The effect of supraphysiological dose of nandrolone decanoate administration on the inflammatory, neurotrophin and behavioral response in adult and old male mice

This study examined the effect of 6 weeks of supraphysiological nandrolone decanoate (ND) administration in adult mice (7 months) on cognitive function and neuroinflammation during aging. Male C57BL/6 mice were randomized into ND (10 mg·kg-1·wk-1) or control (CTL) groups. Half of the mice were tested at a young (Y) age (ND-Y and CTL-Y), 1 week following final ND administration, while the remaining mice were tested at 16 months (O) (ND-O and CTL-O). Learning and memory were better in young mice compared to older mice, regardless of treatment. ND-O displayed decreased anxiety as compared to all other groups. TNFα and IL1β expression were higher in older mice, regardless of treatment. ND administration in young mice appeared to attenuate the neuroinflammatory response in aging mice as evidenced by decreased COX2, IL-4 and increased IL-10 expression in ND-O compared to CTL-O. BDNF AR and ER expression increased in ND-O compared to CTL-O. Results of the study indicated that supraphysiological ND administration had no negative effect on learning and memory but may attenuate anxiety in older mice. In addition, ND administration in young adult mice may attenuate the inflammatory response during aging, which may be related to elevations in both AR and ER expression.

Studying the efficacy of escalated dose conformal radiation therapy in prostate carcinoma - Pakistan experience

BACKGROUND

Our objective in this study was to evaluate the role and benefits in terms of local toxicity and biochemical disease-free survival (bDFS) following escalated-dose conformal radiation therapy in prostate adenocarcinoma.

METHODS

The study population was composed of 53 patients with histologically proven T1b-T4, NO, MO prostate adenocarcinoma, having any Gleason score with prostate-specific antigen (PSA) of less than 50 ng/mL at diagnosis, given escalated dose EBRT (74 Gy) during the period between January 2011 and December 2013, retrospectively and evaluated for a period of 2 years post-radiation. Patients were followed up for a period of 2 years, beginning after completion of escalated dose external beam radiotherapy (EBRT) for biochemical failure as defined in ASTRO consensus committee guidelines 1996 and investigated for gastrointestinal, genitourinary skin toxicity.

RESULTS

Out of 53 patients, 35 showed no biochemical failure at the end of 2 years following the completion of definitive escalated dose conformal radiotherapy while 18 were observed to have biochemical relapse. Acute gastrointestinal grade 1 toxicity was found in 26 patients, grade 2 in 24, and grade 3 only in 3 patients. Late gastrointestinal grade 0 toxicity was found in 16 patients, grade 1 in 28, grade 2 in 7 and grade 3 only in 2 patients. Grade 1 acute genitourinary toxicity was the highest in frequency observed in 28 of the total population followed by grade 2 in 21, grade 0 and grade 3 each, only in 2 patients. Late genitourinary Grade 0 toxicity was observed in 32 patients, grade 1 in 19, grade 2 and 3 only in 1 patient of the total population, respectively.

CONCLUSION

Our data were comparable to international studies of dose escalation using 3D and beneficial as compared to conventional radiation therapy delivered by 2D in terms of biochemical failure rate and treatment related toxicity.

Allele frequencies of nine STR loci of Jewish and Arab populations in Israel

DNA typing of nine short tandem repeat (STR) loci was carried out on unrelated Israeli Jewish and Arab individuals. All loci were highly polymorphic and the distribution of the obtained genotypes did not deviate from Hardy-Weinberg equilibrium. A comparison between Jewish and Arab population data revealed statistically significant differences in allele frequency distributions for some of the loci. The results presented in this study enable the use of these nine STR loci for forensic, identification and paternity cases in the Jewish and the Arab populations of Israel.

Fingerprints and DNA: STR typing of DNA extracted from adhesive tape after processing for fingerprints

An exhibit that is often received for examination in cases of robbery or terrorist activity is adhesive tape. This type of exhibit can often, but not always, be successfully processed for fingerprints. The question arises whether or not it is possible to extract and type DNA after the tape has been sequentially processed for fingerprints. In this work, various donors left fingerprints on the adhesive side of tapes. The tapes were then sequentially processed for fingerprints using an alternate light source, cyanoacrylate fuming, and staining with BY-40 and then crystal violet. DNA was subsequently successfully extracted, amplified and typed for six STR loci.

Light-harvesting complex II pigments and proteins in association with Cbr, a homolog of higher-plant early light-inducible proteins in the unicellular green alga Dunaliella

Like higher plants, unicellular green algae of the genus Dunaliella respond to light stress by enhanced de-epoxidation of violaxanthin and accumulation of Cbr, a protein homologous to early light-inducible proteins (Elips) in plants. Earlier studies indicated that Cbr was associated with the light-harvesting complex of photosystem II (LHCII) and suggested it acted as a zeaxanthin-binding protein and fulfilled a photo-protective function (Levy et al. 1993, J. Biol. Chem. 268: 20892-20896). To characterize the protein-pigment subcomplexes containing Cbr in greater detail than attained so far, thylakoid membranes from Dunaliella salina grown in high light or normal light were solubilized with dodecyl maltoside and fractionated by isoelectric-focusing. Analysis of the resolved LHCII subcomplexes indicated preferred associations among the four LHCIIb polypeptides and between them and Cbr: subcomplexes including Cbr contained one or two of the more acidic of the four LHCIIb polypeptides as well as large amounts of lutein and zeaxanthin relative to chlorophyll a/b. After sucrose gradient centrifugation, Cbr free of LHCIIb polypeptides was detected together with released pigments; this Cbr possibly originated in subcomplexes dissociated in the course of the analysis. These results agree with the conclusion that Cbr is part of the network of LHCIIb protein-pigment complexes and suggest that the role played by Cbr involves the organization and/or stabilization of assemblies highly enriched in zeaxanthin and lutein. Such assemblies may function to protect PSII from photodamage due to overexcitation.

Threat mail and forensic science: DNA profiling from items of evidence after treatment with DFO

Two cases of threatening letters with their accompanying envelopes were received to the Division of Forensic Identification unit of the Israel Police. The envelopes, including the stamps, and the letters were initially examined for latent fingerprints by the DFO reagent, known to cause degradation of DNA. Although no latent fingerprints could be visualized on any of the items, the biology laboratory using organic DNA extraction, was successful in defining genetic profiles from all the items employing six STR loci, even after treatment with DFO. In a controlled experiment, a known donor attached a stamp, by licking, to an envelope. This item was treated with DFO and then profiled using STR loci. The results showed that previous DFO treatment on the control stamp before DNA analysis had no negative effects on obtaining the DNA profile of the known donor using STR loci.

An evaluation of the relevance of routine DNA typing of fingernail clippings for forensic casework

DNA extracted from fingernail clippings of victims in forensic cases is a possible source of DNA from the perpetrator in cases where victims struggled or defended themselves. The source of this DNA on a victim's fingernails could possibly originate from contact with the suspect's blood, saliva, semen or scratched skin. In this technical note we evaluate the relevance of routine DNA typing of fingernail clippings in the forensic biology laboratory when, in real casework, normally only small quantities of nail material is sent. This was carried out by extracting DNA from fingernail clippings from a number of volunteers, before and after aggressively scratching other volunteers. No blood was drawn from the scratching, but skin flakes were observed under the nails before cutting and subsequent DNA typing. The DNA extracted was then typed using the STR systems: HUMTHO1, HUMTPOX and HUMCSF1PO (CTT triplex) and the system of D1S80. These profiles were compared with profiles achieved by similar typing of buccal swabs as a reference from each volunteer. In this study, the profile detected from each volunteer's clippings was the same before and after scratching, and matched the profile of the corresponding volunteer as defined by typing each volunteer's reference buccal swab. Fingernail clippings that are sent to our lab in actual casework are usually so small that additional treatment by swabbing or removing debris from below the clipping is not possible. For this reason, in this simulation the entire clippings were used for DNA extraction, to maximize the possibility of finding an additional profile. In conclusion, the findings from this study show that although the profiles obtained when typing fingernail clippings are those of the donors themselves, we suggest that typing of fingernail clippings should be carried out in forensic cases only when relevant. We would suggest that fingernail clippings not be routinely sent to the biology laboratory as items of evidence to be tested.

Differential responses to different light spectral ranges of violaxanthin de-epoxidation and accumulation of Cbr, an algal homologue of plant early light inducible proteins, in two strains of Dunaliella

Unicellular green algae of the genus Dunaliella, similar to higher plants, respond to light stress by enhanced de-epoxidation of violaxanthin and accumulation of Cbr, a protein homologous to early light inducible proteins (Elips) in plants. These proteins belong to the superfamily of chlorophyll a/b binding proteins. Two Dunaliella strains, D. bardawil and D. salina, were compared for these two responses under light in the UVA, blue, green and red spectral ranges. In D. bardawil, the two stress responses were similarly induced under UVA, blue or red light and to a lesser extent under green light. In D. salina, a similar spectral range dependence was exhibited for violaxanthin de-epoxidation. However, Cbr accumulated only under UVA or blue light but not under green or red light. A strong synergistic effect of a low dose of blue light superimposed on red light resulted in Cbr accumulation. These results reveal strain-specific differences in spectral range requirements of the two light-stress responses. In the two strains, violaxanthin de-epoxidation is triggered under photosynthetically-active spectral ranges but at least in D. salina, Cbr accumulation appears to require a specific light signal additionally to a signal(s) generated by light stress.

Iron uptake by the halotolerant alga Dunaliella is mediated by a plasma membrane transferrin

A 150-kDa transferrin-like protein (Ttf) is associated with the plasma membrane of the halotolerant unicellular alga Dunaliella salina (Fisher, M., Gokhman, I., Pick, U., and Zamir, A. (1997) J. Biol. Chem. 272, 1565-1570). The Ttf level rises with medium salinity or upon iron depletion. Evidence that Ttf is involved in iron uptake by Dunaliella is presented here. Algal iron uptake exhibits characteristics resembling those of animal transferrins: high specificity and affinity for Fe3+ ions, strict dependence on carbonate/bicarbonate ions, and very low activity in acidic pH. Reducing the level of Ttf by mild proteolysis of whole cells is accompanied by lowered uptake activity. Conversely, accumulation of high levels of Ttf is correlated with an enhancement of iron uptake. Kinetically, iron uptake consists of two steps: an energy-independent binding of iron to the cell surface and an energy-dependent internalization. Salinities as high as 3.5 M NaCl do not inhibit iron uptake or decrease the apparent affinity for Fe3+ ions, implying that Ttf activity is not affected by high salt. These results indicate that transferrins, hitherto identified only in animals, are present and function in iron transport also in plant systems.

Immunoproliferative small intestinal disease in a 16-year-old boy presenting as severe malabsorption with excellent response to tetracycline treatment

Immunoproliferative small intestinal disease (IPSID) is a rare lympho-proliferative disorder of the upper small intestine. It is considered a special form of MALT lymphoma with propensity to malignant transformation. This disorder is rare in pediatric literature. We report a case of IPSID in a 16-year-old boy with low-grade malignant transformation, presenting as severe malnutrition and a possible association with Helicobacter pylori. The patient responded well to an extended treatment with tetracycline and eradication of H. pylori.

A structurally novel transferrin-like protein accumulates in the plasma membrane of the unicellular green alga Dunaliella salina grown in high salinities

The alga Dunaliella salina is outstanding is its ability to withstand extremely high salinities. To uncover mechanisms underlying salt tolerance, a search was carried out for salt-induced proteins. The level of a plasma membrane 150-kDa protein, p150, was found to increase with rising external salinity (Sadka, A., Himmelhoch, S., and Zamir, A. (1991) Plant Physiol. 95, 822-831). Based on its cDNA-deduced sequence, p150 belongs to the transferrin family of proteins so far identified only in animals. This, to our best knowledge, is the first demonstration of a transferrin-like protein in a photosynthetic organism. Unlike animal transferrins, p150 contains three, rather than two, internal repeats and a COOH-terminal extension including an acidic amino acid cluster. In intact cells p150 is degraded by Pronase, indicating that the protein is extracellularly exposed. The relationship of p150 to iron uptake is supported by the induction of the protein in iron-deficient media and by its radioactive labeling in cells grown with 59Fe. Accumulation of p150 is transcriptionally regulated. It is proposed that p150 acts in iron uptake other than by receptor-mediated endocytosis and that its induction permits the cells to overcome a possible limitation in iron availability under high salinities.

A salt-resistant plasma membrane carbonic anhydrase is induced by salt in Dunaliella salina

The mechanisms allowing proliferation of the unicellular green alga Dunaliella salina in up to saturating NaCl concentrations are only partially understood at present. Previously, the level of a plasma membrane Mr 60,000 protein, p60, was found to increase with rising external salinities. Based on cDNA cloning and enzymatic assays, it is now shown that p60 is an internally duplicated carbonic anhydrase, with each repeat homologous to animal and Chlamydomonas reinhardtii carbonic anhydrases, but exceptional in the excess of acidic over basic residues. Increasing salinities, alkaline shift, or removal of bicarbonate induced in D. salina parallel increases in the levels of p60, its mRNA, and external carbonic anhydrase activity. Moreover, purified p60 exhibited carbonic anhydrase activity comparable to other carbonic anhydrases. A p60-enriched soluble preparation showed maximal carbonic anhydrase activity at approximately 1.0 M NaCl and retained considerable activity at higher salt concentrations. In contrast, a similar preparation from C. reinhardtii was approximately 90% inhibited in 0.6 M NaCl. These results identified p60 as a structurally novel carbonic anhydrase transcriptionally regulated by CO2 availability and exhibiting halophilic-like characteristics. This enzyme is potentially suited to optimize CO2 uptake by cells growing in hypersaline media.

Possible Role of Cbr, an Algal Early-Light-Induced Protein, in Nonphotochemical Quenching of Chlorophyll Fluorescence

The unicellular green alga Dunaliella bardawil exhibits typical responses to excessive light when starved for sulfate under normal light (60 [mu]E m-2 s-1) but not under low light (14 [mu]E m-2 s-1). Algae were analyzed during several days of sulfate starvation for nonphotochemical quenching of chlorophyll fluorescence in the absence or presence of the uncouplers SF-6847 (SF) or carbonyl cyanide p- trifluoromethoxyphenyl hydrazone. Parallel analyses followed two light-stress responses: (a) violaxanthin conversion to zeaxanthin and (b) accumulation of Cbr, a protein analogous to plant early-light-induced proteins and implicated in zeaxanthin binding. In cells starved under normal light SF inhibited nonphotochemical quenching during the first 24 h, but not from 40 h onward. In cells starved under low light SF inhibited nonphotochemical quenching throughout the starvation period. Under normal light accumulation of zeaxanthin was nearly maximal by 24 h, but Cbr was fully induced only by 40h. Under low light zeaxanthin accumulated slowly but no Cbr was evident. These results suggest that during exposure to excessive light, the initial pH gradient-dependent, Cbr-independent mode of nonphotochemical quenching is modified to become less dependent on pH gradient and requires Cbr.

A Salt-Induced 60-Kilodalton Plasma Membrane Protein Plays a Potential Role in the Extreme Halotolerance of the Alga Dunaliella

The halotolerant alga Dunaliella salina grows in saline conditions as varied as 0.5 and 5 M NaCl, maintaining throughout this range a low intracellular ion concentration. To discover factors potentially involved in ionic homeostasis, we grew cells in media with different salinities or osmolarities and compared their protein profiles. The comparisons indicated that the amount of a 60-kD protein, p60, greatly increased with an increase in salinity and was moderately enhanced when NaCl was substituted with iso-osmotic glycerol. Cells transferred from low to high NaCl or from high glycerol to iso-osmotic NaCl media transiently ceased to grow, and resumption of growth coincided approximately with an increase in p60. The protein, extracted from a plasma membrane fraction, was purified to homogeneity. Anti-p60 antibodies cross-reacted with a 60-kD protein in Dunaliella bardawil. Immunoelectron microscopy of D. salina cell sections indicated that p60 was exclusively located in the plasma membrane. Its induction by salt, the correlation between its accumulation and growth resumption in high concentrations of salt, and its plasma membrane localization suggest the possibility that p60 could play a role in ionic homeostasis in conditions of high salinity, although different types of function could also be considered.

Wall hangings, hairs and the Holocaust

Two wall hangings, from the time of the Second World War, were reportedly made from human hair. Laboratory examination of the hangings confirmed this fact. Fibers, holding the wall hangings together, and the weave of the hangings were also examined. Results and implications of the findings are discussed.

Chaperonins as potential gene regulatory factors. In vitro interaction and solubilization of NifA, the nif transcriptional activator, with GroEL

A previous study (Govezensky, D., Greener, T., and Zamir, A. (1991) J. Bacteriol. 20, 6339-6346) indicated that the chaperonin GroEL was required for maximal expression from nif promoters in Klebsiella pneumoniae and nif-transformed Escherichia coli. That this requirement stemmed from the ability of GroEL to properly fold NifA, the nif transcriptional activator, was first supported by co-immunoprecipitation of NifA in K. pneumoniae extracts with anti-GroEL antibodies. In the present in vitro study, NifA, partially purified from E. coli overexpressing the protein, was diluted from a 6 M urea solution into a refolding buffer in the presence or absence of GroEL. Dilution in the absence of GroEL caused the complete precipitation of NifA. When present in the dilution buffer, GroEL bound NifA and maintained it in a soluble state. GroEL was also found to bind NifA newly synthesized in an in vitro translation system. For both NifA preparations, cochaperonin GroES and ATP promoted release of NifA from GroEL. These results provide evidence for the association of NifA with GroEL and for the role of both GroEL and GroES in the solubilization and thereby folding of the nif transcriptional activator.

Refinements of an isoelectric focusing multi-enzyme phenotyping system

Several modifications have been made to a system of simultaneous phenotyping of EAP, EsD, PGM and ADA in bloodstains by isoelectric focusing, which improved the results of the system. An increase in the thickness of the gel improved the resolution of the isozymes' bands, especially PGM and EAP, and diminished the effect of overloading. By increasing the width of the gel it was possible to increase the number of samples applied to the gel. By coating one of the glass plates, used in the preparation of the gels, with a hydrophobic solution, separation of the plate from the gel was greatly facilitated. Finally, the system was found to be very useful as a rapid screening method prior to DNA testing.

Cbr, an algal homolog of plant early light-induced proteins, is a putative zeaxanthin binding protein

The cbr gene, previously cloned from the unicellular green alga Dunaliella bardawil, is transcriptionally and translationally activated in parallel to accelerated carotenogenesis in response to light stress conditions. The product of cbr, structurally similar to Elips (early light-induced proteins of higher plants), is associated with a minor light harvesting complexes of photosystem II component (Levy, H., Gokhman, I., and Zamir, A. (1992) J. Biol. Chem. 267, 18831-18836). This study examines the relationship between the induction of Cbr and another plant response to light stress, the deepoxidation of violaxanthin to zeaxanthin. A parallel between the two processes was observed in cells exposed to high light, starved for sulfate, or treated with norflurazon, a herbicide inducing photooxidative damage by inhibiting de novo carotenoid biosynthesis. When highly illuminated cells were returned to normal light, Cbr decayed in parallel to the reepoxidation of zeaxanthin to violaxanthin. Evidence for the physical association of Cbr and zeaxanthin was provided by nondenaturing gel electrophoresis. In cells transferred from low to high light, zeaxanthin was associated with the faster migrating of two electrophoretically resolved fractions of light harvesting complexes of photosystem II that also contained Cbr. In cells growing under normal light, violaxanthin was bound equally to the two fractions. Based on these results we propose that Cbr/early light-induced proteins bind zeaxanthin to form photoprotective complexes within the light-harvesting antennae.

A novel multicopy suppressor of a groEL mutation includes two nested open reading frames transcribed from different promoters

When present on a multicopy plasmid, a newly discovered gene (sugE) mapping to 94 min on the Escherichia coli chromosome, suppresses a groEL mutation and mimics the effects of groE overexpression. A groEL mutant of E.coli, transformed with the Klebsiella pneumoniae nif gene cluster, failed to accumulate nitrogenase components [Govezensky et al. (1991) J. Bacteriol., 173, 6339-6346]. Transformation with sugE reversed the mutant phenotype. In wild type K.pneumoniae, transformation with sugE accelerated the rate of nitrogenase biogenesis after nif derepression. In E.coli, transformation with sugE enabled bacteriophage T4 growth in a groEL mutant. A continuous 178 codon open reading frame (ORF) in sugE encloses another, in-frame, 105 codon ORF similar to a predicted ORF in Proteus vulgaris. In vivo products of both sugE ORFs were observed in transformants expressing the gene from a T7 promoter. In non-transformed cells, a typical sigma 70-dependent promoter found upstream of the larger ORF directs sugE transcription during growth at 30 degrees C. At elevated temperatures or in stationary phase cells, another promoter, found within the coding sequence upstream of the smaller ORF, is activated independently of sigma 32. The results suggest that sugE encodes a chaperonin-related system whose composition might vary with temperature and growth phase.

Regulation and light-harvesting complex II association of a Dunaliella protein homologous to early light-induced proteins in higher plants

The unicellular green alga Dunaliella bardawil responds to high light, nutrient deprivation, and several other types of stress by massive accumulation of beta-carotene. We have previously cloned a nuclear gene, cbr, that is co-induced with accelerated carotenogenesis. The predicted product of cbr is closely related to early light-induced proteins (Elips) of higher plants, and also shows resemblance to chlorophyll a/b-binding proteins. In the present study, the determination of the cbr transcription start site supported the previously proposed site of translation initiation. Antibodies raised against a synthetic oligopeptide matching the predicted sequence of Cbr recognized two polypeptides of apparently 17 and 19 kDa that were induced in parallel to cbr transcript accumulation in highly illuminated or sulfate-starved D. bardawil cells. The antibodies also cross-reacted with an approximately 20-kDa polypeptide in sulfate-starved Dunaliella salina. In both D. bardawil and D. salina, Cbr was found exclusively in the thylakoid membranes. After mild solubilization, Cbr co-fractionated with light-harvesting complex II (LHCII) in sucrose gradient centrifugation and gel electrophoresis and was specifically associated with a minor LHCII complex. An occasionally observed, faster mobility Cbr form, free of LHCII, was probably released from the larger complex. These results support the conclusion that Cbr belongs to a class of stress-induced proteins transiently associated with antennae complexes.

Involvement of GroEL in nif gene regulation and nitrogenase assembly

Several approaches were used to study the role of GroEL, the prototype chaperonin, in the nitrogen fixation (nif) system. An Escherichia coli groEL mutant transformed with the Klebsiella pneumoniae nif gene cluster accumulated very low to nondetectable levels of nitrogenase components compared with the isogenic wild-type strain or the mutant cotransformed with the wild-type groE operon. In K. pneumoniae, overexpression of the E. coli groE operon markedly accelerated the rate of appearance of the MoFe protein and its constituent polypeptides after the start of derepression. The groEL mutation in E. coli decreased NifA-dependent beta-galactosidase expression from the nifH promoter but did not affect the constitutive expression of nifA from the tet promoter of ntr-controlled expression from the nifLA promoter. The possibility that GroEL is required for the correct folding of NifA was supported by coimmunoprecipitation of NifA with anti-GroEL antibodies. Kinetic analyses of nitrogenase assembly in 35S pulse-chased K. pneumoniae pointed to the existence of high-molecular-weight intermediates in MoFe protein assembly and demonstrated the transient binding of newly synthesized NifH and NifDK to GroEL. Overall, these results indicate that GroEL fulfills both regulatory and structural functions in the nif system.

Co-regulation of a gene homologous to early light-induced genes in higher plants and beta-carotene biosynthesis in the alga Dunaliella bardawil

Dunaliella bardawil, a unicellular green alga that can be induced to accumulate massive amounts of beta-carotene, is particularly suitable for studies of carotenogenesis regulation and its links to developmental and adaptive processes in the chloroplast. A cDNA clone corresponding to a transcript accumulating coordinately with carotenogenesis induction was isolated by differential hybridization of a cDNA library made from intensely illuminated cells. This transcript was also abundant in algal mutants able to accumulate beta-carotene under relatively low light intensity. DNA sequence analysis indicates that cbr (for carotene biosynthesis-related) is closely related to early light-induced genes (elip) of higher plants. Similarity also exists between repeated oligopeptide motifs in Cbr and Cab proteins of photosystems I and II. Three upstream direct repeats in cbr include an octamer and hexamer related to mammalian sterol regulatory elements. The relationship between cbr transcript and beta-carotene accumulation, the structural similarity between Cbr and Cab proteins, and the presence of potential SRE-1 elements lead us to propose that Cbr represents novel carotenoid binding proteins, whose synthesis might be coordinated with carotenogenic enzymes via an evolutionary conserved regulatory mechanism.

A 150 Kilodalton Cell Surface Protein Is Induced by Salt in the Halotolerant Green Alga Dunaliella salina

Dunaliella salina is an extremely halotolerant, unicellular, green alga lacking a rigid cell wall. Osmotic adaptation to high salinities is based on the accumulation of glycerol. To uncover other functions responsible for halotolerance, protein profiles of algae continuously grown in different salinities were compared. A 150 kilodalton protein (p 150) increased in amount with salt concentration. Furthermore, when the cells were subjected to drastic hyperosmotic shocks, p150 started to rise long after completion of the osmotic response but coincident with reinitiation of cell proliferation. Cells with an initially higher level of p150 resumed growth faster than cells with a lower level of the protein. Addition of cycloheximide early after hyperosmotic shock prevented the rise in p150, indicating this rise was due to de novo synthesis of the protein. These observations suggest that p150 is a saltinduced protein required for proliferation of the cells in saline media. p150 was purified to homogeneity and found to be a detergent-soluble glycoprotein. Polyclonal antibodies against p150 recognized a single protein component in D. salina crude extracts. A high M(r) cross-reacting protein was also observed in another Dunaliella strain, D. bardawil. Immunoelectron microscopy localized p150 to the cell surface.

Photoinduction of Massive beta-Carotene Accumulation by the Alga Dunaliella bardawil: Kinetics and Dependence on Gene Activation

The massive accumulation of beta-carotene by the halotolerant micro alga Dunaliella bardawil, in response to high light intensity and several other environmental factors, has been studied so far under different sets of fixed conditions. To determine the kinetics and characteristics of the induction of beta-carotene accumulation, cells continuously grown under white light of approximately 27 microeinsteins per square meter per second were exposed to light of approximately 1650 microeinsteins per square meter per second. The exposed cells accumulate beta-carotene in two stages: the first stage, lasting for 24 hours, starts shortly after exposure, whereas the second stage starts concomitantly with the onset of the stationary phase and persists until the cells collapse. Actinomycin D, chloramphenicol, or cycloheximide added to low-illuminated cultures abolish the subsequent induction of beta-carotene accumulation by high light intensity. These results, together with the early exponential kinetics of accumulation, point to the role of gene activation in the process. In vivo labeling of proteins and in vitro translation of poly(A)(+) mRNA revealed several pronounced differences between low-illuminated and high-illuminated cells. A strongly light-induced protein of approximately 55 kilodaltons, as well as other light-induced proteins could possibly fulfill a carotenogenic function.

Structure-function relationships in the alpha subunit of Klebsiella pneumoniae nitrogenase MoFe protein from analysis of nifD mutants

Crude extracts of wild-type, nitrogenase-derepressed Klebsiella pneumoniae fractionated by nondenaturing gel electrophoresis contain, in addition to the major form of the MoFe protein, two minor variants of lower electrophoretic mobility. Of seven Nif- mutants of K. pneumoniae with nonpolar point mutations in nifD (encoding the alpha subunit of Kp1), three exhibit a wild-type-like electrophoretic pattern, whereas in the remaining four, the slowest-migrating form becomes the predominant species. Amino acid substitutions in mutants of the first type are located in the N terminus of NifD and include Gly-85 to Arg (UN1661), Glu-121 to Lys (UN1649), and Gly-161 to Asp (UN1683). Mutations of the second type are Gly-186 to Asp (UN1648), Gly-195 to Glu (UN1680), Ser-443 to Pro (UN1793), and Gly-455 to Asp (UN1650). Six of the mutated residues show interspecies conservation, three are close to conserved cysteines, and two are located next to conserved histidines. Based on evidence pointing to the possibility that the lowest-mobility form lacks the iron-molybdenum cofactor, these results provide insights into the functional significance of specific sites in the alpha subunit of the MoFe protein.

Outreading promoters are located at both ends of the gamma-delta transposon

Two plasmids were isolated containing oppositely oriented gamma-delta insertions between the wild-type transcription initiation site of the nifHDKY operon and the nifH coding sequence. The nifHDKY promoter of Klebsiella pneumoniae, similar to other nitrogen fixation (nif) promoters, normally requires the products of ntrA and nifA for activity. Mutations that allowed constitutive expression of the nifHDKY operon were searched for by transforming a plasmid, containing the regulatory region of this operon followed by an in-frame nifH'-'lacZ fusion, into a Lac- Escherichia coli strain (which contains no nifA) and screening for Lac+ derivatives. The plasmids described here were isolated from such derivatives and directed the constitutive expression of beta-galactosidase. Deletion analysis indicated that gamma-delta promoters other than those transcribing tnpA and tnpR were involved in this expression. Nuclease S1 mapping revealed outward-reading transcription initiation sites in both the gamma end and the delta end of the transposon. Most interestingly, one initiation site on each end was located in corresponding positions within the terminal inverted repeats. The sites were in the center of the longest sequence, of 12 bp, contiguously conserved between the terminal inverted repeats of gamma-delta and the related transposon Tn3. In gamma-delta and Tn3, this sequence has been recently implicated in transposase binding. These results suggest a possible interrelationship between transcription from the "end" promoters and transposition.

Selection of in vivo deletions in Saccharomyces cerevisiae

A general screening procedure has been devised for the selection of in vivo-generated deletions in haploid Saccharomyces cerevisiae cells. It is based on the introduction into a cyh2 host (resistant to the drug cycloheximide) of a tandemly duplicated CYH2 gene (a dominant allele, conferring sensitivity to cycloheximide), and subsequent selection for Cyhr derivatives. The duplicated CYH2 gene has been introduced on CEN ARS plasmids or integrated into chromosome II. A variable but significant proportion of the Cyhr derivatives of such transformants were deletion mutants in which both CYH2 copies had suffered deletions. Some of the deletions extended into sequences outside the tandemly duplicated CYH2 gene. A total of 61 independently selected deletions ranged in length from 3.1 to over 20 kilobases and had no obvious preferred endpoints. Restriction analysis showed that other frequently isolated Cyhr derivatives appeared to retain one of the two CYH2 copies. Such single-copy derivatives of CEN ARS plasmids did not contain a functional CYH2 gene. The frequency of true deletions in CEN ARS plasmids, of approximately 10(-7) per viable cell, was comparable in RAD52 and rad52 strains. Chromosomal deletions, which occurred at a frequency of approximately 10(-8) per viable cell, were observed only in rad52 hosts. Derivatives exhibiting an additional altered phenotype, such as the inactivation of a neighboring gene or, less frequently, the transcriptional activation of a previously silent gene, were isolated by screening deletion mutants. These results show that the method described can be used for in vivo deletion mapping or for the generation of gene fusions.

Suppressors suaC109 and suaA101 of Aspergillus nidulans alter the ribosomal phenotype in vitro

A new homologous, cell-free system for protein synthesis has been devised for use with ribosomes and elongation factors from Aspergillus nidulans. Ribosome preparations from strains with either the suaA101 or suaC109 mutations have a higher misreading ratio (non-cognate:cognate amino acid incorporation) in the presence of hygromycin than controls. They can be classed as fidelity mutants. These results also prove that the mutations must be in genes coding for ribosomal proteins or enzymes which modify ribosomal proteins post-translationally. Alternatively, the genes could code for translation factors.

A quantitative approach to sequence comparisons of nitrogenase MoFe protein alpha- and beta-subunits including the newly sequenced nifK gene from Klebsiella pneumoniae

The nucleotide sequence was determined for part of the Klebsiella pneumoniae nif gene cluster containing the 3' end of the nifD gene and the entire length of the nifK gene (encoding the alpha- and beta-subunits of the nitrogenase MoFe protein respectively), as well as the putative start of the nifY gene, a gene of as yet unknown function. A broad-based comparison of a number of MoFe protein alpha-subunits, beta-subunits and alpha-versus beta-subunits was carried out by the use of a computer program that simultaneously aligns three protein sequences according to the mutation data matrix of Dayhoff. A new kind of quantitative statistical measure of the similarity between the aligned sequences was obtained by calculating and plotting standardized similarity scores for overlapping segments along the aligned proteins. This calculation determines if a test sequence is similar to the consensus sequence of two other proteins that are known to be related to each other. The different beta-subunits compared were found to be significantly similar along most of their sequence, with the exception of two relatively short regions centred around residues 225 and 300, which contain insertions/deletions. The overall pattern of similarity between different alpha-subunits exhibits resemblance to the overall pattern of similarity between different beta-subunits, including regions of low similarity centred around residues 225 and 340. Comparison of alpha-subunits with beta-subunits showed that a region of significant similarity between the two types of subunits was located approximately between residues 120 and 180 in both subunits, but other parts of the proteins were only marginally similar. These results provide insights into likely tertiary structural features of the MoFe protein subunits.

Nitrogenase MoFe protein subunits from Klebsiella pneumoniae expressed in foreign hosts. Characteristics and interactions

The expression of selected nitrogen fixation (nif) genes from Klebsiella pneumoniae in foreign hosts provides an approach to determine the pathway, minimal genetic requirements, and host dependence of nitrogenase assembly. In this study, we investigated the assembly of the alpha 2 beta 2 MoFe protein, responsible for substrate binding and reduction, by introducing nifD and nifK (encoding respectively, the alpha and beta subunits) into Escherichia coli and the yeast Saccharomyces cerevisiae. In E. coli, both genes were expressed from the nifHDKY operon; in yeast, the genes, separately fused to the yeast ADH1 promoter, were introduced on two different plasmids. Denaturing immunoblot analyses demonstrated the presence of significant amounts of NifD and NifK in both hosts. In E. coli, the level or perhaps modification of NifD depended on the growth medium of the bacteria. Nondenaturing, anaerobic immunoblot assays revealed in E. coli, nif-specific antigens of lower electrophoretic mobility than Kp1, which may represent assembly intermediates. In yeast, no putative assembled products were evident, and the predominant antigens corresponded to the monomeric forms of the polypeptides. These results indicate that, unlike NifH, the Fe protein subunit (Berman, J., Gershoni, J. M., and Zamir, A. (1985) J. Biol. Chem. 260, 5240-5243), NifD and NifK are insufficient for the assembly of an electrophoretically Kp1-like structure. Homodimerization of nifK and probably of nifD primary gene products does not appear to occur spontaneously and hence is unlikely to represent the initial step in the assembly. The difference between the two hosts suggests that the cellular environment or mode of expression could affect the interaction between the two subunits.

Spontaneous amplification of yeast CEN ARS plasmids

Transformation of Saccharomyces cerevisiae with several yeast CEN4 ARS1 plasmids containing the his3-delta 4 allele (as well as the URA3 and TRP1 markers) yielded His+ transformants at 0.1%-50% the frequency of Ura+ Trp+ transformants. Additional His+ derivatives arose on continuous growth of transformants originally scored as His- Ura+ Trp+. In all cases, the His+ phenotype was not due to plasmid or host mutations but invariably correlated with an up to 12-fold increase in plasmid copy number. On removal of selective pressure, the His+ phenotype was lost more readily than the Ura+ Trp+ markers, with a corresponding decrease in plasmid copy number. Also, the amplification did not decrease the mitotic loss rate of the Ura+ Trp+ markers. These results indicate that CEN ARS plasmids can be spontaneously amplified to higher levels than previously observed. However, when amplified, apparently not all copies exhibit the characteristic stability of CEN ARS plasmids.

Sequence rearrangements may alter the in vivo superhelicity of recombinant plasmids

Electrophoretic resolution of topoisomers was used to compare the in vivo superhelicity of recombinant plasmids containing a fragment of cDNA for an immunoglobulin light chain, cloned in the two possible orientations into the BamHI site of pBR313 or pBR322. Previously, frequent transpositions of IS1 or IS5 were observed into the sequence upstream to the cloned fragment in recombinants in one orientation [(+) plasmids] but not in recombinants in the opposite, (-) orientation [(1982) Nucleic Acids Res. 10, 4525-4542]. The results of the present analyses show that, on average, (-) plasmids are less negatively supercoiled than (+) plasmids, or pBR322. These results suggest that primary sequence rearrangements in plasmids could affect their in vivo topological state, and consequently, perhaps, their effectiveness as recipients of transposable elements.

Transcriptional analysis of promoter mutations in the Klebsiella pneumoniae nifHDKY operon

Previously isolated promoter mutations that allow expression of the Klebsiella pneumoniae nifHDKY operon in the absence of nifA (R. Bitoun, J. Berman, A. Zilberstein, D. Holland, J.B. Cohen, D. Givol, and A. Zamir, Proc. Natl. Acad. Sci. USA, 80:5812-5816, 1983) were further characterized. pRB1 and pRB5, containing, respectively, point and duplication mutations in the nifHDKY regulatory region, were transformed into Escherichia coli and K. pneumoniae hosts with different nifA and ntrA backgrounds. nif transcription start sites were determined by nuclease S1 mapping. The results indicated that nifA-independent expression from both mutants did not require ntrA. Transcription from pBR5 started 3 base pairs (bp) upstream of the start site of nif-regulated transcription and could stem from a canonical promoter sequence generated at the junction between the two copies of the duplicated sequence. In the presence of nifA-ntrA, transcription from pRB5 started predominantly at the site characteristic of the nif-regulated promoter. The site of constitutive transcription initiation in pRB1 was located 33 bp upstream of the point mutation and 40 bp upstream of the start of nifA-ntrA-activated transcription. Low-level transcription from the upstream site was also evident, in the absence of nifA or nifA or both, with the plasmid containing the wild-type nifHDKY regulatory region. However, when nifA and ntrA were present to activate transcription from the major nif promoter, no activity was evident from the upstream site in either pRB1 or the parental plasmid. Thus, the mutation enhanced the activity of a pre-existing constitutive promoter, the activity of which was repressed on nifA-ntrA activation of the major nif promoter.

Priming immunization against cholera toxin and E. coli heat-labile toxin by a cholera toxin short peptide-beta-galactosidase hybrid synthesized in E. coli

A synthetic oligodeoxynucleotide encoding for a small peptide was employed for the expression of this peptide in a form suitable for immunization. The encoded peptide, namely, the region 50-64 of the B subunit of cholera toxin (CTP3), had previously been identified as a relevant epitope of cholera toxin. Thus, multiple immunizations with its conjugate to a protein carrier led to an efficient neutralizing response against native cholera toxin. Immunization with the resulting fusion protein of CTP3 and beta-galactosidase, followed by a booster injection of a sub-immunizing amount (1 microgram) of cholera toxin, led to a substantial level of neutralizing antibodies against both cholera toxin and the heat-labile toxin of Escherichia coli.

Expression of nitrogen fixation genes in foreign hosts. Assembly of nitrogenase Fe protein in Escherichia coli and in yeast

In Klebsiella pneumoniae, the nifH gene encodes the Fe protein (Kp2) polypeptide that is assembled into a homodimer responsible for the reduction of nitrogenase. Escherichia coli or the yeast Saccharomyces cerevisiae, transformed with the K. pneumoniae nifH gene in suitable expression vectors, synthesize the Fe protein polypeptide. This study examines the assembly of the nifH gene product into its characteristic dimeric structure in E. coli and in yeast. Immunoblotting methods, as well as 55Fe2- labeling of K. pneumoniae were employed to detect native nitrogenase components in cell lysates. E. coli and yeast transformants contained a protein similar to native Kp2 in its immunoreactivity, apparent molecular weight, and lability in the presence of oxygen or MgATP. While in E. coli the co-introduction of nifH and nifM resulted in enhanced levels of the nifH product, it appears that the nifH gene product alone is sufficient for the assembly of an Fe protein-like structure in foreign prokaryotic and eukaryotic hosts.

Expression of a nitrogen-fixation gene encoding a nitrogenase subunit in yeast

Biological nitrogen fixation is catalyzed by nitrogenase, an enzyme complex exclusive to prokaryotes. We used the yeast Saccharomyces cerevisiae to study the synthesis, and subsequently the assembly, of nitrogenase components in a eukaryote. Here, the Klebsiella pneumoniae nifH gene, encoding the subunit of the Fe protein (Kp2) component of nitrogenase, was expressed in S. cerevisiae from the yeast ADHI promoter. The nifH gene product, detected in yeast by immunoblot analysis with anti-Kp2 antibodies, exhibited the same electrophoretic mobility in SDS-polyacrylamide gels as that of the Kp2 subunit synthesized in K. pneumoniae. Estimates of Kp2 antigen and assays of beta-galactosidase activity specified by nifH'-'lacZ fusions showed that the level of nifH product was similar in anaerobically and aerobically grown yeast, but varied with different transforming plasmids and in various haploid and diploid yeast strains. A cistron located downstream to nifH in a transcript resembling the polycistronic mRNA of the nifHDKY operon in K. pneumoniae is not translated in yeast.

Secretion and processing of an immunoglobulin light chain in Escherichia coli

When a cDNA coding for the kappa light chain (L-321) from the mouse MOPC321 myeloma was cloned into Escherichia coli, L-321 antigens were found in both cytoplasmic and periplasmic fractions. In cells synthesizing the intact chain, starting with its signal peptide, the periplasm contained a mature-size immunoglobulin indicating that the eukaryotic signal peptide can initiate secretion and be processed. When the entire cDNA for L-321 (including its signal peptide) was inserted in the gene for bacterial beta-lactamase, processing cleaved only the first bacterial signal sequence of the hybrid protein synthesized. Removal of the beta-lactamase signal peptide was also observed with another beta-lactamase-L-321 hybrid which did not include the immunoglobulin signal peptide and the adjacent part of the variable region. The two hybrid proteins may, however, differ in their mode of secretion.

Promoter mutations that allow nifA-independent expression of the nitrogen fixation nifHDKY operon

The nifHDKY operon of Klebsiella pneumoniae encodes for structural polypeptides of nitrogenase and requires the nifA gene product for transcription. Mutations that allow transcription of the nifHDKY operon in absence of the nifA gene product were characterized in plasmids containing the regulatory region of nifHDKY and nifH fused in phase to lacZ. beta-Galactosidase activity served as a measure for nifH expression. Most mutations were located in the nif regulatory region and included insertion sequence 2 (IS2) insertions, a sequence duplication, and a base substitution. In Escherichia coli, beta-galactosidase activity expressed from the mutant plasmids in the absence of nifA was 6-30% of the nifA-activated, parental level. Expression from most mutant plasmids was further increased by nifA. In K. pneumoniae, IS2-containing plasmids expressed low levels of beta-galactosidase and responded poorly, if at all, to activation by nifA, whereas expression from other mutant types was similar to that observed in E. coli. Nucleotide sequence analysis of two mutants indicated that sequences within 41 base pairs upstream to the nifH coding sequence were involved in nif-specific regulation. The results suggest that an inverted repeat element in this region, which could theoretically form a cruciform structure in the DNA, is involved in the transcriptional control of the nifHDKY operon.

Insertion of nonhomologous DNA into the yeast genome mediated by homologous recombination with a cotransforming plasmid

Bacterial plasmids containing no detectable homology with yeast DNA sequences were inserted into the yeast genome by cotransforming with a plasmid containing a yeast gene. Analysis of the yeast transformants confirmed that recombination events occurred between the prokaryotic sequences shared by the two plasmids and between the yeast sequences common to the cotransforming plasmid and to the genome. Multiple copies of the two plasmids, in both tandem and interspersed arrays, are inserted by this method. Populations of cells grown from individual transformants are heterogeneous for the number of integrated sequences. The number of integrated bacterial sequences is greatly reduced after 100 generations of growth in the populations that initially contained large numbers of sequences, while it is stable in those populations that initially contained either a single or a small number of copies.