All-trans retinoic acid works synergistically with the γ-secretase inhibitor crenigacestat to augment BCMA on multiple myeloma and the efficacy of BCMA-CAR T cells

B-cell maturation antigen (BCMA) is the lead antigen for chimeric antigen receptor (CAR) T-cell therapy in multiple myeloma (MM). A challenge is inter- and intra-patient heterogeneity in BCMA expression on MM cells and BCMA downmodulation under therapeutic pressure. Accordingly, there is a desire to augment and sustain BCMA expression on MM cells in patients that receive BCMA-CAR T-cell therapy. We used all-trans retinoic acid (ATRA) to augment BCMA expression on MM cells and to increase the efficacy of BCMA-CAR T cells in pre-clinical models. We show that ATRA treatment leads to an increase in BCMA transcripts by quantitative reverse transcription polymerase chain reaction and an increase in BCMA protein expression by flow cytometry in MM cell lines and primary MM cells. Analyses with super-resolution microscopy confirmed increased BCMA protein expression and revealed an even distribution of non-clustered BCMA molecules on the MM cell membrane after ATRA treatment. The enhanced BCMA expression on MM cells after ATRA treatment led to enhanced cytolysis, cytokine secretion and proliferation of BCMA-CAR T cells in vitro, and increased efficacy of BCMA-CAR T-cell therapy in a murine xenograft model of MM in vivo (NSG/MM.1S). Combination treatment of MM cells with ATRA and the γ- secretase inhibitor crenigacestat further enhanced BCMA expression and the efficacy of BCMA-CAR T-cell therapy in vitro and in vivo. Taken together, the data show that ATRA treatment leads to enhanced BCMA expression on MM cells and consecutively, enhanced reactivity of BCMA-CAR T cells. The data support the clinical evaluation of ATRA in combination with BCMA-CAR T-cell therapy and potentially, other BCMA-directed immunotherapies.

SARS-CoV2 wild type and mutant specific humoral and T cell immunity is superior after vaccination than after natural infection

Objective

We investigated blood samples from fully SARS-CoV2-vaccinated subjects and from previously positive tested patients up to one year after infection with SARS-CoV2, and compared short- and long-term T cell and antibody responses, with a special focus on the recently emerged delta variant (B.1.617.2).

Methods and results

In 23 vaccinated subjects, we documented high anti-SARS-CoV2 spike protein receptor binding domain (RBD) antibody titers. Average virus neutralization by antibodies, assessed as inhibition of ACE2 binding to RBD, was 2.2-fold reduced for delta mutant vs. wild type (wt) RBD. The mean specific antibody titers were lower one year after natural infection than after vaccination; ACE2 binding to delta mutant vs. wt RBD was 1.65-fold reduced. In an additional group, omicron RBD binding was reduced compared to delta. Specific CD4+ T cell responses were measured after stimulation with peptides pools from wt, alpha, beta, gamma, or delta variant SARS-CoV2 spike proteins by flow cytometric intracellular cytokine staining. There was no significant difference in cytokine production of IFN-γ, TNF-α, or IL-2 between vaccinated subjects. T cell responses to wt or mutant SARS-CoV2 spike were significantly weaker after natural occurring infections compared to those in vaccinated individuals.

Conclusion

Antibody neutralisation of the delta mutant was reduced compared to wt, as assessed in a novel inhibition assay with a finger prick blood drop. Strong CD4 T cell responses were present against wt and mutant SARS-CoV2 variants, including the delta (B.1.617.2) strain, in fully vaccinated individuals, whereas they were partly weaker 1 year after natural infection. Hence, immune responses after vaccination are stronger compared to those after naturally occurring infection, pointing out the need of the vaccine to overcome the pandemic.

Nanoscale imaging of bacterial infections by sphingolipid expansion microscopy

Expansion microscopy (ExM) enables super-resolution imaging of proteins and nucleic acids on conventional microscopes. However, imaging of details of the organization of lipid bilayers by light microscopy remains challenging. We introduce an unnatural short-chain azide- and amino-modified sphingolipid ceramide, which upon incorporation into membranes can be labeled by click chemistry and linked into hydrogels, followed by 4× to 10× expansion. Confocal and structured illumination microscopy (SIM) enable imaging of sphingolipids and their interactions with proteins in the plasma membrane and membrane of intracellular organelles with a spatial resolution of 10–20 nm. As our functionalized sphingolipids accumulate efficiently in pathogens, we use sphingolipid ExM to investigate bacterial infections of human HeLa229 cells by Neisseria gonorrhoeae, Chlamydia trachomatis and Simkania negevensis with a resolution so far only provided by electron microscopy. In particular, sphingolipid ExM allows us to visualize the inner and outer membrane of intracellular bacteria and determine their distance to 27.6 ± 7.7 nm.

Imaging of lipid bilayers using light microscopy is challenging. Here the authors label cells using a short chain click-compatible ceramide to visualize mammalian and bacterial membranes with expansion microscopy.

Using Expansion Microscopy to Visualize and Characterize the Morphology of Mitochondrial Cristae

Mitochondria are double membrane bound organelles indispensable for biological processes such as apoptosis, cell signaling, and the production of many important metabolites, which includes ATP that is generated during the process known as oxidative phosphorylation (OXPHOS). The inner membrane contains folds called cristae, which increase the membrane surface and thus the amount of membrane-bound proteins necessary for the OXPHOS. These folds have been of great interest not only because of their importance for energy conversion, but also because changes in morphology have been linked to a broad range of diseases from cancer, diabetes, neurodegenerative diseases, to aging and infection. With a distance between opposing cristae membranes often below 100 nm, conventional fluorescence imaging cannot provide a resolution sufficient for resolving these structures. For this reason, various highly specialized super-resolution methods including dSTORM, PALM, STED, and SIM have been applied for cristae visualization. Expansion Microscopy (ExM) offers the possibility to perform super-resolution microscopy on conventional confocal microscopes by embedding the sample into a swellable hydrogel that is isotropically expanded by a factor of 4–4.5, improving the resolution to 60–70 nm on conventional confocal microscopes, which can be further increased to ∼ 30 nm laterally using SIM. Here, we demonstrate that the expression of the mitochondrial creatine kinase MtCK linked to marker protein GFP (MtCK-GFP), which localizes to the space between the outer and the inner mitochondrial membrane, can be used as a cristae marker. Applying ExM on mitochondria labeled with this construct enables visualization of morphological changes of cristae and localization studies of mitochondrial proteins relative to cristae without the need for specialized setups. For the first time we present the combination of specific mitochondrial intermembrane space labeling and ExM as a tool for studying internal structure of mitochondria.

Conformationally restrained pentamethine cyanines and use in reductive single molecule localization microscopy

Pentamethine cyanines are a class of far-red fluorophores that find extensive use in single-molecule localization microscopy (SMLM), as well as a broad range of other techniques. A drawback of this scaffold is its relatively low quantum yields, which is due to excited state deactivation via trans-to-cis chromophore isomerization. Here we describe a synthetic strategy to improve the photon output of these molecules. In the key synthetic transformation, a protected dialdehyde precursor undergoes a cascade reaction that forms a tetracyclic ring system. The resulting conformationally restrained analogs exhibit improved fluorescence quantum yield and extended fluorescence lifetimes. These properties, together with their ability to efficiently recover from hydride reduction, enable a uniquely simple form of single-molecule localization microscopy (SMLM).

Expansion Microscopy for Cell Biology Analysis in Fungi

Super-resolution microscopy has evolved as a powerful method for subdiffraction-resolution fluorescence imaging of cells and cellular organelles, but requires sophisticated and expensive installations. Expansion microscopy (ExM), which is based on the physical expansion of the cellular structure of interest, provides a cheap alternative to bypass the diffraction limit and enable super-resolution imaging on a conventional fluorescence microscope. While ExM has shown impressive results for the magnified visualization of proteins and RNAs in cells and tissues, it has not yet been applied in fungi, mainly due to their complex cell wall. Here we developed a method that enables reliable isotropic expansion of ascomycetes and basidiomycetes upon treatment with cell wall degrading enzymes. Confocal laser scanning microscopy (CLSM) and structured illumination microscopy (SIM) images of 4.5-fold expanded sporidia of Ustilago maydis expressing fluorescent fungal rhodopsins and hyphae of Fusarium oxysporum or Aspergillus fumigatus expressing either histone H1-mCherry together with Lifeact-sGFP or mRFP targeted to mitochondria, revealed details of subcellular structures with an estimated spatial resolution of around 30 nm. ExM is thus well suited for cell biology studies in fungi on conventional fluorescence microscopes.

Detection of Chlamydia Developmental Forms and Secreted Effectors by Expansion Microscopy

Expansion microscopy (ExM) is a novel tool to improve the resolution of fluorescence-based microscopy that has not yet been used to visualize intracellular pathogens. Here we show the expansion of the intracellular pathogen Chlamydia trachomatis, enabling to differentiate its two distinct forms, catabolic active reticulate bodies (RB) and infectious elementary bodies (EB), on a conventional confocal microscope. We show that ExM enables the possibility to precisely locate chlamydial effector proteins, such as CPAF or Cdu1, within and outside of the chlamydial inclusion. Thus, we claim that ExM offers the possibility to address a broad range of questions and may be useful for further research on various intracellular pathogens.

Sharpening emitter localization in front of a tuned mirror

Single-molecule localization microscopy (SMLM) aims for maximized precision and a high signal-to-noise ratio¹. Both features can be provided by placing the emitter in front of a metal-dielectric nanocoating that acts as a tuned mirror^2-4. Here, we demonstrate that a higher photon yield at a lower background on biocompatible metal-dielectric nanocoatings substantially improves SMLM performance and increases the localization precision by up to a factor of two. The resolution improvement relies solely on easy-to-fabricate nanocoatings on standard glass coverslips and is spectrally and spatially tunable by the layer design and wavelength, as experimentally demonstrated for dual-color SMLM in cells.

Analysis of the putative tumor suppressor gene cdkn2ab in pigment cells and melanoma of Xiphophorus and medaka

In humans, the CDKN2A locus encodes two transcripts, INK4A and ARF. Inactivation of either one by mutations or epigenetic changes is a frequent signature of malignant melanoma and one of the most relevant entry points for melanomagenesis. To analyze whether cdkn2ab, the fish ortholog of CDKN2A, has a similar function as its human counterpart, we studied its action in fish models for human melanoma. Overexpression of cdkn2ab in a Xiphophorus melanoma cell line led to decreased proliferation and induction of a senescence-like phenotype, indicating a melanoma-suppressive function analogous to mammals. Coexpression of Xiphophorus cdkn2ab in medaka transgenic for the mitfa:xmrk melanoma-inducing gene resulted in full suppression of melanoma development, whereas CRISPR/Cas9 knockout of cdkn2ab resulted in strongly enhanced tumor growth. In summary, this provides the first functional evidence that cdkn2ab acts as a potent tumor suppressor gene in fish melanoma models.

Integrated morphologic and molecular analysis of Trichomonas vaginalis, Mycoplasma hominis, and human papillomavirus using cytologic smear preparations

Pathogenic microbes may colonize the female genital tract via sexual transmission and cause health issues like inflammation or malignancy, summarized as sexually transmitted disease (STD). A major representative of such pathogens is Trichomonas vaginalis (T.v.), whose role in the etiology of cervical cancer remains elusive. Traditional morphologic screening of cervical smears is able to detect T.v., although its identification may be complicated by look-alikes such as degenerated granulocytes and basal cells. In addition, the parasite's endosymbiont Mycoplasma hominis (M.h.) cannot be detected in the Pap test. This investigation was aimed at designing a PCR-based method to detect specific pathogenic germs by using cervical cytology slides to overcome morphologic uncertainty and increase diagnostic accuracy. To test our molecular screening method on T.v., M.h., and HPV in archival smears, we elaborated a multiplex PCR approach based on microdissection. This assay was applied to a minute quantity of starting material which harbored or was suspected to harbor T.v.; the resulting isolated DNA was used for subsequent molecular analyses of T.v., M.h., and HPV. We clarified the diagnosis of genital T.v. infection in 88 and 1.8% of morphologically suspicious and T.v.-negative cases, respectively. We also revealed a tendency of M.h. co-infection in high-risk HPV cases. In conclusion, a microdissection-based approach to detect pathogenic microbes such as T.v., HPV, and M.h. is a molecular tool easy to implement and may help to better understand the interactivity of these germs with respect to pathogenesis.

Surface enhanced resonance Raman spectroscopy of iron Hangman complexes on electrodes during electrocatalytic oxygen reduction: advantages and problems of common drycast methods

Drycast methods have been used frequently in recent decades to adsorb a range of synthetic catalysts on electrodes. The uncoordinated multilayers that are formed via this immobilization method can however have a strong impact on the electrocatalytic reaction pathway as slow electron transfer and intermolecular interactions can alter the chemistry of the catalysts on the surface. To gain insight into the structure of Fe porphyrin Hangman catalysts during electrocatalytic oxygen reduction a combination of electrochemistry and surface enhanced resonance Raman spectroscopy (SERRS) was applied. The Hangman complexes were attached to the electrodes via different methods and the influence of the immobilisation technique on oxygen chemistry was studied. In multilayer systems, new intermediates could be identified via potential dependent SERRS that were not present in solution or in monolayer systems under catalytic conditions. A comparison of Raman spectra obtained either via Soret or Q-band excitation showed that the porphyrin symmetry is strongly distorted under reducing conditions, which was interpreted by the transient formation of dimer complexes during catalysis.

Cyanine Conformational Restraint in the Far-Red Range

Far-red cyanine fluorophores find extensive use in modern microscopy despite modest quantum yields. To improve the photon output of these molecules, we report a synthetic strategy that blocks the major deactivation pathway: excited-state trans-to-cis polyene rotation. In the key transformation, a protected dialdehyde precursor undergoes a cascade reaction to install the requisite tetracyclic ring system. The resulting molecules exhibit the characteristic features of conformational restraint, including improved fluorescence quantum yield and extended lifetime. Moreover, these compounds recover from hydride reduction with dramatically improved efficiency. These observations enable efficient single-molecule localization microscopy in oxygenated buffer without addition of thiols. Enabled by modern organic synthesis, these studies provide a new class of far-red dyes with promising spectroscopic and chemical properties.

Reversible light-dependent molecular switches on Ag/AgCl nanostructures

Nanostructured Ag/AgCl substrates were used to generate reversible and highly efficient light-dependent chemical switches based on adsorbed 4,4'-dimercaptoazobenzene (DMAB). DMAB was formed in situ via laser-induced dimerization either from 4-nitrothiophenol (4-NTP) or 4-aminothiophenol (4-ATP). The subsequent reaction pathways of DMAB, however, were quite different as monitored by surface enhanced Raman spectroscopy. In the 4-NTP/DMAB system, AgCl catalyses the reversal of the dimerization. Conversely, irradiation of adsorbed 4-ATP first generated cis-DMAB attached to the surface via two Ag-S bonds, followed by AgCl-catalysed cleavage of one Ag-S bond and cis → trans photoisomerisation of DMAB. In the dark, the trans-isomer thermally reverts to cis-DMAB. The here presented light-dark chemical switches, which work without changing other parameters (e.g., pH, anaerobic vs. aerobic), are based on the (photo)catalytic properties of the Ag/AgCl substrate and do not function on pure metal surfaces.

2nd coordination sphere controlled electron transfer of iron hangman complexes on electrodes probed by surface enhanced vibrational spectroscopy

Surface enhanced vibrational spectroscopy shows the correlation between electron transfer kinetics and protonation degree of Fe Hangman complexes on electrodes.

Iron hangman complexes exhibit improved catalytic properties regarding O₂ and H₂O₂ reduction, which are attributed to the presence of a proton donating group in defined vicinity of the catalytic metal centre. Surface enhanced resonance Raman (SERR) and IR (SEIRA) spectro-electrochemistry has been applied concomitantly for the first time to analyse such iron hangman porphyrin complexes attached to electrodes in aqueous solution. While the SERR spectra yield information about the redox state of the central iron, the SEIRA spectra show protonation and deprotonation events of the 2^nd coordination sphere. To investigate the influence of a proton active hanging group on the heterogeneous electron transfer between the iron porphyrin and the electrode, two hangman complexes with either an acid or ester functional group were compared. Using time resolved SERR spectroscopy the electron transfer rates of both complexes were determined. Complexes with an acid group showed a slow electron transfer rate at neutral pH that increased significantly at pH 4, while complexes with an ester group exhibited a much faster, but pH independent rate. SEIRA measurements were able to determine directly for the first time a pK_a value of 3.4 of a carboxylic hanging group in the immobilized state that shifted to 5.2 in D₂O buffer solution. The kinetic data showed an increase of the heterogeneous electron transfer rate with the protonation degree of the acid groups. From these results, we propose a PCET which is strongly modulated by the protonation state of the acid hanging group via hydrogen bond interactions.

Dioxins and dioxin-like PCBs in different fish from the river Elbe and its tributaries, Germany

In a long-term program polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) as well as dioxin-like polychlorinated biphenyls (DL-PCBs) were analyzed in the muscle tissue of eels (Anguilla anguilla), bream (Abramis brama), European chub (Leuciscus cephalus) and ide (Leuciscus idus) from the river Elbe and its tributaries Mulde and Saale. The variation of the PCDD/F and DL-PCB concentrations in all fish samples is very large, whereby the DL-PCBs predominate in comparison to the PCDD/Fs. In the eels, the concentrations (pg WHO-TEQ/g ww) for the PCDD/Fs lie in the range of 0.48-22 and for the DL-PCBs between 8.5 and 59. In the whitefish, the concentration range is 0.48-12 for the PCDD/Fs and 1.2-14 for the DL-PCBs. Statistical analysis using relative congener patterns for PCDD/Fs allow spatial correlations to be examined for sub-populations of eels and whitefish. The results are compared to the maximum levels laid down in the European Commission Regulation (EC) No. 466/2001 and the action levels of the European Commission Recommendation 2006/88/EC. Eels caught directly after the major flood in August 2002 as well as eels near Hamburg (years 1996 and 1998) show high concentration peaks. Compared to the eels whitefish is less contaminated with PCDD/Fs and DL-PCBs.

Contamination of the alluvial plain, feeding-stuffs and foodstuffs with polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (DL-PCBs) and mercury from the River Elbe in the light of the flood event in August 2002

Meadow soils, feeding-stuffs and foodstuffs from the alluvial plain of the river Elbe were analyzed in respect of PCDD/Fs, DL-PCBs and mercury with a view to assessing the consequences of the extreme flood of August 2002. The PCDD/F concentrations in the soils range from 3 to 2100 ng WHO-TEQ/kg dm, and for the DL-PCBs the range was 0.32 to 28 ng WHO-TEQ/kg dm. On the basis of established threshold values >40% of the areas are only fit for restricted usage. Mercury concentrations range from 0.11 to 17 mg/kg dm, whereby the action value of 2 mg/kg dm is exceeded in about 50% of the soil samples. A cumulative memory effect from past floods rather than a recent contamination from August 2002 is documented. Soils taken from behind broken dykes showed significantly lower concentrations. Grass, hay and grass silage originating from pasture land in Lower Saxony were taken before and immediately after the flooding. PCDD/Fs range from 0.29 to 16 ng WHO-TEQ/kg, the maximum permitted value of 0.75 ng WHO-TEQ/kg was exceeded in about 50% of the samples. Muscle-tissue from cattle, sheep, lamb and a roe deer as well as untreated milk from individual cows returned values ranging from 0.76 to 5.9 pg WHO-PCDD/F-TEQ/g fat, and 10% of the samples returned values higher than the permitted maximum of 3 pg WHO-PCDD/F-TEQ/g fat. The action value of 2 pg WHO-PCDD/F-TEQ/g fat was exceeded in 33% of the samples. No direct connection between these results and the effects of the flood could be established. A major input path for PCDD/Fs is the tributary Mulde, which discharges contaminated sediments from its catchment area into the Elbe.

The Elbe flood in August 2002--occurrence of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/F) and dioxin-like PCB in suspended particulate matter (SPM), sediment and fish

As a result of extreme precipitation in August 2002 major flooding occurred in the catchment area of the rivers Elbe, Vltava (Moldau) and Mulde. Pollutants from industrial sites and from municipal sewage treatment works (STW) entered the Elbe and led to a serious pollution problem in the river. PCDD/F concentrations (in pg WHO-TEQ/g dw) in SPM ranged from 7-150, in sediments from 3-140; the "safe sediment value" of 20 was exceeded in 46% of the samples. 24 eels showed a wide concentration variation for these contaminants. The WHO-PCDD/F+PCB-TEQ values lay in the range from 11-56 pg/g ww, whereby the WHO-PCB-TEQ values were several times higher than the WHO-PCDD/F-TEQ values. The maximum permitted value of 4 pg WHO-PCDD/F/g ww (EU Directive No. 2375/2001) was reached or exceeded in 54% of the individuals. A statistical analysis using data from SPM and sediment samples showed that in the Czech river section the flooding activated a contamination source in the vicinity of the Spolana works. The influence of the tributary Mulde could be clearly demonstrated. Only a major clean-up of the contaminated sites in Bitterfeld can lead to a mid to long term improvement in respect of PCDD/F and dioxin-like PCB input into the Elbe.

The complete sequence of the genome of Cocksfoot streak virus (CSV), a grass infecting Potyvirus

The complete nucleotide sequence of Cocksfoot streak virus (CSV) has been determined. The viral genome comprises 9663 nucleotides, excluding a 3'-terminal poly(A) sequence. The genome of CSV has a 133 nt 5'-non coding and a 260 nt 3'-non coding region. The RNA of CSV encodes a single polyprotein of 3089 amino acid residues and has a deduced genome organization typical for a member of the family Potyviridae. CSV is transmissible by aphids and has a narrow host range in the Gramineae. It was compared to two potyviruses having monocotyledonous hosts (monocot potyviruses) and several potyviruses infecting dicotyledonous plants (dicot potyviruses). CSV is most closely related to other monocot potyviruses like Maize dwarf mosaic virus (MDMV) and Johnson grass mosaic virus (JGMV), but also closely related to the dicot potyviruses. On the other hand, CSV is less related to monocot viruses from the other genera (Rymovirus, Tritimovirus) within the Potyviridae. Specific motifs, described for potyviral polyproteins, are also present in the polyprotein of CSV. Only two motifs in the HC-Pro--motif involved in long distance movement and motif for HC-Pro self-interaction--were different in comparison to most of the dicot potyviruses.

Molecular and serological relationships of Spartina mottle virus (SpMV) strains from Spartina spec. and from Cynodon dactylon to other members of the Potyviridae

Spartina mottle virus (SpMV) was first reported 1980 and classified by physical and biological properties as a tentative member of the genus Rymovirus in the Potyviridae. This genus was recently separated into two genera: Rymovirus and Tritimovirus. Now the sequence of the 3'-terminal part of the genome of SpMV was determined. Additionally a virus isolate originating from Cynodon dactylon in Italy was cloned and sequenced. This Assisi-isolate shared 87.5% amino acid sequence identity with SpMV. The high degree of identity and their close serological relationship indicate that SpMV and Assisi-isolate have to be regarded as different strains of one virus. The Assisi-isolate should be designated as SpMV-AV. Comparing the C-terminal part of the ORF of several Potyviridae the sequences of SpMV strains were more similar to those of the genera Rymovirus and Potyvirus than to the genera Tritimovirus, Macluravirus, Bymovirus and Ipomovirus. The comparisons revealed identities of less than 32% for the CP and 37% for the 3'-NIb/CP region, indicating that SpMV can not be classified to any of the established genera. The results of serological tests support a separate position of SpMV in the Potyviridae. We propose to introduce the name Sparmovirus for the new genus.

Regulation of neuronal cell death and differentiation by NGF and IAP family members

Nerve growth factor (NGF) and other neurotrophins were identified because of their trophic role for distinct populations of neurons in the peripheral nervous system. We know that neuronal cell death is regulated by a genetically encoded programme, called apoptosis, that is conserved from worms to humans. Dysregulation of this programme is thought to contribute to neurodegenerative diseases which are characterized by the loss of neurons. This article will review recent findings about the motoneuron disease spinal muscular atrophy (SMA). Two closely linked candidate genes for SMA, the SMN (survival motor neuron) gene and the NAIP (neuronal apoptosis inhibitory protein) gene have been reported. The SMN protein forms a complex with several other proteins and this complex containing SMN plays a critical role in the assembly of spliceosomes and in pre-mRNA splicing. NAIP, c-IAP1 (inhibitor of apoptosis-1), c-IAP2, X-IAP and survivin comprise the mammalian inhibitor of apoptosis family. Its members can protect mammalian cells from apoptosis induced by a variety of stimuli. Some of the IAP molecules have been shown to interact both with cell signalling molecules and with specific caspases but details concerning their cellular role are only incompletely characterized.

The neuronal apoptosis inhibitory protein suppresses neuronal differentiation and apoptosis in PC12 cells

The human neuronal apoptosis inhibitory protein (NAIP) gene has been discovered as a candidate gene for spinal muscular atrophy, a genetic disorder characterized by motor neuron loss in the spinal cord. The telomeric NAIP gene on human chromosome 5 is deleted together with survival motor neurons (SMN) in many cases of the most severe forms of the disorder. NAIP, c-IAP1 (inhibitor of apoptosis-1), c-IAP2, X-IAP, survivin and Apollon comprise the mammalian inhibitors of the apoptosis family and contain an N-terminal domain with 1-3 imperfect repeats of an approximately 65 amino acids domain named the baculovirus IAP repeat (BIR) motif. We identified six NAIP genes in the mouse genome which were found to be expressed in a broad range of tissues. Furthermore, we have investigated the effects of NAIP in the rat pheochromocytoma PC12 cell line. These cells differentiate in the presence of nerve growth factor (NGF) into cells that resemble sympathetic neurons. We observed that NAIP overexpression impaired NGF-induced neurite outgrowth. The BIR motifs of NAIP (residues 1-345) were not required for this effect. However, the BIR domains of NAIP were essential to prevent apoptosis in PC12 cells after NGF deprivation or TNF-alpha receptor stimulation. Expression of full-length but not BIR-deleted-NAIP protects against cell death. This correlates with reduced activity of the cell death effector protease, caspase-3, in lysates of NAIP-PC12 cells, as measured by cleavage of the fluorogenic tetrapeptide substrate Asp-Glu-Val-Asp. Thus, unregulation of cellular differentiation and/or caspase suppression may contribute to motoneuron dysfunction and cell death in spinal muscular atrophy where NAIP is mutated.

First atropo-divergent total synthesis of the antimalarial korupensamines A and B by the "lactone method"

The stereoselective total synthesis of the antimalarial korupensamines A (1a) and B (1b) by application of the "lactone method" is described. Key steps of this first atropo-selective access to 5,8'-coupled naphthylisoquinoline alkaloids were the regioselective intramolecular coupling of ester 8 to give the configurationally labile lactone-bridged biaryl 9 and its atropisomer-selective cleavage with a variety of chiral and achiral H-nucleophiles, yielding the configurationally stable P-diol 10a or, optionally, the M-product 10b. From the axially chiral phenylisoquinolines thus obtained atropo-diastereodivergently, the authentic natural naphthylisoquinolines with the respective axial configurations, korupensamines A (1a) and B (1b), were obtained by completion of the second naphthalene ring, starting from the previous "bridgehead" C1 unit.

The early expression of VAChT and VIP in mouse sympathetic ganglia is not induced by cytokines acting through LIFRbeta or CNTFRalpha

Sympathetic ganglia consist of noradrenergic and cholinergic neurons. The cholinergic marker protein vesicular acetylcholine transporter (VAChT) and the neuropeptide vasoactive intestinal peptide (VIP), co-expressed in mature cholinergic sympathetic neurons, are first detectable during embryonic development of rat sympathetic ganglia. However, the subpopulation of cholinergic sympathetic neurons which innervates sweat glands in mammalian footpads starts to express VAChT and VIP during the first postnatal weeks, under the influence of sweat gland-derived signals. In vitro evidence suggests that the sweat gland-derived cholinergic differentiation factor belongs to a group of neuropoietic cytokines, including LIF, CNTF and CT-1, that act through a LIFRbeta-containing cytokine receptor. To investigate whether the embryonic expression of cholinergic properties is elicited by a related cytokine, the expression of VAChT and VIP was analyzed in stellate ganglia of mice deficient for the cytokine receptor subunits LIFRbeta or CNTFRalpha. The density of VAChT- and VIP-immunoreactive cells in stellate ganglia of new-born animals was not different in LIFRbeta(-/-) and CNTFRalpha(-/-) ganglia as compared to ganglia from wild-type mice. These results demonstrate that the early, embryonic expression of VAChT and VIP is not induced by cytokines acting through LIFRbeta- or CNTFRalpha-containing receptors.

Ontogeny of catecholamine and adenosine receptor-mediated cAMP signaling of embryonic red blood cells: role of cGMP-inhibited phosphodiesterase 3 and hemoglobin

We have previously shown that the cAMP signaling pathway controls major aspects of embryonic red blood cell (RBC) function in avian embryos (Glombitza et al, Am J Physiol 271:R973, 1996; and Dragon et al, Am J Physiol 271:R982, 1996) that are important for adaptation of the RBC gas transport properties to the progressive hypercapnia and hypoxia of later stages of avian embryonic development. Data about the ontogeny of receptor-mediated cAMP signaling are lacking. We have analyzed the response of primitive and definitive chick embryo RBC harvested from day 3 to 18 of development towards forskolin, beta-adrenergic, and A2 receptor agonists. The results show a strong response of immature definitive and primitive RBC to adenosine A2 and beta-adrenergic receptor agonists, which is drastically reduced in the last stage of development, coincident with the appearance of mature, transcriptionally inactive RBC. Modulation of cGMP-inhibited phosphodiesterase 3 (PDE3) has a controlling influence on cAMP accumulation in definitive RBC. Under physiological conditions, PDE3 is inhibited due to activation of soluble guanylyl cyclase (sGC). Inhibition of sGC with the specific inhibitor ODQ decreases receptor-mediated stimulation of cAMP production; this effect is reversed by the PDE3 inhibitor milrinone. sGC is acitivated by nitric oxide (NO), but we found no evidence for production of NO by erythrocyte NO-synthase. However, embryonic hemoglobin releases NO in an oxygen-linked manner that may activate guanylyl cyclase.

Functional analysis of 150 deletion mutants in Saccharomyces cerevisiae by a systematic approach

In a systematic approach to the study of Saccharomyces cerevisiae genes of unknown function, 150 deletion mutants were constructed (1 double, 149 single mutants) and phenotypically analysed. Twenty percent of all genes examined were essential. The viable deletion mutants were subjected to 20 different test systems, ranging from high throughput to highly specific test systems. Phenotypes were obtained for two-thirds of the mutants tested. During the course of this investigation, mutants for 26 of the genes were described by others. For 18 of these the reported data were in accordance with our results. Surprisingly, for seven genes, additional, unexpected phenotypes were found in our tests. This suggests that the type of analysis presented here provides a more complete description of gene function.

A potential role of the cytoskeleton of Saccharomyces cerevisiae in a functional organization of glycolytic enzymes

Numerous individual enzymes participate in a given synthetic or degradative pathway in which the product of one reaction becomes the substrate for the subsequent enzyme. This raises the question of whether the product of one 'soluble' enzyme diffuses freely through the available cell volume, where it accidentally collides with the subsequent 'soluble' enzyme. Alternatively, enzymes acting in a given pathway may be organized in ordered structures, metabolons. Certain glycolytic enzymes have been shown to co-localize with the cytoskeleton in mammalian cells. We deleted genes coding for proteins associated with the cytoskeleton of Saccharomyces cerevisiae: TPM1 coding for tropomyosin, SAC6 for fimbrin and CIN1 for a microtubule-associated protein. Single deletions or deletions of two such genes had no effect on the specific activities of glycolytic enzymes, or on the rates of glucose consumption and ethanol production. However, the concentrations of glycolytic metabolites during a switch from a gluconeogenic mode of metabolism, growth on an ethanol medium, to glycolysis after glucose addition showed transient deviations from the normal change in metabolite concentrations, as observed in wild type cells. However, all metabolites in mutant strains reached wild-type levels within 2-4 h after the shift. Only ATP levels remained low in all but the tmp1-Delta-sac6-Delta double mutant strains. These observations can be interpreted to mean that metabolic reorganization from a gluconeogenic to a glycolytic metabolism is facilitated by an intact cytoskeleton in yeast.

The anti-apoptotic protein ITA is essential for NGF-mediated survival of embryonic chick neurons

The avian ITA is homologous to the baculoviral and mammalian inhibitor of apoptosis (IAP) proteins, which can prevent apoptosis by inhibition of specific caspases. We investigated the role of ITA in embryonic chick sympathetic and dorsal root ganglionic neurons, which depend on nerve growth factor (NGF) for their survival. Within 6 hours, NGF upregulated ITA protein production more than 25-fold in sensory and sympathetic neurons. Overexpression of ITA in primary neurons supported survival of these cells in the absence of NGF, and ita antisense constructs inhibited NGF-mediated survival. Thus the induction of ITA expression seems to be an essential signaling event for survival of sympathetic and dorsal root ganglionic sensory neurons in response to NGF.

Deletion of the carbonic anhydrase-like gene NCE103 of the yeast Saccharomyces cerevisiae causes an oxygen-sensitive growth defect

The yeast protein Nce103p encoded by the gene NCE103 (YNL036w) was described by Cleves et al. (1996) as a substrate of the non-classical export pathway which acts independently of the classical pathway through the ER and the Golgi compartments. However, the predicted amino acid sequence of Nce103p shows high levels of identities to carbonic anhydrases of pro- and eukaryotes. A nce103-Delta deletion strain did not grow on a rich peptone-yeast extract-glucose medium under normal aerobic conditions at pH values of 3.0-8.0, but grew like wild-type in an oxygen-free nitrogen or oxygen-reduced atmosphere over this pH range, and was more sensitive to H(2)O(2) than wild-type. No carbonic anhydrase activity could be detected in crude extracts prepared from wild-type, nce103-Delta mutants or in strains transformed with a multicopy plasmid carrying the NCE103 gene. Expression of the Medicago sativa carbonic anhydrase gene (Coba de la Peña et al., 1997), in a yeast expression cassette on a multicopy plasmid, complemented the growth defects caused by the nce103-Delta deletion and carbonic anhydrase activity could be readily detected in the crude extract. The ability of the nce103-Delta deletion strain to grow like wild-type under anaerobic conditions suggests that the protein encoded by NCE103 is required for protection against certain products of an oxidative metabolism and can be replaced in this function by the Medicago sativa carbonic anhydrase. A NCE103 promoter-LacZ fusion in a wild-type background showed that NCE103 is poorly transcribed under aerobic conditions and at an undetectable level under anaerobic conditions.

Dioxin (PCDD/F) in the river Elbe--investigations of their origin by multivariate statistical methods

With several multivariate statistical methods a classification of dioxin data has been tried. As a main result one significant source of dioxin in the river Elbe, in the harbour of Hamburg as well as in soils of the flooding areas of the river Elbe could be identified: the dioxin contaminated region Bitterfeld. Our statistical results indicate that the dioxin contamination in the Bitterfeld region was caused partly by metallurgy processes and not only by chemical production.

Adenosine 3':5'-cyclic monophosphate (cAMP)-inducible pyrimidine 5'-nucleotidase and pyrimidine nucleotide metabolism of chick embryonic erythrocytes

Terminally differentiating erythrocytes degrade most of their RNA with subsequent release of mononucleotides. Pyrimidine mononucleotides are preferentially cleaved by an erythrocyte-specific pyrimidine 5'-nucleotidase; deficiency of this enzyme causes hemolytic anemia in humans. Details of the regulation of its activity during erythroid differentiation are unknown. The present study arose from the observation that the immature red blood cells (RBCs) of mid-term chick embryos contain high concentrations of uridine 5'-triphosphate (UTP) (5 to 6 mmol/L), which decline rapidly from days 13 to 14 onward. We analyzed two key enzymes of RBC pyrimidine nucleotide metabolism: pyrimidine nucleoside phosphorylase (PNP) and pyrimidine 5'-nucleotidase (P-5'-N), to evaluate if changes of enzyme activity during embryonic development are correlated with changes of RBC UTP. Secondly, we tested if these enzymes are under hormonal control. The results show that embryonic RBCs contain only minimal activity of PNP. In contrast, P-5'-N increases from day 13 on, suggesting that the enzyme is a limiting factor in UTP degradation. Activation of beta-adrenergic and A2A-adenosine receptors causes transcription-dependent de novo synthesis of P-5'-N. Because beta-adrenergic and adenosine receptors are also found on adult erythroid cells, P-5'-N might be an enzyme of differentiating RBCs whose expression is in part controlled by adenosine 3':5'-cyclic monophosphate (cAMP).

Organic trace compounds in the water of the River Elbe near Hamburg. Part II

Part II of the quantitative determination of altogether 145 distinct organic compounds is presented (88 organic compounds). Elevated amounts of some pesticides concerning triazines and especially dimethoate were recorded as well as of O,O,O-trimethylthiophosphate and O,O,S-trimethyldithiophos-phate, which are related to the chemistry of dimethoate. A comparison of the results of PCB-quantification in unfiltered water samples with the results for solid phase material (SPM-phase) in river water is presented. The occurrence of organic trace compounds in the River Elbe is discussed in comparison to corresponding investigations of the River Rhine.

Organic trace compounds in the water of the River Elbe near Hamburg. Part I

Water samples of the River Elbe near Hamburg were analyzed for 145 organic chemical compounds. In part I results of the investigations concerning the following groups of compounds are presented (57 individual compounds): volatile chlorinated hydrocarbons, chloroalkylethers (haloethers), chlorobenzenes, nitrobenzenes, chloronitrobenzenes, and chloroanilines. Highest concentrations were found for the chlorinated bispropylethers and 1,7-dichloro-3,5-dioxaheptane (haloethers). Other important compounds were nitrobenzene, nitrotoluenes, and chloronitrobenzenes. The results were assessed on the basis of German surface water quality criteria.

Endogenous ciliary neurotrophic factor is a lesion factor for axotomized motoneurons in adult mice

Ciliary neurotrophic factor (CNTF) is an abundant cytosolic molecule in myelinating Schwann cells of adult rodents. In newborn animals in which CNTF is not yet expressed, exogenous CNTF that is locally administered very effectively protects motoneurons from degeneration by axotomy. To evaluate whether endogenous CNTF, released after nerve injury from the cytosol of Schwann cells, supports motoneuron survival, we transected the facial nerve in 4-week-old pmn mice. In this mouse mutant a rapidly progressing degenerative disease of motoneurons starts by the third postnatal week at the hindlimbs and progresses to the anterior parts of the body, leading to death by the seventh to eighth week. Apoptotic death of motoneurons can be observed during this period, as revealed by TUNEL staining. In 6-week-old unlesioned pmn mice approximately 40% of facial motoneurons have degenerated. Facial nerve lesion dramatically increased the number of surviving motoneurons in pmn mice. This protective effect was absent in pmn mice lacking endogenous CNTF. Quantitative analysis of leukemia inhibitory factor (LIF) mRNA expression revealed that the dramatic upregulation seen in wild-type mice after peripheral nerve lesion did not occur in pmn mice. Therefore, endogenous LIF cannot compensate for the lack of CNTF in pmn crossbred with CNTF knock-out mice. Thus, endogenous CNTF released from lesioned Schwann cells supports the survival of axotomized motoneurons under conditions in which motoneurons are in the process of rapid degeneration.

Inactivation of the survival motor neuron gene, a candidate gene for human spinal muscular atrophy, leads to massive cell death in early mouse embryos

Proximal spinal muscular atrophy is an autosomal recessive human disease of spinal motor neurons leading to muscular weakness with onset predominantly in infancy and childhood. With an estimated heterozygote frequency of 1/40 it is the most common monogenic disorder lethal to infants; milder forms represent the second most common pediatric neuromuscular disorder. Two candidate genes-survival motor neuron (SMN) and neuronal apoptosis inhibitory protein have been identified on chromosome 5q13 by positional cloning. However, the functional impact of these genes and the mechanism leading to a degeneration of motor neurons remain to be defined. To analyze the role of the SMN gene product in vivo we generated SMN-deficient mice. In contrast to the human genome, which contains two copies, the mouse genome contains only one SMN gene. Mice with homozygous SMN disruption display massive cell death during early embryonic development, indicating that the SMN gene product is necessary for cellular survival and function.

Adenoviral gene transfer of ciliary neurotrophic factor and brain-derived neurotrophic factor leads to long-term survival of axotomized motor neurons

The neurotrophic factors ciliary neurotrophic factor and brain-derived neurotrophic factor can prevent motor neuron cell death during development and after nerve lesion in neonatal rodents. However, local and systemic application of these factors to newborn rats with damaged motor nerves rescues motor neurons only transiently during the first two weeks after axotomy. In order to test the effect of continuous delivery of these factors, the effect of localized injection of CNTF- or BDNF-transducing recombinant adenoviruses into the lesioned nerves was investigated. Under such conditions, survival of axotomized motor neurons is maintained for at least 5 weeks. This way of delivery corresponds to the physiological situation in adult rodents, under which endogenous CNTF is present in the cytosol of Schwann cells and BDNF expression is upregulated after nerve lesion, making these factors available to the damaged motor neurons. Recent results show that overexpression of muscle-derived neurotrophin-3 prevents degeneration of axons and motor endplates, but has only little effect on the number of motor neuron cell bodies in a murine animal model of motor neuron disease. Therefore, techniques suitable for tonic exposure to both nerve- and muscle-derived neurotrophic factors may have implications for the design of future therapeutic strategies against human motor neuron disease.

Recombinant fish neurotrophin-6 is a heparin-binding glycoprotein: implications for a role in axonal guidance

Neurotrophin-6 (NT-6) was identified in the teleost fish Xiphophorus as a new member of the neurotrophin gene family. NT-6 binds specifically the glycosaminoglycan heparin. In this study NT-6 was expressed in a stably transfected mammalian cell line, and in insect cells via a recombinant baculovirus. It was purified to homogeneity and characterized by MS and N-terminal sequencing. NT-6 from both expression systems was proteolytically processed at one of two protease cleavage motifs and was found to be glycosylated. It supported the survival of embryonic chick sensory neurons; half-maximal survival was observed at 100 ng/ml. Furthermore, NT-6 elicited neurite outgrowth in explanted embryonic dorsal root ganglia. Addition of heparin into the medium did not potentiate the activity of NT-6 in survival assays. However, when a sensory ganglion explant was cultured in a collagen gel matrix assay adjacent to a heparin bead coated with NT-6, neurite outgrowth directed towards the bead was observed. This indicated that NT-6 was slowly released from the heparin bead generating a concentration gradient of NT-6 instrumental for axonal guidance in vitro. Thus the interaction of NT-6 with heparin might not be required for the activation of the cellular receptor for NT-6 on responsive cells but rather may serve to control, in vivo, the distribution of NT-6.

Norepinephrine-mediated hypoxic stimulation of embryonic red cell carbonic anhydrase and 2,3-DPG synthesis

Hypoxia is the stimulus for activation of red cell carbonic anhydrase II (CAII) and 2,3-diphosphoglycerate (2,3-DPG) synthesis of chick red blood cells during late embryonic development. We have tested whether plasma catecholamines are involved as hormonal mediators, because hypoxia is a well-known stimulus for catecholamine release in mammalian fetuses. Plasma catecholamines were measured in 8- to 16-day-old chick embryos. Plasma levels of norepinephrine (NE) were initially low, but its concentration increased rapidly from 2.7 nM (day 12) to 13.4 nM at day 13 and 25.5 nM at day 16. Epinephrine (E) was not detectable before day 13. Short-term hypoxic exposure of day 11 embryos (1-h incubation at 13.5% O2) increased plasma NE concentration fivefold compared with the controls but had no effect on E. During 15-h in vitro incubation of red blood cells from day 11, addition of 1 microM NE to the incubation medium increased the red cell 2,3-DPG concentration nearly threefold and CAII activity sixfold compared with the control. The CAII activity and 2,3-DPG concentration were also increased when cells were incubated with plasma from late chick embryos. The activation was induced by beta-adrenergic stimulation of adenylyl cyclase. Atenolol and propranolol blocked the effects of NE and embryonic chick plasma. Analysis of de novo protein synthesis ([35S]methionine incorporation) demonstrated that catecholamines stimulate the synthesis of several proteins besides CAII. The results indicate that developmental changes of plasma NE concentration are instrumental in the adenosine 3',5'-cyclic monophosphate-dependent activation of CAII and 2,3-DPG synthesis of red blood cells from late chick embryos.

Cryptic physiological trophic support of motoneurons by LIF revealed by double gene targeting of CNTF and LIF

BACKGROUND

The survival and differentiation of motoneurons during embryonic development, and the maintenance of their function in the postnatal phase, are regulated by a great variety of neurotrophic molecules which mediate their effects through different receptor systems. The multifactorial support of motoneurons represents a system of high security, because the inactivation of individual ligands has either no detectable, or relatively small, atrophic or degenerative effect on motoneurons.

RESULTS

Leukaemia inhibitory factor (LIF) has been demonstrated to support motoneuron survival in vitro and in vivo under different experimental conditions. However, when LIF was inactivated by gene targeting, there were no apparent changes in the number and structure of motoneurons and no impairment of their function. The slowly appearing, relatively mild degenerating effects in motoneurons that resulted from ciliary neurotrophic factor (CNTF) gene targeting were substantially potentiated by simultaneous inactivation of the LIF gene, however. Thus, in mice deficient in LIF and CNTF, the degenerative changes in motoneurons were more extensive and appeared earlier. These changes were also functionally reflected by a marked reduction in grip strength.

CONCLUSIONS

Degenerative disorders of the nervous system, in particular those of motoneurons, may be based on multifactorial inherited and/or acquired defects which individually do not result in degenerative disorders, but which become apparent when additional (cryptic) inherited disturbances or sub-threshold concentrations of noxious factors come into play. Accordingly, the inherited inactivation of the CNTF gene in a high proportion of the Japanese population may represent a predisposing factor for degenerative disorders of motoneurons.

[Initial experiences with dilatation of dialysis shunts with color-coded duplex ultrasonography monitoring]

PURPOSE

Aim of the study was to evaluate the technical aspects of colour coded duplex sonography guided interventions of peripheral vessels.

METHODS

During 15 months 39 stenoses of shunt veins in 24 patients were dilated guided by colour coded duplex sonography.

RESULTS

38 stenoses were dilated without complications. The blood flow volume was increased from 361.9 +/- 83.5 to 718.9 +/- 189.2 ml/min. In one case it was not possible to dilate the stenosis because of a vasospasm.

CONCLUSION

PTA guided by colour coded duplex sonography is an alternative to DSA guided interventions of superficial vessels without x-ray exposure or contrast agent application.

The complete nucleotide sequence and genome organization of the mite-transmitted brome streak mosaic rymovirus in comparison with those of potyviruses

A virus isolate, designated as 11-Cal, originating from southern France has been identified as an isolate of the mite-transmitted brome streak mosaic rymovirus (BrSMV) by serological and morphological properties. BrSMV is a member of the genus Rymovirus of the family Potyviridae. The complete nucleotide sequence of the RNA genome of BrSMV has been determined. The assembled RNA is 9672 nucleotides in length, excluding a 3'-terminal poly(A)sequence. The RNA contains one open reading frame (ORF) of 9282 nucleotides coding for a polyprotein of 3093 amino acids. A comparison with typical potyvirus showed that BrSMV has a similar genome organization. The predicted cleavage sites of the polyprotein of BrSMV are similar to those of potyviruses. Nevertheless, unusual dipeptides are proposed in two cases. Based on the proposed location of the cleavage sites nine mature proteins are predicted. Specific motifs, described for potyviral polyproteins, are almost all present in the polyprotein of BrSMV, too. However, only an incomplete zinc-finger motif is present in the potential helper component and the motif for aphid transmission in the coat protein is not found. Several alignments of amino acid sequences showed less similarity between BrSMV and potyviruses than between different potyviruses.

Parathyroid hormone secretion and serum calcium concentration--a deterministic view of its regulation

In seven normal men we investigated the basal secretion of PTH by blood sampling in 30 sec intervals for estimation of intact PTH and at 2-min intervals for measurement of ionized calcium. In 4 of these subjects we also investigated the PTH-secretion under conditions of intermittent hypercalcemia and hypocalcemia. Our measurements demonstrate the existence of three time scales in the secretion of PTH, viz. short-term pulses (faster than 2 min), an intermediate pattern of adjusting PTH levels to changed Ca2+ averages, and finally a long-term coupling between PTH and Ca2+ averages after 20 min. Ionized calcium controls the long-term regulation and intermediate adaptation mechanisms, but the short-term fluctuations seem to be due to spontaneous secretion.