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At least 19 recordsLinked to original sources
PubMed2025

Biochemical and Structural Analyses of the Tardigrade DNA-Damage Suppressor Protein, Dsup.

Tardigrades are extremophiles that withstand harsh environments through unique molecular strategies. One such strategy involves Damage Suppressor (Dsup), a protein shown to protect cells from radiation-induced DNA damage. Little is known about the biochemical and structural characteristics of Dsup that lead to DNA protection. To gain insight into the mechanism of DNA protection by Dsup, we examined its fundamental biochemical and structural properties using mass photometry, biolayer interferometry, small-angle X-ray scattering, and microfluidic modulation spectroscopy. We found that Dsup is largely intrinsically disordered and binds DNA with high affinity via a multi-valent interface. This interaction induced conformational changes in both Dsup and the DNA, suggesting a potential structural mechanism of its DNA protection ability. We propose that Dsup alters DNA structure, possibly by partially unwinding it, to reduce its susceptibility to damage. These findings offer new insights into how a disordered protein such as Dsup functions as radioprotectants in extreme environments.

Tardigrada↗
PubMed2026

TFAM organizes DNA into compact higher order structures.

TFAM (Transcription Factor A, Mitochondrial) is an essential human protein that plays two key roles in mitochondrial DNA (mtDNA) homeostasis. TFAM acts as a transcription factor that specifically binds to promoter regions, but it is also solely responsible for organizing mtDNA into nucleoids by nonspecifically covering the entire genome. Many studies have addressed TFAM in transcription regulation, but its role as a genome organizing entity is not well characterized. The current understanding of how TFAM compacts DNA into nucleoids is based on crystal structures of a TFAM monomer bound to short fragments of DNA (22-28 bp). However, this does not adequately reflect the biological role of TFAM in organizing the nucleoid where multiple TFAM molecules oligomerize on the 16.5 kb genome to form the nucleoid. Here, we present a biochemical and structural analysis of TFAM oligomerization on longer DNA. Our results show that TFAM compacts longer segments of DNA into higher order complexes that are homogenous yet exhibit continuous conformational dynamics.

Major classification: Biological sciences↗
PubMed2004

Oligomeric state of the Escherichia coli metal transporter YiiP.

YiiP is a 32.9-kDa metal transporter found in the plasma membrane of Escherichia coli (Chao, Y., and Fu, D. (2004) J. Biol. Chem. 279, 17173-17180). Here we report the determination of the YiiP oligomeric state in detergent-lipid micelles and in membranes. Molecular masses of YiiP solubilized with dodecyl-, undecyl-, decyl-, or nonyl-beta-d-maltoside were measured directly using size-exclusion chromatography coupled with laser light-scattering photometry, yielding a mass distribution of YiiP homo-oligomers within a narrow range (68.0-68.8 kDa) that equals the predicted mass of a YiiP dimer within experimental error. The detergent-lipid masses associated with YiiP in the mixed micelles were found to increase from 135.5 to 232.6 kDa, with an apparent correlation with the alkyl chain length of the maltoside detergents. Cross-linking the detergent-solubilized YiiP with 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC) resulted in a dimeric cross-linked product in an EDC concentration-dependent manner. The oligomeric state of the purified YiiP in reconstituted membranes was determined by electron microscopic analysis of two-dimensional YiiP crystals in negative stain. A projection structure calculated from measurable optical diffractions to 25 A revealed a pseudo-2-fold symmetry within a molecular boundary of approximately 75 x 40 A, indicative of the presence of YiiP dimers in membranes. These data provide direct structural evidence for a dimeric association of YiiP both in detergent-lipid micelles and in the reconstituted lipid bilayer. The functional relevance of the dimeric association in YiiP is discussed.

Calibration↗
PubMed1986

The spectral sensitivity of blue-sensitive pigeon cones: evidence for complete screening of the visual pigment by the oil-droplets.

The relative spectral sensitivity of blue-sensitive pigeon cones was determined using flicker-photometry based on mass ERG-responses from intact subjects during high-level light adaptation. The resulting spectral sensitivity curve can be mimicked by a P460 nomogram screened by an oil-droplet that absorbs 50% at 466 nm. Comparison of the curve with the nomogram indicates that on the average less than 10% of the light that excites the blue-sensitive cones is guided past or diffracted around their oil-droplets.

Adaptation, Ocular↗
PubMed1984

[Screening and detection of the analgesic zomepirac].

The article describes some possibilities for the screening and detection of the analgesic sodium [5-(4-chlorobenzoyl)-1,4-dimethylpyrrol-2-yl]-acetate dihydrate (zomepirac). UV-photometry seems to be the best method for the urine screening. Gas chromatography with and without derivatization and mass spectrometry are recommended as confirming methods.

Analgesics↗
PubMed1983

Retinal reflex photometry as a screening device for amblyopia and preamblyopic states in children.

Aberration in the physical structure or alignment of the eyes may produce pathologic neurocompensatory changes in the brain that, if left unattended, become irreversible. Two common examples of this abnormal state are accommodative esotropia and amblyopia. Both have a large optic component in their etiology and in most cases are correctable by optic methods. Generated retinal reflex photometry is a screening method that can detect, in the eyes of children, optic defects that tend to be the antecedents of more serious neurocompensatory processes. Detection at an early age permits more effective management and treatment of amblyopia. This technique is fast, safe, and inexpensive and provides a permanent record. It requires no response from the subject except a modicum of cooperation. It is attractive as an ocular screening method because it does not require highly trained personnel to administer the examination, yet appears to be accurate. The results lend themselves to mechanized processing.

Age Factors↗
PubMed2007

Rapid characterization of alkylpolyphosphonates by CZE with indirect photometric and mass spectrometric detection.

Methods for the rapid characterization of industrial alkylpolyphosphonates (APPs) by infusion MS and CZE with indirect photometric (IPD) and MS detection are described. Technical-grade APPs, including alkylaminepolyphosphonates with 3-5 phosphonate groups and different hydrocarbon skeletons, hydroxyethyl-amino-bis(methylenephosphonic acid), hydroxyethylidene-diphosphonic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid, were examined. A 10 mM solution of adenosine triphosphate disodium salt at pH 2.2 was used as BGE. The nominal compounds of the industrial APPs and their impurities were well resolved in less than 15 min. The peaks were identified by using extracted ion electropherograms, which were obtained at the m/z values indicated by the peaks of the infusion spectra. Low concentrations of esters, anhydrides, and APPs having different hydrocarbon skeletons compared to nominal compounds, and lacking phosphonate and methylene-phosphonate groups with respect to them, were found. Also, hydroxyethyl-aminobis(methylenephosphonic acid) contained an intramolecular ester at a concentration close to that of the nominal compound. Application of CZE-IPD and CZE-MS to the quality control of industrial APPs, and of CZE-MS to the identification and characterization of APPs in cleaning products, was demonstrated.

Electrophoresis, Capillary↗
PubMed1984

Interlaboratory survey on thallium in urine.

Quality assurance of analytic results was legalized in the Federal Republic of Germany by the law regulating the calibration of measuring devices of July 11, 1969, and the ordinance concerning the exception from compulsory calibration dated June 29, 1970. Accordingly, in the field of health care the Guidelines of the Medical Society of West Germany for the realization of quality assurance activities have to be followed. Since January 1, 1974, the law regulating the calibration of measuring devices has been fully effective. In the field of legal medicine the clinico-toxicologic analysis is considered to be a part of health care. As far as quantitative determinations are considered, these analyses have to follow the regulations mentioned above. To fulfil the basic program, adequate control samples are necessary. For toxicologic analysis there have been no control samples so far. Therefore, a control sample for thallium has been developed which can be used for long- and short-term interlaboratory surveys. The results are reported.

Forensic Medicine↗
PubMed1975

[Research on the effectiveness of gynecological prescreening (author's transl)].

Malignant tumors are determined by abnormal values of DNA as well as in its precursors. The cytophotometric analysis of smears allowed the determination of DNA of higher number of cells and therefore was presented as prescreening. But higher amounts of DNA caused by colpitis was reached too in this case. Therefore the presented research tried to limit points of malignancy by determination ofDNA, RNA, Histones, and Heterochromatin of cytologically classified cells. The discussion of results with literature pointed out, that this object is only reaching today by simultaneous determination of DNA and Heterochromatin of selected "atypical" cells.

Bibliographies as Topic↗
PubMed1980

Cytophotometric measurement of nuclear DNA and lysine as a method for automated screening of cervical smears.

An automated initial screening of cervical smears would be of great benefit as much time would be saved by removing the need to rely on cytologists for the diagnosis of negative smears. The computerized evaluation of DNA histograms obtained by impulse cytophotometry shows promise but the additional determination of the amount of lysine in the nucleus would seem to be of value. Three mathematical methods for the evaluation of histograms are presented and compared. It is shown that measurements of nuclear DNA as well as lysine improve the diagnostic accuracy of automated screening processes.

Cell Nucleus↗
PubMed2005

Antimicrobial activity of conditioned medium fractions from Spodoptera frugiperda Sf9 and Trichoplusia ni Hi5 insect cells.

Concentrated conditioned medium (CM) fractions from Spodoptera frugiperda Sf9 and Trichoplusia ni cells, eluting from a gel filtration column at around 10 kDa, were found to exhibit strong antibacterial activity against Bacillus megaterium and Escherichia coli. The B. megaterium cells incubated in the CM fraction from Sf9 cells rapidly lost viability: after 8 min the viability had decreased to 0.7%, as compared with the control. Addition of the CM fraction to E. coli cells resulted in a less drastic drop in viability: 65% viability was lost after 60 min of incubation. Further, exposure to the CM fraction caused a substantial leakage of intracellular proteins, as demonstrated by SDS-PAGE analysis. Cell lysis was confirmed by optical density measurements, microscopic investigations and flow cytometry. B. megaterium exposed to a CM fraction from T. ni cells lost 97% of their viability in about 40 min. Ubiquitin, thioredoxin and cyclophilin were identified in the antibacterial fraction from Sf9 cells by mass spectrometry and N-terminal amino acid sequencing. Other proteins in the fraction gave no matches in a database search. Since ubiquitin was shown not to cause the antimicrobial effect and thioredoxin and cyclophilin were likely not involved, the responsible agent may be an unknown protein, not yet registered in databases. The antimicrobial effect of the CM fraction from T. ni cells most probably comes from a lysozyme precursor protein.

Animals↗
PubMed1990

Blood cholesterol screening in several environments using a portable, dry-chemistry analyzer and fingerstick blood samples. Lipid Research Clinics Cholesterol Screening Study Group.

A multicenter study of blood cholesterol screening was performed in several typical environments, such as community sites (shopping malls and a supermarket), health care sites, work sites, a blood bank and a school. Cholesterol was measured with a portable, dry-chemistry analyzer using capillary blood obtained by fingerstick. Data are reported from a total of 13,824 participants, spanning the entire age spectrum. Overall, 25% of screened subjects had blood cholesterol levels above the age-specific cutpoints used in the current study. Although in the aggregate this screening experience very closely approximates the expected level of referrals, the proportion of referred screened subjects differed significantly among the 5 types of screening environments and by gender. Follow-up telephone interviews indicated that 53% of referrals had initiated a physician contact. More than 75% of those who had seen a physician reported that the diagnosis of hypercholesterolemia had been confirmed, and almost 72% had been prescribed a diet. A large proportion of referred screened subjects reported having modified their diet, particularly when recommended to do so by a physician. This study has yielded encouraging evidence that physicians gave referred screened subjects appropriate initial advice for managing hypercholesterolemia. The new technology for blood cholesterol measurement evaluated in the current study has proven to be a feasible and reliable means for measuring blood cholesterol in typical screening settings.

Adult↗
PubMed2001

Determination of lewisite oxide in soil using solid-phase microextraction followed by gas chromatography with flame photometric or mass spectrometric detection.

A rapid, sensitive, and convenient method is described for determining Lewisite oxide in soil. Samples are initially fortified with phenylarsine oxide (surrogate), then both species are extracted using ascorbic acid solutions containing 1,3-propanedithiol (derivatizing reagent). The corresponding filtered supernatant is sampled using a solid-phase microextraction fiber. Collected analytes are thermally desorbed in a heated gas chromatographic inlet, separated using fused-silica capillary columns ("primary" and "confirmatory"), and detected with either a mass spectrometric (selected ion monitoring mode) or flame photometric (sulfur-selective mode) detector. Two independent statistically-unbiased procedures were used to evaluate the detection limit for Lewisite oxide; the values range between 0.1 and 0.5 microg g(-1) soil.

Arsenicals↗
PubMed2003

High-performance size-exclusion chromatography of peptides.

Gel filtration on soft gels has been employed for over 40 years for the separation, desalting and molecular weight estimation of peptides and proteins. Technical improvements have given rise to high-performance size-exclusion chromatography (HPSEC) on rigid supports, giving more rapid run times and increased resolution. Initially, these packings were more suitable for the separation of proteins than of peptides, but supports that operate in the fractionation range <10,000 Daltons (Da) are now available. In this report, HPSEC is described in relation to its application to peptides, especially regarding purification, estimation of molecular weight and study of molecular associations.

Chromatography, Gel↗
PubMed2000

Analysis of amines in plant materials.

Biogenic amines are conveniently divided into aliphatic monoamines, aliphatic di- and polyamines and aromatic amines. These compounds are shown to fulfill an array of roles in cellular metabolism. Thus, amines are needed for growth and development and their metabolism appears to be coordinated with the cell cycle. Di- and polyamines, among which are putrescine, spermidine and spermine, are ubiquitous polycationic molecules that occur in all living cells. However, plants accumulate a number of specific related compounds under free or conjugated forms. In plant tissues, the molecular diversity combined with the fact that amine contents are highly responsive to developmental and environmental signals encouraged analysts to develop specific procedures for their isolation and characterization. The main goals were to develop high performance routine procedures in terms of selectivity, repeatability and detectability with minimum running costs. Domains of application concern not only fundamental aspects of amine biochemistry and physiology in plants but also increasing needs in the control of food and beverage quality from plant origin. The present review reports the most recent advances in extraction, identification and quantitation of amines in plant tissues with special interest in the analysis of original and uncommon metabolites. Emphasis is directed towards chromatographic and electrophoretic separation methodologies and new detection technologies of both derivatized and underivatized compounds including photometry, fluorometry, amperometry and mass spectrometry.

Amines↗