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The Department of Entomology
The Robert H. Smith Faculty of Agriculture, Food and Environment
The Hebrew University of Jerusalem
P.O Box 12, Rehovot 76100, ISRAEL

Tel: 08-9489223 
Fax: 08-9366768
Email: orlytal@savion.huji.ac.il

Publications

2019
Merzendorfer, H. ; Cohen, E. Chitin/Chitosan: Versatile Ecological, Industrial, and Biomedical Applications. In Extracellular Sugar-Based Biopolymers Matrices; Cohen, E. ; Merzendorfer, H., Ed. Extracellular Sugar-Based Biopolymers Matrices; Springer International Publishing: Cham, 2019; pp. 541–624. Publisher's VersionAbstract
Chitin is a linear polysaccharide of N-acetylglucosamine, which is highly abundant in nature and mainly produced by marine crustaceans. Chitosan is obtained by hydrolytic deacetylation. Both polysaccharides are renewable resources, simply and cost-effectively extracted from waste material of fish industry, mainly crab and shrimp shells. Research over the past five decades has revealed that chitosan, in particular, possesses unique and useful characteristics such as chemical versatility, polyelectrolyte properties, gel- and film-forming ability, high adsorption capacity, antimicrobial and antioxidative properties, low toxicity, and biocompatibility and biodegradability features. A plethora of chemical chitosan derivatives have been synthesized yielding improved materials with suggested or effective applications in water treatment, biosensor engineering, agriculture, food processing and storage, textile additives, cosmetics fabrication, and in veterinary and human medicine. The number of studies in this research field has exploded particularly during the last two decades. Here, we review recent advances in utilizing chitosan and chitosan derivatives in different technical, agricultural, and biomedical fields.
Merzendorfer, H. ; Cohen, E. Chitin/Chitosan: Versatile Ecological, Industrial, and Biomedical Applications. In Extracellular Sugar-Based Biopolymers Matrices; Cohen, E. ; Merzendorfer, H., Ed. Extracellular Sugar-Based Biopolymers Matrices; Springer International Publishing: Cham, 2019; pp. 541–624. Publisher's VersionAbstract
Chitin is a linear polysaccharide of N-acetylglucosamine, which is highly abundant in nature and mainly produced by marine crustaceans. Chitosan is obtained by hydrolytic deacetylation. Both polysaccharides are renewable resources, simply and cost-effectively extracted from waste material of fish industry, mainly crab and shrimp shells. Research over the past five decades has revealed that chitosan, in particular, possesses unique and useful characteristics such as chemical versatility, polyelectrolyte properties, gel- and film-forming ability, high adsorption capacity, antimicrobial and antioxidative properties, low toxicity, and biocompatibility and biodegradability features. A plethora of chemical chitosan derivatives have been synthesized yielding improved materials with suggested or effective applications in water treatment, biosensor engineering, agriculture, food processing and storage, textile additives, cosmetics fabrication, and in veterinary and human medicine. The number of studies in this research field has exploded particularly during the last two decades. Here, we review recent advances in utilizing chitosan and chitosan derivatives in different technical, agricultural, and biomedical fields.
2016
Avila, F. W. ; Sánchez-López, J. A. ; McGlaughon, J. L. ; Raman, S. ; Wolfner, M. F. ; Heifetz, Y. Nature and Functions of Glands and Ducts in the Drosophila Reproductive Tract. In Extracellular Composite Matrices in Arthropods; Cohen, E. ; Moussian, B., Ed. Extracellular Composite Matrices in Arthropods; Springer International Publishing: Cham, 2016; pp. 411–444. Publisher's VersionAbstract
Successful reproduction requires interactions between males and females at many levels: the organisms, their cells (the gametes), and their molecules. Among the latter, secreted products of male and female reproductive glands are especially important. These molecules are particularly well understood in Drosophila melanogaster, because of this insect's excellent molecular genetic tools. Here, we discuss the biology of Drosophila reproductive glands, including their development, structure, and secreted products. These glands include important secretory centers, tissues that play roles in gamete maintenance and perhaps in modification, and organs that mediate dynamic transfer of gametes and molecules, and gamete support and/or discharge. Components of seminal fluid produced by male reproductive glands enter the female during mating. There, they interact with female proteins, neurons, and pathways to convert the female from a ``poised'' pre-mated state to an active post-mating state. This mated state is characterized by high levels of egg production, by sperm storage, and by post-mating behaviors related to re-mating, activity, and feeding. Female reproductive gland secretions include additional molecules important for sperm survival or egg transit. The interplay and coordination between male- and female-derived molecules is an area of intense study. Its conclusions are relevant to understanding reproduction in insects and, more broadly, in all animals, and as well as to questions about chemical communication, hormone biology and evolution.
Ya'kobovitz, M. K. ; Butters, T. D. ; Cohen, E. Inhibition of α-glucosidase activity by N-deoxynojirimycin analogs in several insect phloem sap feeders. Insect Science 2016, 23, 59-67. Publisher's VersionAbstract
Abstract Secondary metabolites and synthetic iminosugars that structurally resemble monosaccharides are potent inhibitors of α-glucosidase activity. The enzyme is core in cleaving sucrose in phloem feeding insects and it also plays a crucial role of reducing osmotic stress via the formation of oligosaccharides. Inhibition of hydrolysis by iminosugars should result in nutritional deficiencies and/or disruption of normal osmoregulation. Deoxynojirimycin (DNJ) and 2 N-alkylated analogs [N-butyl DNJ (NB-DNJ) and N-nonyl DNJ (NN-DNJ)] were the major iminosugars used throughout the study. The extensive experiments conducted with α-glucosidase of the whitefly Bemisia tabaci indicated the competitive nature of inhibition and that the hydrophilic DNJ is a potent inhibitor in comparison to the more hydrophobic NB-DNJ and NN-DNJ compounds. The same inhibitory pattern was observed with the psyllid Cacopsylla bidens α-glucosidase. In contrast to the above pattern, enzymes of the aphids, Myzus persicae and Aphis gossypii were more sensitive to the hydrophobic iminosugars as compared to DNJ. In vivo experiments in which adult B. tabaci were fed dietary iminosugars, show that the hydrophilic DNJ was far less toxic than the lipophilic NB-DNJ and NN-DNJ. It is proposed that this pattern is attributed to the better accessibility of the hydrophobic NN-DNJ to the α-glucosidase membrane-bound compartment in the midgut. Based on the inhibitory effects of certain polyhydroxy N-alkylated iminosugars, α-glucosidase of phloem feeding hemipterans could serve as an attractive target site for developing novel pest control agents.