Is an intact hippocampus necessary for answering 3 × 3? - Evidence from Alzheimer's disease.

Recent evidence has suggested that the hippocampus supports learning and retrieval of arithmetic facts during childhood and adolescence. Whether the hippocampus is also involved in retrieving overlearned arithmetic facts (such as 3 × 5 = 15) during adult age is open for investigation. In this study, we assessed whether patients with hippocampal atrophy due to Alzheimer's disease (AD) are still able to retrieve overlearned arithmetic facts from memory. Sixteen patients (n = 13 with AD, n = 3 with Mild Cognitive Impairment - MCI) were evaluated using standard radiological, neurological, and neuropsychological test procedures. We adopted a multiple single-case analysis in order to acknowledge possible dissociations between hippocampal degeneration and intact arithmetic fact retrieval. All patients performed a neuropsychological screening battery assessing episodic memory as well as arithmetic processing, and underwent a 3-Tesla MRI procedure. A morphometric analysis comprising estimation of both cortical thickness and hippocampal volume, which also included a subfield analysis, was conducted. All patients had marked hippocampal atrophy (bilateral n = 15, unilateral n = 1) in comparison to healthy matched controls and showed deficits in episodic memory (delayed recall). However, 13 out of 16 patients performed in the average range of standardised norms during retrieval of overlearned arithmetic facts (i.e. multiplication tables). Our results suggest that intact retrieval of consolidated arithmetic facts from memory does not depend on the integrity of the hippocampus. This is in line with the view that the hippocampus plays a dynamic and time-limited role in arithmetic processing. While the hippocampus seems to be necessary for learning and consolidating new arithmetic facts in memory, it might not be critically involved in retrieving arithmetic facts when these are well consolidated in memory.

Sulfolobus acidocaldarius Transports Pentoses via a Carbohydrate Uptake Transporter 2 (CUT2)-Type ABC Transporter and Metabolizes Them through the Aldolase-Independent Weimberg Pathway.

Sulfolobus spp. possess a great metabolic versatility and grow heterotrophically on various carbon sources, such as different sugars and peptides. Known sugar transporters in Archaea predominantly belong to ABC transport systems. Although several ABC transporters for sugar uptake have been characterized in the crenarchaeon Sulfolobus solfataricus, only one homologue of these transporters, the maltose/maltooligomer transporter, could be identified in the closely related Sulfolobus acidocaldarius Comparison of the transcriptome of S. acidocaldarius MW001 grown on peptides alone and peptides in the presence of d-xylose allowed for the identification of the ABC transporter for d-xylose and l-arabinose transport and the gaining of deeper insights into pentose catabolism under the respective growth conditions. The d-xylose/l-arabinose substrate binding protein (SBP) (Saci_2122) of the ABC transporter is unique in Archaea and shares more similarity to bacterial SBPs of the carbohydrate uptake transporter-2 (CUT2) family than to any characterized archaeal one. The identified pentose transporter is the first CUT2 family ABC transporter analyzed in the domain of Archaea Single-gene deletion mutants of the ABC transporter subunits exemplified the importance of the transport system for d-xylose and l-arabinose uptake. Next to the transporter operon, enzymes of the aldolase-independent pentose catabolism branch were found to be upregulated in N-Z-Amine and d-xylose medium. The α-ketoglutarate semialdehyde dehydrogenase (KGSADH; Saci_1938) seemed not to be essential for growth on pentoses. However, the deletion mutant of the 2-keto-3-deoxyarabinoate/xylonate dehydratase (KDXD [also known as KDAD]; Saci_1939) was no longer able to catabolize d-xylose or l-arabinose, suggesting the absence of the aldolase-dependent branch in S. acidocaldariusIMPORTANCE Thermoacidophilic microorganisms are emerging model organisms for biotechnological applications, as their optimal growth conditions resemble conditions used in certain biotechnologies such as industrial plant waste degradation. Because of its high genome stability, Sulfolobus acidocaldarius is especially suited as a platform organism for such applications. For use in (ligno)cellulose degradation, it was important to understand pentose uptake and metabolism in S. acidocaldarius This study revealed that only the aldolase-independent Weimberg pathway is required for growth of S. acidocaldarius MW001 on d-xylose and l-arabinose. Moreover, S. acidocaldarius employs a CUT2 ABC transporter for pentose uptake, which is more similar to bacterial than to archaeal ABC transporters. The identification of pentose-inducible promoters will expedite the metabolic engineering of S. acidocaldarius for its development into a platform organism for (ligno)cellulose degradation.

Integration of innate into adaptive immune responses in ZAP-70-positive chronic lymphocytic leukemia.

The crucial dependence of chronic lymphocytic leukemia (CLL) cells on signals derived from the B cell receptor (BCR) has encouraged the development of new inhibitors, which interfere with BCR signaling and demonstrate clinical benefits in nearly all patients. In addition, signaling through Toll-like receptor (TLR) 9 of the innate immune system has been shown to further contribute to the activation of CLL cells. However, responses to TLR9 engagement are not uniform, but diametrically opposed with cell death in some patients and cell proliferation in others. We now provide evidence that heterogeneous responses to TLR agonists are related to differences in the ability of CLL cells to activate the BCR-associated kinase Syk. Notably, expression of ZAP-70 appears to be of crucial importance for TLR9-mediated activation of Syk. We show that the activation of Syk provides an antiapoptotic signal, which is independent of Mcl-1, Bcl-2, and Bcl-XL, but related to the degradation of the proapoptotic Bim. Mechanistically, TLR9-mediated antiapoptotic signals in ZAP-70-positive CLL trigger secretion of immunoglobulin M, which then serves as (auto-) antigen for a prosurvival BCR signal. Thus, our data show that single activation of the innate immune receptor TLR9 is sufficient to fully engage BCR signaling in ZAP-70-positive CLL, protecting malignant cells from apoptosis. We conclude that the integration of TLR signaling into an adaptive immune response can further promote survival of CLL cells and may contribute to the unfavorable prognosis of ZAP-70-positive CLL.

Ten years of follow-up in a large family with familial hemiplegic migraine type 1: Clinical course and implications for treatment.

Background Familial hemiplegic migraine (FHM) is a rare, genetic form of migraine with aura. The severity of the aura imposes an effective prophylaxis that is currently based on standard anti-migraine drugs. To this concern, only short-term reports are currently available. Methods Eight patients from a multigenerational FHM type 1 family harbouring a T666M mutation in the CACNA1A gene were referred to our ataxia outpatient clinic. Medical history, general and neurological examination as well as therapeutic approaches were recorded regularly on a routine basis for an average period of 13 years (range 9-15 years). Brain imaging studies and EEG data were also collected. Results Our long-term follow-up revealed that ictal manifestations, which usually improve after the adolescence, may reoccur later in the adulthood. Permanent neurological signs as assessed by means of clinical evaluation as well as follow-up MRIs, EEGs and neuropsychological testing remained stable. Interval therapy with non-selective calcium antagonists reduced the burden of migraine attacks and was well tolerated in the long term.

Autonomic function testing in spinocerebellar ataxia type 2.

PURPOSE: To assess whether autonomic failure belongs to the clinical spectrum of spinocerebellar ataxia type 2 (SCA2), an autosomal dominant genetic disorder showing progressive cerebellar and brainstem dysfunction. METHODS: We evaluated cardiovascular autonomic function in 8 patients with SCA2 and 16 age- and gender-matched healthy controls. Other autonomic domains were examined through standardized questionnaires and by testing the skin sympathetic reflex. RESULTS: Patients with SCA2 showed normal responses to cardiovascular autonomic function tests, with the exception of lower baroreflex sensitivity upon standing compared to controls. In questionnaires, 7 out of 8 patients reported bladder disturbances, while 3 out of 6 tested patients had no skin sympathetic reflex. CONCLUSIONS: We did not observe clinically overt cardiovascular autonomic failure in patients with SCA2. Other autonomic domains (i.e., bladder and sudomotor function) may be affected in the disease.

Investigation of the malE promoter and MalR, a positive regulator of the maltose regulon, for an improved expression system in Sulfolobus acidocaldarius.

In this study, the regulator MalR (Saci_1161) of the TrmB family from Sulfolobus acidocaldarius was identified and was shown to be involved in transcriptional control of the maltose regulon (Saci_1660 to Saci_1666), including the ABC transporter (malEFGK), α-amylase (amyA), and α-glycosidase (malA). The ΔmalR deletion mutant exhibited a significantly decreased growth rate on maltose and dextrin but not on sucrose. The expression of the genes organized in the maltose regulon was induced only in the presence of MalR and maltose in the growth medium, indicating that MalR, in contrast to its TrmB and TrmB-like homologues, is an activator of the maltose gene cluster. Electrophoretic mobility shift assays revealed that the binding of MalR to malE was independent of sugars. Here we report the identification of the archaeal maltose regulator protein MalR, which acts as an activator and controls the expression of genes involved in maltose transport and metabolic conversion in S. acidocaldarius, and its use for improvement of the S. acidocaldarius expression system under the control of an optimized maltose binding protein (malE) promoter by promoter mutagenesis.

Physiological hypoxia prevents bile salt-induced apoptosis in human and rat hepatocytes.

BACKGROUND & AIMS: Hydrophobic bile salts such as glycochenodeoxycholate (GCDC) accumulate in cholestatic liver disease and induce hepatocellular apoptosis, promoting profibrotic signalling. The tissue microenvironment is an integral player in cellular pathophysiology, but it is not routinely incorporated into laboratory studies. Tissue oxygen partial pressure (pO2) may be an underestimated component of the microenvironment: in the liver, a pO2 of 30-45 mmHg (approximately 6% O2) is physiological, because of predominant portal blood supply. It was the aim of this project to investigate the impact of physiological hypoxia (i.e. 6% O2) on hepatocellular function, namely, bile salt-induced apoptosis. METHODS: Human hepatoma cells (HepG2-Ntcp) and primary rat hepatocytes were cultured at standard laboratory (hyperoxic) conditions (21% O2) and at physiological hypoxia (6% O2) in parallel for 1-8 days to study hepatocellular apoptosis and activation of signalling pathways. Standard laboratory analyses were applied for bile salt uptake, caspase-3/-7 activity, western blotting and gene-array analysis. RESULTS: Culturing at physiological hypoxia protected both human and rat hepatocytes against GCDC-induced apoptosis: caspase-3/-7 activation was diminished by 3.1 ± 0.5-fold in human HepG2-Ntcp and completely abolished in primary rat hepatocytes. Bile salt uptake was unaffected. Induction of hypoxia-inducible factor-1α indicated adaption to physiological hypoxia. The MEK/ERK cascade was activated and anti-apoptotic mediators were induced: N-Myc down-regulated gene, gelsolin and carbonic anhydrase IX were upregulated 12.4-, 6.5- and 5.2-fold respectively. CONCLUSIONS: We conclude from these data that (i) physiological hypoxia protects hepatocytes from bile salt-induced apoptosis, (ii) tissue pO2 is a crucial, underestimated component of the microenvironment and should (iii) be considered when studying hepatocellular physiology in vitro.

The sub-cellular localization of Sulfolobus DNA replication.

Analyses of the DNA replication-associated proteins of hyperthermophilic archaea have yielded considerable insight into the structure and biochemical function of these evolutionarily conserved factors. However, little is known about the regulation and progression of DNA replication in the context of archaeal cells. In the current work, we describe the generation of strains of Sulfolobus solfataricus and Sulfolobus acidocaldarius that allow the incorporation of nucleoside analogues during DNA replication. We employ this technology, in conjunction with immunolocalization analyses of replisomes, to investigate the sub-cellular localization of nascent DNA and replisomes. Our data reveal a peripheral localization of replisomes in the cell. Furthermore, while the two replication forks emerging from any one of the three replication origins in the Sulfolobus chromosome remain in close proximity, the three origin loci are separated.

Miniaturized CAR knocked onto CD3ε extends TCR function with CAR specificity under control of endogenous TCR signaling cascade.

Immunotherapy using TCR and especially CAR transgenic T cells is a rapidly advancing field with the potential to become standard of care for the treatment of multiple diseases. While all current FDA approved CAR T cell products are generated using lentiviral gene transfer, extensive work is put into CRISPR/Cas mediated gene delivery to develop the next generation of safer and more potent cell products. One limitation of all editing systems is the size restriction of the knock-in cargo. Targeted integration under control of an endogenous promotor and/or signaling cascades opens the possibility to reduce CAR gene size to absolute minimum. Here we demonstrate that a first-generation CAR payload can be reduced to its minimum component - the antigen-binding domain - by targeted integration under control of the CD3ε promoter generating a CAR-CD3ε fusion protein that exploits the endogenous TCR signaling cascade. Miniaturizing CAR payload in this way results in potent CAR activity while simultaneously retaining the primary antigen recognition function of the TCR. Introducing CAR-specificity using a CAR binder only while maintaining endogenous TCR function may be an appealing design for future autologous CAR T cell therapies.

The cytotoxicity of anti-CD22 immunotoxin is enhanced by bryostatin 1 in B-cell lymphomas through CD22 upregulation and PKC-ßII depletion.

BACKGROUND: In spite of potent first-line therapies for chronic lymphocytic leukemia, treatment remains palliative and all patients frequently relapse. Treatment options for these patients are more limited. BL22 is a recombinant protein composed of the variable region of a monoclonal antibody that binds to CD22 and of PE38, a truncated Pseudomonas exotoxin. BL22 is a very potent drug already used in patients with hairy cell leukemia, whereas in chronic lymphocytic leukemia its cytotoxicity is limited by a lower expression of CD22. Here we demonstrate that this limitation can be overcome by pre-activation of chronic lymphocytic leukemia cells with bryostatin 1. DESIGN AND METHODS: Primary malignant B cells from chronic lymphocytic leukemia and mantle cell lymphoma patients were used in vitro to assess the therapeutic impact of drug combinations using BL22 and bryostatin 1. RESULTS: We demonstrate that bryostatin 1 sensitizes chronic lymphocytic leukemia cells for the cytotoxic effects of BL22 through activation of protein kinase C and subsequently increased CD22 surface expression. Dose and time response analysis reveals that activation of protein kinase C further activates an autocrine feedback loop degrading protein kinase C-ßII protein. Depletion of protein kinase C-ßII and upregulation of CD22 persist for several days following pre-stimulation with bryostatin 1. Therefore, our data provide a rationale for the sequential administration of BL22 following bryostatin 1 treatment. In addition to primary chronic lymphocytic leukemia cells, bryostatin 1 also sensitizes diffuse large B-cell lymphoma and mantle cell lymphoma cells to BL22 induced apoptosis. CONCLUSIONS: Our data suggest that the combination of bryostatin 1 with antibodies directed against CD22 is a potent drug combination for the treatment of low- and high-grade B-cell lymphoma.

Next generation automated traceless cell chromatography platform for GMP-compliant cell isolation and activation.

Large-scale target cell isolation from patient blood preparations is one of the critical operations during drug product manufacturing for personalized cell therapy in immuno-oncology. Use of high-affinity murine antibody coated magnetic nanoparticles that remain on isolated cells is the current standard applied for this purpose. Here, we present the transformation of previously described technology - non-magnetic immunoaffinity column chromatography-based cell selection with reversible reagents into a new clinical-grade cell isolation platform called Automated Traceless Cell affinity chromatography (ATC). ATC is a fully closed and GMP-compliant cell selection and manufacturing system. Reversibility of reagents enables (sequential) positive cell selection, optionally in combination with depletion columns, enabling capture of highly specific cell subsets. Moreover, synergy with other Streptamer-based technologies allows novel uses beyond cell isolation including integrated and automated on-column target cell activation. In conclusion, ATC technology is an innovative as well as versatile platform to select, stimulate and modify cells for clinical manufacturing and downstream therapies.

The sulfolobicin genes of Sulfolobus acidocaldarius encode novel antimicrobial proteins.

Crenarchaea, such as Sulfolobus acidocaldarius and Sulfolobus tokodaii, produce antimicrobial proteins called sulfolobicins. These antimicrobial proteins inhibit the growth of closely related species. Here we report the identification of the sulfolobicin-encoding genes in S. acidocaldarius. The active sulfolobicin comprises two proteins that are equipped with a classical signal sequence. These proteins are secreted by the cells and found to be membrane vesicle associated. Gene inactivation studies demonstrate that both proteins are required for the bacteriostatic antimicrobial activity. Sulfolobicins constitute a novel class of antimicrobial proteins without detectable homology to any other protein.

Anatomically Standardized Detection of MRI Atrophy Patterns in Early-Stage Alzheimer's Disease.

MRI studies have consistently identified atrophy patterns in Alzheimer's disease (AD) through a whole-brain voxel-based analysis, but efforts to investigate morphometric profiles using anatomically standardized and automated whole-brain ROI analyses, performed at the individual subject space, are still lacking. In this study we aimed (i) to utilize atlas-derived measurements of cortical thickness and subcortical volumes, including of the hippocampal subfields, to identify atrophy patterns in early-stage AD, and (ii) to compare cognitive profiles at baseline and during a one-year follow-up of those previously identified morphometric AD subtypes to predict disease progression. Through a prospectively recruited multi-center study, conducted at four Austrian sites, 120 patients were included with probable AD, a disease onset beyond 60 years and a clinical dementia rating of ≤1. Morphometric measures of T1-weighted images were obtained using FreeSurfer. A principal component and subsequent cluster analysis identified four morphometric subtypes, including (i) hippocampal predominant (30.8%), (ii) hippocampal-temporo-parietal (29.2%), (iii) parieto-temporal (hippocampal sparing, 20.8%) and (iv) hippocampal-temporal (19.2%) atrophy patterns that were associated with phenotypes differing predominately in the presentation and progression of verbal memory and visuospatial impairments. These morphologically distinct subtypes are based on standardized brain regions, which are anatomically defined and freely accessible so as to validate its diagnostic accuracy and enhance the prediction of disease progression.

Immunotoxin BL22 induces apoptosis in mantle cell lymphoma (MCL) cells dependent on Bcl-2 expression.

Mantle cell lymphoma (MCL) is an incurable mature B cell proliferation, combining the unfavourable clinical features of aggressive and indolent lymphomas. The blastic variant of MCL has an even worse prognosis and new treatment options are clearly needed. We analysed the effects of BL22, an immunotoxin composed of the Fv portion of an anti- CD22 antibody fused to a 38-kDa Pseudomonas exotoxin-A fragment on four MCL cell lines as well as on primary cells of four MCL patients. Apoptosis induction by BL22 was much more pronounced in MCL cell lines with low Bcl-2 expression (NCEB-1, JeKo-1 and JVM-2) compared to Granta-519 cells with high Bcl-2 expression. While the expression of the antiapoptotic protein Mcl-1 declined (NCEB-1, Granta-519), Bcl-2 levels remained unchanged in Granta-519 cells. However transfection of BCL2 cDNA into NCEB-1, JeKo-1 and JVM-2 cells significantly reduced BL22-mediated toxicity. Accordingly we examined the effects of Bcl-2 inactivation in Granta-519 cells using siRNA. Indeed, apoptosis induction was strongly enhanced in Granta-519 cells with silenced Bcl-2. Our results were confirmed in freshly isolated MCL-cells from patients with leukaemic MCL. We conclude that Bcl-2 expression is important for mediating resistance against the immunotoxin BL22 in MCL cells.

Histone deacetylase inhibitors induce a very broad, pleiotropic anticancer drug resistance phenotype in acute myeloid leukemia cells by modulation of multiple ABC transporter genes.

PURPOSE: Histone deacetylase inhibitors (HDACi) are being studied in clinical trials with the aim to induce cellular differentiation, growth arrest, and apoptosis of tumor cells. Recent reports suggest that the multidrug resistance-1 (MDR1) gene is regulated by epigenetic mechanisms. To investigate whether additional drug transporters are regulated by HDACi and how this affects cytotoxicity, acute myeloid leukemia (AML) cells were examined. EXPERIMENTAL DESIGN: AML cells were cultured in the presence of phenylbutyrate, valproate, suberoylanilide hydroxamic acid, or trichostatin A and analyzed for drug transporter expression and function as well as sensitivity to anticancer drugs. RESULTS: MDR1, breast cancer resistance protein (BCRP), and multidrug resistance-associated proteins (MRP) 7 and 8 were induced in a dose- and time-dependent manner as shown by semiquantitative PCR. The pattern of gene induction was cell line specific. Phenylbutyrate induced P-glycoprotein and BCRP expression and the efflux of drugs as determined with labeled substrates. KG-1a cells treated with phenylbutyrate developed resistance to daunorubicin, mitoxantrone, etoposide, vinblastine, paclitaxel, topotecan, gemcitabine, and 5-fluorouracil; as a result drug-induced apoptosis was impaired. Chromatin immunoprecipitation revealed the hyperacetylation of histone proteins in the promoter regions of MDR1, BCRP, and MRP8 on valproate treatment. Furthermore, an alternative MRP8 promoter was induced by HDACi treatment. CONCLUSIONS: Exposure of AML cells to HDACi induces a drug resistance phenotype broader than the "classic multidrug resistance," which might negatively affect treatment effectiveness.

Identification of XylR, the Activator of Arabinose/Xylose Inducible Regulon in Sulfolobus acidocaldarius and Its Application for Homologous Protein Expression.

The thermophilic archaeon Sulfolobus acidocaldarius can use different carbon sources for growth, including the pentoses D-xylose and L-arabinose. In this study, we identified the activator XylR (saci_2116) responsible for the transcriptional regulation of the pentose transporter and pentose metabolizing genes in S. acidocaldarius. A xylR deletion mutant showed growth retardation on D-xylose/L-arabinose containing media and the lack of transcription of the respective ABC transporter. In contrast to so far used promoters for expression in S. acidocaldarius, the xylR responsive promoters have a very low background activity. Finally, two XylR dependent promoters next to the long-established maltose inducible promotor were used to construct a high-throughput expression vector system for S. acidocaldarius to efficiently clone and express proteins in S. acidocaldarius.

Encephalomyeloneuritis and arthritis after treatment with immune checkpoint inhibitors.

OBJECTIVE: Immunotherapy revolutionized melanoma treatment; however, immune-related adverse events, especially neurotoxicity, may be severe and require early and correct diagnosis as well as early treatment commencement. METHODS: We report an unusual severe multiorgan manifestation of neurotoxicity after treatment with the anti-PDL1 immune checkpoint inhibitor, nivolumab, and the anticytotoxic T-lymphocyte-associated antigen 4 immune checkpoint inhibitor, ipilimumab, in a 47-year-old male patient with metastatic melanoma. RESULTS: The patient developed immune-mediated synovitis and cranial neuritis, followed by longitudinal transverse myelitis, encephalitis, and optic neuritis. Early treatment with high-dose steroids and maintenance therapy with rituximab resulted in a favorable neurologic outcome. CONCLUSIONS: The frequency of spinal cord involvement and neuronal toxicity after cancer immunotherapy is very low and requires an extensive diagnostic workup to differentiate between disease progression and side effects. Immune checkpoint inhibitors should be discontinued and treatment with corticosteroids should be initiated early as the drug of first choice. Therapy may be escalated by other immune-modulating treatments, such as rituximab.

Expamers: a new technology to control T cell activation.

T cell activation is a cornerstone in manufacturing of T cell-based therapies, and precise control over T cell activation is important in the development of the next generation T-cell based therapeutics. This need cannot be fulfilled by currently available methods for T cell stimulation, in particular not in a time dependent manner. Here, we describe a modular activation reagent called Expamers, which addresses these limitations. Expamers are versatile stimuli that are intended for research and clinical use. They are readily soluble and can be rapidly bound and removed from the cell surface, allowing nearly instantaneous initiation and termination of activation signal, respectively. Hence, Expamers enable precise regulation of T cell stimulation duration and provide promise of control over T cell profiles in future products. Expamers can be easily adopted to different T cell production formats and have the potential to increase efficacy of T cell immunotherapeutics.

UV-inducible cellular aggregation of the hyperthermophilic archaeon Sulfolobus solfataricus is mediated by pili formation.

The hyperthermophilic archaeon Sulfolobus solfataricus has been shown to exhibit a complex transcriptional response to UV irradiation involving 55 genes. Among the strongest UV-induced genes was a putative pili biogenesis operon encoding a potential secretion ATPase, two pre-pilins, a putative transmembrane protein and a protein of unknown function. Electron microscopy and image reconstruction of UV-treated cells showed straight pili with 10 nm in diameter, variable in length, not bundled or polarized and composed of three evenly spaced helices, thereby clearly being distinguishable from archaeal flagella. A deletion mutant of SSO0120, the central type II/IV secretion ATPase, did not produce pili. It could be complemented by reintroducing the gene on a plasmid vector. We have named the operon ups operon for UV-inducible pili operon of Sulfolobus. Overexpression of the pre-pilins, Ups-A/B (SSO0117/0118) in Sulfolobus resulted in production of extremely long filaments. Pronounced cellular aggregation was observed and quantified upon UV treatment. This aggregation was a UV-dose-dependent, dynamic process, not inducible by other physical stressors (such as pH or temperature shift) but stimulated by chemically induced double-strand breaks in DNA. We hypothesize that pili formation and subsequent cellular aggregation enhance DNA transfer among Sulfolobus cells to provide increased repair of damaged DNA via homologous recombination.

Expanding and understanding the genetic toolbox of the hyperthermophilic genus Sulfolobus.

Although Sulfolobus species are among the best studied archaeal micro-organisms, the development and availability of genetic tools has lagged behind. In the present paper, we discuss the latest progress in understanding recombination events of exogenous DNA into the chromosomes of Sulfolobus solfataricus and Sulfolobus acidocaldarius and their application in the construction of targeted-deletion mutant strains.