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The Great Green Wall Initiative (GGWI) has an overall objective of fighting desert encroachment through proven practices of sustainable management of land, and the reinforcement and protection of natural resources and systems of production and transformation, while also ensuring socio-economic development of local communities through multi-purpose activity platforms. The activities described in the present study are designed to accomplish several goals: (1) generate wealth, (2) strengthen access to basic social services, (3) manage the transition to a green economy as a means of creating suitable conditions for the emergence of rural production centers, (4) integrate sustainable development in order to eradicate poverty and food insecurity, and (5) strengthen adaptation and resilience capacities of local populations. The present study was undertaken on the basis of a wide variety of available publications and documentation, including articles and scientific papers, thesis, meeting summaries and reports, concerning the implementation of the Great Green Wall Initiative/GGWI in Senegal.

Cystic fibrosis is a common, heriditary disease resulting from mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Airway transfer of the CFTR gene is a potential strategy to treat or prevent the lung pathology that is the main cause of morbidity and mortality. Among the vectors used for gene therapy, adenoviruses have shown their ability to transfer the CFTR gene to respiratory epithelial cells, using either instillation or nebulization. Our objective was to characterize the lung deposition of aerosolized adenovirus by quantitative radioisotopic imaging, the only noninvasive technique allowing in vivo quantitation of inhaled drugs. We first labeled an adenovirus expressing human CFTR with the gamma-emitting radioisotope, technetium 99m (99mTc), and determined the best labeling conditions to allow preservation of virus bioactivity. We then administered the radioaerosol to baboons, determined lung regional deposition of 99mTc-labeled adenovirus, and compared the expression of CFTR transcripts 3 and 21 days after inhalation. The expression of vector-encoded mRNA ranged from 4 to 22% with respect to the endogenous CFTR mRNA depending on the lung segments. Moreover, we have developed a model using 99mTc-DTPA (diethylenetriamine pentaacetic acid), which can be used, as an alternative to adenovirus, to determine the profile of lung deposition of the vector. This study demonstrates that scintigraphy is a useful technique to achieve optimization of gene administration to the airways.

Ad CFTR, a replication-deficient adenovirus expressing the human cystic fibrosis transmembrane conductance regulator (CFTR), was administered by aerosolization in a single escalating dose to three pairs (cohorts) of cystic fibrosis (CF) patients. Buffer only was administered to the nose and lungs 9-14 days before nasal instillation of virus followed the day after by aerosolization of Ad CFTR to the lung. Nasal doses (defined in terms of viral plaque forming units, pfu) were 10(5), 10(7), and 4 x 10(8), whereas aerosolized doses were 10(7), 10(8), 5.4 x 10(8) for each cohort, respectively. No acute toxic effects were observed in the first 4 weeks after virus treatment. Shedding of infectious Ad CFTR was never detected, whereas detection of vector DNA sequences and CFTR expression demonstrated DNA transfer to the nose and airways of patients. No significant deviations in immunological and inflammatory parameters were observed in serum and in bronchoalveolar lavage (BAL). Importantly, for all patients, the serum anti-adenovirus antibody levels did not change significantly from baseline and no antibodies against adenovirus were found in BAL.

At present, it is conceivable that gene therapy of the cystic fibrosis airway epithelium is possible using the direct transfer of a functional human cystic fibrosis transmembrane conductance regulator (CFTR) gene to a wide variety of patients' tracheo-bronchial cells. Here we describe a novel approach (aerosolization) to deliver a replication-deficient adenovirus carrying the CFTR gene (Ad.CFTR) to the airways. Results obtained in vitro and in Rhesus monkeys suggest that the delivery of recombinant adenovirus as an aerosol is feasible and is not associated with severe toxicity after single or double administration depending on the Ad.CFTR dose. This study supports the concept of aerosolization as a delivery method for adenovirus-mediated lung gene therapy.

The pBR322 plasmid containing the sequence encoding β-lactamase, the enzyme conferring resistance to ampicillin, was encapsulated in liposomes of different phospholipid composition and incubated with synchronized cells. In mitotic cells as compared to cells synchronized in G 1 , twice as many exogeneous DNA molecules were found associated with the cell nuclear DNA, when fluid, neutral liposomes were used. These liposomes are taken up by the cells mainly via endocytosis. When fluid, negatively charged liposomes were used as carriers about the same number of exogeneous DNA molecules were found associated with the nuclear DNA both in mitotic and in G 1 -synchronized cells. The efficiency for gene transfer of liposomes entering the cells by different mechanisms was further studied and expressed both by the fraction of the radioactive plasmid associated with the nuclear DNA and by the level of the β-lactamase activity detected in the transfected cells. It appears that liposomes entering the cells mainly via an energy-dependent mechanism are more efficient for this type of DNA transfer.

Fluorescein-substituted lectins, which can be used to visualize cell surface glycoconjugates, are shown to be usable in the quantitative determination of the number of receptor sites and of their association constant. The fluorescence measurements of the fluorescein-substituted lectins released from the cell surface with the related inhibitor, give quantitative data in a large range of fluorescein-substituted lectin concentration (0.1 to 100 microgram/ml). Using fluorescein-substituted concanavalin A or [3H]acetyl-concanavalin A, it was found that baby hamster kidney cells (BHK 21, wild-type) bind 10 +/- 2 x 10(6) lectin molecules per cell with an apparent association constant of 1.8 or 1.7 x 10(6) 1 x mol-1, respectively. Using the fluoresceinyl and [3H]acetyl-substituted wheat germ agglutinin, we found 40 +/- 5 x 10(6) sites per cell with an apparent binding constant of 1 and 1.3 +/- 0.3 x 10(6) 1 x mol-1, respectively. When fluorescein-substituted succinyl wheat germ agglutinin was used instead of the unsuccinylated wheat germ agglutinin derivatives, the number of binding sites was reduced 7 times, while the binding constant was very slightly lowered. Concanavalin A derivatives gave monotonic Scatchard plots; on the opposite, wheat germ agglutinin derivatives gave biphasic Scatchard plots suggesting that wheat germ agglutinin binds to two classes of receptors.

The specific binding of N-acetylneuraminic acid to wheat-germ agglutinin is based on configurational similarities between N-acetylneuraminic acid and N-acetylglucosamine. The N-acetamido group and an adjacent hydroxyl group, both in an equatorial position are shown to be the main determinants. The N-acetylneuraminic acid - wheat-germ agglutinin interaction is increased by the removal of the last two carbons Cs and C9. The interaction between wheat-germ agglutinin and glycoconjugates containing N-acetylneuraminic acid is shown to be dependent on a charge effect and on an avidity effect. Succinylated wheat-germ agglutinin which is negatively charged at physiological pH, in contrast with wheat-germ agglutinin which is positively charged, does not bind cell surface glycoconjugates containing N-acetylneuraminic acid but does bind cell surface glycoconjugates containing N-acetylglucosamine. The use of wheat-germ agglutinin and of SUCcinylated wheat-germ agglutinin leads to the determination of the number of cell surface receptors containing N-acetylneuramipic acid

Resume Les glycoconjugues membranaires des cellules de rein d'hamster nouveau-ne (BHK 21 C13) et des quatre lignees resistantes a la ricine (toxine des graines de Ricinus communis ) ont ete etudies en utilisant la ricine marquee a l'iode 125, et des lectines substituees par la fluoresceine: la limuline (lectine du Limule, Limulus polyphemus ) qui est affine du dioside NeuAc-α2-3(6)-GalNAc, la lectine du germe de ble (WGA, Triticum vulgare ) qui fixe les oligosides contenant un residu de NeuAc ou un residu de GlcNAc en position terminale ou subterminale, et la lectine du germe de ble succinylee qui reconnait les residus de GlcNAc mais ne fixe pas ceux de NeuAc. Des differences importantes ont pu etre mises en evidence en ce qui concerne le nombre d'osides accessibles a la surface des cellules de la lignee 21 C 13 et des lignees resistantes a la ricine. Les resultats sont discutes sur la base des structures glucidiques connues et de la specificite des lectines et de la ricine. Cette etude a permis de mettre en evidence des differences d'une lignee a l'autre, soit au niveau des glycopeptides a asparagine soit au niveau des glycopeptides a hydroxy amino-acides.

During the past few years, a very large number of investigations was devoted to the dynamics proper- ties of cell membranes. Dynamic studies of lipid bilayers were done either by the use of spin label or fluo- rescence depolarization techniques. Amongst various fluorescent probes, 1,6-diphenyl-1,3,5-hexatriene [1] was the most widely used. DPH is easily introduced into membrane bilayers from aqueous dispersions, in which it is not fluorescent [2]. On the basis of phase fluorometric measurements in a homogeneous refer- ence oil, this probe was reported to exhibit a single exponential decay of the emission and a linear Perrin plot [3] e.g., fluorescence intensity and lifetime are in a constant ratio when temperature changes [4]. These results were confirmed by direct measurements of the decay of both intensity and emission anisotropy of DPH in a different oil, using a pulse fluorimeter [5]. However, very recently, nanosecond pulse fluo- rescence studies of DPH incorporated into L-a- dimyristoyl lecithin vesicles [6] and into DL-a- dipalrnitoylphosphatidyl choline vesicles [7] showed that the decay of the total fluorescent emission and the decay of the emission anisotropy could not be described adequately in terms of single exponential decay laws. Therefore, when DPH is embedded in vesicles, the Perrin relationship is no longer valid, and steady state polarization measurements cannot be interpreted in terms of microviscosity. The complex decay could be interpreted either in terms of microheterogeneity of sites for the probe in + To whom correspondence should be

The physicochemical and binding properties of succinylated wheat germ agglutinin are described in comparison with these of unmodified wheat germ agglutinin. Succinylated wheat germ agglutinin is an acidic protein with a pI of 4.0 +/- 0.2 while the native lectin is basic, pI of 8.5. The solubility of succinylated wheat germ agglutinin is about 100 times higher than that of the unmodified lectin at neutral pH. Both lectins are dimeric at pH down to 5, and the dissociation occurs at pH lower than 4.5. The binding of oligosaccharides of N-acetylglucosamine to both lectins is very similar on the basis of fluorescence and phosphorescence studies. The minimal concentration required to agglutinate rabbit red blood cells is about 2 microgram/ml with both lectins and the concentrations of N-acetylglucosamine and di-N-acetylchitobiose which inhibit agglutination are similar with both lectins. The number of succinylated wheat germ agglutinin molecules bound to the surface of mouse thymocytes was ten times lower than that of the unmodified lectin although the apparent binding constant was only slightly different between the two lectins. The dramatic decrease of the apparent number of cell surface receptors upon succinylation of the lectin is discussed on the basis of the decrease of the isoelectric point and of the acidic properties of the cell surface.

Liposomes have been used to introduce drugs (Poste and Papahadjopoulos, 1976), enzymes (Gregoriadis and Buckland, 1973), mRNA (Dimitriadis, 1978), viruses (Lonberg-Holm et al., 1976; Wilson et al., 1977), and allosteric effectors (Nicolau and Gersonde, 1979; Gersonde and Nicolau, 1979) in a number of different cells. Recently, chromosomes have been entrapped in liposomes and transferred to cells (Mukherjee et al., 1978) and DNA has been introduced into bacterial cells (Fraley et al., 1979) and into plant cells (Lurquin, 1979). Also the expression of the tetracycline resistance gene (TetR) has been observed in E. coli after liposome-mediated transfer of the plasmid pBR322 to these cells (Fraley et al., 1979). Fraley et al. (1981) have used liposomes to encapsulate with high efficiency DNA isolated from SV40 virus. Infection of a permissive monkey cell line with these DNA-loaded liposomes resulted in the expression of the SV40 DNA encapsulated in liposomes with efficiencies comparable to the calcium phosphate method. Wong et al. (1980) isolated, from E. coli a restriction fragment, 875 bp, which encodes for a β-lactamase activity, and entrapped it in liposomes. Incubation of the DNA-loaded liposomes with avian, murine and human cells resulted in the uptake by the cells of the DNA and the expression of a β-lactamase activity as determined by spectroscopic and microbiological methods. Recently, Schaeffer-Ridder et al. (1981) transformed mouse LMTK cells with the liposome-encapsulated thymidine kinase gene and Nicolau and Rottem (1981) transformed M. capriolum with the pBR322 plasmid encapsulated in liposomes, conferring thus tetracycline resistance to this tetracycline sensitive organism. We will discuss here several aspects of the transformation of eukaryotic cells with liposome encapsulated genetic material.