 2.78 (p < .002) to the frequency of headache in adulthood as a main effect. (2) Father having had chronic pain showed an OR of 4.36 (p < .001) with headache in adulthood for women, but not for men (OR = 0.86, p < .556). The majority of the examined childhood adversities were not associated with adult headache, neither when tested individually nor as a sum score.

Conclusion

This study confirms results from previous ones that childhood adversities may play a role in the development of adult headache, but it is a rather minor one. Contrary to other studies, neglect turned out to be one of the strongest predictors.     

Polysomy of chromosome 7 is correlated with overexpression of the erbB oncogene in human glioblastoma cell lines

Summary Chromosome analysis in a series of human glioblastoma cell lines (HeRo, HeRo-SV¹, A172, T406, T508, T705) has indicated characteristic changes in the karyotype, the most striking and consistent of which is a significant increase in the copy number of chromosome 7, with up to 8 copies per metaphase. As determined by Spurr et al., chromosome 7 represents the genomic locus for the oncogene erbB (7pter-q22). Therefore, we have compared the number of chromosomes 7 to the levels of expression of the erbB oncogene. Interestingly, in all of them erbB-specific mRNA was found to be increased at levels even higher than expected from the number of chromosomes 7 found. In contrast, in an astrocytoma of slightly lower grade of malignancy (cell line T567), neither polysomy 7 nor significant expression of the erbB oncogene was noted.     

Influence of habitat characteristics on small mammals in a Mexican high-altitude grassland

Small mammals in a high-altitude grassland area close to Mexico City were studied. Populations of 10 species were censused using live traps in 48 sample quadrats. Within each quadrat, vegetation characterization, including complete floristic listings, cover values for species and layers and values of habitat modification, were assessed. Habitats were described according to plant communities identified using ordination and classification methods. Nine different plant communities were obtained. Densities and abundance of all small mammal species were calculated for each of the habitats classified. Peromyscus alsloni was the most abundant species in all habitats, reaching maximum densities of 55 ha⁻¹ in pine forest with dense ground and herb layer. Peromyscus melanotis also occurred in all habitats but at lower densities (maximum 29 ha⁻¹). Reithrodontomys megalotis was found in all habitats except in tall dense grassland. Densities for this species were generally low (1-9 ha⁻¹) but reached 19 ha⁻¹ in short dense grassland. All other species were largely absent from 4–8 habitats and showed very low densities (0.75–4 ha⁻¹). The densities of the more abundant species were largely correlated with more open habitats and higher indices of habitat modification. Lower altitude grassland habitats have a greater abundance of small mammals and a higher species richness than the medium and higher altitude, physiognomically more complex habitats. Species richness was highest in tall pine-alder forest with a species-rich, dense herb layer and lowest in pine forest with dense ground and herb layers. Species richness was positively correlated with overall small mammal density.     

More than royal food - <Emphasis Type="Italic">Major royal jelly protein</Emphasis> genes in sexuals and workers of the honeybee <Emphasis Type="Italic">Apis mellifera</Emphasis>

Background

In the honeybee Apis mellifera, female larvae destined to become a queen are fed with royal jelly, a secretion of the hypopharyngeal glands of young nurse bees that rear the brood. The protein moiety of royal jelly comprises mostly major royal jelly proteins (MRJPs) of which the coding genes (mrjp1-9) have been identified on chromosome 11 in the honeybee’s genome.

Results

We determined the expression of mrjp1-9 among the honeybee worker caste (nurses, foragers) and the sexuals (queens (unmated, mated) and drones) in various body parts (head, thorax, abdomen). Specific mrjp expression was not only found in brood rearing nurse bees, but also in foragers and the sexuals.

Conclusions

The expression of mrjp1 to 7 is characteristic for the heads of worker bees, with an elevated expression of mrjp1-4 and 7 in nurse bees compared to foragers. Mrjp5 and 6 were higher in foragers compared to nurses suggesting functions in addition to those of brood food proteins. Furthermore, the expression of mrjp9 was high in the heads, thoraces and abdomen of almost all female bees, suggesting a function irrespective of body section. This completely different expression profile suggests mrjp9 to code for the most ancestral major royal jelly protein of the honeybee.

     

The MagA protein of Magnetospirilla is not involved in bacterial magnetite biomineralization

Magnetotactic bacteria have the ability to orient along geomagnetic field lines based on the formation of magnetosomes, which are intracellular nanometer-sized, membrane-enclosed magnetic iron minerals. The formation of these unique bacterial organelles involves several processes, such as cytoplasmic membrane invagination and magnetosome vesicle formation, the accumulation of iron in the vesicles, and the crystallization of magnetite. Previous studies suggested that the magA gene encodes a magnetosome-directed ferrous iron transporter with a supposedly essential function for magnetosome formation in Magnetospirillum magneticum AMB-1 that may cause magnetite biomineralization if expressed in mammalian cells. However, more recent studies failed to detect the MagA protein among polypeptides associated with the magnetosome membrane and did not identify magA within the magnetosome island, a conserved genomic region that is essential for magnetosome formation in magnetotactic bacteria. This raised increasing doubts about the presumptive role of magA in bacterial magnetosome formation, which prompted us to reassess MagA function by targeted deletion in Magnetospirillum magneticum AMB-1 and Magnetospirillum gryphiswaldense MSR-1. Contrary to previous reports, magA mutants of both strains still were able to form wild-type-like magnetosomes and had no obvious growth defects. This unambiguously shows that magA is not involved in magnetosome formation in magnetotactic bacteria.