CRISPR-based gene editing of non-homologous end joining factors biases DNA repair pathway choice toward single-strand annealing in Aedes aegypti

To maintain genome stability, eukaryotic cells orchestrate DNA repair pathways to process DNA double-strand breaks (DSBs) that result from diverse developmental or environmental stimuli. Bias in the selection of DSB repair pathways, either non-homologous end joining (NHEJ) or homology-directed repair (HDR), is also critical for efficient gene editing and for homing-based gene drive approaches developed for the control of disease-transmitting vector mosquitoes. However, little is understood about DNA repair homeostasis in the mosquito genome. Here, we utilized CRISPR/Cas9 to generate indel mutant strains for core NHEJ factors ku80, DNA ligase IV (lig4), and DNA-PKcs in the mosquito Aedes aegypti and evaluated the corresponding effects on DNA repair. In a plasmid-based assay, disruption of ku80 or lig4, but not DNA-PKcs, reduced both NHEJ and SSA. However, a transgenic reporter strain-based test revealed that those mutations significantly biased DNA repair events toward SSA. Interestingly, ku80 mutation also significantly increased the end joining rate by a yet-characterized mechanism in males. Our study provides evidence that the core NHEJ factors have an antagonistic effect on SSA-based DSB repair of the Ae. aegypti genome. Down-modulating the NHEJ pathway can enhance the efficiency of nuclease-based genetic control approaches, as most of those operate by homology-based repair processes along with extensive DNA end resection that is antagonized by NHEJ.

Engineering a self-eliminating transgene in the yellow fever mosquito, Aedes aegypti

Promising genetics-based approaches are being developed to reduce or prevent the transmission of mosquito-vectored diseases. Less clear is how such transgenes can be removed from the environment, a concern that is particularly relevant for highly invasive gene drive transgenes. Here, we lay the groundwork for a transgene removal system based on single-strand annealing (SSA), a eukaryotic DNA repair mechanism. An SSA-based rescuer strain (kmo^RG ) was engineered to have direct repeat sequences (DRs) in the Aedes aegypti kynurenine 3-monooxygenase (kmo) gene flanking the intervening transgenic cargo genes, DsRED and EGFP. Targeted induction of DNA double-strand breaks (DSBs) in the DsRED transgene successfully triggered complete elimination of the entire cargo from the kmo^RG strain, restoring the wild-type kmo gene, and thereby, normal eye pigmentation. Our work establishes the framework for strategies to remove transgene sequences during the evaluation and testing of modified strains for genetics-based mosquito control.

Spectral filtering of high-order harmonics via optics-free focusing

Controlling the wavefront of an extreme ultraviolet (XUV) high-order harmonic beam during the generation process offers the capability of modifying the beam properties without resorting to any XUV optics. By characterizing the XUV intensity profile and wavefront, we quantitatively retrieve both the size and the position of the waist of each harmonic generated in an argon jet. We show that optics-free focusing can occur under specific generating conditions leading to XUV focii of micrometer size. We also demonstrate that each focus is located at distinct longitudinal positions. Using this remarkable XUV wavefront control combined with near focus spatial selection, we experimentally demonstrate efficient and adjustable spectral filtering of the XUV beam, along with a strong rejection of the fundamental beam, without using any XUV optics. The experimental results are compared with simulations providing the impact of the filtering on the temporal profile of the XUV field. It shows that the attosecond structure is preserved and that the beam is more homogeneous after the filtering, thereby reducing the longitudinal focii shift. This is a major step to achieve high XUV intensity and probing ultrafast processes with an improved resolution.

Novel synthetic 3'-untranslated regions for controlling transgene expression in transgenic Aedes aegypti mosquitoes

Transgenic technology for mosquitoes is now more than two decades old, and a wide array of control sequences have been described for regulating gene expression in various life stages or specific tissues. Despite this, comparatively little attention has been paid to the development and validation of other transgene-regulating elements, especially 3'-untranslated regions (3'UTRs). As a consequence, the same regulatory sequences are often used multiple times in a single transgene array, potentially leading to instability of transgenic effector genes. To increase the repertoire of characterized 3'UTRs available for genetics-based mosquito control, we generated fifteen synthetic sequences based on the base composition of the widely used SV40 3'UTR sequence, and tested their ability to contribute to the expression of reporter genes EGFP or luciferase. Transient transfection in mosquito cells identified nine candidate 3'UTRs that conferred moderate to strong gene expression. Two of these were engineered into the mosquito genome through CRISPR/Cas9-mediated site-specific insertion and compared to the original SV40 3'UTR. Both synthetic 3'UTRs were shown to successfully promote transgene expression in all mosquito life stages (larva, pupa and adults), similar to the SV40 3'UTR, albeit with differences in intensity. Thus, the synthetic 3'UTR elements described here are suitable for regulating transgene expression in Ae. aegypti, and provide valuable alternatives in the design of multi-gene cassettes. Additionally, the synthetic-scramble approach we validate here could be used to generate additional functional 3'UTR elements in this or other organisms.

A knockout screen of genes expressed specifically in Ae. aegypti pupae reveals a critical role for stretchin in mosquito flight

Aedes aegypti is a critical vector for transmitting Zika, dengue, chikungunya, and yellow fever viruses to humans. Genetic strategies to limit mosquito survival based upon sex distortion or disruption of development may be valuable new tools to control Ae. aegypti populations. We identified six genes with expression limited to pupal development; osi8 and osi11 (Osiris protein family), CPRs and CPF (cuticle protein family), and stretchin (a muscle protein). Heritable CRISPR/Cas9-mediated gene knockout of these genes did not reveal any defects in pupal development. However, stretchin-null mutations (strn^Δ35/Δ41) resulted in flightless mosquitoes with an abnormal open wing posture. The inability of adult strn^Δ35/Δ41 mosquitoes to fly restricted their escape from aquatic rearing media following eclosion, and substantially reduced adult survival rates. Transgenic strains which contain the EGFP marker gene under the control of strn regulatory regions (0.8 kb, 1.4 kb, and 2.2 kb upstream, respectively), revealed the gene expression pattern of strn in muscle-like tissues in the thorax during late morphogenesis from L₄ larvae to young adults. We demonstrated that Ae. aegypti pupae-specific strn is critical for adult mosquito flight capability and a key late-acting lethal target for mosquito-borne disease control.

Lonomia caterpillar envenoming in French Guiana reversed by the Brazilian antivenom: A successful case of international cooperation for a rare but deadly tropical hazard

In the American continent, larval forms (caterpillars) of the Lonomia genus can cause systemic reactions in human beings. In this Paper, we report the third case of Lonomia envenoming recorded in French Guiana in 25 years, and the first in which specific antivenom was administered. Severe symptoms of the envenoming were observed in our patient including pain; coagulopathy and systemic hemorrhage. They are caused by skin contact with caterpillars. Recovery, however, was quite satisfactory thanks to the international cooperation of the health authorities in both France and Brazil.

[Puberty, fertility and chronic diseases]

The onset of puberty is the sum of complex and multifactorial mechanisms resulting from the action of both activating and inhibiting factors, leading to the maturation of the gonads and the ability to reproduce. Many contributors to pubertal development are involved in fat mass acquisition and their action is relayed through the hypothalamus. It is therefore easy to understand how chronic diseases can affect the development of puberty and fertility apart from the specific impact of their molecular alteration. We have chosen cystic fibrosis and chronic renal disease as examples of chronic disorders affecting puberty through distinct mechanisms. As drugs are undistinguishable from chronic diseases, we also describe the impact of corticosteroids and chemotherapy on reproductive function. Last, we describe the surveillance and care of pubertal delay and its consequences (growth and bone mineralization) of patients affected with chronic disorders during adolescence.

Aberration-free laser beam in the soft x-ray range

By seeding an optical-field-ionized population-inverted plasma amplifier with the 25th harmonic of an IR laser, we have achieved what we believe to be the first aberration-free laser beam in the soft x-ray spectral range. This laser emits within a cone of 1.34 mrad(1/e(2)) at a repetition rate of 10 Hz at a central wavelength of 32.8 nm. The beam exhibits a circular profile and wavefront distortions as low as lambda/17. A theoretical analysis of these results shows that this high beam quality is due to spatial filtering of the seed beam by the plasma amplifier aperture.

Non-thermal desorption/ablation of molecular solids induced by ultra-short soft x-ray pulses

We report the first observation of single-shot soft x-ray laser induced desorption occurring below the ablation threshold in a thin layer of poly (methyl methacrylate)--PMMA. Irradiated by the focused beam from the Free-electron LASer in Hamburg (FLASH) at 21.7 nm, the samples have been investigated by atomic-force microscope (AFM) enabling the visualization of mild surface modifications caused by the desorption. A model describing non-thermal desorption and ablation has been developed and used to analyze single-shot imprints in PMMA. An intermediate regime of materials removal has been found, confirming model predictions. We also report below-threshold multiple-shot desorption of PMMA induced by high-order harmonics (HOH) at 32 nm. Short-time exposure imprints provide sufficient information about transverse beam profile in HOH's tight focus whereas long-time exposed PMMA exhibits radiation-initiated surface ardening making the beam profile measurement infeasible.

264 SUITABILITY OF BOVINE SEXING PRIMERS FOR SEX DETERMINATION OF CAPRINE CELLS

Recent studies on PCR-based sex determination of caprine cells use amplification of a single-copy Y-chromosome-specific sequence. Our study investigated the suitability of widely used bovine sexing primers for their usefulness in sexing caprine cells. The common use of these sexing primers is to amplify BRY.4, a Y-specific sequence found in bovine cells (Reed et al. 1995 U.S. Pat# 5459038). The major advantage in amplifying these sequences is that they are multiple repeated DNA sequences. This enhances the sensitivity for use on as few as one cell. Early in their use, a problem was discovered amplifying BRY.4 for bovine sexing; one or more copies of a homologous repeat sequence were present in female cells. Copies in female cells differed by the presence of a Hinf1 restriction site. By digesting the DNA with Hinf1 either prior or subsequent to PCR amplification, it was possible to eliminate the troublesome sequence. Our study investigated whether a site homologous to theY-specific sequence was also present in female caprine cells and, if so, it too contained the Hinf1 restriction site, making possible the elimination of the troublesome sequence. The components of the PCR reaction mix were: buffer (50 mm Tris, 1% dextran T-500, 50 mm KCl, 2.5 mm MgCl2, and 0.035% 2- mercaptoethanol), deoxyribonucleotides (5 µm) (Boehringer Mannheim, Basel, Switzerland), primers (5´-GAACTTTCAAGCAGCTGAGGC-3´ and 5´-GATTGTTGATCCCACAGAAGG-3´) (2.5 µm) (custom synthesis, IDT Inc, Coralville, IA, USA), and Taq polymerase (2.7 U) (AmpliTaq DNA Polymerase, Stoeffel Fragment, Perkin Elmer, Branchburg, NJ, USA). Lymphocytes from one male and three female goat species (Saanen, Nubian/Alpine mix, and Albino) were used as the source of DNA. Approximately 100 cells/2 µL were used to ensure the amplification of the sequence homologous to theY-repeat. The DNA replication was carried out using a Corbett Rapid Thermocycler (Model FTS-IS, Corbett Research, Montlake, Australia) in 20-µL volumes, and all assays were run with positive and negative DNA controls. After replication, some samples were digested with Hinf1 (20 U) (New England Biolabs, Ipswich, MA, USA) for 2 h at 38�C. A 3% agarose gel was run in an agarose gel electrophoresis apparatus (Model 52000, IBI-Shelton Scientific, Peosta, IA, USA) for 30 min at 180 volts. All caprine species samples were run in duplicate. The DNA from three female undigested samples banded at the same position as the male samples (130 bp). The DNA from all three female digested samples banded at two positions (50 bp and 80 bp), both lower than the male samples. The male DNA remained unaltered after the Hinf1 digest, which suggests that the Hinf1 site is not present in the amplified DNA from male cells. The assay generated strong sexing bands with as few as 6 male lymphocytes, the lowest number of cells tested. These primers seem suitable if used in conjunction with Hinf1 digestion.

270 STILL GLOWING AFTER ALL THESE YEARS: STORAGE LIFE OFA COMPLETE BOVINE SEXING PCR MIX

Generally, PCR reaction mixes are made fresh on the day of use. This is impractical for field sexing. Mistakes occur due to the required measuring precision and to contamination from environmental DNA. Therefore, we developed a complete reaction mix (YCD). Storage and transport of YCD required liquid N2. No study has determined storage life of PCR reaction mixes in standard freezers. Our study compared 14-year-old bovine YCD (AB Technology, Pullman, WA, USA) stored in a standard freezer to a freshly prepared mix. The working concentration of bovineYCD was: buffer (50 mm Tris, 1% dextran T-500, 50 mm KCl, 2.5 mm MgCl2, and 0.035% 2-mercaptoethanol), deoxyribonucleotides (5µm) (Boehringer Mannheim, Basel, Switzerland), two sets of primers (sexing primers, 5´-GAACTTTCAAGCAGCTGAGGC-3´ and 5´-GATTGTTGATCCCACAGAAGG-3´ (2.5µm), and control primers, 5´-TTGAGGCATGGAACTCCGCT-3´ and 5´-GGTGGTTCCACATTCCGTAGG-3´ (0.25µm) (custom synthesis, IDT Inc, Coralville IA, USA)), and Taq polymerase (Taq p) (2 IU) (AmpliTaq DNA Polymerase, Stoeffel Fragment, Perkin Elmer, Branchburg, NJ, USA). The concentrations in the complete reaction mix were twice the working concentration. The freshly prepared mix was the same as YCD except: deoxyribonucleotides (C01581, GenScript Corp., Piscataway, NJ, USA) and Taq p (M0273L, New England BioLabs, Ipswich, MA, USA). Male and female bovine lymphocytes (100 cells/2 µL) were used as the DNA source. The DNA replication occurred in a Corbett Rapid Thermocycler (Model FTS-IS, Corbett Research, Montlake, Australia) in 20-µL volumes. All assays were run with positive and negative DNA controls. The PCR products were separated using polyacrylamide gel electrophoresis (PAGE). A 6% gel with Tris as the buffer was formed in an agarose gel chamber (M12 Electrophoresis Unit, Edvotek, Bethesda, MD, USA) under argon gas. The gel was run at 200 volts (PS500ST, Hoefer Scientific Instruments, San Francisco, CA, USA) for 30 min, and then stained with 5 µL ethidium bromide in 100 mL of Tris buffer for 30 min. The gel was destained for 30 min in H2O. The gel was viewed using a transilluminator (3–300, Fotodyne, Hartland, WI, USA) and photographed. The 14-year-old stored YCD and freshly prepared reaction mix both produced strong signals. We further investigated effects of stability of two reagents: 8-year-old AmpliTaq and 8-year-old deoxyribonucleotides (Boehringer Mannheim, Basel, Switzerland). Nucleotides and Taq p have a labeled shelf life of two years. Sexing bands were observed in gels from the reaction mix with 8-year-old deoxyribonucleotides, but no signals were observed with the use of 8-year-old AmpliTaq. These results suggest that Taq p is the most likely candidate to cause failure in stored PCR reaction mixes. As supplied, Taq p is liquid even when stored in the freezer. Our hypothesis is that because the Taq p was frozen solid in YCD instead of being kept in a liquid form, the denaturing of Taq p was prevented. We conclude that storage and transport of PCR reaction mix could become more convenient: ship on dry ice and transport to the field in a mobile freezer.

269 THE ENHANCEMENT OF THE SENSITIVITY OF A PCR-BASED AVIAN SEX DETERMINATION ASSAY

For over a decade it has been possible to externally sex monomorphic birds using PCR. A major drawback of the protocol developed by Richard Griffiths is that DNA from at least 20 000 cells is needed (Griffiths et al. 1996 Proc. Royal Soc. London B 263, 1249–1254). Our study attempted to decrease the number of cells required. A sequence within the chromobox-helicase-DNA-binding (CHD) gene, located on the sex chromosomes of all avian species, was amplified. The sequence lengths were 362 and 354 base pairs for the CHD-W and CHD-Z, respectively. The polyacrylamide gel electrophoresis (PAGE) purified primers used were 5´-TCTGCATCGCTAAATCCTTT-3´ and 5´-CTCCCAAGGATGAGRAAYTG-3´ (2.5 µm) (IDT, Inc., San Jose, CA, USA). All assays used Taq DNA polymerase (2.7 U) (M0273L, New England BioLabs, Ipswich, MA, USA) and deoxyribonucleotides (5 µm) (C01581, GenScript Corp, Piscataway, NJ, USA). Lymphocytes from chickens (Gallus domesticus) (10 cells/2 µL) were used as the DNA source for all experiments. Assays were run with positive and negative DNA controls. The DNA was replicated in a Corbett Rapid Thermocycler (Model FTS-IS, Corbett Research, Sydney, Australia) in 20 µL volumes with an annealing temperature of 48�C. All of the PCR products were separated using PAGE. An 8% gel (17:1, con- to bis-acrylamide) with 10 mm TRIS (pH 8) was formed in an agarose gel chamber (M12 Electrophoresis Unit, Edvotek, Bethesda, MD, USA) under Ar. The gel was placed in 10 mm TRIS (pH 8) in the electrophoresis apparatus and the PCR products were added to wells. The applied voltage was 200 and the duration was 2 h (PS500ST, Hoefer Scientific Instruments, San Francisco, CA, USA). The gel was stained for 30 min in 1.25 µm ethidium bromide in 100 mL of 10 mm TRIS (pH 8). Destaining was carried out over 45 min in 100 mL of H2O. The gel was viewed using a transilluminator (3–300, Fotodyne, Hartland, WI, USA) and photographed with an Olympus digital camera. An initial experiment established Griffiths' assay in our lab. Results were consistent with published data, albeit with the same troubling signal-to-noise problems. No signals were observed in assays with less than 20 000 cells. The next experiment compared the use of Griffiths' amplification buffer to a buffer we developed, Bart: 50 mm barbital, 1% dextran T-500, 50 mm KCl, 2.5 mm MgCl2, and 0.035% 2-mercaptoethanol. Signals were produced and a working assay was established with only 10 cells needed, significantly fewer cells than the 20 000 cells necessary for Griffiths' protocol. It was possible to increase the number of productive replication cycles from 35 to 45 without generation of noise. In fact, use of Bart eliminated primer-generated noise, leaving only sexing bands in the gel. Interestingly, when Bart was used with 20 000 cells, no signals were observed. Assays incorporating Bart were run in triplicate and signals were consistently observed. Reduction in the number of cells required for avian sex determination provides potential applications for the sexing of embryos or sexing from a single down feather. Our assay makes sex determination prior to hormonal treatment simple. We are currently replacing the use of the CHD gene with a conserved W-specific sequence.

Demonstration of a spatial filtering amplifier for high-order harmonics

We report what is to our knowledge the first demonstration of spatial filtering of a high-order harmonic beam into a soft-x-ray laser plasma amplifier at 32.8 nm. After amplification the seed energy is enhanced by a factor of 50, and the beam profile of the amplified beam exhibits an Airy-like shape due to the spatial filtering by the optical field ionized plasma. Moreover, the transverse coherence of the spatially filtered amplified beam is strongly enhanced, resulting in the generation of a peak coherent power of 0.9 x 10(5) to 1.8 x 10(5) W.

Temporal superresolution of ultrashort laser pulses

We introduce the notion of temporal superresolution for ultrashort laser pulses, by analogy with the well-known method of optical superresolution in imaging systems. Simple linear spectral masks are presented, that shapes a laser pulse into a central peak of very short duration, well below the Fourier limited width of Gaussian pulses, but accompanied by low intensity satellite pulses. A proof-of-principle experiment is presented, using a short pulse, high intensity laser system. Such lasers may induce very strongly non linear phenomena in laser-matter interactions, suppressing the effect of the satellite pulses and therefore fully mimicking shorter light pulses. As an example, we show theoretically that the field ionization asymmetry induced by cosine few cycle pulses is strongly enhanced using temporally superresolved laser pulses.

Attosecond electron wave packet dynamics in strong laser fields

We use a train of sub-200 attosecond extreme ultraviolet (XUV) pulses with energies just above the ionization threshold in argon to create a train of temporally localized electron wave packets. We study the energy transfer from a strong infrared (IR) laser field to the ionized electrons as a function of the delay between the XUV and IR fields. When the wave packets are born at the zero crossings of the IR field, a significant amount of energy (approximately 20 eV) is transferred from the field to the electrons. This results in dramatically enhanced above-threshold ionization in conditions where the IR field alone does not induce any significant ionization. Because both the energy and duration of the wave packets can be varied independently of the IR laser, they are valuable tools for studying and controlling strong-field processes.

A high-intensity highly coherent soft X-ray femtosecond laser seeded by a high harmonic beam

Synchrotrons have for decades provided invaluable sources of soft X-rays, the application of which has led to significant progress in many areas of science and technology. But future applications of soft X-rays--in structural biology, for example--anticipate the need for pulses with much shorter duration (femtoseconds) and much higher energy (millijoules) than those delivered by synchrotrons. Soft X-ray free-electron lasers should fulfil these requirements but will be limited in number; the pressure on beamtime is therefore likely to be considerable. Laser-driven soft X-ray sources offer a comparatively inexpensive and widely available alternative, but have encountered practical bottlenecks in the quest for high intensities. Here we establish and characterize a soft X-ray laser chain that shows how these bottlenecks can in principle be overcome. By combining the high optical quality available from high-harmonic laser sources (as a seed beam) with a highly energetic soft X-ray laser plasma amplifier, we produce a tabletop soft X-ray femtosecond laser operating at 10 Hz and exhibiting full saturation, high energy, high coherence and full polarization. This technique should be readily applicable on all existing laser-driven soft X-ray facilities.

Imaging and quality assessment of high-harmonic focal spots

We present a direct method of studying the focusability of an intense, short-pulse extreme-ultraviolet (XUV) beam obtained by high-harmonic generation. We perform near-field imaging of the focal spot of five high-harmonic orders strongly focused by a broadband toroidal mirror. To visualize the focal spot directly, we image the fluorescence induced by an XUV beam on a cerium-doped YAG crystal on a visible CCD camera. We can thus measure the harmonic spot size on a single image, together with the Strehl ratio, to evaluate the quality of focusing. Such techniques should become instrumental in optimizing the focusing conditions and reaching intensities required for exploring attosecond nonlinear optics in the XUV range.

Global optimization of high harmonic generation

We investigate the relevance of the absorption limit concept in the optimization of high harmonic generation. Thanks to the first direct observation of the coherence length of the process from high-contrast Maker fringes, we unravel experimental conditions for which the harmonic dipole response is enhanced when phase matching is realized within the absorption limit, leading to record conversion efficiencies in argon. Moreover, we show that harmonic generation in guided or freely propagating geometries are equivalent in the loose focusing regime. This analysis is generalized to other advanced phase-matching schemes, thereby predicting the possibility to boost the conversion efficiencies using light noble gases.

Demonstration of a Ni-like Kr optical-field-ionization collisional soft x-ray laser at 32.8 nm

We report the first experimental demonstration of a Ni-like optical-field ionization collisional soft x-ray laser. The amplifying medium is generated by focusing a circularly polarized 760 mJ, 30 fs, 10-Hz Ti:sapphire laser beam in a few mm cell filled with krypton. We have measured a gain coefficient of 78 cm(-1) on the 3d(9)4d 1S0-3d(9)4p(1)P1 transition at 32.8 nm, which is here amplified for the first time. This radiation source represents the shortest wavelength optical-field ionization collisional soft x-ray laser ever produced. The influence of the gas pressure and the pumping energy on the lasing output are also presented.

Triose phosphate isomerase deficiency in 3 French families: two novel null alleles, a frameshift mutation (TPI Alfortville) and an alteration in the initiation codon (TPI Paris)

Three French families with triose phosphate isomerase (TPI) deficiency were studied, and 2 new mutations giving rise to null alleles were observed: a frameshift mutation with deletion of the 86-87 TG dinucleotide in codon 29 (TPI Alfortville) and a T-->A transversion in nucleotide 2 of the initiation codon (TPI Paris). The first mutation occurred in compound heterozygosity with the frequent E105D mutation. The second mutation occurred in association with the 2-nucleotide promoter variant (-43G,-46A). In a third family, the propositus was an E105D homozygote. In the TPI Paris family, the coinheritance of the -43,-46 promoter variant appeared to exert little, if any, effect on TPI enzyme activity, a finding consistent with 2 previous reports that questioned the putative role of the promoter polymorphism as a true deficiency variant. Similarly, the further coinheritance of glucose-6-phosphate dehydrogenase (G6PD) A- (202 G-->A/376 A-->G) appeared to have little effect on the observed phenotype. Compound heterozygosity for the E105D mutation with the null allele TPI Alfortville appeared to lead to a more severe clinical syndrome than did E105D homozygosity, suggesting that compound heterozygosity with null alleles may lead to more profound clinical abnormalities than homozygosity with missense alleles. A simple, rapid polymerase chain reaction and restriction enzyme procedure for the E105D mutation was developed for prenatal diagnosis in one family and subsequently used for screening in the other families.

A phosphoglycerate kinase mutant (PGK Herlev; D285V) in a Danish patient with isolated chronic hemolytic anemia: mechanism of mutation and structure-function relationships

Phosphoglycerate kinase (PGK) is a X-linked enzyme that plays a key role in the glycolytic pathway. Twelve different variants have already been reported. We describe a new PGK variant, PGK Herlev (Asp 285-->Val), in a 69-year-old Danish patient with isolated chronic hemolysis but who had no neurological or muscular disorders. The description of the mutation is based upon PCR amplification of specific regions of the PGK gene, followed by direct sequencing. Although observed in a male patient, this mutated X-linked gene is expressed partially, i.e., both normal and substituted nucleotides are present at the same position in a ratio of approximately 1:9. The most likely explanation for this observation is based on the occurrence of a somatic mutation of the PGK gene. The relationship of structure to function in PGK Herlev, as well as in all known variants, was examined by the use of a computer model based on the known spatial structure of the yeast and horse enzymes. Such an approach can be generalized to any other protein that has been crystallized and for which x-ray diffraction data are available in a species closely related to man.

A sensitive mapping strategy for monitoring the reproducibility of glycan processing in an HIV vaccine, RGP-160, expressed in a mammalian cell line

The external envelope glycoprotein (gp160) of HIV-1 is a candidate for vaccines against AIDS. Most of the surface of the molecule is shielded by carbohydrate and the structures and locations of these glycans may be important in defining the immunogenicity of the viral coat. Here we report a sensitive mapping strategy for profiling and analysing the N-glycosylation of gp160, based on chemical release of glycans, fluorescent labelling and HPLC analysis. This approach has been validated in terms of establishing the reproducibility of all steps in the analytical procedure and on overall reproducibility on a run-to-run and day-to-day basis. The validated analysis technique was used to monitor the consistency of N-glycosylation of one rgp 160 vaccine candidate produced in baby hamster kidney (BHK) cell culture. It was demonstrated that the variation in the glycan profiles of 6 different lots was not statistically significant.

Identical germ-line mutations in the triosephosphate isomerase alleles of two brothers are associated with distinct clinical phenotypes

We describe here a new stop mutation at triosephosphate isomerase (TPI) position 145 in a Hungarian family for which the first mutation (240 Phe-->Leu) was published earlier. The entire genomic TPI locus (exons, introns and promoter) was sequenced and found to be identical in the two compound-heterozygote brothers. Both brothers have the same well-compensated level of non-spherocytic hemolytic anemia and very high levels of the TPI substrate dihydroxyacetonephosphate (DHAP), but only one brother manifests neurologic disorders. Differences in nonsense-mediated mRNA decay may be at the basis of the differences in phenotype expression although it cannot be excluded the interaction with a modifier gene. Based on our earlier results, the development of neurodegeneration may be decisively modulated by the cellular environment of the mutant proteins initiating the process of focal apoptosis of neurons in glycolytic, peroxisomal and prion-induced neurological diseases.

Safety and immunogenicity of a live recombinant canarypox virus expressing HIV type 1 gp120 MN MN tm/gag/protease LAI (ALVAC-HIV, vCP205) followed by a p24E-V3 MN synthetic peptide (CLTB-36) administered in healthy volunteers at low risk for HIV infection. AGIS Group and L'Agence Nationale de Recherches sur Le Sida

A live recombinant canarypox vector expressing HIV-1 gpl20 MN tm/gag/protease LAI (ALVAC-HIV, vCP205) alone or boosted by a p24E-V3 MN synthetic peptide (CLTB-36) was tested in healthy volunteers at low risk for HIV infection for their safety and immunogenicity. Both antigens were well tolerated. ALVAC-HIV (vCP205) induced low levels of neutralizing antibodies against HIV-1 MN in 33% of the volunteers. None of them had detectable neutralizing antibodies against a nonsyncytium-inducing HIV-1 clade B primary isolate (Bx08). After the fourth injection of vCP205, CTL activity was detected in 33% of the volunteers and was directed against Env, Gag, and Pol. This activity was mediated by both CD4+ and CD8+ lymphocytes. On the other hand, the CLTB-36 peptide was poorly immunogenic and induced no neutralizing antibodies or CTLs. Although the ALVAC-HIV (vCP205) and CLTB-36 prime-boost regimen was not optimal, further studies with ALVAC-HIV (vCP205) are warranted because of its clear induction of a cellular immune response and utility as a priming agent for other subunit antigens such as envelope glycoproteins, pseudoparticles, or new peptides.

A multi-mode chromatographic method for the comparison of the N-glycosylation of a recombinant HIV envelope glycoprotein (gp160s-MN/LAI) purified by two different processes

The glycosylation pattern of a recombinant gp160s-MN/LAI variant of human immunodeficiency virus type 1 (HIV-1) was studied in relation to two alternative purification techniques one of which involves an immunoprecipitation step. For analysis a multi-mode high performance liquid chromatography (HPLC) method which combines gel permeation chromatography on the RAAM 2000 GlycoSequencer, weak anion exchange chromatography and normal phase chromatography was developed and profiles were obtained for the fluorescently-labelled glycans released from the two gp160s-MN/LAI preparations. Charged glycans accounted for 77 and 80% of the total glycans for the IAP- and SP-purified samples, respectively. The acidic character of these glycans was mainly due to the presence of sialic acids. However, following sialidase treatment, residual charged glycans were still found. No differences were found in the glycan distributions of the two gp160s-MN/LAI preparations either in their degree of sialylation or in their relative proportion of each separated structure. Although this did not reach statistical significance, a lower proportion of large glycan structures regardless of their charge status was found on the gp160s-MN/LAI prepared by the procedure which involved an immunoaffinity chromatography step.

A new sickle cell disease phenotype associating Hb S trait, severe pyruvate kinase deficiency (PK Conakry), and an alpha2 globin gene variant (Hb Conakry)

A Guinean woman, heterozygous for haemoglobin (Hb) S, was studied because of episodes of marked anaemia, repeated typical metaphyseal painful crises and haemosiderosis. Her sickling syndrome resulted from the association of Hb S trait with a severe pyruvate kinase deficiency leading to a 2,3-DPG concentration of twice normal levels. Sequence of the PK-R gene revealed an undescribed mutation in the homozygous or hemizygous state within exon 5 (nucleotide 2670 C-->A), leading to the interchange of Ser 130 into Tyr (PK Conakry). In addition, the patient carried a new haemoglobin variant, Hb Conakry [alpha80(F1) Leu-->Val], which seemed to have a mild effect. The high intraerythrocytic 2,3-DPG concentration induced by the PK deficiency resulted in a decreased oxygen affinity which favoured sickling to a level almost similar to that of Hb S/C compound heterozygous patients. This was confirmed by oxygen binding measurements of Hb A/Hb S erythrocytes in which 2,3-DPG content was modified in vitro. Hysteresis between deoxy- and reoxygenation curves, as well as increase in the n(max) value, demonstrated that the extent of HbS polymerization in the propositus was almost the same as that of RBCs from a homozygous sickle cell patient or those of an A/S heterozygous patient with an artificial in vitro increase of 2,3-DPG concentration.

A phosphoglycerate kinase mutant (PGK Herlev; D285V) in a Danish patient with isolated chronic hemolytic anemia: mechanism of mutation and structure-function relationships

Phosphoglycerate kinase (PGK) is a X-linked enzyme that plays a key role in the glycolytic pathway. Twelve different variants have already been reported. We describe a new PGK variant, PGK Herlev (Asp 285-->Val), in a 69-year-old Danish patient with isolated chronic hemolysis but who had no neurological or muscular disorders. The description of the mutation is based upon PCR amplification of specific regions of the PGK gene, followed by direct sequencing. Although observed in a male patient, this mutated X-linked gene is expressed partially, i.e., both normal and substituted nucleotides are present at the same position in a ratio of approximately 1:9. The most likely explanation for this observation is based on the occurrence of a somatic mutation of the PGK gene. The relationship of structure to function in PGK Herlev, as well as in all known variants, was examined by the use of a computer model based on the known spatial structure of the yeast and horse enzymes. Such an approach can be generalized to any other protein that has been crystallized and for which x-ray diffraction data are available in a species closely related to man.

Agroecological zones and the assessment of crop production potential

The rapidly growing world population puts considerable pressure on the scarce natural resources, and there is an urgent need to develop more efficient and sustainable agricultural production systems to feed the growing population. This should be based on an initial assessment of the physical and biological potential of natural resources, which can vary greatly. The agroecological zonation (AEZ) approach presents a useful preliminary evaluation of this potential, and ensures that representation is maintained at an appropriate biogeographic scale for regional sustainable development planning. The principal AEZs of the world, as described by the Technical Advisory Committee of the Consultative Group on International Agricultural Research, are presented along with their extent and characteristics. Net primary productivity of terrestrial vegetation can be assessed from weather data, and it varies from 1 t dry matter ha −1 yr −1 in high latitude zones and dry regions to 29 t ha −1 yr −1 in tropical wet regions, depending on the climatic conditions. To assess the crop production potential, length of the growing period zones, a concept introduced by the UN Food and Agriculture Organization, is very useful as it describes an area within which rainfall and temperature conditions are suitable for crop growth for a given number of days in the year. These data, combined with the information on soils and known requirements of different food crops, can be used to assess the potential crop productivity. Some perspectives on AEZs and crop production potential are presented by describing the manner in which production potential can be integrated with present constraints. Efforts to intensify production should place emphasis on methods appropriate to the socio-economic conditions in a given AEZ, and on promotion of conservation-effective and sustainable production systems to meet the food, fodder and fuel needs for the future.

Five unknown mutations in the LR pyruvate kinase gene associated with severe hereditary nonspherocytic haemolytic anaemia in France

A survey of PK-deficient patients by molecular biology techniques has been performed in France in 26 unrelated families, in which at least one mutation has been characterized. The patients, of European or North African origin, exhibited approximatively 10% of PK activity. Among the PK-R mutants described, mutation G1529-->A (Arg-509-->Gln) was the most frequent. The strategy followed for the description of PK mutants in France firstly involves determination of this mutation by PCR amplification and restriction enzyme digestion and, secondly, the sequencing of the gene for negative samples. Study of the mutation at residue 509 in 26 unrelated families indicated that 10/52 defective alleles possessed this mutation. Our study described seven different mutations; five of these have not as yet been documented. Two frameshift mutations were found: the deletion of one G base in a repetition of four Gs in position 1231-1234 (PK Mondor), del C-1527 (PK Rouen), and three missense mutations: G382-->C (Ala-114-->Pro) (PK Val-de-Marne), C398-->T (Ser-119-->Phe) (PK Beaujon), A1217-->G (Asn-392-->Ser) (PK Paris). Two mutations which were detected have been reported previously: C760-->T (Glu-240-->End) and G1529-->A (Arg-509-->Gln.

Identification of new mutations in two phosphoglycerate kinase (PGK) variants expressing different clinical syndromes: PGK Créteil and PGK Amiens

Phosphoglycerate kinase (PGK) deficiency is generally associated with chronic hemolytic anemia, although it can be accompanied by either mental retardation or muscular disease. Genomic DNAs of two PGK-deficient patients previously described in France were sequenced directly after polymerase chain reaction amplification. The PGK Créteil variant arises from a G-->A nucleotide interchange at position 1022 in cDNA (exon 9), resulting in amino acid substitution 314 Asp-->Asn in the C-terminal domain, which contains the nucleotide binding site. It is associated with rhabdomyolysis crises but not with hemolysis or mental retardation. In the other case, which is associated with chronic hemolytic anemia and mental retardation (PGK Amiens), an A-->T nucleotide interchange was found at position 571 in cDNA (exon 5); this leads to amino acid substitution 163 Asp-->Val in the N-terminal domain, which contains the catalytic site for phosphoglycerate binding. These results corroborate the kinetic data observed. In the two cases, the mutations are distinct from others previously reported and no significant relationship could be observed between the location of the amino acid substitution and its clinical consequences.

The evolutionary origin of red algae as deduced from the nuclear genes encoding cytosolic and chloroplast glyceraldehyde-3-phosphate dehydrogenases from Chondrus crispus

Algae are a heterogeneous group of photosynthetic eukaryotes traditionally separated into three major subdivisions: rhodophytes, chlorophytes, and chromophytes. The evolutionary origin of rhodophytes or red algae and their links to other photosynthetic and nonphotosynthetic eukaryotes have been a matter of much controversy and speculation. Here we present the first cDNAs of nuclear protein genes from red algae: Those encoding cytosolic and chloroplast glyceraldehyde-3-phosphate dehydrogenases (GAPDH) from Chondrus crispus. A phylogenetic analysis including GAPDH gene sequences from a number of eukaryotic taxa, cyanobacteria, and purple bacteria suggests that chloroplasts and rhodoplasts together form a monophyletic group of cyanobacterial descent and that rhodophytes separated from chlorophytes at about the same time as animals and fungi. The composite GAPDH tree further demonstrates that chloroplast and cytosolic GAPDH genes are closely related to their homologs in cyanobacteria and purple bacteria, respectively, the presumptive ancestors of chloroplasts and mitochondria, thereby firmly establishing the endosymbiotic origin of these nuclear genes and their fixation in eukaryotic cells before the rhodophyte/chlorophyte separation. The present data are in conflict with phylogenetic inferences based on plastid-encoded rbcL sequences supporting a polyphyletic origin of rhodoplasts and chloroplasts. Comparison of rbcL to GAPDH phylogenies suggests that rbcL trees may be misleading because they are composed of branches representing ancient duplicated (paralogous) genes.

The GAPDH gene system of the red alga Chondrus crispus: promoter structures, intron/exon organization, genomic complexity and differential expression of genes

Our previous phylogenetic analysis based on cDNA sequences of chloroplast and cytosolic glyceraldehyde-3-phosphate dehydrogenases (GAPDH; genes GapA and GapC, respectively) of the red alga Chondrus crispus suggested that rhodophytes and green plants are sister groups with respect to plastids and mitochondria and diverged at about the same time or somewhat later than animals and fungi. Here we characterize the genomic sequences of genes GapC and GapA of C. crispus with respect to promotor structures, intron/exon organization, genomic complexity, G + C content, CpG suppression and their transcript levels in gametophytes and protoplasts, respectively. To our knowledge this is the first report on nuclear protein genes of red algae. The GapC gene is G + C-rich, contains no introns and displays a number of classic sequence motifs within its promotor region, such as TATA, CAAT, GC boxes and several elements resembling the plant-specific G-box palindrome. The GapA gene has a moderate G+C content, a single CAAT box motif in its promotor region and a single intron of 115 bp near its 5' end. This intron occupies a conserved position corresponding to that of intron 1 in the transit peptide region of chloroplast GAPDH genes (GapA and GapB) of higher plants. It has consensus sequences similar to those of yeast introns and folds into a conspicuous secondary structure of -61.3 kJ. CpG profiles of genes GapC and GapA and their flanking sequences show no significant CpG depletion suggesting that these genomic sequences are not methylated. Genomic Southern blots hybridized with generic and gene specific probes indicate that both genes are encoded by single loci composed of multiple polymorphic alleles. Northern hybridizations demonstrate that both genes are expressed in gametophytes but not in protoplasts where appreciable amounts of transcripts can only be detected for GapC.

Compound heterozygosity in a complete erythrocyte bisphosphoglycerate mutase deficiency

Erythrocyte bisphosphoglycerate mutase (BPGM) deficiency is a rare disease associated with a decrease in 2,3-diphosphoglycerate concentration. A complete BPGM deficiency was described in 1978 by Rosa et al (J Clin Invest 62:907, 1978) and was shown to be associated with 30% to 50% of an inactive enzyme detectable by specific antibodies and resulting from an 89 Arg-->Cys substitution. The propositus' three sisters exhibited the same phenotype, while his two children had an intermediate phenotype. Samples from the family were examined using polymerase chain reaction and allele-specific oligonucleotide hybridization and sequencing techniques. Amplification of erythrocyte total RNA from the propositus' sister around the 89 mutation indicated the presence of two forms of messenger RNAs, a major form with the 89 Arg-->Cys mutation and a minor form with a normal sequence. Sequence studies of the propositus' DNA samples indicated heterozygosity at locus 89 and another heterozygosity with the deletion of nucleotide C 205 or C 206. Therefore, the total BPGM deficiency results from a genetic compound with one allele coding for an inactive enzyme (mutation BPGM Créteil I) and the other bearing a frameshift mutation (mutation BPGM Créteil II). Examination of the propositus' two children indicated that they both inherited the BPGM Créteil I mutation.

Isolation and characterization of the gene encoding the muscle-specific isozyme of human phosphoglycerate mutase

The human muscle-specific phosphoglycerate mutase encoding gene (PGAM-M) has been cloned from a genomic cosmid library and sequenced. The sequence corresponding to the coding region was evaluated and revised by sequencing of the protein itself, fully confirming our results. The amino acid sequence of the M isozyme presented a 80.6% homology with the B isozyme (non-muscle-specific isozyme), a value higher than previously reported. The PGAM-M gene is composed of three exons, which consist of 454, 180 and 202 bp, respectively, and are separated by two introns of 103 bp and approx. 5.6 kb, respectively. Comparison of the structure of the human PGAM-M gene with that coding for human bisphosphoglycerate mutase, an erythroid-specific enzyme belonging to the same multifunctional enzyme family, revealed that the location of the second intron is similar in each gene and corresponds to a tertiary subdomain in the spatial structure of the protein. The transcription start point (tsp) in the PGAM-M gene was identified by both primer extension and S1 nuclease-protection experiments. A TATA-box-like element was observed 29 bp upstream from the tsp; the sequence ATTGG, inverse/complementary to CCAAT-box, was found 40 bp upstream from the supposed TATA box. No muscle-specific consensus sequences could be detected in the 5'-untranslated region. Only one polyadenylation AATAAA signal was observed in the short 3'-untranslated region (43 bp long). Finally, only one copy of this gene is present in the human genome instead of the several copies found for the PGAM-B gene, suggesting the possible evolutionary origin of the muscle subunit in a modified copy of the PGAM-B gene.

Molecular size characterization of bacterial capsular polysaccharide vaccines by high performance liquid chromatography

Bacterial capsular polysaccharides are major virulence factors and some are used as vaccinal antigens. Their molecular size is an important physicochemical criterion which correlates with immunogenicity. This article describes a new application of high performance liquid chromatography (HPLC), based on molecular sieving, for such an evaluation. This HPLC method is rapid, accurate, reproducible, requires only very low amounts of product and presents good correlation with conventional gel permeation chromatography.

In situ mapping of the muscle-specific form of phosphoglycerate mutase gene to human chromosome 7p12-7p13

A 2.3-kb-long probe derived from the 5' flanking region, the first exon and part of the first intron of the human muscle-specific phosphoglycerate mutase gene (PGAM-M) (EC 5.4.2.1) was used to map the gene by "in situ" chromosomal hybridization. The structural gene for PGAM-M was assigned to chromosome 7p12-7p13; a single hybridization peak indicated that there is a single gene for this isozyme of PGAM, and confirmed results obtained by Southern blot hybridization.

Isolation and characterization of the human 2,3-bisphosphoglycerate mutase gene

The human 2,3-bisphosphoglycerate mutase gene was isolated from genomic libraries and analyzed by Southern blots and DNA sequencing. The transcription initiation site was localized by primer extension as well as by S1 protection of the mRNA. The gene extends over 22 kilobase pairs; it is composed of two introns (8.8 and 11.5 kilobase pairs long) and three exons (84, 662, and 965 base pairs long). The second exon correlates with a functional subdomain of the protein, as shown by comparison with the yeast phosphoglycerate mutase structure. The sequence TAGAAAA was found 30 bases upstream from the transcription initiation site and could be analogous to the TATA box. A sequence homologous to the CCAAT box was found twice, at positions -75 and -178. There is no GC-rich sequence or GC box in the 5'-flanking region of the gene. Northern blot analysis indicates that the 2,3-bisphosphoglycerate mutase mRNA is detected mainly in erythroid tissues and cell lines, although it is also present in low amounts in a nonerythroid tissue. A comparison of the 5'-upstream sequences with other promoters active only in erythroid cells did not reveal any common signal that could be responsible for the "erythroid promoter."