Geographical variability of bacterial communities of cryoconite holes of Andean glaciers

Cryoconite holes, ponds full of melting water with sediment on the bottom, are hotspots of biodiversity on glacier surfaces and host dynamic micro-ecosystems. They have been extensively investigated in different areas of the world (e.g., the Arctic, Antarctic, Alps, and Himalaya), but so far no study has described the bacterial communities of the glaciers in the Andes, the world's longest mountain range. In this study, we describe the bacterial communities of three small (< 2 km²) high-elevation (< 4200 m a.s.l.) glaciers of the Central Andes (Iver, East Iver and Morado glaciers) and two large (> 85 km²) glaciers of the Patagonian Andes (Exploradores and Perito Moreno glaciers) whose ablation tongues reach low altitude (< 300 m a.s.l.). Results show that the bacterial communities were generally similar to those observed in the cryoconite holes of other continents, but with few cyanobacteria (0.5% of sequences). The most abundant orders were Betaproteobacteriales, Cytophagales, Chitinophagales, Acetobacterales, Frankiales, Armatimonadales, Sphingobacteriales, Rhizobiales, Bacteroidales, Sphingomonadales, and Micrococcales. The bacterial communities differed between glaciers and both water pH and O₂ concentration appeared to influence the bacterial community composition. This work thus provides the first description of the bacterial communities in cryoconite holes of South American glaciers.

Bioremoval of copper by filamentous fungi isolated from contaminated soils of Puchuncaví-Ventanas Central Chile

Pollution represents a high risk to plants, animals, and human beings, causing an imbalance and affecting the environment. Soil is considered a universal sink, containing the highest load of environmental pollution. Puchuncaví-Ventanas sector, decreed as a saturated contamination zone in 1993, is considered one of the most affected areas by industrial pollution and belongs to one of the 5 sacrifice zones of Chile. The localities of Puchuncaví and Ventanas have heavy metal pollution levels that exceed up to 99% of the limits allowed by Canadian standards. The objective of this study was to characterize heavy metal tolerance and removal potential of filamentous fungi isolated from polluted soils for their use in decontamination systems and in situ soil improvement. Six fungal strains were selected based on their tolerance and a high capability to accumulate heavy metals, achieving copper bioaccumulation of 84% (Mortierella sp. strain LG01), 49% (Clonostachys sp. strain CQ23) and 48-77.5% (Trichoderma sp. strain LM01A). Trichoderma sp. strain LM01A was able to remove 41% of copper from contaminated soil under ex situ conditions. Some fungal strains belong to beneficial fungal genera, which are used as bioproducts in agriculture. The results of this study highlighted the use of Trichoderma sp. in soils contaminated, which may be of special interest in agriculture due to the large amounts of copper sulfate still applied as a pesticide in Chile and the world.

THU0603 IGG4-RELATED SINGLE-ORGAN DISEASE: IMMUNOSUPPRESSION NEEDED AFTER COMPLETE RESECTION? A CASE REPORT AN BRIEF LITERATURE REVIEW

Background:

IgG4-related disease (IgG4-RD) is a polymorphic autoimmune disease leading to tumourous swelling and/or fibrosis of affected organs. Riedel’s thyroiditis is – besides chronic periaortitis, Mikulicz Syndrome and many others – an organ manifestation of IgG4-RD that has been thought to be an independent disease for a long time. About 40% of patients have single organ IgG4-RD while the others suffer from multisystemic disease [1].

Objectives:

Glucocorticoids, sometimes combined with other immunosuppressives are the standard treatment of IgG4-RD, in some situations (e.g. mechanical complications or suspected malignancy) surgery may be necessary but little is known about the management of fully resected single-organ IgG4-RD [1].

Methods:

We report a case of single-organ IgG4-RD (Riedel’s thyroiditis) after complete resection and perform a brief review of the literature to guide clinical management in this situation.

Results:

A woman (51 y) with pre-existing Hashimoto’s thyroiditis (thyroid peroxidase antibody positive) developed a rapidly growing struma with very firm consistency (not allowing fine needle biopsy). Besides slightly increased C-reactive protein (5,3 mg/l) there was no laboratory sign suggestive for IgG4-RD (normal serum IgG4, complement, eosinophils and IgE). Within 4 months the patient suffered from hoarseness and progredient dyspnea. Surgical thyroidectomy was performed and histopathology revealed IgG4-related Riedel’s thyroiditis with extensive (storiform) fibrosis, a dense lymphoplasmacytic infiltrate, obliterative phlebitis, eosinophilia and 13 IgG4-positive plasma cells per high power field.

After referral to our department a comprehensive work-up showed no signs of other manifestations of IgG4-RD. Treatment with glucocorticoids is clearly recommended for patients with symptomatic IgG4-RD in an international consensus statement, whereas “watchful waiting” may be appropriate in some cases of asymptomatic or mild disease. While some highly fibrotic lesions may not respond well to glucocorticoids and may require surgical intervention, no clear guidance is available for the management of fully resected single organ IgG4-RD [2].

A brief review of the literature revealed that few cases of single-organ IgG4-RD remaining in remission after resection without medical treatment have been reported e.g. IgG4-related cholecystitis, autoimmune-pancreatitis, tumours of the intestinal tract, lung, thymus, meninges, paravertebral space and others [3–9].

After discussion of the options with the patient no systemic immunosuppression was given under close follow up without signs of relapse in clinical examinations, laboratory or imaging during the first 6 months.

Conclusion:

Limited evidence from case reports suggests that a “watchful waiting” strategy without systemic immunosuppressive treatment may be reasonable in some cases of single-organ IgG4-RD after the affected organ was completely resected (e.g. due to mechanical complications or suspected malignoma). However, close follow-up monitoring should be applied due to the risk of relapse or development of new organ manifestations.

References:

[1]Brito-Zerón et al.Best Pract. Res. Clin. Rheumatol.2016

[2]Khosroshahi et al.Arthritis Rheumatol.2015

[3]Takahashi et al.Surg. Case Rep.2015

[4]Akbari et al.ACG Case Rep. J.2018

[5]Oda et al.Thorac. Cancer2019

[6]Nambirajan et al.Childs Nerv. Syst. ChNS Off. J. Int. Soc. Pediatr. Neurosurg.2019

[7]Uchida et al.Asian J. Endosc. Surg.2018

[8]Hart et al.Mod. Pathol. Off. J. U. S. Can. Acad. Pathol. Inc2015

[9]Kim et al.Tuberc. Respir. Dis.2014

Disclosure of Interests:

Jan Schirmer: None declared, Marcus Seeger: None declared, Dominik Schulte Paid instructor for: Ferring, Speakers bureau: Amgen, Astra Zeneca, Braun, Fresenius, Ipsen, Johnson & Johnson, Lilly, MSD, Novartis, Novo Nordisk, Sanofi, Matthias Laudes Speakers bureau: Roche, Sanofi, Chugai, Stefan Schreiber Consultant of: AbbVie, Arena, BMS, Biogen, Celltrion, Celgene, IMAB, Gilead, MSD, Mylan, Pfizer, Fresenius, Janssen, Takeda, Theravance, provention Bio, Protagonist and Falk, Bimba F. Hoyer: None declared

10 W CEP-stable few-cycle source at 2 µm with 100 kHz repetition rate

We developed a high repetition rate optical parametric chirped-pulse amplification (OPCPA) laser system based on fiber-laser-seeded Innoslab to generate few-cycle pulses around 2 µm with passively stable carrier-envelope phase (CEP) by difference frequency generation (DFG). Incorporating a piezo mirror before the DFG stage permits rapid CEP control. The OPCPA system is seeded by a stable supercontinuum generated in bulk material with the picosecond Innoslab pulses. Few-cycle pulses with durations of 17 fs and energies of over 100 μJ were produced in a single OPCPA stage. Three different nonlinear crystals: BBO, BiBO, and LNB were tested in the final parametric amplifier, and their average power related limitations are addressed.

Complete genome sequence of the marine Rhodococcus sp. H-CA8f isolated from Comau fjord in Northern Patagonia, Chile

Rhodococcus sp. H-CA8f was isolated from marine sediments obtained from the Comau fjord, located in Northern Chilean Patagonia. Whole-genome sequencing was achieved using PacBio RS II platform, comprising one closed, complete chromosome of 6,19 Mbp with a 62.45% G + C content. The chromosome harbours several metabolic pathways providing a wide catabolic potential, where the upper biphenyl route is described. Also, Rhodococcus sp. H-CA8f bears one linear mega-plasmid of 301 Kbp and 62.34% of G + C content, where genomic analyses demonstrated that it is constituted mostly by putative ORFs with unknown functions, representing a novel genetic feature. These genetic characteristics provide relevant insights regarding Chilean marine actinobacterial strains.

Soil erosion in sloping vineyards under conventional and organic land use managements (Saar-Mosel Valley, Germany)

German vineyards are one of the land uses most prone to soil erosion. Due to their placement on mainly steep slopes and non-conservative cultivation practices, runoff and soil loss are a serious problem for wine growers. In the Saar-Mosel valley (Rhineland-Palatinate, Germany), there is a tendency towards organic management of vineyards with protective grass cover in the inter-rows. Since there is a lack of information about organic-conventional tillage in German vineyards related to soil erosion processes, this study presents a comparison between these two soil management practices. For this purpose, 22 rainfall simulations were performed as well as a medium-term monitoring by using 4-paired Gerlach troughs in two experimental sites in the Saar-Mosel valley. The mean simulated runoff coefficient and suspended sediment load in conventional vineyards amounted up to 23.3% and 33.75 g m-2, respectively. In the organic site, runoff and soil loss were only recorded in one out of the 11 simulations. Runoff and sediment was collected in the Gerlach troughs for 33 natural rainfall events. In the conventional vineyard, the total measured soil loss was 3314.63 g m-1 and 6503.77 g m-1 and total runoff volumes were 105.52 L m-1 and 172.58 L m-1. In the organic site, total soil losses reached 143.16 g m-1 and 258.89 g m-1 and total runoff was 21.65 L m-1 and 12.69 L m-1. When soil loss was measured without corresponding runoff or precipitation, soil erosion was activated by tillage or trampling. Finally, the conventional vineyard showed a higher variability in soil loss and runoff suggesting less predictable results.

Subcycle quantum electrodynamics

Squeezed states of electromagnetic radiation have quantum fluctuations below those of the vacuum field. They offer a unique resource for quantum information systems and precision metrology, including gravitational wave detectors, which require unprecedented sensitivity. Since the first experiments on this non-classical form of light, quantum analysis has been based on homodyning techniques and photon correlation measurements. These methods currently function in the visible to near-infrared and microwave spectral ranges. They require a well-defined carrier frequency, and photons contained in a quantum state need to be absorbed or amplified. Quantum non-demolition experiments may be performed to avoid the influence of a measurement in one quadrature, but this procedure comes at the expense of increased uncertainty in another quadrature. Here we generate mid-infrared time-locked patterns of squeezed vacuum noise. After propagation through free space, the quantum fluctuations of the electric field are studied in the time domain using electro-optic sampling with few-femtosecond laser pulses. We directly compare the local noise amplitude to that of bare (that is, unperturbed) vacuum. Our nonlinear approach operates off resonance and, unlike homodyning or photon correlation techniques, without absorption or amplification of the field that is investigated. We find subcycle intervals with noise levels that are substantially less than the amplitude of the vacuum field. As a consequence, there are enhanced fluctuations in adjacent time intervals, owing to Heisenberg's uncertainty principle, which indicate generation of highly correlated quantum radiation. Together with efforts in the far infrared, this work enables the study of elementary quantum dynamics of light and matter in an energy range at the boundary between vacuum and thermal background conditions.

Quantitative comparison of initial soil erosion processes and runoff generation in Spanish and German vineyards

The aim of this study was to enable a quantitative comparison of initial soil erosion processes in European vineyards using the same methodology and equipment. The study was conducted in four viticultural areas with different characteristics (Valencia and Málaga in Spain, Ruwer-Mosel valley and Saar-Mosel valley in Germany). Old and young vineyards, with conventional and ecological planting and management systems were compared. The same portable rainfall simulator with identical rainfall intensity (40mmh(-1)) and sampling intervals (30min of test duration, collecting the samples at 5-min-intervals) was used over a circular test plot with 0.28m(2). The results of 83 simulations have been analysed and correlation coefficients were calculated for each study area to identify the relationship between environmental plot characteristics, soil texture, soil erosion, runoff and infiltration. The results allow for identification of the main factors related to soil properties, topography and management, which control soil erosion processes in vineyards. The most important factors influencing soil erosion and runoff were the vegetation cover for the ecological German vineyards (with 97.6±8% infiltration coefficients) and stone cover, soil moisture and slope steepness for the conventional land uses.

Variación espacio-temporal de los procesos hidrológicos del suelo en viñedos con elevadas pendientes (Valle del Ruwer-Mosela, Alemania)

The vineyards of Ruwer-Mosel valley (Germany) cultivated on steep slopes showed a high spatial and temporal variability of hydrological dynamics. Forty two experiments were carried out using a Guelph permeameter in old and young vines to measure the infiltration rates, the hydraulic conductivity and the soil matrix flux potential. The essays were performed before (spring-summer) and after (autumn) the harvest with dry soil conditions and without soil tillage signals, and with humid soil conditions, signals of soil farming (wheel traffic and footprints) and a decrease of organic matter, respectively. In general, the results of the young vineyards were higher than the values of the old vineyards. Furthermore, all the rates increased after the harvest. For the young vineyards, the most elevated values were registered on the middle slope (398.5 mm h-1 infiltration rate, 89.2 mm h-1 hydraulic conductivity and 62.8 mm2 h-1 soil matrix flux potential). For its part, a decrease of the infiltration from the upper slope to the foot slope was observed (from 42.5 to 16.8 mm h-1). Hydraulic conductivity and soil matrix flux potential showed the same hydro-dynamic: from 13.2 to 5.4 mm h-1 and from 5.5 to 2.5 mm2 h-1, respectively. Finally, it was observed that the most correlated factor with these hydrological processes was the soil moisture content and the soil tillage practices.

Photothermal deflectometry enhanced by total internal reflection enables non-invasive glucose monitoring in human epidermis

We present TIR-PTD spectroscopy, an IR-pump/VIS-probe method for the measurement of IR absorption spectra by means of photothermal deflectometry (PTD) enhanced by total internal reflection (TIR). It overcomes the limitations of IR spectroscopy for the study of opaque samples and allows molecular fingerprinting of IR-active liquids or solids. Another important advantage of the presented approach over traditional IR spectroscopy methods is the ability to obtain IR information by means of VIS detection, which is generally much cheaper and easier to handle than IR detection. By application of mid-IR TIR-PTD spectroscopy on human skin in vivo, we are demonstrating the correlation between epidermal- and blood-glucose levels on a type 1 diabetic patient.

Soil Erosion on Abandoned Land in Andalusia: A Comparison of Interrill- and Rill Erosion Rates

The present paper is based on several field investigations (monitoring soil and rill erosion by aerial photography, rainfall simulations with portable rainfall simulators, and manmade rill flooding) in southern Spain. Experiments lead now to a closer understanding of the dynamics and power of different soil erosion processes in a gully catchment area. The test site Freila (Andalusia, Spain) covers an area of 10.01 ha with a rill density of 169 m ha−1, corresponding to a total rill length of 1694 m. Assuming an average rill width of 0.15 m, the total rill surface can be calculated at 250 m2 (0.025 ha). Given that, the surface covered by rills makes up only 0.25% of the total test site. Since the rill network drains 1.98 ha, 20% of the total runoff comes from rills. The rills’ sediment erosion was measured and the total soil loss was then calculated for detachment rates between 1685 g m−2 and 3018 g m−2. The interrill areas (99.75% of the test site) show values between 29 and 143 g m−2. This suggests an important role of rill erosion concerning runoff and soil detachment.

[Fibro-osseous pseudotumor of the hand in a 5-year old boy - a close relative to myositis ossificans]

Fibro-osseous pseudotumors of the hand are rare lesions in children. Clinical and radiological presentation can be challenging and simulating a malignant neoplasm. We present the case of a 5-year-old boy with a rapidly growing soft tissue tumor of the right palm. Diagnosis was confirmed by biopsy and the patient was treated with a tissue preserving resection. There was no evidence for recurrence 1 year after the operation.

Influence of microorganisms and leaching on simazine attenuation in an agricultural soil

Simazine is an s-triazine herbicide world widely used for the control of broadleaf weeds. The influence of leaching and microorganisms on simazine attenuation in an agricultural soil long-term treated with this herbicide was studied. To elucidate the leaching potential of simazine in this soil, undisturbed soil columns amended with simazine were placed in a specially designed system and an artificial precipitation was simulated. To evaluate the simazine removal by soil microorganisms, three soil microcosm sets were established: i) control soil; ii) soil subjected to gamma irradiation (γ-soil) and iii) γ-soil inoculated with the simazine-degrading bacterium Pseudomonas sp. strain MHP41. The simazine-degrading microorganisms in soil were estimated using an indicator for respiration combined with MPN enumeration. The simazine removal in soil was monitored by GC-ECD and HPLC. In this agricultural soil the leaching of the applied simazine was negligible. The gamma irradiation decreased in more than one order of magnitude the cultivable heterotrophic bacteria and reduced the simazine-degrading microorganisms. Simazine was almost completely depleted (97%) in control soil by natural attenuation after 23 d, whereas in γ-soil only 70% of simazine was removed. The addition of the simazine-degrading strain MHP41 to γ-soil restored and upheld high stable simazine catabolic microorganisms as well as increased the simazine removal (87%). The results indicated that simazine is subjected to microbial degradation with negligible leaching in this agricultural soil and pointed out the crucial role of native microbiota in the herbicide removal.

Measured turbulent mixing in a small-scale circuit breaker model

The performance of high voltage gas circuit breakers depends on the temperature distribution of hot gas or plasma from the arc zone mixed with cold gas that is present, for example, in the exhausts and mixing volume. Understanding the details of the mixing process is imperative to estimate the temperature distribution within the entire breaker volume. Design studies rely on computational fluid dynamics (CFD) simulations to search for the best way to achieve satisfactory mixing. One key uncertainty in the CFD simulations is the role of turbulence in this process and how to properly account for it. To gain knowledge of the mixing process between hot and cold gases, we have constructed a simplified breaker geometry that is flexible and accessible to diagnostics. Apart from standard measurements of current and arc voltage, we measure pressure in the arc zone and the mixing volume. Further, the mixing volume is specially designed to be transparent, allowing us to make shadowgraphy measurements of the turbulent mixing during and after the arcing phase. We report on experiments performed in air at atmospheric pressure.

Sonografische Diagnostik des akuten Milzinfarkts durch Echosignalverstärker

HISTORY AND CLINICAL FINDINGS

A 35-year-old patient with known mitral valve endocarditis presented with a stabbing pain in the left upper abdomen (patient 1). A 79-year-old patient with a history of chronic lymphocytic leukaemia (CLL) and aortic valve replacement presented with acute left upper quadrant, chest pain and impaired vision (patient 2).

INVESTIGATIONS

An abdominal ultrasound revealed nonhomogeneous hypoechoic splenic lesions in both patients, which were classified as extended splenic infarctions by echo enhancer studies. The diagnosis was confirmed by computed tomography. Transesophageal echocardiography showed extensive mitral valve vegetations in patient 1. Patient 2 had a progression of the CLL without evidence of endocarditis. Magnetic resonance imaging of the brain showed infarction of the posterior cerebral artery area.

DIAGNOSIS, TREATMENT AND COURSE

Patient 1: Mitral valve endocarditis with embolic splenic infarction. Patient 2: Progressive CLL with thrombotic splenic and brain infarction. In patient 1, mitral valve replacement was performed. In patient 2, chemotherapy was initiated and she was started on low molecular weight heparin s. c. and aspirin. No further embolic or thrombotic complications occurred. No splenectomy was performed.

CONCLUSION

A splenic infarction is a complication pointing towards an underlying serious disorder. Echo-enhanced ultrasound is as sensitive as computed tomography for early diagnosis. Splenic infarction should trigger urgent treatment of the underlying condition.

[Chromogenic substrate as antidote against the thrombin inhibitor Melagatran?]

It could be shown in vitro that a chromogenic substrate (Chromozym TH, Roche Mannheim) acts at least partially as antidote against the new thrombin inhibitor Melagatran (AstraZeneca, Mölndal, Sweden). It is discussed that this antidote effect of a chromogenic substrate might be due to a substrate competition of fibrinogen, thrombin inhibitor, and chromogenic substrate for thrombin. Further animal experiments will clarify whether this in vitro observation is of practical relevance in vivo, too.

Chromogenes Substrat als Antidot gegen den Thrombininhibitor Melagatran?

Mit In-vitro-Untersuchungen wird gezeigt, dass ein chromogenes Substrat (Chromozym TH von Roche, Mannheim) die gerinnungshemmende Wirkung des neuen Thrombininhibitors Melagatran (AstraZeneca, Mölndal, Schweden) zumindest partiell antagonisieren kann. Der hier beschriebene Antidoteffekt eines chromogenen Substrats gegenüber einem Thrombininhibitor könnte seine Erklärung darin finden, dass eine Substratkompetition zwischen Thrombins im Testsystem und Fibrinogen, Thrombininhibitor und chromogenem Substrat vorliegt. Tierversuche unter Einbeziehung weiterer Thrombininhibitoren könnten klären, ob die beschriebene Antidotwirkung die beobachteten Blutungskomplikationen tatsächlich reduzieren kann oder ob ein In-vitro-Phänomen vorliegt, das in vivo wenig Relevanz besitzt.

Proteins containing the UBA domain are able to bind to multi-ubiquitin chains

The UBA domain is a motif found in a variety of proteins, some of which are associated with the ubiquitin-proteasome system. We describe the isolation of a fission-yeast gene, mud1+, which encodes a UBA domain containing protein that is able to bind multi-ubiquitin chains. We show that the UBA domain is responsible for this activity. Two other proteins containing this motif, the fission-yeast homologues of Rad23 and Dsk2, are also shown to bind multi-ubiquitin chains via their UBA domains. These two proteins are implicated, along with the fission-yeast Pus1(S5a/Rpn10) subunit of the 26 S proteasome, in the recognition and turnover of substrates by this proteolytic complex.

Protein stability: the COP9 signalosome gets in on the act

The COP9 signalosome is a multiprotein complex somewhat similar to the lid component of the 26S proteasome. Recent studies suggest that it regulates the stability of proteins by interfering with the ubiquitin-proteasome pathway via deneddylation and phosphorylation.

Dehalogenation, denitration, dehydroxylation, and angular attack on substituted biphenyls and related compounds by a biphenyl dioxygenase

The attack by the bph-encoded biphenyl dioxygenase of Burkholderia sp. strain LB400 on a number of symmetrical ortho-substituted biphenyls or quasi ortho-substituted biphenyl analogues has been investigated. 2,2'-Difluoro-, 2,2'-dibromo-, 2,2'-dinitro-, and 2,2'-dihydroxybiphenyl were accepted as substrates. Dioxygenation of all of these compounds showed a strong preference for the semisubstituted pair of vicinal ortho and meta carbons, leading to the formation of 2'-substituted 2,3-dihydroxybiphenyls by subsequent elimination of HX (X = F, Br, NO(2), or OH). All of these products were further metabolized by 2,3-dihydroxybiphenyl 1,2-dioxygenases of Burkholderia sp. strain LB400 or of Rhodococcus globerulus P6. Dibenzofuran and dibenzodioxin, which may be regarded as analogues of doubly ortho-substituted biphenyls or diphenylethers, respectively, were attacked at the "quasi ortho" carbon (the angular position 4a) and its neighbor. This shows that an aromatic ring-hydroxylating dioxygenase of class IIB is able to attack angular carbons. The catechols formed, 2,3,2'-trihydroxybiphenyl and 2,3,2'-trihydroxydiphenylether, were further metabolized by 2,3-dihydroxybiphenyl 1,2-dioxygenase. While angular attack by the biphenyl dioxygenase was the main route of dibenzodioxin oxidation, lateral dioxygenation leading to dihydrodiols was the major reaction with dibenzofuran. These results indicate that this enzyme is capable of hydroxylating ortho or angular carbons carrying a variety of substituents which exert electron-withdrawing inductive effects. They also support the view that the conversions of phenols into catechols by ring-hydroxylating dioxygenases, such as the transformation of 2,2'-dihydroxybiphenyl into 2,3,2'-trihydroxybiphenyl, are the results of di- rather than of monooxygenations. Lateral dioxygenation of dibenzofuran and subsequent dehydrogenation and extradiol dioxygenation by a number of biphenyl-degrading strains yielded intensely colored dead-end products. Thus, dibenzofuran can be a useful chromogenic indicator for the activity of the first three enzymes of biphenyl catabolic pathways.

Mutant presenilin 1 increases the levels of Alzheimer amyloid beta-peptide Abeta42 in late compartments of the constitutive secretory pathway

Mutations in the presenilin 1 (PS1) gene are associated with autosomal dominant, early-onset, familial Alzheimer's disease and result in increased release of the hyperaggregatable 42-amino acid form of the amyloid beta-peptide (A(beta)42). To determine which subcellular compartments are potential source(s) of released Abeta42, we compared the levels and spatial segregation of intracellular A(beta)40 and A(beta)42 peptides between N2a neuroblastoma cells doubly transfected with the "Swedish" familial Alzheimer's disease-linked amyloid precursor protein variant and either wild-type PS1 (PS1(wt)) or familial Alzheimer's disease-linked delta9 mutant PS1 (PS1delta9). As expected, PS1delta9-expressing cells had dramatically higher levels of intracellular Abeta42 than did cells expressing PS1wt. However, the highest levels of A(beta)42 colocalized not with endoplasmic reticulum or Golgi markers but with rab8, a marker for trans-Golgi network (TGN)-to-plasma membrane (PM) transport vesicles. We show that PS1 mutants are capable of causing accumulation of A(beta)42 in late compartments of the secretory pathway, generating there a readily releasable source of A(beta)42. Our findings indicate that PS1 "bioactivity" localizes to the vicinity of the TGN and/or PM and reconcile the apparent discrepancy between the preponderant concentration of PS1 protein in proximal compartments of the secretory pathway and the recent findings that PS1 "bioactivity" can control gamma-secretase-like processing of another transmembrane substrate, Notch, at or near the PM.

Generation of the amyloid-beta peptide N terminus in Saccharomyces cerevisiae expressing human Alzheimer's amyloid-beta precursor protein

The Alzheimer's amyloid-beta precursor protein (betaAPP) is a type 1 membrane-spanning protein from which the Alzheimer's disease amyloid-beta peptide (Abeta) is proteolytically derived. To date, attempts to identify the enzymes responsible for Abeta generation have failed. Here we report the accumulation of Abeta-immunoreactive peptides in yeast expressing human betaAPP. Characterization of these peptides by metabolic labeling, immunoprecipitation with Abeta-specific antibodies, and N-terminal radiosequencing indicates that these peptides include the Abeta peptide at their N termini. The Abeta-like peptides generated in yeast were recovered predominantly as 8- and 12-14-kDa species. A 4-kDa species was recovered either when a protease-deficient strain was used to prevent breakdown or when the 8- and 12-14-kDa species were treated with disaggregating agents. The likely existence in yeast of enzymes generating the Abeta N terminus indicates that the molecular identification of yeast beta-secretase-like enzymes may be accomplished using genetic screens or empirical approaches based upon the sequenced genome of Saccharomyces cerevisiae.

Regiospecificity of dioxygenation of di- to pentachlorobiphenyls and their degradation to chlorobenzoates by the bph-encoded catabolic pathway of Burkholderia sp. strain LB400

Burkholderia sp. strain LB400 is one of the most potent aerobic polychlorobiphenyl (PCB)-degrading microorganisms that have been characterized. Its PCB-dioxygenating activity originates predominantly or exclusively from the biphenyl dioxygenase encoded by its bph gene cluster. Analysis of the dioxygenation products of several di- to pentachlorinated biphenyls formed by this enzyme revealed a complex dependence of the regiospecificity and the yield of dioxygenation on the substitution patterns of both the oxidized and the nonoxidized rings. No dioxygenolytic attack involving chlorinated meta or para carbons was observed. Therefore, the ability of the enzyme to hydroxylate chlorinated carbons appears to be limited to the ortho position. However, it is not limited to monochlorinated rings, as evidenced by dioxygenation of the 2, 4-disubstituted ring at carbons 2 and 3. This site of attack is strikingly different from that of the 2,5-dichlorinated ring, which has been shown to be dihydroxylated at positions 3 and 4 (J. D. Haddock, J. R. Horton, and D. T. Gibson, J. Bacteriol. 177:20-26, 1995). These results demonstrate that a second substituent of ortho-chlorinated rings crucially influences the site of dioxygenation at this ring and thereby determines whether or not the initial chlorobiphenyl oxidation product is further metabolized through the bph-encoded pathway. The 2,4-dichlorinated ring can alternatively be attacked at carbons 5 and 6. The preferred site crucially depends on the substitution pattern of the other ring. The formation of more than a single dioxygenation product was found predominantly with congeners that contain two chlorinated rings, both of which are similarly prone to dioxygenation or one is substituted only at carbon 3.

Developmental expression of wild-type and mutant presenilin-1 in hippocampal neurons from transgenic mice: evidence for novel species-specific properties of human presenilin-1

Presenilins 1 (PS1) and 2 (PS2) are multispanning transmembrane proteins associated with familial Alzheimer disease (FAD). They are developmentally regulated, being expressed at highest levels during neuronal differentiation and are sustained at a lower level throughout life. We investigated the distribution and metabolism of endogenous murine PS1 as well as human wild-type (wtPS1) and the familial AD Met146Leu (M146L) mutant presenilins in dissociated cultures of hippocampal neurons derived from control and transgenic mice. We found that the PS1 endoproteolytic fragments and, to a lesser extent, the full-length protein, were expressed as early as day 3 post-plating. Both species increased until the cells were fully differentiated at day 12. Confocal microscopy revealed that presenilin is present in the Golgi and endoplasmic reticulum and, as in punctate, vesicle-like structures within developing neurites and growth cones. Using a human-specific PS1 antibody, we were able to independently examine the distribution of the transgenic protein which, although similar to the endogenous, showed some unique qualities. These included (i) some heterogeneity in the proteolytic fragments of human PS1; (ii) significantly reduced levels of full-length human PS1, possibly as a result of preferential processing; and (iii) a more discrete intracellular distribution of human PS1. Colocalization with organelle-specific proteins revealed that PS1 was located in a diffuse staining pattern in the MAP2-positive dendrites and in a punctate manner in GAP43-positive axons. PS1 showed considerable overlap with GAP43, particularly at the growth cones. Similar patterns of PS1 distribution were detected in cultures derived from transgenic animals expressing human wild-type or mutant presenilins. The studies demonstrate that mutant presenilins are not grossly different in their processing or distribution within cultured neurons, which may represent more physiological models as compared to transfection systems. Our data also suggest that the molecular pathology associated with PS1 mutations results from subtle alterations in presenilin function, which can be further investigated using these transgenic neuronal cell culture models.

Comparison of human COP9 signalsome and 26S proteasome lid'

The human core COP9 signalosome consists of eight subunits which have been identified, cloned and sequenced. The components of COP9 signalosome possess homologies with eight non-ATPase regulatory subunits of the 26S proteasome. These polypeptides of the 19S regulator form a reversibly binding subcomplex called the 'lid'. We isolated the 'lid' from human red blood cells and compared it with the COP9 signalosome complex. In addition to the non-ATPase regulatory polypeptides, we found a high molecular mass ATPase copurifying with the human 'lid'. The COP9 signalosome-associated kinase activity is either not at all or only weakly affected by common kinase inhibitors such as 1-(5-Isoquinolinesulfonyl)-2-methyl-piperazine (H7), 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole (DRB) or Wortmannin. Curcumin, a tumor suppressor and effector of AP-1 activation, is a potent inhibitor of the COP9 signalosome kinase activity with a Ki of about 10 microM. Since curcumin is known as an inhibitor of the c-Jun N-terminal kinase (JNK) signaling pathway acting upstream of the MAP kinase kinase kinase level, one site of action of the COP9 signalosome might be proximal to regulators on that level.

The netrin receptor frazzled is required in the target for establishment of retinal projections in the Drosophila visual system

Retinal axons in Drosophila make precise topographic connections with their target cells in the optic lobe. Here we investigate the role of the Netrins and their receptor Frazzled in the establishment of retinal projections. We find that the Netrins, although expressed in the target, are not required for retinal projections. Surprisingly, Frazzled, found on both retinal fibers and target cells, is required in the target for attracting retinal fibers, while playing at best a redundant role in the retinal fibers themselves; this finding demonstrates that target attraction is necessary for topographic map formation. Finally, we show that Frazzled is not required for the differentiation of cells in the target. Our data suggest that Frazzled does not function as a Netrin receptor in attracting retinal fibers to the target; nor does it seem to act as a homotypic cell adhesion molecule. We favor the possibility that Frazzled in the target interacts with a component on the surface of retinal fibers, possibly another Netrin receptor.

Involvement of cell surface glycosyl-phosphatidylinositol-linked aspartyl proteases in alpha-secretase-type cleavage and ectodomain solubilization of human Alzheimer beta-amyloid precursor protein in yeast

Human beta-amyloid precursor protein (APP) introduced into yeast undergoes alpha-secretase-type cleavage, suggesting that yeast have alpha-secretase-like protease(s). Here we report that two structurally and functionally related glycosyl-phosphatidylinositol-linked yeast aspartyl proteases, Mkc7p and Yap3p (collectively termed yapsin), are responsible for alpha-secretase-type cleavage of APP expressed in yeast, resulting in release of soluble APP into the extracellular space. Disruption of MKC7 and YAP3 in a vacuolar protease-deficient strain abolished this APP cleavage/release, and APP cleavage/release could be restored by introduction of MKC7 or YAP3 on a single copy plasmid. Purified Mkc7p cleaved an internally quenched fluorogenic APP peptide substrate at the alpha-secretase cleavage site. Measurement of proteolytic activity either in yeast homogenates or on the yeast cell surface revealed that most Mkc7p and Yap3p activities were localized at the cell surface. These results establish a molecular basis for alpha-secretase-type cleavage in yeast and support the generally held concept that alpha-secretase cleavage of APP occurs at the cell surface.

The Pad1+ gene encodes a subunit of the 26 S proteasome in fission yeast

We have isolated a fission yeast mutant, mts5-1, in a screen for mutations that confer both methyl 2-benzimidazolecarbamate resistance (MBCR) and temperature sensitivity (ts) on Schizosaccharomyces pombe. This screen has previously isolated mutations in the 26 S proteasome subunits Mts2, Mts3, and Mts4. We show that the mutation in the mts5-1 strain occurs in the pad1(+) gene. pad1(+) was originally isolated on a multicopy plasmid that was capable of conferring staurosporine resistance on a wild type strain. mts5-1/pad1-1 has a similar phenotype to 26 S proteasome mutants previously isolated in the same screen and we show that Pad1 interacts genetically with two of these subunits, Mts3 and Mts4. In this study we describe the identification of Pad1 as a subunit of the 26 S proteasome in fission yeast.

Antigen-independent suppression of the IgE immune response to bee venom phospholipase A2 by maternally derived monoclonal IgG antibodies

The IgE immune response to ovalbumin in rats can be suppressed by prior immunization of the dams. The results reported in this paper extend this observation to include a different antigen and another species, namely the IgE immune response to bee venom phospholipase A2 (PLA2) in CBA/J mice. The degree of suppression seemed to depend on the amount of IgG antibodies transferred to the offspring. Moreover, we found that the maternally mediated suppression of the IgE response could be achieved in a completely antigen-free system in which exogenous monoclonal anti-PLA2 IgG antibodies were transferred from the dams to the offspring. The following results were obtained: (i) The IgE suppression by monoclonal IgG antibodies was induced as efficiently with one single anti-PLA2 IgG1 antibody as with a mixture of ten antibodies (nine IgG1, one IgG2b). (ii) Even after several immunizations up to an age of 6 months with a dose of PLA2 that normally induces IgE production, none of the F1 mice developed an IgE response. (iii) This long-lasting suppression was observed in mice which were first immunized at an age of 4 weeks (i.e. when low amounts of maternally derived monoclonal IgG were still present), as well as in mice which were first immunized at an age of 8 weeks, when no such maternal antibodies could be detected in their sera. The corresponding IgG responses showed, compared to normal mice, a transient enhancement in the maternally influenced mice. It is concluded that the immunological experience of the mother is of particular importance for the isotype regulation in the newborns, especially with respect to the ability to elicit an IgE response. The possible implications for the development of allergic diseases in humans are discussed.

Estrogen reduces neuronal generation of Alzheimer beta-amyloid peptides

Alzheimer's disease (AD) is characterized by the accumulation of cerebral plaques composed of 40- and 42-amino acid beta-amyloid (Abeta) peptides, and autosomal dominant forms of AD appear to cause disease by promoting brain Abeta accumulation. Recent studies indicate that postmenopausal estrogen replacement therapy may prevent or delay the onset of AD. Here we present evidence that physiological levels of 17beta-estradiol reduce the generation of Abeta by neuroblastoma cells and by primary cultures of rat, mouse and human embryonic cerebrocortical neurons. These results suggest a mechanism by which estrogen replacement therapy can delay or prevent AD.

A novel protein complex involved in signal transduction possessing similarities to 26S proteasome subunits

A novel protein complex has been identified in human cells that has a molecular mass of approximately 450 kDa. It consists of at least eight different subunits including JAB1, the Jun activation-domain binding protein 1, and Trip15, the thyroid hormone receptor-interacting protein 15. The purified complex contains COP9 and COP11 protein homologs and is very similar, if not identical, to the plant COP9 complex involved in light-mediated signal transduction. The isolated JAB1-containing particle has kinase activity that phosphorylates IkappaBalpha, the carboxy terminus of p105, and Ser63 and/or Ser73 of the amino-terminal activation domain of c-Jun. The phosphorylation of c-Jun requires the carboxy terminus of the protein containing the DNA binding and dimerization domains. Three subunits of the new complex--Sgn3, Sgn5/JAB1, and Sgn6--exhibit sequence similarities to regulatory components of the 26S proteasome, which could indicate the existence of common substrate binding sites. Immunofluorescence staining reveals that the new complex shows a subcellular distribution similar to that of the 26S proteasome. The functional relationship of the two particles in regulating transcriptional activity is discussed. Considering the putative role of the complex in signal transduction and its widespread occurrence, we suggest the name JAB1-containing signalosome.

Presenilin 1 is actively degraded by the 26S proteasome

The metabolic pathways governing the turnover of presenilin 1 (PS1) have been incompletely worked out. The PS1 holoprotein has low abundance in many cells and appears to undergo endoproteolytic cleavage near residue 298. We provide evidence that one mechanism by which the PS1 holoprotein is degraded is through the action of the 26S proteasome. We also show that the proteasome does not participate in the endoproteolytic cleavage.

Transversal and longitudinal images from the retina of the living eye using low coherence reflectometry

An optical coherence tomography (OCT) system to produce both longitudinal and transversal images of the in vivo human eye is presented. For the first time, OCT transversal images collected from the living eye at 50-μm depth steps show details unobtainable with the state-of-the-art scanning laser ophthalmoscope. Images of up to 3×3 mm are produced from the retina in less than a second. For images larger than 1.6×1.6 mm, a path modulation is introduced by the galvanometric scanning mirror and is used as an effective phase modulation method.© 1998 Society of Photo-Optical Instrumentation Engineers.

Resistance to diverse drugs and ultraviolet light conferred by overexpression of a novel human 26 S proteasome subunit

We have investigated the usefulness of the fission yeast Schizosaccharomyces pombe as a model organism for the discovery of novel modes of drug resistance in human cells. In fission yeast, overexpression of the essential pad1(+) gene confers pleiotropic drug resistance through a pathway involving an AP-1 transcription factor encoded by pap1(+). We have identified POH1, a human pad1 homologue that can substitute fully for pad1(+) and induce AP-1-dependent drug resistance in fission yeast. POH1 also confers P-glycoprotein-independent resistance to taxol (paclitaxel), doxorubicin, 7-hydroxystaurosporine, and ultraviolet light when transiently overexpressed in mammalian cells. Poh1 is a previously unidentified component of the human 26 S proteasome, a multiprotein complex that degrades proteins targeted for destruction by the ubiquitin pathway. Hence, Poh1 is part of a conserved mechanism that determines cellular susceptibility to cytotoxic agents, perhaps by influencing the ubiquitin-dependent proteolysis of transcription factors.

Mts4, a non-ATPase subunit of the 26 S protease in fission yeast is essential for mitosis and interacts directly with the ATPase subunit Mts2

We have isolated a fission yeast gene, mts4(+), by complementation of a temperature-sensitive mutation and show that it encodes subunit 2 (S2) of the 19 S regulatory complex of the 26 S protease. mts4(+) is an essential gene, and we show that loss of this subunit causes cells to arrest in metaphase, illustrating the importance of S2 for mitosis. The Mts4 protein is 48% identical to S2 of the human 26 S protease, and the lethal phenotype of the null mts4 allele can be rescued by the human cDNA encoding S2. We provide genetic and physical evidence to suggest that the Mts4 protein interacts with the product of the mts2(+) gene, an ATPase which has previously been shown to be subunit 4 of the 26 S protease.

Evidence for phosphorylation and oligomeric assembly of presenilin 1

Pathogenic mutations in presenilin 1 (PS1) are associated with approximately 50% of early-onset familial Alzheimer disease. PS1 is endoproteolytically cleaved to yield a 30-kDa N-terminal fragment (NTF) and an 18-kDa C-terminal fragment (CTF). Using COS7 cells transfected with human PS1, we have found that phorbol 12, 13-dibutyrate and forskolin increase the state of phosphorylation of serine residues of the human CTF. Phosphorylation of the human CTF resulted in a shift in electrophoretic mobility from a single major species of 18 kDa to a doublet of 20-23 kDa. This mobility shift was also observed with human PS1 that had been transfected into mouse neuroblastoma (N2a) cells. Treatment of the phosphorylated CTF doublet with phage lambda protein phosphatase eliminated the 20- to 23-kDa doublet while enhancing the 18-kDa species, consistent with the interpretation that the electrophoretic mobility shift was due to the addition of phosphate to the 18-kDa species. The NTF and CTF eluted from a gel filtration column at an estimated mass of over 100 kDa, suggesting that these fragments exist as an oligomerized species. Upon phosphorylation of the PS1 CTF, the apparent mass of the NTF- or CTF-containing oligomers was unchanged. Thus, the association of PS1 fragments may be maintained during cycles of phosphorylation/dephosphorylation of the PS1 CTF.

HIV-1 tat inhibits the 20 S proteasome and its 11 S regulator-mediated activation

The proteasomal system consists of a proteolytic core, the 20 S proteasome, which associates in an ATP-dependent reaction with the 19 S regulatory complex to form the functional 26 S proteasome. In the absence of ATP, the 20 S proteasome forms a complex with the gamma-interferon-inducible 11 S regulator. Both the 20 S proteasome and the 11 S regulator have been implied in the generation of antigenic peptides. The human immunodeficiency virus (HIV)-1 Tat protein causes a number of different effects during acquired immunodeficiency syndrome (AIDS). Here we show that HIV-1 Tat protein strongly inhibits the peptidase activity of the 20 S proteasome and that it interferes with formation of the 20 S proteasome-11 S regulator complex. In addition, it slightly increases the activity of purified 26 S proteasome. These results may explain the mechanism by which HIV-1-infected cells escape cytotoxic T lymphocyte response and at least in part immunodeficiency in AIDS patients.

Heterologous expression of biphenyl dioxygenase-encoding genes from a gram-positive broad-spectrum polychlorinated biphenyl degrader and characterization of chlorobiphenyl oxidation by the gene products

The bphA1A2A3A4 gene cluster, encoding a biphenyl dioxygenase from Rhodococcus globerulus P6, a gram-positive microorganism able to degrade a wide spectrum of polychlorobiphenyls (PCBs), was expressed in Pseudomonas putida, thereby allowing characterization of chlorobiphenyl oxidation by this enzyme. While P6 biphenyl dioxygenase activity was observed in P. putida containing bphA1A2A3A4, no activity was detected in Escherichia coli cells containing the same gene cluster. In E. coli, transcription of genes bphB and bphCl, located downstream of bphA1A2A3A4, was shown to be driven solely by a vector promoter, which indicated that the lack of biphenyl dioxygenase activity was not due to a lack of mRNA synthesis. Radioactive labelling of bph gene products in E. coli implied inefficient translation of the bphA gene cluster or rapid degradation of the gene products. The biosynthesis of functional P6 biphenyl dioxygenase in P. putida cells containing the same plasmid construct that yielded no activity in E. coli emphasizes the importance of the host strain for heterologous expression and shows that synthesis, correct folding, and assembly of a Rhodococcus biphenyl dioxygenase can be achieved in a gram-negative organism. Dioxygenation of six mono- and dichlorinated PCB congeners by P. putida containing the P6 bphA gene cluster indicates the following ring substitution preference for this reaction (from most to least preferred): un-, meta-, para-, and ortho-substitution. No indications were found for dioxygenation of meta/para carbon pairs, or for hydroxylation of chlorinated carbons at any position of a monochlorinated ring, suggesting a strict specificity of this biphenyl dioxygenase for attack at nonhalogenated ortho/meta vicinal carbons. This contrasts the properties of an analogous enzyme from Pseudomonas sp. strain LB400, which can both dioxygenate at meta and para positions and dehalogenate substituted ortho carbons during ortho and meta dioxygenation.