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At least 577 records · Page 32Linked to original sources
PubMed1992

Complete sequence of a cDNA clone specifying sandbar shark immunoglobulin light chain: gene organization and implications for the evolution of light chains.

A full-length cDNA clone specifying sandbar shark (Carcharhinus plumbeus) immunoglobulin light chain has been isolated and sequenced. By alignment with human lambda chains, the leader, framework, complementarity-determining, joining, and constant regions are clearly identified in the shark light chain. Approximately 40-50% identity is shared between the human and shark sequences in the variable and constant regions. We have performed sequence comparisons of the individual segments and constructed phylogenetic trees for the variable region. These studies identify the shark protein as a lambda chain. In addition, the sandbar shark light chain is only distantly related to that of horned shark (Heterodontus francisci) [Shamblott, M. J. & Litman, G. W. (1989) Proc. Natl. Acad. Sci. USA 86, 4684-4688], demonstrating that the long evolutionary time of divergence among shark species has led to the generation of substantial differences in sequence. The positions of the variable, joining, and constant gene segments in 14 genomic clones have been mapped. The segments are linked in individual clusters (variable, joining, constant) occupying 3-7 kilobases. Cluster arrangement can be grouped into two patterns based upon spacing between the genes in the individual clones. This arrangement is fundamentally different from that observed in higher vertebrates.

Amino Acid Sequence↗
PubMed1984

Investigations of the role of the main light-harvesting chlorophyll-protein complex in thylakoid membranes. Reconstitution of depleted membranes from intermittent-light-grown plants with the isolated complex.

The functions of the light-harvesting complex of photosystem II (LHC-II) have been studied using thylakoids from intermittent-light-grown (IML) plants, which are deficient in this complex. These chloroplasts have no grana stacks and only limited lamellar appression in situ. In vitro the thylakoids showed limited but significant Mg2+-induced membrane appression and a clear segregation of membrane particles into such regions. This observation, together with the immunological detection of small quantities of LHC-II apoproteins, suggests that the molecular mechanism of appression may be similar to the more extensive thylakoid stacking seen in normal chloroplasts and involve LHC-II polypeptides directly. To study LHC-II function directly, a sonication-freeze-thaw procedure was developed for controlled insertion of purified LHC-II into IML membranes. Incorporation was demonstrated by density gradient centrifugation, antibody agglutination tests, and freeze-fracture electron microscopy. The reconstituted membranes, unlike the parent IML membranes, exhibited both extensive membrane appression and increased room temperature fluorescence in the presence of cations, and a decreased photosystem I activity at low light intensity. These membranes thus mimic normal chloroplasts in this regard, suggesting that the incorporated LHC-II interacts with photosystem II centers in IML membranes and exerts a direct role in the regulation of excitation energy distribution between the two photosystems.

Chlorophyll↗
PubMed1957

Sensitivity to light in the sea anemone Metridium senile (L). II. Studies of reaction time variability and the effects of changes in light intensity and temperature.

1. The reaction time of the photosensitive response of Metridium was found to be composed almost entirely of a sensitization period. If a latent period exists, it is too short to be detected by the methods used and is probably less than a second in duration. The length of the reaction time, therefore, was used as a measure of the radiant energy necessary at any intensity to elicit a response. 2. The length of the reaction time was found to vary randomly by a factor of seven under constant environmental and stimulating conditions. Determination of large numbers of reaction times on several anemones, grouped according to length, gave closely similar distributions resembling Poisson distributions. It was suggested that the variability may be caused by the same factor or mechanism in each individual. An experimental scheme was presented for determining the expected error and variation in statistical quantities when groups of ten observations are used. 3. The means of groups of reaction times determined at different intensities formed a hyperbolic relationship when plotted against intensity, suggesting that the animal obeys the Bunsen-Roscoe law of reciprocity. No marked changes were noted of per cent deviation from the mean or of randomness at different intensities. Stimulation of Metridium requires roughly 5 x 10(9) incident quanta/cm.(2) of blue-green light. 4. No temperature effect could be found on either the means, the per cent deviation from the mean, or the degree of randomness of series of about ten observations, studied over a 17 degrees C. range. It was concluded that the variability in reaction time was not due to changes in any complex physiological state such as muscular tone. 5. A possible use of the photosensitive response is suggested and the potentialities of "integrative" photosensitivity are discussed. 6. Possible mechanisms to explain the variability in reaction time are discussed. In the light of evidence presented, the most likely hypothesis appears to be the uncertainty of quantum capture caused by low concentrations of photosensitive pigment. Assuming the validity of this hypothesis, evidence suggests that the anemones responded to less than 10 quanta of absorbed light. Caution, however, is recommended in accepting the hypothesis because of the indirect nature of the supporting evidence.

Animals↗
PubMed2002

Two early light-inducible protein (ELIP) cDNAs from the resurrection plant Tortula ruralis are differentially expressed in response to desiccation, rehydration, salinity, and high light.

Tortula ruralis (Syntrichia ruralis) is a useful model system for the study of gene control in response to severe water deficit-stress. EST gene discovery efforts utilizing desiccated gametophytes have identified two cDNAs designated Elipa and Elipb with significant similarity to early light-inducible proteins (ELIPs). Elipa is 1006 bp in length, encoding a 212 amino acid deduced polypeptide (ELIPa) with a predicted molecular mass of 23.3 kDa and pI of 5.57. Elipb is 997 bp in length, encoding a 224 amino acid deduced polypeptide (ELIPb) with a predicted molecular mass of 24.4 kDa and pI of 9.27. Phylogenetic analysis demonstrated that ELIPa and ELIPb are reproducibly grouped with ELIP sequences derived from desiccation-tolerance tissues. RNA blot hybridization was used to analyse Elipa and Elipb mRNA abundance in response to a variety of stresses. Elipa steady-state transcript levels increased in response to slow desiccation, rapid desiccation/rehydration, salinity, ABA, and rehydration in high light. The Elipb transcript was only detectable in response to ABA or rehydration in high light. It is postulated that ELIPa and ELIPb are an adaptive response to stress-induced photodamage within the moss chloroplast, and play a key role in the protection and/or repair of the photosynthetic apparatus.

Abscisic Acid↗
PubMed1999

Kappa light chain-associated Fanconi's syndrome: molecular analysis of monoclonal immunoglobulin light chains from patients with and without intracellular crystals.

Plasma cell dyscrasias may be responsible for Fanconi's syndrome, due to the toxicity of a free monoclonal kappa light chain toward kidney proximal tubules. Eight cases of Fanconi's syndrome were analyzed. We compared the structures of VkappaI variability subgroup V domains from five cases of Fanconi's syndrome and one myeloma without renal involvement. Among Fanconi cases, four putative structures were obtained after molecular modeling by homology, and the other had previously been refined by X-ray crystallography. The complete sequences of one VkappaI, one VkappaIII and N-terminal sequences of two VkappaI light chains, from patients with different forms of Fanconi's syndrome, were compared with four previously studied sequences. All three kappa chains responsible for a 'classical' form with intralysosomal crystals and a low mass myeloma, were encoded by the LCO2/O12 germline gene and had an unusual non-polar residue exposed to the solvent in the CDR-L1 loop. Of both VkappaI light chains from patients with Fanconi's syndrome without intracellular crystals, one derived from LCO2/O12 and the other from LCO8/O18 gene. Another feature that could be related to non-crystallization was the absence of accessible side chains in the CDR-L3 loop which is known to be implicated in dimer formation.

Amino Acid Sequence↗
PubMed2004

Genetics, lighting environment, and heritable responses to lighting environment affect male color morph expression in bluefin killifish, Lucania goodei.

Determining the degree to which variation in traits is controlled by genetics and/or environment is fundamental to understanding adaptation. In this study, we examine the genetic and environmental influences on color pattern expression in male bluefin killifish, Lucania goodei. This is a compelling system because both male color patterns and vision physiology are correlated with basic properties of the environment. Across populations, males with blue anal fins are more abundant in waters with low transmission of UV and blue wavelengths. Here, we present results from two paternal half-sib breeding experiments (one in the laboratory, one in the greenhouse) in which offspring were raised under light treatments that mimicked natural variation in the spectral composition of light. In both experiments, we found that red-versus-yellow expression is controlled by an autosomal locus of large effect where yellow (Y) is dominant over red (y). There was little blue expression in the laboratory. In the greenhouse, we found higher expression of blue anal fin morphs when males were raised in tea-stained water (low transmission UV/blue) than when raised in clear water (high transmission UV/blue). We also found genetic effects of sires and an interaction between sire and lighting environment (i.e. heritable plasticity). These results show that a relatively simple, environmentally dependent, epistatic interaction can produce a large amount of variation in male color patterns that presumably function in sexual selection.

Analysis of Variance↗
PubMed2007

Charge differences between in vivo deposits in immunoglobulin light chain amyloidosis and non-amyloid light chain deposition disease.

Immunoglobulin light chain amyloidosis (AL) and non-amyloid light chain deposition disease (NALCDD) are different forms of protein aggregation disorders that may occur in plasma cell dyscrasias with dysproteinemia. In systemic AL, the deposits are fibrillar and patchy in distribution, within and amongst different organs, whereas in NALCDD, the deposits are granular and diffusely distributed in systemic basement membranes, suggesting different mechanisms of aggregation and deposition. Previous evidence, that charge differences between the light chains in AL and NALCDD might account for their different phenotypes, prompted the present study, which compared the isoelectric points (pIs) of AL and NALCDD protein deposits extracted from human tissues. The pI profiles (5.2-8.8) of polypeptides in AL deposits were heterogenous in four cases, with a spread of both anionic and cationic isoforms; in contrast, in three of NALCDD the pI profiles (8.2-8.8) were homogeneous and restricted in the cationic range. These in vivo findings in human disease, together with other reported in vitro and in vivo experimental data, suggest that the fibrillar deposits in AL may form by electrostatic interaction between oppositely charged polypeptides, whereas the granular deposits in NALCDD form by the binding of cationic polypeptides to anionic proteoglycans sites in basement membranes.

Amyloid↗
PubMed2006

Calibration of a wide-field frequency-domain fluorescence lifetime microscopy system using light emitting diodes as light sources.

High brightness light emitting diodes are an inexpensive and versatile light source for wide-field frequency-domain fluorescence lifetime imaging microscopy. In this paper a full calibration of an LED based fluorescence lifetime imaging microscopy system is presented for the first time. A radio-frequency generator was used for simultaneous modulation of light emitting diode (LED) intensity and the gain of an intensified charge coupled device (CCD) camera. A homodyne detection scheme was employed to measure the demodulation and phase shift of the emitted fluorescence, from which phase and modulation lifetimes were determined at each image pixel. The system was characterized both in terms of its sensitivity to measure short lifetimes (500 ps to 4 ns), and its capability to distinguish image features with small lifetime differences. Calibration measurements were performed in quenched solutions containing Rhodamine 6G dye and the results compared to several independent measurements performed with other measurement methodologies, including time correlated single photon counting, time gated detection, and acousto optical modulator (AOM) based modulation of excitation sources. Results are presented from measurements and simulations. The effects of limited signal-to-noise ratios, baseline drifts and calibration errors are discussed in detail. The implications of limited modulation bandwidth of high brightness, large area LED devices ( approximately 40 MHz for devices used here) are presented. The results show that phase lifetime measurements are robust down to sub ns levels, whereas modulation lifetimes are prone to errors even at large signal-to-noise ratios. Strategies for optimizing measurement fidelity are discussed. Application of the fluorescence lifetime imaging microscopy system is illustrated with examples from studies of molecular mixing in microfluidic devices and targeted drug delivery research.

Calibration↗
PubMed2006

Immunohistochemical study of immunoglobulin light chain amyloidosis with antibodies to the immunoglobulin light chain variable region.

To detect immunoglobulin (Ig) light chain amyloidosis (AL amyloidosis) in formalin-fixed, paraffin-embedded tissue sections by immunohistochemistry, polyclonal antibodies were generated against synthetic peptides corresponding to amino acids 1-19 of the Ig lambda light chain V lambda VI subgroup (anti-V lambda VI (1-19)) and the Ig kappa light chain Vkappa I subgroup (anti-Vkappa I (1-19)). Anti-V lambda VI (1-19) antibody reacted with amyloid deposits in 21 of 22 Alambda amyloidosis cases, and anti-Vkappa I (1-19) antibody reacted with amyloid deposits in 10 of 11 Akappa amyloidosis cases. Immunoreactivity varied in intensity by case and within specimens. Surprisingly, amyloid deposits were positive for anti-V kappa I (1-19) staining in one case of Alambda amyloidosis. Analysis of anti-V lambda VI (1-19) and anti-Vkappa I (1-19) antibody reactivity by ELISA showed some cross-reactivity with peptides other than antigen peptides. The antibodies were not reactive in all cases of AL amyloidosis examined but may be useful, together with anti-Ig constant region antibodies, for immunohistochemical diagnosis of AL amyloidosis.

Amyloid↗
PubMed1994

Correlation between recordings obtained with a light-intensity tester and degree of conversion of a light-curing resin.

The present study evaluated the ability of a light-intensity tester (CL-Tester) to predict the degree of conversion of a resin. A light-curing resin was mixed from 25 mol-% BISGMA and 75 mol-% TEGDMA. The resin was cured with one of five different curing units whose light intensity varied from poor to very good when recorded with the CL-Tester. The degree of conversion was found by determination of the number of remaining double bonds (RDB) from transmission infrared spectra of the resin. The five mean values of RDB varied with statistical significance. A significant linear correlation was found between recordings of the CL-Tester and degree of conversion. It was concluded that the CL-Tester was able to predict the degree of conversion to such a degree that it may be expected to constitute a useful means of regular control of curing units.

Analysis of Variance↗
PubMed1978

Light effects in yeast: inhibition by visible light of growth and transport in Saccharomyces cerevisiae grown at low temperatures.

Growth rate, sugar transport, and amino acid transport of yeast cells grown at 12 degrees C were inhibited by cool-white fluorescent light. At light intensities below 1,250 lx, growth and membrane transport were only slightly inhibited. Above 1,250 lx, there was increasing inhibition of both processes. Transport of histidine was completely inhibited after 3 to 5 days in cultures grown at 12 degrees C under 3,500-lx illumination. Cells grown at 20 degrees C were not inhibited by light intensities that caused complete loss of viability and membrane transport activity in cells grown at 12 degrees C.

Amino Acids↗
PubMed2004

The malic enzyme is required for optimal photoautotrophic growth of Synechocystis sp. strain PCC 6803 under continuous light but not under a diurnal light regimen.

A mutation was recovered in the slr0721 gene, which encodes the decarboxylating NADP(+)-dependent malic enzyme in the cyanobacterium Synechocystis sp. strain PCC 6803, yielding the mutant 3WEZ. Under continuous light, 3WEZ exhibits poor photoautotrophic growth while growing photoheterotrophically on glucose at rates nearly indistinguishable from wild-type rates. Interestingly, under diurnal light conditions (12 h of light and 12 h of dark), normal photoautotrophic growth of the mutant is completely restored.

Darkness↗
PubMed1996

[Development of a measuring set-up for determination of light distribution of scattered light applicators for interstitial laser treatment].

In the medical setting, scattering dome applicators are used in various therapeutic and diagnostic procedures, e.g. laser-induced interstitial thermotherapy. The present study reports on the development of an automatic measuring system for determining the light distribution along the active end of scattering dome applicators. Using a stepper motor, the applicator is gradually moved into an integrating sphere, in which the light intensity is measured with a photodetector. It was shown the light distribution is determined mainly by the conditions under which the laser beam is coupled to the transmission fiber. The results made it possible to optimize the production of applicators, and showed that the set-up was suitable for quality control use.

Equipment Design↗
PubMed1986

Influence of milk fat, milk solids, and light intensity on the light stability of vitamin A and riboflavin in lowfat milk.

Retinyl palmitate and riboflavin were quantified in milk samples exposed to fluorescent light. Effects of compositional factors were determined by comparing rates of loss of riboflavin and vitamin A in milks with different amounts of milk fat and milk solids. Upon exposure to fluorescent light, rates of vitamin A and riboflavin loss were lower in whole milk than in skim milk. Riboflavin degraded more slowly in skim milk with 1% added nonfat dry milk than in skim milk with no added solids. No additional protective effect for riboflavin was found when added solids were increased from 1 to 3%. Compared with milk with no added solids, 1% added nonfat dry milk did not increased protection for vitamin A, but a protective effect was noted when the skim milk was fortified with 3% nonfat dry milk. Increasing light intensity increased the rates of loss of both vitamins, and riboflavin was lost at a greater rate.

Animals↗
PubMedDate not supplied

[Fluorescence, excited by light in the 380-540 nm wavelength range, in in cucumber leaves depends on the time of vegetation and light regime].

The slow fluorescence induction produced in cucumber leaves by light in the range of wavelengths 380-540 nm and intensity of 180 W/m2 was studied. The ratio of fluorescence maxima in the red region (F734/F682) in young and mature leaves was approximately 2. It is assumed that this value depends on an increase in the contribution of the long-wavelength fluorescence due to the spillover effect. In plants grown under natural conditions, the parameter F734/F682 correlated with the concentrations of chlorophyll and carotenoids. In plants grown in the light of red and blue regions no such correlation was observed and the F734/F682 remained unchanged. It is concluded that the F534/F682 is affected by the intensity and spectral composition of exciting light used during the growing.

Carotenoids↗
PubMed1998

Effects of light intensity and air velocity on air temperature, water vapor pressure, and CO2 concentration inside a plant canopy under an artificial lighting condition.

In order to characterize environmental variables inside a plant canopy under artificial lighting in the CELSS, we investigated the effects of light intensity and air velocity on air temperature, water vapor pressure, and CO2 concentration inside a plant canopy. Under a PPF of 500 micromoles m-2 s-1, air temperature was 2-3 degrees C higher, water vapor pressure was 0.6 kPa higher, and CO2 concentration was 25-35 micromoles mol-1 lower at heights ranging from 0 to 30 mm below the canopy than at a height 60 mm above the canopy. Increasing the PPF increased air temperature and water vapor pressure and decreased CO2 concentration inside the canopy. The air temperature was lower and the CO2 concentration was higher inside the canopy at an air velocity of 0.3 m s-1 than at an air velocity of 0.1 m s-1. The environmental variables inside the canopy under a high light intensity were characterized by higher air temperature, higher vapor pressure, and lower CO2 concentration than those outside the canopy.

Air Conditioning↗
PubMed2002

Induction of light emission by luminescent bacteria treated with UV light and chemical mutagens.

Intensity of light emission by luminescent bacteria in response to UV irradiation and chemical mutagens was tested. We demonstrated that luminescence of six strains of marine bacteria (belonging to four species: Photobacterium leiognathi, P. phosphoreum, Vibrio fischeri and V. harveyi) is significantly increased by UV irradiation relatively shortly after dilution of cultures. Such a stimulation of luminescence was abolished in cells treated with chloramphenicol 15 min before UV irradiation, indicating that effective gene expression is necessary for UV-mediated induction of light emission. These results suggest that stimulation of luminescence in UV-irradiated bacterial cells may operate independently of the quorum sensing regulation. A significant induction of luminescence was also observed upon treatment of diluted cultures of all investigated strains with chemical mutagens: sodium azide (SA), 2-methoxy-6-chloro-9-(3-(2-chloroethyl)aminopropylamino)acridine x 2HCl (ICR-191), 4-nitro-o-phenylenediamine (NPD), 4-nitroquinolone-N-oxide (NQNO), 2-aminofluorene (2-AF), and benzo[alpha]pyrene. These results support the proposal that genes involved in bioluminescence belong to the SOS regulon. The use of bacterial luminescence systems in assays for detection of mutagenic compounds is discussed in the light of this proposal.

Bacterial Proteins↗
PubMed1992

[Measuring scattered light with the Opacity Lensmeter 701 in normal eyes and eyes with cataracts. Correlation between scattered light and cataract-induced vision loss].

In 50 eyes with nuclear cataract, posterior subcapsular cataract and cortical cataract and 34 normal eyes, the amount of scattered light was determined using the Opacity Lensmeter 701 to determine its accuracy in distinguishing between clear and cataractous lenses. Taking as a basis the manufacturer's statement that normal lenses show Opacity Lensmeter readings of less than 25 and that cataractous lenses show Opacity Lensmeter readings of more than 30, 94% of the nuclear cataract cases, 62% of the posterior subcapsular cases and 66% of the cortical cataract cases were identified as being pathologically opaque. Of the normal eyes, 88% had an Opacity Lensmeter reading of less than 25. Among the types of cataract examined, a significant linear relationship (P < 0.05) between visual acuity loss due to cataract and scattered light measurements could be found only in eyes with nuclear cataract, with the individual results heavily scattered around the linear regression. In the case of nuclear cataracts, measuring scattered light with the Opacity Lensmeter is suitable for making general statements on visual loss due to cataract for a whole group of patients. However, in individual cases the results can only be used together with other clinical examinations.

Adult↗