Polymorphism of the Hereditary Sigma Virus in Natural Populations of DROSOPHILA MELANOGASTER

Previous studies have shown that, in natural French populations of Drosophila melanogaster, 10 to 20% of the flies are infected by the noncontagious, hereditary rhabdovirus sigma responsible for CO₂ sensitivity. These populations are also polymorphic for two alleles [ref(2)P^o and ref(2)P^p] of a gene for resistance to the sigma virus. Evidence is given here that two viral genetic types, differing in their response to the ref(2)P^p allele, are present in these populations of flies; the most common type is only slightly sensitive to the ref(2)P^p allele.     

Location of the LSP-1 Genes in Drosophila Species by IN SITU Hybridization

The locations of the larval serum protein one (LSP-1) α, β and γ genes were determined in Drosophila melanogaster and in 14 other species of Drosophila by in situ hybridization to polytene chromosomes. The LSP-1 α gene mapped to bands 11B on the X chromosome, the LSP-1 β gene mapped to bands 21D-E on chromosome 2L, and the LSP-1 γ gene mapped to band 61A in all the melanogaster subgroup species. In eight other species, both the LSP-1 α and β genes mapped to one site on Muller's element E which corresponds to chromosome 3R of D. melanogaster. No hybridization of LSP-1 γ was detected in these eight species. Restriction enzyme digestion and analysis of genomic DNA by filter transfer hybridization confirmed the presence of LSP-1 α-like and β-like genes in seven of these species. These results are discussed with respect to conservation of the chromosomal elements in the genus Drosophila.     

Association of Chromosome and Enzyme Polymorphisms in Natural and Cage Populations of DROSOPHILA MELANOGASTER

The frequencies of a polymorphic inversion, In(2L)t, and of Adh and αGpdh alleles were analyzed in three natural populations of Drosophila melanogaster from Japan. Significant positive correlations between the frequencies of In(2L)t and Adh^S or αGpdh^F were detected due to tight linkage. An analysis of correlation with latitude showed that the negative cline of Adh^S frequency could be explained entirely by its linkage with In(2L)t; the frequency of Adh^S on the standard chromosome did not show a latitudinal cline. To the contrary, the cline of αGpdh^F frequency itself was positive, and its linkage with In(2L)t makes the positive cline unclear. These results suggest that the two allozymes themselves respond to latitudinal natural selection in different ways. When these populations were transferred to laboratory cages and maintained for a long time, they lost the chromosomal polymorphism but retained stable enzyme polymorphisms, although allele frequencies in the cage were not the same as in nature. The frequencies of Adh and αGpdh alleles were close to those in earlier cage populations of the same geographical origin.     

Genic Variation in Male Haploids under Deterministic Selection

Genic variation in male haploids and male diploids was compared assuming constant fitnesses (derived from computer-generated random numbers) and infinite population size. Several models were studied, differing by the fitness correlation between the sexes (r_s) and genotypes (r_g), and by the intensity of selection as measured by the coefficient of variation (CV) of the fitness distribution. Genic variation was quantified using the proportion of polymorphic loci, P, the gene diversity at polymorphic loci, H_p, and the gene diversity over all loci, H_a. The two genetic systems were compared via variation ratios: variation in male haploidy/variation in male diploidy.—P and H_a were markedly lower for male-haploids than for male diploids, the variation ratios declining with increasing r_s, r_g and CV, but the two genetic systems were similar for H_p. Except for male diploids with r_s = 1, the two sexes had different equilibrium gene frequencies but the sample sizes required to detect such differences reliably were larger than usually possible in surveys of natural populations.—Data from natural populations fit the above trends qualitatively, but the variation ratios are much lower than those from our analyses, except that for H_p, which is higher when Drosophila is excluded. Also, the frequency distribution of most common alleles from electrophoretic data has a deficiency of intermediate frequencies compared to that from the computer-generated sets of fitnesses, possibly reflecting either the influence of stochastic processes shifting frequencies away from equilibrium or the involvement of alleles under selection-mutation balance.——While electrophoretic data suggest that Drosophila has unusually high levels of genic variation, unusually low levels of genic variation in male haploids compared with male diploids are not strongly indicated. However, if further data confirm male haploids as having low levels of genic variation, likely explanations are that the bulk of electrophoretically detected variation involves fixed-fitness balancing selection, selection-mutation balance involving slightly deleterious recessive alleles, new favorable male haploid alleles moving more rapidly to fixation than under male diploidy and thus carrying linked loci to fixation faster, or some combination of these possible factors.     

The Apolipoprotein E/CI/CII Gene Cluster and Late-Onset Alzheimer Disease

The chromosome 19 apolipoprotein E/CI/CII gene cluster was examined for evidence of linkage to a familial Alzheimer disease (FAD) locus. The family groups studied were Volga German (VG), early-onset non-VG (ENVG; mean age at onset <60 years), and late-onset families. A genetic association was observed between apolipoprotein E (ApoE) allele ε4 and FAD in late-onset families; the ε4 allele frequency was .51 in affected subjects, .37 in at-risk subjects, .11 in spouses, and .19 in unrelated controls. The differences between the ε4 frequencies in affected subjects versus controls and in at-risk subjects versus controls were highly significant (standard normal deviate [Z_SND]) = 7.37, P < 10⁻⁹; and Z_SND = 4.07, P < .00005, respectively). No association between the ε4 allele and FAD was observed in the ENVG or VG groups. A statistically significant allelic association between ε4 and AD was also observed in a group of unrelated subjects; the ε4 frequency was .26 in affected subjects, versus .19 in controls (Z_SND = 2.20, P < .03). Evidence of linkage of ApoE and ApoCII to FAD was examined by maximum-likelihood methods, using three models and assuming autosomal dominant inheritance: (1) age-dependent penetrance, (2) extremely low (1%) penetrance, and (3) age-dependent penetrance corrected for sporadic Alzheimer disease (AD). For ApoCII in late-onset families, results for close linkage were negative, and only small positive lod-score-statistic (Z) values were obtained (model 1, maximum Z [Z_max] = 0.61, recombination fraction [θ] = .30; model 2, Z_max = 0.47, θ = .20). For ApoE in late-onset kindreds, positive Z values were obtained when either allele frequencies from controls (model 1, Z_max = 2.02, θ = .15; model 2, Z_max = 3.42, θ = .05) or allele frequencies from the families (model 1, Z_max = 1.43, θ = .15; model 2, Z_max = 1.70, θ = .05) were used. When linkage disequilibrium was incorporated into the analysis, the Z values increased (model 1, Z_max = 3.17, θ = .23; model 3, Z_max = 1.85, θ = .20). For the ENVG group, results for ApoE and ApoCII were uniformly negative. Affected-pedigree-member analysis gave significant results for the late-onset kindreds, for ApoE (Z_SND = 3.003, P = .003) and ApoCII (Z_SND = 2.319, P = .016), when control allele frequencies were used but not when allele frequencies were derived from the families.     

The Structure of the Karrikin-Insensitive Protein (KAI2) in Arabidopsis thaliana

KARRIKIN INSENSITIVE 2 (KAI2) is an α/β hydrolase involved in seed germination and seedling development. It is essential for plant responses to karrikins, a class of butenolide compounds derived from burnt plant material that are structurally similar to strigolactone plant hormones. The mechanistic basis for the function of KAI2 in plant development remains unclear. We have determined the crystal structure of Arabidopsis thaliana KAI2 in space groups P2₁ 2₁ 2₁ (a  = 63.57 Å, b  = 66.26 Å, c  = 78.25 Å) and P2₁ (a  = 50.20 Å, b  = 56.04 Å, c  = 52.43 Å, β  = 116.12°) to 1.55 and 2.11 Å respectively. The catalytic residues are positioned within a large hydrophobic pocket similar to that of DAD2, a protein required for strigolactone response in Petunia hybrida. KAI2 possesses a second solvent-accessible pocket, adjacent to the active site cavity, which offers the possibility of allosteric regulation. The structure of KAI2 is consistent with its designation as a serine hydrolase, as well as previous data implicating the protein in karrikin and strigolactone signalling.     

Studies of Root Function in Zea mays: III. Xylem Sap Composition at Maximum Root Pressure Provides Evidence of Active Transport into the Xylem and a Measurement of the Reflection Coefficient of the Root

The cut ends of excised Zea mays roots were sealed to a pressure transducer and their root pressures recorded. These rose approximately hyperbolically to a maximum value of 4.21 ± 0.34 bar after 30 to 40 minutes. Xylem exudate could not be collected at this pressure since the flow rate was zero. Samples of exudate were collected at lower applied pressures (ΔP), however, and Δπ, the osmotic pressure difference between them and the solution bathing the root, was measured by freezing point depression. A plot of ΔP/Δπ against J_v/Δπ, where J_v is the volume flux, proved to be a straight line whose intercept, equal to σ, the reflection coefficient, was 0.853 ± 0.016. The maximum xylem concentrations of various chemical species were found by a similar extrapolative method and compared with those in the cell sap. This indicated that (a) Ca²⁺, Mg²⁺, NO₃²⁻, SO₄²⁻, and most amino acids move from the cells to the xylem down an electrochemical potential gradient; (b) relative to these ions H⁺, NH₄⁺, glutamine and asparagine are actively transported into the xylem; and (c) H₂PO₄⁻, and K⁺ are actively retained in the symplasm.     

Genetic Analysis of Natural Populations of DROSOPHILA MELANOGASTER in Japan. III. Genetic Variability of Inducing Factors of Amylase and Fitness

"Inducibility" of amylase in Drosophila melanogaster was defined and investigated in a natural population from Japan. Inducibility represents the effects of factors remote from the structural gene that control the amount of enzyme produced. Inducibility of an isogenic line is measured as the ratio of the enzyme's specific activity in two different inducing environments. There was considerable genetic variability with respect to inducibility of amylase in 44 isogenic lines derived from a natural population of D. melanogaster . Net fitness and its components in these isogenic lines were also measured. The results indicated that, although the inducibility of the enzyme was positively correlated with the net fitness (r_g = 0.63 ± 0.2), the enzyme activities in the normal medium were not (r_g = 0.12 ± 0.37). The analysis of the data shows that the differences in inducing factors are mainly responsible for the differences in the fitness of lines and are the genetic materials for the adaptive evolution of organisms.     

Self-Subunit Swapping Occurs in Another Gene Type of Cobalt Nitrile Hydratase

Self-subunit swapping is one of the post-translational maturation of the cobalt-containing nitrile hydratase (Co-NHase) family of enzymes. All of these NHases possess a gene organization of <β-subunit> <α-subunit> <activator protein>, which allows the activator protein to easily form a mediatory complex with the α-subunit of the NHase after translation. Here, we discovered that the incorporation of cobalt into another type of Co-NHase, with a gene organization of <α-subunit> <β-subunit> <activator protein>, was also dependent on self-subunit swapping. We successfully isolated a recombinant NHase activator protein (P14K) of Pseudomonas putida NRRL-18668 by adding a Strep-tag N-terminal to the P14K gene. P14K was found to form a complex [α(StrepP14K)₂] with the α-subunit of the NHase. The incorporation of cobalt into the NHase of P. putida was confirmed to be dependent on the α-subunit substitution between the cobalt-containing α(StrepP14K)₂ and the cobalt-free NHase. Cobalt was inserted into cobalt-free α(StrepP14K)₂ but not into cobalt-free NHase, suggesting that P14K functions not only as a self-subunit swapping chaperone but also as a metallochaperone. In addition, NHase from P. putida was also expressed by a mutant gene that was designed with a <β-subunit> <α-subunit> <P14K> order. Our findings expand the general features of self-subunit swapping maturation.     

Stomatal Behavior and Water Status of Maize, Sorghum, and Tobacco under Field Conditions: II. At Low Soil Water Potential

Diurnal changes in the vertical profiles of irradiance incident upon the adaxial leaf surface (I), leaf resistance (r₁), leaf water potential (ψ), osmotic potential (π), and turgor potential (P) were followed concurrently in crops of maize (Zea mays L. cv. Pa602A), sorghum (Sorghum bicolor [L.] Moench cv. RS 610), and tobacco (Nicotiana tabacum L. cv. Havanna Seed 211) on several days in 1968 to 1970 when soil water potentials were low. The r₁, measured with a ventilated diffusion porometer, of the leaves in the upper canopy decreased temporarily after sunrise [~0530 hours Eastern Standard Time] as I increased, but then r₁ increased again between 0700 and 0830 hr Eastern Standard Time as the ψ, measured with a pressure chamber, decreased rapidly from the values of −7, −4 and −6 bars at sunrise to minimal values of −18, −22 and −15 bars near midday in the maize, sorghum, and tobacco, respectively. The π, measured with a vapor pressure osmometer, also decreased after sunrise, but not to the same degree as the decrease in ψ, so that a P of zero was reached in some leaves between 0730 and 0800 hours. The lower (more negative) π of leaves in the upper canopy than those in the lower canopy gave the upper leaves a higher P at a given ψ than the lower leaves in all three species; leaves at intermediate heights had an intermediate P. This difference between leaves at the three heights in the canopy was maintained at all values of ψ. The r₁ remained unchanged over a wide range of P and then increased markedly at a P of 2 bars in maize, −1 bar in sorghum, and near zero P in tobacco: r₁ also remained constant until ψ decreased to −17, −20, and −13 bars in leaves at intermediate heights in maize, sorghum, and tobacco, respectively. In all three species r₁ of leaves in the upper canopy increased at more negative values of ψ than those at the base of the canopy, and in tobacco, leaves in the upper canopy wilted at more negative values of ψ than those in the lower canopy.     

Kinetic diversity of single-channel burst openings underlying persistent Na(+) current in entorhinal cortex neurons

The kinetic diversity of burst openings responsible for the persistent Na⁺ current (I_NaP) in entorhinal cortex neurons was examined by separately analyzing single bursts. Although remarkable kinetic variability was observed among bursts in terms of intraburst opening probability and mean open and closed times, the values of time constants describing intraburst open times (τ_o(b)s) and closed times (τ_c(b)s) were distributed around well-defined peaks. At −40 mV, τ_o(b) peaks were found at ~0.34 (τ_o(b)1) and 0.77 (τ_o(b)2) ms, and major τ_c(b) peaks were found at ~0.24 (τ_c(b)1) and 0.54 (τ_c(b)2) ms. In ~80% of the bursts two preferential gating modes were found that consisted of a combination of either τ_o(b)1 and τ_c(b)2 (“intraburst mode 1”), or τ_o(b)2 and τ_c(b)1 (“intraburst mode 2”). Individual channels could switch between different gating modalities, but normally tended to maintain a specific gating mode for long periods. Mean burst duration also displayed considerable variability. At least three time constants were found to describe burst duration, and the frequencies at which each of the corresponding “bursting states” occurred varied in different channels. Short-lasting bursting states were preferentially associated with intraburst mode 1, whereas very-long-lasting bursts tended to gate according to mode 2 only or other modes that included considerably longer mean open times. These results show that I_NaP channels can generate multiple intraburst open and closed states and bursting states, but these different kinetic states tend to combine in definite ways to produce a limited number of prevalent, well-defined gating modalities. Modulation of distinct gating modalities in individual Na⁺ channels may be a powerful form of plasticity to influence neuronal excitability and function.     

A Cytogenetic Analysis of the Chromosomal Region Surrounding the α-Glycerophosphate Dehydrogenase Locus of DROSOPHILA MELANOGASTER

The chromosomal region surrounding the structural gene for α-glycerophosphate dehydrogenase (αGpdh, 2-20.5) of Drosophila melanogaster has been studied in detail. Forty-three EMS-induced recessive lethal mutations and five previously identified visible mutations have been localized within the 25A-27D region of chromosome 2 by deficiency mapping and in some cases by a recombination analysis. The 43 lethal mutations specify 17 lethal loci. αGpdh has been localized to a single polytene chromosome band, 25F5, and there apparently are no lethals that map to the αGpdh locus.     

RNA Interference against Platelet-Derived Growth Factor Receptor α mRNA Inhibits Fibroblast Transdifferentiation in Skin Lesions of Patients with Systemic Sclerosis

Objective

To down-regulate expression of mRNA for the platelet-derived growth factor receptor (PDGFR)-α, block the signalling pathway of PDGF and its receptor, and study their influence on fibroblast transdifferentiation to myofibroblasts in systemic sclerosis (SSc).

Methods

Fibroblasts from skin lesions of SSc patients and health adult controls were cultured in vitro, and α-smooth muscle actin (α-SMA) expression was determined by immunocytochemistry. Both groups of fibroblasts were stimulated with PDGF-AA, transforming growth factor β₁ (TGF-β₁), and costimulated with PDGF-AA and TGF-β₁, then PDGFR-α and α-SMA mRNA and protein expression were detected with RT-PCR and WB respectively. Three pairs of siRNAs targeting different PDGFR-α mRNA sequences were synthesized for RNAi. SSc and control fibroblasts were transfected with PDGFR-α siRNA; stimulated with PDGF-AA; and assessed for PDGFR-α and α-SMA mRNA and protein expression.

Results

Although the fibroblasts from both groups had similar morphology, the SSc skin lesions had significantly more myofibroblasts than control skin lesions. PDGF-AA stimulation, TGF-β₁ stimulation, and costimulation significantly up-regulated PDGFR-α and α-SMA mRNA and protein expression in SSc fibroblasts compared to control (P<0.05), and costimulation had the strongest effects (P<0.05). All three pairs of siRNAs suppressed PDGFR-α mRNA and protein expression (P<0.05), but siRNA₁₄₉₅ had the highest gene-silencing efficiency (P<0.05). PDGFR-α siRNA attenuated the effects of PDGF-AA through up-regulating PDGFR-α and α-SMA mRNA and protein expression and inhibiting fibroblast transdifferentiation to myofibroblasts in SSc (P<0.05).

Conclusions

PDGFR-α over-expression in SSc fibroblasts bound PDGF-AA more efficiently and promoted fibroblast transdifferentiation, which was enhanced by TGF-β₁. PDGFR-α siRNA down-regulated PDGFR-α expression, blocked binding to PDGF-AA, and inhibited fibroblast transdifferentiation to myofibroblasts.     

gammaTub23C interacts genetically with brahma chromatin-remodeling complexes in Drosophila melanogaster

The brahma gene encodes the catalytic subunit of the Drosophila melanogaster BRM chromatin-remodeling complexes. Screening for mutations that interact with brahma, we isolated the dominant-negative Pearl-2 allele of γTub23C. γTub23C encodes one of the two γ-tubulin isoforms in Drosophila and is essential for zygotic viability and normal adult patterning. γ-Tubulin is a subunit of microtubule organizer complexes. We show that mutations in lethal (1) discs degenerate 4, which encodes the Grip91 subunit of microtubule organizer complexes, suppress the recessive lethality and the imaginal phenotypes caused by γTub23C mutations. The genetic interactions between γTub23C and chromatin-remodeling mutations suggest that γ-tubulin might have a role in regulating gene expression.     

Stomatal Behavior and Water Status of Maize, Sorghum, and Tobacco under Field Conditions: I. At High Soil Water Potential

Diurnal changes in the vertical profiles of irradiance incident upon the adaxial leaf surface (I), stomatal resistance (r_s), leaf water potential (ψ), osmotic potential (π), and turgor potential (P) were followed concurrently in crops of maize (Zea mays L. var. Pa 602A), sorghum (Sorghum bicolor [L.] Moench var. RS610), and tobacco (Nicotiana tabacum L. var. Havanna Seed 211) on several days in 1968 to 1970 when soil water potentials were high. In all three crops the r_s, measured with a ventilated diffusion porometer, the ψ, measured with the pressure chamber, the π, measured with a vapor pressure osmometer, and the calculated P, decreased from sunrise to reach minimum values near midday and then increased again in the afternoon. The diurnal range of all the variables was greater for leaves in the upper canopy than for those in the lower canopy. P was observed to decrease with decreasing ψ, but never became zero. Sorghum had a higher P at a ψ of, say −10 bars, than did maize, and maize had a higher P than tobacco at the same ψ. Moreover, at the same ψ the upper leaves in all canopies had a higher P than the lower leaves. When compared at high irradiances, r_s did not increase as ψ declined to −13, −15, and −10 bars or as P declined to 0.3, 3.5, and 1.2 bars in maize, sorghum, and tobacco, respectively. The relation between r_s and I in the upper, nonsenescent leaves of all three crops fits a hyperbolic curve, but the response varied with species and leaf senescence. The adaxial and abaxial epidermises had the same response of r_s to I in maize and sorghum, whereas in tobacco the adaxial epidermis had a higher r_s than the abaxial epidermis at all values of I. At equal values of I, tobacco had the lowest leaf resistance (r_l) and maize had the highest r_l. Senescent maize leaves had nonfunctional stomata, whereas the lowermost sorghum leaves had higher stomatal resistances on average than the other leaves.     

L-Type Ca2+ Channel Sparklets Revealed by TIRF Microscopy in Mouse Urinary Bladder Smooth Muscle

Calcium is a ubiquitous second messenger in urinary bladder smooth muscle (UBSM). In this study, small discrete elevations of intracellular Ca²⁺, referred to as Ca²⁺ sparklets have been detected in an intact detrusor smooth muscle electrical syncytium using a TIRF microscopy Ca²⁺ imaging approach. Sparklets were virtually abolished by the removal of extracellular Ca²⁺ (0.035±0.01 vs. 0.23±0.07 Hz/mm²; P<0.05). Co-loading of smooth muscle strips with the slow Ca²⁺ chelator EGTA-AM (10 mM) confirmed that Ca²⁺ sparklets are restricted to the cell membrane. Ca²⁺ sparklets were inhibited by the calcium channel inhibitors R-(+)-Bay K 8644 (1 μM) (0.034±0.02 vs. 0.21±0.08 Hz/mm²; P<0.05), and diltiazem (10 μM) (0.097±0.04 vs. 0.16±0.06 Hz/mm²; P<0.05). Ca²⁺ sparklets were unaffected by inhibition of P2X₁ receptors α,β-meATP (10 μM) whilst sparklet frequencies were significantly reduced by atropine (1 μM). Ca²⁺ sparklet frequency was significantly reduced by PKC inhibition with Gö6976 (100 nM) (0.030±0.01 vs. 0.30±0.1 Hz/mm²; P<0.05), demonstrating that Ca²⁺ sparklets are PKC dependant. In the presence of CPA (10 μM), there was no apparent change in the overall frequency of Ca²⁺ sparklets, although the sparklet frequencies of each UBSM became statistically independent of each other (Spearman''s rank correlation 0.2, P>0.05), implying that Ca²⁺ store mediated signals regulate Ca²⁺ sparklets. Under control conditions, inhibition of store operated Ca²⁺ entry using ML-9 (100 μM) had no significant effect. Amplitudes of Ca²⁺ sparklets were unaffected by any agonists or antagonists, suggesting that these signals are quantal events arising from activation of a single channel, or complex of channels. The effects of CPA and ML-9 suggest that Ca²⁺ sparklets regulate events in the cell membrane, and contribute to cytosolic and sarcoplasmic Ca²⁺ concentrations.     

Successional Development of Sulfate-Reducing Bacterial Populations and Their Activities in a Wastewater Biofilm Growing under Microaerophilic Conditions

A combination of fluorescence in situ hybridization, microprofiles, denaturing gradient gel electrophoresis of PCR-amplified 16S ribosomal DNA fragments, and 16S rRNA gene cloning analysis was applied to investigate successional development of sulfate-reducing bacteria (SRB) community structure and in situ sulfide production activity within a biofilm growing under microaerophilic conditions (dissolved oxygen concentration in the bulk liquid was in the range of 0 to 100 μM) and in the presence of nitrate. Microelectrode measurements showed that oxygen penetrated 200 μm from the surface during all stages of biofilm development. The first sulfide production of 0.32 μmol of H₂S m⁻² s⁻¹ was detected below ca. 500 μm in the 3rd week and then gradually increased to 0.70 μmol H₂S m⁻² s⁻¹ in the 8th week. The most active sulfide production zone moved upward to the oxic-anoxic interface and intensified with time. This result coincided with an increase in SRB populations in the surface layer of the biofilm. The numbers of the probe SRB385- and 660-hybridized SRB populations significantly increased to 7.9 × 10⁹ cells cm⁻³ and 3.6 × 10⁹ cells cm⁻³, respectively, in the surface 400 μm during an 8-week cultivation, while those populations were relatively unchanged in the deeper part of the biofilm, probably due to substrate transport limitation. Based on 16S rRNA gene cloning analysis data, clone sequences that related to Desulfomicrobium hypogeium (99% sequence similarity) and Desulfobulbus elongatus (95% sequence similarity) were most frequently found. Different molecular analyses confirmed that Desulfobulbus, Desulfovibrio, and Desulfomicrobium were found to be the numerically important members of SRB in this wastewater biofilm.     

Stereochemical Control in the Still-Wittig Rearrangement Synthesis of Cyclohexyl (Z)-Alkene Inhibitors of Pin1

Three stereoisomeric inhibitors of Pin1: (2R,5S)-, (2S,5R)- and (2S,5S)-Ac–pSer–Ψ[(Z)CH = C]–pipecolyl(Pip)–2-(2-naphthyl)ethylamine 1, that mimic L-pSer–D-Pro, D-pSer–L-Pro, and D-pSer–D-Pro amides respectively, were synthesized by a 13-step route. The newly formed stereogenic centers in the pipecolyl ring were introduced by Luche reduction, followed by stereospecific [2,3]-Still-Wittig rearrangement. The (Z)- to (E)-alkene ratio in the rearrangements were consistently 5.5 to 1. The stereochemistry at the original Ser α-carbon controlled the stereochemistry of the Luche reduction, but it did not affect the stereochemical outcome of the rearrangement, which consistently gave the (Z)-alkene. The epimerized by-product, (2S,5S)-10, resulting from the work-up after Na/NH₃ debenzylation of (2S,5R)-9, was carried on to the (2S,5S)-1 isomer. Compound (2S,5S)-10 was resynthesized from the Luche reduction by-product, (2R,3R)-3, and the stereochemistry was confirmed by comparison of the optical rotations. The IC₅₀ values for (2R,5S)-1, (2S,5R)-1 and (2S,5S)-1 Pin1 inhibition were: 52, 85, and 140 μM, respectively.     

Effect of Low Doses (5-40 cGy) of Gamma-irradiation on Lifespan and Stress-related Genes Expression Profile in Drosophila melanogaster

Studying of the effects of low doses of γ-irradiation is a crucial issue in different areas of interest, from environmental safety and industrial monitoring to aerospace and medicine. The goal of this work is to identify changes of lifespan and expression stress-sensitive genes in Drosophila melanogaster, exposed to low doses of γ-irradiation (5 – 40 cGy) on the imaginal stage of development. Although some changes in life extensity in males were identified (the effect of hormesis after the exposure to 5, 10 and 40 cGy) as well as in females (the effect of hormesis after the exposure to 5 and 40 cGy), they were not caused by the organism “physiological” changes. This means that the observed changes in life expectancy are not related to the changes of organism physiological functions after the exposure to low doses of ionizing radiation. The identified changes in gene expression are not dose-dependent, there is not any proportionality between dose and its impact on expression. These results reflect nonlinear effects of low dose radiation and sex-specific radio-resistance of the postmitotic cell state of Drosophila melanogaster imago.