The Antarctic Peninsula is one of the three fastest warming regions on Earth. Here we review Holocene proxy records of marine and terrestrial palaeoclimate in the region, and discuss possible forcing ...mechanisms underlying past change, with a specific focus on past warm periods. Our aim is to critically evaluate the mechanisms by which palaeoclimate changes might have occurred, in order to provide a longer-term context for assessing the drivers of recent warming. Two warm events are well recorded in the Holocene palaeoclimate record, namely the early Holocene warm period, and the `Mid Holocene Hypsithermal' (MHH), whereas there are fewer proxy data for the `Mediaeval Warm Period' (MWP) and the `Recent Rapid Regional' (RRR) warming. We show that the early Holocene warm period and MHH might be explained by relatively abrupt shifts in position of the Southern Westerlies, superimposed on slower solar insolation changes. A key finding of our synthesis is that the marine and terrestrial records in the AP appear to show markedly different behaviour during the MHH. This might be partly explained by contrasts in the seasonal insolation forcing between these records. Circumpolar Deep Water (CDW) has been implicated in several of the prominent changes through the Holocene but there are still differences in interpretation of the proxy record that make its influence difficult to assess. Further work is required to investigate contrasts between marine and terrestrial proxy records, east—west contrasts in palaeoclimate, the history of CDW, to retrieve a long onshore high resolution record of the Holocene, and determine the role of sea ice in driving or modulating palaeoclimate change, along with further efforts to study the proxy record of the RRR and the MWP.
Background Recent studies have shown that in several countries atopic sensitization to common allergens (common atopy) and atopic symptoms are markedly less prevalent in children living on a farm, ...compared with non‐farm children living in the same rural areas. Living conditions on farms may, however, vary largely between different countries. It is also not yet known whether the ‘protective’ effect of a farm environment can also be found in adults.
Materials and methods Common atopy and respiratory health were assessed by skin prick tests (SPT), questionnaire and measurement of bronchial hyper‐responsiveness (BHR) in the Sund Stald (SUS) study, a cohort study on respiratory health in Danish farming students and conscripts from the same rural areas as controls. Results of SPT were confirmed by IgE serology in all SPT+ subjects and a subset of SPT– subjects. Prevalences of common atopy, respiratory symptoms and bronchial hyper‐ responsiveness were compared for farmers and controls, and for those who had or had not lived on a farm in early childhood.
Results In multiple logistic regression analyses adjusting for ever smoking and a familial history of allergy, both being a farmer (ORs 0.62–0.75) and having had a farm childhood (ORs 0.55–0.75) appeared to contribute independently to a lower risk of sensitization to common allergens as assessed by SPT and IgE serology. A farm childhood was also inversely associated with high total IgE (OR 0.68), presence of respiratory symptoms (ORs 0.69–0.79) and BHR (OR 0.61) in these analyses. Direction and strength of the association between being a farmer and respiratory symptoms or BHR varied widely (ORs 0.69–1.28).
Conclusion The ‘anti‐atopy’ protective effect of a farm childhood could be confirmed in Danish farming students: prevalences of positive SPT, specific and total IgE, allergic symptoms and BHR were lower in those being born or raised on a farm. Past exposure to the farm environment in early childhood may therefore also contribute to a lower risk of atopic sensitization and disease at a later age.
Background. Antibody to hepatitis E virus (anti-HEV) is prevalent in Western countries, where clinical hepatitis E is rarely reported. The aim of this study was to determine the prevalence of ...anti-HEV among Danish blood donors and Danish farmers. In addition, we compared the prevalence among 2 sets of serum samples obtained from blood donors 20 years apart. Methods. Samples from 291 Danish farmers and 169 blood donors that were collected in 1983 and samples from 461 blood donors that were collected in 2003 were tested for anti-HEV. Relevant information on HEV exposure was collected by self-administered questionnaire. Results. Anti-HEV testing was performed on samples after 20 years of storage at −20°C. The prevalence of anti-HEV was 50.4% among farmers and 32.9% among donors in 1983 and 20.6% among donors in 2003 (P<.05). Presence of anti-HEV was significantly correlated with increasing age in all 3 groups (P<.05). Among donors who had serum samples obtained in 2003, age, contact with horses, and the presence of antibody to hepatitis A virus were associated with the presence of anti-HEV in multivariate analysis. Among farmers, only age was independently associated with the presence of anti-HEV. Conclusion. Anti-HEV was highly prevalent among Danes but has decreased in prevalence over the past 50 years. Our study supports the hypothesis that HEV infection in Denmark may be an asymptomatic zoonotic infection.
The aim of this study was to assess the prevalence of asthma (self-reported) and relate this to lung function and factors associated with asthma in young farmers. Two hundred and ten female and 1,691 ...male farming students together with 407 males controls were studied. Each subject underwent a medical interview; forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were recorded using a dry wedge spirometer. Histamine bronchial reactivity was measured using the Yan method. Skin prick testing was performed using inhalant allergens. Nonsmokers had lower prevalence of asthma (5.4-10.8%) than smokers (11.3-21.0%) (p<0.05). Females reported symptoms of asthma nearly twice as often as males. Sex, smoking and a family history of asthma/allergy were significantly associated with asthma. Controls had higher standardized FEV1 and FVC residuals than male students, both nonsmokers (0.21 and 0.24) versus (-0.06 and -0.05) and smokers (0.29 and 0.33) versus (-0.11 and 0.13) (p<0.032). Bronchial hyperresponsiveness, asthma, siblings with allergy and working with cattle (controls only) were significantly associated with reduced lung function. In conclusion, the prevalence of asthma was significantly related to smoking, female sex, family history of asthma and allergy. Whilst bronchial hyperresponsiveness was associated with reduced lung function and lung function was slightly reduced in the male farming students, there was no association found between occupational farming exposure and either lung symptoms or lung function.
The koji mold, Aspergillus oryzae is widely used for the production of industrial enzymes due to its particularly high protein secretion capacity and ability to perform post-translational ...modifications. However, systemic analysis of its secretion system is lacking, generally due to the poorly annotated proteome.
Here we defined a functional protein secretory component list of A. oryzae using a previously reported secretory model of S. cerevisiae as scaffold. Additional secretory components were obtained by blast search with the functional components reported in other closely related fungal species such as Aspergillus nidulans and Aspergillus niger. To evaluate the defined component list, we performed transcriptome analysis on three α-amylase over-producing strains with varying levels of secretion capacities. Specifically, secretory components involved in the ER-associated processes (including components involved in the regulation of transport between ER and Golgi) were significantly up-regulated, with many of them never been identified for A. oryzae before. Furthermore, we defined a complete list of the putative A. oryzae secretome and monitored how it was affected by overproducing amylase.
In combination with the transcriptome data, the most complete secretory component list and the putative secretome, we improved the systemic understanding of the secretory machinery of A. oryzae in response to high levels of protein secretion. The roles of many newly predicted secretory components were experimentally validated and the enriched component list provides a better platform for driving more mechanistic studies of the protein secretory pathway in this industrially important fungus.
In Aspergillus oryzae, one full-length chitin synthase (chsB) and fragments of two other chitin synthases (csmA and chsC) were identified. The deduced amino acid sequence of chsB was similar (87% ...identity) to chsB from Aspergillus nidulans, which encodes a class III chitin synthase. The sequence obtained for csmA indicated that it had high similarity to class V chitin synthases. chsB and csmA disruption strains and a strain in which chsB transcription was controlled were constructed using the nitrite reductase (niiA) promoter. The strains were examined during hyphal growth by Northern analysis, analysis of the cell-wall composition and growth in the presence of Calcofluor white (CFW). The chsB disrupted strain and the uninduced p(niiA)-chsB strain exhibited hyperbranching, they had a lower level of conidiation than the wild-type and were sensitive to CFW at 50 mg l(-1). When chsB transcription was induced in the strain containing the p(niiA)-chsB construct, the strain displayed wild-type morphology on solid medium and at sub-maximum growth rates but the wild-type morphology was not fully restored during rapid growth in batch cultivation. The csmA disruption strain displayed morphological abnormalities, such as ballooning cells, intrahyphal hyphae and conidial scars. The growth was severely inhibited in the presence of 10 mg CFW l(-1). In none of the constructed strains did the cell-wall composition differ from the wild-type. Northern analysis indicated no change in the transcription of the chitin synthase genes csmA and chsC when chsB expression was altered, and there was no change in the transcription of chsB and chsC when csmA was disrupted.
During the Quaternary period, ice sheets centred over the Barents and Kara seas expanded several times onto mainland Russia and blocked northflowing rivers, such as the Yenissei, Ob, Pechora and ...Mezen. Large ice-dammed lakes with reversed outlets, e.g. toward the Caspian Sea, formed south of these ice sheets. Some lakes are reconstructed from shorelines and lacustrine sediments, others mainly from ice-sheet configuration. Ice-dammed lakes, considerably larger than any lake on Earth today, are reconstructed for the periods 90–80 and 60–50
ka. The ages are based on numerous optically stimulated luminescence (OSL) dates. During the global Last Glacial Maximum (LGM, about 20
ka) the Barents–Kara Ice Sheet was too small to block these eastern rivers, although in contrast to the 90–80 and 60–50
ka maxima, the Scandinavian Ice Sheet grew large enough to divert rivers and meltwater across the drainage divide from the Baltic Basin to the River Volga, and that way to the Caspian Sea. Climate modelling shows that the lakes caused lower summer temperatures on the continent and on the lower parts of the ice sheet. The final drainage of the best mapped lake is modelled, and it is concluded that it probably emptied within few months. We predict that this catastrophic outburst had considerable impact on sea-ice formation in the Arctic Ocean and on the climate of a much larger area.
Earlier work in northeast Greenland has suggested a limited advance of the Greenland Ice Sheet during the Last Glacial Maximum (LGM). However, this concept has recently been challenged by marine ...geological studies, indicating grounded ice on the continental shelf at this time. New Be-10-ages from the Store Koldewey island, northeast Greenland, suggest that unscoured mountain plateaus at the outer coast were covered at least partly by cold-based ice during the LGM. It is, however, still inconclusive whether this ice was dynamically connected to the Greenland Ice Sheet or not. Regardless of the LGM ice sheet extent, the Be-10 results from Store Koldewey add to a growing body of evidence suggesting considerable antiquity of crystalline unscoured terrain near present and Pleistocene ice sheet margins.
Expression of several
Aspergillus niger genes encoding major secreted, but not vacuolar, protease genes including the major acid protease gene
pepA, was shown to be affected in the previously ...isolated
A. niger protease mutant, AB1.13 Mattern, I.E., van Noort, J.M., van den Berg, P., Archer, D.A., Roberts, I.N., Hondel, C.A.M.J.J., 1992. Isolation and characterization of mutants of
Aspergillus niger deficient in extracellular proteases. Molecular & General Genetics 2, 332–336. Complementation cloning of the putative protease-regulatory gene affected in this mutant was accomplished using a functional selection approach based on the use of the
A. nidulans amdS selection marker driven by the
A. niger pepA promoter. As expected the PpepA::amdS selection marker is not expressed in the mutant. Introduction of a self-replicating cosmid library into the mutant strain carrying the PpepA::amdS marker allowed selection of AmdS+ transformants functionally complementing the proposed regulatory mutation. Analysis of complementing cosmid clones revealed that the complementing sequences contained a gene encoding a member of the fungal-specific Zn2Cys6-binuclear cluster protein family. Sequence comparison of the encoded protein, PrtT, showed that it has homologues among different
Aspergillus species. The
A. oryzae homologue was shown to govern expression of the major alkaline protease AlpA and neutral protease Np1 in this species. In contrast to several other pathway specific regulators, such as AmyR and XlnR, no PrtT orthologues could be found in any other non-
Aspergillus (or related) species and surprisingly, also not in
Aspergillus nidulans. Interestingly, in all
Aspergillus species carrying a
prtT orthologue the gene is tightly clustered to a completely syntenous region carrying an amylolytic gene cluster including another Zn2Cys6-binuclear cluster protein, AmyR. Northern analysis of the
A. niger prtT gene showed (constitutive) expression from two upstream promoters about 700
bp apart. The presence of several short upstream open reading frames downstream of both the distal and the proximal transcription start point of the
prtT gene suggests regulation at the post-translational level. Also regulation at the level of differential splicing is suggested by the fact that several
Aspergillus EST databases carry a considerable fraction of clones in which in frame intron sequences are retained.
In this study we have tested a number of lipases, lipase variants and cutinases for ferulic acid esterase activity, using ferulic acid ethyl ester as substrate. It was shown that
Thermomyces ...lanuginosa lipase (TLL),
Candida antartica lipase A,
Candida antartica lipase B,
Rhizomucor miehei lipase and
Fusarium oxysporum lipase have no significant ferulic acid esterase activity. Thirteen variants of TLL were constructed based on a model of
Aspergillus niger ferulic acid esterase A (FAE-A). Activity assay using ferulic acid ethyl ester as substrate gave, for FAE-A, 112 U/mg=112 μmol ferulic acid released per min per mg enzyme. Two of the variants of TLL had significant ferulic acid esterase activity, TLLv1 (7 U/mg) and TLLv10 (20 U/mg). Both these variants contain the mutation F113Y that seems to be essential for ferulic acid esterase activity. In addition to lipase activity, three cutinases showed ferulic acid esterase activity,
Aspergillus oryzae cutinase (5 U/mg),
Fusarium solani pisi cutinase (13 U/mg),
Humicola insolence cutinase (20 U/mg).
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